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Sample records for barrier si detector

  1. Microstructure, electrical, and optical properties of evaporated PtSi/p-Si(100) Schottky barriers as high quantum efficient infrared detectors

    International Nuclear Information System (INIS)

    Wu Jihhuah; Chang Rongsen; Horng Gwoji

    2004-01-01

    The effects of the microstructure and the electrical and optical properties on the formation at highly efficient infrared PtSi Schottky barrier detectors (SBD) have been studied in detail. Two- to twelve-nanometer-thick PtSi films were grown by evaporation at temperature ranging from 350 to 550 deg. C. The electron diffraction patterns indicate the existence of both the (11-bar0) and (12-bar1) orientations when PtSi films formed at 350 deg. C. However, the diffraction patterns show only the (12-bar1) orientation when the PtSi films are formed at 450 deg. C or above. The electrical barrier height of the Schottky barrier detector that formed at 350 deg. C was about 20 meV higher than that formed at 450 deg. C or above. The grain size and the film thickness had a negligible effect on the electrical barrier height. However, the optical performance was strongly dependent on the film thickness and the growth conditions. The 350 deg. C PtSi film showed increased quantum efficiency as the film thickness decreased. The optimal thickness that provided the highest responsivity was 2 nm. On the other hand, the optimal thickness shifted to 8 nm for PtSi film formed at 450 deg. C or above. These results indicate that the quantum efficiency of a detector can be improved if the PtSi film has an orientation at (12-bar1), a larger grain size, and an optimal film thickness

  2. Barrier Infrared Detector (BIRD)

    Data.gov (United States)

    National Aeronautics and Space Administration — A recent breakthrough in MWIR detector design, has resulted in a high operating temperature (HOT) barrier infrared detector (BIRD) that is capable of spectral...

  3. Experimental investigation of energy resolution in a semiconductor detector (surface barrier and Si (Li) detector) in the detection of protons

    International Nuclear Information System (INIS)

    Nordborg, C.

    1974-05-01

    The action of electronic effects on the energy resolution of the detector is investigated. The results are applicable not only to protons but also to heavier charged particles. It should be possible to reach a resolution of about 6 to 7 keV for 10 MeV protons with electronic detectors. Magnetic spectrometers could achieve a resolution of 2 to 3 keV. It is convenient to use Peltier elements for cooling semiconductor spectrometers. (Auth.)

  4. Detectors for proton counting. Si-APD and scintillation detectors

    International Nuclear Information System (INIS)

    Kishimoto, Shunji

    2008-01-01

    Increased intensity of synchrotron radiation requests users to prepare photon pulse detectors having higher counting rates. As detectors for photon counting, silicon-avalanche photodiode (Si-APD) and scintillation detectors were chosen for the fifth series of detectors. Principle of photon detection by pulse and need of amplification function of the detector were described. Structure and working principle, high counting rate measurement system, bunch of electrons vs. counting rate, application example of NMR time spectroscopy measurement and comments for users were described for the Si-APD detector. Structure of scintillator and photomultiplier tube, characteristics of scintillator and performance of detector were shown for the NaI detector. Future development of photon pulse detectors was discussed. (T. Tanaka)

  5. Application of pulse shape discrimination in Si detector for fission ...

    Indian Academy of Sciences (India)

    Pulse shape discrimination (PSD) with totally depleted transmission type Si surface barrier detector in reverse mount has been investigated to identify fission fragments in the presence of elastic background in heavy ion-induced fission reactions by both numerical simulation and experimental studies. The PSD method is ...

  6. Si(Li) X-ray detector

    International Nuclear Information System (INIS)

    Yuan Xianglin; Li Zhiyong; Hong Xiuse

    1990-08-01

    The fabrication technology of the 10∼80 mm 2 Si(Li) X-ray detectors are described and some problems concerning technology and measurement are discussed. The specifications of the detectors are shown as well. The Si(Li) X-ray detector is a kind of low energy X-ray detectors. Owing to very high energy resolution, fine linearity and high detection efficiency in the range of low energy X-rays, it is widely used in the fields of nuclear physics, medicine, geology and environmental protection, etc,. It is also a kernel component for the scanning electron microscope and X-ray fluorescence analysis systems

  7. Sub-barrier fusion of Si+Si systems

    Science.gov (United States)

    Colucci, G.; Montagnoli, G.; Stefanini, A. M.; Bourgin, D.; Čolović, P.; Corradi, L.; Courtin, S.; Faggian, M.; Fioretto, E.; Galtarossa, F.; Goasduff, A.; Haas, F.; Mazzocco, M.; Scarlassara, F.; Stefanini, C.; Strano, E.; Urbani, M.; Szilner, S.; Zhang, G. L.

    2017-11-01

    The near- and sub-barrier fusion excitation function has been measured for the system 30Si+30Si at the Laboratori Nazionali di Legnaro of INFN, using the 30Si beam of the XTU Tandem accelerator in the energy range 47 - 90 MeV. A set-up based on a beam electrostatic deflector was used for detecting fusion evaporation residues. The measured cross sections have been compared to previous data on 28Si+28Si and Coupled Channels (CC) calculations have been performed using M3Y+repulsion and Woods-Saxon potentials, where the lowlying 2+ and 3- excitations have been included. A weak imaginary potential was found to be necessary to reproduce the low energy 28Si+28Si data. This probably simulates the effect of the oblate deformation of this nucleus. On the contrary, 30Si is a spherical nucleus, 30Si+30Si is nicely fit by CC calculations and no imaginary potential is needed. For this system, no maximum shows up for the astrophysical S-factor so that we have no evidence for hindrance, as confirmed by the comparison with CC calculations. The logarithmic derivative of the two symmetric systems highlights their different low energy trend. A difference can also be noted in the two barrier distributions, where the high-energy peak present in 28Si+28Si is not observed for 30Si+30Si, probably due to the weaker couplings in last case.

  8. Sub-barrier fusion of Si+Si systems

    Directory of Open Access Journals (Sweden)

    Colucci G.

    2017-01-01

    Full Text Available The near- and sub-barrier fusion excitation function has been measured for the system 30Si+30Si at the Laboratori Nazionali di Legnaro of INFN, using the 30Si beam of the XTU Tandem accelerator in the energy range 47 - 90 MeV. A set-up based on a beam electrostatic deflector was used for detecting fusion evaporation residues. The measured cross sections have been compared to previous data on 28Si+28Si and Coupled Channels (CC calculations have been performed using M3Y+repulsion and Woods-Saxon potentials, where the lowlying 2+ and 3− excitations have been included. A weak imaginary potential was found to be necessary to reproduce the low energy 28Si+28Si data. This probably simulates the effect of the oblate deformation of this nucleus. On the contrary, 30Si is a spherical nucleus, 30Si+30Si is nicely fit by CC calculations and no imaginary potential is needed. For this system, no maximum shows up for the astrophysical S-factor so that we have no evidence for hindrance, as confirmed by the comparison with CC calculations. The logarithmic derivative of the two symmetric systems highlights their different low energy trend. A difference can also be noted in the two barrier distributions, where the high-energy peak present in 28Si+28Si is not observed for 30Si+30Si, probably due to the weaker couplings in last case.

  9. A surface barrier detector for simultaneous detection of α and β particles

    International Nuclear Information System (INIS)

    Shiraishi, Fumio

    1981-01-01

    Semiconductor detectors are indispensable as the solid detectors with high energy resolution. Ge detectors are used for gamma-ray spectroscopy and its applied fields, while Si detectors are used as the detectors for charged particles such as α and β rays and low energy X-ray. In this paper, it is reported that the Si detector developed in the author's laboratory is suitable to monitor very weak radioactivity. The Si detector is a rectifier, but in order to capture radiation, it has large area and increased thickness, and a window is provided for incident charged particles. The Si detectors are classified into three types according to the manufacturing methods, namely surface barrier type, PN joint type and Li drift type. The Si detector introduced here is of surface barrier type, but it is characterized by the use of P-type Si with superhigh purity. The method of manufacturing this detector, its specifications and characteristics are described. Because of the surface barrier type, it can be produced simply in short time, and the yield of products is good. The stability is good, and the sensitivity is high, accordingly very weak radioactivity can be measured. As the examples of measurements, the results of uranium ore and fertilizer on the market are compared. Also the utilization as surface contamination meters is explained. (Kako, I.)

  10. Plasma measurements with surface barrier detectors

    International Nuclear Information System (INIS)

    Futch, A.H. Jr.; Bradley, A.E.

    1969-01-01

    A surface barrier detector system for measuring the loss rate of protons from a hydrogen plasma and their energy spectrum is described. A full width at half maximum (FWHM) resolution of 1.4 keV for 15-keV hydrogen atoms was obtained using a selected detector having a sensitive area of 3 mm 2 and a depletion depth of 700 microns

  11. Electronics for the Si detectors in APEX

    International Nuclear Information System (INIS)

    Wilt, P.R.; Betts, R.R.; Freer, M.

    1994-01-01

    APEX (ATLAS Positron EXperiment), a collaborative effort of ANL, FSU, MSU/NSCL, Princeton, Queen's, Rochester, Washington and Yale, is an experiment to study positron and electron production in very heavy ion collisions. The electrons and positrons are detected with two detector arrays, each consisting of 216 1 mm thick Si PIN diodes, and their energy and time-of-flight are measured. The number of detectors and limited space made it necessary to develop a system that could efficiently process and transfer signals from the detectors to the charge sensing ADC's and data readout electronics as well as monitor the condition of the detectors. The discussion will cover the electronics designed for the Si detectors, including the charge amplifier, ''Mother board'' for the charge amplifiers, 8 channel Shaper, 16 channel Constant Fraction Discriminator (CFD), 16 channel Peak-to-FERA (PTF) and the integration of the CFD and PTF with Charge sensing ADC's. Function and performance of the individual modules as well as the system as a whole will be discussed

  12. New Type Far IR and THz Schottky Barrier Detectors for Scientific and Civil Application

    Directory of Open Access Journals (Sweden)

    V. G. Ivanov

    2011-01-01

    Full Text Available The results of an experimental investigation into a new type of VLWIR detector based on hot electron gas emission and architecture of the detector are presented and discussed. The detectors (further referred to as HEGED take advantage of the thermionic emission current change effect in a semiconductor diode with a Schottky barrier (SB as a result of the direct transfer of the absorbed radiation energy to the system of electronic gas in the quasimetallic layer of the barrier. The possibility of detecting radiation having the energy of quantums less than the height of the Schottky diode potential barrier and of obtaining a substantial improvement of a cutoff wavelength to VLWIR of the PtSi/Si detector has been demonstrated. The complementary contribution of two physical mechanisms of emanation detection—“quantum” and hot electrons gas emission—has allowed the creation of a superwideband IR detector using standard silicon technology.

  13. Schottky barrier CdTe(Cl) detectors for planetary missions

    International Nuclear Information System (INIS)

    Eisen, Yosef; Floyd, Samuel

    2002-01-01

    Schottky barrier cadmium telluride (CdTe) radiation detectors of dimensions 2mm x 2mm x 1mm and segmented monolithic 3cm x 3 cm x 1mm are under study at GSFC for future NASA planetary instruments. These instruments will perform x-ray fluorescence spectrometry of the surface and monitor the solar x-ray flux spectrum, the excitation source for the characteristic x-rays emitted from the planetary body. The Near Earth Asteroid Rendezvous (NEAR) mission is the most recent example of such a remote sensing technique. Its x-ray fluorescence detectors were gas proportional counters with a back up Si PIN solar monitor. Analysis of NEAR data has shown the necessity to develop a solar x-ray detector with efficiency extending to 30keV. Proportional counters and Si diodes have low sensitivity above 9keV. Our 2mm x 2mm x 1mm CdTe operating at -30 degree sign C possesses an energy resolution of 250eV FWHM for 55Fe with unit efficiency to up to 30keV. This is an excellent candidate for a solar monitor. Another ramification of the NEAR data is a need to develop a large area detector system, 20-30 cm2, with cosmic ray charged particle rejection, for measuring the characteristic radiation. A 3cm x 3cm x 1mm Schottky CdTe segmented monolithic detector is under investigation for this purpose. A tiling of 2-3 such detectors will result in the desired area. The favorable characteristics of Schottky CdTe detectors, the system design complexities when using CdTe and its adaptation to future missions will be discussed

  14. Characterization of a SiC MIS Schottky diode as RBS particle detector

    Science.gov (United States)

    Kaufmann, I. R.; Pick, A. C.; Pereira, M. B.; Boudinov, H. I.

    2018-02-01

    A 4H-SiC Schottky diode was investigated as a particle detector for Rutherford Backscattering Spectroscopy (RBS) experiment. The device was fabricated on a commercial 4H-SiC epitaxial n-type layer grown onto a 4H-SiC n+ type substrate wafer doped with nitrogen. Hafnium oxide with thickness of 1 nm was deposited by Atomic Layer Deposition and 10 nm of Ni were deposited by sputtering to form the Ni/HfO2/4H-SiC MIS Schottky structure. Current-Voltage curves with variable temperature were measured to extract the real Schottky Barrier Height (0.32 V) and ideality factor values (1.15). Reverse current and Capacitance-Voltage measurements were performed on the 4H-SiC detector and compared to a commercial Si barrier detector acquired from ORTEC. RBS data for four alpha energies (1, 1.5, 2 and 2.5 MeV) were collected from an Au/Si sample using the fabricated SiC and the commercial Si detectors simultaneously. The energy resolution for the fabricated detector was estimated to be between 75 and 80 keV.

  15. Beta dosimetry with surface barrier detectors

    International Nuclear Information System (INIS)

    Heinzelmann, M.F.M.; Schuren, H.; Dreesen, K.

    1980-01-01

    A small dosimeter to measure the dose rate due to β-radiation in an energy independent fashion is described in detail. A surface barrier semi-conductor detector is used whose thickness of sensitive layer is changed by varying the detector voltage. The integral count rate can then be determined as a function of applied voltage and discrimination thresholds. The integral count rate can be related to β dose rate in an energy independent fashion only for a time constant of 0.25 μs. However, the use of a single channel analyzer permits an energy-independent determination of the β-dose rate with 0.25 or 0.5 μs time constants. The sensitivity of the device as a function of dose rate is investigation up to 600 rad/hr. Furthermore, the sensitivity of the device at a constant dose rate was shown to be uniform up to a dose of 50,000 rads. (UK)

  16. HgCdTe photovoltaic detectors on Si substrates

    International Nuclear Information System (INIS)

    Zanio, K.R.; Bean, R.C.

    1988-01-01

    HgCdTe photovoltaic detectors have been fabricated on Si substrates through intermediate CdTe/GaAs layers. Encapsulation of the GaAs between the CdTe and Si prevents unintentional doping of the HgCdTe by Ga and As. Uniform epitaxial GaAs is grown on three inch diameter Si substrates. Detectors on such large area Si substrates will offer hybrid focal plane arrays whose dimensions are not limited by the difference between the coefficients of thermal expansion of the Si signal processor and the substrate for the HgCdTe detector array. The growth of HgCdTe detectors on the Si signal processors for monolithic focal plane arrays is also considered. 40 references

  17. Correlation of DT and DD fusion neutron damage in silicon surface barrier detector

    International Nuclear Information System (INIS)

    Iida, Toshiyuki; Sueyoshi, Yasuhiro; Sunarno; Takahashi, Akito

    1994-01-01

    In order to examine the correlation of DT and DD fusion neutron damage in Si, a silicon surface barrier detector (Si-SBD) was irradiation with neutrons from a deuteron accelerator. The leakage current increased proportionally with neutron fluence, which determined the neutron damage constant for the Si-SBD. The correlation factor of the DT and DD neutron damage in the Si-SBD was determined from the ratio of the DT and DD neutron damage constants and was found to be 2.3. We also calculated the rate of DT and DD neutron displacement damage for Si by using the TRIM-90 computer program and actual data on neutron reactions in the Si-SBD. The correlation factor of DT and DD neutron damage from the calculation agreed with that from the Si-SBD irradiation experiment. (author)

  18. Multi-angle gas and Si detector particle telescope

    International Nuclear Information System (INIS)

    McDonald, R.J.; Sobotka, L.G.; Wozniak, G.J.

    1984-01-01

    A simple gas ΔE and multiple Si E detector telescope (called a WEDGE detector) has been constructed, which is particularly suitable for angular distribution studies of light ion emission from fragments following heavy ion reactions. This inexpensive detector was designed to have a low detection threshold, large dynamic range and constant ΔE path length. The detector has been used in studies of complex fragment emission (typically 2 < Z < 10) following compound nucleus and deep-inelastic heavy ion reactions

  19. Two-dimensional position sensitive Si(Li) detector

    International Nuclear Information System (INIS)

    Walton, J.T.; Hubbard, G.S.; Haller, E.E.; Sommer, H.A.

    1978-11-01

    Circular, large-area two-dimensional Si(Li) position sensitive detectors have been fabricated. The detectors employ a thin lithium-diffused n + resisitive layer for one contact and a boron implanted p + resistive layer for the second contact. A position resolution of the order of 100 μm is indicated

  20. A TWO-DIMENSIONAL POSITION SENSITIVE SI(LI) DETECTOR

    Energy Technology Data Exchange (ETDEWEB)

    Walton, Jack T.; Hubbard, G. Scott; Haller, Eugene E.; Sommer, Heinrich A.

    1978-11-01

    Circular, large-area two-dimensional Si(Li) position sensitive detectors have been fabricated. The detectors employ a thin lithium-diffused n{sup +} resistive layer for one contact and a boron implanted p{sup +} resistive layer for the second contact. A position resolution of the order of 100 {micro}m is indicated.

  1. Silicon surface barrier detectors used for liquid hydrogen density measurement

    Science.gov (United States)

    James, D. T.; Milam, J. K.; Winslett, H. B.

    1968-01-01

    Multichannel system employing a radioisotope radiation source, strontium-90, radiation detector, and a silicon surface barrier detector, measures the local density of liquid hydrogen at various levels in a storage tank. The instrument contains electronic equipment for collecting the density information, and a data handling system for processing this information.

  2. The physics and technology of Si and Ge detectors

    International Nuclear Information System (INIS)

    Stab, Lucien

    Semiconductor physics fundamentals are recalled (energy levels in crystalline solids, level population, charge carrier transport) as an introduction to studying NP junction at thermal equilibrium, or reversly biased. The fabrication of semiconductor detectors including surface barrier detectors, implanted junctions, and lithium-drifted semiconductors is discussed [fr

  3. Computer controlled drifting of Si(Li) detectors

    International Nuclear Information System (INIS)

    Landis, D.A.; Wong, Y.K.; Walton, J.T.; Goulding, F.S.

    1989-01-01

    A relatively inexpensive computer-controlled system for performing the drift process used in fabricating Si(Li) detectors is described. The system employs a small computer to monitor the leakage current, applied voltage and temperature on eight individual drift stations. The associated computer program initializes the drift process, monitors the drift progress and then terminates the drift when an operator set drift time has elapsed. The improved control of the drift with this system has been well demonstrated over the past three years in the fabrication of a variety of Si(Li) detectors. A few representative system responses to detector behavior during the drift process are described

  4. Diagnostic x-ray spectra measurements using a silicon surface barrier detector

    International Nuclear Information System (INIS)

    Pani, R.; Laitano, R.F.

    1987-01-01

    A silicon surface barrier detector having a low efficiency for x-ray is used to analyse diagnostic x-ray spectra. This characteristic is advantageous in overcoming experimental problems caused by high fluence rates typical of diagnostic x-ray beams. The pulse height distribution obtained with silicon surface barrier detectors is very different from the true photon spectra because of the presence of escaped Compton photons and the fact that detection efficiency falls abruptly when photon energy increases. A detailed analysis of the spurious effects involved in detection is made by a Monte Carlo method. A stripping procedure is described for implementation on a personal computer. The validity of this method is tested by comparison with experimental results obtained with a Ge detector. The spectra obtained with the Si detector are in fairly good agreement with the analogous spectra measured with a Ge detector. The advantages of using Si as opposed to Ge detectors in x-ray spectrometry are: its simplicity of use, its greater economy for use in routine diagnostic x-ray spectroscopy and the possibility that the stripping procedure can be implemented on a personal computer. (author)

  5. Breakdown of coupling dielectrics for Si microstrip detectors

    International Nuclear Information System (INIS)

    Candelori, A.; Paccagnella, A.; Padova Univ.; Saglimbeni, G.

    1999-01-01

    Double-layer coupling dielectrics for AC-coupled Si microstrip detectors have been electrically characterized in order to determine their performance in a radiation-harsh environment, with a focus on the dielectric breakdown. Two different dielectric technologies have been investigated: SiO 2 /TEOS and SiO 2 /Si 3 N 4 . Dielectrics have been tested by using a negative gate voltage ramp of 0.2 MV/(cm·s). The metal/insulator/Si I-V characteristics show different behaviours depending on the technology. The extrapolated values of the breakdown field for unirradiated devices are significantly higher for SiO 2 /Si 3 N 4 dielectrics, but the data dispersion is lower for SiO 2 /TEOS devices. No significant variation of the breakdown field has been measured after a 10 Mrad (Si) γ irradiation for SiO 2 /Si 3 N 4 dielectrics. Finally, the SiO 2 /Si 3 N 4 DC conduction is enhanced if a positive gate voltage ramp is applied with respect to the negative one, due to the asymmetric conduction of the double-layer dielectric

  6. Hight resolution Si(Li) X ray detector

    International Nuclear Information System (INIS)

    Yuan Xianglin; Huang Naizhang; Lin Maocai; Li Zhiyong

    1985-01-01

    This paper describes the fabrication technology of GL1221 type Si(Li) X ray detector core and the pulse light feedback colded preamplifier fitted on the detector. The energy resolution of the detector system is 165 eV (At 5.89 KeV Mn-K α X ray); the counting rate is 1020 cps, and the electronics noise is 104 eV. The performace of the detector keeps up with the business level of a foreign product of the same kind

  7. Radially dependent photopeak efficiency model for Si(Li) detectors

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, D D [Australian Inst. of Nuclear Science and Engineering, Lucas Heights

    1980-12-15

    A simple five parameter model for the efficiency of a Si(Li) detector has been developed. It was found necessary to include a radially dependent efficiency even for small detectors. The model is an extension of the pioneering work of Hansen et al. but correction factors include more up to date data and explicit equations for the mass attenuation coefficients over a wide range of photons energies. Four of the five parameters needed are generally supplied by most commercial manufacturers of Si(Li) detectors. /sup 54/Mn and /sup 241/Am sources have been used to calibrate a Si(Li) to approx. +-3% over the energy range 3-60 keV.

  8. A new configuration of the Moxon-Rae detector based on Si detector

    International Nuclear Information System (INIS)

    Niu, H.; Hsu, J.Y.; Liang, J.H.; Yuan, L.G.

    2002-01-01

    A new Moxon-Rae detector configuration based on Si semiconductor detector was proposed in this paper. Three γ-ray sources, 137 Cs, 60 Co, and 24 Na, were employed to make actual measurements using the new Moxon-Rae detector. The measured pulse height spectra and detection efficiencies were compared with the EGS4 simulated values. The results revealed that the proposed new configuration is indeed a successful method and specially a useful technique for higher energy γ-ray measurement

  9. Charged particle discrimination with silicon surface barrier detectors

    International Nuclear Information System (INIS)

    Coote, G.E.; Pithie, J.; Vickridge, I.C.

    1996-01-01

    The application for materials analysis of nuclear reactions that give rise to charged particles is a powerful surface analytical and concentration depth profiling technique. Spectra of charged particles, with energies in the range 0.1 to 15 MeV, emitted from materials irradiated with beams of light nuclei such as deuterons are measured with silicon surface barrier detectors. The spectra from multi-elemental materials typically encountered in materials research are usually composed of an overlapping superposition of proton, alpha, and other charged particle spectra. Interpretation of such complex spectra would be simplified if a means were available to electronically discriminate between the detector response to the different kinds of charged particle. We have investigated two methods of discriminating between different types of charged particles. The fast charge pulses from a surface barrier detector have different shapes, depending on the spatial distribution of energy deposition of the incident particle. Fast digitisation of the pulses, followed by digital signal processing provides one avenue for discrimination. A second approach is to use a thin transmission detector in front of a thick detector as a detector telescope. For a given incident energy, different types of charged particles will lose different amounts of energy in the thin detector, providing an alternative means of discrimination. We show that both approaches can provide significant simplification in the interpretation of charged particle spectra in practical situations, and suggest that silicon surface barrier detectors having graded electronic properties could provide improved discrimination compared to the current generation of detectors having homogeneous electronic properties. (author).12 refs., 2 tabs., 28 figs

  10. Automatic α-spectrometry using surface barrier detectors

    International Nuclear Information System (INIS)

    Czarwinski, R.; Loessner, V.; Klucke, H.; Krause, J.

    1984-01-01

    A measurement system has been developed for the routine determination of transuranics in biosamples by α-spectrometry. It employs high-resolution surface-barrier detectors and can be operated automatically by means of an integrated CAMAC system. For 241 Am, the minimum detectable activity is 2.4 x 10 -3 Bq. (author)

  11. Advanced Environmental Barrier Coating Development for SiC/SiC Ceramic Matrix Composites: NASA's Perspectives

    Science.gov (United States)

    Zhu, Dongming

    2016-01-01

    This presentation reviews NASA environmental barrier coating (EBC) system development programs and the coating materials evolutions for protecting the SiC/SiC Ceramic Matrix Composites in order to meet the next generation engine performance requirements. The presentation focuses on several generations of NASA EBC systems, EBC-CMC component system technologies for SiC/SiC ceramic matrix composite combustors and turbine airfoils, highlighting the temperature capability and durability improvements in simulated engine high heat flux, high pressure, high velocity, and with mechanical creep and fatigue loading conditions. The current EBC development emphasis is placed on advanced NASA 2700F candidate environmental barrier coating systems for SiC/SiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. Major technical barriers in developing environmental barrier coating systems, the coating integrations with next generation CMCs having the improved environmental stability, erosion-impact resistance, and long-term fatigue-environment system durability performance are described. The research and development opportunities for advanced turbine airfoil environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling are discussed.

  12. Imaging with SiPMs in noble-gas detectors

    International Nuclear Information System (INIS)

    Yahlali, N; González, K; Fernandes, L M P; Garcia, A N C; Soriano, A

    2013-01-01

    Silicon photomultipliers (SiPMs) are photosensors widely used for imaging in a variety of high energy and nuclear physics experiments. In noble-gas detectors for double-beta decay and dark matter experiments, SiPMs are attractive photosensors for imaging. However they are insensitive to the VUV scintillation emitted by the noble gases (xenon and argon). This difficulty is overcome in the NEXT experiment by coating the SiPMs with tetraphenyl butadiene (TPB) to convert the VUV light into visible light. TPB requires stringent storage and operational conditions to prevent its degradation by environmental agents. The development of UV sensitive SiPMs is thus of utmost interest for experiments using electroluminescence of noble-gas detectors. It is in particular an important issue for a robust and background free ββ0ν experiment with xenon gas aimed by NEXT. The photon detection efficiency (PDE) of UV-enhanced SiPMs provided by Hamamatsu was determined for light in the range 250–500 nm. The PDE of standard SiPMs of the same model (S10362-33-50C), coated and non-coated with TPB, was also determined for comparison. In the UV range 250–350 nm, the PDE of the standard SiPM is shown to decrease strongly, down to about 3%. The UV-enhanced SiPM without window is shown to have the maximum PDE of 44% at 325 nm and 30% at 250 nm. The PDE of the UV-enhanced SiPM with silicon resin window has a similar trend in the UV range, although it is about 30% lower. The TPB-coated SiPM has shown to have about 6 times higher PDE than the non-coated SiPM in the range 250–315 nm. This is however below the performance of the UV-enhanced prototypes in the same wavelength range. Imaging in noble-gas detectors using UV-enhanced SiPMs is discussed.

  13. Isotopic effects in sub-barrier fusion of Si + Si systems

    Science.gov (United States)

    Colucci, G.; Montagnoli, G.; Stefanini, A. M.; Esbensen, H.; Bourgin, D.; Čolović, P.; Corradi, L.; Faggian, M.; Fioretto, E.; Galtarossa, F.; Goasduff, A.; Grebosz, J.; Haas, F.; Mazzocco, M.; Scarlassara, F.; Stefanini, C.; Strano, E.; Szilner, S.; Urbani, M.; Zhang, G. L.

    2018-04-01

    Background: Recent measurements of fusion cross sections for the 28Si+28Si system revealed a rather unsystematic behavior; i.e., they drop faster near the barrier than at lower energies. This was tentatively attributed to the large oblate deformation of 28Si because coupled-channels (CC) calculations largely underestimate the 28Si+28Si cross sections at low energies, unless a weak imaginary potential is applied, probably simulating the deformation. 30Si has no permanent deformation and its low-energy excitations are of a vibrational nature. Previous measurements of this system reached only 4 mb, which is not sufficient to obtain information on effects that should show up at lower energies. Purpose: The aim of the present experiment was twofold: (i) to clarify the underlying fusion dynamics by measuring the symmetric case 30Si+30Si in an energy range from around the Coulomb barrier to deep sub-barrier energies, and (ii) to compare the results with the behavior of 28Si+28Si involving two deformed nuclei. Methods: 30Si beams from the XTU tandem accelerator of the Laboratori Nazionali di Legnaro of the Istituto Nazionale di Fisica Nucleare were used, bombarding thin metallic 30Si targets (50 μ g /cm2) enriched to 99.64 % in mass 30. An electrostatic beam deflector allowed the detection of fusion evaporation residues (ERs) at very forward angles, and angular distributions of ERs were measured. Results: The excitation function of 30Si+30Si was measured down to the level of a few microbarns. It has a regular shape, at variance with the unusual trend of 28Si+28Si . The extracted logarithmic derivative does not reach the LCS limit at low energies, so that no maximum of the S factor shows up. CC calculations were performed including the low-lying 2+ and 3- excitations. Conclusions: Using a Woods-Saxon potential the experimental cross sections at low energies are overpredicted, and this is a clear sign of hindrance, while the calculations performed with a M3Y + repulsion

  14. Ge nanocrystals embedded in ultrathin Si3N4 multilayers with SiO2 barriers

    Science.gov (United States)

    Bahariqushchi, R.; Gundogdu, Sinan; Aydinli, A.

    2017-04-01

    Multilayers of germanium nanocrystals (NCs) embedded in thin films of silicon nitride matrix separated with SiO2 barriers have been fabricated using plasma enhanced chemical vapor deposition (PECVD). SiGeN/SiO2 alternating bilayers have been grown on quartz and Si substrates followed by post annealing in Ar ambient from 600 to 900 °C. High resolution transmission electron microscopy (HRTEM) as well as Raman spectroscopy show good crystallinity of Ge confined to SiGeN layers in samples annealed at 900 °C. Strong compressive stress for SiGeN/SiO2 structures were observed through Raman spectroscopy. Size, as well as NC-NC distance were controlled along the growth direction for multilayer samples by varying the thickness of bilayers. Visible photoluminescence (PL) at 2.3 and 3.1 eV with NC size dependent intensity is observed and possible origin of PL is discussed.

  15. Formation of permeation barriers on ceramic SiC/SiC composites

    International Nuclear Information System (INIS)

    Racault, C.; Fenici, P.

    1996-01-01

    The effectiveness as permeation barriers of the following CVD and PVD (sputtering) coatings has been investigated: TiC+Al 2 O 3 (CVD), SiC(CVD), SiO 2 (CVD), TiN(CVD), TiN(CVD)+TiN(PVD) and SiC(CVD)+Al 2 O 3 (PVD). The substrate material was a SiC/SiC composite, proposed as low activation structural material for fusion applications. Permeation measurements were performed in the temperature range 300-750 K using deuterium at pressures in the range 0.5-150 kPa. A linear dependence of permeation rate on pressure was measured. The efficiency of the coatings as deuterium permeation barriers is discussed in terms of coating microstructure. The best result was obtained with a bilayer of TiN(CVD) (15 μm) +TiN(PVD) (8 μm). (orig.)

  16. Effects induced by high and low intensity laser plasma on SiC Schottky detectors

    Directory of Open Access Journals (Sweden)

    Sciuto Antonella

    2018-01-01

    Full Text Available Silicon-Carbide detectors are extensively employed as diagnostic devices in laser-generated plasma, allowing the simultaneous detection of photons, electrons and ions, when used in time-of-flight configuration. The plasma generated by high intensity laser (1016 W/cm2 producing high energy ions was characterized by SiC detector with a continuous front-electrode, and a very thick active depth, while SiC detector with an Interdigit front-electrode was used to measure the low energy ions of plasma generated by low intensity laser (1010 W/cm2. Information about ion energy, number of charge states, plasma temperature can be accurately obtained. However, laser exposure induces the formation of surface and bulk defects whose concentration increases with increasing the time to plasma exposure. The surface defects consist of clusters with a main size of the order of some microns and they modify the diode barrier height and the efficiency of the detector as checked by alpha spectrometry. The bulk defects, due to the energy loss of detected ions, strongly affect the electrical properties of the device, inducing a relevant increase of the leakage (reverse current and decrease the forward current related to a deactivation of the dopant in the active detector region.

  17. Effects induced by high and low intensity laser plasma on SiC Schottky detectors

    Science.gov (United States)

    Sciuto, Antonella; Torrisi, Lorenzo; Cannavò, Antonino; Mazzillo, Massimo; Calcagno, Lucia

    2018-01-01

    Silicon-Carbide detectors are extensively employed as diagnostic devices in laser-generated plasma, allowing the simultaneous detection of photons, electrons and ions, when used in time-of-flight configuration. The plasma generated by high intensity laser (1016 W/cm2) producing high energy ions was characterized by SiC detector with a continuous front-electrode, and a very thick active depth, while SiC detector with an Interdigit front-electrode was used to measure the low energy ions of plasma generated by low intensity laser (1010 W/cm2). Information about ion energy, number of charge states, plasma temperature can be accurately obtained. However, laser exposure induces the formation of surface and bulk defects whose concentration increases with increasing the time to plasma exposure. The surface defects consist of clusters with a main size of the order of some microns and they modify the diode barrier height and the efficiency of the detector as checked by alpha spectrometry. The bulk defects, due to the energy loss of detected ions, strongly affect the electrical properties of the device, inducing a relevant increase of the leakage (reverse) current and decrease the forward current related to a deactivation of the dopant in the active detector region.

  18. Hybrid organic/inorganic position-sensitive detectors based on PEDOT:PSS/n-Si

    Science.gov (United States)

    Javadi, Mohammad; Gholami, Mahdiyeh; Torbatiyan, Hadis; Abdi, Yaser

    2018-03-01

    Various configurations like p-n junctions, metal-semiconductor Schottky barriers, and metal-oxide-semiconductor structures have been widely used in position-sensitive detectors. In this report, we propose a PEDOT:PSS/n-Si heterojunction as a hybrid organic/inorganic configuration for position-sensitive detectors. The influence of the thickness of the PEDOT:PSS layer, the wavelength of incident light, and the intensity of illumination on the device performance are investigated. The hybrid PSD exhibits very high sensitivity (>100 mV/mm), excellent nonlinearity (0.995) with a response time of heterojunction are very promising for developing a new class of position-sensitive detectors based on the hybrid organic/inorganic junctions.

  19. Detector production for the R3B Si-tracker

    Energy Technology Data Exchange (ETDEWEB)

    Borri, M., E-mail: marcello.borri@liverpool.ac.uk [University of Liverpool, Department of Physics, Oxford Street, Liverpool L69 7ZE (United Kingdom); Lemmon, R. [STFC Daresbury Laboratory, Daresbury, Warrington WA4 4 CE (United Kingdom); Thornhill, J.; Bate, R.; Chartier, M. [University of Liverpool, Department of Physics, Oxford Street, Liverpool L69 7ZE (United Kingdom); Clague, N. [STFC Daresbury Laboratory, Daresbury, Warrington WA4 4 CE (United Kingdom); Herzberg, R.-D. [University of Liverpool, Department of Physics, Oxford Street, Liverpool L69 7ZE (United Kingdom); Labiche, M. [STFC Daresbury Laboratory, Daresbury, Warrington WA4 4 CE (United Kingdom); Lindsay, S.; Nolan, P.; Pearce, F.; Powell, W.; Wells, D. [University of Liverpool, Department of Physics, Oxford Street, Liverpool L69 7ZE (United Kingdom)

    2016-11-11

    R3B is a fixed target experiment which will study reactions with relativistic radioactive beams at FAIR. Its Si-tracker will surround the target volume and it will detect light charged-particles like protons. The detector technology in use consists of double-sided silicon strip sensors wire bonded to the custom made R3B-ASIC. The tracker allows for a maximum of two outer layers and one inner layer. This paper reports on the production of detectors necessary to build the minimum tracking configuration: one inner layer and one outer layer.

  20. SiPM as photon counter for Cherenkov detectors

    International Nuclear Information System (INIS)

    Roy, B.J.; Orth, H.; Schwarz, C.; Wilms, A.; Peters, K.

    2009-01-01

    Silicon photomultipliers (SiPMs) are very new type of photon counting devices that show great promise to be used as detection device in combination with scintillators/ Cherenkov radiators. SiPM is essentially an avalanche photo-diode operated in limited Geiger mode. They have been considered as potential readout devices for DIRC counter of the PANDA detector which is one of the large experiment at FAIR- the new international facility to be built at GSI, Darmstadt. In addition, the potential use of SiPM includes medical diagnosis, fluorescence measurement and high energy physics experiments. The SiPM module is a photon counting device capable of low light level detection. It is essentially an opto-semiconductor device with excellent photon counting capability and possesses great advantages over the conventional PMTs because of low voltage operation and insensitivity to magnetic fields. In many of the high energy physics experiments, the photon sensors are required to operate in high magnetic fields precluding the use of conventional PMTs. This problem can be over come with the use of SiPMs. With this motivation in mind, we have developed a SiPM test facility and have tested several commercially available SiPM for their performance study and comparison with other photon counting devices

  1. Calculation of Si(Li) x-ray detector efficiencies

    International Nuclear Information System (INIS)

    Zaluzec, N.; Holton, R.

    1984-01-01

    The calculation of detector efficiency functions is an important step in the quantitative analysis of x-ray spectra when approached by a standardless technique. In this regard, it becomes essential that the analyst not only model the physical aspects of the absorption and transmission of the various windows present, but also use the most accurate data available for the mass absorption coefficients required in these calculations. The topic of modeling the size and shape of the windows present is beyond the scope of this paper and the authors instead concentrate on the mass absorption coefficients used in the calculations and their implications to efficiency calculations. For the purposes of this paper, the authors consider that the relative detector efficiency function of a conventional Si(Li) detector can be modeled by a simple expression

  2. Passivation layer of Si/Li ionizing radiation detectors

    International Nuclear Information System (INIS)

    Vidra, M.; Reznicek, L.

    1992-01-01

    The proposed passivating layer of Si/Li ionizing radiation detectors ensures a good long-time stability of their volt-ampere characteristics and noise properties. The layer can be applied to protect the detector junction surface in systems cyclically cooled to liquid nitrogen temperature, and in preamplifier feedback optoelectronics to prevent light from entering into the detector. The passivating layer is obtained by evaporating solvent from a cured suspension of boron nitride or aluminium oxide powder in a solution containing piceine and a nonpolar solvent such as toluene. The weight proportions are 1 to 8 parts of piceine, 3 to 9 parts of boron nitride or aluminium oxide, and 1 to 10 parts of the nonpolar solvent. (Z.S.)

  3. Development and Production of Array Barrier Detectors at SCD

    Science.gov (United States)

    Klipstein, P. C.; Avnon, E.; Benny, Y.; Berkowicz, E.; Cohen, Y.; Dobromislin, R.; Fraenkel, R.; Gershon, G.; Glozman, A.; Hojman, E.; Ilan, E.; Karni, Y.; Klin, O.; Kodriano, Y.; Krasovitsky, L.; Langof, L.; Lukomsky, I.; Nevo, I.; Nitzani, M.; Pivnik, I.; Rappaport, N.; Rosenberg, O.; Shtrichman, I.; Shkedy, L.; Snapi, N.; Talmor, R.; Tessler, R.; Weiss, E.; Tuito, A.

    2017-09-01

    XB n or XB p barrier detectors exhibit diffusion-limited dark currents comparable with mercury cadmium telluride Rule-07 and high quantum efficiencies. In 2011, SemiConductor Devices (SCD) introduced "HOT Pelican D", a 640 × 512/15- μm pitch InAsSb/AlSbAs XB n mid-wave infrared (MWIR) detector with a 4.2- μm cut-off and an operating temperature of ˜150 K. Its low power (˜3 W), high pixel operability (>99.5%) and long mean time to failure make HOT Pelican D a highly reliable integrated detector-cooler product with a low size, weight and power. More recently, "HOT Hercules" was launched with a 1280 × 1024/15- μm format and similar advantages. A 3-megapixel, 10- μm pitch version ("HOT Blackbird") is currently completing development. For long-wave infrared applications, SCD's 640 × 512/15- μm pitch "Pelican-D LW" XB p type II superlattice (T2SL) detector has a ˜9.3- μm cut-off wavelength. The detector contains InAs/GaSb and InAs/AlSb T2SLs, and is fabricated into focal plane array (FPA) detectors using standard production processes including hybridization to a digital silicon read-out integrated circuit (ROIC), glue underfill and substrate thinning. The ROIC has been designed so that the complete detector closely follows the interfaces of SCD's MWIR Pelican-D detector family. The Pelican-D LW FPA has a quantum efficiency of ˜50%, and operates at 77 K with a pixel operability of >99% and noise equivalent temperature difference of 13 mK at 30 Hz and F/2.7.

  4. Response function of semiconductor detectors, Ge and Si(Li)

    International Nuclear Information System (INIS)

    Zevallos Chavez, Juan Yury

    2003-01-01

    The Response Function (RF) for Ge and Si(Li) semiconductor detectors was obtained. The RF was calculated for five detectors, four Hp Ge with active volumes of 89 cm 3 , 50 cm 3 , 8 cm 3 and 5 cm 3 , and one Si(Li) with 0.143 cm 3 of active volume. The interval of energy studied ranged from 6 keV up to 1.5 MeV. Two kinds of studies were done in this work. The first one was the RF dependence with the detection geometry. Here the calculation of the RF for a geometry named as simple and an extrapolation of that RF, were both done. The extrapolation process analyzed both, spectra obtained with a shielding geometry and spectra where the source-detector distance was modified. The second one was the RF dependence with the detection electronics. This study was done varying the shaping time of the pulse in the detection electronics. The purpose was to verify the effect of the ballistic deficit in the resolution of the detector. This effect was not observed. The RF components that describe the region of the total absorption of the energy of the incident photons, and the partial absorption of this energy, were both treated. In particular, empirical functions were proposed for the treatment of both, the multiple scattering originated in the detector (crystal), and the photon scattering originated in materials of the neighborhood of the crystal. Another study involving Monte Carlo simulations was also done in order to comprehend the photon scattering structures produced in an iron shield. A deconvolution method is suggested, for spectra related to scattered radiation in order to assess the dose delivered to the scatterer. (author)

  5. Response function of semiconductor detectors, Ge and Si(Li); Funcao resposta de detectores semicondutores, Ge e Si(Li)

    Energy Technology Data Exchange (ETDEWEB)

    Zevallos Chavez, Juan Yury

    2003-07-01

    The Response Function (RF) for Ge and Si(Li) semiconductor detectors was obtained. The RF was calculated for five detectors, four Hp Ge with active volumes of 89 cm{sup 3} , 50 cm{sup 3} , 8 cm{sup 3} and 5 cm{sup 3}, and one Si(Li) with 0.143 cm{sup 3} of active volume. The interval of energy studied ranged from 6 keV up to 1.5 MeV. Two kinds of studies were done in this work. The first one was the RF dependence with the detection geometry. Here the calculation of the RF for a geometry named as simple and an extrapolation of that RF, were both done. The extrapolation process analyzed both, spectra obtained with a shielding geometry and spectra where the source-detector distance was modified. The second one was the RF dependence with the detection electronics. This study was done varying the shaping time of the pulse in the detection electronics. The purpose was to verify the effect of the ballistic deficit in the resolution of the detector. This effect was not observed. The RF components that describe the region of the total absorption of the energy of the incident photons, and the partial absorption of this energy, were both treated. In particular, empirical functions were proposed for the treatment of both, the multiple scattering originated in the detector (crystal), and the photon scattering originated in materials of the neighborhood of the crystal. Another study involving Monte Carlo simulations was also done in order to comprehend the photon scattering structures produced in an iron shield. A deconvolution method is suggested, for spectra related to scattered radiation in order to assess the dose delivered to the scatterer. (author)

  6. Field profile tailoring in a-Si:H radiation detectors

    International Nuclear Information System (INIS)

    Fujieda, I.; Cho, G.; Conti, M.; Drewery, J.; Kaplan, S.N.; Perez-Mendez, V.; Quershi, S.; Wildermuth, D.; Street, R.A.

    1990-03-01

    The capability of tailoring the field profile in reverse-biased a-Si:H diodes by doping and/or manipulating electrode shapes opens a way to many interesting device structures. Charge collection in a-Si:H radiation detectors is improved for high LET particle detection by inserting thin doped layers into the i-layer of the usual p-i-n diode. This buried p-i-n structure enables us to apply higher reverse-bias and the electric field is enhanced in the mid i-layer. Field profiles of the new structures are calculated and the improved charge collection process is discussed. Also discussed is the possibility of field profile tailoring by utilizing the fixed space charges in i-layers and/or manipulating electrode shapes of the reverse-biased p-i-n diodes. 10 refs., 7 figs

  7. Radiation damage studies of detector-compatible Si JFETs

    International Nuclear Information System (INIS)

    Dalla Betta, Gian-Franco; Boscardin, Maurizio; Candelori, Andrea; Pancheri, Lucio; Piemonte, Claudio; Ratti, Lodovico; Zorzi, Nicola

    2007-01-01

    We have largely improved the performance of our detector-compatible Si JFETs by optimizing the fabrication technology. New devices feature thermal noise values close to the theoretical ones, and remarkably low 1/f noise figures. In view of adopting these JFETs for X-ray imaging and HEP applications, bulk and surface radiation damage tests have been carried out by irradiating single transistors and test structures with neutrons and X-rays. Selected results from static and noise characterization of irradiated devices are discussed in this paper, and the impact of radiation effects on the performance of JFET-based circuits is addressed

  8. Irradiation of 4H-SiC UV detectors with heavy ions

    International Nuclear Information System (INIS)

    Kalinina, E. V.; Lebedev, A. A.; Bogdanova, E.; Berenquier, B.; Ottaviani, L.; Violina, G. N.; Skuratov, V. A.

    2015-01-01

    Ultraviolet (UV) photodetectors based on Schottky barriers to 4H-SiC are formed on lightly doped n-type epitaxial layers grown by the chemical vapor deposition method on commercial substrates. The diode structures are irradiated at 25°C by 167-MeV Xe ions with a mass of 131 amu at a fluence of 6 × 10 9 cm −2 . Comparative studies of the optical and electrical properties of as-grown and irradiated structures with Schottky barriers are carried out in the temperature range 23–180°C. The specific features of changes in the photosensitivity and electrical characteristics of the detector structures are accounted for by the capture of photogenerated carriers into traps formed due to fluctuations of the conduction-band bottom and valence-band top, with subsequent thermal dissociation

  9. Performance and Durability of Environmental Barrier Coatings on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan; Bhatt, Ramakrishna

    2016-01-01

    This presentation highlights advanced environmental barrier coating (EBC) and SiC-SiC Ceramic Matrix Composites (CMC) systems for next generation turbine engines. The emphasis will be placed on fundamental coating and CMC property evaluations; and the integrated system performance and degradation mechanisms in simulated laboratory turbine engine testing environments. Long term durability tests in laser rig simulated high heat flux the rmomechanical creep and fatigue loading conditions will also be presented. The results can help improve the future EBC-CMC system designs, validating the advanced EBC-CMC technologies for hot section turbine engine applications.

  10. Silicon Based Mid Infrared SiGeSn Heterostructure Emitters and Detectors

    Science.gov (United States)

    2016-05-16

    AFRL-AFOSR-JP-TR-2016-0054 Silicon based mid infrared SiGeSn heterostrcture emitters and detectors Greg Sun UNIVERSITY OF MASSACHUSETTS Final Report... Silicon Based Mid Infrared SiGeSn Heterostructure Emitters and Detectors ” February 10, 2016 Principal Investigator: Greg Sun Engineering...diodes are incompatible with the CMOS process and therefore cannot be easily integrated with Si electronics . The GeSn mid IR detectors developed in

  11. A SPICE model of double-sided Si microstrip detectors

    International Nuclear Information System (INIS)

    Candelori, A.; Paccagnella, A.; Bonin, F.

    1996-01-01

    We have developed a SPICE model for the ohmic side of AC-coupled Si microstrip detectors with interstrip isolation via field plates. The interstrip isolation has been measured in various conditions by varying the field plate voltage. Simulations have been compared with experimental data in order to determine the values of the model parameters for different voltages applied to the field plates. The model is able to predict correctly the frequency dependence of the coupling between adjacent strips. Furthermore, we have used such model for the study of the signal propagation along the detector when a current signal is injected in a strip. Only electrical coupling is considered here, without any contribution due to charge sharing derived from carrier diffusion. For this purpose, the AC pads of the strips have been connected to a read-out electronics and the current signal has been injected into a DC pad. Good agreement between measurements and simulations has been reached for the central strip and the first neighbors. Experimental tests and computer simulations have been performed for four different strip and field plate layouts, in order to investigate how the detector geometry affects the parameters of the SPICE model and the signal propagation

  12. Advanced Environmental Barrier Coating Development for SiC-SiC Ceramic Matrix Composite Components

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan; Hurst, Janet B.; Halbig, Michael Charles; Puleo, Bernadette J.; Costa, Gustavo; Mccue, Terry R.

    2017-01-01

    This presentation reviews the NASA advanced environmental barrier coating (EBC) system development for SiC-SiC Ceramic Matrix Composite (CMC) combustors particularly under the NASA Environmentally Responsible Aviation, Fundamental Aeronautics and Transformative Aeronautics Concepts Programs. The emphases have been placed on the current design challenges of the 2700-3000F capable environmental barrier coatings for low NOX emission combustors for next generation turbine engines by using advanced plasma spray based processes, and the coating processing and integration with SiC-SiC CMCs and component systems. The developments also have included candidate coating composition system designs, degradation mechanisms, performance evaluation and down-selects; the processing optimizations using TriplexPro Air Plasma Spray Low Pressure Plasma Spray (LPPS), Plasma Spray Physical Vapor Deposition and demonstration of EBC-CMC systems. This presentation also highlights the EBC-CMC system temperature capability and durability improvements under the NASA development programs, as demonstrated in the simulated engine high heat flux, combustion environments, in conjunction with high heat flux, mechanical creep and fatigue loading testing conditions.

  13. Thermally stimulated capacitance in gamma irradiated epitaxial 4H-SiC Schottky barrier diodes

    Science.gov (United States)

    Vigneshwara Raja, P.; Narasimha Murty, N. V. L.

    2018-04-01

    Deep level defects in 4H-SiC Schottky barrier diodes (SBDs) fabricated on n-type epitaxial 4H-SiC have been identified by thermally stimulated capacitance (TSCAP) spectroscopy prior to and after 60Co-gamma irradiation. The TSCAP measurements on the non-irradiated SBDs reveal two electron traps at Ec-0.63 eV (˜250 K) and Ec-1.13 eV (˜525 K), whereas only one trap at Ec-0.63 eV is identified by conventional thermally stimulated current (TSC) measurements. Hence, TSCAP spectroscopy is more effective in identifying deep level defects in epitaxial 4 H-SiC SBDs as compared to the TSC spectroscopy. Upon exposure to 60Co-gamma rays up to a dose of 100 Mrad, significant changes in the concentration of the traps at Ec-0.63 eV, Ec-1.13 eV, and one new trap at Ec-0.89 eV (˜420 K) are observed. The electrical characteristics of the SBDs are considerably changed after gamma irradiation. The dominant mechanisms responsible for the irradiation induced changes in the SBD electrical characteristics are analyzed by incorporating the trap signatures in the commercial Silvaco® TCAD device simulator. The extracted trap parameters of the irradiated SBDs may be helpful in predicting the survival of 4H-SiC SBD detectors at higher irradiation levels.

  14. Property Evaluation and Damage Evolution of Environmental Barrier Coatings and Environmental Barrier Coated SiC/SiC Ceramic Matrix Composite Sub-Elements

    Science.gov (United States)

    Zhu, Dongming; Halbig, Michael; Jaskowiak, Martha; Hurst, Janet; Bhatt, Ram; Fox, Dennis S.

    2014-01-01

    This paper describes recent development of environmental barrier coatings on SiC/SiC ceramic matrix composites. The creep and fatigue behavior at aggressive long-term high temperature conditions have been evaluated and highlighted. Thermal conductivity and high thermal gradient cyclic durability of environmental barrier coatings have been evaluated. The damage accumulation and complex stress-strain behavior environmental barrier coatings on SiCSiC ceramic matrix composite turbine airfoil subelements during the thermal cyclic and fatigue testing of have been also reported.

  15. Phase Stability and Thermal Conductivity of Composite Environmental Barrier Coatings on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Benkel, Samantha; Zhu, Dongming

    2011-01-01

    Advanced environmental barrier coatings are being developed to protect SiC/SiC ceramic matrix composites in harsh combustion environments. The current coating development emphasis has been placed on the significantly improved cyclic durability and combustion environment stability in high-heat-flux and high velocity gas turbine engine environments. Environmental barrier coating systems based on hafnia (HfO2) and ytterbium silicate, HfO2-Si nano-composite bond coat systems have been processed and their stability and thermal conductivity behavior have been evaluated in simulated turbine environments. The incorporation of Silicon Carbide Nanotubes (SiCNT) into high stability (HfO2) and/or HfO2-silicon composite bond coats, along with ZrO2, HfO2 and rare earth silicate composite top coat systems, showed promise as excellent environmental barriers to protect the SiC/SiC ceramic matrix composites.

  16. Creep Behavior of Hafnia and Ytterbium Silicate Environmental Barrier Coating Systems on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Fox, Dennis S.; Ghosn, Louis J.; Harder, Bryan

    2011-01-01

    Environmental barrier coatings will play a crucial role in future advanced gas turbine engines because of their ability to significantly extend the temperature capability and stability of SiC/SiC ceramic matrix composite (CMC) engine components, thus improving the engine performance. In order to develop high performance, robust coating systems for engine components, appropriate test approaches simulating operating temperature gradient and stress environments for evaluating the critical coating properties must be established. In this paper, thermal gradient mechanical testing approaches for evaluating creep and fatigue behavior of environmental barrier coated SiC/SiC CMC systems will be described. The creep and fatigue behavior of Hafnia and ytterbium silicate environmental barrier coatings on SiC/SiC CMC systems will be reported in simulated environmental exposure conditions. The coating failure mechanisms will also be discussed under the heat flux and stress conditions.

  17. On the suitability of Peltier cooled Si-PIN detectors in transmission experiments

    International Nuclear Information System (INIS)

    Murty, V.R.K.; Devan, K.R.S.

    2001-01-01

    The performance of a Peltier cooled Si-PIN detector is compared with that for a Freolectric cooled Si(Li) detector, references being made to transmission experiments that evaluate total cross sections at low photon energies. The results of these measurements are discussed. (author)

  18. On the suitability of P Si-PIN detectors in transmission experiments

    International Nuclear Information System (INIS)

    Murty, V.R.K.; Devan, K.R.S.

    2000-01-01

    There has been considerable interest, in the recent past, in the development of detector technology. In this context, new detectors, especially room temperature operated detectors and inexpensive cooling systems have recently entered the market. These new systems replace the old systems where there are inadequate facilities to operate them to achieve superior performance. Such performance capabilities of different systems, on a comparative basis have not been widely published in the recent past. In this direction, the Peltier cooled detectors have entered the market and are replacing the conventional Si(Li) detectors. In between the conventional Si(Li) detectors and Peltier cooled Si-PIN detectors, the freolectric cooled Si(Li) detectors were also used in Radiation Physics applications. In this paper, the performance of the Peltier cooled Si-PIN detector in comparison with a Freolectric cooled Si(Li) detector has been studied in Transmission experiments to evaluate the total cross sections at low energies and the results are discussed. (author)

  19. Gamma detection: an unusual application for surface barrier detectors

    Energy Technology Data Exchange (ETDEWEB)

    Fichtenbaum de Iacub, S; Matatagui, E

    1983-02-01

    The silicon surface barrier detectors (SBD), may be ideal devices to be used in dose indicators for the monitoring of gamma radiations; the SBD working as a cavity sensor. The measurement consists in counting the number of pulses that exceeds a certain level of discrimination, this number being proportional to the absorbed dose. The spectral distribution of the pulses gives an idea of the existing photon field's energy. Characteristic spectra obtained with different gamma and X-ray sources are described and analyzed, and tests are carried out by using different sensitive volumes of the detector in order to determine significant parameters for a gamma-monitor system. The results from the measurements indicate: a) high sensitivity of the system with SBD (high density of material); b) low background: enviromental backgrounds are reliably registered (approx. 10 R/h); c) minimum detectable energies of the order of 60 keV; d) possibility to determine high exposure rates (approx. 100 R/h); e) for emitters of low Z, the result is approximately independent from the gamma energy. These results suggest the possibility of constructing fixed and portable systems, appropriate for gamma monitoring, which utilize SBD as sensors; these devices are adequate for working at enviroment temperatures, being compact, reliable, with low polarization voltages, and of relatively low cost.

  20. Gamma detection: an unusual application for surface barrier detectors

    International Nuclear Information System (INIS)

    Fichtenbaum de Iacub, Silvana; Matatagui, Emilio

    1983-01-01

    The silicon surface barrier detectors (SBD), may be ideal devices to be used in dose indicators for the monitoring of gamma radiations; the SBD working as a cavity sensor. The measurement consists in counting the number of pulses that exceeds a certain level of discrimination, this number being proportional to the absorbed dose. The spectral distribution of the pulses gives an idea of the existing photons field's energy. Characteristic spectra obtained with different gamma-and X ray sources are described and analyzed, and tests are carried out by using different sensitive volumes of the detector in order to determine significant parameters for a gamma-monitor system. The results from the measurements indicate: a) high sensitivity of the system with SBD (high density of material); b) low background: enviromental backgrounds are reliably registered (approx. 10μ R/h); c) minimum detectable energies of the order of 60 keV; d) possibility to determine high exposure rates (approx. 100 R/h); e) for emitters of low Z, the result is approximately independent from the gamma energy. These results suggest the possibility of constructing fixed and portable systems, appropriate for gamma monitoring, which utilize SBD as sensors; these devices are adequate for working at enviroment temperatures, being compact, reliable, with low polarization voltages, and of relatively low cost. (M.E.L.) [es

  1. Fast SiPM Readout of the PANDA TOF Detector

    International Nuclear Information System (INIS)

    Böhm, M.; Lehmann, A.; Motz, S.; Uhlig, F.

    2016-01-01

    For the identification of low momentum charged particles and for event timing purposes a barrel Time-of-Flight (TOF) detector surrounding the interaction point is planned for the PANDA experiment at FAIR . Since the boundary conditions in terms of available radial space and radiation length are quite strict the favored layout is a hodoscope composed of several thousand small scintillating tiles (SciTils) read out by silicon photomultipliers (SiPMs). A time resolution of well below 100 ps is aimed for. With the originally proposed 30 × 30 × 5 mm 3 SciTils read out by two single 3 × 3 mm 2 SiPMs at the rims of the scintillator the targeted time resolution can be just reached, but with a considerable position dependence across the scintillator surface. In this paper we discuss other design options to further improve the time resolution and its homogeneity. It will be shown that wide scintillating rods (SciRods) with a size of, e.g., 50 × 30 × 5 mm 3 or longer and read out at opposite sides by a chain of four serially connected SiPMs a time resolution down to 50 ps can be reached without problems. In addition, the position dependence of the time resolution is negligible. These SciRods were tested in the laboratory with electrons of a 90 Sr source and under real experimental conditions in a particle beam at CERN. The measured time resolutions using fast BC418 or BC420 plastic scintillators wrapped in aluminum foil were consistently between 45 and 75 ps dependent on the SciRod design. This is a significant improvement compared to the original SciTil layout.

  2. Annealing effect on Schottky barrier inhomogeneity of graphene/n-type Si Schottky diodes

    International Nuclear Information System (INIS)

    Lin, Yow-Jon; Lin, Jian-Huang

    2014-01-01

    Highlights: • The current–voltage characteristics of graphene/n-type Si devices were measured. • The ideality factor increases with the decrease measurement temperatures. • Such behavior is attributed to Schottky barrier inhomogeneities. • Both Schottky barrier inhomogeneity and the T 0 effect are affected by annealing. • Stoichiometry of SiO x has a noticeable effect on the inhomogeneous barriers. - Abstract: The current–voltage characteristics of graphene/n-type Si (n-Si) Schottky diodes with and without annealing were measured in the temperature range of −120 to 30 °C and analyzed on the basis of thermionic emission theory. It is found that the barrier height decreases and the ideality factor increases with the decrease measurement temperatures. Such behavior is attributed to Schottky barrier inhomogeneities. It is shown that both the barrier height and the ideality factor can be tuned by changing the annealing temperature. Through the analysis, it can be suspected that a SiO x layer at the graphene/n-Si interfaces influences the electronic conduction through the device and stoichiometry of SiO x is affected by annealing treatment. In addition, both Schottky barrier inhomogeneity and the T 0 effect are affected by annealing treatment, implying that stoichiometry of SiO x has a noticeable effect on the inhomogeneous barriers of graphene/n-Si Schottky diodes

  3. Silicon for ultra-low-level detectors and sup 32 Si

    Energy Technology Data Exchange (ETDEWEB)

    Plaga, R. (Max Planck Inst. fuer Kernphysik, Heidelberg (Germany))

    1991-11-15

    A recent dark matter experiment using a silicon diode detector confirms that the decay of {sup 32}Si is a dangerous background in ultra-low-level experiments using silicon as detector material or shielding. In this Letter we study the mechanism of how {sup 32}Si enters commercially available silicon. Ways to avoid this contamination are pointed out. Limits on the {sup 32}Si content of silicon from measurements with miniaturized low-level proportional counters are also given. (orig.).

  4. POSSuMUS: a position sensitive scintillating muon SiPM detector

    CERN Document Server

    Ruschke, Alexander

    The development of a modular designed large scale scintillation detector with a two-dimensional position sensitivity is presented in this thesis. This novel POsition Sensitive Scintillating MUon SiPM Detector is named POSSuMUS. The POSSuMUS detector is capable to determine the particle’s position in two space dimensions with a fast trigger capability. Each module is constructed from two trapezoidal shaped plastic scintillators to form one rectangular shaped detector module. Both trapezoids are optically insulated against each other. In both trapezoids the scintillation light is collected by plastic fibers and guided towards silicon photomultipliers (SiPMs). SiPMs are light sensors which are capable to detect even smallest amounts of light. By combining several detector modules, position sensitive areas from 100 cm2 to few m2 are achievable with few readout channels. Therefore, POSSuMUS provides a cost effective detector concept. The position sensitivity along the trapezoidal geometry of one detector module ...

  5. Detection alpha particles and Cf-252 fission fragments with track solid detectors and with surface barrier detectors: efficiency determination

    International Nuclear Information System (INIS)

    Khouri, M.T.F.C.; Koskinas, M.F.; Andrade, C. de; Vilela, E.C.; Hinostroza, H.; Kaschiny, J.R.A.; Costa, M.S. da; Rizzo, P.; Santos, W.M.S.

    1990-01-01

    The technique of particle detection by solid track detectors, types of developing and analysis of results are presented. Efficiency measurements of alpha particle detection with Makrofol e and surface barrier detector are made. Detection of Cf-252 fission fragments is shown. (L.C.)

  6. Detection of alpha particles and Cf-252 fission fragments with solid track detectors and surface barrier detector. Efficiency calculation

    International Nuclear Information System (INIS)

    Khouri, M.T.F.C.; Koskinas, M.F.; Andrade, C. de; Vilela, E.C.; Hinostroza, H.; Kaschiny, J.E.A.; Costa, M.S. da; Rizzo, P.; Santos, W.M.S.

    1990-01-01

    A technique for particle detection by using track solid detector and also types of revealing and result analysis are presented concerned to Cf-252 fission fragments detection. Measurements of alpha particles detection efficiency using Makrofol E and surface barrier detector are performed. (L.C.J.A.)

  7. Diffusion barrier and adhesion properties of SiO(x)N(y) and SiO(x) layers between Ag/polypyrrole composites and Si substrates.

    Science.gov (United States)

    Horváth, Barbara; Kawakita, Jin; Chikyow, Toyohiro

    2014-06-25

    This paper describes the interface reactions and diffusion between silver/polypyrrole (Ag/PPy) composite and silicon substrate. This composite material can be used as a novel technique for 3D-LSI (large-scale integration) by the fast infilling of through-silicon vias (TSV). By immersion of the silicon wafer with via holes into the dispersed solution of Ag/PPy composite, the holes are filled with the composite. It is important to develop a layer between the composite and the Si substrate with good diffusion barrier and adhesion characteristics. In this paper, SiOx and two types of SiOxNy barrier layers with various thicknesses were investigated. The interface structure between the Si substrate, the barrier, and the Ag/PPy composite was characterized by transmission electron microscopy. The adhesion and diffusion properties of the layers were established for Ag/PPy composite. Increasing thickness of SiOx proved to permit less Ag to transport into the Si substrate. SiOxNy barrier layers showed very good diffusion barrier characteristics; however, their adhesion depended strongly on their composition. A barrier layer composition with good adhesion and Ag barrier properties has been identified in this paper. These results are useful for filling conductive metal/polymer composites into TSV.

  8. Si(Li) detectors with thin dead layers for low energy x-ray detection

    International Nuclear Information System (INIS)

    Rossington, C.S.; Walton, J.T.; Jaklevic, J.M.

    1990-10-01

    Regions of incomplete charge collection, or ''dead layers'', are compared for Si(Li) detectors fabricated with Au and Pd entrance window electrodes. The dead layers were measured by characterizing the detector spectral response to x-ray energies above and below the Si Kα absorption edge. It was found that Si(Li) detectors with Pd electrodes exhibit consistently thinner effective Si dead layers than those with Au electrodes. Furthermore, it is demonstrated that the minimum thickness required for low resistivity Pd electrodes is thinner than that required for low resistivity Au electrodes, which further reduces the signal attenuation in Pd/Si(Li) detectors. A model, based on Pd compensation of oxygen vacancies in the SiO 2 at the entrance window Si(Li) surface, is proposed to explain the observed differences in detector dead layer thickness. Electrode structures for optimum Si(Li) detector performance at low x-ray energies are discussed. 18 refs., 8 figs., 1 tab

  9. Estimation of interface resistivity in bonded Si for the development of high performance radiation detectors

    International Nuclear Information System (INIS)

    Kanno, Ikuo; Yamashita, Makoto; Nomiya, Seiichiro; Onabe, Hideaki

    2007-01-01

    For the development of high performance radiation detectors, direct bonding of Si wafers would be an useful method. Previously, p-n bonded Si were fabricated and they showed diode characteristics. The interface resistivity was, however, not investigated in detail. For the study of interface resistivity, n-type Si wafers with different resistivities were bonded. The resistivity of bonded Si wafers were measured and the interface resistivity was estimated by comparing with the results of model calculations. (author)

  10. Optimization of Silicon parameters as a betavoltaic battery: Comparison of Si p-n and Ni/Si Schottky barrier

    International Nuclear Information System (INIS)

    Rahmani, Faezeh; Khosravinia, Hossein

    2016-01-01

    Theoretical studies on the optimization of Silicon (Si) parameters as the base of betavoltaic battery have been presented using Monte Carlo simulations and the state equations in semiconductor to obtain maximum power. Si with active area of 1 cm 2 has been considered in p-n junction and Schottky barrier structure to collect the radiation induced-charge from 10 mCi cm −2 of Nickle-63 ( 63 Ni) Source. The results show that the betavoltaic conversion efficiency in the Si p-n structure is about 2.7 times higher than that in the Ni/Si Schottky barrier structure. - Highlights: • Silicon parameters were studied in betavoltaic batteries. • Studied betavoltaic batteries include p-n and Schottky barrier structures. • The p-n structure has higher conversion efficiency.

  11. Combined Thermomechanical and Environmental Durability of Environmental Barrier Coating Systems on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan; Bhatt, Ramakrishna

    2016-01-01

    Environmental barrier coatings (EBCs) and SiC/SiC ceramic matrix composites (CMCs) will play a crucial role in next generation turbine engines for hot-section component applications. The development of prime-reliant environmental barrier coatings is essential to the EBC-CMC system durability, ensuring the successful implementations of the high temperature and lightweight engine component technologies for engine applications.This paper will emphasize recent NASA environmental barrier coating and CMC developments for SiC/SiC turbine airfoil components, utilizing advanced coating compositions and processing methods. The emphasis has been particularly placed on thermomechanical and environment durability evaluations of EBC-CMC systems. We have also addressed the integration of the EBCs with advanced SiC/SiC CMCs, and studied the effects of combustion environments and Calcium-Magnesium-Alumino-Silicate (CMAS) deposits on the durability of the EBC-CMC systems under thermal gradient and mechanical loading conditions. Advanced environmental barrier coating systems, including multicomponent rare earth silicate EBCs and HfO2-Si based bond coats, will be discussed for the performance improvements to achieve better temperature capability and CMAS resistance for future engine operating conditions.

  12. Environmental Barrier Coating Development for SiC/SiC Ceramic Matrix Composites: Recent Advances and Future Directions

    Science.gov (United States)

    Zhu, Dongming

    2016-01-01

    This presentation briefly reviews the SiC/SiC major environmental and environment-fatigue degradations encountered in simulated turbine combustion environments, and thus NASA environmental barrier coating system evolution for protecting the SiC/SiC Ceramic Matrix Composites for meeting the engine performance requirements. The presentation will review several generations of NASA EBC materials systems, EBC-CMC component system technologies for SiC/SiC ceramic matrix composite combustors and turbine airfoils, highlighting the temperature capability and durability improvements in simulated engine high heat flux, high pressure, high velocity, and with mechanical creep and fatigue loading conditions. This paper will also focus on the performance requirements and design considerations of environmental barrier coatings for next generation turbine engine applications. The current development emphasis is placed on advanced NASA candidate environmental barrier coating systems for SiC/SiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. The efforts have been also directed to developing prime-reliant, self-healing 2700F EBC bond coat; and high stability, lower thermal conductivity, and durable EBC top coats. Major technical barriers in developing environmental barrier coating systems, the coating integrations with next generation CMCs having the improved environmental stability, erosion-impact resistance, and long-term fatigue-environment system durability performance will be described. The research and development opportunities for turbine engine environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling will be briefly discussed.

  13. Characterisation of NdFeB thin films prepared on (100)Si substrates with SiO2 barrier layers

    International Nuclear Information System (INIS)

    Sood, D.K.; Muralidhar, G.K.

    1998-01-01

    This work presents a systematic study of the deposition and characterization of NdFeB films on substrates of Si(100) and of SiO2 layer thermally grown on Si(100) held at RT, 360 deg C or 440 deg C. The post-deposition annealing is performed at 600 or 800 deg C in vacuum. The films are characterised using the analytical techniques of RBS, SIMS, XRD, OM and SEM. Results indicate that SiO2 is, in deed, an excellent diffusion barrier layer till 600 deg C but becomes relatively less effective at 800 deg C. Without this barrier layer, interdiffusion at the Si-NdFeB film interface leads to formation of iron silicides, α-Fe and B exclusion from the diffusion zone, in competition with the formation of the magnetic NdFeB phase. (authors)

  14. Calculation of the Electronic Parameters of an Al/DNA/p-Si Schottky Barrier Diode Influenced by Alpha Radiation

    Directory of Open Access Journals (Sweden)

    Hassan Maktuff Jaber Al-Ta'ii

    2015-02-01

    Full Text Available Many types of materials such as inorganic semiconductors have been employed as detectors for nuclear radiation, the importance of which has increased significantly due to recent nuclear catastrophes. Despite the many advantages of this type of materials, the ability to measure direct cellular or biological responses to radiation might improve detector sensitivity. In this context, semiconducting organic materials such as deoxyribonucleic acid or DNA have been studied in recent years. This was established by studying the varying electronic properties of DNA-metal or semiconductor junctions when exposed to radiation. In this work, we investigated the electronics of aluminium (Al/DNA/silicon (Si rectifying junctions using their current-voltage (I-V characteristics when exposed to alpha radiation. Diode parameters such as ideality factor, barrier height and series resistance were determined for different irradiation times. The observed results show significant changes with exposure time or total dosage received. An increased deviation from ideal diode conditions (7.2 to 18.0 was observed when they were bombarded with alpha particles for up to 40 min. Using the conventional technique, barrier height values were observed to generally increase after 2, 6, 10, 20 and 30 min of radiation. The same trend was seen in the values of the series resistance (0.5889–1.423 Ω for 2–8 min. These changes in the electronic properties of the DNA/Si junctions could therefore be utilized in the construction of sensitive alpha particle detectors.

  15. Particle Identification algorithm for the CLIC ILD and CLIC SiD detectors

    CERN Document Server

    Nardulli, J

    2011-01-01

    This note describes the algorithm presently used to determine the particle identification performance for single particles for the CLIC ILD and CLIC SiD detector concepts as prepared in the CLIC Conceptual Design Report.

  16. Uncooled Radiation Hard SiC Schottky VUV Detectors Capable of Single Photon Sensing, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This project seeks to design, fabricate, characterize and commercialize very large area, uncooled and radiative hard 4H-SiC VUV detectors capable of near single...

  17. Particle mis-identification rate algorithm for the CLIC ILD and CLIC SiD detectors

    CERN Document Server

    Nardulli, J

    2011-01-01

    This note describes the algorithm presently used to determine the particle mis- identification rate and gives results for single particles for the CLIC ILD and CLIC SiD detector concepts as prepared for the CLIC Conceptual Design Report.

  18. Analysis and comparison of the breakdown performance of semi- insulator and dielectric passivated Si strip detectors

    CERN Document Server

    Ranjan, Kirti; Chatterji, S; Srivastava-Ajay, K; Shivpuri, R K

    2002-01-01

    The harsh radiation environment in future high-energy physics (HEP) experiments like LHC provides a challenging task to the performance of Si microstrip detectors. Normal operating condition for silicon detectors in HEP experiments are in most cases not as favourable as for experiments in nuclear physics. In HEP experiments the detector may be exposed to moisture and other adverse atmospheric environment. It is therefore utmost important to protect the sensitive surfaces against such poisonous effects. These instabilities can be nearly eliminated and the performance of Si detectors can be improved by implementing suitably passivated metal-overhang structures. This paper presents the influence of the relative permittivity of the passivant on the breakdown performance of the Si detectors using computer simulations. The semi-insulator and the dielectric passivated metal-overhang structures are compared under optimal conditions. The influence of various parameters such as passivation layer thickness, junction dep...

  19. Properties of SiC semiconductor detector of fast neutrons investigated using MCNPX code

    International Nuclear Information System (INIS)

    Sedlakova, K.; Sagatova, A.; Necas, V.; Zatko, B.

    2013-01-01

    The potential of silicon carbide (SiC) for use in semiconductor nuclear radiation detectors has been long recognized. The wide bandgap of SiC (3.25 eV for 4H-SiC polytype) compared to that for more conventionally used semiconductors, such as silicon (1.12 eV) and germanium (0.67 eV), makes SiC an attractive semiconductor for use in high dose rate and high ionization nuclear environments. The present work focused on the simulation of particle transport in SiC detectors of fast neutrons using statistical analysis of Monte Carlo radiation transport code MCNPX. Its possibilities in detector design and optimization are presented.(authors)

  20. Measuring variation of indoor radon concentration using bare nuclear tracks detectors, scintillation counters and surface barrier detectors

    International Nuclear Information System (INIS)

    Ishak, I.; Mahat, R.H.; Amin, Y.M.

    1996-01-01

    Bare LRI 15 nuclear track detectors , scintillators counter and surface barrier detectors were used to measured the indoor radon concentration in various location within two rooms. Spatial variation of the radon concentration is caused by positioning of the door, windows, furniture, cracks in the building and also distances from floor, wall and ceiling. It is found that the change in temperature are causing radon concentration to increase at certain time of the day

  1. Development of large area si detectors based on planar technology for charged particles

    International Nuclear Information System (INIS)

    Zhang Wanchang; Sun Liang; Huang Xiaojian; Liu Yang; Chen Guozhu

    2009-01-01

    This paper describes the processing method of large area Si detectors fabricated by planar technology for charged particles. In order to decrease the detectors leakage current, the surface passivation technique was used. The paper gives the measurement results of the leakage current of 300μm thick, 20mm diameter detectors and 500μm thick, 40mm diameter detectors respectively. The spectra of the detectors for 241 Am 5.486MeV α particles are also provided at room temperature. (authors)

  2. POSSuMUS. A position sensitive scintillating muon SiPM detector

    International Nuclear Information System (INIS)

    Ruschke, Alexander

    2014-01-01

    The development of a modular designed large scale scintillation detector with a two-dimensional position sensitivity is presented in this thesis. This novel POsition Sensitive Scintillating MUon SiPM Detector is named POSSuMUS. The POSSuMUS detector is capable to determine the particle's position in two space dimensions with a fast trigger capability. Each module is constructed from two trapezoidal shaped plastic scintillators to form one rectangular shaped detector module. Both trapezoids are optically insulated against each other. In both trapezoids the scintillation light is collected by plastic fibers and guided towards silicon photomultipliers (SiPMs). SiPMs are light sensors which are capable to detect even smallest amounts of light. By combining several detector modules, position sensitive areas from 100 cm 2 to few m 2 are achievable with few readout channels. Therefore, POSSuMUS provides a cost effective detector concept. The position sensitivity along the trapezoidal geometry of one detector module is achieved by the path length dependent amount of detected light for crossing particles. The ratio of the light yields in both trapezoids is calculated. This value corresponds to the position of the particle traversing the detector. A spatial resolution in the order of several mm is foreseen. The position sensitivity along the scintillator module is determined by the propagation time of light to the SiPMs located on opposite sides of the detector. A spatial resolution of few cm is expected for this direction. The POSSuMUS detector is applicable as large area trigger detector with a two dimensional position information of crossing particles. This is suitable in detector tests of large area precesion detectors or for measuring the small angle scattering of cosmic muons. At the beginning of this thesis, the determination of important SiPM characteristics like the breakdown voltage is presented. In the course of this work the detector principle is proven by

  3. Si(Li) detector system for application to x-ray astronomy rocket experiments

    International Nuclear Information System (INIS)

    Griffiths, R.E.; Cheron, C.; Friant, A.; Jehanno, C.; Rocchia, R.; Rothenflug, R.; Testard, O.

    1975-01-01

    The problems associated with the use of Si(Li) detectors in x-ray astronomy rocket experiments are discussed. In particular a detector system is described that can be used at the focus of a grazing-incidence paraboloid telescope for the energy range 0.3 to 2 keV. (U.S.)

  4. Silicon surface barrier detector and study of energy spectrum of alpha particles from radioactive source

    International Nuclear Information System (INIS)

    Verma, S.D.; Sinha, Vijaya

    1986-01-01

    The principles of working of three commonly used radiation detectors, namely ionization chambers, scintillation counters with photomultiplier tube (PMT) systems and semiconductor detectors are briefly discussed. Out of the semiconductor detectors, the silicon surface barrier (SSB) detector has distinct advantages for detection of radiations, alpha particles in particular. The experimental setup to obtain the energy spectrum of alpha particles from 241 Am source using SSB fabricated in the Physics Department of Gujarat University, Ahmedabad is described. Its performance is compared with scintillation counter using PMT. SSB detector shows a sharp peak of #approx # 3 per cent energy resolution. The factors affecting the peak, namely, electronic noise, source dependent factors and detector-dependent factors are discussed. A method of calibrating SSB detectors based on energy loss mechanism of alpha particles in thin absorbers is described. Applications of such detectors are indicated. (M.G.B.)

  5. Microstructure Evolution and Durability of Advanced Environmental Barrier Coating Systems for SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Evans, Laura J.; McCue, Terry R.; Harder, Bryan

    2016-01-01

    Environmental barrier coated SiC-SiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. Advanced HfO2 and rare earth silicate environmental barrier coatings (EBCs), along with multicomponent hafnium and rare earth silicide EBC bond coats have been developed. The coating degradation mechanisms in the laboratory simulated engine thermal cycling, and fatigue-creep operating environments are also being investigated. This paper will focus on the microstructural and compositional evolutions of an advanced environmental barrier coating system on a SiC-SiC CMC substrate during the high temperature simulated durability tests, by using a Field Emission Gun Scanning Electron Microscopy, Energy Dispersive Spectroscopy (EDS) and Wavelength Dispersive Spectroscopy (WDS). The effects of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the degradation mechanisms of the environmental barrier coating systems will also be discussed. The detailed analysis results help understand the EBC-CMC system performance, aiming at the durability improvements to achieve more robust, prime-reliant environmental barrier coatings.

  6. Planar edge Schottky barrier-tunneling transistors using epitaxial graphene/SiC junctions.

    Science.gov (United States)

    Kunc, Jan; Hu, Yike; Palmer, James; Guo, Zelei; Hankinson, John; Gamal, Salah H; Berger, Claire; de Heer, Walt A

    2014-09-10

    A purely planar graphene/SiC field effect transistor is presented here. The horizontal current flow over one-dimensional tunneling barrier between planar graphene contact and coplanar two-dimensional SiC channel exhibits superior on/off ratio compared to conventional transistors employing vertical electron transport. Multilayer epitaxial graphene (MEG) grown on SiC(0001̅) was adopted as the transistor source and drain. The channel is formed by the accumulation layer at the interface of semi-insulating SiC and a surface silicate that forms after high vacuum high temperature annealing. Electronic bands between the graphene edge and SiC accumulation layer form a thin Schottky barrier, which is dominated by tunneling at low temperatures. A thermionic emission prevails over tunneling at high temperatures. We show that neglecting tunneling effectively causes the temperature dependence of the Schottky barrier height. The channel can support current densities up to 35 A/m.

  7. Analysis and optimal design of Si microstrip detector with overhanging metal electrode

    CERN Document Server

    Ranjan, Kirti; Chatterji, S; Srivastava-Ajay, K; Shivpuri, R K

    2001-01-01

    The harsh radiation environment to be encountered at LHC (large hadron collider) and RHIC (relativistic heavy ion collider) poses a challenging task for the fabrication of Si microstrip detectors. Due to high luminosities, detectors are required to sustain very high voltage operation well exceeding the bias voltage needed to fully deplete them. The "overhanging" metal contact is now a well established technique for improving the breakdown performance of the Si microstrip detector. Based on computer simulation, the influence of various physical and geometrical parameters on the electrical breakdown of the Si detectors equipped with metal overhangs is extensively analysed. Furthermore, optimization of design parameters is performed to achieve breakdown voltages close to maximum realizable values. The simulation results are found to be in good agreement with experimental data. (17 refs).

  8. A novel, SiPM-array-based, monolithic scintillator detector for PET

    International Nuclear Information System (INIS)

    Schaart, Dennis R; Dam, Herman T van; Seifert, Stefan; Beekman, Freek J; Vinke, Ruud; Dendooven, Peter; Loehner, Herbert

    2009-01-01

    Silicon photomultipliers (SiPMs) are of great interest to positron emission tomography (PET), as they enable new detector geometries, for e.g., depth-of-interaction (DOI) determination, are MR compatible, and offer faster response and higher gain than other solid-state photosensors such as avalanche photodiodes. Here we present a novel detector design with DOI correction, in which a position-sensitive SiPM array is used to read out a monolithic scintillator. Initial characterization of a prototype detector consisting of a 4 x 4 SiPM array coupled to either the front or back surface of a 13.2 mm x 13.2 mm x 10 mm LYSO:Ce 3+ crystal shows that front-side readout results in significantly better performance than conventional back-side readout. Spatial resolutions 2 detector, equals 960 ps FWHM.

  9. Interface engineered carbon nanotubes with SiO{sub 2} for flexible infrared detectors

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhenlong [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Gao, Min, E-mail: mingao@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Center for Information in Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054 (China); Pan, Taisong [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Wei, Xianhua [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang, Sichuan 621010 (China); Chen, Chonglin [Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX 78249 (United States); Department of Physics and the Texas Center for Superconductivity, University of Houston, Houston, TX 77204 (United States); Lin, Yuan, E-mail: linyuan@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Center for Information in Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054 (China)

    2017-08-15

    Highlights: • Interface engineered carbon nanotubes with SiO{sub 2} is used to construct a kind of flexible infrared detector. • The interface between the MWCNTs and SiO{sub 2} could enhance the IR response speed. • Detector based on the integrated interface of MWCNTs and SiO{sub 2} has successfully detected the movements of the human fingers. - Abstract: Nitrogen-doped/non-doped carbon nanotubes (CNTs) were integrated on SiO{sub 2}/Si and PMMA substrates for understanding the infrared sensing mechanisms. The nanotube structures on SiO{sub 2} substrates exhibit a much shorter response time (about 40 ms) than those directly on PMMA substrates (about 1200 ms), indicating the interface effects between CNTs and the substrates. The infrared responses for both structures show a linear relationship with the light power density even at the radiation power as low as 0.1 mW/mm{sup 2}. Moreover, a new concept flexible IR detector was designed and fabricated by transferring the CNTs/SiO{sub 2} structure onto the PMMA substrate, which exhibits both short response time (50 ms) and good flexibility. The successful detection of human finger movements indicates the practical applications of the CNT-based detectors for the detection of weak thermal or far infrared radiation.

  10. Characterisation of Ta-based barrier films on SiLK for Cu-metalisation

    NARCIS (Netherlands)

    van Nieuwkasteele-Bystrova, Svetlana Nikolajevna; Holleman, J.; Woerlee, P.H.; Wolters, Robertus A.M.

    2002-01-01

    Structures with Ta, TaxN1-x, Ta90C10, Ta95Si5 on SiLK were tested using in-situ 4- point probe resistance measurements during annealing up to 400oC. The change in normalized resistance by a factor of up to 2.58 was attributed to oxygen diffusion out of SiLK layer into the barriers. No direct

  11. Inhomogeneity in barrier height at graphene/Si (GaAs) Schottky junctions

    OpenAIRE

    Tomer, D.; Rajput, S.; Hudy, L. J.; Li, C. H.; Li, L.

    2015-01-01

    Graphene interfaced with a semiconductor forms a Schottky junction with rectifying properties, however, fluctuations in the Schottky barrier height are often observed. In this work, Schottky junctions are fabricated by transferring chemical vapor deposited monolayer graphene onto n-type Si and GaAs substrates. Temperature dependence of the barrier height and ideality factor are obtained by current-voltage measurements between 215 and 350 K. An increase in the zero bias barrier height and decr...

  12. One-cm-thick Si detector at LHe temperature

    Energy Technology Data Exchange (ETDEWEB)

    Braggio, C. [Dipartimento di Fisica, Universita di Ferrara, Via Saragat 1, 44100 Ferrara (Italy)], E-mail: braggio@pd.infn.it; Bressi, G. [INFN, Sez. di Pavia, Via Bassi 6, 27100 Pavia (Italy); Carugno, G. [INFN, Sez. di Padova, Via Marzolo 8, 35131 Padova (Italy); Galeazzi, G. [Laboratori Nazionali di Legnaro, Via dell' Universita 1, 35020 Legnaro (Italy); Serafin, A. [Dipartimento di Fisica, Universita di Padova, Via Marzolo 8, 35131 Padova (Italy)

    2007-10-11

    A silicon p-i-n diode of thickness 1 cm has been studied experimentally at liquid helium temperature. This preliminary study is aimed at the construction of a much bigger detector to detect low energy neutrino events.

  13. One-cm-thick Si detector at LHe temperature

    International Nuclear Information System (INIS)

    Braggio, C.; Bressi, G.; Carugno, G.; Galeazzi, G.; Serafin, A.

    2007-01-01

    A silicon p-i-n diode of thickness 1 cm has been studied experimentally at liquid helium temperature. This preliminary study is aimed at the construction of a much bigger detector to detect low energy neutrino events

  14. 6,7Li + 28Si total reaction cross sections at near barrier energies

    International Nuclear Information System (INIS)

    Pakou, A.; Musumarra, A.; Pierroutsakou, D.; Alamanos, N.; Assimakopoulos, P.A.; Divis, N.; Doukelis, G.; Gillibert, A.; Harissopulos, S.; Kalyva, G.; Kokkoris, M.; Lagoyannis, A.; Mertzimekis, T.J.; Nicolis, N.G.; Papachristodoulou, C.; Perdikakis, G.; Roubos, D.; Rusek, K.; Spyrou, S.; Zarkadas, Ch.

    2007-01-01

    Total reaction cross section measurements for the 6,7 Li + 28 Si systems have been performed at near-barrier energies. The results indicate that, with respect to the potential anomaly at barrier, 6 Li and 7 Li on light targets exhibit similar energy dependence on the imaginary potential. Comparisons are made with 6,7 Li cross sections on light and heavy targets, extracted via previous elastic scattering measurements and also with CDCC calculations. Energy dependent parametrisations are also obtained for total reaction cross sections of 6,7 Li on Si, as well as on any target, at near barrier energies

  15. Study the radiation damage effects in Si microstrip detectors for future HEP experiments

    Energy Technology Data Exchange (ETDEWEB)

    Lalwani, Kavita, E-mail: kavita.phy@mnit.ac.in [Malaviya National Institute of Technology (MNIT) Jaipur, Jaipur-302017 (India); Jain, Geetika; Dalal, Ranjeet; Ranjan, Kirti; Bhardwaj, Ashutosh [University of Delhi (DU), Delhi-110007 (India)

    2016-07-15

    Silicon (Si) detectors are playing a key role in High Energy Physics (HEP) experiments due to their superior tracking capabilities. In future HEP experiments, like upgrade of the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC), CERN, the silicon tracking detectors will be operated in a very intense radiation environment. This leads to both surface and bulk damage in Si detectors, which in turn will affect the operating performance of Si detectors. It is important to complement the measurements of the irradiated Si strip detectors with device simulation, which helps in understanding of both the device behavior and optimizing the design parameters needed for the future Si tracking system. An important ingredient of the device simulation is to develop a radiation damage model incorporating both bulk and surface damage. In this work, a simplified two-trap model is incorporated in device simulation to describe the type-inversion. Further, an extensive simulation of effective doping density as well as electric field profile is carried out at different temperatures for various fluences.

  16. Study the radiation damage effects in Si microstrip detectors for future HEP experiments

    International Nuclear Information System (INIS)

    Lalwani, Kavita; Jain, Geetika; Dalal, Ranjeet; Ranjan, Kirti; Bhardwaj, Ashutosh

    2016-01-01

    Silicon (Si) detectors are playing a key role in High Energy Physics (HEP) experiments due to their superior tracking capabilities. In future HEP experiments, like upgrade of the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC), CERN, the silicon tracking detectors will be operated in a very intense radiation environment. This leads to both surface and bulk damage in Si detectors, which in turn will affect the operating performance of Si detectors. It is important to complement the measurements of the irradiated Si strip detectors with device simulation, which helps in understanding of both the device behavior and optimizing the design parameters needed for the future Si tracking system. An important ingredient of the device simulation is to develop a radiation damage model incorporating both bulk and surface damage. In this work, a simplified two-trap model is incorporated in device simulation to describe the type-inversion. Further, an extensive simulation of effective doping density as well as electric field profile is carried out at different temperatures for various fluences.

  17. SiC detectors to monitor ionizing radiations emitted from nuclear events and plasmas

    Science.gov (United States)

    Torrisi, L.; Cannavò, A.

    2016-09-01

    Silicon Carbide (SiC) semiconductor detectors are increasingly employed in Nuclear Physics for their advantages with respect to traditional silicon (Si). Such detectors show an energy resolution, charge mobility, response velocity and detection efficiency similar to Si detectors. However, the higher band gap (3.26 eV), the lower leakage current (∼10 pA) maintained also at room temperature, the higher radiation hardness and the higher density with respect to Si represent some indisputable advantages characterizing such detectors. The devices can be employed at high temperatures, at high absorbed doses and in the case of high visible light intensities, for example, in plasma, for limited exposition times without damage. Generally SiC Schottky diodes are employed in reverse polarization with an active region depth of the order of 100 µm, purity below 1014 cm-3 and an active area lower than 1 cm2. Measurements in the regime of proportionality with the radiation energy released in the active region and measurements in time-of-flight configuration are employed for nuclear emission events produced at both low and high fluences. Alpha spectra demonstrated an energy resolution of about 1.3% at 5.8 MeV. Radiation emission from laser-generated plasma can be monitored in terms of detected photons, electrons and ions, using the laser pulse as a start signal and the radiation detection as a stop signal, enabling to measure the ion velocity by knowing the target-detector flight distance. SiC spectra acquired in the Messina University laboratories using radioactive ion sources and at the PALS laboratory facility in Prague (Czech Republic) are presented. A preliminary study of the use of SiC detectors, embedded in a water equivalent polymer, as a dosimeter is presented and discussed.

  18. Effect of SiO$_{2}$ passivating layer in segmented silicon planar detectors on the detector response

    CERN Document Server

    Verbitskaya, Elena; Eremin, Vladimir; Golubkov, S; Konkov, K; Roe, Shaun; Ruggiero, G; Sidorov, A; Weilhammer, Peter

    2004-01-01

    Silicon detectors with a fine segmentation (micropixel and microstrip) are the main type of detectors used in the inner trackers of LHC experiments. Due to the high luminosity of the LHC machines they are required to have a fast response to fit the short shaping time of 25 ns and to be radiation hard. Evaluation of silicon microstrip detectors developed for the ATLAS silicon tracker and carried out under collaboration of CERN and PTI has shown the reversal of the pulse polarity in the detector response to short- range radiation. Since the negative signal is of about 30% of the normal positive one, the effect strongly reduces the charge collection efficiency in irradiated detectors. The investigation presents the consideration on the origin of a negative response in Si microstrip detectors and the experimental proof of the model. The study of the effect has been carried out using "baby" strip detectors with a special design: each strip has a window in a metallization, which covers the p/sup +/ implant. The sca...

  19. Evaluation of the barrier capability of Zr-Si films with different substrate temperature for Cu metallization

    International Nuclear Information System (INIS)

    Wang Ying; Cao Fei; Ding Minghui; Shao Lei

    2009-01-01

    Barrier capability of Zr-Si diffusion barriers in Cu metallization has been investigated. Amorphous Zr-Si diffusion barriers were deposited on the Si substrates by RF reactive magnetron sputtering under various substrate temperatures. An increase in substrate temperature results in a slightly decreased deposition rate together with an increase in mass density. An increase in substrate temperature also results in grain growth as deduced from field emission scanning electron microscopy (FE-SEM) micrographs. X-ray diffraction (XRD) spectra and Auger electron spectroscopy (AES) depth profiles for Cu/Zr-Si(RT)/Si and Cu/Zr-Si(300 deg. C)/Si samples subjected to anneal at various temperatures show that the thermal stability was strongly correlated with the deposition temperature (consequently different density and chemical composition etc.) of the Zr-Si barrier layers. ZrSi(300 deg. C) with higher mass density make the Cu/Zr-Si(300 deg. C)/Si sample more stable. The appearance of Cu 3 Si in the Cu/Zr-Si/Si sample is attributed to the failure mechanism which may be associated with the diffusion of Cu and Si via the grain boundaries of the Zr-Si barriers.

  20. Naturally occurring 32 Si and low-background silicon dark matter detectors

    Energy Technology Data Exchange (ETDEWEB)

    Orrell, John L.; Arnquist, Isaac J.; Bliss, Mary; Bunker, Raymond; Finch, Zachary S.

    2018-05-01

    The naturally occurring radioisotope Si-32 represents a potentially limiting background in future dark matter direct-detection experiments. We investigate sources of Si-32 and the vectors by which it comes to reside in silicon crystals used for fabrication of radiation detectors. We infer that the Si-32 concentration in commercial single-crystal silicon is likely variable, dependent upon the specific geologic and hydrologic history of the source (or sources) of silicon “ore” and the details of the silicon-refinement process. The silicon production industry is large, highly segmented by refining step, and multifaceted in terms of final product type, from which we conclude that production of Si-32-mitigated crystals requires both targeted silicon material selection and a dedicated refinement-through-crystal-production process. We review options for source material selection, including quartz from an underground source and silicon isotopically reduced in Si-32. To quantitatively evaluate the Si-32 content in silicon metal and precursor materials, we propose analytic methods employing chemical processing and radiometric measurements. Ultimately, it appears feasible to produce silicon-based detectors with low levels of Si-32, though significant assay method development is required to validate this claim and thereby enable a quality assurance program during an actual controlled silicon-detector production cycle.

  1. Naturally occurring 32Si and low-background silicon dark matter detectors

    Science.gov (United States)

    Orrell, John L.; Arnquist, Isaac J.; Bliss, Mary; Bunker, Raymond; Finch, Zachary S.

    2018-05-01

    The naturally occurring radioisotope 32Si represents a potentially limiting background in future dark matter direct-detection experiments. We investigate sources of 32Si and the vectors by which it comes to reside in silicon crystals used for fabrication of radiation detectors. We infer that the 32Si concentration in commercial single-crystal silicon is likely variable, dependent upon the specific geologic and hydrologic history of the source (or sources) of silicon "ore" and the details of the silicon-refinement process. The silicon production industry is large, highly segmented by refining step, and multifaceted in terms of final product type, from which we conclude that production of 32Si-mitigated crystals requires both targeted silicon material selection and a dedicated refinement-through-crystal-production process. We review options for source material selection, including quartz from an underground source and silicon isotopically reduced in 32Si. To quantitatively evaluate the 32Si content in silicon metal and precursor materials, we propose analytic methods employing chemical processing and radiometric measurements. Ultimately, it appears feasible to produce silicon detectors with low levels of 32Si, though significant assay method development is required to validate this claim and thereby enable a quality assurance program during an actual controlled silicon-detector production cycle.

  2. Characterization of Si pixel detectors of different thickness

    Energy Technology Data Exchange (ETDEWEB)

    Bisogni, M.G.; Boscardin, M.; Dalla Betta, G.F.; Delogu, P.; Fantacci, M.E.; Gregori, P.; Linsalata, S.; Novelli, M. E-mail: marzia.novelli@pi.infn.it; Piemonte, C.; Quattrocchi, M.; Rosso, V.; Stefanini, A.; Zorzi, N.; Zucca, S

    2004-02-01

    Tests on silicon pixel detector in the mammographic energy range have shown good imaging performances so, in order to improve the efficiency in this energy range, we have designed thicker detectors of the p{sup +}/n type. The detectors have been fabricated by ITC-IRST (Trento, Italy) in high resistivity silicon substrates (300 and 525 {mu}m thick). A TCAD simulation work has been carried out to optimize the electric field distribution and to enhance the breakdown voltage. Very low leakage current and high breakdown voltage characteristics have been measured on detectors in preliminary on-wafer tests. After that, detectors have been bump-bonded to a dedicated VLSI electronic chips, realizing an assembly. Choosing the best set-up condition and using a standard mammographic tube, we have acquired a large area image (8x8 cm{sup 2}) of the RMI 156 phantom, recommended for mammographic quality checks. In order to cover the whole surface, we have acquired different images translating the phantom over the assembly. We present some selected results for these assemblies both for the electrical characteristics and for the imaging performances.

  3. Characterization of Si pixel detectors of different thickness

    International Nuclear Information System (INIS)

    Bisogni, M.G.; Boscardin, M.; Dalla Betta, G.F.; Delogu, P.; Fantacci, M.E.; Gregori, P.; Linsalata, S.; Novelli, M.; Piemonte, C.; Quattrocchi, M.; Rosso, V.; Stefanini, A.; Zorzi, N.; Zucca, S.

    2004-01-01

    Tests on silicon pixel detector in the mammographic energy range have shown good imaging performances so, in order to improve the efficiency in this energy range, we have designed thicker detectors of the p + /n type. The detectors have been fabricated by ITC-IRST (Trento, Italy) in high resistivity silicon substrates (300 and 525 μm thick). A TCAD simulation work has been carried out to optimize the electric field distribution and to enhance the breakdown voltage. Very low leakage current and high breakdown voltage characteristics have been measured on detectors in preliminary on-wafer tests. After that, detectors have been bump-bonded to a dedicated VLSI electronic chips, realizing an assembly. Choosing the best set-up condition and using a standard mammographic tube, we have acquired a large area image (8x8 cm 2 ) of the RMI 156 phantom, recommended for mammographic quality checks. In order to cover the whole surface, we have acquired different images translating the phantom over the assembly. We present some selected results for these assemblies both for the electrical characteristics and for the imaging performances

  4. Si and gaas pixel detectors for medical imaging applications

    International Nuclear Information System (INIS)

    Bisogni, M. G.

    2001-01-01

    As the use of digital radiographic equipment in the morphological imaging field is becoming the more and more diffuse, the research of new and more performing devices from public institutions and industrial companies is in constant progress. Most of these devices are based on solid-state detectors as X-ray sensors. Semiconductor pixel detectors, originally developed in the high energy physics environment, have been then proposed as digital detector for medical imaging applications. In this paper a digital single photon counting device, based on silicon and GaAs pixel detector, is presented. The detector is a thin slab of semiconductor crystal where an array of 64 by 64 square pixels, 170- m side, has been built on one side. The data read-out is performed by a VLSI integrated circuit named Photon Counting Chip (PCC), developed within the MEDIPIX collaboration. Each chip cell geometrically matches the sensor pixel. It contains a charge preamplifier, a threshold comparator and a 15 bits pseudo-random counter and it is coupled to the detector by means of bump bonding. Most important advantages of such system, with respect to a traditional X-rays film/screen device, are the wider linear dynamic range (3x104) and the higher performance in terms of MTF and DQE. Besides the single photon counting architecture allows to detect image contrasts lower than 3%. Electronics read-out performance as well as imaging capabilities of the digital device will be presented. Images of mammographic phantoms acquired with a standard Mammographic tube will be compared with radiographs obtained with traditional film/screen systems

  5. Development of an angled Si-PM-based detector unit for positron emission mammography (PEM) system

    Energy Technology Data Exchange (ETDEWEB)

    Nakanishi, Kouhei, E-mail: nakanishi.kouhei@c.mbox.nagoya-u.ac.jp; Yamamoto, Seiichi

    2016-11-21

    Positron emission mammography (PEM) systems have higher sensitivity than clinical whole body PET systems because they have a smaller ring diameter. However, the spatial resolution of PEM systems is not high enough to detect early stage breast cancer. To solve this problem, we developed a silicon photomultiplier (Si-PM) based detector unit for the development of a PEM system. Since a Si-PM's channel is small, Si-PM can resolve small scintillator pixels to improve the spatial resolution. Also Si-PM based detectors have inherently high timing resolution and are able to reduce the random coincidence events by reducing the time window. We used 1.5×1.9×15 mm LGSO scintillation pixels and arranged them in an 8×24 matrix to form scintillator blocks. Four scintillator blocks were optically coupled to Si-PM arrays with an angled light guide to form a detector unit. Since the light guide has angles of 5.625°, we can arrange 64 scintillator blocks in a nearly circular shape (a regular 64-sided polygon) using 16 detector units. We clearly resolved the pixels of the scintillator blocks in a 2-dimensional position histogram where the averages of the peak-to-valley ratios (P/Vs) were 3.7±0.3 and 5.7±0.8 in the transverse and axial directions, respectively. The average energy resolution was 14.2±2.1% full-width at half-maximum (FWHM). By including the temperature dependent gain control electronics, the photo-peak channel shifts were controlled within ±1.5% with the temperature from 23 °C to 28 °C. With these results, in addition to the potential high timing performance of Si-PM based detectors, our developed detector unit is promising for the development of a high-resolution PEM system.

  6. SiGe Intersubband Detectors for Terahertz Communication and Sensing

    National Research Council Canada - National Science Library

    Kolodzey, James

    2003-01-01

    We report on the design and fabrication of THz detectors based on silicon germanium nanostructures grown by MBE to obtain intersubband transitions in the energy range from 4.1 meV to 4.1 meV (1 to 10 THz...

  7. On the use of thin ion implanted Si detectors in heavy ion experiments

    International Nuclear Information System (INIS)

    Lavergne-Gosselin, L.; Stab, L.; Lampert, M.O.

    1988-10-01

    We present test results on the use of thin ion implanted epitaxial Si detectors for registration of low- and medium energy heavy fragments in nuclear reactions. A linear energy response for very low energy nuclei has been observed. A test of 10 μm + 300 μm telescopes under realistic experimental conditions for heavy ion experiments exhibits the possibilities to use these detectors for the measurements of multifragmentation products. (authors)

  8. Si-strip photon counting detectors for contrast-enhanced spectral mammography

    Science.gov (United States)

    Chen, Buxin; Reiser, Ingrid; Wessel, Jan C.; Malakhov, Nail; Wawrzyniak, Gregor; Hartsough, Neal E.; Gandhi, Thulasi; Chen, Chin-Tu; Iwanczyk, Jan S.; Barber, William C.

    2015-08-01

    We report on the development of silicon strip detectors for energy-resolved clinical mammography. Typically, X-ray integrating detectors based on scintillating cesium iodide CsI(Tl) or amorphous selenium (a-Se) are used in most commercial systems. Recently, mammography instrumentation has been introduced based on photon counting Si strip detectors. The required performance for mammography in terms of the output count rate, spatial resolution, and dynamic range must be obtained with sufficient field of view for the application, thus requiring the tiling of pixel arrays and particular scanning techniques. Room temperature Si strip detector, operating as direct conversion x-ray sensors, can provide the required speed when connected to application specific integrated circuits (ASICs) operating at fast peaking times with multiple fixed thresholds per pixel, provided that the sensors are designed for rapid signal formation across the X-ray energy ranges of the application. We present our methods and results from the optimization of Si-strip detectors for contrast enhanced spectral mammography. We describe the method being developed for quantifying iodine contrast using the energy-resolved detector with fixed thresholds. We demonstrate the feasibility of the method by scanning an iodine phantom with clinically relevant contrast levels.

  9. Development of SiC Neutron Detector Assembly to Measure the Neutron Flux of the Reactor Core

    Energy Technology Data Exchange (ETDEWEB)

    Park, Se Hwan; Park, June Sic; Shin, Hee Sung; Kim, Ho Dong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Yong Kyun [Hanyang University, Seoul (Korea, Republic of)

    2012-05-15

    At present, the conventional detector to measure the neutron at harsh environment is a Self Powered Neutron Detector (SPND). Rhodium(Rh)-103 is in the SPND. When neutron is incident on the Rhodium, the neutron capture reaction occurs, and the Rh-103 is converted to Rh-104. The Rh-104 is decayed to Pd-104 by {beta}-decay, and electrons are generated as the decay products. Because of the half life of Rh-104, approximately 5 minutes are required for the SPND output to reach the equilibrium condition. Therefore the on-line monitoring of the nuclear reactor state is limited if the neutron flux in the reactor core is monitored with the SPND. Silicon carbide (SiC) has the possibility to be developed as neutron detector at harsh environment, because the SiC can be operative at high temperature and high neutron flux conditions. Previously, the basic operation properties of the SiC detector were studied. Also, the radiation response of the SiC detector was studied at high neutron and gamma dose rate. The measurement results for an ex-core neutron flux monitor or a neutron flux monitor of the spent fuel were published. The SiC detector was also developed as neutron detector to measure the fissile material with active interrogation method. However, the studies about the development of SiC detector are still limited. In the present work, the radiation damage effect of the SiC detector was studied. The detector structure was determined based on the study, and a neutron detector assembly was made with the SiC detectors. The neutron and gamma-ray response of the detector assembly is presented in this paper. The detector assembly was positioned in the HANARO research reactor core, the performance test was done. The preliminary results are also included in this paper

  10. Characterisation of SI Detectors for the Use at 2 K*

    CERN Document Server

    Bartosik, M; Eisel, T; Kurfuerst, C; Rementeria, C; Sapinski, M; Eremin, V; Verbitskaya, E

    2013-01-01

    It is expected that the luminosity of the Large Hadron Collider (LHC) will be bounded in the future by the beam loss limits of the superconducting magnets. To protect the superconducting magnets of the high luminosity insertions an optimal detection of the energy deposition by the shower of beam particles is necessary. Therefore beam Loss Monitors (BLM) need to be placed close to the particle impact location in the cold mass of the magnets where they should operate in superfluid helium at 1.9 Kelvin. To choose optimal detectors n-type silicon wafers have been examined at superfluid helium temperature whilst under irradiation from a high intensity proton beam. The radiation hardness and leakage current of these detectors were found to be significantly improved at 1.9 Kelvin when compared to their operation at room temperature.

  11. Beta-spectrometer with Si-detectors for the study of 144Ce-144Pr decays

    Science.gov (United States)

    Alexeev, I. E.; Bakhlanov, S. V.; Bazlov, N. V.; Chmel, E. A.; Derbin, A. V.; Drachnev, I. S.; Kotina, I. M.; Muratova, V. N.; Pilipenko, N. V.; Semyonov, D. A.; Unzhakov, E. V.; Yeremin, V. K.

    2018-05-01

    Here we present the specifications of a newly developed beta-spectrometer, based on full absorption Si(Li) detector and thin transmission detector, allowing one to perform efficient separation beta-radiation and accompanying X-rays and gamma radiation. Our method is based on registration of coincident events from both detectors. The spectrometer can be used for precision measurements of various beta-spectra, namely for the beta-spectrum shape study of 144Pr, which is considered to be an advantageous anti-neutrino source for sterile neutrino searches.

  12. Detector block based on arrays of 144 SiPMs and monolithic scintillators: A performance study

    International Nuclear Information System (INIS)

    González, A.J.; Conde, P.; Iborra, A.; Aguilar, A.; Bellido, P.; García-Olcina, R.; Hernández, L.; Moliner, L.; Rigla, J.P.; Rodríguez-Álvarez, M.J.; Sánchez, F.; Seimetz, M.; Soriano, A.; Torres, J.; Vidal, L.F.; Benlloch, J.M.

    2015-01-01

    We have developed a detector block composed by a monolithic LYSO scintillator coupled to a custom made 12×12 SiPMs array. The design is mainly focused to applications such as Positron Emission Tomography. The readout electronics is based on 3 identical and scalable Application Specific Integrated Circuits (ASIC). We have determined the main performance of the detector block namely spatial, energy, and time resolution but also the system capability to determine the photon depth of interaction, for different crystal surface treatments. Intrinsic detector spatial resolution values as good as 1.7 mm FWHM and energies of 15% for black painted crystals were measured

  13. An improved fabrication process for Si-detector-compatible JFETs

    International Nuclear Information System (INIS)

    Piemonte, Claudio; Dalla Betta, Gian-Franco; Boscardin, Maurizio; Gregori, Paolo; Zorzi, Nicola; Ratti, Lodovico

    2006-01-01

    We report on JFET devices fabricated on high-resistivity silicon with a radiation detector technology. The problems affecting previous versions of these devices have been thoroughly investigated and solved by developing an improved fabrication process, which allows for a sizeable enhancement in the JFET performance. In this paper, the main features of the fabrication technology are presented and selected results from the electrical and noise characterization of transistors are discussed

  14. Time Of Flight Detectors: From phototubes to SiPM

    International Nuclear Information System (INIS)

    Laurenti, G.; Levi, G.; Foschi, E.; Guandalini, C.; Quadrani, L.; Sbarra, C.; Zuffa, M.

    2008-01-01

    A sample of Silicon Photomultipliers was tested because they looked promising for future space missions: low consumption, low weight, resistance to radiation damage and insensitivity to magnetic fields. They have been studied in laboratory by means of the same characterization methods adopted to calibrate the fine mesh photomultipliers used by the Time Of Flight of the AMS-02 experiment. A detailed simulation was made to reproduce the SiPM response to the various experimental conditions. A possible counter design has been studied with front end electronics card equipped with SiPMs and Peltier cell for thermoregulation. A proper simulation based on COMSOL Multiphysics package reproduces quite well the Peltier cell nominal cooling capability

  15. Physics of Schottky-barrier change by segregation and structural disorder at metal/Si interfaces: First-principles study

    International Nuclear Information System (INIS)

    Nakayama, T.; Kobinata, K.

    2012-01-01

    Schottky-barrier changes by the segregation and structural disorder are studied using the first-principles calculations and adopting Au/Si interface. The Schottky barrier for electrons simply decreases as increasing the valency of segregated atoms from II to VI families, which variation is shown closely related to how the Si atoms are terminated at the interface. On the other hand, the structural disorders (defects) prefer to locate near the interface and the Schottky barrier for hole carriers does not change in cases of Si vacancy and Au substitution, while it increases in cases of Si and Au interstitials reflecting the appearance of Si dangling bonds.

  16. SPICE evaluation of the S/N ratio for Si microstrip detectors

    International Nuclear Information System (INIS)

    Candelori, A.; Paccagnella, A.; Padova Univ.; Nardi, F.

    1999-01-01

    SPICE simulations of AC-coupled single-sided Si microstrip detectors connected to the Pre-Shape 32 read-out chip have been performed in order to determine the geometrical characteristics which maximize the signal-to-noise ratio at room temperature. All the resistive and capacitive elements of the detector have been determined as a function of the ω/ρ ratio, by considering experimental and simulated data available in the literature. The SPICE model takes into account all the main noise source in the detector and read-out electronics. The minimum ionizing particle current signal shape characteristics have been introduced in the simulations. Two read-out configurations have been investigated for 6.4 cm and 12.8 cm long detectors. Finally, general guidelines in the detector design have been proposed starting from the simulation results

  17. The influence of fast neutron irradiation on the noise properties of silicon surface-barrier detectors

    International Nuclear Information System (INIS)

    Dabrowski, W.; Korbel, K.

    1988-01-01

    The susceptibility to the fast neutron irradiation of silicon surface-barrier detectors has been investigated. It was shown that the 1/f-noise decreases substantially with increasing fluence in the range from 10 10 n/cm 2 to 10 11 n/cm 2 . The deterioration of the detector performance is caused mainly by the positively-charged defects induced by the radiation. The critical value of the neutron fluence, at which the detector performance begins to be worsened was also determined. 5 refs., 5 figs. (author)

  18. Fabrication and characterization of surface barrier detector from commercial silicon substrate

    International Nuclear Information System (INIS)

    Silva, Julio Batista Rodrigues

    2016-01-01

    In this work it was developed radiation detectors silicon surface barrier that were capable of detecting the presence of gamma radiation from a low energy of iodine-125 seeds used in brachytherapy treatments. >From commercial silicon substrates detectors were developed, one sequence left of chemical treatments to the surfaces of these substrates with the intention of minimizing the possible noise generated, validation of the samples obtained as diodes, ensuring detector characteristics and effective use as detector for Iodine-125 radioactive sources with energy of about 25 keV and Americium-251 with energy on the order of 59 keV. Finished performing the analysis of the obtained energy spectra and so it was possible to observe the ability of these detectors to measure the energy from these seeds. (author)

  19. Investigation of temperature dependent barrier height of Au/ZnO/Si schottky diodes

    International Nuclear Information System (INIS)

    Asghar, M.; Mahmood, K.; Rabia, S.; BM, S.; Shahid, M. Y.; Hasan, M. A.

    2013-01-01

    In this study, temperature dependent current-voltage (I-V) measurements have been performed to investigate the inhomogeneity in the temperature dependent barrier heights of Au/ZnO/Si Schottky barrier diode in the temperature range 150 - 400K. The room temperature values for ideality factor and barrier height were found to be 2.9 and 0.60 eV respectively indicating the inhomogenity in the barrier heights of grown samples. The Richardson plot and ideality factor verses barrier height graph were also drawn to verified the discontinuity between Au and ZnO. This barrier height inhomogenity was explained by applying Gaussian distribution model. The extrapolation of the linear Fap (n) plot to n= 1 has given a homogeneous barrier height of approximately 1.1 eV. Fap versus 1/T plot was drawn to obtain the values of mean barrier height for Au/ZnO/Si Schottky diode (1.1 eV) and standard deviation(ds) (0.02 V) at zero bais. (author)

  20. Investigation of temperature dependent barrier height of Au/ZnO/Si schottky diodes

    International Nuclear Information System (INIS)

    Asghar, M; Mahmood, K; Rabia, S; M, Samaa B; Shahid, M Y; Hasan, M A

    2014-01-01

    In this study, temperature dependent current-voltage (I-V) measurements have been performed to investigate the inhomogeneity in the temperature dependent barrier heights of Au/ZnO/Si Schottky barrier diode in the temperature range 150 – 400K. The room temperature values for ideality factor and barrier height were found to be 2.9 and 0.60 eV respectively indicating the inhomogenity in the barrier heights of grown samples. The Richardson plot and ideality factor verses barrier height graph were also drawn to verified the discontinuity between Au and ZnO. This barrier height inhomogenity was explained by applying Gaussian distribution model. The extrapolation of the linear Φ ap (n) plot to n= 1 has given a homogeneous barrier height of approximately 1.1 eV. Φ ap versus 1/T plot was drawn to obtain the values of mean barrier height for Au/ZnO/Si Schottky diode (1.1 eV) and standard deviation(δ s ) (0.02 V) at zero bais

  1. X-ray escape effects in Si, Ge, and NaI detectors

    International Nuclear Information System (INIS)

    Brunner, G.

    1989-01-01

    A 3-parameter representation of the type x = K 1 [1 -L(ln(1 + 1/L))] together with L = K 2 E K 3 is recommended for the escape to parent peak ratio. Parameter values are provided for Si, Ge, and NaI detectors. Scattering, which has been neglected up to now, is included. (author)

  2. A novel, SiPM-array-based, monolithic scintillator detector for PET

    NARCIS (Netherlands)

    Schaart, Dennis R.; van Dam, Herman T.; Seifert, Stefan; Vinke, Ruud; Dendooven, Peter; Beekman, Freek J.; Löhner, H.

    2009-01-01

    Silicon photomultipliers (SiPMs) are of great interest to positron emission tomography (PET), as they enable new detector geometries, for e. g., depth-of-interaction (DOI) determination, are MR compatible, and offer faster response and higher gain than other solid-state photosensors such as

  3. Development of Si-based detectors for intermediate energy heavy-ion physics at a storage-ring accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Whitlow, H.J.; Jaworowski, J.; Leandersson, M.; El Bouanani, M. [Lund Institute of Technology, Solvegatan Lund, (Sweden). Department of Nuclear Physics; Jakobsson, B. [Lund Univ. (Sweden). Dept. of Cosmic and Subatomic Physics; Romanski, J.; Westerberg, L.; Van Veldhuizen, E.J. [Uppsala Univ. (Sweden); The Chicsi Collaboration

    1996-12-31

    Ultrahigh vacuum (UHV) compatible Si detectors are being developed by the CELSIUS Heavy lon Collaboration (CHIC) for measuring the energy and identity of Intermediate Mass Fragments (IMF) with Z {approx} 3 - 12 and energies of 0.7 - I 0 A MeV. Here we give an overview of the development of Si {delta}E-E detector telescopes and investigations on IMF identification based on the pulse shape from Si-detectors where the particles impinge on the rear-face of the detector. 9 refs., 4 figs.

  4. Development of Si-based detectors for intermediate energy heavy-ion physics at a storage-ring accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Whitlow, H J; Jaworowski, J; Leandersson, M; El Bouanani, M [Lund Institute of Technology, Solvegatan Lund, (Sweden). Department of Nuclear Physics; Jakobsson, B [Lund Univ. (Sweden). Dept. of Cosmic and Subatomic Physics; Romanski, J; Westerberg, L; Van Veldhuizen, E J [Uppsala Univ. (Sweden); The Chicsi Collaboration

    1997-12-31

    Ultrahigh vacuum (UHV) compatible Si detectors are being developed by the CELSIUS Heavy lon Collaboration (CHIC) for measuring the energy and identity of Intermediate Mass Fragments (IMF) with Z {approx} 3 - 12 and energies of 0.7 - I 0 A MeV. Here we give an overview of the development of Si {delta}E-E detector telescopes and investigations on IMF identification based on the pulse shape from Si-detectors where the particles impinge on the rear-face of the detector. 9 refs., 4 figs.

  5. Aerospace Ceramic Materials: Thermal, Environmental Barrier Coatings and SiC/SiC Ceramic Matrix Composites for Turbine Engine Applications

    Science.gov (United States)

    Zhu, Dongming

    2018-01-01

    Ceramic materials play increasingly important roles in aerospace applications because ceramics have unique properties, including high temperature capability, high stiffness and strengths, excellent oxidation and corrosion resistance. Ceramic materials also generally have lower densities as compared to metallic materials, making them excellent candidates for light-weight hot-section components of aircraft turbine engines, rocket exhaust nozzles, and thermal protection systems for space vehicles when they are being used for high-temperature and ultra-high temperature ceramics applications. Ceramic matrix composites (CMCs), including non-oxide and oxide CMCs, are also recently being incorporated in gas turbine engines for high pressure and high temperature section components and exhaust nozzles. However, the complexity and variability of aerospace ceramic processing methods, compositions and microstructures, the relatively low fracture toughness of the ceramic materials, still remain the challenging factors for ceramic component design, validation, life prediction, and thus broader applications. This ceramic material section paper presents an overview of aerospace ceramic materials and their characteristics. A particular emphasis has been placed on high technology level (TRL) enabling ceramic systems, that is, turbine engine thermal and environmental barrier coating systems and non-oxide type SiC/SiC CMCs. The current status and future trend of thermal and environmental barrier coatings and SiC/SiC CMC development and applications are described.

  6. First Compton telescope prototype based on continuous LaBr3-SiPM detectors

    International Nuclear Information System (INIS)

    Llosá, G.; Cabello, J.; Callier, S.; Gillam, J.E.; Lacasta, C.; Rafecas, M.; Raux, L.; Solaz, C.; Stankova, V.; La Taille, C. de; Trovato, M.; Barrio, J.

    2013-01-01

    A first prototype of a Compton camera based on continuous scintillator crystals coupled to silicon photomultiplier (SiPM) arrays has been successfully developed and operated. The prototype is made of two detector planes. The first detector is made of a continuous 16×18×5 mm 3 LaBr 3 crystal coupled to a 16-elements SiPM array. The elements have a size of 3×3 mm 3 in a 4.5×4.05 mm 2 pitch. The second detector, selected by availability, consists of a continuous 16×18×5 mm 3 LYSO crystal coupled to a similar SiPM array. The SPIROC1 ASIC is employed in the readout electronics. Data have been taken with a 22 Na source placed at different positions and images have been reconstructed with the simulated one-pass list-mode (SOPL) algorithm. Detector development for the construction of a second prototype with three detector planes is underway. LaBr 3 crystals of 32×36 mm 2 size and 5/10 mm thickness have been acquired and tested with a PMT. The resolution obtained is 3.5% FWHM at 511 keV. Each crystal will be coupled to four MPPC arrays. Different options are being tested for the prototype readout

  7. Durability and CMAS Resistance of Advanced Environmental Barrier Coatings Systems for SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming

    2015-01-01

    Environmental barrier coatings (EBCs) and SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. This paper will emphasize advanced environmental barrier coating developments for SiCSiC turbine airfoil components, by using advanced coating compositions and processing, in conjunction with mechanical and environment testing and durability validations. The coating-CMC degradations and durability in the laboratory simulated engine fatigue-creep and complex operating environments are being addressed. The effects of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the degradation mechanisms of the environmental barrier coating systems will be discussed. The results help understand the advanced EBC-CMC system performance, aiming at the durability improvements of more robust, prime-reliant environmental barrier coatings for successful applications of the component technologies and lifing methodologies.

  8. A conductive surface coating for Si-CNT radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Valentini, Antonio, E-mail: antonio.valentini@ba.infn.it [Dipartimento di Fisica, Università degli Studi di Bari, Via Orabona 4, 70125 Bari (Italy); Valentini, Marco [INFN, Sezione di Bari, Via Orabona 4, 70126 Bari (Italy); Ditaranto, Nicoletta [Dipartimento di Chimica, Università degli Studi di Bari, Via Amendola 173, 70126 Bari (Italy); Melisi, Domenico [INFN, Sezione di Bari, Via Orabona 4, 70126 Bari (Italy); Aramo, Carla, E-mail: aramo@na.infn.it [INFN, Sezione di Napoli, Via Cintia 2, 80126 Napoli (Italy); Ambrosio, Antonio [CNR-SPIN U.O.S. di Napoli and Dipartimento di Scienze Fisiche, Università degli Studi di Napoli “Federico II”, Via Cintia 2, 80126 Napoli (Italy); Casamassima, Giuseppe [Dipartimento di Fisica, Università degli Studi di Bari, Via Orabona 4, 70125 Bari (Italy); INFN, Sezione di Bari, Via Orabona 4, 70126 Bari (Italy); Cilmo, Marco [INFN, Sezione di Napoli, and Dipartimento di Scienze Fisiche, Università degli Studi di Napoli “Federico II”, Via Cintia 2, 80126 Napoli (Italy); Fiandrini, Emanuele [INFN, Sezione di Perugia, and Dipartimento di Fisica, Università degli Studi di Perugia, Piazza Università 1, 06100 Perugia (Italy); Grossi, Valentina [INFN, Sezione di L’Aquila, and Dipartimento di Scienze Fisiche e Chimiche, Università degli Studi dell’Aquila, Via Vetoio 10 Coppito, 67100 L’Aquila (Italy); and others

    2015-08-01

    Silicon–Carbon Nanotube radiation detectors need an electrically conductive coating layer to avoid the nanotube detachment from the silicon substrate and uniformly transmit the electric field to the entire nanotube active surface. Coating material must be transparent to the radiation of interest, and must provide the drain voltage necessary to collect charges generated by incident photons. For this purpose various materials have been tested and proposed in photodetector and photoconverter applications. In this article interface properties and electrical contact behavior of Indium Tin Oxide films on Carbon Nanotubes have been analyzed. Ion Beam Sputtering has been used to grow the transparent conductive layer on the nanotubes. The films were deposited at room temperature with Oxygen/Argon mixture into the sputtering beam, at fixed current and for different beam energies. Optical and electrical analyses have been performed on films. Surface chemical analysis and in depth profiling results obtained by X-ray Photoelectron Spectroscopy of the Indium Tin Oxide layer on nanotubes have been used to obtain the interface composition. Results have been applied in photodetectors realization based on multi wall Carbon Nanotubes on silicon. - Highlights: • ITO was deposited by Ion Beam Sputtering on MWCNT. • ITO on CNT makes an inter-diffusion layer of the order of one hundred nanometers. • Improvements of quantum efficiency of photon detectors based on CNT with ITO.

  9. Improved charge collection of the buried p-i-n a-Si:H radiation detectors

    International Nuclear Information System (INIS)

    Fujieda, I.; Cho, G.; Conti, M.; Drewery, J.; Kaplan, S.N.; Perez-Mendez, V.; Qureshi, S.; Street, R.A.

    1989-09-01

    Charge collection in hydrogenated amorphous silicon (a-Si:H) radiation detectors is improved for high LET particle detection by adding thin intrinsic layers to the usual p-i-n structure. This buried p-i-n structure enables us to apply higher bias and the electric field is enhanced. When irradiated by 5.8 MeV α particles, the 5.7 μm thick buried p-i-n detector with bias 300V gives a signal size of 60,000 electrons, compared to about 20,000 electrons with the simple p-i-n detectors. The improved charge collection in the new structure is discussed. The capability of tailoring the field profile by doping a-Si:H opens a way to some interesting device structures. 17 refs., 7 figs

  10. Optical transitions in Ge/SiGe multiple quantum wells with Ge-rich barriers

    Science.gov (United States)

    Bonfanti, M.; Grilli, E.; Guzzi, M.; Virgilio, M.; Grosso, G.; Chrastina, D.; Isella, G.; von Känel, H.; Neels, A.

    2008-07-01

    Direct-gap and indirect-gap transitions in strain-compensated Ge/SiGe multiple quantum wells with Ge-rich SiGe barriers have been studied by optical transmission spectroscopy and photoluminescence experiments. An sp3d5s∗ tight-binding model has been adopted to interpret the experimental results. Photoluminescence spectra and their comparison with theoretical calculations prove the existence of type-I band alignment in compressively strained Ge quantum wells grown on relaxed Ge-rich SiGe buffers. The high quality of the transmission spectra opens up other perspectives for application of these structures in near-infrared optical modulators.

  11. Comparison of bulk and epitaxial 4H-SiC detectors for radiation hard particle tracking

    CERN Document Server

    Quinn, T; Bruzzi, M; Cunningham, W; Mathieson, K; Moll, M; Nelson, T; Nilsson, H E; Pintillie, I; Rahman, M; Reynolds, L; Sciortino, S; Sellin, P J; Strachan, H; Svensson, B G; Vaitkus, J

    2003-01-01

    Measurements and simulations have been carried out using bulk and epitaxial SiC detectors. Samples were irradiated to fluences of around 10**1**4 hardrons/cm**2. Material of thickness 40um gave a charge collection efficiency of 100% dropping to around 60% at 100mum thickness. Detailed MEDICI simulations incorporated the main defect levels in SiC, the vanadium center, Z-center and a mid-gap level as measured by deep level transient spectroscopy and other techniques. Calculated recombination currents and charge collection efficiencies at varying fluences were comparable to experimental data. The study suggests that SiC detectors will operate up to fluences around 10 **1**6/cm**2 as required by future particle physics experiments.

  12. Stress-directed compositional patterning of SiGe substrates for lateral quantum barrier manipulation

    International Nuclear Information System (INIS)

    Ghosh, Swapnadip; Kaiser, Daniel; Sinno, Talid; Bonilla, Jose; Han, Sang M.

    2015-01-01

    While vertical stacking of quantum well and dot structures is well established in heteroepitaxial semiconductor materials, manipulation of quantum barriers in the lateral directions poses a significant engineering challenge. Here, we demonstrate lateral quantum barrier manipulation in a crystalline SiGe alloy using structured mechanical fields to drive compositional redistribution. To apply stress, we make use of a nano-indenter array that is pressed against a Si 0.8 Ge 0.2 wafer in a custom-made mechanical press. The entire assembly is then annealed at high temperatures, during which the larger Ge atoms are selectively driven away from areas of compressive stress. Compositional analysis of the SiGe substrates reveals that this approach leads to a transfer of the indenter array pattern to the near-surface elemental composition, resulting in near 100% Si regions underneath each indenter that are separated from each other by the surrounding Si 0.8 Ge 0.2 bulk. The “stress transfer” process is studied in detail using multiscale computer simulations that demonstrate its robustness across a wide range of applied stresses and annealing temperatures. While the “Si nanodot” structures formed here are not intrinsically useful as quantum structures, it is anticipated that the stress transfer process may be modified by judicious control of the SiGe film thickness and indenter array pattern to form more technologically useful structures

  13. Fabrication of 4H-SiC Schottky barrier diodes with high breakdown voltages

    CERN Document Server

    Kum, B H; Shin, M W; Park, J D

    1999-01-01

    This paper discusses the fabrication and the breakdown characteristics of 4H-SiC Schottky barrier diodes (SBDs). Optimal processing conditions for the ohmic contacts were extracted using the transmission-line method (TLM) and were applied to the device fabrication. The Ti/4H-SiC SBDs with Si sub x B sub y passivation showed a maximum reverse breakdown voltage of 268 V with a forward current density as high as 70 mA/cm sup 2 at a forward voltage of 2 V. The breakdown of the Pt. 4H-SiC SBDs without any passivation occurred at near 110 V. It is concluded that the breakdown enhancement in the Ti/4H-SiC SBDs can be attributed to the passivation; otherwise, excess surface charge near the edge of the Schottky contact would lead to electric fields of sufficient magnitude to cause field emission.

  14. Large area, low capacitance Si(Li) detectors for high rate x-ray applications

    International Nuclear Information System (INIS)

    Rossington, C.S.; Fine, P.M.; Madden, N.W.

    1992-10-01

    Large area, single-element Si(Li) detectors have been fabricated using a novel geometry which yields detectors with reduced capacitance and hence reduced noise at short amplifier pulse-processing times. A typical device employing the new geometry with a thickness of 6 mm and an active area of 175 mm 2 has a capacitance of only 0.5 pf, compared to 2.9 pf for a conventional planar device with equivalent dimensions. These new low capacitance detectors, used in conjunction with low capacitance field effect transistors, will result in x-ray spectrometers capable of operating at very high count rates while still maintaining excellent energy resolution. The spectral response of the low capacitance detectors to a wide range of x-ray energies at 80 K is comparable to typical state-of-the-art conventional Si(Li) devices. In addition to their low capacitance, the new devices offer other advantages over conventional detectors. Detector fabrication procedures, I-V and C-V characteristics, noise performance, and spectral response to 2-60 keV x-rays are described

  15. Tunneling Characteristics Depending on Schottky Barriers and Diffusion Current in SiOC.

    Science.gov (United States)

    Oh, Teresa; Kim, Chy Hyung

    2016-02-01

    To obtain a diffusion current in SiOC, the aluminum doped zinc oxide films were deposited on SiOC/Si wafer by a RF magnetron sputtering. All the X-ray patterns of the SiOC films showed amorphous phases. The level of binding energy of Si atoms will lead to an additional potential modulation by long range Coulombic and covalent interactions with oxygen ions. The growth of the AZO film was affected by the characteristics of SiOC, resulting in similar trends in XPS spectra and a shift to higher AZO lattice d values than the original AZO d values in XRD analyses. The charges trapped by the defects at the interlayer between AZO and SiOC films induced the decreased mobility of carriers. In the absence of trap charges, AZO grown on SiOC film such as the sample prepared at O2 = 25 or 30 sccm, which has low charge carrier concentration and high mobility, showed high mobility in an ambipolar characteristic of oxide semiconductor due to the tunneling effect and diffusion current. The structural matching of an interface between AZO and amorphous SiOC enhanced the height of Schottky Barrier (SB), and then the mobility was increased by the tunneling effect from band to band through the high SB.

  16. Asymmetry of characteristic X-ray peaks obtained by a Si(Li) detector

    Energy Technology Data Exchange (ETDEWEB)

    Visnovezky, Claudia [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000, Cordoba (Argentina)], E-mail: cavy3@hotmail.com; Limandri, Silvina [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000, Cordoba (Argentina)], E-mail: silvilimandri@hotmail.com; Canafoglia, Maria Elena [Centro de Investigacion y Desarrollo en Ciencias Aplicadas Dr. Jorge Ronco, Calle 47 No 257, 1900 La Plata, Argentina, Facultad de Ciencias Exactas y Facultad de Ingenieria de la UNLP, La Plata (Argentina); Bonetto, Rita [Centro de Investigacion y Desarrollo en Ciencias Aplicadas Dr. Jorge Ronco, Calle 47 No 257, 1900 La Plata, Argentina, Facultad de Ciencias Exactas y Facultad de Ingenieria de la UNLP, La Plata (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina (Argentina)], E-mail: bonetto@quimica.unlp.edu.ar; Trincavelli, Jorge [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000, Cordoba (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina (Argentina)], E-mail: jorge@quechua.fis.uncor.edu

    2007-05-15

    The asymmetry of the characteristic X-ray peaks obtained using a Si(Li) detector is mainly due to incomplete charge collection. Impurities and defects in the crystalline structure of Si can act as 'traps' for holes and electrons in their trip toward the detector electrodes. Therefore, the collected charge, and consequently the detected energy, is smaller than the expected one. The global effect is that peaks may present a 'tail' toward the low energy side. This phenomenon is more important for low energies (lower than 2.3 keV, in the case of the detector characterized). In this work, the parameters related to peak asymmetry were studied, allowing a better understanding of the trapping process mentioned above. For this purpose, spectra from mono- and multi-element samples were collected for elements with atomic number between 7 and 20. In order to describe the shape of the characteristic K peaks as a function of its energy, an asymmetric correction to a Gaussian function was proposed. Spectra were obtained by electron probe microanalysis for incidence energies between 5 and 25 keV using an energy dispersive spectrometer equipped with an ultra-thin window Si(Li) detector. It was observed that the area corresponding to the asymmetric correction exhibits an energy dependence similar to that of the mass absorption coefficient of the detector material. In addition, other two spectrometers were used to investigate the dependence of tailing on the detection system. When two spectrometers with the same kind of detector and different pulse processors were compared, peaks were more asymmetric for lower peaking time values. When two different detectors were used, differences were even more important.

  17. P-type silicon surface barrier detector used for x-ray dosimetry

    International Nuclear Information System (INIS)

    Yamamoto, Hisao; Hatakeyama, Satoru; Norimura, Toshiyuki; Tsuchiya, Takehiko

    1983-01-01

    Responses to X-rays of a P-type surface barrier detector fabricated in our laboratory were studied, taking into consideration the dependence on the temperature in order to examine its applicability to dosimetry of short-range radiation. The study was also made in the case of N-type surface barrier detector. At room temperature, the short-circuit current increased linearly with exposure dose rate (15 - 50 R/min) for N- and P-type detectors. The open-circuit voltage showed a nonlinear dependence. With increasing temperature, the short-circuit current for the N-type detector was approximately constant up to 30 0 C and then decreased, though the open-circuit voltage decreased linearly. For the P- type detector, both open-circuit voltage and short-circuit current decreased almost linearly with increasing temperature. While a P-type detector is still open to some improvements, these results indicate that it can be used as a dosimeter. (author)

  18. Electrical characteristics of schottky barriers on 4H-SiC: The effects of barrier height nonuniformity

    Science.gov (United States)

    Skromme, B. J.; Luckowski, E.; Moore, K.; Bhatnagar, M.; Weitzel, C. E.; Gehoski, T.; Ganser, D.

    2000-03-01

    Electrical properties, including current-voltage (I-V) and capacitance-voltage (C-V) characteristics, have been measured on a large number of Ti, Ni, and Pt-based Schottky barrier diodes on 4H-SiC epilayers. Various nonideal behaviors are frequently observed, including ideality factors greater than one, anomalously low I-V barrier heights, and excess leakage currents at low forward bias and in reverse bias. The nonidealities are highly nonuniform across individual wafers and from wafer to wafer. We find a pronounced linear correlation between I-V barrier height and ideality factor for each metal, while C-V barrier heights remain constant. Electron beam induced current (EBIC) imaging strongly suggests that the nonidealities result from localized low barrier height patches. These patches are related to discrete crystal defects, which become visible as recombination centers in the EBIC images. Alternative explanations involving generation-recombination current, uniform interfacial layers, and effects related to the periphery are ruled out.

  19. SiPM application for a detector for UHE neutrinos tested at Sphinx station

    International Nuclear Information System (INIS)

    Iori, M.; Atakisi, I.O.; Chiodi, G.; Denizli, H.; Ferrarotto, F.; Kaya, M.; Yilmaz, A.; Recchia, L.; Russ, J.

    2014-01-01

    We present the preliminary test results of the prototype detector, working at Sphinx Observatory Center, Jungfraujoch (∼3800 m a.s.l.) HFSJG – Switzerland. This prototype detector is designed to measure large zenith angle showers produced by high energy neutrino interactions in the Earth crust. This station provides us an opportunity to understand if the prototype detector works safely (or not) under hard environmental conditions (the air temperature changes between −25 °C and −5 °C). The detector prototype is using silicon photomultiplier (SiPM) produced by SensL and DRS4 chip as read-out part. Measurements at different temperature at fixed bias voltage (∼29.5 V) were performed to reconstruct tracks by Time Of Flight

  20. SiPM application for a detector for UHE neutrinos tested at Sphinx station

    Science.gov (United States)

    Iori, M.; Atakisi, I. O.; Chiodi, G.; Denizli, H.; Ferrarotto, F.; Kaya, M.; Yilmaz, A.; Recchia, L.; Russ, J.

    2014-04-01

    We present the preliminary test results of the prototype detector, working at Sphinx Observatory Center, Jungfraujoch (~3800 m a.s.l.) HFSJG - Switzerland. This prototype detector is designed to measure large zenith angle showers produced by high energy neutrino interactions in the Earth crust. This station provides us an opportunity to understand if the prototype detector works safely (or not) under hard environmental conditions (the air temperature changes between -25 °C and -5 °C). The detector prototype is using silicon photomultiplier (SiPM) produced by SensL and DRS4 chip as read-out part. Measurements at different temperature at fixed bias voltage (~29.5 V) were performed to reconstruct tracks by Time Of Flight.

  1. SiPM application for a detector for UHE neutrinos tested at Sphinx station

    Energy Technology Data Exchange (ETDEWEB)

    Iori, M. [Sapienza University of Rome, Piazzale A. Moro 5, 00185 Rome (Italy); Atakisi, I.O. [University of Kafkas, 36100 Kars (Turkey); Chiodi, G. [INFN, Sezione Roma 1, Piazzale A. Moro 2, 00185 Rome (Italy); Denizli, H. [Abant Izzet Baysal University, 14280 Bolu (Turkey); Ferrarotto, F. [INFN, Sezione Roma 1, Piazzale A. Moro 2, 00185 Rome (Italy); Kaya, M. [University of Kafkas, 36100 Kars (Turkey); Yilmaz, A. [Abant Izzet Baysal University, 14280 Bolu (Turkey); Recchia, L. [INFN, Sezione Roma 1, Piazzale A. Moro 2, 00185 Rome (Italy); Russ, J. [Carnegie-Mellon University, Pittsburgh, PA 15213 (United States)

    2014-04-01

    We present the preliminary test results of the prototype detector, working at Sphinx Observatory Center, Jungfraujoch (∼3800 m a.s.l.) HFSJG – Switzerland. This prototype detector is designed to measure large zenith angle showers produced by high energy neutrino interactions in the Earth crust. This station provides us an opportunity to understand if the prototype detector works safely (or not) under hard environmental conditions (the air temperature changes between −25 °C and −5 °C). The detector prototype is using silicon photomultiplier (SiPM) produced by SensL and DRS4 chip as read-out part. Measurements at different temperature at fixed bias voltage (∼29.5 V) were performed to reconstruct tracks by Time Of Flight.

  2. Optimization of a bolometer detector for ITER based on Pt absorber on SiN membrane

    Energy Technology Data Exchange (ETDEWEB)

    Meister, H.; Eich, T.; Endstrasser, N.; Giannone, L.; Kannamueller, M.; Kling, A.; Koll, J.; Trautmann, T. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstr. 2, D-85748 Garching (Germany); Detemple, P.; Schmitt, S. [Institut fuer Mikrotechnik Mainz GmbH, Carl-Zeiss-Str. 18-20, D-55129 Mainz (Germany); Collaboration: ASDEX Upgrade Team

    2010-10-15

    Any plasma diagnostic in ITER must be able to operate at temperatures in excess of 200 deg. C and neutron loads corresponding to 0.1 dpa over its lifetime. To achieve this aim for the bolometer diagnostic, a miniaturized metal resistor bolometer detector based on Pt absorbers galvanically deposited on SiN membranes is being developed. The first two generations of detectors featured up to 4.5 {mu}m thick absorbers. Results from laboratory tests are presented characterizing the dependence of their calibration constants under thermal loads up to 450 deg. C. Several detectors have been tested in ASDEX Upgrade providing reliable data but also pointing out the need for further optimization. A laser trimming procedure has been implemented to reduce the mismatch in meander resistances below 1% for one detector and the thermal drifts from this mismatch.

  3. Optimization of a bolometer detector for ITER based on Pt absorber on SiN membranea)

    Science.gov (United States)

    Meister, H.; Eich, T.; Endstrasser, N.; Giannone, L.; Kannamüller, M.; Kling, A.; Koll, J.; Trautmann, T.; ASDEX Upgrade Team; Detemple, P.; Schmitt, S.

    2010-10-01

    Any plasma diagnostic in ITER must be able to operate at temperatures in excess of 200 °C and neutron loads corresponding to 0.1 dpa over its lifetime. To achieve this aim for the bolometer diagnostic, a miniaturized metal resistor bolometer detector based on Pt absorbers galvanically deposited on SiN membranes is being developed. The first two generations of detectors featured up to 4.5 μm thick absorbers. Results from laboratory tests are presented characterizing the dependence of their calibration constants under thermal loads up to 450 °C. Several detectors have been tested in ASDEX Upgrade providing reliable data but also pointing out the need for further optimization. A laser trimming procedure has been implemented to reduce the mismatch in meander resistances below 1% for one detector and the thermal drifts from this mismatch.

  4. Reaction channels of 6,7Li+28Si at near-barrier energies

    International Nuclear Information System (INIS)

    Pakou, A; Rusek, K; Nicolis, N G; Alamanos, N; Doukelis, G; Gillibert, A; Kalyva, G; Kokkoris, M; Lagoyannis, A; Musumarra, A; Papachristodoulou, C; Perdikakis, G; Pierroutsakou, D; Pollacco, E C; Spyrou, A; Zarkadas, Ch

    2005-01-01

    The production of α-particles in the reactions 6,7 Li+ 28 Si was studied as a means to disentangle the various reaction channels at near-barrier energies. The competition between compound and direct reactions was determined by using the shape of angular distributions and statistical model calculations. DWBA calculations were also performed to probe the various direct channels. It was found that, approaching barrier, transfer channels are the most dominant for both reactions. For 7 Li+ 28 Si d-transfer is one of the contributing channels without excluding t-transfer, while for 6 Li+ 28 Si, n-transfer and p-transfer have substantial contribution but without excluding d-transfer

  5. Defect-driven inhomogeneities in Ni /4H-SiC Schottky barriers

    Science.gov (United States)

    Tumakha, S.; Ewing, D. J.; Porter, L. M.; Wahab, Q.; Ma, X.; Sudharshan, T. S.; Brillson, L. J.

    2005-12-01

    Nanoscale depth-resolved cathodoluminescence spectroscopy (DRCLS) of Ni diode arrays on 4H-SiC epitaxial wafers reveals a striking correspondence between deep level defects and electrical transport measurements on a diode-by-diode basis. Current-voltage measurements display both ideal and nonideal diode characteristics due to multiple barriers within individual contacts. Near-interface DRCLS demonstrates the presence of three discrete midgap defect levels with 2.2, 2.45, and 2.65eV emission energies whose concentrations vary on a submicron scale among and within individual diodes, correlating with barrier inhomogeneity. These results also suggest that SiC native defect levels can account for the maximum range of n-type barrier heights.

  6. Fabrication and characterization of surface barrier detector from commercial silicon substrate

    International Nuclear Information System (INIS)

    Costa, Fabio Eduardo da; Silva, Julio Batista Rodrigues da

    2015-01-01

    This work used 5 silicon substrates, n-type with resistivity between 500-20,000 Ω.cm, with 12 mm diameter and 1 mm thickness, from Wacker - Chemitronic, Germany. To produce the surface barrier detectors, the substrates were first cleaned, then, they were etched with HNO 3 solution. After this, a deposition of suitable materials on the crystal was made, to produce the desired population inversion of the crystal characteristics. The substrates received a 10 mm diameter gold contact in one of the surfaces and a 5 mm diameter aluminum in the other. The curves I x V and the energy spectra for 28 keV and 59 keV, for each of the produced detectors, were measured. From the 5 substrates, 4 of them resulted in detectors and one did not present even diode characteristics. The results showed that the procedures used are suitable to produce detectors with this type of silicon substrates. (author)

  7. Calibration of diffusion barrier charcoal detectors and application to radon sampling in dwellings

    Energy Technology Data Exchange (ETDEWEB)

    Montero C, M.E.; Colmenero S, L.; Villalba, L.; Saenz P, J.; Cano J, A.; Moreno B, A.; Renteria V, M.; Herrera P, E.F. [Cento de Investigacion en Materiales Avanzados, S. C. Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua, (Mexico); Cruz G, S. De la [Facultad de Enfermeria y Nutriologia, Universidad Autonoma de Chihuahua, Av. Politecnico Nacional 2714, Chihuahua, (Mexico); Lopez M, A. [Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027, 11801 Mexico D.F. (Mexico)

    2003-07-01

    Some calibration conditions of diffusion barrier charcoal canister (DBCC) detectors for measuring radon concentration in air were studied. A series of functional expressions and graphs were developed to describe relationship between radon concentration in air and the activity adsorbed in DBCC, when placed in small chambers. A semi-empirical expression for the DBCC calibration was obtained, based on the detector integration time and the adsorption coefficient of radon on activated charcoal. Both, the integration time for 10 % of DBCC of the same batch, and the adsorption coefficient of radon for the activated charcoal used in these detectors, were experimentally determined. Using these values as the calibration parameters, a semi-empirical calibration function was used for the interpretation of the radon activities in the detectors used for sampling more than 200 dwellings in the major cities of the state of Chihuahua, Mexico. (Author)

  8. A sensitive gas chromatography detector based on atmospheric pressure chemical ionization by a dielectric barrier discharge.

    Science.gov (United States)

    Kirk, Ansgar T; Last, Torben; Zimmermann, Stefan

    2017-02-03

    In this work, we present a novel concept for a gas chromatography detector utilizing an atmospheric pressure chemical ionization which is initialized by a dielectric barrier discharge. In general, such a detector can be simple and low-cost, while achieving extremely good limits of detection. However, it is non-selective apart from the use of chemical dopants. Here, a demonstrator manufactured entirely from fused silica capillaries and printed circuit boards is shown. It has a size of 75×60×25mm 3 and utilizes only 2W of power in total. Unlike other known discharge detectors, which require high-purity helium, this detector can theoretically be operated using any gas able to form stable ion species. Here, purified air is used. With this setup, limits of detection in the low parts-per-billion range have been obtained for acetone. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Calibration of diffusion barrier charcoal detectors and application to radon sampling in dwellings

    International Nuclear Information System (INIS)

    Montero C, M.E.; Colmenero S, L.; Villalba, L.; Saenz P, J.; Cano J, A.; Moreno B, A.; Renteria V, M.; Herrera P, E.F.; Cruz G, S. De la; Lopez M, A.

    2003-01-01

    Some calibration conditions of diffusion barrier charcoal canister (DBCC) detectors for measuring radon concentration in air were studied. A series of functional expressions and graphs were developed to describe relationship between radon concentration in air and the activity adsorbed in DBCC, when placed in small chambers. A semi-empirical expression for the DBCC calibration was obtained, based on the detector integration time and the adsorption coefficient of radon on activated charcoal. Both, the integration time for 10 % of DBCC of the same batch, and the adsorption coefficient of radon for the activated charcoal used in these detectors, were experimentally determined. Using these values as the calibration parameters, a semi-empirical calibration function was used for the interpretation of the radon activities in the detectors used for sampling more than 200 dwellings in the major cities of the state of Chihuahua, Mexico. (Author)

  10. Capabilities of silicon Shottki barriers and planar detectors in low-energy proton spectometry

    Energy Technology Data Exchange (ETDEWEB)

    Verbitskaya, E M; Eremin, V K; Malyarenko, A M; Sakharov, V I; Serenkov, I T; Strokan, N B; Sukhanov, V L

    1987-05-12

    Dependence of the resolution of surface barrier and planar diffusion silicon detectors on proton energy is investigated. The experiment was conducted at the device, representing the double mass spectrometer with the maximal energy of single-charged ions up to 200 keV. Two advantages of using planar diffusion detectors for light low-energy ion spectrometry is established: high energy resolution and independence of signal amplitude of bias voltage. Background noise represents the main factor dictaiting resolution, but fluctuations of losses in input window are sufficient as well. It was concluded that planar detector application for spectrometry of protons with energy of less than 200 keV would improve the resolution up to 2.2 keV without detector cooling.

  11. SiD Linear Collider Detector R&D, DOE Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Brau, James E. [Univ. of Oregon, Eugene, OR (United States); Demarteau, Marcel [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-05-15

    The Department of Energy’s Office of High Energy Physics supported the SiD university detector R&D projects in FY10, FY11, and FY12 with no-cost extensions through February, 2015. The R&D projects were designed to advance the SiD capabilities to address the fundamental questions of particle physics at the International Linear Collider (ILC): • What is the mechanism responsible for electroweak symmetry breaking and the generation of mass? • How do the forces unify? • Does the structure of space-time at small distances show evidence for extra dimensions? • What are the connections between the fundamental particles and forces and cosmology? Silicon detectors are used extensively in SiD and are well-matched to the challenges presented by ILC physics and the ILC machine environment. They are fast, robust against machine-induced background, and capable of very fine segmentation. SiD is based on silicon tracking and silicon-tungsten sampling calorimetry, complemented by powerful pixel vertex detection, and outer hadronic calorimetry and muon detection. Radiation hard forward detectors which can be read out pulse by pulse are required. Advanced calorimetry based on a particle flow algorithm (PFA) provides excellent jet energy resolution. The 5 Tesla solenoid is outside the calorimeter to improve energy resolution. PFA calorimetry requires fine granularity for both electromagnetic and hadronic calorimeters, leading naturally to finely segmented silicon-tungsten electromagnetic calorimetry. Since silicon-tungsten calorimetry is expensive, the detector architecture is compact. Precise tracking is achieved with the large magnetic field and high precision silicon microstrips. An ancillary benefit of the large magnetic field is better control of the e⁺e⁻ pair backgrounds, permitting a smaller radius beampipe and improved impact parameter resolution. Finally, SiD is designed with a cost constraint in mind. Significant advances and new capabilities have been made and

  12. Development of a compact 25-channel preamplifier module for Si-pad detectors of the BARC-CPDA

    International Nuclear Information System (INIS)

    Inkar, A.; John, Bency; Vind, R.P.; Kinage, L.; Jangale, R.V.; Biswas, D.C.; Nayak, B.K.

    2011-01-01

    The BARC Charged Particle Detector Array modules use indigenously developed Si pad detectors as their first element. Total number of charge sensitive pre-amplifiers required for the Si-pad detectors is 250. One of the main ideas here is a layout of five pre-amplifiers connected with one Si-pad detector (called a bank of preamplifiers). In the present work, a 25-channel pre-amplifier module that can cater to 5 independent Si-pad detectors, or a five-bank module, has been developed. This module uses pre-amp hybrid chips A1422H from CAEN S.p.A. and is housed in a double width NIM standard box. The module has been tested for performance using proton and ''7Li beams from FOTIA facility, Trombay

  13. Plasma-laser ion discrimination by TOF technique applied to coupled SiC detectors.

    Science.gov (United States)

    Cavallaro, Salvatore

    2018-01-01

    The rate estimation of nuclear reactions induced in high intensity laser-target interaction (≥1016 W/cm2), is strongly depending on the neutron detection efficiency and ion charge discrimination, according to particles involved in exit open-channels. Ion discrimination is basically performed by means of analysis of pits observed on track detector, which is critically dependent on calibration and/or fast TOF devices based on SiC and diamond detectors. Last setup is used to determine the ion energy and to obtain a rough estimation of yields. However, for each TOF interval, the dependence of yield from the energy deposited in the detector sensitive region, introduces a distortion in the ion spectra. Moreover, if two ion species are present in the same spectrum, the discrimination of their contribution is not attainable. In this paper a new method is described which allows to discriminate the contribution of two ion species in the wide energy range of nuclear reactions induced in laser-target interactions. The method is based on charge response of two TOF-SiC detectors, of suitable thicknesses, placed in adjacent positions. In presence of two ion species, the response of the detectors, associated with different energy losses, can determine the ion specific contribution to each TOF interval.

  14. Inhomogeneity in barrier height at graphene/Si (GaAs) Schottky junctions.

    Science.gov (United States)

    Tomer, D; Rajput, S; Hudy, L J; Li, C H; Li, L

    2015-05-29

    Graphene (Gr) interfaced with a semiconductor forms a Schottky junction with rectifying properties, however, fluctuations in the Schottky barrier height are often observed. In this work, Schottky junctions are fabricated by transferring chemical vapor deposited monolayer Gr onto n-type Si and GaAs substrates. Temperature dependence of the barrier height and ideality factor are obtained by current-voltage measurements between 215 and 350 K. An increase in the zero bias barrier height and decrease in the ideality factor are observed with increasing temperature for both junctions. Such behavior is attributed to barrier inhomogeneities that arise from interfacial disorders as revealed by scanning tunneling microscopy/spectroscopy. Assuming a Gaussian distribution of the barrier heights, mean values of 1.14 ± 0.14 eV and 0.76 ± 0.10 eV are found for Gr/Si and Gr/GaAs junctions, respectively. These findings resolve the origin of barrier height inhomogeneities in these Schottky junctions.

  15. Inhomogeneity in barrier height at graphene/Si (GaAs) Schottky junctions

    International Nuclear Information System (INIS)

    Tomer, D; Rajput, S; Hudy, L J; Li, L; Li, C H

    2015-01-01

    Graphene (Gr) interfaced with a semiconductor forms a Schottky junction with rectifying properties, however, fluctuations in the Schottky barrier height are often observed. In this work, Schottky junctions are fabricated by transferring chemical vapor deposited monolayer Gr onto n-type Si and GaAs substrates. Temperature dependence of the barrier height and ideality factor are obtained by current–voltage measurements between 215 and 350 K. An increase in the zero bias barrier height and decrease in the ideality factor are observed with increasing temperature for both junctions. Such behavior is attributed to barrier inhomogeneities that arise from interfacial disorders as revealed by scanning tunneling microscopy/spectroscopy. Assuming a Gaussian distribution of the barrier heights, mean values of 1.14 ± 0.14 eV and 0.76 ± 0.10 eV are found for Gr/Si and Gr/GaAs junctions, respectively. These findings resolve the origin of barrier height inhomogeneities in these Schottky junctions. (paper)

  16. Study Of Boosted W-Jets And Higgs-Jets With the SiFCC Detector

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Shin-Shan [Taiwan, Natl. Central U.; Chekanov, Sergei [Argonne; Gray, Lindsey [Fermilab; Kotwal, Ashutosh [Duke U.; Sen, Sourav [Duke U.; Tran, Nhan Viet [Fermilab

    2016-11-04

    We study the detector performance in the reconstruction of hadronically-decaying W bosons and Higgs bosons at very high energy proton colliders using a full GEANT4 simulation of the SiFCC detector. The W and Higgs bosons carry transverse momentum in the multi-TeV range, which results in collimated decay products that are reconstructed as a single jet. We present a measurement of the energy response and resolution of boosted W-jets and Higgs-jets and show the separation of two sub-jets within the boosted boson jet.

  17. A simulation study of 6H-SiC Schottky barrier source/drain MOSFET

    International Nuclear Information System (INIS)

    Wang Yuan; Zhang Yimen; Zhang Yuming; Tang Xiaoyan

    2003-01-01

    A novel SiC metal-oxide-semiconductor field-effect transistor (SiC SBSD-MOSFET) with Schottky barrier contacts for source and drain is presented in this paper. This kind of device gives a fabrication advantage of avoiding the steps of ion implantation and annealing at high temperatures of the conventional SiC MOSFET. Also it has no problems of crystal damage caused by ion implantation and low activation rate of implanted atoms. The operational mechanism of this device is analyzed and its characteristics are comparable to the conventional SiC MOSFET from the simulation with MEDICI. The effects of different metal workfunctions, oxide thickness, and gate length on the device performance are discussed

  18. Compact modeling of SiC Schottky barrier diode and its extension to junction barrier Schottky diode

    Science.gov (United States)

    Navarro, Dondee; Herrera, Fernando; Zenitani, Hiroshi; Miura-Mattausch, Mitiko; Yorino, Naoto; Jürgen Mattausch, Hans; Takusagawa, Mamoru; Kobayashi, Jun; Hara, Masafumi

    2018-04-01

    A compact model applicable for both Schottky barrier diode (SBD) and junction barrier Schottky diode (JBS) structures is developed. The SBD model considers the current due to thermionic emission in the metal/semiconductor junction together with the resistance of the lightly doped drift layer. Extension of the SBD model to JBS is accomplished by modeling the distributed resistance induced by the p+ implant developed for minimizing the leakage current at reverse bias. Only the geometrical features of the p+ implant are necessary to model the distributed resistance. Reproduction of 4H-SiC SBD and JBS current-voltage characteristics with the developed compact model are validated against two-dimensional (2D) device-simulation results as well as measurements at different temperatures.

  19. Energy and time of flight measurements of REX-ISOLDE stable beams using Si detectors

    CERN Document Server

    Cantero, E D; Fraser, M A; Lanaia, D; Sosa, A; Voulot, D; Zocca, F

    2014-01-01

    In this paper we present energy and time spectroscopy measurements for the stable beams of REX-ISOLDE obtained using Si detectors. By using an alpha source as a calibration reference, the absolute energy E of stable beam particles (A/q = 4) was determined in spectroscopy mode in the energy range 1 MeV < E < 8 MeV (0.30 MeV/u < E/A < 1.87 MeV/u). The time of flight of the beam particles (2.18 MeV/u < E/A < 2.27 MeV/u) was determined by installing identical Si detectors in two diagnostic boxes separated by 7.7 m. The results obtained with these two techniques are compared with the values obtained by dipole scans using a bending magnet. The measurements took place between January and February of 2013.

  20. Charge-sensitive poly-silicon TFT amplifiers for a-Si:H pixel particle detectors

    International Nuclear Information System (INIS)

    Cho, G.; Perez-Mendez, V.; Hack, M.; Lewis, A.

    1992-04-01

    Prototype charge-sensitive poly-Si TFT amplifiers have been made for the amplification of signals (from an a-Si:H pixel diode used as an ionizing particle detector). They consist of a charge-sensitive gain stage, a voltage gain stage and a source follower output stage. The gain-bandwidth product of the amplifier is ∼ 300 MHz. When the amplifier is connected to a pixel detector of 0.2 pF, it gives a charge-to-voltage gain of ∼ 0.02 mV/electrons with a pulse rise time less than 100 nsec. An equivalent noise charge of the front-end TFT is ∼ 1000 electrons for a shaping time of 1 μsec

  1. Application of a-Si:H radiation detectors in medical imaging

    International Nuclear Information System (INIS)

    Lee, Hyoung-Koo.

    1995-06-01

    Monte Carlo simulations of a proposed a-Si:H-based current-integrating gamma camera were performed. The analysis showed that the intrinsic resolution of such a camera was 1 ∼ 2.5 mm, which is somewhat better than that of a conventional gamma camera, and that the greater blurring, due to the detection of scattered γ-rays, could be reduced considerably by image restoration techniques. This proposed gamma camera would be useful for imaging shallow organs such as the thyroid. Prototype charge-storage a-Si:H pixel detectors for such a camera were designed, constructed and tested. The detectors could store signal charge as long as 5 min at -26C. The thermal generation current in reverse biased a-Si:H p-i-n photodetectors was investigated, and the Poole-Frenkel effect was found to be the most significant source of the thermal generation current. Based on the Poole-Frenkel effect, voltage- and time-dependent thermal generation current was modeled. Using the model, the operating conditions of the proposed a-Si:H gamma camera, such as the operating temperature, the operating bias and the γ-scan period, could be predicted. The transient photoconductive gain mechanism in various a-Si:H devices was investigated for applications in digital radiography. Using the a-Si:H photoconductors in n-i-n configuration in pixel arrays, enhancement in signal collection (more than 200 times higher signal level) can be achieved in digital radiography, compared to the ordinary p-i-n type a-Si:H x-ray imaging arrays

  2. Ultrafast photon number resolving detector with a temperature stabilized si multi pixel photon counter

    Energy Technology Data Exchange (ETDEWEB)

    Song, Minsoo; Hong, Eugene; Won, Eunil; Yoon, Tai Hyun [Korea Univ., Seoul (Korea, Republic of)

    2008-11-15

    Quantum information science has been rapidly progressed and matured and matured thanks to the recent developments of the single photon detection technologies. Single photon detectors such as a Si avalanche photo diode(APD)in the infrared, an InGaAs/InP APD in the telecommunication band, and a super conducting transient edge sensor(TES)in the broad region of the spectrum have been widely used. Single photon detectors, however, operating at the ultraviolet to visible (370nm∼800nm)regions has not been actively investigated partly due to the lack of single photon and/or entangled photon sources and the lack of solid state single photon detectors. In this paper, we investigate the single photon detection characteristics of a Si multi pixel photon counter(MPPC), which has a high spectral responsivity between 300nm to 800nm, as a photon number resolving solid state detector. Figure 1 shows the schematic diagram of the single photon detection set up at 399nm by using a temperature stabilized Si MPPC. The output beam of the laser being properly attenuated is directed to the MPPC module, at which fixed number of photo electrons corresponding to incident individual photon are generated at Geiger mode of the Si APD pixels. The detected photo current is converted into a digital signal by using a fast analog to digital converter and a digital oscilloscope stores the time sequence of the photo currents. Figure 2 shows the accumulated charges collected by MPPC at∼10.deg.C showing a clear single photon and two photons peaks, respectively, separated by ∼5 sigma of the coincidence counts at the two output ports of a Mach Zender interferometer as a function of optical path length difference. The research was supported by Seoul R and BD program(NT070127)and by the KRISS.

  3. Ultrafast photon number resolving detector with a temperature stabilized si multi pixel photon counter

    International Nuclear Information System (INIS)

    Song, Minsoo; Hong, Eugene; Won, Eunil; Yoon, Tai Hyun

    2008-01-01

    Quantum information science has been rapidly progressed and matured and matured thanks to the recent developments of the single photon detection technologies. Single photon detectors such as a Si avalanche photo diode(APD)in the infrared, an InGaAs/InP APD in the telecommunication band, and a super conducting transient edge sensor(TES)in the broad region of the spectrum have been widely used. Single photon detectors, however, operating at the ultraviolet to visible (370nm∼800nm)regions has not been actively investigated partly due to the lack of single photon and/or entangled photon sources and the lack of solid state single photon detectors. In this paper, we investigate the single photon detection characteristics of a Si multi pixel photon counter(MPPC), which has a high spectral responsivity between 300nm to 800nm, as a photon number resolving solid state detector. Figure 1 shows the schematic diagram of the single photon detection set up at 399nm by using a temperature stabilized Si MPPC. The output beam of the laser being properly attenuated is directed to the MPPC module, at which fixed number of photo electrons corresponding to incident individual photon are generated at Geiger mode of the Si APD pixels. The detected photo current is converted into a digital signal by using a fast analog to digital converter and a digital oscilloscope stores the time sequence of the photo currents. Figure 2 shows the accumulated charges collected by MPPC at∼10.deg.C showing a clear single photon and two photons peaks, respectively, separated by ∼5 sigma of the coincidence counts at the two output ports of a Mach Zender interferometer as a function of optical path length difference. The research was supported by Seoul R and BD program(NT070127)and by the KRISS

  4. Radiation tolerance of the FOXFET biasing scheme for AC-coupled Si microstrip detectors

    International Nuclear Information System (INIS)

    Bacchetta, N.; Gotra, Yu.; Bisello, D.; Da Ros, R.; Giraldo, A.; Fusaro, G.; Paccagnella, A.; Univ. di Cagliari; Verzellesi, G.; Univ. di Padova

    1993-01-01

    The radiation response of FOXFETs has been studied for proton, gamma and neutron exposures. The punch-through behavior, which represents the normal FET operating conditions in Si microstrip detectors, has been found to be much less sensitive to radiation damage than threshold voltage. The device performance has been elucidated by means of two-dimensional simulations. The main radiation effects have been also taken into account in the numerical analysis and separately examined

  5. Characteristics of Fabricated SiC Neutron Detectors for Neutron Flux Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Han Soo; Ha, Jang Ho; Park, Se Hwan; Lee, Kyu Hong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, Cheol Ho [Hanyang University, Seoul (Korea, Republic of)

    2011-05-15

    An SPND (Self-powered Neutron Detector) is commonly used for neutron detection in NPP (Nuclear Power Plant) by virtue of un-reactivity for gamma-rays. But it has a drawback, which is that it cannot detect neutrons in real time due to beta emissions (about > 48 s) after reactions between neutrons and {sup 103}Rh in an SPND. And Generation IV reactors such as MSR (Molten-salt reactor), SFR (Sodium-cooled fast reactor), and GFR (Gas-cooled fast reactor) are designed to compact size and integration type. For GEN IV reactor, neutron monitor also must be compact-sized to apply such reactor easily and much more reliable. The wide band-gap semiconductors such as SiC, AlN, and diamond make them an attractive alternative in applications in harsh environments by virtue of the lower operating voltage, faster charge-collection times compared with gas-filled detectors, and compact size.1) In this study, two PIN-type SiC semiconductor neutron detectors, which are for fast neutron detection by elastic and inelastic scattering SiC atoms and for thermal neutron detection by charged particle emissions of 6LiF reaction, were designed and fabricated for NPP-related applications. Preliminary tests such as I-V and alpha response were performed and neutron responses at ENF in HANARO research reactor were also addressed. The application feasibility of the fabricated SiC neutron detector as an in-core neutron monitor was discussed

  6. Programmable integrated front-end for SiPM/PMT PET detectors with continuous scintillating crystal

    OpenAIRE

    Herrero Bosch, Vicente; Monzó Ferrer, José María; Ros García, Ana; Aliaga Varea, Ramón José; González Martínez, Antonio Javier; Montoliu, C.; Colom Palero, Ricardo José; Benlloch Baviera, Jose María

    2012-01-01

    AMIC architecture has been introduced in previous works in order to provide a generic and expandable solution for implementing large number of outputs SiPM array/PMT detectors. The underlying idea in AMIC architecture is to calculate the moments of the detected light distribution in an analog fashion. These moments provide information about energy, x/y position, etc. of the light distribution of the detected event. Moreover this means that a small set of signals contains most of the informati...

  7. A forward bias method for lag correction of an a-Si flat panel detector

    International Nuclear Information System (INIS)

    Starman, Jared; Tognina, Carlo; Partain, Larry; Fahrig, Rebecca

    2012-01-01

    Purpose: Digital a-Si flat panel (FP) x-ray detectors can exhibit detector lag, or residual signal, of several percent that can cause ghosting in projection images or severe shading artifacts, known as the radar artifact, in cone-beam computed tomography (CBCT) reconstructions. A major contributor to detector lag is believed to be defect states, or traps, in the a-Si layer of the FP. Software methods to characterize and correct for the detector lag exist, but they may make assumptions such as system linearity and time invariance, which may not be true. The purpose of this work is to investigate a new hardware based method to reduce lag in an a-Si FP and to evaluate its effectiveness at removing shading artifacts in CBCT reconstructions. The feasibility of a novel, partially hardware based solution is also examined. Methods: The proposed hardware solution for lag reduction requires only a minor change to the FP. For pulsed irradiation, the proposed method inserts a new operation step between the readout and data collection stages. During this new stage the photodiode is operated in a forward bias mode, which fills the defect states with charge. A Varian 4030CB panel was modified to allow for operation in the forward bias mode. The contrast of residual lag ghosts was measured for lag frames 2 and 100 after irradiation ceased for standard and forward bias modes. Detector step response, lag, SNR, modulation transfer function (MTF), and detective quantum efficiency (DQE) measurements were made with standard and forward bias firmware. CBCT data of pelvic and head phantoms were also collected. Results: Overall, the 2nd and 100th detector lag frame residual signals were reduced 70%-88% using the new method. SNR, MTF, and DQE measurements show a small decrease in collected signal and a small increase in noise. The forward bias hardware successfully reduced the radar artifact in the CBCT reconstruction of the pelvic and head phantoms by 48%-81%. Conclusions: Overall, the

  8. The strain effect in the surface barrier structures prepared on the basis of n-Si and p-Si

    International Nuclear Information System (INIS)

    Mamatkarimov, O.O.; Tuychiev, U.A.

    2004-01-01

    Full text: One of the ways of creation of large deformations in small volume of the semiconductor is the deformation created by a needle. At insignificant change of external influence the large deformation under a needle in small volume of the semiconductor the significant change of electrophysical parameters of the semiconductor in small volume is created. Therefore, in the present work the results of researches of local pressure influence on physical properties of surface barrier structures has been performed on the basis of silicon with Ni and Mn impurity. The relative changes of a direct current made on the basis n-Si and p-Si from a different degree of compensation are given depending on size of local pressure are shown. Change of current in structures Au-Si -Sb with specific resistance of base ρ=80 Ω·cm and ρ=200 Ω·cm are I p /I 0 =3-3.5 times and I P /I ) =2-2.5 times at pressure P=1.6·10 8 Pa respectively. These data show, that in structures received on the basis of initial silicon, change of a direct current with pressure is in inverse proportion to size of resistance of base of the diode. And in structures Au-Si -Sb with specific resistance of base ρ=5·10 2 Ω·cm and ρ=3·10 3 Ω·cm these changes accordingly are I P /I 0 =7 and I P /I 0 =14. Changes of direct current relative to initial value for structures on the basis p-Si with specific resistance ρ=7·10 2 Ω·cm and ρ=4·10 3 Ω·cm) are I P /I 0 =9 and I P /I 0 =16 respectively. The same changes of direct current of structures on the basis P-Si at local pressure are I P /I 0 =2-2.5. The given values I P /I 0 testify that as in structures Au-Si -Sb, and structures Sb-p-Si -Au, unlike structures on the basis of initial silicon, the values I P /I 0 are increased with increase of specific resistance of base of structures

  9. Polymer-Derived Ceramics as Innovative Oxidation Barrier Coatings for Mo-Si-B Alloys

    Science.gov (United States)

    Hasemann, Georg; Baumann, Torben; Dieck, Sebastian; Rannabauer, Stefan; Krüger, Manja

    2015-04-01

    A preceramic polymer precursor, perhydropolysilazane, is used to investigate its function as a new type of oxidation barrier coating on Mo-Si-B alloys. After dip-coating and pyrolysis at 1073 K (800 °C), dense and well-adhering SiON ceramic coatings could be achieved, which were investigated by SEM and cyclic oxidation tests at 1073 K and 1373 K (800 °C and 1100 °C). The coating is promising in reducing the mass loss during the initial stage of oxidation exposure at 1373 K (1100 °C) significantly.

  10. Fusion barrier distributions in 28,30Si + 124Sn reactions

    International Nuclear Information System (INIS)

    Danu, L.S.; Nayak, B.K.; Biswas, D.C.; Saxena, A.; Thomas, R.G.; Mirgule, E.T.; Choudhury, R.K.

    2009-01-01

    The coupling of various degrees of freedom such as static deformation, inelastic excitation and nucleon transfer with the relative motion gives rise to a distribution of barrier in heavy ion induced fusion reactions. The barrier distribution is a fingerprint of the reaction characterizing the important channel couplings. The relative importance of various couplings in fusion reaction is of topical interest. In an earlier study with deformed projectiles 28,30 Si on 115 In target, it was observed that the barrier distributions get affected due to coulomb reorientation of the deformed projectile nuclei in the field of target nucleus thus giving rise to fusion hindrance at sub-barrier energies. In that study, we considered deformed projectile rotational and positive Q-value transfer channel couplings to relative motion in fusion for investigation of Coulomb reorientation and no inelastic coupling of the 115 In target was considered. In the present work, we have extended the measurements with 124 Sn target and inelastic coupling of target has been considered in the coupled channel calculations. The fusion barrier distributions for 28,30 Si + 124 Sn systems have been obtained by quasi-elastic scattering measurements at backward angles and the results compared with the predictions of coupled channel calculations

  11. Project and construction of a spectrometer for alpha particles using surface barrier detectors

    International Nuclear Information System (INIS)

    Terini, R.A.

    1986-01-01

    The project, construction, tests and some applications of a system for alpha and beta spectrometry, using surface barrier detector are described. The device includes a solid state detector ORTEC-Series F coupled to a system for amplifying the charges produced by passage of an ionizing particle through the detector. The amplifying system is composed by a charge sensitive pre-amplifier, which employs an operational amplifier CA 3140, and a low noise linear amplifier, which is based on the operational amplifiers CA 3140 and LM 301. The pre-amplifier stage input impedance is on the order of TΩ and produces output pulses which heights are proportional to total charge produced by passage of particle through the detector sensitive volume. The main advantage to use charge sensitive system lies in obtention of independent pulse heights of the distributed capacity of connecting cable between the detector and the pre-amplifier. The total system amplification ca reach a maximum of 50.000 in the linear region. Pulses are analysed in a multichannel system ORTEC, model 6240. The amplifier system is easily constructed and low cost using components available in the national market, and it can be employed with ionization chambers, proportional counters, scitillation counters and semiconductor detectors. The results of spectrometer application for alpha spectrometry of AM 241 source were compared to systems made with imported stages. (Author) [pt

  12. Zinc Selenide-Based Schottky Barrier Detectors for Ultraviolet-A and Ultraviolet-B Detection

    Directory of Open Access Journals (Sweden)

    V. Naval

    2010-01-01

    Full Text Available Wide-bandgap semiconductors such as zinc selenide (ZnSe have become popular for ultraviolet (UV photodetectors due to their broad UV spectral response. Schottky barrier detectors made of ZnSe in particular have been shown to have both low dark current and high responsivity. This paper presents the results of electrical and optical characterization of UV sensors based on ZnSe/Ni Schottky diodes fabricated using single-crystal ZnSe substrate with integrated UV-A (320–400 nm and UV-B (280–320 nm filters. For comparison, characteristics characterization of an unfiltered detector is also included. The measured photoresponse showed good discrimination between the two spectral bands. The measured responsivities of the UV-A and UV-B detectors were 50 mA/W and 10 mA/W, respectively. A detector without a UV filter showed a maximum responsivity of about 110 mA/W at 375 nm wavelength. The speed of the unfiltered detector was found to be about 300 kHz primarily limited by the RC time constant determined largely by the detector area.

  13. Fast neutron detection at near-core location of a research reactor with a SiC detector

    Science.gov (United States)

    Wang, Lei; Jarrell, Josh; Xue, Sha; Tan, Chuting; Blue, Thomas; Cao, Lei R.

    2018-04-01

    The measurable charged-particle produced from the fast neutron interactions with the Si and C nucleuses can make a wide bandgap silicon carbide (SiC) sensor intrinsically sensitive to neutrons. The 4H-SiC Schottky detectors have been fabricated and tested at up to 500 °C, presenting only a slightly degraded energy resolution. The response spectrum of the SiC detectors were also obtained by exposing the detectors to external neutron beam irradiation and at a near-core location where gamma-ray field is intense. The fast neutron flux of these two locations are ∼ 4 . 8 × 104cm-2 ṡs-1 and ∼ 2 . 2 × 107cm-2 ṡs-1, respectively. At the external beam location, a Si detector was irradiated side-by-side with SiC detector to disjoin the neutron response from Si atoms. The contribution of gamma ray, neutron scattering, and charged-particles producing reactions in the SiC was discussed. The fast neutron detection efficiencies were determined to be 6 . 43 × 10-4 for the external fast neutron beam irradiation and 6 . 13 × 10-6 for the near-core fast neutron irradiation.

  14. Limitations of the pulse-shape technique for particle discrimination in planar Si detectors

    International Nuclear Information System (INIS)

    Pausch, G.; Seidel, W.; Lampert, M.O.; Rohr, P.

    1996-11-01

    Limitations of the pulse-shape discrimination (PSD) technique - a promising method to identify the charged particles stopped in planar Si-detectors - have been investigated. The particle resolution turned out to be basically determined by resistivity fluctuations in the bulk silicon which cause the charge-collection time to depend on the point of impact. Detector maps showing these fluctuations have been measured and are discussed. Furthermore we present a simple method to test the performance of detectors with respect to PSD. Another limitation of the PSD technique is the finite energy threshold for particle identification. This threshold is caused by an unexpected decrease of the total charge-collection time for ions with a short range, in spite of the fact that the particle tracks are located in a region of very low electric field. (orig.)

  15. Improvement of the instrumental line shape of X-ray spectrometers with Si(Li) - detectors

    International Nuclear Information System (INIS)

    Berdikov, V.V.; Zajtsev, E.A.; Iokhin, B.S.

    1983-01-01

    The possibility of decreasing the background of the X-ray spectrometer detector using the rise-time pulse selection method was investigated. Si(Li)-detectors of 10 and 25 mm 2 square were investigated. Spectrometer channel was composed of ORTEC-472 amplifier and ULTIMA/2 multichannel analyzer on the base of NOVA-3 minicomputer. The energy resolution was equal to 300 eV on 14 KeV line. The pulses of detection allowing were transmitted to analog-to-digital converter. The detection was allowed if front photopeak square) were measured at 17.4, 20.3 and 59.6 keV. 4-6-fold decrease of X-factor was obtained without any loss of detection efficiency. The combination of the method with collimation of radiation in the centre of the detector gives an extremely low value of X-factor which agress with theretical estimations

  16. Measurements of low noise 64 channel counting ASIC for Si and CdTe strip detectors

    International Nuclear Information System (INIS)

    Kachel, M; Grybos, P; Szczygiel, R; Takeyoshi, T

    2011-01-01

    We present the design and performance of a 64-channel ASIC called SXDR64. The circuit is intended to work with DC coupled CdTe detectors as well as with standard AC coupled Si detectors. A single channel of the ASIC consists of a charge sensitive amplifier with a pole-zero cancellation circuit, a 4 th order programmable shaper, a base-line restorer and two independent discriminators with 20-bit counters equipped with RAM. The circuit is able to operate correctly with both polarities of the input signal and the detectors leakage current in a few nA range, with the average rate of input pulses up to 1 Mcps.

  17. Energy measurement and fragment identification using digital signals from partially depleted Si detectors

    International Nuclear Information System (INIS)

    Pasquali, G.; Pastore, G.; Barlini, S.; Bini, M.; Poggi, G.; Stefanini, A.A.; Valdre, S.; Le Neindre, N.; Bougault, R.; Lopez, O.; Vient, E.; Ademard, G.; Borderie, B.; Edelbruck, P.; Rivet, M.F.; Salomon, F.; Bonnet, E.; Chbihi, A.; Frankland, J.D.; Gruyer, D.; Casini, G.; Olmi, A.; Piantelli, S.; Cinausero, M.; Gramegna, F.; Marchi, T.; Duenas, J.A.; Kordyasz, A.; Kozik, T.; Twarog, T.; Morelli, L.; Ordine, A.; Parlog, M.; Rosato, E.; Spadaccini, G.; Alba, R.; Maiolino, C.; Santonocito, D.

    2014-01-01

    A study of identification properties of a Si-Si ΔE-E telescope exploiting an underdepleted residual-energy detector has been performed. Five different bias voltages have been used, one corresponding to full depletion, the others associated with a depleted layer ranging from 90% to 60% of the detector thickness. Fragment identification has been performed using either the ΔE-E technique or the Pulse Shape Analysis (PSA). Both detectors are reverse mounted: particles enter from the low field side, to enhance the PSA performance. The achieved charge and mass resolution has been quantitatively expressed using a Figure of Merit (FoM). Charge collection efficiency has been evaluated and the possibility of energy calibration corrections has been considered. We find that the ΔE-E performance is not affected by incomplete depletion even when only 60% of the wafer is depleted. Isotopic separation capability improves at lower bias voltages with respect to full depletion, though charge identification thresholds are higher than at full depletion. Good isotopic identification via PSA has been obtained from a partially depleted detector, whose doping uniformity is not good enough for isotopic identification at full depletion. (orig.)

  18. Characteristics of fabricated si PIN-type radiation detectors on cooling temperature

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Han Soo; Jeong, Manhee; Kim, Young Soo [Korea Atomic Energy Research Institute, Jeongeup-si 580-185 (Korea, Republic of); Lee, Dong Hun [Korea Research Institute of Standards and Science, Daejeon 305-340 (Korea, Republic of); Cho, Seung Yeon [Environmental Health Center, Yonsei University, Wonju-si 1184-4 (Korea, Republic of); Ha, Jang Ho [Korea Atomic Energy Research Institute, Jeongeup-si 580-185 (Korea, Republic of)

    2015-06-01

    Si PIN photodiode radiation detectors with three different active areas (3×3 mm{sup 2}, 5×5 mm{sup 2}, and 10×10 mm{sup 2}) were designed and fabricated at the Korea Atomic Energy Research Institute (KAERI) for low energy X- and gamma-ray detection. In Si-based semiconductor radiation detectors, one of the noise sources is thermal noise, which degrades their energy resolution performance. In this study, the temperature effects on the energy resolution were investigated using a 3×3 mm{sup 2} active area PIN photodiode radiation detector using a Thermoelectric Module (TEM) from room temperature to −23 °C. Energy resolutions from 25 keV auger electrons to 81 keV gamma-ray from a Ba-133 calibration source were measured and compared at every 10 °C interval. At −23 °C, energy resolutions were improved by 15.6% at 25 keV, 4.0% at 31 keV, and 1.2% at 81 keV in comparison with resolutions at room temperature. CsI(Tl)/PIN photodiode radiation detectors were also fabricated for relatively high energy gamma-ray detection. Energy resolutions for Cs-137, Co-60, and Na-22 sources were measured and compared with the spectral responsivity.

  19. Energy measurement and fragment identification using digital signals from partially depleted Si detectors

    Energy Technology Data Exchange (ETDEWEB)

    Pasquali, G.; Pastore, G.; Barlini, S.; Bini, M.; Poggi, G.; Stefanini, A.A.; Valdre, S. [Universita di Firenze, Dipartimento di Fisica, Sesto Fiorentino (Italy); INFN, Sezione di Firenze, Sesto Fiorentino (Italy); Le Neindre, N.; Bougault, R.; Lopez, O.; Vient, E. [ENSICAEN et Universite de Caen, LPC, IN2P3-CNRS, Caen-Cedex (France); Ademard, G.; Borderie, B.; Edelbruck, P.; Rivet, M.F.; Salomon, F. [Universite Paris-Sud 11, Institut de Physique Nucleaire, CNRS/IN2P3, Orsay cedex (France); Bonnet, E.; Chbihi, A.; Frankland, J.D.; Gruyer, D. [CEA/DSM-CNRS/IN2P3, GANIL, B.P. 5027, Caen cedex (France); Casini, G.; Olmi, A.; Piantelli, S. [INFN, Sezione di Firenze, Sesto Fiorentino (Italy); Cinausero, M.; Gramegna, F.; Marchi, T. [INFN-LNL Legnaro, Legnaro (Padova) (Italy); Duenas, J.A. [FCCEE Universidad de Huelva, Departamento de Fisica Aplicada, Huelva (Spain); Kordyasz, A. [University of Warsaw, Heavy Ion Laboratory, Warsaw (Poland); Kozik, T.; Twarog, T. [Institute of Nuclear Physics IFJ-PAN, Jagiellonian University, Krakow (Poland); Morelli, L. [INFN, Bologna (Italy); Universita di Bologna, Bologna (Italy); Ordine, A. [INFN, Sezione di Napoli, Napoli (Italy); Parlog, M. [ENSICAEN et Universite de Caen, LPC, IN2P3-CNRS, Caen-Cedex (France); ' ' Horia Hulubei' ' National Institute of Physics and Nuclear Engineering, Bucharest (Romania); Rosato, E.; Spadaccini, G. [INFN, Sezione di Napoli, Napoli (Italy); Universita di Napoli ' ' Federico II' ' , Dipartimento di Fisica, Napoli (Italy); Alba, R.; Maiolino, C.; Santonocito, D. [INFN-LNS Catania, Catania (Italy); Collaboration: FAZIA Collaboration

    2014-05-15

    A study of identification properties of a Si-Si ΔE-E telescope exploiting an underdepleted residual-energy detector has been performed. Five different bias voltages have been used, one corresponding to full depletion, the others associated with a depleted layer ranging from 90% to 60% of the detector thickness. Fragment identification has been performed using either the ΔE-E technique or the Pulse Shape Analysis (PSA). Both detectors are reverse mounted: particles enter from the low field side, to enhance the PSA performance. The achieved charge and mass resolution has been quantitatively expressed using a Figure of Merit (FoM). Charge collection efficiency has been evaluated and the possibility of energy calibration corrections has been considered. We find that the ΔE-E performance is not affected by incomplete depletion even when only 60% of the wafer is depleted. Isotopic separation capability improves at lower bias voltages with respect to full depletion, though charge identification thresholds are higher than at full depletion. Good isotopic identification via PSA has been obtained from a partially depleted detector, whose doping uniformity is not good enough for isotopic identification at full depletion. (orig.)

  20. Calculation of the time fixation accuracy for Si(Li)-detectors

    International Nuclear Information System (INIS)

    Kondrat'ev, V.P.; Krasnov, L.V.

    1981-01-01

    An accuracy of time fixation to pulses of changing shape for li-frifted si detectors with thickness over 1 mm is evaluated. The method of the comparison of main and converted signal shapes is the most universal method of time fixation. The idea of the method consists in shaping a bipolar pulse using a single-polar input Rulse and recording the point of the bipolar signal intersection with the zero level. The combination of an analytical method with numerical computer calculations is used for evaluating the time fixation fluctuations. Analysis of the results obtained shows that the value of delay p=tausub(d)/tausub(n) (where tausub(d) is delay time for the main part of a signal, tausub(n) is the maximum time of electron collection) affects most strongly the time shift. The parameter K=tausub(i)/tausub(n) (tausub(i) is a constant of integrating circuit) affects slightly the maximum value of time shift. For the li-drifted si detector 2 mm thick with dispattacement vottage of 400 V the moment of the time fixation will be equal to 47 is in the case of K--1, p=0.4 and x=0.25 (x=R/i, where R is a particle range in the detector, l is the thickness of the detector depleted area. The fluctuations in time fixation don't exceed 2.3 ns for the whole particle energy range

  1. Simulation, image reconstruction and SiPM characterisation for a novel endoscopic positron emission tomography detector

    International Nuclear Information System (INIS)

    Zvolsky, Milan

    2017-12-01

    In the scope of the EndoTOFPET-US project, a novel multimodal device for ultrasound (US) endoscopy and positron emission tomography (PET) is being developed. The project aims at detecting and quantifying morphologic and functional biomarkers and developing new biomarkers for pancreas and prostate oncology. The detector system comprises a small detector probe mounted on an ultrasound endoscope and an external detector plate. The detection of the gamma rays is realised by scintillator crystals with Silicon Photomultiplier (SiPM) read-out. For the characterisation of over 4000 SiPMs for the external plate, an automatised measurement and data analysis procedure is established. The key properties of the SiPMs like breakdown voltage and dark count rate (DCR) are extracted. This knowledge is needed both as a quality assurance as well as for the calibration of the detector. The spread between minimum and maximum breakdown voltage within a SiPM array of 4 x 4 is at maximum 0.43 V with a mean of 0.15 V and an RMS of 0.06 V. This assures the optimal biasing of each SiPM at its individual operating voltage. The mean DCR amounts to 1.49 MHz with an RMS of 0.54 MHz and is thus well below the acceptable threshold of 3 MHz. Two spare modules from the external plate are re-measured and analysed several years after the module assembly, revealing a potential alteration of the SiPM noise properties over time. For the characterisation of SiPMs from different vendors, a software framework for the automatic extraction of performance parameters from pulseheight spectra, including a t of the entire spectrum, is developed and tested. In order to facilitate the modelling of the response of the EndoTOFPET-US detector, a framework is developed which is built around the Geant4-based simulation toolkit GAMOS, to simulate and reconstruct realistic imaging scenarios with this asymmetric PET detector. The simulation studies are used to compare different possible detector designs, guide the

  2. Simulation, image reconstruction and SiPM characterisation for a novel endoscopic positron emission tomography detector

    Energy Technology Data Exchange (ETDEWEB)

    Zvolsky, Milan

    2017-12-15

    In the scope of the EndoTOFPET-US project, a novel multimodal device for ultrasound (US) endoscopy and positron emission tomography (PET) is being developed. The project aims at detecting and quantifying morphologic and functional biomarkers and developing new biomarkers for pancreas and prostate oncology. The detector system comprises a small detector probe mounted on an ultrasound endoscope and an external detector plate. The detection of the gamma rays is realised by scintillator crystals with Silicon Photomultiplier (SiPM) read-out. For the characterisation of over 4000 SiPMs for the external plate, an automatised measurement and data analysis procedure is established. The key properties of the SiPMs like breakdown voltage and dark count rate (DCR) are extracted. This knowledge is needed both as a quality assurance as well as for the calibration of the detector. The spread between minimum and maximum breakdown voltage within a SiPM array of 4 x 4 is at maximum 0.43 V with a mean of 0.15 V and an RMS of 0.06 V. This assures the optimal biasing of each SiPM at its individual operating voltage. The mean DCR amounts to 1.49 MHz with an RMS of 0.54 MHz and is thus well below the acceptable threshold of 3 MHz. Two spare modules from the external plate are re-measured and analysed several years after the module assembly, revealing a potential alteration of the SiPM noise properties over time. For the characterisation of SiPMs from different vendors, a software framework for the automatic extraction of performance parameters from pulseheight spectra, including a t of the entire spectrum, is developed and tested. In order to facilitate the modelling of the response of the EndoTOFPET-US detector, a framework is developed which is built around the Geant4-based simulation toolkit GAMOS, to simulate and reconstruct realistic imaging scenarios with this asymmetric PET detector. The simulation studies are used to compare different possible detector designs, guide the

  3. Time over threshold readout method of SiPM based small animal PET detector

    International Nuclear Information System (INIS)

    Valastyan, I.; Gal, J.; Hegyesi, G.; Kalinka, G.; Nagy, F.; Kiraly, B.; Imrek, J.; Molnar, J.

    2012-01-01

    Complete text of publication follows. The aim of the work was to design a readout concept for silicon photomultiplier (SiPM) sensor array used in small animal PET scanner. The detector module consist of LYSO 35x35 scintillation crystals, 324 SiPM sensors (arranged in 2x2 blocks and those quads in a 9x9 configuration) and FPGA based readout electronics. The dimensions of the SiPM matrix are area: 48x48 mm 2 and the size of one SiPM sensor is 1.95x2.2 mm 2 . Due to the high dark current of the SiPM, conventional Anger based readout method does not provide sufficient crystal position maps. Digitizing the 324 SiPM channels is a straightforward way to obtain proper crystal position maps. However handling hundreds of analogue input channels and the required DSP resources cause large racks of data acquisition electronics. Therefore coding of the readout channels is required. Proposed readout method: The coding of the 324 SiPMs consists two steps: Step 1) Reduction of the channels from 324 to 36: Row column readout, SiPMs are connected to each other in column by column and row-by row, thus the required channels are 36. The dark current of 18 connected SiPMs is small in off for identifying pulses coming from scintillating events. Step 2) Reduction of the 18 rows and columns to 4 channels: Comparators were connected to each rows and columns, and the level was set above the level of dark noise. Therefore only few comparators are active when scintillation light enters in the tile. The output of the comparator rows and columns are divided to two parts using resistor chains. Then the outputs of the resistor chains are digitized by a 4 channel ADC. However instead of the Anger method, time over threshold (ToT) was used. Figure 1 shows the readout concept of the SiPM matrix. In order to validate the new method and optimize the front-end electronics of the detector, the analogue signals were digitized before the comparators using a CAEN DT5740 32 channel digitizer, then the

  4. Uncooled Radiation Hard Large Area SiC X-ray and EUV Detectors and 2D Arrays, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This project seeks to design, fabricate, characterize and commercialize large area, uncooled and radiative hard 4H-SiC EUV ? soft X-ray detectors capable of ultra...

  5. Towards radiation hard converter material for SiC-based fast neutron detectors

    Science.gov (United States)

    Tripathi, S.; Upadhyay, C.; Nagaraj, C. P.; Venkatesan, A.; Devan, K.

    2018-05-01

    In the present work, Geant4 Monte-Carlo simulations have been carried out to study the neutron detection efficiency of the various neutron to other charge particle (recoil proton) converter materials. The converter material is placed over Silicon Carbide (SiC) in Fast Neutron detectors (FNDs) to achieve higher neutron detection efficiency as compared to bare SiC FNDs. Hydrogenous converter material such as High-Density Polyethylene (HDPE) is preferred over other converter materials due to the virtue of its high elastic scattering reaction cross-section for fast neutron detection at room temperature. Upon interaction with fast neutrons, hydrogenous converter material generates recoil protons which liberate e-hole pairs in the active region of SiC detector to provide a detector signal. The neutron detection efficiency offered by HDPE converter is compared with several other hydrogenous materials viz., 1) Lithium Hydride (LiH), 2) Perylene, 3) PTCDA . It is found that, HDPE, though providing highest efficiency among various studied materials, cannot withstand high temperature and harsh radiation environment. On the other hand, perylene and PTCDA can sustain harsh environments, but yields low efficiency. The analysis carried out reveals that LiH is a better material for neutron to other charge particle conversion with competent efficiency and desired radiation hardness. Further, the thickness of LiH has also been optimized for various mono-energetic neutron beams and Am-Be neutron source generating a neutron fluence of 109 neutrons/cm2. The optimized thickness of LiH converter for fast neutron detection is found to be ~ 500 μm. However, the estimated efficiency for fast neutron detection is only 0.1%, which is deemed to be inadequate for reliable detection of neutrons. A sensitivity study has also been done investigating the gamma background effect on the neutron detection efficiency for various energy threshold of Low-Level Discriminator (LLD). The detection

  6. Low Energy X-Ray and γ-Ray Detectors Fabricated on n-Type 4H-SiC Epitaxial Layer

    Science.gov (United States)

    Mandal, Krishna C.; Muzykov, Peter G.; Chaudhuri, Sandeep K.; Terry, J. Russell

    2013-08-01

    Schottky barrier diode (SBD) radiation detectors have been fabricated on n-type 4H-SiC epitaxial layers and evaluated for low energy x- and γ-rays detection. The detectors were found to be highly sensitive to soft x-rays in the 50 eV to few keV range and showed 2.1 % energy resolution for 59.6 keV gamma rays. The response to soft x-rays for these detectors was significantly higher than that of commercial off-the-shelf (COTS) SiC UV photodiodes. The devices have been characterized by current-voltage (I-V) measurements in the 94-700 K range, thermally stimulated current (TSC) spectroscopy, x-ray diffraction (XRD) rocking curve measurements, and defect delineating chemical etching. I-V characteristics of the detectors at 500 K showed low leakage current ( nA at 200 V) revealing a possibility of high temperature operation. The XRD rocking curve measurements revealed high quality of the epitaxial layer exhibiting a full width at half maximum (FWHM) of the rocking curve 3.6 arc sec. TSC studies in a wide range of temperature (94-550 K) revealed presence of relatively shallow levels ( 0.25 eV) in the epi bulk with a density 7×1013 cm-3 related to Al and B impurities and deeper levels located near the metal-semiconductor interface.

  7. Low frequency noise in semiconductor detectors

    International Nuclear Information System (INIS)

    Stojanovic, M.; Marjanovic, N.

    1998-01-01

    Noise characteristics of surface-barrier detectors based on Au contacts on n-Si were measured and analyzed. The metal layers were deposited by evaporation to 40-100 nm thickness. Standard surface-barrier detectors based on Au/Si structures are known to have favorable characteristics, but they tend to degrade with aging and under severe working conditions. Degradation is particularly related to the increase in noise level, leakage current and the reduction of detector efficiency and resolution. Therefore, practical applications of surface-barrier detectors demand their constant upgrading. Improvements of detector properties are concentrated mainly on the front surface and front (rectifying) contact. The aim was to improve the noise characteristics of the surface-barrier structures and retain the favorable detector properties of the Au/Si system. (authors)

  8. Tunable Schottky barrier and high responsivity in graphene/Si-nanotip optoelectronic device

    Science.gov (United States)

    Di Bartolomeo, Antonio; Giubileo, Filippo; Luongo, Giuseppe; Iemmo, Laura; Martucciello, Nadia; Niu, Gang; Fraschke, Mirko; Skibitzki, Oliver; Schroeder, Thomas; Lupina, Grzegorz

    2017-03-01

    We demonstrate tunable Schottky barrier height and record photo-responsivity in a new-concept device made of a single-layer CVD graphene transferred onto a matrix of nanotips patterned on n-type Si wafer. The original layout, where nano-sized graphene/Si heterojunctions alternate to graphene areas exposed to the electric field of the Si substrate, which acts both as diode cathode and transistor gate, results in a two-terminal barristor with single-bias control of the Schottky barrier. The nanotip patterning favors light absorption, and the enhancement of the electric field at the tip apex improves photo-charge separation and enables internal gain by impact ionization. These features render the device a photodetector with responsivity (3 {{A}} {{{W}}}-1 for white LED light at 3 {{mW}} {{{cm}}}-2 intensity) almost an order of magnitude higher than commercial photodiodes. We extensively characterize the voltage and the temperature dependence of the device parameters, and prove that the multi-junction approach does not add extra-inhomogeneity to the Schottky barrier height distribution. We also introduce a new phenomenological graphene/semiconductor diode equation, which well describes the experimental I-V characteristics both in forward and reverse bias.

  9. Studies of SiPM photosensors for time-of-flight detectors within PANDA at FAIR

    International Nuclear Information System (INIS)

    Gruber, L.

    2014-01-01

    The PANDA experiment at FAIR is a planned particle physics experiment dedicated to strong interaction studies using proton-antiproton annihilations. The PANDA time-of-flight (TOF) system is foreseen as a Scintillator Tile (SciTil) Hodoscope, which will deliver valuable input for event timing and particle identification. The proposed detector is based on small plastic scintillator tiles with a size of about 30 x 30 x 5 mm 3 , which are read-out with directly attached Silicon Photomultipliers (SiPMs). The whole system is composed of 5760 scintillator tiles and twice the number of photodetectors, covering an area of about 5.2 m 2 in total. The requirements for the detector are a time resolution in the order of 100 ps sigma and a minimum use of material due to the limited space inside the PANDA spectrometer. SiPMs are extremely versatile photodetectors which tend to successively replace the ordinary vacuum Photomultiplier Tubes (PMTs) in many of the photosensing demands ranging from particle physics to medical imaging. Due to many advantages like good time resolution, high photon detection efficiency (PDE), compactness, low operating voltage, radiation hardness, low cost and, in contrast to PMTs, insensitivity to magnetic fields, SiPMs are well suited for applications in high energy physics like PANDA. Recently, Philips invented the first fully digital SiPM (DPC), which allows to exploit the quasi digital nature of single photon detection. The analog and digital SiPM, respectively, are the main detector technologies used within this work. This thesis describes a detailed study of SiPM properties in order to characterize the new devices and get a profound understanding of their functionality. The characterization studies have been carried out using various experimental setups employing pulsed pico- and femtosecond lasers. With regard to applications in high energy physics experiments, e.g. the PANDA TOF system, parameters like SiPM gain, dark count rate, time resolution

  10. 3D Silicon Coincidence Avalanche Detector (3D-SiCAD) for charged particle detection

    Science.gov (United States)

    Vignetti, M. M.; Calmon, F.; Pittet, P.; Pares, G.; Cellier, R.; Quiquerez, L.; Chaves de Albuquerque, T.; Bechetoille, E.; Testa, E.; Lopez, J.-P.; Dauvergne, D.; Savoy-Navarro, A.

    2018-02-01

    Single-Photon Avalanche Diodes (SPADs) are p-n junctions operated in Geiger Mode by applying a reverse bias above the breakdown voltage. SPADs have the advantage of featuring single photon sensitivity with timing resolution in the picoseconds range. Nevertheless, their relatively high Dark Count Rate (DCR) is a major issue for charged particle detection, especially when it is much higher than the incoming particle rate. To tackle this issue, we have developed a 3D Silicon Coincidence Avalanche Detector (3D-SiCAD). This novel device implements two vertically aligned SPADs featuring on-chip electronics for the detection of coincident avalanche events occurring on both SPADs. Such a coincidence detection mode allows an efficient discrimination of events related to an incoming charged particle (producing a quasi-simultaneous activation of both SPADs) from dark counts occurring independently on each SPAD. A 3D-SiCAD detector prototype has been fabricated in CMOS technology adopting a 3D flip-chip integration technique, and the main results of its characterization are reported in this work. The particle detection efficiency and noise rejection capability for this novel device have been evaluated by means of a β- strontium-90 radioactive source. Moreover the impact of the main operating parameters (i.e. the hold-off time, the coincidence window duration, the SPAD excess bias voltage) over the particle detection efficiency has been studied. Measurements have been performed with different β- particles rates and show that a 3D-SiCAD device outperforms single SPAD detectors: the former is indeed capable to detect particle rates much lower than the individual DCR observed in a single SPAD-based detectors (i.e. 2 to 3 orders of magnitudes lower).

  11. SPICE evaluation of the S/N ratio for Si microstrip detectors

    International Nuclear Information System (INIS)

    Candelori, A.; Paccagnella, A.; Nardi, F.; Bacchetta, N.; Bisello, D.

    1999-01-01

    SPICE simulations of ac-coupled single-sided Si microstrip detectors connected to the PreShape 32 read-out chip have been performed in order to determine the geometrical characteristics (i.e., the strip pitch p and width w) which maximize the signal-to-noise ratio. All of the resistive and capacitive elements of the detector have been determined as a function of the w/p ratio by considering experimental and simulated data available in literature. The SPICE model the authors propose in this work takes into account all the main noise sources in the detector and read-out electronics. The minimum ionizing particle current signal shape has been introduced in the simulations. Two read-out configurations (every strip or every second strip) have been investigated for 6.4- and 12.8-cm-long detectors. The equivalent noise charge as determined by the simulations has been compared with analytical calculations, in order to determine the limits and the corrections to a simplified analytical noise model. Finally, general guidelines for the detector design have been proposed, based on the simulation results

  12. Study of 4H-SiC junction barrier Schottky diode using field guard ring termination

    International Nuclear Information System (INIS)

    Feng-Ping, Chen; Yu-Ming, Zhang; Hong-Liang, Lü; Yi-Men, Zhang; Jian-Hua, Huang

    2010-01-01

    This paper reports that the 4H-SiC Schottky barrier diode, PiN diode and junction barrier Schottky diode terminated by field guard rings are designed, fabricated and characterised. The measurements for forward and reverse characteristics have been done, and by comparison with each other, it shows that junction barrier Schottky diode has a lower reverse current density than that of the Schottky barrier diode and a higher forward drop than that of the PiN diode. High-temperature annealing is presented in this paper as well to figure out an optimised processing. The barrier height of 0.79 eV is formed with Ti in this work, the forward drop for the Schottky diode is 2.1 V, with an ideality factor of 3.2, and junction barrier Schottky diode with blocking voltage higher than 400 V was achieved by using field guard ring termination. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  13. A heating and diffusion barrier based on TaSiN x for miniaturized IC devices

    International Nuclear Information System (INIS)

    Cheng, H.-Y.; Chen, Y.-C.; Lee, C.-M.; Wang, S.-H.; Chin, T.-S.

    2006-01-01

    Highly resistive TaSiN x films investigated as candidates for heating and diffusion-barrier layers for miniaturized IC devices such as a sensor or a phases-change random access memory (PCRAM). The obtained resistivity, between 0.069-1.21 Ω cm, increases with increasing nitrogen content up to 52.83%, and fulfills the requirements as a suitable heating layer. All the as-deposited films were amorphous, and the films with substantial nitrogen content showed excellent thermal stability The amorphous structure had a very smooth surface which was stable at temperatures up to 800 deg. C. In addition to its heating capability, the amorphous structure with no grain boundaries was found to also act as a good diffusion barrier effect in contact with a tungsten electrode as determined by AES an TEM analysis. The barrier effect was evaluated by an annealing at 500 and 600 deg. C in Ar atmosphere for 30 min, respectively. The highly resistive TaSiN x heating layer successfully obstructed the diffusion of tungsten atoms from the W electrodes even when the layer was only 10 nm thick. With increasing N content, the heating and diffusion-barrier layer for PCRAM was proposed as a typical example of many potential applications

  14. Development of Advanced Environmental Barrier Coatings for SiC/SiC Ceramic Matrix Composites: Path Toward 2700 F Temperature Capability and Beyond

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan; Hurst, Janet B.; Good, Brian; Costa, Gustavo; Bhatt, Ramakrishna T.; Fox, Dennis S.

    2017-01-01

    Advanced environmental barrier coating systems for SiC-SiC Ceramic Matrix Composite (CMC) turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant coating development challenges is to achieve prime-reliant environmental barrier coating systems to meet the future 2700F EBC-CMC temperature stability and environmental durability requirements. This presentation will emphasize recent NASA environmental barrier coating system testing and down-selects, particularly the development path and properties towards 2700-3000F durability goals by using NASA hafnium-hafnia-rare earth-silicon-silicate composition EBC systems for the SiC-SiC CMC turbine component applications. Advanced hafnium-based compositions for enabling next generation EBC and CMCs capabilities towards ultra-high temperature ceramic coating systems will also be briefly mentioned.

  15. Timing performance measurements of Si-PM-based LGSO phoswich detectors

    International Nuclear Information System (INIS)

    Yamamoto, Seiichi; Kobayashi, Takahiro; Okumura, Satoshi; Yeom, Jung Yeol

    2016-01-01

    Since the timing resolution was significantly improved using silicon photomultipliers (Si-PMs) combined with fast scintillators, we expect that phoswich detectors will be used in future TOF-PET systems. However, no practical phoswich detector has been proposed for TOF-PET detectors. We conducted timing performance measurements of phoswich detectors comprised of two types of Ce-doped LGSO scintillators with different decay times coupled to Si-PMs and digitized the output signals using a high bandwidth digital oscilloscope. We prepared three types of LGSOs (LGSO-fast, LGSO-standard, and LGSO-slow) with different Ce concentrations. After measuring the decay time, the energy performance, and the timing performance of each LGSO, we conducted pulse shape analysis and timing resolution measurements for two versions of phoswich LGSOs: LGSO-standard/LGSO-fast and LGSO-slow/LGSO-fast combinations. The pulse shape spectra for a 10-mm-long crystal LGSO-slow/LGSO-fast combination showed good separation of the front and back crystals with a peak-to-valley ratio of 2.0. The timing resolutions for the 20-mm-long crystal LGSO-slow/LGSO-fast combination were ~300 ps FWHM. The timing resolutions for the phoswich LGSOs were slightly inferior than that measured with the individual LGSO fast, but the acquired timing resolution for the phoswich configuration, ~300 ps with a LGSO-slow/LGSO-fast combination, is adequate for TOF-PET systems. We conclude that LGSO phoswich detectors are promising for TOF-DOI-PET systems.

  16. Charge collection in Si detectors irradiated in situ at superfluid helium temperature

    Energy Technology Data Exchange (ETDEWEB)

    Verbitskaya, Elena, E-mail: elena.verbitskaya@cern.ch [Ioffe Institute, 26 Politekhnicheskaya str., St. Petersburg 194021 (Russian Federation); Eremin, Vladimir; Zabrodskii, Andrei [Ioffe Institute, 26 Politekhnicheskaya str., St. Petersburg 194021 (Russian Federation); Dehning, Bernd; Kurfürst, Christoph; Sapinski, Mariusz; Bartosik, Marcin R. [CERN, CH-1211, Geneva 23 (Switzerland); Egorov, Nicolai [Research Institute of Material Science and Technology, 4 Passage 4806, Moscow, Zelenograd 124460 (Russian Federation); Härkönen, Jaakko [Helsinki Institute of Physics, P.O.Box 64 (Gustaf Hallströmin katu 2) FI-00014 University of Helsinki (Finland)

    2015-10-01

    Silicon and diamond detectors operated in a superfluid helium bath are currently being considered for the upgrade of the LHC beam loss monitoring system. The detectors would be installed in immediate proximity of the superconducting coils of the triplet magnets. We present here the results of the in situ irradiation test for silicon detectors using 23 GeV protons while keeping the detectors at a temperature of 1.9 K. Red laser (630 nm) Transient Current Technique and DC current measurements were used to study the pulse response and collected charge for silicon detectors irradiated to a maximum radiation fluence of 1×10{sup 16} p/cm{sup 2}. The dependence between collected charge and irradiation fluence was parameterized using the Hecht equation and assumption of a uniform electric field distribution. The collected charge was found to degrade with particle fluence for both bias polarities. We observed that the main factor responsible for this degradation was related to trapping of holes on the donor-type radiation-induced defects. In contrast to expectations, along with formation of donors, acceptor-type defects (electron traps) are introduced into the silicon bulk. This suggests that the current models describing charge collection in irradiated silicon detectors require an extension for taking into account trapping at low temperatures with a contribution of shallow levels. New in situ irradiation tests are needed and planned now to extend statistics of the results and gain a deeper insight into the physics of low temperature detector operation in harsh radiation environment. - Highlights: • Si detectors irradiated in situ at 1.9 K by 23 GeV protons are further studied. • Trapping parameters are derived from the fits of collected charge vs. fluence data. • Acceptor-type defects are likely to be induced along with donor-type ones. • Trapping of holes has a dominating effect on the collected charge degradation. • New tests are planned to gain deeper insight

  17. SiPMs characterization and selection for the DUNE far detector photon detection system

    Science.gov (United States)

    Sun, Y.; Maricic, J.

    2016-01-01

    The Deep Underground Neutrino Experiment (DUNE) together with the Long Baseline Neutrino Facility (LBNF) hosted at the Fermilab will provide a unique, world-leading program for the exploration of key questions at the forefront of neutrino physics and astrophysics. CP violation in neutrino flavor mixing is one of its most important potential discoveries. Additionally, the experiment will determine the neutrino mass hierarchy and precisely measure the neutrino mixing parameters which may potentially reveal new fundamental symmetries of nature. Moreover, the DUNE is also designed for the observation of nucleon decay and supernova burst neutrinos. The photon detection (PD) system in the DUNE far detector provides trigger for cosmic backgrounds, enhances supernova burst trigger efficiency and improves the energy resolution of the detector. The DUNE adopts the technology of liquid argon time projection chamber (LArTPC) that requires the PD sensors, silicon photomultipliers (SiPM), to be carefully chosen to not only work properly in LAr temperature, but also meet certain specifications for the life of the experiment. A comprehensive testing of SiPMs in cryostat is necessary since the datasheet provided by the manufactures in the market does not cover this temperature regime. This paper gives the detailed characterization results of SenSL C-Series 60035 SiPMs, including gain, dark count rate (DCR), cross-talk and after-pulse rate. Characteristic studies on SiPMs from other vendors are also discussed in order to avoid any potential problems associated with using a single source. Moreover, the results of the ongoing mechanical durability tests are shown for the current candidate, SenSL B/C-Series 60035 SiPMs.

  18. Signal and noise analysis of a-Si:H radiation detector-amplifier system

    International Nuclear Information System (INIS)

    Cho, Gyuseong.

    1992-03-01

    Hydrogenated amorphous silicon (a-Si:H) has potential advantages in making radiation detectors for many applications because of its deposition capability on a large-area substrate and its high radiation resistance. Position-sensitive radiation detectors can be made out of a 1d strip or a 2-d pixel array of a Si:H pin diodes. In addition, signal processing electronics can be made by thin-film transistors on the same substrate. The calculated radiation signal, based on a simple charge collection model agreed well with results from various wave length light sources and 1 MeV beta particles on sample diodes. The total noise of the detection system was analyzed into (a) shot noise and (b) 1/f noise from a detector diode, and (c) thermal noise and (d) 1/f noise from the frontend TFT of a charge-sensitive preamplifier. the effective noise charge calculated by convoluting these noise power spectra with the transfer function of a CR-RC shaping amplifier showed a good agreement with the direct measurements of noise charge. The derived equations of signal and noise charge can be used to design an a-Si:H pixel detector amplifier system optimally. Signals from a pixel can be readout using switching TFTs, or diodes. Prototype tests of a double-diode readout scheme showed that the storage time and the readout time are limited by the resistances of the reverse-biased pixel diode and the forward biased switching diodes respectively. A prototype charge-sensitive amplifier was made using poly-Si TFTs to test the feasibility of making pixel-level amplifiers which would be required in small-signal detection. The measured overall gain-bandwidth product was ∼400 MHz and the noise charge ∼1000 electrons at a 1 μsec shaping time. When the amplifier is connected to a pixel detector of capacitance 0.2 pF, it would give a charge-to-voltage gain of ∼0.02 mV/electron with a pulse rise time less than 100 nsec and a dynamic range of 48 dB

  19. Signal and noise analysis of a-Si:H radiation detector-amplifier system

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Gyuseong [Univ. of California, Berkeley, CA (United States)

    1992-03-01

    Hydrogenated amorphous silicon (a-Si:H) has potential advantages in making radiation detectors for many applications because of its deposition capability on a large-area substrate and its high radiation resistance. Position-sensitive radiation detectors can be made out of a 1d strip or a 2-d pixel array of a Si:H pin diodes. In addition, signal processing electronics can be made by thin-film transistors on the same substrate. The calculated radiation signal, based on a simple charge collection model agreed well with results from various wave length light sources and 1 MeV beta particles on sample diodes. The total noise of the detection system was analyzed into (a) shot noise and (b) 1/f noise from a detector diode, and (c) thermal noise and (d) 1/f noise from the frontend TFT of a charge-sensitive preamplifier. the effective noise charge calculated by convoluting these noise power spectra with the transfer function of a CR-RC shaping amplifier showed a good agreement with the direct measurements of noise charge. The derived equations of signal and noise charge can be used to design an a-Si:H pixel detector amplifier system optimally. Signals from a pixel can be readout using switching TFTs, or diodes. Prototype tests of a double-diode readout scheme showed that the storage time and the readout time are limited by the resistances of the reverse-biased pixel diode and the forward biased switching diodes respectively. A prototype charge-sensitive amplifier was made using poly-Si TFTs to test the feasibility of making pixel-level amplifiers which would be required in small-signal detection. The measured overall gain-bandwidth product was ~400 MHz and the noise charge ~1000 electrons at a 1 μsec shaping time. When the amplifier is connected to a pixel detector of capacitance 0.2 pF, it would give a charge-to-voltage gain of ~0.02 mV/electron with a pulse rise time less than 100 nsec and a dynamic range of 48 dB.

  20. Signal and noise analysis of a-Si:H radiation detector-amplifier system

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Gyuseong.

    1992-03-01

    Hydrogenated amorphous silicon (a-Si:H) has potential advantages in making radiation detectors for many applications because of its deposition capability on a large-area substrate and its high radiation resistance. Position-sensitive radiation detectors can be made out of a 1d strip or a 2-d pixel array of a Si:H pin diodes. In addition, signal processing electronics can be made by thin-film transistors on the same substrate. The calculated radiation signal, based on a simple charge collection model agreed well with results from various wave length light sources and 1 MeV beta particles on sample diodes. The total noise of the detection system was analyzed into (a) shot noise and (b) 1/f noise from a detector diode, and (c) thermal noise and (d) 1/f noise from the frontend TFT of a charge-sensitive preamplifier. the effective noise charge calculated by convoluting these noise power spectra with the transfer function of a CR-RC shaping amplifier showed a good agreement with the direct measurements of noise charge. The derived equations of signal and noise charge can be used to design an a-Si:H pixel detector amplifier system optimally. Signals from a pixel can be readout using switching TFTs, or diodes. Prototype tests of a double-diode readout scheme showed that the storage time and the readout time are limited by the resistances of the reverse-biased pixel diode and the forward biased switching diodes respectively. A prototype charge-sensitive amplifier was made using poly-Si TFTs to test the feasibility of making pixel-level amplifiers which would be required in small-signal detection. The measured overall gain-bandwidth product was {approximately}400 MHz and the noise charge {approximately}1000 electrons at a 1 {mu}sec shaping time. When the amplifier is connected to a pixel detector of capacitance 0.2 pF, it would give a charge-to-voltage gain of {approximately}0.02 mV/electron with a pulse rise time less than 100 nsec and a dynamic range of 48 dB.

  1. Characterization of new a-Si:H detectors fabricated from amorphous silicon deposited at high rate by helium enhanced PECVD

    International Nuclear Information System (INIS)

    Pochet, T.; Ilie, A.; Foulon, F.

    1993-01-01

    This paper is concerned with the characterization of new detectors fabricated from a-Si:H films deposited at high rates through the dilution of SiH 4 in helium. Rates of up to ten times (5.5 micrometer/h) that of the standard technique are obtained, allowing for the feasible fabrication of detectors having thickness up to 100 micrometers. The electrical characteristics (depletion voltage, residual space charge density) of the helium diluted material, have been investigated and compared to that of the standard material. The response of detectors, made from both materials, to 5.5 MeV alpha particles are compared. 6 figs., 5 tabs., 13 refs

  2. Design of InAs/GaSb superlattice infrared barrier detectors

    Science.gov (United States)

    Delmas, M.; Rossignol, R.; Rodriguez, J. B.; Christol, P.

    2017-04-01

    Design of InAs/GaSb type-II superlattice (T2SL) infrared barrier detectors is theoretically investigated. Each part of the barrier structures is studied in order to achieve optimal device operation at 150 K and 77 K, in the midwave and longwave infrared domain, respectively. Whatever the spectral domain, nBp structure with a p-type absorbing zone and an n-type contact layer is found to be the most favourable detector architecture allowing a reduction of the dark-current associated with generation-recombination processes. The nBp structures are then compared to pin photodiodes. The MWIR nBp detector with 5 μm cut-off wavelength can operate up to 120 K, resulting in an improvement of 20 K on the operating temperature compared to the pin device. The dark-current density of the LWIR nBp device at 77 K is expected to be as low as 3.5 × 10-4 A/cm2 at 50 mV reverse bias, more than one decade lower than the usual T2SL photodiode. This result, for a device having cut-off wavelength at 12 μm, is at the state of the art compared to the well-known MCT 'rule 07'.

  3. Barrier controlled carrier trapping of extended defects in CdZnTe detector

    International Nuclear Information System (INIS)

    Guo, Rongrong; Jie, Wanqi; Xu, Yadong; Yu, Hui; Zha, Gangqiang; Wang, Tao; Ren, Jie

    2015-01-01

    Transient current techniques using alpha particle source were utilized to study the influence of extended defects on the electron drift time and the detector performance of CdZnTe crystals. Different from the case of trapping through isolated point defect, a barrier controlled trapping model was used to explain the mechanism of carrier trapping at the extended defects. The effect of extended defects on the photoconductance was studied by laser beam induced transient current (LBIC) measurement. The results demonstrate that the Schottky-type depletion space charge region is induced at the vicinity of the extended defects, which further distorts the internal electric field distribution and affects the carrier trajectory in CdZnTe crystals. The relationship between the electron drift time and detector performance has been established. - Highlights: • The barrier controlled trapping model was developed around extended defects. • Electron mobility and E-field distribution were distorted by space charge depletion region. • Extended defects act as a recombination-activated region. • The relationships between extended defects and detector performance were established

  4. Study of araldite in edge protection of n-type and p-type surface barrier detectors

    International Nuclear Information System (INIS)

    Alencar, M.A.V.; Jesus, E.F.O.; Lopes, R.T.

    1995-01-01

    The aim of this work is the realization of a comparative study between the surface barrier detectors performance n and type using the epoxy resin Araldite as edge protection material with the purpose of determining which type of detector (n or p) the use of Araldite is more indicated. The surface barrier detectors were constructed using n and p type silicon wafer with resistivity of 3350Ω.cm and 5850 Ω.cm respectively. In the n type detectors, the metals used as ohmic and rectifier contacts were the Al and Au respectively, while in the p type detectors, the ohmic and rectifier contacts were Au and Al. All metallic contacts were done by evaporation in high vacuum (∼10 -4 Torr) and with deposit of 40 μm/cm 2 . The obtained results for the detectors (reverse current of -350nA and resolution from 21 to 26 keV for p type detectors and reserve current of 1μA and resolution from 44 to 49 keV for n type detectors) tend to demonstrate that use of epoxy resin Araldite in the edge protection is more indicated to p type surface barrier detectors. (author). 3 refs., 4 figs., 1 tab

  5. The Development of a Hybrid-Type Radiation Detector with SiC for a Reactor Robot

    International Nuclear Information System (INIS)

    Lee, Nam Ho; Cho, Jai Wan; Kim, Seung Ho

    2005-01-01

    For a robot working in a harsh environment such as a nuclear reactor environment or a space environment, requirements of on-board radiation detectors are not the same as those for environments around human. SiC devices with the wide band-gap are less dependent on temperature than Si counterparts and the can be the better candidate for the high radiation environment. With this background, radiation performance of a commercial SiC detector in a Co-60 gamma-ray environment has been evaluated. In addition to the SiC detector, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) detector has been incorporated as a backup. With this MOSFET sensor the dosimeter can keep its radiation exposure history even with loss of power. It is not only a redundant feature but also a diverse feature. The dosimetry module can be attached to mobile robot for high radiation environment was developed. This module has both SiC diode and pMOSFET mentioned above. The monitoring program which receives the radiation information from them and gives out the alarm signal when the difference of the two values from them is over the preset level was constructed. Because both the SiC pulse-type detector and the MOSFET dosimeter are small and light weight, they can be easily accommodated on a small printcircuit board for a tight space on a robot arm or for a small spacecraft

  6. Volumetric CT with sparse detector arrays (and application to Si-strip photon counters).

    Science.gov (United States)

    Sisniega, A; Zbijewski, W; Stayman, J W; Xu, J; Taguchi, K; Fredenberg, E; Lundqvist, Mats; Siewerdsen, J H

    2016-01-07

    Novel x-ray medical imaging sensors, such as photon counting detectors (PCDs) and large area CCD and CMOS cameras can involve irregular and/or sparse sampling of the detector plane. Application of such detectors to CT involves undersampling that is markedly different from the commonly considered case of sparse angular sampling. This work investigates volumetric sampling in CT systems incorporating sparsely sampled detectors with axial and helical scan orbits and evaluates performance of model-based image reconstruction (MBIR) with spatially varying regularization in mitigating artifacts due to sparse detector sampling. Volumetric metrics of sampling density and uniformity were introduced. Penalized-likelihood MBIR with a spatially varying penalty that homogenized resolution by accounting for variations in local sampling density (i.e. detector gaps) was evaluated. The proposed methodology was tested in simulations and on an imaging bench based on a Si-strip PCD (total area 5 cm  ×  25 cm) consisting of an arrangement of line sensors separated by gaps of up to 2.5 mm. The bench was equipped with translation/rotation stages allowing a variety of scanning trajectories, ranging from a simple axial acquisition to helical scans with variable pitch. Statistical (spherical clutter) and anthropomorphic (hand) phantoms were considered. Image quality was compared to that obtained with a conventional uniform penalty in terms of structural similarity index (SSIM), image uniformity, spatial resolution, contrast, and noise. Scan trajectories with intermediate helical width (~10 mm longitudinal distance per 360° rotation) demonstrated optimal tradeoff between the average sampling density and the homogeneity of sampling throughout the volume. For a scan trajectory with 10.8 mm helical width, the spatially varying penalty resulted in significant visual reduction of sampling artifacts, confirmed by a 10% reduction in minimum SSIM (from 0.88 to 0.8) and a 40

  7. Tuning of Schottky barrier height of Al/n-Si by electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Vali, Indudhar Panduranga [Manipal Institute of Technology, Manipal University, Manipal 576104 (India); Shetty, Pramoda Kumara, E-mail: pramod.shetty@manipal.edu [Manipal Institute of Technology, Manipal University, Manipal 576104 (India); Mahesha, M.G. [Manipal Institute of Technology, Manipal University, Manipal 576104 (India); Petwal, V.C.; Dwivedi, Jishnu [Raja Ramanna Centre for Advanced Technology, Department of Atomic Energy, Government of India, Indore 452012 (India); Choudhary, R.J. [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452017 (India)

    2017-06-15

    Highlights: • Tuning of Schottky barrier height has been achieved by electron beam irradiation at different doses on n-Si wafer prior to the fabrication of Schottky contact. • The XPS analyses have shown irradiation induced defects and the formation of several localized chemical states in Si/SiOx interface that influences the Schottky barrier height. • High ideality factor indicates metal-insulator-semiconductor configuration of the Schottky diode and the inhomogeneous nature of the Schottky barrier height. • The modifications in I–V characteristics have been observed as a function of electron dose. This is caused due to changes in the Schottky diode parameters and different transport mechanisms. - Abstract: The effect of electron beam irradiation (EBI) on Al/n-Si Schottky diode has been studied by I–V characterization at room temperature. The behavior of the metal-semiconductor (MS) interface is analyzed by means of variations in the MS contact parameters such as, Schottky barrier height (Φ{sub B}), ideality factor (n) and series resistance (R{sub s}). These parameters were found to depend on the EBI dose having a fixed incident beam of energy 7.5 MeV. At different doses (500, 1000, 1500 kGy) of EBI, the Schottky contacts were prepared and extracted their contact parameters by applying thermionic emission and Cheung models. Remarkably, the tuning of Φ{sub B} was observed as a function of EBI dose. The improved n with increased Φ{sub B} is seen for all the EBI doses. As a consequence of which the thermionic emission is more favored. However, the competing transport mechanisms such as space charge limited emission, tunneling and tunneling through the trap states were ascribed due to n > 1. The analysis of XPS spectra have shown the presence of native oxide and increased radiation induced defect states. The thickness variation in the MS interface contributing to Schottky contact behavior is discussed. This study explains a new technique to tune

  8. Dispersion of SiC nanoparticles in cellulose for study of tensile, thermal and oxygen barrier properties.

    Science.gov (United States)

    Kisku, Sudhir K; Dash, Satyabrata; Swain, Sarat K

    2014-01-01

    Cellulose/silicon carbide (cellulose/SiC) nanobiocomposites were prepared by solution technique. The interaction of SiC nanoparticles with cellulose were confirmed by Fourier transformed infrared (FTIR) spectroscopy. The structure of cellulose/SiC nanobiocomposites was investigated by X-ray diffraction (XRD), and transmission electron microscopy (TEM). The tensile properties of the nanobiocomposites were improved as compared with virgin cellulose. Thermal stabilities of cellulose/SiC nanobiocomposites were studied by thermogravimetric analysis (TGA). The cellulose/SiC nanobiocomposites were thermally more stable than the raw cellulose. It may be due to the delamination of SiC with cellulose matrix. The oxygen barrier properties of cellulose composites were measured using gas permeameter. A substantial reduction in oxygen permeability was obtained with increase in silicon carbide concentrations. The thermally resistant and oxygen barrier properties of the prepared nanobiocomposites may enable the materials for the packaging applications. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Design, fabrication and characterization of an a-Si:H-based UV detector for sunburn applications

    Science.gov (United States)

    Bayat, Khadijeh; Vygranenko, Yuriy; Sazonov, Andrei; Farrokh-Baroughi, Mahdi

    2006-12-01

    A thin-film a-Si:H pin detector was developed for selective detection of UVA (320-400 nm) radiation. In order for the fabrication technology to be transferable onto flexible substrates, all of the processing steps were conducted at temperatures less than 125 °C. The measured saturation current as low as 2 pA cm-2 and the ideality factor of 1.47 show that the pin diodes have a good quality i-layer as well as p-i and n-i interfaces. The film thicknesses were optimized to suppress the detector sensitivity in the visible spectral range, and the peak of spectral response was observed at 410 nm. The selectivity estimated from the ratio of the photocurrent generated by UVA absorption to the total photocurrent is 21%.

  10. Delamination Mechanisms of Thermal and Environmental Barrier Coatings on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Choi, Sung R.; Lee, Kang N.; Miller, Robert A.

    2003-01-01

    Advanced ceramic thermal harrier coatings will play an increasingly important role In future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. However, the coating durability issue remains a major concern with the ever-increasing temperature requirements. In this paper, thermal cyclic response and delamination failure modes of a ZrO2-8wt%Y2O3 and mullite/BSAS thermaVenvironmenta1 barrier coating system on SiC/SiC ceramic matrix composites were investigated using a laser high-heat-flux technique. The coating degradation and delamination processes were monitored in real time by measuring coating apparent conductivity changes during the cyclic tests under realistic engine temperature and stress gradients, utilizing the fact that delamination cracking causes an apparent decrease in the measured thermal conductivity. The ceramic coating crack initiation and propagation driving forces under the cyclic thermal loads, in conjunction with the mechanical testing results, will be discussed.

  11. High resolution detectors based on continuous crystals and SiPMs for small animal PET

    International Nuclear Information System (INIS)

    Cabello, J.; Barrillon, P.; Barrio, J.; Bisogni, M.G.; Del Guerra, A.; Lacasta, C.; Rafecas, M.; Saikouk, H.; Solaz, C.; Solevi, P.; La Taille, C. de; Llosá, G.

    2013-01-01

    Sensitivity and spatial resolution are the two main factors to maximize in emission imaging. The improvement of one factor deteriorates the other with pixelated crystals. In this work we combine SiPM matrices with monolithic crystals, using an accurate γ-ray interaction position determination algorithm that provides depth of interaction. Continuous crystals provide higher sensitivity than pixelated crystals, while an accurate interaction position determination does not degrade the spatial resolution. Monte Carlo simulations and experimental data show good agreement both demonstrating sub-millimetre intrinsic spatial resolution. A system consisting in two rotating detectors in coincidence is currently under operation already producing tomographic images

  12. Pile-up and defective pulse rejection by pulse shape discrimination in surface barrier detectors

    International Nuclear Information System (INIS)

    Sjoeland, K.A.; Kristiansson, P.

    1994-01-01

    A technique to reject pile-up pulses and defective tail pulses from surface barrier detectors by the use of pulse shape discrimination is demonstrated. The electronic implementation of the pulse shape discrimination is based upon the zero crossing technique and for data reduction multiparameter techniques are used. The characteristic τ value for pile-up rejection is shown to be less than 56 ns. Its effect on detection limits from tail reduction in Particle Elastic Scattering Analysis (PESA) and pile-up peak suppression is discussed. ((orig.))

  13. Monte Carlo semi-empirical model for Si(Li) x-ray detector: Differences between nominal and fitted parameters

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Pino, N.; Padilla-Cabal, F.; Garcia-Alvarez, J. A.; Vazquez, L.; D' Alessandro, K.; Correa-Alfonso, C. M. [Departamento de Fisica Nuclear, Instituto Superior de Tecnologia y Ciencias Aplicadas (InSTEC) Ave. Salvador Allende y Luaces. Quinta de los Molinos. Habana 10600. A.P. 6163, La Habana (Cuba); Godoy, W.; Maidana, N. L.; Vanin, V. R. [Laboratorio do Acelerador Linear, Instituto de Fisica - Universidade de Sao Paulo Rua do Matao, Travessa R, 187, 05508-900, SP (Brazil)

    2013-05-06

    A detailed characterization of a X-ray Si(Li) detector was performed to obtain the energy dependence of efficiency in the photon energy range of 6.4 - 59.5 keV, which was measured and reproduced by Monte Carlo (MC) simulations. Significant discrepancies between MC and experimental values were found when the manufacturer parameters of the detector were used in the simulation. A complete Computerized Tomography (CT) detector scan allowed to find the correct crystal dimensions and position inside the capsule. The computed efficiencies with the resulting detector model differed with the measured values no more than 10% in most of the energy range.

  14. Fabrication and characteristics of a 4H-SiC junction barrier Schottky diode

    International Nuclear Information System (INIS)

    Chen Fengping; Zhang Yuming; Lue Hongliang; Zhang Yimen; Guo Hui; Guo Xin

    2011-01-01

    4H-SiC junction barrier Schottky (JBS) diodes with four kinds of design have been fabricated and characterized using two different processes in which one is fabricated by making the P-type ohmic contact of the anode independently, and the other is processed by depositing a Schottky metal multi-layer on the whole anode. The reverse performances are compared to find the influences of these factors. The results show that JBS diodes with field guard rings have a lower reverse current density and a higher breakdown voltage, and with independent P-type ohmic contact manufacturing, the reverse performance of 4H-SiC JBS diodes can be improved effectively. Furthermore, the P-type ohmic contact is studied in this work. (semiconductor devices)

  15. Demonstration of a 4H SiC betavoltaic nuclear battery based on Schottky barrier diode

    International Nuclear Information System (INIS)

    Qiao Dayong; Yuan Weizheng; Gao Peng; Yao Xianwang; Zang Bo; Zhang Lin; Guo Hui; Zhang Hongjian

    2008-01-01

    A 4H SiC betavoltaic nuclear battery is demonstrated. A Schottky barrier diode is utilized for carrier separation. Under illumination of Ni-63 source with an apparent activity of 4 mCi/cm 2 an open circuit voltage of 0.49 V and a short circuit current density of 29.44 nA/cm 2 are measured. A power conversion efficiency of 1.2% is obtained. The performance of the device is limited by low shunt resistance, backscattering and attenuation of electron energy in air and Schottky electrode. It is expected to be significantly improved by optimizing the design and processing technology of the device. (authors)

  16. Demonstration of a 4H SiC Betavoltaic Nuclear Battery Based on Schottky Barrier Diode

    International Nuclear Information System (INIS)

    Da-Yong, Qiao; Wei-Zheng, Yuan; Peng, Gao; Xian-Wang, Yao; Bo, Zang; Lin, Zhang; Hui, Guo; Hong-Jian, Zhang

    2008-01-01

    A 4H SiC betavoltaic nuclear battery is demonstrated. A Schottky barrier diode is utilized for carrier separation. Under illumination of Ni-63 source with an apparent activity of 4 mCi/cm 2 an open circuit voltage of 0.49 V and a short circuit current density of 29.44 nA/cm 2 are measured. A power conversion efficiency of 1.2% is obtained. The performance of the device is limited by low shunt resistance, backscattering and attenuation of electron energy in air and Schottky electrode. It is expected to be significantly improved by optimizing the design and processing technology of the device

  17. Influence of dopants on the glow curve structure and energy dependence of LiF:Mg,Cu,Si detectors

    International Nuclear Information System (INIS)

    Knezevic, Z.; Ranogajec-Komor, M.; Miljanic, S.; Lee, J.I.; Kim, J.L.; Music, S.

    2011-01-01

    LiF thermoluminescent material doped with Mg, Cu and Si recently developed by the Korea Atomic Energy Research Institute (KAERI) has shown very good dosimetric properties. Since the thermoluminescence in LiF was found to be dependent on the proper combination of dopants, the investigation of the concentration and type of dopants is very important in developing and characterisation of new TL materials. The aim of this work was to determine the influence of type and concentration of activators on the glow curve structure, sensitivity, reproducibility and on the photon energy response of LiF:Mg,Cu,Si detectors. The energy response was studied in air and on the ISO water phantom in the range of mean photon energies between 33 keV and 164 keV. The morphology and local chemical composition of LiF:Mg,Cu,Si detectors were examined using high resolution scanning electron microscopy (FE-SEM). The results show that type and concentration of activators influence the glow curve and sensitivity. Different dopant concentrations did not show influence on the photon energy response. The sensitivity of LiF:Mg,Cu,Si detector with dopant concentration of Mg = 0.35 mol%, Cu = 0.025 mol% and Si = 0.9 mol% was very high (up to 65 times higher than that of TLD-100). The photon energy response of LiF:Mg,Cu,Si detectors containing all three dopants in various concentrations is in accordance with the IAEA recommendations for individual monitoring.

  18. Influence of dopants on the glow curve structure and energy dependence of LiF:Mg,Cu,Si detectors

    Energy Technology Data Exchange (ETDEWEB)

    Knezevic, Z., E-mail: zknez@irb.h [Ruder Boskovic Institute, Bijenicka 54, 10000 Zagreb (Croatia); Ranogajec-Komor, M.; Miljanic, S. [Ruder Boskovic Institute, Bijenicka 54, 10000 Zagreb (Croatia); Lee, J.I.; Kim, J.L. [Korea Atomic Energy Research Institute, P.O. Box 105 Yuseong, Daejon 305-600 (Korea, Republic of); Music, S. [Ruder Boskovic Institute, Bijenicka 54, 10000 Zagreb (Croatia)

    2011-03-15

    LiF thermoluminescent material doped with Mg, Cu and Si recently developed by the Korea Atomic Energy Research Institute (KAERI) has shown very good dosimetric properties. Since the thermoluminescence in LiF was found to be dependent on the proper combination of dopants, the investigation of the concentration and type of dopants is very important in developing and characterisation of new TL materials. The aim of this work was to determine the influence of type and concentration of activators on the glow curve structure, sensitivity, reproducibility and on the photon energy response of LiF:Mg,Cu,Si detectors. The energy response was studied in air and on the ISO water phantom in the range of mean photon energies between 33 keV and 164 keV. The morphology and local chemical composition of LiF:Mg,Cu,Si detectors were examined using high resolution scanning electron microscopy (FE-SEM). The results show that type and concentration of activators influence the glow curve and sensitivity. Different dopant concentrations did not show influence on the photon energy response. The sensitivity of LiF:Mg,Cu,Si detector with dopant concentration of Mg = 0.35 mol%, Cu = 0.025 mol% and Si = 0.9 mol% was very high (up to 65 times higher than that of TLD-100). The photon energy response of LiF:Mg,Cu,Si detectors containing all three dopants in various concentrations is in accordance with the IAEA recommendations for individual monitoring.

  19. Simulations of Si-PIN photodiode based detectors for underground explosives enhanced by ammonium nitrate

    Science.gov (United States)

    Yücel, Mete; Bayrak, Ahmet; Yücel, Esra Barlas; Ozben, Cenap S.

    2018-02-01

    Massive Ammonium Nitrate (NH4-NO3) based explosives buried underground are commonly used in terror attacks. These explosives can be detected using neutron scattering method with some limitations. Simulations are very useful tools for designing a possible detection system for these kind of explosives. Geant4 simulations were used for generating neutrons at 14 MeV energy and tracking them through the scattering off the explosive embedded in soil. Si-PIN photodiodes were used as detector elements in the design for their low costs and simplicity for signal readout electronics. Various neutron-charge particle converters were applied on to the surface of the photodiodes to increase the detection efficiency. Si-PIN photodiodes coated with 6LiF provided the best result for a certain energy interval. Energy depositions in silicon detector from all secondary particles generated including photons were taken into account to generate a realistic background. Humidity of soil, one of the most important parameter for limiting the detection, was also studied.

  20. High-resolution Compton cameras based on Si/CdTe double-sided strip detectors

    International Nuclear Information System (INIS)

    Odaka, Hirokazu; Ichinohe, Yuto; Takeda, Shin'ichiro; Fukuyama, Taro; Hagino, Koichi; Saito, Shinya; Sato, Tamotsu; Sato, Goro; Watanabe, Shin; Kokubun, Motohide; Takahashi, Tadayuki; Yamaguchi, Mitsutaka

    2012-01-01

    We have developed a new Compton camera based on silicon (Si) and cadmium telluride (CdTe) semiconductor double-sided strip detectors (DSDs). The camera consists of a 500-μm-thick Si-DSD and four layers of 750-μm-thick CdTe-DSDs all of which have common electrode configuration segmented into 128 strips on each side with pitches of 250μm. In order to realize high angular resolution and to reduce size of the detector system, a stack of DSDs with short stack pitches of 4 mm is utilized to make the camera. Taking advantage of the excellent energy and position resolutions of the semiconductor devices, the camera achieves high angular resolutions of 4.5° at 356 keV and 3.5° at 662 keV. To obtain such high resolutions together with an acceptable detection efficiency, we demonstrate data reduction methods including energy calibration using Compton scattering continuum and depth sensing in the CdTe-DSD. We also discuss imaging capability of the camera and show simultaneous multi-energy imaging.

  1. Effect of SiO2 coating in bolometric Ge light detectors for rare event searches

    International Nuclear Information System (INIS)

    Beeman, J.W.; Gentils, A.; Giuliani, A.; Mancuso, M.; Pessina, G.; Plantevin, O.; Rusconi, C.

    2013-01-01

    In germanium-based light detectors for scintillating bolometers, a SiO 2 anti-reflective coating is often applied on the side of the germanium wafer exposed to light with the aim to improve its light collection efficiency. In this paper, we report about a measurement, performed in the temperature range 25–35 mK, of the light-collection increase obtained thanks to this method, which resulted to be of the order of 20%. The procedure followed has been carefully selected in order to minimize systematic effects. The employed light sources have the same spectral features (peaking at ∼630nm wavelength) that will characterize future neutrinoless double beta decay experiments on the isotope 82 Se and based on ZnSe crystals, such as LUCIFER. The coupling between source and light detector reproduces the configuration used in scintillating bolometers. The present measurement clarifies the role of SiO 2 coating and describes a method and a set-up that can be extended to the study of other types of coatings and luminescent materials

  2. Effect of SiO2 coating in bolometric Ge light detectors for rare event searches

    Science.gov (United States)

    Beeman, J. W.; Gentils, A.; Giuliani, A.; Mancuso, M.; Pessina, G.; Plantevin, O.; Rusconi, C.

    2013-05-01

    In germanium-based light detectors for scintillating bolometers, a SiO2 anti-reflective coating is often applied on the side of the germanium wafer exposed to light with the aim to improve its light collection efficiency. In this paper, we report about a measurement, performed in the temperature range 25-35 mK, of the light-collection increase obtained thanks to this method, which resulted to be of the order of 20%. The procedure followed has been carefully selected in order to minimize systematic effects. The employed light sources have the same spectral features (peaking at ˜630 nm wavelength) that will characterize future neutrinoless double beta decay experiments on the isotope 82Se and based on ZnSe crystals, such as LUCIFER. The coupling between source and light detector reproduces the configuration used in scintillating bolometers. The present measurement clarifies the role of SiO2 coating and describes a method and a set-up that can be extended to the study of other types of coatings and luminescent materials.

  3. Calcium-Magnesium-Alumino-Silicates (CMAS) Reaction Mechanisms and Resistance of Advanced Turbine Environmental Barrier Coatings for SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Costa, Gustavo; Harder, Bryan J.; Wiesner, Valerie L.; Hurst, Janet B.; Puleo, Bernadette J.

    2017-01-01

    Environmental barrier coatings (EBCs) and SiC/SiC ceramic matrix composites (CMCs) systems will play a crucial role in future turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is an essential requirement to enable the applications of the 2700-3000 F EBC - CMC systems. This presentation primarily focuses on the reaction mechanisms of advanced NASA environmental barrier coating systems, when in contact with Calcium-Magnesium Alumino-Silicates (CMAS) at high temperatures. Advanced oxide-silicate defect cluster environmental barrier coatings are being designed for ultimate balanced controls of the EBC temperature capability and CMAS reactivity, thus improving the CMAS resistance. Further CMAS mitigation strategies are also discussed.

  4. Development of neutron detector using sensor type surface barrier with (n,p) and (n,α) converters

    International Nuclear Information System (INIS)

    Madi Filho, Tufic

    1999-01-01

    A Si semiconductor detector, surface barrier type, with a slim film of a converter material capable to produce charged particles was used as a sensor of neutrons in an environment of a zero power reactor. Two types of converters were used to improve the detection efficiency: (1) the polyethylene, n(CH 2 ), which produces recoil protons from the (n,p) interaction and, (2) the 10 B which generates a particle from the (n,alpha) reaction. The optimal thickness of those converters was determined experimentally and specifically for the polyethylene a mathematical model R(ips) = ε p · N 0 ·(1-e -Σ·Χ ) ·e -μ ·Χ + ε n · N 0 · -Σ · Χ was used to fit to the experimental data. For the polyethylene converter the thickness was of 0.058 cm (62.64 mg.cm -2 ) while for the 10 B it was equal to 6.55 [μm (1.54 mg.cm -2 ). The converter of polyethylene or 10 B improved the detection efficiency to a factor of 4.7 and 3.0 respectively. The comparison of the spectrum of the background radiation with the spectra of the recoil protons and the a radiation from the 10 B it was concluded that the polyethylene presented better performance than the 10 B converter. (author)

  5. The thermal neutron detection using 4H-SiC detectors with 6LiF conversion layer

    International Nuclear Information System (INIS)

    Zatko, B.; Bohacek, P.; Sekacova, M.; Arbet, J.; Sagatova, A.; Necas, V.

    2016-01-01

    In this paper we have examined 4H-SiC detector using a thermal neutron source and studied its detection properties. The detector was exposed to neutrons generated by 238 Pu-Be radiation source. The detection properties of 4H-SiC detectors were evaluated considering the use of the 6 LiF conversion. We prepared 4H-SiC Schottky contact detectors based on high-quality of epitaxial layer. The current-voltage characteristic show operating region between 100 V and 400 V. The detector was connected to the spectrometric set-up and used for detection of alpha particles from 241 Am. Following the 6 LiF conversion layer was applied on the Schottky contact of detector and the detection of thermal neutrons was performed. We are able to resolve alpha particles and tritons which are products of nuclear reaction between thermal neutrons and conversion layer. Also bare detector was used for neutron detection to clearly show significant influence of the used conversion layer.(authors)

  6. Development of a coincidence system for radio-nuclide standardization using surface barrier detectors

    International Nuclear Information System (INIS)

    Koskinas, M.F.

    1988-01-01

    A system for the standardization of alpha-gamma or electron-X radionuclide emitters has been developed in the present work. The system consists of one or two surface barrier detectors for alpha or electron detection which are coupled to thin-window NaI (T1) crystals suitable for low energy X or gamma ray detection. The performance of the system has been verified by means of the standardization of 241 Am, 137 Cs and 109 Cd solutions. The activity has been obtained using the extrapolation method applied to the 4Πα-γ and 2Πe c -X coincidence technique. The surface barrier detection efficiency was varied by placing absorbers over the radioactive sources or by changing the source to detector distance. The results were compared to those obtained using conventional absolute systems based on gas-flow and pressurized 4Π proportional counters, or using radioactive solutions standardized in international comparisons spondored by the Bureau International des Poids et Mesures. The expect and measured activities agree within the experimental uncertainties which were: 0.2 % for 241 Am, 0.7% for 137 Cs and 0.6% for 109 Cd. The ratio between the probabilities of (electron capture + internal conversion) and internal conversion for the K-shell of 109 Cd has been determined. The result is: 2.8883 ± 0.016. (author) [pt

  7. Fast Track Finding in the ILC's Silicon Detector, SiD01

    International Nuclear Information System (INIS)

    Baker, David E.

    2007-01-01

    A fast track finder is presented which, unlike its more efficient, more computationally costly O(n3) time counterparts, tracks particles in O(n) time (for n being the number of hits). Developed as a tool for processing data from the ILC's proposed SiD detector, development of this fast track finder began with that proposed by Pablo Yepes in 1996 and adjusted to accommodate the changes in geometry of the SiD detector. First, space within the detector is voxellated, with hits assigned to voxels according to their r, φ, and η coordinates. A hit on the outermost layer is selected, and a 'sample space' is built from the hits in the selected hit's surrounding voxels. The hit in the sample space with the smallest distance to the first is then selected, and the sample space recalculated for this hit. This process continues until the list of hits becomes large enough, at which point the helical circle in the x, y plane is conformally mapped to a line in the x', y' plane, and hits are chosen from the sample spaces of the previous fit by selecting the hits which fit a line to the previously selected points with the smallest χ 2 . Track finding terminates when the innermost layer has been reached or no hit in the sample space fits those previously selected to an acceptable χ 2 . Again, a hit on the outermost layer is selected and the process repeats until no assignable hits remain. The algorithm proved to be very efficient on artificial diagnostic events, such as one hundred muons scattered at momenta of 1 GeV/c to 10 GeV/c. Unfortunately, when tracking simulated events corresponding to actual physics, the track finder's efficiency decreased drastically (mostly due to signal noise), though future data cleaning programs could noticeably increase its efficiency on these events

  8. Process effects on leakage current of Si-PIN neutron detectors with porous microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Baoning; Zhao, Kangkang; Yang, Taotao [Beijing University of Technology, Chaoyang District, Pingleyuan 100, 100124 Beijing (China); Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Ruoshui Road 398, 215123 Suzhou (China); Jiang, Yong; Fan, Xiaoqiang [Institute of Nuclear Physics and Chemistry, CAEP, Mianshan Road 64, 621900 Mianyang (China); Lu, Min [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Ruoshui Road 398, 215123 Suzhou (China); Han, Jun [Beijing University of Technology, Chaoyang District, Pingleyuan 100, 100124 Beijing (China)

    2017-06-15

    Using the technique of Microfabrication, such as deep silicon dry etching, lithography, etc. Si-PIN neutron detectors with porous microstructure have been successfully fabricated. In order to lower the leakage current, the key fabrication processes, including the Al windows opening, deep silicon etching and the porous side wall smoothing, have been optimized. The cross-section morphology and current-voltage characteristics have been measured to evaluate the microfabrication processes. With the optimized conditions presented by the measurements, a neutron detector with a leakage current density of 2.67 μA cm{sup -2} at a bias of -20 V is obtained. A preliminary neutron irradiation test with {sup 252}Cf neutron source has also been carried out. The neutron irradiation test shows that the neutron detection efficiency of the microstructured neutron detectors is almost 3.6 times higher than that of the planar ones. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Evaluation of signal energy calculation methods for a light-sharing SiPM-based PET detector

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Qingyang [School of Automation and Electrical Engineering, University of Science & Technology Beijing, Beijing 100083 (China); Beijing Engineering Research Center of Industrial Spectrum Imaging, University of Science and Technology Beijing, Beijing 100083 (China); Ma, Tianyu; Xu, Tianpeng; Liu, Yaqiang; Wang, Shi [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Gu, Yu, E-mail: guyu@ustb.edu.cn [School of Automation and Electrical Engineering, University of Science & Technology Beijing, Beijing 100083 (China)

    2017-03-11

    Signals of a light-sharing positron emission tomography (PET) detector are commonly multiplexed to three analog pulses (E, X, and Y) and then digitally sampled. From this procedure, the signal energy that are critical to detector performance are obtained. In this paper, different signal energy calculation strategies for a self-developed SiPM-based PET detector, including pulse height and different integration methods, are evaluated in terms of energy resolution and spread of the crystal response in the flood histogram using a root-mean-squared (RMS) index. Results show that integrations outperform the pulse height. Integration using the maximum derivative value of the pulse E as the landmark point and 28 integrated points (448 ns) has the best performance in these evaluated methods for our detector. Detector performance in terms of energy and position is improved with this integration method. The proposed methodology is expected to be applicable for other light-sharing PET detectors.

  10. A fast preamplifier concept for SiPM-based time-of-flight PET detectors

    Energy Technology Data Exchange (ETDEWEB)

    Huizenga, J., E-mail: j.huizenga@tudelft.nl [Delft University of Technology, Radiation Detection and Medical Imaging, Mekelweg 15, 2629 JB Delft (Netherlands); Seifert, S. [Delft University of Technology, Radiation Detection and Medical Imaging, Mekelweg 15, 2629 JB Delft (Netherlands); Schreuder, F. [Kernfysisch Versneller Instituut, University of Groningen, Zernikelaan 25, 9747 AA Groningen (Netherlands); Dam, H.T. van [Delft University of Technology, Radiation Detection and Medical Imaging, Mekelweg 15, 2629 JB Delft (Netherlands); Dendooven, P.; Loehner, H.; Vinke, R. [Kernfysisch Versneller Instituut, University of Groningen, Zernikelaan 25, 9747 AA Groningen (Netherlands); Schaart, D.R. [Delft University of Technology, Radiation Detection and Medical Imaging, Mekelweg 15, 2629 JB Delft (Netherlands)

    2012-12-11

    Silicon photomultipliers (SiPMs) offer high gain and fast response to light, making them interesting for fast timing applications such as time-of-flight (TOF) PET. To fully exploit the potential of these photosensors, dedicated preamplifiers that do not deteriorate the rise time and signal-to-noise ratio are crucial. Challenges include the high sensor capacitance, typically >300 pF for a 3 mm Multiplication-Sign 3 mm SiPM sensor, as well as oscillation issues. Here we present a preamplifier concept based on low noise, high speed transistors, designed for optimum timing performance. The input stage consists of a transimpedance common-base amplifier with a very low input impedance even at high frequencies, which assures a good linearity and avoids that the high detector capacitance affects the amplifier bandwidth. The amplifier has a fast timing output as well as a 'slow' energy output optimized for determining the total charge content of the pulse. The rise time of the amplifier is about 300 ps. The measured coincidence resolving time (CRT) for 511 keV photon pairs using the amplifiers in combination with 3 mm Multiplication-Sign 3 mm SiPMs (Hamamatsu MPPC-S10362-33-050C) coupled to 3 mm Multiplication-Sign 3 mm Multiplication-Sign 5 mm LaBr{sub 3}:Ce and LYSO:Ce crystals equals 95 ps FWHM and 138 ps FWHM, respectively.

  11. A fast preamplifier concept for SiPM-based time-of-flight PET detectors

    International Nuclear Information System (INIS)

    Huizenga, J.; Seifert, S.; Schreuder, F.; Dam, H.T. van; Dendooven, P.; Löhner, H.; Vinke, R.; Schaart, D.R.

    2012-01-01

    Silicon photomultipliers (SiPMs) offer high gain and fast response to light, making them interesting for fast timing applications such as time-of-flight (TOF) PET. To fully exploit the potential of these photosensors, dedicated preamplifiers that do not deteriorate the rise time and signal-to-noise ratio are crucial. Challenges include the high sensor capacitance, typically >300 pF for a 3 mm×3 mm SiPM sensor, as well as oscillation issues. Here we present a preamplifier concept based on low noise, high speed transistors, designed for optimum timing performance. The input stage consists of a transimpedance common-base amplifier with a very low input impedance even at high frequencies, which assures a good linearity and avoids that the high detector capacitance affects the amplifier bandwidth. The amplifier has a fast timing output as well as a ‘slow’ energy output optimized for determining the total charge content of the pulse. The rise time of the amplifier is about 300 ps. The measured coincidence resolving time (CRT) for 511 keV photon pairs using the amplifiers in combination with 3 mm×3 mm SiPMs (Hamamatsu MPPC-S10362-33-050C) coupled to 3 mm×3 mm×5 mm LaBr 3 :Ce and LYSO:Ce crystals equals 95 ps FWHM and 138 ps FWHM, respectively.

  12. Development of a alpha spectrometer system with the surface barrier detector

    International Nuclear Information System (INIS)

    Alencar, Marcus Alexandre Vallini de

    1994-04-01

    The aim of this work is the development of an α spectrometer of low cost and home made technology. The spectrometer is mounted in a double NIM module and includes a surface barrier detector and dedicate electronic system. Six barrier surface detectors were made, three of which with η type silicon wafer 3350 Ω.cm, 270mm 2 and three other with ρ type silicon wafer 5850 Ω.cm and 220mm 2 . The rectifier and the ohmic contacts were prepared at high vacuum (10 -2 to 10 -3 Pa) evaporation with 40μg/cm 2 of Au and Al respectively for the η type detectors, and with Al and Au respectively for the ρ type detectors. The electronic system is composed by a low noise charge sensitive preamplifier with the operational amplifier LF-356 mounted with 1OOMΩ feedback resistor and a 0.5 pF capacitor. The linear amplifier is also based in the LF-356 and the LM-310 operational amplifier. The bipolar output is formatted through a (CR) 2- (RC) 4 shaping network and the unipolar output is obtained through a CR-(RC) 4 shaping system which is sufficient to realize a almost true Gaussian shaping pulse with a time constant of 3.0μs. This format was chosen because we can expect a low counting rate and the gaussian pulse can improve the signal/noise ratio. The first CR differentiation has also a active pole-zero cancellation network.The resolution of detectors for 241 Am α particles at room temperature (24 degree) vary 21 to 44 keV FWHM. The electronic noise of the noise of the system is 7.5 keV FWHM at OpF input capacitance. The overall resolution of the spectrometer was found to be 62 keV FWHM at room temperature. The simplicity of the electronic system, the low cost of the construction and the overall resolution show that this alpha spectrometer can be readily used in measurements where high resolution is not a premium. (author)

  13. Pulse-height response of silicon surface-barrier detectors to high-energy heavy ions

    International Nuclear Information System (INIS)

    Smith, G.D.

    1973-01-01

    The pulse-height defect (PHD) of high-energy heavy ions in silicon surface-barrier detectors can be divided into three components: (1) energy loss in the gold-surface layer, (2) a nuclear-stopping defect, and (3) a defect due to recombination of electron-hole pairs in the plasma created by the heavy ion. The plasma recombination portion of the PHD was the subject of this study using the variation of the PHD with (1) the angle of incidence of incoming heavy ions, and (2) changes in the detector bias. The Tandem Van de Graaff accelerator at Argonne National Laboratory was used to produce scattered beam ions ( 32 S, 35 Cl) and heavy target recoils (Ni, Cu, 98 Mo, Ag, Au) at sufficient energies to produce a significant recombination defect. The results confirm the existence of a recombination zone at the front surface of these detectors and the significance of plasma recombination as a portion of the pulse-height defect. (Diss. Abstr. Int., B)

  14. The role of deep level traps in barrier height of 4H-SiC Schottky diode

    Energy Technology Data Exchange (ETDEWEB)

    Zaremba, G., E-mail: gzaremba@ite.waw.pl [Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Adamus, Z. [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Jung, W.; Kaminska, E.; Borysiewicz, M.A.; Korwin-Mikke, K. [Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw (Poland)

    2012-09-01

    This paper presents a discussion about the influence of deep level defects on the height of Ni-Si based Schottky barriers to 4H-SiC. The defects were characterized by deep level transient spectroscopy (DLTS) in a wide range of temperatures (78-750 K). The numerical simulation of barrier height value as a function of dominant defect concentration was carried out to estimate concentration, necessary to 'pin' Fermi level and thus significantly influence the barrier height. From comparison of the results of simulation with barrier height values obtained by capacitance-voltage (C-V) measurements it seems that dominant defect in measured concentration has a very small impact on the barrier height and on the increase of reverse current.

  15. Development of Ge/NbSi detectors for EDELWEISS-II with identification of near-surface events

    International Nuclear Information System (INIS)

    Juillard, A.; Marnieros, S.; Dolgorouky, Y.; Berge, L.; Collin, S.; Fiorucci, S.; Lalu, F.; Dumoulin, L.

    2006-01-01

    The actual limitation of Ge ionization heat cryogenic detectors for direct WIMP detection such as EDELWEISS arises from incomplete charge collection for near-surface events. We present results on Ge/NbSi detectors that are fitted with segmented electrodes and two NbSi Anderson insulator thermometric layers. Three such bolometers were studied in the low-background cryostat of the EDELWEISS collaboration in the LSM: analysis of the athermal signals allows us to identify and reject events occurring in the first millimeter under the electrodes

  16. Development of Ge/NbSi detectors for EDELWEISS-II with identification of near-surface events

    Energy Technology Data Exchange (ETDEWEB)

    Juillard, A. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse (CSNSM), IN2P3/CNRS, Bat 108, Orsay Campus 91405 (France)]. E-mail: juillard@csnsm.in2p3.fr; Marnieros, S. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse (CSNSM), IN2P3/CNRS, Bat 108, Orsay Campus 91405 (France); Dolgorouky, Y. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse (CSNSM), IN2P3/CNRS, Bat 108, Orsay Campus 91405 (France); Berge, L. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse (CSNSM), IN2P3/CNRS, Bat 108, Orsay Campus 91405 (France); Collin, S. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse (CSNSM), IN2P3/CNRS, Bat 108, Orsay Campus 91405 (France); Fiorucci, S. [C.E.A, Centre d' etudes Nucleaires de Saclay, DSM/DAPNIA, Gif. Yvette, Cedex 91191n (France); Lalu, F. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse (CSNSM), IN2P3/CNRS, Bat 108, Orsay Campus 91405 (France); Dumoulin, L. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse (CSNSM), IN2P3/CNRS, Bat 108, Orsay Campus 91405 (France)

    2006-04-15

    The actual limitation of Ge ionization heat cryogenic detectors for direct WIMP detection such as EDELWEISS arises from incomplete charge collection for near-surface events. We present results on Ge/NbSi detectors that are fitted with segmented electrodes and two NbSi Anderson insulator thermometric layers. Three such bolometers were studied in the low-background cryostat of the EDELWEISS collaboration in the LSM: analysis of the athermal signals allows us to identify and reject events occurring in the first millimeter under the electrodes.

  17. HfO2 and SiO2 as barriers in magnetic tunneling junctions

    Science.gov (United States)

    Shukla, Gokaran; Archer, Thomas; Sanvito, Stefano

    2017-05-01

    SiO2 and HfO2 are both high-k, wide-gap semiconductors, currently used in the microelectronic industry as gate barriers. Here we investigate whether the same materials can be employed to make magnetic tunnel junctions, which in principle can be amenable for integration in conventional Si technology. By using a combination of density functional theory and the nonequilibrium Green's functions method for quantum transport we have studied the transport properties of Co [0001 ] /SiO2[001 ] /Co [0001 ] and Fe [001 ] /HfO2[001 ] /Fe [001 ] junctions. In both cases we found a quite large magnetoresistance, which is explained through the analysis of the real band structure of the magnets and the complex one of the insulator. We find that there is no symmetry spin filtering for the Co-based junction since the high transmission Δ2' band crosses the Fermi level, EF, for both spin directions. However, the fact that Co is a strong ferromagnet makes the orbital contribution to the two Δ2' spin subbands different, yielding magnetoresistance. In contrast for the Fe-based junction symmetry filtering is active for an energy window spanning between the Fermi level and 1 eV below EF, with Δ1 symmetry contributing to the transmission.

  18. Reactive diffusion in Sc/Si multilayer X-ray mirrors with CrB2 barrier layers

    International Nuclear Information System (INIS)

    Pershyn, Y.P.; Zubarev, E.N.; Kondratenko, V.V.; Sevryukova, V.A.; Kurbatova, S.V.

    2011-01-01

    Processes undergoing in Sc/Si multilayer X-ray mirrors (MXMs) with periods of ∝27 nm and barrier layers of CrB 2 0.3- and 0.7-nm thick within the temperature range of 420-780 K were studied by methods of small-angle X-ray reflectivity (λ=0.154 nm) and cross-sectional transmission electron microscopy. All layers with the exception of Sc ones are amorphous. Barrier layers are stable at least up to a temperature of 625 K and double the activation energy of diffusional intermixing at moderate temperatures. Introduction of barriers improves the thermal stability of Sc/Si MXMs at least by 80 degrees. Diffusion of Si atoms through barrier layers into Sc layers with formation of silicides was shown to be the main degradation mechanism of MXMs. A comparison of the stability for Sc/Si MXMs with different barriers published in the literature is conducted. The ways of further improvement of barrier properties are discussed. (orig.)

  19. Development of a circular shape Si-PM-based detector ring for breast-dedicated PET system

    Science.gov (United States)

    Nakanishi, Kouhei; Yamamoto, Seiichi; Watabe, Hiroshi; Abe, Shinji; Fujita, Naotoshi; Kato, Katsuhiko

    2018-02-01

    In clinical situations, various breast-dedicated positron emission tomography (PET) systems have been used. However, clinical breast-dedicated PET systems have polygonal detector ring. Polygonal detector ring sometimes causes image artifact, so complicated reconstruction algorithm is needed to reduce artifact. Consequently, we developed a circular detector ring for breast-dedicated PET to obtain images without artifact using a simple reconstruction algorithm. We used Lu1.9Gd0.1SiO5 (LGSO) scintillator block which was made of 1.5 x 1.9 x 15 mm pixels that were arranged in an 8 x 24 matrix. As photodetectors, we used silicon photomultiplier (Si-PM) arrays whose channel size was 3 x 3 mm. A detector unit was composed of four scintillator blocks, 16 Si-PM arrays and a light guide. The developed detector unit had angled configuration since the light guide was bending. A detector unit had three gaps with an angle of 5.625° between scintillator blocks. With these configurations, we could arrange 64 scintillator blocks in nearly circular shape (regular 64-sided polygon) using 16 detector units. The use of the smaller number of detector units could reduce the size of the front-end electronics circuits. The inner diameter of the developed detector ring was 260 mm. This size was similar to those of brain PET systems, so our breast-dedicated PET detector ring can measure not only breast but also brain. Measured radial, tangential and axial spatial resolution of the detector ring reconstructed by the filtered back-projection (FBP) algorithm were 2.1 mm FWHM, 2.0 mm FWHM and 1.7 mm FWHM at center of field of view (FOV), respectively. The sensitivity was 2.0% at center of the axial FOV. With the developed detector ring, we could obtain high resolution image of the breast phantom and the brain phantom. We conclude that our developed Si-PM-based detector ring is promising for a high resolution breast-dedicated PET system that can also be used for brain PET system.

  20. The Development of 2700-3000 F Environmental Barrier Coatings for SiC/SiC Ceramic Matrix Composites: Challenges and Opportunities

    Science.gov (United States)

    Zhu, Dongming

    2015-01-01

    Environmental barrier coatings (EBCs) and SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in future turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is a key to enable the applications of the envisioned 2700-3000F EBC - CMC systems to help achieve next generation engine performance and durability goals. This paper will primarily address the performance requirements and design considerations of environmental barrier coatings for turbine engine applications. The emphasis is placed on current NASA candidate environmental barrier coating systems for SiCSiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. The efforts have been also directed to developing prime-reliant, self-healing 2700F EBC bond coat; and high stability, lower thermal conductivity, and durable EBC top coats. Major technical barriers in developing environmental barrier coating systems, the coating integrations with next generation CMCs having the improved environmental stability, cyclic durability, erosion-impact resistance, and long-term system performance will be described. The research and development opportunities for turbine engine environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling will be discussed.

  1. Application of the pulse-shape technique to proton-alpha discrimination in Si-detector arrays

    International Nuclear Information System (INIS)

    Pausch, G.; Moszynski, M.; Wolski, D.; Bohne, W.; Grawe, H.; Hilscher, D.; Schubart, R.; De Angelis, G.; De Poli, M.

    1995-04-01

    The capability of the pulse-shape technique with reversed n-type Si detectors for discrimination of protons and alphas produced in fusion-evaporation reactions was tested at the VICKSI cyclotron in Berlin. We applied a zero-crossing technique which does not need any external time reference, and which can therefore be exploited at DC accelerators. Excellent proton-alpha discrimination in the full energy range of the evaporation spectra, but also charge and even isotope resolution for heavier ions produced in projectile fragmentation, was obtained with detectors of an existing Si ball. There is no doubt that the pulse-shape discrimination works well with detectors from serial production and under experimental conditions which are typical for nuclear structure studies. An application of this technique in Si detector arrays is obvious, but some special features must be considered in the design of the electronics. The particle discrimination depends strongly on the electric field distribution inside the detector. Stabilization of the bias voltage at the detector is therefore recommended. A consequence of the rear-side injection mode is a strong variation of the charge-collection time with energy, charge, and mass number of the detected ion. To obtain a precise energy signal it is indispensable to correct for the ballistic deficit. (orig.)

  2. A low cost network of spectrometer radiation detectors based on the ArduSiPM a compact transportable Software/Hardware Data Acquisition system with Arduino DUE

    International Nuclear Information System (INIS)

    Bocci, Valerio; Chiodi, Giacomo; Iacoangeli, Francesco; Nuccetelli, Massimo; Recchia, Luigi

    2015-01-01

    The necessity to use Photo Multipliers (PM) as light detector limited in the past the use of crystals in radiation handled device preferring the Geiger approach. The Silicon Photomultipliers (SiPMs) are very small and cheap, solid photon detectors with good dynamic range and single photon detection capability, they are usable to supersede cumbersome and difficult to use Photo Multipliers (PM). A SiPM can be coupled with a scintillator crystal to build efficient, small and solid radiation detector. A cost effective and easily replicable Hardware software module for SiPM detector readout is made using the ArduSiPM solution. The ArduSiPM is an easily battery operable handled device using an Arduino DUE (an open Software/Hardware board) as processor board and a piggy-back custom designed board (ArduSiPM Shield), the Shield contains all the blocks features to monitor, set and acquire the SiPM using internet network. (authors)

  3. A low cost network of spectrometer radiation detectors based on the ArduSiPM a compact transportable Software/Hardware Data Acquisition system with Arduino DUE

    Energy Technology Data Exchange (ETDEWEB)

    Bocci, Valerio; Chiodi, Giacomo; Iacoangeli, Francesco; Nuccetelli, Massimo; Recchia, Luigi [INFN Sezione di Roma, P.le Aldo moro 2, Rome, I-00185 (Italy)

    2015-07-01

    The necessity to use Photo Multipliers (PM) as light detector limited in the past the use of crystals in radiation handled device preferring the Geiger approach. The Silicon Photomultipliers (SiPMs) are very small and cheap, solid photon detectors with good dynamic range and single photon detection capability, they are usable to supersede cumbersome and difficult to use Photo Multipliers (PM). A SiPM can be coupled with a scintillator crystal to build efficient, small and solid radiation detector. A cost effective and easily replicable Hardware software module for SiPM detector readout is made using the ArduSiPM solution. The ArduSiPM is an easily battery operable handled device using an Arduino DUE (an open Software/Hardware board) as processor board and a piggy-back custom designed board (ArduSiPM Shield), the Shield contains all the blocks features to monitor, set and acquire the SiPM using internet network. (authors)

  4. Schottky barrier height measurements of Cu/Si(001), Ag/Si(001), and Au/Si(001) interfaces utilizing ballistic electron emission microscopy and ballistic hole emission microscopy

    International Nuclear Information System (INIS)

    Balsano, Robert; Matsubayashi, Akitomo; LaBella, Vincent P.

    2013-01-01

    The Schottky barrier heights of both n and p doped Cu/Si(001), Ag/Si(001), and Au/Si(001) diodes were measured using ballistic electron emission microscopy and ballistic hole emission microscopy (BHEM), respectively. Measurements using both forward and reverse ballistic electron emission microscopy (BEEM) and (BHEM) injection conditions were performed. The Schottky barrier heights were found by fitting to a linearization of the power law form of the Bell-Kaiser BEEM model. The sum of the n-type and p-type barrier heights are in good agreement with the band gap of silicon and independent of the metal utilized. The Schottky barrier heights are found to be below the region of best fit for the power law form of the BK model, demonstrating its region of validity

  5. The Development of Environmental Barrier Coatings for SiCSiC Ceramic Matrix Composites: Challenges and Opportunities

    Science.gov (United States)

    Zhu, Dongming

    2014-01-01

    Environmental barrier coatings (EBCs) and SiC/SiC ceramic matrix composites (CMCs) systems will play a crucial role in future turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is a key to enable the applications of the envisioned CMC components to help achieve next generation engine performance and durability goals. This paper will primarily address the performance requirements and design considerations of environmental barrier coatings for turbine engine applications. The emphasis is placed on current candidate environmental barrier coating systems for SiCSiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. Major technical barriers in developing advanced environmental barrier coating systems, the coating integrations with next generation CMC turbine components having improved environmental stability, cyclic durability and system performance will be described. The development trends for turbine environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling will be discussed.

  6. Effect of graphene tunnel barrier on Schottky barrier height of Heusler alloy Co2MnSi/graphene/n-Ge junction

    International Nuclear Information System (INIS)

    Li Gui-fang; Hu Jing; Lv Hui; Cui Zhijun; Hou Xiaowei; Liu Shibin; Du Yongqian

    2016-01-01

    We demonstrate that the insertion of a graphene tunnel barrier between Heusler alloy Co 2 MnSi and the germanium (Ge) channel modulates the Schottky barrier height and the resistance–area product of the spin diode. We confirm that the Fermi level is depinned and a reduction in the electron Schottky barrier height (SBH) occurs following the insertion of the graphene layer between Co 2 MnSi and Ge. The electron SBH is modulated in the 0.34 eV–0.61 eV range. Furthermore, the transport mechanism changes from rectifying to symmetric tunneling following the insertion. This behavior provides a pathway for highly efficient spin injection from a Heusler alloy into a Ge channel with high electron and hole mobility. (paper)

  7. Effect of graphene tunnel barrier on Schottky barrier height of Heusler alloy Co2MnSi/graphene/n-Ge junction

    Science.gov (United States)

    Gui-fang, Li; Jing, Hu; Hui, Lv; Zhijun, Cui; Xiaowei, Hou; Shibin, Liu; Yongqian, Du

    2016-02-01

    We demonstrate that the insertion of a graphene tunnel barrier between Heusler alloy Co2MnSi and the germanium (Ge) channel modulates the Schottky barrier height and the resistance-area product of the spin diode. We confirm that the Fermi level is depinned and a reduction in the electron Schottky barrier height (SBH) occurs following the insertion of the graphene layer between Co2MnSi and Ge. The electron SBH is modulated in the 0.34 eV-0.61 eV range. Furthermore, the transport mechanism changes from rectifying to symmetric tunneling following the insertion. This behavior provides a pathway for highly efficient spin injection from a Heusler alloy into a Ge channel with high electron and hole mobility. Project supported by the National Natural Science Foundation of China (Grant No. 61504107) and the Fundamental Research Funds for the Central Universities, China (Grant Nos. 3102014JCQ01059 and 3102015ZY043).

  8. Nuclear radiation detector based on ion implanted p-n junction in 4H-SiC

    International Nuclear Information System (INIS)

    Vervisch, V.; Issa, F.; Ottaviani, L.; Lazar, M.; Kuznetsov, A.; Szalkai, D.; Klix, A.; Lyoussi, A.; Vermeeren, L.; Hallen, A.

    2013-06-01

    In this paper, we propose a new device detector based on ion implanted p-n junction in 4H-SiC for nuclear instrumentation. We showed the interest to use 10 Boron as a Neutron Converter Layer in order to detect thermal neutrons. We present the main results obtained during irradiation tests performed in the Belgian Reactor 1. We show the capability of our detector by means of first results of the detector response at different reverse voltage biases and at different reactor power (authors)

  9. Improvement of thick a-Si radiation detectors by field profile tailoring

    International Nuclear Information System (INIS)

    Drewery, J.S.; Cho, G.; Jing, T.; Kaplan, S.N.; Mireshghi, A.; Perez-Mendez, V.; Wildermuth, D.

    1992-04-01

    Application of thick (∼50 μm) a-Si p-i-n diodes as a direct radiation detector for minimum ionizing particles is hampered by the need to apply large bias voltages in order fully to deplete the detecting intrinsic layer, which typically contains 5 - 10 x 10 14 ionizable dangling bonds per CM 3 . By insertion of thin p-type layers at intervals within the intrinsic layer, the required depletion voltage can be reduced by a factor of at least 1/(n+l) where n is the number of layers inserted. This principle is demonstrated for devices approximately 12μm in thickness. It is shown that electron losses within the p type layer can be kept to minimum by choice of a low doping concentration for the introduced players

  10. Plasma-polymerized SiOx deposition on polymer film surfaces for preparation of oxygen gas barrier polymeric films

    International Nuclear Information System (INIS)

    Inagaki, N.

    2003-01-01

    SiOx films were deposited on surfaces of three polymeric films, PET, PP, and Nylon; and their oxygen gas barrier properties were evaluated. To mitigate discrepancies between the deposited SiOx and polymer film, surface modification of polymer films was done, and how the surface modification could contribute to was discussed from the viewpoint of apparent activation energy for the permeation process. The SiOx deposition on the polymer film surfaces led to a large decrease in the oxygen permeation rate. Modification of polymer film surfaces by mans of the TMOS or Si-COOH coupling treatment in prior to the SiOx deposition was effective in decreasing the oxygen permeation rate. The cavity model is proposed as an oxygen permeation process through the SiOx-deposited Nylon film. From the proposed model, controlling the interface between the deposited SiOx film and the polymer film is emphasized to be a key factor to prepare SiOx-deposited polymer films with good oxygen gas barrier properties. (author)

  11. Development of an MRI-compatible digital SiPM detector stack for simultaneous PET/MRI.

    Science.gov (United States)

    Düppenbecker, Peter M; Weissler, Bjoern; Gebhardt, Pierre; Schug, David; Wehner, Jakob; Marsden, Paul K; Schulz, Volkmar

    2016-02-01

    Advances in solid-state photon detectors paved the way to combine positron emission tomography (PET) and magnetic resonance imaging (MRI) into highly integrated, truly simultaneous, hybrid imaging systems. Based on the most recent digital SiPM technology, we developed an MRI-compatible PET detector stack, intended as a building block for next generation simultaneous PET/MRI systems. Our detector stack comprises an array of 8 × 8 digital SiPM channels with 4 mm pitch using Philips Digital Photon Counting DPC 3200-22 devices, an FPGA for data acquisition, a supply voltage control system and a cooling infrastructure. This is the first detector design that allows the operation of digital SiPMs simultaneously inside an MRI system. We tested and optimized the MRI-compatibility of our detector stack on a laboratory test bench as well as in combination with a Philips Achieva 3 T MRI system. Our design clearly reduces distortions of the static magnetic field compared to a conventional design. The MRI static magnetic field causes weak and directional drift effects on voltage regulators, but has no direct impact on detector performance. MRI gradient switching initially degraded energy and timing resolution. Both distortions could be ascribed to voltage variations induced on the bias and the FPGA core voltage supply respectively. Based on these findings, we improved our detector design and our final design shows virtually no energy or timing degradations, even during heavy and continuous MRI gradient switching. In particular, we found no evidence that the performance of the DPC 3200-22 digital SiPM itself is degraded by the MRI system.

  12. A planar Al-Si Schottky barrier metal–oxide–semiconductor field effect transistor operated at cryogenic temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Purches, W. E. [School of Physics, UNSW, Sydney 2052 (Australia); Rossi, A.; Zhao, R. [School of Electrical Engineering and Telecommunications, UNSW, Sydney 2052 (Australia); Kafanov, S.; Duty, T. L. [School of Physics, UNSW, Sydney 2052 (Australia); Centre for Engineered Quantum Systems (EQuS), School of Physics, UNSW, Sydney 2052 (Australia); Dzurak, A. S. [School of Electrical Engineering and Telecommunications, UNSW, Sydney 2052 (Australia); Australian Centre of Excellence for Quantum Computation and Communication Technology (CQC2T), UNSW, Sydney 2052 (Australia); Rogge, S.; Tettamanzi, G. C., E-mail: g.tettamanzi@unsw.edu.au [School of Physics, UNSW, Sydney 2052 (Australia); Australian Centre of Excellence for Quantum Computation and Communication Technology (CQC2T), UNSW, Sydney 2052 (Australia)

    2015-08-10

    Schottky Barrier-MOSFET technology offers intriguing possibilities for cryogenic nano-scale devices, such as Si quantum devices and superconducting devices. We present experimental results on a device architecture where the gate electrode is self-aligned with the device channel and overlaps the source and drain electrodes. This facilitates a sub-5 nm gap between the source/drain and channel, and no spacers are required. At cryogenic temperatures, such devices function as p-MOS Tunnel FETs, as determined by the Schottky barrier at the Al-Si interface, and as a further advantage, fabrication processes are compatible with both CMOS and superconducting logic technology.

  13. Single channel analog pulse processor Asic for gas proportional counters and SI detector

    International Nuclear Information System (INIS)

    Chandratre, V.B.; Sarkar, Soumen; Kataria, S.K.; Viyogi, Y.P.

    2005-01-01

    The paper presents the design and development of a single channel pulse processor in short Singleplex ASIC targeted for gas proportional counters/Si detectors. The design is optimized for the dynamic range of +500 fC to -500 fC with provision for externally adjusted pole-zero cancellation. A dedicated filter based on the de-convolution principle is used for the cancellation of the long hyperbolic signal tail produced by the slow drift of ions, typical in gas proportional with the filter time constants derived from the actual detector input signal shape. The pole-zero adjustment can be done by external dc voltage to achieve perfect base-line recovery to 1% after 5 μs. The simulated 0 pf noise is 500 e - rms for the peaking time of 1.2 μs with noise slope of 7e - -. The gain is 3.4 mv/fC over the entire linear dynamic range with power dissipation of 13 mW. This design is a modified version of Indiplex chip with features dynamic range equal gain on both polarities with nearly same noise and serves as diagnostic chip for Indiplex. The chip can be used for radiation monitoring instruments. (author)

  14. Fully solution processed Al-TiO2-Si (MIS) structured photo-detector

    Science.gov (United States)

    Mondal, Sandip; Kumar, Arvind

    2018-05-01

    We demonstrate the fabrication of a high performance photo detector by fully solution processed technique. The detector is fabricated with photo sensitive, low temperature (200˚C) and sol-gel processed titanium dioxide (TiO2) dielectric material on silicon substrate in the form of MIS structure with top aluminum gate. The optical detection experiment is performed on Al—TiO2—Si (MIS) device by measuring the capacitance—voltage (CV at 100 kHz) curve within the visible region of light (365 — 700 nm). The presence of light shift the flat band voltage (VFB) from 290 mV to 360 mV due to the generation of photo activated charge carriers by UV (365 nm) and white light, respectively. Moreover, the generation of the charge carrier increases drastically by the combination of UV and white, which resulting as a very large shift (600 mV) in the VFB. The entire experiment was performed in normal lab conditions with open air environment, without any clean room facility.

  15. Particle Identification performance for leptons in jets for the CLIC ILD and CLIC SiD detectors

    CERN Document Server

    Nardulli, J

    2011-01-01

    This note describes the particle identification performance for particles in jets for the CLIC ILD and CLIC SiD detector concepts as prepared in the CLIC Conceptual Design Report. The results are presented with and without the presence of the γγ → hadrons background events.

  16. Mechanical Properties and Real-Time Damage Evaluations of Environmental Barrier Coated SiC/SiC CMCs Subjected to Tensile Loading Under Thermal Gradients

    Science.gov (United States)

    Appleby, Matthew; Zhu, Dongming; Morscher, Gregory

    2015-01-01

    SiC/SiC ceramic matrix composites (CMCs) require new state-of-the art environmental barrier coatings (EBCs) to withstand increased temperature requirements and high velocity combustion corrosive combustion gasses. The present work compares the response of coated and uncoated SiC/SiC CMC substrates subjected to simulated engine environments followed by high temperature mechanical testing to asses retained properties and damage mechanisms. Our focus is to explore the capabilities of electrical resistance (ER) measurements as an NDE technique for testing of retained properties under combined high heat-flux and mechanical loading conditions. Furthermore, Acoustic Emission (AE) measurements and Digital Image Correlation (DIC) were performed to determine material damage onset and accumulation.

  17. Creep, Fatigue and Fracture Behavior of Environmental Barrier Coating and SiC-SiC Ceramic Matrix Composite Systems: The Role of Environment Effects

    Science.gov (United States)

    Zhu, Dongming; Ghosn, Louis J.

    2015-01-01

    Advanced environmental barrier coating (EBC) systems for low emission SiCSiC CMC combustors and turbine airfoils have been developed to meet next generation engine emission and performance goals. This presentation will highlight the developments of NASAs current EBC system technologies for SiC-SiC ceramic matrix composite combustors and turbine airfoils, their performance evaluation and modeling progress towards improving the engine SiCSiC component temperature capability and long-term durability. Our emphasis has also been placed on the fundamental aspects of the EBC-CMC creep and fatigue behaviors, and their interactions with turbine engine oxidizing and moisture environments. The EBC-CMC environmental degradation and failure modes, under various simulated engine testing environments, in particular involving high heat flux, high pressure, high velocity combustion conditions, will be discussed aiming at quantifying the protective coating functions, performance and durability, and in conjunction with damage mechanics and fracture mechanics approaches.

  18. Spin accumulation in Si channels using CoFe/MgO/Si and CoFe/AlOx/Si tunnel contacts with high quality tunnel barriers prepared by radical-oxygen annealing

    International Nuclear Information System (INIS)

    Akushichi, T.; Shuto, Y.; Sugahara, S.; Takamura, Y.

    2015-01-01

    We investigate spin injection into Si channels using three-terminal spin-accumulation (3T-SA) devices with high-quality CoFe/MgO/n-Si and CoFe/AlO x /n-Si tunnel spin-injectors whose tunnel barriers are formed by radical oxidation of Mg and Al thin films deposited on Si(100) substrates and successive annealing under radical-oxygen exposure. When the MgO and AlO x barriers are not treated by the radical-oxygen annealing, the Hanle-effect signals obtained from the 3T-SA devices are closely fitted by a single Lorentz function representing a signal due to trap spins. On the other hand, when the tunnel barriers are annealed under radical-oxygen exposure, the Hanle-effect signals can be accurately fitted by the superposition of a Lorentz function and a non-Lorentz function representing a signal due to accumulated spins in the Si channel. These results suggest that the quality improvement of tunnel barriers treated by radical-oxygen annealing is highly effective for spin-injection into Si channels

  19. Development of a composite large-size SiPM (assembled matrix) based modular detector cluster for MAGIC

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, A., E-mail: ahahn@mpp.mpg.de [Max Planck Institute for Physics (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München (Germany); Mazin, D., E-mail: mazin@mpp.mpg.de [Max Planck Institute for Physics (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München (Germany); Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwa-no-Ha, Kashiwa City, Chiba 277–8582 (Japan); Bangale, P., E-mail: priya@mpp.mpg.de [Max Planck Institute for Physics (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München (Germany); Dettlaff, A., E-mail: todettl@mpp.mpg.de [Max Planck Institute for Physics (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München (Germany); Fink, D., E-mail: fink@mpp.mpg.de [Max Planck Institute for Physics (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München (Germany); Grundner, F., E-mail: grundner@mpp.mpg.de [Max Planck Institute for Physics (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München (Germany); Haberer, W., E-mail: haberer@mpp.mpg.de [Max Planck Institute for Physics (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München (Germany); Maier, R., E-mail: rma@mpp.mpg.de [Max Planck Institute for Physics (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München (Germany); and others

    2017-02-11

    The MAGIC collaboration operates two 17 m diameter Imaging Atmospheric Cherenkov Telescopes (IACTs) on the Canary Island of La Palma. Each of the two telescopes is currently equipped with a photomultiplier tube (PMT) based imaging camera. Due to the advances in the development of Silicon Photomultipliers (SiPMs), they are becoming a widely used alternative to PMTs in many research fields including gamma-ray astronomy. Within the Otto-Hahn group at the Max Planck Institute for Physics, Munich, we are developing a SiPM based detector module for a possible upgrade of the MAGIC cameras and also for future experiments as, e.g., the Large Size Telescopes (LST) of the Cherenkov Telescope Array (CTA). Because of the small size of individual SiPM sensors (6 mm×6 mm) with respect to the 1-inch diameter PMTs currently used in MAGIC, we use a custom-made matrix of SiPMs to cover the same detection area. We developed an electronic circuit to actively sum up and amplify the SiPM signals. Existing non-imaging hexagonal light concentrators (Winston cones) used in MAGIC have been modified for the angular acceptance of the SiPMs by using C++ based ray tracing simulations. The first prototype based detector module includes seven channels and was installed into the MAGIC camera in May 2015. We present the results of the first prototype and its performance as well as the status of the project and discuss its challenges. - Highlights: • The design of the first SiPM large-size IACT pixel is described. • The simulation of the light concentrators is presented. • The temperature stability of the detector module is demonstrated. • The calibration procedure of SiPM device in the field is described.

  20. Penetrating heavy ion charge and velocity discrimination with a TimePix-based Si detector (for space radiation applications)

    Energy Technology Data Exchange (ETDEWEB)

    Pinsky, Lawrence S., E-mail: pinsky@uh.edu [University of Houston, 4800 Calhoun Blvd., Houston, TX 77204-5005 (United States); Empl, Anton [University of Houston, 4800 Calhoun Blvd., Houston, TX 77204-5005 (United States); Gutierrez, Andrea [University of Montreal, 2905 Chemin des services, Montreal, Que., H3T 1J4 (Canada); Jakubek, Jan [Institute of Experimental and Applied Physics, Czech Technical University, Horska 3a/22, CZ-12800 Prague 2-Albertov (Czech Republic); Kitamura, Hisashi [National Institute for Radiological Sciences, Anagawa 4-9-1, Inage, Chiba 263-8555 (Japan); Miller, Jack [Space Sciences Laboratory, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Leroy, Claude [University of Montreal, 2905 Chemin des services, Montreal, Que., H3T 1J4 (Canada); Stoffle, Nicholas [University of Houston, 4800 Calhoun Blvd., Houston, TX 77204-5005 (United States); Pospisil, Stanislav [Institute of Experimental and Applied Physics, Czech Technical University, Horska 3a/22, CZ-12800 Prague 2-Albertov (Czech Republic); Uchihori, Yukio; Yasuda, Nakahiro [National Institute for Radiological Sciences, Anagawa 4-9-1, Inage, Chiba 263-8555 (Japan); Zeitlin, Cary [Southwest Research Institute, 6220 Culebra Rd., San Antonio, TX 78238-5166 (United States)

    2011-05-15

    Exposures were made with Medipix2 TimePix-based Si detectors at the HIMAC facility in Japan to explore the potential for discrimination between tracks with differing charges and energies, but with very similar dE/dx values. Data were taken at 15 deg. increments for a number of different beams including 600 and 800 MeV/A Si, 180 MeV/A Ne and 100 MeV/A O. Data were also obtained for 400 MeV/A Si and 500 MeV/A Fe along with 290 and 180 MeV/A N. The TimePix chips have been calibrated to achieve the maximum resolution. Estimates for the angular resolution for these types of tracks are also possible from these data, which are essential in the development of a TimePix-based dosimetric device for use in a space radiation environment. One of the principal objectives of these data runs was to explore the resolution of TimePix-based Si detectors to discriminate between various ions with different energies and charges, but with similar dE/dx values in Si. Analysis of the images obtained shows the clear differences in the {delta}-ray halos for particles with similar dE/dx values but for differing charges and energies. These measurements are part of an ongoing program to explore the range of capabilities of the TimePix-based detector with respect to dosimetry uses in space.

  1. Development and Performance Evaluations of HfO2-Si and Rare Earth-Si Based Environmental Barrier Bond Coat Systems for SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming

    2014-01-01

    Ceramic environmental barrier coatings (EBC) and SiCSiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft propulsion systems because of their ability to significantly increase engine operating temperatures, improve component durability, reduce engine weight and cooling requirements. Advanced EBC systems for SiCSiC CMC turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant material development challenges for the high temperature CMC components is to develop prime-reliant, high strength and high temperature capable environmental barrier coating bond coat systems, since the current silicon bond coat cannot meet the advanced EBC-CMC temperature and stability requirements. In this paper, advanced NASA HfO2-Si based EBC bond coat systems for SiCSiC CMC combustor and turbine airfoil applications are investigated. The coating design approach and stability requirements are specifically emphasized, with the development and implementation focusing on Plasma Sprayed (PS) and Electron Beam-Physic Vapor Deposited (EB-PVD) coating systems and the composition optimizations. High temperature properties of the HfO2-Si based bond coat systems, including the strength, fracture toughness, creep resistance, and oxidation resistance were evaluated in the temperature range of 1200 to 1500 C. Thermal gradient heat flux low cycle fatigue and furnace cyclic oxidation durability tests were also performed at temperatures up to 1500 C. The coating strength improvements, degradation and failure modes of the environmental barrier coating bond coat systems on SiCSiC CMCs tested in simulated stress-environment interactions are briefly discussed and supported by modeling. The performance enhancements of the HfO2-Si bond coat systems with rare earth element dopants and rare earth-silicon based bond coats are also highlighted. The advanced bond coat systems, when

  2. Thermal Gradient Cyclic Behavior of a Thermal/Environmental Barrier Coating System on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Lee, Kang N.; Miller, Robert A.

    2002-01-01

    Thermal barrier and environmental barrier coatings (TBCs and EBCs) will play a crucial role in future advanced gas turbine engines because of their ability to significantly extend the temperature capability of the ceramic matrix composite (CMC) engine components in harsh combustion environments. In order to develop high performance, robust coating systems for effective thermal and environmental protection of the engine components, appropriate test approaches for evaluating the critical coating properties must be established. In this paper, a laser high-heat-flux, thermal gradient approach for testing the coatings will be described. Thermal cyclic behavior of plasma-sprayed coating systems, consisting of ZrO2-8wt%Y2O3 thermal barrier and NASA Enabling Propulsion Materials (EPM) Program developed mullite+BSAS/Si type environmental barrier coatings on SiC/SiC ceramic matrix composites, was investigated under thermal gradients using the laser heat-flux rig in conjunction with the furnace thermal cyclic tests in water-vapor environments. The coating sintering and interface damage were assessed by monitoring the real-time thermal conductivity changes during the laser heat-flux tests and by examining the microstructural changes after the tests. The coating failure mechanisms are discussed based on the cyclic test results and are correlated to the sintering, creep, and thermal stress behavior under simulated engine temperature and heat flux conditions.

  3. Monolayer graphene/SiC Schottky barrier diodes with improved barrier height uniformity as a sensing platform for the detection of heavy metals.

    Science.gov (United States)

    Shtepliuk, Ivan; Eriksson, Jens; Khranovskyy, Volodymyr; Iakimov, Tihomir; Lloyd Spetz, Anita; Yakimova, Rositsa

    2016-01-01

    A vertical diode structure comprising homogeneous monolayer epitaxial graphene on silicon carbide is fabricated by thermal decomposition of a Si-face 4H-SiC wafer in argon atmosphere. Current-voltage characteristics of the graphene/SiC Schottky junction were analyzed by applying the thermionic-emission theory. Extracted values of the Schottky barrier height and the ideality factor are found to be 0.4879 ± 0.013 eV and 1.01803 ± 0.0049, respectively. Deviations of these parameters from average values are smaller than those of previously observed literature data, thereby implying uniformity of the Schottky barrier height over the whole diode area, a stable rectifying behaviour and a good quality of ohmic palladium-graphene contacts. Keeping in mind the strong sensitivity of graphene to analytes we propose the possibility to use the graphene/SiC Schottky diode as a sensing platform for the recognition of toxic heavy metals. Using density functional theory (DFT) calculations we gain insight into the nature of the interaction of cadmium, mercury and lead with graphene as well as estimate the work function and the Schottky barrier height of the graphene/SiC structure before and after applying heavy metals to the sensing material. A shift of the I - V characteristics of the graphene/SiC-based sensor has been proposed as an indicator of presence of the heavy metals. Since the calculations suggested the strongest charge transfer between Pb and graphene, the proposed sensing platform was characterized by good selectivity towards lead atoms and slight interferences from cadmium and mercury. The dependence of the sensitivity parameters on the concentration of Cd, Hg and Pb is studied and discussed.

  4. Monolayer graphene/SiC Schottky barrier diodes with improved barrier height uniformity as a sensing platform for the detection of heavy metals

    Directory of Open Access Journals (Sweden)

    Ivan Shtepliuk

    2016-11-01

    Full Text Available A vertical diode structure comprising homogeneous monolayer epitaxial graphene on silicon carbide is fabricated by thermal decomposition of a Si-face 4H-SiC wafer in argon atmosphere. Current–voltage characteristics of the graphene/SiC Schottky junction were analyzed by applying the thermionic-emission theory. Extracted values of the Schottky barrier height and the ideality factor are found to be 0.4879 ± 0.013 eV and 1.01803 ± 0.0049, respectively. Deviations of these parameters from average values are smaller than those of previously observed literature data, thereby implying uniformity of the Schottky barrier height over the whole diode area, a stable rectifying behaviour and a good quality of ohmic palladium–graphene contacts. Keeping in mind the strong sensitivity of graphene to analytes we propose the possibility to use the graphene/SiC Schottky diode as a sensing platform for the recognition of toxic heavy metals. Using density functional theory (DFT calculations we gain insight into the nature of the interaction of cadmium, mercury and lead with graphene as well as estimate the work function and the Schottky barrier height of the graphene/SiC structure before and after applying heavy metals to the sensing material. A shift of the I–V characteristics of the graphene/SiC-based sensor has been proposed as an indicator of presence of the heavy metals. Since the calculations suggested the strongest charge transfer between Pb and graphene, the proposed sensing platform was characterized by good selectivity towards lead atoms and slight interferences from cadmium and mercury. The dependence of the sensitivity parameters on the concentration of Cd, Hg and Pb is studied and discussed.

  5. Modeling of 4H—SiC multi-floating-junction Schottky barrier diode

    International Nuclear Information System (INIS)

    Hong-Bin, Pu; Lin, Cao; Zhi-Ming, Chen; Jie, Ren; Ya-Gong, Nan

    2010-01-01

    This paper develops a new and easy to implement analytical model for the specific on-resistance and electric field distribution along the critical path for 4H—SiC multi-floating junction Schottky barrier diode. Considering the charge compensation effects by the multilayer of buried opposite doped regions, it improves the breakdown voltage a lot in comparison with conventional one with the same on-resistance. The forward resistance of the floating junction Schottky barrier diode consists of several components and the electric field can be understood with superposition concept, both are consistent with MEDICI simulation results. Moreover, device parameters are optimized and the analyses show that in comparison with one layer floating junction, multilayer of floating junction layer is an effective way to increase the device performance when specific resistance and the breakdown voltage are traded off. The results show that the specific resistance increases 3.2 mΩ·cm 2 and breakdown voltage increases 422 V with an additional floating junction for the given structure. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  6. Considerations for application of Si(Li) detectors in analyses of sub-keV, ion-induced x rays

    International Nuclear Information System (INIS)

    Musket, R.G.

    1985-01-01

    Spectroscopy of ion-induced x rays is commonly performed using lithium-drifted, silicon detectors, Si(Li), with beryllium windows. Strong absorption of x rays with energies below 1 keV occurs in even the thinnest commercially available beryllium windows and precludes useful analysis of sub-keV x rays. Access to the sub-keV x ray region can be achieved using windowless (WL) and ultra-thin-windowed (UTW) Si(Li) detectors. These detectors have been shown to be useful for spectroscopy of x rays with energies above approximately 200 eV. The properties of such detectors are reviewed with regard to analysis of ion-induced x rays. In particular, considerations of detection efficiency, output linearity, energy resolution, peak shapes, and vacuum requirements are presented. The use of ion excitation for determination of many detector properties serves to demonstrate the usefulness of WL and UTW detectors for the spectroscopy of sub-keV, ion-induced x rays. 23 refs., 4 figs

  7. Long-term stable water vapor permeation barrier properties of SiN/SiCN/SiN nanolaminated multilayers grown by plasma-enhanced chemical vapor deposition at extremely low pressures

    International Nuclear Information System (INIS)

    Choi, Bum Ho; Lee, Jong Ho

    2014-01-01

    We investigated the water vapor permeation barrier properties of 30-nm-thick SiN/SiCN/SiN nanolaminated multilayer structures grown by plasma enhanced chemical vapor deposition at 7 mTorr. The derived water vapor transmission rate was 1.12 × 10 −6 g/(m 2 day) at 85 °C and 85% relative humidity, and this value was maintained up to 15 000 h of aging time. The X-ray diffraction patterns revealed that the nanolaminated film was composed of an amorphous phase. A mixed phase was observed upon performing high resolution transmission electron microscope analysis, which indicated that a thermodynamically stable structure was formed. It was revealed amorphous SiN/SiCN/SiN multilayer structures that are free from intermixed interface defects effectively block water vapor permeation into active layer

  8. Development of a composite large-size SiPM (assembled matrix) based modular detector cluster for MAGIC

    Science.gov (United States)

    Hahn, A.; Mazin, D.; Bangale, P.; Dettlaff, A.; Fink, D.; Grundner, F.; Haberer, W.; Maier, R.; Mirzoyan, R.; Podkladkin, S.; Teshima, M.; Wetteskind, H.

    2017-02-01

    The MAGIC collaboration operates two 17 m diameter Imaging Atmospheric Cherenkov Telescopes (IACTs) on the Canary Island of La Palma. Each of the two telescopes is currently equipped with a photomultiplier tube (PMT) based imaging camera. Due to the advances in the development of Silicon Photomultipliers (SiPMs), they are becoming a widely used alternative to PMTs in many research fields including gamma-ray astronomy. Within the Otto-Hahn group at the Max Planck Institute for Physics, Munich, we are developing a SiPM based detector module for a possible upgrade of the MAGIC cameras and also for future experiments as, e.g., the Large Size Telescopes (LST) of the Cherenkov Telescope Array (CTA). Because of the small size of individual SiPM sensors (6 mm×6 mm) with respect to the 1-inch diameter PMTs currently used in MAGIC, we use a custom-made matrix of SiPMs to cover the same detection area. We developed an electronic circuit to actively sum up and amplify the SiPM signals. Existing non-imaging hexagonal light concentrators (Winston cones) used in MAGIC have been modified for the angular acceptance of the SiPMs by using C++ based ray tracing simulations. The first prototype based detector module includes seven channels and was installed into the MAGIC camera in May 2015. We present the results of the first prototype and its performance as well as the status of the project and discuss its challenges.

  9. Measurements of Schottky barrier at the low-k SiOC:H/Cu interface using vacuum ultraviolet photoemission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Guo, X.; Pei, D.; Zheng, H.; Shohet, J. L. [Plasma Processing and Technology Laboratory and Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); King, S. W. [Logic Technology Development, Intel Corporation, Hillsboro, Oregon 97124 (United States); Lin, Y.-H.; Fung, H.-S.; Chen, C.-C. [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China); Nishi, Y. [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States)

    2015-12-07

    The band alignment between copper interconnects and their low-k interlayer dielectrics is critical to understanding the fundamental mechanisms involved in electrical leakage in low-k/Cu interconnects. In this work, vacuum-ultraviolet (VUV) photoemission spectroscopy is utilized to determine the potential of the Schottky barrier present at low-k a-SiOC:H/Cu interfaces. By examining the photoemission spectra before and after VUV exposure of a low-k a-SiOC:H (k = 3.3) thin film fabricated by plasma-enhanced chemical-vapor deposition on a polished Cu substrate, it was found that photons with energies of 4.9 eV or greater can deplete accumulated charge in a-SiOC:H films, while VUV photons with energies of 4.7 eV or less, did not have this effect. These critical values were identified to relate the electric potential of the interface barrier between the a-SiOC:H and the Cu layers. Using this method, the Schottky barrier at the low-k a-SiOC:H (k = 3.3)/Cu interface was determined to be 4.8 ± 0.1 eV.

  10. Development of cryogenic Si detectors by CERN RD39 Collaboration for ultra radiation hardness in SLHC environment

    CERN Document Server

    Li, Z; Anbinderis, P; Anbinderis, T; D’Ambrosio, N; de Boer, Wim; Borchi, E; Borer, K; Bruzzi, M; Buontempo, S; Chen, W; Cindro, V; Dierlamm, A; Eremin, V; Gaubas, E; Gorbatenko, V; Grigoriev, E; Hauler, F; Heijne, Erik H M; Heising, S; Hempel, O; Herzog, R; Härkönen, J; Ilyashenko, I; Janos, S; Jungermann, L; Kalesinskas, V; Kapturauskas, J; Laiho, R; Luukka, P; Mandic, I; De Masi, R; Menichelli, D; Mikuz, M; Militaru, O; Niinikosky, T O; O’Shea, V; Pagano, S; Paul, S; Piotrzkowski, K; Pretzl, K; Rato-Mendes, P; Rouby, X; Ruggiero, G; Smith, K; Sonderegger, P; Sousa, P; Tuominen, E; Tuovinen, E; Verbitskaya, E; Vaitkus, J; Wobst, E; Zavrtanik, M

    2007-01-01

    There are two key approaches in our CERN RD 39 Collaboration efforts to obtain ultra-radiation-hard Si detectors: (1) use of the charge/current injection to manipulate the detector internal electric field in such a way that it can be depleted at a modest bias voltage at cryogenic temperature range (150 K), and (2) freezing out of the trapping centers that affects the CCE at cryogenic temperatures lower than that of the liquid nitrogen (LN2) temperature. In our first approach, we have developed the advanced radiation hard detectors using charge or current injection, the current injected diodes (CID). In a CID, the electric field is controlled by injected current, which is limited by the space charge, yielding a nearly uniform electric field in the detector, independent of the radiation fluence. In our second approach, we have developed models of radiation-induced trapping levels and the physics of their freezing out at cryogenic temperatures.

  11. Role of hexadecapole deformation of projectile 28Si in heavy-ion fusion reactions near the Coulomb barrier

    Science.gov (United States)

    Kaur, Gurpreet; Hagino, K.; Rowley, N.

    2018-06-01

    The vast knowledge regarding the strong influence of quadrupole deformation β2 of colliding nuclei in heavy-ion sub-barrier fusion reactions inspires a desire to quest the sensitivity of fusion dynamics to higher order deformations, such as β4 and β6 deformations. However, such studies have rarely been carried out, especially for deformation of projectile nuclei. In this article, we investigated the role of β4 of the projectile nucleus in the fusion of the 28Si+92Zr system. We demonstrated that the fusion barrier distribution is sensitive to the sign and value of the β4 parameter of the projectile, 28Si, and confirmed that the 28Si nucleus has a large positive β4. This study opens an indirect way to estimate deformation parameters of radioactive nuclei using fusion reactions, which is otherwise difficult because of experimental constraints.

  12. Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture.

    Science.gov (United States)

    Karthikeya Sharma, T

    2015-11-01

    Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE). This paper investigates the effects of using argon (Ar) gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine's performance within the range studied.

  13. Effect of La doping on interface barrier between Si-passivated Ge and insulating HfO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Kolomiiets, Nadiia M.; Afanas' ev, Valery V.; Madia, Oreste; Stesmans, Andre [Department of Physics and Astronomy, University of Leuven, Celestijnenlaan 200D, 3001 Leuven (Belgium); Cott, Daire J.; Collaert, Nadine [Imec, Kapeldreef 75, 3001 Leuven (Belgium); Thean, Aaron [Imec, Kapeldreef 75, 3001 Leuven (Belgium); National University of Singapore (Singapore)

    2016-12-15

    By analyzing internal photoemission of electrons from Si/SiO{sub x}-passivated Ge into insulating HfO{sub 2} we found that insertion of additional La interlayer between SiO{sub x} and HfO{sub 2} leads to dramatic increase (more than by factor of 20) of the barrier transparency. However, no measurable variation of the interface barrier height is observed suggesting that La induces intermixing of near-interface oxide stack resulting in development of additional density of states corresponding to conduction band of LaO{sub x} and HfO{sub x} sub-networks. At the same time, photoemission results indicate the presence of discrete positive charges in the near-interface oxide layer which may explain the observed ∝1 V shift of capacitance-voltage curves. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Characteristics of a commercial Hi-pSi detector for dosimetry of stereotactic collimators with very small diameters

    International Nuclear Information System (INIS)

    Foerster, U.; Grebe, G.; Pfaender, M.

    2002-01-01

    Background: Conformal stereotactic radiosurgery and radiotherapy with linear accelerators and hole collimators yield a dose concentration in the target volume by rotation of the gantry. For small target volumes collimators with isocentre diameters of 4-45 mm are used. In this paper dosimetric measurements with a commercial high doped p-type silicon detector are demonstrated and compared to measurements with diamond detector and ionisation chamber. Material and Methods: The properties of the silicon detector SFD trademark from Scanditronix were investigated with the radiation of a Gammatron trademark S and a Varian 2100 CD trademark at 6 MV. The results were compared with those of a calibrated ionisation chamber (0.3 cm 3 ) and a diamond detector. Measurements and Results: At the beginning the reproducibility of the registered dose and dose rate and the temperature dependence of the Si-detector were investigated at the Gammatron S. For the comparison the absorbed dose was measured with the ionisation chamber in air. The sensitivity decreases slightly with dose and dose rate. After a period of several days without radiation again higher doses were registered. The temperature dependence causes deviations of 0.25%/K. The signal-to-noise ratio and the spatial resolution were investigated with the linear accelerator. The signal-to-noise ratio is clearly lower compared with that of the diamond detector, whereas the resolution is nearly the same. Conclusions: The Si-detector is qualified for dosimetry of very small fields because of the insignificant dose and dose rate dependence and in spite of some disadvantages regarding dosimetric properties compared with the diamond detector. The advantage is the availability and the cost. Measurement with ionisation chambers are not useful for collimator diameters below 20 mm. (orig.) [de

  15. SU-F-T-322: A Comparison of Two Si Detectors for in Vivo Dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Talarico, O [National Research Nuclear University “Mephi“, Moscow (Russian Federation); Krylova, T; Lebedenko, I [Russian Research Cancer Center, Moscow (Russian Federation)

    2016-06-15

    Purpose: To compare two types of semiconductor detectors for in vivo dosimetry by their dependence from various parameters in different conditions. Methods: QED yellow (Sun Nuclear) and EDP (Scanditronix) Si detectors were radiated by a Varian Clinac 2300 ix with 6 and 18 MV energies. 10 cm thickness water equivalent phantom consisted of 30×30 cm{sup 2} squared plates was used for experiments. Dose dependencies for different beam angles (0 – 180°), field size (3–40 cm), dose (50 – 300 MU), and dose rates (50 – 300 MU/min) were obtained and calibrated with Standard Farmer chamber (PTW). Results: Reproducibility, linearity, dose rate, angular dependence, and field size dependence were obtained for QED and EDP. They show no dose-rate dependence in available clinical dose rate range (100–600 MU/min). Both diodes have linear dependence with increasing the dose. Therefore even in case of high radiation therapy (including total body irradiation) it is not necessary to apply an additional correction during in vivo dosimetry. The diodes have different behavior for angular and field size dependencies. QED diode showed that dose value is stable for beam angles from 0 to 60°, for 60–180° correction factor has to be applied for each beam angle during in vivo measurements. For EDP diode dose value is sensitive to beam angle in whole range of angles. Conclusion: The study shows that QED diode is more suitable for in vivo dosimetry due to dose value independence from incident beam angle in the range 0–60°. There is no need in correction factors for increasing of dose and dose rate for both diodes. The next step will be to carry out measurements in non-standard conditions of total body irradiation. After this modeling of these experiments with Monte Carlo simulation for comparison calculated and obtained data is planned.

  16. Interfacial mixing in double-barrier magnetic tunnel junctions with amorphous NiFeSiB layers

    International Nuclear Information System (INIS)

    Chun, B.S.; Ko, S.P.; Hwang, J.Y.; Rhee, J.R.; Kim, T.W.; Kim, Y.K.

    2007-01-01

    Double-barrier magnetic tunnel junctions (DMTJs) comprising Ta 45/Ru 9.5/IrMn 10/CoFe 7/AlO x /free layer (CoFe 4/NiFeSiB 2/CoFe 4, CoFe 10, or NiFeSiB 10)/AlO x /CoFe 7/IrMn 10/Ru 60 (nm) have been examined with an emphasis given on understanding the interfacial mixing effects. The DMTJ, consisted of NiFeSiB, shows low switching field and low bias voltage dependence because the amorphous NiFeSiB has lower M S (=800 emu/cm 3 ) and offers smoother interfaces than polycrystalline CoFe. An interesting feature observed in the CoFe/NiFeSiB/CoFe sandwich free layered DMTJ is the presence of a wavy MR transfer curve at high-resistance region. Because the polycrystalline CoFe usually grows into a columnar structure, diamagnetic CoSi, paramagnetic FeSi, and/or diamagnetic CoB might have been formed during the sputter-deposition process. By employing electron energy loss spectrometry (EELS) and Auger electron spectroscopy (AES), we were able to confirm that Si and B atoms were arranged evenly in the top and bottom portions of AlO x /CoFe interfaces. This means that the interfacial mixing resulted in a distorted magnetization reversal process

  17. NASA's Advanced Environmental Barrier Coatings Development for SiC/SiC Ceramic Matrix Composites: Understanding Calcium Magnesium Alumino-Silicate (CMAS) Degradations and Resistance

    Science.gov (United States)

    Zhu, Dongming

    2014-01-01

    Environmental barrier coatings (EBCs) and SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is essential to the viability and reliability of the envisioned CMC engine component applications, ensuring integrated EBC-CMC system durability and designs are achievable for successful applications of the game-changing component technologies and lifing methodologies.This paper will emphasize recent NASA environmental barrier coating developments for SiCSiC turbine airfoil components, utilizing advanced coating compositions, state-of-the-art processing methods, and combined mechanical and environment testing and durability evaluations. The coating-CMC degradations in the engine fatigue-creep and operating environments are particularly complex; one of the important coating development aspects is to better understand engine environmental interactions and coating life debits, and we have particularly addressed the effect of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the durability of the environmental barrier coating systems, and how the temperature capability, stability and cyclic life of the candidate rare earth oxide and silicate coating systems will be impacted in the presence of the CMAS at high temperatures and under simulated heat flux conditions. Advanced environmental barrier coating systems, including HfO2-Si with rare earth dopant based bond coat systems, will be discussed for the performance improvements to achieve better temperature capability and CMAS resistance for future engine operating conditions.

  18. Si(Li)-NaI(Tl) sandwich detector array for measurements of trace radionuclides in soil samples

    International Nuclear Information System (INIS)

    Strauss, M.G.; Sherman, I.S.; Roche, C.T.; Pehl, R.H.

    1986-01-01

    An ultra-sensitive X/γ-ray detector system for assaying trace radioactivity in actinide contaminated soil and ash samples has been developed. The new system consists of an array of 6 large Si(Li) X-ray detectors sensitive on both faces and mounted on edge in a paddle-shaped cryostat with a 14 cm diameter Be window on each side. The paddle, with a sample of the soil placed at each window, is sandwiched between 2 large NaI(Tl) scintillators which suppress the γ background. With X-rays being measured simultaneously from soil in 2 sample holders and background reduced by 50% using anticoincidence, the sensitivity of this detector is 4 times higher than that of conventionally mounted Si(Li) detectors. A soil sample containing 50 pCi/g 239 Pu was measured in 5 min with an uncertainty of 1 and NpLsub(β1) X-ray peaks are resolved thus permitting measurement of trace Pu in the presence of 241 Am. This is the most sensitive and selective detector known for nondestructive assay of radioactivity in soil and other samples. (orig.)

  19. Status of HgCdTe Barrier Infrared Detectors Grown by MOCVD in Military University of Technology

    Science.gov (United States)

    Kopytko, M.; Jóźwikowski, K.; Martyniuk, P.; Gawron, W.; Madejczyk, P.; Kowalewski, A.; Markowska, O.; Rogalski, A.; Rutkowski, J.

    2016-09-01

    In this paper we present the status of HgCdTe barrier detectors with an emphasis on technological progress in metalorganic chemical vapor deposition (MOCVD) growth achieved recently at the Institute of Applied Physics, Military University of Technology. It is shown that MOCVD technology is an excellent tool for HgCdTe barrier architecture growth with a wide range of composition, donor /acceptor doping, and without post-grown annealing. The device concept of a specific barrier bandgap architecture integrated with Auger-suppression is as a good solution for high-operating temperature infrared detectors. Analyzed devices show a high performance comparable with the state-of-the-art of HgCdTe photodiodes. Dark current densities are close to the values given by "Rule 07" and detectivities of non-immersed detectors are close to the value marked for HgCdTe photodiodes. Experimental data of long-wavelength infrared detector structures were confirmed by numerical simulations obtained by a commercially available software APSYS platform. A detailed analysis applied to explain dark current plots was made, taking into account Shockley-Read-Hall, Auger, and tunneling currents.

  20. Experimental characterization and Monte Carlo simulation of Si(Li) detector efficiency by radioactive sources and PIXE

    Energy Technology Data Exchange (ETDEWEB)

    Mesradi, M. [Institut Pluridisciplinaire Hubert-Curien, UMR 7178 CNRS/IN2P3 et Universite Louis Pasteur, 23 rue du Loess, BP 28, F-67037 Strasbourg Cedex 2 (France); Elanique, A. [Departement de Physique, FS/BP 8106, Universite Ibn Zohr, Agadir, Maroc (Morocco); Nourreddine, A. [Institut Pluridisciplinaire Hubert-Curien, UMR 7178 CNRS/IN2P3 et Universite Louis Pasteur, 23 rue du Loess, BP 28, F-67037 Strasbourg Cedex 2 (France)], E-mail: abdelmjid.nourreddine@ires.in2p3.fr; Pape, A.; Raiser, D.; Sellam, A. [Institut Pluridisciplinaire Hubert-Curien, UMR 7178 CNRS/IN2P3 et Universite Louis Pasteur, 23 rue du Loess, BP 28, F-67037 Strasbourg Cedex 2 (France)

    2008-06-15

    This work relates to the study and characterization of the response function of an X-ray spectrometry system. The intrinsic efficiency of a Si(Li) detector has been simulated with the Monte Carlo codes MCNP and GEANT4 in the photon energy range of 2.6-59.5 keV. After finding it necessary to take a radiograph of the detector inside its cryostat to learn the correct dimensions, agreement within 10% between the simulations and experimental measurements with several point-like sources and PIXE results was obtained.

  1. (001) 3C SiC/Ni contact interface: In situ XPS observation of annealing induced Ni{sub 2}Si formation and the resulting barrier height changes

    Energy Technology Data Exchange (ETDEWEB)

    Tengeler, Sven, E-mail: stengeler@surface.tu-darmstadt.de [Institute of Material Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany); Univ. Grenoble Alpes, CNRS, LMGP, F-38000 Grenoble (France); Kaiser, Bernhard [Institute of Material Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany); Chaussende, Didier [Univ. Grenoble Alpes, CNRS, LMGP, F-38000 Grenoble (France); Jaegermann, Wolfram [Institute of Material Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany)

    2017-04-01

    Highlights: • Schottky behavior (Φ{sub B} = 0.41 eV) and Fermi level pining were found pre annealing. • Ni{sub 2}Si formation was confirmed for 5 min at 850 °C. • 3C/Ni{sub 2}Si Fermi level alignment is responsible for ohmic contact behavior. • Wet chemical etching (Si–OH/C–H termination) does not impair Ni{sub 2}Si formation. - Abstract: The electronic states of the (001) 3C SiC/Ni interface prior and post annealing are investigated via an in situ XPS interface experiment, allowing direct observation of the induced band bending and the transformation from Schottky to ohmic behaviour for the first time. A single domain (001) 3C SiC sample was prepared via wet chemical etching. Nickel was deposited on the sample in multiple in situ deposition steps via RF sputtering, allowing observation of the 3C SiC/Ni interface formation. Over the course of the experiments, an upward band bending of 0.35 eV was observed, along with defect induced Fermi level pinning. This indicates a Schottky type contact behaviour with a barrier height of 0.41 eV. The subsequent annealing at 850 °C for 5 min resulted in the formation of a Ni{sub 2}Si layer and a reversal of the band bending to 0.06 eV downward. Thus explaining the ohmic contact behaviour frequently reported for annealed n-type 3C SiC/Ni contacts.

  2. (001) 3C SiC/Ni contact interface: In situ XPS observation of annealing induced Ni_2Si formation and the resulting barrier height changes

    International Nuclear Information System (INIS)

    Tengeler, Sven; Kaiser, Bernhard; Chaussende, Didier; Jaegermann, Wolfram

    2017-01-01

    Highlights: • Schottky behavior (Φ_B = 0.41 eV) and Fermi level pining were found pre annealing. • Ni_2Si formation was confirmed for 5 min at 850 °C. • 3C/Ni_2Si Fermi level alignment is responsible for ohmic contact behavior. • Wet chemical etching (Si–OH/C–H termination) does not impair Ni_2Si formation. - Abstract: The electronic states of the (001) 3C SiC/Ni interface prior and post annealing are investigated via an in situ XPS interface experiment, allowing direct observation of the induced band bending and the transformation from Schottky to ohmic behaviour for the first time. A single domain (001) 3C SiC sample was prepared via wet chemical etching. Nickel was deposited on the sample in multiple in situ deposition steps via RF sputtering, allowing observation of the 3C SiC/Ni interface formation. Over the course of the experiments, an upward band bending of 0.35 eV was observed, along with defect induced Fermi level pinning. This indicates a Schottky type contact behaviour with a barrier height of 0.41 eV. The subsequent annealing at 850 °C for 5 min resulted in the formation of a Ni_2Si layer and a reversal of the band bending to 0.06 eV downward. Thus explaining the ohmic contact behaviour frequently reported for annealed n-type 3C SiC/Ni contacts.

  3. New a-Si:H photo-detectors for long-term charge storage

    International Nuclear Information System (INIS)

    Lee, H.; Cho, G.; Drewery, J.S.; Hong, W.S.; Jing, T.; Kaplan, S.N.; Mireshghi, A.; Perez-Mendez, V.; Wildermuth, D.

    1993-04-01

    Using the high light absorption properties of amorphous silicon, we developed a new device configuration that can detect photons and store the induced charges for relatively long time. This device, coupled to a scintillator such as CsI(Tl) in an array form, could be used as a scintillation camera, or for long-term photo-detection such as radionuclide labeled chromatography. The detector has a simple sandwich structure consisting of a scintillator followed by a top metal layer, p-i-n layers of hydrogenated amorphous silicon (a-Si:H), a second metal layer, a thin insulating layer and a bottom metal layer. The electron-hole pairs generated in the i-layer by the interaction with the incident light will be separated by the imposed electric field and be stored in the central metal-insulator interface. Readout will be done by switching the external bias to ground after the storage time, which depends on the needs for the specific application. Prototype devices were fabricated and tested. The performances of the devices were analyzed in connection with the storage time and the background signal produced by the thermally generated charges

  4. SiGe HBT linear-in-dB high dynamic range RF envelope detectors and wideband high linearity amplifiers

    OpenAIRE

    Pan, Hsuan-yu

    2010-01-01

    This research work aims on exploiting SiGe HBT technologies in high dynamic range wideband RF linear-in- dB envelope detectors and linear amplifiers. First, an improved all-npn broadband highly linear SiGe HBT differential amplifier is presented based on a variation of Caprio's Quad. A broadband linear amplifier with 46dBm OIP₃ at 20MHz, 34dBm OIP₃ at 1GHz, 6dB noise figure and 10.3dBm P₁dB is demonstrated. Second, an improved exact dynamic model of a fast-settling linear-in-dB Automatic Gain...

  5. The distribution of the barrier height in Al–TiW–Pd2Si/n-Si Schottky diodes from I–V–T measurements

    International Nuclear Information System (INIS)

    Dökme, Ilbilge; Altındal, Şemsettin; Afandiyeva, Izzet M

    2008-01-01

    The forward and reverse bias current–voltage (I–V) characteristics of Al–TiW–Pd 2 Si/n-Si Schottky barrier diodes (SBDs) were measured in the temperature range of 300–400 K. The estimated zero-bias barrier height Φ B0 and the ideality factor n assuming thermionic emission (TE) theory show a strong temperature dependence. While n decreases, Φ B0 increases with increasing temperature. The Richardson plot is found to be linear in the temperature range measured, but the activation energy value of 0.378 eV and the Richardson constant (A*) value of 15.51 A cm −2 K −2 obtained in this plot are much lower than the known values. Such behavior is attributed to Schottky barrier inhomogeneities by assuming a Gaussian distribution of barrier heights (BHs) due to BH inhomogeneities that prevail at the interface. Also, the Φ B0 versus q/2kT plot was drawn to obtain evidence of a Gaussian distribution of the BHs, and Φ B0 = 0.535 eV and σ 0 = 0.069 V for the mean BH and zero-bias standard deviation, respectively, have been obtained from this plot. Thus, the modified ln(I 0 /T 2 ) − q 2 σ 2 0 /2k 2 T 2 versus q/kT plot gives Φ B0 and A* as 0.510 eV and 121.96 A cm −2 K −2 , respectively. This value of the Richardson constant 121.96 A cm −2 K −2 is very close to the theoretical value of 120 A K −2 cm −2 for n-type Si. Hence, it has been concluded that the temperature dependence of the forward I–V characteristics of the Al–TiW–Pd 2 Si/n-Si Schottky barrier diodes can be successfully explained on the basis of a thermionic emission mechanism with a Gaussian distribution of the BHs

  6. Electric field strength and plasma delay in silicon surface barrier detector

    International Nuclear Information System (INIS)

    Kanno, I.; Inbe, T.; Kanazawa, S.; Kimura, I.

    1994-01-01

    The resistivity change of a silicon irradiated by high energy neutrons became an interest of study associated with the large scale accelerator projects . The increase of the resistivity of the silicon of a silicon surface barrier detector (SSBD) was studied as a function of neutron fluence. The plasma delay, which was an interesting but not favorite timing property of the SSBD, was reported being dependent on the resistivity of silicon . The neutron irradiation brings the change of timing property as well as the resistivity change on the SSBD. The resistivity dependence of the plasma delay should be studied for the purpose of high energy accelerator experiments. Some empirical formulae of the plasma delay were reported, however, there were no discussions on the physical meanings of the resistivity dependence of the plasma delay. The plasma delay in a SSBD is discussed in the light of electric field strength in the depletion layer of the SSBD. The explanation of the plasma delay is presented taking into account of the competing two electric forces. The resistivity of the silicon affects the plasma delay through the electric forces. 3 figs, 3 refs. (author)

  7. Sputtered carbon as a corrosion barrier for x-ray detector windows

    Energy Technology Data Exchange (ETDEWEB)

    Rowley, Joseph; Pei, Lei; Davis, Robert C., E-mail: davis@byu.edu; Vanfleet, Richard R. [Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602 (United States); Liddiard, Steven; Harker, Mallorie; Abbott, Jonathan [Moxtek, Inc., 452 W 1260 N, Orem, Utah 84057 (United States)

    2016-09-15

    Sputtered amorphous carbon thin films were explored as corrosion resistant coatings on aluminum thin films to be incorporated into x-ray detector windows. The requirements for this application include high corrosion resistance, low intrinsic stress, high strains at failure, and high x-ray transmission. Low temperature sputtering was used because of its compatibility with the rest of the window fabrication process. Corrosion resistance was tested by exposure of carbon coated and uncoated Al thin films to humidity. Substrate curvature and bulge testing measurements were used to determine intrinsic stress and ultimate strain at failure. The composition and bonding of the carbon films were further characterized by electron energy loss spectroscopy, Raman spectroscopy, and carbon, hydrogen, and nitrogen elemental analyses. Samples had low compressive stress (down to.08 GPa), a high strain at failure (3%), and a low fraction of sp{sup 3} carbon–carbon bonds (less than 5%). The high breaking strain and excellent x-ray transmission of these sputtered carbon films indicate that they will work well as corrosion barriers in this application.

  8. 63Ni schottky barrier nuclear battery of 4H-SiC

    International Nuclear Information System (INIS)

    Xiao-Ying Li; Yong Ren; Xue-Jiao Chen; Da-Yong Qiao; Wei-Zheng Yuan

    2011-01-01

    The design, fabrication, and testing of a 4H-SiC Schottky betavoltaic nuclear battery based on MEMS fabrication technology are presented in this paper. It uses a Schottky diode with an active area of 3.14 mm 2 to collect the charge from a 4 mCi/cm 2 63 Ni source. Some of the critical steps in process integration for fabricating silicon carbide-based Schottky diode were addressed. A prototype of this battery was fabricated and tested under the illumination of the 63 Ni source with an activity of 0.12 mCi. An open circuit voltage (V OC ) of 0.27 V and a short circuit current density (J SC ) of 25.57 nA/cm 2 are measured. The maximum output power density (P max ) of 4.08 nW/cm 2 and power conversion efficiency (η) of 1.01% is obtained. The performance of this battery is expected to be significantly improved by using larger activity and optimizing the design and processing technology of the battery. By achieving comparable performance with previously constructed p-n or p-i-n junction energy conversion structures, the Schottky barrier diode proves to be a feasible approach to achieve practical betavoltaics. (author)

  9. (001) 3C SiC/Ni contact interface: In situ XPS observation of annealing induced Ni2Si formation and the resulting barrier height changes

    Science.gov (United States)

    Tengeler, Sven; Kaiser, Bernhard; Chaussende, Didier; Jaegermann, Wolfram

    2017-04-01

    The electronic states of the (001) 3C SiC/Ni interface prior and post annealing are investigated via an in situ XPS interface experiment, allowing direct observation of the induced band bending and the transformation from Schottky to ohmic behaviour for the first time. A single domain (001) 3C SiC sample was prepared via wet chemical etching. Nickel was deposited on the sample in multiple in situ deposition steps via RF sputtering, allowing observation of the 3C SiC/Ni interface formation. Over the course of the experiments, an upward band bending of 0.35 eV was observed, along with defect induced Fermi level pinning. This indicates a Schottky type contact behaviour with a barrier height of 0.41 eV. The subsequent annealing at 850 °C for 5 min resulted in the formation of a Ni2Si layer and a reversal of the band bending to 0.06 eV downward. Thus explaining the ohmic contact behaviour frequently reported for annealed n-type 3C SiC/Ni contacts.

  10. Na effect on flexible Cu(In,Ga)Se{sub 2} photovoltaic cell depending on diffusion barriers (SiOx, i-ZnO) on stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Woo-Jung; Cho, Dae-Hyung; Wi, Jae-Hyung; Han, Won Seok [Electronics and Telecommunications Research Institute, Daejeon 305-700 (Korea, Republic of); Kim, Jeha [Insitute of Photovoltaics, Cheongju University, Cheongju 360-764 (Korea, Republic of); Chung, Yong-Duck, E-mail: ydchung@etri.re.kr [Electronics and Telecommunications Research Institute, Daejeon 305-700 (Korea, Republic of); Department of Advanced Device Engineering, Korea University of Science and Technology, Daejeon 305-350 (Korea, Republic of)

    2014-10-15

    Cu(In,Ga)Se{sub 2} (CIGS) based-photovoltaic (PV) cells with different diffusion barriers of SiOx and i-ZnO were fabricated on stainless steel (STS) substrate and their electrical characteristics were investigated by measuring J–V curves under illuminated and dark conditions. The physical properties of the CIGS film depending on type of diffusion barrier were also analyzed using X-ray diffraction and secondary ion mass spectroscopy. The efficiency of the CIGS-PV cell with i-ZnO barrier was approximately 2% higher than that with the SiOx barrier. Through the analysis of dark J–V curves, we discovered that distinctive defects were formed in the band gap of CIGS based on which diffusion barrier contacted the STS. The diffraction pattern showed a slightly different tendency of the peak intensity ratio of (220/204)/(112) in the PV cell with the i-ZnO barrier, which was slightly higher than that in the PV cell with SiOx barrier. In elemental depth profile, a deficient Ga profile was observed near the surface of the CIGS film with the SiOx barrier, and an abundant Na profile within the CIGS film with the i-ZnO barrier was detected. This is attributed to a difference in thermal conduction through the diffusion barriers during CIGS film growth, originating from the larger thermal conductivity of ZnO compared with SiOx. - Highlights: • We fabricated CIGS-PV cells with diffusion barriers of SiOx and i-ZnO on STS. • The efficiency of CIGS-PV cell with i-ZnO was ∼2% higher than that with SiOx. • Distinctive defects were formed into CIGS absorber depending on diffusion barrier.

  11. Performance of a high-resolution depth-encoding PET detector module using linearly-graded SiPM arrays

    Science.gov (United States)

    Du, Junwei; Bai, Xiaowei; Gola, Alberto; Acerbi, Fabio; Ferri, Alessandro; Piemonte, Claudio; Yang, Yongfeng; Cherry, Simon R.

    2018-02-01

    The goal of this study was to exploit the excellent spatial resolution characteristics of a position-sensitive silicon photomultiplier (SiPM) and develop a high-resolution depth-of-interaction (DOI) encoding positron emission tomography (PET) detector module. The detector consists of a 30  ×  30 array of 0.445  ×  0.445  ×  20 mm3 polished LYSO crystals coupled to two 15.5  ×  15.5 mm2 linearly-graded SiPM (LG-SiPM) arrays at both ends. The flood histograms show that all the crystals in the LYSO array can be resolved. The energy resolution, the coincidence timing resolution and the DOI resolution were 21.8  ±  5.8%, 1.23  ±  0.10 ns and 3.8  ±  1.2 mm, respectively, at a temperature of -10 °C and a bias voltage of 35.0 V. The performance did not degrade significantly for event rates of up to 130 000 counts s-1. This detector represents an attractive option for small-bore PET scanner designs that simultaneously emphasize high spatial resolution and high detection efficiency, important, for example, in preclinical imaging of the rodent brain with neuroreceptor ligands.

  12. Electroless Ni-B plating on SiO2 with 3-aminopropyl-triethoxysilane as a barrier layer against Cu diffusion for through-Si via interconnections in a 3-dimensional multi-chip package

    International Nuclear Information System (INIS)

    Ikeda, Akihiro; Sakamoto, Atsushi; Hattori, Reiji; Kuroki, Yukinori

    2009-01-01

    Electroless Ni-B was plated on SiO 2 as a barrier layer against Cu diffusion for through-Si via (TSV) interconnections in a 3-dimensional multi-chip package. The electroless Ni-B was deposited on the entire area of the SiO 2 side wall of a deep via with vapor phase pre-deposition of 3-aminopropyl-triethoxysilane on the SiO 2 . The carrier lifetimes in the Si substrates plated with Ni-B/Cu did not decrease with an increase in annealing temperature up to 400 deg. C . The absence of degradation of carrier lifetimes indicates that Cu atoms did not diffuse into the Si through the Ni-B. The advantages of electroless Ni-B (good conformal deposition and forming an effective diffusion barrier against Cu) make it useful as a barrier layer for TSV interconnections in a 3-dimensional multi-chip package

  13. High performance detector head for PET and PET/MR with continuous crystals and SiPMs

    International Nuclear Information System (INIS)

    Llosá, G.; Barrillon, P.; Barrio, J.; Bisogni, M.G.; Cabello, J.; Del Guerra, A.; Etxebeste, A.; Gillam, J.E.; Lacasta, C.; Oliver, J.F.; Rafecas, M.; Solaz, C.; Stankova, V.; La Taille, C. de

    2013-01-01

    A high resolution PET detector head for small animal PET applications has been developed. The detector is composed of a 12mm×12mm continuous LYSO crystal coupled to a 64-channel monolithic SiPM matrix from FBK-irst. Crystal thicknesses of 5 mm and 10 mm have been tested, both yielding an intrinsic spatial resolution around 0.7 mm FWHM with a position determination algorithm that can also provide depth-of-interaction information. The detectors have been tested in a rotating system that makes it possible to acquire tomographic data and reconstruct images of 22 Na sources. An image reconstruction method specifically adapted for continuous crystals has been employed. The Full Width at Half Maximum measured from a point source reconstructed with ML–EM was 0.7 mm with the 5 mm crystal and 0.8 mm with the 10 mm crystal

  14. Design and construction of a system for determination of Radon-222 by a surface-barrier detector

    International Nuclear Information System (INIS)

    Bonifacio M, J.; Iturbe, J.L.

    1993-01-01

    In the present work the design and construction of a system for the determination of 222 Rn is described, which utilizes silicon surface-barrier detectors. The 222 Rn gas was obtained a source of 226 Ra electrodeposited on stainless-steel discs. The well separated energies with this system makes possible the measurement and identification of alpha particles of 222 Rn, and its daughters 210 Po, 218 Po and 214 Po. (Author) 3 figs, 19 refs

  15. RBS using {sup 28}Si beams

    Energy Technology Data Exchange (ETDEWEB)

    Ophel, T.R. [Australian National Univ., Canberra, ACT (Australia); Mitchell, I.V. [University of Western Ontario, London, ON (Canada). Dept. of Physics

    1996-12-31

    Measurements of RBS using {sup 28}Si beams have been made to evaluate the enhancement of sensitivity that should obtain from kinematic suppression of silicon substrate scattering. Two detection methods were tried. Aside from a surface barrier detector, a magnetic spectrometer, instrumented with a multi-electrode gas focal plane detector, was used to indicate the resolution attainable with low energy {sup 28}Si ions. The results confirm that kinematically suppressed RBS does provide greatly improved sensitivity. 5 refs., 2 figs.

  16. RBS using {sup 28}Si beams

    Energy Technology Data Exchange (ETDEWEB)

    Ophel, T R [Australian National Univ., Canberra, ACT (Australia); Mitchell, I V [University of Western Ontario, London, ON (Canada). Dept. of Physics

    1997-12-31

    Measurements of RBS using {sup 28}Si beams have been made to evaluate the enhancement of sensitivity that should obtain from kinematic suppression of silicon substrate scattering. Two detection methods were tried. Aside from a surface barrier detector, a magnetic spectrometer, instrumented with a multi-electrode gas focal plane detector, was used to indicate the resolution attainable with low energy {sup 28}Si ions. The results confirm that kinematically suppressed RBS does provide greatly improved sensitivity. 5 refs., 2 figs.

  17. Development of SiPM-based scintillator tile detectors for a multi-layer fast neutron tracker

    Directory of Open Access Journals (Sweden)

    Jakubek J.

    2012-10-01

    Full Text Available We are developing thin tile scintillator detectors with silicon photomultiplier (SiPM readout for use in a multi-layer fast-neutron tracker. The tracker is based on interleaved Timepix and plastic scintillator layers. The thin 15 × 15 × 2 mm plastic scintillators require suitable optical readout in order to detect and measure the energy lost by energetic protons that have been recoiled by fast neutrons. Our first prototype used dual SiPMs, coupled to opposite edges of the scintillator tile using light-guides. An alternative readout geometry was designed in an effort to increase the fraction of scintillation light detected by the SiPMs. The new prototype uses a larger SiPM array to cover the entire top face of the tile. This paper details the comparative performance of the two prototype designs. A deuterium-tritium (DT fast-neutron source was used to compare the relative light collection efficiency of the two designs. A collimated UV light source was scanned across the detector face to map the uniformity. The new prototype was found to have 9.5 times better light collection efficiency over the original design. Both prototypes exhibit spatial non-uniformity in their response. Methods of correcting this non-uniformity are discussed.

  18. Application of large area SiPMs for the readout of a plastic scintillator based timing detector

    Science.gov (United States)

    Betancourt, C.; Blondel, A.; Brundler, R.; Dätwyler, A.; Favre, Y.; Gascon, D.; Gomez, S.; Korzenev, A.; Mermod, P.; Noah, E.; Serra, N.; Sgalaberna, D.; Storaci, B.

    2017-11-01

    In this study an array of eight 6 mm × 6 mm area SiPMs was coupled to the end of a long plastic scintillator counter which was exposed to a 2.5 GeV/c muon beam at the CERN PS. Timing characteristics of bars with dimensions 150 cm × 6 cm × 1 cm and 120 cm × 11 cm × 2.5 cm have been studied. An 8-channel SiPM anode readout ASIC (MUSIC R1) based on a novel low input impedance current conveyor has been used to read out and amplify SiPMs independently and sum the signals at the end. Prospects for applications in large-scale particle physics detectors with timing resolution below 100 ps are provided in light of the results.

  19. arXiv Application of large area SiPMs for the readout of a plastic scintillator based timing detector

    CERN Document Server

    Betancourt, C.; Brundler, R.; Dätwyler, A.; Favre, Y.; Gascon, D.; Gomez, S.; Korzenev, Alexander; Mermod, P.; Noah, E.; Serra, N.; Sgalaberna, D.; Storaci, B.

    2017-11-27

    In this study an array of eight 6 mm × 6 mm area SiPMs was coupled to the end of a long plastic scintillator counter which was exposed to a 2.5 GeV/c muon beam at the CERN PS. Timing characteristics of bars with dimensions 150 cm × 6 cm × 1 cm and 120 cm × 11 cm × 2.5 cm have been studied. An 8-channel SiPM anode readout ASIC (MUSIC R1) based on a novel low input impedance current conveyor has been used to read out and amplify SiPMs independently and sum the signals at the end. Prospects for applications in large-scale particle physics detectors with timing resolution below 100 ps are provided in light of the results.

  20. Design and evaluation of a SiPM-based large-area detector module for positron emission imaging

    Science.gov (United States)

    Alva-Sánchez, H.; Murrieta-Rodríguez, T.; Calva-Coraza, E.; Martínez-Dávalos, A.; Rodríguez-Villafuerte, M.

    2018-03-01

    The design and evaluation of a large-area detector module for positron emission imaging applications, is presented. The module features a SensL ArrayC-60035-64P-PCB solid state detector (8×8 array of tileable silicon photomultipliers by SensL, 7.2 mm pitch) covering a total area of 57.4×57.4 mm2. The detector module was formed using a pixelated array of 40×40 lutetium-yttrium oxyorthosilicate (LYSO) scintillator crystal elements with 1.43 mm pitch. A 7 mm thick coupling light guide was used to allow light sharing between adjacent SiPM. A 16-channel symmetric charge division (SCD) readout board was designed to multiplex the number of signals from 64 to 16 (8 columns and 8 rows) and a center-of-gravity algorithm to identify the position. Data acquisition and digitization was accomplished using a custom-made system based on FPGAs boards. Crystal maps were obtained using 18F-positron sources and Voronoi diagrams were used to correct for geometric distortions and to generate a non-uniformity correction matrix. All measurements were taken at a controlled room temperature of 22oC. The crystal maps showed minor distortion, 90% of the 1600 total crystal elements could be identified, a mean peak-to-valley ratio of 4.3 was obtained and a 10.8% mean energy resolution for 511 keV annihilation photons was determined. The performance of the detector using our own readout board was compared to that using two different commercially readout boards using the same detector module arrangement. We show that these large-area SiPM arrays, combined with a 16-channel SCD readout board, can offer high spatial resolution, excellent energy resolution and detector uniformity and thus, can be used for positron emission imaging applications.

  1. First-principles study of the effects of Silicon doping on the Schottky barrier of TiSi2/Si interfaces

    Science.gov (United States)

    Wang, Han; Silva, Eduardo; West, Damien; Sun, Yiyang; Restrepo, Oscar; Zhang, Shengbai; Kota, Murali

    As scaling of semiconductor devices is pursued in order to improve power efficiency, quantum effects due to the reduced dimensions on devices have become dominant factors in power, performance, and area scaling. In particular, source/drain contact resistance has become a limiting factor in the overall device power efficiency and performance. As a consequence, techniques such as heavy doping of source and drain have been explored to reduce the contact resistance, thereby shrinking the width of depletion region and lowering the Schottky barrier height. In this work, we study the relation between doping in Silicon and the Schottky barrier of a TiSi2/Si interface with first-principles calculation. Virtual Crystal Approximation (VCA) is used to calculate the average potential of the interface with varying doping concentration, while the I-V curve for the corresponding interface is calculated with a generalized one-dimensional transfer matrix method. The relation between substitutional and interstitial Boron and Phosphorus dopant near the interface, and their effect on tuning the Schottky barrier is studied. These studies provide insight to the type of doping and the effect of dopant segregation to optimize metal-semiconductor interface resistance.

  2. Tuning of Schottky Barrier Height at NiSi/Si Contact by Combining Dual Implantation of Boron and Aluminum and Microwave Annealing

    Directory of Open Access Journals (Sweden)

    Feng Sun

    2018-03-01

    Full Text Available Dopant-segregated source/drain contacts in a p-channel Schottky-barrier metal-oxide semiconductor field-effect transistor (SB-MOSFET require further hole Schottky barrier height (SBH regulation toward sub-0.1 eV levels to improve their competitiveness with conventional field-effect transistors. Because of the solubility limits of dopants in silicon, the requirements for effective hole SBH reduction with dopant segregation cannot be satisfied using mono-implantation. In this study, we demonstrate a potential solution for further SBH tuning by implementing the dual implantation of boron (B and aluminum (Al in combination with microwave annealing (MWA. By using such a method, not only has the lowest hole SBH ever with 0.07 eV in NiSi/n-Si contacts been realized, but also the annealing duration of MWA was sharply reduced to 60 s. Moreover, we investigated the SBH tuning mechanisms of the dual-implanted diodes with microwave annealing, including the dopant segregation, activation effect, and dual-barrier tuning effect of Al. With the selection of appropriate implantation conditions, the dual implantation of B and Al combined with the MWA technique shows promise for the fabrication of future p-channel SB-MOSFETs with a lower thermal budget.

  3. Bias voltage dependence of magnetic tunnel junctions comprising amorphous ferromagnetic CoFeSiB layer with double barriers

    International Nuclear Information System (INIS)

    Yim, H.I.; Lee, S.Y.; Hwang, J.Y.; Rhee, J.R.; Chun, B.S.; Wang, K.L.; Kim, Y.K.; Kim, T.W.; Lee, S.S.; Hwang, D.G.

    2008-01-01

    Double-barrier magnetic tunnel junctions (DMTJs) with and without an amorphous ferromagnetic material such as CoFeSiB 10, CoFe 5/CoFeSiB 5, and CoFe 10 (nm) were prepared and compared to investigate the bias voltage dependence of the tunneling magnetoresistance (TMR) ratio. Typical DMTJ structures were Ta 45/Ru 9.5/IrMn 10/CoFe 7/AlO x /free layer 10/AlO x /CoFe 7/IrMn 10/Ru 60 (in nanometers). The interlayer coupling field and the normalized TMR ratios at the applied voltages of +0.4 and -0.4 V of the amorphous CoFeSiB free-layer DMTJ offer lower and higher values than that of the polycrystalline CoFe free-layer DMTJ, respectively. An amorphous ferromagnetic CoFeSiB layer improves the interface roughness of the free layer/tunnel barrier and, as a result, the interlayer coupling field and bias voltage dependence of the TMR ratio are suppressed at a given voltage. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Advanced Environmental Barrier Coating and SA Tyrannohex SiC Composites Integration for Improved Thermomechanical and Environmental Durability

    Science.gov (United States)

    Zhu, Dongming; Halbig, Michael; Singh, Mrityunjay

    2018-01-01

    The development of 2700 degF capable environmental barrier coating (EBC) systems, particularly, the Rare Earth "Hafnium" Silicon bond coat systems, have significantly improved the temperature capability and environmental stability of SiC/SiC Ceramic Matrix Composite Systems. We have specifically developed the advanced 2700 degF EBC systems, integrating the EBC to the high temperature SA Tyrannohex SiC fiber composites, for comprehensive performance and durability evaluations for potential turbine engine airfoil component applications. The fundamental mechanical properties, environmental stability and thermal gradient cyclic durability performance of the EBC - SA Tyrannohex composites were investigated. The paper will particularly emphasize the high pressure combustion rig recession, cyclic thermal stress resistance and thermomechanical low cycle fatigue testing of uncoated and environmental barrier coated Tyrannohex SiC SA composites in these simulated turbine engine combustion water vapor, thermal gradients, and mechanical loading conditions. We have also investigated high heat flux and flexural fatigue degradation mechanisms, determined the upper limits of operating temperature conditions for the coated SA composite material systems in thermomechanical fatigue conditions. Recent progress has also been made by using the self-healing rare earth-silicon based EBCs, thus enhancing the SA composite hexagonal fiber columns bonding for improved thermomechanical and environmental durability in turbine engine operation environments. More advanced EBC- composite systems based on the new EBC-Fiber Interphases will also be discussed.

  5. Room temperature current-voltage (I-V) characteristics of Ag/InGaN/n-Si Schottky barrier diode

    Energy Technology Data Exchange (ETDEWEB)

    Erdoğan, Erman, E-mail: e.erdogan@alparslan.edu.tr [Department of Physics, Faculty of Art and Science, Muş Alparslan University, Muş 49250 (Turkey); Kundakçı, Mutlu [Department of Physics, Faculty of Science, Atatürk University, Erzurum 25240 (Turkey)

    2017-02-01

    Metal-semiconductors (MSs) or Schottky barrier diodes (SBDs) have a significant potential in the integrated device technology. In the present paper, electrical characterization of Ag/InGaN/n-Si Schottky diode have been systematically carried out by simple Thermionic method (TE) and Norde function based on the I-V characteristics. Ag ohmic and schottky contacts are deposited on InGaN/n-Si film by thermal evaporation technique under a vacuum pressure of 1×10{sup −5} mbar. Ideality factor, barrier height and series resistance values of this diode are determined from I-V curve. These parameters are calculated by TE and Norde methods and findings are given in a comparetive manner. The results show the consistency for both method and also good agreement with other results obtained in the literature. The value of ideality factor and barrier height have been determined to be 2.84 and 0.78 eV at room temperature using simple TE method. The value of barrier height obtained with Norde method is calculated as 0.79 eV.

  6. Room temperature current-voltage (I-V) characteristics of Ag/InGaN/n-Si Schottky barrier diode

    Science.gov (United States)

    Erdoğan, Erman; Kundakçı, Mutlu

    2017-02-01

    Metal-semiconductors (MSs) or Schottky barrier diodes (SBDs) have a significant potential in the integrated device technology. In the present paper, electrical characterization of Ag/InGaN/n-Si Schottky diode have been systematically carried out by simple Thermionic method (TE) and Norde function based on the I-V characteristics. Ag ohmic and schottky contacts are deposited on InGaN/n-Si film by thermal evaporation technique under a vacuum pressure of 1×10-5 mbar. Ideality factor, barrier height and series resistance values of this diode are determined from I-V curve. These parameters are calculated by TE and Norde methods and findings are given in a comparetive manner. The results show the consistency for both method and also good agreement with other results obtained in the literature. The value of ideality factor and barrier height have been determined to be 2.84 and 0.78 eV at room temperature using simple TE method. The value of barrier height obtained with Norde method is calculated as 0.79 eV.

  7. Performance of a position sensitive Si(Li) x-ray detector dedicated to Compton polarimetry of stored and trapped highly-charged ions

    International Nuclear Information System (INIS)

    Weber, G; Braeuning, H; Hess, S; Maertin, R; Spillmann, U; Stoehlker, Th

    2010-01-01

    We report on a novel two-dimensional position sensitive Si(Li) detector dedicated to Compton polarimetry of x-ray radiation arising from highly-charged ions. The performance of the detector system was evaluated in ion-atom collision experiments at the ESR storage ringe at GSI, Darmstadt. Based on the data obtained, the polarimeter efficiency is estimated in this work.

  8. A new fission-fragment detector to complement the CACTUS-SiRi setup at the Oslo Cyclotron Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Tornyi, T.G., E-mail: tornyitom@atomki.hu [Department of Physics, University of Oslo (Norway); Institute of Nuclear Research of the Hungarian Academy of Sciences (MTA Atomki), Debrecen (Hungary); Görgen, A.; Guttormsen, M.; Larsen, A.C.; Siem, S. [Department of Physics, University of Oslo (Norway); Krasznahorkay, A. [Institute of Nuclear Research of the Hungarian Academy of Sciences (MTA Atomki), Debrecen (Hungary); Csige, L. [Institute of Nuclear Research of the Hungarian Academy of Sciences (MTA Atomki), Debrecen (Hungary); Max-Planck-Institute for Quantum Optics, D-85748 Garching (Germany)

    2014-02-21

    An array of Parallel Plate Avalanche Counters (PPAC) for the detection of heavy ions has been developed. The new device, NIFF (Nuclear Instrument for Fission Fragments), consists of four individual detectors and covers 60% of 2π. It was designed to be used in conjunction with the SiRi array of ΔE−E silicon telescopes for light charged particles and fits into the CACTUS array of 28 large-volume NaI scintillation detectors at the Oslo Cyclotron Laboratory. The low-pressure gas-filled PPACs are sensitive for the detection of fission fragments, but are insensitive to scattered beam particles of light ions or light-ion ejectiles. The PPAC detectors of NIFF have good time resolution and can be used either to select or to veto fission events in in-beam experiments with light-ion beams and actinide targets. The powerful combination of SiRi, CACTUS, and NIFF provides new research opportunities for the study of nuclear structure and nuclear reactions in the actinide region. The new setup is particularly well suited to study the competition of fission and γ decay as a function of excitation energy.

  9. Design and spectrum calculation of 4H-SiC thermal neutron detectors using FLUKA and TCAD

    Science.gov (United States)

    Huang, Haili; Tang, Xiaoyan; Guo, Hui; Zhang, Yimen; Zhang, Yimeng; Zhang, Yuming

    2016-10-01

    SiC is a promising material for neutron detection in a harsh environment due to its wide band gap, high displacement threshold energy and high thermal conductivity. To increase the detection efficiency of SiC, a converter such as 6LiF or 10B is introduced. In this paper, pulse-height spectra of a PIN diode with a 6LiF conversion layer exposed to thermal neutrons (0.026 eV) are calculated using TCAD and Monte Carlo simulations. First, the conversion efficiency of a thermal neutron with respect to the thickness of 6LiF was calculated by using a FLUKA code, and a maximal efficiency of approximately 5% was achieved. Next, the energy distributions of both 3H and α induced by the 6LiF reaction according to different ranges of emission angle are analyzed. Subsequently, transient pulses generated by the bombardment of single 3H or α-particles are calculated. Finally, pulse height spectra are obtained with a detector efficiency of 4.53%. Comparisons of the simulated result with the experimental data are also presented, and the calculated spectrum shows an acceptable similarity to the experimental data. This work would be useful for radiation-sensing applications, especially for SiC detector design.

  10. Determination of equilibrium factor between radon and its progeny using surface barrier detector for various shapes of passive radon dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Jamil, K. [PINSTECH, Islamabad (Pakistan). Environ. Radiat. Group; Fazal-ur-Rehman [PINSTECH, Islamabad (Pakistan). Environ. Radiat. Group; Ali, S. [PINSTECH, Islamabad (Pakistan). Environ. Radiat. Group; Khan, H.A. [PINSTECH, Islamabad (Pakistan). Environ. Radiat. Group

    1997-03-21

    In the field of radon dosimetry, it is customary to measure radon ({sup 222}Rn) concentration while potential health hazard is due to the radon short-lived progeny. When radon is in secular equilibrium, the measured activity of radon equals the activity of radon`s progeny. However, in practical cases an inequilibrium between radon and its progeny exists which is measured in terms of the equilibrium factor. To determine the equilibrium factor between radon and its progeny in a closed environment various shapes of passive dosimeters based upon solid state nuclear track detectors (SSNTDs) are employed. In order to observe the dependence of equilibrium factor upon shapes or effective volumes, experiments have been performed replacing the SSNTDs with a surface barrier detector in Karlsruhe diffusion chamber, pen-type and box-type dosimeters. Using the collected alpha spectra, the equilibrium factor has been determined for a radon-air mixture in a custom designed radon chamber simulating a closed environment of a room. The results show that the radon equilibrium factor is about 0.20 for different shapes of dosimeters studied in this research. It is concluded that the determination of equilibrium factor between radon and its progeny does not depend upon effective volume or shape of the passive dosimeters using alpha spectroscopic data acquired by surface barrier detector. (orig.).

  11. Determination of equilibrium factor between radon and its progeny using surface barrier detector for various shapes of passive radon dosimeters

    International Nuclear Information System (INIS)

    Jamil, K.; Fazal-ur-Rehman; Ali, S.; Khan, H.A.

    1997-01-01

    In the field of radon dosimetry, it is customary to measure radon ( 222 Rn) concentration while potential health hazard is due to the radon short-lived progeny. When radon is in secular equilibrium, the measured activity of radon equals the activity of radon's progeny. However, in practical cases an inequilibrium between radon and its progeny exists which is measured in terms of the equilibrium factor. To determine the equilibrium factor between radon and its progeny in a closed environment various shapes of passive dosimeters based upon solid state nuclear track detectors (SSNTDs) are employed. In order to observe the dependence of equilibrium factor upon shapes or effective volumes, experiments have been performed replacing the SSNTDs with a surface barrier detector in Karlsruhe diffusion chamber, pen-type and box-type dosimeters. Using the collected alpha spectra, the equilibrium factor has been determined for a radon-air mixture in a custom designed radon chamber simulating a closed environment of a room. The results show that the radon equilibrium factor is about 0.20 for different shapes of dosimeters studied in this research. It is concluded that the determination of equilibrium factor between radon and its progeny does not depend upon effective volume or shape of the passive dosimeters using alpha spectroscopic data acquired by surface barrier detector. (orig.)

  12. Application of a radiation detector in the interdisciplinary study. 1. Portable fluorescent X-ray analysis using the Si-PIN photodiode

    International Nuclear Information System (INIS)

    Ito, Yutaka

    2000-01-01

    As a semiconductor used for X-ray detector has excellent resolution, it must be cooled by liquid nitrogen at its use, which is a limitation on its actual use and applications. Then, a compound detector with wider bandwidth such as CdTe and HgI 2 has conventionally been used to attempt to use the detector at room temperature. Here was adopted an Si-PIN photodiode for a representative small type semiconductor detector unnecessary for liquid nitrogen, to introduce small and portable fluorescent X-ray analyzer for its application. As Si-PIN can work at room temperature, it has large leak current and insufficiently spread empty phase, so it is used by cooling due to Peltier element and so on. Then, here was used an X-ray detector, XR-100CR of AMPTEK Inc. composed of Si-PIN photodiode and a Pre-AMP. And, for a portable fluorescent X-ray analyzer, the Si-PIN photodiode detector of AMPTEK Inc., and a closely sealed small radiation source of 50 μ Ci 241 Am for excitation of X-ray in specimen were used. Its working principle consists of excitation of elements in a specimen with X- and gamma-ray from 241 Am, and detection of emitted fluorescent X-ray with Si-PIN photodiode. (G.K.)

  13. Determination of Schottky barrier heights and Fermi-level unpinning at the graphene/n-type Si interfaces by X-ray photoelectron spectroscopy and Kelvin probe

    International Nuclear Information System (INIS)

    Lin, Yow-Jon; Zeng, Jian-Jhou

    2014-01-01

    Highlights: • The interface characteristics of graphene/n-type Si devices are measured. • The actual work function of graphene is examined with the Kelvin probe. • An analysis is conducted according to the Schottky–Mott limit. • The Fermi energy level at the graphene/n-type Si interfaces is unpinned. • The Schottky barrier value is dependent on the work function of graphene. - Abstract: The interface characteristics of graphene/n-type Si samples using X-ray photoelectron spectroscopy (XPS) measurements are investigated. XPS makes it possible to extract a reliable Schottky barrier value. For graphene/n-type Si samples with (without) sulfide treatment, the Schottky barrier height is 0.86 (0.78) eV. The Schottky barrier height was increased from 0.78 to 0.86 eV, indicating that sulfide treatment is effective in passivating the surface of Si (owing to the formation of Si–S bonds). To determine the Fermi-level pinning/unpinning at the graphene/n-type Si interfaces with sulfide treatment, an analysis is conducted according to the Schottky–Mott limit and the actual work function of graphene is examined with the Kelvin probe. It is shown that the Fermi energy level is unpinned and the Schottky barrier value is dependent on the work function of graphene. Investigation of graphene/n-type Si interfaces is important, and providing the other technique for surface potential control is possible

  14. Diffusion barrier performances of thin Mo, Mo-N and Mo/Mo-N films between Cu and Si

    International Nuclear Information System (INIS)

    Song Shuangxi; Liu Yuzhang; Mao Dali; Ling Huiqin; Li Ming

    2005-01-01

    In this work, we have studied the diffusion barrier performances of Mo, Mo-N and Mo/Mo-N metallization layers deposited by sputtering Mo in Ar/N 2 atmospheres, respectively. Samples were subsequently annealed at different temperatures ranging from 400 to 800 deg C in vacuum condition. The film properties and their suitability as diffusion barriers and protective coatings in silicon devices were characterized using four-point probe measurement, X-ray diffractometry, scanning electron microscopy, Auger electron spectroscopy and transmission electron microscopy analyses. Experimental results revealed that the Mo (20 nm)/Mo-N (30 nm) layer was able to prevent the diffusion reaction between Cu and Si substrate after being annealed at 600 deg C for 30 min. The adhesion between layers and the content of N atoms are the key parameters to improve the properties of Mo-based barrier materials. The Mo layer interposed between Cu and Mo-N diluted the high nitrogen concentration of the barrier and so enhanced the barrier performances

  15. Barrier inhomogeneities and electronic transport of Pt contacts to relatively highly doped n-type 4H-SiC

    International Nuclear Information System (INIS)

    Huang, Lingqin; Wang, Dejun

    2015-01-01

    The barrier characteristics of Pt contacts to relatively highly doped (∼1 × 10 18  cm −3 ) 4H-SiC were investigated using current-voltage (I-V) and capacitance-voltage (C-V) measurements in the temperature range of 160–573 K. The barrier height and ideally factor estimated from the I-V characteristics based on the thermionic emission model are abnormally temperature-dependent, which can be explained by assuming the presence of a double Gaussian distribution (GD) of inhomogeneous barrier heights. However, in the low temperature region (160–323 K), the obtained mean barrier height according to GD is lower than the actual mean value from C-V measurement. The values of barrier height determined from the thermionic field emission model are well consistent with those from the C-V measurements, which suggest that the current transport process could be modified by electron tunneling at low temperatures

  16. A high-granularity scintillator hadronic-calorimeter with SiPM readout for a linear collider detector

    International Nuclear Information System (INIS)

    Andreev, V.; Balagura, V; Bobchenko, B.

    2004-01-01

    We report upon the design, construction and operation of a prototype for a high-granularity tile hadronic calorimeter for a future international linear collider(ILC) detector. Scintillating tiles are read out via wavelength-shifting fibers which guides the scintillation light to a novel photodetector, the Silicon Photomultiplier. The prototype has been tested at DESY using a positron test beam. The results are compared with a reference prototype equipped with multichannel vacuum photomultipliers. Detector calibration, noise, linearity and stability are discussed, and the energy response in a 1-6 GeV positron beam is compared with simulation. The work presented serves to establish the application of SiPM for calorimetry, and leads to the choice of this device for the construction of a 1m 3 calorimeter prototype for tests in hadron beams. (orig.)

  17. Simulation of a detector prototype with direct SiPM read-out and comparison with measurements

    CERN Document Server

    Kunsken, Andreas

    2010-01-01

    The features of a novel muon detection system are studied in this thesis with the help of GEANT4 simulations. The detector consists of a 10 cm×10 cm scintillator on whose top 3 mm×3 mm silicon photomultipliers are mounted. The scintillator may optionally be wrapped in a reflector. In the simulations various properties of the scintillator and the wrapping are varied like the scintillator thickness or the kind of wrapping and its reflectivity. Subsequently, the number of photons arriving at the SiPM is analyzed to determine the influence of the varied properties. Finally, the results of the simulations are compared to results that come from measurements with the detector setup.

  18. Superconducting single X-ray photon detector based on W0.8Si0.2

    Directory of Open Access Journals (Sweden)

    Xiaofu Zhang

    2016-11-01

    Full Text Available We fabricated a superconducting single X-ray photon detector based on W0.8Si0.2, and we characterized its basic detection performance for keV-photons at different temperatures. The detector has a critical temperature of 4.97 K, and it is able to be operated up to 4.8 K, just below the critical temperature. The detector starts to react to X-ray photons at relatively low bias currents, less than 1% of Ic at T = 1.8 K, and it shows a saturated count rate dependence on bias current at all temperatures, indicating that the optimum internal quantum efficiency can always be reached. Dark counts are negligible up to the highest investigated bias currents (99% of Ic and operating temperature (4.8 K. The latching effect affects the detector performance at all temperatures due to the fast recovery of the bias current; however, further modifications of the device geometry are expected to reduce the tendency for latching.

  19. Reliable determination of the Cu/n-Si Schottky barrier height by using in-device hot-electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Parui, Subir, E-mail: s.parui@nanogune.eu, E-mail: l.hueso@nanogune.eu; Atxabal, Ainhoa; Ribeiro, Mário; Bedoya-Pinto, Amilcar; Sun, Xiangnan; Llopis, Roger [CIC nanoGUNE, 20018 Donostia-San Sebastian, Basque Country (Spain); Casanova, Fèlix; Hueso, Luis E., E-mail: s.parui@nanogune.eu, E-mail: l.hueso@nanogune.eu [CIC nanoGUNE, 20018 Donostia-San Sebastian, Basque Country (Spain); IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Basque Country (Spain)

    2015-11-02

    We show the operation of a Cu/Al{sub 2}O{sub 3}/Cu/n-Si hot-electron transistor for the straightforward determination of a metal/semiconductor energy barrier height even at temperatures below carrier-freeze out in the semiconductor. The hot-electron spectroscopy measurements return a fairly temperature independent value for the Cu/n-Si barrier of 0.66 ± 0.04 eV at temperatures below 180 K, in substantial accordance with mainstream methods based on complex fittings of either current-voltage (I-V) and capacitance-voltage (C-V) measurements. The Cu/n-Si hot-electron transistors exhibit an OFF current of ∼2 × 10{sup −13} A, an ON/OFF ratio of ∼10{sup 5}, and an equivalent subthreshold swing of ∼96 mV/dec at low temperatures, which are suitable values for potential high frequency devices.

  20. Reliable determination of the Cu/n-Si Schottky barrier height by using in-device hot-electron spectroscopy

    International Nuclear Information System (INIS)

    Parui, Subir; Atxabal, Ainhoa; Ribeiro, Mário; Bedoya-Pinto, Amilcar; Sun, Xiangnan; Llopis, Roger; Casanova, Fèlix; Hueso, Luis E.

    2015-01-01

    We show the operation of a Cu/Al 2 O 3 /Cu/n-Si hot-electron transistor for the straightforward determination of a metal/semiconductor energy barrier height even at temperatures below carrier-freeze out in the semiconductor. The hot-electron spectroscopy measurements return a fairly temperature independent value for the Cu/n-Si barrier of 0.66 ± 0.04 eV at temperatures below 180 K, in substantial accordance with mainstream methods based on complex fittings of either current-voltage (I-V) and capacitance-voltage (C-V) measurements. The Cu/n-Si hot-electron transistors exhibit an OFF current of ∼2 × 10 −13  A, an ON/OFF ratio of ∼10 5 , and an equivalent subthreshold swing of ∼96 mV/dec at low temperatures, which are suitable values for potential high frequency devices

  1. Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture

    Directory of Open Access Journals (Sweden)

    T. Karthikeya Sharma

    2015-11-01

    Full Text Available Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE. This paper investigates the effects of using argon (Ar gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine’s performance within the range studied.

  2. Use of M and L transitions of heavy elements for the determination of a Si(Li) detector's efficiency

    International Nuclear Information System (INIS)

    Morales, J.R.; Romo, C.; Dinator, M.I.; Llona, F.; Tabacniks, M.

    1987-01-01

    The verification of the Si(Li) cryogenic detector's efficiency may be fastly carried out using the M radiations of the heavy elements, such as Pb and Au. Thin targets have been bombarded with protons of 2.0 and 6.6 MeV, thus resulting the transitions M and L. The number of emitted photons are possible to be inferred using tabulated cross sections from different authors. The comparison with the number of photons registered allows to determine the efficiency. (S.M.) [es

  3. Optimization of a large-area detector-block based on SiPM and pixelated LYSO crystal arrays.

    Science.gov (United States)

    Calva-Coraza, E; Alva-Sánchez, H; Murrieta-Rodríguez, T; Martínez-Dávalos, A; Rodríguez-Villafuerte, M

    2017-10-01

    We present the performance evaluation of a large-area detector module based on the ArrayC-60035-64P, an 8×8 array of tileable, 7.2mm pitch, silicon photomultipliers (SiPM) by SensL, covering a total area of 57.4mm×57.4mm. We characterized the ArrayC-60035-64P, operating at room temperature, using LYSO pixelated crystal arrays of different pitch sizes (1.075, 1.430, 1.683, 2.080 and 2.280mm) to determine the resolvable crystal size. After an optimization process, a 7mm thick coupling light guide was used for all crystal pitches. To identify the interaction position a 16-channel (8 columns, 8 rows) symmetric charge division (SCD) readout board together with a center-of-gravity algorithm was used. Based on this, we assembled the detector modules using a 40×40 LYSO, 1.43mm pitch array, covering the total detector area. Calibration was performed using a 137 Cs source resulting in excellent crystal maps with minor geometric distortion, a mean 4.1 peak-to-valley ratio and 9.6% mean energy resolution for 662keV photons in the central region. The resolvability index was calculated in the x and y directions with values under 0.42 in all cases. We show that these large area SiPM arrays, combined with a 16-channel SCD readout board, can offer high spatial resolution, without processing a big number of signals, attaining excellent energy resolution and detector uniformity. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  4. A Systematic Study to Optimize SiPM Photo-Detectors for Highest Time Resolution in PET

    CERN Document Server

    Gundacker, S.; Frisch, B.; Hillemanns, H.; Jarron, P.; Meyer, T.; Pauwels, K.; Lecoq, P.

    2012-01-01

    We report on a systematic study of time resolution made with three different commercial silicon photomultipliers (SiPMs) (Hamamatsu MPPC S10931-025P, S10931-050P, and S10931-100P) and two LSO scintillating crystals. This study aimed to determine the optimum detector conditions for highest time resolution in a prospective time-of-flight positron emission tomography (TOF-PET) system. Measurements were based on the time over threshold method in a coincidence setup using the ultrafast amplifier-discriminator NINO and a fast oscilloscope. Our tests with the three SiPMs of the same area but of different SPAD sizes and fill factors led to best results with the Hamamatsu type of 50×50×μm2 single-pixel size. For this type of SiPM and under realistic geometrical PET scanner conditions, i.e., with 2×2×10×mm3 LSO crystals, a coincidence time resolution of 220 ±4 ps FWHM could be achieved. The results are interpreted in terms of SiPM photon detection efficiency (PDE), dark noise, and photon yield.

  5. Charge collection in Si detectors irradiated in situ at superfluid helium temperature

    Science.gov (United States)

    Verbitskaya, Elena; Eremin, Vladimir; Zabrodskii, Andrei; Dehning, Bernd; Kurfürst, Christoph; Sapinski, Mariusz; Bartosik, Marcin R.; Egorov, Nicolai; Härkönen, Jaakko

    2015-10-01

    Silicon and diamond detectors operated in a superfluid helium bath are currently being considered for the upgrade of the LHC beam loss monitoring system. The detectors would be installed in immediate proximity of the superconducting coils of the triplet magnets. We present here the results of the in situ irradiation test for silicon detectors using 23 GeV protons while keeping the detectors at a temperature of 1.9 K. Red laser (630 nm) Transient Current Technique and DC current measurements were used to study the pulse response and collected charge for silicon detectors irradiated to a maximum radiation fluence of 1×1016 p/cm2. The dependence between collected charge and irradiation fluence was parameterized using the Hecht equation and assumption of a uniform electric field distribution. The collected charge was found to degrade with particle fluence for both bias polarities. We observed that the main factor responsible for this degradation was related to trapping of holes on the donor-type radiation-induced defects. In contrast to expectations, along with formation of donors, acceptor-type defects (electron traps) are introduced into the silicon bulk. This suggests that the current models describing charge collection in irradiated silicon detectors require an extension for taking into account trapping at low temperatures with a contribution of shallow levels. New in situ irradiation tests are needed and planned now to extend statistics of the results and gain a deeper insight into the physics of low temperature detector operation in harsh radiation environment.

  6. Planned studies of charge collection in non-uniformly irradiated Si and GaAs detectors

    International Nuclear Information System (INIS)

    Rosenfeld, A.; Reinhard, M.; Carolan, M.; Kaplan, G.; Lerch, M.; Alexiev, D.

    1995-01-01

    The aim of this project is to study the time and amplitude characteristics of silicon ion-implanted detectors non-uniformly irradiated with fast neutrons in order to predict their radiation behaviour in the LHC and space. It is expected in such detectors increases of the charge deficit due to trapping by large scale traps and transient time increases due to the reduction of the mobility. The theoretical model will be modified to describe the charge kinetics in the electrical field of the detector created by a non uniform space charge distribution. Experimental confirmation techniques are needed to develop non uniform predictable damage of silicon detectors using fast neutron sources (accelerators, reactors) and to study peculiarities of the charge transport in different parts of the detector. In parallel to experimental research will be started the theoretical development of the charge transport model for non-uniform distribution of space charge in the depletion layer (Neff). The model will include the linear distribution of Neff(y) along the detector as well as the change of sign of Neff (conversion from n to p type of silicon) inside the detector

  7. Diffusion barriers for Cu metallisation in Si integrated circuits : deposition and related thin film properties

    NARCIS (Netherlands)

    van Nieuwkasteele-Bystrova, Svetlana Nikolajevna

    2004-01-01

    In modern integrated circuits with Cu interconnects a diffusion barrier is used between the dielectric and Cu in order to prevent diffusion of Cu through the dielectrics. The choice of such a barrier requires a material exploration and a study of the material reactivity with both Cu and the

  8. Fabrication, characterization and simulation of 4H-SiC Schottky diode alpha particle detectors for pyroprocessing actinide monitoring

    Science.gov (United States)

    Garcia, Timothy Richard

    Pyroprocessing is a method of using high-temperature molten salts and electric fields to separate and collect fuel isotopes of used nuclear fuel. It has been has been tested in the U.S. at Idaho National Laboratory as a key step in closing the nuclear fuel cycle. One technical problem with the pyroprocessing method is a lack of knowledge regarding the actinide concentrations in the salt bath during operation, since on-line techniques for measuring these concentrations are not presently available. 4H-SiC Schottky diode detectors can potentially fulfill this need. Such detectors would operate in contact with the molten salt, and measure concentrations via alpha-particle spectroscopy. This work seeks to fabricate and characterize 4H-SiC Schottky diode detectors at high temperature, model the alpha particle spectrum expected in a molten salt, and model the operation of the detectors to confirm the physics of operation is as expected. In this work, 4H-SiC Schottky diode detectors were fabricated at OSU Nanotech West. After fabrication, these detectors were characterized using both I-V curves and Am-241 alpha-particle energy spectra. All measurements were made as a function of temperature, from room temperature up to 500°C. The average energy required to create an electron-hole pair was observed to decrease with an increase of temperature, due to a decrease of both the 4H-SiC bandgap and non-linear energy loss terms. Furthermore, the FWHM of the spectra was observed to be dependent on the leakage current at a certain temperature, and not dependent on the temperature itself. Secondly, the alpha particle energy spectrum in the pyroprocessing environment was modeled using SRIM. The molten salt was modeled in 3 different geometries, with or without a protective cover material on top of the detector. Due to the loss of alpha-particle energy in the molten salt itself, a high-energy alpha emitter may completely cover the spectrum from a lower-energy alpha emitter. Each of the

  9. SiC fiber and yttria-stabilized zirconia composite thick thermal barrier coatings fabricated by plasma spray

    Science.gov (United States)

    Ma, Rongbin; Cheng, Xudong; Ye, Weiping

    2015-12-01

    Approximately 4 mm-thick SiC fiber/yttria-stabilized zirconia (YSZ) composite thermal barrier coatings (TBCs) were prepared by atmospheric plasma spray (APS). The composite coatings have a 'reinforced concrete frame structure', which can protect the coating from failure caused by increasing thickness of coating. The SiC fiber plays an important role in reducing the residual stress level of the composite coatings. The thermal conductivity (TC) value of the composite coatings is 0.632 W/m K, which is about 50% reduction compared to that of typical APS YSZ TBCs. And the composite coatings have higher fracture toughness and better thermal shock resistance than the YSZ TBCs.

  10. Small suppression of the complete fusion of {sup 6}Li + {sup 28}Si reaction at near barrier energies

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Mandira [Bose Institute, Department of Physics, Kolkata (India); Lubian, J. [Universidade Federal Fluminense, Instituto de Fisica, Niteroi, Rio de Janeiro (Brazil)

    2017-11-15

    The incomplete fusion cross section of the {sup 6}Li + {sup 28}Si weakly bound system at above barrier energies was deduced from the measured γ-ray cross sections. The complete fusion cross section was estimated from the measured total fusion and incomplete fusion cross section and is found to be 85-100% of the total fusion cross section. The coupled channel calculation has been performed considering ground and first excited states of {sup 28}Si target. The fusion cross section estimated from coupled channel calculation shows good agreement with measured total fusion cross section at higher energies. The suppression of about 15% of the fusion cross section predicted by coupled channel calculation shows good agreement with the complete fusion cross section. The effect of the channel couplings on the elastic scattering angular distribution is also investigated. (orig.)

  11. Yb2Si2O7 Environmental Barrier Coatings Deposited by Various Thermal Spray Techniques: A Preliminary Comparative Study

    Science.gov (United States)

    Bakan, Emine; Marcano, Diana; Zhou, Dapeng; Sohn, Yoo Jung; Mauer, Georg; Vaßen, Robert

    2017-08-01

    Dense, crack-free, uniform, and well-adhered environmental barrier coatings (EBCs) are required to enhance the environmental durability of silicon (Si)-based ceramic matrix composites in high pressure, high gas velocity combustion atmospheres. This paper represents an assessment of different thermal spray techniques for the deposition of Yb2Si2O7 EBCs. The Yb2Si2O7 coatings were deposited by means of atmospheric plasma spraying (APS), high-velocity oxygen fuel spraying (HVOF), suspension plasma spraying (SPS), and very low-pressure plasma spraying (VLPPS) techniques. The initial feedstock, as well as the deposited coatings, were characterized and compared in terms of their phase composition. The as-sprayed amorphous content, microstructure, and porosity of the coatings were further analyzed. Based on this preliminary investigation, the HVOF process stood out from the other techniques as it enabled the production of vertical crack-free coatings with higher crystallinity in comparison with the APS and SPS techniques in atmospheric conditions. Nevertheless, VLPPS was found to be the preferred process for the deposition of Yb2Si2O7 coatings with desired characteristics in a controlled-atmosphere chamber.

  12. Direct conversion Si and CdZnTe detectors for digital mammography

    CERN Document Server

    Yin Shi Shi; Maeding, D; Mainprize, J; Mawdsley, G; Yaffe, M J; Gordon, E E; Hamilton, W J

    2000-01-01

    Hybrid pixel detector arrays that convert X-rays directly into charge signals are under development at NOVA for application to digital mammography. This technology also has wide application possibilities in other fields of radiology or in industrial imaging, nondestructive evaluation (NDE) and nondestructive inspection (NDI). These detectors have potentially superior properties compared to either emulsion-based film-screen systems which has nonlinear response to X-rays, or phosphor-based detectors in which there is an intermediate step of X-ray to light photon conversion (Feig and Yaffe, Radiol. Clinics North America 33 (1995) 1205-1230). Potential advantages of direct conversion detectors are high quantum efficiencies (QE) of 98% or higher (for 0.3 mm thick CdZnTe detector with 20 keV X-rays), improved contrast, high sensitivity and low intrinsic noise. These factors are expected to contribute to high detective quantum efficiency (DQE). The prototype hybrid pixel detector developed has 50x50 mu m pixel size,...

  13. Pilot tests of a PET detector using the TOF-PET ASIC based on monolithic crystals and SiPMs

    International Nuclear Information System (INIS)

    Aguilar, A.; González-Montoro, A.; González, A.J.; Hernández, L.; Monzó, J.M.; Benlloch, J.M.; Bugalho, R.; Ferramacho, L.

    2016-01-01

    In this work we show pilot tests of PET detector blocks using the TOF-PET ASIC, coupled to SiPM detector arrays and different crystal configurations. We have characterized the main ASIC features running calibration processes to compensate the time dispersion among the different ASIC/SiPM paths as well as for the time walk on the arrival of optical photons. The aim of this work is to use of LYSO monolithic crystals and explore their photon Depth of Interaction (DOI) capabilities, keeping good energy and spatial resolutions. First tests have been carried out with crystal arrays. Here we made it possible to reach a coincidence resolving times (CRT) of 370 ps FWHM, with energy resolutions better than 20% and resolving well 2 mm sized crystal elements. When using monolithic crystals, a single-pixel LYSO reference crystal helped to explore the CRT performance. We studied different strategies to provide the best timestamp determination in the monolithic scintillator. Times around 1 ns FWHM have been achieved in these pilot studies. In terms of spatial and energy resolution, values of about 3 mm and better than 30% were found, respectively. We have also demonstrated the capability of this system (monolithic and ASIC) to return accurate DOI information.

  14. The front-end electronics for the 1.8-kchannel SiPM tracking plane in the NEW detector

    International Nuclear Information System (INIS)

    Rodríguez, J.; Lorca, D.; Monrabal, F.; Toledo, J.; Esteve, R.

    2015-01-01

    NEW is the first phase of NEXT-100 experiment, an experiment aimed at searching for neutrinoless double-beta decay. NEXT technology combines an excellent energy resolution with tracking capabilities thanks to a combination of optical sensors, PMTs for the energy measurement and SiPMs for topology reconstruction. Those two tools result in one of the highest background rejection potentials in the field. This work describes the tracking plane that will be constructed for the NEW detector which consists of close to 1800 sensors with a 1-cm pitch arranged in twenty-eight 64-SiPM boards. Then it focuses in the development of the electronics needed to read the 1800 channels with a front-end board that includes per-channel differential transimpedance input amplifier, gated integrator, automatic offset voltage compensation and 12-bit ADC. Finally, a description of how the FPGA buffers data, carries out zero suppression and sends data to the DAQ interface using CERN RD-51 SRS's DTCC link specification complements the description of the electronics of the NEW detector tracking plane

  15. Effect of SiO{sub 2} coating in bolometric Ge light detectors for rare event searches

    Energy Technology Data Exchange (ETDEWEB)

    Beeman, J.W. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Gentils, A. [Centre de Spectrométrie Nuclaire et de Spectrométrie de Masse, CNRS and Université Paris-Sud, F-91405 Orsay (France); Giuliani, A., E-mail: andrea.giuliani@csnsm.in2p3.fr [Centre de Spectrométrie Nuclaire et de Spectrométrie de Masse, CNRS and Université Paris-Sud, F-91405 Orsay (France); Università dell' Insubria, Dipartimento di Scienza e Alta Tecnologia, 22100 Como, Italy, (Italy); INFN, Sezione di Milano Bicocca, 20126 Milano (Italy); Mancuso, M. [Università dell' Insubria, Dipartimento di Scienza e Alta Tecnologia, 22100 Como, Italy, (Italy); INFN, Sezione di Milano Bicocca, 20126 Milano (Italy); Pessina, G. [Università di Milano-Bicocca, Dipartimento di Fisica, and INFN, Sezione di Milano Bicocca, 20126 Milano (Italy); Plantevin, O. [Centre de Spectrométrie Nuclaire et de Spectrométrie de Masse, CNRS and Université Paris-Sud, F-91405 Orsay (France); Rusconi, C. [Università dell' Insubria, Dipartimento di Scienza e Alta Tecnologia, 22100 Como, Italy, (Italy); INFN, Sezione di Milano Bicocca, 20126 Milano (Italy)

    2013-05-01

    In germanium-based light detectors for scintillating bolometers, a SiO{sub 2} anti-reflective coating is often applied on the side of the germanium wafer exposed to light with the aim to improve its light collection efficiency. In this paper, we report about a measurement, performed in the temperature range 25–35 mK, of the light-collection increase obtained thanks to this method, which resulted to be of the order of 20%. The procedure followed has been carefully selected in order to minimize systematic effects. The employed light sources have the same spectral features (peaking at ∼630nm wavelength) that will characterize future neutrinoless double beta decay experiments on the isotope {sup 82}Se and based on ZnSe crystals, such as LUCIFER. The coupling between source and light detector reproduces the configuration used in scintillating bolometers. The present measurement clarifies the role of SiO{sub 2} coating and describes a method and a set-up that can be extended to the study of other types of coatings and luminescent materials.

  16. UV detector based on InAlN/GaN-on-Si HEMT stack with photo-to-dark current ratio > 107

    Science.gov (United States)

    kumar, Sandeep; Pratiyush, Anamika Singh; Dolmanan, Surani B.; Tripathy, Sudhiranjan; Muralidharan, Rangarajan; Nath, Digbijoy N.

    2017-12-01

    We demonstrate an InAlN/GaN-on-Si high electron mobility transistor based UV detector with a photo-to-dark current ratio of >107. The Ti/Al/Ni/Au metal stack was evaporated and thermal annealed rapidly for Ohmic contacts to the 2D electron gas (2DEG) at the InAlN/GaN interface, while the channel + barrier was recess etched to a depth of 20 nm to pinch-off the 2DEG between Source-Drain pads. A spectral responsivity (SR) of 32.9 A/W at 367 nm was measured at 5 V. A very high photo-to-dark current ratio of >107 was measured at a bias of 20 V. The photo-to-dark current ratio at a fixed bias was found to be decreasing with an increase in the recess length of photodetectors. The fabricated devices were found to exhibit a UV-to-visible rejection ratio of >103 with a low dark current of < 32 pA at 5 V. Transient measurements showed rise and fall times in the range of 3-4 ms. The gain mechanism was investigated, and carrier lifetimes were estimated which matched well with those reported elsewhere.

  17. Characteristic performance evaluation of a photon counting Si strip detector for low dose spectral breast CT imaging

    Science.gov (United States)

    Cho, Hyo-Min; Barber, William C.; Ding, Huanjun; Iwanczyk, Jan S.; Molloi, Sabee

    2014-01-01

    Purpose: The possible clinical applications which can be performed using a newly developed detector depend on the detector's characteristic performance in a number of metrics including the dynamic range, resolution, uniformity, and stability. The authors have evaluated a prototype energy resolved fast photon counting x-ray detector based on a silicon (Si) strip sensor used in an edge-on geometry with an application specific integrated circuit to record the number of x-rays and their energies at high flux and fast frame rates. The investigated detector was integrated with a dedicated breast spectral computed tomography (CT) system to make use of the detector's high spatial and energy resolution and low noise performance under conditions suitable for clinical breast imaging. The aim of this article is to investigate the intrinsic characteristics of the detector, in terms of maximum output count rate, spatial and energy resolution, and noise performance of the imaging system. Methods: The maximum output count rate was obtained with a 50 W x-ray tube with a maximum continuous output of 50 kVp at 1.0 mA. A109Cd source, with a characteristic x-ray peak at 22 keV from Ag, was used to measure the energy resolution of the detector. The axial plane modulation transfer function (MTF) was measured using a 67 μm diameter tungsten wire. The two-dimensional (2D) noise power spectrum (NPS) was measured using flat field images and noise equivalent quanta (NEQ) were calculated using the MTF and NPS results. The image quality parameters were studied as a function of various radiation doses and reconstruction filters. The one-dimensional (1D) NPS was used to investigate the effect of electronic noise elimination by varying the minimum energy threshold. Results: A maximum output count rate of 100 million counts per second per square millimeter (cps/mm2) has been obtained (1 million cps per 100 × 100 μm pixel). The electrical noise floor was less than 4 keV. The energy resolution

  18. Evaluation of a SiPM array detector coupled to a LFS-3 pixellated scintillator for PET/MR applications

    International Nuclear Information System (INIS)

    David, Stratos; Fysikopoulos, Eleftherios; Georgiou, Maria; Loudos, George

    2015-01-01

    SiPM arrays are insensitive to magnetic fields and thus good candidates for hybrid PET/MR imaging systems. Moreover, due to their small size and flexibility can be used in dedicated small field of view small animal imaging detectors and especially in head PET/MR studies in mice. Co-doped LFS-3 scintillator crystals have higher light yield and slightly faster response than that of LSO:Ce mainly due to the co-doped activation of emission centers with varying materials such as Ce, Gd, Sc, Y, La, Tb, or Ca distributed at the molecular scale through the lutetium silicate crystal host. The purpose of this study is to investigate the behavior of the SensL ArraySL-4 (4x4 element array of 3x3 mm 2 silicon photomultipliers) optical detector coupled to a 6x6 LFS-3 scintillator array, with 2x2x5 mm 3 crystal size elements, for possible applications in small field of view PET/MR imaging detectors. We have designed a symmetric resistive charge division circuit to read out the signal outputs of 4x4 pixel SiPM array reducing the 16 pixel outputs of the photodetector to 4 position signals. The 4 position signals were digitized using free running Analog to Digital Converters. The ADCs sampling rate was 50 MHz. An FPGA (Spartan 6 LX150T) was used for triggering and digital signal processing of the pulses. Experimental evaluation was carried out with 22 Na radioactive source and the parameters studied where energy resolution and peak to valley ratio. The first preliminary results of the evaluation shows a clear visualization of the discrete 2x2x5 mm 3 LFS-3 scintillator elements. The mean peak to valley ratio of the horizontal profiles on the raw image was measured equal to 11 while the energy resolution was calculated equal to 30% at the central pixels.

  19. High-performance 4H-SiC junction barrier Schottky diodes with double resistive termination extensions

    International Nuclear Information System (INIS)

    Zheng Liu; Zhang Feng; Liu Sheng-Bei; Dong Lin; Liu Xing-Fang; Liu Bin; Yan Guo-Guo; Wang Lei; Zhao Wan-Shun; Sun Guo-Sheng; He Zhi; Fan Zhong-Chao; Yang Fu-Hua

    2013-01-01

    4H-SiC junction barrier Schottky (JBS) diodes with a high-temperature annealed resistive termination extension (HARTE) are designed, fabricated and characterized in this work. The differential specific on-state resistance of the device is as low as 3.64 mΩ·cm 2 with a total active area of 2.46 × 10 −3 cm 2 . Ti is the Schottky contact metal with a Schottky barrier height of 1.08 V and a low onset voltage of 0.7 V. The ideality factor is calculated to be 1.06. Al implantation annealing is performed at 1250°C in Ar, while good reverse characteristics are achieved. The maximum breakdown voltage is 1000 V with a leakage current of 9 × 10 −5 A on chip level. These experimental results show good consistence with the simulation results and demonstrate that high-performance 4H-SiC JBS diodes can be obtained based on the double HARTE structure. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  20. Testing and further development of a low-noise Si radiation detector

    International Nuclear Information System (INIS)

    Pho Duc, C.

    1995-02-01

    The functionality of a double DEP-MOSFET was proved, and the attempted improvement of energy resolution was achieved by controlling the signal electrons. The numerical simulation of the detector function provided important information for this. The experiment was caried out as an independent project with specially developed hardware and software. In particular, the absolute mesasurement of the output signal with subsequent data analysis was implemented, which is necessary for multiple selection. On the basis of the experimental findings, conclusions are drawn for the further development of this detector concept

  1. Characterization of Si detectors, search for vertex and potentiality of detecting a light charged Higgs boson in the CMS experiment

    International Nuclear Information System (INIS)

    Estre, N.

    2004-01-01

    The CMS (compact muon solenoid) detector that will be set on the future LHC (large hadron collider) accelerator will enable us to continue our search for the Higgs boson as well as to look for any hint for a new physics beyond the standard model. CMS is composed of an efficient muon detector, an electromagnetic calorimeter and of a tracker with high spatial resolution, this tracker is the topic of this thesis. The tracker will allow an accurate reconstruction of charged-particles trajectories and the reconstruction of the primary interaction vertex. The tracker's technology is based on micro-strip Si detectors, tests performed with the SPS particle beam show that these detectors have an impact reconstruction efficiency greater than 98% and a piling-up rate limited to 6%. The spatial resolution concerning particle trajectories is about 45 μm for an interval of 183 μm between 2 strips. The simulation for the search for a light charged Higgs boson show that an excess of τν τ + bb-bar + qq-bar' events is possible to be observed for any value of tan(β) up to M A = 122 GeV/c 2 during the first year of operation and up to 136 GeV/c 2 afterwards. With the assumption that this event excess is due to the decay of charged Higgs bosons we can state that the assessment of its mass will be possible till m H = 150 GeV/c 2 with an accuracy of 15 GeV/c 2 . (A.C.)

  2. Effect of Aluminum on Characterization of ZnTe/n-Si Heterojunction Photo detector

    Science.gov (United States)

    Maki, Samir A.; Hassun, Hanan K.

    2018-05-01

    Aluminum doped zinc telluride ZnTenSi thin films of (400nm) thickness with (005 01 015 and 02) wt % were deposited on the glass substrate and nSi wafer to fabricate ZnTenSi heterojunction Photodetector by using thermal vacuum evaporation technique Structural optical electrical and photovoltaic properties are investigated for the samples XRD analysis shows that all the deposited ZnTenSi films show polycrystalline structure with cubic phases and highest sharp peak corresponding to (111) planes and from AFM images shows the surface roughness increase with increase Al percentage ratio The optical absorption measurement of the films was find from transmittance ranges in the variety of wavelength (400 1000) nm and the optical energy band gap decrease from 224 eV to 186 eV dependent upon the Aluminum ratio in the films moreover our studies contain the calculation of the electrical properties of hetero junction were obtained via IV (dark and light condition) and C V measurement The photoelectric properties indicated rise illumination current of heterojunctions through increasing both of incident lighting intensity and Aluminum dopant The values of specific detectivity and quantum efficiency are calculated for all samples also the best spectral response occurs when Al doping ratio 02% The high photo sensitivity and comparatively fast response haste are attributable to in height crystal quality of the [ZnTe ] thin films.

  3. A fast preamplifier concept for SiPM-based time-of-flight PET detectors

    NARCIS (Netherlands)

    Huizenga, J.; Seifert, S.; Schreuder, F.; Dendooven, P.; Löhner, H.; Vinke, R.; Schaart, D. R.; van Dam, H.T.

    2012-01-01

    Silicon photomultipliers (SiPMs) offer high gain and fast response to light, making them interesting for fast timing applications such as time-of-flight (TOF) PET. To fully exploit the potential of these photosensors, dedicated preamplifiers that do not deteriorate the rise time and signal-to-noise

  4. A Fast Calibration System for SiPM Based Scintillator HCAL Detector

    CERN Document Server

    Polak, I

    2015-01-01

    with mid-range a fixed-intensity light pulse. The full SiPM response function is cross-checked by varying the light intensity from zero to the saturation level. In calibration systems we developed, we concentrate especially on the aspect a high dynamic range of pre...

  5. Electroless Ni-Mo-P diffusion barriers with Pd-activated self-assembled monolayer on SiO2

    International Nuclear Information System (INIS)

    Liu Dianlong; Yang Zhigang; Zhang Chi

    2010-01-01

    Ternary Ni-based amorphous films can serve as a diffusion barrier layer for Cu interconnects in ultralarge-scale integration (ULSI) applications. In this paper, electroless Ni-Mo-P films deposited on SiO 2 layer without sputtered seed layer were prepared by using Pd-activated self-assembled monolayer (SAM). The solutions and operating conditions for pretreatment and deposition were presented, and the formation of Pd-activated SAM was demonstrated by XPS (X-ray photoelectron spectroscopy) analysis and BSE (back-scattered electron) observation. The effects of the concentration of Na 2 MoO 4 added in electrolytes, pH value, and bath temperature on the surface morphology and compositions of Ni-Mo-P films were investigated. The microstructures, diffusion barrier property, electrical resistivity, and adhesion were also examined. Based on the experimental results, the Ni-Mo-P alloys produced by using Pd-activated SAM had an amorphous or amorphous-like structure, and possessed good performance as diffusion barrier layer.

  6. Development and Property Evaluation of Selected HfO2-Silicon and Rare Earth-Silicon Based Bond Coats and Environmental Barrier Coating Systems for SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming

    2016-01-01

    Ceramic environmental barrier coatings (EBC) and SiC/SiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft propulsion systems because of their ability to significantly increase engine operating temperatures, improve component durability, reduce engine weight and cooling requirements. Advanced EBC systems for SiC/SiC CMC turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant material development challenges for the high temperature CMC components is to develop prime-reliant, high strength and high temperature capable environmental barrier coating bond coat systems, since the current silicon bond coat cannot meet the advanced EBC-CMC temperature and stability requirements. In this paper, advanced NASA HfO2-Si and rare earth Si based EBC bond coat EBC systems for SiC/SiC CMC combustor and turbine airfoil applications are investigated. High temperature properties of the advanced EBC systems, including the strength, fracture toughness, creep and oxidation resistance have been studied and summarized. The advanced NASA EBC systems showed some promise to achieve 1500C temperature capability, helping enable next generation turbine engines with significantly improved engine component temperature capability and durability.

  7. Performance Study of an aSi Flat Panel Detector for Fast Neutron Imaging of Nuclear Waste

    Energy Technology Data Exchange (ETDEWEB)

    Schumann, M.; Mauerhofer, E. [Institute of Energy and Climate Research - Nuclear Waste Management and Reactor Safety, Forschungszentrum Juelich GmbH, 52425 Juelich (Germany); Engels, R.; Kemmerling, G. [Central Institute for Engineering, Electronics and Analytics - Electronic Systems, Forschungszentrum Juelich GmbH, 52425 Juelich (Germany); Frank, M. [MATHCCES - Department of Mathematics, RWTH Aachen University, 52062 Aachen (Germany); Havenith, A.; Kettler, J.; Klapdor-Kleingrothaus, T. [Institute of Nuclear Engineering and Technology Transfer, RWTH Aachen University, 52062 Aachen (Germany); Schitthelm, O. [Corporate Technology, Siemens AG, 91058 Erlangen (Germany)

    2015-07-01

    Radioactive waste must be characterized to check its conformance for intermediate storage and final disposal according to national regulations. For the determination of radio-toxic and chemo-toxic contents of radioactive waste packages non-destructive analytical techniques are preferentially used. Fast neutron imaging is a promising technique to assay large and dense items providing, in complementarity to photon imaging, additional information on the presence of structures in radioactive waste packages. Therefore the feasibility of a compact Neutron Imaging System for Radioactive waste Analysis (NISRA) using 14 MeV neutrons is studied in a cooperation framework of Forschungszentrum Juelich GmbH, RWTH Aachen University and Siemens AG. However due to the low neutron emission of neutron generators in comparison to research reactors the challenging task resides in the development of an imaging detector with a high efficiency, a low sensitivity to gamma radiation and a resolution sufficient for the purpose. The setup is composed of a commercial D-T neutron generator (Genie16GT, Sodern) with a surrounding shielding made of polyethylene, which acts as a collimator and an amorphous silicon flat panel detector (aSi, 40 x 40 cm{sup 2}, XRD-1642, Perkin Elmer). Neutron detection is achieved using a general propose plastic scintillator (EJ-260, Eljen Technology) linked to the detector. The thermal noise of the photodiodes is reduced by employing an entrance window made of aluminium. Optimal gain and integration time for data acquisition are set by measuring the response of the detector to the radiation of a 500 MBq {sup 241}Am-source. Detector performance was studied by recording neutron radiography images of materials with various, but well known, chemical compositions, densities and dimensions (Al, C, Fe, Pb, W, concrete, polyethylene, 5 x 8 x 10 cm{sup 3}). To simulate gamma-ray emitting waste radiographs in presence of a gamma-ray sources ({sup 60}Co, {sup 137}Cs, {sup 241

  8. Time resolution below 100 ps for the SciTil detector of PANDA employing SiPM

    Science.gov (United States)

    Brunner, S. E.; Gruber, L.; Marton, J.; Orth, H.; Suzuki, K.

    2014-03-01

    The barrel time-of-flight (TOF) detector for the bar PANDA experiment at FAIR in Darmstadt is planned as a scintillator tile hodoscope (SciTil) using 8000 small scintillator tiles. It will provide fast event timing for a software trigger in the otherwise trigger-less data acquisition scheme of bar PANDA, relative timing in a multiple track event topology as well as additional particle identification in the low momentum region. The goal is to achieve a time resolution of σ simeq 100 ps. We have conducted measurements using organic scintillators coupled to Silicon Photomultipliers (SiPM). The results are encouraging such that we are confident to reach the required system time resolution.

  9. New developments at INFN-LNS on TOF–DOI PET based on SiPM detectors

    International Nuclear Information System (INIS)

    Cosentino, L.; Cusanno, F.; De Leo, R.; Di Venti, G.; Finocchiaro, P.; Garibaldi, F.; Loddo, F.; Meddi, F.; Musico, P.; Pappalardo, A.; Perrino, R.; Ranieri, A.

    2013-01-01

    The development of an endorectal PET Time Of Flight (TOF) probe prototype compatible with MRI, is going to be carried out within the INFN project TOPEM. Time resolution and depth of interaction (DOI) will allow to significantly improve the image quality, by rejecting those events coming from the surrounding tissues and correcting the parallax error. The activity described in this paper is focused on the characterization of the single pixel detector of the probe, consisting of a LYSO finger scintillator read out at both ends by means of a pair of Silicon Photomultipliers (SiPM). Energy, timing and DOI resolutions have been measured with a proper surface treatment and wrapping, finding very competitive results for DOI and timing

  10. Commissioning of the scatter component of a Compton camera consisting of a stack of Si strip detectors

    Energy Technology Data Exchange (ETDEWEB)

    Liprandi, S.; Marinsek, T.; Bortfeldt, J.; Lang, C.; Lutter, R.; Dedes, G.; Parodi, K.; Thirolf, P.G. [LMU Munich, Garching (Germany); Aldawood, S. [LMU Munich, Garching (Germany); King Saud University, Riyadh (Saudi Arabia); Maier, L.; Gernhaeuser, R. [TU Munich, Garching (Germany); Kolff, H. van der [LMU Munich, Garching (Germany); TU Delft (Netherlands); Castelhano, I. [LMU Munich, Garching (Germany); University of Lisbon, Lisbon (Portugal); Schaart, D.R. [TU Delft (Netherlands)

    2015-07-01

    At LMU Munich in Garching a Compton camera is presently being developed aiming at the range verification of proton (or ion) beams for hadron therapy via imaging of prompt γ rays from nuclear reactions in the tissue. The poster presentation focuses on the characterization of the scatter component of the Compton camera, consisting of a stack of six double-sided Si strip detectors (50 x 50 mm{sup 2}, 0.5 mm thick, 128 strips/side). The overall 1536 electronics channels are processed by a readout system based on the GASSIPLEX ASIC chip, feeding into a VME-based data acquisition system. The status of the offline and online characterization studies is presented.

  11. An educational distributed Cosmic Ray detector network based on ArduSiPM

    Science.gov (United States)

    Bocci, V.; Chiodi, G.; Fresch, P.; Iacoangeli, F.; Recchia, L.

    2017-10-01

    The advent of high performance microcontrollers equipped with analog and digital peripherals, makes the design of a complete particle detector and a relative acquisition system on a single microcontroller chip possible. The existence of a world wide data infrastructure such as the internet, allows for the conception of a distributed network of cheap detectors able to elaborate and send data as well as to respond to setting commands. The internet infrastructure enables the distribution of the absolute time, with precision of a few milliseconds, to all devices independently of their physical location, when the sky view is accessible it possible to use a GPS module to reach synchronization of tens of nanoseconds. These devices can be far apart from each other and their relative distance can range from a few meters to thousands of kilometers. This allows for the design of a crowdsourcing experiment of citizen science, based on the use of many small scintillation-based particle detectors to monitor the high energetic cosmic ray and the radiation environment.

  12. Radiation effects in the Si-PIN detector on the Near Earth Asteroid Rendezvous mission

    CERN Document Server

    Starr, R; Evans, L G; Floyd, S R; McClanahan, T P; Trombka, J I; Goldsten, J O; Maurer, R H; McNutt, R L; Roth, D R

    1999-01-01

    A Si-PIN photodiode is being used as a solar X-ray monitor on the X-ray/gamma-ray spectrometer experiment which is flying on the Near Earth Asteroid Rendezvous spacecraft. Since its launch in February 1996 this photodiode has experienced several brief failures. These anomalies and other performance characteristics will be described. Efforts to reproduce these failures in ground tests with flight spare equipment will also be discussed.

  13. SiPM and ADD as advanced detectors for astro-particle physics

    International Nuclear Information System (INIS)

    Mirzoyan, Razmick; Dolgoshein, Boris; Holl, Peter; Klemin, Sergei; Merck, Christine; Moser, Hans-Guenther; Otte, Adam Nepomuk; Ninkovic, Jelena; Popova, Elena; Richter, Rainer; Teshima, Masahiro

    2007-01-01

    In recent years, a few scientific groups are developing a novel type light sensor. These so-called silicon photo multipliers (SiPM) operate at relatively low bias voltage of 20-60 V, show unprecedented amplitude resolution and already now can provide photon detection efficiencies (PDE) comparable to or better than that of classical photo multipliers (PMT). We are developing the novel sensors for the astro-particle physics experiments MAGIC [J. Albert, et al., Astrophys. Lett. 642 (2006) L119. ] and also for EUSO [M. Teshima, et al., EUSO (The Extreme Universe Space Observatory), in: Scientific Objectives Proceedings ICRC, 2003, p. 10690. ]. The front-illuminated SiPM are developing with the group from MEPhI in Moscow and the back-illuminated Avalanche Drift Diodes (ADD) with the semiconductor laboratory (HLL) attached to the MPI for Physics. Our goal is to produce 5-10 mm size ultra-fast, low-noise and very high PDE (60-80%) sensors operating in the wavelength range 300-600 nm. Together with MEPhI, we have already produced and successfully tested 1.3x1.3, 3x3 and 5x5 mm 2 size SiPMs. Very recently, the first ADD test structures were produced and are under evaluation at the HLL. In this report, we want to outline the main parameters of the new sensors for the needs of astro-particle physics experiments

  14. Influence of average ion energy and atomic oxygen flux per Si atom on the formation of silicon oxide permeation barrier coatings on PET

    Science.gov (United States)

    Mitschker, F.; Wißing, J.; Hoppe, Ch; de los Arcos, T.; Grundmeier, G.; Awakowicz, P.

    2018-04-01

    The respective effect of average incorporated ion energy and impinging atomic oxygen flux on the deposition of silicon oxide (SiO x ) barrier coatings for polymers is studied in a microwave driven low pressure discharge with additional variable RF bias. Under consideration of plasma parameters, bias voltage, film density, chemical composition and particle fluxes, both are determined relative to the effective flux of Si atoms contributing to film growth. Subsequently, a correlation with barrier performance and chemical structure is achieved by measuring the oxygen transmission rate (OTR) and by performing x-ray photoelectron spectroscopy. It is observed that an increase in incorporated energy to 160 eV per deposited Si atom result in an enhanced cross-linking of the SiO x network and, therefore, an improved barrier performance by almost two orders of magnitude. Furthermore, independently increasing the number of oxygen atoms to 10 500 per deposited Si atom also lead to a comparable barrier improvement by an enhanced cross-linking.

  15. On the efficiency calibration of Si(Li) detector in the low-energy region using thick-target bremsstrahlung

    Energy Technology Data Exchange (ETDEWEB)

    An, Z. E-mail: anzhu@scu.edu.cn; Liu, M.T

    2002-10-01

    In this paper, the efficiency calibration of a Si(Li) detector in the low-energy region down to 0.58 keV has been performed using thick-carbon-target bremsstrahlung by 19 keV electron impact. The shape of the efficiency calibration curve was determined from the thick-carbon-target bremsstrahlung spectrum, and the absolute value for the efficiency calibration was obtained from the use of {sup 241}Am radioactive standard source. The modified Wentzel's formula for thick-target bremsstrahlung was employed and it was also compared with the most recently developed theoretical model based upon the doubly differential cross-sections for bremsstrahlung of Kissel, Quarles and Pratt. In the present calculation of theoretical bremsstrahlung, the self-absorption correction and the convolution of detector's response function with the bremsstrahlung spectrum have simultaneously been taken into account. The accuracy for the efficiency calibration in the low-energy region with the method described here was estimated to be about 6%. Moreover, the self-absorption correction calculation based upon the prescription of Wolters et al. has also been presented as an analytical factor with the accuracy of {approx}1%.

  16. SiC Schottky Diode Detectors for Measurement of Actinide Concentrations from Alpha Activities in Molten Salt Electrolyte

    International Nuclear Information System (INIS)

    Windl, Wolfgang; Blue, Thomas

    2013-01-01

    In this project, we have designed a 4H-SiC Schottky diode detector device in order to monitor actinide concentrations in extreme environments, such as present in pyroprocessing of spent fuel. For the first time, we have demonstrated high temperature operation of such a device up to 500 °C in successfully detecting alpha particles. We have used Am-241 as an alpha source for our laboratory experiments. Along with the experiments, we have developed a multiscale model to study the phenomena controlling the device behavior and to be able to predict the device performance. Our multiscale model consists of ab initio modeling to understand defect energetics and their effect on electronic structure and carrier mobility in the material. Further, we have developed the basis for a damage evolution model incorporating the outputs from ab initio model in order to predict respective defect concentrations in the device material. Finally, a fully equipped TCAD-based device model has been developed to study the phenomena controlling the device behavior. Using this model, we have proven our concept that the detector is capable of performing alpha detection in a salt bath with the mixtures of actinides present in a pyroprocessing environment.

  17. SiC Schottky Diode Detectors for Measurement of Actinide Concentrations from Alpha Activities in Molten Salt Electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Windl, Wolfgang [The Ohio State Univ., Columbus, OH (United States); Blue, Thomas [The Ohio State Univ., Columbus, OH (United States)

    2013-01-28

    In this project, we have designed a 4H-SiC Schottky diode detector device in order to monitor actinide concentrations in extreme environments, such as present in pyroprocessing of spent fuel. For the first time, we have demonstrated high temperature operation of such a device up to 500 °C in successfully detecting alpha particles. We have used Am-241 as an alpha source for our laboratory experiments. Along with the experiments, we have developed a multiscale model to study the phenomena controlling the device behavior and to be able to predict the device performance. Our multiscale model consists of ab initio modeling to understand defect energetics and their effect on electronic structure and carrier mobility in the material. Further, we have developed the basis for a damage evolution model incorporating the outputs from ab initio model in order to predict respective defect concentrations in the device material. Finally, a fully equipped TCAD-based device model has been developed to study the phenomena controlling the device behavior. Using this model, we have proven our concept that the detector is capable of performing alpha detection in a salt bath with the mixtures of actinides present in a pyroprocessing environment.

  18. Development Status and Performance Comparisons of Environmental Barrier Coating Systems for SiCSiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan

    2016-01-01

    Environmental barrier coatings (EBC) and SiCSiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft turbine engine systems, because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. This paper presents current NASA EBC-CMC development emphases including: the coating composition and processing improvements, laser high heat flux-thermal gradient thermo-mechanical fatigue - environmental testing methodology development, and property evaluations for next generation EBC-CMC systems. EBCs processed with various deposition techniques including Plasma Spray, Electron Beam - Physical Vapor Deposition, and Plasma Spray Physical Vapor Deposition (PS-PVD) will be particularly discussed. The testing results and demonstrations of advanced EBCs-CMCs in complex simulated engine thermal gradient cyclic fatigue, oxidizing-steam and CMAS environments will help provide insights into the coating development strategies to meet long-term engine component durability goals.

  19. Simulation of Si P-i-N diodes for use in a positron emission tomography detector module

    International Nuclear Information System (INIS)

    Bailey, M.J.; University of Wollongong, NSW; Rosenfeld, A.; Lerch, M.; Taylor, G.; Heiser, G.

    2000-01-01

    Full text: Current Positron Emission Tomography (PET) systems consist of scintillation crystals optically coupled to photomultiplier tubes with associated electronics used to detect photons generated within the scintillator. The cost of photomultiplier tubes (PMTs) is considerable and is the major factor in the cost of PET systems. It has been suggested that Si P-i-N diodes can replace PMTs and provide Depth of Interaction (DOI) information for improved spatial resolution. Si P-i-N diodes of 25mm x 300μm and 3mm x 300μm cross sectional area were simulated using a 2D Monte Carlo program (PClD V5) from the UNSW photovoltics group. The diffusion lengths were varied from 0.5μm to 5μm and the charge collection characteristics of the diodes were observed. A 400nm monochromatic light source was used for the excitation as an approximation of the mean wavelength output from LSO crystal. The diodes were reverse biased with voltages 40V, 20V and 10V. The optimum diffusion length of up to 2μm and bias voltage of 40V were determined using the electric field, current density, carrier density and potential distribution results. These parameters will be used for the design of a device for optimal charge collection capabilities for the wavelengths encountered in PET applications. Further studies need to be conducted using spectra from LSO rather than a monochromatic source. The response of various Si P-i-N diodes to a monochromatic light source have been modeled in order to design a device for application in a PET detector module for DOI measurements. The charge collection within the first 2μm has been emphasized due to the strong absorption of photons from LSO near the surface.Copyright (2000) Australasian College of Physical Scientists and Engineers in Medicine

  20. Central tracker for BM@N experiment based on double side Si-microstrip detectors

    Science.gov (United States)

    Kovalev, Yu.; Kapishin, M.; Khabarov, S.; Shafronovskaia, A.; Tarasov, O.; Makankin, A.; Zamiatin, N.; Zubarev, E.

    2017-07-01

    Design of central tracker system based on Double-Sided Silicon Detectors (DSSD) for BM@N experiment is described. A coordinate plane with 10240 measuring channels, pitch adapter, reading electronics was developed. Each element was tested and assembled into a coordinate plane. The first tests of the plane with 106Ru source were carried out before installation for the BM@N experiment. The results of the study indicate that noisy channels and inefficient channels are less than 3%. In general, single clusters 87% (one group per module of consecutive strips) and 75% of clusters with a width equal to one strip.

  1. Characteristics of Si-PIN diode X-ray detector with DSP electronics

    International Nuclear Information System (INIS)

    Dutta, Juhi; Tapader, Srijita; Bisoi, Abhijit; Ray, Sudatta; Saha Sarkar, M.; Pramanik, Dibyadyuti; Saha, Archisman

    2012-01-01

    In the present work, the studies to investigate the features of PIN diodes detector coupled with a digital processor have been extended. At low energies, backscattered Compton peaks are close in energy to photo peak of the gamma of interest. Thus the backscattered peaks pose a serious problem in the analysis of spectra of low energy gamma rays. It has been initiated some measurements to quantitatively estimate the same as function of energy and Z of the scatterer. Recently there has been application of backscattering in high-resolution gamma backscatter imaging for technical applications

  2. Evaluation of a SiPM array detector coupled to a LFS-3 pixellated scintillator for PET/MR applications

    Energy Technology Data Exchange (ETDEWEB)

    David, Stratos; Fysikopoulos, Eleftherios [Technological Educational Institute of Athens (Greece); Georgiou, Maria [Technological Educational Institute of Athens (Greece); Department of Medical School, University of Thessaly, Larissa (Greece); Loudos, George [Technological Educational Institute of Athens (Greece)

    2015-05-18

    SiPM arrays are insensitive to magnetic fields and thus good candidates for hybrid PET/MR imaging systems. Moreover, due to their small size and flexibility can be used in dedicated small field of view small animal imaging detectors and especially in head PET/MR studies in mice. Co-doped LFS-3 scintillator crystals have higher light yield and slightly faster response than that of LSO:Ce mainly due to the co-doped activation of emission centers with varying materials such as Ce, Gd, Sc, Y, La, Tb, or Ca distributed at the molecular scale through the lutetium silicate crystal host. The purpose of this study is to investigate the behavior of the SensL ArraySL-4 (4x4 element array of 3x3 mm{sup 2} silicon photomultipliers) optical detector coupled to a 6x6 LFS-3 scintillator array, with 2x2x5 mm{sup 3} crystal size elements, for possible applications in small field of view PET/MR imaging detectors. We have designed a symmetric resistive charge division circuit to read out the signal outputs of 4x4 pixel SiPM array reducing the 16 pixel outputs of the photodetector to 4 position signals. The 4 position signals were digitized using free running Analog to Digital Converters. The ADCs sampling rate was 50 MHz. An FPGA (Spartan 6 LX150T) was used for triggering and digital signal processing of the pulses. Experimental evaluation was carried out with {sup 22}Na radioactive source and the parameters studied where energy resolution and peak to valley ratio. The first preliminary results of the evaluation shows a clear visualization of the discrete 2x2x5 mm{sup 3} LFS-3 scintillator elements. The mean peak to valley ratio of the horizontal profiles on the raw image was measured equal to 11 while the energy resolution was calculated equal to 30% at the central pixels.

  3. Prototype Si microstrip sensors for the CDF-II ISL detector

    CERN Document Server

    Hara, K; Kanao, K; Kim, S; Ogasawara, M; Ohsugi, T; Shimojima, M; Takikawa, K

    1999-01-01

    Prototype Si microstrip sensors for the CDF-II ISL were fabricated by Hamamatsu Photonics and SEIKO Instruments using 4'' technology. The sensor is AC coupled and double-sided forming a stereo angle of 1.207 degree sign . The strip pitch is 112 mu m on both sides. The main differences between the two manufacturers lie on the technologies of passivation and the structure of coupling capacitors. We describe the design of the sensor and evaluation results of the performance. The evaluations include the total and individual strip currents and interstrip capacitance measured before and after sup 6 sup 0 Co gamma irradiation. (author)

  4. Mean range and energy of 28Si ions some Makrofol track detectors

    International Nuclear Information System (INIS)

    Shyam, S.; Mishra, R.; Tripathy, S.P.; Mawar, A.K.; Dwivedi, K.K.; Khathing, D.T.; Srivastava, A.; Avasthi, D.K.

    2000-01-01

    The rate of energy loss of the impinging ion as it passes through succeeding layers of the target material gives information regarding the nature of material and helps to calculate the range of the ions in a thick target in which the ions are stopped. Here the range, energy loss of 118 MeV 28 Si were measured in Makrofol-N, Makrofol-G and Makrofol-KG, using nuclear track technique. The experimental range data are compared with the theoretical values obtained from different computer codes. (author)

  5. Si Interface Barrier Modification on Memristor for Brain-Inspired Computing

    Science.gov (United States)

    Wu, Wei; Wu, Huaqiang; Gao, Bin; Qian, He

    2017-06-01

    Memristor is an emerging technology aimed at implementing neuromorphic computing in hardware system. Resistive random access memory (RRAM) is a kind of memristor with excellent performance, but abrupt switching in the set process influences the efficiency of neuromorphic system. In this study, we present an interface switching memristor device based on TiN/Si/TaOx/TiN stack and CMOS compatible fabrication process to achieve gradually resistive switching both in set and reset processes. The devices show a more than 10 switching window. The related switching mechanism is discussed.

  6. The Fabrication and Characterization of Ni/4H-SiC Schottky Diode Radiation Detectors with a Sensitive Area of up to 4 cm².

    Science.gov (United States)

    Liu, Lin-Yue; Wang, Ling; Jin, Peng; Liu, Jin-Liang; Zhang, Xian-Peng; Chen, Liang; Zhang, Jiang-Fu; Ouyang, Xiao-Ping; Liu, Ao; Huang, Run-Hua; Bai, Song

    2017-10-13

    Silicon carbide (SiC) detectors of an Ni/4H-SiC Schottky diode structure and with sensitive areas of 1-4 cm² were fabricated using high-quality lightly doped epitaxial 4H-SiC material, and were tested in the detection of alpha particles and pulsed X-rays/UV-light. A linear energy response to alpha particles ranging from 5.157 to 5.805 MeV was obtained. The detectors were proved to have a low dark current, a good energy resolution, and a high neutron/gamma discrimination for pulsed radiation, showing the advantages in charged particle detection and neutron detection in high-temperature and high-radiation environments.

  7. The Fabrication and Characterization of Ni/4H-SiC Schottky Diode Radiation Detectors with a Sensitive Area of up to 4 cm2

    Directory of Open Access Journals (Sweden)

    Lin-Yue Liu

    2017-10-01

    Full Text Available Silicon carbide (SiC detectors of an Ni/4H-SiC Schottky diode structure and with sensitive areas of 1–4 cm2 were fabricated using high-quality lightly doped epitaxial 4H-SiC material, and were tested in the detection of alpha particles and pulsed X-rays/UV-light. A linear energy response to alpha particles ranging from 5.157 to 5.805 MeV was obtained. The detectors were proved to have a low dark current, a good energy resolution, and a high neutron/gamma discrimination for pulsed radiation, showing the advantages in charged particle detection and neutron detection in high-temperature and high-radiation environments.

  8. Effect of Barrier Metal Based on Titanium or Molybdenum in Characteristics of 4H-SiC Schottky Diodes

    Directory of Open Access Journals (Sweden)

    M. Ben Karoui

    2014-05-01

    Full Text Available The electrical properties were extracted by I-V and C-V analysis, performed from 10 K to 450 K. When the annealing temperature varied to 400 °C, the Schottky barrier height (SBH increased from 0.85 Ev to 1.20 eV in Ti/4H-SiC whereas in the Mo/4H-SiC the SBH varied from 1.04 eV to 1.10 eV. Deformation of J-V-T characteristics was observed in two types of devices when the temperature decreases from 300 K to 10 K. The electrical properties and the stability of the devices have been correlated to the fabrication processes and to the metal/semiconductor interfaces. Mo-based contacts show better behaviour in forward polarization when compared to the Ti-based Schottky contacts, with ideality factors close to the unity even after the annealing process. However, Mo-based contacts show leakage currents higher than that measured on the more optimized Ti-based Schottky.

  9. A fully integrated optical detector with a-Si:H based color photodiodes

    Energy Technology Data Exchange (ETDEWEB)

    Watty, Krystian; Merfort, Christian; Seibel, Konstantin; Schoeler, Lars; Boehm, Markus [Institute for Microsystem Technologies (IMT), University of Siegen, Hoelderlinstr. 3, 57076 Siegen (Germany)

    2010-03-15

    The fabrication of an electrophoresis separation microchip with monolithic integrated excitation light source and variospectral photodiodes for absorption detection is presented in this paper. Microchip based separation techniques are essential elements in the development of fully integrated micro-total analysis systems ({mu}-TAS). An integrated microfluidic device, like an application specific lab-on-microchip (ALM) (Seibel et al., in: MRS Spring Meeting, San Francisco, USA, 2005 1), includes all components, necessary to perform a chemical analysis on chip and it can be used as a stand-alone unit directly at the point of sampling. Variospectral diodes based on hydrogenated amorphous silicon (a-Si:H) technology allow for advanced optical detection schemes, because the spectral sensitivity of the devices can be tailored to fit the emission of specific fluorescent markers. Important features of a-Si:H variospectral photodiodes are a high dynamic range, a bias-tunable spectral sensitivity and a very good linearity for the separation of mixed color signals. Principle of ALM device. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  10. Key Durability Issues with Mullite-Based Environmental Barrier Coatings for Si-Based Ceramics

    Science.gov (United States)

    Lee, Kang N.

    2000-01-01

    Plasma-sprayed mullite (3Al2O3.2SiO2) and mullite/yttria-stabilized-zirconia (YSZ) dual layer coatings have been developed to protect silicon -based ceramics from environmental attack. Mullite-based coating systems show excellent durability in air. However, in combustion environments, corrosive species such as molten salt or water vapor penetrate through cracks in the coating and attack the Si-based ceramics along the interface. Thus the modification of the coating system for enhanced crack-resistance is necessary for long-term durability in combustion environments. Other key durability issues include interfacial contamination and coating/substrate bonding. Interfacial contamination leads to enhanced oxidation and interfacial pore formation, while a weak coating/substrate bonding leads to rapid attack of the interface by corrosive species, both of which can cause a premature failure of the coating. Interfacial contamination can be minimized by limiting impurities in coating and substrate materials. The interface may be modified to improve the coating/substrate bond.

  11. Investigation of amorphous RuMoC alloy films as a seedless diffusion barrier for Cu/p-SiOC:H ultralow-k dielectric integration

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Guohua [Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences, Shenzhen (China); The Chinese University of Hong Kong, Shatin, Hong Kong (China); Liu, Bo [Sichuan University, Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Chengdu (China); Li, Qiran [CNRS-Universite Paris Sud UMR 8622, Institut d' Electronique Fondamentale, Orsay (France)

    2015-08-15

    Ultrathin RuMoC amorphous films prepared by magnetron co-sputtering with Ru and MoC targets in a sandwiched scheme Si/p-SiOC:H/RuMoC/Cu were investigated as barrier in copper metallization. The evolution of final microstructure of RuMoC alloy films show sensitive correlation with the content of doped Mo and C elements and can be easily controlled by adjusting the sputtering power of the MoC target. There was no signal of interdiffusion between the Cu and SiOC:H layer in the sample of Cu/RuMoC/p-SiOC:H/Si, even annealing up to 500 C. Very weak signal of oxygen have been confirmed in the RuMoC barrier layer both as-deposited and after being annealed, and a good performance on preventing oxygen diffusion has been proved. Leakage current and resistivity evaluations also reveal the excellent thermal reliability of this Si/p-SiOC:H/RuMoC/Cu film stack at the temperatures up to 500 C, indicating its potential application in the advanced barrierless Cu metallization. (orig.)

  12. Near-barrier Fusion Evaporation and Fission of 28Si+174Yb and 32S+170Er

    Science.gov (United States)

    Wang, Dongxi; Lin, Chengjian; Jia, Huiming; Ma, Nanru; Sun, Lijie; Xu, Xinxing; Yang, Lei; Yang, Feng; Zhang, Huanqiao; Bao, Pengfei

    2017-11-01

    Fusion evaporation residues and fission fragments have been measured, respectively, at energies around the Coulomb barrier for the 28Si+174Yb and 32S+170Er systems forming the same compound nucleus 202Po. The excitation function of fusion evaporation, fission as well as capture reactions were deduced. Coupled-channels analyses reveal that couplings to the deformations of targets and the two-phonon states of projectiles contribute much to the enhancement of capture cross sections at sub-barrier energies. The mass and total kinetic energy of fission fragments were deduced by the time-difference method assuming full momentum transfer in a two-body kinematics. The mass-energy and mass-angle distributions were obtained and no obvious quasi-fission components were observed in this bombarding energy range. Further, mass distributions of fission fragments were fitted to extract their widths. Results show that the mass widths decrease monotonically with decreasing energy, but might start to increase when Ec.m./VB < 0.95 for both systems.

  13. Step edge influence on barrier height and contact area in vertical heterojunctions between epitaxial graphene and n-type 4H-SiC

    International Nuclear Information System (INIS)

    Tadjer, M. J.; Nyakiti, L. O.; Robinson, Z.; Anderson, T. J.; Myers-Ward, R. L.; Wheeler, V. D.; Eddy, C. R.; Gaskill, D. K.; Koehler, A. D.; Hobart, K. D.; Kub, F. J.

    2014-01-01

    Vertical rectifying contacts of epitaxial graphene grown by Si sublimation on the Si-face of 4H-SiC epilayers were investigated. Forward bias preferential conduction through the step edges was correlated by linear current density normalization. This phenomenon was observed on samples with 2.7–5.8 monolayers of epitaxial graphene as determined by X-ray photoelectron spectroscopy. A modified Richardson plot was implemented to extract the barrier height (0.81 eV at 290 K, 0.99 eV at 30 K) and the electrically dominant SiC step length of a Ti/Al contact overlapping a known region of approximately 0.52 μm wide SiC terraces

  14. Low power frontend ASIC (Anusuchak) for dosimeter using Si-PIN detector

    International Nuclear Information System (INIS)

    Darad, A.; Chandratre, V.B.

    2010-01-01

    A low power ASIC (Anusuchak) for silicon PIN detector signal processing channel designed for pocket dosimeter in 0.35 μm CMOS process. The ASIC contains two channels one for Beta particle and other for Gamma ray. The channel is a CSA integrated with a shaper, gain stage and comparator with total power consumption of 4.6 mW. The ASIC has gain of 12 mV/fC and can be raised to 29 mV/fC without degrading the noise, power or linearity specification of the channel. The channel has a peaking time of 1.2 μs with baseline recovery within 5.3 μs and noise figure of 420 e- at 0 pF. The noise slope is 17 e-/pF. The ASIC is designed for single supply of 3.3 V for which battery is available. (author)

  15. Determination of the efficiency curve for a Si-Li detector

    International Nuclear Information System (INIS)

    Aldape U, F.; Oliver, A.; Montenegro, E.C.

    1986-02-01

    In this work it is carried out a new calibration method for an X-rays detection system for PIXE analysis. This method it bases on the parametric expression introduced by Gallaher and Cipola in which the efficiency curve is obtained adjusting the parameters that they represent the solid angle, the attenuation in the absorbers of low Z and the absorption in the sensitive region of the detector, starting from calibrated radioactive sources, in those which those ray-X emitted its are in most of E > 10 KeV. In the region E < 10 Kev, the quantity of experimental points is poor and also, due to the absorption problems, its are the points where greater experimental error is made. (Author)

  16. Noise in a-Si:H p-i-n detector diodes

    International Nuclear Information System (INIS)

    Cho, G.; Qureshi, S.; Drewery, J.S.; Jing, T.; Kaplan, S.N.; Lee, H.; Mireshghi, A.; Perez-Mendez, V.; Wildermuth, D.

    1991-10-01

    Noise of a-Si:H p-i-n diodes (5 ∼ 50 μm thick) under reverse bias was investigated. The current dependent 1/f type noise was found to be the main noise component at high bias. At low bias the thermal noise from a series resistance of the p-layer and of the metallic contacts is the dominant noise source which is unrelated to the reverse current through the diode. The noise associated with the p-layer resistance decreased significantly on annealing under reverse bias, reducing the total zero bias noise by a factor 2 approximately. The noise recovered to the original value on subsequent annealing without bias. In addition to the resistive noise there seems to be a shaping time independent noise component at zero biased diodes

  17. Delivery of siRNA silencing P-gp in peptide-functionalized nanoparticles causes efflux modulation at the blood-brain barrier

    DEFF Research Database (Denmark)

    Gomes, Maria João; Kennedy, Patrick J; Martins, Susana

    2017-01-01

    AIM: Explore the use of transferrin-receptor peptide-functionalized nanoparticles (NPs) targeting blood-brain barrier (BBB) as siRNA carriers to silence P-glycoprotein (P-gp). MATERIALS & METHODS: Permeability experiments were assessed through a developed BBB cell-based model; P-gp mRNA expression...

  18. Investigation of enzyme-sensitive lipid nanoparticles for delivery of siRNA to blood–brain barrier and glioma cells

    DEFF Research Database (Denmark)

    Bruun, Jonas; Larsen, Trine Bjørnbo; Jølck, Rasmus Irming

    2015-01-01

    Clinical applications of siRNA for treating disorders in the central nervous system require development of systemic stable, safe, and effective delivery vehicles that are able to cross the impermeable blood–brain barrier (BBB). Engineering nanocarriers with low cellular interaction during systemi...

  19. Microcalcification detectability using a bench-top prototype photon-counting breast CT based on a Si strip detector.

    Science.gov (United States)

    Cho, Hyo-Min; Ding, Huanjun; Barber, William C; Iwanczyk, Jan S; Molloi, Sabee

    2015-07-01

    To investigate the feasibility of detecting breast microcalcification (μCa) with a dedicated breast computed tomography (CT) system based on energy-resolved photon-counting silicon (Si) strip detectors. The proposed photon-counting breast CT system and a bench-top prototype photon-counting breast CT system were simulated using a simulation package written in matlab to determine the smallest detectable μCa. A 14 cm diameter cylindrical phantom made of breast tissue with 20% glandularity was used to simulate an average-sized breast. Five different size groups of calcium carbonate grains, from 100 to 180 μm in diameter, were simulated inside of the cylindrical phantom. The images were acquired with a mean glandular dose (MGD) in the range of 0.7-8 mGy. A total of 400 images was used to perform a reader study. Another simulation study was performed using a 1.6 cm diameter cylindrical phantom to validate the experimental results from a bench-top prototype breast CT system. In the experimental study, a bench-top prototype CT system was constructed using a tungsten anode x-ray source and a single line 256-pixels Si strip photon-counting detector with a pixel pitch of 100 μm. Calcium carbonate grains, with diameter in the range of 105-215 μm, were embedded in a cylindrical plastic resin phantom to simulate μCas. The physical phantoms were imaged at 65 kVp with an entrance exposure in the range of 0.6-8 mGy. A total of 500 images was used to perform another reader study. The images were displayed in random order to three blinded observers, who were asked to give a 4-point confidence rating on each image regarding the presence of μCa. The μCa detectability for each image was evaluated by using the average area under the receiver operating characteristic curve (AUC) across the readers. The simulation results using a 14 cm diameter breast phantom showed that the proposed photon-counting breast CT system can achieve high detection accuracy with an average AUC greater

  20. In-situ fabrication of MoSi{sub 2}/SiC–Mo{sub 2}C gradient anti-oxidation coating on Mo substrate and the crucial effect of Mo{sub 2}C barrier layer at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jun [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084 (China); State Key Laboratory of New Ceramics and Fine Processing, Beijing 100084 (China); Gong, Qianming, E-mail: gongqianming@mail.tsinghua.edu.cn [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084 (China); State Key Laboratory of New Ceramics and Fine Processing, Beijing 100084 (China); Shao, Yang; Zhuang, Daming [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084 (China); State Key Laboratory of New Ceramics and Fine Processing, Beijing 100084 (China); Liang, Ji [Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China)

    2014-07-01

    MoSi{sub 2}/SiC–Mo{sub 2}C gradient coating on molybdenum was in situ prepared with pack cementation process by two steps: (1) carburizing with graphite powder to obtain a Mo{sub 2}C layer on Mo substrate, and (2) siliconizing with Si powder to get a composite MoSi{sub 2}/SiC layer on the upper part of Mo{sub 2}C layer. The microstructure and elemental distribution in the coating were investigated with scanning electron microscopy (SEM), backscattered electron (BSE), energy dispersive spectroscopy (EDS), electron probe microanalysis (EPMA) and X-ray diffraction (XRD). Cyclic oxidation tests (at 500 °C, 1200 °C, 1400 °C and 1600 °C) demonstrated excellent oxidation resistance for the gradient composite coating and the mass loss was only 0.23% in 60 min at 1600 °C. XRD, EPMA, thermal dynamic and phase diagram analyses indicated that the Mo{sub 2}C barrier layer played the key role in slowing down the diffusion of C and Si toward inner Mo substrate at high temperature and principally this contributed to the excellent anti-oxidation for Mo besides the outer MoSi{sub 2}/SiC composite layer.

  1. In-situ fabrication of MoSi2/SiC–Mo2C gradient anti-oxidation coating on Mo substrate and the crucial effect of Mo2C barrier layer at high temperature

    International Nuclear Information System (INIS)

    Liu, Jun; Gong, Qianming; Shao, Yang; Zhuang, Daming; Liang, Ji

    2014-01-01

    MoSi 2 /SiC–Mo 2 C gradient coating on molybdenum was in situ prepared with pack cementation process by two steps: (1) carburizing with graphite powder to obtain a Mo 2 C layer on Mo substrate, and (2) siliconizing with Si powder to get a composite MoSi 2 /SiC layer on the upper part of Mo 2 C layer. The microstructure and elemental distribution in the coating were investigated with scanning electron microscopy (SEM), backscattered electron (BSE), energy dispersive spectroscopy (EDS), electron probe microanalysis (EPMA) and X-ray diffraction (XRD). Cyclic oxidation tests (at 500 °C, 1200 °C, 1400 °C and 1600 °C) demonstrated excellent oxidation resistance for the gradient composite coating and the mass loss was only 0.23% in 60 min at 1600 °C. XRD, EPMA, thermal dynamic and phase diagram analyses indicated that the Mo 2 C barrier layer played the key role in slowing down the diffusion of C and Si toward inner Mo substrate at high temperature and principally this contributed to the excellent anti-oxidation for Mo besides the outer MoSi 2 /SiC composite layer.

  2. Detection of 14 MeV neutrons in high temperature environment up to 500 deg. C using 4H-SiC based diode detector

    Energy Technology Data Exchange (ETDEWEB)

    Szalkai, D.; Klix, A. [KIT- Karlsruhe Institute of Technology, Institute of Neutron Physics and Reactor Technology Karlsruhe 76344 (Germany); Ferone, R.; Issa, F.; Ottaviani, L.; Vervisch, V. [IM2NP, UMR CNRS 7334, Aix-Marseille University, Case 231 -13397 Marseille Cedex 20 (France); Gehre, D. [Inst. for Nucl.- and Particle-Phys., Dresden University of Technology, Dresden 01069 (Germany); Lyoussi, A. [CEA, DEN, Departement d' Etudes des Reacteurs, Service de Physique Experimentale, Laboratoire Dosimetrie Capteurs Instrumentation, 13108 Saint-Paul-lez-Durance (France)

    2015-07-01

    In reactor technology and industrial applications detection of fast and thermal neutrons plays a crucial role in getting relevant information about the reactor environment and neutron yield. The inevitable elevated temperatures make neutron yield measurements problematic. Out of the currently available semiconductors 4H-SiC seems to be the most suitable neutron detector material under extreme conditions due to its high heat and radiation resistance, large band-gap and lower cost of production than in case of competing diamond detectors. In the framework of the European I-Smart project, optimal {sup 4}H-SiC diode geometries were developed for high temperature neutron detection and have been tested with 14 MeV fast neutrons supplied by a deuterium-tritium neutron generator with an average neutron flux of 10{sup 10}-10{sup 11} n/(s*cm{sup 2}) at Neutron Laboratory of the Technical University of Dresden in Germany from room temperatures up to several hundred degrees Celsius. Based on the results of the diode measurements, detector geometries appear to play a crucial role for high temperature measurements up to 500 deg. C. Experimental set-ups using SiC detectors were constructed to simulate operation in the harsh environmental conditions found in the tritium breeding blanket of the ITER fusion reactor, which is planned to be the location of neutron flux characterization measurements in the near future. (authors)

  3. Energy dispersive X-ray fluorescence from useless tyres samples with a Si PIN detector; Fluorescencia de raios X por dispersao em energia de amostras de pneus inserviveis com detector de Si-PIN

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Fabio; Scheibel, Viviane [Universidade Estadual de Londrina, PR (Brazil). Dept. de Fisica. Lab. de Fisica Nuclear Aplicada]. E-mail: bonn@uel.br; Melquiades, Fabio Luiz [Universidade Estadual do Centro-Oeste, Guarapuava, PR (Brazil). Dept. de Fisica; Moraes, Liz Mary Bueno de [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Lab. de Instrumentacao Nuclear

    2005-07-01

    The concentration of Zn from discard tyre samples is of environmental interest, since on its production are used S for the rubber vulcanization process, and Zn O as reaction catalyze. The useless tyres are been used for asphalt pave, burn in cement industry and thermoelectric power plant and in erosion control of agriculture areas. Analyses of these samples requires frequently chemical digestion that is expensive and take a long time. Trying to eliminate these limitations, the objective of this work was use Energy Dispersive X Ray Fluorescence technique (EDXRF) with a portable system as the technique is multi elementary and needs a minimum sample preparation. Five useless tyres samples were grind in a knife mill and after this in a cryogenic mill, and analyzed in pellets form, using a X ray mini tube (Ag target, Mo {sub l}ter, 25 kV/20 {sub A}) for 200 s and a Si-PIN semiconductor detector coupled to a multichannel analyzer. Were obtained Zn concentrations in the range of 40.6 to 44.2 {sub g} g{sub 1}, representing nearly 0.4. (author)

  4. Energy-dispersive X-ray fluorescence of discarded tire samples, using a Si-PIN detector; Fluorescencia de raios X por dispersao em energia de amostras de pneus inserviveis com detector de Si-Pin

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Fabio; Appoloni, C.R., E-mail: bonn@uel.b [Universidade Estadual de Londrina (UEL), PR (Brazil). Dept. de Fisica. Lab. de Fisica Nuclear Aplicada; Melquiades, Fabio L. [Universidade Estadual do Centro Oeste (UNICENTRO), Guarapuava, PR (Brazil). Dept. de Fisica

    2007-07-01

    The determination of zinc concentration in samples of discarded tires is of great environmental interest because the process for manufacturing tyres uses S for rubber vulcanization, and ZnO is the reaction catalyst. Discarded tyres are being used in asphalt paving, in the burning process of thermoelectric and cement industries and also for controlling erosion in agricultural areas. Analysis of tyre samples usually requires chemical digestion which is slow and expensive. Aiming to eliminate those limitations, this work uses energy-dispersive X-ray fluorescence (EDXRF) with a portable equipment, once it is a simultaneous multi-element analytical technique, requiring minimal sample preparation. Five samples of discarded tyres have been ground and analysed in the form of pastilles, using a mini X-ray tube (Ag target, MO filter, 25 kV/20 muA) for 200 s, and a Si-PIN semiconductor detector coupled to a multichannel analyser. Zinc concentrations in the range of 40.6 to 44.2 mug g{sup -1} have been obtained, representing 0.4% of the tire composition, which is below the maximum value (2%) recommended by the European Tyre Recycling Association. Concentrations between 0.15 and 0.52 mug g{sup -1} were obtained for Fe

  5. Amorphous silicon/crystalline silicon heterojunctions for nuclear radiation detector applications

    International Nuclear Information System (INIS)

    Walton, J.T.; Hong, W.S.; Luke, P.N.; Wang, N.W.; Ziemba, F.P.

    1996-10-01

    Results on characterization of electrical properties of amorphous Si films for the 3 different growth methods (RF sputtering, PECVD [plasma enhanced], LPCVD [low pressure]) are reported. Performance of these a-Si films as heterojunctions on high resistivity p-type and n- type crystalline Si is examined by measuring the noise, leakage current, and the alpha particle response of 5mm dia detector structures. It is demonstrated that heterojunction detectors formed by RF sputtered films and PECVD films are comparable in performance with conventional surface barrier detectors. Results indicate that the a-Si/c-Si heterojunctions have the potential to greatly simplify detector fabrication. Directions for future avenues of nuclear particle detector development are indicated

  6. Defect analysis in low temperature atomic layer deposited Al{sub 2}O{sub 3} and physical vapor deposited SiO barrier films and combination of both to achieve high quality moisture barriers

    Energy Technology Data Exchange (ETDEWEB)

    Maindron, Tony, E-mail: tony.maindron@cea.fr; Jullien, Tony; André, Agathe [Université Grenoble-Alpes, CEA, LETI, MINATEC Campus, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France)

    2016-05-15

    Al{sub 2}O{sub 3} [20 nm, atomic layer deposition (ALD)] and SiO films' [25 nm, physical vacuum deposition (PVD)] single barriers as well as hybrid barriers of the Al{sub 2}O{sub 3}/SiO or SiO/Al{sub 2}O{sub 3} have been deposited onto single 100 nm thick tris-(8-hydroxyquinoline) aluminum (AlQ{sub 3}) organic films made onto silicon wafers. The defects in the different barrier layers could be easily observed as nonfluorescent AlQ{sub 3} black spots, under ultraviolet light on the different systems stored into accelerated aging conditions (85 °C/85% RH, ∼2000 h). It has been observed that all devices containing an Al{sub 2}O{sub 3} layer present a lag time τ from which defect densities of the different systems start to increase significantly. This is coherent with the supposed pinhole-free nature of fresh, ALD-deposited, Al{sub 2}O{sub 3} films. For t > τ, the number of defect grows linearly with storage time. For devices with the single Al{sub 2}O{sub 3} barrier layer, τ has been estimated to be 64 h. For t > τ, the defect occurrence rate has been calculated to be 0.268/cm{sup 2}/h. Then, a total failure of fluorescence of the AlQ{sub 3} film appears between 520 and 670 h, indicating that the Al{sub 2}O{sub 3} barrier has been totally degraded by the hot moisture. Interestingly, the device with the hybrid barrier SiO/Al{sub 2}O{sub 3} shows the same characteristics as the device with the single Al{sub 2}O{sub 3} barrier (τ = 59 h; 0.246/cm{sup 2}/h for t > τ), indicating that Al{sub 2}O{sub 3} ALD is the factor that limits the performance of the barrier system when it is directly exposed to moisture condensation. At the end of the storage period (1410 h), the defect density for the system with the hybrid SiO/Al{sub 2}O{sub 3} barrier is 120/cm{sup 2}. The best sequence has been obtained when Al{sub 2}O{sub 3} is passivated by the SiO layer (Al{sub 2}O{sub 3}/SiO). In that case, a large lag time of 795 h and a very

  7. The MINDView brain PET detector, feasibility study based on SiPM arrays

    Energy Technology Data Exchange (ETDEWEB)

    González, Antonio J., E-mail: agonzalez@i3m.upv.es [Institute for Instrumentation in Molecular Imaging (I3M), 46022 Valencia (Spain); Majewski, Stan [Radiology Research, Department of Radiology, University of Virginia, VA 22903 (United States); Sánchez, Filomeno [Institute for Instrumentation in Molecular Imaging (I3M), 46022 Valencia (Spain); Aussenhofer, Sebastian [NORAS MRI products GmbH, Hochberg (Germany); Aguilar, Albert; Conde, Pablo; Hernández, Liczandro; Vidal, Luis F. [Institute for Instrumentation in Molecular Imaging (I3M), 46022 Valencia (Spain); Pani, Roberto; Bettiol, Marco; Fabbri, Andrea [Department of Molecular Medicine, Sapienza University of Rome (Italy); Bert, Julien; Visvikis, Dimitris [Université de Bretagne Occidentale, Brest (France); Jackson, Carl; Murphy, John; O’Neill, Kevin [SensL Technologies, Cork (Ireland); Benlloch, Jose M. [Institute for Instrumentation in Molecular Imaging (I3M), 46022 Valencia (Spain)

    2016-05-11

    The Multimodal Imaging of Neurological Disorders (MINDView) project aims to develop a dedicated brain Positron Emission Tomography (PET) scanner with sufficient resolution and sensitivity to visualize neurotransmitter pathways and their disruptions in mental disorders for diagnosis and follow-up treatment. The PET system should be compact and fully compatible with a Magnetic Resonance Imaging (MRI) device in order to allow its operation as a PET brain insert in a hybrid imaging setup with most MRI scanners. The proposed design will enable the currently-installed MRI base to be easily upgraded to PET/MRI systems. The current design for the PET insert consists of a 3-ring configuration with 20 modules per ring and an axial field of view of ~15 cm and a geometrical aperture of ~33 cm in diameter. When coupled to the new head Radio Frequency (RF) coil, the inner usable diameter of the complete PET-RF coil insert is reduced to 26 cm. Two scintillator configurations have been tested, namely a 3-layer staggered array of LYSO with 1.5 mm pixel size, with 35×35 elements (6 mm thickness each) and a black-painted monolithic LYSO block also covering about 50×50 mm{sup 2} active area with 20 mm thickness. Laboratory test results associated with the current MINDView PET module concept are presented in terms of key parameters' optimization, such as spatial and energy resolution, sensitivity and Depth of Interaction (DOI) capability. It was possible to resolve all pixel elements from the three scintillator layers with energy resolutions as good as 10%. The monolithic scintillator showed average detector resolutions varying from 3.5 mm in the entrance layer to better than 1.5 mm near the photosensor, with average energy resolutions of about 17%.

  8. Detector characterization and first coincidence tests of a Compton telescope based on LaBr3 crystals and SiPMs

    International Nuclear Information System (INIS)

    Llosá, G.; Barrio, J.; Cabello, J.; Crespo, A.; Lacasta, C.; Rafecas, M.; Callier, S.; La Taille, C. de; Raux, L.

    2012-01-01

    A Compton telescope for dose monitoring in hadron therapy consisting of several layers of continuous LaBr 3 crystals coupled to silicon photomultiplier (SiPM) arrays is under development within the ENVISION project. In order to test the possibility of employing such detectors for the telescope, a detector head consisting of a continuous 16 mm×18 mm×5 mm LaBr 3 crystal coupled to a SiPM array has been assembled and characterized, employing the SPIROC1 ASIC as readout electronics. The best energy resolution obtained at 511 keV is 6.5% FWHM and the timing resolution is 3.1 ns FWHM. A position determination method for continuous crystals is being tested, with promising results. In addition, the detector has been operated in time coincidence with a second detector layer, to determine the coincidence capabilities of the system. The first tests are satisfactory, and encourage the development of larger detectors that will compose the telescope prototype.

  9. Temperature dependent current-voltage characteristics of Au/n-Si Schottky barrier diodes and the effect of transition metal oxides as an interface layer

    Science.gov (United States)

    Mahato, Somnath; Puigdollers, Joaquim

    2018-02-01

    Temperature dependent current-voltage (I‒V) characteristics of Au/n-type silicon (n-Si) Schottky barrier diodes have been investigated. Three transition metal oxides (TMO) are used as an interface layer between gold and silicon. The basic Schottky diode parameters such as ideality factor (n), barrier height (ϕb 0) and series resistance (Rs) are calculated and successfully explained by the thermionic emission (TE) theory. It has been found that ideality factor decreased and barrier height increased with increased of temperature. The conventional Richardson plot of ln(I0/T2) vs. 1000/T is determined the activation energy (Ea) and Richardson constant (A*). Whereas value of 'A*' is much smaller than the known theoretical value of n-type Si. The temperature dependent I-V characteristics obtained the mean value of barrier height (ϕb 0 bar) and standard deviation (σs) from the linear plot of ϕap vs. 1000/T. From the modified Richardson plot of ln(I0/T2) ˗ (qσ)2/2(kT)2 vs. 1000/T gives Richardson constant and homogeneous barrier height of Schottky diodes. Main observation in this present work is the barrier height and ideality factor shows a considerable change but the series resistance value exhibits negligible change due to TMO as an interface layer.

  10. A compact 7-cell Si-drift detector module for high-count rate X-ray spectroscopy.

    Science.gov (United States)

    Hansen, K; Reckleben, C; Diehl, I; Klär, H

    2008-05-01

    A new Si-drift detector module for fast X-ray spectroscopy experiments was developed and realized. The Peltier-cooled module comprises a sensor with 7 × 7-mm 2 active area, an integrated circuit for amplification, shaping and detection, storage, and derandomized readout of signal pulses in parallel, and amplifiers for line driving. The compactness and hexagonal shape of the module with a wrench size of 16mm allow very short distances to the specimen and multi-module arrangements. The power dissipation is 186mW. At a shaper peaking time of 190 ns and an integration time of 450 ns an electronic rms noise of ~11 electrons was achieved. When operated at 7 °C, FWHM line widths around 260 and 460 eV (Cu-K α ) were obtained at low rates and at sum-count rates of 1.7 MHz, respectively. The peak shift is below 1% for a broad range of count rates. At 1.7-MHz sum-count rate the throughput loss amounts to 30%.

  11. Energy-dispersive X-ray fluorescence of discarded tire samples, using a Si-PIN detector

    International Nuclear Information System (INIS)

    Lopes, Fabio; Appoloni, C.R.; Melquiades, Fabio L.

    2007-01-01

    The determination of zinc concentration in samples of discarded tires is of great environmental interest because the process for manufacturing tyres uses S for rubber vulcanization, and ZnO is the reaction catalyst. Discarded tyres are being used in asphalt paving, in the burning process of thermoelectric and cement industries and also for controlling erosion in agricultural areas. Analysis of tyre samples usually requires chemical digestion which is slow and expensive. Aiming to eliminate those limitations, this work uses energy-dispersive X-ray fluorescence (EDXRF) with a portable equipment, once it is a simultaneous multi-element analytical technique, requiring minimal sample preparation. Five samples of discarded tyres have been ground and analysed in the form of pastilles, using a mini X-ray tube (Ag target, MO filter, 25 kV/20 μA) for 200 s, and a Si-PIN semiconductor detector coupled to a multichannel analyser. Zinc concentrations in the range of 40.6 to 44.2 μg g -1 have been obtained, representing 0.4% of the tire composition, which is below the maximum value (2%) recommended by the European Tyre Recycling Association. Concentrations between 0.15 and 0.52 μg g -1 were obtained for Fe

  12. TFTR alpha extraction and measurement: Development and testing of advanced alpha detectors: Final report

    International Nuclear Information System (INIS)

    Wehring, B.W.

    1988-01-01

    Advanced alpha-particle detectors made of heavy elements were investigated as alternatives to silicon surface-barrier detectors for the ''foil-neutralization technique'' of alpha-particle diagnostics in fusion reactors with high neutron backgrounds. From an extensive literature review, it was decided that HgI 2 would make a more suitable detector for alpha-particle diagnostics than other heavy element detectors such as CdTe. Thus, HgI 2 detectors were designed and fabricated. Experimental tests were performed to determine detector characteristics and detector responses to alpha particles. Radiation noise measurements were also performed using the North Carolina State University PULSTAR nuclear reactor for both the HgI 2 detectors and commercial Si(Au) surface barrier detectors. 15 refs., 1 fig

  13. Electric field strength in a silicon surface barrier detector with the presence of a dielectric plasma column

    International Nuclear Information System (INIS)

    Kanno, Ikuo

    1994-01-01

    The dynamic change of the electric field strength in a silicon surface barrier detector (SSBD) is studied. With the presence of a dielectric plasma column in the depletion layer of the SSBD, the electric field strength inside/outside the plasma column is suppressed/enhanced. As the length and the dielectric constant of the plasma column become shorter and smaller, the suppression and enhancement of the electric field strength become less. The electric field strength recovers the initial state, when the plasma column disappears. When the electrons and holes are inside/outside the dielectric plasma column, they have less/more electric potential than the one they have when there is no plasma column. During the movement of the electron/hole outside the plasma column to the positive/negative electrode, the enhanced electric field strength becomes smaller. Electron and hole pairs, which are the parts of the dielectric plasma column, arrive at positive and negative electrodes, having insufficient electric potential to induce the unit charge. This paper shows that the presence of a dielectric plasma column explains the main part of the residual defect in a SSBD. ((orig.))

  14. A novel method to achieve selective emitter for silicon solar cell using low cost pattern-able a-Si thin films as the semi-transparent phosphorus diffusion barrier

    International Nuclear Information System (INIS)

    Chen, Da Ming; Liang, Zong Cun; Zhuang, Lin; Lin, Yang Huan; Shen, Hui

    2012-01-01

    Highlights: ► a-Si thin films as semitransparent phosphorus diffusion barriers for solar cell. ► a-Si thin films on silicon wafers were patterned by the alkaline solution. ► Selective emitter was formed with patterned a-Si as diffusion barrier for solar cell. -- Abstract: Selective emitter for silicon solar cell was realized by employing a-Si thin films as the semi-transparent diffusion barrier. The a-Si thin films with various thicknesses (∼10–40 nm) were deposited by the electron-beam evaporation technique. Emitters with sheet resistances from 37 to 145 Ω/□ were obtained via POCl 3 diffusion process. The thickness of the a-Si diffusion barrier was optimized to be 15 nm for selective emitter in our work. Homemade mask which can dissolve in ethanol was screen-printed on a-Si film to make pattern. The a-Si film was then patterned in KOH solution to form finger-like design. Selective emitter was obtainable with one-step diffusion with patterned a-Si film on. Combinations of sheet resistances for the high-/low-level doped regions of 39.8/112.1, 36.2/88.8, 35.4/73.9 were obtained. These combinations are suitable for screen-printed solar cells. This preparation method of selective emitter based on a-Si diffusion barrier is a promising approach for low cost industrial manufacturing.

  15. Environmental Stability and Oxidation Behavior of HfO2-Si and YbGd(O) Based Environmental Barrier Coating Systems for SiCSiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Farmer, Serene; McCue, Terry R.; Harder, Bryan; Hurst, Janet B.

    2017-01-01

    Ceramic environmental barrier coatings (EBC) and SiCSiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft propulsion systems because of their ability to significantly increase engine operating temperatures, improve component durability, reduce engine weight and cooling requirements. Advanced EBC systems for SiCSiC CMC turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant material development challenges for the high temperature CMC components is to develop prime-reliant, environmental durable environmental barrier coating systems. In this paper, the durability and performance of advanced Electron Beam-Physical Vapor Deposition (EB-PVD) NASA HfO2-Si and YbGdSi(O) EBC bond coat top coat systems for SiCSiC CMC have been summarized. The high temperature thermomechanical creep, fatigue and oxidation resistance have been investigated in the laboratory simulated high-heat-flux environmental test conditions. The advanced NASA EBC systems showed promise to achieve 1500C temperature capability, helping enable next generation turbine engines with significantly improved engine component temperature capability and durability.

  16. Highly sensitive x-ray detectors in the low-energy range on n-type 4H-SiC epitaxial layers

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Krishna C.; Muzykov, Peter G. [Department of Electrical Engineering, University of South Carolina, Columbia, South Carolina 29208 (United States); Russell Terry, J. [Space Science and Applications Group (ISR-1), Intelligence and Space Research Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2012-07-30

    Schottky diodes on n-type 4H-SiC epitaxial layers have been fabricated for low-energy x-ray detection. The detectors were highly sensitive to soft x-rays and showed improved response compared to the commercial SiC UV photodiodes. Current-voltage characteristics at 475 K showed low leakage current revealing the possibility of high temperature operation. The high quality of the epi-layer was confirmed by x-ray diffraction and chemical etching. Thermally stimulated current measurements performed at 94-550 K revealed low density of deep levels which may cause charge trapping. No charge trapping on detectors' responsivity in the low x-ray energy was found.

  17. Efficiency studies for a tracking detector based on square 1.5 m long scintillating fibers read out by SiPM

    International Nuclear Information System (INIS)

    Sanchez Majos, S.; Achenbach, P.; Pochodzalla, J.

    2009-01-01

    A tracking detector based on 1.5 m long scintillating fibers is being developed for the electron arm of the KAOS spectrometer at the Mainz Microtron MAMI. Measurements on light attenuation, particle detection efficiencies and accidental coincidence rates with a prototype set-up using 2x2mm 2 fibers read out by silicon photomultipliers (SiPM) are presented. The highest efficiency at the lowest accidental coincidence rate was reached for high trigger thresholds at the largest SiPM bias voltages. The influence of signal attenuation and dispersion on detection efficiencies is discussed. The results are in good agreement with a Monte Carlo model that was used to predict detector characteristics for different fiber geometries.

  18. Estimation of power dissipation of a 4H-SiC Schottky barrier diode with a linearly graded doping profile in the drift region

    Directory of Open Access Journals (Sweden)

    Rajneesh Talwar

    2009-09-01

    Full Text Available The aim of this paper is to establish the importance of a linearly graded profile in the drift region of a 4H-SiC Schottky barrier diode (SBD. The power dissipation of the device is found to be considerably lower at any given current density as compared to its value obtained for a uniformly doped drift region. The corresponding values of breakdown voltages obtained are similar to those obtained with uniformly doped wafers of 4H-SiC.

  19. Fabrication and characterization of a 32 x 32 array digital Si-PIN X-ray detector for a single photon counting image sensor

    International Nuclear Information System (INIS)

    Seo, Jungho; Kim, Jinyoung; Lim, Hyunwoo; Park, Jingoo; Lee, Songjun; Kim, Bonghoe; Jeon, Sungchae; Huh, Young

    2010-01-01

    A Si-PIN X-ray detector for digital x-ray imaging with single photon counting capability has been fabricated and characterized. It consists of an array of 32 x 32 pixels with an area of 80 x 80 μm 2 . An extrinsic gettering process was performed to reduce the leakage current by removing the impurities and defects from the X-ray detector's Si substrate. Multiple guard-rings (MGRs) and metal filed plates (MFPs) techniques were adopted to reduce the leakage current and to improve the breakdown performance. The simulation verified that the breakdown voltage was improved with the MGRs and that the leakage current was significantly reduced with the MFPs. The electrical properties, such as the leakage current and the breakdown voltage, of the Si-PIN X-ray detector were characterized. The extrinsic gettering process played a significant role in reducing the leakage current, and a leakage current lower than 60 pA could be achieved at 100 V dc .

  20. Comparative Measurements of the Photon Detection Efficiency of KETEK SiPM Detectors for the LHCb SciFi Upgrade Project

    CERN Document Server

    Joram, Christian

    2014-01-01

    The LHCb SciFi detector is conceived to employ arrays of SiPM detectors to detect scintillation light from ribbons of 2.5 m long scintillating fibres of 250 $\\mu$m diameter. The fibres of type Kuraray SCSF-78 are blue emitting with an emission maximum at 440 nm. However, as a consequence of the radiation damage mainly from charged hadrons in the LHCb experiments, the effective emission spectrum at the end of the fibre will shift to longer wavelengths. A simulation of the light absorption in the fibre, assuming an ionizing dose distribution along the fibre as predicted by the FLUKA code, is able to predict the emission spectrum. Fig. 1 shows the emission spectra (in arbitrary units) for 10 cm intervals along the fibre. At 250 cm, where the ionization dose is expected to reach over the full lifetime of the upgrade LHCb detector about 30 kGy, the average wavelength of emission is approximately 500 nm. The sensitivity spectrum of the SiPM detector should be tuned to match this emission spectrum, i.e. the PDE shou...

  1. Response of Ni/4H-SiC Schottky barrier diodes to alpha-particle irradiation at different fluences

    Energy Technology Data Exchange (ETDEWEB)

    Omotoso, E., E-mail: ezekiel.omotoso@up.ac.za [Department of Physics, University of Pretoria, Private Bag X20, Hatfield 0028 (South Africa); Departments of Physics, Obafemi Awolowo University, Ile-Ife 220005 (Nigeria); Meyer, W.E.; Auret, F.D.; Diale, M.; Ngoepe, P.N.M. [Department of Physics, University of Pretoria, Private Bag X20, Hatfield 0028 (South Africa)

    2016-01-01

    Irradiation experiments have been carried out on 1.9×10{sup 16} cm{sup −3} nitrogen-doped 4H-SiC at room temperature using 5.4 MeV alpha-particle irradiation over a fluence ranges from 2.6×10{sup 10} to 9.2×10{sup 11} cm{sup −2}. Current–voltage (I–V), capacitance–voltage (C–V) and deep level transient spectroscopy (DLTS) measurements have been carried out to study the change in characteristics of the devices and free carrier removal rate due to alpha-particle irradiation, respectively. As radiation fluence increases, the ideality factors increased from 1.20 to 1.85 but the Schottky barrier height (SBH{sub I–V}) decreased from 1.47 to 1.34 eV. Free carrier concentration, N{sub d} decreased with increasing fluence from 1.7×10{sup 16} to 1.1×10{sup 16} cm{sup −2} at approximately 0.70 μm depth. The reduction in N{sub d} shows that defects were induced during the irradiation and have effect on compensating the free carrier. The free carrier removal rate was estimated to be 6480±70 cm{sup −1}. Alpha-particle irradiation introduced two electron traps (E{sub 0.39} and E{sub 0.62}), with activation energies of 0.39±0.03 eV and 0.62±0.08 eV, respectively. The E{sub 0.39} as attribute related to silicon or carbon vacancy, while the E{sub 0.62} has the attribute of Z{sub 1}/Z{sub 2}.

  2. New GaN based HEMT with Si3N4 or un-doped region in the barrier for high power applications

    Science.gov (United States)

    Razavi, S. M.; Tahmasb Pour, S.; Najari, P.

    2018-06-01

    New AlGaN/GaN high electron mobility transistors (HEMTs) that their barrier layers under the gate are divided into two regions horizontally are presented in this work. Upper region is Si3N4 (SI-HEMT) or un-doped AlGaN (UN-HEMT) and lower region is AlGaN with heavier doping compared to barrier layer. Upper region in SI-HEMT and UN-HEMT reduces peak electric field in the channel and then improves breakdown voltage considerably. Lower region increases electron density in the two dimensional electron gas (2-DEG) and enhances drain current significantly. For instance, saturated drain current in SI-HEMT is about 100% larger than that in the conventional one. Moreover, the maximum breakdown voltage in the proposed structures is 65 V. This value is about 30% larger than that in the conventional transistor (50 V). Also, suggested structure reduces short channel effect such as DIBL. The maximum gm is obtained in UN-HEMT and conventional devices. Proposed structures improve breakdown voltage and saturated drain current and then enhance maximum output power density. Maximum output power density in the new structures is about 150% higher than that in the conventional.

  3. Digital signal processing for a thermal neutron detector using ZnS(Ag):{sup 6}LiF scintillating layers read out with WLS fibers and SiPMs

    Energy Technology Data Exchange (ETDEWEB)

    Mosset, J.-B., E-mail: jean-baptiste.mosset@psi.ch; Stoykov, A.; Greuter, U.; Hildebrandt, M.; Schlumpf, N.

    2016-07-11

    We present a digital signal processing system based on a photon counting approach which we developed for a thermal neutron detector consisting of ZnS(Ag):{sup 6}LiF scintillating layers read out with WLS fibers and SiPMs. Three digital filters have been evaluated: a moving sum, a moving sum after differentiation and a digital CR-RC{sup 4} filter. The performances of the detector with these filters are presented. A full analog signal processing using a CR-RC{sup 4} filter has been emulated digitally. The detector performance obtained with this analog approach is compared with the one obtained with the best performing digital approach. - Highlights: • Application of digital signal processing for a SiPM-based ZnS:6LiF neutron detector. • Optimisation of detector performances with 3 different digital filters. • Comparison with detector performances with a full analog signal processing.

  4. The use of GaSe semiconductor detectors for monitoring high energy muon beams

    CERN Document Server

    Mancini, A M; Murri, R; Quirini, A; Rizzo, A; Vasanelli, L

    1976-01-01

    GaSe semiconductor detectors have been successfully tested during one year for monitoring muon beams in the GeV range in the neutrino experiment at CERN. Their performances are comparable with those of commercial Si surface barrier detectors for this particular application. Crystal growth, detector fabrication and characterization are briefly described. Various advantages (cost, ruggedness, resistance to radiation damage, manufacturing simplicity, etc.) are discussed. (8 refs).

  5. Response of CR39 detector to 5 A GeV Si14+ ions and measurement of total charge changing cross-section

    International Nuclear Information System (INIS)

    Gupta, Renu; Kumar, Ashavani

    2013-01-01

    In the present work, response of CR39 track etch detector was obtained by cone-height measurement technique. CR39 track etch detector was used to identify the incident charged particles and their fragments by the measurements of cone-height of tracks using an optical microscope DM6000 M and automated image analyzer system installed with Leica QWin Plus software. The CR39 detector was calibrated and the response points were fitted with a linear relation and all the points are within the limits of the experimental errors. The charge resolution of the detector was calculated to be 0.2e. The response function is obtained and fitted with a linear relation which is good throughout Z/β=6.1–14.1. The experimental value of the total charge changing cross-section of 5 A GeV Si 14+ ion beam in polyethylene and CR39 combined target is σ tot =(734±128) mb. The total charge changing cross-section is compared with the experimental results of others based on cone base-area measurement technique and also fitted by the Bradt–Peters geometrical cross-section. - Highlights: • Charge resolution of 0.2e was obtained by cone-height measurement. • Consistency in manual measurements of cone-heights is presented. • Response of CR39 detector was obtained and fitted with first degree polynomial. • Total charge changing cross-section of 5 A GeV Si 14+ ions in CH 2 and CR39 as a combined target was calculated

  6. Characterization of imaging pixel detectors of Si and CdTe read out with the counting X-ray chip MPEC 2.3

    International Nuclear Information System (INIS)

    Loecker, M.

    2007-04-01

    Single photon counting detectors with Si- and CdTe-sensors have been constructed and characterized. As readout chip the MPEC 2.3 is used which consists of 32 x 32 pixels with 200 x 200 μm 2 pixel size and which has a high count rate cabability (1 MHz per pixel) as well as a low noise performance (55 e - ). Measurements and simulations of the detector homogeneity are presented. It could be shown that the theoretical maximum of the homogeneity is reached (quantum limit). By means of the double threshold of the MPEC chip the image contrast can be enhanced which is demonstrated by measurement and simulation. Also, multi-chip-modules consisting of 4 MPEC chips and a single Si- or CdTe-sensor have been constructed and successfully operated. With these modules modulation-transfer-function measurements have been done showing a good spatial resolution of the detectors. In addition, multi-chip-modules according to the Sparse-CMOS concept have been built and tests characterizing the interconnection technologies have been performed

  7. The Development of Environmental Barrier Coating Systems for SiC-SiC Ceramic Matrix Composites: Environment Effects on the Creep and Fatigue Resistance

    Science.gov (United States)

    Zhu, Dongming; Ghosn, Louis J.

    2014-01-01

    Topics covered include: Environmental barrier coating system development: needs, challenges and limitations; Advanced environmental barrier coating systems (EBCs) for CMC airfoils and combustors; NASA EBC systems and material system evolutions, Current turbine and combustor EBC coating emphases, Advanced development, processing, testing and modeling, EBC and EBC bond coats: recent advances; Design tool and life prediction of coated CMC components; Advanced CMC-EBC rig demonstrations; Summary and future directions.

  8. Bonding of Si wafers by surface activation method for the development of high efficiency high counting rate radiation detectors

    International Nuclear Information System (INIS)

    Kanno, Ikuo; Yamashita, Makoto; Onabe, Hideaki

    2006-01-01

    Si wafers with two different resistivities ranging over two orders of magnitude were bonded by the surface activation method. The resistivities of bonded Si wafers were measured as a function of annealing temperature. Using calculations based on a model, the interface resistivities of bonded Si wafers were estimated as a function of the measured resistivities of bonded Si wafers. With thermal treatment from 500degC to 900degC, all interfaces showed high resistivity, with behavior that was close to that of an insulator. Annealing at 1000degC decreased the interface resistivity and showed close to ideal bonding after thermal treatment at 1100degC. (author)

  9. A high granularity scintillator hadronic — calorimeter with SiPM readout for a linear collider detector

    Czech Academy of Sciences Publication Activity Database

    Andreev, V.; Balagura, V.; Bobchenko, B.; Cvach, Jaroslav; Janata, Milan; Kacl, Ivan; Němeček, Stanislav; Polák, Ivo; Valkár, Š.; Weichert, Jan; Zálešák, Jaroslav

    2005-01-01

    Roč. 540, - (2005), s. 368-380 ISSN 0168-9002 R&D Projects: GA MŠk(CZ) LN00A006 Institutional research plan: CEZ:AV0Z10100502 Keywords : linear collider detector * analog calorimeter * semiconductor detectors * scintillator * high granularity Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 1.224, year: 2005

  10. Hybrid Lipid/Polymer Nanoparticles for Pulmonary Delivery of siRNA: Development and Fate Upon In Vitro Deposition on the Human Epithelial Airway Barrier.

    Science.gov (United States)

    d'Angelo, Ivana; Costabile, Gabriella; Durantie, Estelle; Brocca, Paola; Rondelli, Valeria; Russo, Annapina; Russo, Giulia; Miro, Agnese; Quaglia, Fabiana; Petri-Fink, Alke; Rothen-Rutishauser, Barbara; Ungaro, Francesca

    2017-10-16

    Nowadays, the downregulation of genes involved in the pathogenesis of severe lung diseases through local siRNA delivery appears an interesting therapeutic approach. In this study, we propose novel hybrid lipid-polymer nanoparticles (hNPs) consisting of poly(lactic-co-glycolic) acid (PLGA) and dipalmitoyl phosphatidylcholine (DPPC) as siRNA inhalation system. A panel of DPPC/PLGA hNPs was prepared by emulsion/solvent diffusion and fully characterized. A combination of model siRNAs against the sodium transepithelial channel (ENaC) was entrapped in optimized hNPs comprising or not poly(ethylenimine) (PEI) as third component. siRNA-loaded hNPs were characterized for encapsulation efficiency, release kinetics, aerodynamic properties, and stability in artificial mucus (AM). The fate and cytotoxicity of hNPs upon aerosolization on a triple cell co-culture model (TCCC) mimicking human epithelial airway barrier were assessed. Finally, the effect of siRNA-loaded hNPs on ENaC protein expression at 72 hours was evaluated in A549 cells. Optimized muco-inert hNPs encapsulating model siRNA with high efficiency were produced. The developed hNPs displayed a hydrodynamic diameter of ∼150 nm, a low polydispersity index, a negative ζ potential close to -25 mV, and a peculiar triphasic siRNA release lasting for 5 days, which slowed down in the presence of PEI. siRNA formulations showed optimal in vitro aerosol performance after delivery with a vibrating mesh nebulizer. Furthermore, small-angle X-ray scattering analyses highlighted an excellent stability upon incubation with AM, confirming the potential of hNPs for direct aerosolization on mucus-lined airways. Studies in TCCC confirmed that fluorescent hNPs are internalized inside airway epithelial cells and do not exert any cytotoxic or acute proinflammatory effect. Finally, a prolonged inhibition of ENaC protein expression was observed in A549 cells upon treatment with siRNA-loaded hNPs. Results demonstrate the great potential

  11. SiC-based neutron detector in quasi-realistic working conditions: efficiency and stability at room and high temperature under fast neutron irradiations

    Energy Technology Data Exchange (ETDEWEB)

    Ferone, Raffaello; Issa, Fatima; Ottaviani, Laurent; Biondo, Stephane; Vervisch, Vanessa [IM2NP, UMR CNRS 7334, Aix-Marseille University, Case 231,13397 Marseille Cedex 20, (France); Szalkai, Dora; Klix, Axel [KIT- Karlsruhe Institute of Technology, Institute of Neutron Physics and Reactor Technology Karlsruhe 76344, (Germany); Vermeeren, Ludo [SCK-CEN, Boeretang 200, B-2400 Mol, (Belgium); Saenger, Richard [Schlumberger, Clamart, (France); Lyoussi, Abadallah [CEA, DEN, Departement d' Etudes des Reacteurs, Service de Physique Experimentale, Laboratoire Dosimetrie Capteurs Instrumentation, 13108 Saint-Paul-lez-Durance, (France)

    2015-07-01

    In the framework of the European I SMART project, we have designed and made new SiC-based nuclear radiation detectors able to operate in harsh environments and to detect both fast and thermal neutrons. In this paper, we report experimental results of fast neutron irradiation campaign at high temperature (106 deg. C) in quasi-realistic working conditions. Our device does not suffer from high temperature, and spectra do show strong stability, preserving features. These experiments, as well as others in progress, show the I SMART SiC-based device skills to operate in harsh environments, whereas other materials would strongly suffer from degradation. Work is still demanded to test our device at higher temperatures and to enhance efficiency in order to make our device fully exploitable from an industrial point of view. (authors)

  12. Tailoring Lipid and Polymeric Nanoparticles as siRNA Carriers towards the Blood-Brain Barrier - from Targeting to Safe Administration.

    Science.gov (United States)

    Gomes, Maria João; Fernandes, Carlos; Martins, Susana; Borges, Fernanda; Sarmento, Bruno

    2017-03-01

    Blood-brain barrier is a tightly packed layer of endothelial cells surrounding the brain that acts as the main obstacle for drugs enter the central nervous system (CNS), due to its unique features, as tight junctions and drug efflux systems. Therefore, since the incidence of CNS disorders is increasing worldwide, medical therapeutics need to be improved. Consequently, aiming to surpass blood-brain barrier and overcome CNS disabilities, silencing P-glycoprotein as a drug efflux transporter at brain endothelial cells through siRNA is considered a promising approach. For siRNA enzymatic protection and efficient delivery to its target, two different nanoparticles platforms, solid lipid (SLN) and poly-lactic-co-glycolic (PLGA) nanoparticles were used in this study. Polymeric PLGA nanoparticles were around 115 nm in size and had 50 % of siRNA association efficiency, while SLN presented 150 nm and association efficiency close to 52 %. Their surface was functionalized with a peptide-binding transferrin receptor, in a site-oriented manner confirmed by NMR, and their targeting ability against human brain endothelial cells was successfully demonstrated by fluorescence microscopy and flow cytometry. The interaction of modified nanoparticles with brain endothelial cells increased 3-fold compared to non-modified lipid nanoparticles, and 4-fold compared to non-modified PLGA nanoparticles, respectively. These nanosystems, which were also demonstrated to be safe for human brain endothelial cells, without significant cytotoxicity, bring a new hopeful breath to the future of brain diseases therapies.

  13. Use of a silicon surface-barrier detector for measurement of high-energy end loss electrons in a tandem mirror

    International Nuclear Information System (INIS)

    Saito, T.; Kiwamoto, Y.; Honda, T.; Kasugai, A.; Kurihara, K.; Miyoshi, S.

    1991-01-01

    An apparatus for the measurement of high-energy electrons (10--500 keV) with a silicon surface-barrier detector is described. The apparatus has special features. In particular, a fast CAMAC transient digitizer is used to directly record the wave form of a pulse train from the detector and then pulse heights are analyzed with a computer instead of on a conventional pulse height analyzer. With this method the system is capable of detecting electrons with a count rate as high as ∼300--400 kilocounts/s without serious deterioration of performance. Moreover, piled up signals are reliably eliminated from analysis. The system has been applied to measure electron-cyclotron-resonance-heating-induced end loss electrons in the GAMMA 10 tandem mirror and has yielded information relating to electron heating and diffusion in velocity space

  14. SiPM photosensors and fast timing readout for the Barrel Time-of-Flight detector in bar PANDA

    Science.gov (United States)

    Suzuki, K.

    2018-03-01

    The Barrel Time-of-Flight detector system will be installed in the upcoming bar PANDA experiment at FAIR in Germany. The detector has a barrel shape of phi=0.5 m and 1.8 m long, covering about 5 m2, which corresponds to the laboratory polar angle coverage of 22oPANDA Barrel Time-of-Flight detector are presented. The test shows that the current design fulfils satisfactorily the required timing performance (σt~ 56 ps) and the timing performance depends little on the hit position on the surface.

  15. Comparative study between c-Si and CZT semiconducting detectors using the mathematical simulation of the radiation transport through matter

    International Nuclear Information System (INIS)

    Dona, O.; Leyva, A.; Pinera, I.; Abreu, Y.; Cruz, C.

    2007-01-01

    Using the code system MCNP-X, based on the Monte Carlo statistical method, a comparative study of some properties of the crystalline silicon and CZT semiconducting detectors was carried out. This program, conceived to simulate the transport of several types of particles through matter, allowed the study of spatial distribution of the radiation energy deposition in detectors and evaluate the devices quantum efficiency. A quantitative estimation of the number of charge carriers generated in active zone of the detector was also presented. The results of the displacement cross sections calculation and the devices resistance to the radiacional damage are discussed. (Author)

  16. Infrared detectors and focal plane arrays II; Proceedings of the Meeting, Orlando, FL, Apr. 23, 24, 1992

    Science.gov (United States)

    Dereniak, Eustace L.; Sampson, Robert E.

    The present conference discusses Schottky-barrier IR image sensors, SWIR and MWIR Schottky-barrier imagers, a 640 x 640 PtSi, models of nonlinearities in focal plane arrays, retinal function relative to IRT focal plane arrays, a solid-state pyroelectric imager, and electrolyte electroreflectance spectroscopies for the ion-implanted HgCdTe with thermal annealing. Also discussed are HgCdTe hybrid focal plane arrays for thermoelectrically cooled applications, a novel IR detector plasma-edge detector, and IR detector circuits using monolithic CMOS amps with InSb detectors. (No individual items are abstracted in this volume)

  17. Failure behavior of ITO diffusion barrier between electroplating Cu and Si substrate annealed in a low vacuum

    International Nuclear Information System (INIS)

    Hsieh, S.H.; Chien, C.M.; Liu, W.L.; Chen, W.J.

    2009-01-01

    A structure of Cu/ITO(10 nm)/Si was first formed and then annealed at various temperatures for 5 min in a rapid thermal annealing furnace under 10 -2 Torr pressure. In Cu/ITO(10 nm)/Si structure, the ITO(10 nm) film was coated on Si substrate by sputtering process and the Cu film was deposited on ITO film by electroplating technique. The various Cu/ITO(10 nm)/Si samples were characterized by a four-point probe, a scanning electron microscope, an X-ray diffractometer, and a transmission electron microscope. The results showed that when the annealing temperature increases near 600 deg. C the interface between Cu and ITO becomes unstable, and the Cu 3 Si particles begin to form; and when the annealing temperature increases to 650 deg. C, a good many of Cu 3 Si particles about 1 μm in size form and the sheet resistance of Cu/ITO(10 nm)/Si structure largely increases.

  18. Simulation of thermal stresses in SiC-Al2O3 composite tritium penetration barrier by finite-element analysis

    International Nuclear Information System (INIS)

    Liu, Hongbing; Tao, Jie; Gautreau, Yoann; Zhang, Pingze; Xu, Jiang

    2009-01-01

    Tritium penetration barrier (TPB) composed of Al 2 O 3 and SiC on 316L stainless steel was proposed to improve the tritium penetration resistance of the substrate in this work. At the same time, the concept of functionally graded materials (FGM) was applied to manage to decrease residual stresses between Al 2 O 3 and 316L stainless steel substrate due to the mismatch of their thermal expansion coefficients. The effects of system architecture on the residual stresses developed in the composite coatings were investigated numerically by means of finite-element analysis (FEA). Modeling results showed that the presence of the graded properties and the compositions within the coating did reduce the stress discontinuity at the interfaces between the coating and the substrate. Also, the magnitudes of the residual stresses on the coating surface and at the coating/substrate interface were dependent on the Al 2 O 3 and SiC coating thickness.

  19. SEDRX: A computer program for the simulation Si(Li) and Ge(Hp) x-ray detectors efficiency

    International Nuclear Information System (INIS)

    Benamar, M.A.; Benouali, A.; Tchantchane, A.; Azbouche, A.; Tobbeche, S. Centre de Developpement des Techniques Nucleaires, Algiers; Labo. des Techniques Nucleaires)

    1992-12-01

    The difficulties encountered in measuring the x-ray detectors efficiency has motivated to develop a computer program to simulate this parameter. this program computes the efficiency of detectors as a function of energy. the computation of this parameter is based on the fitting coefficients of absorption in the case of photoelectric, coherent and incoherent factors. These coefficients are given by Mc Master library or may be determined by the interpolation based on cubic splines

  20. Performance simulation of an x-ray detector for spectral CT with combined Si and Cd[Zn]Te detection layers.

    Science.gov (United States)

    Herrmann, Christoph; Engel, Klaus-Jürgen; Wiegert, Jens

    2010-12-21

    . The possible choices are, however, quite limited, since only 'mature' materials, which operate at room temperature and can be manufactured reliably should reasonably be considered. Since GaAs is still known to cause reliability problems, the simplest choice is Si, however with the drawback of strong Compton scatter which can cause considerable inter-pixel cross-talk. To investigate the potential and the problems of Si in a multi-layer detector, in this paper the combination of top detector layers made of Si with lower layers made of Cd[Zn]Te is studied by using Monte Carlo simulated detector responses. It is found that the inter-pixel cross-talk due to Compton scatter is indeed very high; however, with an appropriate cross-talk correction scheme, which is also described, the negative effects of cross-talk are shown to be removed to a very large extent.

  1. Fabrication of fully epitaxial magnetic tunnel junctions with a Co2MnSi thin film and a MgO tunnel barrier

    International Nuclear Information System (INIS)

    Kijima, H.; Ishikawa, T.; Marukame, T.; Matsuda, K.-I.; Uemura, T.; Yamamoto, M.

    2007-01-01

    Fully epitaxial magnetic tunnel junctions (MTJs) were fabricated with a Co-based full-Heusler alloy Co 2 MnSi (CMS) thin film having the ordered L2 1 structure as a lower electrode, a MgO tunnel barrier, and a Co 50 Fe 50 upper electrode. Reflection high-energy electron diffraction patterns observed in situ for each layer in the MTJ layer structure during fabrication clearly indicated that all layers of the CMS lower electrode, MgO tunnel barrier, and Co 50 Fe 50 upper electrode grew epitaxially. The microfabricated fully epitaxial CMS/MgO/Co 50 Fe 50 MTJs demonstrated relatively high tunnel magnetoresistance ratios of 90% at room temperature and 192% at 4.2 K

  2. Fischer-Tropsch Performance of an SiO2-Supported Co-Based Catalyst Prepared by Hydrogen Dielectric-Barrier Discharge Plasma

    International Nuclear Information System (INIS)

    Fu Tingjun; Huang Chengdu; Lv Jing; Li Zhenhua

    2014-01-01

    A silica-supported cobalt catalyst was prepared by hydrogen dielectric-barrier discharge (H 2 -DBD) plasma. Compared to thermal hydrogen reduction, H 2 -DBD plasma treatment can not only fully decompose the cobalt precursor but also partially reduce the cobalt oxides at lower temperature and with less time. The effect of the discharge atmosphere on the property of the plasma-prepared catalyst and the Fischer-Tropsch synthesis activity was studied. The results indicate that H 2 -DBD plasma treatment is a promising alternative for preparing Co/SiO 2 catalysts from the viewpoint of energy savings and efficiency

  3. Amorphous silicon/crystalline silicon heterojunctions for nuclear radiation detector applications

    International Nuclear Information System (INIS)

    Walton, J.T.; Hong, W.S.; Luke, P.N.; Wang, N.W.; Ziemba, F.P.

    1996-01-01

    Results on the characterization of the electrical properties of amorphous silicon films for the three different growth methods, RF sputtering, PECVD, and LPCVD are reported. The performance of these a-Si films as heterojunctions on high resistivity p-type and n-type crystalline silicon is examined by measuring the noise, leakage current and the alpha particle response of 5 mm diameter detector structures. It is demonstrated that heterojunction detectors formed by RF sputtered films and PECVD films are comparable in performance with conventional surface barrier detectors. The results indicate that the a-Si/c-Si heterojunctions have the potential to greatly simplify detector fabrication. Directions for future avenues of nuclear particle detector development are indicated

  4. Systematic study of Si-based GeSn photodiodes with 2.6 µm detector cutoff for short-wave infrared detection.

    Science.gov (United States)

    Pham, Thach; Du, Wei; Tran, Huong; Margetis, Joe; Tolle, John; Sun, Greg; Soref, Richard A; Naseem, Hameed A; Li, Baohua; Yu, Shui-Qing

    2016-03-07

    Normal-incidence Ge 1-x Sn x photodiode detectors with Sn compositions of 7 and 10% have been demonstrated. Such detectors were based on Ge/Ge 1-x Sn x /Ge double heterostructures grown directly on a Si substrate via a chemical vapor deposition system. A temperature-dependence study of these detectors was conducted using both electrical and optical characterizations from 300 to 77 K. Spectral response up to 2.6 µm was achieved for a 10% Sn device at room temperature. The peak responsivity and specific detectivity (D*) were measured to be 0.3 A/W and 4 × 10 9 cmHz 1/2 W -1 at 1.55 µm, respectively. The spectral D* of a 7% Sn device at 77 K was only one order-of-magnitude lower than that of an extended-InGaAs photodiode operating in the same wavelength range, indicating the promising future of GeSn-based photodetectors.

  5. Infrared detectors and focal plane arrays; Proceedings of the Meeting, Orlando, FL, Apr. 18, 19, 1990

    Science.gov (United States)

    Dereniak, Eustace L.; Sampson, Robert E.

    1990-09-01

    The papers contained in this volume provide an overview of recent advances and the current state of developments in the field of infrared detectors and focal plane arrays. Topics discussed include nickel silicide Schottky-barrier detectors for short-wavelength infrared applications; high performance PtSi linear and focal plane arrays; and multispectral band Schottky-barrier IRSSD for remote-sensing applications. Papers are also presented on the performance of an Insi hybrid focal array; characterization of IR focal plane test stations; GaAs CCD readout for engineered bandgap detectors; and fire detection system for aircraft cargo bays.

  6. Electric Characteristic Enhancement of an AZO/Si Schottky Barrier Diode with Hydrogen Plasma Surface Treatment and AlxOx Guard Ring Structure

    Directory of Open Access Journals (Sweden)

    Chien-Yu Li

    2018-01-01

    Full Text Available In this study, the design and fabrication of AZO/n-Si Schottky barrier diodes (SBDs with hydrogen plasma treatment on silicon surface and AlxOx guard ring were presented. The Si surface exhibited less interface defects after the cleaning process following with 30 w of H2 plasma treatment that improved the switching properties of the following formed SBDs. The rapid thermal annealing experiment also held at 400 °C to enhance the breakdown voltage of SBDs. The edge effect of the SBDs was also suppressed with the AlxOx guard ring structure deposited by the atomic layer deposition (ALD at the side of the SBDs. Experimental results show that the reverse leakage current was reduced and the breakdown voltage increased with an addition of the AlxOx guard ring. The diode and fabrication technology developed in the study were applicable to the realization of SBDs with a high breakdown voltage (>200 V, a low reverse leakage current density (≤72 μA/mm2@100 V, and a Schottky barrier height of 1.074 eV.

  7. Electric Characteristic Enhancement of an AZO/Si Schottky Barrier Diode with Hydrogen Plasma Surface Treatment and AlxOx Guard Ring Structure

    Science.gov (United States)

    Li, Chien-Yu; Cheng, Min-Yu; Houng, Mau-Phon; Yang, Cheng-Fu; Liu, Jing

    2018-01-01

    In this study, the design and fabrication of AZO/n-Si Schottky barrier diodes (SBDs) with hydrogen plasma treatment on silicon surface and AlxOx guard ring were presented. The Si surface exhibited less interface defects after the cleaning process following with 30 w of H2 plasma treatment that improved the switching properties of the following formed SBDs. The rapid thermal annealing experiment also held at 400 °C to enhance the breakdown voltage of SBDs. The edge effect of the SBDs was also suppressed with the AlxOx guard ring structure deposited by the atomic layer deposition (ALD) at the side of the SBDs. Experimental results show that the reverse leakage current was reduced and the breakdown voltage increased with an addition of the AlxOx guard ring. The diode and fabrication technology developed in the study were applicable to the realization of SBDs with a high breakdown voltage (>200 V), a low reverse leakage current density (≤72 μA/mm2@100 V), and a Schottky barrier height of 1.074 eV. PMID:29316726

  8. Highly conformal SiO2/Al2O3 nanolaminate gas-diffusion barriers for large-area flexible electronics applications

    International Nuclear Information System (INIS)

    Choi, Jin-Hwan; Kim, Young-Min; Park, Young-Wook; Park, Tae-Hyun; Jeong, Jin-Wook; Choi, Hyun-Ju; Song, Eun-Ho; Ju, Byeong-Kwon; Lee, Jin-Woo; Kim, Cheol-Ho

    2010-01-01

    The present study demonstrates a flexible gas-diffusion barrier film, containing an SiO 2 /Al 2 O 3 nanolaminate on a plastic substrate. Highly uniform and conformal coatings can be made by alternating the exposure of a flexible polyethersulfone surface to vapors of SiO 2 and Al 2 O 3 , at nanoscale thickness cycles via RF-magnetron sputtering deposition. The calcium degradation test indicates that 24 cycles of a 10/10 nm inorganic bilayer, top-coated by UV-cured resin, greatly enhance the barrier performance, with a permeation rate of 3.79 x 10 -5 g m -2 day -1 based on the change in the ohmic behavior of the calcium sensor at 20 deg. C and 50% relative humidity. Also, the permeation rate for 30 cycles of an 8/8 nm inorganic bilayer coated with UV resin was beyond the limited measurable range of the Ca test at 60 deg. C and 95% relative humidity. It has been found that such laminate films can effectively suppress the void defects of a single inorganic layer, and are significantly less sensitive against moisture permeation. This nanostructure, fabricated by an RF-sputtering process at room temperature, is verified as being useful for highly water-sensitive organic electronics fabricated on plastic substrates.

  9. On electrical and interfacial properties of iron and platinum Schottky barrier diodes on (111) n-type Si0.65Ge0.35

    Science.gov (United States)

    Hamri, D.; Teffahi, A.; Djeghlouf, A.; Chalabi, D.; Saidane, A.

    2018-04-01

    Current-voltage (I-V), capacitance-voltage-frequency (C-V-f) and conductance-voltage-frequency (G/ω-V-f) characteristics of Molecular Beam Epitaxy (MBE)-deposited Fe/n-Si0.65Ge0.35 (FM1) and Pt/n-Si0.65Ge0.35(PM2) (111) orientated Schottky barrier diodes (SBDs) have been investigated at room-temperature. Barrier height (ΦB0), ideality factor (n) and series resistance (RS) were extracted. Dominant current conduction mechanisms were determined. They revealed that Poole-Frenkel-type conduction mechanism dominated reverse current. Differences in shunt resistance confirmed the difference found in leakage current. Under forward bias, quasi-ohmic conduction is found at low voltage regions and space charge-limited conduction (SCLC) at higher voltage regions for both SBDs. Density of interface states (NSS) indicated a difference in interface reactivity. Distribution profiles of series resistance (RS) with bias gives a peak in depletion region at low-frequencies that disappears with increasing frequencies. These results show that interface states density and series resistance of Schottky diodes are important parameters that strongly influence electrical properties of FM1 and PM2 structures.

  10. The "1"2C("1"6O,γ"2"8Si) radiative capture reaction at sub-barrier energies

    International Nuclear Information System (INIS)

    Goasduff, A.; Courtin, S.; Haas, F.; Lebhertz, D.; Jenkins, D.G.; Fallis, J.; Ruiz, C.; Hutcheon, D.A.; Amandruz, P.A.; Davis, C.; Hager, U.; Ottewell, D.; Ruprecht, G.

    2014-01-01

    The heavy-ion radiative capture "1"2C("1"6O,γ"2"8Si) was measured at the sub-Coulomb barrier bombarding energy E(lab) = 15.7 MeV, which corresponds to the lowest important resonance observed in the "1"2C + "1"6O fusion excitation function. Thanks to combination of the bismuth germanate (BGO) γ-ray array and the 0 degree DRAGON electromagnetic spectrometer at TRIUMF, the γ-decay spectrum from the entrance channel down to the ground state of "2"8Si was measured. Comparisons of the experimental spectrum to γ spectrum extracted from Monte-Carlo simulations of the complete setup suggest a J"π = 2"+ spin-parity assignment to the entrance channel and yield the radiative capture cross section σ(RC) = 0.22 ± 0.04 μb. Combining this present spin assignment with previous data on radiative capture, a J (J + 1) systematics was constructed, and it indicated a moment of inertia commensurate with the "1"2C+"1"6O grazing angular momentum. Strong dipole transitions are observed from the entrance channel to T = 1 states around 11.5 MeV and are found to result from enhanced M1_I_V transitions to states exhausting a large part of the M1 sum rule built on the ground state of "2"8Si. This specific decay was also reported at bombarding energies close to the Coulomb barrier in our previous study of the "1"2C("1"2C,γ"2"4Mg) heavy-ion radiative capture reaction. Similarities between both systems are investigated. (authors)

  11. Development and simulation of a Ge/Si multi-detector spectrometer for fission products traces detection in the environment

    International Nuclear Information System (INIS)

    Cagniant, Antoine

    2015-01-01

    For the verification of the Comprehensive nuclear Test Ban Treaty (CTBT), the measurement of fission products trace levels in the environment is fundamental. Such measurement is a key indicator of a nuclear explosion. For constant amelioration of these measurements, the CEA/DAM-Ile de France has developed and installed a new dedicated surface spectrometer. Named GAMMA3, it is equipped with three germanium detectors, two silicon detectors (integrated in a dedicated gas cell, the PIPSBox) and includes an optimized shielding.This shielding reduces greatly the interference of environmental photons, muons and neutrons with the detectors. The residual radiological background measured inside the shielding is the community's lowest for a surface laboratory. This set of high energy resolution detectors allows the operator to optimize a measurement according to the sample geometry, activity or nature. More precisely, a radioactive noble gas can be measured by photon/electron coincidence, an active sample can be measured by photon/photon coincidence, and a low-active sample can be measured in a high-efficiency configuration. Combining optimized shielding and optimized measurement, Minimum Detectable Activities required for CTBT certification are obtained quickly. Specifically, MDA is reached in 5 hours for 140-Ba (24 mBq), in 6h30 hours for 131m/133m-Xe (5 mBq) and in 7h15 for 133-Xe (5 mBq), when CTBT requirement is in 6 days. (author) [fr

  12. Space charge sign inversion and electric field reconstruction in 24 GeV/c proton-irradiated MCZ Si p+-n(TD)-n+ detectors processed via thermal donor introduction

    International Nuclear Information System (INIS)

    Li, Z.; Verbitskaya, E.; Carini, G.; Chen, W.; Eremin, V.; Gul, R.; Haerkoenen, J.; Li, M.

    2009-01-01

    The aim of this study is the evaluation of radiation effects in detectors based on p-type magnetic czochralski (MCZ) Si that was converted to n-type by thermal donor (TD) introduction. As-processed p + -p-n + detectors were annealed at 430 deg. C resulting in p + -n(TD)-n + structures. The space charge sign and the electric field distribution E(x) in MCz Si p + -n(TD)-n + detectors irradiated by 24 GeV/c protons were analyzed using the data on the current pulse response and the Double Peak (DP) electric field distribution model for heavily irradiated detectors. The approach considers an irradiated detector as a structure with three regions in which the electric field depends on the coordinate, and the induced current pulse response arises from the drift process of free carriers in the detector with variable electric field. Reconstruction of the E(x) profile from the pulse response shapes is performed employing a new method for DP electric field reconstruction. This method includes: (a) a direct extraction of charge loss due to trapping and (b) the fitting of a simulated pulse response to the 'corrected' pulse by adjusting the electric field profiles in the three regions. Reconstruction of E(x) distribution showed that in the diodes irradiated by a proton fluence of (2-4)x10 14 p/cm 2 space charge sign inversion has occurred. This is the evidence that the influence of 24 GeV/c proton radiation on MCz Si p + -n(TD)-n + detectors is similar to that on p + -n-n + detectors based on FZ or diffusion oxygenated n-type Si.

  13. Recrystallization effects of swift heavy {sup 209}Bi ions irradiation on electrical degradation in 4H-SiC Schottky barrier diode

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhimei; Ma, Yao; Gong, Min [Key Laboratory for Microelectronics, College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Key Laboratory of Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Li, Yun [Key Laboratory for Microelectronics, College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Huang, Mingmin [Key Laboratory for Microelectronics, College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Key Laboratory of Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Gao, Bo [Key Laboratory for Microelectronics, College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Zhao, Xin, E-mail: zhaoxin1234@scu.edu.cn [Key Laboratory for Microelectronics, College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China)

    2017-06-15

    In this paper, the phenomenon that the recrystallization effects of swift heavy {sup 209}Bi ions irradiation can partially recovery damage with more than 1 × 10{sup 10} ions/cm{sup 2} is investigated by the degradation of the electrical characteristics of 4H-SiC Schottky barrier diode (SBD) with swift heavy ion irradiation. Deep level transient spectroscopy (DLTS) and Current-Voltage (I-V) measurements clearly indicated that E{sub 0.62} defect induced by swift heavy ion irradiation, which was a recombination center, could result in the increase of reverse leakage current (I{sub R}) at fluence less than 1 × 10{sup 9} ions/cm{sup 2} and the recovery of I{sub R} at fluence more than 1 × 10{sup 10} ions/cm{sup 2} in 4H-SiC SBD. The variation tendency of I{sub R} is consisted with the change of E{sub 0.62} defect. Furthermore, it is reasonable explanation that the damage or defect formed at low fluence in SiC may be recovered by further swift heavy ion irradiation with high fluence, which is due to the melting with the ion tracks of the amorphous zones through a thermal spike and subsequent epitaxial recrystallization initiated from the neighboring crystalline regions.

  14. Effect of a gate buffer layer on the performance of a 4H-SiC Schottky barrier field-effect transistor

    International Nuclear Information System (INIS)

    Zhang Xianjun; Yang Yintang; Chai Changchun; Duan Baoxing; Song Kun; Chen Bin

    2012-01-01

    A lower doped layer is inserted between the gate and channel layer and its effect on the performance of a 4H-SiC Schottky barrier field-effect transistor (MESFET) is investigated. The dependences of the drain current and small signal parameters on this inserted gate-buffer layer are obtained by solving one-dimensional (1-D) and two-dimensional (2-D) Poisson's equations. The drain current and small signal parameters of the 4H-SiC MESFET with a gate-buffer layer thickness of 0.15 μm are calculated and the breakdown characteristics are simulated. The results show that the current is increased by increasing the thickness of the gate-buffer layer; the breakdown voltage is 160 V, compared with 125 V for the conventional 4H-SiC MESFET; the cutoff frequency is 27 GHz, which is higher than 20 GHz of the conventional structure due to the lower doped gate-buffer layer. (semiconductor devices)

  15. 4.0-nm-thick amorphous Nb–Ni film as a conducting diffusion barrier layer for integrating ferroelectric capacitor on Si

    International Nuclear Information System (INIS)

    Dai, X.H.; Guo, J.X.; Zhang, L.; Jia, D.M.; Qi, C.G.; Zhou, Y.; Li, X.H.; Shi, J.B.; Fu, Y.J.; Wang, Y.L.; Lou, J.Z.; Ma, L.X.; Zhao, H.D.; Liu, B.T.

    2015-01-01

    Highlights: • 4-nm-thick amorphous Nb–Ni film is first used as the conducting barrier layer. • No obvious interdiffusion/reaction can be found from the LSCO/PZT/LSCO/Nb–Ni/Si. • The LSCO/PZT/LSCO capacitor, measured at 5 V, possesses very good properties. • Ultrathin amorphous Nb–Ni film is ideal to fabricate silicon-based FRAM. - Abstract: We have successfully integrated La 0.5 Sr 0.5 CoO 3 /PbZr 0.4 Ti 0.6 O 3 /La 0.5 Sr 0.5 CoO 3 (LSCO/PZT/LSCO) capacitors on silicon substrate using a ∼4.0-nm-thick amorphous Nb–Ni film as the conducting diffusion barrier layer. Transmission electron microscopy technique confirms that the Nb–Ni film is still amorphous after fabrication of the capacitors, and the interfaces related to Nb–Ni are clean and sharp without any findable interdiffusion/reaction. The LSCO/PZT/LSCO capacitor, measured at 5 V, possesses very good properties, such as large remanent polarization of ∼22.1 μC/cm 2 , small coercive voltage of ∼1.27 V, good fatigue-resistance, and small pulse width dependence, implying that ultrathin amorphous Nb–Ni film is ideal as the conducting diffusion barrier layer to fabricate high-density silicon-based ferroelectric random access memories

  16. UVSiPM: A light detector instrument based on a SiPM sensor working in single photon counting

    Energy Technology Data Exchange (ETDEWEB)

    Sottile, G.; Russo, F.; Agnetta, G. [Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo, IASF-Pa/INAF, Palermo (Italy); Belluso, M.; Billotta, S. [Osservatorio Astrofisico di Catania, OACT/INAF, Catania (Italy); Biondo, B. [Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo, IASF-Pa/INAF, Palermo (Italy); Bonanno, G. [Osservatorio Astrofisico di Catania, OACT/INAF, Catania (Italy); Catalano, O.; Giarrusso, S. [Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo, IASF-Pa/INAF, Palermo (Italy); Grillo, A. [Osservatorio Astrofisico di Catania, OACT/INAF, Catania (Italy); Impiombato, D.; La Rosa, G.; Maccarone, M.C.; Mangano, A. [Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo, IASF-Pa/INAF, Palermo (Italy); Marano, D. [Osservatorio Astrofisico di Catania, OACT/INAF, Catania (Italy); Mineo, T.; Segreto, A.; Strazzeri, E. [Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo, IASF-Pa/INAF, Palermo (Italy); Timpanaro, M.C. [Osservatorio Astrofisico di Catania, OACT/INAF, Catania (Italy)

    2013-06-15

    UVSiPM is a light detector designed to measure the intensity of electromagnetic radiation in the 320–900 nm wavelength range. It has been developed in the framework of the ASTRI project whose main goal is the design and construction of an end-to-end Small Size class Telescope prototype for the Cherenkov Telescope Array. The UVSiPM instrument is composed by a multipixel Silicon Photo-Multiplier detector unit coupled to an electronic chain working in single photon counting mode with 10 nanosecond double pulse resolution, and by a disk emulator interface card for computer connection. The detector unit of UVSiPM is of the same kind as the ones forming the camera at the focal plane of the ASTRI prototype. Eventually, the UVSiPM instrument can be equipped with a collimator to regulate its angular aperture. UVSiPM, with its peculiar characteristics, will permit to perform several measurements both in lab and on field, allowing the absolute calibration of the ASTRI prototype.

  17. Study of oxide facing at silicone detectors of ionization detectors

    International Nuclear Information System (INIS)

    Kopestansky, J.; Tykva, R.

    1999-01-01

    Formation of oxide facing on silicone in discrete phases of technological preparation of detectors and interaction of gold (aluminium) steamed with SiO x layer were studied. The homogeneity of Au and Si) x layers and interface Au-SiO x and SiO x -Si were examined. The methods SIMS, and partially XPS, AES and RBS were used

  18. Dimensionless parameterization of lidar for laser remote sensing of the atmosphere and its application to systems with SiPM and PMT detectors.

    Science.gov (United States)

    Agishev, Ravil; Comerón, Adolfo; Rodriguez, Alejandro; Sicard, Michaël

    2014-05-20

    In this paper, we show a renewed approach to the generalized methodology for atmospheric lidar assessment, which uses the dimensionless parameterization as a core component. It is based on a series of our previous works where the problem of universal parameterization over many lidar technologies were described and analyzed from different points of view. The modernized dimensionless parameterization concept applied to relatively new silicon photomultiplier detectors (SiPMs) and traditional photomultiplier (PMT) detectors for remote-sensing instruments allowed predicting the lidar receiver performance with sky background available. The renewed approach can be widely used to evaluate a broad range of lidar system capabilities for a variety of lidar remote-sensing applications as well as to serve as a basis for selection of appropriate lidar system parameters for a specific application. Such a modernized methodology provides a generalized, uniform, and objective approach for evaluation of a broad range of lidar types and systems (aerosol, Raman, DIAL) operating on different targets (backscatter or topographic) and under intense sky background conditions. It can be used within the lidar community to compare different lidar instruments.

  19. Magnetic field induced suppression of the forward bias current in Bi2Se3/Si Schottky barrier diodes

    Science.gov (United States)

    Jin, Haoming; Hebard, Arthur

    Schottky diodes formed by van der Waals bonding between freshly cleaved flakes of the topological insulator Bi2Se3 and doped silicon substrates show electrical characteristics in good agreement with thermionic emission theory. The motivation is to use magnetic fields to modulate the conductance of the topologically protected conducting surface state. This surface state in close proximity to the semiconductor surface may play an important role in determining the nature of the Schottky barrier. Current-voltage (I-V) and capacitance-voltage (C-V) characteristics were obtained for temperatures in the range 50-300 K and magnetic fields, both perpendicular and parallel to the interface, as high as 7 T. The I-V curve shows more than 6 decades linearity on semi-logarithmic plots, allowing extraction of parameters such as ideality (η), zero-voltage Schottky barrier height (SBH), and series resistance (Rs). In forward bias we observe a field-induced decrease in current which becomes increasingly more pronounced at higher voltages and lower temperature, and is found to be correlated with changes in Rs rather than other barrier parameters. A comparison of changes in Rs in both field direction will be made with magnetoresistance in Bi2Se3 transport measurement. The work is supported by NSF through DMR 1305783.

  20. A SiPM-based isotropic-3D PET detector X'tal cube with a three-dimensional array of 1 mm{sup 3} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Yamaya, Taiga; Mitsuhashi, Takayuki; Inadama, Naoko; Nishikido, Fumihiko; Yoshida, Eiji; Murayama, Hideo [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Matsumoto, Takahiro; Kawai, Hideyuki; Suga, Mikio [Chiba University, 1-33 Yayoicho, Inage-ku, Chiba 263-8522 (Japan); Watanabe, Mitsuo, E-mail: taiga@nirs.go.jp [Central Research Laboratory, Hamamatsu Photonics K.K., 5000 Hirakuchi, Hamakita-ku, Hamamatsu 434-8601 (Japan)

    2011-11-07

    We are developing a novel, general purpose isotropic-3D PET detector X'tal cube which has high spatial resolution in all three dimensions. The research challenge for this detector is implementing effective detection of scintillation photons by covering six faces of a segmented crystal block with silicon photomultipliers (SiPMs). In this paper, we developed the second prototype of the X'tal cube for a proof-of-concept. We aimed at realizing an ultimate detector with 1.0 mm{sup 3} cubic crystals, in contrast to our previous development using 3.0 mm{sup 3} cubic crystals. The crystal block was composed of a 16 x 16 x 16 array of lutetium gadolinium oxyorthosilicate (LGSO) crystals 0.993 x 0.993 x 0.993 mm{sup 3} in size. The crystals were optically glued together without inserting any reflector inside and 96 multi-pixel photon counters (MPPCs, S10931-50P, i.e. six faces each with a 4 x 4 array of MPPCs), each having a sensitive area of 3.0 x 3.0 mm{sup 2}, were optically coupled to the surfaces of the crystal block. Almost all 4096 crystals were identified through Anger-type calculation due to the finely adjusted reflector sheets inserted between the crystal block and light guides. The reflector sheets, which formed a belt of 0.5 mm width, were placed to cover half of the crystals of the second rows from the edges in order to improve identification performance of the crystals near the edges. Energy resolution of 12.7% was obtained at 511 keV with almost uniform light output for all crystal segments thanks to the effective detection of the scintillation photons.

  1. High performance SiC detectors for MeV ion beamsgenerated by intense pulsed laser plasmas

    Czech Academy of Sciences Publication Activity Database

    Cutroneo, M.; Musumeci, P.; Zimbone, M.; Torrisi, L.; La Via, F.; Margarone, Daniele; Velyhan, Andriy; Ullschmied, Jiří; Calcagno, L.

    2013-01-01

    Roč. 28, č. 1 (2013), s. 87-93 ISSN 0884-2914 R&D Projects: GA MŠk ED1.1.00/02.0061; GA MŠk EE.2.3.20.0087 Grant - others:ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; OP VK 2 LaserGen(XE) CZ.1.07/2.3.00/20.0087 Institutional support: RVO:68378271 ; RVO:61389021 Keywords : silicon carbide * ion detectors * high power laser Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.815, year: 2013

  2. Frequency Dependent Electrical and Dielectric Properties of Au/P3HT:PCBM:F4-TCNQ/n-Si Schottky Barrier Diode

    Science.gov (United States)

    Taşçıoğlu, İ.; Tüzün Özmen, Ö.; Şağban, H. M.; Yağlıoğlu, E.; Altındal, Ş.

    2017-04-01

    In this study, poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester: 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (P3HT:PCBM:F4-TCNQ) organic film was deposited on n-type silicon (n-Si) substrate by spin coating method. The electrical and dielectric analysis of Au/P3HT:PCBM:F4-TCNQ/n-Si Schottky barrier diode was conducted by means of capacitance-voltage ( C- V) and conductance-voltage ( G/ ω- V) measurements in the frequency range of 10 kHz-2 MHz. The C- V- f plots exhibit fairly large frequency dispersion due to excess capacitance caused by the presence of interface states ( N ss). The values of N ss located in semiconductor bandgap at the organic film/semiconductor interface were calculated by Hill-Coleman method. Experimental results show that dielectric constant ( ɛ') and dielectric loss ( ɛ″) decrease with increasing frequency, whereas loss tangent (tan δ) remains nearly the same. The decrease in ɛ' and ɛ″ was interpreted by the theory of dielectric relaxation due to interfacial polarization. It is also observed that ac electrical conductivity ( σ ac) and electric modulus ( M' and M″) increase with increasing frequency.

  3. Role of SiNx Barrier Layer on the Performances of Polyimide Ga2O3-doped ZnO p-i-n Hydrogenated Amorphous Silicon Thin Film Solar Cells

    Science.gov (United States)

    Wang, Fang-Hsing; Kuo, Hsin-Hui; Yang, Cheng-Fu; Liu, Min-Chu

    2014-01-01

    In this study, silicon nitride (SiNx) thin films were deposited on polyimide (PI) substrates as barrier layers by a plasma enhanced chemical vapor deposition (PECVD) system. The gallium-doped zinc oxide (GZO) thin films were deposited on PI and SiNx/PI substrates at room temperature (RT), 100 and 200 °C by radio frequency (RF) magnetron sputtering. The thicknesses of the GZO and SiNx thin films were controlled at around 160 ± 12 nm and 150 ± 10 nm, respectively. The optimal deposition parameters for the SiNx thin films were a working pressure of 800 × 10−3 Torr, a deposition power of 20 W, a deposition temperature of 200 °C, and gas flowing rates of SiH4 = 20 sccm and NH3 = 210 sccm, respectively. For the GZO/PI and GZO-SiNx/PI structures we had found that the GZO thin films deposited at 100 and 200 °C had higher crystallinity, higher electron mobility, larger carrier concentration, smaller resistivity, and higher optical transmittance ratio. For that, the GZO thin films deposited at 100 and 200 °C on PI and SiNx/PI substrates with thickness of ~000 nm were used to fabricate p-i-n hydrogenated amorphous silicon (α-Si) thin film solar cells. 0.5% HCl solution was used to etch the surfaces of the GZO/PI and GZO-SiNx/PI substrates. Finally, PECVD system was used to deposit α-Si thin film onto the etched surfaces of the GZO/PI and GZO-SiNx/PI substrates to fabricate α-Si thin film solar cells, and the solar cells’ properties were also investigated. We had found that substrates to get the optimally solar cells’ efficiency were 200 °C-deposited GZO-SiNx/PI. PMID:28788494

  4. Role of SiNx Barrier Layer on the Performances of Polyimide Ga2O3-doped ZnO p-i-n Hydrogenated Amorphous Silicon Thin Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Fang-Hsing Wang

    2014-02-01

    Full Text Available In this study, silicon nitride (SiNx thin films were deposited on polyimide (PI substrates as barrier layers by a plasma enhanced chemical vapor deposition (PECVD system. The gallium-doped zinc oxide (GZO thin films were deposited on PI and SiNx/PI substrates at room temperature (RT, 100 and 200 °C by radio frequency (RF magnetron sputtering. The thicknesses of the GZO and SiNx thin films were controlled at around 160 ± 12 nm and 150 ± 10 nm, respectively. The optimal deposition parameters for the SiNx thin films were a working pressure of 800 × 10−3 Torr, a deposition power of 20 W, a deposition temperature of 200 °C, and gas flowing rates of SiH4 = 20 sccm and NH3 = 210 sccm, respectively. For the GZO/PI and GZO-SiNx/PI structures we had found that the GZO thin films deposited at 100 and 200 °C had higher crystallinity, higher electron mobility, larger carrier concentration, smaller resistivity, and higher optical transmittance ratio. For that, the GZO thin films deposited at 100 and 200 °C on PI and SiNx/PI substrates with thickness of ~1000 nm were used to fabricate p-i-n hydrogenated amorphous silicon (α-Si thin film solar cells. 0.5% HCl solution was used to etch the surfaces of the GZO/PI and GZO-SiNx/PI substrates. Finally, PECVD system was used to deposit α-Si thin film onto the etched surfaces of the GZO/PI and GZO-SiNx/PI substrates to fabricate α-Si thin film solar cells, and the solar cells’ properties were also investigated. We had found that substrates to get the optimally solar cells’ efficiency were 200 °C-deposited GZO-SiNx/PI.

  5. 4.0-nm-thick amorphous Nb–Ni film as a conducting diffusion barrier layer for integrating ferroelectric capacitor on Si

    Energy Technology Data Exchange (ETDEWEB)

    Dai, X.H. [Hebei Key Lab of Optic-electronic Information and Materials, College of Physics Science & Technology, Hebei University, Hebei 071002 (China); College of Electronic and Information Engineering, Hebei University of Technology, Tianjin 300401 (China); Guo, J.X.; Zhang, L.; Jia, D.M.; Qi, C.G.; Zhou, Y.; Li, X.H.; Shi, J.B.; Fu, Y.J.; Wang, Y.L.; Lou, J.Z. [Hebei Key Lab of Optic-electronic Information and Materials, College of Physics Science & Technology, Hebei University, Hebei 071002 (China); Ma, L.X. [Department of Physics, Blinn College, Bryan, TX 77805 (United States); Zhao, H.D. [College of Electronic and Information Engineering, Hebei University of Technology, Tianjin 300401 (China); Liu, B.T., E-mail: btliu@hbu.cn [Hebei Key Lab of Optic-electronic Information and Materials, College of Physics Science & Technology, Hebei University, Hebei 071002 (China)

    2015-10-05

    Highlights: • 4-nm-thick amorphous Nb–Ni film is first used as the conducting barrier layer. • No obvious interdiffusion/reaction can be found from the LSCO/PZT/LSCO/Nb–Ni/Si. • The LSCO/PZT/LSCO capacitor, measured at 5 V, possesses very good properties. • Ultrathin amorphous Nb–Ni film is ideal to fabricate silicon-based FRAM. - Abstract: We have successfully integrated La{sub 0.5}Sr{sub 0.5}CoO{sub 3}/PbZr{sub 0.4}Ti{sub 0.6}O{sub 3}/La{sub 0.5}Sr{sub 0.5}CoO{sub 3} (LSCO/PZT/LSCO) capacitors on silicon substrate using a ∼4.0-nm-thick amorphous Nb–Ni film as the conducting diffusion barrier layer. Transmission electron microscopy technique confirms that the Nb–Ni film is still amorphous after fabrication of the capacitors, and the interfaces related to Nb–Ni are clean and sharp without any findable interdiffusion/reaction. The LSCO/PZT/LSCO capacitor, measured at 5 V, possesses very good properties, such as large remanent polarization of ∼22.1 μC/cm{sup 2}, small coercive voltage of ∼1.27 V, good fatigue-resistance, and small pulse width dependence, implying that ultrathin amorphous Nb–Ni film is ideal as the conducting diffusion barrier layer to fabricate high-density silicon-based ferroelectric random access memories.

  6. Atomic layer deposition α-Al2O3 diffusion barriers to eliminate the memory effect in beta-gamma radioxenon detectors

    International Nuclear Information System (INIS)

    Warburton, W.K.; Wolfgang Hennig; Bertrand, J.A.; George, S.M.; Steven Biegalski

    2013-01-01

    Well designed scintillator detectors, including such examples as ARSA, SAUNA, and XIA's 'PhosWatch', can readily achieve the state of the art radioxenon detection limits required for nuclear explosion monitoring. They are also reliable, robust detectors that do not require cryogenic cooling for operation. All three employ the principle of beta-gamma coincidence detection to reduce background counting rates, using a BC-404 plastic scintillator to detect the betas and a CsI or NaI scintillator to detect the gamma-rays. As a consequence of this commonality of design, all three also display a 'memory effect' arising from the diffusion of Xe into BC-404. Thus, when one sample is pumped out of the detector, a fraction remains behind, embedded in the BC-404, where it artificially raises the signal counting rate for the next sample. While this is not a fatal flaw in scintillator detectors, developing a method to eliminate the memory effect would significantly enhance their utility. This paper reports efforts to develop thin, amorphous Al 2 O 3 films, deposited by atomic layer deposition (ALD) to act as diffusion barriers on the BC-404 surfaces exposed to radioxenon. Using radon as a convenient substitute for Xe, film thicknesses between 2 and 10 nm were originally investigated and found to show a memory effect to varying degrees. A second set of 20 and 30 nm films was then produced, which appeared to completely eliminate the radon memory effect, but, when consequentially tested with radioxenon, were found to exhibit xenon memory effects that were approximately half of the effect found on uncoated BC-404. We draw two conclusions from this result. The first is that it will be necessary to develop an improved method for depositing thicker ALD Al 2 O 3 films at lower temperatures while still retaining high film quality. The second is that, since xenon is required to test for the xenon memory effect, we need a test method that does not require xenon radio-isotopes in order to

  7. Processing of n{sup +}/p{sup −}/p{sup +} strip detectors with atomic layer deposition (ALD) grown Al{sub 2}O{sub 3} field insulator on magnetic Czochralski silicon (MCz-si) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Härkönen, J., E-mail: jaakko.harkonen@helsinki.fi [Helsinki Institute of Physics (Finland); Tuovinen, E. [Helsinki Institute of Physics (Finland); VTT Technical Research Centre of Finland, Microsystems and Nanoelectronics (Finland); Luukka, P.; Gädda, A.; Mäenpää, T.; Tuominen, E.; Arsenovich, T. [Helsinki Institute of Physics (Finland); Junkes, A. [Institute for Experimental Physics, University of Hamburg (Germany); Wu, X. [VTT Technical Research Centre of Finland, Microsystems and Nanoelectronics (Finland); Picosun Oy, Tietotie 3, FI-02150 Espoo Finland (Finland); Li, Z. [School of Materials Science and Engineering, Xiangtan University, Xiangtan, Hunan 411105 (China)

    2016-08-21

    Detectors manufactured on p-type silicon material are known to have significant advantages in very harsh radiation environment over n-type detectors, traditionally used in High Energy Physics experiments for particle tracking. In p-type (n{sup +} segmentation on p substrate) position-sensitive strip detectors, however, the fixed oxide charge in the silicon dioxide is positive and, thus, causes electron accumulation at the Si/SiO{sub 2} interface. As a result, unless appropriate interstrip isolation is applied, the n-type strips are short-circuited. Widely adopted methods to terminate surface electron accumulation are segmented p-stop or p-spray field implantations. A different approach to overcome the near-surface electron accumulation at the interface of silicon dioxide and p-type silicon is to deposit a thin film field insulator with negative oxide charge. We have processed silicon strip detectors on p-type Magnetic Czochralski silicon (MCz-Si) substrates with aluminum oxide (Al{sub 2}O{sub 3}) thin film insulator, grown with Atomic Layer Deposition (ALD) method. The electrical characterization by current–voltage and capacitance−voltage measurement shows reliable performance of the aluminum oxide. The final proof of concept was obtained at the test beam with 200 GeV/c muons. For the non-irradiated detector the charge collection efficiency (CCE) was nearly 100% with a signal-to-noise ratio (S/N) of about 40, whereas for the 2×10{sup 15} n{sub eq}/cm{sup 2} proton irradiated detector the CCE was 35%, when the sensor was biased at 500 V. These results are comparable with the results from p-type detectors with the p-spray and p-stop interstrip isolation techniques. In addition, interestingly, when the aluminum oxide was irradiated with Co-60 gamma-rays, an accumulation of negative fixed oxide charge in the oxide was observed.

  8. MSM-Metal Semiconductor Metal Photo-detector Using Black Silicon Germanium (SiGe) for Extended Wavelength Near Infrared Detection

    Science.gov (United States)

    2012-09-01

    its effect on the optical beam. Computer Tunable optical source Detectors Test MSM detector Lock-in- amplifier Multiplexer Transimpedance ... amplifier Three-way beam splitter L3 sample L1 Light source L4 L2 Reference Detector Reflectance Detector

  9. Temperature and voltage dependence of barrier height and ideality factor in Au/0.07 graphene-doped PVA/n-Si structures

    Science.gov (United States)

    Altındal Yerişkin, S.; Balbaşı, M.; Demirezen, S.

    2017-04-01

    In this study, Au/0.07 graphene-doped PVA/n-Si structures were fabricated and current conduction mechanism in these structures were investigated in the temperature range of 80-380 K through forward bias current-voltage ( I- V) measurements. Main electrical parameters were extracted from I-V data. Zero-bias barrier height (\\overline{Φ}_{B0}) and ideality factor (n) were found strong functions of temperature and their values ranged from 0.234 eV and 4.98 (at 80 K) to 0.882 eV and 1.15 (at 380 K), respectively. Φ ap versus q/2k T plot was drawn to obtain an evidence of a Gaussian distribution of the barrier heights (BHs) and it revealed two distinct linear regions with different slopes and intercepts. The mean values of BH ( Φ Bo) and zero-bias standard deviation (σ s ) were obtained from the intercept and slope of the linear regions of this plot as 1.30 eV and 0.16 V for the first region (280-380 K) and 0.74 eV and 0.085 V for the second region (80-240 K), respectively. Thus, the values of \\overline{Φ}_{B0} and effective Richardson constant ( A*) were also found from the intercept and slope of the modified Richardson plot [ln( I s /T 2) - q 2 σ o 2 /2k 2 T 2 vs q/ kT] as 1.31 eV and 130 A/cm2 K2 for the first region and 0.76 eV and 922 A/cm2 K2 for the second region, respectively. The value of A* for the first region was very close to the theoretical value for n-Si (112 A/cm2 K2). The energy density distribution profile of surface states (Nss) was also extracted from the forward bias I-V data by taking into account voltage dependent effective BH (Φe) and n.

  10. Measurements of Ultra-Fast single photon counting chip with energy window and 75 μm pixel pitch with Si and CdTe detectors

    International Nuclear Information System (INIS)

    Maj, P.; Grybos, P.; Kasinski, K.; Koziol, A.; Krzyzanowska, A.; Kmon, P.; Szczygiel, R.; Zoladz, M.

    2017-01-01

    Single photon counting pixel detectors become increasingly popular in various 2-D X-ray imaging techniques and scientific experiments mainly in solid state physics, material science and medicine. This paper presents architecture and measurement results of the UFXC32k chip designed in a CMOS 130 nm process. The chip consists of about 50 million transistors and has an area of 9.64 mm × 20.15 mm. The core of the IC is a matrix of 128 × 256 pixels of 75 μm pitch. Each pixel contains a CSA, a shaper with tunable gain, two discriminators with correction circuits and two 14-bit ripple counters operating in a normal mode (with energy window), a long counter mode (one 28-bit counter) and a zero-dead time mode. Gain and noise performance were verified with X-ray radiation and with the chip connected to Si (320 μm thick) and CdTe (750 μ m thick) sensors.

  11. Investigation of enzyme-sensitive lipid nanoparticles for delivery of siRNA to blood–brain barrier and glioma cells

    Directory of Open Access Journals (Sweden)

    Bruun J

    2015-09-01

    Full Text Available Jonas Bruun,1 Trine B Larsen,1 Rasmus I Jølck,1 Rasmus Eliasen,1 René Holm,2 Torben Gjetting,1 Thomas L Andresen11Department of Micro- and Nanotechnology, Center for Nanomedicine and Theranostics, Technical University of Denmark, DTU Nanotech, Lyngby, Denmark; 2H Lundbeck A/S, Biologics and Pharmaceutical Science, Valby, DenmarkAbstract: Clinical applications of siRNA for treating disorders in the central nervous system require development of systemic stable, safe, and effective delivery vehicles that are able to cross the impermeable blood–brain barrier (BBB. Engineering nanocarriers with low cellular interaction during systemic circulation, but with high uptake in targeted cells, is a great challenge and is further complicated by the BBB. As a first step in obtaining such a delivery system, this study aims at designing a lipid nanoparticle (LNP able to efficiently encapsulate siRNA by a combination of titratable cationic lipids. The targeted delivery is obtained through the design of a two-stage system where the first step is conjugation of angiopep to the surface of the LNP for targeting the low-density lipoprotein receptor-related protein-1 expressed on the BBB. Second, the positively charged LNPs are masked with a negatively charged PEGylated (poly(ethylene glycol cleavable lipopeptide, which contains a recognition sequence for matrix metalloproteinases (MMPs, a class of enzymes often expressed in the tumor microenvironment and inflammatory BBB conditions. Proteolytic cleavage induces PEG release, including the release of four glutamic acid residues, providing a charge switch that triggers a shift of the LNP charge from weakly negative to positive, thus favoring cellular endocytosis and release of siRNA for high silencing efficiency. This work describes the development of this two-stage nanocarrier-system and evaluates the performance in brain endothelial and glioblastoma cells with respect to uptake and gene silencing efficiency. The

  12. Validation of an analytical method for simultaneous high-precision measurements of greenhouse gas emissions from wastewater treatment plants using a gas chromatography-barrier discharge detector system.

    Science.gov (United States)

    Pascale, Raffaella; Caivano, Marianna; Buchicchio, Alessandro; Mancini, Ignazio M; Bianco, Giuliana; Caniani, Donatella

    2017-01-13

    Wastewater treatment plants (WWTPs) emit CO 2 and N 2 O, which may lead to climate change and global warming. Over the last few years, awareness of greenhouse gas (GHG) emissions from WWTPs has increased. Moreover, the development of valid, reliable, and high-throughput analytical methods for simultaneous gas analysis is an essential requirement for environmental applications. In the present study, an analytical method based on a gas chromatograph (GC) equipped with a barrier ionization discharge (BID) detector was developed for the first time. This new method simultaneously analyses CO 2 and N 2 O and has a precision, measured in terms of relative standard of variation RSD%, equal to or less than 6.6% and 5.1%, respectively. The method's detection limits are 5.3ppm v for CO 2 and 62.0ppb v for N 2 O. The method's selectivity, linearity, accuracy, repeatability, intermediate precision, limit of detection and limit of quantification were good at trace concentration levels. After validation, the method was applied to a real case of N 2 O and CO 2 emissions from a WWTP, confirming its suitability as a standard procedure for simultaneous GHG analysis in environmental samples containing CO 2 levels less than 12,000mg/L. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Detectors - Electronics

    International Nuclear Information System (INIS)

    Bregeault, J.; Gabriel, J.L.; Hierle, G.; Lebotlan, P.; Leconte, A.; Lelandais, J.; Mosrin, P.; Munsch, P.; Saur, H.; Tillier, J.

    1998-01-01

    The reports presents the main results obtained in the fields of radiation detectors and associated electronics. In the domain of X-ray gas detectors for the keV range efforts were undertaken to rise the detector efficiency. Multiple gap parallel plate chambers of different types as well as different types of X → e - converters were tested to improve the efficiency (values of 2.4% at 60 KeV were reached). In the field of scintillators a study of new crystals has been carried out (among which Lutetium orthosilicate). CdTe diode strips for obtaining X-ray imaging were studied. The complete study of a linear array of 8 CdTe pixels has been performed and certified. The results are encouraging and point to this method as a satisfying solution. Also, a large dimension programmable chamber was used to study the influence of temperature on the inorganic scintillators in an interval from -40 deg. C to +150 deg. C. Temperature effects on other detectors and electronic circuits were also investigated. In the report mentioned is also the work carried out for the realization of the DEMON neutron multidetector. For neutron halo experiments different large area Si detectors associated with solid and gas position detectors were realized. In the frame of a contract with COGEMA a systematic study of Li doped glasses was undertaken aiming at replacing with a neutron probe the 3 He counters presently utilized in pollution monitoring. An industrial prototype has been realised. Other studies were related to integrated analog chains, materials for Cherenkov detectors, scintillation probes for experiments on fundamental processes, gas position sensitive detectors, etc. In the field of associated electronics there are mentioned the works related to the multidetector INDRA, data acquisition, software gamma spectrometry, automatic gas pressure regulation in detectors, etc

  14. MUST detector

    International Nuclear Information System (INIS)

    Blumenfeld, Y.; Auger, F.; Sauvestre, J.E.

    1999-01-01

    The IPN-Orsay, in collaboration with the SPhN-Saclay and the DPTA Bruyeres, has built an array of 8 telescopes based on Si-strip technology for the study of direct reactions induced by radioactive beams. The detectors are described, along with the compact high density VXI electronics and the stand-alone data acquisition system developed in the laboratory. One telescope was tested using an 40 Ar beam and the measured performances are discussed. (authors)

  15. Silicon carbide and its use as a radiation detector material

    International Nuclear Information System (INIS)

    Nava, F; Bertuccio, G; Cavallini, A; Vittone, E

    2008-01-01

    We present a comprehensive review of the properties of the epitaxial 4H silicon carbide polytype (4H–SiC). Particular emphasis is placed on those aspects of this material related to room, high-temperature and harsh environment ionizing radiation detector operation. A review of the characterization methods and electrical contacting issues and how these are related to detector performance is presented. The most recent data on charge transport parameters across the Schottky barrier and how these are related to radiation spectrometer performance are presented. Experimental results on pixel detectors having equivalent noise energies of 144 eV FWHM (7.8 electrons rms) and 196 eV FWHM at +27 °C and +100 °C, respectively, are reported. Results of studying the radiation resistance of 4H–SiC are analysed. The data on the ionization energies, capture cross section, deep-level centre concentrations and their plausible structures formed in SiC as a result of irradiation with various particles are reviewed. The emphasis is placed on the study of the 1 MeV neutron irradiation, since these thermal particles seem to play the main role in the detector degradation. An accurate electrical characterization of the induced deep-level centres by means of PICTS technique has allowed one to identify which play the main role in the detector degradation. (topical review)

  16. Fixed interface charges between AlGaN barrier and gate stack composed of in situ grown SiN and Al2O3 in AlGaN/GaN high electron mobility transistors with normally off capability

    International Nuclear Information System (INIS)

    Capriotti, M.; Alexewicz, A.; Fleury, C.; Gavagnin, M.; Bethge, O.; Wanzenböck, H. D.; Bertagnolli, E.; Pogany, D.; Strasser, G.; Visalli, D.; Derluyn, J.

    2014-01-01

    Using a generalized extraction method, the fixed charge density N int at the interface between in situ deposited SiN and 5 nm thick AlGaN barrier is evaluated by measurements of threshold voltage V th of an AlGaN/GaN metal insulator semiconductor high electron mobility transistor as a function of SiN thickness. The thickness of the originally deposited 50 nm thick SiN layer is reduced by dry etching. The extracted N int is in the order of the AlGaN polarization charge density. The total removal of the in situ SiN cap leads to a complete depletion of the channel region resulting in V th  = +1 V. Fabrication of a gate stack with Al 2 O 3 as a second cap layer, deposited on top of the in situ SiN, is not introducing additional fixed charges at the SiN/Al 2 O 3 interface

  17. SiD Letter of Intent

    CERN Document Server

    Aihara, H.; Oreglia, M.; Berger, E.L.; Guarino, V.; Repond, J.; Weerts, H.; Xia, L.; Zhang, J.; Zhang, Q.; Srivastava, A.; Butler, J.M.; Goldstein, Joel; Velthuis, J.; Radeka, V.; Zhu, R.-Y.; Lutz, P.; de Roeck, A.; Elsener, K.; Gaddi, A.; Gerwig, H.; Grefe, C.; Klempt, W.; Linssen, L.; Schlatter, D.; Speckmayer, P.; Thom, J.; Yang, J.; Christian, D.C.; Cihangir, S.; Cooper, W.E.; Demarteau, M.; Fisk, H.E.; Garren, L.A.; Krempetz, K.; Kutschke, R.K.; Lipton, R.; Para, A.; Tschirhart, R.; Wenzel, H.; Yarema, R.; Grunewald, M.; Pankov, A.; U., Gomel State Tech.; Dutta, T.; Dauncey, P.D.; Balbuena, J.P.; Fleta, C.; Lozano, M.; Ullan, M.; Christian, G.B.; Faus-Golfe, A.; Fuster, J.; Lacasta, C.; Marinnas, C.; Vos, M.; Duarte, J.; Fernandez, M.; Gonzalez, J.; Jaramillo, R.; Lopez, Virto A.; Martinez-Eivero, C.; Moya, D.; Ruiz-Mimeno, A.; Vila, I.; Colledani, C.; Dorokhov, A.; Hu-Guo, C.; Winter, M.; Moortgat-Pick, G.; Onoprienko, D.V.; Kim, G.N.; Park, H.; Adloff, C.; Blaha, J.; Blaising, J.-J.; Cap, S.; Chefdeville, M.; Drancourt, C.; Espargiliare, A.; Gaglione, R.; Geffroy, N.; Jacquemier, J.; Karyotakis, Y.; Prast, J.; Vouters, G.; Gronberg, J.; Walston, S.; Wright, D.; Sawyer, L.; Laloum, M.; Ciobanu, C.; Chauveau, J.; Savoy-Navarro, A.; Andricek, L.; Moser, H.-G.; Cowan, R.f.; Fisher, P.; Yamamoto, R.K.; Kenney, ClMl; Boos, E.E.; Merkin, M.; Chen, S.; Chakraborty, D.; Dyshkant, A.; Hedin, D.; Zutshi, V.; Galkin, V.; D'Ascenzo, N.; Ossetski, D.; Saveliev, V.; Kapusta, F.; De Masi, R.; Vrba, V.; Lu, C.; McDonald, K.T.; Smith, A.J.S.; Bortoletto, D.; Coath, R.; Crooks, J.; Damerell, C.; Gibson, M.; Nichols, A.; Stanitzki, M.; Strube, J.; Turchetta, R.; Tyndel, M.; Weber, M.; Worm, S.; Zhang, Z.; Barklow, T.L.; Belymam, A.; Breidenbach, M.; Cassell, R.; Craddock, W.; Deaconu, C.; Dragone, A.; Graf, N.A.; Haller, G.; Herbst, R.; Hewett, J.L.; Jaros, J.A.; Johnson, A.S.; Kim, P.C.; MacFarlane, D.B.; Markiewicz, T.; Maruyama, T.; McCormick, J.; Moffeit, K.; Neal, H.A.; Nelson, T.K.; Oriunno, M.; Partridge, R.; Peskin, M.E.; Rizzo, T.G.; Rowson, P.; Su, D.; Woods, M.; Chakrabarti, S.; Dieguez, A.; Garrido, Ll.; Kaminski, J.; Conway, J.S.; Chertok, M.; Gunion, J.; Holbrook, B.; Lander, R.L.; Tripathi, S.M.; Fadeyev, V.; Schumm, B.A.; Oreglia, M.; Gill, J.; Nauenberg, U.; Oleinik, G.; Wagner, S.R.; Ranjan, K.; Shivpuri, R.; Varner, G.S.; Orava, R.; Van Kooten, R.; Bilki, B.; Charles, M.; Kim, T.J.; Mallik, U.; Norbeck, E.; Onel, Y.; Brau, B.P.; Willocq, S.; Taylor, G.N.; Riles, Keith; Yang, H.-J.; Kriske, R.; Cremaldi, L.; Rahmat, R.; Lastovicka-Medin, G.; Seidel, S.; Hildreth, M.D.; Wayne, M.; Brau, J.E.; Frey, R.; Sinev, N.; Strom, D.M.; Torrence, E.; Banda, Y.; Burrows, P.N.; Devetak, E.; Foster, B.; Lastovicka, T.; Li, Y.-M.; Nomerotski, A.; Riera-Babures, J.; Vilasis-Cardona, X.; Manly, S.; Adeva, B.; Iglesias Escudero, C.; Vazquez Regueiro, P.; Saborido Silva, J.J.; Gallas Torreira, A.; Gao, D.; Jie, W.; Jungfeng, Y.; Li, C.; Liu, S.; Liu, Y.; Sun, Y.; Wang, Q.; Yi, J.; Yonggang, W.; Zhao, Z.; De, K.; Farbin, A.; Park, S.; Smith, J.; White, A.P.; Yu, J.; Lou, X.C.; Abe, T.; Iwasaki, M.; Lubatti, H.J.; Band, H.R.; Feyzi, F.; Prepost, R.; Karchin, P.E.; Milstene, C.; Baltay, C.; Dhawan, S.; Kwon, Y.-J.

    2009-01-01

    Letter of intent describing SiD (Silicon Detector) for consideration by the International Linear Collider IDAG panel. This detector concept is founded on the use of silicon detectors for vertexing, tracking, and electromagnetic calorimetry. The detector has been cost-optimized as a general-purpose detector for a 500 GeV electron-positron linear collider.

  18. Semiconductor detector with smoothly tunable effective thickness for the study of ionization loss by moderately relativistic electrons

    Energy Technology Data Exchange (ETDEWEB)

    Shchagin, A.V., E-mail: shchagin@kipt.kharkov.ua [Kharkov Institute of Physics and Technology, Kharkov (Ukraine); Belgorod National Research University, Belgorod (Russian Federation); Shul’ga, N.F.; Trofymenko, S.V. [Kharkov Institute of Physics and Technology, Kharkov (Ukraine); Kharkov National University, Kharkov (Ukraine); Nazhmudinov, R.M.; Kubankin, A.S. [Belgorod National Research University, Belgorod (Russian Federation); P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow (Russian Federation)

    2016-11-15

    The possibility of measurement of electrons ionization loss in Si layer of smoothly tunable thickness is shown in the proof-of-principle experiment. The Si surface-barrier detector with the depleted layer thickness controlled by the value of high voltage power supply has been used. Ionization loss spectra for electrons emitted by radioactive source {sup 207}Bi are presented and discussed. Experimental results for the most probable ionization loss in the Landau spectral peak are compared with theoretical calculations. The possibility of research of evolution of electromagnetic field of ultra-relativistic particles traversing media interface with the use of detectors with smoothly tunable thickness is proposed.

  19. Compound Semiconductor Radiation Detector

    International Nuclear Information System (INIS)

    Kim, Y. K.; Park, S. H.; Lee, W. G.; Ha, J. H.

    2005-01-01

    In 1945, Van Heerden measured α, β and γ radiations with the cooled AgCl crystal. It was the first radiation measurement using the compound semiconductor detector. Since then the compound semiconductor has been extensively studied as radiation detector. Generally the radiation detector can be divided into the gas detector, the scintillator and the semiconductor detector. The semiconductor detector has good points comparing to other radiation detectors. Since the density of the semiconductor detector is higher than that of the gas detector, the semiconductor detector can be made with the compact size to measure the high energy radiation. In the scintillator, the radiation is measured with the two-step process. That is, the radiation is converted into the photons, which are changed into electrons by a photo-detector, inside the scintillator. However in the semiconductor radiation detector, the radiation is measured only with the one-step process. The electron-hole pairs are generated from the radiation interaction inside the semiconductor detector, and these electrons and charged ions are directly collected to get the signal. The energy resolution of the semiconductor detector is generally better than that of the scintillator. At present, the commonly used semiconductors as the radiation detector are Si and Ge. However, these semiconductor detectors have weak points. That is, one needs thick material to measure the high energy radiation because of the relatively low atomic number of the composite material. In Ge case, the dark current of the detector is large at room temperature because of the small band-gap energy. Recently the compound semiconductor detectors have been extensively studied to overcome these problems. In this paper, we will briefly summarize the recent research topics about the compound semiconductor detector. We will introduce the research activities of our group, too

  20. Determination Of Rare Earth And Other Elements In YEN-PHU Rare Earth Ore And Other Intermediate Products From The Floatation And Hydrometallurgical Process On Portable XRF Si-PIN Detector

    International Nuclear Information System (INIS)

    Doan Thanh Son; Phung Vu Phong; Nguyen Hanh Phuc

    2014-01-01

    The concentration of rare earths elements such as La, Ce, Pr, Nd, Gd and other elements as Ca, Fe, U, Th in Yen Phu rare earth ore and other intermediate products from the flotation and hydrometallurgical process was determined by using Si-PIN detector fluorescence spectrometry. The precision and accuracy of quantitative analysis was tested by standard reference materials and comparative analysis with different analytical methods. The analytical procedures were set-up and applied for the determination of rare earth and other elements in Yen Phu rare earth ore and other intermediate products from the flotation and hydrometallurgical process with high precision and accuracy. (author)

  1. Reduction of basal plane defects in (11-22) semipolar InGaN/GaN MQWs fabricated on patterned (113) Si substrates by introducing AlGaN barrier layers

    Energy Technology Data Exchange (ETDEWEB)

    Uesugi, Kenjiro; Hikosaka, Toshiki; Ono, Hiroshi; Sakano, Tatsunori; Nunoue, Shinya [Corporate Research and Development Center, Toshiba Corporation, Kawasaki (Japan)

    2017-08-15

    GaN grown on nonpolar or semipolar faces have been widely developed as a promising material for the next generation optical and electronic devices. In this work, (11-22) semipolar InGaN/GaN MQWs were grown on patterned (113) Si substrates and fabricated into thin-film-type flip-chip LEDs. From CL and TEM measurement, generation of basal plane defects (BPDs) around MQWs and Strain-relaxation layers (SRLs) has been observed. The relationship between MQW structures and formation of BPDs has been investigated. By optimizing MQW structures, light output power and external quantum efficiency have been improved with thick InGaN well layers and GaN barrier layers. Introducing AlGaN barrier layers has enabled further reduction of BPDs in MQWs and, as a result, an enhancement of EQE has been achieved. The maximum EQE value of the sample with AlGaN barrier layers was 12.9%.This result indicates that the reduction of BPDs is an effective approach for obtaining the high-efficiency semipolar LEDs on Si substrates. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Multilayer moisture barrier

    Science.gov (United States)

    Pankow, Joel W; Jorgensen, Gary J; Terwilliger, Kent M; Glick, Stephen H; Isomaki, Nora; Harkonen, Kari; Turkulainen, Tommy

    2015-04-21

    A moisture barrier, device or product having a moisture barrier or a method of fabricating a moisture barrier having at least a polymer layer, and interfacial layer, and a barrier layer. The polymer layer may be fabricated from any suitable polymer including, but not limited to, fluoropolymers such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), or ethylene-tetrafluoroethylene (ETFE). The interfacial layer may be formed by atomic layer deposition (ALD). In embodiments featuring an ALD interfacial layer, the deposited interfacial substance may be, but is not limited to, Al.sub.2O.sub.3, AlSiO.sub.x, TiO.sub.2, and an Al.sub.2O.sub.3/TiO.sub.2 laminate. The barrier layer associated with the interfacial layer may be deposited by plasma enhanced chemical vapor deposition (PECVD). The barrier layer may be a SiO.sub.xN.sub.y film.

  3. Characterization of imaging pixel detectors of Si and CdTe read out with the counting X-ray chip MPEC 2.3; Charakterisierung von bildgebenden Pixeldetektoren aus Si und CdTe ausgelesen mit dem zaehlenden Roentgenchip MPEC 2.3

    Energy Technology Data Exchange (ETDEWEB)

    Loecker, M.

    2007-04-15

    Single photon counting detectors with Si- and CdTe-sensors have been constructed and characterized. As readout chip the MPEC 2.3 is used which consists of 32 x 32 pixels with 200 x 200 {mu}m{sup 2} pixel size and which has a high count rate cabability (1 MHz per pixel) as well as a low noise performance (55 e{sup -}). Measurements and simulations of the detector homogeneity are presented. It could be shown that the theoretical maximum of the homogeneity is reached (quantum limit). By means of the double threshold of the MPEC chip the image contrast can be enhanced which is demonstrated by measurement and simulation. Also, multi-chip-modules consisting of 4 MPEC chips and a single Si- or CdTe-sensor have been constructed and successfully operated. With these modules modulation-transfer-function measurements have been done showing a good spatial resolution of the detectors. In addition, multi-chip-modules according to the Sparse-CMOS concept have been built and tests characterizing the interconnection technologies have been performed.

  4. The international linear collider. Technical design report. Vol. 4. Detectors

    International Nuclear Information System (INIS)

    Behnke, Ties; Brau, James E.; Burrows, Philip; Fuster, Juan; Peskin, Michael; Stanitzki, Marcel; Sugimoto, Yasuhiro; Yamada, Sakue; Yamamoto, Hitoshi

    2013-01-01

    The following topics are dealt with: The Si Vertex detectors, the main tracker, calorimetry, muon detectors, the superconducting spectrometer magnet, the detector electronics and data acquisition, simulation and reconstruction, benchmarking, costs. (HSI)

  5. The international linear collider. Technical design report. Vol. 4. Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Behnke, Ties; Brau, James E.; Burrows, Philip; Fuster, Juan; Peskin, Michael; Stanitzki, Marcel; Sugimoto, Yasuhiro; Yamada, Sakue; Yamamoto, Hitoshi [eds.

    2013-10-01

    The following topics are dealt with: The Si Vertex detectors, the main tracker, calorimetry, muon detectors, the superconducting spectrometer magnet, the detector electronics and data acquisition, simulation and reconstruction, benchmarking, costs. (HSI)

  6. Utilization of a Si-surface-barrier-detector for alpha-spectrometry and its application in radiation protection for the detection of law alpha-activities

    International Nuclear Information System (INIS)

    Steger, F.; Urbanich, E.; Lovranich, E.; Hefner, A.

    1974-12-01

    Due to the construction of the ''Safeguard Analytical Laboratory''(IAEA), the institute for radiation protection at the Research Center Seibersdorf is interested in a method for the alpha-spectroscopic determination of Pu-239 for personnel and environmental monitoring. Therefore an alpha-spectrometer has been built which will mainly be used for the excretion analysis. The design of the apparatus is described, results of measurements are given and other fields of its application are discussed. (C.R.)

  7. Heavy ion recoil spectrometry of Si{sub x}Ge{sub 1-x} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Walker, S R; Johnston, P N; Bubb, I F [Royal Melbourne Inst. of Tech., VIC (Australia); Cohen, D D; Dytlewski, N [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Hult, M; Whitlow, H J [Lund Institute of Technology, Solvegatan (Sweden). Department of Nuclear Physics; Zaring, C; Oestling, M [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Solid State Electronics

    1994-12-31

    Mass and energy dispersive recoil spectrometry employing 77 MeV {sup 127}I ions from ANTARES (FN Tandem) facility at Lucas Heights has been used to examine the isotopic composition of samples of Si{sub x}Ge{sub 1-x} grown at the Australian National University by Electron Beam Evaporation (EBE). The recoiling target nuclei were analysed by a Time Of Flight and Energy (TOF-E) detector telescope composed of two timing pickoff detectors and a surface barrier (energy) detector. From the time of flight and energy, the ion mass can be determined and individual depth distributions for each element can be obtained. Recoil spectrometry has shown the presence of oxygen in the Si{sub x}Ge{sub 1-x} layer and has enabled the separate determination of energy spectra for individual elements. 9 refs., 3 figs.

  8. Heavy ion recoil spectrometry of Si{sub x}Ge{sub 1-x} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Walker, S.R.; Johnston, P.N.; Bubb, I.F. [Royal Melbourne Inst. of Tech., VIC (Australia); Cohen, D.D.; Dytlewski, N. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Hult, M.; Whitlow, H.J. [Lund Institute of Technology, Solvegatan (Sweden). Department of Nuclear Physics; Zaring, C.; Oestling, M. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Solid State Electronics

    1993-12-31

    Mass and energy dispersive recoil spectrometry employing 77 MeV {sup 127}I ions from ANTARES (FN Tandem) facility at Lucas Heights has been used to examine the isotopic composition of samples of Si{sub x}Ge{sub 1-x} grown at the Australian National University by Electron Beam Evaporation (EBE). The recoiling target nuclei were analysed by a Time Of Flight and Energy (TOF-E) detector telescope composed of two timing pickoff detectors and a surface barrier (energy) detector. From the time of flight and energy, the ion mass can be determined and individual depth distributions for each element can be obtained. Recoil spectrometry has shown the presence of oxygen in the Si{sub x}Ge{sub 1-x} layer and has enabled the separate determination of energy spectra for individual elements. 9 refs., 3 figs.

  9. Development of antibody-modified chitosan nanoparticles for the targeted delivery of siRNA across the blood-brain barrier as a strategy for inhibiting HIV replication in astrocytes.

    Science.gov (United States)

    Gu, Jijin; Al-Bayati, Karam; Ho, Emmanuel A

    2017-08-01

    RNA interference (RNAi)-mediated gene silencing offers a novel treatment and prevention strategy for human immunodeficiency virus (HIV) infection. HIV was found to infect and replicate in human brain cells and can cause neuroinfections and neurological deterioration. We designed dual-antibody-modified chitosan/small interfering RNA (siRNA) nanoparticles to deliver siRNA across the blood-brain barrier (BBB) targeting HIV-infected brain astrocytes as a strategy for inhibiting HIV replication. We hypothesized that transferrin antibody and bradykinin B2 antibody could specifically bind to the transferrin receptor (TfR) and bradykinin B2 receptor (B2R), respectively, and deliver siRNA across the BBB into astrocytes as potential targeting ligands. In this study, chitosan nanoparticles (CS-NPs) were prepared by a complex coacervation method in the presence of siRNA, and antibody was chemically conjugated to the nanoparticles. The antibody-modified chitosan nanoparticles (Ab-CS-NPs) were spherical in shape, with an average particle size of 235.7 ± 10.2 nm and a zeta potential of 22.88 ± 1.78 mV. The therapeutic potential of the nanoparticles was evaluated based on their cellular uptake and gene silencing efficiency. Cellular accumulation and gene silencing efficiency of Ab-CS-NPs in astrocytes were significantly improved compared to non-modified CS-NPs and single-antibody-modified CS-NPs. These results suggest that the combination of anti-Tf antibody and anti-B2 antibody significantly increased the knockdown effect of siRNA-loaded nanoparticles. Thus, antibody-mediated dual-targeting nanoparticles are an efficient and promising delivery strategy for inhibiting HIV replication in astrocytes. Graphical abstract Graphic representation of dual-antibody-conjugated chitosan nanoparticles for the targeted delivery of siRNA across the blood-brain barrier (BBB) for inhibiting HIV replication in astrocytes. a Nanoparticle delivery to the BBB and penetration. b Tf

  10. Radiation detectors

    International Nuclear Information System (INIS)

    2013-01-01

    This sixth chapter presents the operational principles of the radiation detectors; detection using photographic emulsions; thermoluminescent detectors; gas detectors; scintillation detectors; liquid scintillation detectors; detectors using semiconductor materials; calibration of detectors; Bragg-Gray theory; measurement chain and uncertainties associated to measurements

  11. The ATLAS inner detector semiconductor tracker (Si and GaAs strips): review of the 1995 beam tests at the CERN SPS H8 beamline

    International Nuclear Information System (INIS)

    Moorhead, G.F.

    1995-01-01

    This talk will consist of a brief review of the ATLAS Inner Detector (ID) Semiconductor Tracker (SCT) strip detector (both silicon and gallium arsenide) beam tests conducted at the ATLAS test beam facility at the CERN SPS H8 beamline. It will include a brief overview of the H8 facilities, the experimental layout of the SCT/Strip apparatus, the data acquisition system, some of the online software tools and the high precision silicon hodoscope and timing modules used. A very brief indication of some of the main varieties of detector systems tested and the measurements performed will be given. Throughout some emphasis will be placed on the contributions and-interests of members of the Melbourne group. (author)

  12. Silicon Detector Letter of Intent

    Energy Technology Data Exchange (ETDEWEB)

    Aihara, H.; Burrows, P.; Oreglia, M.

    2010-05-26

    This document presents the current status of SiD's effort to develop an optimized design for an experiment at the International Linear Collider. It presents detailed discussions of each of SiD's various subsystems, an overview of the full GEANT4 description of SiD, the status of newly developed tracking and calorimeter reconstruction algorithms, studies of subsystem performance based on these tools, results of physics benchmarking analyses, an estimate of the cost of the detector, and an assessment of the detector R&D needed to provide the technical basis for an optimised SiD.

  13. Sub-millimetre DOI detector based on monolithic LYSO and digital SiPM for a dedicated small-animal PET system

    International Nuclear Information System (INIS)

    Marcinkowski, Radosław; Mollet, Pieter; Van Holen, Roel; Vandenberghe, Stefaan

    2016-01-01

    The mouse model is widely used in a vast range of biomedical and preclinical studies. Thanks to the ability to detect and quantify biological processes at the molecular level in vivo, PET has become a well-established tool in these investigations. However, the need to visualize and quantify radiopharmaceuticals in anatomic structures of millimetre or less requires good spatial resolution and sensitivity from small-animal PET imaging systems. In previous work we have presented a proof-of-concept of a dedicated high-resolution small-animal PET scanner based on thin monolithic scintillator crystals and Digital Photon Counter photosensor. The combination of thin monolithic crystals and MLE positioning algorithm resulted in an excellent spatial resolution of 0.7 mm uniform in the entire field of view (FOV). However, the limitation of the scanner was its low sensitivity due to small thickness of the lutetium-yttrium oxyorthosilicate (LYSO) crystals (2 mm). Here we present an improved detector design for a small-animal PET system that simultaneously achieves higher sensitivity and sustains a sub-millimetre spatial resolution. The proposed detector consists of a 5 mm thick monolithic LYSO crystal optically coupled to a Digital Photon Counter. Mean nearest neighbour (MNN) positioning combined with depth of interaction (DOI) decoding was employed to achieve sub-millimetre spatial resolution. To evaluate detector performance the intrinsic spatial resolution, energy resolution and coincidence resolving time (CRT) were measured. The average intrinsic spatial resolution of the detector was 0.60 mm full-width-at-half-maximum (FWHM). A DOI resolution of 1.66 mm was achieved. The energy resolution was 23% FWHM at 511 keV and CRT of 529 ps were measured. The improved detector design overcomes the sensitivity limitation of the previous design by increasing the nominal sensitivity of the detector block and retains an excellent intrinsic spatial resolution. (paper)

  14. Silicon Telescope Detectors

    CERN Document Server

    Gurov, Yu B; Sandukovsky, V G; Yurkovski, J

    2005-01-01

    The results of research and development of special silicon detectors with a large active area ($> 8 cm^{2}$) for multilayer telescope spectrometers (fulfilled in the Laboratory of Nuclear Problems, JINR) are reviewed. The detector parameters are listed. The production of totally depleted surface barrier detectors (identifiers) operating under bias voltage two to three times higher than depletion voltage is described. The possibility of fabrication of lithium drifted counters with a very thin entrance window on the diffusion side of the detector (about 10--20 $\\mu$m) is shown. The detector fabrication technique has allowed minimizing detector dead regions without degradation of their spectroscopic characteristics and reliability during long time operation in charge particle beams.

  15. GaAs detectors with an ultra-thin Schottky contact for spectrometry of charged particles

    Energy Technology Data Exchange (ETDEWEB)

    Chernykh, S.V., E-mail: chsv_84@mail.ru [National University of Science and Technology “MISIS”, Moscow (Russian Federation); Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); Chernykh, A.V. [National University of Science and Technology “MISIS”, Moscow (Russian Federation); Didenko, S.I.; Baryshnikov, F.M. [National University of Science and Technology “MISIS”, Moscow (Russian Federation); Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); Burtebayev, N. [Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); Institute of Nuclear Physics, Almaty (Kazakhstan); Britvich, G.I. [Institute of High Energy Physics, Protvino, Moscow region (Russian Federation); Chubenko, A.P. [Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow (Russian Federation); Guly, V.G.; Glybin, Yu.N. [LLC “SNIIP Plus”, Moscow (Russian Federation); Zholdybayev, T.K.; Burtebayeva, J.T.; Nassurlla, M. [Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); Institute of Nuclear Physics, Almaty (Kazakhstan)

    2017-02-11

    For the first time, samples of particle detectors based on high-purity GaAs epilayers with an active area of 25 and 80 mm{sup 2} and an ultra-thin Pt Schottky barrier were fabricated for use in the spectrometry of charged particles and their operating characteristics were studied. The obtained FWHM of 14.2 (for 25 mm{sup 2} detector) and 15.5 keV (for 80 mm{sup 2} detector) on the 5.499 MeV line of {sup 238}Pu is at the level of silicon spectrometric detectors. It was found that the main component that determines the energy resolution of the detector is a fluctuation in the number of collected electron–hole pairs. This allows us to state that the obtained energy resolution is close to the limit for VPE GaAs. - Highlights: • VPE GaAs particle detectors with an active area of 25 and 80 mm{sup 2} were fabricated. • 120 Å ultra-thin Pt Schottky barrier was used as a rectifying contact. • The obtained FWHM of 14.2 keV ({sup 238}Pu) is at the level of Si spectrometric detectors. • Various components of the total energy resolution were analyzed. • It was shown that obtained energy resolution is close to its limit for VPE GaAs.

  16. (Li) detector characteristics on the accuracy in X-ray analysis using the

    African Journals Online (AJOL)

    A study has been carried out to show how variations in Si(Li) detector characteristics affect the accuracy of X-ray spectra evaluation. The detector characteristics investigated are Be window thickness, Au layer, Si dead layer and Si Detector Sensitive volume. For each of the detector parameters, different thickness values ...

  17. Performances of the Si microstrip detector of the STAR experiment at RHIC; Performances du detecteur en silicium a micropistes de l'experience STAR a RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Bouchet, J

    2007-10-15

    The Silicon Strip Detector (SSD) is the fourth layer of detector using a double-sided microstrip technology of the STAR experiment at RHIC, completing STAR's inner tracking device. The goal of STAR is to study heavy ions collisions in order to probe the existence of the quark gluon plasma (QGP), a deconfined state of nuclear matter. Strangeness enhancement, such as {kappa}{sub S}{sup 0}, {lambda}, {xi} and {omega}, for particles production, has been proposed to sign the formation of QGP. Then precise measurement of secondary vertices is needed. The SSD will also permit an attempt to use the inner tracking device to measure charm and beauty with direct topological identification. It was proposed to enhance the STAR tracking capabilities by providing a better connection between reconstructed tracks in the main tracking device (TPC) and the initial vertex detector (SVT). In this thesis, we will present the intrinsic performances of the SSD and its impact on the inner tracking system performances by studying Cu-Cu collisions occurred at RHIC in 2005. We show that the SSD detector has excellent performances in terms of resolution: (945 {+-} 18) {mu}m in azimuth and (1021 {+-} 13) {mu}m along the beam axis. For the final result when SSD is associated to the SVT the resolutions are (281 {+-} 1) {mu}m and (213 {+-} 0.8) {mu}m in azimuth and along the beam axis respectively. The resolution reached by the addition of the Silicon Vertex detectors of STAR will allow the search for rare particles like charm and beauty, which have a decay-length of the order of hundred microns.

  18. Proportional gas scintillation detectors and their applications

    International Nuclear Information System (INIS)

    Petr, I.

    1978-01-01

    The principle is described of a gas proportional scintillation detector and its function. Dependence of Si(Li) and xenon proportional detectors energy resolution on the input window size is given. A typical design is shown of a xenon detector used for X-ray spetrometry at an energy of 277 eV to 5.898 keV and at a gas pressure of 98 to 270 kPa. Gas proportional scintillation detectors show considerable better energy resolution than common proportional counters and even better resolution than semiconductor Si(Li) detectors for low X radiation energies. For detection areas smaller than 25 mm 2 Si(Li) detectors show better resolution, especially for higher X radiation energies. For window areas 25 to 190 mm 2 both types of detectors are equal, for a window area exceeding 190 mm 2 the proportional scintillation detector has higher energy resolution. (B.S.)

  19. Use of semiconductor detector c-Si microstrip type in obtaining the digital radiographic imaging of phantoms and biological samples of mammary glands

    International Nuclear Information System (INIS)

    Leyva, A.; Cabal, A.; Pinera, I.; Abreu, Y.; Cruz, C. M.; Montano, L. M.; Diaz, C. C.; Fontaine, M.; Ortiz, C. M.; Padilla, F.; De la Mora, R.

    2009-01-01

    The present work synthesizes the experimental results obtained in the characterization of 64 micro strips crystalline silicon detector designed for experiments in high energies physics, with the objective of studying its possible application in advanced medical radiography, specifically in digital mammography and angiography. The research includes the acquisition of two-dimensional radiography of a mammography phantom using the scanning method, and its comparison with similar images simulated mathematically for different X rays sources. The paper also shows the experimental radiography of two biological samples taken from biopsies of mammas, where it is possible to identify the presence of possible pathological lesions. The results reached in this work point positively toward the effective possibility of satisfactorily introducing those advanced detectors in medical digital imaging applications. (Author)

  20. Inverse spin-valve effect in nanoscale Si-based spin-valve devices

    Science.gov (United States)

    Hiep, Duong Dinh; Tanaka, Masaaki; Hai, Pham Nam

    2017-12-01

    We investigated the spin-valve effect in nano-scale silicon (Si)-based spin-valve devices using a Fe/MgO/Ge spin injector/detector deposited on Si by molecular beam epitaxy. For a device with a 20 nm Si channel, we observed clear magnetoresistance up to 3% at low temperature when a magnetic field was applied in the film plane along the Si channel transport direction. A large spin-dependent output voltage of 20 mV was observed at a bias voltage of 0.9 V at 15 K, which is among the highest values in lateral spin-valve devices reported so far. Furthermore, we observed that the sign of the spin-valve effect is reversed at low temperatures, suggesting the possibility of a spin-blockade effect of defect states in the MgO/Ge tunneling barrier.

  1. Undepleted silicon detectors

    International Nuclear Information System (INIS)

    Rancoita, P.G.; Seidman, A.

    1985-01-01

    Large-size silicon detectors employing relatively low resistivity material can be used in electromagnetic calorimetry. They can operate in strong magnetic fields, under geometric constraints and with microstrip detectors a high resolution can be achieved. Low noise large capacitance oriented electronics was developed to enable good signal-to-noise ratio for single relativistic particles traversing large area detectors. In undepleted silicon detectors, the charge migration from the field-free region has been investigated by comparing the expected peak position (from the depleted layer only) of the energy-loss of relativistic electrons with the measured one. Furthermore, the undepleted detectors have been employed in a prototype of Si/W electromagnetic colorimeter. The sensitive layer was found to be systematically larger than the depleted one

  2. Measurements of jet rates with the anti-$k_T$ and SiScone algorithms at LEP with the OPAL detector

    CERN Document Server

    Verbytskyi, A

    2016-01-01

    We study jet production in $e^+e^−$ annihilation to hadrons with data recorded by the OPAL experiment at LEP at centre-of-mass energies between 90 GeV and 207 GeV. The jet $e^+e^−$ production rates were measured for the first time with the anti-$k_T$ and SiScone jet clustering algorithms. We compare the data with predictions by modern Monte Carlo event generators.

  3. Comparative study of mean value of 111 and mean value of 100 crystals and capacitance measurements on Si strip detectors in CSM

    International Nuclear Information System (INIS)

    Albergo, S.

    1999-01-01

    For the construction of the silicon microstrip detectors for the tracker of CMS experiment, two different substrate choices were investigated. A high-resistivity substrate with mean value of 111 crystal orientation and a low-resistivity one with mean value of 100 Dirac ket vector crystal orientation. The interstrip and backplane capacitances were measured before and after the exposure to radiation in a range of strip pitches from 60 μm to 240 μm and for values of the width-pitch ratio between 0.1 and 0.5

  4. SiD Letter of Intent

    Energy Technology Data Exchange (ETDEWEB)

    Aihara, H., (Ed.); Burrows, P., (Ed.); Oreglia, M., (Ed.); Berger, E.L.; Guarino, V.; Repond, J.; Weerts, H.; Xia, L.; Zhang, J.; /Argonne, HEP; Zhang, Q.; /Argonne, HEP /Beijing, Inst. High Energy Phys.; Srivastava, A.; /Birla Inst. Tech. Sci.; Butler, J.M.; /Boston U.; Goldstein, Joel; Velthuis, J.; /Bristol U.; Radeka, V.; /Brookhaven; Zhu, R.-Y.; /Caltech.; Lutz, P.; /DAPNIA, Saclay; de Roeck, A.; Elsener, K.; Gaddi, A.; Gerwig, H.; /CERN /Cornell U., LNS /Ewha Women' s U., Seoul /Fermilab /Gent U. /Darmstadt, GSI /Imperial Coll., London /Barcelona, Inst. Microelectron. /KLTE-ATOMKI /Valencia U., IFIC /Cantabria Inst. of Phys. /Louis Pasteur U., Strasbourg I /Durham U., IPPP /Kansas State U. /Kyungpook Natl. U. /Annecy, LAPP /LLNL, Livermore /Louisiana Tech. U. /Paris U., VI-VII /Paris U., VI-VII /Munich, Max Planck Inst. /MIT, LNS /Chicago, CBC /Moscow State U. /Nanjing U. /Northern Illinois U. /Obninsk State Nucl. Eng. U. /Paris U., VI-VII /Strasbourg, IPHC /Prague, Inst. Phys. /Princeton U. /Purdue U. /Rutherford /SLAC /SUNY, Stony Brook /Barcelona U. /Bonn U. /UC, Davis /UC, Santa Cruz /Chicago U. /Colorado U. /Delhi U. /Hawaii U. /Helsinki U. /Indiana U. /Iowa U. /Massachusetts U., Amherst /Melbourne U. /Michigan U. /Minnesota U. /Mississippi U. /Montenegro U. /New Mexico U. /Notre Dame U. /Oregon U. /Oxford U. /Ramon Llull U., Barcelona /Rochester U. /Santiago de Compostela U., IGFAE /Hefei, CUST /Texas U., Arlington /Texas U., Dallas /Tokyo U. /Washington U., Seattle /Wisconsin U., Madison /Wayne State U. /Yale U. /Yonsei U.

    2012-04-11

    This document presents the current status of the Silicon Detector (SiD) effort to develop an optimized design for an experiment at the International Linear Collider. It presents detailed discussions of each of SiD's various subsystems, an overview of the full GEANT4 description of SiD, the status of newly developed tracking and calorimeter reconstruction algorithms, studies of subsystem performance based on these tools, results of physics benchmarking analyses, an estimate of the cost of the detector, and an assessment of the detector R and D needed to provide the technical basis for an optimised SiD.

  5. Cryogenic Tracking Detectors

    CERN Multimedia

    Luukka, P R; Tuominen, E M; Mikuz, M

    2002-01-01

    The recent advances in Si and diamond detector technology give hope of a simple solution to the radiation hardness problem for vertex trackers at the LHC. In particular, we have recently demonstrated that operating a heavily irradiated Si detector at liquid nitrogen (LN$_2$) temperature results in significant recovery of Charge Collection Efficiency (CCE). Among other potential benefits of operation at cryogenic temperatures are the use of large low-resistivity wafers, simple processing, higher and faster electrical signal because of higher mobility and drift velocity of carriers, and lower noise of the readout circuit. A substantial reduction in sensor cost could result The first goal of the approved extension of the RD39 program is to demonstrate that irradiation at low temperature in situ during operation does not affect the results obtained so far by cooling detectors which were irradiated at room temperature. In particular we shall concentrate on processes and materials that could significantly reduce th...

  6. Tailoring Lipid and Polymeric Nanoparticles as siRNA Carriers towards the Blood-Brain Barrier – from Targeting to Safe Administration

    DEFF Research Database (Denmark)

    Gomes, Maria João; Fernandes, Carlos; Martins, Susana

    2017-01-01

    . The interaction of modified nanoparticles with brain endothelial cells increased 3-fold compared to non-modified lipid nanoparticles, and 4-fold compared to non-modified PLGA nanoparticles, respectively. These nanosystems, which were also demonstrated to be safe for human brain endothelial cells, without...... and efficient delivery to its target, two different nanoparticles platforms, solid lipid (SLN) and poly-lactic-co-glycolic (PLGA) nanoparticles were used in this study. Polymeric PLGA nanoparticles were around 115 nm in size and had 50 % of siRNA association efficiency, while SLN presented 150 nm...

  7. Analysis of the /sup 28/Si(p,. gamma. )/sup 29/P reaction data in the region of the sub-barrier single particle resonances

    Energy Technology Data Exchange (ETDEWEB)

    Matulewicz, T; Decowski, P; Kicinska-Habior, M; Sikora, B; Toke, J

    1983-01-01

    The /sup 28/Si(p, ..gamma..)/sup 29/P reaction data have been analyzed in terms of a modified direct-semidirect capture model which accounts for the presence of broad shape (single-particle) resonances in the entrance channel. Values of the spectroscopic factors for the ground state and 1,65 MeV and 2,88 MeV resonances in /sup 29/P nuclei were extracted and found to be consistent with those obtained in other experiments. The modified theoretical analysis scheme was found to provide a convenient tool for analyzing the radiative capture reaction data.

  8. Ionization detector

    International Nuclear Information System (INIS)

    Steele, D.S.

    1987-01-01

    An ionization detector having an array of detectors has, for example, grounding pads positioned in the spaces between some detectors (data detectors) and other detectors (reference detectors). The grounding pads are kept at zero electric potential, i.e. grounded. The grounding serves to drain away electrons and thereby prevent an unwanted accumulation of charge in the spaces, and cause the electric field lines to be more perpendicular to the detectors in regions near the grounding pads. Alternatively, no empty space is provided there being additional, grounded, detectors provided between the data and reference detectors. (author)

  9. High resolution investigation of the 30Si(þ, þ)30Si reaction

    NARCIS (Netherlands)

    Walinga, J.; Rinsvelt, H.A. van; Endt, P.M.

    The differential cross section for elastic scattering of protons on 30Si was measured with surface barrier counters at four angles. Thirty-six 30Si(þ, γ)31P resonances are known in the Ep=1–2MeV region. Fifteen of these were also observed in the 30Si(þ, þ)30Si reaction, with natural widths varying

  10. Silicon detectors

    International Nuclear Information System (INIS)

    Klanner, R.

    1984-08-01

    The status and recent progress of silicon detectors for high energy physics is reviewed. Emphasis is put on detectors with high spatial resolution and the use of silicon detectors in calorimeters. (orig.)

  11. Study of 50 GeV proton ionization loss by semiconductor detector with smoothly tunable thickness

    Energy Technology Data Exchange (ETDEWEB)

    Nazhmudinov, R.M.; Kubankin, A.S. [Belgorod National Research University, Belgorod (Russian Federation); P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow (Russian Federation); Shchagin, A.V., E-mail: shchagin@kipt.kharkov.ua [Belgorod National Research University, Belgorod (Russian Federation); Kharkov Institute of Physics and Technology, Kharkov (Ukraine); Shul' ga, N.F.; Trofymenko, S.V. [Kharkov Institute of Physics and Technology, Kharkov (Ukraine); Kharkov National University, Kharkov (Ukraine); Britvich, G.I.; Durum, A.A.; Kostin, M. Yu.; Maisheev, V.A.; Chesnokov, Yu.A.; Yanovich, A.A. [Institute for High Energy Physics in National Research Centre Kurchatov Institute, Protvino (Russian Federation)

    2017-01-15

    The possibility of the measurement of proton ionization loss in the Silicon (Si) layer of smoothly tunable thickness was demonstrated in an experiment with a 50-GeV proton beam. The Si surface-barrier detector with the depleted layer thickness controlled by the value of high-voltage power supply was used in the experiment. The measured spectra of ionization loss are discussed and compared with the calculated spectra. The possibilities of research of the evolution of electromagnetic field of ultrarelativistic particles traversing the media interface and the study of dynamics of particles moving in the channeling regime or the volume reflection regime with the use of detectors with smoothly tunable thickness are indicated.

  12. Some Applications of Surface Barrier Solid-State Detectors for Alpha-Activity Detection and Measurement; Quelques Applications des Detecteurs a Semi-Conducteurs a Barriere de Surface pour Deceler et Mesurer l'Activite Alpha; Nekotorye vidy primeneniya detektorov tverdogo sostoyaniya s poverkhnostnym bar'erom dlya izmereniya i obnaruzheniya al'fa-aktivnosti; Aplicaciones de los Detectores de Semiconductores de Barrera Superficial a la Deteccion y Medicion de Emisores Alfa

    Energy Technology Data Exchange (ETDEWEB)

    Perry, K. E.G. [Atomic Energy Establishment, Winfrith, Dorset (United Kingdom)

    1965-10-15

    utilise un nouvel appareil automatique de mesure du rayonnement alpha, qui comporte un detecteur a semi-conducteurs, pour analyser les papiers-filtres provenant des echantillonneurs d'air dont est pourvu le personnel qui manipule du plutonium. Cet appareil mesure automatiquement la radioactivite individuelle de 12 papiers-filtres pendant un temps pre-regle et imprime le nombre total de coups enregistres. Il comporte egalement un circuit d'analyse en continu qui permet de controler rapidement si la radioactivite de l'echantillon est superieure ou inferieure a un niveau pre-determine. On pourrait facilement utiliser la meme methode pour une gamme etendue d'analyses d'echantillons. Les detecteurs a semi-conducteurs sont egalement tres souvent utilises dans divers types de sondes servant au controle general du rayonnement alpha; on a mis au point des sondes dont la surface sensible varie entre 12 mm{sup 2} et 18 cm{sup 2}. Les detecteurs a surface de detection reduite sont utiles pour deceler des points de contamination sur le corps et ils sont plus pratiques a cet egard que d'autres types de detecteurs (par exemple, les detecteurs a scintillation), du fait de leur solidite, de leur absence de sensibilite a la lumiere et de la simplicite de l'appareillage connexe. Une autre propriete interessante des detecteurs and semi-conducteurs, par rapport aux compteurs a scintillation a ZnS normaux, est leur absence de reponse au rayonnement gamma; cette consideration est importante lorsqu'on veut determiner la contamination alpha en presence d'un bruit de fond constitue par un rayonnement gamma intense; c'est notamment le cas pour la detection des fuites de matiere provenant d'une aiguille de radium ou d'une capsule de radon. Le memoire donne des details sur ces sondes. (author) [Spanish] Los servicios de la United Kingdom Atomic Energy Authority utilizan cada vez mas los detectores de semiconductores para la medicion de muestras biologicas y para la vigilancia de las operaciones con

  13. A monolithic silicon detector telescope

    International Nuclear Information System (INIS)

    Cardella, G.; Amorini, F.; Cabibbo, M.; Di Pietro, A.; Fallica, G.; Franzo, G.; Figuera, P.; Papa, M.; Pappalardo, G.; Percolla, G.; Priolo, F.; Privitera, V.; Rizzo, F.; Tudisco, S.

    1996-01-01

    An ultrathin silicon detector (1 μm) thick implanted on a standard 400 μm Si-detector has been built to realize a monolithic telescope detector for simultaneous charge and energy determination of charged particles. The performances of the telescope have been tested using standard alpha sources and fragments emitted in nuclear reactions with different projectile-target colliding systems. An excellent charge resolution has been obtained for low energy (less than 5 MeV) light nuclei. A multi-array lay-out of such detectors is under construction to charge identify the particles emitted in reactions induced by low energy radioactive beams. (orig.)

  14. Interfacial barrier height modification of indium tin oxide/a-Si:H(p) via control of density of interstitial oxygen for silicon heterojunction solar cell application

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Shihyun; Kim, Sunbo; Dao, Vinh Ai; Lee, Seungho; Iftiquar, S.M. [College of Information and Communication Engineering, Sungkyunkwan University, 300 Chunchun-dong, Jangan-gu, Suwon, Gyeonggi-do 400-746 (Korea, Republic of); Kim, Doyoung [School of Electricity and Electronics, Ulsan College, Ulsan, 680-749 (Korea, Republic of); Hussain, Shahzada Qamar [Department of Energy Science, Sungkyunkwan University, 300 Chunchun-dong, Jangan-gu, Suwon, Gyeonggi-do 400-746 (Korea, Republic of); Park, Hyeongsik; Lee, Jaehyeong [College of Information and Communication Engineering, Sungkyunkwan University, 300 Chunchun-dong, Jangan-gu, Suwon, Gyeonggi-do 400-746 (Korea, Republic of); Lee, Youngseok [Department of Energy Science, Sungkyunkwan University, 300 Chunchun-dong, Jangan-gu, Suwon, Gyeonggi-do 400-746 (Korea, Republic of); Cho, Jaehyun [College of Information and Communication Engineering, Sungkyunkwan University, 300 Chunchun-dong, Jangan-gu, Suwon, Gyeonggi-do 400-746 (Korea, Republic of); Kim, Sangho [Department of Energy Science, Sungkyunkwan University, 300 Chunchun-dong, Jangan-gu, Suwon, Gyeonggi-do 400-746 (Korea, Republic of); Yi, Junsin, E-mail: yi@yurim.skku.ac.kr [College of Information and Communication Engineering, Sungkyunkwan University, 300 Chunchun-dong, Jangan-gu, Suwon, Gyeonggi-do 400-746 (Korea, Republic of); Department of Energy Science, Sungkyunkwan University, 300 Chunchun-dong, Jangan-gu, Suwon, Gyeonggi-do 400-746 (Korea, Republic of)

    2013-11-01

    An indium tin oxide (ITO) film with low carrier concentration (n), high mobility (μ) and high work function (Φ{sub ITO}) is a beneficial material for the front electrode in heterojunction silicon (HJ) solar cells due to its low free-carrier absorption in the near-infrared wavelength and low Schottky barrier height at the ITO/emitter-layer front contact. This low free-carrier absorption as well as the low Schottky barrier height increase the open-circuit voltage (V{sub oc}) and the short-circuit current density (J{sub sc}), which in turn increases the overall cell efficiency (η). Hence, ITO films with lower n, higher μ and higher Φ{sub ITO} were prepared by controlling the density of the interstitial oxygen [O{sub i}] in the films and used as anti-reflection electrodes in HJ solar cells. With increasing [O{sub i}] in the ITO, the preferential orientation of the (222) crystalline plane became more dominant. The Φ{sub ITO} and μ increased from 4.87 eV and 38.9 cm{sup 2} V{sup −1} s{sup −1} to 5.04 eV and 48.79 cm{sup 2} V{sup −1} s{sup −1}, respectively, whereas n decreased from 4.7 × 10{sup 20} cm{sup −3} to 2.8 × 10{sup 20} cm{sup −3}. We attribute these changes to the chemisorbed oxygen into the ITO films, while the decrease of n is due to the ability of interstitial oxygen to capture electron, and the increase of μ is due to the reduction in free-carrier scattering. These ITO films were used to fabricate HJ solar cells. As [O{sub i}] in the ITO film increased, the device performance improved and the best cell performance was obtained with V{sub oc} of 714 mV, J{sub sc} 34.79 mA/cm{sup 2} and η of 17.82%. By computer simulation, we found that the higher Φ{sub ITO} and μ but lower n were responsible for the enhanced cell performance. The cell performance, however, deteriorated due to poor film properties when [O{sub i}] exceeded concentration limit from 3.2 × 10{sup 20} cm{sup −3}. - Highlights: • The carrier concentration (n) decreases

  15. Detectors - Electronics; Detecteurs - Electronique

    Energy Technology Data Exchange (ETDEWEB)

    Bregeault, J.; Gabriel, J.L.; Hierle, G.; Lebotlan, P.; Leconte, A.; Lelandais, J.; Mosrin, P.; Munsch, P.; Saur, H.; Tillier, J. [Lab. de Physique Corpusculaire, Caen Univ., 14 (France)

    1998-04-01

    The reports presents the main results obtained in the fields of radiation detectors and associated electronics. In the domain of X-ray gas detectors for the keV range efforts were undertaken to rise the detector efficiency. Multiple gap parallel plate chambers of different types as well as different types of X {yields} e{sup -} converters were tested to improve the efficiency (values of 2.4% at 60 KeV were reached). In the field of scintillators a study of new crystals has been carried out (among which Lutetium orthosilicate). CdTe diode strips for obtaining X-ray imaging were studied. The complete study of a linear array of 8 CdTe pixels has been performed and certified. The results are encouraging and point to this method as a satisfying solution. Also, a large dimension programmable chamber was used to study the influence of temperature on the inorganic scintillators in an interval from -40 deg. C to +150 deg. C. Temperature effects on other detectors and electronic circuits were also investigated. In the report mentioned is also the work carried out for the realization of the DEMON neutron multidetector. For neutron halo experiments different large area Si detectors associated with solid and gas position detectors were realized. In the frame of a contract with COGEMA a systematic study of Li doped glasses was undertaken aiming at replacing with a neutron probe the {sup 3}He counters presently utilized in pollution monitoring. An industrial prototype has been realised. Other studies were related to integrated analog chains, materials for Cherenkov detectors, scintillation probes for experiments on fundamental processes, gas position sensitive detectors, etc. In the field of associated electronics there are mentioned the works related to the multidetector INDRA, data acquisition, software gamma spectrometry, automatic gas pressure regulation in detectors, etc

  16. Transmutation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Viererbl, L., E-mail: vie@ujv.c [Research Centre Rez Ltd. (Czech Republic); Nuclear Research Institute Rez plc (Czech Republic); Lahodova, Z. [Research Centre Rez Ltd. (Czech Republic); Nuclear Research Institute Rez plc (Czech Republic); Klupak, V. [Nuclear Research Institute Rez plc (Czech Republic); Sus, F. [Research Centre Rez Ltd. (Czech Republic); Nuclear Research Institute Rez plc (Czech Republic); Kucera, J. [Research Centre Rez Ltd. (Czech Republic); Nuclear Physics Institute, Academy of Sciences of the Czech Republic (Czech Republic); Kus, P.; Marek, M. [Research Centre Rez Ltd. (Czech Republic); Nuclear Research Institute Rez plc (Czech Republic)

    2011-03-11

    We have designed a new type of detectors, called transmutation detectors, which can be used primarily for neutron fluence measurement. The transmutation detector method differs from the commonly used activation detector method in evaluation of detector response after irradiation. Instead of radionuclide activity measurement using radiometric methods, the concentration of stable non-gaseous nuclides generated by transmutation in the detector is measured using analytical methods like mass spectrometry. Prospective elements and nuclear reactions for transmutation detectors are listed and initial experimental results are given. The transmutation detector method could be used primarily for long-term measurement of neutron fluence in fission nuclear reactors, but in principle it could be used for any type of radiation that can cause transmutation of nuclides in detectors. This method could also be used for measurement in accelerators or fusion reactors.

  17. Transmutation detectors

    International Nuclear Information System (INIS)

    Viererbl, L.; Lahodova, Z.; Klupak, V.; Sus, F.; Kucera, J.; Kus, P.; Marek, M.

    2011-01-01

    We have designed a new type of detectors, called transmutation detectors, which can be used primarily for neutron fluence measurement. The transmutation detector method differs from the commonly used activation detector method in evaluation of detector response after irradiation. Instead of radionuclide activity measurement using radiometric methods, the concentration of stable non-gaseous nuclides generated by transmutation in the detector is measured using analytical methods like mass spectrometry. Prospective elements and nuclear reactions for transmutation detectors are listed and initial experimental results are given. The transmutation detector method could be used primarily for long-term measurement of neutron fluence in fission nuclear reactors, but in principle it could be used for any type of radiation that can cause transmutation of nuclides in detectors. This method could also be used for measurement in accelerators or fusion reactors.

  18. Air Plasma-Sprayed La2Zr2O7-SrZrO3 Composite Thermal Barrier Coating Subjected to CaO-MgO-Al2O3-SiO2 (CMAS)

    Science.gov (United States)

    Cai, Lili; Ma, Wen; Ma, Bole; Guo, Feng; Chen, Weidong; Dong, Hongying; Shuang, Yingchai

    2017-08-01

    La2Zr2O7-SrZrO3 composite thermal barrier coatings (TBCs) were prepared by air plasma spray (APS). The La2Zr2O7-SrZrO3 composite TBCs covered with calcium-magnesium-aluminum-silicate (CMAS) powder, as well as the powder mixture of CMAS and spray-dried La2Zr2O7-SrZrO3 composite powder, were heat-treated at 1250 °C in air for 1, 4, 8, and 12 h. The phase constituents and microstructures of the reaction products were characterized by x-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. Experimental results showed that the La2Zr2O7-SrZrO3 composite TBCs had higher CMAS resistance than 8YSZ coating. A dense new layer developed between CMAS and La2Zr2O7-SrZrO3 composite TBCs during interaction, and this new layer consisted mostly of apatite (Ca2La8(SiO4)6O2) and c-ZrO2. The newly developed layer effectively protected the La2Zr2O7-SrZrO3 composite TBCs from further CMAS attack.

  19. Conduction mechanism in electron beam irradiated Al/n-Si Schottky diode

    International Nuclear Information System (INIS)

    Vali, Indudhar Panduranga; Shetty, Pramoda Kumara; Mahesha, M.G.; Petwal, V.C.

    2016-01-01

    In the high energy physics experiments, silicon based diodes are used to fabricate radiation detector to detect the charged particles. The Schottky barrier diodes have been studied extensively to understand the behavior of metal semiconductor interface, since such interfaces have been utilized as typical contacts in silicon devices. Because of surface states, interfacial layer, microscopic clusters of metal-semiconductor phases and other effects, it is difficult to fabricate junctions with barriers near the ideal values predicted from the work functions of the two isolated materials, therefore measured barrier heights are used in the device design. In this work, the Al/n-Si Schottky contacts are employed to study the diode parameters (Schottky barrier height and ideality factor), where the Schottky contacts were fabricated on electron beam irradiated silicon wafers. The interface behavior between electron irradiated Si wafer and post metal deposition is so far not reported. This method could be an alternative way to tailor the Schottky barrier height (SBH) without subjecting semiconductor sample to pre chemical and/or post heat treatments during fabrication

  20. An edge-readout, multilayer detector for positron emission tomography.

    Science.gov (United States)

    Li, Xin; Ruiz-Gonzalez, Maria; Furenlid, Lars R

    2018-04-10

    We present a novel gamma-ray-detector design based on total internal reflection (TIR) of scintillation photons within a crystal that addresses many limitations of traditional PET detectors. Our approach has appealing features, including submillimeter lateral resolution, DOI positioning from layer thickness, and excellent energy resolution. The design places light sensors on the edges of a stack of scintillator slabs separated by small air gaps and exploits the phenomenon that more than 80% of scintillation light emitted during a gamma-ray event reaches the edges of a thin crystal with polished faces due to TIR. Gamma-ray stopping power is achieved by stacking multiple layers, and DOI is determined by which layer the gamma ray interacts in. The concept of edge readouts of a thin slab was verified by Monte Carlo simulation of scintillation light transport. An LYSO crystal of dimensions 50.8 mm × 50.8 mm × 3.0 mm was modeled with five rectangular SiPMs placed along each edge face. The mean-detector-response functions (MDRFs) were calculated by simulating signals from 511 keV gamma-ray interactions in a grid of locations. Simulations were carried out to study the influence of choice of scintillator material and dimensions, gamma-ray photon energies, introduction of laser or mechanically induced optical barriers (LIOBs, MIOBs), and refractive indices of optical-coupling media and SiPM windows. We also analyzed timing performance including influence of gamma-ray interaction position and presence of optical barriers. We also modeled and built a prototype detector, a 27.4 mm × 27.4 mm × 3.0 mm CsI(Tl) crystal with 4 SiPMs per edge to experimentally validate the results predicted by the simulations. The prototype detector used CsI(Tl) crystals from Proteus outfitted with 16 Hamamatsu model S13360-6050PE MPPCs read out by an AiT-16-channel readout. The MDRFs were measured by scanning the detector with a collimated beam of 662-keV photons from a 137 Cs