Development of a compact scintillator-based high-resolution Compton camera for molecular imaging

Energy Technology Data Exchange (ETDEWEB)

Kishimoto, A., E-mail: daphne3h-aya@ruri.waseda.jp [Research Institute for Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku, Tokyo (Japan); Kataoka, J.; Koide, A.; Sueoka, K.; Iwamoto, Y.; Taya, T. [Research Institute for Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku, Tokyo (Japan); Ohsuka, S. [Central Research Laboratory, Hamamatsu Photonics K.K., 5000 Hirakuchi, Hamakita-ku, Hamamatsu, Shizuoka (Japan)

2017-02-11

The Compton camera, which shows gamma-ray distribution utilizing the kinematics of Compton scattering, is a promising detector capable of imaging across a wide range of energy. In this study, we aim to construct a small-animal molecular imaging system in a wide energy range by using the Compton camera. We developed a compact medical Compton camera based on a Ce-doped Gd{sub 3}Al{sub 2}Ga{sub 3}O{sub 12} (Ce:GAGG) scintillator and multi-pixel photon counter (MPPC). A basic performance confirmed that for 662 keV, the typical energy resolution was 7.4 % (FWHM) and the angular resolution was 4.5° (FWHM). We then used the medical Compton camera to conduct imaging experiments based on a 3-D imaging reconstruction algorithm using the multi-angle data acquisition method. The result confirmed that for a {sup 137}Cs point source at a distance of 4 cm, the image had a spatial resolution of 3.1 mm (FWHM). Furthermore, we succeeded in producing 3-D multi-color image of different simultaneous energy sources ({sup 22}Na [511 keV], {sup 137}Cs [662 keV], and {sup 54}Mn [834 keV]).

Al{sub 0.2}Ga{sub 0.8}As X-ray photodiodes for X-ray spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Whitaker, M.D.C., E-mail: M.Whitaker@sussex.ac.uk; Lioliou, G.; Butera, S.; Barnett, A.M.

2016-12-21

Three custom-made Al{sub 0.2}Ga{sub 0.8}As p-i-n mesa X-ray photodiodes (200 µm diameter, 3 µm i layer) were electrically characterised and investigated for their response to illumination with soft X-rays from an {sup 55}Fe radioisotope X-ray source (Mn Kα = 5.9 keV; Mn Kβ = 6.49 keV). The AlGaAs photodiodes were shown to be suitable for photon counting X-ray spectroscopy at room temperature. When coupled to a custom-made low-noise charge-sensitive preamplifier, a mean energy resolution (as quantified by the full width at half maximum of the 5.9 keV photopeak) of 1.24 keV was measured at room temperature. Parameters such as the depletion width (1.92 µm at 10 V), charge trapping noise (61.7 e{sup −} rms ENC at 5 V, negligible at 10 V) and the electronic noise components (known dielectric noise (63.4 e{sup −} rms), series white noise (27.7 e{sup −} rms), parallel white noise (9.5 e{sup −} rms) and 1/f series noise (2.2 e{sup −} rms) at 10 V reverse bias) affecting the achieved energy resolution were computed. The estimated charge trapping noise and mean energy resolution were compared to similar materials (e.g. Al{sub 0.8}Ga{sub 0.2}As) previously reported, and discussed. These results are the first demonstration of photon counting X-ray spectroscopy with Al{sub 0.2}Ga{sub 0.8}As reported to date.

PTR, PCR and Energy Resolution Study of GAGG:Ce Scintillator

Science.gov (United States)

Limkitjaroenporn, Pruittipol; Hongtong, Wiraporn; Kim, Hong Joo; Kaewkhao, Jakrapong

2018-03-01

In this paper, the peak to total ratio (PTR), the peak to Compton ratio (PCR) and the energy resolution of cerium doped gadolinium aluminium gallium garnet (GAGG:Ce) scintillator are measured in the range of energy from 511 keV to 1332 keV using the radioactive source Na-22, Cs-137 and Co-60. The crystal is coupled with the PMT number R1306 and analyzed by the nuclear instrument module (NIM). The results found that the PTR and PCR of GAGG:Ce scintillator decrease with the increasing of energy. The results of energy resolution show the trend is decrease with the increasing of energy which corresponding to the higher energy resolution at higher energy. Moreover the energy resolution found to be linearly with.

Performance evaluation of a sub-millimeter spatial resolution PET detector module using a digital silicon photomultiplier coupled LGSO array

Energy Technology Data Exchange (ETDEWEB)

Leem, Hyun Tae [Molecular Imaging Research & Education (MiRe) Laboratory, Department of Electronic Engineering, Sogang University, Seoul (Korea, Republic of); Choi, Yong, E-mail: ychoi@sogang.ac.kr [Molecular Imaging Research & Education (MiRe) Laboratory, Department of Electronic Engineering, Sogang University, Seoul (Korea, Republic of); Kim, Kyu Bom; Lee, Sangwon [Molecular Imaging Research & Education (MiRe) Laboratory, Department of Electronic Engineering, Sogang University, Seoul (Korea, Republic of); Yamamoto, Seiichi [Department of Medical Technology, Nagoya University Graduate School of Medicine, Nagoya (Japan); Yeom, Jung-Yeol, E-mail: jungyeol@korea.ac.kr [School of Biomedical Engineering, Korea University, Seoul (Korea, Republic of)

2017-02-21

In positron emission tomography (PET) for breast, brain and small animal imaging, the spatial resolution of a PET detector is crucial to obtain high quality PET images. In this study, a PET detector for sub-millimeter spatial resolution imaging purpose was assembled using 4×4 pixels of a digital silicon photomultiplier (dSiPM, DPC-3200-22-44, Philips) coupled with a 15×15 LGSO array with BaSO{sub 4} reflector, and a 1 mm thick acrylic light guide for light distribution between the dSiPM pixels. The active area of each dSiPM pixel was 3.2×3.9 mm{sup 2} and the size of each LGSO scintillator element was 0.7×0.7×6 mm{sup 3}. In this paper, we experimentally demonstrated the performance of the PET detector by measuring the energy resolution, 2D flood map, peak to valley (P/V) ratio, and coincidence resolving time (CRT). All measurements were performed at a temperature of 10±1 ℃. The average energy resolution was 15.6% (without correcting for saturation effects) at 511 keV and the best CRT was 242±5 ps. The 2D flood map obtained with an energy window of 400–600 keV demonstrated clear identification of all pixels, and the average P/V ratio of the X- and Y-directions were 7.31 and 7.81, respectively. This study demonstrated that the PET detector could be suitable for application in high resolution PET while achieving good timing resolution.

On the limiting resolution of silicon detectors for short-range particles

Energy Technology Data Exchange (ETDEWEB)

Verbitskaya, E M; Eremin, V K; Malyarenko, A M; Strokan, N B; Sukhanov, V L

1986-10-20

The transition to planar tecnology has lead to substantial improvement of energy resolution of Si detectors of strongly ionizing nuclear radiations. For 5 MeV ..cap alpha..-particles the resolution (delta/sub ..cap alpha../) is equal 9.2 keV. The application of the method of local diffusion permitted to attain delta/sub ..cap alpha../=8.1-8.4 keV. The comparison of the new resolution level with the theoretical limit is carried out. It is shown that the combination of partial contributions of fluctuations caused by fundamental mechanisms practically determined delta/sub ..cap alpha../ of obtained detectors.

Total bremsstrahlung spectra of thick lead compounds produced by {sup 90}Sr beta emitter in photon energy region of 10–100 keV

Energy Technology Data Exchange (ETDEWEB)

Sharma, Suhansar Jit [Department of Physics, B.B.S.B Polytechnic, Fatehgarh Sahib, Punjab (India); Singh, Tajinder, E-mail: tajindersingh2k9@gmail.com [Department of Physics, Mata Gujri College, Fatehgarh Sahib, Punjab (India); Singh, Doordarshi [Department of Mechanical Engineering, B.B.S.B Engineering College, Fatehgarh Sahib, Punjab (India); Singh, Amrit [Department of Physics, Baba Ajay Singh Khalsa College, Gurdas Nangal, Gurdaspur, Punjab (India); Dhaliwal, A.S. [Department of Physics, Sant Longowal Institute of Engineering & Technology, Longowal (Sangrur), Punjab (India)

2017-06-15

Highlights: • Total bremsstrahlung spectra in thick targets of Pb compounds by {sup 90}Sr in energy range 10–100 keV. • Experimental results show better agreement with the model which includes PB in SA up to 30 keV. • At higher photon energy region 30–100 keV the model which describes OB is more accurate. • Experimental results show positive deviations from the entire models at higher energy end spectrum. - Abstract: The total bremsstrahlung spectra in the thick targets of lead acetate trihydrate (Pb(CH{sub 3}COO){sub 2}·3H{sub 2}O), lead nitrate Pb(NO{sub 3}){sub 2} and lead chloride (PbCl{sub 2}) produced by {sup 90}Sr beta particles have been investigated in the photon energy region of 10–100 keV. The experimental bremsstrahlung spectra have been compared with the theoretical models Elwert corrected (non relativistic) Bethe Heitler theory, modified Elwert factor (relativistic) Bethe Heitler theory for ordinary bremsstrahlung and modified Elwert factor (relativistic) Bethe Heitler theory which includes polarization bremsstrahlung in the stripped atom approximation. The experimental results show better agreement with theoretical model that includes polarization bremsstrahlung in stripped approximation in the photon energy region below 30 keV. However, at higher photon energy region 30–100 keV, the theoretical model which describes ordinary bremsstrahlung is more accurate to describe the experimental bremsstrahlung spectra. The experimental results show positive deviations from the entire theoretical models at higher energy end of the spectrum. The results indicate that polarization bremsstrahlung plays important role in the formation of total bremsstrahlung spectra in lead compounds produced by continuous beta particles at low photon energy region of 10–30 keV.

Luminescence and scintillation timing characteristics of (Lu{sub x}Gd{sub 2−x})SiO{sub 5}:Ce single crystals

Energy Technology Data Exchange (ETDEWEB)

Yawai, Nattasuda; Chewpraditkul, Warut; Sakthong, Ongsa [Faculty of Science, King Mongkut' s University of Technology Thonburi, Bangkok10140 (Thailand); Chewpraditkul, Weerapong, E-mail: weerapong.che@kmutt.ac.th [Faculty of Science, King Mongkut' s University of Technology Thonburi, Bangkok10140 (Thailand); Wantong, Kriangkrai [Faculty of Science, King Mongkut' s University of Technology Thonburi, Bangkok10140 (Thailand); Szczesniak, Tomasz; Swiderski, Lukasz; Moszynski, Marek [National Centre for Nuclear Research, A. Soltana 7, PL 05-400 Otwock-Swierk (Poland); Sidletskiy, Oleg [Institute for Scintillation Materials NAS of Ukraine, 60 Nauky Avenue, 61001 Kharkiv (Ukraine)

2017-02-01

The luminescence and scintillation characteristics of cerium-doped lutetium-gadolinium orthosilicate (Lu{sub x}Gd{sub 2−x}SiO{sub 5}:Ce; x=0, 0.8, 1.8) single crystals were investigated. At 662 keV γ-rays, the light yield of 29,800±3000 ph MeV{sup −1} obtained for Lu{sub 1.8}Gd{sub 0.2}SiO{sub 5}:Ce is higher than that of 20,200±2000 and 11,800±1200 ph MeV{sup −1} obtained for Lu{sub 0.8}Gd{sub 1.2}SiO{sub 5}:Ce and Gd{sub 2}SiO{sub 5}:Ce, respectively. The fast component decay time of 32, 18 and 17 ns was measured in the scintillation decay of Gd{sub 2}SiO{sub 5}:Ce, Lu{sub 0.8}Gd{sub 1.2}SiO{sub 5}:Ce and Lu{sub 1.8}Gd{sub 0.2}SiO{sub 5}:Ce, respectively. The coincidence time spectra for 511 keV annihilation quanta were measured in reference to a fast BaF{sub 2} detector and time resolution was discussed in terms of a number of photoelectrons and decay time of the fast component. The mass attenuation coefficient for studied crystals at 60 and 662 keV γ-rays was also evaluated and discussed. - Highlights: • Scintillation timing characteristics of Lu{sub x}Gd{sub 2−x}SiO{sub 5}:Ce crystals are studied. • Lu{sub 1.8}Gd{sub 0.2}SiO{sub 5}:Ce exhibits excellent light yield and timing response. • Energy resolution of 6% @662 keV is obtained for Lu{sub 0.8}Gd{sub 1.2}SiO{sub 5}:Ce. • Coincidence time resolution of 368 ps is obtained for Lu{sub 1.8}Gd{sub 0.2}SiO{sub 5}:Ce.

Characteristic K-shell x-ray production by protons below 500 keV

International Nuclear Information System (INIS)

Wheeler, R.M.; Chaturvedi, R.P.; Zander, A.R.

1974-01-01

The total thick target yield of K-shell x-rays produced in Ni by incident protons over the energy range 90 to 415 keV was measured. Similar measurements with 130 to 415 keV protons were made for Ti, Mn, Fe, Cu, and Zn. The East Texas State University 150 keV Cockcroft--Walton accelerator was used to study Ni K-shell x-rays produced by 90 to 150 keV protons. The remaining data were taken with the SUNY College at Cortland 400 keV Van de Graaff generator. The characteristic x-rays were measured with high resolution Si(Li) detectors. Using the most recent values of K-shell fluorescent yields, x-ray ionization cross sections were calculated and compared to theoretical predictions based on the binary encounter approximation (BEA) model. It was found that even though the data were lower than those expected by the BEA theory, they lie on a universal curve. A comprehensive summary of x-ray ionization cross section references covering the proton energy range up to 500 keV is also included. Possible applications of low energy accelerators (E/sub p/ less than or equal to 500 keV) for further experimental work is discussed

The interaction between Xe and F in Si (1 0 0) pre-amorphised with 20 keV Xe and implanted with low energy BF{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Werner, M. [Joule Physics Laboratory, Institute of Materials Research, University of Salford, Salford M54WT (United Kingdom)]. E-mail: m.werner@pgr.salford.ac.uk; Berg, J.A. van den [Joule Physics Laboratory, Institute of Materials Research, University of Salford, Salford M54WT (United Kingdom); Armour, D.G. [Joule Physics Laboratory, Institute of Materials Research, University of Salford, Salford M54WT (United Kingdom); Carter, G. [Joule Physics Laboratory, Institute of Materials Research, University of Salford, Salford M54WT (United Kingdom); Feudel, T. [AMD Saxony LLC and Co. KG, Wilschdorfer Landstrasse, 101 D-01109 Dresden (Italy); Herden, M. [AMD Saxony LLC and Co. KG, Wilschdorfer Landstrasse, 101 D-01109 Dresden (Italy); Bersani, M. [ITC IRST, 38050 Povo, Trento (Italy); Giubertoni, D. [ITC IRST, 38050 Povo, Trento (Italy); Bailey, P. [CCLRC Daresbury Laboratory, Daresbury WA44A (United Kingdom); Noakes, T.C.Q. [CCLRC Daresbury Laboratory, Daresbury WA44A (United Kingdom)

2004-12-15

The pre-amorphisation of Si by Xe{sup +} ions, before source/drain and extension implants, is an attractive alternative to Ge{sup +} or Si{sup +}, as it produces sharper amorphous/crystalline interfaces. Si (1 0 0) samples pre-amorphised with 20 keV Xe{sup +} to a nominal dose of 2E14 cm{sup -2} were implanted with 1 and 3 keV BF{sub 2} {sup +} to doses of 7E14 cm{sup -2}. Samples were annealed at temperatures ranging from 600 to 1130 deg. C and investigated by medium energy ion scattering (MEIS) and secondary ion mass spectrometry (SIMS). Following annealing, it was observed that implanted Xe has interacted with F originating from the BF{sub 2} {sup +} implant. MEIS studies showed that for all annealing conditions, approximately half of the Xe accumulated at depths of 7 nm for the 1 keV and at 13 nm for the 3 keV BF{sub 2} {sup +} implant. This equates to the end of range of B and F within the amorphous Si. SIMS showed that in the pre-amorphised samples, approximately 10% of the F migrates into the bulk and is trapped at the same depth in a {approx}1:1 ratio to Xe. A small fraction of the implanted B is also trapped. The effect is interpreted in terms of the formation of a defect structure within the amorphised Si, leading to F stabilised Xe bubble or XeF compound formation.

Calibration efficiency of HPGe detector in the 50-1800 KeV energy range; Calibracao em eficiencia de um detector HPGe na faixa de energias 50 - 1800KeV

Energy Technology Data Exchange (ETDEWEB)

Venturini, Luzia [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Servico de Monitoracao Ambiental

1996-07-01

This paper describes the efficiency of an HPGe detector in the 50 - 1800 keV energy range, for two geometries for water measurements: Marinelli breaker (850 ml) and a polyethylene flask (100 ml). The experimental data were corrected for the summing effect and fitted to a continuous, differentiable and energy dependent function given by 1n({epsilon})=b{sub 0}+b{sub 1}.1n(E/E{sub 0})+ {beta}.1n(E/E{sub 0}){sup 2}, where {beta} = b{sub 2} if E>E{sub 0} and {beta} =a{sub 2} if E {<=}E{sub 0}; {epsilon} = the full absorption peak efficiency; E is the gamma-ray energy and {l_brace}b{sub 0}, b{sub 1}, b{sub 2}, a{sub 2}, E{sub 0} {r_brace} is the parameter set to be fitted. (author)

Synthesis of gold and silver nanoparticles by electron irradiation at 5-15 keV energy

Energy Technology Data Exchange (ETDEWEB)

Mahapatra, S K; Bogle, K A; Dhole, S D; Bhoraskar, V N [Microtron Accelerator Laboratory, Department of Physics, University of Pune, Pune-411007 (India)

2007-04-04

Thin coatings ({approx}10 {mu}m) made from a mixture of polyvinyl alcohol (PVA) and HAuCl{sub 4} or PVA and AgNO{sub 3} on quartz plates were irradiated with 5-15 keV electrons, at room temperature. The electron energy was varied from coating to coating in the range of 5-15 keV, but electron fluence was kept constant at {approx}10{sup 15} e cm{sup -2}. Samples were characterized by the UV-vis, XRD, SEM and TEM techniques. The plasmon absorption peaks at {approx}511 and {approx}442 nm confirmed the formation of gold and silver nanoparticles in the respective electron-irradiated coatings. The XRD, SEM and TEM measurements reveal that the average size of the particles could be tailored in the range of 130-50 nm for gold and from 150-40 nm for silver by varying the electron energy in the range of 5-15 keV. These particles of gold and silver embedded in the polymer could also be separated by dissolving the coatings in distilled water.

Measurement of high-energy (10–60 keV) x-ray spectral line widths with eV accuracy

Energy Technology Data Exchange (ETDEWEB)

Seely, J. F., E-mail: seelyjf@gmail.com; Feldman, U. [Artep Inc., 2922 Excelsior Springs Court, Ellicott City, Maryland 21042 (United States); Glover, J. L.; Hudson, L. T.; Ralchenko, Y.; Henins, Albert [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Pereira, N. [Ecopulse Inc., P. O. Box 528, Springfield, Virginia 22152 (United States); Di Stefano, C. A.; Kuranz, C. C.; Drake, R. P. [University of Michigan, Ann Arbor, Michigan 48109 (United States); Chen, Hui; Williams, G. J.; Park, J. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

2014-11-15

A high resolution crystal spectrometer utilizing a crystal in transmission geometry has been developed and experimentally optimized to measure the widths of emission lines in the 10–60 keV energy range with eV accuracy. The spectrometer achieves high spectral resolution by utilizing crystal planes with small lattice spacings (down to 2d = 0.099 nm), a large crystal bending radius and Rowland circle diameter (965 mm), and an image plate detector with high spatial resolution (60 μm in the case of the Fuji TR image plate). High resolution W L-shell and K-shell laboratory test spectra in the 10–60 keV range and Ho K-shell spectra near 47 keV recorded at the LLNL Titan laser facility are presented. The Ho K-shell spectra are the highest resolution hard x-ray spectra recorded from a solid target irradiated by a high-intensity laser.

56Fe resonance parameters for neutron energies up to 850 keV

International Nuclear Information System (INIS)

Perey, C.M.; Perey, F.G.; Harvey, J.A.; Hill, N.W.; Larson, N.M.

1990-12-01

High-resolution neutron measurements for 56 Fe-enriched iron targets were made at the Oak Ridge Electron Linear Accelerator (ORELA) in transmission below 20 MeV and in differential elastic scattering below 5 MeV. Transmission measurements were also performed with a natural iron target below 160 keV. The transmission data were analyzed from 5 to 850 keV with the multilevel R-matrix code SAMMY which uses Bayes' theorem for the fitting process. This code provides energies and neutron widths of the resonances inside the 5- to 850-keV energy region, as well as possible parameterization for resonances external to the analyzed region to describe the smooth cross section from a few eV to 850 keV. The resulting set of resonance parameters yields the accepted values for the thermal total and capture cross sections. The differential elastic-scattering data at several scattering angles were compared to theoretical calculations from 40 to 850 keV using the R-matrix code RFUNC based on the Blatt-Biedenharn formalism. Various combinations of spin and parity were tried to predict cross sections for the well defined ell > 0 resonances; comparison of these predictions with the data allowed us to determine the most likely spin and parity assignments for these resonances. The results of a capture data analysis by Corvi et al. (COR84), from 2 to 350 keV, were combined with our results to obtain the radiation widths of the resonances below 350 keV observed in transmission, capture, and differential elastic-scattering experiments

New generation of efficient high resolution detector for 30-100 keV photons

DEFF Research Database (Denmark)

Olsen, Ulrik Lund

between pores. The potential of the structured scintillator is explored through Monte Carlo simulations. A spatial resolution of 1 µm is obtainable and for scintillators with a resolution between 1 µm and 8 µm the efficiency could be more than 15 times higher than a regular scintillator with corresponding...... detector. This establishes an inverse correlation between the spatial resolution and the detection efficiency which limits the performance of existing x-ray detectors. The purpose of this Ph.D. project is to explore alternative paths of research, to develop x-ray detectors for the 30-100 keV energy range...... with single micrometre resolution without compromising efficiency. A number of detector types have been evaluated for this purpose. Structured scintillators are found to exhibit a high potential in terms of performance and also in terms of realizing an actual detector. The structured scintillator consists...

Reducing the effects of metal artefact using high keV monoenergetic reconstruction of dual energy CT (DECT) in hip replacements

Energy Technology Data Exchange (ETDEWEB)

Lewis, Mark [Norfolk and Norwich University Hospital, Norwich (United Kingdom); Norwich Radiology Academy, Norwich (United Kingdom); Reid, Karen [Norfolk and Norwich University Hospital, Norwich (United Kingdom); Toms, Andoni P. [Norfolk and Norwich University Hospital and University of East Anglia, Norwich (United Kingdom)

2013-02-15

The aim of this study was to determine whether high keV monoenergetic reconstruction of dual energy computed tomography (DECT) could be used to overcome the effects of beam hardening artefact that arise from preferential deflection of low energy photons. Two phantoms were used: a Charnley total hip replacement set in gelatine and a Catphan 500. DECT datasets were acquired at 100, 200 and 400 mA (Siemens Definition Flash, 100 and 140 kVp) and reconstructed using a standard combined algorithm (1:1) and then as monoenergetic reconstructions at 10 keV intervals from 40 to 190 keV. Semi-automated segmentation with threshold inpainting was used to obtain the attenuation values and standard deviation (SD) of the streak artefact. High contrast line pair resolution and background noise were assessed using the Catphan 500. Streak artefact is progressively reduced with increasing keV monoenergetic reconstructions. Reconstruction of a 400 mA acquisition at 150 keV results in reduction in the volume of streak artefact from 65 cm{sup 3} to 17 cm{sup 3} (74 %). There was a decrease in the contrast to noise ratio (CNR) at higher tube voltages, with the peak CNR seen at 70-80 keV. High contrast spatial resolution was maintained at high keV values. Monoenergetic reconstruction of dual energy CT at increasing theoretical kilovoltages reduces the streak artefact produced by beam hardening from orthopaedic prostheses, accompanied by a modest increase in heterogeneity of background image attenuation, and decrease in contrast to noise ratio, but no deterioration in high contrast line pair resolution. (orig.)

Elastic and inelastic processes in He/sup +/-H/sub 2/ collisions between 2 and 30 keV

Energy Technology Data Exchange (ETDEWEB)

Bergnes, C.; Bordenave-Montesquieu, D.; Boutonnet, A.; Nouet, P.; Dagnac, R.

1986-10-14

The elastic and inelastic processes have been studied for scattering of He/sup +/ ions by H/sub 2/ molecules between 2 and 30 keV in the angular range from 10' to 3/sup 0/ by an energy loss technique. The analysis of elastic energy loss against E/sub 0/theta/sup 2/ shows that the incident ion is scattered by the entire molecule at low energies whereas at high energies it is scattered by only one atom in the target. Comparison of the relative probabilities of the various excitation processes with the isoelectronic system He/sup +/-He demonstrates the different behaviours of a molecular target in the excitation mechanism.

Neutron fluence and energy reconstruction with the IRSN recoil detector μ-TPC at 27 keV, 144 keV and 565 keV

Energy Technology Data Exchange (ETDEWEB)

Maire, D.; Lebreton, L.; Richer, J.P. [IRSN, PRP-HOM, SDE, LMDN, 13115 Saint Paul-Lez-Durance (France); Bosson, G.; Bourrion, O.; Guillaudin, O.; Riffard, Q.; Santos, D. [CNRS/IN2P3-UJF-INPG, LPSC, 38000 Grenoble (France)

2015-07-01

The French Institute for Radioprotection and Nuclear Safety (IRSN), associated to the French Metrology Institute (LNE), is developing a time projection chamber using a Micromegas anode: μ-TPC. This work is carried out in collaboration with the Laboratory of Subatomic Physics and Cosmology (LPSC). The aim is to characterize with a primary procedure the energy distribution of neutron fluence in the energy range 8 keV - 1 MeV. The time projection chambers are gaseous detectors, which are able to measure charged particles energy and to reconstruct their track if a pixelated anode is used. In our case, the gas is used as a (n, p) converter in order to detect neutrons down to few keV. Coming from elastic collisions with neutrons, recoil protons lose a part of their kinetic energy by ionizing the gas. The ionization electrons are drifted toward a pixelated anode (2D projection), read at 50 MHz by a self-triggered electronic system to obtain the third track dimension. The neutron energy is reconstructed event by event thanks to proton scattering angle and proton energy measurements. The scattering angle is deduced from the 3D track. The proton energy is obtained by charge collection measurements, knowing the ionization quenching factor (i.e. the part of proton kinetic energy lost by ionizing the gas). The fluence is calculated thanks to the detected events number and the simulated detector response. The μ-TPC is a new reliable detector which enables to measure energy distribution of the neutron fluence without deconvolution or neutron calibration contrary to usual gaseous counters. The μ-TPC is still being developed and measurements have been carried out at the AMANDE facility, with neutrons energies going from 8 keV to 565 keV. After the context and the μ-TPC working principle presentation, measurements of the neutron energy and fluence at 27.2 keV, 144 keV and 565 keV are shown and compared to the complete detector simulation. This work shows the first direct

High-resolution ion-implanted silicon detectors

International Nuclear Information System (INIS)

von Borany, J.; Schmidt, B.

1985-01-01

An account is given of the properties of silicon detectors developed at the Central Institute of Nuclear Research of the Academy of Sciences of the German Democratic Republic (Rossendorf) and made by a special planar technology using ion implantation, anodic oxidation, thermal oxidation in an oxygen atmosphere containing HCl, and annealing by pulses of 10--20 msec duration. The resolution for α particles of 5.5 MeV energy was 11.2 keV (active area A 2 ). The detectors were characterized by a low intrinsic noise (< or =5 keV), so that they could be used for spectrometry of low-energy electrons (E/sub e/< or =250 keV). In a certain range of energies (E/sub x/ = 15--60 keV) it was possible to use these detectors for spectrometry of x rays at room temperature. Examples and results of applications of detectors in radiation chemistry (investigations of backscattering of particles and nuclear reaction spectroscopy) are given. The feasibility of annealing of radiation defects in such detectors after irradiation with a large dose of charged particles is considered

Scintillation properties of Ce:(La,Gd){sub 2}Si{sub 2}O{sub 7} at high temperatures

Energy Technology Data Exchange (ETDEWEB)

Kurosawa, Shunsuke, E-mail: kurosawa@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Miyagi (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Miyagi (Japan); Shishido, Toetsu; Sugawara, Takamasa; Nomura, Akiko; Yubuta, Kunio; Suzuki, Akira; Murakami, Rikito [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Miyagi (Japan); Pejchal, Jan [New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Miyagi (Japan); Institute of Physics, AS CR, Cukrovarnická 10, 162 53 Prague (Czech Republic); Yokota, Yuui; Kamada, Kei [New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Miyagi (Japan); Yoshikawa, Akira [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Miyagi (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Miyagi (Japan); C and A Corporation, 6-6-40 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8577 (Japan)

2015-02-01

Temperature dependence of scintillation properties was investigated for (Ce{sub 0.01}, Gd{sub 0.90}, La{sub 0.09}){sub 2}Si{sub 2}O{sub 7} grown by floating zone method. The light output over 35,000 photons/MeV was found constant in the temperature range from 0 °C to 150 °C. In addition, FWHM energy resolution of Ce:La-GPS (roughly 7–8%) at 662 keV remained constant up to 100 °C. Thus, this crystal can be applied to oil well logging or other radiation detection application at high temperature conditions.

Energy dependence of the air kerma response of a liquid ionization chamber at photon energies between 8 keV and 1250 keV

International Nuclear Information System (INIS)

Hilgers, G.; Bahar-Gogani, J.; Wickman, G.

2002-01-01

Full text: In its recent reports on cardiovascular brachytherapy the DGMP recommends the source strength of brachytherapy sources being characterized in terms of absorbed dose to water at a distance of 2 mm from the central axis of the source. As a consequence, the response of a detector suitable for characterizing such sources with respect to absorbed dose to water should depend only to a small extent on radiation energy. Additionally, the detection volume of the detector has to be sufficiently small for the necessary spatial resolution to be obtained. The liquid ionization chamber as described in seems to be a promising means for this type of measurements. The two components of the ionization liquid (TMS and isooctane) can be mixed in a ratio which ensures that the mass-energy absorption coefficient of the resulting mixture deviates from that of water by less than ±15 % down to photon energies of 10 keV. Due to the high density of the ionization medium, the spacing between the two electrodes of the ionization chamber can be made as small as a few tenths of a millimeter and still the resulting ionization current is sufficiently large. The ionization chamber used in the present investigation is a plane parallel chamber 5 mm in diameter and of 0.3 mm electrode spacing. The ionization medium is a mixture of 40 % TMS and 60 % isooctane. The irradiations were carried out with the ISO wide spectra series with tube voltages between 10 kV and 300 kV and with 137 Cs and 60 Co γ-radiation. As a first step, the response of the liquid ionization chamber was investigated with respect to air kerma instead of absorbed dose to water. Although the mass-energy absorption coefficient of the liquid deviates from that of air by less than ±10 % over the photon energy range, the measured chamber response varies by a factor of about 3.5. Monte Carlo calculations carried out with EGSnrc show a variation of the chamber response smaller than ±20 %. Measurements of the ion yield of the

Characterization of the intrinsic scintillator Cs<sub>2sub>LiCeCl>6sub>

Energy Technology Data Exchange (ETDEWEB)

James, R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2017-10-02

In this work, we report on the scintillation properties of the intrinsic scintillator Cs<sub>2sub>LiCeCl>6sub> (CLCC), which is potentially useful for dual gamma-ray and neutron detection. CLCC is from the elpasolite family with a cubic structure. We grew the crystals at BNL by the vertical Bridgman growth technique. The luminescence spectrum of CLCC showed a doublet with peak maxima at 384 nm and 402 nm. The light yield of CLCC was approximately 20,000 photons/MeV, and the energy resolution was about 6% for 662-keV gamma radiation. A scintillation decay of ~81% of the total light was observed to be ~ 90 nanoseconds.

High energy resolution measurement of the sup 238 U neutron capture yield from 1 to 100 keV

Energy Technology Data Exchange (ETDEWEB)

Macklin, R.L. (Tennessee Univ., Knoxville, TN (United States). Dept. of Nuclear Engineering); Perez, R.B. (Tennessee Univ., Knoxville, TN (United States). Dept. of Nuclear Engineering Oak Ridge National Lab., TN (United States)); De Saussure, G.; Ingle, R.W. (Oak Ridge National Lab., TN (United States))

1991-01-01

The purpose of this work is the precise determination of the {sup 238}U neutron capture yield (i.e. the probability of neutron capture) as a function of neutron energy with the highest available neutron energy resolution. The motivation for this undertaking arises from the central role played by the {sup 238}U neutron capture process in the neutron balance of both thermal reactors and fast breeder reactors. The present measurement was performed using the Oak Ridge Electron Linear Accelerator (ORELA) facility. The pulsed beam of neutrons from the ORELA facility is collimated on a sample of {sup 238}U. The neutron capture rate in the sample is measured, as a function of neutron time-of-flight (TOF) by detecting the {gamma}-rays from the {sup 238}U(n, {gamma}){sup 239}U reaction with a large {gamma}-ray detector surrounding the {sup 238}U sample. At each energy, the capture yield is proportional to the observed capture rate divided by the measured intensity of the neutron beam. The constant of proportionality (the normalization constant) is obtained from the ratio of theoretical to experimentally measured areas under small {sup 238}U resonances where the resonance parameters have been determined from high-resolution {sup 238}U transmission measurements. The cross section for the reaction {sup 238}U(n,{gamma}){sup 239}U can be derived from the measured capture yield if one applies appropriate corrections for multiple scattering and resonance self-shielding. Some 200 {sup 238}U neutron resonances in the energy range from 250 eV to 10 keV have been observed which had not been detected in previous measurements. (author).

Study of vacancy decays in the L-shell photoionization of barium in the excitation energy range of 5.6-30 keV: from L{sub 2} edge to energy high above the thresholds of double L-vacancy production

Energy Technology Data Exchange (ETDEWEB)

Zou, Y [Key Laboratory of Applied Ion Beam Physics (Chinese Educational Ministry), Fudan University, Shanghai 200433 (China); Oura, M [RIKEN Spring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Hutton, R [Lund Observatory, SE-221 00 Lund (Sweden); Yamaoka, H [RIKEN Spring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Takeshima, N [Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan); Takahiro, K [Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan); Kawatsura, K [Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan); Mukoyama, T [Kansai Gaidai University, 16-1 Nakamiyahigashino-cho, Hirakata, Osaka 573-1001 (Japan)

2006-11-28

Photoinduced Ba L x-rays were measured, in the excitation energy range of 5.6-30 keV, by using high-brilliance undulator radiation. The obtained intensity ratios, the excitation-energy independent L{beta}{sub 4}/L{beta}{sub 3}, L{eta}/L{beta}{sub 1}, L{iota}/L{alpha}{sub 1,2}, L{beta}{sub 6}/L{alpha}{sub 1,2} and L{beta}{sub 2,15}/L{alpha}{sub 1,2} as well as the excitation-energy dependent L{beta}{sub 1}/L{alpha}{sub 1,2}, L{beta}{sub 3}/L{alpha}{sub 1,2} and L{beta}{sub 3}/L{beta}{sub 1}, were compared with theoretical calculations, in which the calculations were performed by applying various subsets of the L subshell fluorescence yields and Coster-Kronig yields. Deviations of the theoretical calculations from the experimental results call on improvements in theory for the emission rates. We have also surveyed the L{alpha}{sub 1,2} related x-ray hypersatellite lines in the photoinduced Ba L x-ray spectrum.

Kinetic energies of charged fragments resulting from multifragmentation and asymmetric fission of the C{sub 60} molecule in collisions with monocharged ions (2-130 keV)

Energy Technology Data Exchange (ETDEWEB)

Rentenier, A; Bordenave-Montesquieu, D; Moretto-Capelle, P; Bordenave-Montesquieu, A [Laboratoire CAR-IRSAMC, UMR 5589 CNRS - Universite Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex (France)

2003-04-28

Multifragmentation and asymmetric fission (AF) of the C{sub 60} molecule induced by H{sup +}, H{sub 2}{sup +}, H{sub 3}{sup +} and He{sup +} ions at medium collision energies (2-130 keV) are considered. Momenta and kinetic energies of C{sub n}{sup +} fragment ions (n = 1- 12) are deduced from an analysis of time-of-flight spectra. In multifragmentation processes, momenta are found to be approximately constant when n > 2, a behaviour which explains that the most probable kinetic energy, as well as the width of the kinetic energy distributions, is found to be inversely proportional to the fragment size n; both momenta and kinetic energies are independent of the velocity and nature of the projectile, and hence of the energy deposit. A specific study of the AF shows that the kinetic energies of C{sub 2}{sup +}, C{sub 4}{sup +} and C{sub 6}{sup +} fragments are also independent of the collision velocity and projectile species; a quantitative agreement is found with values deduced from kinetic energy release measurements by another group in electron impact experiments, and the observed decrease when the mass of the light fragment increases is also reproduced. A quantitative comparison of AF and multifragmentation for the n = 2, 4 and 6 fragment ions shows that kinetic energies in AF exceed that in multifragmentation, a result which explains the oscillations observed when momenta or kinetic energies of fragments are plotted against the n-value. The AF yield is also found to scale with the energy deposit in the collision velocity range extending below the velocity at the maximum of the electronic stopping power; except for protons, it remains negligible with respect to multifragmentation as soon as the total energy deposit exceeds about 100 eV.

A new spectroscopic imager for X-rays from 0.5 keV to 150 keV combining a pnCCD and a columnar CsI(Tl) scintillator

Science.gov (United States)

Schlosser, D. M.; Hartmann, R.; Kalok, D.; Bechteler, A.; Abboud, A.; Shokr, M.; Çonka, T.; Pietsch, U.; Strüder, L.

2017-04-01

By combining a low noise fully depleted pnCCD detector with a columnar CsI(Tl) scintillator an energy dispersive spatial resolving detector can be realized with a high quantum efficiency in the range from below 0.5 keV to above 150 keV. The used scintillator system increases the pulse height of gamma-rays converted in the CsI(Tl), due to focusing properties of the columnar scintillator structure by reducing the event size in indirect detection mode (conversion in the scintillator). In case of direct detection (conversion in the silicon of the pnCCD) the relative energy resolution is 0.7% at 122 keV (FWHM = 850 eV) and the spatial resolution is less than 75 μm. In case of indirect detection the relative energy resolution, integrated over all event sizes is about 9% at 122 keV with an expected spatial precision of below 75 μm.

Intrinsic radioactivity of KSr{sub 2}I{sub 5}:Eu{sup 2+}

Energy Technology Data Exchange (ETDEWEB)

Rust, M.; Melcher, C.; Lukosi, E., E-mail: elukosi@utk.edu

2016-10-11

A current need in nuclear security is an economical, yet high energy resolution (near 2%), scintillation detector suitable for gamma-ray spectroscopy. For current scintillators on the market, there is an inverse relationship between scintillator energy resolution and cost of production. A new promising scintillator, KSr{sub 2}I{sub 5}:Eu{sup 2+}, under development at the University of Tennessee, has achieved an energy resolution of 2.4% at 662 keV at room temperature, with potential growth rates exceeding several millimeters per hour. However, the internal background due to the {sup 40}K content could present a hurdle for effective source detection/identification in nuclear security applications. As a first step in addressing this question, this paper reports on a computational investigation of the intrinsic differential pulse height spectrum (DPHS) generated by {sup 40}K within the KSr{sub 2}I{sub 5}:Eu{sup 2+} scintillator as a function of crystal geometry. It was found that the DPHS remains relatively equal to a constant multiplicative factor of the negatron emission spectrum with a direct increase of the 1.46 MeV photopeak relative height to the negatron spectrum with volume. Further, peak pileup does not readily manifest itself for practical KSr{sub 2}I{sub 5}:Eu{sup 2+} volumes.

Thermoelectrically cooled semiconductor detectors for non-destructive analysis of works of art by means of energy dispersive X-ray fluorescence

CERN Document Server

Cesareo, R; Castellano, A

1999-01-01

Thermoelectrically cooled semiconductor detectors, such as Si-PIN, Si-drift, Cd sub 1 sub - sub x Zn sub x Te and HgI sub 2 , coupled to miniaturized low-power X-ray tubes, are well suited in portable systems for energy-dispersive X-ray fluorescence (EDXRF), analysis of archaeological samples. The Si-PIN detector is characterized by a thickness of about 300 mu m, an area of about 2x3 mm sup 2 , an energy resolution of about 200-250 eV at 5.9 keV and an entrance window of 25-75 mu m. The Si-drift detector has approximately the same area and thickness, but an energy resolution of 155 eV at 5.9 keV. The efficiency of these detectors is around 100% from 4 to 10 keV, and then decreases versus energy, reaching approx 9% at 30 keV. Coupled to a miniaturized 10 kV, 0.1 mA, Ca-anode or to a miniaturized 30 kV, 0.1 mA, W-anode X-ray tubes, portable systems can be constructed, which are able to analyse K-lines of elements up to about silver, and L-lines of heavy elements. The Cd sub 1 sub - sub x Zn sub x Te detector ha...

Bulk superconducting gap of V{sub 3}Si studied by low-energy ultrahigh-resolution photoemission spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Sato, T., E-mail: t-sato@arpes.phys.tohoku.ac.jp [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); Souma, S. [WPI Research Center, Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Nakayama, K. [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); Sugawara, K. [WPI Research Center, Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Toyota, N. [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); Takahashi, T. [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); WPI Research Center, Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

2016-04-15

Highlights: • We report ultrahigh-resolution photoemission spectroscopy of A15 compound V{sub 3}Si. • We found a sharp quasiparticle peak due to superconducting-gap opening. • The surface metallic component is negligibly small in the bulk-sensitive measurement. • We show that V{sub 3}Si is a single-gap s-wave superconductor. - Abstract: We have performed low-energy ultrahigh-resolution photoemission spectroscopy (PES) of A15 compound V{sub 3}Si with a xenon-plasma discharge lamp to elucidate the bulk superconducting gap. Below the superconducting transition temperature (T{sub c} = 15.9 K), we found a sharp quasiparticle peak at the Fermi level in the PES spectrum. The gap spectrum is well fitted by a single s-wave superconducting-gap function together with a dip structure at ∼30 meV suggestive of a strong electron-phonon coupling. The anomalous in-gap state previously observed in the PES measurement with high-energy photons is absent or negligibly small in the present bulk-sensitive measurement. The present PES result shows that V{sub 3}Si is a single-gap s-wave superconductor.

Prospects for realizing a sub-A sub-eV resolution EFTEM

International Nuclear Information System (INIS)

Rose, H.

1999-01-01

The arrangement of a sub-Angstrom and sub-eV resolution energy filtering transmission electron microscope (EFTEM) is outlined. This ideal future analytical microscope is a combination of a scanning transmission (STEM) and a corrected fixed-beam transmission electron microscope (TEM) and operates at voltages between 150 and 300 kV. The ultra resolution EFTEM will consist of a field emission gun followed by a monochromator yielding an energy width below 0.2 eV. The condenser system provides Koehler illumination for the TEM mode and a spot size of about 0.2 nm for the STEM mode. The spherically corrected aplanatic objective lens consists of a coma-free round lens and an integrated hexapole corrector. The formation of the energy loss spectrum is performed by the ultradispersive aberration-free MANDOLINE filter. The filtered intermediate image or the energy loss spectrum, respectively, are imaged onto a Charged-Coupled Device (CCD) array with variable magnification by means of a distortion-free projector system consisting of several quadrupoles and octupoles. For obtaining sub-Angstrom resolution the parasitic mechanical and electromagnetic instabilities must be reduced to such an extent that the information limit is pushed below 0.06 nm. All requirements can be met at the present state of technology. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

High resolution spectroscopy of H+ energy loss in thin carbon film

International Nuclear Information System (INIS)

Matsunami, Noriaki; Kitoh, Kenshin

1991-05-01

The energy loss of ∼100 keV H + transmitted through thin carbon film of ∼7 nm has been measured with the resolution of ∼20 eV. We have observed new energy loss peaks around 210 and 400 eV in addition to the normal energy loss peak around 1 keV. We find that the experimental artifacts, ionization of C K-(290 eV) and impurity inner-shells, extreme non-uniformity of films, events associated with elastic scattering are not responsible for these peaks. The origin of these low energy loss peaks will be discussed. (author)

Study of the double charge-changing collision cross-sections of H{sup +}, D{sup +}, Li{sup +} ions with organic molecules in the energy range 10-50 keV; Etude des sections efficaces de double echange de charges ({sigma}{sub 1-1}) d'ions H{sup +}, D{sup +}, Li{sup +} traversant differents gaz organiques dans une gamme d'energie comprise entre 10 et 50 keV

Energy Technology Data Exchange (ETDEWEB)

Farrokhi, S [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1966-07-01

The variation of the double charge-changing collision cross-sections of H{sup +}, D{sup +}, Li{sup +} ions with organic molecules (CH{sub 4}, C{sub 2}H{sub 6}, C{sub 3}H{sub 8}, C{sub 4}H{sub 10}) in the energy range 10-50 keV has been studied. Several maximums for {sigma}{sub 1-1} = f(E) have been shown. Their existence should be explained by the different possibilities of dissociating the target-molecules. The position of the maximums, for the H{sup +} {yields} H{sup -} and D{sup +} {yields} D{sup -} reactions is in good agreement with that defined by the Massey adiabatic relation. (author) [French] Nous avons etudie la variation de la section efficace de double echange de charges des ions H{sup +}, D{sup +}, Li{sup +} lors de la collision avec les molecules organiques de CH{sub 4}, C{sub 2}H{sub 6}, C{sub 3}H{sub 8}, C{sub 4}H{sub 10} dans la gamme d'energie comprise entre 10 et 50 keV. Les resultats obtenus ont montre plusieurs maximums de {sigma}{sub 1-1} f(E). L'existence de ces maximums pourrait etre expliquee par les differentes possibilites de dissociation des molecules cibles. La position des points maximaux concernant les reactions H{sup +} {yields} H{sup -} et D{sup +} {yields} D{sup -} est en bon accord avec celle definie par la relation adiabatique de MASSEY. (auteur)

Signal yields, energy resolution, and recombination fluctuations in liquid xenon

Science.gov (United States)

Akerib, D. S.; Alsum, S.; Araújo, H. M.; Bai, X.; Bailey, A. J.; Balajthy, J.; Beltrame, P.; Bernard, E. P.; Bernstein, A.; Biesiadzinski, T. P.; Boulton, E. M.; Bramante, R.; Brás, P.; Byram, D.; Cahn, S. B.; Carmona-Benitez, M. C.; Chan, C.; Chiller, A. A.; Chiller, C.; Currie, A.; Cutter, J. E.; Davison, T. J. R.; Dobi, A.; Dobson, J. E. Y.; Druszkiewicz, E.; Edwards, B. N.; Faham, C. H.; Fiorucci, S.; Gaitskell, R. J.; Gehman, V. M.; Ghag, C.; Gibson, K. R.; Gilchriese, M. G. D.; Hall, C. R.; Hanhardt, M.; Haselschwardt, S. J.; Hertel, S. A.; Hogan, D. P.; Horn, M.; Huang, D. Q.; Ignarra, C. M.; Ihm, M.; Jacobsen, R. G.; Ji, W.; Kamdin, K.; Kazkaz, K.; Khaitan, D.; Knoche, R.; Larsen, N. A.; Lee, C.; Lenardo, B. G.; Lesko, K. T.; Lindote, A.; Lopes, M. I.; Manalaysay, A.; Mannino, R. L.; Marzioni, M. F.; McKinsey, D. N.; Mei, D.-M.; Mock, J.; Moongweluwan, M.; Morad, J. A.; Murphy, A. St. J.; Nehrkorn, C.; Nelson, H. N.; Neves, F.; O'Sullivan, K.; Oliver-Mallory, K. C.; Palladino, K. J.; Pease, E. K.; Phelps, P.; Reichhart, L.; Rhyne, C.; Shaw, S.; Shutt, T. A.; Silva, C.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Stephenson, S.; Sumner, T. J.; Szydagis, M.; Taylor, D. J.; Taylor, W. C.; Tennyson, B. P.; Terman, P. A.; Tiedt, D. R.; To, W. H.; Tripathi, M.; Tvrznikova, L.; Uvarov, S.; Verbus, J. R.; Webb, R. C.; White, J. T.; Whitis, T. J.; Witherell, M. S.; Wolfs, F. L. H.; Xu, J.; Yazdani, K.; Young, S. K.; Zhang, C.; LUX Collaboration

2017-01-01

This work presents an analysis of monoenergetic electronic recoil peaks in the dark-matter-search and calibration data from the first underground science run of the Large Underground Xenon (LUX) detector. Liquid xenon charge and light yields for electronic recoil energies between 5.2 and 661.7 keV are measured, as well as the energy resolution for the LUX detector at those same energies. Additionally, there is an interpretation of existing measurements and descriptions of electron-ion recombination fluctuations in liquid xenon as limiting cases of a more general liquid xenon recombination fluctuation model. Measurements of the standard deviation of these fluctuations at monoenergetic electronic recoil peaks exhibit a linear dependence on the number of ions for energy deposits up to 661.7 keV, consistent with previous LUX measurements between 2 and 16 keV with 3H. We highlight similarities in liquid xenon recombination for electronic and nuclear recoils with a comparison of recombination fluctuations measured with low-energy calibration data.

Direct and indirect signal detection of 122 keV photons with a novel detector combining a pnCCD and a CsI(Tl) scintillator

Energy Technology Data Exchange (ETDEWEB)

Schlosser, D.M., E-mail: dieter.schlosser@pnsensor.de [PNSensor GmbH, Sckellstraße 3, 81667 München (Germany); Huth, M.; Hartmann, R. [PNSensor GmbH, Sckellstraße 3, 81667 München (Germany); Abboud, A.; Send, S. [Universität Siegen, Walter-Flex-Straße 3, 57072 Siegen (Germany); Conka-Nurdan, T. [Türkisch-Deutsche Universität, Sakinkaya Cad. 86, Beykoz, 34820 Istanbul (Turkey); Shokr, M.; Pietsch, U. [Universität Siegen, Walter-Flex-Straße 3, 57072 Siegen (Germany); Strüder, L. [PNSensor GmbH, Sckellstraße 3, 81667 München (Germany); Universität Siegen, Walter-Flex-Straße 3, 57072 Siegen (Germany)

2016-01-01

By combining a low noise fully depleted pnCCD detector with a CsI(Tl) scintillator, an energy-dispersive area detector can be realized with a high quantum efficiency (QE) in the range from below 1 keV to above 100 keV. In direct detection mode the pnCCD exhibits a relative energy resolution of 1% at 122 keV and spatial resolution of less than 75 µm, the pixel size of the pnCCD. In the indirect detection mode, i.e. conversion of the incoming X-rays in the scintillator, the measured energy resolution was about 9–13% at 122 keV, depending on the depth of interaction in the scintillator, while the position resolution, extracted with the help of simulations, was 30 µm only. We show simulated data for incident photons of 122 keV and compare the various interaction processes and relevant physical parameters to experimental results obtained with a radioactive {sup 57}Co source. - Highlights: • Position and energy resolving pnCCD+CsI(Tl) detector for energies from 1-150 keV • Detection in the pnCCD (122keV): 1% energy and <75µm spatial resolution • Detection in the scintillator (122keV): 9-12% energy and ~30µm spatial resolution.

VOXES: a high precision X-ray spectrometer for diffused sources with HAPG crystals in the 2–20 keV range

Science.gov (United States)

Scordo, A.; Curceanu, C.; Miliucci, M.; Shi, H.; Sirghi, F.; Zmeskal, J.

2018-04-01

Bragg spectroscopy is one of the best established experimental methods for high energy resolution X-ray measurements and has been widely used in several fields, going from fundamental physics to quantum mechanics tests, synchrotron radiation and X-FEL applications, astronomy, medicine and industry. However, this technique is limited to the measurement of photons produced from well collimated or point-like sources and becomes quite inefficient for photons coming from extended and diffused sources like those, for example, emitted in the exotic atoms radiative transitions. The VOXES project's goal is to realise a prototype of a high resolution and high precision X-ray spectrometer, using Highly Annealed Pyrolitic Graphite (HAPG) crystals in the Von Hamos configuration, working also for extended sources. The aim is to deliver a cost effective system having an energy resolution at the level of eV for X-ray energies from about 2 keV up to tens of keV, able to perform sub-eV precision measurements with non point-like sources. In this paper, the working principle of VOXES, together with first results, are presented.

Installation of high-resolution ERDA in UTTAC at the University of Tsukuba: Determination of the energy resolution and the detection limit for hydrogen

Energy Technology Data Exchange (ETDEWEB)

Sekiba, D., E-mail: sekiba@tac.tsukuba.ac.jp [Institute of Applied Physics, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki 305-8573 (Japan); University of Tsukuba, Tandem Accelerator Complex (UTTAC), Tennodai 1-1-1, Tsukuba, Ibaraki 305-8577 (Japan); Chito, K.; Harayama, I. [Institute of Applied Physics, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki 305-8573 (Japan); Watahiki, Y.; Ishii, S. [University of Tsukuba, Tandem Accelerator Complex (UTTAC), Tennodai 1-1-1, Tsukuba, Ibaraki 305-8577 (Japan); Ozeki, K. [Department of Mechanical Engineering, Ibaraki University, Nakanarusawa 4-12-1, Hitachi, Ibaraki 316-8511 (Japan)

2017-06-15

A newly developed high-resolution elastic recoil detection analysis (HERDA) system installed at the 1 MV Tandetron in UTTAC at the University of Tsukuba is introduced. The effective solid angle of detector, energy resolution and detection limit for hydrogen are, for the first time, determined quantitatively by the measurements on an a-C:H (and D) film deposited on a Si substrate. In the case of a 500 keV {sup 16}O{sup +} as the incident beam, an energy resolution of ∼0.45 keV and a detection limit of ∼3.8 × 10{sup 20} atoms/cm{sup 3} (∼0.18 at.%) with a data acquisition time of ∼310 s are derived.

A sub-millimeter resolution PET detector module using a multi-pixel photon counter array

International Nuclear Information System (INIS)

Song, Tae Yong; Wu Heyu; Komarov, Sergey; Tai, Yuan-Chuan; Siegel, Stefan B

2010-01-01

A PET block detector module using an array of sub-millimeter lutetium oxyorthosilicate (LSO) crystals read out by an array of surface-mount, semiconductor photosensors has been developed. The detector consists of a LSO array, a custom acrylic light guide, a 3 x 3 multi-pixel photon counter (MPPC) array (S10362-11-050P, Hamamatsu Photonics, Japan) and a readout board with a charge division resistor network. The LSO array consists of 100 crystals, each measuring 0.8 x 0.8 x 3 mm 3 and arranged in 0.86 mm pitches. A Monte Carlo simulation was used to aid the design and fabrication of a custom light guide to control distribution of scintillation light over the surface of the MPPC array. The output signals of the nine MPPC are multiplexed by a charge division resistor network to generate four position-encoded analog outputs. Flood image, energy resolution and timing resolution measurements were performed using standard NIM electronics. The linearity of the detector response was investigated using gamma-ray sources of different energies. The 10 x 10 array of 0.8 mm LSO crystals was clearly resolved in the flood image. The average energy resolution and standard deviation were 20.0% full-width at half-maximum (FWHM) and ±5.0%, respectively, at 511 keV. The timing resolution of a single MPPC coupled to a LSO crystal was found to be 857 ps FWHM, and the value for the central region of detector module was 1182 ps FWHM when ±10% energy window was applied. The nonlinear response of a single MPPC when used to read out a single LSO was observed among the corner crystals of the proposed detector module. However, the central region of the detector module exhibits significantly less nonlinearity (6.5% for 511 keV). These results demonstrate that (1) a charge-sharing resistor network can effectively multiplex MPPC signals and reduce the number of output signals without significantly degrading the performance of a PET detector and (2) a custom light guide to permit light sharing

Measurements of energy resolution with hemispheric scintillators

International Nuclear Information System (INIS)

Mendonca, A.C.S.; Binns, D.A.C.; Tauhata, L.; Poledna, R.

1980-01-01

The hemispheric configuration is used for plastic scintillators type NE 102 with the aiming to optimize the light collect. Scintillators at this configuration, with radii of 3,81 cm and 2,54 cm, are showing improvement about 16-17% in the energy resolution, on cilyndric scintillators with the same volume, for gamma rays of 511-1275 KeV. (E.G.) [pt

Imaging of hard X-rays with sub-millimetre spatial resolution by means of a xenon filled MWPC

International Nuclear Information System (INIS)

Bateman, J.E.; Connolly, J.F.

1979-11-01

Results are presented showing that a beam of Eu K X-rays (41.5 keV) can be imaged in a xenon filled (NTP) MWPC with sub-millimetre spatial resolution. In the best case (at low data rates) the predicted physical limit of 0.5 mm fwhm is observed. (author)

Solar neutrino flux at keV energies

Science.gov (United States)

Vitagliano, Edoardo; Redondo, Javier; Raffelt, Georg

2017-12-01

We calculate the solar neutrino and antineutrino flux in the keV energy range. The dominant thermal source processes are photo production (γ e→ e νbar nu), bremsstrahlung (e+Ze→ Ze+e+νbar nu), plasmon decay (γ→νbar nu), and νbar nu emission in free-bound and bound-bound transitions of partially ionized elements heavier than hydrogen and helium. These latter processes dominate in the energy range of a few keV and thus carry information about the solar metallicity. To calculate their rate we use libraries of monochromatic photon radiative opacities in analogy to a previous calculation of solar axion emission. Our overall flux spectrum and many details differ significantly from previous works. While this low-energy flux is not measurable with present-day technology, it could become a significant background for future direct searches for keV-mass sterile neutrino dark matter.

Solar wind ∼0.1-1.5 keV electrons at quiet times

Energy Technology Data Exchange (ETDEWEB)

Tao, Jiawei; Wang, Linghua, E-mail: wanglhwang@gmail.com; Zong, Qiugang; He, Jiansen; Tu, Chuanyi [School of Earth and Space Science, Peking University, Beijing 100871 (China); Li, Gang [Department of Physics and CSPAR, University of Alabama in Huntsville, Alabama 35899 (United States); Salem, Chadi S.; Bale, Stuart D. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Wimmer-Schweingruber, Robert F. [Institute for Experimental and Applied Physics, University of Kiel (Germany)

2016-03-25

We present a statistical survey of the energy spectrum of solar wind suprathermal (∼0.1-1.5 keV) electrons measured by the WIND 3-D Plasma & Energetic Particle (3DP) instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. Firstly, we separate strahl (beaming) electrons and halo (isotropic) electrons based on their features in pitch angle distributions. Secondly, we fit the observed energy spectrum of both the strahl and halo electrons at ∼0.1-1.5 keV to a Kappa distribution function with an index κ, effective temperature T{sub eff} and density n{sub 0}. We also integrate the the measurements over ∼0.1-1.5 keV to obtain the average electron energy E{sub avg} of the strahl and halo. We find a strong positive correlation between κ and T{sub eff} for both the strahl and halo, possibly reflecting the nature of the generation of these suprathermal electrons. Among the 245 selected samples, ∼68% have the halo κ smaller than the strahl κ, while ∼50% have the halo E{sub h} larger than the strahl E{sub s}.

Total electron scattering cross sections of molecules containing H, C, N, O and F in the energy range 0.2–6.0 keV

Energy Technology Data Exchange (ETDEWEB)

Gurung, Meera Devi; Ariyasinghe, W.M., E-mail: wickram_ariyasinghe@baylor.edu

2017-03-15

Based on the effective atomic total electron scattering cross sections (EATCS) of atoms in a molecular environment, a simple model is proposed to predict the total electron scattering cross sections (TCS) of H, C, N, O, and F containing molecules. The EATCS for these five atoms are reported for 0.2–6.0 keV energies. The predicted TCS by this model are compared with experimental TCS in the literature. The experimental TCS of CHF{sub 3}, C{sub 2}F{sub 4}, C{sub 2}F{sub 2}H{sub 2}, C{sub 4}F{sub 6}, and c-C{sub 4}F{sub 8} have been obtained for 0.2–4.5 keV electrons by measuring the attenuation of the electron beam through a gas cell.

Optimization of energy and fluence of N{sub 2}{sup +} ions in the conversion of Al{sub 2}O{sub 3} surface into AlN at room temperature

Energy Technology Data Exchange (ETDEWEB)

Kumar, Praveen, E-mail: praiitr@gmail.com [Center for Nanoscience and Nanotechnology, Panjab University, Chandigarh 160014 (India); Devi, Pooja [Central Scientific Instruments Organization, Sector-30 C, Chandigarh 160030 (India); Kumar, Mahesh [Physics of Energy and Harvesting group, National Physical Laboratory, New Delhi 110012 (India); Shivaprasad, S.M. [Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India)

2016-01-15

Graphical abstract: We present a systematic study of energetic N{sub 2}{sup +} ions (0.1–5 keV) interaction with clean c-plane Al{sub 2}O{sub 3} surface in situ in a UHV system equipped with X-ray Photoelectron Spectroscopy at room temperature. Results show that maximum thickness of surface is nitride by 5 keV N{sub 2}{sup +} ion with an optimal fluence of 1.5 × 10{sup 15} ions/cm{sup 2}. This modified surface can be used as a template for low defect III-nitrides growth, with enhanced lattice matching than on bare c-Al{sub 2}O{sub 3}. - Highlights: • A mechanism for the formation of AlN on Al{sub 2}O{sub 3}. • Investigation of optimal energy and fluence for energetic N{sub 2}{sup +} ions. • AlN formation at room temperature on Al{sub 2}O{sub 3}. - Abstract: The work presents a systematic study of energetic N{sub 2}{sup +} ion interaction with the clean Al{sub 2}O{sub 3} surface at room temperature. Energetic N{sub 2}{sup +} ions with energies ranging from 0.1 to 5 keV were bombarded onto the c-plane Al{sub 2}O{sub 3} surface in situ in a UHV system equipped with X-ray Photoelectron Spectroscopy. Survey scans and core level spectra of Al(2p), O(1s), N(1s) were recorded as a function of ion fluence. Survey scans of XPS are used for the compositional analysis, while deconvoluted core level spectra are used to identify the evolution of the chemical bonding. Energetic dependence of N{sub 2}{sup +} ions occupying interstitial and substitutional sites in Al{sub 2}O{sub 3} lattice are probed to follow the surface evolution. Results show that maximum thickness of surface is nitride by 5 keV N{sub 2}{sup +} ion with an optimal fluence of 1.5 × 10{sup 15} ions/cm{sup 2}. This modified surface can be used as a template for low defect III-nitrides growth, with enhanced lattice matching than on bare c-Al{sub 2}O{sub 3}.

New determinations of gamma-ray line intensities of the E{sub p}=550 and 1747 keV resonances of the {sup 13}C(p,{gamma}){sup 14}N reaction

Energy Technology Data Exchange (ETDEWEB)

Kiener, J. E-mail: kiener@csnsm.in2p3.fr; Gros, M.; Tatischeff, V.; Attie, D.; Bailly, I.; Bauchet, A.; Chapuis, C.; Cordier, B.; Deloncle, I.; Porquet, M.G.; Schanne, S.; Sereville, N. de; Tauzin, G

2004-03-01

Gamma-ray angular distributions for the resonances at E{sub p}=550 and 1747 keV of the radiative capture reaction {sup 13}C(p,{gamma}){sup 14}N have been measured, using intense proton beams on isotopically pure {sup 13}C targets. Experimental gamma-ray spectra were obtained with three HP-Germanium detectors at four angles for E{sub p}=550 keV and six angles for E{sub p}=1747 keV in the range of 0-90 deg. with respect to the proton beam. From the data, relative intensities for the strongest transitions were extracted with an accuracy of typically 5%, making these resonances new useful gamma-ray standards for efficiency calibration in the energy range from E{sub {gamma}}=1.6-9 MeV. Gamma-ray branching ratios were obtained for several levels of {sup 14}N and are compared with literature values.

The Galactic 511 keV line: analysis and interpretation of Integral observations

International Nuclear Information System (INIS)

Lonjou, V.

2005-09-01

Ever since the discovery of the 511 keV annihilation line emission from the galactic center region in the late seventies, the origin of galactic positrons has been the topic of a vivid scientific debate. It is also one of the prime scientific objectives of the imaging spectrometer SPI on board ESA's INTEGRAL observatory. In this thesis first a description of the most important SPI sub-system is given - the detector plane. Procedures for detector energy calibration and detector degradation analysis are developed. The determination of instrumental background models, a crucial aspect of data analysis, is elaborated. These background models are then applied to deriving sky maps and spectra of unprecedented quality of the Galactic positron annihilation radiation. The emission is centered on the galactic center with a spatial resolution of 8 degrees (FWHM), a second spatial component appears clearly: the galactic disc. The ray energy has been measured with unprecedented accuracy: 511.0 ± 0.03 keV for a full width at half maximum (FWHM) of 2.07 ± 0.1 keV. The total galactic flux ranges from 1.09 to 2.43 10 -3 ph.cm -2 .s -1 including uncertainties on spatial distribution. Finally, the implications of these observations for the production of positrons by various Galactic populations are discussed

Radiation blistering of Nb implanted sequentially with helium ions of different energies (3-500 keV)

International Nuclear Information System (INIS)

Guseva, M.I.; Gusev, V.; Krasulin, U.L.; Martinenko, U.V.; Das, S.K.; Kaminsky, M.S.

1976-01-01

Cold rolled, polycrystalline niobium samples were irradiated at room temperature with 4 He + ions sequentially at 14 different energies over an energy range from 3 keV--500 keV in steps of 50 keV. The dose for each energy was chosen to give an approximately uniform concentration of helium between the implant depths corresponding to 3 keV and 500 keV. In one set of experiments the irradiations were started at the Kurchatov Institute with 3 keV 4 He + ions and extended up to 80 keV in several steps. Subsequently, the same target area was irradiated with 4 He + ions at Argonne National Laboratory (ANL) starting at 100 keV and increased to 500 keV in steps of 50 keV. Another set of irradiations were started at ANL with 500 keV 4 He + ions and continued with decreasing ion energies to 100 keV. Subsequently, the same area was irradiated at the Kurchatov Institute starting at 80 keV and continued with decreasing ion energies to 3 keV. Both sets of irradiations were completed for two different total doses, 0.5 C cm -2 and 1.0 C cm -2

Effects of packaging SrI{sub 2}(Eu) scintillator crystals

Energy Technology Data Exchange (ETDEWEB)

Sturm, Benjamin W., E-mail: sturm1@llnl.gov [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Cherepy, Nerine J.; Drury, Owen B.; Thelin, Peter A.; Fisher, Scott E.; Payne, Stephen A. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Burger, Arnold [Fisk University, Nashville, TN 37201 (United States); Boatner, Lynn A.; Ramey, Joanne O. [Oak Ridge National Laboratory, Oak Ridge, TN 37830 (United States); Shah, Kanai S.; Hawrami, Rastgo [Radiation Monitoring Devices, Watertown, MA 02472 (United States)

2011-10-01

Recent renewed emphasis placed on gamma-ray detectors for national security purposes has motivated researchers to identify and develop new scintillator materials capable of high energy resolution and growable to large sizes. We have discovered that SrI{sub 2}(Eu) has many desirable properties for gamma-ray detection and spectroscopy, including high light yield of {approx}90,000 photons/MeV and excellent light yield proportionality. We have measured <2.7% FWHM at 662 keV with small detectors (<1 cm{sup 3}) in direct contact with a photomultiplier tube, and {approx}3% resolution at 662 keV is obtained for 1 in.{sup 3} crystals. Due to the hygroscopic nature of SrI{sub 2}(Eu), similar to NaI(Tl), proper packaging is required for field use. This work describes a systematic study performed to determine the key factors in the packaging process to optimize performance. These factors include proper polishing of the surface, the geometry of the crystal, reflector materials and windows. A technique based on use of a collimated {sup 137}Cs source was developed to examine light collection uniformity. Employing this technique, we found that when the crystal is packaged properly, the variation in the pulse height at 662 keV from events near the bottom of the crystal compared to those near the top of the crystal could be reduced to <1%. This paper describes the design and engineering of our detector package in order to improve energy resolution of 1 in.{sup 3}-scale SrI{sub 2}(Eu) crystals.

Neutron resonance transmission spectroscopy with high spatial and energy resolution at the J-PARC pulsed neutron source

Energy Technology Data Exchange (ETDEWEB)

Tremsin, A.S., E-mail: ast@ssl.berkeley.edu [University of California at Berkeley, 7 Gauss Way, Berkeley, CA 94720 (United States); Shinohara, T.; Kai, T.; Ooi, M. [Japan Atomic Energy Agency, 2–4 Shirakata-shirane, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Kamiyama, T.; Kiyanagi, Y.; Shiota, Y. [Hokkaido University, Kita 13 Nishi 8 Kita-ku, Sapporo-shi, Hokkaido 060-8628 (Japan); McPhate, J.B.; Vallerga, J.V.; Siegmund, O.H.W. [University of California at Berkeley, 7 Gauss Way, Berkeley, CA 94720 (United States); Feller, W.B. [NOVA Scientific, Inc., 10 Picker Rd., Sturbridge, MA 01566 (United States)

2014-05-11

The sharp variation of neutron attenuation at certain energies specific to particular nuclides (the lower range being from ∼1 eV up to ∼1 keV), can be exploited for the remote mapping of element and/or isotope distributions, as well as temperature probing, within relatively thick samples. Intense pulsed neutron beam-lines at spallation sources combined with a high spatial, high-timing resolution neutron counting detector, provide a unique opportunity to measure neutron transmission spectra through the time-of-flight technique. We present the results of experiments where spatially resolved neutron resonances were measured, at energies up to 50 keV. These experiments were performed with the intense flux low background NOBORU neutron beamline at the J-PARC neutron source and the high timing resolution (∼20 ns at epithermal neutron energies) and spatial resolution (∼55 µm) neutron counting detector using microchannel plates coupled to a Timepix electronic readout. Simultaneous element-specific imaging was carried out for several materials, at a spatial resolution of ∼150 µm. The high timing resolution of our detector combined with the low background beamline, also enabled characterization of the neutron pulse itself – specifically its pulse width, which varies with neutron energy. The results of our measurements are in good agreement with the predicted results for the double pulse structure of the J-PARC facility, which provides two 100 ns-wide proton pulses separated by 600 ns, broadened by the neutron energy moderation process. Thermal neutron radiography can be conducted simultaneously with resonance transmission spectroscopy, and can reveal the internal structure of the samples. The transmission spectra measured in our experiments demonstrate the feasibility of mapping elemental distributions using this non-destructive technique, for those elements (and in certain cases, specific isotopes), which have resonance energies below a few keV, and with lower

The 65 keV resonance in the {sup 17}O(p,alpha){sup 14}N thermonuclear reaction

Energy Technology Data Exchange (ETDEWEB)

Sergi, M.L. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia, Catania (Italy); Spitaleri, C. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Coc, A. [CSNSM, UMR 8609, CNRS/IN2P3and Universite Paris Sud 11, Batiment 104, 91405 Orsay Campus (France); Mukhamedzhanov, A. [Cyclotron Institute, Texas A and M University, College Station, TX 77843 (United States); Burjan, S.V. [Nuclear Physics Institute of ASCR Rez near Prague (Czech Republic); Gulino, M. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Hammache, F. [IPN, IN2P3-CNRS et Universite de Paris-Sud 11, 91406 Orsay Cedex (France); Hons, Z. [Nuclear Physics Institute of ASCR Rez near Prague (Czech Republic); Irgaziev, B. [GIK Institute of Engineering Sciences and Technology Topi District Swabi NWFP (Pakistan); Kiss, G.G. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Kroha, V. [Nuclear Physics Institute of ASCR Rez near Prague (Czech Republic); La Cognata, M. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia, Catania (Italy); Lamia, L.; Pizzone, R.G. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Sereville, N. de [IPN, IN2P3-CNRS et Universite de Paris-Sud 11, 91406 Orsay Cedex (France); Somorjai, E. [ATOMKI, Debrecen (Hungary)

2010-03-01

The indirect measurement of {sup 17}O(p,alpha){sup 14}N cross section was performed by means of the Trojan Horse Method. This approach allowed to investigate the ultra-low energy range (E{sub c.m.}=0-300 keV) relevant for several astrophysics environments, where two resonant levels of {sup 18}F at E{sub c.m.}{sup R}=65 keV and E{sub c.m.}{sup R}=183 keV play a significant role in the reaction rate determination.

Simbol-X: a formation flight mission with an unprecedented imaging capability in the 0.5-80 keV energy band

Science.gov (United States)

Tagliaferri, Gianpiero; Ferrando, Philippe; Le Duigou, Jean-Michel; Pareschi, Giovanni; Laurent, Philippe; Malaguti, Giuseppe; Clédassou, Rodolphe; Piermaria, Mauro; La Marle, Olivier; Fiore, Fabrizio; Giommi, Paolo

2017-11-01

The discovery of X-ray emission from cosmic sources in the 1960s has opened a new powerful observing window on the Universe. In fact, the exploration of the X-ray sky during the 70s-90s has established X-ray astronomy as a fundamental field of astrophysics. Today, the emission from astrophysical sources is by large best known at energies below 10 keV. The main reason for this situation is purely technical since grazing incidence reflection has so far been limited to the soft X-ray band. Above 10 keV all the observations have been obtained with collimated detectors or coded mask instruments. To make a leap step forward in Xray astronomy above 10 keV it is necessary to extend the principle of focusing X ray optics to higher energies, up to 80 keV and beyond. To this end, ASI and CNES are presently studying the implementation of a X-ray mission called Simbol-X. Taking advantage of emerging technology in mirror manufacturing and spacecraft formation flying, Simbol-X will push grazing incidence imaging up to 80 keV and beyond, providing a strong improvement both in sensitivity and angular resolution compared to all instruments that have operated so far above 10 keV. This technological breakthrough will open a new highenergy window in astrophysics and cosmology. Here we will address the problematic of the development for such a distributed and deformable instrument. We will focus on the main performances of the telescope, like angular resolution, sensitivity and source localization. We will also describe the specificity of the calibration aspects of the payload distributed over two satellites and therefore in a not "frozen" configuration.

Sub-nanometre resolution imaging of polymer-fullerene photovoltaic blends using energy-filtered scanning electron microscopy.

Science.gov (United States)

Masters, Robert C; Pearson, Andrew J; Glen, Tom S; Sasam, Fabian-Cyril; Li, Letian; Dapor, Maurizio; Donald, Athene M; Lidzey, David G; Rodenburg, Cornelia

2015-04-24

The resolution capability of the scanning electron microscope has increased immensely in recent years, and is now within the sub-nanometre range, at least for inorganic materials. An equivalent advance has not yet been achieved for imaging the morphologies of nanostructured organic materials, such as organic photovoltaic blends. Here we show that energy-selective secondary electron detection can be used to obtain high-contrast, material-specific images of an organic photovoltaic blend. We also find that we can differentiate mixed phases from pure material phases in our data. The lateral resolution demonstrated is twice that previously reported from secondary electron imaging. Our results suggest that our energy-filtered scanning electron microscopy approach will be able to make major inroads into the understanding of complex, nano-structured organic materials.

Sub-nanometre resolution imaging of polymer–fullerene photovoltaic blends using energy-filtered scanning electron microscopy

Science.gov (United States)

Masters, Robert C.; Pearson, Andrew J.; Glen, Tom S.; Sasam, Fabian-Cyril; Li, Letian; Dapor, Maurizio; Donald, Athene M.; Lidzey, David G.; Rodenburg, Cornelia

2015-01-01

The resolution capability of the scanning electron microscope has increased immensely in recent years, and is now within the sub-nanometre range, at least for inorganic materials. An equivalent advance has not yet been achieved for imaging the morphologies of nanostructured organic materials, such as organic photovoltaic blends. Here we show that energy-selective secondary electron detection can be used to obtain high-contrast, material-specific images of an organic photovoltaic blend. We also find that we can differentiate mixed phases from pure material phases in our data. The lateral resolution demonstrated is twice that previously reported from secondary electron imaging. Our results suggest that our energy-filtered scanning electron microscopy approach will be able to make major inroads into the understanding of complex, nano-structured organic materials. PMID:25906738

Development of ultrahigh energy resolution gamma spectrometers for nuclear safeguards

International Nuclear Information System (INIS)

Drury, O.B.; Velazquez, M.; Dreyer, J.G.; Friedrich, S.

2009-01-01

We are developing superconducting ultrahigh resolution gamma-detectors for non-destructive analysis (NDA) of nuclear materials, and specifically for spent fuel characterization in nuclear safeguards. The detectors offer an energy resolution below 100 eV FWHM at 100 keV, and can therefore significantly increase the precision of NDA at low energies where line overlap affects the errors of the measurement when using germanium detectors. They also increase the peak-to-background ratio and thus improve the detection limits for weak gamma emissions from the fissile Pu and U isotopes at low energy in the presence of an intense Compton background from the fission products in spent fuel. Here we demonstrate high energy resolution and high peak-to-background ratio of our superconducting Gamma detectors, and discuss their relevance for measuring actinides in spent nuclear fuel. (author)

Measurements of the charge exchange and dissociation cross-sections of the H{sub 2}+ ion in a wide energy range; Mesures des sections efficaces d'echange de charge et de dissociation des ions H{sub 2}{sup +} dans une large gamme d'energie (25 - 250 keV)

Energy Technology Data Exchange (ETDEWEB)

Guidini, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1962-07-01

The dissociation, ionisation, and charge exchange cross-sections of molecular hydrogen ions H{sub 2}{sup +} passing through various gases, have been measured as a function of the energy of the ions. The energy range studied was from 25 to 250 keV. The reaction products, analysed by a magnetic field according to their e/m ratio, are collected on scintillation detectors. Two methods have made it possible to separate the various reactions leading to the formation of particles having the same e/m ratio. The first separates the particles according to their energy, the other selects those arriving simultaneously on two different detectors. The results show a large variation in the charge exchange cross-section with the energy of the H{sub 2}{sup +} ions. The variations in the dissociation and ionisation cross-sections are less pronounced. For a given energy, the values of the cross-sections increase with the atomic weight of the target particles. These measurements have been extended to the case of H{sub 2}{sup +} ions passing through a target of charged particles. Preliminary results show an increase in the cross-sections as compared to the preceding case. Finally the scattering of the reaction products has been studied; this scattering is due to the fact that the molecules formed during a reaction are in an unstable state and the nuclei or atoms diverge from each other. (author) [French] Les sections efficaces de dissociation, d'ionisation et d'echange de charge d'ions hydrogene moleculaires H{sub 2}{sup +} traversant differents gaz, ont ete mesurees en fonction de l'energie des ions. La gamme d'energie exploree est comprise entre 25 et 250 keV. Les produits de reactions, analyses suivant leur rapport e/m par un champ magnetique, sont recus sur des detecteurs a scintillations. Deux methodes ont permis de separer les diverses reactions conduisant a la formation de particules ayant meme rapport e/m. L'une classe les particules secondaires en energie, l'autre selectionne

Hard x-ray monochromator with milli-electron volt bandwidth for high-resolution diffraction studies of diamond crystals

Energy Technology Data Exchange (ETDEWEB)

Stoupin, Stanislav; Shvyd' ko, Yuri; Shu Deming; Khachatryan, Ruben; Xiao, Xianghui; DeCarlo, Francesco; Goetze, Kurt; Roberts, Timothy; Roehrig, Christian; Deriy, Alexey [Advanced Photon Source, Argonne National Laboratory, Illinois 60439 (United States)

2012-02-15

We report on design and performance of a high-resolution x-ray monochromator with a spectral bandwidth of {Delta}E{sub X}{approx_equal} 1.5 meV, which operates at x-ray energies in the vicinity of the backscattering (Bragg) energy E{sub H} = 13.903 keV of the (008) reflection in diamond. The monochromator is utilized for high-energy-resolution diffraction characterization of diamond crystals as elements of advanced x-ray crystal optics for synchrotrons and x-ray free-electron lasers. The monochromator and the related controls are made portable such that they can be installed and operated at any appropriate synchrotron beamline equipped with a pre-monochromator.

Studies of internal bremsstrahlung spectrum of 35S beta emitter in the photon energy region of 1–100 keV

International Nuclear Information System (INIS)

Singh, Amrit; Dhaliwal, A.S.

2014-01-01

The internal bremsstrahlung (IB) spectral photon distribution, produced by soft beta particles of 35 S (W max =164 keV), in the photon energy region of 1–100 keV, is measured by using a Si(Li) detector, having high energy resolution and efficiency at low energy region. The measured spectral IB photon distribution is compared with KUB theory and Coulomb corrected IB theories given by Nilsson, and Lewis and Ford. After applying the necessary corrections, the experimental and theoretical IB spectral photon distributions are compared in terms of the number of IB photon of energy k per m o c 2 per unit photon yield. In the low energy region (below 10 keV), the experimental results are in agreement with all the theories. However, in photon energy region of 10–50 keV, experimental results are in agreement with Coulomb corrected Nilsson theory only, within the experimental errors. Further, beyond 50 keV, the Nilsson theory is more close to the experimental results than the KUB, and the Lewis and Ford theories. Hence, the Nilsson theory is more accurate than the other theories given by KUB and Lewis and Ford, particularly at a high energy end. The experimental results reported here with Si(Li) detector are free from number of ambiguities in earlier measurements reported with NaI(Tl) and HPGe detectors. The present results are indicating a relook into the theoretical considerations, given by different theories, while taking into account the Coulomb corrections for predicting the IB spectrum, particularly at high photon energy region. - Highlights: • The internal bremsstrahlung spectrum of 35 S beta emitter, in the photon energy region of 1–100 keV. • These measurement are taken by using a Si(Li) detector. • Theoretical and experimental results are reported in terms of number of photons of energy k per m 0 c 2 per unit photon yield. • The Nilsson theory for IB is more accurate than KUB and Lewis and Ford, particularly at high photon energy region

Neutron transmission and capture measurements and analysis of 60Ni from 1 to 450 keV

International Nuclear Information System (INIS)

Perey, C.M.; Harvey, J.A.; Macklin, R.L.; Winters, R.R.; Perey, F.G.

1982-11-01

High-resolution transmission and capture measurements of 60 Ni-enriched targets have been made at the Oak Ridge Electron Linear Accelerator (ORELA) from a few eV to 1800 keV in transmission and from 2.5 keV to 5 MeV in capture . The transmission data from 1 to 450 keV were analyzed with a multi-level R-matrix code which uses the Bayes' theorem for the fitting process. This code provides the energies and neutron widths of the resonances inside the 1- to 450-keV region as well as a possible parameterization for outside resonances to describe the smooth cross section in this region. The capture data were analyzed with a least-squares fitting code using the Breit-Wigner formula. From 2.5 to 450 keV, 166 resonances were seen in both sets of data. Correspondence between the energy scales shows a discontinuity around 300 keV which makes the matching of resonances at higher energies difficult. Eighty-nine resonances were seen in the capture data only. Average parameters for the 30 observed s-wave resonances were deduced. The average level spacing D 0 was found to be equal to 15.2 +- 1.5 keV, the strength function, S 0 , equal to (2.2 +- 0.6) x 10 -4 and the average radiation width, GAMMA/sub γ/, equal to 1.30 +- 0.07 eV. The staircase plot of the reduced level widths and the plot of the Lorentz-weighted strength function averaged over various energy intervals show possible evidence for doorway states. The level densities calculated with the Fermi-gas model for l = 0 and for l > 0 resonances were compared with the cumulative number of observed resonances, but the analysis is not conclusive. The average capture cross section as a function of the neutron incident energy is compared to the tail of the giant electric dipole resonance prediction

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.)

Iodine-131 imaging using 284 keV photons with a small animal CZT-SPECT system dedicated to low-medium-energy photon detection.

Science.gov (United States)

Kojima, Akihiro; Gotoh, Kumiko; Shimamoto, Masako; Hasegawa, Koki; Okada, Seiji

2016-02-01

Iodine-131 is widely used for radionuclide therapy because of its β-particle and for diagnostic imaging employing its principal gamma ray. Since that principal gamma ray has the relatively high energy of 364 keV, small animal single-photon emission computed tomography (SPECT) imaging systems may be required to possess the ability to image such higher energy photons. The aim of this study was to investigate the possibility of imaging I-131 using its 284 keV photons instead of its 364 keV photons in a small animal SPECT imaging system dedicated to the detection of low-medium-energy photons (below 300 keV). The imaging system used was a commercially available preclinical SPECT instrument with CZT detectors that was equipped with multi-pinhole collimators and was accompanied by a CT imager. An energy window for I-131 imaging was set to a photopeak of 284 keV with a low abundance compared with 364 keV photons. Small line sources and two mice, one of each of two types, that were injected with NaI-131 were scanned. Although higher counts occurred at the peripheral region of the reconstructed images due to the collimator penetration by the 364 keV photons, the shape of the small line sources could be well visualized. The measured spatial resolution was relatively poor (~1.9 mm for full width at half maximum and ~3.9 mm for full width at tenth maximum). However, a good linear correlation between SPECT values and the level of I-131 radioactivity was observed. Furthermore, the uptake of NaI-131 to the thyroid gland for the two mice was clearly identified in the 3D-SPECT image fused with the X-ray CT image. We conclude that the use of an energy window set on the photopeak of 284 keV and the multi-pinhole collimator may permit I-131 imaging for a preclinical CZT-SPECT system that does not have the ability to acquire images using the 364 keV photons.

Study on energy and position resolution of MWPC for the Beijing e/π test beam

International Nuclear Information System (INIS)

Shen Ji; Chen Ziyu; Ye Yunxiu; Cui Xiangzong; Li Jiacai

2006-01-01

This paper describes the research on the energy and position resolution of the MWPC used in the e/π Test Beam on BEPC (Beijing Electron Positron Collider), which localizes the particles of e/π by the readout method of gravity center of the induced charges on the cathode strips. The spatial resolution of about 0.24 mm and energy resolution of 17% for 5.9 keV γ photons are attained at the 3700 V anode voltage. For the 1.1 GeV electrons, the spatial resolution of 0.3 mm is obtained. The contributions of various factors to energy resolution are analysed. It is found that energy resolution is changed with the anode voltage and there exists a least energy resolution. The reasons for these are discussed. (authors)

Optimized high energy resolution in γ-ray spectroscopy with AGATA triple cluster detectors

Energy Technology Data Exchange (ETDEWEB)

Wiens, Andreas

2011-06-20

The AGATA demonstrator consists of five AGATA Triple Cluster (ATC) detectors. Each triple cluster detector contains three asymmetric, 36-fold segmented, encapsulated high purity germanium detectors. The purpose of the demonstrator is to show the feasibility of position-dependent γ-ray detection by means of γ-ray tracking, which is based on pulse shape analysis. The thesis describes the first optimization procedure of the first triple cluster detectors. Here, a high signal quality is mandatory for the energy resolution and the pulse shape analysis. The signal quality was optimized and the energy resolution was improved through the modification of the electronic properties, of the grounding scheme of the detector in particular. The first part of the work was the successful installation of the first four triple cluster detectors at INFN (National Institute of Nuclear Physics) in Legnaro, Italy, in the demonstrator frame prior to the AGATA commissioning experiments and the first physics campaign. The four ATC detectors combine 444 high resolution spectroscopy channels. This number combined with a high density were achieved for the first time for in-beam γ-ray spectroscopy experiments. The high quality of the ATC detectors is characterized by the average energy resolutions achieved for the segments of each crystal in the range of 1.943 and 2.131 keV at a γ-ray energy of 1.33 MeV for the first 12 crystals. The crosstalk level between individual detectors in the ATC is negligible. The crosstalk within one crystal is at a level of 10{sup -3}. In the second part of the work new methods for enhanced energy resolution in highly segmented and position sensitive detectors were developed. The signal-to-noise ratio was improved through averaging of the core and the segment signals, which led to an improvement of the energy resolution of 21% for γ-energies of 60 keV to a FWHM of 870 eV. In combination with crosstalk correction, a clearly improved energy resolution was

Front-illuminated versus back-illuminated photon-counting CCD-based gamma camera: important consequences for spatial resolution and energy resolution

International Nuclear Information System (INIS)

Heemskerk, Jan W T; Westra, Albert H; Linotte, Peter M; Ligtvoet, Kees M; Zbijewski, Wojciech; Beekman, Freek J

2007-01-01

Charge-coupled devices (CCDs) coupled to scintillation crystals can be used for high-resolution imaging with x-rays and gamma rays. When the CCD images can be read out fast enough, the energy and interaction position of individual gamma quanta can be estimated by a real-time image analysis of the scintillation light flashes ('photon-counting mode'). The electron-multiplying CCD (EMCCD) is well suited for fast read out, since even at high frame rates it has extremely low read-out noise. Back-illuminated (BI) EMCCDs have much higher quantum efficiency than front-illuminated (FI) EMCCDs. Here we compare the spatial and energy resolution of gamma cameras based on FI and BI EMCCDs. The CCDs are coupled to a 1000 μm thick columnar CsI(Tl) crystal for the purpose of Tc-99m and I-125 imaging. Intrinsic spatial resolutions of 44 μm for I-125 and 49 μm for Tc-99m were obtained when using a BI EMCCD, which is an improvement by a factor of about 1.2-2 over the FI EMCCD. Furthermore, in the energy spectrum of the BI EMCCD, the I-125 signal could be clearly separated from the background noise, which was not the case for the FI EMCCD. The energy resolution of a BI EMCCD for Tc-99m was estimated to be approximately 36 keV, full width at half maximum, at 141 keV. The excellent results for the BI EMCCD encouraged us to investigate the cooling requirements for our setup. We have found that for the BI EMCCD, the spatial and energy resolution, as well as image noise, remained stable over a range of temperatures from -50 deg. C to -15 deg. C. This is a significant advantage over the FI EMCCD, which suffered from loss of spatial and especially energy resolution at temperatures as low as -40 deg. C. We conclude that the use of BI EMCCDs may significantly improve the imaging capabilities and the cost efficiency of CCD-based high-resolution gamma cameras. (note)

A proton polarimeter for beam energies below 300 keV

International Nuclear Information System (INIS)

Buchmann, L.

1990-10-01

A nuclear polarimeter based on the low energy analyzing power of the 6 Li(p, 3 He)α reaction has been developed and tested for proton energies below E p =300 keV. The polarimeter uses a 6 LiF target evaporated on a water cooled tantalum backing. The target is observed at backwards angles by four silicon surface barrier detectors. The energy dependence of the analyzing power under 130 o for the 6 Li(p, 3 He)α reaction has been determined down to 200 keV. Spin rotation has been observed via a magnetic field incorporated in a Wien filter demonstrating that the polarimeter is operational. (Author) (7 refs., 7 figs.)

Calculated and measured W values in N2, Ar, CH4 and CO2 gases for ions H+, He+, C+, N+, O+ and Ar+ in the energy range 25 KeV to 375 KeV

International Nuclear Information System (INIS)

Nguyen Van Dat; Chemtob, Maurice.

1979-01-01

The present paper describes the experimental method used for measurement of W values in argon gas and in the three components of T.E. gas: nitrogen, methane and carbon dioxide, for ions with masses in the range 1 to 40 a.m.u. and with energies in the range 25 KeV to 375 KeV. For these ions, the incident velocities are comparable to the electron orbital velocities. At these velocities energy losses due to elastic scattering and electron capture processes are expected to become significant as compared to ionization and excitation which predominate at higher velocities. These measured W values are then compared to calculated values. These calculations are obtained by introducing the inelastic and elastic stopping power cross sections in a transport equation, the resolution of which gives ionization range and the amount of energy released to produce ionization

X-ray optics for 50-100 keV undulator radiation using crystals and refractive lenses

International Nuclear Information System (INIS)

Shastri, S. D.; Mashayekhi, A.; Cremer, J. T.; Piestrup, M. A.

2003-01-01

Compound refractive lenses (CRLs) are effective for collimating or focusing high-energy x-ray beams (50 - 100 keV) and can be used in conjunction with crystal optics in a variety of configurations, as demonstrated at the 1-ID undulator beamline of the Advanced Photon Source. As a primary example, this article describes the quadrupling of the output flux when a collimating CRL, composed of cylindrical holes in aluminum, is inserted in between two successive monochromators -- a modest energy resolution premonochromator followed by a high-resolution monochromator. The premonochromator is a cryogenically cooled, divergence-preserving, bent double-Laue Si(111) crystal device delivering an energy width ΔE/E ∼ 10 -3 , sufficient for most experiments. The high-resolution monochromator is a four-reflection, flat Si(111) crystal system resembling two channel-cuts in a dispersive arrangement, reducing the bandwidth to ΔE/E -4 , as required for some applications. Tests with 67 keV and 81 keV photon energies show that the high-resolution monochromator, having a narrow angular acceptance of a few erad, exhibits, a four-fold throughput enhancement due to the insertion of a CRL which reduces the premonochromatized beam's vertical divergence from 29 erad to a few erad. The ability to focus high-energy x-rays with CRLs having long focal lengths (tens of meters) is also shown by creating a line focus of 70 - 90 μ m beam height in the beamline end-station with both the modest-energy-resolution and high-energy- resolution monochromatic x-rays

A massive cryogenic particle detector with good energy resolution

International Nuclear Information System (INIS)

Ferger, P.; Colling, P.; Cooper, S.; Dummer, D.; Frank, M.; Nagel, U.; Nucciotti, A.; Proebst, F.; Seidel, W.

1993-12-01

Massive cryogenic particle detectors are being developed for use in a search for dark matter particles. Results with a 31 g sapphire crystal and a superconducting phase transition thermometer operated at 44 mK are presented. The observed signal includes a fast component which is significantly larger than the expected thermal pulse. The energy resolution is 210 eV (FWHM) for 6 keV X-rays. (orig.)

Ion temperature measurement by neutral energy analyzer in high-field tokamak TRIAM-1

Energy Technology Data Exchange (ETDEWEB)

Nakamura, K; Hiraki, N; Toi, K; Itoh, S [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics

1980-02-01

The measurement of the ion temperature of the TRIAM-1 tokamak plasma is carried out by using a seven-channel neutral energy analyzer. The temporal and spatial variations of the ion temperature have been obtained with the spatial resolution of +-4.3 mm and the temporal resolution of 100 ..mu..sec. The energy range of the analyzed neutral particles is from 0.2 to 8 keV. The energy spectrum in the TRIAM-1 plasma without the strong gas puffing usually consists of two-component Maxwellian; the one represents the thermal part which is a superposition of the contribution from a hot region (T sub(i) = 100 - 300 eV) and that from an edge region (T sub(i) asymptotically equals 50 eV), and the other represents the superthermal part (T sub(i) asymptotically equals 1 keV). The neutral particle energy spectra at several vertical positions are obtained by scanning the analyzer in the vertical direction. From those spectra, the radial profile of the ion temperature is derived by means of the nonlinear optimization method.

SU-C-206-01: Impact of Charge Sharing Effect On Sub-Pitch Resolution for CZT-Based Photon Counting CT Systems

Energy Technology Data Exchange (ETDEWEB)

Zheng, X; Cheng, Z; Deen, J; Peng, H [McMaster University, Hamilton, Ontario (Canada); Xing, L [Stanford University School of Medicine, Stanford, CA (United States)

2016-06-15

Purposes: Photon counting CT is a new imaging technology that can provide tissue composition information such as calcium/iodine content quantification. Cadmium zinc telluride CZT is considered a good candidate the photon counting CT due to its relatively high atomic number and band gap. One potential challenge is the degradation of both spatial and energy resolution as the fine electrode pitch is deployed (<50 µm). We investigated the extent of charge sharing effect as functions of gap width, bias voltage and depth-of-interaction (DOI). Methods: The initial electron cloud size and diffusion process were modeled analytically. The valid range of charge sharing effect refers to the range over which both signals of adjacent electrodes are above the triggering threshold (10% of the amplitude of 60keV X-ray photons). The intensity ratios of output in three regions (I1/I2/I3: left pixel, gap area and right pixel) were calculated. With Gaussian white noises modeled (a SNR of 5 based upon the preliminary experiments), the sub-pitch resolution as a function of the spatial position in-between two pixels was studied. Results: The valid range of charge sharing increases linearly with depth-of-interaction (DOI) but decreases with gap width and bias voltage. For a 1.5mm thickness CZT detector (pitch: 50µm, bias: 400 V), the range increase from ∼90µm up to ∼110µm. Such an increase can be attributed to a longer travel distance and the associated electron cloud broadening. The achievable sub-pitch resolution is in the range of ∼10–30µm. Conclusion: The preliminary results demonstrate that sub-pixel spatial resolution can be achieved using the ratio of amplitudes of two neighboring pixels. Such ratio may also be used to correct charge loss and help improve energy resolution of a CZT detector. The impact of characteristic X-rays hitting adjacent pixels (i.e., multiple interaction) on charge sharing is currently being investigated.

Energy reflection coefficient for H+ ions at energies between 10 and 80 keV

International Nuclear Information System (INIS)

Chen, C.K.; Bohdansky, J.; Eckstein, W.; Robinson, M.T.

1984-04-01

The energy reflection coefficient for H + ions at energies between 10 keV and 80 keV was determined by experiments and by computer calculations. Measurements were made with graphite, Al, Cu, Mo and W. targets. The angle of ion incidence was restricted to 85 0 , 78 0 and 70 0 measured from the surface normal. Calculated data were obtained by two different Monte Carlo computer programs (MARLOWE, TRIM). It was found that both the calculated and the measured data scale with the parameter epsilon cos 2 α, where epsilon is Lindhard's reduced energy and α the angle of incidence for the ions. The measured values are smaller than those calculated. This can be explained by surface roughness which developed during the ion irradiation

M sub shell X-ray emission cross section measurements for Pt, Au, Hg, Pb, Th and U at 8 and 10 keV synchrotron photons

International Nuclear Information System (INIS)

Kaur, Gurpreet; Gupta, Sheenu; Tiwari, M.K.; Mittal, Raj

2014-01-01

Highlights: • First time M sub shell fluorescence cross section measurements at 8 and 10 keV photons. • Comparison with theoretical evaluations from different model data for parameters. • Explained the large deviations from the trend of parameters with atomic number Z. • A specific pattern of cross sections with Z is predicted in the region, 78 ⩽ Z ⩽ 92. • Confirmation of prediction requires more experiment in these Z and energy region. -- Abstract: M sub shell X-ray emission cross sections of Pt, Au, Hg, Pb, Th and U at 8 and 10 keV photon energies have been determined with linearly polarized photon beam from Indus-2 synchrotron source. The measured cross sections have been reported for the first time and were used to check the available theoretical Dirac–Hartree–Slater (DHS) and Dirac–Fock (DF) values reported in literature and also the presently derived Non Relativistic Hartree–Slater (NRHS), DF and DHS values for M ξ , M δ , M α , M β , M γ , M m1 and M m2 group of X-rays

High-resolution tomography of positron emitters with clustered pinhole SPECT

Energy Technology Data Exchange (ETDEWEB)

Goorden, Marlies C; Beekman, Freek J [Section of Radiation Detection and Medical Imaging, Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands)], E-mail: m.c.goorden@tudelft.nl

2010-03-07

State-of-the-art small-animal single photon emission computed tomography (SPECT) enables sub-half-mm resolution imaging of radio-labelled molecules. Due to severe photon penetration through pinhole edges, current multi-pinhole SPECT is not suitable for high-resolution imaging of photons with high energies, such as the annihilation photons emitted by positron emitting tracers (511 keV). To deal with this edge penetration, we introduce here clustered multi-pinhole SPECT (CMP): each pinhole in a cluster has a narrow opening angle to reduce photon penetration. Using simulations, CMP is compared with (i) a collimator with traditional pinholes that is currently used for sub-half-mm imaging of SPECT isotopes (U-SPECT-II), and (ii), like (i) but with collimator thickness adapted to image high-energy photons (traditional multi-pinhole SPECT, TMP). At 511 keV, U-SPECT-II is able to resolve the 0.9 mm rods of an iteratively reconstructed Jaszczak-like capillary hot rod phantom, and while TMP only leads to small improvements, CMP can resolve rods as small as 0.7 mm. Using a digital tumour phantom, we show that CMP resolves many details not assessable with standard USPECT-II and TMP collimators. Furthermore, CMP makes it possible to visualize uptake of positron emitting tracers in sub-compartments of a digital mouse striatal brain phantom. This may open up unique possibilities for analysing processes such as those underlying the function of neurotransmitter systems. Additional potential of CMP may include (i) the imaging of other high-energy single-photon emitters (e.g. I-131) and (ii) localized imaging of positron emitting tracers simultaneously with single photon emitters, with an even better resolution than coincidence PET.

Formation of H{sub 2} from internally heated polycyclic aromatic hydrocarbons: Excitation energy dependence

Energy Technology Data Exchange (ETDEWEB)

Chen, T., E-mail: tao.chen@fysik.su.se, E-mail: henning@fysik.su.se; Gatchell, M.; Stockett, M. H.; Schmidt, H. T.; Cederquist, H.; Zettergren, H., E-mail: tao.chen@fysik.su.se, E-mail: henning@fysik.su.se [Department of Physics, Stockholm University, S-106 91 Stockholm (Sweden); Delaunay, R.; Rousseau, P.; Adoui, L. [CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen cedex 05 (France); Université de Caen Basse-Normandie, Esplanade de la Paix, F-14032 Caen (France); Domaracka, A.; Huber, B. A. [CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen cedex 05 (France); Micelotta, E. R. [Université Paris Sud, Institut d’Astrophysique Spatiale, UMR 8617, 91405 Orsay (France); Tielens, A. G. G. M. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)

2015-04-14

We have investigated the effectiveness of molecular hydrogen (H{sub 2}) formation from Polycyclic Aromatic Hydrocarbons (PAHs) which are internally heated by collisions with keV ions. The present and earlier experimental results are analyzed in view of molecular structure calculations and a simple collision model. We estimate that H{sub 2} formation becomes important for internal PAH temperatures exceeding about 2200 K, regardless of the PAH size and the excitation agent. This suggests that keV ions may effectively induce such reactions, while they are unlikely due to, e.g., absorption of single photons with energies below the Lyman limit. The present analysis also suggests that H{sub 2} emission is correlated with multi-fragmentation processes, which means that the [PAH-2H]{sup +} peak intensities in the mass spectra may not be used for estimating H{sub 2}-formation rates.

Energy and resolution calibration of detectors for noble gas β-γ coincidence system

International Nuclear Information System (INIS)

Jia Huaimao; Wang Shilian; Li Qi; Wang Jun; Zhao Yungang; Zhang Xinjun; Fan Yuanqing

2010-01-01

The β-γ coincidence technique is a kind of important method to detect radioactive xenon isotopes for the Comprehensive Nuclear-Test-Ban Treaty(CTBT). The energy and resolution calibration of detectors is the first key technique. This paper describes in detail the energy and resolution calibration methods of NaI (Tl) and plastic scintillator detectors for the noble gas β-γ coincidence system SAUNA II-Lab. NaI (Tl) detector's energy and resolution for γ-ray were calibrated with γ radioactive point sources. Plastic scintillator detector's energy and resolution for β-ray were calibrated by Compton scattering electrons of 137 Cs 661.66 keV γ-ray. And the results of β-ray energy resolution calibrated by Compton scattering electrons of 137 Cs were compared with the results of conversion electron of 131 Xe m . In conclusion,it is an easy and feasible method of calibrating plastic scintillator detector's energy by Compton scattering electrons of 137 Cs,but detector's resolution calibrated by Compton scattering electrons is higher than factual result. (authors)

A novel gamma-ray detector with submillimeter resolutions using a monolithic MPPC array with pixelized Ce:LYSO and Ce:GGAG crystals

Energy Technology Data Exchange (ETDEWEB)

Kato, T., E-mail: katou.frme.8180@asagi.waseda.jp [Research Institute for Science and Engineering, Waseda University, 3-4-1, Ohkubo, Shinjuku, Tokyo (Japan); Kataoka, J.; Nakamori, T.; Miura, T.; Matsuda, H.; Kishimoto, A. [Research Institute for Science and Engineering, Waseda University, 3-4-1, Ohkubo, Shinjuku, Tokyo (Japan); Sato, K.; Ishikawa, Y.; Yamamura, K.; Nakamura, S.; Kawabata, N. [Solid State Division, Hamamatsu Photonics K. K., 1126-1, Ichino-cho, Hamamatsu, Shizuoka (Japan); Ikeda, H. [ISAS/JAXA, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara-shi, Kanagawa (Japan); Yamamoto, S. [Kobe City College of Technology, 8-3, Gakuenhigashimati, Nishi-ku, Kobe-shi, Hyougo 651-2194 (Japan); Kamada, K. [Materials Research Laboratory, Furukawa Co., Ltd., 1-25-13, Kannondai, Tsukuba, Ibaraki 305-0856 (Japan)

2013-01-21

We have developed a large-area monolithic Multi-Pixel Photon Counter (MPPC) array consisting of 4×4 channels with a three-side buttable package. Each channel has a photosensitive area of 3×3 mm{sup 2} and 3600 Geiger mode avalanche photodiodes (APDs). For typical operational gain of 7.5×10{sup 5} at +20 °C, gain fluctuation over the entire MPPC device is only ±5.6%, and dark count rates (as measured at the 1 p.e. level) amount to ≤400kcps per channel. We first fabricated a gamma-ray camera consisting of the MPPC array with one-to-one coupling to a Ce-doped (Lu,Y){sub 2}(SiO{sub 4})O (Ce:LYSO) crystal array (4×4 array of 3×3×10 mm{sup 3} crystals). Energy and time resolutions of 11.5±0.5% (FWHM at 662 keV) and 493±22ps were obtained, respectively. When using the charge division resistor network, which compiles signals into four position-encoded analog outputs, the ultimate positional resolution is estimated as 0.19 mm in both X and Y directions, while energy resolution of 10.2±0.4% (FWHM) was obtained. Finally, we fabricated submillimeter Ce:LYSO and Ce-doped Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12} (Ce:GGAG) scintillator matrices each consisting of 1.0×1.0, 0.7×0.7 and 0.5×0.5 mm{sup 2} pixels, to further improve the spatial resolution. In all types of Ce:LYSO and Ce:GGAG matrices, each crystal was clearly resolved in the position histograms when irradiated by a {sup 137}Cs source. The energy resolutions for 662 keV gamma-rays for each Ce:LYSO and Ce:GGAG scintillator matrix were ≤14.3%. These results suggest excellent potential for its use as a high spatial medical imaging device, particularly in positron emission tomography (PET). -- Highlights: ► We developed a newly designed large-area monolithic MPPC array. ► We obtained fine gain uniformity, and good energy and time resolutions when coupled to the LYSO scintillator. ► We fabricated gamma-ray camera consisting of the MPPC array and submillimeter pixelized LYSO and GGAG scintillators. ► In

A highly sensitive CaF{sub 2}:Dy nanophosphor as an efficient low energy ion dosimetry

Energy Technology Data Exchange (ETDEWEB)

Bhadane, Mahesh S.; Hareesh, K.; Dahiwale, S.S.; Sature, K.R. [Microtron Accelerator Laboratory, Department of Physics, Savitribai Phule Pune University, Pune 411007 (India); Patil, B.J. [Department of Physics, Abasaheb Garware College, Pune 411004 (India); Asokan, K.; Kanjilal, D. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Bhoraskar, V.N. [Microtron Accelerator Laboratory, Department of Physics, Savitribai Phule Pune University, Pune 411007 (India); Dhole, S.D., E-mail: sanjay@physics.unipune.ac.in [Microtron Accelerator Laboratory, Department of Physics, Savitribai Phule Pune University, Pune 411007 (India)

2016-11-01

Highlights: • CaF{sub 2}:Dy nanophosphor synthesized by chemical co-precipitation route. • Phosphors are irradiated by H, Ar and N low energy ions at different fluences. • LEBI irradiated phosphors are characterized by XRD, TEM, FTIR and PL spectroscopy. • First time report to LEIB irradiated for thermoluminescence dosimetric applications. - Abstract: Dysprosium doped calcium fluoride (CaF{sub 2}:Dy) powers synthesized by co-precipitation method were irradiated with low energy ion beams (LEIB) viz. 100 keV H, 200 keV Ar and 350 keV N beams at different fluences and demonstrated for low energy ion dosimetric application. X-ray Diffraction and Transmission electron microscopy revealed the formation of highly crystalline cubic structured particles with size ∼45–50 nm. FTIR spectra of the CaF{sub 2}:Dy samples show changes of some bonds such as N–O asymmetric, C–F bonding and C–H aromatic contain stretching mode after LEIB irradiation. The thermoluminescence (TL) glow curve peaks were observed at 207 °C for Ar ion, at 203 °C for H ion and at 216 °C and 270 °C for N ion. It has been found that CaF{sub 2}:Dy nanophosphor shows a linear response with minimum fading for all the ion species. Computerized Glow Curve Deconvolution was performed for TL curve of high fluence ion irradiated nanophosphor to estimate the trapping parameters and the respective figure of merit (FOM) found to be very appropriate for all the nanophosphor. These results indicated that the CaF{sub 2}:Dy can be used as a low energy ion detector or dose.

Neutron capture resonances in 56Fe and 58Fe in the energy range from 10 to 100 keV

International Nuclear Information System (INIS)

Kaeppeler, F.; Wisshak, K.; Hong, L.D.

1982-11-01

The neutron capture cross section of 56 Fe and 58 Fe has been measured in the energy range from 10 to 250 keV relative to the gold standard. A pulsed 3 MV Van de Graaff accelerator and the 7 Li(p, n) reaction served as a neutron source. Capture gamma rays were detected by two C 6 D 6 detectors, which were operated in coincidence and anticoincidence mode. Two-dimensional data acquisition allowed to apply the pulse height weighting technique off-line. The samples were located at a flight path of 60 cm. The total time resolution was 1.2 ns thus allowing for an energy resolution of 2 ns/m. The experimental set-up was optimized with respect to low background and low neutron sensitivity. The additional flight path of 4 cm from the sample to the detector was sufficient to discriminate capture of sample scattered neutrons by the additional time of flight. In this way reliable results were obtained even for the strong s-wave resonances of both isotopes. The experimental capture yield was analyzed with the FANAC code. The energy resolution allowed to extract resonance parameters in the energy range from 10 to 100 keV. The individual systematic uncertainties of the experimental method are discussed in detail. They were found to range between 5 and 10% while the statistical uncertainty is 3-5% for most of the resonances. A comparison to the results of other authors exhibits in case of 56 Fe systematic differences of 7-11%. For 58 Fe the present results differ up to 50% from the only other measurement for this isotope. (orig.) [de

A Study of the 190 keV Transition in {sup 141}La

Energy Technology Data Exchange (ETDEWEB)

Berg, V; Hoeglund, Aa [Inst. of Physics, Univ. of Stockholm (Sweden); [AB Atome nergi, Nykoping (Sweden); Fogelberg, B [Inst. of Physics, Uppsala Univ. (Sweden)

1970-05-15

The gamma-ray spectrum from the decay of 18 min 141 Ba has been studied. Seventeen transitions were found below 900 keV, with energies and (intensities) as follows: 112.9{+-}0.2(3.0), 163.1{+-}0.3 (1.0), 165.7{+-}0.4(0.7), 180.5{+-}0.2(0.9), 190.3{+-}0.1(100), 276.9{+-}0.1 (52.2), 304.2{+-}0.1(55.8), 343.6{+-}0.1(30.8), 364.4{+-}0.6(1.6), 389.7{+-}0.2(2.8), 457.7{+-}0.2(10.4), 462.3{+-}0.2(10.5), 467.3{+-}0.1(11.4), 625.1{+-}0.2(6.1), 647.9{+-}0.2(10.7), 739.1{+-}0.3(8.7), 876.5{+-}0.3(6.7). K- and L-shell conversion coefficients have been measured for the 190. 3 keV transition, yielding a multipolarity of M1 + < 8 % E2. Half-life measurements using delayed coincidence technique have given the following results: T{sub 1/2} (190 keV level) = 1.27 {sup +0.06}{sub -0.10} ns, T{sub 1/2} (304 keV level) < 200 ps, T{sub 1/2} (467 keV level) < 120 ps. A level scheme of {sup 141}La has been constructed, and the spin-parity assignments of the ground state and first excited state are discussed in terms of the shell model.

Experimental studies of keV energy neutron-induced reactions relevant to astrophysics and nuclear physics

Energy Technology Data Exchange (ETDEWEB)

Shima, T.; Kii, T.; Kikuchi, T.; Okazaki, F.; Kobayashi, T.; Baba, T.; Nagai, Y. [Tokyo Inst. of Tech. (Japan). Faculty of Science; Igashira, M.

1997-03-01

Nuclear reactions induced by keV energy neutrons provide a plenty of informations for studies of both astrophysics and nuclear physics. In this paper we will show our experimental studies of neutron- induced reactions of light nuclei in the keV energy region by means of a pulsed keV neutron beam and high-sensitivity detectors. Also we will discuss astrophysical and nuclear-physical consequences by using the obtained results. (author)

Defect structures in YBa/sub 2/Cu/sub 3/O/sub 7-x/ produced by electron irradiation

International Nuclear Information System (INIS)

Kirk, M.A.; Baker, M.C.; Liu, J.Z.; Lam, D.J.; Weber, H.W.

1988-01-01

Defect structures in YBa/sub 2/Cu/sub 3/O/sub 7-x/ produced by electron irradiation at 300 K were investigated by transmission electron microscopy. Threshold energies for the production of visible defects were determined to be 152 keV and 131 keV (+- 7 keV) in directions near the a and b (b>a) axes (both perpendicular to c, the long axis in the orthorhombic structure), respectively. During above threshold irradiations in an electron flux of 3x10/sup 18/ cm/sup -2/ s/sup -1/, extended defects were observed to form and grow to sizes of 10-50 nm over 1000 s in material thickness 20-200 nm. Such low electron threshold energies suggest oxygen atom displacements with recoil energies near 20 eV. The observation of movement of twin boundaries during irradiation just above threshold suggests movement of the basal plane oxygen atoms by direct displacement or defect migration processes. Crystals irradiated above threshold were observed after about 24 hours to have transformed to a structure heavily faulted on planes perpendicular to the c axis

High-Resolution Energy and Intensity Measurements with CVD Diamond at REX-ISOLDE

CERN Document Server

Griesmayer, E; Dobos, D; Wenander, F; Bergoz, J; Bayle, H; Frais-Kölbl, H; Leinweber, J; Aumeyr, T; CERN. Geneva. BE Department

2009-01-01

A novel beam instrumentation device for the HIE-REX (High In-tensity and Energy REX) upgrade has been developed and tested at the On-Line Isotope Mass Separator ISOLDE, located at the European Laboratory for Particle Physics (CERN). This device is based on CVD diamond detector technology and is used for measuring the beam intensity, particle counting and measuring the energy spectrum of the beam. An energy resolution of 0.6% was measured at a carbon ion energy of 22.8 MeV. This corresponds to an energy spread of ± 140 keV.

The 7 keV axion dark matter and the X-ray line signal

Energy Technology Data Exchange (ETDEWEB)

Higaki, Tetsutaro [KEK, Tsukuba (Japan). Theory Center; Jeong, Kwang Sik [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Takahashi, Fuminobu [Tohoku Univ., Sendai (Japan). Dept. of Physics; Tokyo Univ., Kashiwa (Japan). Kavli IPMU, TODIAS

2014-03-15

We propose a scenario where the saxion dominates the energy density of the Universe and reheats the standard model sector via the dilatonic coupling, while its axionic partner contributes to dark matter decaying into photons via the same operator in supersymmetry. Interestingly, for the axion mass m{sub a} ≅ 7 keV and the decay constant f{sub a} ≅10{sup 14-15} GeV, the recently discovered X-ray line at 3.5 keV in the XMM Newton X-ray observatory data can be explained. We discuss various cosmological aspects of the 7 keV axion dark matter such as the production of axion dark matter, the saxion decay process, hot dark matter and isocurvature constraints on the axion dark matter, and the possible baryogenesis scenarios.

Radiation scattering back to the plasma by the tokamak inner wall in the energy range 50-500 keV during lower hybrid current drive

International Nuclear Information System (INIS)

Peysson, Y.

1990-10-01

We describe the wall reflectivity by the ratio between the number of photons emerging from the wall and the number entering - and determine the proportion of the reflected contribution to the detected radiations. Various emission profiles and plasma positions in the tokamak chamber have been considered. The contribution of multiple reflections has also be investigated. The wall reflectivity can lead to spurious conclusions for a peaked radial profile in the vicinity of the plasma edge. The next step is devoted to the resolution of the radiation transport equation in solid matter. As an heterogeneous medium is considered - carbon tiles brazed on an iron bulk -, the solution is determined by a numerical Monte-Carlo method. The reflectivity is greatly enhanced by a carbon layer between 50 keV and 150 keV, even for a thickness of one centimeter. The reflectivity is then nearly independent of the energy of the entering photons up to 500 KeV, and lies between 0.15 and 0.4 from a perpendicular to a nearly tangential incidence. Angular corrections have also been considered. Finally, a fully description of the X-ray reflectivity in the high energy range has been performed, taking account of the toroidal geometry and the exact solution of the radiation transport equation. Comparison between theoretical and experimental results obtained with the Tore-Supra high energy X-ray spectrometer has been done. A strong reflectivity effect is observed for the more peripheral line of sight when the plasma emission profile is peaked. There is a good agreement for the total number of detected photons with an energy greater than 100 keV The measured energy spectrum lies up to 200 keV when the photon energy spectrum of the plasma determined from the central chords extends up to 500 keV. A procedure to determine the energy threshold above which the photon energy spectrum is free of the reflected contribution is proposed

Two-dimensional analysis of three-body reactions 11B(p,αα) from 163 keV to MeV

International Nuclear Information System (INIS)

Engelhardt, D.; Fontenille, J.

1967-01-01

An experimental apparatus for two-dimensions analysis of the break-up of 12 C * produced by the reaction 11 B(p,αα) 4 He, at proton bombarding energies between 163 keV and 2 MeV, is described. It uses Si surface barrier detectors and, fast-slow coincidence techniques: the energy resolution is about 40 keV and time resolution 6 ns. A 4096 channel analyser and a small digital computer was used for information storage and data processing. The experimental set-up was tested on the C.E.N.G. 2 MeV Van de Graaff accelerator. The spectra of the 12 C * decay products taken at proton bombarding energies of 163 keV and 680 keV at different angles between the two α-counters are shown. They indicate strong evidence for sequential decay of 12 C * to the 8 Be fundamental, first or second excited level. (authors) [fr

Performance of a monolithic LaBr{sub 3}:Ce crystal coupled to an array of silicon photomultipliers

Energy Technology Data Exchange (ETDEWEB)

Ulyanov, Alexei, E-mail: alexey.uliyanov@ucd.ie [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Morris, Oran [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Department of Computer Science & Applied Physics, Galway-Mayo Institute of Technology, Galway (Ireland); Hanlon, Lorraine; McBreen, Sheila; Foley, Suzanne; Roberts, Oliver J.; Tobin, Isaac; Murphy, David; Wade, Colin [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Nelms, Nick; Shortt, Brian [European Space Agency, ESTEC, 2200 AG Noordwijk (Netherlands); Slavicek, Tomas; Granja, Carlos; Solar, Michael [Institute of Experimental and Applied Physics, Czech Technical University in Prague, 12800 Prague 2 (Czech Republic)

2016-02-21

A gamma-ray detector composed of a single 28×28×20 mm{sup 3} LaBr{sub 3}:Ce crystal coupled to a custom built 4×4 array of silicon photomultipliers was tested over an energy range of 30 keV to 9.3 MeV. The silicon photomultipliers were initially calibrated using 20 ns light pulses generated by a light emitting diode. The photodetector responses measured as a function of the number of incident photons were found to be non-linear and consistent with model predictions. Using corrections for the non-linearity of the silicon photomultipliers, the detector showed a linear response to gamma-rays with energies from 100 keV to the maximum available energy of 9.3 MeV. The energy resolution was found to be 4% FWHM at 662 keV. Despite the large thickness of the scintillator (20 mm) and a 5 mm thick optical window, the detector was capable of measuring the positions of the gamma-ray interaction points. The position resolution was measured at 356 keV and was found to be 8 mm FWHM in the detector plane and 11 mm FWHM for the depth of interaction. The detector can be used as a building block of a larger calorimeter system that is capable of measuring gamma-ray energies up to tens of MeV.

Portable high energy gamma ray imagers

International Nuclear Information System (INIS)

Guru, S.V.; Squillante, M.R.

1996-01-01

To satisfy the needs of high energy gamma ray imagers for industrial nuclear imaging applications, three high energy gamma cameras are presented. The RMD-Pinhole camera uses a lead pinhole collimator and a segmented BGO detector viewed by a 3 in. square position sensitive photomultiplier tube (PSPMT). This pinhole gamma camera displayed an energy resolution of 25.0% FWHM at the center of the camera at 662 keV and an angular resolution of 6.2 FWHM at 412 keV. The fixed multiple hole collimated camera (FMCC), used a multiple hole collimator and a continuous slab of NaI(Tl) detector viewed by the same PSPMT. The FMCC displayed an energy resolution of 12.4% FWHM at 662 keV at the center of the camera and an angular resolution of 6.0 FWHM at 412 keV. The rotating multiple hole collimated camera (RMCC) used a 180 antisymmetric rotation modulation collimator and CsI(Tl) detectors coupled to PIN silicon photodiodes. The RMCC displayed an energy resolution of 7.1% FWHM at 662 keV and an angular resolution of 4.0 FWHM at 810 keV. The performance of these imagers is discussed in this paper. (orig.)

Effective atomic numbers and electron densities of some biologically important compounds containing H, C, N and O in the energy range 145-1330 keV

International Nuclear Information System (INIS)

Manjunathaguru, V; Umesh, T K

2006-01-01

A semi-empirical relation which can be used to determine the total attenuation cross sections of samples containing H, C, N and O in the energy range 145-1332 keV has been derived based on the total attenuation cross sections of several sugars, amino acids and fatty acids. The cross sections have been measured by performing transmission experiments in a narrow beam good geometry set-up by employing a high-resolution hyperpure germanium detector at seven energies of biological importance such as 145.4 keV, 279.2 keV, 514 keV, 661.6 keV, 1115.5 keV, 1173.2 keV and 1332.1 keV. The semi-empirical relation can reproduce the experimental values within 1-2%. The total attenuation cross sections of five elements carbon, aluminium, titanium, copper and zirconium measured in the same experimental set-up at the energies mentioned above have been used in a new matrix method to evaluate the effective atomic numbers and the effective electron densities of samples such as cholesterol, fatty acids, sugars and amino acids containing H, C, N and O atoms from their effective atomic cross sections. The effective atomic cross sections are the total attenuation cross sections divided by the total number of atoms of all types in a particular sample. Further, a quantity called the effective atomic weight was defined as the ratio of the molecular weight of a sample to the total number of atoms of all types in it. The variation of the effective atomic number was systematically studied with respect to the effective atomic weight and a new semi-empirical relation for Z eff has been evolved. It is felt that this relation can be very useful to determine the effective atomic number of any sample having H, C, N and O atoms in the energy range 145-1332 keV irrespective of its chemical structure

Study of SiO2 surface sputtering by a 250-550 keV He+ ion beam during high-resolution Rutherford backscattering measurements

International Nuclear Information System (INIS)

Kusanagi, Susumu; Kobayashi, Hajime

2006-01-01

Decreases in oxygen signal intensities in spectra of high-resolution Rutherford backscattering spectrometry (HRBS) were observed during measurements on a 5-nm thick SiO 2 layer on a Si substrate when irradiated by 250-550 keV He + ions. Shifts in an implanted arsenic profile in a 5-nm thick SiO 2 /Si substrate were also observed as a result of He + ion irradiation. These results lead to the conclusion that the SiO 2 surface was sputtered by He + ions in this energy range

Applications of an energy-dispersive pnCCD for X-ray reflectivity: Investigation of interdiffusion in Fe-Pt multilayers

Energy Technology Data Exchange (ETDEWEB)

Abboud, Ali; Send, Sebastian; Pietsch, Ullrich [Universitaet Siegen, FB Physik, Walter-Flex-Strasse 3, 57072 Siegen (Germany); Hartmann, Robert [PNSensor GmbH, Muenchen (Germany); Strueder, Lothar [Universitaet Siegen, FB Physik, Walter-Flex-Strasse 3, 57072 Siegen (Germany); Planck-Institut fuer extraterrestrische Physik (MPE), Muenchen (Germany); MPI Halbleiterlabor, Muenchen (Germany); Savan, Alan; Ludwig, Alfred [Ruhr-Universitaet Bochum, Bochum (Germany); Zotov, Nikolay [Forschungszentrum Juelich, Juelich (Germany)

2011-11-15

A frame store pn-junction CCD (pnCCD) detector was applied to study thermally induced interdiffusion in Fe/Pt thin film multilayers (MLs) in a temperature range between 300 and 585 K. Based on the energy resolution of the detector the reflectivity was measured simultaneously in a spectral range between 8 keV < E < 20 keV including the Pt L-edge energies close to 11.5 keV. Above T = 533 K we find a strong drop of intensities at 1st and 2nd order ML Bragg peak interpreted by mutual interdiffusion. Considering a simulated model of interdiffusion it has been found that the concentration of iron that diffuses into the platinum sub layers is higher than that of platinum into iron. The time dependence of inter diffusion was also calculated in the range of 533-568 K and was described by the Arrhenius equation D(T) = D{sub 0} exp(-H{sub a}/k{sub B}T). The activation energy for the MLs used [Fe 1.7 nm/Pt 2 nm]{sub 50} was found to be 0.94 {+-} 0.22 eV. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

High resolution fast neutron spectrometry without time-of-flight

International Nuclear Information System (INIS)

Evans, A.E.; Brandenberger, J.D.

1978-01-01

Performance tests of a spectrometer tube of the type developed by Cuttler and Shalev show that the measurement of fast neutron spectra with this device can be made with an energy resolution previously obtainable only in large time-of-flight facilities. In preliminary tests, resolutions of 16.4 keV for thermal neutrons and 30.9 keV for 1-MeV neutrons were obtained. A broad-window pulse-shape discrimination (PSD) system is used to remove from pulse-height distributions most of the continua due to 3 He-recoil events, noise, and wall effect. Use of PSD improved the energy resolution to 12.9 keV for thermal neutrons and 29.2 keV for 1-MeV neutrons. The detector is a viable tool for neutron research at nominally equipped accelerator laboratories

Optimization of Monochromated TEM for Ultimate Resolution Imaging and Ultrahigh Resolution Electron Energy Loss Spectroscopy

KAUST Repository

Lopatin, Sergei; Cheng, Bin; Liu, Wei-Ting; Tsai, Meng-Lin; He, Jr-Hau; Chuvilin, Andrey

2017-01-01

The performance of a monochromated transmission electron microscope with Wien type monochromator is optimized to achieve an extremely narrow energy spread of electron beam and an ultrahigh energy resolution with spectroscopy. The energy spread in the beam is improved by almost an order of magnitude as compared to specified values. The optimization involves both the monochromator and the electron energy loss detection system. We demonstrate boosted capability of optimized systems with respect to ultra-low loss EELS and sub-angstrom resolution imaging (in a combination with spherical aberration correction).

Optimization of Monochromated TEM for Ultimate Resolution Imaging and Ultrahigh Resolution Electron Energy Loss Spectroscopy

KAUST Repository

Lopatin, Sergei

2017-09-01

The performance of a monochromated transmission electron microscope with Wien type monochromator is optimized to achieve an extremely narrow energy spread of electron beam and an ultrahigh energy resolution with spectroscopy. The energy spread in the beam is improved by almost an order of magnitude as compared to specified values. The optimization involves both the monochromator and the electron energy loss detection system. We demonstrate boosted capability of optimized systems with respect to ultra-low loss EELS and sub-angstrom resolution imaging (in a combination with spherical aberration correction).

Determination of Psub(K) values to the 172, 103 and 97 keV levels and the fluorescence yield. omega. sub(K) of Eu after electron capture by /sup 153/Gd

Energy Technology Data Exchange (ETDEWEB)

Singh, K; Grewal, B S; Sahota, H S [Punjabi Univ., Patiala (India). Dept. of Physics

1985-03-01

From an analysis of K x-ray-..gamma..-ray sum peaks observed with an intrinsic Ge detector the K-capture probabilities (Psub(K)) to the 172, 103 and 97 keV levels in the decay of /sup 153/Gd have been determined; these yield an electron-capture energy Qsub(EC)=245 +- 2. The K-capture probability to the 172 keV level differs significantly from that found in the literature. With these results the K-shell fluorescence yield of Eu is ..omega..sub(K)=0.935 +- 0.019.

The energy spectrum of 662 keV photons in a water equivalent phantom

International Nuclear Information System (INIS)

Akar Tarim, U.; Gurler, O.; Ozmutlu, E.N.; Yalcin, S.; Gundogdu, O.; Sharaf, J.M.; Bradley, D.A.

2012-01-01

Investigation is made on the energy spectrum of photons originating from interactions of 662 keV primary gamma-ray photons emitted by a point source positioned at the centre of a water equivalent solid phantom of dimensions 19 cm×19 cm×24 cm. Peaks resulting from total energy loss (photopeak) and multiple and back scattering have been observed using a 51 mm×51 mm NaI(Tl) detector; good agreement being found between the measured and simulated response functions. The energy spectrum of the gamma photons obtained through the Monte Carlo simulation reveals local maxima at about 100 keV and 210 keV, being also observed in the experimental response function. Such spectra can be used as a method of testing the water equivalence of solid phantom media before their use for dosimetry measurements. - Highlights: ► Peaks resulting from total energy loss (photopeak) and multiple and back scattering were observed. ► Energy distribution of γ-ray photons from a point source at the centre of a water equivalent solid phantom. ► The method can be applied to various detector geometries.

A position sensitive detector using a NaI(Tl)/photomultiplier tube combination for the energy range 200 keV to 10 MeV

International Nuclear Information System (INIS)

Court, A.J.; Dean, A.J.; Yearworth, M.; Younis, F.; Chiappetti, L.; Perotti, F.; Villa, G.; Ubertini, P.; La Padula, C.

1988-01-01

The performance of the position sensitive detector for the ZEBRA low energy gamma-ray imaging telescope is described. The detector consists of 9 position sensitive NaI(Tl) elements each 5.8x5.0x56.0 cm viewed at either end of the long axis by 2 in. photomultiplier tubes. The total active area is 2470 cm 2 with an average positional resolution of 2.1 cm and energy resolution of 15% FWHM at 661.6 keV. The method of flight calibration is described together with the provision within the on-board electronics to correct for sources of error in the calculation of event energy loss and position. The results presented are obtained from the calibration phase of the ZEBRA telescope project. (orig.)

Double excitation of helium in collisions with proton and antiproton impact in the energy range 50-500 keV

International Nuclear Information System (INIS)

Purkait, M.

2009-01-01

Double-electron excitation processes of helium atoms by proton and antiproton impact have been theoretically investigated using the four-body formalism of boundary corrected continuum intermediate state (BCCIS-4B) approximation in the energy range of 50-500 keV. In this formalism, the presence of the projectile in the exit channels is described by distorting the final bound state wave functions with coulomb waves (associated with the projectile-electron interactions). The results are in good agreement with the other theoretical and experimental results. Reasonably better agreements have been found in the intermediate and high energy regions. Contributions to the cross section of the different magnetic sub-shells are also analysed.

High spectral resolution studies of gamma ray bursts on new missions

International Nuclear Information System (INIS)

Desai, U. D.; Acuna, M. H.; Cline, T. L.; Dennis, B. R.; Orwig, L. E.; Trombka, J. I.; Starr, R. D.

1996-01-01

Two new missions will be launched in 1996 and 1997, each carrying X-ray and gamma ray detectors capable of high spectral resolution at room temperature. The Argentine Satelite de Aplicaciones Cientificas (SAC-B) and the Small Spacecraft Technology Initiative (SSTI) Clark missions will each carry several arrays of X-ray detectors primarily intended for the study of solar flares and gamma-ray bursts. Arrays of small (1 cm 2 ) cadmium zinc telluride (CZT) units will provide x-ray measurements in the 10 to 80 keV range with an energy resolution of ≅6 keV. Arrays of both silicon avalanche photodiodes (APD) and P-intrinsic-N (PIN) photodiodes (for the SAC-B mission only) will provide energy coverage from 2-25 keV with ≅1 keV resolution. For SAC-B, higher energy spectral data covering the 30-300 keV energy range will be provided by CsI(Tl) scintillators coupled to silicon APDs, resulting in similar resolution but greater simplicity relative to conventional CsI/PMT systems. Because of problems with the Pegasus launch vehicle, the launch of SAC-B has been delayed until 1997. The launch of the SSTI Clark mission is scheduled for June 1996

A condensed matter electron momentum spectrometer with parallel detection in energy and momentum

Energy Technology Data Exchange (ETDEWEB)

Storer, P; Caprari, R S; Clark, S A.C.; Vos, M; Weigold, E

1994-03-01

An electron momentum spectrometer has been constructed which measures electron binding energies and momenta by fully determining the kinematics of the incident, scattered and ejected electrons resulting from (e,2e) ionizing collisions in a thin solid foil. The spectrometer operates with incident beam energies of 20-30 keV in an asymmetric, non-coplanar scattering geometry. Bethe ridge kinematics are used. The technique uses transmission through the target foil, but it is most sensitive to the surface from which the 1.2 keV electrons emerge, to a depth of about 5 nm. Scattered and ejected electron energies and azimuthal angles are detected in parallel using position sensitive detection, yielding true coincidence count rates of 6 Hz from a 5.5 nm thick evaporated carbon target and an incident beam current of around 100 nA. The energy resolution is approximately 1.3 eV and momentum resolution approximately 0.15 a{sub 0}{sup -1}. The energy resolution could readily be improved by monochromating the incident electron beam. 28 refs., 15 figs.

Correlation between blister skin thickness, the maximum in the damage-energy distribution, and projected ranges of helium ions in Nb for the energy range 10 to 1500 keV

International Nuclear Information System (INIS)

St-Jacques, R.G.; Martel, J.G.; Terreault, B.; Veilleux, G.; Das, S.K.; Kaminsky, M.; Fenske, G.

1976-01-01

The skin thickness of blisters formed on polycrystalline niobium by 4 He + irradiation at room temperature for energies from 15 to 80 keV have been measured. Similar measurements were conducted for 10 keV 4 He + irradiation at 500 0 C to increase blister exfoliation, and thereby allow examination of a larger number of blister skins. For energies smaller than 100 keV the skin thicknesses are compared with the projected range and the damage-energy distributions constructed from moments interpolated from Winterbon's tabulated values. For energies of 10 and 15 keV the projected ranges and damage-energy distributions have also been computed with a Monte Carlo program. For energies larger than 100 keV the projected ranges of 4 He + in Nb were calculated using either Brice's formalism or the one given by Schiott. The thicknesses for 60 and 80 keV, and those reported earlier for 100 to 1500 keV correlate well with calculated projected ranges. For energies lower than 60 keV the measured thicknesses are larger than the calculated ranges

Measurement of the 232Th capture cross section in the energy region 5 keV-150 keV

International Nuclear Information System (INIS)

Lobo, G.; Schillebeeckx, P.; Brusegan, A.; Borella, A.; Corvi, F.; Janeva, N.; Volev, K.

2003-01-01

The 232 Th(n,γ) neutron capture cross-section is of great importance for accelerator driven reactor (ADS) systems based on the Thorium-Uranium fuel cycle. An analysis of the required nuclear data, reveals that the status of the 232 Th capture data is far from the requested 2 % uncertainty level. Recently 232 Th average capture measurements, between 5-200 keV neutron energy, were performed at the FzK Karlsruhe (DE). A comparison of the measured averaged capture cross section with the evaluated data files shows a reasonable agreement in the neutron energy range above 15 keV. However, discrepancies of up to 40 % at lower neutron energies are observed. The same order of discrepancies is observed when comparing their results with the results obtained by Macklin et al. at ORELA. To clarify these discrepancies we measured at IRMM the average capture cross-section at the GEel LINear Accelerator (GELINA). The measurements were performed at a 14.37 m flight-path using the Time-Of-Flight (TOF) method. The gamma rays, originating from the 232 Th(n,γ) reaction, were detected by a pair of C 6 D 6 -based liquid scintillators applying a pulse-height weighting method. The neutron flux was measured with an ionisation chamber placed at 80 cm before the Thorium sample. This chamber has a cathode loaded with two back-to-back layers of about 40 μg/cm 2 10 B. The sample consisted of a metallic natural thorium disc of 8 cm diameter and 0.5 mm thick, corresponding to a thickness of 1.588 10 -3 at/b. The background for the capture measurements consists of a time independent and time dependent component. The former, mainly produced by the radioactive decay of the sample, was deduced from measurements with a closed beam. The latter was measured by replacing the thorium sample with a 0.5 mm thick 208 Pb sample of the same size. Such a Pb sample has practically the same scattering probability as the thorium sample and has a negligible capture yield. Therefore, the 208 Pb run provides a good

Fresnel zone-plate based X-ray microscopy in Zernike phase contrast with sub-50 nm resolution at NSRL

International Nuclear Information System (INIS)

Chen Jie; Li Wenjie; Tian Jinping; Liu Longhua; Xiong Ying; Liu Gang; Wu Ziyu; Tian Yangchao; Liu Yijin; Yue Zhengbo; Yu Hanqing; Wang Chunru

2009-01-01

A transmission X-ray microscope using Fresnel zone-plates (FZPs) has been installed at U7A beamline of National Synchrotron Radiation Laboratory (NSRL). The objective FZP with 45 nm outermost zone width delivers a sub-50 nm resolution. A gold phase ring with 2.5 μm thickness and 4 μm width was placed at the focal plane of the objective FZP at 8 keV to produce a negative Zernike phase contrast. A series of samples were used to test the performance of the Zernike phase contrast X-ray microscopy.

Fresnel zone-plate based X-ray microscopy in Zernike phase contrast with sub-50 nm resolution at NSRL

Energy Technology Data Exchange (ETDEWEB)

Chen Jie; Li Wenjie; Tian Jinping; Liu Longhua; Xiong Ying; Liu Gang; Wu Ziyu; Tian Yangchao [National Synchrotron Radiation Laboratory (China); Liu Yijin [School of Physics (China); Yue Zhengbo; Yu Hanqing [Laboratory of Environmental Engineering, School of Chemistry, University of Science and Technology of China, Hefei Anhui 230029 (China); Wang Chunru, E-mail: ychtian@ustc.edu.c [Institute of Chemistry, Chinese Academy of Sciences, Beijing 10060 (China)

2009-09-01

A transmission X-ray microscope using Fresnel zone-plates (FZPs) has been installed at U7A beamline of National Synchrotron Radiation Laboratory (NSRL). The objective FZP with 45 nm outermost zone width delivers a sub-50 nm resolution. A gold phase ring with 2.5 {mu}m thickness and 4 {mu}m width was placed at the focal plane of the objective FZP at 8 keV to produce a negative Zernike phase contrast. A series of samples were used to test the performance of the Zernike phase contrast X-ray microscopy.

Effective atomic numbers for photon energy absorption of essential amino acids in the energy range 1 keV to 20 MeV

International Nuclear Information System (INIS)

Manohara, S.R.; Hanagodimath, S.M.

2007-01-01

Effective atomic numbers for photon energy-absorption (Z PEAeff ) of essential amino acids histidine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine have been calculated by a direct method in the energy region of 1 keV to 20 MeV. The Z PEAeff values have been found to change with energy and composition of the amino acids. The variations of mass energy-absorption coefficient, effective atomic number for photon interaction (Z PIeff ) and Z PEAeff with energy are shown graphically. Significant differences exist between Z PIeff and the Z PEAeff in the energy region of 8-100 keV for histidine and threonine; 6-100 keV for leucine, lysine, tryptophan, phenylalanine and valine; 15-400 keV for methionine. The effect of absorption edge on effective atomic numbers and the possibility of defining two set values of these parameters at the K-absorption edge of high-Z element present in the amino acids are discussed. The reasons for using Z PEAeff rather than the commonly used Z PIeff in medical radiation dosimetry for the calculation of absorbed dose in radiation therapy are also discussed

Contribution to the study of (d,p) and (d,{alpha}> reactions on {sup 16}O and {sup 11}B from 200 keV to 1 MeV; Contribution a l'etude des reactions (d,p) et (d,{alpha}) sur {sup 16}O et {sup 11}B de 200 keV a 1 MeV

Energy Technology Data Exchange (ETDEWEB)

Longequeue, N [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1965-05-01

The reactions {sup 16}O(d,{alpha}{sub 0}), (d,p{sub 0}), (d,p{sub 1}) and {sup 11}B(d,{alpha}{sub 0}), (d,{alpha}{sub 2}), (d,p{sub 0}) have been studied from 200 keV to 1 MeV. The interpretation of (d,{alpha}) reactions by the compound nucleus theory has shown the presence of {sup 18}F levels (7,94 MeV, 1+; 8,09 MeV, 1+ ) and of {sup 13}C level (19 MeV, 3/2{+-} or 5/2-). The interpretation of {sup 16}O(d,p{sub 1}) and {sup 11}B(d,p{sub 0}) reactions at energies lower than 400 keV has been given by a theory of Coulomb stripping. (author) [French] L'etude experimentale des reactions {sup 16}O(d,{alpha}{sub 0}); (d,p{sub 0}), (d,p{sub 1}) et {sup 11}B(d,{alpha}{sub 0}), (d,{alpha}{sub 2}), (d,p{sub 0}) a ete faite de 200 keV a 1 Mev. L'interpretation des reactions (d,a) par la theorie du noyau compose a permis la mise en evidence de niveaux du {sup 18}F (7,94 MeV, 1+; 8,09MeV, 1+ ) et du {sup 13}C(19 MeV, 3/2{+-} ou 5/2-). L'interpretation des reactions {sup 16}O(d,p{sub 1}) et {sup 11}B(d,p{sub 0}), a basse energie (< 400 keV), par une theorie de stripping de Coulomb, a ete donnee.

Development of a TPC for energy and fluence references in low energies neutronic fields (from 8 keV to 5 MeV)

International Nuclear Information System (INIS)

Maire, Donovan

2015-01-01

In order to judge the measurement reliability, metrology requires to measure quantities with their uncertainties, in relation to a reference through a documented and unbroken chain of calibrations. In neutron radiation field, instrument response has to be known as a function of the neutron energy. Then detector calibrations are required using reference neutron fields. In France, primary reference neutron fields are held by the LNE-IRSN, at the Laboratory for Neutron Metrology and Dosimetry (LMDN). In order to improve reference neutron field characterization, the LNE-IRSN MIMAC μTPC has been developed. This detector is a Time Projection Chamber (TPC), using a gas at low pressure (30 mbar abs. to 1 bar abs.). Nuclear recoils are generated by neutron elastic scattering onto gas atoms. By measuring the nuclear recoil energy and scattering angle, the μTPC detector is able to measure the energy distribution of the neutron fluence between 8 keV and 5 MeV. The main challenge was to perform accurate spectrometry of neutron fields in the keV range, following a primary procedure. First of all, a metrological approach was followed in order to master every physical process taking part in the neutron detection. This approach led to develop the direct and inverse models, representing the detector response function and its inverse function respectively. Using this detailed characterization, the energy distribution of the neutron fluence has been measured for a continuous neutron field of 27 keV. The reconstructed energy is 28,2 ± 4,5 keV, the difference between μTPC integral fluence measurement and other measurement methods is less than 6%. The LNE-IRSN MIMAC μTPC system becomes the only one system able to measure simultaneously energy and fluence at energies lower than 100 keV, following a primary procedure. The project goal is then reached. These measurements at energies lower than 100 keV shows also a non-linearity between the ionization charge and the ion kinetic energy

A space-based, high-resolution view of notable changes in urban NO <sub>x> pollution around the world (2005-2014)

Energy Technology Data Exchange (ETDEWEB)

Duncan, Bryan N. [NASA Goddard Space Flight Center, Greenbelt Maryland USA; Lamsal, Lok N. [NASA Goddard Space Flight Center, Greenbelt Maryland USA; Goddard Earth Sciences Technology and Research, Universities Space Research Association, Columbia Maryland USA; Thompson, Anne M. [NASA Goddard Space Flight Center, Greenbelt Maryland USA; Yoshida, Yasuko [NASA Goddard Space Flight Center, Greenbelt Maryland USA; Science Systems and Applications, Inc., Greenbelt Maryland USA; Lu, Zifeng [Argonne National Laboratory, Argonne Illinois USA; Streets, David G. [Argonne National Laboratory, Argonne Illinois USA; Hurwitz, Margaret M. [NASA Goddard Space Flight Center, Greenbelt Maryland USA; GESTAR, Morgan State University, Baltimore Maryland USA; Pickering, Kenneth E. [NASA Goddard Space Flight Center, Greenbelt Maryland USA

2016-01-20

Nitrogen oxides (NO<sub>x> = NO + NO<sub>2sub>) are produced during combustion processes and, thus may serve as a proxy for fossil fuel-based energy usage and coemitted greenhouse gases and other pollutants. We use high-resolution nitrogen dioxide (NO<sub>2sub>) data from the Ozone Monitoring Instrument (OMI) to analyze changes in urban NO<sub>2sub> levels around the world from 2005 to 2014, finding complex heterogeneity in the changes. We discuss several potential factors that seem to determine these NO<sub>x> changes. First, environmental regulations resulted in large decreases. The only large increases in the United States may be associated with three areas of intensive energy activity. Second, elevated NO<sub>2sub> levels were observed over many Asian, tropical, and subtropical cities that experienced rapid economic growth. Two of the largest increases occurred over recently expanded petrochemical complexes in Jamnagar (India) and Daesan (Korea). Third, pollution transport from China possibly influenced the Republic of Korea and Japan, diminishing the impact of local pollution controls. However, in China, there were large decreases over Beijing, Shanghai, and the Pearl River Delta, which were likely associated with local emission control efforts. Fourth, civil unrest and its effect on energy usage may have resulted in lower NO<sub>2sub> levels in Libya, Iraq, and Syria. Fifth, spatial heterogeneity within several megacities may reflect mixed efforts to cope with air quality degradation. We also show the potential of high-resolution data for identifying NO<sub>x> emission sources in regions with a complex mix of sources. Finally, intensive monitoring of the world's tropical/subtropical megacities will remain a priority, as their populations and emissions of pollutants and greenhouse gases are expected to increase significantly.

Quantitative analysis and efficiency study of PSD methods for a LaBr{sub 3}:Ce detector

Energy Technology Data Exchange (ETDEWEB)

Zeng, Ming; Cang, Jirong [Key Laboratory of Particle & Radiation Imaging(Tsinghua University), Ministry of Education (China); Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Zeng, Zhi, E-mail: zengzhi@tsinghua.edu.cn [Key Laboratory of Particle & Radiation Imaging(Tsinghua University), Ministry of Education (China); Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Yue, Xiaoguang; Cheng, Jianping; Liu, Yinong; Ma, Hao; Li, Junli [Key Laboratory of Particle & Radiation Imaging(Tsinghua University), Ministry of Education (China); Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

2016-03-21

The LaBr{sub 3}:Ce scintillator has been widely studied for nuclear spectroscopy because of its optimal energy resolution (<3%@ 662 keV) and time resolution (~300 ps). Despite these promising properties, the intrinsic radiation background of LaBr{sub 3}:Ce is a critical issue, and pulse shape discrimination (PSD) has been shown to be an efficient potential method to suppress the alpha background from the {sup 227}Ac. In this paper, the charge comparison method (CCM) for alpha and gamma discrimination in LaBr{sub 3}:Ce is quantitatively analysed and compared with two other typical PSD methods using digital pulse processing. The algorithm parameters and discrimination efficiency are calculated for each method. Moreover, for the CCM, the correlation between the CCM feature value distribution and the total charge (energy) is studied, and a fitting equation for the correlation is inferred and experimentally verified. Using the equations, an energy-dependent threshold can be chosen to optimize the discrimination efficiency. Additionally, the experimental results show a potential application in low-activity high-energy γ measurement by suppressing the alpha background.

Photoelectron spectroscopy in a wide hν region from 6 eV to 8 keV with full momentum and spin resolution

Energy Technology Data Exchange (ETDEWEB)

Suga, Shigemasa, E-mail: ssmsuga@gmail.com [Institute of Scientific and Industrial Research, Osaka University, Osaka (Japan); Max-Planck-Institute für Mikrostrukturphysik, Weinberg 2, 06120 Halle (Germany); Tusche, Christian [Max-Planck-Institute für Mikrostrukturphysik, Weinberg 2, 06120 Halle (Germany)

2015-04-15

Highlights: • Full two-dimensional angle resolved photoelectron spectroscopy (2D-ARPES). • Spin-resolved ARPES (SP-ARPES) with very high spin detection efficiency. • Aberration corrected double hemispherical deflection analyzers (HDAs). • Momentum microscopy (M.M.) with high energy and momentum resolutions. • Spin resolved momentum microscopy with capability of micro-nano region detection. - Abstract: High resolution photoelectron spectroscopy is recognized to be a very powerful approach to study surface and bulk electronic structures of various solids by employing different photon energies (hν). In particular, angle resolved photoelectron spectroscopy (ARPES) has progressed dramatically in the last few decades providing useful information on Fermi surface (FS) topology and band dispersions. The information of the electron spin is often decisive to fully understand the electronic properties of many material classes. However, spin-resolved studies by photoelectron spectroscopy were strongly hindered by the low detection efficiency of spin detectors. In the case of surface electronic structures, possible surface degradation with time is a serious problem to discuss intrinsic electronic effects. Therefore rather fast and high efficiency detection is required in the case of surface sensitive spin-resolved ARPES. Two-dimensional (2D) detection is nowadays widely employed in ARPES. In the use of a conventional hemispherical deflection analyzer (HDA), one direction on the 2D detector corresponds to the binding energy E{sub B} and the other direction to the emission angle. The novel concept of momentum microscopy, however, directly provides 2D (k{sub x},k{sub y}) maps of the photoemission intensities. The reciprocal space image directly represents the cross section through the valence band structure of the sample at a selected energy. By scanning E{sub B}, very high resolution three-dimensional E{sub B}(k{sub x},k{sub y}) maps of the band-dispersion can be

Scanning SQUID susceptometers with sub-micron spatial resolution

Energy Technology Data Exchange (ETDEWEB)

Kirtley, John R., E-mail: jkirtley@stanford.edu; Rosenberg, Aaron J.; Palmstrom, Johanna C.; Holland, Connor M.; Moler, Kathryn A. [Department of Applied Physics, Stanford University, Stanford, California 94305-4045 (United States); Paulius, Lisa [Department of Physics, Western Michigan University, Kalamazoo, Michigan 49008-5252 (United States); Spanton, Eric M. [Department of Physics, Stanford University, Stanford, California 94305-4045 (United States); Schiessl, Daniel [Attocube Systems AG, Königinstraße 11A, 80539 Munich (Germany); Jermain, Colin L.; Gibbons, Jonathan [Department of Physics, Cornell University, Cornell, Ithaca, New York 14853 (United States); Fung, Y.-K.K.; Gibson, Gerald W. [IBM Research Division, T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Huber, Martin E. [Department of Physics, University of Colorado Denver, Denver, Colorado 80217-3364 (United States); Ralph, Daniel C. [Department of Physics, Cornell University, Cornell, Ithaca, New York 14853 (United States); Kavli Institute at Cornell, Ithaca, New York 14853 (United States); Ketchen, Mark B. [OcteVue, Hadley, Massachusetts 01035 (United States)

2016-09-15

Superconducting QUantum Interference Device (SQUID) microscopy has excellent magnetic field sensitivity, but suffers from modest spatial resolution when compared with other scanning probes. This spatial resolution is determined by both the size of the field sensitive area and the spacing between this area and the sample surface. In this paper we describe scanning SQUID susceptometers that achieve sub-micron spatial resolution while retaining a white noise floor flux sensitivity of ≈2μΦ{sub 0}/Hz{sup 1/2}. This high spatial resolution is accomplished by deep sub-micron feature sizes, well shielded pickup loops fabricated using a planarized process, and a deep etch step that minimizes the spacing between the sample surface and the SQUID pickup loop. We describe the design, modeling, fabrication, and testing of these sensors. Although sub-micron spatial resolution has been achieved previously in scanning SQUID sensors, our sensors not only achieve high spatial resolution but also have integrated modulation coils for flux feedback, integrated field coils for susceptibility measurements, and batch processing. They are therefore a generally applicable tool for imaging sample magnetization, currents, and susceptibilities with higher spatial resolution than previous susceptometers.

DISPLACEMENT CASCADE SIMULATION IN TUNGSTEN UP TO 200 KEV OF DAMAGE ENERGY AT 300, 1025, AND 2050 K

Energy Technology Data Exchange (ETDEWEB)

Setyawan, Wahyu; Nandipati, Giridhar; Roche, Kenneth J.; Kurtz, Richard J.; Wirth, Brian D.

2015-09-22

We generated molecular dynamics database of primary defects that adequately covers the range of tungsten recoil energy imparted by 14-MeV neutrons. During this semi annual period, cascades at 150 and 200 keV at 300 and 1025 K were simulated. Overall, we included damage energy up to 200 keV at 300 and 1025 K, and up to 100 keV at 2050 K. We report the number of surviving Frenkel pairs (NF) and the size distribution of defect clusters. The slope of the NF curve versus cascade damage energy (EMD), on a log-log scale, changes at a transition energy (μ). For EMD > μ, the cascade forms interconnected damage regions that facilitate the formation of large clusters of defects. At 300 K and EMD = 200 keV, the largest size of interstitial cluster and vacancy cluster is 266 and 335, respectively. Similarly, at 1025 K and EMD = 200 keV, the largest size of interstitial cluster and vacancy cluster is 296 and 338, respectively. At 2050 K, large interstitial clusters also routinely form, but practically no large vacancy clusters do

Optimal energy window setting depending on the energy resolution for radionuclides used in gamma camera imaging. Planar imaging evaluation

International Nuclear Information System (INIS)

Kojima, Akihiro; Watanabe, Hiroyuki; Arao, Yuichi; Kawasaki, Masaaki; Takaki, Akihiro; Matsumoto, Masanori

2007-01-01

In this study, we examined whether the optimal energy window (EW) setting depending on an energy resolution of a gamma camera, which we previously proposed, is valid on planar scintigraphic imaging using Tl-201, Ga-67, Tc-99m, and I-123. Image acquisitions for line sources and paper sheet phantoms containing each radionuclide were performed in air and with scattering materials. For the six photopeaks excluding the Hg-201 characteristic x-rays' one, the conventional 20%-width energy window (EW20%) setting and the optimal energy window (optimal EW) setting (15%-width below 100 keV and 13%-width above 100 keV) were compared. For the Hg-201 characteristic x-rays' photopeak, the conventional on-peak EW20% setting was compared with the off-peak EW setting (73 keV-25%) and the wider off-peak EW setting (77 keV-29%). Image-count ratio (defined as the ratio of the image counts obtained with an EW and the total image counts obtained with the EW covered the whole photopeak for a line source in air), image quality, spatial resolutions (full width half maximum (FWHM) and full width tenth maximum (FWTM) values), count-profile curves, and defect-contrast values were compared between the conventional EW setting and the optimal EW setting. Except for the Hg-201 characteristic x-rays, the image-count ratios were 94-99% for the EW20% setting, but 78-89% for the optimal EW setting. However, the optimal EW setting reduced scatter fraction (defined as the scattered-to-primary counts ratio) effectively, as compared with the EW20% setting. Consequently, all the images with the optimal EW setting gave better image quality than ones with the EW20% setting. For the Hg-201 characteristic x-rays, the off-peak EW setting showed great improvement in image quality in comparison with the EW20% setting and the wider off-peak EW setting gave the best results. In conclusion, from our planar imaging study it was shown that although the optimal EW setting proposed by us gives less image-count ratio by

Kirkpatrick-Baez microscope with spherical multilayer mirrors around 2.5keV photon energy

Science.gov (United States)

An, Ning; Du, Xuewei; Wang, Qiuping; Cao, Zhurong; Jiang, Shaoen; Ding, Yongkun

2014-09-01

A Kirkpatrick-Baez (KB) x-ray microscope has been developed for the diagnostics of inertial confinement fusion (ICF). The KB microscope system works around 2.5keV with the magnification of 20. It consists of two spherical multilayer mirrors. The grazing angle is 3.575° at 2.5keV. The influence of the slope error of optical components and the alignment errors is simulated by SHADOW software. The mechanical structure which can perform fine tuning is designed. Experiment result with Manson x-ray source shows that the spatial resolution of the system is about 3-4μm over a field of view of 200μm.

Neutron Fluence and Energy Reconstruction with the LNE-IRSN/MIMAC Recoil Detector MicroTPC at 27 keV

Energy Technology Data Exchange (ETDEWEB)

Maire, D.; Lebreton, L.; Querre, Ph. [Institute for Radioprotection and Nuclear Safety - IRSN, site of Cadarache, 13115 Saint Paul lez Durance (France); Bosson, G.; Guillaudin, O.; Muraz, J.F.; Riffard, Q.; Santos, D. [Laboratoire de Physique Subatomique et de Cosmologie - LPSCCNRSIN2P3/ UJF/INP, 38000 Grenoble (France)

2015-07-01

The French Institute for Radiation protection and Nuclear Safety (IRSN), designated by the French Metrology Institute (LNE) for neutron metrology, is developing a time projection chamber using a Micromegas anode: microTPC. This work is carried out in collaboration with the Laboratory of Subatomic Physics and Cosmology (LPSC). The aim is to characterize the energy distribution of neutron fluence in the energy range 8 keV - 5 MeV with a primary procedure. The time projection chambers are gaseous detectors able to measure charged particles energy and to reconstruct their track if a pixelated anode is used. In our case, the gas is used as a (n, p) converter in order to detect neutrons down to few keV. Coming from elastic collisions with neutrons, recoil protons lose a part of their kinetic energy by ionizing the gas. The ionization electrons are drifted toward a pixelated anode (2D projection), read at 50 MHz by a self-triggered electronic system to obtain the third track dimension. The neutron energy is reconstructed event by event thanks to proton scattering angle and proton energy measurements. The scattering angle is deduced from the 3D track. The proton energy is obtained by charge collection measurements, knowing the ionization quenching factor (i.e. the part of proton kinetic energy lost by ionizing the gas). The fluence is calculated thanks to the detected events number and the simulation of the detector response. The μTPC is a new reliable detector able to measure energy distribution of the neutron fluence without unfolding procedure or prior neutron calibration contrary to usual gaseous counters. The microTPC is still being developed and measurements have been carried out at the AMANDE facility, with neutrons energies going from 8 keV to 565 keV. After the context and the μ-TPC working principle presentation, measurements of the neutron energy and fluence at 27 keV and 144 keV are shown and compared to the complete detector response simulation. This work

Single-electron capture for 2-8 keV incident energy and direct scattering at 6 keV in He2+-He collisions

International Nuclear Information System (INIS)

Bordenave-Montesquieu, D.; Dagnac, R.

1992-01-01

We studied the single-electron capture as well as the direct processes occurring when a He 2+ ion is scattered by a He target. Doubly differential cross sections were measured for single-electron capture with a collision energy ranging from 2 to 8 keV and a scattering angle varying from 10' to 3 o 30' (laboratory frame). Single-electron capture into excited states of He + was found to be the dominant process, confirming a previous experimental study. Elastic scattering and ionization differential cross sections were measured for E = 6 keV. (Author)

Imaging Lithium Atoms at Sub-Angstrom Resolution

Energy Technology Data Exchange (ETDEWEB)

O' Keefe, Michael A.; Shao-Horn, Yang

2005-01-03

John Cowley and his group at ASU were pioneers in the use of transmission electron microscopy (TEM) for high-resolution imaging. Three decades ago they achieved images showing the crystal unit cell content at better than 4A resolution. Over the years, this achievement has inspired improvements in resolution that have enabled researchers to pinpoint the positions of heavy atom columns within the cell. More recently, this ability has been extended to light atoms as resolution has improved. Sub-Angstrom resolution has enabled researchers to image the columns of light atoms (carbon, oxygen and nitrogen) that are present in many complex structures. By using sub-Angstrom focal-series reconstruction of the specimen exit surface wave to image columns of cobalt, oxygen, and lithium atoms in a transition metal oxide structure commonly used as positive electrodes in lithium rechargeable batteries, we show that the range of detectable light atoms extends to lithium. HRTEM at sub-Angstrom resolution will provide the essential role of experimental verification for the emergent nanotech revolution. Our results foreshadow those to be expected from next-generation TEMs with CS-corrected lenses and monochromated electron beams.

A New Observation of the Quiet Sun Soft X-ray (0.5-5 keV) Spectrum

Science.gov (United States)

Caspi, Amir; Woods, Thomas N.; Stone, Jordan

2013-03-01

The solar corona is the brightest source of X-rays in the solar system, and the X-ray emission is highly variable with solar activity. While this is particularly true during solar flares, when emission can be enhanced by many orders of magnitude up to gamma-ray energies, even the so-called "quiet Sun" is bright in soft X-rays (SXRs), as the 1-2 MK ambient plasma of the corona emits significant thermal bremsstrahlung up to 5 keV. However, the actual solar SXR (0.5-5 keV) spectrum is not well known, particularly during quiet periods, as, with few exceptions, this energy range has not been systematically studied in many years. Previous observations include ultra-high-resolution but very narrow-band spectra from crystral spectrometers (e.g. Yohkoh/BCS), or integrated broadband irradiances from photometers (e.g. GOES/XRS, TIMED/XPS, etc.) that lack detailed spectral information. In recent years, broadband measurements with fair energy resolution ( 0.5-0.7 keV FWHM) were made by SphinX on CORONAS-Photon and XRS on MESSENGER, although they did not extend below 1 keV. We present observations of the quiet Sun SXR emission obtained using a new SXR spectrometer flown on the third SDO/EVE underflight calibration rocket (NASA 36.286). The commercial off-the-shelf Amptek X123 silicon drift detector, with an 8-micron Be window and custom aperture, measured the solar SXR emission from 0.5 to >10 keV with 0.15 keV FWHM resolution (though, due to hardware limitations, with only 0.12 keV binning) and 2-sec cadence over 5 minutes on 23 June 2012. Despite the rising solar cycle, activity on 23 June 2012 was abnormally low, with no visible active regions and GOES XRS emission near 2010 levels; we measured no solar counts above 4 keV during the observation period. We compare our X123 measurements with spectra and broadband irradiances from other instruments, including the SphinX observations during the deep solar minimum of 2009, and with upper limits of >3 keV quiet Sun emission

An analytical X-ray CdTe detector response matrix for incomplete charge collection correction for photon energies up to 300 keV

Science.gov (United States)

Kurková, Dana; Judas, Libor

2018-05-01

Gamma and X-ray energy spectra measured with semiconductor detectors suffer from various distortions, one of them being so-called "tailing" caused by an incomplete charge collection. Using the Hecht equation, a response matrix of size 321 × 321 was constructed which was used to correct the effect of incomplete charge collection. The correction matrix was constructed analytically for an arbitrary energy bin and the size of the energy bin thus defines the width of the spectral window. The correction matrix can be applied separately from other possible spectral corrections or it can be incorporated into an already existing response matrix of the detector. The correction was tested and its adjustable parameters were optimized on the line spectra of 57Co measured with a cadmium telluride (CdTe) detector in a spectral range from 0 up to 160 keV. The best results were obtained when the values of the free path of holes were spread over a range from 0.4 to 1.0 cm and weighted by a Gauss function. The model with the optimized parameter values was then used to correct the line spectra of 152Eu in a spectral range from 0 up to 530 keV. An improvement in the energy resolution at full width at half maximum from 2.40 % ± 0.28 % to 0.96 % ± 0.28 % was achieved at 344.27 keV. Spectra of "narrow spectrum series" beams, N120, N150, N200, N250 and N300, generated with tube voltages of 120 kV, 150 kV, 200 kV, 250 kV and 300 kV respectively, and measured with the CdTe detector, were corrected in the spectral range from 0 to 160 keV (N120 and N150) and from 0 to 530 keV (N200, N250, N300). All the measured spectra correspond both qualitatively and quantitatively to the available reference data after the correction. To obtain better correspondence between N150, N200, N250 and N300 spectra and the reference data, lower values of the free paths of holes (range from 0.16 to 0.65 cm) were used for X-ray spectra correction, which suggests energy dependence of the phenomenon.

New Observations of Soft X-ray (0.5-5 keV) Solar Spectra

Science.gov (United States)

Caspi, A.; Woods, T. N.; Mason, J. P.; Jones, A. R.; Warren, H. P.

2013-12-01

The solar corona is the brightest source of X-rays in the solar system, and the X-ray emission is highly variable on many time scales. However, the actual solar soft X-ray (SXR) (0.5-5 keV) spectrum is not well known, particularly during solar quiet periods, as, with few exceptions, this energy range has not been systematically studied in many years. Previous observations include high-resolution but very narrow-band spectra from crystal spectrometers (e.g., Yohkoh/BCS), or integrated broadband irradiances from photometers (e.g., GOES/XRS, TIMED/XPS, etc.) that lack detailed spectral information. In recent years, broadband measurements with moderate energy resolution (~0.5-0.7 keV FWHM) were made by SphinX on CORONAS-Photon and SAX on MESSENGER, although they did not extend to energies below ~1 keV. We present observations of solar SXR emission obtained using new instrumentation flown on recent SDO/EVE calibration rocket underflights. The photon-counting spectrometer, a commercial Amptek X123 with a silicon drift detector and an 8 μm Be window, measures the solar disk-integrated SXR emission from ~0.5 to >10 keV with ~0.15 keV FWHM resolution and 1 s cadence. A novel imager, a pinhole X-ray camera using a cooled frame-transfer CCD (15 μm pixel pitch), Ti/Al/C filter, and 5000 line/mm Au transmission grating, images the full Sun in multiple spectral orders from ~0.1 to ~5 nm with ~10 arcsec/pixel and ~0.01 nm/pixel spatial and spectral detector scales, respectively, and 10 s cadence. These instruments are prototypes for future CubeSat missions currently being developed. We present new results of solar observations on 04 October 2013 (NASA sounding rocket 36.290). We compare with previous results from 23 June 2012 (NASA sounding rocket 36.286), during which solar activity was low and no signal was observed above ~4 keV. We compare our spectral and imaging measurements with spectra and broadband irradiances from other instruments, including SDO/EVE, GOES/XRS, TIMED

A new X-ray pinhole camera for energy dispersive X-ray fluorescence imaging with high-energy and high-spatial resolution

Energy Technology Data Exchange (ETDEWEB)

Romano, F.P., E-mail: romanop@lns.infn.it [IBAM, CNR, Via Biblioteca 4, 95124 Catania (Italy); INFN-LNS, Via S. Sofia 62, 95123 Catania (Italy); Altana, C. [INFN-LNS, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, 95123 Catania (Italy); Cosentino, L.; Celona, L.; Gammino, S.; Mascali, D. [INFN-LNS, Via S. Sofia 62, 95123 Catania (Italy); Pappalardo, L. [IBAM, CNR, Via Biblioteca 4, 95124 Catania (Italy); INFN-LNS, Via S. Sofia 62, 95123 Catania (Italy); Rizzo, F. [INFN-LNS, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, 95123 Catania (Italy)

2013-08-01

A new X-ray pinhole camera for the Energy Dispersive X-ray Fluorescence (ED-XRF) imaging of materials with high-energy and high-spatial resolution, was designed and developed. It consists of a back-illuminated and deep depleted CCD detector (composed of 1024 × 1024 pixels with a lateral size of 13 μm) coupled to a 70 μm laser-drilled pinhole-collimator, positioned between the sample under analysis and the CCD. The X-ray pinhole camera works in a coaxial geometry allowing a wide range of magnification values. The characteristic X-ray fluorescence is induced on the samples by irradiation with an external X-ray tube working at a maximum power of 100 W (50 kV and 2 mA operating conditions). The spectroscopic capabilities of the X-ray pinhole camera were accurately investigated. Energy response and energy calibration of the CCD detector were determined by irradiating pure target-materials emitting characteristic X-rays in the energy working-domain of the system (between 3 keV and 30 keV). Measurements were performed by using a multi-frame acquisition in single-photon counting. The characteristic X-ray spectra were obtained by an automated processing of the acquired images. The energy resolution measured at the Fe–Kα line is 157 eV. The use of the X-ray pinhole camera for the 2D resolved elemental analysis was investigated by using reference-patterns of different materials and geometries. The possibility of the elemental mapping of samples up to an area of 3 × 3 cm{sup 2} was demonstrated. Finally, the spatial resolution of the pinhole camera was measured by analyzing the profile function of a sharp-edge. The spatial resolution determined at the magnification values of 3.2 × and 0.8 × (used as testing values) is about 90 μm and 190 μm respectively. - Highlights: • We developed an X-ray pinhole camera for the 2D X-ray fluorescence imaging. • X-ray spectra are obtained by a multi-frame acquisition in single photon mode. • The energy resolution in the X

Non-Proportionality of Electron Response and Energy Resolution of Compton Electrons in Scintillators

Science.gov (United States)

Swiderski, L.; Marcinkowski, R.; Szawlowski, M.; Moszynski, M.; Czarnacki, W.; Syntfeld-Kazuch, A.; Szczesniak, T.; Pausch, G.; Plettner, C.; Roemer, K.

2012-02-01

Non-proportionality of light yield and energy resolution of Compton electrons in three scintillators (LaBr3:Ce, LYSO:Ce and CsI:Tl) were studied in a wide energy range from 10 keV up to 1 MeV. The experimental setup was comprised of a High Purity Germanium detector and tested scintillators coupled to a photomultiplier. Probing the non-proportionality and energy resolution curves at different energies was obtained by changing the position of various radioactive sources with respect to both detectors. The distance between both detectors and source was kept small to make use of Wide Angle Compton Coincidence (WACC) technique, which allowed us to scan large range of scattering angles simultaneously and obtain relatively high coincidence rate of 100 cps using weak sources of about 10 μCi activity. The results are compared with those obtained by direct irradiation of the tested scintillators with gamma-ray sources and fitting the full-energy peaks.

Improvement of the energy resolution via an optimized digital signal processing in GERDA Phase I

Science.gov (United States)

Agostini, M.; Allardt, M.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Barros, N.; Baudis, L.; Bauer, C.; Becerici-Schmidt, N.; Bellotti, E.; Belogurov, S.; Belyaev, S. T.; Benato, G.; Bettini, A.; Bezrukov, L.; Bode, T.; Borowicz, D.; Brudanin, V.; Brugnera, R.; Budjáš, D.; Caldwell, A.; Cattadori, C.; Chernogorov, A.; D'Andrea, V.; Demidova, E. V.; Vacri, A. di; Domula, A.; Doroshkevich, E.; Egorov, V.; Falkenstein, R.; Fedorova, O.; Freund, K.; Frodyma, N.; Gangapshev, A.; Garfagnini, A.; Grabmayr, P.; Gurentsov, V.; Gusev, K.; Hegai, A.; Heisel, M.; Hemmer, S.; Heusser, G.; Hofmann, W.; Hult, M.; Inzhechik, L. V.; Janicskó Csáthy, J.; Jochum, J.; Junker, M.; Kazalov, V.; Kihm, T.; Kirpichnikov, I. V.; Kirsch, A.; Klimenko, A.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kuzminov, V. V.; Laubenstein, ********************M.; Lazzaro, A.; Lebedev, V. I.; Lehnert, B.; Liao, H. Y.; Lindner, M.; Lippi, I.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Macolino, C.; Majorovits, B.; Maneschg, W.; Medinaceli, E.; Misiaszek, M.; Moseev, P.; Nemchenok, I.; Palioselitis, D.; Panas, K.; Pandola, L.; Pelczar, K.; Pullia, A.; Riboldi, S.; Rumyantseva, N.; Sada, C.; Salathe, M.; Schmitt, C.; Schneider, B.; Schönert, S.; Schreiner, J.; Schütz, A.-K.; Schulz, O.; Schwingenheuer, B.; Selivanenko, O.; Shirchenko, M.; Simgen, H.; Smolnikov, A.; Stanco, L.; Stepaniuk, M.; Ur, C. A.; Vanhoefer, L.; Vasenko, A. A.; Veresnikova, A.; von Sturm, K.; Wagner, V.; Walter, M.; Wegmann, A.; Wester, T.; Wilsenach, H.; Wojcik, M.; Yanovich, E.; Zavarise, P.; Zhitnikov, I.; Zhukov, S. V.; Zinatulina, D.; Zuber, K.; Zuzel, G.

2015-06-01

An optimized digital shaping filter has been developed for the Gerda experiment which searches for neutrinoless double beta decay in Ge. The Gerda Phase I energy calibration data have been reprocessed and an average improvement of 0.3 keV in energy resolution (FWHM) corresponding to 10 % at the value for decay in Ge is obtained. This is possible thanks to the enhanced low-frequency noise rejection of this Zero Area Cusp (ZAC) signal shaping filter.

Electron energy-loss spectrometry at the frontier of spatial and energy resolution

International Nuclear Information System (INIS)

Hofer, F.; Grogger, W.; Kothleitner, G.

2004-01-01

Full text: Electron energy-loss spectroscopy (EELS) in the transmission electron microscope (TEM) is now used routinely as a means of measuring chemical and structural properties of very small regions of a thin specimen. The power of this technique depends significantly on two parameters: its spatial resolution and the energy resolution available in the spectrum and in the energy-filtered TEM (EFTEM) image. The cold field emission source and the Schottky emitter have made an energy resolution below 1 eV possible and it is now feasible to obtain data with a spatial resolution close to atomic dimensions, given the right instrumentation and specimen. EFTEM allows to record elemental maps at sub-nanometre resolution, being mainly limited by chromatic and spherical aberration of the objective lens and by delocalization of inelastic scattering. Recently the possibility of correcting spherical and even chromatic aberrations of electron lenses has become a practical reality thus improving the point resolution of the TEM to below 0.1 nm. The other limiting factor for EFTEM resolution is delocalization. However, recent measurements show that resolution values in the range of 1 nm and below can be achieved, even for energy-losses of only a few eV. In terms of energy-resolution, EELS and EFTEM compare less favourably with other spectroscopies. For common TEMs, the overall energy-resolution is mainly determined by the energy width of the electron source, typically between 0.5 and 1.5 eV. For comparison, synchrotron x-ray sources and beam line spectrometers, provide a resolution well below 0.1 eV for absorption spectroscopy. During the early sixties, the energy spread of an electron beam could be reduced by incorporating an energy-filter into the illumination system, but the system lacked spatial resolution. Later developments combined high energy resolution in the range of 0.1 eV with improved spatial resolution. Recently, FEI introduced a new high resolution EELS system based

Low-energy x-ray dosimetry studies (6 to 16 keV) at SSRL beamline 1-5

International Nuclear Information System (INIS)

Ipe, N.E.; Chatterji, S.; Fassograve, A.; Kase, K.R.; Seefred, R.; Bilski, P.; Soares, C.

1997-01-01

Synchrotron radiation facilities provide a unique opportunity for low-energy x-ray dosimetry studies because of the availability of monochromatic x-ray beams. Results of such studies performed at the Stanford Synchrotron Radiation Laboratory (SSRL) are described. Polish lithium fluoride thermoluminescent dosemeters (TLDs), MTS-N(LiF:Mg, Ti- 0.4 mm thick), MCP-N (LiF:Mg, Cu, P - 0.4 mm thick) were exposed free in air to monochromatic x-rays (6 - 16 keV). These exposures were monitored with an SSRL ionization chamber. The responses (counts/Gy) of MTS-N and MCP-N were generally found to increase with increasing energy. The response at 16 keV is about 3 and 4 times higher than the response at 6 keV for MTS-N and MCP-N, respectively. Irradiation at 6 keV indicates a fairly linear dose response for both type of TLDs over a dose range of 0.01 to 0.4 Gy. In addition there appears to be no significant difference in responses between irradiating the TLDs from the front and the back sides. The energy response of the PTW ionization chamber type 23342 relative to the SSRL ionization chamber is within ±4.5% between 6 and 16 keV. Both the TLDs and the PTW ionization chamber can also be used for beam dosimetry. copyright 1997 American Institute of Physics

TiN{sub x}O{sub y}/TiN dielectric contrasts obtained by ion implantation of O{sub 2}{sup +}; structural, optical and electrical properties

Energy Technology Data Exchange (ETDEWEB)

Punzon Quijorna, E; Torres Costa, V; Climent, A; Manso Silvan, M [Departamento de Fisica Aplicada. Universidad Autonoma de Madrid, 28049 Madrid (Spain); Agullo-Rueda, F; Herrero Fernandez, P [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid (Spain); Rossi, F [Institute for Health and Consumer Protection, Joint Research Center, 21020 Ispra (Vatican City State, Holy See) (Italy)

2011-06-15

The properties of TiN can be gradually transformed by O{sub 2}{sup +} implantations in the 10-40 keV range and fluences in the 5 x 10{sup 13}-5 x 10{sup 16} cm{sup -2} range. The resulting structure consists of shallow TiN{sub x}O{sub y}(TiNO)/TiN contrasts with increased resistivity on the top layer. In fact, oxygen actively replaces nitrogen in the implanted TiN region as illustrated by Rutherford backscattering spectrometry. N substitutions and vacancies in the lattice induce structural distortions and strain generation as illustrated by x-ray diffraction, high resolution transmission electron microscopy and Raman spectroscopy. The influence of these modifications in the optical and electrical properties was characterized by spectroscopic ellipsometry and four probe resistivity measurements. The proposed process, especially at the lower energy, is liable to help in the creation of electrical/photonic structures based in shallow TiNO/TiN electric/dielectric contrasts.

Attenuation coefficients of soils and some building materials of Bangladesh in the energy range 276-1332 keV

International Nuclear Information System (INIS)

Alam, M.N.; Miah, M.M.H.; Chowdhury, M.I.; Kamal, M.; Ghose, S.; Rahman, Runi

2001-01-01

The linear and mass attenuation coefficients of different types of soil, sand, building materials and heavy beach mineral samples from the Chittagong and Cox's Bazar area of Bangladesh were measured using a high-resolution HPGe detector and the γ-ray energies 276.1, 302.8, 356.0, 383.8, 661.6 and 1173.2 and 1332.5 keV emitted from point sources of 133 Ba, 137 Cs and 60 Co, respectively. The linear attenuation coefficients show a linear relationship with the corresponding densities of the samples studied. The variations of the mass attenuation coefficient with γ-ray energy were exponential in nature. The measured mass attenuation coefficient values were compared with measurements made in other countries for similar kinds of materials. The values are in good agreement with each other in most cases

A Cs{sub 2}LiYCl{sub 6}:Ce-based advanced radiation monitoring device

Energy Technology Data Exchange (ETDEWEB)

Budden, B.S. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Stonehill, L.C., E-mail: lauracs@lanl.gov [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Dallmann, N. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Baginski, M.J.; Best, D.J. [SCI Technology, Inc., Huntsville, AL 35803 (United States); Smith, M.B.; Graham, S.A. [Bubble Technology Industries, Chalk River, ON, Canada K0J1J0 (Canada); Dathy, C.; Frank, J.M. [Saint-Gobain Crystals, Hiram, OH 44234 (United States); McClish, M. [Radiation Monitoring Devices, Inc., Watertown, MA 02472 (United States)

2015-06-01

Cs{sub 2}LiYCl{sub 6}:Ce{sup 3+} (CLYC) scintillator has gained recent interest because of its ability to perform simultaneous gamma spectroscopy and thermal neutron detection. Discrimination between the two incident particle types owes to the fundamentally unique emission waveforms, a consequence of the interaction and subsequent scintillation mechanisms within the crystal. Due to this dual-mode detector capability, CLYC was selected for the development of an Advanced Radiation Monitoring Device (ARMD), a compact handheld instrument for radioisotope identification and localization. ARMD consists of four 1 in.-right cylindrical CLYC crystals, custom readout electronics including a suitable multi-window application specific integrated circuit (ASIC), battery pack, proprietary software, and Android-based tablet for high-level analysis and display. We herein describe the motivation of the work and engineering design of the unit, and we explain the software embedded in the core module and for radioisotope analysis. We report an operational range of tens of keV to 8.5 MeV with approximately 5.3% gamma energy resolution at 662 keV, thermal neutron detection efficiency of 10%, battery lifetime of up to 10 h, manageable rates of 20 kHz; further, we describe in greater detail time to identify specific gamma source setups.

Angular distribution of thick-target bremsstrahlung produced by electrons with initial energies ranging from 10 to 20 keV incident on Ag

Energy Technology Data Exchange (ETDEWEB)

Gonzales, D.; Cavness, B.; Williams, S. [Department of Physics, Angelo State University, San Angelo, Texas 76909 (United States)

2011-11-15

Experimental results are presented comparing the intensities of the bremsstrahlung produced by electrons with initial energies ranging from 10 to 20 keV incident on a thick Ag target, measured at forward angles in the range of 0 degree sign to 55 degree sign . When the data are corrected for attenuation due to photon absorption within the target, the results indicate that the detected radiation is distributed anisotropically only at photon energies k that are approximately equal to the initial energy of the incident electrons E{sub 0}. The results of our experiments suggest that, as k/E{sub 0}{yields} 0, the detected radiation essentially becomes isotropic due primarily to the scattering of electrons within the target. A comparison to the theory of Kissel et al.[At. Data Nucl. Data Tables 28, 381 (1983)] suggests that the angular distribution of bremsstrahlung emitted by electrons incident on thick targets is similar to the angular distribution of bremsstrahlung emitted by electrons incident on free-atom targets only when k/E{sub 0}{approx_equal} 1. The experimental data also are in approximate agreement with the angular distribution predictions of the Monte Carlo program penelope.

Improvement of the energy resolution via an optimized digital signal processing in GERDA Phase I

International Nuclear Information System (INIS)

Agostini, M.; Allardt, M.; Bakalyarov, A. M.; Balata, M.

2015-01-01

An optimized digital shaping filter has been developed for the Gerda experiment which searches for neutrinoless double beta decay in 76 Ge. The Gerda Phase I energy calibration data have been reprocessed and an average improvement of 0.3 keV in energy resolution (FWHM) corresponding to 10 % at the Q value for 0νββ decay in 76 Ge is obtained. This is possible thanks to the enhanced low-frequency noise rejection of this Zero Area Cusp (ZAC) signal shaping filter

Feasibility study of the anti pp → D{sub s}{sup -}D{sub s0}{sup *}(2317) process with PANDA

Energy Technology Data Exchange (ETDEWEB)

Prencipe, Elisabetta; Gillitzer, Albrecht; Ritman, James [Forschungszentrum Juelich IKP1, Juelich (Germany); Goetzen, Klaus [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany)

2016-07-01

Charm spectroscopy has recently gained renewed attention, due to confirmations and new observations published by LHCb. Despite of the excellent performance of the CERN experiments, still limitations exist, that do not allow to perform the measurement of the width (Γ) of narrow states with Γ ≤ 1 MeV. The measurement of the D{sub s0}{sup *}(2317) and the D{sub s1}(2460) width is a crucial point to discriminate among theoretical models, and to reveal their nature. One of the major advantage of the future PANDA experiment at FAIR is the excellent momentum beam resolution of about Δp/p=5 x 10{sup -5}, allowing energy scans with an energy resolution down to ΔE ∼ 26 keV. We present a method to measure the width of the D{sub s0}{sup *}(2317), and for the first time a complete full simulation performed with PandaRoot is shown. Feasibility studies for assumption of different signal cross sections are shown, to accommodate the incomplete experimental and theoretical knowledge of the corresponding process of interest. A proposal for a threshold scan for the production reaction anti pp → D{sub s}{sup -}D{sub s0}{sup *}(2317){sup +} in 100-keV-steps is presented, together with an estimate of the competitiveness of PANDA in this field, assuming an average luminosity of L=10{sup 31} cm{sup -1}s{sup -1}.

Asymmetric fission and evaporation of C{sup r+}{sub 60} (r = 2-4) fullerene ions in ion-C{sub 60} collisions: III. Universal behaviour of fission

Energy Technology Data Exchange (ETDEWEB)

Bordenave-Montesquieu, D; Bordenave-Montesquieu, A; Rentenier, A; Moretto-Capelle, P [LCAR-IRSAMC, UMR 5589 Universite Paul Sabatier-CNRS, 118 rte de Narbonne, 31062 Toulouse Cedex (France)

2005-04-14

The behaviour of the asymmetrical fission (AF) scheme (correlated ion distributions) against the collision conditions is investigated using H{sup +}{sub x} (x = 1-3) and He{sup +} projectiles in the 1-130 keV collision energy range. The present work is an extension of our recent publications on this topic using 11 keV protons (Rentenier et al 2004 J. Phys. B: At. Mol. Opt. Phys. 37 2429 and 2455). The threshold for AF is observed at 2 keV proton energy corresponding to a maximum deposited energy equal to about 41 eV. The main result concerns the fragment distributions resulting from AF of C{sup r+}{sub 60} ions, and secondary dissociation of even-n C{sup +}{sub n} fragments, which are both found to remain independent of the projectile species and collision velocity. These findings indicate that they are insensitive to the internal energy distributions of the parent ions. In addition, a contribution of binary collisions between the projectile and individual carbon atoms of the C{sub 60} molecule to AF is identified in the C{sup +}{sub 1} production at the lowest collision velocities, the so-called impulsive fragmentation.

High-spatial resolution and high-spectral resolution detector for use in the measurement of solar flare hard x rays

International Nuclear Information System (INIS)

Desai, U.D.; Orwig, L.E.

1988-01-01

In the areas of high spatial resolution, the evaluation of a hard X-ray detector with 65 micron spatial resolution for operation in the energy range from 30 to 400 keV is proposed. The basic detector is a thick large-area scintillator faceplate, composed of a matrix of high-density scintillating glass fibers, attached to a proximity type image intensifier tube with a resistive-anode digital readout system. Such a detector, combined with a coded-aperture mask, would be ideal for use as a modest-sized hard X-ray imaging instrument up to X-ray energies as high as several hundred keV. As an integral part of this study it was also proposed that several techniques be critically evaluated for X-ray image coding which could be used with this detector. In the area of high spectral resolution, it is proposed to evaluate two different types of detectors for use as X-ray spectrometers for solar flares: planar silicon detectors and high-purity germanium detectors (HPGe). Instruments utilizing these high-spatial-resolution detectors for hard X-ray imaging measurements from 30 to 400 keV and high-spectral-resolution detectors for measurements over a similar energy range would be ideally suited for making crucial solar flare observations during the upcoming maximum in the solar cycle

FIRST INTEGRAL OBSERVATIONS OF V404 CYGNI DURING THE 2015 OUTBURST: SPECTRAL BEHAVIOR IN THE 20–650 KeV ENERGY RANGE

Energy Technology Data Exchange (ETDEWEB)

Roques, Jean-Pierre; Jourdain, Elisabeth [Université Toulouse, UPS-OMP, CNRS, IRAP, 9 Av. Roche, BP 44346, F-31028 Toulouse (France); Bazzano, Angela; Fiocchi, Mariateresa; Natalucci, Lorenzo; Ubertini, Pietro [Istituto di Astrofisica e Planetologia Spaziali, INAF, Via Fosso del Cavaliere 100, I-00133 Roma, Italy (Italy)

2015-11-01

In 2015 June, the source V404 Cygni (= GS2023+38) underwent an extraordinary outburst. We present the results obtained during the first revolution dedicated to this target by the INTEGRAL mission and focus on the spectral behavior in the hard X-ray domain, using both SPI and IBIS instruments. The source exhibits extreme variability and reaches fluxes of several tens of Crab. However, the emission between 20 and 650 keV can be understood in terms of two main components, varying on all the observable timescales, similar to what is observed in the persistent black hole system Cyg X-1. The low-energy component (up to ∼200 keV) presents a rather unusual shape, probably due to the intrinsic source variability. Nonetheless, a satisfactory description is obtained with a Comptonization model, if an unusually hot population of seed photons (kT{sub 0} ∼ 7 keV) is introduced. Above this first component, a clear excess extending up to 400–600 keV leads us to investigate a scenario where an additional (cutoff) power law could correspond to the contribution of the jet synchrotron emission, as proposed in Cyg X-1. A search for an annihilation feature did not provide any firm detection, with an upper limit of 2 × 10{sup −4} ph cm{sup −2} s{sup −1} (2σ) for a narrow line centered at 511 keV, on the averaged obtained spectrum.

Scanning SQUID susceptometers with sub-micron spatial resolution

International Nuclear Information System (INIS)

Kirtley, John R.; Rosenberg, Aaron J.; Palmstrom, Johanna C.; Holland, Connor M.; Moler, Kathryn A.; Paulius, Lisa; Spanton, Eric M.; Schiessl, Daniel; Jermain, Colin L.; Gibbons, Jonathan; Fung, Y.-K.K.; Gibson, Gerald W.; Huber, Martin E.; Ralph, Daniel C.; Ketchen, Mark B.

2016-01-01

Superconducting QUantum Interference Device (SQUID) microscopy has excellent magnetic field sensitivity, but suffers from modest spatial resolution when compared with other scanning probes. This spatial resolution is determined by both the size of the field sensitive area and the spacing between this area and the sample surface. In this paper we describe scanning SQUID susceptometers that achieve sub-micron spatial resolution while retaining a white noise floor flux sensitivity of ≈2μΦ_0/Hz"1"/"2. This high spatial resolution is accomplished by deep sub-micron feature sizes, well shielded pickup loops fabricated using a planarized process, and a deep etch step that minimizes the spacing between the sample surface and the SQUID pickup loop. We describe the design, modeling, fabrication, and testing of these sensors. Although sub-micron spatial resolution has been achieved previously in scanning SQUID sensors, our sensors not only achieve high spatial resolution but also have integrated modulation coils for flux feedback, integrated field coils for susceptibility measurements, and batch processing. They are therefore a generally applicable tool for imaging sample magnetization, currents, and susceptibilities with higher spatial resolution than previous susceptometers.

Experimental energy resolution of a paracentric hemispherical deflector analyzer for different entry positions and bias

Energy Technology Data Exchange (ETDEWEB)

Dogan, M.; Ulu, M. [eCOL Laboratory, Department of Physics, Science and Arts Faculty, Afyon Kocatepe University, 03200 Afyonkarahisar (Turkey); Gennarakis, G. G.; Zouros, T. J. M. [Atomic Collisions and Electron Spectroscopy Laboratory, Department of Physics, University of Crete, P.O. Box 2208, 71003 Heraklion, Crete (Greece)

2013-04-15

A specially designed hemispherical deflector analyzer (HDA) with 5-element input lens having a movable entry position R{sub 0} suitable for electron energy analysis in atomic collisions was constructed and tested. The energy resolution of the HDA was experimentally determined for three different entry positions R{sub 0}= 84, 100, 112 mm as a function of the nominal entry potential V(R{sub 0}) under pre-retardation conditions. The resolution for the (conventional) entry at the mean radius R{sub 0}= 100 mm was found to be a factor of 1.6-2 times worse than the resolution for the two (paracentric) positions R{sub 0}= 84 and 112 mm at particular values of V(R{sub 0}). These results provide the first experimental verification and a proof of principle of the utility of such a paracentric HDA, while demonstrating its advantages over the conventional HDA: greater dispersion with reduced angular aberrations resulting in better energy resolution without the use of any additional fringing field correction electrodes. Supporting simulations of the entire lens plus HDA spectrometer are also provided and mostly found to be within 20%-30% of experimental values. The paracentric HDA is expected to provide a lower cost and/or more compact alternative to the conventional HDA particularly useful in modern applications utilizing a position sensitive detector.

Proton-induced nanorod melting in a coating obtained from the pulsed laser ablation of W{sub 2}B{sub 5}/B{sub 4}C

Energy Technology Data Exchange (ETDEWEB)

Tadadjeu Sokeng, I., E-mail: ifriky@tlabs.ac.za [Department of Electrical, Electronics and Computer Engineering, French South African Institute of Technology/Cape Peninsula University of Technology, Bellville Campus, PO Box 1906, Bellville 7530 (South Africa); Electron Microscopy Unit, University of the Western Cape, Private bag x17, Bellville 7535 (South Africa); Ngom, B.D. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Laboratoire de Photonique et de Nanofrabrication, Groupes de physique du Solide et Sciences des Matriaux (GPSSM), Facult des sciences et Techniques, Universit Cheikh Anta Diop de Dakar (UCAD), B.P. 25114 Dakar-Fann, Dakar (Senegal); Cummings, F. [Electron Microscopy Unit, University of the Western Cape, Private bag x17, Bellville 7535 (South Africa); Kotsedi, L. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Msimanga, M. [iThemba LABS Gauten, Private Bag 11, WITS 2050, Johannesburg (South Africa); Maaza, M. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); and others

2015-02-01

Highlights: • Coatings from ablated B{sub 4}C/W{sub 2}B{sub 5} were irradiated with 900 keV protons. • Nanorod clusters were observed to melt and disperse. • Uniformly shaped nanorods were observed to grow. • Lateral diffusion of energy and lateral dispersion of matter were observed. - Abstract: Coatings obtained from pulsed laser ablated W{sub 2}B{sub 5}/B{sub 4}C were irradiated with 900keV protons at fluences ranging from about 1×10{sup 15}protons/cm{sup 2} to about 4×10{sup 15}protons/cm{sup 2}. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) were used to study the resulting structural effects. Clusters of nanorods were observed to disperse and reduce in number with increase in proton fluence. The atomic percentage of constituent elements were observed to vary with proton fluence, both within the nanorods and the film floor. Our results show that the structural effect of proton irradiation on the coating is lateral dispersion of matter.

Use of a YAP:Ce matrix coupled to a position-sensitive photomultiplier for high resolution positron emission tomography

International Nuclear Information System (INIS)

Del Guerra, A.; Zavattini, G.; Notaristefani, F. de; Giganti, M.; Piffanelli, A.; Pani, R.; Turra, A.

1996-01-01

A new scintillation detector system has been designed for application in high resolution Positron Emission Tomography (PET). The detector is a bundle of small YAlO 3 :Ce (YAP) crystals closely packed (0.2 x 0.2 x 3.0 cm 3 ), coupled to a position sensitive photomultiplier tube (PSPMT). The preliminary results obtained for spatial resolution, time resolution, energy resolution and efficiency of two such detectors working in coincidence are presented. These are 1.2 mm for the FWHM spatial resolution, 2.0 ns for the FWHM time resolution and 20% for the FWHM energy resolution at 511 keV. The measured efficiency is (44 ± 3)% with a 150 keV threshold and (20 ± 2)% with a 300 keV threshold

Determining metal ion distributions using resonant scattering at very high-energy K-edges: Bi/Pb in Pb{sub 5}Bi{sub 6}Se{sub 14}

Energy Technology Data Exchange (ETDEWEB)

Yuegang, Zhang; Lee, P L; Shastri, S D; Deming, Shu [Argonne National Lab., IL (United States). XOR, Advanced Photon Source; Wilkinson, A P [Georgia Inst. of Tech., Atlanta (United States). School of Chemistry and Biochemistry; Duck-Young, Chung; Kanatzidis, M G [Michigan State Univ., East Lansing (United States). Dept. of Chemistry

2005-06-01

Powder diffraction data collected at {proportional_to} 86 keV, and just below both the Pb and the Bi K-edges, on an imaging plate detector using synchrotron radiation from the Advanced Photon Source have been used to examine the Pb/Bi distribution over the 11 crystallographically distinct sites in Pb{sub 5}Bi{sub 6}Se{sub 14} [space group P2{sub 1}/m, a=16.0096(2) Aa, b=4.20148(4) Aa, c=21.5689(3) Aa and {beta}=97.537(1){sup 0}]. The scattering factors needed for the analyses were determined both by Kramers- Kronig transformation of absorption spectra and by analyses of diffraction patterns from reference compounds. Even with the relatively low scattering contrast that is available at the K-edges, it was possible to determine the Pb/Bi distribution and probe the presence of cation site vacancies in the material. The current results indicate that resonant scattering measurements at high-energy K-edges are a viable, and perhaps preferable, route to site occupancies when absorption from the sample or sample environment/container is a major barrier to the acquisition of high-quality resonant scattering data at lower-energy edges.

Synthesis of sponge-like hydrophobic NiBi{sub 3} surface by 200 keV Ar ion implantation

Energy Technology Data Exchange (ETDEWEB)

Siva, Vantari; Datta, D.P. [School of Physical Sciences, National Institute of Science Education and Research, HBNI, Jatni 752050 (India); Chatterjee, S. [Colloids and Materials Chemistry Department, CSIR-Institute of Minerals and Materials Technology, Acharya Vihar, Bhubaneswar 751 013 (India); Varma, S. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Kanjilal, D. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Sahoo, Pratap K., E-mail: pratap.sahoo@niser.ac.in [School of Physical Sciences, National Institute of Science Education and Research, HBNI, Jatni 752050 (India)

2017-07-15

Highlights: • A sponge-like hydrophobic NiBi{sub 3} surface has been synthesized using 200 keV Ar ion implantation. • A competition between amorphization and re-crystallization was observed in the existing phases owing to comparable magnitudes of nuclear and electronic energy depositions. • The relation between hydrophobic nature and sponge-like NiBi{sub 3} phase seems interesting, which is attributed to ion beam induced sputtering and mixing of the layers. - Abstract: Sponge-like nanostructures develop under Ar-ion implantation of a Ni–Bi bilayer with increasing ion fluence at room temperature. The surface morphology features different stages of evolution as a function of ion fluence, finally resulting in a planar surface at the highest fluence. Our investigations on the chemical composition reveal a spontaneous formation of NiBi{sub 3} phase on the surface of the as deposited bilayer film. Interestingly, we observe a competition between crystallization and amorphization of the existing poly-crystalline phases as a function of the implanted fluence. Measurements of contact angle by sessile drop method clearly show the ion-fluence dependent hydrophobic nature of the nano-structured surfaces. The wettability has been correlated with the variation in roughness and composition of the implanted surface. In fact, our experimental results confirm dominant effect of ion-sputtering as well as ion-induced mixing at the bilayer interface in the evolution of the sponge-like surface.

Single-electron capture for 2-8 keV incident energy and direct scattering at 6 keV in He[sup 2+]-He collisions

Energy Technology Data Exchange (ETDEWEB)

Bordenave-Montesquieu, D.; Dagnac, R. (Toulouse-3 Univ., 31 (France). Centre de Physique Atomique)

1992-06-14

We studied the single-electron capture as well as the direct processes occurring when a He[sup 2+] ion is scattered by a He target. Doubly differential cross sections were measured for single-electron capture with a collision energy ranging from 2 to 8 keV and a scattering angle varying from 10' to 3[sup o]30' (laboratory frame). Single-electron capture into excited states of He[sup +] was found to be the dominant process, confirming a previous experimental study. Elastic scattering and ionization differential cross sections were measured for E = 6 keV. (Author).

Evaluation of cross sections for neutron interactions with {sup 238}U in the energy region between 5 keV and 150 keV

Energy Technology Data Exchange (ETDEWEB)

Sirakov, I. [Institute for Nuclear Research and Nuclear Energy, Sofia (Bulgaria); Capote, R.; Trkov, A. [International Atomic Energy Agency, NAPC-Nuclear Data Section, Vienna (Austria); Gritzay, O. [Institute for Nuclear Research, Kyiv (Ukraine); Kim, H.I. [Korea Atomic Energy Research Institute, Nuclear Data Center, Daejeon (Korea, Republic of); Kopecky, S.; Paradela, C.; Schillebeeckx, P. [European Commission, Joint Research Centre, Geel (Belgium); Kos, B. [Jozef Stefan Institute, Ljubljana (Slovenia); Pronyaev, V.G. [Rosatom State Corporation, Atomsrandart, Moscow (Russian Federation)

2017-10-15

Cross sections for neutron interactions with {sup 238}U in the energy region from 5 keV to 150 keV have been evaluated. Average total and capture cross sections have been derived from a least squares analysis using experimental data reported in the literature. The resulting cross sections have been parameterised in terms of average resonance parameters maintaining full consistency with results of optical model calculations by using a dispersive coupled channel optical model potential. The average compound partial cross sections have been expressed in terms of transmission coefficients by applying the Hauser-Feshbach statistical reaction theory including width-fluctuations. A generalized single-level representation compatible with the energy-dependent options of the ENDF-6 format has been applied using standard boundary conditions. The results have been transferred into a full ENDF-6 compatible data file. (orig.)

Sputtering of copper atoms by keV atomic and molecular ions A comparison of experiment with analytical and computer based models

CERN Document Server

Gillen, D R; Goelich,

2002-01-01

Non-resonant multiphoton ionisation combined with quadrupole and time-of-flight analysis has been used to measure energy distributions of sputtered copper atoms. The sputtering of a polycrystalline copper target by 3.6 keV Ar sup + , N sup + and CF sub 2 sup + and 1.8 keV N sup + and CF sub 2 sup + ion bombardment at 45 deg. has been investigated. The linear collision model in the isotropic limit fails to describe the high energy tail of the energy distributions. However the TRIM.SP computer simulation has been shown to provide a good description. The results indicate that an accurate description of sputtering by low energy, molecular ions requires the use of computer simulation rather than analytical approaches. This is particularly important when considering plasma-surface interactions in plasma etching and deposition systems.

Improvement of the energy resolution via an optimized digital signal processing in GERDA Phase I

Energy Technology Data Exchange (ETDEWEB)

Agostini, M. [Physik Department and Excellence Cluster Universe, Technische Universität München, Munich (Germany); Allardt, M. [Institut für Kern- und Teilchenphysik, Technische Universität Dresden, Dresden (Germany); Bakalyarov, A. M. [National Research Center “Kurchatov Institute”, Moscow (Russian Federation); Balata, M. [INFN Laboratori Nazionali del Gran Sasso, LNGS, and Gran Sasso Science Institute, GSSI, Assergi (Italy); Collaboration: GERDA Collaboration; and others

2015-06-09

An optimized digital shaping filter has been developed for the Gerda experiment which searches for neutrinoless double beta decay in {sup 76}Ge. The Gerda Phase I energy calibration data have been reprocessed and an average improvement of 0.3 keV in energy resolution (FWHM) corresponding to 10 % at the Q value for 0νββ decay in {sup 76}Ge is obtained. This is possible thanks to the enhanced low-frequency noise rejection of this Zero Area Cusp (ZAC) signal shaping filter.

Improvement of the energy resolution via an optimized digital signal processing in GERDA Phase I

Energy Technology Data Exchange (ETDEWEB)

Agostini, M.; Bode, T.; Budjas, D.; Janicsko Csathy, J.; Lazzaro, A.; Schoenert, S. [Technische Universitaet Muenchen, Physik Department and Excellence Cluster Universe, Munich (Germany); Allardt, M.; Domula, A.; Lehnert, B.; Schneider, B.; Wester, T.; Wilsenach, H.; Zuber, K. [Technische Universitaet Dresden, Institut fuer Kern- und Teilchenphysik, Dresden (Germany); Bakalyarov, A.M.; Belyaev, S.T.; Lebedev, V.I.; Zhukov, S.V. [National Research Center ' ' Kurchatov Institute' ' , Moscow (Russian Federation); Balata, M.; D' Andrea, V.; Di Vacri, A.; Junker, M.; Laubenstein, M.; Macolino, C.; Zavarise, P. [LNGS, Assergi (Italy); Barabanov, I.; Bezrukov, L.; Doroshkevich, E.; Fedorova, O.; Gurentsov, V.; Kazalov, V.; Kuzminov, V.V.; Lubsandorzhiev, B.; Moseev, P.; Selivanenko, O.; Veresnikova, A.; Yanovich, E. [Institute for Nuclear Research of the Russian Academy of Sciences, Moscow (Russian Federation); Barros, N. [Technische Universitaet Dresden, Institut fuer Kern- und Teilchenphysik, Dresden (Germany); University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, PA (United States); Baudis, L.; Benato, G.; Walter, M. [Physik Institut der Universitaet Zuerich, Zurich (Switzerland); Bauer, C.; Heisel, M.; Heusser, G.; Hofmann, W.; Kihm, T.; Kirsch, A.; Knoepfle, K.T.; Lindner, M.; Maneschg, W.; Salathe, M.; Schreiner, J.; Schwingenheuer, B.; Simgen, H.; Smolnikov, A.; Stepaniuk, M.; Wagner, V.; Wegmann, A. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Becerici-Schmidt, N.; Caldwell, A.; Liao, H.Y.; Majorovits, B.; Palioselitis, D.; Schulz, O.; Vanhoefer, L. [Max-Planck-Institut fuer Physik, Munich (Germany); Bellotti, E. [Universita Milano Bicocca, Dipartimento di Fisica, Milan (Italy); INFN Milano Bicocca, Milan (Italy); Belogurov, S.; Kornoukhov, V.N. [Institute for Nuclear Research of the Russian Academy of Sciences, Moscow (Russian Federation); Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Bettini, A.; Brugnera, R.; Garfagnini, A.; Hemmer, S.; Medinaceli, E.; Sada, C.; Sturm, K. von [Universita di Padova, Dipartimento di Fisica e Astronomia, Padua (Italy); INFN Padova, Padua (Italy); Borowicz, D. [Jagiellonian University, Institute of Physics, Krakow (Poland); Joint Institute for Nuclear Research, Dubna (Russian Federation); Brudanin, V.; Egorov, V.; Kochetov, O.; Nemchenok, I.; Rumyantseva, N.; Zhitnikov, I.; Zinatulina, D. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Cattadori, C. [INFN Milano Bicocca, Milan (Italy); Chernogorov, A.; Demidova, E.V.; Kirpichnikov, I.V.; Vasenko, A.A. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Falkenstein, R.; Freund, K.; Grabmayr, P.; Hegai, A.; Jochum, J.; Schmitt, C.; Schuetz, A.K. [Eberhard Karls Universitaet Tuebingen, Physikalisches Institut, Tuebingen (Germany); Frodyma, N.; Misiaszek, M.; Panas, K.; Pelczar, K.; Wojcik, M.; Zuzel, G. [Jagiellonian University, Institute of Physics, Krakow (Poland); Gangapshev, A. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Institute for Nuclear Research of the Russian Academy of Sciences, Moscow (Russian Federation); Gusev, K. [Joint Institute for Nuclear Research, Dubna (Russian Federation); National Research Center ' ' Kurchatov Institute' ' , Moscow (Russian Federation); Technische Universitaet Muenchen, Physik Department and Excellence Cluster Universe, Munich (Germany); Hult, M.; Lutter, G. [Institute for Reference Materials and Measurements, Geel (Belgium); Inzhechik, L.V. [Institute for Nuclear Research of the Russian Academy of Sciences, Moscow (Russian Federation); Moscow Institute of Physics and Technology, Moscow (Russian Federation); Klimenko, A. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); International University for Nature, Society and Man ' ' Dubna' ' , Dubna (Russian Federation); Lippi, I.; Stanco, L.; Ur, C.A. [INFN Padova, Padua (Italy); Lubashevskiy, A. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Pandola, L. [INFN Laboratori Nazionali del Sud, Catania (Italy); Pullia, A.; Riboldi, S. [Universita degli Studi di Milano, Dipartimento di Fisica, Milan (Italy); INFN, Milano (Italy); Shirchenko, M. [Joint Institute for Nuclear Research, Dubna (Russian Federation); National Research Center ' ' Kurchatov Institute' ' , Moscow (Russian Federation); Collaboration: GERDA Collaboration

2015-06-15

An optimized digital shaping filter has been developed for the Gerda experiment which searches for neutrinoless double beta decay in {sup 76}Ge. The GERDA Phase I energy calibration data have been reprocessed and an average improvement of 0.3 keV in energy resolution (FWHM) corresponding to 10% at the Q value for 0νββ decay in {sup 76}Ge is obtained. This is possible thanks to the enhanced low-frequency noise rejection of this Zero Area Cusp (ZAC) signal shaping filter. (orig.)

Resolution on the program energy-climate; Resolution sur le paquet energie-climat

Energy Technology Data Exchange (ETDEWEB)

NONE

2008-07-01

This document presents the resolutions proposed in the resolution proposition n. 1261 and concerning the european Commission program on the energy policies and the climate change. Twelve resolution are presented on the energy sources development, the energy efficiency, the energy economy and the carbon taxes. (A.L.B.)

Seeded quantum FEL at 478 keV

Energy Technology Data Exchange (ETDEWEB)

Guenther, Marc [Max-Planck-Institut fuer Quantenoptik, Garching (Germany); Thirolf, Peter; Seggebrock, Thorben [Ludwig-Maximilians-Universitaet Muenchen, Garching (Germany); Habs, Dietrich [Max-Planck-Institut fuer Quantenoptik, Garching (Germany); Ludwig-Maximilians-Universitaet Muenchen, Garching (Germany)

2012-07-01

We present for the first time a concept for a seeded {gamma} quantum Free Electron Laser (QFEL) at 478 keV (transition in {sup 7}Li). To produce a highly intense and coherent {gamma} beam, we intend to use a seeded FEL scheme. Important for the production of a highly brilliant and coherent {gamma} beam are novel refractive {gamma} lenses for focusing and an efficient monochromator, allowing to generate a very intense and coherent seed beam. To realize such a coherent {gamma} beam at 478 keV (1/38 A), it is suitable to use a quantum FEL design based on a new ''asymmetric'' laser-electron Compton back scattering scheme as pursued for the MeGaRay and ELI-NP facilities. Here the pulse length of the laser is much longer than the electron bunch length, equivalent to a {gamma}-FEL with laser wiggler. The coherence of a seeded QFEL can open up totally new areas of fundamental physics and applications. Especially, 478 keV can be attractive for ''green energy'' and life-science research, such as the detection of Li deposition in the brain for manic-depressive psychosis treatment with high spatial resolution or isotope-specific nuclear waste management and treatment.

Poster - 01: LabPET II Pixelated APD-Based PET Scanner for High-Resolution Preclinical Imaging

Energy Technology Data Exchange (ETDEWEB)

Lecomte, Roger; Arpin, Louis; Beaudoin, Jean-François; Bergeron, Mélanie; Bouchard, Jonathan; Bouziri, Haithem; Cadorette, Jules; Gaudin, Émilie; Jürgensen, Nadia; Koua, Konin Calliste; Trépanier, Pierre-Yves Lauzier; Leroux, Jean-Daniel; Loignon-Houle, Francis; Njejimana, Larissa; Paillé, Maxime; Paulin, Caroline; Pepin, Catherine; Pratte, Jean-François; Samson, Arnaud; Thibaudeau, Christian [Université de Sherbrooke, Université de Sherbrooke, CIMS/CRCHUS, Université de Sherbrooke, Université de Sherbrooke, Université de Sherbrooke, CIMS/CRCHUS, Université de Sherbrooke, Université de Sherbrooke, 3IT, Université de Sherbrooke, Novalgo Inc., Université de Sherbrooke, Université de Sherbrooke, CIMS/CRCHUS, 3IT, Université de Sherbrooke, Université de Sherbrooke, Université de Sherbrooke, Université de Sherbrooke, 3IT, Université de Sherbrooke (Canada); and others

2016-08-15

Purpose: LabPET II is a new generation APD-based PET scanner designed to achieve sub-mm spatial resolution using truly pixelated detectors and highly integrated parallel front-end processing electronics. Methods: The basic element uses a 4×8 array of 1.12×1.12 mm{sup 2} Lu{sub 1.9}Y{sub 0.1}SiO{sub 5}:Ce (LYSO) scintillator pixels with one-to-one coupling to a 4×8 pixelated monolithic APD array mounted on a ceramic carrier. Four detector arrays are mounted on a daughter board carrying two flip-chip, 64-channel, mixed-signal, application-specific integrated circuits (ASIC) on the backside interfacing to two detector arrays each. Fully parallel signal processing was implemented in silico by encoding time and energy information using a dual-threshold Time-over-Threshold (ToT) scheme. The self-contained 128-channel detector module was designed as a generic component for ultra-high resolution PET imaging of small to medium-size animals. Results: Energy and timing performance were optimized by carefully setting ToT thresholds to minimize the noise/slope ratio. ToT spectra clearly show resolved 511 keV photopeak and Compton edge with ToT resolution well below 10%. After correction for nonlinear ToT response, energy resolution is typically 24±2% FWHM. Coincidence time resolution between opposing 128-channel modules is below 4 ns FWHM. Initial imaging results demonstrate that 0.8 mm hot spots of a Derenzo phantom can be resolved. Conclusion: A new generation PET scanner featuring truly pixelated detectors was developed and shown to achieve a spatial resolution approaching the physical limit of PET. Future plans are to integrate a small-bore dedicated mouse version of the scanner within a PET/CT platform.

A new approach for precise measurements of keV neutron capture cross sections: The examples of 93Nb, 103Rh, and 181Ta

International Nuclear Information System (INIS)

Wisshak, K.; Voss, F.; Kaeppeler, F.; Reffo, G.

1990-04-01

A new experimental method has been implemented for precise measurements of neutron capture cross sections in the energy range from 3 to 200 keV. Neutrons are produced via the 7 Li(p,n) 7 Be reaction using a pulsed 3 MV Van de Graaff accelerator. The neutron energy is determined by the time of flight technique using flight paths of less than 1 m. Capture events are detected with the Karlsruhe 4π Barium Fluoride Detector. This detector is characterized by a resolution in gamma-ray energy of 14% at 662 keV and 7% at 2.5 MeV, a time resolution of 500 ps, and a peak efficiency of 90% at 1 MeV. Capture events are registered with ≅ 95% probability above a gamma-ray threshold of 2.5 MeV. The combined effect of the relatively short primary flight path, the 10 cm inner radius of the detector sphere, and of the low capture cross section of BaF 2 allows to discriminate the main background due to capture of sample scattered neutrons in the scintillator via time of flight, leaving part of the neutron energy range completely undisturbed. The high efficiency and good energy resolution for capture gamma-rays yields a further reduction of this background by using only the relevant energy channels for data evaluation. In the first measurements with the new detector, the neutron capture cross sections of 93 Nb, 103 Rh, and 181 Ta were determined in the energy range from 3 to 200 keV relative to gold as a standard. The cross section ratios could be determined with overall systematic uncertainties of 0.7 to 0.8%; statistical uncertainties were less than 1% in the energy range from 20 to 100 keV, if the data are combined in 20 keV wide bins. The necessary sample masses were of the order of one gram. Further improvements with respect to sensitivity and accuracy are discussed. (orig.) [de

SPECT imaging of 131I (364 keV): importance of collimation

International Nuclear Information System (INIS)

Clarke, L.P.; Saw, C.B.; Leong, L.K.; Serafini, A.N.

1985-01-01

A low sensitivity medium energy collimator (LSMEC) designed with thick septa and long bore (theoretical leakage 131 I for a SPECT system operated in both planar and tomographic imaging modes. The collimator was designed to minimize the influence of photon penetration on spatial resolution, in particular the resolution index FWTM. Overall spatial resolution for the planar imaging mode at 10 cm from the collimator face was found to be 11.6 mm FWHM and 21.6 mm FWTM. The corresponding transverse plane and slice thickness resolution was of the order of 17 mm FWHM and 31 mm FWTM, for a radius of rotation of 16 cm. A SPECT resolution phantom was imaged. Two quadrants of cold rods were well resolved, with rod dimensions of 16 and 12.7 mm respectively, the resolution being comparable to that obtained using 99 Tcsup(m) (140 keV) and a low-energy high-resolution collimator. NEMA sensitivity obtained was 75 cpm/μCi 131 I. The resolution measurements obtained suggest that this collimator should be useful for SPECT imaging with 131 I in either radioimmunoimaging or radioimmunotherapy. (author)

Properties of the transitions populating and depopulating the 279 keV level in /sup 75/As

Energy Technology Data Exchange (ETDEWEB)

Puri, V S; Khurana, C S; Sahota, H S [Punjabi Univ., Patiala (India). Nuclear Science Labs.

1977-09-01

The low-energy gamma-ray spectrum of /sup 75/As from /sup 75/Sc has been investigated using a 6 mm x 6 mm Si(Li) spectrometer. The intensity of the 24.4 keV transition has been found to be 0.07 +- 0.01. No evidence has been found for the presence of a 14.9 keV transition. From directional correlation measurements involving the 24.4 keV transition detected in the Si(Li) detector, the multipolarity of this transition has been found to be delta(E3/M2)sub(24.4) =0.18 +- 0.02. The internal conversion process of the 279 keV transition seems to be normal. No effect of the chemical environment has been observed on the (121 ..gamma..-279..gamma..) directional correlation coefficients.

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.

Nature of mixed symmetry 2{sup +} states in {sup 94}Mo from high resolution electron and proton scattering and line shape of the first excited 1/2{sup +} state in {sup 9}Be

Energy Technology Data Exchange (ETDEWEB)

Burda, Oleksiy

2007-07-15

The present work contains two parts. The first one is devoted to the investigation of mixed-symmetry structure in {sup 94}Mo and the second one to the astrophysical relevant line shape of the first excited 1/2{sup +} state in {sup 9}Be. In the first part of the thesis the nature of one- and two-phonon symmetric and mixed-symmetric 2{sup +} states in {sup 94}Mo is investigated with high-resolution inelastic electron and proton scattering experiments in a combined analysis. The (e,e') experiments were carried out at the 169 magnetic spectrometer at the S-DALINAC. Data were taken at a beam energy E e=70 MeV and scattering angles {theta}{sub e}=93 -165 . In dispersion-matching mode an energy resolution {delta}{sub E}=30-45 keV (full width at half maximum) was achieved. The (p,p') measurements were performed at iThemba LABS, South Africa, using a K600 magnetic spectrometer at a proton energy E p=200 MeV and scattering angles {theta}{sub p}=4.5 -26 . Typical energy resolutions were {delta}{sub E}{approx_equal}35 keV. The combined analysis reveals a dominant one-phonon structure of the transitions to the first and third 2{sup +} states, as well as an isovector character of the transition to the one-phonon mixed-symmetric state within the valence shell. Quantitatively consistent estimates of the one-phonon admixtures are obtained from both experimental probes when two-step contributions to the proton scattering cross sections are taken into account. In the second part of the thesis the line shape of the first excited 1/2{sup +} state in {sup 9}Be is studied. Spectra of the {sup 9}Be(e,e') reaction were measured at the S-DALINAC at an electron energy E e=73 MeV and scattering angles of 93 and 141 with high energy resolution up to excitation energies E{sub x}=8 MeV. The form factor of the first excited state has been extracted from the data. The astrophysical relevant {sup 9}Be({gamma},n) cross sections have been extracted from the (e,e') data. The

A comparative study of inelastic scattering models at energy levels ranging from 0.5 keV to 10 keV

Energy Technology Data Exchange (ETDEWEB)

Hu, Chia-Yu [Department of Photonics, National Cheng Kung University, Tainan 701, Taiwan (China); Lin, Chun-Hung, E-mail: chlin@mail.ncku.edu.tw [Department of Photonics, National Cheng Kung University, Tainan 701, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701, Taiwan (China)

2017-03-01

Six models, including a single-scattering model, four hybrid models, and one dielectric function model, were evaluated using Monte Carlo simulations for aluminum and copper at incident beam energies ranging from 0.5 keV to 10 keV. The inelastic mean free path, mean energy loss per unit path length, and backscattering coefficients obtained by these models are compared and discussed to understand the merits of the various models. ANOVA (analysis of variance) statistical models were used to quantify the effects of inelastic cross section and energy loss models on the basis of the simulated results deviation from the experimental data for the inelastic mean free path, the mean energy loss per unit path length, and the backscattering coefficient, as well as their correlations. This work in this study is believed to be the first application of ANOVA models towards evaluating inelastic electron beam scattering models. This approach is an improvement over the traditional approach which involves only visual estimation of the difference between the experimental data and simulated results. The data suggests that the optimization of the effective electron number per atom, binding energy, and cut-off energy of an inelastic model for different materials at different beam energies is more important than the selection of inelastic models for Monte Carlo electron scattering simulation. During the simulations, parameters in the equations should be tuned according to different materials for different beam energies rather than merely employing default parameters for an arbitrary material. Energy loss models and cross-section formulas are not the main factors influencing energy loss. Comparison of the deviation of the simulated results from the experimental data shows a significant correlation (p < 0.05) between the backscattering coefficient and energy loss per unit path length. The inclusion of backscattering electrons generated by both primary and secondary electrons for

B<sub>12sub>P>2sub>: Improved Epitaxial Growth and Evaluation of Alpha Irradiation on its Electrical Transport Properties

Energy Technology Data Exchange (ETDEWEB)

Frye, Clint D. [Kansas State Univ., Manhattan, KS (United States)

2016-10-17

The wide bandgap (3.35 eV) semiconductor icosahedral boron phosphide (B<sub>12sub>P>2sub>) has been reported to self-heal from radiation damage from β particles (electrons) with energies up to 400 keV by demonstrating no lattice damage using transmission electron microscopy. This property could be exploited to create radioisotope batteries–semiconductor devices that directly convert the decay energy from a radioisotope to electricity. Such devices potentially have enormous power densities and decades-long lifetimes. To date, the radiation hardness of B<sub>12sub>P>2sub> has not been characterized by electrical measurements nor have B<sub>12sub>P>2sub> radioisotope batteries been realized. Therefore, this study was undertaken to evaluate the radiation hardness of B<sub>12sub>P>2sub> after improving its epitaxial growth, developing ohmic electrical contacts, and reducing the residual impurities. Subsequently, the effects of radiation from a radioisotope on the electrical transport properties of B<sub>12sub>P>2sub> were tested.

High-Resolution Measurements of Low-Energy Conversion Electrons

CERN Multimedia

Gizon, A; Putaux, J

2002-01-01

Measurements of low-energy internal conversion electrons have been performed with high energy resolution in some N = 105 odd and odd-odd nuclei using a semi-circular spectrograph associated to a specific tape transport system. These experiments aimed to answer the following questions~: \\begin{itemize} \\item Do M3 isomeric transitions exist in $^{183}$Pt and $^{181}$Os, isotones of $^{184}$Au~? \\item Are the neutron configurations proposed to describe the isomeric and ground states of $^{184}$Au right or wrong~? \\item Does it exist an isomeric state in $^{182}$Ir, isotone of $^{181}$Os, $^{183}$Pt and $^{184}$Au~? \\item What are the spin and parity values of the excited states of $^{182}$Ir~? \\end{itemize} In $^{183}$Pt, the 35.0 keV M3 isomeric transition has been clearly observed and the reduced transition probability has been determined. The deduced hindrance factor is close to that observed in the neighbouring odd-odd $^{184}$Au nucleus. This confirms the neutron configurations previously proposed for the ...

3.5 keV X-ray line signal from dark matter decay in local U(1){sub B−L} extension of Zee-Babu model

Energy Technology Data Exchange (ETDEWEB)

Baek, Seungwon [School of Physics and Open KIAS Center, KIAS,85 Hoegiro Dongdaemun-gu, Seoul 130-722 (Korea, Republic of)

2015-08-06

We consider a local U(1){sub B−L} extension of Zee-Babu model to explain the recently observed 3.5 keV X-ray line signal. The model has three Standard model (SM)-singlet Dirac fermions with different U(1){sub B−L} charges. A complex scalar field charged under U(1){sub B−L} is introduced to break the U(1){sub B−L} symmetry. After U(1){sub B−L} symmetry breaking a remnant discrete symmetry stabilizes the lightest state of the Dirac fermions, which can be a stable dark matter (DM). The second lightest state, if mass splitting with the stable DM is about 3.5 keV, decays dominantly to the stable DM and 3.5 keV photon through two-loop diagrams, explaining the X-ray line signal. Two-loop suppression of the decay amplitude makes its lifetime much longer than the age of the universe and it can be a decaying DM candidate in large parameter region. We also introduce a real scalar field which is singlet under both the SM and U(1){sub B−L} and can explain the current relic abundance of the Dirac fermionic DMs. If the mixing with the SM Higgs boson is small, it does not contribute to DM direct detection. The main contribution to the scattering of DM off atomic nuclei comes from the exchange of U(1){sub B−L} gauge boson, Z{sup ′}, and is suppressed below current experimental bound when Z{sup ′} mass is heavy (≳10 TeV). If the singlet scalar mass is about 0.1–10 MeV, DM self-interaction can be large enough to solve small scale structure problems in simulations with the cold DM, such as, the core-vs-cusp problem and too-big-to-fail problem.

Measurement of astrophysical S-factors and electron screening potentials for d(d,n){sup 3}He reaction in ZrD{sub 2}, TiD{sub 2} and TaD{sub 0.5} targets in the ultralow energy region using plasma accelerator

Energy Technology Data Exchange (ETDEWEB)

Bystritsky, V.M., E-mail: bystvm@jinr.ru [Joint Institute for Nuclear Research, Dubna, Moscow Region (Russian Federation); Bystritskii, Vit.M. [Department of Physics and Astronomy, University of California, Irvine (United States); Dudkin, G.N. [National Scientific Research Tomsk Polytechnical University, Tomsk (Russian Federation); Filipowicz, M. [Faculty of Energy and Fuels, AGH, University of Science and Technology, Cracow (Poland); Gazi, S.; Huran, J. [Institute of Electrical Engineering, SAS, Bratislava (Slovakia); Kobzev, A.P. [Joint Institute for Nuclear Research, Dubna, Moscow Region (Russian Federation); Mesyats, G.A. [Lebedev Physical Institute of the Russian Academy of Sciences, Moscow (Russian Federation); Nechaev, B.A.; Padalko, V.N. [National Scientific Research Tomsk Polytechnical University, Tomsk (Russian Federation); Parzhitskii, S.S. [Joint Institute for Nuclear Research, Dubna, Moscow Region (Russian Federation); Pen' kov, F.M. [Institute of Nuclear Physics, NNC, Almaty (Kazakhstan); Philippov, A.V. [Joint Institute for Nuclear Research, Dubna, Moscow Region (Russian Federation); Kaminskii, V.L. [National Scientific Research Tomsk Polytechnical University, Tomsk (Russian Federation); Tuleushev, Yu.Zh. [Institute of Nuclear Physics, NNC, Almaty (Kazakhstan); Wozniak, J. [Faculty of Physics and Applied Computer Sciences, AGH, University of Science and Technology, Cracow (Poland)

2012-09-01

The present paper is devoted to the study of the electron screening effect influence on the rate of d(d,n){sup 3}He reaction in the ultralow deuteron collision energy range in the deuterated metals (ZrD{sub 2}, TiD{sub 2} and TaD{sub 0.5}). The ZrD{sub 2}, TiD{sub 2} and TaD0.5 targets were fabricated via magnetron sputtering of titanium, zirconium and tantalum in gas (deuterium) environment. The experiments have been carried out using the high-current pulsed Hall plasma accelerator (NSR TPU, Russia). The detection of neutrons with energy of 2.5 MeV from the dd reaction was done with plastic scintillation spectrometers. As a result of the experiments, the energy dependences of the astrophysical S-factor for the dd reaction in the deuteron collision energy range of 2-7 keV and the values of the electron screening potential U{sub e} of the interacting deuterons have been measured for the above targets: U{sub e}(ZrD{sub 2})=(205{+-}35) eV; U{sub e}(TiD{sub 2})=(125{+-}34) eV; U{sub e}(TaD{sub 0.5})=(313{+-}58) eV. Our results are compared with the other published experimental and calculated data.

Surface damage studies of ETFE polymer bombarded with low energy Si ions (≤100 keV)

International Nuclear Information System (INIS)

Minamisawa, Renato Amaral; Almeida, Adelaide De; Budak, Satilmis; Abidzina, Volha; Ila, Daryush

2007-01-01

Surface studies of ethylenetetrafluoroethylene (ETFE), bombarded with Si in a high-energy tandem Pelletron accelerator, have recently been reported. Si ion bombardment with a few MeV to a few hundred keV energies was shown to be sufficient to produce damage on ETFE film. We report here the use of a low energy implanter with Si ion energies lower than 100 keV, to induce changes on ETFE films. In order to determine the radiation damage, ETFE bombarded films were simulated with SRIM software and analyzed with optical absorption photometry (OAP), Raman and Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy to show quantitatively the physical and chemical property changes. Carbonization occurs following higher dose implantation, and hydroperoxides were formed following dehydroflorination of the polymer

Studies on effective atomic numbers for photon energy absorption and electron density of some narcotic drugs in the energy range 1 keV-20 MeV

Science.gov (United States)

Gounhalli, Shivraj G.; Shantappa, Anil; Hanagodimath, S. M.

2013-04-01

Effective atomic numbers for photon energy absorption ZPEA,eff, photon interaction ZPI,eff and for electron density Nel, have been calculated by a direct method in the photon-energy region from 1 keV to 20 MeV for narcotic drugs, such as Heroin (H), Cocaine (CO), Caffeine (CA), Tetrahydrocannabinol (THC), Cannabinol (CBD), Tetrahydrocannabivarin (THCV). The ZPEA,eff, ZPI,eff and Nel values have been found to change with energy and composition of the narcotic drugs. The energy dependence ZPEA,eff, ZPI,eff and Nel is shown graphically. The maximum difference between the values of ZPEA,eff, and ZPI,eff occurs at 30 keV and the significant difference of 2 to 33% for the energy region 5-100 keV for all drugs. The reason for these differences is discussed.

Determination of differential cross-sections for the {sup nat}K(p, p{sub 0}) and {sup 39}K(p, {alpha}{sub 0}) reactions in the backscattering geometry

Energy Technology Data Exchange (ETDEWEB)

Kokkoris, M., E-mail: kokkoris@central.ntua.g [Department of Physics, National Technical University of Athens, Zografou Campus, 157 80 Athens (Greece); Tsaris, A. [Department of Physics, National Technical University of Athens, Zografou Campus, 157 80 Athens (Greece); Misaelides, P. [Department of Chemistry, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece); Sokaras, D.; Lagoyannis, A.; Harissopulos, S. [Institute of Nuclear Physics, TANDEM Accelerator, N.C.S.R. ' Demokritos' , Aghia Paraskevi, 153 10 Athens (Greece); Vlastou, R.; Papadopoulos, C.T. [Department of Physics, National Technical University of Athens, Zografou Campus, 157 80 Athens (Greece)

2010-06-15

In the present work, new, differential cross-section values are presented for the {sup nat}K(p, p{sub 0}) reaction in the energy range E{sub lab} = 3000-5000 keV (with an energy step of 25 keV) and for detector angles between 140{sup o} and 170{sup o} (with an angular step of 10{sup o}). A qualitative discussion of the observed cross-section variations through the influence of strong, closely spaced resonances in the p + {sup 39}K system is also presented. Information has also been extracted concerning the {sup 39}K(p,{alpha}{sub 0}) reaction for E{sub lab} = 4000-5000 keV in the same angular range. As a result, more than {approx}500 data points will soon be available to the scientific community through IBANDL (Ion Beam Analysis Nuclear Data Library - (http://www-nds.iaea.org/ibandl/)) and could thus be incorporated in widely used IBA algorithms (e.g. SIMNRA, WINDF, etc.) for potassium depth profiling at relatively high proton beam energies.

The Galactic 511 keV line: analysis and interpretation of Integral observations; L'annihilation des positrons galactiques: analyse et interpretation des donnees INTEGRAL

Energy Technology Data Exchange (ETDEWEB)

Lonjou, V

2005-09-15

Ever since the discovery of the 511 keV annihilation line emission from the galactic center region in the late seventies, the origin of galactic positrons has been the topic of a vivid scientific debate. It is also one of the prime scientific objectives of the imaging spectrometer SPI on board ESA's INTEGRAL observatory. In this thesis first a description of the most important SPI sub-system is given - the detector plane. Procedures for detector energy calibration and detector degradation analysis are developed. The determination of instrumental background models, a crucial aspect of data analysis, is elaborated. These background models are then applied to deriving sky maps and spectra of unprecedented quality of the Galactic positron annihilation radiation. The emission is centered on the galactic center with a spatial resolution of 8 degrees (FWHM), a second spatial component appears clearly: the galactic disc. The ray energy has been measured with unprecedented accuracy: 511.0 {+-} 0.03 keV for a full width at half maximum (FWHM) of 2.07 {+-} 0.1 keV. The total galactic flux ranges from 1.09 to 2.43 10{sup -3} ph.cm{sup -2}.s{sup -1} including uncertainties on spatial distribution. Finally, the implications of these observations for the production of positrons by various Galactic populations are discussed.

High resolution krypton M/sub 4,5/ x-ray emission spectra

International Nuclear Information System (INIS)

Perera, R.C.C.; Hettrick, M.C.; Lindle, D.W.

1987-10-01

High resolution M/sub 4,5/ (3d → 4p) x-ray emission spectra from a krypton plasma were measured using a recently developed grazing-incidence reflection-grating monochromator/spectrometer with very high flux rates at extreme ultraviolet and soft x-ray wave lengths. The nominal resolving power of the instrument, E/ΔE, is about 300 in this energy range (∼80 eV). Three dipole-allowed 3d → 4p emission lines were observed at 80.98 eV, 80.35 eV and 79.73 eV. A broad peak at about 82.3 eV is tentatively assigned to transitions resulting from Kr 2+ , and effects of excitation energy on M/sub 4,5/ x-ray emission were observed. 9 refs., 3 figs., 1 tab

Low energy atomic field bremsstrahlung from thin rare gas targets

International Nuclear Information System (INIS)

Semaan, M.E.

1982-01-01

A relative measurement of the doubly-differential cross-section for electron atomic field bremsstrahling, differential in photon energy and angle is reported. Data for (d 2 sigma)/(dk dO/sub k/) have been taken for incident electron energies T ranging from 4 to 10 keV on target atoms of helium, neon, argon, krypton and xenon at a photon emission angle of 90 0 . The X-rays, produced at 90 0 to the intersection of the crossed electron and gas beams, are detected by a Si(Li) detector, having a resolution of about 200 eV at 6 keV and 0.3 mil Be window. The theoretical angular distribution (d 2 sigma)/(dk dO/sub k/) has been deduced from the photon energy spectrum by the use of the shape function S(Z,T,k,T) defined by Tseng and Pratt as S(Z,T,k,T) = [(d 2 sigma)/(dk dO/sub k/)] / [(dsigma)/(dk)]. The values of S used were obtained by an interpolation of the benchmark data provided by Pratt et al. Agreement between our experiment and the theory is measured by how well the theoretical curve fits the data. The agreement appeared to be good

Calibration of hard x-ray (15 - 50 keV) optics at the MPE test facility PANTER

Science.gov (United States)

Bräuninger, Heinrich; Burkert, Wolfgang; Hartner, Gisela D.; Citterio, Oberto; Ghigo, Mauro; Mazzoleni, Francesco; Pareschi, Giovanni; Spiga, Daniele

2004-02-01

The Max-Planck-Institut für extraterrestrische Physik (MPE) in Garching, Germany, operates the large X-ray beam line facility PANTER for testing astronomical systems. At PANTER a number of telescopes like EXOSAT, ROSAT, SAX, JET-X, ABRIXAS, XMM and SWIFT operating in the soft energy range (0.02 - 15 keV) have been successfully calibrated. In the present paper we report on an important upgrade recently implemented that enables the calibration of hard X-ray optics (from 15 up to 50 keV). Currently hard X-ray optics based on single and multilayer coating are being developed for several future X-ray missions. The hard X-ray calibrations at PANTER are carried out by a high energy source based on an electron gun and several anodes, able to cover the energy range from 4.5 up to 50 keV. It provides fluxes up to 104 counts/sec/cm2 at the instrument chamber with a stability better than 1%. As detector a pn-CCD camera operating between 0.2 and 50 keV and a collecting area of 36 cm2 is used. Taking into account the high energy resolution of the CCD (145 eV at 6 keV), a very easy way to operate the facility in hard X-ray is in energy-dispersive mode (i.e. with a broad-band beam). A double crystal monochromator is also available providing energies up to 20 keV. In this paper we present the first results obtained by using PANTER for hard X-ray characterizations, performed on prototype multilayer optics developed by the Osservatorio Astronomico di Brera (OAB), Milano, Italy, and the Harvard-Smithsonian Center for Astrophysics (CfA), Cambridge, MA, USA.

Z/sub 1/ dependence of ion-induced electron emission from aluminum. [H/sup +/,H/sub 2//sup +/,D/sup +/,D/sub 2//sup +/,He/sup +/,B/sup +/,C/sup +/,N/sup +/,N/sub 2//sup +/,O/sup +/,O/sub 2//sup +/,F/sup +/,Ne/sup +/,S/sup +/,Cl/sup +/,Ar/sup +/,Kr/sup +/, and Xe/sup +/, 1. 2-50 keV

Energy Technology Data Exchange (ETDEWEB)

Alonso, E.V.; Baragiola, R.A.; Ferron, J.; Jakas, M.M.; Oliva-Florio, A.

1980-07-01

We have measured the electron emission yields ..gamma.. of clean aluminum under bombardment with H/sup +/, H/sub 2/ /sup +/, D/sup +/, D/sub 2/ /sup +/, He/sup +/, B/sup +/, C/sup +/, N/sup +/, N/sub 2/ /sup +/, O/sup +/, O/sub 2/ /sup +/, F/sup +/, Ne/sup +/, S/sup +/, Cl/sup +/, Ar/sup +/, Kr/sup +/, and Xe/sup +/ in the energy range 1.2--50 keV. The clean surfaces were prepared by in situ evaporation of high-purity Al under ultra-high-vacuum conditions. It is found that kinetic electron emission yields ..gamma../sub k/, obtained after subtracting from the measured ..gamma.. a contribution due to potential emission, are roughly proportional to the electronic stopping powers, for projectiles lighter than Al. For heavier projectiles there is a sizable contribution to electron emission from collisions involving rapidly recoiling target atoms, which increases with the mass of the projectile, and which dominates the threshold and near-threshold behavior of kinetic emission. The results, together with recently reported data on Auger electron emission from ion-bombarded Al show that the mechanism proposed by Parilis and Kishinevskii of inner-shell excitation and subsequent Auger decay is negligible for light ions and probably small for heavy ions on Al and in our energy range. We thus conclude that kinetic electron emission under bombardment by low-energy ions results mainly from the escape of excited valence electrons.

Energy distribution measurements of 300 keV transmitted protons at the axial-to-planar channeling transition in silicon

International Nuclear Information System (INIS)

Bulgakov, Yu.V.; Lenkeit, K.; Stolle, R.

1983-01-01

The energy distribution of protons with initial energy of 300 keV which passed through a 0.76 μm thick Si monocrystal film was measured under the conditions of transition from the axial to planar (110) channeling. The experimental angular dependences of the transparency coefficient and of the first three moments of the energy distributions (energy loss, straggling, and skewness) for 300 keV protons are shown. The shape of curves are discussed explaining the resonance dechanneling effect and the non-monotonic behaviour of transparency in the case of the axial-to-planar channeling transition

Evaluation and optimization of the High Resolution Research Tomograph (HRRT)

International Nuclear Information System (INIS)

Knoess, C.

2004-01-01

Positron Emission Tomography (PET) is an imaging technique used in medicine to determine qualitative and quantitative metabolic parameters in vivo. The High Resolution Research Tomograph (HRRT) is a new high resolution tomograph that was designed for brain studies (312 mm transaxial field-of-view (FOV), 252 mm axial FOV). The detector blocks are arranged in a quadrant sharing design and consist of two crystal layers with dimensions of 2.1 mm x 2.1 mm x 7.5 mm. The main detector material is the newly developed scintillator lutetium oxyorthosilicate (LSO). Events from the different crystal layers are distinguished by Pulse Shape Discrimination (PSD) to gain Depth of Interaction (DOI) information. This will improve the spatial resolution, especially at the edges of the FOV. A prototype of the tomograph was installed at the Max-Planck Institute for Neurological Research in Cologne, Germany in 1999 and was evaluated with respect to spatial resolution, sensitivity, scatter fraction, and count rate behavior. These performance measurements showed that this prototype provided a spatial resolution of around 2.5 mm in a volume big enough to contain the human brain. A comparison with a single layer HRRT prototype showed a 10% worsening of the resolution, despite the fact that DOI was used. Without DOI, the resolution decreased considerably. The sensitivity, as measured with a 22 Na point source, was 46.5 cps/kBq for an energy window of 350-650 keV and 37.9 cps/kBq for an energy window of 400-650 keV, while the scatter fractions were 56% for 350-650 keV and 51% for 400-650 keV, respectively. A daily quality check was developed and implemented that uses the uniform, natural radioactive background of the scintillator material LSO. In 2001, the manufacturer decided to build a series of additional HRRT scanners to try to improve the design (detector electronics, transmission source design, and shielding against out-of-FOV activity) and to eliminate problems (difficult detector

QUIET-TIME SUPRATHERMAL (∼0.1–1.5 keV) ELECTRONS IN THE SOLAR WIND

Energy Technology Data Exchange (ETDEWEB)

Tao, Jiawei; Wang, Linghua; Zong, Qiugang; He, Jiansen; Tu, Chuanyi [School of Earth and Space Science, Peking University, Beijing 100871 (China); Li, Gang [Department of Physics and CSPAR, University of Alabama in Huntsville, Alabama 35899 (United States); Salem, Chadi S.; Bale, Stuart D. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Wimmer-Schweingruber, Robert F., E-mail: wanglhwang@gmail.com [Institute for Experimental and Applied Physics, University of Kiel, Leibnizstrasse 11, D-24118 Kiel (Germany)

2016-03-20

We present a statistical survey of the energy spectrum of solar wind suprathermal (∼0.1–1.5 keV) electrons measured by the WIND 3DP instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. After separating (beaming) strahl electrons from (isotropic) halo electrons according to their different behaviors in the angular distribution, we fit the observed energy spectrum of both strahl and halo electrons at ∼0.1–1.5 keV to a Kappa distribution function with an index κ and effective temperature T{sub eff}. We also calculate the number density n and average energy E{sub avg} of strahl and halo electrons by integrating the electron measurements between ∼0.1 and 1.5 keV. We find a strong positive correlation between κ and T{sub eff} for both strahl and halo electrons, and a strong positive correlation between the strahl n and halo n, likely reflecting the nature of the generation of these suprathermal electrons. In both solar cycles, κ is larger at solar minimum than at solar maximum for both strahl and halo electrons. The halo κ is generally smaller than the strahl κ (except during the solar minimum of cycle 23). The strahl n is larger at solar maximum, but the halo n shows no difference between solar minimum and maximum. Both the strahl n and halo n have no clear association with the solar wind core population, but the density ratio between the strahl and halo roughly anti-correlates (correlates) with the solar wind density (velocity)

Luminescence properties and gamma-ray response of the Ce and Ca co-doped (Gd,Y)F{sub 3} single crystals

Energy Technology Data Exchange (ETDEWEB)

Kamada, Kei, E-mail: k-kamada@furukawakk.co.jp [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai (Japan); Furukawa Co. Ltd. (Japan); Yanagida, Takayuki; Fujimoto, Yutaka; Fukabori, Akihiro [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai (Japan); Yoshikawa, Akira [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai (Japan); New Industry Creation Hatchery Center, Tohoku University, Sendai (Japan); Nikl, Martin [Institute of Physics AS CR (Czech Republic)

2011-12-11

The Ca0.5% and Ce1%, 3%, 7%, 10% co-doped Gd{sub 0.5}Y{sub 0.5}F{sub 3} single crystals were grown by the {mu}-PD method. In the Ca0.5% and Ce3% co-doped sample, Ce{sup 3+}-perturbed luminescence at 380 nm was observed with 32.4 ns photoluminescence decay time. The energy transfer in the sequence of the regular Ce{sup 3+}{yields} (Gd{sup 3+}){sub n}{yields} the perturbed Ce{sup 3+} sites was evidenced through observation of decay time shortening of the regular Ce{sup 3+} and Gd{sup 3+} centers and the change between the Gd{sup 3+} and Ce{sup 3+}-perturbed emission intensity. The gamma-ray excited scintillation response of the Ca0.5%, Ce7% co-doped Gd{sub 0.5}Y{sub 0.5}F{sub 3} sample was investigated with the help of the pulse height spectra and the light yield, energy resolution and non-proportionality was evaluated in the interval of energies of 59.4-1274 keV.

A hybrid, broadband, low noise charge preamplifier for simultaneous high resolution energy and time information with large capacitance semiconductor detector

International Nuclear Information System (INIS)

Goyot, M.

1975-05-01

A broadband and low noise charge preamplifier was developed in hybrid form, for a recoil spectrometer requiring large capacitance semiconductor detectors. This new hybrid and low cost preamplifier permits good timing information without compromising energy resolution. With a 500 pF external input capacity, it provides two simultaneous outputs: (i) the faster, current sensitive, with a rise time of 9 nsec and 2 mV/MeV on 50 ohms load, (ii) the lower, charge sensitive, with an energy resolution of 14 keV (FWHM Si) using a RC-CR ungated filter of 2 μsec and a FET input protection [fr

Moessbauer spectroscopy at the 93.3 KeV gamma transition at Zn-67

International Nuclear Information System (INIS)

Forster, A.

1981-01-01

This work presents the result of a Moessbauer effect study at the zinc-67 isotope. The 93.3 KeV gamma transition has the highest energy resolution of all accessible Moessbauer transitions. Source and absorber we cooled down to 4.2 K. The aim of the examination was 1) development of a method for solid state physical measuring of Moessbauer-resonances with high resolution and 2) to test this method to study the hfs parameters for ZnO, ZnS, ZnSe, ZnTe and ZnF 2 . (KHF)

Deuteron polarizability and S-wave π+d scattering at energies below 1 keV

International Nuclear Information System (INIS)

Pupyshev, V.V.

1987-01-01

The influence of deuteron polarizability on the S-wave π + d-scattering in a low-energy limit is explored in the framework of the variable phase method. It is shown that the nonoscillating part of the S-wave cross section of π + d-scattering has a deep and sharp minimum in the energy region ∼ 0.4 keV

Direct band gap measurement of Cu(In,Ga)(Se,S){sub 2} thin films using high-resolution reflection electron energy loss spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Heo, Sung [Analytical Engineering Group, Samsung Advanced Institute of Technology, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-803 (Korea, Republic of); College of Information and Communication Engineering, Sungkyunkwan University, Cheoncheon-dong 300, Jangan-gu, Suwon 440-746 (Korea, Republic of); Lee, Hyung-Ik; Park, Jong-Bong; Ko, Dong-Su; Chung, JaeGwan; Kim, KiHong; Kim, Seong Heon; Yun, Dong-Jin; Ham, YongNam; Park, Gyeong Su [Analytical Engineering Group, Samsung Advanced Institute of Technology, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-803 (Korea, Republic of); Song, Taewon [Energy lab, Samsung Advanced Institute of Technology, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-803 (Korea, Republic of); Lee, Dongho, E-mail: dhlee0333@gmail.com; Nam, Junggyu [PV Development Team, Energy Solution Business Division, Samsung SDI, 467 Beonyeong-ro, Cheonan-si, Chungcheongnam-do 331-330 (Korea, Republic of); Kang, Hee Jae [Department of Physics, Chungbuk National University, Gaesin-dong, Heungdeok-gu, Cheongju, 361-763 (Korea, Republic of); Choi, Pyung-Ho; Choi, Byoung-Deog, E-mail: bdchoi@skku.edu [College of Information and Communication Engineering, Sungkyunkwan University, Cheoncheon-dong 300, Jangan-gu, Suwon 440-746 (Korea, Republic of)

2015-06-29

To investigate the band gap profile of Cu(In{sub 1−x},Ga{sub x})(Se{sub 1−y}S{sub y}){sub 2} of various compositions, we measured the band gap profile directly as a function of in-depth using high-resolution reflection energy loss spectroscopy (HR-REELS), which was compared with the band gap profile calculated based on the auger depth profile. The band gap profile is a double-graded band gap as a function of in-depth. The calculated band gap obtained from the auger depth profile seems to be larger than that by HR-REELS. Calculated band gaps are to measure the average band gap of the spatially different varying compositions with respect to considering its void fraction. But, the results obtained using HR-REELS are to be affected by the low band gap (i.e., out of void) rather than large one (i.e., near void). Our findings suggest an analytical method to directly determine the band gap profile as function of in-depth.

Identification of an isomer in 110Ag at 1-keV excitation energy

International Nuclear Information System (INIS)

Clark, D.D.; Kostroun, V.O.; Siems, N.E.

1975-01-01

The existence of a new isomeric state in 110 Ag at approx. 1 keV excitation has been established in two experiments using a new instrument, the inner-shell-vacancy (ISV) detector. In the first experiment, a transition with a half-life of 660 plus-or-minus 40 ns was observed to follow the well-known 116-keV M4 transition that depopulates the 6 + 250-day isomeric level in 110 Ag; the energy of the new transition was deduced to be 109 Ag(n, γ) 110 Ag reaction to follow γ transitions previously assigned by others to populate a 1-keV excited state. The two results indicate the existence of a 2 - 660-ns isomer at 1.11 keV. Under the assumption that the newly observed transition is from a 2 - 1.11-keV state to the 1 + ground state, its hindrance factor with respect to the Moszkowski estimate is approx. 2.6 times 10 3 . Possible chemical-state perturbations of the measured half-life are estimated to be much smaller than the measurement error. In both experiments the approx. 1-keV transition was detected with the ISV detector, a new device based on the well-established atomic effect that within approx. 10 -14 s after the formation of an inner shell vacancy an atom will undergo a multiple loss of []lectrons ranging from several to 20 or more, the number being a function of Z and subshell. The emitted electrons, which are very soft, are collected with an accelerating and focusing electrostatic lens and detected with a plastic scintillator and a photomultiplier tube. Nuclear transitions that cause ISVs can thus be sensed. Experiments are described that show the detector is fast, sensitive, selective, and efficient in responding to ISVs.

X-ray spectrometer having 12 000 resolving power at 8 keV energy

Science.gov (United States)

Seely, John F.; Hudson, Lawrence T.; Henins, Albert; Feldman, Uri

2017-10-01

An x-ray spectrometer employing a thin (50 μm) silicon transmission crystal was used to record high-resolution Cu Kα spectra from a laboratory x-ray source. The diffraction was from the (331) planes that were at an angle of 13.26° to the crystal surface. The components of the spectral lines resulting from single-vacancy (1s) and double-vacancy (1s and 3d) transitions were observed. After accounting for the natural lifetime widths from reference double-crystal spectra and the spatial resolution of the image plate detector, the intrinsic broadening of the transmission crystal was measured to be as small as 0.67 eV and the resolving power 12 000, the highest resolving power achieved by a compact (0.5 m long) spectrometer employing a single transmission crystal operating in the hard x-ray region. By recording spectra with variable source-to-crystal distances and comparing to the calculated widths from various geometrical broadening mechanisms, the primary contributions to the intrinsic crystal broadening were found to be the source height at small distances and the crystal apertured height at large distances. By reducing these two effects, using a smaller source size and vignetting the crystal height, the intrinsic crystal broadening is then limited by the crystal thickness and the rocking curve width and would be 0.4 eV at 8 keV energy (20 000 resolving power).

Measured energy dependence of L-shell photoelectric cross sections of lead in the energy region 17-50 keV

Energy Technology Data Exchange (ETDEWEB)

Arora, S K; Allawadhi, K L; Sood, B S [Punjabi Univ., Patiala (India). Nuclear Science Labs.

1980-08-28

The energy dependence of L-shell photoelectric cross sections for lead in the energy region 17-50 keV has been investigated. The method utilises external conversion x-rays as the source of photons and it yields relative rather than absolute cross sections, but is simpler and more accurate. The results show fairly good agreement with theory.

A study of energy resolution in a gridded ionization chamber filled with tetramethylsilane and tetramethylgermanium

International Nuclear Information System (INIS)

Hara, H.; Ohnuma, H.; Hoshi, Y.; Yuta, H.; Abe, K.; Suekane, F.; Neichi, M.; Nakajima, T.; Masuda, K.

1998-01-01

The energy resolutions of 976 keV conversion electrons from a 207 Bi source are measured in a gridded ionization chamber filled with tetramethylsilane (TMS) and tetramethylgermanium (TMG), and are found to be about 5.7 and 5.5% (rms) for TMS and TMG, respectively. We also deduce a simple method of estimating the electron lifetime using a gridded ionization chamber. The electron lifetime, free ion yield and thermalization length for these liquids are measured by this simple method

Electron scattering by Ne, Ar and Kr at intermediate and high energies, 0.5-10 keV

Energy Technology Data Exchange (ETDEWEB)

Garcia, G.; Roteta, M.; Manero, F. [Centro de Investigaciones Energeticas Medioambientales y Tecnologicas (CIEMAT), Departamento de Fusion y Particulas Elementales, Madrid (Spain); Blanco, F. [Universidad Complutense de Madrid, Facultad de Fisica, Departamento de Fisica Atomica Molecular y Nuclear, Madrid (Spain); Williart, A. [Universidad Nacional de Educacion a Distancia, Facultad de Ciencias, Departamento de Fisica de los Materiales, Madrid (Spain)

1999-04-28

Semi-empirical total cross sections for electron scattering of noble gases (Ne, Ar and Kr) in the energy range 0.5-10 keV have been obtained by combining transmission-beam measurements for impact energies up to 6 keV with an asymptotic behaviour at higher energies according to the Born-Bethe approximation. The influence of the forward electron scattering on the experimental system has been evaluated by means of a Monte Carlo electron transport simulation. Theoretical values have also been obtained by applying the Born approximation in the case of inelastic processes and by means of an atomic scattering potential for the elastic part. The results of these calculations show an excellent agreement with the semi-empirical values in the above-mentioned energy range. (author)

Effective atomic number and effective electron densities of some inorganic compounds for Compton effect in the gamma energy range 280 keV to 1115 keV

International Nuclear Information System (INIS)

Prasannakumar, S.; Umesh, T.K.

2014-01-01

The effective atomic number and effective electron densities of some inorganic compounds for Compton effect in the gamma energy range 280 keV to 1115 keV by using Compton scattering cross sections which are determined on a goniometer assembly. An ORTEC model 23210 gamma-x high purity germanium detector (HpGe) has been used to record the data along with a personal computer based MCA in the angular region 50°-110°. The effective atomic numbers so obtained were found to be equal to the total number of electrons present in the sample in accordance with the chemical formula. The results so obtained are of first of their kind at these energies and are expected to be important in a variety of applications of radiation physics and chemistry. (author)

Energy dependent features of X-ray signals in a GridPix detector

Science.gov (United States)

Krieger, C.; Kaminski, J.; Vafeiadis, T.; Desch, K.

2018-06-01

We report on the calibration of an argon/isobutane (97.7%/2.3%)-filled GridPix detector with soft X-rays (277 eV to 8 keV) using the variable energy X-ray source of the CAST Detector Lab at CERN. We study the linearity and energy resolution of the detector using both the number of pixels hit and the total measured charge as energy measures. For the latter, the energy resolution σE / E is better than 10% (20%) for energies above 2 keV (0.5 keV). Several characteristics of the recorded events are studied.

C60 and U ion irradiation of Gd<sub>2sub>Ti_xZr>2-xsub>O>7sub> pyrochlore

Energy Technology Data Exchange (ETDEWEB)

Zhang, Jiaming; Toulemonde, Marcel; Lang, Maik; Costantini, Jean Marc; Della-Negra, Serge; Ewing, Rodney C.

2015-08-01

Gd<sub>2sub>Ti_xZr>2-xsub>O>7sub> (x = 0 to 2) pyrochlore was irradiated by 30 MeV C<sub>60sub> clusters, which provide an extremely high ionizing energy density. Here, high-resolution transmission electron microscopy revealed a complex ion-track structure in Gd<sub>2sub>Ti>2sub>O>7sub> and Gd<sub>2sub>TiZrO>7sub>, consisting of an amorphous core and a shell of a disordered, defect-fluorite structure.

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

HRTEM imaging of atoms at sub-Angstroem resolution

International Nuclear Information System (INIS)

O'Keefe, Michael A.; Allard, Lawrence F.; Blom, Douglas A.

2005-01-01

John Cowley and his group at Arizona State University pioneered the use of transmission electron microscopy for high-resolution imaging. Images were achieved three decades ago showing the crystal unit cell content at better than 4 A resolution. This achievement enabled researchers to pinpoint the positions of heavy atom columns within the unit cell. Lighter atoms appear as resolution is improved to sub-Angstroem levels. Currently, advanced microscopes can image the columns of the light atoms (carbon, oxygen, nitrogen) that are present in many complex structures, and even the lithium atoms present in some battery materials. Sub-Angstroem imaging, initially achieved by focal-series reconstruction of the specimen exit surface wave, will become commonplace for next-generation electron microscopes with C s -corrected lenses and monochromated electron beams. Resolution can be quantified in terms of peak separation and inter-peak minimum, but the limits imposed on the attainable resolution by the properties of the microscope specimen need to be considered. At extreme resolution the 'size' of atoms can mean that they will not be resolved even when spaced farther apart than the resolution of the microscope. (author)

HRTEM Imaging of Atoms at Sub-Angstrom Resolution

Energy Technology Data Exchange (ETDEWEB)

O' Keefe, Michael A.; Allard, Lawrence F.; Blom, Douglas A.

2005-04-06

John Cowley and his group at Arizona State University pioneered the use of transmission electron microscopy (TEM) for high-resolution imaging. Images were achieved three decades ago showing the crystal unit cell content at better than 4 Angstrom resolution. This achievement enabled researchers to pinpoint the positions of heavy atom columns within the unit cell. Lighter atoms appear as resolution is improved to sub-Angstrom levels. Currently, advanced microscopes can image the columns of the light atoms (carbon, oxygen, nitrogen) that are present in many complex structures, and even the lithium atoms present in some battery materials. Sub-Angstrom imaging, initially achieved by focal-series reconstruction of the specimen exit surface wave, will become common place for next-generation electron microscopes with CS-corrected lenses and monochromated electron beams. Resolution can be quantified in terms of peak separation and inter-peak minimum, but the limits imposed on the attainable resolution by the properties of the micro-scope specimen need to be considered. At extreme resolution the ''size'' of atoms can mean that they will not be resolved even when spaced farther apart than the resolution of the microscope.

High power pulse electron beam modification and ion implantation of Hg{sub 1-x}Cd{sub x}Te crystals

Energy Technology Data Exchange (ETDEWEB)

Vojtsekhovskij, A V; Remnev, G E [Tomsk Polytechnic Univ. (Russian Federation). Nuclear Physics Inst.; Opekunov, M S; Kokhanenko, A P; Korotaev, A G; Denisov, Yu A; Oucherenko, D A [Tomsk State Univ. (Russian Federation). Dept. of Radiophysics

1997-12-31

Hg{sub 1-x}Cd{sub x}Te (MCT) samples (x = 0.21 - 0.22) were irradiated by pulse electron beams at doses of 10{sup 13} to 10{sup 17} cm{sup -2}. The electron beams possessed the following parameters: 500 keV electron energy (30-40 A/cm{sup 2} electron current density, 60-80 ns current pulse); 200 keV electron energy (8- 10 A/cm{sup 2} electron current density, 100-200 ns current pulse). The electric conductivity and recombination of modified samples were investigated by the Hall effect and photoconductivity methods. For the 200 keV electron energy beam irradiation, the n-type surface regions were obtained under threshold mechanisms of donor defect generation. For the 500 keV electron energy beam irradiation, the maximum value of charge carrier lifetimes occur in the p- to n-type conductivity conversion range for the initial p-type crystals due to the conductivity compensation. MCT samples (x = 0.21 - 0.22) were implanted with Al ions at doses of 10{sup 12}-10{sup 16} cm{sup -2}. The ion beams possessed the following parameters: (1-10) A/cm{sup 2} ion current density, (100-200) ns current pulse; (150-450) keV Al ion (Al{sup +},Al{sup ++}, Al{sup +++}). The ion distribution and doping profiles were investigated by PIGE and Hall effect methods. Comparison between MCT samples after power pulse ion implantation and after standard ion implantation demonstrates differences in ion distribution, doping profiles and defect formation radiation mechanisms. (author). 3 figs., 8 refs.

Neutron diagnostic that measures Z/sub eff/ in a neutral-beam-heated Tokomak

International Nuclear Information System (INIS)

Slaughter, D.R.

1979-01-01

The rate of pitch-angle scattering in a beam-driven Tokomak is proportional to Z/sub eff/ when neutral deuterium is injected parallel or antiparallel to the toroidal field B/sub T/. The energy spectrum of neutrons produced by D--D or D--T reactions is sensitive to the angular distribution of reacting energetic deuterons so that a measurement of the spectrum may be used to infer Z/sub eff/. Energy spectra of neutrons emitted parallel to B/sub T/ during simultaneous co- and counter-injection were calculated for the case of 120-keV beams by using a PPPL code. The results were then convoluted with spectrometer lineshapes determined experimentally for a system used to measure neutron spectra during a 1.0-s source pulse. Results indicate that Z/sub eff/ in the range of 1 to 4 may be determined with uncertainties of +- 0.25 for D--D plasma and +- 0.5 for D--T plasma, provided the ion temperature T/sub i/ is well known. However, the spectrometer energy resolution is not adequate to determine T/sub i/ directly from a neutron--spectrum measurement. In the absence of accurate T/sub i/ data, the uncertainty in Z/sub eff/ is approximately +- 1. In either case, impurity identification is not established by this type of measurement

Measurement of the G-value for 1. 5 keV X-rays

Energy Technology Data Exchange (ETDEWEB)

Freyer, J.P.; Schillaci, M.E.; Raju, M.R. (Los Alamos National Lab., NM (USA))

1989-12-01

Using a ferrous sulfate solution modified by the addition of benzoic acid, the authors measured relative G-values for Al{sub k} characteristic X-rays (1.5keV), {sup 238}Pu {alpha}-particles (3.7MeV), {sup 60}Co (1.17 MeV) and {sup 137}Cs (0.66 MeV){gamma}-rays. Relative ferrous-to-ferric conversions as a function of dose were similar for the two {gamma}-ray energies, yielding G-values of 1.62 and 1.59 {mu}mol J{sup -1} for the {sup 60}Co and {sup 137}Cs radiations. The {alpha}-particle G-value was 0.52 {mu}mol J{sup -1}, or 31% of that for {sup 60}Co {gamma}-rays. The Al{sub k} X-rays had a G-value of 0.92 {mu}mol J{sup -1} or 57% of that of the {sup 60}Co radiation. This G-value for 1.5 keV X-rays is within 20% of values predicted by current theories, and theoretical values are within the error range of the authors' measurements. (author).

X-ray attenuation coefficient measurements for photon energies 4.508-13.375 keV in Cu, Cr and their compounds and the validity of the mixture rule

International Nuclear Information System (INIS)

Turgut, Ue.; Simsek, Oe.; Bueyuekkasap, E.; Ertugrul, M.

2004-01-01

To investigate the validity of the mixture rule which is used to compute the mass attenuation coefficients in compounds, the total mass attenuation coefficients for Cu, Cr elements and Cu 2 O, CuC 2 O 4 , CuCl 2 ·2H 2 O, Cu(C 2 H 3 O 2 ) 2 ·H 2 O, Cr 2 O 3 , Cr(NO 3 ) 3 , Cr 2 (SO 4 ) 3 ·H 2 O, Cr 3 (CH 3 CO 7 )(OH) 2 compounds were measured at photon energies between 4.508 and 13.375 keV by using the secondary excitation method. Ti, Mn, Fe, Ni, Zn, Ge, As, Rb elements were used as secondary exciters. 59.5 keV gamma rays emitted from an 241 Am annular source were used to excite the secondary exciters and Kα (K-L 3 , L 2 ) rays emitted from the secondary exciter were counted by a Si(Li) detector with a resolution of 160 eV at 5.9 keV. Our measurements indicate that the mixture rule is not a suitable method for the computation of mass attenuation coefficients of compounds especially at an energy that is near the absorption edge. Obtained values were compared with theoretical values

Energy absorption coefficients for 662 keV gamma ray in some fatty acids

International Nuclear Information System (INIS)

Bhandal, G.S.; Singh, K.; Rama Rani; Vijay Kumar

1993-01-01

The mass energy absorption coefficient refers to the amount of energy dissipation by the secondary electron set in motion as a result of interactions between incident photons and matter. Under certain conditions, the energy dissipated by electrons in a given volume can be equated to the energy absorbed in that volume. The absorbed energy is of basic interest in radiation dosimetry because it represents the amount of energy made available for the production of chemical or biological effects. Sphere transmission is employed for the direct measurement of mass energy absorption coefficients at 662 keV in some fatty acids. Excellent agreement is obtained between the measured and theoretical values. (author). 6 refs., 1 fig., 1 tab

Performance of CdZnTe strip detectors as sub-millimeter resolution imaging gamma radiation spectrometers

International Nuclear Information System (INIS)

Mayer, M.; Boykin, D.V.; Drake, A.

1996-01-01

We report γ-ray detection performance measurements and computer simulations of a sub-millimeter pitch CdZnTe strip detector. The detector is a prototype for γ-ray astronomy measurements in the range of 20-200 keV. The prototype is a 1.5 mm thick, 64 x 64 orthogonal stripe CdZnTe detector of 0.375 mm pitch in both dimensions, with approximately one square inch of sensitive area. Using discrete laboratory electronics to process signals from 8 x 8 stripe region of the prototype we measured good spectroscopic uniformity and sub-pitch (∼ 0.2 mm) spatial resolution in both x and y dimensions. We present below measurements of the spatial uniformity, relative timing and pulse height of the anode and cathode signals, and the photon detection efficiency. We also present a technique for determining the location of the event in the third dimension (depth). We simulated the photon interactions and signal generation in the strip detector and the test electronics and we compare these results with the data. The data indicate that cathode signal - as well as the anode signal - arises more strongly from the conduction electrons rather than the holes

Development of a flat-field spectrometer with a wideband Ni/C multilayer grating in the 1–3.5 keV range

Energy Technology Data Exchange (ETDEWEB)

Imazono, Takashi [Quantum Beam Science Center, Japan Atomic Energy Agency, 8-1-7, Umemidai, Kizugawa, Kyoto 619-0216 (Japan)

2016-07-27

To develop a flat-field spectrometer with coverage of the 1–3.5 keV range, a wideband Ni/C multilayer grating was invented. The multilayer consists of two kinds of layer structures. One is a conventional periodic multilayer of thickness D{sub 1} = 5.6 nm, Ni thickness ratio to the multilayer period γ{sub 1} = 0.5 and the number of layers N{sub 1} = 79. Both the first and last layers are Ni. The other is a C/Ni bilayer of D{sub 2} = 8.4 nm, γ{sub 2} = 0.53 and N{sub 2} = 2. The first layer is C and then Ni. The aperiodic multilayer from the topmost C/Ni bilayer was coated on a laminar-type grating having an effective grating constant of 1/2400 mm, groove depth of 2.8 nm, and duty ratio (land width/groove period) of 0.5. In a preliminary experiment, the diffraction efficiency was in excess of 0.8% in the energy range of 2.1-3.3 keV and the maximum of 5.4% at 3.1 keV at a constant angle of incidence of 88.54°, which is considerably higher than that of an Au-coated grating before deposition of the multilayer.

Gamma-Ray Imager With High Spatial And Spectral Resolution

Science.gov (United States)

Callas, John L.; Varnell, Larry S.; Wheaton, William A.; Mahoney, William A.

1996-01-01

Gamma-ray instrument developed to enable both two-dimensional imaging at relatively high spatial resolution and spectroscopy at fractional-photon-energy resolution of about 10 to the negative 3rd power in photon-energy range from 10 keV to greater than 10 MeV. In its spectroscopic aspect, instrument enables identification of both narrow and weak gamma-ray spectral peaks.

Measurements of energy losses, distributions of energy loss and additivity of energy losses for 50 to 150 keV protons in hydrogen and nine hydrocarbon gases

International Nuclear Information System (INIS)

Thorngate, J.H.

1976-05-01

Measurements of energy-loss distributions were made for 51, 102, and 153 keV protons traversing hydrogen, methane, ethyne (acetylene), ethene (ethylene), ethane, propyne (methyl acetylene), propadiene (allene), propene (propylene), cyclopropane and propane. The objectives were to test the theories of energy-loss distribution in this energy range and to see if the type of carbon bonding in a hydrocarbon molecule affects the shape of the distribution. Stopping powers and stopping cross sections were also measured at these energies and at 76.5 and 127.5 keV to determine effects of chemical binding. All of the measurements were made at the gas density required to give a 4 percent energy loss. The mean energy, second central moment (a measure of the width of the distribution), and the third central moment (a measure of the skew) were calculated from the measured energy-loss distributions. Stopping power values, calculated using the mean energy, compared reasonably well with those calculated from the Bethe stopping power theory. For the second and third central moments, the best agreement between measurement and theory was when the classical scattering probability was used for the calculations, but even these did not agree well. In all cases, variations were found in the data that could be correlated to the type of carbon binding in the molecule. The differences were statistically significant at a 99 percent confidence interval for the stopping powers and second central moments measured with 51 keV protons. Similar trends were noted at other energies and for the third central moment, but the differences were not statistically significant at the 99 percent confidence interval

Interferometric phase-contrast X-ray CT imaging of VX2 rabbit cancer at 35keV X-ray energy

Science.gov (United States)

Takeda, Tohoru; Wu, Jin; Tsuchiya, Yoshinori; Yoneyama, Akio; Lwin, Thet-Thet; Hyodo, Kazuyuki; Itai, Yuji

2004-05-01

Imaging of large objects at 17.7-keV low x-ray energy causes huge x-ray exposure to the objects even using interferometric phase-contrast x-ray CT (PCCT). Thus, we tried to obtain PCCT images at high x-ray energy of 35keV and examined the image quality using a formalin-fixed VX2 rabbit cancer specimen with 15-mm in diameter. The PCCT system consisted of an asymmetrically cut silicon (220) crystal, a monolithic x-ray interferometer, a phase-shifter, an object cell and an x-ray CCD camera. The PCCT at 35 keV clearly visualized various inner structures of VX2 rabbit cancer such as necrosis, cancer, the surrounding tumor vessels, and normal liver tissue. Besides, image-contrast was not degraded significantly. These results suggest that the PCCT at 35 KeV is sufficient to clearly depict the histopathological morphology of VX2 rabbit cancer specimen.

Chandra ACIS Sub-pixel Resolution

Science.gov (United States)

Kim, Dong-Woo; Anderson, C. S.; Mossman, A. E.; Allen, G. E.; Fabbiano, G.; Glotfelty, K. J.; Karovska, M.; Kashyap, V. L.; McDowell, J. C.

2011-05-01

We investigate how to achieve the best possible ACIS spatial resolution by binning in ACIS sub-pixel and applying an event repositioning algorithm after removing pixel-randomization from the pipeline data. We quantitatively assess the improvement in spatial resolution by (1) measuring point source sizes and (2) detecting faint point sources. The size of a bright (but no pile-up), on-axis point source can be reduced by about 20-30%. With the improve resolution, we detect 20% more faint sources when embedded on the extended, diffuse emission in a crowded field. We further discuss the false source rate of about 10% among the newly detected sources, using a few ultra-deep observations. We also find that the new algorithm does not introduce a grid structure by an aliasing effect for dithered observations and does not worsen the positional accuracy

Measurement of the 13C(α,n)16O reaction with the Trojan horse method: Focus on the sub threshold resonance at −3 keV

International Nuclear Information System (INIS)

La Cognata, M.; Spitaleri, C.; Guardo, G. L.; Puglia, S. M. R.; Romano, S.; Spartà, R.; Trippella, O.; Kiss, G. G.; Rogachev, G. V.; Avila, M.; Koshchiy, E.; Kuchera, A.; Santiago, D.; Mukhamedzhanov, A. M.; Lamia, L.

2014-01-01

The 13 C(α,n) 16 O reaction is the neutron source of the main component of the s-process. The astrophysical S(E)-factor is dominated by the −3 keV sub-threshold resonance due to the 6.356 MeV level in 17 O. Its contribution is still controversial as extrapolations, e.g., through R-matrix calculations, and indirect techniques, such as the asymptotic normalization coefficient (ANC), yield inconsistent results. Therefore, we have applied the Trojan Horse Method (THM) to the 13 C( 6 Li,n 16 O)d reaction to measure its contribution. For the first time, the ANC for the 6.356 MeV level has been deduced through the THM, allowing to attain an unprecedented accuracy. Though a larger ANC for the 6.356 MeV level is measured, our experimental S(E) factor agrees with the most recent extrapolation in the literature in the 140-230 keV energy interval, the accuracy being greatly enhanced thanks to this innovative approach, merging together two well establish indirect techniques, namely, the THM and the ANC

High-energy behavior of the double photoionization of helium from 2 to 12 keV

International Nuclear Information System (INIS)

Levin, J.C.; Sellin, I.A.; Johnson, B.M.; Lindle, D.W.; Miller, R.D.; Berrah, N.; Azuma, Y.; Berry, H.G.; Lee, D.

1993-01-01

We report the ratio of double-to-single photoionization of He at several photon energies from 2 to 12 keV. By time-of-flight methods, we find a ratio consistent with an asymptote at 1.5%±0.2%, essentially reached by hν∼4 keV. Fair agreement is obtained with older shake calculations of Byron and Joachain [Phys. Rev. 164, 1 (1967)], of Aberg [Phys. Rev. A 2, 1726 (1970)], and with recent many-body perturbation theory (MBPT) of Ishihara, Hino, and McGuire [Phys. Rev. A 44, 6980 (1991)]. The result lies below earlier MPBT calculations by Amusia et al. [J. Phys. B 8, 1248 (1975)] (2.3%), and well above semiempirical predictions of Samson [Phys. Rev. Lett. 65, 2861 (1990)], who expects no asymptote and predicts σ(He 2+ )/σ(He + )=0.3% at 12 keV

Measurement of the 232Th neutron capture cross section in the region 5 keV-150 keV

International Nuclear Information System (INIS)

Lobo, Georges; Corvi, Franco; Schillebeeckx, Peter; Brusegan, Antonio; Mutti, Paolo; Janeva, Natalia

2002-01-01

The average capture cross-section of 232 Th has been measured at the 14.37 m flight path of GELINA, IRMM-Geel, in the energy range from 5 to 150 keV. The capture events were detected by two C 6 D 6 liquid scintillators and the neutron flux was measured with a 10 B-loaded ionisation chamber. The data, corrected with the pulse-height weighting technique, have been normalised to the well-isolated and nearly saturated 232 Th (n, γ) resonances at 21.8 eV and 23.5 eV. Below 15 keV neutron energy, we do not observe the discrepancies, up to 40%, with the evaluated ENDF/B-VI data as reported by Wisshak et al.. Between 5 and 80 keV our results are about 10% systematically above the ENDF/B-VI data and approach the evaluated data between 80 and 100 keV. (author)

Hith resolution {beta}-spectroscopy of the isotope {sup 36}Cl using magnetic calorimeters; Entwicklung magnetischer Mikrokalorimeter fuer die hochaufloesende Spektroskopie des {beta}-Emitters {sup 36}Cl

Energy Technology Data Exchange (ETDEWEB)

Rotzinger, H.

2006-12-13

This thesis describes the development of a high resolution magnetic calorimeter for the detection of the {beta}-spectrum of the isotope {sup 36}Cl with endpoint energy of 709.6 keV. The temperature rise of a metallic paramagnetic sensor due to an energy deposition is sensed by measuring its magnetization using a sensitive DC-SQUID magnetometer. For a high detection efficiency an 4{pi} gold absorber was used. The heat capacity and the geometry of the absorber is optimally matched by a flat sensor and an optimized meander shaped readout coil. The fabrication of the superconducting structures and the detector setup are described. In addition, the relevant noise sources, the energy resolution and the quantum efficiency are discussed. A measured {sup 36}Cl-spectrum with an energy resolution of {delta}E{sub FWHM}=750 eV is presented and compared with existing experimental and theoretical data. (orig.)

High-resolution energetic particle measurements at 6.6R/sub E/ 3. Low-energy electron anisotropies and short-term substorm predictions

International Nuclear Information System (INIS)

Baker, D.N.; Higbie, P.R.; Hones, E.W. Jr.; Belian, R.D.

1978-01-01

Multiple detectors giving nearly complete 4π coverage of particle pitch angle distributions have provided high resolution measurements (in energy and time) of 30- to 300-keV electrons. Data from a spacecraft (1976-059A) in geostationary orbit show a remarkably consistent sequence of variations of the electron anisotropy before and during magnetospheric substorms. For periods typically 1--2 hours prior to the onset of substorms, electron distributions, peaked along the direction of the local magnetic field, are observed in the premidnight sector. These cigarlike anisotropies are accompanied by a local taillike magnetic field which may develop further during the event. At substorm onset an abrupt transition usually occurs from the cigar-shaped distributions to pancake-shaped distributions. This anisotropy sequence may be due to the buildup and subsequent release of stresses in the magnetotail; the cigar phase may also be due to associated processes at the dayside magnetopause causing a loss of 90 0 pitch angle particles. The present observations, based on approx.100 events, appear to provide a predictive tool for assessing the probability of occurrence of a substorm

Deactivation of group III acceptors in silicon during keV electron irradiation

International Nuclear Information System (INIS)

Sah, C.; Sun, J.Y.; Tzou, J.J.; Pan, S.C.

1983-01-01

Experimental results on p-Si metal-oxide-semiconductor capacitors (MOSC's) are presented which demonstrate the electrical deactivation of the acceptor dopant impurity during 8-keV electron irradiation not only in boron but also aluminum and indium-doped silicon. The deactivation rates of the acceptors during the 8-keV electron irradiation are nearly independent of the acceptor impurity type. The final density of the remaining active acceptor approaches nonzero values N/sub infinity/, with N/sub infinity/(B) Al--H>In-H. These deactivation results are consistent with our hydrogen bond model. The thermal annealing or regeneration rate of the deactivated acceptors in the MOSC's irradiated by 8-keV electron is much smaller than that in the MOSC's that have undergone avalanche electron injection, indicating that the keV electron irradiation gives rise to stronger hydrogen-acceptor bond

High pressure Moessbauer spectrometer for the high-resolution 93.3 keV resonance in 67Zn

International Nuclear Information System (INIS)

Adlassnig, W.; Potzel, W.; Moser, J.; Schaefer, C.; Steiner, M.; Kalvius, G.M.

1989-01-01

A high pressure, low temperature Moessbauer spectrometer for the high-resolution 93.3 keV resonance in 67 Zn is described. The pressure is generated by applying the opposed anvil technique. Using B 4 C anvils and a sandwich gasket quasihydrostatic pressures up to 6 GPa were obtained for the required large samples of 7 mm diameter and 2 mm thickness. The piezoelectric Doppler drive is mounted on top of the pressure clamp. The whole system can be cooled to liquid He temperatures. The spectrometer was used to investigate at 4.2 K the pressure dependence of the Moessbauer parameters of Zn metal. (orig.)

Development of a metallic magnetic calorimeter for high resolution spectroscopy

International Nuclear Information System (INIS)

Linck, M.

2007-01-01

In this thesis the development of a metallic magnetic calorimeter for high resolution detection of single x-ray quanta is described. The detector consists of an X-ray absorber and a paramagnetic temperature sensor. The raise in temperature of the paramagnetic sensor due to the absorption of a single X-ray is measured by the change in magnetization of the sensor using a low-noise SQUID magnetometer. The thermodynamic properties of the detector can be described by a theoretical model based on a mean field approximation. This allows for an optimization of the detector design with respect to signal size. The maximal archivable energy resolution is limited by thermodynamic energy fluctuations between absorber, heat bath and thermometer. An interesting field of application for a metallic magnetic calorimeter is X-ray astronomy and the investigation of X-ray emitting objects. Through high-resolution X-ray spectroscopy it is possible to obtain information about physical processes of even far distant objects. The magnetic calorimeter that was developed in this thesis has a metallic absorber with a quantum efficiency of 98% at 6 keV. The energy resolution of the magnetic calorimeter is EFWHM=2.7 eV at 5.9 keV. The deviation of the detector response from a linear behavior of the detector is only 0.8% at 5.9 keV. (orig.)

Measurement of the fission cross section of uranium-235 between 4 eV and 20 keV; Mesure de la section efficace de fission de l'uranium-235 entre 4 eV et 20 keV

Energy Technology Data Exchange (ETDEWEB)

Michaudon, A; Genin, R; Joly, R; Vendryes, G

1959-01-01

The neutron fission cross section of uranium-235 has been measured between 4 ev and 20 kev by the time of flight method with the Saclay electron linear accelerator as a pulsed neutron source. After a brief description of the experimental apparatus and the conditions of work during the experiment, the curve {sigma}{sub F} {radical}E in the energy range studied is shown. This curve is then analyzed by the ''area'' method and a set of {sigma}{sub 0} {gamma}{sub F} values is obtained. With {sigma}{sub 0} {gamma} values measured in other laboratories, it is possible to compute fission widths for several resonances and to study their distribution. This distribution is then compared to Porter-Thomas distributions with different values of the number of exit channels. (authors) [French] La section efficace de fission de l'uranium--235 a ete mesuree entre 4 eV et 20 KeV par la methode du temps de vol en utilisant l'accelerateur lineaire a electrons de Saclay comme source pulses de neutrons. Apres une rapide description de l'appareillage experimental et des conditions de fonctionnement au cours de l'experience, on presente la courbe {sigma}{sub F} {radical}E obtenue dans la game d'energie etudiee. Cette courbe est ensuite analysee par la methode de surface des resonances et un lot de valeurs de {sigma}{sub 0} {gamma}{sub F} est obtenue. Conjuguee avec les valeurs de {sigma}{sub 0} {gamma} obtenues dans d'autres laboratoires, cette analyse permet de calculer les largeurs de fission pour plusieurs resonances et d'etudier leur distribution. Cette distribution est ensuite comparee aux distributions de Porter et Thomas correspondant a differentes valeurs du nombre de voies de sortie. (auteurs)

Some rules to improve the energy resolution in alpha liquid scintillation with beta rejection

CERN Document Server

Aupiais, J; Dacheux, N

2003-01-01

Two common scintillating mixtures dedicated to alpha measurements by means of alpha liquid scintillation with pulse shape discrimination were tested: the di-isopropylnaphthalene - based and the toluene-based solvents containing the commercial cocktails Ultima Gold AB trademark and Alphaex trademark. We show the possibility to enhance the resolution up to 200% by using no-water miscible cocktails and by reducing the optical path. Under these conditions, the resolution of about 200 keV can be obtained either by the Tri Carb sup T sup M or by the Perals sup T sup M spectrometers. The time responses, e.g., the time required for a complete energy transfer between the initial interaction alpha particle-solvent and the final fluorescence of the organic scintillator, have been compared. Both cocktails present similar behavior. According to the Foerster theory, about 6-10 ns are required to complete the energy transfer. For both apparatus, the detection limits were determined for alpha emitters. The sensitivity of the...

Mean free paths by inelastic interactions, stopping powers, and energy straggling for electrons of energies up to 20 keV in various solids

International Nuclear Information System (INIS)

Akkerman, A.F.; Chernov, G.Ya.

1978-01-01

For the elements C, Be, Mg, Al, Si, K, Ge, Sb, Bi calculations of the mean free paths and stopping powers of low energy electrons are performed. In the computational model Lindhard's formalism of the dielectric response function for pair and plasmon excitation and the classical cross-section for ionization processes are used. Anomalously high mean free paths and small stopping powers in potassium are found. This behaviour which is connected with low electron concentration in the valence band is expected to hold for all alkali metals. For energies above 10 keV the calculated dE/dx agree well with values calculated from the Bethe-Bloch formula. A Monte-Carlo method is used for the calculation of the energy loss distribution of electrons passing through thin targets. It is noted that Blunck-Leisegang's theory fails to render the energy straggling at electron energies below 10 keV. (author)

Tuning of wettability of PANI-GNP composites using keV energy ions

Energy Technology Data Exchange (ETDEWEB)

Lakshmi, G.B.V.S., E-mail: lakshmigbvs@gmail.com [Inter University Accelerator Centre, New Delhi 67 (India); Avasthi, D.K. [Amity University, Noida 201313, Uttar Pradesh (India)

2016-07-15

Polyaniline nanofiber composites with various nanomaterials have several applications in electrochemical biosensors. The surface properties of these composites coated electrodes play crucial role in enzyme absorption and analyte detection process. In the present study, Polyaniline-Graphene nanopowder (PANI-GNP) composites were prepared by rapid-mixing polymerization method. The films were prepared on ITO coated glass substrates and irradiated with 42 keV He{sup +} ions produced by indigenously fabricated accelerator at IUAC, New Delhi. The films were characterized before and after irradiation by SEM, Raman spectroscopy and contact angle measurements. The as-prepared films show superhydrophilic nature and after irradiation the films show highly hydrophobic nature with water contact angle (135°). The surface morphology was studied by SEM and structural changes were studied by Raman spectra. The surface morphological modifications induced by keV energy ions helps in tuning the wettability at different ion fluences.

Results from a 64-pixel PIN-diode detector system for low-energy beta-electrons

Energy Technology Data Exchange (ETDEWEB)

Wuestling, Sascha, E-mail: sascha.wuestling@kit.ed [Forschungszentrum Karlsruhe, Institut fuer Prozessdatenverarbeitung und Elektronik, Postfach 3640, 76021 Karlsruhe (Germany); Fraenkle, F.; Habermehl, F.; Renschler, P. [Universitaet Karlsruhe - TH, Institut fuer Experimentelle Kernphysik, Postfach 6980, 76128 Karlsruhe (Germany); Steidl, M [Forschungszentrum Karlsruhe, Institut fuer Kernphysik, Postfach 3640, 76021 Karlsruhe (Germany)

2010-12-11

The KATRIN neutrino mass experiment is based on a precise energy measurement ({Delta}E/E=5x10{sup -5}) of electrons emerging from tritium beta decay (E{sub max}=18.6 keV). This is done by a large electrostatic retarding spectrometer (MAC-E Filter), which is followed by an electron detector. Key requirements for this detector are a large sensitive area ({approx}80 cm{sup 2}), a certain energy resolution ({Delta}E=600 eV - 18.6 keV) but also a certain spatial resolution ({approx}3 mm), which leads to a multi-pixel design. As a tentative design on the way to the final detector, but also for operational service on the so-called pre-spectrometer experiment, a detector system with a reduced size (16 cm{sup 2}) and a reduced pixel number (64), making use of a monolithic segmented silicon PIN diode, was designed and built. While the design and very first measurements have been presented in Wuestling et al. , this publication shows the operational performance of the detector system. The robust concept of the electronics allowed adaptation to mechanically different experimental setups. The spacial resolution of the detector system proved to be essential in examining Penning trap induced background and other effects in the pre-spectrometer experiment. The detector performance test runs include energy resolution and calibration, background rates, correlation between pixels (crosstalk), spatially resolved rate analysis, and a dead-layer measurement . The detector allows for background searches with a sensitivity as low as 1.3x10{sup -3} cps/cm{sup 2} in the energy range of 20 keV. This allows the pre-spectrometer to be characterized with e-gun illumination with a signal to background ratio of better than 10{sup 5} and the search for ultra low Penning discharge emissions.

Cross section for induced L X-ray emission by protons of energy <400 keV

International Nuclear Information System (INIS)

Mohan, Harsh; Jain, Arvind Kumar; Kaur, Mandeep; Singh, Parjit S.; Sharma, Sunita

2014-01-01

In performing ion beam analysis, cross section for induced L X-ray emission plays a crucial role. There are different approaches by which these can be found experimentally or can be calculated theoretically based on various models. L X-ray production cross sections for Bi with protons in the energy range 260–400 keV at the interval of 20 keV are measured. These are compared with calculations obtained on the basis of current prevailing theories ECPSSR and ECPSSR-UA. Their importance in understanding this phenomenon and existing arguments in this regard will be highlighted

Energy resolution measurements of LaBr3:Ce scintillating crystals with an ultra-high quantum efficiency photomultiplier tube

International Nuclear Information System (INIS)

Pani, R.; Cinti, M.N.; Scafe, R.; Pellegrini, R.; Vittorini, F.; Bennati, P.; Ridolfi, S.; Lo Meo, S.; Mattioli, M.; Baldazzi, G.; Pisacane, F.; Navarria, F.; Moschini, G.; Boccaccio, P.; Orsolini Cencelli, V.; Sacco, D.

2009-01-01

The performance of the new prototype of high quantum efficiency PMT (43% at 380 nm), Hamamatsu R7600U-200, was studied coupled to a LaBr 3 :Ce crystal with the size of o12.5 mmx12.5 mm. The energy resolution results were compared with ones from two PMTs, Hamamatsu R7600U and R6231MOD, with 22% and 30% quantum efficiency (QE), respectively. Moreover, the photodetectors were equipped with tapered and un-tapered voltage dividers to study the non-linearity effects on pulse height distribution, due to very high peak currents induced in the PMT by the fast and intense light pulse of LaBr 3 :Ce. The results show an energy resolution improvement with UBA PMT of about 20%, in the energy range of 80-662 keV, with respect to the BA one.

Improving depth resolutions in positron beam spectroscopy by concurrent ion-beam sputtering

Science.gov (United States)

John, Marco; Dalla, Ayham; Ibrahim, Alaa M.; Anwand, Wolfgang; Wagner, Andreas; Böttger, Roman; Krause-Rehberg, Reinhard

2018-05-01

The depth resolution of mono-energetic positron annihilation spectroscopy using a positron beam is shown to improve by concurrently removing the sample surface layer during positron beam spectroscopy. During ion-beam sputtering with argon ions, Doppler-broadening spectroscopy is performed with energies ranging from 3 keV to 5 keV allowing for high-resolution defect studies just below the sputtered surface. With this technique, significantly improved depth resolutions could be obtained even at larger depths when compared to standard positron beam experiments which suffer from extended positron implantation profiles at higher positron energies. Our results show that it is possible to investigate layered structures with a thickness of about 4 microns with significantly improved depth resolution. We demonstrated that a purposely generated ion-beam induced defect profile in a silicon sample could be resolved employing the new technique. A depth resolution of less than 100 nm could be reached.

Calibration of PM-355 nuclear track detectors for low-energy deuterons

International Nuclear Information System (INIS)

Malinowski, K.; Skladnik-Sadowska, E.; Sadowski, M.J.; Czaus, K.

2008-01-01

A dependence of track diameters on deuteron energy was investigated for PM-355 nuclear track detectors. Deuteron streams were obtained from RPI-IBIS facility at the pulsed injection of deuterium. Mass and energy analysis was performed with a Thomson-type spectrometer and PM-355 samples. An etched deuteron parabola extended from about 20 keV to about 500 keV. The energy resolution of measurements on the parabola at 20 keV was ±0.2keV, and at 500 keV amounted to ±50keV. Accuracy of the determination of deuteron energies decreased for higher energy values. Results are presented in diagrams showing the track diameters as a function of deuteron energy for chosen etching times (1-8 h)

Analysis of dependence of fission cross section and angular anisotropy of the 235U fission fragment escape induced by neutrons of intermediate energies (epsilon < or approximately200 keV) on target nucleus orientation

International Nuclear Information System (INIS)

Barabanov, A.L.

1985-01-01

Experimental data on dependence of fission cross section Σsub(f) (epsilon) and angular anisotropy W(epsilon, 0 deg)/W(epsilon, 90 deg) of sup(235)U fission fragment escape by neutrons with energy epsilon=100 and 200 keV on orientation of target nuclei are analyzed. 235 U (Isup(πsub(0))=7/2sup(-)) nuclei were orientated at the expense of interaction of quadrupole nucleus momenta with nonuniform electric field of uranyl-rubidium nitrate crystal at crystal cooling to T=0.2 K. The analysis was carried out with three different sets of permeability factors T(epsilon). Results of the analysis weakly depend on T(epsilon) choice. It is shown that a large number of adjusting parameters (six fissionabilities γsup(f)(Jsup(π), epsilon) and six momenta sub(Jsup(π))) permit to described experimental data on Σsub(f)(epsilon) and W(epsilon, 0 deg)/W(epsilon, 90 deg), obtained at epsilon=200 keV by introducing essential dependence of γsup(f)(Jsup(π), epsilon) and sub(Jsup(π)) on Jsup(π). Estimations of fission cross sections Σsub(f)(epsilon) and angular distribution W(epsilon, n vector) up to T approximately equal to 0.01 K in two geometries of the experiment: the orientation axis is parallel and perpendicular to momentum direction p vector of incident neutrons, are conducted

Structural investigations of interfaces in Fe{sub 90}Sc{sub 10} nanoglasses using high-energy x-ray diffraction

Energy Technology Data Exchange (ETDEWEB)

Ghafari, M.; Gleiter, H.; Feng, T. [Karlsruhe Institute of Technology (KIT), Institute for Nanotechnology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Kohara, S. [Research and Utilization Division, Japan Synchrotron Radiation Research Institute/SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Hahn, H.; Witte, R. [Karlsruhe Institute of Technology (KIT), Institute for Nanotechnology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); KIT-TUD Joint Research Laboratory Nanomaterials, Technische Universitaet Darmstadt, Petersenstr. 32, 64287 Darmstadt (Germany); Kamali, S. [Department of Chemistry, University of California, One Shields Ave., Davis, California 95616 (United States)

2012-03-26

High-resolution diffraction experiments of Fe{sub 90}Sc{sub 10} nanoglasses and rapidly quenched metallic glasses as reference materials have been performed using high-energy x-rays with a wavelength of 0.21 Angst from a synchrotron radiation source. Nanoglasses are amorphous alloys with a significant fraction of interfaces on the nanometer scale. The short- and intermediate-range orders of a nanoglass are different from the well known amorphous materials produced by rapid quenching from the melt. These structural modifications have significant influence on the physical properties. In this paper, the short- and intermediate-range orders of the nanoglass Fe{sub 90}Sc{sub 10} and the reference metallic glass Fe{sub 90}Sc{sub 10} alloy prepared by rapid quenching are discussed.

Energy development and CO<sub>2sub> emissions in China

Energy Technology Data Exchange (ETDEWEB)

Xi, Xiaolin [Carnegie-Mellon Univ., Pittsburgh, PA (United States)

1993-03-01

The objective of this research is to provide a better understanding of future Chinese energy development and CO<sub>2sub> emissions from burning fossil fuels. This study examines the current Chinese energy system, estimates CO<sub>2sub> emissions from burning fossil fuels and projects future energy use and resulting CO<sub>2sub> emissions up to the year of 2050. Based on the results of the study, development strategies are proposed and policy implications are explored. This study first develops a Base scenario projection of the Chinese energy development based upon a sectoral analysis. The Base scenario represents a likely situation of future development, but many alternatives are possible. To explore this range of alternatives, a systematic uncertainty analysis is performed. The Base scenario also represents an extrapolation of current policies and social and economic trends. As such, it is not necessarily the economically optimal future course for Chinese energy development. To explore this issue, an optimization analysis is performed. For further understanding of developing Chinese energy system and reducing CO<sub>2sub> emissions, a Chinese energy system model with 84 supply and demand technologies has been constructed in MARKAL, a computer LP optimization program for energy systems. Using this model, various technological options and economic aspects of energy development and CO<sub>2sub> emissions reduction in China during the 1985-2020 period are examined.

Definition of the absolute energy of beam particles from tandem EGP-10K by means of gamma-spectrometry

CERN Document Server

Goryunov, O Y; Mozhzhukhyin, E M

2003-01-01

The attachment of absolute energy of proton beam from tandem EGP-10K to the nuclear magnetic resonance (NMR) frequency of field device put in rotated magnet-analyzer SP-88 has been made. The determination of beam energy was made with the aid of sup 8 sup 9 Y(p, n) sup 8 sup 9 Zr reaction, where the threshold is 3656 keV. 587 keV level from decay of sup 8 sup 9 Zr was used for identification of the reaction. It was determined that NMR frequency f = 16253,5 sup + sup 4 sup , sup 8 sub - sub 8 sub , sub 3 Kc/s corresponds to 4272 KeV proton energy.

Memory effect, resolution, and efficiency measurements of an Al{sub 2}O{sub 3} coated plastic scintillator used for radioxenon detection

Energy Technology Data Exchange (ETDEWEB)

Bläckberg, L., E-mail: lisa.blackberg@physics.uu.se [Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala (Sweden); Fritioff, T.; Mårtensson, L.; Nielsen, F.; Ringbom, A. [Division of Defence and Security Systems, Swedish Defence Research Agency (FOI), SE-17290 Stockholm (Sweden); Sjöstrand, H.; Klintenberg, M. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala (Sweden)

2013-06-21

A cylindrical plastic scintillator cell, used for radioxenon monitoring within the verification regime of the Comprehensive Nuclear-Test-Ban Treaty, has been coated with 425 nm Al{sub 2}O{sub 3} using low temperature Atomic Layer Deposition, and its performance has been evaluated. The motivation is to reduce the memory effect caused by radioxenon diffusing into the plastic scintillator material during measurements, resulting in an elevated detection limit. Measurements with the coated detector show both energy resolution and efficiency comparable to uncoated detectors, and a memory effect reduction of a factor of 1000. Provided that the quality of the detector is maintained for a longer period of time, Al{sub 2}O{sub 3} coatings are believed to be a viable solution to the memory effect problem in question.

X-ray attenuation coefficients and photoelectric cross sections of Cu, Fe and Sn for the energy range 3-29 KeV

International Nuclear Information System (INIS)

Wang Dachun; Yang Hua; Luo Pingan; Ding Xunliang; Wang Xinfu; Zhou Hongyu; Shen Xinyin; Zhu Guanghua

1991-08-01

The document contains the following two papers: X-ray attenuation coefficient and photoelectric cross sections of Sn for the Energy Range 3.3 KeV to 29.1 KeV - by Wang Dachun, Yang Hua and Luo Pingan. X-ray attenuation coefficients and photoelectric cross sections of Cu and Fe for the range 3 KeV to 29 KeV - by Wang Dachun, Ding Xunliang, Wang Xinfu, Yang Hua, Zhou Hongyu, Shen Xinyin and Zhu Guanghua. A separate abstract was prepared for each of these papers. Refs, figs and tabs

Slowing down of 100 keV antiprotons in Al foils

Science.gov (United States)

Nordlund, K.

2018-03-01

Using energy degrading foils to slow down antiprotons is of interest for producing antihydrogen atoms. I consider here the slowing down of 100 keV antiprotons, that will be produced in the ELENA storage ring under construction at CERN, to energies below 10 keV. At these low energies, they are suitable for efficient antihydrogen production. I simulate the antihydrogen motion and slowing down in Al foils using a recently developed molecular dynamics approach. The results show that the optimal Al foil thickness for slowing down the antiprotons to below 5 keV is 910 nm, and to below 10 keV is 840 nm. Also the lateral spreading of the transmitted antiprotons is reported and the uncertainties discussed.

Mass attenuation and mass energy absorption coefficients for 10 keV to 10 MeV photons; Coefficients d'attenuation massique et d'absorption massique en energie pour les photons de 10 keV a 10 MeV

Energy Technology Data Exchange (ETDEWEB)

Joffre, H; Pages, L [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-07-01

In this report are given the elements allowing the definition of the values of mass attenuation coefficients and mass energy absorption coefficients for some elements and mixtures, necessary for the study of tissue equivalent materials, for photons in the energy range 10 keV to 10 MeV. After a short reminding of the definitions of the two coefficients, follows, in table form, a compilation of these coefficients, as a function of energy, for simple elements, for certain mineral compounds, organic compounds, gases and particularly of soft tissues. (author) [French] Dans ce rapport, sont donnes les elements permettant de determiner les valeurs des coefficients d'attenuation massique et d'absorption massique en energie pour certains elements et melanges necessaires a l'etude des materiaux equivalents aux tissus pour les photons dans le domaine d'energie allant de 10 keV a 10 MeV. Apres un bref rappel des definitions des deux coefficients, suit, sous forme de tableaux, un recueil de ces coefficients, en fonction de l'energie, pour les elements simples, certains composes mineraux, composes organiques, gaz, et, particulierement, pour les tissus mous. (auteur)

Study of the secondary electron emission during bombardment of metal targets by positive D{sup +} and D{sub 2}{sup +} ions (1960); Etude de l'emission secondaire d'electrons au cours du bombardement de cibles metalliques par des ions positifs D{sup +} et D{sub 2}{sup +} (1960)

Energy Technology Data Exchange (ETDEWEB)

Leroy, J [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires; Prelec, K [Institut Rudjer Boskovic, Zagreb (Croatia)

1960-07-01

The secondary electron yield {gamma}-bar due to primary positive ions D{sup +} and D{sup +}{sub 2} has been measured in the 70 keV to 300 keV ion energy range. Several metallic targets have been used. The variation of this yield with the angle of incidence is proportional to sec {theta} where {theta} is the angle between the beam of primary ions and the normal to the target surface. The values {gamma}-bar decrease for increasing energy ions. At a given energy all the targets tried gave approximately the same electron yield. (author) [French] Le facteur d'emission secondaire a ete mesure pour des ions positifs D{sup +} et D{sup +}{sub 2} ayant une energie comprise entre 70 keV et 300 keV, sur differentes cibles metalliques. La variation de ce facteur avec l'angle d'incidence suit une loi de la forme {gamma}{sub 0} sec {theta}, {theta} etant l'angle entre le faisceau et la normale a la cible. Les valeurs de {gamma}-bar trouvees decroissent lorsque l'energie des ions incidents augmente, mais sont assez voisines les unes des autres, a une energie donnee, pour les differentes cibles essayees. (auteur)

A detection system for very low-energy protons from {beta}-delayed proton decay

Energy Technology Data Exchange (ETDEWEB)

Spiridon, A.; Pollacco, E.; Trache, L.; Simmons, E.; McCleskey, M.; Roeder, B. T.; Tribble, R. E.; Pascovici, G.; Riallot, M.; Mols, J. P.; Kebbiri, M. [Cyclotron Institute, Texas A and M University, College Station, TX 77843-3366 (United States); CEA/IRFU Saclay, Gif-sur-Yvette (France); Cyclotron Institute, Texas A and M University, College Station, TX 77843-3366 (United States); Institut fuer Kernphysik der Universitaet zu Koeln, D-50937 Koeln (Germany); CEA/IRFU Saclay, Gif-sur-Yvette (France)

2012-11-20

We have recently developed a gas based detection system called AstroBox, motivated by nuclear astrophysics studies. The goal was to detect very low-energy protons from {beta}-delayed p-decay with reduced beta background and improved energy resolution. The detector was tested using the {beta}-delayed proton-emitter 23Al previously studied with a set-up based on thin double-sided Si strip detectors. The proton spectrum obtained with AstroBox showed no beta background down to {approx}80 keV. The low energy (206 keV, 267 keV) proton peaks were positively identified, well separated, and the resolution was improved.

A detection system for very low-energy protons from β-delayed proton decay

International Nuclear Information System (INIS)

Spiridon, A.; Pollacco, E.; Trache, L.; Simmons, E.; McCleskey, M.; Roeder, B. T.; Tribble, R. E.; Pascovici, G.; Riallot, M.; Mols, J. P.; Kebbiri, M.

2012-01-01

We have recently developed a gas based detection system called AstroBox, motivated by nuclear astrophysics studies. The goal was to detect very low-energy protons from β-delayed p-decay with reduced beta background and improved energy resolution. The detector was tested using the β-delayed proton-emitter 23Al previously studied with a set-up based on thin double-sided Si strip detectors. The proton spectrum obtained with AstroBox showed no beta background down to ∼80 keV. The low energy (206 keV, 267 keV) proton peaks were positively identified, well separated, and the resolution was improved.

Secondary ion emission from metal surfaces bombarded by 0.5-10 keV protons and hydrogens

International Nuclear Information System (INIS)

Kitamura, Akira; Yano, Syukuro

1978-01-01

Secondary ion emission coefficients by bombardment of 0.5 - 10 keV protons K 11 and atomic hydrogens K 01 on copper, stainless steel, molybdenum and evaporated gold surfaces have been measured in a moderate vacuum. Results are summarized as follows; 1) There is no significant difference between K 11 and K 01 . 2) Differences in K 11 and K 11 between different samples of the same material and between the sample before baking-out and the same sample after baking-out are of the order of several tens of percent. 3) The incident particle energy E sub(max) at which K 11 and K 01 have the maximum value lies in the keV region, and increases with the target mass. According to the fact that E sub(max) differs substantially from the energy at which the elastic stopping power has the maximum value, a characteristic length l is introduced and calculated to be of the order of hundreds of A; the factor exp (-x/l) represents the degree of contribution of collision at depth x to K 11 or K 01 . (author)

Electron Flux Models for Different Energies at Geostationary Orbit

Science.gov (United States)

Boynton, R. J.; Balikhin, M. A.; Sibeck, D. G.; Walker, S. N.; Billings, S. A.; Ganushkina, N.

2016-01-01

Forecast models were derived for energetic electrons at all energy ranges sampled by the third-generation Geostationary Operational Environmental Satellites (GOES). These models were based on Multi-Input Single-Output Nonlinear Autoregressive Moving Average with Exogenous inputs methodologies. The model inputs include the solar wind velocity, density and pressure, the fraction of time that the interplanetary magnetic field (IMF) was southward, the IMF contribution of a solar wind-magnetosphere coupling function proposed by Boynton et al. (2011b), and the Dst index. As such, this study has deduced five new 1 h resolution models for the low-energy electrons measured by GOES (30-50 keV, 50-100 keV, 100-200 keV, 200-350 keV, and 350-600 keV) and extended the existing >800 keV and >2 MeV Geostationary Earth Orbit electron fluxes models to forecast at a 1 h resolution. All of these models were shown to provide accurate forecasts, with prediction efficiencies ranging between 66.9% and 82.3%.

Sub-Angstrom Atomic-Resolution Imaging of Heavy Atoms to Light Atoms

Energy Technology Data Exchange (ETDEWEB)

O' Keefe, Michael A.; Shao-Horn, Yang

2003-05-23

Three decades ago John Cowley and his group at ASU achieved high-resolution electron microscope images showing the crystal unit cell contents at better than 4Angstrom resolution. Over the years, this achievement has inspired improvements in resolution that have enabled researchers to pinpoint the positions of heavy atom columns within the cell. More recently, this ability has been extended to light atoms as resolution has improved. Sub-Angstrom resolution has enabled researchers to image the columns of light atoms (carbon, oxygen and nitrogen) that are present in many complex structures. By using sub-Angstrom focal-series reconstruction of the specimen exit surface wave to image columns of cobalt, oxygen, and lithium atoms in a transition metal oxide structure commonly used as positive electrodes in lithium rechargeable batteries, we show that the range of detectable light atoms extends to lithium. HRTEM at sub-Angstrom resolution will provide the essential role of experimental verification for the emergent nanotech revolution. Our results foreshadow those to be expected from next-generation TEMs with Cs-corrected lenses and monochromated electron beams.

Calculation of W for low energy electrons in tissue-equivalent gas. [<10 keV

Energy Technology Data Exchange (ETDEWEB)

Dayashankar, [Bhabha Atomic Research Centre, Bombay (India). Div. of Radiation Protection

1977-11-01

The mean energy expended per ion pair formed (W-value) in the tissue-equivalent gas for incident electrons of energy up to 10 keV has been calculated in the continuous slowing-down approximation. The effect of secondary and tertiary electrons has been considered by utilizing recent measurements of Opal et al., (1971, J. Chem. Phys., 55,4100) on the energy spectra of low-energy secondary electrons and the Mott formula for the spectra of high-energy secondaries. The results, which are provisional in nature due to the limitations on the accuracy of the input cross-section data and the neglect of the discrete nature of energy loss process, are compared with the available measurements.

Detectors for high resolution dynamic pet

International Nuclear Information System (INIS)

Derenzo, S.E.; Budinger, T.F.; Huesman, R.H.

1983-05-01

This report reviews the motivation for high spatial resolution in dynamic positron emission tomography of the head and the technical problems in realizing this objective. We present recent progress in using small silicon photodiodes to measure the energy deposited by 511 keV photons in small BGO crystals with an energy resolution of 9.4% full-width at half-maximum. In conjunction with a suitable phototube coupled to a group of crystals, the photodiode signal to noise ratio is sufficient for the identification of individual crystals both for conventional and time-of-flight positron tomography

L X-ray fluorescence cross sections experimentally determined for elements with 45keV

Energy Technology Data Exchange (ETDEWEB)

Bonzi, Edgardo V., E-mail: bonzie@famaf.unc.edu.ar [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria-5010, Cordoba (Argentina); Badiger, Nagappa M. [Departments of Physics, Karnatak University, Dharwad 580 003, Karnataka (India); Grad, Gabriela B. [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria-5010, Cordoba (Argentina); Barrea, Raul A. [The Biophysics Collaborative Access Team (BioCAT), Dept of Biological Chemical, and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616 (United States); Figueroa, Rodolo G. [Departamento de Cs. Fisicas, Universidad de La Frontera, Temuco (Chile)

2012-04-15

Experimental determination of L fluorescence cross-sections for elements with 45keV using Synchrotron radiation. This work is part of an investigation we did at low energies in the same group of elements. The individual L X-ray photons, Ll, L{alpha}, L{beta}{sub I}, L{beta}{sub II}, L{gamma}{sub {Iota}} and L{gamma}{sub {Iota}{Iota}} produced in the target were measured using a Si(Li) detector. The experimental set-up provided a low background by using linearly polarized monoenergetic photon beam, improving the signal-to-noise ratio. The experimental cross sections obtained in this work were compared with data calculated using coefficients from , , and Scofield and Puri et al. (1993, 1995) - Highlights: Black-Right-Pointing-Pointer Experimental data of L fluorescence cross-sections with 45keV by Synchrotron radiation. Black-Right-Pointing-Pointer The cross sections Ll, L{alpha}, L{beta}{sub I}, L{beta}{sub II}, L{gamma}{sub {Iota}} and L{gamma}{sub {Iota}{Iota}} obtained, were compared with calculated data. Black-Right-Pointing-Pointer The Hypermet function was used to fit the data, because it considers a tail on the left side of the peak. Black-Right-Pointing-Pointer The tail is relevant when a small peak has another one on the right side with a big area.

Metallic magnetic calorimeters for high resolution X-ray spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Krantz, M.; Hengstler, D.; Geist, J.; Schoetz, C.; Hassel, K.; Hendricks, S.; Keller, M.; Kempf, S.; Gastaldo, L.; Fleischmann, A.; Enss, C. [Heidelberg Univ. (Germany). KIP

2015-07-01

We develop microfabricated, energy dispersive particle detector arrays based on metallic magnetic calorimeters (MMCs) for high resolution X-ray spectroscopy to challenge bound-state QED calculations. Our MMCs are operated at about T=30 mK and use a paramagnetic temperature sensor, read-out by a SQUID, to measure the energy deposited by single X-ray photons. We discuss the physics of MMCs, the detector performance and the cryogenic setups for two different detector arrays. We present their microfabrication layouts with focus on challenges like the heatsinking of each pixel of the detector and the overhanging absorbers. The maXs-20 detector is a linear 1x8-pixel array with excellent linearity in its designated energy range up to 20 keV and unsurpassed energy resolution of 1.6 eV for 6 keV x-rays. MaXs-20 operated in a highly portable pulse tube cooled ADR setup has already been used at the EBIT facilities of the MPI-K for new reference measurements of V-like and Ti-like tungsten. The maXs-30 detector currently in development is a 8x8-pixel 2d-array with an active detection area of 16 mm{sup 2} and is designed to detect X-rays up to 50 keV with a designated energy resolution below 5 eV. MaXs-30 will be operated in a cryogen free 3He/4He-dilution refrigerator at the tip of a 40 cm long cold finger at T=20 mK.

Use of Peltier cells in high resolution alpha spectrometry

International Nuclear Information System (INIS)

Bueno, C.C.; Santos, M.D.S.; Goncalves, J.A.C.

1994-01-01

The experiments with low-cost commercial silicon PIN photodiodes have shown the possibility of their transformation for use as alpha detectors with performance comparable with surface barrier detectors which are more expensive. Utilizing the silicon photodiode with reverse bias, an energy resolution for 241 Am alpha particles of 28 KeV and 23 KeV were obtained at room temperature and at -30 0 C respectively. (author). 4 refs, 4 figs

De-excitation gamma-ray technique for improved resolution in intermediate energy photonuclear reactions

International Nuclear Information System (INIS)

Kuzin, A.; Thompson, M.N.; Rassool, R.; Adler, J.O.; Fissum, K.; Issaksson, L.; Ruijter, H.; Schroeder, B.; Annand, J.R.M.; McGeorge, J.C.; Crawford, G.I.; Gregel, J.

1997-01-01

The 12 C (γ,p) reaction was studied. The experiment was done at the MAX Laboratory of Lund University, using tagged photons with energy between 50 and 70 MeV and natural carbon targets. It has been possible to detect γ-ray emitted from the residual nucleus, in coincidence with photoprotons leading to the excited residual state. The 200 KeV gamma-ray resolution permitted the identification of the residual states and allowed off-line cuts to be made in order to identify the excitation region in 11 B from what particular de-excitation gamma-ray were seen. 9 refs., 1 tab., 3 figs

Testing the E(sub peak)-E(sub iso) Relation for GRBs Detected by Swift and Suzaku-WAM

Science.gov (United States)

Krimm, H. A.; Yamaoka, K.; Sugita, S.; Ohno, M.; Sakamoto, T.; Barthelmy, S. D.; Gehrels, N.; Hara, R.; Onda, K.; Sato, G.;

Characteristic and non-characteristic X-ray yields produced from thick Ti element by sub-relativistic electrons

International Nuclear Information System (INIS)

Yadav, Namita; Kumar, Sunil; Bhatt, Pragya; Singh, Raj; Singh, B.K.; Shanker, R.

2012-01-01

Highlights: ► The X-ray spectra of a thick Ti element by 10–25 keV electron impact are obtained. ► Measured Ti K α yields are found to be in good agreement with PWBA theory. ► Doubly differential bremsstrahlung yields agree reasonably with MC simulation. ► Average value of the ratio K α /(K α + K β ) of Ti is found to be 0.881 ± 0.003. -- Abstract: Measurements are performed to study the electron impact energy dependence of doubly differential bremsstrahlung yields (DDBY) and of characteristic Ti K α line yields produced from sub-relativistic electrons (10–25 keV) colliding with a thick Ti (Z = 22) target. The emitted radiation is detected by a Si-PIN photo-diode detector with energy resolution (FWHM) of 180 eV at 5.9 keV. The measured data of DDBY are compared with the results predicted by Monte-Carlo (MC) simulations using the general purpose PENELOPE code. A reasonable agreement is found between experimental and simulation results within the experimental uncertainty of measurements of 12%. Characteristic Ti K α yields are obtained for the considered impact energy range and they are compared with the existing theoretical results. A good agreement is found between the present measurements and the theoretical calculations. Furthermore, data are presented for impact energy dependence of the ratio K α /(K α + K β ) of a thick Ti target under impact of 10–25 keV electrons. The ratio shows a very weak dependence on impact energy in the studied range. The average value of the ratio is found to be 0.881 ± 0.003.

Anti-irradiation performance against helium bombardment in bulk metallic glass (Cu{sub 47}Zr{sub 45}Al{sub 8}){sub 98.5}Y{sub 1.5}

Energy Technology Data Exchange (ETDEWEB)

Mei, Xianxiu, E-mail: xxmei@dlut.edu.cn [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024 (China); Wang, Bin; Dong, Chuang; Gong, Faquan; Wang, Younian [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024 (China); Wang, Zhiguang [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2013-07-15

Highlights: ► This paper used He{sup 2+} ion-irradiated metallic glass (Cu{sub 47}Zr{sub 45}Al{sub 8}){sub 98.5}Y{sub 1.5} and the W metal with the energy of 500 keV. ► There was no significant irradiation damage phenomenon on the surface of metallic glass at different irradiation fluences. ► For irradiated W, the peeling, delamination and flaking appeared numerously at fluences of 1 × 10{sup 18} and 2 × 10{sup 18} ions/cm{sup 2}. ► The resistance to He{sup 2+} irradiation of metallic glass (Cu{sub 47}Zr{sub 45}Al{sub 8}){sub 98.5}Y{sub 1.5} was superior to the one in W metal. -- Abstract: In order to compare the resistance to He{sup 2+} ion induced irradiation between metallic glass and polycrystal W metal, this paper used different fluences of He{sup 2+} ion-irradiated metallic glass (Cu{sub 47}Zr{sub 45}Al{sub 8}){sub 98.5}Y{sub 1.5} and polycrystal W with an energy of 500 keV. The SRIM simulation calculation results showed that the range (1.19 μm) of He{sup 2+} in metallic glass was greater than the one (0.76 μm) in polycrystal W. The SEM analysis showed that there was no significant irradiation damage phenomenon on the surface of metallic glass, and there was only a damage layer 1.45 μm away from the surface when the fluence reached 2 × 10{sup 18} ions/cm{sup 2}. For W, there were surface peeling, flaking and other surface damages at a fluence of 1 × 10{sup 18} ions/cm{sup 2}; when the fluence increased to 2 × 10{sup 18} ions/cm{sup 2}, multilayer detachment phenomenon appeared. The surface root mean square roughness of metallic glass (Cu{sub 47}Zr{sub 45}Al{sub 8}){sub 98.5}Y{sub 1.5} first increased and then decreased with the increase of fluence. The surface reflectivity of (Cu{sub 47}Zr{sub 45}Al{sub 8}){sub 98.5}Y{sub 1.5} decreased with the increase of fluence. Through detection by XRD, it was found that (Cu{sub 47}Zr{sub 45}Al{sub 8}){sub 98.5}Y{sub 1.5} always maintained amorphous phase after different fluences of radiation. The

Evolution of substorm and quiet-time electron anisotropies (30 less than or equal to E/sub e/ less than or equal to 300 keV)

International Nuclear Information System (INIS)

Higbie, P.R.; Baker, D.N.; Belian, R.D.; Hones, E.W. Jr.

1979-01-01

Work using the Charged Particle Analyzer (CPA) instruments aboard spacecraft 1976-059A and 1977-007A in synchronous orbit has shown that approx. 30 keV electron anisotropies may act as a sensitive indicator of the buildup of stresses in the outer magnetosphere. The development of such stresses is evidenced in the premidnight sector by the formation of field-aligned (cigar) anisotropies in the 30 keV electrons one to two hours prior to the onset of the expansion phase of the substorm. Using the complete three-dimensional pitch angle measurement capability of the CPA, it is shown in a movie format the detailed development of electron anisotropies during the course of substorm growth, expansion, and recovery phases. In contrast, detailed examples of quiet-time behavior of electron anisotropies at several energy levels between 30 and 300 keV are also shown. Such periods with no substorm activity show that 30 keV electrons remain approx. isotropic (outside the loss cone) throughout the nighttime sector, even though the higher energy (> 100 keV) electrons show the development of cigar anisotropies associated with normal drift-shell splitting. These results emphasize the substorm predictive capabilities of the low energy electron anisotropies and illustrate how the data might be used in a real-time monitoring mode. 19 references

Empirical formulae for mass attenuation and energy absorption coefficients from 1 keV to 20 MeV

International Nuclear Information System (INIS)

Manjunatha, H.C.; Sowmya, N.; Seenappa, L.; Sridhar, K.N.; Hanumantharayappa, C.

2017-01-01

Mass attenuation and energy absorption coefficients represents attenuation and absorption of X-rays and gamma rays in the material medium. A new empirical formula is proposed for mass attenuation and energy absorption coefficients in the region 1 < Z < 92 and from 1 keV to 20 MeV. The mass attenuation and energy absorption coefficients do not varies linearly with energy. We have performed the nonlinear regressions/nonlinear least square fittings and proposed the simple empirical relations between mass attenuation coefficients (μ/ρ) and mass energy absorption coefficients (μ en /ρ) and energy. We have compared the values produced by this formula with that of experiments. A good agreement of present formula with the experiments/previous models suggests that the present formulae could be used to evaluate mass attenuation and energy absorption coefficients in the region 1 < Z < 92. This formula is a model-independent formula and is the first of its kind that produces a mass attenuation and energy absorption coefficient values with the only simple input of energy for wide energy range 1 keV - 20 MeV in the atomic number region 1 < Z < 92. This formula is very much useful in the fields of radiation physics and dosimetry

High-resolution 3D dose distribution measured for two low-energy x-ray brachytherapy seeds: 125I and 103Pd

International Nuclear Information System (INIS)

Massillon-JL, G.; Minniti, R.; Mitch, M.G.; Soares, C.G.; Hearn, R.A.

2011-01-01

In this work, we have investigated the 3D absorbed dose distribution around 125 I and 103 Pd low-energy photon brachytherapy seeds using a high-spatial-resolution gel scanning system to address the current difficulty in measuring absorbed dose at close distances to these sources as a consequence of high dose rate gradient. A new version of BANG-gel coupled with a small format laser CT scanner has been used. Measurements were performed with 100 μm resolution in all dimensions. In particular, radial dose function and absorbed dose rate in the plane parallel to the sources longitudinal-axis were derived at radial distances smaller than or equal to 1 cm. In addition, the energy dependence was evaluated, finding that, within measurement uncertainties, the gel response is independent of the energy for energy photon values between 20 keV and 1250 keV. We have observed that at distances larger than 1.4 mm from the source, the delivered dose is similar to predictions from published Monte Carlo calculations (MC) for the 125 I seed. For distances between 1 mm and 3 mm, differences in magnitude and shape are significant for the 103 Pd seed, where an enhancement is observed. In the enhancement region, a difference of up to 70% in the radial dose function was obtained. Such observation suggests a contribution from other radionuclides emitting beta-particles or electrons, and not considered by MC. To understand the effect, spectrometry measurements were performed. A small contribution of 102 Rh/ 102m Rh radionuclide relative to 103 Pd was observed and its importance on the absorbed dose measured at close distances to the seed is time dependent and consequently, avoids reproducible measurements. Finally, the results obtained in this work underscore the importance of using high-spatial-resolution and water-equivalent detectors for measuring absorbed dose in low-energy photon radiation fields.

Sub-keV secondary ion mass spectrometry depth profiling: comparison of sample rotation and oxygen flooding

International Nuclear Information System (INIS)

Liu, R.; Wee, A.T.S.

2004-01-01

Following the increasingly stringent requirements in the characterization of sub-micron IC devices, an understanding of the various factors affecting ultra shallow depth profiling in secondary ion mass spectrometry (SIMS) has become crucial. Achieving high depth resolution (of the order of 1 nm) is critical in the semiconductor industry today, and various methods have been developed to optimize depth resolution. In this paper, we will discuss ultra shallow SIMS depth profiling using B and Ge delta-doped Si samples using low energy 0.5 keV O 2 + primary beams. The relationship between depth resolution of the delta layers and surface topography measured by atomic force microscopy (AFM) is studied. The effect of oxygen flooding and sample rotation, used to suppress surface roughening is also investigated. Oxygen flooding was found to effectively suppress roughening and gives the best depth resolution for B, but sample rotation gives the best resolution for Ge. Possible mechanisms for this are discussed

A sub-50meV spectrometer and energy filter for use in combination with 200kV monochromated (S)TEMs.

Science.gov (United States)

Brink, H A; Barfels, M M G; Burgner, R P; Edwards, B N

2003-09-01

A high-energy resolution post-column spectrometer for the purpose of electron energy loss spectroscopy (EELS) and energy-filtered TEM in combination with a monochromated (S)TEM is presented. The prism aberrations were corrected up to fourth order using multipole elements improving the electron optical energy resolution and increasing the acceptance of the spectrometer for a combination of object area and collection angles. Electronics supplying the prism, drift tube, high-tension reference and critical lenses have been newly designed such that, in combination with the new electron optics, a sub-50 meV energy resolution has been realized, a 10-fold improvement over past post-column spectrometer designs. The first system has been installed on a 200 kV monochromated TEM at the Delft University of Technology. Total system energy resolution of sub-100 meV has been demonstrated. For a 1s exposure the resolution degraded to 110 meV as a result of noise. No further degradation in energy resolution was measured for exposures up to 1 min at 120 kV. Spectral resolution measurements, performed on the pi* peak of the BN K-edge, demonstrated a 350 meV (FWHM) peak width at 200 kV. This measure is predominantly determined by the natural line width of the BN K-edge.

HIGH-RESOLUTION XMM-NEWTON SPECTROSCOPY OF THE COOLING FLOW CLUSTER A3112

Energy Technology Data Exchange (ETDEWEB)

Bulbul, G. Esra; Smith, Randall K.; Foster, Adam [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Cottam, Jean; Loewenstein, Michael; Mushotzky, Richard; Shafer, Richard, E-mail: ebulbul@cfa.harvard.edu [NASA Goddard Space Flight Center, Greenbelt, MD (United States)

2012-03-01

We examine high signal-to-noise XMM-Newton European Photon Imaging Camera (EPIC) and Reflection Grating Spectrometer (RGS) observations to determine the physical characteristics of the gas in the cool core and outskirts of the nearby rich cluster A3112. The XMM-Newton Extended Source Analysis Software data reduction and background modeling methods were used to analyze the XMM-Newton EPIC data. From the EPIC data, we find that the iron and silicon abundance gradients show significant increase toward the center of the cluster while the oxygen abundance profile is centrally peaked but has a shallower distribution than that of iron. The X-ray mass modeling is based on the temperature and deprojected density distributions of the intracluster medium determined from EPIC observations. The total mass of A3112 obeys the M-T scaling relations found using XMM-Newton and Chandra observations of massive clusters at r{sub 500}. The gas mass fraction f{sub gas} = 0.149{sup +0.036}{sub -0.032} at r{sub 500} is consistent with the seven-year Wilkinson Microwave Anisotropy Probe results. The comparisons of line fluxes and flux limits on the Fe XVII and Fe XVIII lines obtained from high-resolution RGS spectra indicate that there is no spectral evidence for cooler gas associated with the cluster with temperature below 1.0 keV in the central <38'' ({approx}52 kpc) region of A3112. High-resolution RGS spectra also yield an upper limit to the turbulent motions in the compact core of A3112 (206 km s{sup -1}). We find that the contribution of turbulence to total energy is less than 6%. This upper limit is consistent with the energy contribution measured in recent high-resolution simulations of relaxed galaxy clusters.

Experimental investigation of the multiple scatter peak of gamma rays in portland cement in the energy range 279-1332 keV

International Nuclear Information System (INIS)

Singh, Tejbir; Singh, Parjit S

2011-01-01

The pulse height spectra for different thicknesses of portland cement in the reflected geometry has been recorded with the help of a NaI(Tl) scintillator detector and 2 K MCA card using different gamma-ray sources such as Hg 203 (279 keV), Cs 137 (662 keV) and Co 60 (1173 and 1332 keV). It has been observed that the multiple scatter peak for portland cement appears at 110 (±7) keV in all the spectra irrespective of different incident photon energies in the range 279-1332 keV from different gamma-ray sources. Further, the variation in the intensity of the multiple scatter peak with the thickness of portland cement in the backward semi-cylinders has been investigated.

X-ray intensity fluctuation spectroscopy in the energy range from 1 to 4 keV

Energy Technology Data Exchange (ETDEWEB)

Retsch, C.C.

2001-06-01

X-ray intensity fluctuation spectroscopy was developed in the energy range of 1 to 4 keV and was used to study complex sample structures and dynamics in a liquid-crystal - aerosil dispersion. The advantages of a focusing versus a nonfocusing setup were explored, and the effects of using X-ray energies near absorption edges were investigated to enhance the capabilities of the method. It was found that even though excellent real space resolution and an increase in flux density can be gained from a Fresnel zone plate focusing setup, this usually comes at the expense of speckle contrast. At absorption edges, the speckle contrast is dominated by the imaginary part of the sample's index of refraction and therefore varies in a way similar to the total transmitted intensity. Employing these results, the dynamics of a dispersion of low-density silica aerosil in octylcyanobiphenyl (8CB) were studied. It was found that the known cross-over behavior of 8CB - aerosil samples towards the 3d-XY universality class should be understood as the coupling of the aerosil-gel dynamics to the dynamics of the director fluctuations in the liquid-crystal. This work indicates that the aerosil-gel mimics and dampens these director fluctuations and thus, by suppressing the director fluctuations, achieves a pure 3d-XY system. (orig.)

Resolution on the program energy-climate

International Nuclear Information System (INIS)

2008-01-01

This document presents the resolutions proposed in the resolution proposition n. 1261 and concerning the european Commission program on the energy policies and the climate change. Twelve resolution are presented on the energy sources development, the energy efficiency, the energy economy and the carbon taxes. (A.L.B.)

Calculated microdose spectra for intermediate energy neutrons (1 to 100 keV)

International Nuclear Information System (INIS)

Al-Affan, I.A.M.; Watt, D.E.

1983-01-01

Basic formulae for calculation of energy deposition events due to insiders, starters, stoppers and crossers, using the continuous slowing down approximation have been modified to allow for the enhanced energy deposition in spherical volumes due to elastic scattering interactions which reduce the penetration depth of the charged particle recoils. Energy deposition spectra have been obtained for energies of 1, 10, 50, 100 keV in 0.2 μm and 1 μm tissue-equivalent spheres. From these, frequency and dose distributions in lineal energy and in specific energy density have been calculated. Also calculated for different neutron energies are values of zeta, the energy average of event size, as a function of the diameter of the sensitive site. The structure of the energy event distributions can be interpreted in terms of the basic physics. The effect of the modifications to the basic formulae is to increase the number of energy deposition events due to insiders and to decrease the number of starters, stoppers and crossers. The degree of the effect increases with decreasing neutron energy, increasing sphere size, and the change is most significant for low energy deposition events. (author)

Calculated microdose spectra for intermediate energy neutrons (1 to 100 keV)

Energy Technology Data Exchange (ETDEWEB)

Al-Affan, I.A.M.; Watt, D.E. (Dundee Univ. (UK). Dept. of Medical Biophysics); Colautti, P.; Talpo, G. (Laboratori Nazionali dell' Infn, 35020, Legnaro (Padova) (Italy))

1983-01-01

Basic formulae for calculation of energy deposition events due to insiders, starters, stoppers and crossers, using the continuous slowing down approximation have been modified to allow for the enhanced energy deposition in spherical volumes due to elastic scattering interactions which reduce the penetration depth of the charged particle recoils. Energy deposition spectra have been obtained for energies of 1, 10, 50, 100 keV in 0.2 ..mu..m and 1 ..mu..m tissue-equivalent spheres. From these, frequency and dose distributions in lineal energy and in specific energy density have been calculated. Also calculated for different neutron energies are values of zeta, the energy average of event size, as a function of the diameter of the sensitive site. The structure of the energy event distributions can be interpreted in terms of the basic physics. The effect of the modifications to the basic formulae is to increase the number of energy deposition events due to insiders and to decrease the number of starters, stoppers and crossers. The degree of the effect increases with decreasing neutron energy, increasing sphere size, and the change is most significant for low energy deposition events.

High resolution Moessbauer spectroscopy with 67Zn in metallic systems

International Nuclear Information System (INIS)

Potzel, W.

1985-01-01

Moessbauer experiments on metallic systems are described where the high resolution 93.3 keV resonance in 67 Zn is used. In the first part, the Cu-Zn alloy system is investigated and the high energy resolution of this Moessbauer transition is employed to determine small changes of the s-electron density at the 67 Zn nucleus when the Zn concentration is changed. In the second part, Zn metal is taken as an example to demonstrate that the 93.3 keV transition is also extremely sensitive to small changes of lattice dynamical effects. 7 refs., 18 figs. (author)

Testing and simulation of silicon photomultiplier readouts for scintillators in high-energy astronomy and solar physics

Energy Technology Data Exchange (ETDEWEB)

Bloser, P.F., E-mail: Peter.Bloser@unh.edu; Legere, J.S.; Bancroft, C.M.; Jablonski, L.F.; Wurtz, J.R.; Ertley, C.D.; McConnell, M.L.; Ryan, J.M.

2014-11-01

Space-based gamma-ray detectors for high-energy astronomy and solar physics face severe constraints on mass, volume, and power, and must endure harsh launch conditions and operating environments. Historically, such instruments have usually been based on scintillator materials due to their relatively low cost, inherent ruggedness, high stopping power, and radiation hardness. New scintillator materials, such as LaBr{sub 3}:Ce, feature improved energy and timing performance, making them attractive for future astronomy and solar physics space missions in an era of tightly constrained budgets. Despite this promise, the use of scintillators in space remains constrained by the volume, mass, power, and fragility of the associated light readout device, typically a vacuum photomultiplier tube (PMT). In recent years, silicon photomultipliers (SiPMs) have emerged as promising alternative light readout devices that offer gains and quantum efficiencies similar to those of PMTs, but with greatly reduced mass and volume, high ruggedness, low voltage requirements, and no sensitivity to magnetic fields. In order for SiPMs to replace PMTs in space-based instruments, however, it must be shown that they can provide comparable performance, and that their inherent temperature sensitivity can be corrected for. To this end, we have performed extensive testing and modeling of a small gamma-ray spectrometer composed of a 6 mm×6 mm SiPM coupled to a 6 mm×6 mm ×10 mm LaBr{sub 3}:Ce crystal. A custom readout board monitors the temperature and adjusts the bias voltage to compensate for gain variations. We record an energy resolution of 5.7% (FWHM) at 662 keV at room temperature. We have also performed simulations of the scintillation process and optical light collection using Geant4, and of the SiPM response using the GosSiP package. The simulated energy resolution is in good agreement with the data from 22 keV to 662 keV. Above ∼1 MeV, however, the measured energy resolution is

Explanation of the 511 keV line. Cascade annihilating dark matter with the {sup 8}Be anomaly

Energy Technology Data Exchange (ETDEWEB)

Jia, Lian-Bao [Southwest University of Science and Technology, School of Science, Mianyang (China)

2018-02-15

A possible dark matter (DM) explanation about the long-standing issue of the Galactic 511 keV line is explored in this paper. For DM cascade annihilations of concern, a DM pair π{sub d}{sup +}π{sub d}{sup -} annihilates into unstable π{sub d}{sup 0}π{sub d}{sup 0}, and π{sub d}{sup 0} decays into e{sup +}e{sup -} with new interactions suggested by the {sup 8}Be anomaly. Considering the constraints from the effective neutrino number N{sub eff} and the 511 keV gamma-ray emission, a range of DM is obtained, 11.6 sub π{sub d}{sup {sub ±}}} keV line. The MeV scale DM may be searched by the DM-electron scattering, and the upper limit set by the CMB s-wave annihilation is derived in DM direct detections. (orig.)

Investigation of human teeth with respect to the photon interaction, energy absorption and buildup factor

Energy Technology Data Exchange (ETDEWEB)

Kurudirek, Murat, E-mail: mkurudirek@gmail.co [Faculty of Science, Department of Physics, Ataturk University, 25240 Erzurum (Turkey); Topcuoglu, Sinan [Faculty of Dentistry, Department of Endodontic, Ataturk University, 25240 Erzurum (Turkey)

2011-05-15

The effective atomic numbers and electron densities of human teeth have been calculated for total photon interaction (Z{sub PI{sub e{sub f{sub f}}}},Ne{sub PI{sub e{sub f{sub f}}}}) and photon energy absorption (Z{sub PEA{sub e{sub f{sub f}}}},Z{sub RW{sub e{sub f{sub f}}}}Ne{sub PEA{sub e{sub f{sub f}}}}) in the energy region 1 keV-20 MeV. Besides, the energy absorption (EABF) and exposure (EBF) buildup factors have been calculated for these samples by using the geometric progression fitting approximation in the energy region 0.015-15 MeV up to 40 mfp (mean free path). Wherever possible the results were compared with experiment. Effective atomic numbers (Z{sub PI{sub e{sub f{sub f}}}}) of human teeth were calculated using different methods. Discrepancies were noted in Z{sub PI{sub e{sub f{sub f}}}} between the direct and interpolation methods in the low and high energy regions where absorption processes dominate while good agreement was observed in intermediate energy region where Compton scattering dominates. Significant variations up to 22% were observed between Z{sub PI{sub e{sub f{sub f}}}} and Z{sub PEA{sub e{sub f{sub f}}}} in the energy region 30-150 keV which is the used energy range in dental cone beam computed tomography (CBCT) X-ray machines. The Z{sub eff} values of human teeth were found to relatively vary within 1% if different laser treatments are applied. In this variation, the Er:YAG laser treated samples were found to be less effected than Nd:YAG laser treated ones when compared with control group. Relative differences between EABF and EBF were found to be significantly high in the energy region 60 keV-1 MeV even though they have similar variations with respect to the different parameters viz. photon energy, penetration depth.

Mass separated neutral particle energy analyser

International Nuclear Information System (INIS)

Takeuchi, Hiroshi; Matsuda, Toshiaki; Miura, Yukitoshi; Shiho, Makoto; Maeda, Hikosuke; Hashimoto, Kiyoshi; Hayashi, Kazuo.

1983-09-01

A mass separated neutral particle energy analyser which could simultaneously measure hydrogen and deuterium atoms emitted from tokamak plasma was constructed. The analyser was calibrated for the energy and mass separation in the energy range from 0.4 keV to 9 keV. In order to investigate the behavior of deuteron and proton in the JFT-2 tokamak plasma heated with ion cyclotron wave and neutral beam injection, this analyser was installed in JFT-2 tokamak. It was found that the energy spectrum could be determined with sufficient accuracy. The obtained ion temperature and ratio of deuteron and proton density from the energy spectrum were in good agreement with the value deduced from Doppler broadening of TiXIV line and the line intensities of H sub(α) and D sub(α) respectively. (author)

Spectroscopic Investigation of p-Shell Lambda Hypernuclei by the (e,e'K⁺) Reaction

Energy Technology Data Exchange (ETDEWEB)

Chen, Chunhua [Hampton Univ., Hampton, VA (United States)

2014-08-01

Hypernuclear spectroscopy is a powerful tool to investigate Lambda-N interaction. Compared with other Lambda hypernuclei productions, electroproduction via the (e,e'K+) reaction has the advantage of exciting states deeply inside of the hypernucleus and achieving sub-MeV energy resolution. The E05-115 experiment, which was successfully performed in 2009, is the third generation hypernuclear experiment in JLab Hall C. A new splitter magnet and electron spectrometer were installed, and beam energy of 2.344 GeV was selected in this experiment. These new features gave better field uniformity, optics quality and made the tilt method more effective in improving yield-to-background ratio. The magnetic optics of the spectrometers were carefully studied with GEANT simulation, and corrections were applied to compensate for the fringe field cross talk between the compact spectrometer magnets. The non-linear least chi-squared method was used to further calibrate the spectrometer with the events from Lambda, Sigma0 and B12Lambda and uniform magnetic optics as well as precise kinematics were achieved. Several p-shell Lambda hypernuclear spectra, including B¹²<sub>Λ>, Be¹⁰<sub>Λ>, He⁷<sub>Λ>, were obtained with high energy resolution and good accuracy. For B¹²<sub>Λ>, eight peaks were recognized with the resolution of ~540keV (FWHM), and the ground state binding energy was obtained as 11.529 ± 0.012(stat.) ± 0.110(syst.) MeV. Be¹⁰<sub>Λ>, twelve peaks were recognized with the resolution of ~520keV (FWHM), and the binding energy of the ground state was determined as 8.710 ± 0.059(stat.) ± 0.114(syst.) MeV. For He⁷<sub>Λ>, three peaks were recognized with the resolution of ~730keV, and the ground state binding energy was obtained as 5.510 ± 0.050(stat.) ± 0.120(syst.) MeV. Compared with the published data of B¹²<sub>Λ> from the JLab Hall A experiment

Middle-energy electron anisotropies in the auroral region

Directory of Open Access Journals (Sweden)

P. Janhunen

2004-01-01

Full Text Available Field-aligned anisotropic electron distribution functions of T<sub>∥> > T<sub>⊥> type are observed on auroral field lines at both low and high altitudes. We show that typically the anisotropy is limited to a certain range of energies, often below 1keV, although sometimes extending to slightly higher energies as well. Almost always there is simultaneously an isotropic electron distribution at higher energies. Often the anisotropies are up/down symmetrical, although cases with net upward or downward electron flow also occur. For a statistical analysis of the anisotropies we divide the energy range into low (below 100eV, middle (100eV–1keV and high (above 1keV energies and develop a measure of anisotropy expressed in density units. The statistical magnetic local time and invariant latitude distribution of the middle-energy anisotropies obeys that of the average auroral oval, whereas the distributions of the low and high energy anisotropies are more irregular. This suggests that it is specifically the middle-energy anisotropies that have something to do with auroral processes. The anisotropy magnitude decreases monotonically with altitude, as one would expect, because electrons have high mobility along the magnetic field and thus, the anisotropy properties spread rapidly to different altitudes.

Key words. Magnetospheric physics (auroral phenomena. Space plasma physics (wave-particle interactions; changed particle motion and acceleration

Energy resolution of scintillation detectors

Energy Technology Data Exchange (ETDEWEB)

Moszyński, M., E-mail: M.Moszynski@ncbj.gov.pl; Syntfeld-Każuch, A.; Swiderski, L.; Grodzicka, M.; Iwanowska, J.; Sibczyński, P.; Szczęśniak, T.

2016-01-01

According to current knowledge, the non-proportionality of the light yield of scintillators appears to be a fundamental limitation of energy resolution. A good energy resolution is of great importance for most applications of scintillation detectors. Thus, its limitations are discussed below; which arise from the non-proportional response of scintillators to gamma rays and electrons, being of crucial importance to the intrinsic energy resolution of crystals. The important influence of Landau fluctuations and the scattering of secondary electrons (δ-rays) on intrinsic resolution is pointed out here. The study on undoped NaI and CsI at liquid nitrogen temperature with a light readout by avalanche photodiodes strongly suggests that the non-proportionality of many crystals is not their intrinsic property and may be improved by selective co-doping. Finally, several observations that have been collected in the last 15 years on the influence of the slow components of light pulses on energy resolution suggest that more complex processes are taking place in the scintillators. This was observed with CsI(Tl), CsI(Na), ZnSe(Te), and undoped NaI at liquid nitrogen temperature and, finally, for NaI(Tl) at temperatures reduced below 0 °C. A common conclusion of these observations is that the highest energy resolution, and particularly intrinsic resolution measured with the scintillators, characterized by two or more components of the light pulse decay, is obtainable when the spectrometry equipment integrates the whole light of the components. In contrast, the slow components observed in many other crystals degrade the intrinsic resolution. In the limiting case, afterglow could also be considered as a very slow component that spoils the energy resolution. The aim of this work is to summarize all of the above observations by looking for their origin.

Measurement of the internal bremsstrahlung spectrum of a 89Sr beta emitter in the 1–100 keV photon energy regime

International Nuclear Information System (INIS)

Singh, Amrit; Dhaliwal, A.S.

2015-01-01

The internal bremsstrahlung (IB) spectrum of 89 Sr, which is a unique first forbidden beta emitter, is studied in the 1–100 keV photon energy regime. The IB spectrum is experimentally measured using a Si(Li) detector, which is efficient in this photon energy regime, and is compared with the IB distributions that are predicted by the Knipp, Uhlenbeck and Bloch (KUB), Nilsson, and Lewis and Ford theories. In the soft energy regime up to 15 keV, the measured results are in agreement with all the aforementioned theories. However, from 16–30 keV, the experimental results are in agreement with the Lewis and Ford theory, which applies to forbidden transitions, and at higher photon energies, the Nilsson theory best describes the measured results. The differences among the different theories also increase with the photon energy. The effect of the electrostatic Coulomb field on the IB process for beta emitters with different end-point energies is investigated by comparing the ratio of the IB probabilities predicted using the KUB and Nilsson theories for 35 S and 89 Sr, i.e., soft and hard beta emitters, respectively. The Coulomb effect is shown to be significant in the high photon energy regime and for beta emitters with low end-point energies. - Highlights: • Internal bremsstrahlung spectrum of 89 Sr, a unique first forbidden beta emitter, is studied. • The measurements are taken in the photon energy regions of 1–100 keV with Si(Li) detector. • The measured results are deviating from Lewis and Ford theory and are close to the Nilsson theory. • The effect of Coulomb field on the IB process for different end point energy sources is investigated. • Effect of Coulomb field is more for low energy beta emitter towards the high energy end

Development of nanotopography during SIMS characterization of thin films of Ge{sub 1−x}Sn{sub x} alloy

Energy Technology Data Exchange (ETDEWEB)

Secchi, M., E-mail: secchi@fbk.eu [Center for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, 38123 Povo, TN (Italy); Department of Physics, University of Trento, Via Sommarive 14, 38123 Trento (Italy); Demenev, E. [Center for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, 38123 Povo, TN (Italy); Department of Molecular Science and Nanosystems, Ca’Foscari University, Dorsoduro 2137, 30123 Venice (Italy); Colaux, J.L. [Ion Beam Centre, Advanced Technology Institute, University of Surrey, Guildford GU2 7XH, Surrey, England (United Kingdom); Giubertoni, D.; Dell’Anna, R.; Iacob, E. [Center for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, 38123 Povo, TN (Italy); Gwilliam, R.M.; Jeynes, C. [Ion Beam Centre, Advanced Technology Institute, University of Surrey, Guildford GU2 7XH, Surrey, England (United Kingdom); Bersani, M. [Center for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, 38123 Povo, TN (Italy)

2015-11-30

Highlights: • SIMS protocol to measure high Sn concentration in GeSn alloy is proposed. • Cs{sup +} as incidence beam, collecting positive ions MCs{sup +} was the chosen configuration. • Applied sputtering conditions induced an early formation of surface topography. • Unusual dot and ripple evolution at oblique incidence angle on Ge were studied. • Two different mechanisms seem to be involved: ripple formation and nanovoids in Ge. - Abstract: This work presents a study of application of secondary ion mass spectrometry (SIMS) to measure tin concentration in Ge{sub 1−x}Sn{sub x} alloy with x higher than solid solubility ∼1%, i.e. well above the diluted regime where SIMS measurements usually provide the most reliable quantitative results. SIMS analysis was performed on Sn{sup +} ion implanted Ge films, epitaxially deposited on Si, and on chemical vapor deposition deposited Ge{sub 0.93}Sn{sub 0.07} alloy. Three SIMS conditions were investigated, varying primary beam ion species and secondary ion polarity keeping 1 keV impact energy. Best depth profile accuracy, best agreement with the fluences measured by Rutherford backscattering spectrometry, good detection limit (∼1 × 10{sup 17} at/cm{sup 3}) and depth resolution (∼2 nm/decade) are achieved in Cs{sup +}/SnCs{sup +} configuration. However, applied sputtering conditions (Cs{sup +} 1 keV, 64° incidence vs. normal) induced an early formation of surface topography on the crater bottom resulting in significant variation of sputtering yield. Atomic force microscopy shows a peculiar topography developed on Ge: for oblique incidence, a topography consisting in a sequence of dots and ripples was observed on the crater bottom. This behavior is unusual for grazing incidence and has been observed to increase with the Cs{sup +} fluence. Rotating sample during sputtering prevents this ripple formation and consequently improves the depth accuracy.

Sub-keV x-ray calibration of plastic scintillators

International Nuclear Information System (INIS)

Lyons, P.B.; Day, R.H.; Lier, D.W.; Elsberry, T.L.

1976-01-01

Several types of x-ray detectors have found widespread use for plasma diagnostic applications in the energy range below a few keV. Silicon diodes, photoelectric diodes, and plastic scintillators have been used to obtain diagnostic information in this region. Sub-keV calibration data for plastic scintillator detectors are reported, and the advantages and limitations of these three detectors in diagnostic measurements are compared. In a previous paper calibration data for plastic scintillators from 1.5 to 20 keV were given. In this paper the data are extended to the C-K/sub α/ line (277 eV). These data represent one application of a new sub-keV x-ray calibration facility at the Los Alamos Scientific Laboratory

Deviation from an inverse cosine dependence of kinetic secondary electron emission for angle of incidence at keV energy

International Nuclear Information System (INIS)

Ohya, Kaoru; Kawata, Jun; Mori, Ichiro

1989-01-01

Incident angle dependence of kinetic secondary electron emission from metals resulting from incidence of keV ions is investigated by computer simulation with the TRIM Monte Carlo program of ion scattering in matter. The results show large deviations from the inverse cosine dependence, which derives from high-energy approximation, because of a series of elastic collisions of incident ions with metal atoms. In the keV energy region, the elastic collisions have two different effects on the angular dependence for relatively high-energy light ions and for low-energy heavy ions: they result in over- and under-inverse-cosine dependences, respectively. The properties are observed even with an experiment of the keV-neutral incidence on a contaminated surface. In addition, the effects of the thin oxide layer and roughness on the surface are examined with simplified models. (author)

High resolution spectroscopy of jet cooled phenyl radical: The ν{sub 1} and ν{sub 2} a{sub 1} symmetry C–H stretching modes

Energy Technology Data Exchange (ETDEWEB)

Chang, Chih-Hsuan; Nesbitt, David J. [JILA, National Institute of Standards and Technology, University of Colorado, Boulder, Colorado 80309, USA and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309 (United States)

2016-07-28

A series of CH stretch modes in phenyl radical (C{sub 6}H{sub 5}) has been investigated via high resolution infrared spectroscopy at sub-Doppler resolution (∼60 MHz) in a supersonic discharge slit jet expansion. Two fundamental vibrations of a{sub 1} symmetry, ν{sub 1} and ν{sub 2}, are observed and rotationally analyzed for the first time, corresponding to in-phase and out-of-phase symmetric CH stretch excitation at the ortho/meta/para and ortho/para C atoms with respect to the radical center. The ν{sub 1} and ν{sub 2} band origins are determined to be 3073.968 50(8) cm{sup −1} and 3062.264 80(7) cm{sup −1}, respectively, which both agree within 5 cm{sup −1} with theoretical anharmonic scaling predictions based on density functional B3LYP/6-311g++(3df,3dp) calculations. Integrated band strengths for each of the CH stretch bands are analyzed, with the relative intensities agreeing remarkably well with theoretical predictions. Frequency comparison with previous low resolution Ar-matrix spectroscopy [A. V. Friderichsen et al., J. Am. Chem. Soc. 123, 1977 (2001)] reveals a nearly uniform Δν ≈ + 10-12 cm{sup −1} blue shift between gas phase and Ar matrix values for ν{sub 1} and ν{sub 2}. This differs substantially from the much smaller red shift (Δν ≈ − 1 cm{sup −1}) reported for the ν{sub 19} mode, and suggests a simple physical model in terms of vibrational mode symmetry and crowding due to the matrix environment. Finally, the infrared phenyl spectra are well described by a simple asymmetric rigid rotor Hamiltonian and show no evidence for spectral congestion due to intramolecular vibrational coupling, which bodes well for high resolution studies of other ring radicals and polycyclic aromatic hydrocarbons. In summary, the combination of slit jet discharge methods with high resolution infrared lasers enables spectroscopic investigation of even highly reactive combustion and interstellar radical intermediates under gas phase, jet

X-ray photoelectron spectroscopy study of {beta}-BaB{sub 2}O{sub 4} optical surface

Energy Technology Data Exchange (ETDEWEB)

Atuchin, V.V.; Kesler, V.G.; Kokh, A.E.; Pokrovsky, L.D

2004-02-29

An X-ray photoelectron spectroscopy (XPS) study has been performed for (0 0 1) BaB{sub 2}O{sub 4}. The crystal surface has been polished mechanically and cleaned by chemical etching. In XPS observation, depth profiling has been produced by sputtering with Ar{sup +} 3 keV ions. Photoelectron binding energies of original element core levels and valence band have been measured as a function of sputtering time. The persistence of binding energies of barium and boron core levels and valence band structure has been found. For O 1 s core level the formation of new spectral components with lower binding energies has been revealed.

Nuclear resonance scattering study of iridates, iridium and antimony based pyrochlores

Energy Technology Data Exchange (ETDEWEB)

Alexeev, P.

2017-04-15

This thesis shows the first synchrotron-based Moessbauer spectroscopy studies on iridium containing compounds and first vibrational spectroscopy on Sb containing compounds carried out at the P01 beamline of PETRA III. In this context, two types of X-ray monochromators have been developed: a monochromator for 73 keV photons with medium energy resolution, and a high-resolution backscattering monochromator based on a sapphire crystal. The monochromator for 73 keV X-rays is the key instrument for hyperfine spectroscopy on Iridium compounds, while the sapphire backscattering monochromator is purposed to vibrational spectroscopy on any Moessbauer resonances with the transition energies in the 20-50 keV range. Additionally, the signal detection for nuclear resonance scattering experiments at the beamline was significantly improved during this work, inspired by the high energies and low lifetimes of the employed resonances. The first synchrotron-based hyperfine spectroscopy on Iridium-containing compounds was demonstrated by NRS on 73 keV resonance in {sup 193}Ir. The results can be interpreted by dynamical theory of nuclear resonance scattering. In this work, special emphasis is set onto the electronic and magnetic properties of Ir nuclei in IrO{sub 2} and in Ruddlesden-Popper (RP) phases of strontium iridates Sr{sub n+1}Ir{sub n}O{sub 3n+1} (n=0,1). These systems are well-suited for studies with X-ray scattering techniques, since the scattered signal contains vast information about the widely tunable crystallographic and electronic structure of these systems; furthermore, studies with X-rays are less limited by absorption from iridium as it is the case for neutron scattering experiments. The hyperfine parameters in IrO{sub 2}, SrIrO{sub 3} and Sr{sub 2}IrO{sub 4} have been measured via Nuclear Forward Scattering for the first time. Using the dynamical theory of NRS, the temperature and magnetic field dependence of the electric field gradient and magnetic hyperfine field

High resolution electron microscopy and electron diffraction of YBa/sub 2/Cu/sub 3/O/sub 7-x/

International Nuclear Information System (INIS)

Krakow, W.; Shaw, T.M.

1988-01-01

Experimental high resolution electron micrographs and computer simulation experiments have been used to evaluate the visibility of the atomic constituents of YBa/sub 2/Cu/sub 3/O/sub 7-x/. In practice, the detection of oxygen has not been possible in contradiction to that predicted by modelling of perfect crystalline material. Preliminary computer experiments of the electron diffraction patterns when oxygen vacancies are introduced on the Cu-O sheets separating Ba layers show the diffuse streaks characteristic of short range ordering

Calibration efficiency of HPGe detector in the 50-1800 KeV energy range

International Nuclear Information System (INIS)

Venturini, Luzia

1996-01-01

This paper describes the efficiency of an HPGe detector in the 50 - 1800 keV energy range, for two geometries for water measurements: Marinelli breaker (850 ml) and a polyethylene flask (100 ml). The experimental data were corrected for the summing effect and fitted to a continuous, differentiable and energy dependent function given by 1n(ε)=b 0 +b 1 .1n(E/E 0 )+ β.1n(E/E 0 ) 2 , where β = b 2 if E>E 0 and β =a 2 if E ≤E 0 ; ε = the full absorption peak efficiency; E is the gamma-ray energy and {b 0 , b 1 , b 2 , a 2 , E 0 } is the parameter set to be fitted. (author)

High-resolution imaging of coronary calcifications by intense low-energy fluoroscopic X-ray obtained from synchrotron radiation

Energy Technology Data Exchange (ETDEWEB)

Ohtsuka, S.; Sugishita, Y.; Takeda, T.; Itai, Y.; Tada, J.; Hyodo, K.; Ando, M. [Inst. of Clinical Medicine, Univ. of Tsukuba, Ibaraki (Japan). Dept. of Cardiology

2000-07-01

In order to obtain an intense monochromatic low-energy X-ray from synchrotron radiation (SR) and apply it to detect coronary calcifications, the SR beam was reflected with a silicon crystal to be expanded (150 mm in height and 80 mm in width) and to be monochromatized at an energy level of 37 keV. The X-ray was intermittently irradiated to obtain dynamic imaging of 30 images/s. Images were recorded by a digital fluorography system. The low-energy X-ray from SR sharply visualized calcification of coronary arteries, while conventional X-ray could not visualize coronary calcification. The intense monochromatic low-energy X-ray from SR is sensitive, has high-resolution for imaging coronary calcification and may serve as a screening method for coronary artery disease.

Investigation to optimize the energy resolution and efficiency of cadmium(zinc)telluride for photon measurements

Science.gov (United States)

Kim, Hadong

While the investigations of the Cd(Zn)Te characteristics were completed, a new method to make arbitrary anode shapes, without the troublesome shadow mask technique, was found. With this technique, the two-anode geometry Cd(Zn)Te detector was introduced and tested. The semiconductor performance of the two-anode geometry detectors for the incoming gamma rays of 241Am, 57Co, and 137Cs were compared to the responses of the planar device. The very promising photon energy resolutions of 9.3 and 5.4% FWHM were obtained with the two-anode geometry detector for the gamma rays energies of 122 keV and 662 keV, respectively, while no discernible full energy peaks were apparent with the planar detector. Several simulation programs that are very easy to handle were developed as useful tools for investigating the complicated gamma ray pulse height distributions, which were due to the energy deposition events inside the semiconductors. Comparisons to the known values and with the results from other application programs, validated the information obtained from the simulation programs, which were developed during this research effort. A graphical user interface (GUI) was designed for the user's convenience in order to enter the required input parameters for the specific requirements of each simulation programs. The idealized noise free spectra for the planar detector and for the small pixel geometry detector were successfully obtained by applying Monte Carlo techniques.

Dual energy exposure control (DEEC) for computed tomography: Algorithm and simulation study

Energy Technology Data Exchange (ETDEWEB)

Stenner, Philip; Kachelriess, Marc [Institute of Medical Physics, University of Erlangen-Nuernberg, Henkestr. 91, Erlangen 91052 (Germany)

2008-11-15

DECT means acquiring the same object at two different energies, respectively two different tube voltages U{sub 1} and U{sub 2}. The raw data q{sub 1} and q{sub 2} undergo a decomposition process of type p=p(q{sub 1},q{sub 2}). The raw data p are reconstructed to obtain monochromatic images of the attenuation {mu}, of the object density {rho}, or of a specific material distribution. Recent advances in DECT focus on noise reduction techniques [S. Richard and J. H. Siewerdsen, Med. Phys. 35(2), 586-600 (2008)] and enable high performance DECT such as lung nodule detection [Shkumat et al., Med. Phys. 35(2), 629-632 (2008)]. Given p and a raw data-based projection-wise patient dose estimation D({alpha}) the authors determine the optimal tube current curves I{sub 1}({alpha}) and I{sub 2}({alpha}), with {alpha} being the view angle, which minimizes image noise for a given patient dose level. DEEC can perform online; I{sub 1}({alpha}) and I{sub 2}({alpha}) can be determined during the scan. Simulation studies using semianthropomorphic phantom data were carried out. In particular, functions p that generate {mu}-images and density images were evaluated. Image quality was compared to standard scans at U{sub 0}=120 kV (clinical CT) and U{sub 0}=45 kV (micro-CT) that were taken at the same dose level (D{sub 0}=D{sub 1}+D{sub 2}) and identical spatial resolution. Appropriate choice of p(q{sub 1},q{sub 2}) allows to obtain {mu}-images that show fewer artifacts and yield image noise levels comparable to the noise of the standard scan. The authors compared the standard scan to {mu}-images at 70 keV, which is the effective energy used in clinical CT, and found optimal results with {mu}-images at 25 keV for micro-CT. Nonoptimal choice of the decomposition function will, however, significantly increase image noise. In particular {mu}-images at 511 keV, as needed for PET/CT attenuation correction, exhibit more than twice as much image noise as the standard scan. With DEEC, which

Experimental charge fractions of hydrogen scattered from insulators at 50-340 keV

CERN Document Server

Ross, Graham G

2002-01-01

Ion bombardment of insulators induces accumulation of electric charges at and under the insulator surfaces. This paper deals with the effect of the accumulated electric charges on the charge fractions of scattered hydrogen. We have measured and compiled charge fractions of hydrogen, in the energy range (for the scattered particles) from 50 to 340 keV, scattered from polystyrene, polymethylmethacrylate, polycarbonate, polyethylene and silicon. In order to establish the effect of the charge accumulation, some samples have been cut from a thick (1 mm) sheet, while some others have been spin coated (approx 250 nm) onto silicon wafers. Experimental measurements have been fitted with the equation f(0)=Aexp(-V sup 2 /V sub i V sub 0), where f(0) is the neutral fraction, V the velocity, V sub i the 'Bohr velocity' for the electron of projectiles, A and V sub 0 the fitting parameters. Comparisons using the least-square fitting procedure have shown that the accumulation of electric charges on the thick polymer samples ...

Elemental mapping in achromatic atomic-resolution energy-filtered transmission electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Forbes, B.D. [School of Physics, University of Melbourne, Parkville, VIC 3010 (Australia); Houben, L. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Gruenberg Institute, Forschungszentrum Jülich, D-52425 Jülich (Germany); Mayer, J. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Gruenberg Institute, Forschungszentrum Jülich, D-52425 Jülich (Germany); Central Facility for Electron Microscopy, RWTH Aachen University, D-52074 Aachen (Germany); Dunin-Borkowski, R.E. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Gruenberg Institute, Forschungszentrum Jülich, D-52425 Jülich (Germany); Allen, L.J., E-mail: lja@unimelb.edu.au [School of Physics, University of Melbourne, Parkville, VIC 3010 (Australia)

2014-12-15

We present atomic-resolution energy-filtered transmission electron microscopy (EFTEM) images obtained with the chromatic-aberration-corrected FEI Titan PICO at the Ernst-Ruska Centre, Jülich, Germany. We find qualitative agreement between experiment and simulation for the background-subtracted EFTEM images of the Ti–L{sub 2,3} and O–K edges for a specimen of SrTiO{sub 3} oriented down the [110] zone axis. The simulations utilize the transition potential formulation for inelastic scattering, which permits a detailed investigation of contributions to the EFTEM image. We find that energy-filtered images of the Ti–L{sub 2,3} and O–K edges are lattice images and that the background-subtracted core-loss maps may not be directly interpretable as elemental maps. Simulations show that this is a result of preservation of elastic contrast, whereby the qualitative details of the image are determined primarily by elastic, coherent scattering. We show that this effect places a constraint on the range of specimen thicknesses which could theoretically yield directly useful elemental maps. In general, interpretation of EFTEM images is ideally accompanied by detailed simulations. - Highlights: • Achromatic atomic-resolution EFTEM images were obtained for STO 〈110〉. • Simulations were in qualitative agreement with Ti–L{sub 2,3} and O–K edge maps. • The experimental EFTEM maps are not directly interpretable as elemental maps. • Image intensities are strongly determined by preservation of elastic contrast. • Interpretation of EFTEM images is ideally accompanied by detailed simulations.

Mounting and testing of a 'sandwich' type neutron spectrometer with semiconductor detectors and 6Li

International Nuclear Information System (INIS)

Fabro, M.A.

1973-01-01

Commercial surface barrier detectors (Si(Au)) were used to construct the spectrometer; the 6 LiF was evaporated by vacuum onto a film of Formvar and afterwards over the surface of one of the detectors, with a 6 LiF thickness of 0,2 μm (50 μg/cm 2 ) and 1,5 μm(400 μg/cm 2 ) respectively. Tests were made with slow neutrons and with neutrons from the reactions D(d,n) 3 He (2,65 MeV) and T(d,n) 4 He (14 MeV). The energy resolution for thermal neutrons was about 200 keV (FWHM) for the sum (E sub(t) + E sub(α)) and about 7 keV (FWHM) for the difference (E sub(t) - E sub(α)) with an evaluated efficiency of 5,5x10 -4 , for the sum. For the 2,65 MeV neutrons, the energy resolution was about 240 keV (FWHM) and an evaluated efficiency of 2,1 x 10 -7 . It was not possible to detect 14 MeV neutrons [pt

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.

Benchmarking NaI(Tl) Electron Energy Resolution Measurements

International Nuclear Information System (INIS)

Mengesha, Wondwosen; Valentine, J D.

2002-01-01

A technique for validating electron energy resolution results measured using the modified Compton coincidence technique (MCCT) has been developed. This technique relies on comparing measured gamma-ray energy resolution with calculated values that were determined using the measured electron energy resolution results. These gamma-ray energy resolution calculations were based on Monte Carlo photon transport simulations, the measured NaI(Tl) electron response, a simplified cascade sequence, and the measured electron energy resolution results. To demonstrate this technique, MCCT-measured NaI(Tl) electron energy resolution results were used along with measured gamma-ray energy resolution results from the same NaI(Tl) crystal. Agreement to within 5% was observed for all energies considered between the calculated and measured gamma-ray energy resolution results for the NaI(Tl) crystal characterized. The calculated gamma-ray energy resolution results were also compared with previously published gamma-ray energy resolution measurements with good agreement (<10%). In addition to describing the validation technique that was developed in this study and the results, a brief review of the electron energy resolution measurements made using the MCCT is provided. Based on the results of this study, it is believed that the MCCT-measured electron energy resolution results are reliable. Thus, the MCCT and this validation technique can be used in the future to characterize the electron energy resolution of other scintillators and to determine NaI(Tl) intrinsic energy resolution

Low-energy x-ray dosimetry studies (7 to 17.5 keV) with synchroton radiation

International Nuclear Information System (INIS)

Ipe, N.E.; Bellamy, H.; Flood, J.R.

1995-06-01

Unique properties of synchrotron radiation (SR), such as its high intensity, brightness, polarization, and broad spectral distribution (extending from x-ray to infra-red wavelengths) make it an attractive light source for numerous experiments. As SR facilities are rapidly being built all over the world, they introduce the need for low-energy x-ray dosemeters because of the potential radiation exposure to experimenters. However, they also provide a unique opportunity for low-energy x-ray dosimetry studies because of the availability of monochromatic x-ray beams. Results of such studies performed at the Stanford Synchrotron Radiation Laboratory are described. Lithium fluoride TLDs (TLD-100) of varying thicknesses (0.015 to 0.08 cm) were exposed free in air to monochromatic x-rays (7 to 17.5 keV). These exposures were monitored with ionization chambers. The response (nC/Gy) was found to increase with increasing TLD thickness and with increasing beam energy. A steeper increase in response with increasing energy was observed with the thicker TLDs. The responses at 7 and 17.5 keV were within a factor of 2.3 and 5.2 for the 0.015 and 0.08 cm-thick TLDs, respectively. The effects of narrow (beam size smaller than the dosemeter) and broad (beam size larger than the dosemeter) beams on the response of the TLDs are also reported

Influence of Si ion implantation on structure and morphology of g-C{sub 3}N{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Varalakshmi, B.; Sreenivasulu, K.V. [School of Engineering Sciences and Technology (SEST), University of Hyderabad, Hyderabad 500046 (India); Asokan, K. [Inter University Accelerator Centre (IUAC), Aruna Asaf Ali Marg, Near Vasant Kunj, New Delhi 110067 (India); Srikanth, V.V.S.S., E-mail: vvsssse@uohyd.ernet.in [School of Engineering Sciences and Technology (SEST), University of Hyderabad, Hyderabad 500046 (India)

2016-07-15

Effect of Si ion implantation on structural and morphological features of graphite-like carbon nitride (g-C{sub 3}N{sub 4}) was investigated. g-C{sub 3}N{sub 4} was prepared by using a simple atmospheric thermal decomposition process. The g-C{sub 3}N{sub 4} pellets were irradiated with a Si ion beam of energy 200 keV with different fluencies. Structural, morphological and elemental, and phase analysis of the implanted samples in comparison with the pristine samples was carried out by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) with energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) techniques, respectively. The observations revealed that Si ion implantation results in a negligible change in the crystallite size and alteration of the network-like to the sheet-like morphology of g-C{sub 3}N{sub 4} and Si ions in the g-C{sub 3}N{sub 4} network.

Inelastic scattering of 275 keV neutrons by silver

International Nuclear Information System (INIS)

Litvinsky, L.L.; Zhigalov, Ya.A.; Krivenko, V.G.; Purtov, O.A.; Sabbagh, S.

1997-01-01

Neutron total, elastic and inelastic scattering cross-scattering of Ag at the E n = 275 KeV neutron energy were measured by using the filtered neutron beam of the WWR-M reactor in Kiev. The d-neutron strength function S n2 of Ag was determined from the analysis of all available data in the E n ≤ keV energy region on neutron inelastic scattering cross-sections with excitation of the first isomeric levels I π m = 7/2 + , E m ∼ 90 keV of 107,109 Ag: S n2 = (1.03 ± 0.19) · 10 -4 . (author). 10 refs, 3 figs

The development of high resolution silicon x-ray microcalorimeters

Science.gov (United States)

Porter, F. S.; Kelley, R. L.; Kilbourne, C. A.

2005-12-01

Recently we have produced x-ray microcalorimeters with resolving powers approaching 2000 at 5.9 keV using a spare XRS microcalorimeter array. We attached 400 um square, 8 um thick HgTe absorbers using a variety of attachment methods to an XRS array and ran the detector array at temperatures between 40 and 60 mK. The best results were for absorbers attached using the standard XRS absorber-pixel thermal isolation scheme utilizing SU8 polymer tubes. In this scenario we achieved a resolution of 3.2 eV FWHM at 5.9 keV. Substituting a silicon spacer for the SU8 tubes also yielded sub-4eV results. In contrast, absorbers attached directly to the thermistor produced significant position dependence and thus degraded resolution. Finally, we tested standard 640um-square XRS detectors at reduced bias power at 50mK and achieved a resolution of 3.7eV, a 50% improvement over the XRS flight instrument. Implanted silicon microcalorimeters are a mature flight-qualified technology that still has a substantial phase space for future development. We will discuss these new high resolution results, the various absorber attachment schemes, planned future improvements, and, finally, their relevance to future high resolution x-ray spectrometers including Constellation-X.

Internal conversion coefficients of M4 isomeric transitions in /sup 125/ /sup 127/ /sup 129/Te decay

Energy Technology Data Exchange (ETDEWEB)

Soni, S K; Kumar, A; Gupta, S L; Pancholi, S C [Delhi Univ. (India). Dept. of Physics and Astrophysics

1977-01-01

The internal conversion coefficients have been measured using a high resolution low energy Ge(Li) detector for the following M4 transitions: /sup 125/Te: 109.27 keV transition ..cap alpha..sub(T) = 357 +- 11; RG method, /sup 127/Te: 88,26 keV transition ..cap alpha..sub(K) = 484 +- 23; XPG method, /sup 129/Te: 105.50 keV transition ..cap alpha..sub(K) = 213 +- 10; XPG method. It is observed that these values are lower by 2.5-3.6% as compared with Hager and Seltzer's calculations. A comparison between experimental and theoretical ..cap alpha..sub(K) and ..cap alpha..sub(T) values for eleven M4 transitions shows that the experimental values are systematically lower.

AstroBox: A novel detection system for very low-energy protons from β-delayed proton decay

Energy Technology Data Exchange (ETDEWEB)

Pollacco, E., E-mail: epollacco@cea.fr [IRFU, CEA Saclay, Gif-sur-Yvette (France); Trache, L. [Cyclotron Institute, Texas A and M University, College Station, TX 77843-3366 (United States); National Institute of Physics and Nuclear Engineering, Bucharest-Magurele, RO-077125 (Romania); Simmons, E.; Spiridon, A.; McCleskey, M. [Cyclotron Institute, Texas A and M University, College Station, TX 77843-3366 (United States); Roeder, B.T., E-mail: broeder@comp.tamu.edu [Cyclotron Institute, Texas A and M University, College Station, TX 77843-3366 (United States); Saastamoinen, A.; Tribble, R.E. [Cyclotron Institute, Texas A and M University, College Station, TX 77843-3366 (United States); Pascovici, G. [National Institute of Physics and Nuclear Engineering, Bucharest-Magurele, RO-077125 (Romania); Kebbiri, M.; Mols, J.P.; Raillot, M. [IRFU, CEA Saclay, Gif-sur-Yvette (France)

2013-09-21

An instrument, AstroBox, has been developed to perform low energy proton spectroscopy from β-delayed proton emitters of interest to astrophysics studies. Energetic precursor nuclei are identified and stopped in the gas volume of the detector. The subsequent β or β-proton decay traces ionized paths in the gas. The ionization electrons are drifted in an electric field and are amplified with a Micro Pattern Gas Amplifier Detector (MPGAD). The system was tested in-beam using the β-delayed proton-emitter {sup 23}Al, which was produced with the p({sup 24}Mg,{sup 23}Al)2n reaction and separated with the Momentum Achromat Recoil Spectrometer (MARS) at the Cyclotron Institute at Texas A and M University. Off-beam proton spectra have essentially no β background down to ∼100keV and have a resolution of ∼15keV (fwhm) for proton-decay lines at E{sub p}=197 and 255 keV. Lines with βp-branching as low as 0.02% are observed. In addition, the device also gives good mass and charge resolution for energetic heavy ions measured in-beam.

Investigation of multilayer X-ray optics for 6 keV to 20 keV energy range

Czech Academy of Sciences Publication Activity Database

Oberta, Peter; Platonov, Y.; Flechsig, U.

2012-01-01

Roč. 19, č. 5 (2012), s. 675-681 ISSN 0909-0495 Institutional research plan: CEZ:AV0Z10100522 Keywords : X-ray optics * multilayer * energy resolution Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.186, year: 2012 http://journals.iucr.org/s/issues/2012/05/00/issconts.html

Energy loss and straggling of 1–50 keV H, He, C, N, and O ions passing through few layer graphene

International Nuclear Information System (INIS)

Allegrini, Frédéric; Bedworth, Peter; Ebert, Robert W.; Fuselier, Stephen A.; Nicolaou, Georgios; Sinton, Steve

2015-01-01

Highlights: • Evaluation of graphene foils for space plasma instruments. • Energy loss and straggling of keV ions passing through graphene foils. • Lower energy loss than for ultra-thin carbon foils. • Thickness non-uniformity leads to higher straggling. - Abstract: Graphene could be an alternative to amorphous carbon foils, in particular in space plasma instrumentation. The interaction of ions or neutral atoms with these foils results in different effects: electron emission, charge exchange, angular scattering, and energy straggling. We showed in previous studies that (1) the charge exchange properties are similar for graphene and regular carbon foils, and (2) the scattering at low energies (few keVs) is less for graphene than for one of our thinnest practical carbon foils. In this study, we report measurements of the energy loss and straggling of ∼1–50 keV H, He, C, N, and O ions in graphene. We compare graphene and a carbon foil for hydrogen. We provide simple power law fits to the average energy loss, energy straggling, and skewness of the energy distributions. We find the energy loss for ions transiting through graphene to be reduced compared to thin carbon foils but the energy straggling to be larger, which we attribute to the non-uniformity of the graphene foils used in this study

Ion Beam Materials Analysis and Modifications at keV to MeV Energies at the University of North Texas

Science.gov (United States)

Rout, Bibhudutta; Dhoubhadel, Mangal S.; Poudel, Prakash R.; Kummari, Venkata C.; Lakshantha, Wickramaarachchige J.; Manuel, Jack E.; Bohara, Gyanendra; Szilasi, Szabolcs Z.; Glass, Gary A.; McDaniel, Floyd D.

2014-02-01

The University of North Texas (UNT) Ion Beam Modification and Analysis Laboratory (IBMAL) has four particle accelerators including a National Electrostatics Corporation (NEC) 9SDH-2 3 MV tandem Pelletron, a NEC 9SH 3 MV single-ended Pelletron, and a 200 kV Cockcroft-Walton. A fourth HVEC AK 2.5 MV Van de Graaff accelerator is presently being refurbished as an educational training facility. These accelerators can produce and accelerate almost any ion in the periodic table at energies from a few keV to tens of MeV. They are used to modify materials by ion implantation and to analyze materials by numerous atomic and nuclear physics techniques. The NEC 9SH accelerator was recently installed in the IBMAL and subsequently upgraded with the addition of a capacitive-liner and terminal potential stabilization system to reduce ion energy spread and therefore improve spatial resolution of the probing ion beam to hundreds of nanometers. Research involves materials modification and synthesis by ion implantation for photonic, electronic, and magnetic applications, micro-fabrication by high energy (MeV) ion beam lithography, microanalysis of biomedical and semiconductor materials, development of highenergy ion nanoprobe focusing systems, and educational and outreach activities. An overview of the IBMAL facilities and some of the current research projects are discussed.

Measurement of the {sup 13}C(α,n){sup 16}O reaction with the Trojan horse method: Focus on the sub threshold resonance at −3 keV

Energy Technology Data Exchange (ETDEWEB)

La Cognata, M. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Catania (Italy); Spitaleri, C.; Guardo, G. L.; Puglia, S. M. R.; Romano, S.; Spartà, R. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Catania and Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy); Trippella, O. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Catania and Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, and Dipartimento di Fisica, Università di Perugia, Perugia (Italy); Kiss, G. G. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Catania and Institute of Nuclear Research (ATOMKI), Debrecen (Hungary); Rogachev, G. V.; Avila, M.; Koshchiy, E.; Kuchera, A.; Santiago, D. [Department of Physics, Florida State University, Tallahassee, Florida (United States); Mukhamedzhanov, A. M. [Cyclotron Institute, Texas A and M University, College Station, Texas (United States); Lamia, L. [Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy)

2014-05-02

The {sup 13}C(α,n){sup 16}O reaction is the neutron source of the main component of the s-process. The astrophysical S(E)-factor is dominated by the −3 keV sub-threshold resonance due to the 6.356 MeV level in {sup 17}O. Its contribution is still controversial as extrapolations, e.g., through R-matrix calculations, and indirect techniques, such as the asymptotic normalization coefficient (ANC), yield inconsistent results. Therefore, we have applied the Trojan Horse Method (THM) to the {sup 13}C({sup 6}Li,n{sup 16}O)d reaction to measure its contribution. For the first time, the ANC for the 6.356 MeV level has been deduced through the THM, allowing to attain an unprecedented accuracy. Though a larger ANC for the 6.356 MeV level is measured, our experimental S(E) factor agrees with the most recent extrapolation in the literature in the 140-230 keV energy interval, the accuracy being greatly enhanced thanks to this innovative approach, merging together two well establish indirect techniques, namely, the THM and the ANC.

Characterizations of MCP performance in the hard x-ray range (6–25 keV)

Energy Technology Data Exchange (ETDEWEB)

Wu, Ming, E-mail: minwu@sandia.gov; Rochau, Greg [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Moy, Ken [Special Technology Laboratories, NSTec, Santa Barbara, California 93111-2335 (United States); Kruschwitz, Craig [National Security Technologies, LLC, Los Alamos Operations, Los Alamos, New Mexico 87544 (United States)

2014-11-15

MCP detector performance at hard x-ray energies from 6 to 25 keV was recently investigated using NSLS beamline X15A at BNL. Measurements were made with an NSTec Gen-II (H-CA-65) framing camera, based on a Photonis MCP with ∼10 μm in diameter pores, ∼12 μm center-center spacing, an L/D ratio of 46, and a bias angle of 8°. The MCP characterizations were focused on (1) energy and angle dependent sensitivity, (2) energy and angle dependent spatial resolution, (3) energy dependent gain performance, and (4) energy dependent dynamic range. These measurement corroborated simulation results using a Monte Carlo model that included hard x-ray interactions and the subsequent electron cascade in the MCP.

Study of neutron resonances of barium and copper isotopes by the time-of-flight method at low energies (0 to 15 keV); Etude des resonances de neutrons pour les isotopes du baryum et du cuivre par la methode de temps-de-vol a basse energie (0-15 kev)

Energy Technology Data Exchange (ETDEWEB)

Chevillon-Pitollat, P L [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-01-01

Resonance parameters of Cu (0-15 keV) and Ba (0-1000 eV) have been determined, using the time-of-flight method. Spin assignment (J = I{+-}1/2) being not possible with usual capture methods, the 'sum coincident' method was used in Ba study. A careful analysis of transmission curves including interference effects between levels of the same spin afforded to assign the J value to the most of Cu resonances. Strength function values (S{sub 0}) for those nuclei I = 3/2 confirm previous results obtained for other nuclei having the same value of spin I = 3/2, i.e. S{sub 0} (J = 2) {approx_equal} 2 S{sub 0} (J = 1). Another result has to be mentioned: total radiative width exhibits large fluctuation for different isotopes of Cu and Ba. Experimental methods, specially the 'sum coincidence' one are described in detail and results are discussed in view of theoretical predictions. (author) [French] Les parametres des resonances de {sup 63}Cu et {sup 65}Cu ont ete determines dans le domaine d'energie de zero a 15 keV et ceux du baryum dans le domaine de zero a 1000 eV. Les methodes habituelles de capture n'etant pas applicables pour trouver la valeur du spin S = I{+-}1/2, la methode 'somme coincidence' fut appliquee pour l'attribution de J aux resonances du baryum tandis qu'une analyse soigneuse des courbes de transmission, tenant compte en particulier des effets d'interference entre niveaux de meme spin permettait de determiner J pour la plupart des resonances du cuivre. Les resultats trouves pour ces differents noyaux de spin I = 3/2 confirment ceux deja trouves pour d'autres noyaux I = 3/2 c'est-a-dire que la valeur de la fonction densite S{sub 0} pour J 2 est deux fois celle pour J = 1. Un autre resultat interessant est la variation de la largeur radiative totale pour les isotopes du cuivre et du baryum. Les methodes experimentales surtout la methode 'somme coincidence' sont decrites en detail et les resultats compares aux predictions theoriques. (auteur)

Tables of Shore and Fano parameters for the helium resonances 2s21S, 2p21D, and 2s 2p 1P excited in p-He collisions E/sub p/ = 33 to 150 keV

International Nuclear Information System (INIS)

Bordenave-Montesquieu, A.; Benoit-Cattin, P.; Gleizes, A.; Merchez, H.

1976-01-01

Absolute values of Shore and Fano parameters are tabulated for the helium atom 2s 2 1 S, 2p 2 1 D, and 2s 2p 1 P resonances produced by a proton beam. Observations were made on the spectra of ejected electrons. The important variation of the shape of the resonances with ejection angle is illustrated for E/sub p/ = 100 keV; the variation with proton energy is shown at 30 0

High-spin structure of the neutron-rich sup 1 sup 0 sup 9 sup , sup 1 sup 1 sup 1 sup , sup 1 sup 1 sup 3 sup sub 4 sup sub 5 Rh isotopes

CERN Document Server

Venkova, T; Bauchet, A; Deloncle, I; Astier, A; Buforn, N; Meyer, M; Prevost, A; Redon, N; Stezowski, O; Lalkovski, S; Donadille, L; Dorvaux, O; Gall, B J P; Schulz, N; Lucas, R; Minkova, A

2002-01-01

The sup 1 sup 0 sup 9 sup , sup 1 sup 1 sup 1 sup , sup 1 sup 1 sup 3 Rh nuclei have been produced as fission fragments in the fusion reaction sup 1 sup 8 O + sup 2 sup 0 sup 8 Pb at 85 MeV. Their level schemes have been built from gamma-rays detected using the Euroball IV array. High-spin states of the neutron-rich sup 1 sup 1 sup 1 sup , sup 1 sup 1 sup 3 Rh nuclei have been identified for the first time. Several rotational bands with the odd proton occupying the pi g sub 9 sub / sub 2 , pi p sub 1 sub / sub 2 and pi(g sub 7 sub / sub 2 /d sub 5 sub / sub 2) sub-shells have been observed. A band of low-energy transitions has been identified at excitation energy around 2 MeV in sup 1 sup 0 sup 9 sup , sup 1 sup 1 sup 1 Rh, which can be interpreted in terms of three-quasiparticle excitation, pi g sub 9 sub / sub 2 nu h sub 1 sub 1 sub / sub 2 nu g sub 7 sub / sub 2 /d sub 5 sub / sub 2. In addition another structure built on states located at low excitation energy (608 keV in sup 1 sup 1 sup 1 Rh, 570 keV in ...

The Energy Variation of the Sensitivity of a Polyethylene Moderated BF{sub 3} Proportional Counter

Energy Technology Data Exchange (ETDEWEB)

Fraeki, R; Leimdoerfer, M; Malmskog, S

1962-11-15

The variation with neutron energy of the sensitivity of a polyethylene moderated boron counter has been investigated experimentally at 2.3 MeV, 550 keV, 210 keV, 110 keV, 340 eV and 5 eV, and theoretically by the multigroup diffusion method in the same range. Different moderator thicknesses up to 10 cm were considered Results show good agreement between experimental and theoretical sensitivities for the keV and MeV energies, while a discrepancy of the order of a factor 2 at the most is obtained in the eV region.

Investigation on ultracold RbCs molecules in (2)0{sup +} long-range state below the Rb(5S{sub 1/2}) + Cs(6P{sub 1/2}) asymptote by high resolution photoassociation spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Yuan, Jinpeng; Ji, Zhonghua; Li, Zhonghao; Zhao, Yanting, E-mail: zhaoyt@sxu.edu.cn; Xiao, Liantuan; Jia, Suotang [State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006 (China)

2015-07-28

We present high resolution photoassociation spectroscopy of RbCs molecules in (2)0{sup +} long-range state below the Rb(5S{sub 1/2}) + Cs(6P{sub 1/2}) asymptote and derive the corresponding C{sub 6} coefficient, which is used to revise the potential energy curves. The excited state molecules are produced in a dual-species dark spontaneous force optical trap and detected by ionizing ground state molecules after spontaneous decay, using a high sensitive time-of-flight mass spectrum. With the help of resonance-enhanced two-photon ionization technique, we obtain considerable high resolution photoassociation spectrum with rovibrational states, some of which have never been observed before. By applying the LeRoy-Bernstein method, we assign the vibrational quantum numbers and deduce C{sub 6} coefficient, which agrees with the theoretical value of A{sup 1}Σ{sup +} state correlated to Rb(5S{sub 1/2}) + Cs(6P{sub 1/2}) asymptote. The obtained C{sub 6} coefficient is used to revise the long-range potential energy curve for (2)0{sup +} state, which possesses unique A − b mixing characteristic and can be a good candidate for the production of absolutely ground state molecule.

Measurement of multilayer reflectivities from 8 keV to 130 keV

DEFF Research Database (Denmark)

Hoeghoej, P.; Joensen, K. D.; Christensen, Finn Erland

1993-01-01

This paper presents measurements of specular and non-specular reflectivities of a W/Si multilayer with period d=135.1 A. Angular dispersive measurements were performed at 8.05 keY and 59.3 keY, while energy dispersive measurements were made in the range of 17 keV to 130 keY. At an incidence angle...

Sputtering of octatetraene by 15 keV C{sub 60} projectiles: Comparison of reactive interatomic potentials

Energy Technology Data Exchange (ETDEWEB)

Kanski, Michal; Maciazek, Dawid; Golunski, Mikolaj; Postawa, Zbigniew, E-mail: zbigniew.postawa@uj.edu.pl

2017-02-15

Highlights: • Probing the effect of interatomic potentials on sputtering of an octatetraene sample. • Problems with charge calculations are observed during cluster impact for ReaxFF. • COMB3 leads to a very low sputtering yield due to abrupt energy dissipation. • AIREBO is computationally the most efficient, while ReaxFF is more accurate. - Abstract: Molecular dynamics computer simulations have been used to probe the effect of the AIREBO, ReaxFF and COMB3 interatomic potentials on sputtering of an organic sample composed of octatetraene molecules. The system is bombarded by a 15 keV C{sub 60} projectile at normal incidence. The effect of the applied force fields on the total time of simulation, the calculated sputtering yield and the angular distribution of sputtered particles is investigated and discussed. It has been found that caution should be taken when simulating particles ejection from nonhomogeneous systems that undergo significant fragmentation described by the ReaxFF. In this case, the charge state of many particles is improper due to an inadequacy of a procedure used for calculating partial charges on atoms in molecules for conditions present during sputtering. A two-step simulation procedure is proposed to minimize the effect of this deficiency. There is also a possible problem with the COMB3 potential, at least at conditions present during cluster impact, as its results are very different from AIREBO or ReaxFF.

Collision cross sections of N2 by H+ impact at keV energies within time-dependent density-functional theory

Science.gov (United States)

Yu, W.; Gao, C.-Z.; Zhang, Y.; Zhang, F. S.; Hutton, R.; Zou, Y.; Wei, B.

2018-03-01

We calculate electron capture and ionization cross sections of N2 impacted by the H+ projectile at keV energies. To this end, we employ the time-dependent density-functional theory coupled nonadiabatically to molecular dynamics. To avoid the explicit treatment of the complex density matrix in the calculation of cross sections, we propose an approximate method based on the assumption of constant ionization rate over the period of the projectile passing the absorbing boundary. Our results agree reasonably well with experimental data and semi-empirical results within the measurement uncertainties in the considered energy range. The discrepancies are mainly attributed to the inadequate description of exchange-correlation functional and the crude approximation for constant ionization rate. Although the present approach does not predict the experiments quantitatively for collision energies below 10 keV, it is still helpful to calculate total cross sections of ion-molecule collisions within a certain energy range.

Experimental study of interactions of highly charged ions with atoms at keV energies: Progress report, February 16, 1987-January 15, 1988

International Nuclear Information System (INIS)

Kostroun, V.O.

1988-01-01

This report describes the progress made during the past year towards the understanding of the behavior of electron beam ion sources and using the sources constructed in this laboratory to investigate interactions of highly charged ions with atoms at keV energies. The operational status of the two sources in use, CEBIS I and CEBIS II is described. At present, the sources are producing beams of bare, hydrogen and helium like ions of C, N, and O, and argon ions up to Ar 13+ with peak current pulses in the electric nanoampere range. Some of the problems encountered in the development of the sources and their resolution are discussed, and a brief description of experimental apparatus and ion beam transport line is presented. Experiments in progress are described

The Half Life of the 53 keV Level in {sup 197}Pt

Energy Technology Data Exchange (ETDEWEB)

Malmskog, S G

1967-02-15

The half life of the recently proposed 53 keV level in {sup 197}Pt has been measured to 18.5 {+-} 1.5 nsec using the delayed coincidence technique. This level, which is identified with the f{sub 5/2} single particle state, decays directly to the p{sub 1/2} ground state in {sup 197}Pt. The reduced E2 transition probability for this 53 keV transition has been deduced and compared with the results obtained for the corresponding transitions in other Pt, Hg, and Pb isotopes and with the theoretical predictions by Sorensen and by Wahlborn and Martinson.

Spatial resolution measurements of the advanced radiographic capability x-ray imaging system at energies relevant to Compton radiography

Energy Technology Data Exchange (ETDEWEB)

Hall, G. N., E-mail: hall98@llnl.gov; Izumi, N.; Landen, O. L.; Tommasini, R.; Holder, J. P.; Hargrove, D.; Bradley, D. K.; Lumbard, A.; Cruz, J. G.; Piston, K.; Bell, P. M.; Carpenter, A. C.; Palmer, N. E.; Felker, B.; Rekow, V.; Allen, F. V. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); Lee, J. J.; Romano, E. [National Security Technologies LLC, 161 S Vasco Rd., Livermore, California 94551 (United States)

2016-11-15

Compton radiography provides a means to measure the integrity, ρR and symmetry of the DT fuel in an inertial confinement fusion implosion near peak compression. Upcoming experiments at the National Ignition Facility will use the ARC (Advanced Radiography Capability) laser to drive backlighter sources for Compton radiography experiments and will use the newly commissioned AXIS (ARC X-ray Imaging System) instrument as the detector. AXIS uses a dual-MCP (micro-channel plate) to provide gating and high DQE at the 40–200 keV x-ray range required for Compton radiography, but introduces many effects that contribute to the spatial resolution. Experiments were performed at energies relevant to Compton radiography to begin characterization of the spatial resolution of the AXIS diagnostic.

A laboratory 8 keV transmission full-field x-ray microscope with a polycapillary as condenser for bright and dark field imaging

Energy Technology Data Exchange (ETDEWEB)

Baumbach, S., E-mail: baumbach@rheinahrcampus.de; Wilhein, T. [Institute for X-Optics, University of Applied Sciences Koblenz, RheinAhrCampus Remagen, Joseph-Rovan-Allee 2, D-53424 Remagen (Germany); Kanngießer, B.; Malzer, W. [Institute for Optics and Atomic Physics, Technical University of Berlin, Hardenbergstrasse 36, D-10623 Berlin (Germany); Stiel, H. [Max-Born-Institute, Max-Born-Strasse 2A, D-12489 Berlin (Germany)

2015-08-15

This article introduces a laboratory setup of a transmission full-field x-ray microscope at 8 keV photon energy. The microscope operates in bright and dark field imaging mode with a maximum field of view of 50 μm. Since the illumination geometry determines whether the sample is illuminated homogeneously and moreover, if different imaging methods can be applied, the condenser optic is one of the most significant parts. With a new type of x-ray condenser, a polycapillary optic, we realized bright field imaging and for the first time dark field imaging at 8 keV photon energy in a laboratory setup. A detector limited spatial resolution of 210 nm is measured on x-ray images of Siemens star test patterns.

Mechanical design and construction of a 200 mA, 100 keV, DC, negative ion accelerator

International Nuclear Information System (INIS)

Purgalis, P.; Anderson, O.A.; Cooper, W.S.; Cummings, C.; Koehler, G.W.; Matuk, C.A.; Wells, R.P.

1987-01-01

A volume production source and a 100 keV, dc, accelerator together with an additional, modular, 100 keV, electro static focused accelerator provide a starting point for a high energy H - /D - beamline (200 keV to 800 keV), intended for fusion energy applications. The 100 keV accelerator tests started in June 1987. The mechanical design and construction of the accelerator is described

Hard X-ray Microscopy with sub 30 nm Spatial Resolution

International Nuclear Information System (INIS)

Tang, M.-T.; Song, Y.-F.; Yin, G.-C.; Chen, J.-H.; Chen, Y.-M.; Liang, Keng S.; Chen, F.-R.; Duewer, F.; Yun Wenbing

2007-01-01

A transmission X-ray microscope (TXM) has been installed at the BL01B beamline at National Synchrotron Radiation Research Center in Taiwan. This state-of-the-art TXM operational in a range 8-11 keV provides 2D images and 3D tomography with spatial resolution 60 nm, and with the Zernike-phase contrast mode for imaging light materials such as biological specimens. A spatial resolution of the TXM better than 30 nm, apparently the best result in hard X-ray microscopy, has been achieved by employing the third diffraction order of the objective zone plate. The TXM has been applied in diverse research fields, including analysis of failure mechanisms in microelectronic devices, tomographic structures of naturally grown photonic specimens, and the internal structure of fault zone gouges from an earthquake core. Here we discuss the scope and prospects of the project, and the progress of the TXM in NSRRC

The sapphire backscattering monochromator at the Dynamics beamline P01 of PETRA III

Energy Technology Data Exchange (ETDEWEB)

Alexeev, P., E-mail: pavel.alexeev@desy.de [Deutsches Elektronen-Synchrotron DESY (Germany); Asadchikov, V. [Russian Academy of Sciences, A.V. Shubnikov Institute of Crystallography (Russian Federation); Bessas, D. [European Synchrotron Radiation Facility (France); Butashin, A.; Deryabin, A. [Russian Academy of Sciences, A.V. Shubnikov Institute of Crystallography (Russian Federation); Dill, F.-U.; Ehnes, A.; Herlitschke, M. [Deutsches Elektronen-Synchrotron DESY (Germany); Hermann, R. P.; Jafari, A. [JARA-FIT, Jülich Centre for Neutron Science JCNS and Peter Grünberg Institut PGI (Germany); Prokhorov, I. [Kaluga Branch of Shubnikov Institute of Crystallography RAS, Research Center for Space Materials Science (Russian Federation); Roshchin, B. [Russian Academy of Sciences, A.V. Shubnikov Institute of Crystallography (Russian Federation); Röhlsberger, R.; Schlage, K.; Sergueev, I.; Siemens, A.; Wille, H.-C., E-mail: hans.christian.wille@desy.de [Deutsches Elektronen-Synchrotron DESY (Germany)

2016-12-15

We report on a high resolution sapphire backscattering monochromator installed at the Dynamics beamline P01 of PETRA III. The device enables nuclear resonance scattering experiments on Mössbauer isotopes with transition energies between 20 and 60 keV with sub-meV to meV resolution. In a first performance test with {sup 119}Sn nuclear resonance at a X-ray energy of 23.88 keV an energy resolution of 1.34 meV was achieved. The device extends the field of nuclear resonance scattering at the PETRA III synchrotron light source to many further isotopes like {sup 151}Eu, {sup 149}Sm, {sup 161}Dy, {sup 125}Te and {sup 121}Sb.

Characterization and optimization of laser-driven electron and photon sources in keV and MeV energy ranges

International Nuclear Information System (INIS)

Bonnet, Thomas

2013-01-01

This work takes place in the framework of the characterization and the optimization of laser-driven electron and photon sources. With the goal of using these sources for nuclear physics experiments, we focused on 2 energy ranges: one around a few MeV and the other around a few tens of keV. The first part of this work is thus dedicated to the study of detectors routinely used for the characterization of laser-driven particle sources: Imaging Plates. A model has been developed and is fitted to experimental data. Response functions to electrons, photons, protons and alpha particles are established for SR, MS and TR Fuji Imaging Plates for energies ranging from a few keV to several MeV. The second part of this work present a study of ultrashort and intense electron and photon sources produced in the interaction of a laser with a solid or liquid target. An experiment was conducted at the ELFIE facility at LULI where beams of electrons and photons were accelerated up to several MeV. Energy and angular distributions of the electron and photons beams were characterized. The sources were optimized by varying the spatial extension of the plasma at both the front and the back end of the initial target position. In the optimal configuration of the laser-plasma coupling, more than 1011 electrons were accelerated. In the case of liquid target, a photon source was produced at a high repetition rate on an energy range of tens of keV by the interaction of the AURORE Laser at CELIA (10 16 W.cm -2 ) and a melted gallium target. It was shown that both the mean energy and the photon number can be increased by creating gallium jets at the surface of the liquid target with a pre-pulse. A physical interpretation supported by numerical simulations is proposed. (author)

On the 17-keV neutrino

International Nuclear Information System (INIS)

Hime, A.

1993-04-01

A brief review on the status of the 17-keV neutrino is presented. Several different experiments found spectral distortions which were consistently interpreted as evidence for a heavy neutrino admixture in β decay. Recent experiments, however, rule out the existence of a 17-keV neutrino as well as escaping criticisms of earlier null results. Moreover, the majority of positive results have been reinterpreted in terms of instrumental effects, despite the need for a different explanation in each case. Anomalies persist in the low energy region of the tritium spectrum which deserve further investigation

Linear attenuation coefficients of tissues from 1 keV to 150 keV

Science.gov (United States)

Böke, Aysun

2014-09-01

The linear attenuation coefficients and three interaction processes have been computed for liver, kidney, muscle, fat and for a range of x-ray energies from 1 keV to 150 keV. Molecular photoelectric absorption cross sections were calculated from atomic cross section data. Total coherent (Rayleigh) and incoherent (Compton) scattering cross sections were obtained by numerical integration over combinations of F2m(x) with the Thomson formula and Sm(x) with the Klein-Nishina formula, respectively. For the coherent (Rayleigh) scattering cross section calculations, molecular form factors were obtained from recent experimental data in the literature for values of xelements involved in tissue composition is 5 for liver, 47 for kidney, 44 for muscle and 3 for fat. The results are compared with previously published experimental and theoretical linear attenuation coefficients. In general, good agreement is obtained. The molecular form factors and scattering functions and cross sections are incorporated into a Monte Carlo program. The energy distributions of x-ray photons scattered from tissues have been simulated and the results are presented.

Ionization effects on Cu(In, Ga)Se{sub 2} thin-film solar cells

Energy Technology Data Exchange (ETDEWEB)

Kawakita, Shirou; Imaizumi, Mitsuru [Japan Aerospace Exploration Agency, 2-1-1 Sengen, Tsukuba, Ibaraki 305-0031 (Japan); Ishizuka, Shogo; Shibata, Hajime [Institute of National Advanced Industrial Science and Technology, 1-1 Umezono, Tsukuba 305-8568 (Japan); Okuda, Shuichi [Osaka Prefecture University, 1-2 Gakuenmachi, Sakai 599-8570 (Japan)

2017-06-15

Cu (In, Ga) Se{sub 2} (CIGS) solar cells were irradiated with 60, 100, and 250 keV electrons to reveal the characteristics of radiation induced defects. Electrons with less than 200 keV energy cannot generate any displacement defects in CIGS materials. In addition, a low amount of the electrons can improve the roll-over behavior in current-voltage characteristics of CIGS solar cells. However, the deterioration of the electrical performance in CIGS solar cells irradiated with a high amount of electrons was observed. The deterioration rate on the cells irradiated with lower-energy electrons was higher than that induced by electrons with higher-energy. The degradation curve of J{sub SC} based on the ionizing dose estimated from the ionizing energy loss model does not depend on the energy of electrons. Therefore, it implies that the electrons can degrade CIGS solar cells due to the ionization effect. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

One dimensional detector for X-ray diffraction with superior energy resolution based on silicon strip detector technology

International Nuclear Information System (INIS)

Dąbrowski, W; Fiutowski, T; Wiącek, P; Fink, J; Krane, H-G

2012-01-01

1-D position sensitive X-ray detectors based on silicon strip detector technology have become standard instruments in X-ray diffraction and are available from several vendors. As these devices have been proven to be very useful and efficient further improvement of their performance is investigated. The silicon strip detectors in X-ray diffraction are primarily used as counting devices and the requirements concerning the spatial resolution, dynamic range and count rate capability are of primary importance. However, there are several experimental issues in which a good energy resolution is important. The energy resolution of silicon strip detectors is limited by the charge sharing effects in the sensor as well as by noise of the front-end electronics. The charge sharing effects in the sensor and various aspects of the electronics, including the baseline fluctuations, which affect the energy resolution, have been analyzed in detail and a new readout concept has been developed. A front-end ASIC with a novel scheme of baseline restoration and novel interstrip logic circuitry has been designed. The interstrip logic is used to reject the events resulting in significant charge sharing between neighboring strips. At the expense of rejecting small fraction of photons entering the detector one can obtain single strip energy spectra almost free of charge sharing effects. In the paper we present the design considerations and measured performance of the detector being developed. The electronic noise of the system at room temperature is typically of the order of 70 el rms for 17 mm long silicon strips and a peaking time of about 1 μs. The energy resolution of 600 eV FWHM has been achieved including the non-reducible charge sharing effects and the electronic noise. This energy resolution is sufficient to address a common problem in X-ray diffraction, i.e. electronic suppression of the fluorescence radiation from samples containing iron or cobalt while irradiated with 8.04 keV

Measurement of attenuation coefficients for bone, muscle, fat and water at 140, 364 and 662keV γ-ray energies

International Nuclear Information System (INIS)

Akar, A.; Baltas, H.; Cevik, U.; Korkmaz, F.; Okumusoglu, N.T.

2006-01-01

The half-value thicknesses, linear and mass attenuation coefficients of biological samples such as bone, muscle, fat and water have been measured at 140, 364 and 662keV γ-ray energies by using the ATOMLAB TM -930 medical spectrometer. The γ-rays were obtained from 99m Tc, 131 I and 137 Cs γ-ray point sources. Also theoretical calculations have been performed in order to obtain the half-value thicknesses and, mass and linear attenuation coefficients at photon energies 0.001keV-20MeV for bone, muscle and water samples. The calculated value and the experimental results of this work and the other results in literature are found to be in good agreement

Diffusion modelling of low-energy ion-implanted BF{sub 2} in crystalline silicon: Study of fluorine vacancy effect on boron diffusion

Energy Technology Data Exchange (ETDEWEB)

Marcon, J. [Laboratoire Electronique Microtechnologie et Instrumentation (LEMI), University of Rouen, 76821 Mont Saint Aignan (France)], E-mail: Jerome.Marcon@univ-rouen.fr; Merabet, A. [Laboratoire de Physique et Mecanique des Materiaux Metalliques, Departement d' O.M.P., Faculte des Sciences de l' Ingenieur, Universite de Setif, 19000 Setif (Algeria)

2008-12-05

We have investigated and modelled the diffusion of boron implanted into crystalline silicon in the form of boron difluoride BF{sub 2}{sup +}. We have used published data for BF{sub 2}{sup +} implanted with an energy of 2.2 keV in crystalline silicon. Fluorine effects are considered by using vacancy-fluorine pairs which are responsible for the suppression of boron diffusion in crystalline silicon. Following Uematsu's works, the simulations satisfactory reproduce the SIMS experimental profiles in the 800-1000 deg. C temperature range. The boron diffusion model in silicon of Uematsu has been improved taking into account the last experimental data.

Sub-second pulsations simultaneously observed at microwaves and hard X-rays in a solar burst

International Nuclear Information System (INIS)

Takakura, T.; Degaonkar, S.S.; Nitta, N.; Ohki, N.

1982-11-01

Sub-second time structures have been found in the emissions during solar bursts in mm-waves and, independently, in hard X-rays. However, simultaneous observations of such fast time structure in mm radio and X-ray ranges has not been available so far. Accordingly, coordinated observations of solar bursts in November 1981 with a high time resolution of a few milliseconds were planned. The hard X-rays (30-40 KeV were observed with hard X-ray monitor (HXM) aboard the Hinotori Satellite with a time resolution of 7.81 ms and the radio emissions were observed on the ground with 45ft dish at Itapetinga Radio Observatory with a high time resolution (1 ms) and high sensitivities at 22 GHz and 44 GHz, supplemented by a patrol observation at 7 GHz with time resolution of 100 ms. The pulsations repeated with a period of about 300 ms. The physical implication of the good correlation is not clear at this stage, but it may give a clue to the understanding of the high energy phenomena occuring during the solar flares. (Author) [pt

Molecular dynamics studies of displacement cascades in Fe-Y{sub 2}TiO{sub 5} system

Energy Technology Data Exchange (ETDEWEB)

Dholakia, Manan, E-mail: manan@igcar.gov.in; Chandra, Sharat; Jaya, S. Mathi [Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, TN (India)

2016-05-23

The effect of displacement cascade on Fe-Y{sub 2}TiO{sub 5} bilayer is studied using classical molecular dynamics simulations. Different PKA species – Fe, Y, Ti and O – with the same PKA energy of 8 keV are used to produce displacement cascades that encompass the interface. It is shown that Ti atom has the highest movement in the ballistic regime of cascades which can lead to Ti atoms moving out of the oxide clusters into the Fe matrix in ODS alloys.

Effect of energy window on cardiac ejection fraction

International Nuclear Information System (INIS)

Bacharach, S.L.; Green, M.V.; Bonow, R.O.; Findley, S.L.; Daube-Witherspoon, M.E.; Larson, S.M.

1988-01-01

ECG gated gamma-ray energy spectra from the left ventricle were created each 50 msec during the cardiac cycle. Nine of ten subjects were studied with a nonimaging Nal probe, and the tenth with a high-resolution Germanium detector. Placing multiple energy windows over the energy spectra, EF was found to vary with the energy window selected. Moving a 20% window across the photopeak produced a roughly linear increase in EF with energy (2.3 EF units per 10 keV increase in energy) in eight of the ten subjects. Dividing the photopeak into a low (126-140 keV) and high-energy (140-154 keV) portion gave significantly different EFs (high energy exceeding low energy by 17%). Increasing the width of a narrow window centered about the photopeak produced negligible change in EF. Examining the energy spectra showed that the small-angle scattered radiation (126-139 keV) was proportionately greater at end systole than at end diastole, after normalizing the spectra to the same photopeak area

Gamma-line intensity difference method for sup 1 sup 1 sup 7 sup m Sn at high resolution

CERN Document Server

Remeikis, V; Mazeika, K

1998-01-01

The method for detection of small differences in the gamma-spectrum line intensity for the radionuclide in different environments has been developed for measurements at high resolution. The experiments were realized with the pure germanium planar detector. Solution of the methodical problems allowed to measure the relative difference DELTA IOTA subgamma/IOTA subgamma=(3.4+-1.5)*10 sup - sup 4 of the sup 1 sup 1 sup 7 sup m Sn 156.02 keV gamma-line intensity for the radionuclide in SnO sub 2 with respect to SnS from the difference in the gamma-spectra. The error of the result is caused mainly by the statistical accuracy. It is limited by the highest counting rate at sufficiently high energy resolution and relatively short half-life of sup 1 sup 1 sup 7 sup m Sn. (author)

Changes in measured size of atherosclerotic plaque calcifications in dual-energy CT of ex vivo carotid endarterectomy specimens: effect of monochromatic keV image reconstructions

International Nuclear Information System (INIS)

Mannelli, Lorenzo; Mitsumori, Lee M.; Ferguson, Marina; Xu, Dongxiang; Chu, Baocheng; Branch, Kelley R.; Shuman, William P.; Yuan, Chun

2013-01-01

The aim of this study was to compare the size of the calcifications measured on the different keV images to a histological standard. Five ex vivo carotid endarterectomy (CEA) specimens were imaged with a dual-energy CT. CT images were reconstructed at different monochromatic spectral energies (40, 60, 77, 80, 100, 120, 140 keV). Cross-sectional area of the plaque calcifications present on each CT image was measured. The histological calcium areas on each corresponding CEA specimen were traced manually on digitised images of Toluidine Blue/Basic Fuchsin stained plastic sections. The CT images and corresponding histology sections were matched. The CT-derived calcium areas on each keV image were compared to the calcified area measurements by histology. A total of 107 histology sections were matched to corresponding CT images. The average calcified area per section by histology was 7.6 ± 7 mm 2 (range 0-26.4 mm 2 ). There was no significant difference between the calcified areas measured by histology and those measured on CT-virtual monochromatic spectral (VMS) reconstructed images at 77 keV (P = 0.08), 80 keV (P = 0.20) and 100 keV (P = 0.14). Calcium area measured on the 80 keV image set was most comparable to the amount of calcium measured by histology. (orig.)

The 93.54 keV level in {sup 91}Sr, and Evidence for 3-neutron States Above N=50

Energy Technology Data Exchange (ETDEWEB)

Malmskog, S G; McDonald, J

1970-01-15

An intense transition of 93.54 keV is seen in the decay of {sup 91}Rb ( T{sub 1/2} = 58.2 sec), and is assigned to a level at this energy in {sup 91}Sr. The level energy is accurately measured with a Ge(Li) detector. The half-life of the level is found by direct timing to be (88 {+-} 3) ns. Measurement of the conversion electron spectrum with a long lens spectrometer has enabled the E2/M1 ratio to be deduced. The nature of the ground and excited states of N 53 nuclei is discussed in terms of configurations of 2d{sub 5/2} neutrons, and compared with the behaviour of the N = 55 and 57 ruthenium nuclei.

Dissociation of deep-core-excited CH{sub 3}Cl

Energy Technology Data Exchange (ETDEWEB)

Hansen, D.L.; Martin, R.; Vanderford, B. [Univ. of Nevada, Las Vegas, NV (United States)] [and others

1997-04-01

Using x-rays from B.L. 9.3.1, a space-focused time-of-flight (TOF) was used to study photofragmentation of CH{sub 3}Cl following excitation in the neighborhood of the Cl K-shell threshold ({approximately} 2.8 keV). Multi-ion coincidence measurements were used to search for selective dissociation of specific bonds in the molecule. Such selectivity has been observed for excitation near outer-core-level thresholds (e.g., Cl 2p), but this is the first study in deep core levels, where very-short core-hole lifetimes and Auger cascade effects may influence fragmentation. Both high-resolution time-of-flight spectroscopy and multi-coincidence photoelectron-photoion-photoion (PE-PIPICO), as well as photoelectron-photoion-photoion-photoion (PE3PICO) measurements were performed. Dramatic changes in the line shapes for different fragment ions are observed as a function of the excitation energy, and are attributed to selective dissociation of the CH{sub 3}Cl molecule along the C-Cl bond. In addition, pronounced angular distributions of the ejected ions are observed on resonance.

Investigation of the 14N/d,α/12C reaction at Esub(d)=640-310 keV deuteron energies

International Nuclear Information System (INIS)

Bakr, M.H.S.; Hunyadi, I.; Schlenk, G.; Somogyi, G.; Valek, A.

1974-01-01

Angular distributions of the α 0 , α 1 , α 2 , and α 3 groups from the 14 N/d,α/ 12 C reaction have been measured at deuteron energies 640, 510, and 350 keV using solid state track detectors. Semiconductor detector was used to measure the excitation functions of the α 0 and α 1 groups from the same reaction in the energy range 640-310 keV at THETAsub(lab)=90 0 . The absolute cross-section values are given for the alpha groups investigated. The experimentally obtained angular distributions have been analysed in terms of Legendre polynomials. The measured relative intensity ratios of the α 0 , α 1 , and α 3 groups could be reproduced by a simple calculation assuming statistical compound reaction mechanism. (B.T.)

Investigating energy deposition within cell populations using Monte Carlo simulations.

Science.gov (United States)

Oliver, Patricia A K; Thomson, Rowan M

2018-06-27

In this work, we develop multicellular models of healthy and cancerous human soft tissues, which are used to investigate energy deposition in subcellular targets, quantify the microdosimetric spread in a population of cells, and determine how these results depend on model details. Monte Carlo (MC) tissue models combining varying levels of detail on different length scales are developed: microscopically-detailed regions of interest (>1500 explicitly-modelled cells) are embedded in bulk tissue phantoms irradiated by photons (20 keV to 1.25 MeV). Specific energy (z; energy imparted per unit mass) is scored in nuclei and cytoplasm compartments using the EGSnrc user-code egs_chamber; specific energy mean, <z>, standard deviation, σ<sub>z>, and distribution, f(z,D), are calculated for a variety of macroscopic doses, D. MC-calculated f(z,D) are compared with normal distributions having the same mean and standard deviation. For mGy doses, there is considerable variation in energy deposition (microdosimetric spread) throughout a cell population: e.g., for 30 keV photons irradiating melanoma with 7.5 μm cell radius and 3 μm nuclear radius, σ<sub>z>/<z> for nuclear targets is 170%, and the fraction of nuclei receiving no energy deposition, f<sub>z=0sub>, is 0.31 for a dose of 10 mGy. If cobalt-60 photons are considered instead, then σ<sub>z>/<z> decreases to 84%, and f<sub>z=0sub> decreases to 0.036. These results correspond to randomly arranged cells with cell/nucleus sizes randomly sampled from a normal distribution with a standard deviation of 1 μm. If cells are arranged in a hexagonal lattice and cell/nucleus sizes are uniform throughout the population, then σ<sub>z>/<z> decreases to 106% and 68% for 30 keV and cobalt-60,respectively; f<sub>z=0sub

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)

The dynamic range of ultra-high-resolution cryogenic gamma-ray spectrometers

Energy Technology Data Exchange (ETDEWEB)

Ali, Shafinaz [Advanced Detector Group, Lawrence Livermore National Laboratory, 7000 East Avenue, L-270, Livermore, CA 94550 (United States); Terracol, Stephane F. [Advanced Detector Group, Lawrence Livermore National Laboratory, 7000 East Avenue, L-270, Livermore, CA 94550 (United States); Drury, Owen B. [Advanced Detector Group, Lawrence Livermore National Laboratory, 7000 East Avenue, L-270, Livermore, CA 94550 (United States); Friedrich, Stephan [Advanced Detector Group, Lawrence Livermore National Laboratory, 7000 East Avenue, L-270, Livermore, CA 94550 (United States)]. E-mail: friedrich1@llnl.gov

2006-04-15

We are developing high-resolution cryogenic gamma-ray spectrometers for nuclear science and non-proliferation applications. The gamma-ray detectors are composed of a bulk superconducting Sn foil absorber attached to a multilayer Mo/Cu transition-edge sensor (TES). The energy resolution of a detector with a 1x1x0.25 mm{sup 3} Sn absorber is 50-90 eV FWHM for {gamma}-rays up to 100 keV, and it decreases for larger absorbers. Here, we present the detector performance for different absorber volumes, and discuss the trade-offs between energy resolution and dynamic range.

The Dynamic Range of Ultra-High Resolution Cryogenic Gamma-ray Spectrometers

International Nuclear Information System (INIS)

Ali, S; Terracol, S F; Drury, O B; Friedrich, S

2005-01-01

We are developing high-resolution cryogenic gamma-ray spectrometers for nuclear science and non-proliferation applications. The gamma-ray detectors are composed of a bulk superconducting Sn foil absorber attached to multilayer Mo/Cu transition-edge sensors (TES). The energy resolution achieved with a 1 x 1 x 0.25 mm 3 Sn absorber is 50 -90eV for γ-rays up to 100 keV and it decreases for large absorber sizes. We discuss the trade-offs between energy resolution and dynamic range, as well as development of TES arrays for higher count rates and better sensitivity

Design, development and operational experience of radio frequency (RF) power systems/technologies for LEHIPA and 400 keV RFQ

International Nuclear Information System (INIS)

Pande, Manjiri; Shrotriya, Sandip; Patel, Niranjan

2015-01-01

The important technology development for ion accelerators of 'accelerator driven sub critical reactor system (ADS) is being done under the program of Department of Atomic Energy (DAE). In BARC (BARC) of DAE, technology development of 400 keV radio frequency quadrupole (RFQ) accelerator is done and a 20 MeV - low energy high intensity proton accelerator (LEHIPA) is under development. A 400 KeV deuteron RFQ accelerator is already developed at BARC and its 60 kW radio frequency (RF) power system required for beam acceleration has been designed, developed and tested both in CW mode and in pulse mode for full power of 60 leW. It has been successfully integrated with RFQ via 6-1/8'', 50 ohm RF transmission line, to accelerate proton beam up to 200 KeV energy and deuteron beam to 400 KeV energy. LEHIPA requires about 3 MW of RF power for its operation. So, three 1 MW, 352 MHz RF systems based on klystron will be developed for RFQ and two DTLs. The klystron based RF system for 3 MeV RFQ is under commissioning. Its various subsystems like energy less and insulated gate bipolar transistor (IGBT) based high voltage and low voltage bias supplies, a critical and fast protection and control system - handling various types of field signals, fast acting hard wired instrumentation circuits for critical signals, 100 kV crowbar with its circuits, pulsing circuits and RF circuits have been successfully designed, developed and integrated with klystron. Latest technology development of solid state RF amplifiers at 325 MHz and 350 MHz for normal and super conducting accelerators has attained a certain power level. This paper will discuss all these high power RF systems in detail. (author)

Low-energy X-ray and gamma spectrometry using silicon photodiodes

International Nuclear Information System (INIS)

Silva, Iran Jose Oliveira da

2000-08-01

The use of semiconductor detectors for radiation detection has increased in recent years due to advantages they present in comparison to other types of detectors. As the working principle of commercially available photodiodes is similar to the semiconductor detector, this study was carried out to evaluate the use of Si photodiodes for low energy x-ray and gamma spectrometry. The photodiodes investigated were SFH-205, SFH-206, BPW-34 and XRA-50 which have the following characteristics: active area of 0,07 cm 2 and 0,25 cm 2 , thickness of the depletion ranging from 100 to 200 μm and junction capacitance of 72 pF. The photodiode was polarized with a reverse bias and connected to a charge sensitive pre-amplifier, followed by a amplifier and multichannel pulse analyzer. Standard radiation source used in this experiment were 241 Am, 109 Cd, 57 Co and 133 Ba. The X-ray fluorescence of lead and silver were also measured through K- and L-lines. All the measurements were made with the photodiodes at room temperature.The results show that the responses of the photodiodes very linear by the x-ray energy and that the energy resolution in FWHM varied between 1.9 keV and 4.4 keV for peaks corresponding to 11.9 keV to 59 keV. The BPW-34 showed the best energy resolution and the lower dark current. The full-energy peak efficiency was also determined and it was observed that the peak efficiency decreases rapidly above 50 keV. The resolution and efficiency are similar to the values obtained with other semiconductor detectors, evidencing that the photodiodes used in that study can be used as a good performance detector for low energy X-ray and gamma spectrometry. (author)

A compact sub-Kelvin ultrahigh vacuum scanning tunneling microscope with high energy resolution and high stability.

Science.gov (United States)

Zhang, L; Miyamachi, T; Tomanić, T; Dehm, R; Wulfhekel, W

2011-10-01

We designed a scanning tunneling microscope working at sub-Kelvin temperatures in ultrahigh vacuum (UHV) in order to study the magnetic properties on the nanoscale. An entirely homebuilt three-stage cryostat is used to cool down the microscope head. The first stage is cooled with liquid nitrogen, the second stage with liquid (4)He. The third stage uses a closed-cycle Joule-Thomson refrigerator of a cooling power of 1 mW. A base temperature of 930 mK at the microscope head was achieved using expansion of (4)He, which can be reduced to ≈400 mK when using (3)He. The cryostat has a low liquid helium consumption of only 38 ml/h and standing times of up to 280 h. The fast cooling down of the samples (3 h) guarantees high sample throughput. Test experiments with a superconducting tip show a high energy resolution of 0.3 meV when performing scanning tunneling spectroscopy. The vertical stability of the tunnel junction is well below 1 pm (peak to peak) and the electric noise floor of tunneling current is about 6fA/√Hz. Atomic resolution with a tunneling current of 1 pA and 1 mV was achieved on Au(111). The lateral drift of the microscope at stable temperature is below 20 pm/h. A superconducting spilt-coil magnet allows to apply an out-of-plane magnetic field of up to 3 T at the sample surface. The flux vortices of a Nb(110) sample were clearly resolved in a map of differential conductance at 1.1 K and a magnetic field of 0.21 T. The setup is designed for in situ preparation of tip and samples under UHV condition.

Different strain relaxation mechanisms in strained Si/Si sub 1 sub - sub x Ge sub x /Si heterostructures by high dose B sup + and BF sub 2 sup + doping

CERN Document Server

Chen, C C; Zhang, S L; Zhu, D Z; Vantomme, A

2002-01-01

Strained Si/Si sub 0 sub . sub 8 Ge sub 0 sub . sub 2 /Si heterostructures are implanted at room temperature with 7.5 keV B sup + and 33 keV BF sub 2 sup + ions to a high dose of 2x10 sup 1 sup 5 ions/cm sup 2 , respectively. The samples are subsequently subjected to three-step anneals (spacer anneal, oxidation anneal and rapid thermal anneal), which are used to simulate a real fabrication process of SiGe-based MOSFET devices. The damage induced by implantation and its recovery are characterized by 2 MeV sup 4 He sup + RBS/channeling spectrometry. A damage layer on the surface is induced by B sup + implantation, but BF sup + sub 2 ion implantation amorphizes the surface of Si/Si sub 0 sub . sub 8 Ge sub 0 sub . sub 2 /Si heterostructure. Channeling angular scans along the axial direction demonstrate that the strain stored in the SiGe layer could be nearly completely retained for the B sup + implanted and subsequently annealed sample. However, the strain in the BF sub 2 sup + implanted/annealed SiGe layer has...

Self-attenuation correction factors for bioindicators measured by γ spectrometry for energies <100keV

International Nuclear Information System (INIS)

Manduci, L.; Tenailleau, L.; Trolet, J.L.; De Vismes, A.; Lopez, G.; Piccione, M.

2010-01-01

The mass attenuation coefficients for a number of marine and terrestrial bioindicators were measured using γ spectrometry for energies between 22 and 80 keV. These values were then used to find the correction factor k for the apparent radioactivity. The experimental results were compared with a Monte Carlo simulation performed using PENELOPE in order to evaluate the reliability of the simplified calculation and to determine the correction factors.

Superconducting energy gap of BaPb/sub 1-//sub x/Bi/sub x/O3

International Nuclear Information System (INIS)

Schlesinger, Z.; Collins, R.T.; Scott, B.A.; Calise, J.A.

1988-01-01

We report the first infrared measurement of the superconducting energy gap of BaPb/sub 1-//sub x/Bi/sub x/O 3 . In our polycrystalline samples with T/sub c/≅9.5 K (x≅0.2) we obtain 2Δ≅3.2kT/sub c/, roughly in agreement with the weak-coupling Bardeen-Cooper-Schrieffer prediction, 2Δ = 3.5kT/sub c/, and with tunneling measurements of the gap. We do not observe any structure above the gap energy associated with strong coupling

Uncertainty in relative energy resolution measurements

International Nuclear Information System (INIS)

Volkovitsky, P.; Yen, J.; Cumberland, L.

2007-01-01

We suggest a new method for the determination of the detector relative energy resolution and its uncertainty based on spline approximation of experimental spectra and a statistical bootstrapping procedure. The proposed method is applied to the spectra obtained with NaI(Tl) scintillating detectors and 137 Cs sources. The spectrum histogram with background subtracted channel-by-channel is modeled by cubic spline approximation. The relative energy resolution (which is also known as pulse height resolution and energy resolution), defined as the full-width at half-maximum (FWHM) divided by the value of peak centroid, is calculated using the intercepts of the spline curve with the line of the half peak height. The value of the peak height is determined as the point where the value of the derivative goes to zero. The residuals, which are normalized over the square root of counts in a given bin (y-coordinate), obey the standard Gaussian distribution. The values of these residuals are randomly re-assigned to a different set of y-coordinates where a new 'pseudo-experimental' data set is obtained after 'de-normalization' of the old values. For this new data set a new spline approximation is found and the whole procedure is repeated several hundred times, until the standard deviation of relative energy resolution becomes stabilized. The standard deviation of relative energy resolutions calculated for each 'pseudo-experimental' data set (bootstrap uncertainty) is considered to be an estimate for relative energy resolution uncertainty. It is also shown that the relative bootstrap uncertainty is proportional to, and generally only two to three times bigger than, 1/√(N tot ), which is the relative statistical count uncertainty (N tot is the total number of counts under the peak). The newly suggested method is also applicable to other radiation and particle detectors, not only for relative energy resolution, but also for any of the other parameters in a measured spectrum, like

Energy dependence of effective atomic numbers for photon energy absorption and photon interaction: Studies of some biological molecules in the energy range 1 keV-20 MeV

DEFF Research Database (Denmark)

Manohara, S.R.; Hanagodimath, S.M.; Gerward, Leif

2008-01-01

Effective atomic numbers for photon energy absorption, Z(PEA,eff), and for photon interaction, Z(PI,eff), have been calculated by a direct method in the photon-energy region from 1 keV to 20 MeV for biological molecules, such as fatty acids (lauric, myristic, palmitic, stearic, oleic, linoleic......, linolenic, arachidonic, and arachidic acids), nucleotide bases (adenine, guanine, cytosine, uracil, and thymine), and carbohydrates (glucose, sucrose, raffinose, and starch). The Z(PEA, eff) and Z(PI, eff) values have been found to change with energy and composition of the biological molecules. The energy...

Study on the thermoluminescent properties of K{sub 2}YF{sub 5} and K{sub 2}GdF{sub 5} crystals doped with optically active trivalent ions for gamma and neutrons dosimetry; Estudo das propriedades termoluminescentes de cristais de K{sub 2}YF{sub 5} e K{sub 2}GdF{sub 5} dopados com ions trivalentes opticamente ativos para dosimetria gama e de neutrons

Energy Technology Data Exchange (ETDEWEB)

Silva, Edna Carla da

2008-07-01

In this work, the thermoluminescent (TL) properties of both double potassium yttrium fluoride (K{sub 2}YF{sub 5}) and double potassium gadolinium fluoride (K{sub 2}GdF{sub 5}) crystals doped with optically active rare earth ions were investigated from the point of view of gamma and neutron dosimetry. Crystalline platelets with thickness of about 1 mm, synthesized under hydrothermal conditions, were irradiated in order to study TL sensitivity, as well as dose and energy response, reproducibility and fading, in terms of Ce{sup 3+}, Tb{sup 3+}, Dy{sup 3+}, e Pr{sup 3+} concentrations. The K{sub 2}YF{sub 5} crystals doped with 1.0 at por cent Dy{sup 3+} have been found to have an excellent linear TL response to X and gamma photons, in the range of 0.01 to 10 mGy. The TL output is comparable to that of CaS0{sub 4}:Mn dosemeters. The main peak at 130 deg C has been found to have a TL response for 41.1 keV X-ray energy 32 times higher than that for 662 keV gamma rays. This fact points out that the K{sub 2}Y{sub 0.99}Dy{sub 0.01}F{sub 5} crystals have great potential for X-rays diagnostic and/or industrial radiography. On the other hand, the K{sub 2}GdF{sub 5} crystals doped with 5.0 at por cent Dy{sup 3+} have been found to have the better TL response for gamma and fast neutron radiation, among the dopants studied. For gamma fields the TL response was linear for doses ranging from 0.1 to 200 mGy. The TL peak around 200 deg C can be deconvoluted into four individual peaks, all of them with linear behavior. For fast neutron radiation produced by an {sup 241}Am{sub B}e source, the TL responses for doses ranging from 0.6 to 12 mSv were also linear and comparable to that of commercial TLD-600, irradiated at same conditions. The TL emission due to neutrons was in the high temperature range, above 200 deg C. These results points out that K{sub 2}Gd{sub 0.95}Dy{sub 0.05}F{sub 5} crystals are good candidates for use in neutron dosimetry applications. (author)

Novel energy resolving x-ray pinhole camera on Alcator C-Moda)

Science.gov (United States)

Pablant, N. A.; Delgado-Aparicio, L.; Bitter, M.; Brandstetter, S.; Eikenberry, E.; Ellis, R.; Hill, K. W.; Hofer, P.; Schneebeli, M.

2012-10-01

A new energy resolving x-ray pinhole camera has been recently installed on Alcator C-Mod. This diagnostic is capable of 1D or 2D imaging with a spatial resolution of ≈1 cm, an energy resolution of ≈1 keV in the range of 3.5-15 keV and a maximum time resolution of 5 ms. A novel use of a Pilatus 2 hybrid-pixel x-ray detector [P. Kraft et al., J. Synchrotron Rad. 16, 368 (2009), 10.1107/S0909049509009911] is employed in which the lower energy threshold of individual pixels is adjusted, allowing regions of a single detector to be sensitive to different x-ray energy ranges. Development of this new detector calibration technique was done as a collaboration between PPPL and Dectris Ltd. The calibration procedure is described, and the energy resolution of the detector is characterized. Initial data from this installation on Alcator C-Mod is presented. This diagnostic provides line-integrated measurements of impurity emission which can be used to determine impurity concentrations as well as the electron energy distribution.

Medium energy ion scattering (MEIS)

International Nuclear Information System (INIS)

Dittmann, K.; Markwitz, A.

2009-01-01

This report gives an overview about the technique and experimental study of medium energy ion scattering (MEIS) as a quantitative technique to determine and analyse the composition and geometrical structure of crystalline surfaces and near surface-layers by measuring the energy and yield of the backscattered ions. The use of a lower energy range of 50 to 500 keV accelerated ions impinging onto the target surface and the application of a high-resolution electrostatic energy analyser (ESA) makes medium energy ion scattering spectroscopy into a high depth resolution and surface-sensitive version of RBS with less resulting damage effects. This report details the first steps of research in that field of measurement technology using medium energetic backscattered ions detected by means of a semiconductor radiation detector instead of an ESA. The study of medium energy ion scattering (MEIS) has been performed using the 40 keV industrial ion implanter established at GNS Sciences remodelled with supplementary high voltage insulation for the ion source in order to apply voltages up to 45 kV, extra apertures installed in the beamline and sample chamber in order to set the beam diameter accurately, and a semiconductor radiation detector. For measurement purposes a beam of positive charged helium ions accelerated to an energy of about 80 keV has been used impinging onto target surfaces of lead implanted into silicon (PbSi), scandium implanted into aluminium (ScAl), aluminium foil (Al) and glassy carbon (C). First results show that it is possible to use the upgraded industrial implanter for medium energy ion scattering. The beam of 4 He 2+ with an energy up to 88 keV has been focussed to 1 mm in diameter. The 5 nA ion beam hit the samples under 2 x 10 -8 mbar. The results using the surface barrier detector show scattering events from the samples. Cooling of the detector to liquid nitrogen temperatures reduced the electronic noise in the backscattering spectrum close to zero. A

Neutron-capture-activation cross sections of 9496Zr and 98100Mo at thermal and 30 keV energy

International Nuclear Information System (INIS)

Wyrick, J.M.; Poenitz, W.P.

1982-01-01

Neutron-capture cross sections of 94 96 Zr and 98 100 Mo were measured relative to the standard-capture cross section of gold at thermal and 30 keV neutron energies using the activation technique. The reported values are based upon available decay-scheme information

Evaluation of Multi-Channel ADCs for Gamma-Ray Spectroscopy

Science.gov (United States)

Tan, Hui; Hennig, Wolfgang; Walby, Mark D.; Breus, Dimitry; Harris, Jackson

2013-04-01

As nuclear physicists increasingly design large scale experiments with hundreds or thousands of detector channels, there are growing needs for high density readout electronics with good timing and energy resolution that at the same time offer lower cost per channel compared to existing commercial solutions. Recent improvements in the design of commercial analog to digital converters (ADCs) have resulted in a variety of multi-channel ADCs that are natural choice for designing such high density readout modules. However, multi-channel ADCs typically are designed for medical imaging/ultrasound applications and therefore are not rated for their spectroscopic characteristics. In this work, we evaluated the gamma-ray spectroscopic performance of several multi-channel ADCs, including their energy resolution, nonlinearity, and timing resolution. Some of these ADCs demonstrated excellent energy resolution, 2.66% FWHM at 662 keV with a LaBr3 or 1.78 keV FWHM at 1332.5 keV with a high purity germanium (HPGe) detector, and sub-nanosecond timing resolution with LaBr 3. We present results from these measurements to illustrate their suitability for gamma-ray spectroscopy.

In-beam measurement of the position resolution of a highly segmented coaxial germanium detector

International Nuclear Information System (INIS)

Descovich, M.; Lee, I.Y.; Fallon, P.; Cromaz, M.; Macchiavelli, A.O.; Radford, D.C.; Vetter, K.; Clark, R.M.; Deleplanque, M.A.; Stephens, F.S.; Ward, D.

2005-01-01

The position resolution of a highly segmented coaxial germanium detector was determined by analyzing the 2055keV γ-ray transition of Zr90 excited in a fusion-evaporation reaction. The high velocity of the Zr90 nuclei imparted large Doppler shifts. Digital analysis of the detector signals recovered the energy and position of individual γ-ray interactions. The location of the first interaction in the crystal was used to correct the Doppler energy shift. Comparison of the measured energy resolution with simulations implied a position resolution (root mean square) of 2mm in three-dimensions

Measurement of GAMMA{sub ee}(J/psi).B(J/psi->e{sup +}e{sup -}) and GAMMA{sub ee}(J/psi).B(J/psi->mu{sup +}mu{sup -})

Energy Technology Data Exchange (ETDEWEB)

Anashin, V.V. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk, 630090 (Russian Federation); Aulchenko, V.M. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, 2, Pirogova street, Novosibirsk, 630090 (Russian Federation); Baldin, E.M., E-mail: E.M.Baldin@inp.nsk.s [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, 2, Pirogova street, Novosibirsk, 630090 (Russian Federation); Barladyan, A.K.; Barnyakov, A.Yu.; Barnyakov, M.Yu. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk, 630090 (Russian Federation); Baru, S.E. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, 2, Pirogova street, Novosibirsk, 630090 (Russian Federation); Bedny, I.V. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk, 630090 (Russian Federation); Beloborodova, O.L. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, 2, Pirogova street, Novosibirsk, 630090 (Russian Federation); Blinov, A.E. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk, 630090 (Russian Federation); Blinov, V.E. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk, 630090 (Russian Federation); Novosibirsk State Technical University, 20, Karl Marx prospect, Novosibirsk, 630092 (Russian Federation); Bobrov, A.V.; Bobrovnikov, V.S. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk, 630090 (Russian Federation)

2010-03-01

The products of the electron width of the J/psi meson and the branching fraction of its decays to the lepton pairs were measured using data from the KEDR experiment at the VEPP-4M electron-positron collider. The results are GAMMA{sub ee}xGAMMA{sub ee}/GAMMA=0.3323+-0.0064(stat.)+-0.0048(syst.) keV, GAMMA{sub ee}xGAMMA{sub m}u{sub m}u/GAMMA=0.3318+-0.0052(stat.)+-0.0063(syst.) keV. Their combinations GAMMA{sub ee}x(GAMMA{sub ee}+GAMMA{sub m}u{sub m}u)/GAMMA=0.6641+-0.0082(stat.)+-0.0100(syst.) keV, GAMMA{sub ee}/GAMMA{sub m}u{sub m}u=1.002+-0.021(stat.)+-0.013(syst.) can be used to improve the accuracy of the leptonic and full widths and test leptonic universality. Assuming emu universality and using the world average value of the lepton branching fraction, we also determine the leptonic GAMMA{sub ll}=5.59+-0.12 keV and total GAMMA=94.1+-2.7 keV widths of the J/psi meson.

7 keV sterile neutrino dark matter from split flavor mechanism

Energy Technology Data Exchange (ETDEWEB)

Ishida, Hiroyuki [Tohoku Univ., Sendai (Japan). Dept. of Physics; Jeong, Kwang Sik [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Takahashi, Fuminobu [Tohoku Univ., Sendai (Japan). Dept. of Physics; Tokyo Univ., Kashiwa (Japan). Kavli IPMU, TODIAS

2014-02-15

The recently discovered X-ray line at about 3.5 keV can be explained by sterile neutrino dark matter with mass, m{sub s}≅ 7 keV, and the mixing, sin{sup 2}2θ∝10{sup -10}. Such sterile neutrino is more long-lived than estimated based on the seesaw formula, which strongly suggests an extra flavor structure in the seesaw sector. We show that one can explain both the small mass and the longevity based on the split flavor mechanism where the breaking of flavor symmetry is tied to the breaking of the B-L symmetry. In a supersymmetric case we find that the 7 keV sterile neutrino implies the gravitino mass about 100 TeV.

Interaction between Solid Nitrogen and 1-3-keV Electrons

DEFF Research Database (Denmark)

Schou, Jørgen; Sørensen, H.

1978-01-01

V. At 3 keV, the SEE coefficient is 12 times that for solid deuterium. This is attributed partly to the larger production rate for low-energy electrons in nitrogen and partly to the larger escape probability for these electrons. Moreover, measurements were made of the electron-reflection coefficient, both......Experimental studies were made of the interaction between solid nitrogen and beams of 1-2-keV electrons. The projected range for the electrons was measured by means of the mirror-substrate method (gold substrate), giving the result 9.02×1016 E1.75 molecules/cm2 with the energy given in ke...... for solid nitrogen and for the carbon substrate. For nitrogen, it varied from 0.17 el/el at 1 keV to 0.13 el/el at 3 keV, and for carbon it varied from 0.13 to 0.12. The observations are discussed and comparisons made with other theoretical and experimental results. The agreement ranges from good to fair...

Neutron total cross section measurements in the energy region from 47 keV to 20 MeV

International Nuclear Information System (INIS)

Poenitz, W.P.; Whalen, J.F.

1983-05-01

Neutron total cross sections were measured for 26 elements. Data were obtained in the energy range from 47 keV to 20 MeV for 11 elements in the range of light-mass fission products. Previously reported measurements for eight heavy and actinide isotopes were extended to 20 MeV. Data were also obtained for Cu (47 keV to 1.4 MeV) and for Sc, Zn, Nd, Hf, and Pt (1.8 to 20 MeV). The present work is part of a continuing effort to provide accurate neutron total cross sections for evaluations and for optical-model parameteriztions. The latter are required for the derivation of other nuclear-data information of importance to applied programs. 37 references

The cyclopropene radical cation: Rovibrational level structure at low energies from high-resolution photoelectron spectra

Energy Technology Data Exchange (ETDEWEB)

Vasilatou, K.; Michaud, J. M.; Baykusheva, D.; Grassi, G.; Merkt, F. [Laboratorium für Physikalische Chemie, ETH Zürich, CH-8093 Zurich (Switzerland)

2014-08-14

The cyclopropene radical cation (c-C{sub 3}H{sub 4}{sup +}) is an important but poorly characterized three-membered-ring hydrocarbon. We report on a measurement of the high-resolution photoelectron and photoionization spectra of cyclopropene and several deuterated isotopomers, from which we have determined the rovibrational energy level structure of the X{sup ~+} {sup 2}B{sub 2} ground electronic state of c-C{sub 3}H{sub 4}{sup +} at low energies for the first time. The synthesis of the partially deuterated isotopomers always resulted in mixtures of several isotopomers, differing in their number of D atoms and in the location of these atoms, so that the photoelectron spectra of deuterated samples are superpositions of the spectra of several isotopomers. The rotationally resolved spectra indicate a C{sub 2v}-symmetric R{sub 0} structure for the ground electronic state of c-C{sub 3}H{sub 4}{sup +}. Two vibrational modes of c-C{sub 3}H{sub 4}{sup +} are found to have vibrational wave numbers below 300 cm{sup −1}, which is surprising for such a small cyclic hydrocarbon. The analysis of the isotopic shifts of the vibrational levels enabled the assignment of the lowest-frequency mode (fundamental wave number of ≈110 cm{sup −1} in c-C{sub 3}H{sub 4}{sup +}) to the CH{sub 2} torsional mode (ν{sub 8}{sup +}, A{sub 2} symmetry) and of the second-lowest-frequency mode (≈210 cm{sup −1} in c-C{sub 3}H{sub 4}{sup +}) to a mode combining a CH out-of-plane with a CH{sub 2} rocking motion (ν{sub 15}{sup +}, B{sub 2} symmetry). The potential energy along the CH{sub 2} torsional coordinate is flat near the equilibrium structure and leads to a pronounced anharmonicity.