New approach to calculate the true-coincidence effect of HpGe detector

Energy Technology Data Exchange (ETDEWEB)

Alnour, I. A., E-mail: aaibrahim3@live.utm.my, E-mail: ibrahim.elnour@yahoo.com [Department of Physics, Faculty of Pure and Applied Science, International University of Africa, 12223 Khartoum (Sudan); Wagiran, H. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai,Johor (Malaysia); Ibrahim, N. [Faculty of Defence Science and Technology, National Defence University of Malaysia, Kem Sungai Besi, 57000 Kuala Lumpur (Malaysia); Hamzah, S.; Elias, M. S. [Malaysia Nuclear Agency (MNA), Bangi, 43000 Kajang, Selangor D.E. (Malaysia); Siong, W. B. [Chemistry Department, Faculty of Resource Science & Technology, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak (Malaysia)

2016-01-22

The corrections for true-coincidence effects in HpGe detector are important, especially at low source-to-detector distances. This work established an approach to calculate the true-coincidence effects experimentally for HpGe detectors of type Canberra GC3018 and Ortec GEM25-76-XLB-C, which are in operation at neutron activation analysis lab in Malaysian Nuclear Agency (NM). The correction for true-coincidence effects was performed close to detector at distances 2 and 5 cm using {sup 57}Co, {sup 60}Co, {sup 133}Ba and {sup 137}Cs as standard point sources. The correction factors were ranged between 0.93-1.10 at 2 cm and 0.97-1.00 at 5 cm for Canberra HpGe detector; whereas for Ortec HpGe detector ranged between 0.92-1.13 and 0.95-100 at 2 and 5 cm respectively. The change in efficiency calibration curve of the detector at 2 and 5 cm after correction was found to be less than 1%. Moreover, the polynomial parameters functions were simulated through a computer program, MATLAB in order to find an accurate fit to the experimental data points.

HPGe detectors timing using pulse shape analysis techniques

International Nuclear Information System (INIS)

Crespi, F.C.L.; Vandone, V.; Brambilla, S.; Camera, F.; Million, B.; Riboldi, S.; Wieland, O.

2010-01-01

In this work the Pulse Shape Analysis has been used to improve the time resolution of High Purity Germanium (HPGe) detectors. A set of time aligned signals was acquired in a coincidence measurement using a coaxial HPGe and a cerium-doped lanthanum chloride (LaCl 3 :Ce) scintillation detector. The analysis using a Constant Fraction Discriminator (CFD) time output versus the HPGe signal shape shows that time resolution ranges from 2 to 12 ns depending on the slope in the initial part of the signal. An optimization procedure of the CFD parameters gives the same final time resolution (8 ns) as the one achieved after a correction of the CFD output based on the current pulse maximum position. Finally, an algorithm based on Pulse Shape Analysis was applied to the experimental data and a time resolution between 3 and 4 ns was obtained, corresponding to a 50% improvement as compared with that given by standard CFDs.

Characterization of large volume HPGe detectors. Part II: Experimental results

International Nuclear Information System (INIS)

Bruyneel, Bart; Reiter, Peter; Pascovici, Gheorghe

2006-01-01

Measurements on a 12-fold segmented, n-type, large volume, irregular shaped HPGe detector were performed in order to determine the parameters of anisotropic mobility for electrons and holes as charge carriers created by γ-ray interactions. To characterize the electron mobility the complete outer detector surface was scanned in small steps employing photopeak interactions at 60keV. A precise measurement of the hole drift anisotropy was performed with 356keV γ-rays. The drift velocity anisotropy and crystal geometry cause considerable rise time differences in pulse shapes depending on the position of the spatial charge carrier creation. Pulse shapes of direct and transient signals are reproduced by weighting potential calculations with high precision. The measured angular dependence of rise times is caused by the anisotropic mobility, crystal geometry, changing field strength and space charge effects. Preamplified signals were processed employing digital spectroscopy electronics. Response functions, crosstalk contributions and averaging procedures were taken into account implying novel methods due to the segmentation of the Ge-crystal and digital signal processing electronics

Study of the performance of HPGe detectors operating in very high magnetic fields

International Nuclear Information System (INIS)

Agnello, M.; Botta, E.; Bressani, T.; Bruschi, M.; Bufalino, S.; De Napoli, M.; Feliciello, A.; Fontana, A.; Giacobbe, B.; Lavezzi, L.; Raciti, G.; Rapisarda, E.; Rotondi, A.; Sbarra, C.; Sfienti, C.; Zoccoli, A.

2009-01-01

A new generation of high-resolution hypernuclear γ-spectroscopy experiments using high-purity germanium (HPGe) detectors is presently designed for the FINUDA spectrometer at DAΦNE, the Frascati Φ-factory, and for PANDA, the p-p-bar hadron spectrometer at the future FAIR facility. In both spectrometers the HPGe detectors have to be operated in strong magnetic fields. In this paper we report on a series of measurements performed on a HPGe detector inserted in a magnetic field of intensity up to 2.5 T, the highest ever reached for operations with a HPGe, and with different orientations of the detector's axis with respect to field direction. A significant worsening of the energy resolution was found, but with a moderate loss of the efficiency. The most relevant features of the peak shapes, described by bi-Gaussian functions, are parametrized in terms of field intensity and energy: this allows to correct the spectra measured in magnetic field and to recover the energy resolution almost completely.

Development of the MCNPX model for the portable HPGe detector

International Nuclear Information System (INIS)

Koleska, Michal; Viererbl, Ladislav; Marek, Milan

2014-01-01

The portable HPGe coaxial detector Canberra Big MAC is used in LVR-15 research reactor for spectrometric measurement of spent nuclear fuel. The fuel is measured in the dedicated system located in the spent fuel pool situated near the reactor. For the purpose of the spectrometric system calibration, the detector was precisely modeled with the MCNPX code. This model was constructed with the data acquired from the technical specification provided by the manufacturer and from the data obtained by the radiography of the crystal. The detector model was verified on the experimental data measured with available standard radionuclide sources and on-site prepared 110m Ag source. - Highlights: • Inner structure of the HPGe detector is determined. • An MCNPX model of the detector is developed. • The model is verified using different sources for two measurement geometries

TIGRESS highly-segmented high-purity germanium clover detector

Science.gov (United States)

Scraggs, H. C.; Pearson, C. J.; Hackman, G.; Smith, M. B.; Austin, R. A. E.; Ball, G. C.; Boston, A. J.; Bricault, P.; Chakrawarthy, R. S.; Churchman, R.; Cowan, N.; Cronkhite, G.; Cunningham, E. S.; Drake, T. E.; Finlay, P.; Garrett, P. E.; Grinyer, G. F.; Hyland, B.; Jones, B.; Leslie, J. R.; Martin, J.-P.; Morris, D.; Morton, A. C.; Phillips, A. A.; Sarazin, F.; Schumaker, M. A.; Svensson, C. E.; Valiente-Dobón, J. J.; Waddington, J. C.; Watters, L. M.; Zimmerman, L.

2005-05-01

The TRIUMF-ISAC Gamma-Ray Escape-Suppressed Spectrometer (TIGRESS) will consist of twelve units of four high-purity germanium (HPGe) crystals in a common cryostat. The outer contacts of each crystal will be divided into four quadrants and two lateral segments for a total of eight outer contacts. The performance of a prototype HPGe four-crystal unit has been investigated. Integrated noise spectra for all contacts were measured. Energy resolutions, relative efficiencies for both individual crystals and for the entire unit, and peak-to-total ratios were measured with point-like sources. Position-dependent performance was measured by moving a collimated source across the face of the detector.

Influence of Cell Phone Waves on the Performance of HPGe Detector

International Nuclear Information System (INIS)

Mansour, N.A.; Hassan, M.F.

2012-01-01

Hand phone mobile waves search systems, constructed with high resolution germanium (HPGe) detectors, are currently being installed at locations worldwide. This reflects a general desire for improved performance and a reduction in the time to make a good decision in interdiction cases. An integrated gamma-ray spectrometer, incorporating a mechanically-cooled HPGe detector, digital signal processing electronics, MCA, and communications has been developed to meet the detection and environmental needs of these systems. The HPGe detectors are designed to have good low- and medium-energy detection efficiency and excellent spectral peak resolution in order to eliminate peak overlaps and thereby remove problems by common industrial and medical radionuclides found in all types of hand phone mobile. Systems using detectors with inferior resolution, regardless of efficiency, are unable to separate the radiation signals from NORM and illicit nuclides. The absolute full-energy peak efficiency of the detector and background count-rate in the peak energy region determine the signal-to-noise ratio. Measurements presented show the impact of shielding and masking on the performance of the hand phone mobile. The results illustrate applicability of the design to a variety of monitoring situations for the detection of illicit material. In the present work we studied the effects of different types of hand phone waves on the performance of 70% HPGe X and Gamma-ray detector. The detected interference has an energy range 30-100 keV. A correction battues was estimated as a function of time verses cell phone type.The measurement quality of the measurer gamma-spectra can be corrected at low X-ray region. The effect of these waves was also studied on the performance of the main detector amplifier. The results were obtained for Etesalat, Vodafone and Mobinile stations. The introduced method can be simulated for other devices having the same interference effect.

Relative efficiency calculation of a HPGe detector using MCNPX code

International Nuclear Information System (INIS)

Medeiros, Marcos P.C.; Rebello, Wilson F.; Lopes, Jose M.; Silva, Ademir X.

2015-01-01

High-purity germanium detectors (HPGe) are mandatory tools for spectrometry because of their excellent energy resolution. The efficiency of such detectors, quoted in the list of specifications by the manufacturer, frequently refers to the relative full-energy peak efficiency, related to the absolute full-energy peak efficiency of a 7.6 cm x 7.6 cm (diameter x height) NaI(Tl) crystal, based on the 1.33 MeV peak of a 60 Co source positioned 25 cm from the detector. In this study, we used MCNPX code to simulate a HPGe detector (Canberra GC3020), from Real-Time Neutrongraphy Laboratory of UFRJ, to survey the spectrum of a 60 Co source located 25 cm from the detector in order to calculate and confirm the efficiency declared by the manufacturer. Agreement between experimental and simulated data was achieved. The model under development will be used for calculating and comparison purposes with the detector calibration curve from software Genie2000™, also serving as a reference for future studies. (author)

Performance of HPGe detectors in high magnetic fields

Czech Academy of Sciences Publication Activity Database

Lorente, A.S.; Achenbach, P.; Agnello, M.; Majling, Lubomír

2007-01-01

Roč. 573, č. 3 (2007), s. 410-417 ISSN 0168-9002 R&D Projects: GA ČR GA202/05/2142 Institutional research plan: CEZ:AV0Z10480505 Keywords : hypernuclear gamma-spectroscopy * HPGe detectors Subject RIV: BE - Theoretical Physics Impact factor: 1.114, year: 2007

Segmented quasi-coaxial HP-Ge detectors optimized for spatial localization of the events

International Nuclear Information System (INIS)

Ripamonti, Giancarlo; Pulici, Paolo; Abbiati, Roberto

2006-01-01

A methodology for the design of segmented high purity Germanium detectors is presented. Its motivation follows from the necessity of making it easier to derive fast algorithms for measuring the gamma-detector interaction position. By using our study, detector geometries can be designed, which could allow a first estimate of the interaction coordinate along the carrier drift direction by analyzing the shape of the signal of a single segment. The maximum resolution that can be achieved and the corresponding conditions for the electronics are highlighted: basic unavoidable constraints limit the resolution to around 3 mm, but this first position estimate can be used, at least in principle, as a starting point for more accurate, although computationally heavy, algorithms

Position sensitivity of the proposed segmented germanium detectors for the DESPEC project

International Nuclear Information System (INIS)

Khaplanov, A.; Tashenov, S.; Cederwall, B.

2009-01-01

The DESPEC HPGe array is a part of the NuSTAR project at FAIR, Germany. It is aimed at the spectroscopy of the stopped decaying exotic nuclei. Segmented γ-ray tracking detectors are proposed for this array in order to maximize detection efficiency and background suppression when searching for very rare events. Two types of detector modules-stacks of three 16-fold segmented planar crystals and 12- and 16-fold segmented clover detectors-have been investigated and compared from the point of view of the achievable position resolution using pulse shape analysis (PSA). To this end, detector signals from realistic γ-ray interactions have been calculated. These signals were treated by PSA in order to reconstruct the photon interaction locations. Comparing the initial interaction locations to the reconstructed ones, it was found that the double-sided strip planar detector yielded position reconstruction errors at least a factor 2 lower than the other detectors considered.

Dose measurements with a HPGe detector - a technical manual

Energy Technology Data Exchange (ETDEWEB)

Lidstroem, K.; Nordenfors, C.; Aagren, G

2000-06-01

This paper is a technical manual for estimations of dose based on a gamma spectrum. The method used is based on the Monte Carlo code EGS4. Since dose estimations from spectra are specific for each detector, this work is performed on two mobile HPGe detectors at FOA NBC Defence in Umeaa. This technical manual describes the method used in three steps: Part 1 explains how to construct a model of the detector geometry and the specific material for a new detector. Part 2 describes the underlying work of Monte Carlo simulations of a detector given geometry and material. Part 3 describes dose estimations from a gamma spectrum.

Characterization of segmented large volume, high purity germanium detectors

International Nuclear Information System (INIS)

Bruyneel, B.

2006-01-01

γ-ray tracking in future HPGe arrays like AGATA will rely on pulse shape analysis (PSA) of multiple γ-interactions. For this purpose, a simple and fast procedure was developed which enabled the first full characterization of a segmented large volume HPGe detector. An analytical model for the hole mobility in a Ge crystal lattice was developed to describe the hole drift anisotropy with experimental velocity values along the crystal axis as parameters. The new model is based on the drifted Maxwellian hole distribution in Ge. It is verified by reproducing successfully experimental longitudinal hole anisotropy data. A comparison between electron and hole mobility shows large differences for the longitudinal and tangential velocity anisotropy as a function of the electrical field orientation. Measurements on a 12 fold segmented, n-type, large volume, irregular shaped HPGe detector were performed in order to determine the parameters of anisotropic mobility for electrons and holes as charge carriers created by γ-ray interactions. To characterize the electron mobility the complete outer detector surface was scanned in small steps employing photopeak interactions at 60 keV. A precise measurement of the hole drift anisotropy was performed with 356 keV rays. The drift velocity anisotropy and crystal geometry cause considerable rise time differences in pulse shapes depending on the position of the spatial charge carrier creation. Pulse shapes of direct and transient signals are reproduced by weighting potential calculations with high precision. The measured angular dependence of rise times is caused by the anisotropic mobility, crystal geometry, changing field strength and space charge effects. Preamplified signals were processed employing digital spectroscopy electronics. Response functions, crosstalk contributions and averaging procedures were taken into account implying novel methods due to the segmentation of the Ge-crystal and the digital electronics. The results are

Characterization of segmented large volume, high purity germanium detectors

Energy Technology Data Exchange (ETDEWEB)

Bruyneel, B. [Koeln Univ. (Germany). Inst. fuer Kernphysik

2006-07-01

{gamma}-ray tracking in future HPGe arrays like AGATA will rely on pulse shape analysis (PSA) of multiple {gamma}-interactions. For this purpose, a simple and fast procedure was developed which enabled the first full characterization of a segmented large volume HPGe detector. An analytical model for the hole mobility in a Ge crystal lattice was developed to describe the hole drift anisotropy with experimental velocity values along the crystal axis as parameters. The new model is based on the drifted Maxwellian hole distribution in Ge. It is verified by reproducing successfully experimental longitudinal hole anisotropy data. A comparison between electron and hole mobility shows large differences for the longitudinal and tangential velocity anisotropy as a function of the electrical field orientation. Measurements on a 12 fold segmented, n-type, large volume, irregular shaped HPGe detector were performed in order to determine the parameters of anisotropic mobility for electrons and holes as charge carriers created by {gamma}-ray interactions. To characterize the electron mobility the complete outer detector surface was scanned in small steps employing photopeak interactions at 60 keV. A precise measurement of the hole drift anisotropy was performed with 356 keV rays. The drift velocity anisotropy and crystal geometry cause considerable rise time differences in pulse shapes depending on the position of the spatial charge carrier creation. Pulse shapes of direct and transient signals are reproduced by weighting potential calculations with high precision. The measured angular dependence of rise times is caused by the anisotropic mobility, crystal geometry, changing field strength and space charge effects. Preamplified signals were processed employing digital spectroscopy electronics. Response functions, crosstalk contributions and averaging procedures were taken into account implying novel methods due to the segmentation of the Ge-crystal and the digital electronics

Response function of a p type - HPGe detector

International Nuclear Information System (INIS)

Lopez-Pino, Neivy; Cabral, Fatima Padilla; D'Alessandro, Katia; Maidana, Nora Lia; Vanin, Vito Roberto

2011-01-01

The response function of a HPGe detector depends on Ge crystal dimensions and dead layers thicknesses; most of them are not given by the manufacturers or change with detector damage from neutrons or contact with the atmosphere and therefore must be experimentally determined. The response function is obtained by a Monte-Carlo simulation procedure based on the Ge crystal characteristics. In this work, a p-type coaxial HPGe detector with 30% efficiency, manufactured in 1989, was investigated. The crystal radius and length and the inner hole dimensions were obtained scanning the capsule both in the radial and axial directions using 4 mm collimated beams from 137 Cs, 207 Bi point sources placed on a x-y table in steps of 2,00 mm. These dimensions were estimated comparing the experimental peak areas with those obtained by simulation using several hole configurations. In a similar procedure, the frontal dead layer thickness was determined using 2 mm collimated beams of the 59 keV gamma-rays from 241 Am and 81 keV from 133 Ba sources hitting the detector at 90 deg and 45 deg with respect to the capsule surface. The Monte Carlo detector model included, besides the crystal, hole and capsules sizes, the Ge dead-layers. The obtained spectra were folded with a gaussian resolution function to account for electronic noise. The comparison of simulated and experimental response functions for 4 mm collimated beams of 60 Co, 137 Cs, and 207 Bi points sources placed at distances of 7, 11 and 17 cm from the detector end cap showed relative deviations of about 10% in general and below 10% in the peak. The frontal dead layer thickness determined by our procedure was different from that specified by the detector manufacturer. (author)

Charge collection performance of a segmented planar high-purity germanium detector

Energy Technology Data Exchange (ETDEWEB)

Cooper, R.J. [Department of Physics, The University of Liverpool, Oliver Lodge Laboratory, Liverpool Merseyside L69 7ZE (United Kingdom)], E-mail: R.Cooper@liverpool.ac.uk; Boston, A.J.; Boston, H.C.; Cresswell, J.R.; Grint, A.N.; Harkness, L.J.; Nolan, P.J.; Oxley, D.C.; Scraggs, D.P. [Department of Physics, The University of Liverpool, Oliver Lodge Laboratory, Liverpool Merseyside L69 7ZE (United Kingdom); Lazarus, I.; Simpson, J. [STFC Daresbury Laboratory, Warrington, Cheshire WA4 4AD (United Kingdom); Dobson, J. [Rosemere Cancer Centre, Royal Preston Hospital, Preston PR2 9HT (United Kingdom)

2008-10-01

High-precision scans of a segmented planar high-purity germanium (HPGe) detector have been performed with a range of finely collimated gamma ray beams allowing the response as a function of gamma ray interaction position to be quantified. This has allowed the development of parametric pulse shape analysis (PSA) techniques and algorithms for the correction of imperfections in performance. In this paper we report on the performance of this detector, designed for use in a positron emission tomography (PET) development system.

Performance revaluation of a N-type coaxial HPGe detector with front edges crystal using MCNPX

International Nuclear Information System (INIS)

Azli, Tarek; Chaoui, Zine-El-Abidine

2015-01-01

The MCNPX code was used to determine the efficiency of a N-type HPGe detector after two decades of operation. Accounting for the roundedness of the crystal's front edges and an inhomogeneous description of the detector's dead layers were shown to achieve better agreement between measurements and simulation efficiency determination. The calculations were experimentally verified using point sources in the energy range from 50 keV to 1400 keV, and an overall uncertainty less than 2% was achieved. In order to use the detector for different matrices and geometries in radioactivity, the suggested model was validated by changing the counting geometry and by using multi-gamma disc sources. The introduced simulation approach permitted the revaluation of the performance of an HPGe detector in comparison of its initial condition, which is a useful tool for precise determination of the thickness of the inhomogeneous dead layer. - Highlights: • Monte Carlo (MCNPX) simulation of an HPGe detector performance after more than two decades in use. • Investigating influence of detector rounded front edges of crystal. • Achieving good matching between Monte Carlo simulation and experiments by inhomogeneous description of detector dead layers

MCNP HPGe detector benchmark with previously validated Cyltran model.

Science.gov (United States)

Hau, I D; Russ, W R; Bronson, F

2009-05-01

An exact copy of the detector model generated for Cyltran was reproduced as an MCNP input file and the detection efficiency was calculated similarly with the methodology used in previous experimental measurements and simulation of a 280 cm(3) HPGe detector. Below 1000 keV the MCNP data correlated to the Cyltran results within 0.5% while above this energy the difference between MCNP and Cyltran increased to about 6% at 4800 keV, depending on the electron cut-off energy.

The influence of anisotropic electron drift velocity on the signal shapes of closed-end HPGe detectors

CERN Document Server

Mihailescu, L; Lieder, R M; Brands, H; Jaeger, H

2000-01-01

This study is concerned with the anisotropy of the electron drift velocity in germanium crystals at high electric fields and low temperature, and its influence on the charge collection process in n-type, high-purity germanium (HPGe) detectors of closed-end, coaxial geometry. The electron trajectories inside HPGe detectors are simulated using a phenomenological model to calculate the dependence of the drift velocity on the angle between the electric field and the crystal orientation. The resulting induced currents and pulse shapes for a given detector geometry and preamplifier bandwidth are compared to experiment. Experimentally, the dependence of the pulse shapes on the conductivity anisotropy in closed-end HPGe detectors was observed. The experimental data on pulse shapes were obtained by sampling preamplifier signals of an encapsulated, hexaconical EUROBALL detector, which was irradiated by collimated sup 2 sup 2 Na and sup 2 sup 4 sup 1 Am sources. The crystal orientation was measured by neutron reflection...

A New Virtual Point Detector Concept for a HPGe detector

International Nuclear Information System (INIS)

Byun, Jong In; Yun, Ju Yong

2009-01-01

For last several decades, the radiation measurement and radioactivity analysis techniques using gamma detectors have been well established. Especially , the study about the detection efficiency has been done as an important part of gamma spectrometry. The detection efficiency depends strongly on source-to-detector distance. The detection efficiency with source-to-detector distance can be expressed by a complex function of geometry and physical characteristics of gamma detectors. In order to simplify the relation, a virtual point detector concept was introduced by Notea. Recently, further studies concerning the virtual point detector have been performed. In previous other works the virtual point detector has been considered as a fictitious point existing behind the detector end cap. However the virtual point detector position for the front and side of voluminous detectors might be different due to different effective central axis of them. In order to more accurately define the relation, therefore, we should consider the virtual point detector for the front as well as side and off-center of the detector. The aim of this study is to accurately define the relation between the detection efficiency and source-to-detector distance with the virtual point detector. This paper demonstrates the method to situate the virtual point detectors for a HPGe detector. The new virtual point detector concept was introduced for three area of the detector and its characteristics also were demonstrated by using Monte Carlo Simulation method. We found that the detector has three virtual point detectors except for its rear area. This shows that we should consider the virtual point detectors for each area when applying the concept to radiation measurement. This concept can be applied to the accurate geometric simplification for the detector and radioactive sources.

Incomplete charge collection in an HPGe double-sided strip detector

International Nuclear Information System (INIS)

Hayward, Jason; Wehe, David

2008-01-01

For gamma-ray detection, high-purity germanium (HPGe) has long been the standard for energy resolution, and double-sided strip detectors (DSSDs) offer the possibility of sub-millimeter position resolution. Our HPGe DSSD is 81 mm in diameter, 11-mm thick, and has 3-mm strip pitch with a gap width of 500 μm. In this work, we focus on characterizing just the interactions that occur between collecting strips. Simulation and measurement results for our HPGe DSSD show that the gap between strips is the most position-sensitive region. But, spectra collected from events that occur in and near the gaps are complicated by: (1) incomplete charge-carrier collection, or charge loss; (2) signal variance introduced by charge-carrier cloud size, orientation, and lateral spreading; and (3) the difficulty of distinguishing single interactions from multiple close interactions. Using tightly, collimated beams of monoenergetic gamma rays, the measured energy spectra at the gap center show that incomplete charge collection is significant in our detector at 356 and 662 keV, resulting in degradation of the photopeak efficiency. Additionally, close interactions are identifiable in the spectra. Thus, close interactions must be identified on an event-by-event basis in order to precisely identify gap interaction position or make charge-loss corrections at these energies. Furthermore, spectral differences are observed between anode and cathode gaps, and a possible reason for this asymmetry is proposed

Gamma-ray Full Spectrum Analysis for Environmental Radioactivity by HPGe Detector

Science.gov (United States)

Jeong, Meeyoung; Lee, Kyeong Beom; Kim, Kyeong Ja; Lee, Min-Kie; Han, Ju-Bong

2014-12-01

Odyssey, one of the NASA¡¯s Mars exploration program and SELENE (Kaguya), a Japanese lunar orbiting spacecraft have a payload of Gamma-Ray Spectrometer (GRS) for analyzing radioactive chemical elements of the atmosphere and the surface. In these days, gamma-ray spectroscopy with a High-Purity Germanium (HPGe) detector has been widely used for the activity measurements of natural radionuclides contained in the soil of the Earth. The energy spectra obtained by the HPGe detectors have been generally analyzed by means of the Window Analysis (WA) method. In this method, activity concentrations are determined by using the net counts of energy window around individual peaks. Meanwhile, an alternative method, the so-called Full Spectrum Analysis (FSA) method uses count numbers not only from full-absorption peaks but from the contributions of Compton scattering due to gamma-rays. Consequently, while it takes a substantial time to obtain a statistically significant result in the WA method, the FSA method requires a much shorter time to reach the same level of the statistical significance. This study shows the validation results of FSA method. We have compared the concentration of radioactivity of 40K, 232Th and 238U in the soil measured by the WA method and the FSA method, respectively. The gamma-ray spectrum of reference materials (RGU and RGTh, KCl) and soil samples were measured by the 120% HPGe detector with cosmic muon veto detector. According to the comparison result of activity concentrations between the FSA and the WA, we could conclude that FSA method is validated against the WA method. This study implies that the FSA method can be used in a harsh measurement environment, such as the gamma-ray measurement in the Moon, in which the level of statistical significance is usually required in a much shorter data acquisition time than the WA method.

Gamma-ray Full Spectrum Analysis for Environmental Radioactivity by HPGe Detector

Directory of Open Access Journals (Sweden)

Meeyoung Jeong

2014-12-01

Full Text Available Odyssey, one of the NASA’s Mars exploration program and SELENE (Kaguya, a Japanese lunar orbiting spacecraft have a payload of Gamma-Ray Spectrometer (GRS for analyzing radioactive chemical elements of the atmosphere and the surface. In these days, gamma-ray spectroscopy with a High-Purity Germanium (HPGe detector has been widely used for the activity measurements of natural radionuclides contained in the soil of the Earth. The energy spectra obtained by the HPGe detectors have been generally analyzed by means of the Window Analysis (WA method. In this method, activity concentrations are determined by using the net counts of energy window around individual peaks. Meanwhile, an alternative method, the so-called Full Spectrum Analysis (FSA method uses count numbers not only from full-absorption peaks but from the contributions of Compton scattering due to gamma-rays. Consequently, while it takes a substantial time to obtain a statistically significant result in the WA method, the FSA method requires a much shorter time to reach the same level of the statistical significance. This study shows the validation results of FSA method. We have compared the concentration of radioactivity of 40K, 232Th and 238U in the soil measured by the WA method and the FSA method, respectively. The gamma-ray spectrum of reference materials (RGU and RGTh, KCl and soil samples were measured by the 120% HPGe detector with cosmic muon veto detector. According to the comparison result of activity concentrations between the FSA and the WA, we could conclude that FSA method is validated against the WA method. This study implies that the FSA method can be used in a harsh measurement environment, such as the gamma-ray measurement in the Moon, in which the level of statistical significance is usually required in a much shorter data acquisition time than the WA method.

Characterization of HPGe detectors using Computed Tomography

Energy Technology Data Exchange (ETDEWEB)

Hedman, A., E-mail: Angelica.Hedman@foi.se [Swedish Defence Research Agency, Division of CBRN Defence and Security, SE-90182 Umeå (Sweden); Umeå University, Department of Radiation Sciences, Radiation Physics, SE-90187 Umeå (Sweden); Bahar Gogani, J.; Granström, M. [Swedish Defence Research Agency, Division of CBRN Defence and Security, SE-90182 Umeå (Sweden); Johansson, L.; Andersson, J.S. [Umeå University, Department of Radiation Sciences, Radiation Physics, SE-90187 Umeå (Sweden); Ramebäck, H. [Swedish Defence Research Agency, Division of CBRN Defence and Security, SE-90182 Umeå (Sweden); Chalmers University of Technology, Department of Chemical and Biological Engineering, Nuclear Chemistry, SE-41296 Göteborg (Sweden)

2015-06-11

Computed Tomography (CT) high-resolution imaging have been used to investigate if there is a significant change in the crystal-to-window distance, i.e. the air gap thickness, in a small n-type detector cooled to 77 K, and in a medium sized p-type HPGe detector when cooled to 100 K. The findings were compared to detector dimension data made available by the manufacturer. The air gap thickness increased by (0.38±0.07) mm for the n-type detector and by (0.40±0.15) mm for the p-type detector when the detectors were cooled to 77 resp. 100 K compared to at room temperature. Monte Carlo calculations indicate that these differences have a significant impact on the efficiency in close geometries (<5 cm). In the energy range of 40–700 keV with a source placed directly on endcap, the change in detector efficiency with temperature is 1.9–2.9% for the n-type detector and 0.3–2.1% for the p-type detector. The measured air gap thickness when cooling the detector was 1.1 mm thicker than manufacturer data for the n-type detector and 0.2 mm thicker for the p-type detector. In the energy range of 40–700 keV and with a source on endcap, this result in a change in detector efficiency of 5.2–7.1% for the n-type detector and 0.2–1.0% for the p-type detector, i.e. the detector efficiency is overestimated using data available by the manufacturer.

Optimization of the n-type HPGe detector parameters to theoretical determination of efficiency curves

International Nuclear Information System (INIS)

Rodriguez-Rodriguez, A.; Correa-Alfonso, C.M.; Lopez-Pino, N.; Padilla-Cabal, F.; D'Alessandro, K.; Corrales, Y.; Garcia-Alvarez, J. A.; Perez-Mellor, A.; Baly-Gil, L.; Machado, A.

2011-01-01

A highly detailed characterization of a 130 cm 3 n-type HPGe detector, employed in low - background gamma spectrometry measurements, was done. Precise measured data and several Monte Carlo (MC) calculations have been combined to optimize the detector parameters. HPGe crystal location inside the Aluminum end-cap as well as its dimensions, including the borehole radius and height, were determined from frontal and lateral scans. Additionally, X-ray radiography and Computed Axial Tomography (CT) studies were carried out to complement the information about detector features. Using seven calibrated point sources ( 241 Am, 133 Ba, 57,60 Co, 137 Cs, 22 Na and 152 Eu), photo-peak efficiency curves at three different source - detector distances (SDD) were obtained. Taking into account the experimental values, an optimization procedure by means of MC simulations (MCNPX 2.6 code) were performed. MC efficiency curves were calculated specifying the optimized detector parameters in the MCNPX input files. Efficiency calculation results agree with empirical data, showing relative deviations lesser 10%. (Author)

Studies on a pulse shaping system for fast coincidence with very large volume HPGe detectors

International Nuclear Information System (INIS)

Bose, S.; Chatterjee, M.B.; Sinha, B.K.; Bhattacharya, R.

1987-01-01

A variant of the leading edge timing (LET) has been proposed which compensates the ''walk'' due to risetime spread in very large volume (∝100 cm 3 ) HPGe detectors. The method - shape compensated leading edge timing (SCLET) - can be used over a wide dynamic range of energies with 100% efficiency and has been compared with the LET and ARC methods. A time resolution of 10 ns fwhm and 21 ns fwtm has been obtained with 22 Na gamma rays and two HPGe detectors of 96 and 114 cm 3 volume. This circuit is easy to duplicate and use can be a low cost alternative to commercial circuits in experiments requiring a large number of detectors. (orig.)

Determination Performance Of Gamma Spectrometry Co-Axial HPGE Detector In Radiochemistry And Environment Group, Nuclear Malaysia

International Nuclear Information System (INIS)

Mei-Woo, Y.

2014-01-01

Gamma Spectrometry System is used to measure qualitatively and quantitatively a gamma emitting radionuclide. The accuracy of the measurement very much depends on the performance specifications of the HPGe detectors. From this study it found that all the seven co-axial HPGe detectors in Radiochemistry and Environment Group, Nuclear Malaysia are in good working conditions base on the verification of performance specifications namely Resolution, Peak Shape, Peak-to-Compton ratio and Relative Efficiency against the warranted value from the manufacturers. (author)

Determination of efficiency curves for HPGE detector in different counting geometries

International Nuclear Information System (INIS)

Rodrigues, Josianne L.; Kastner, Geraldo F.; Ferreira, Andrea V.

2011-01-01

This paper presents the first experimental results related to determination of efficiency curves for HPGe detector in different counting geometries. The detector is a GX2520 Canberra belonging to CDTN/CNEN. Efficiency curves for punctual were determined by using a certified set of gamma sources. These curves were determined for three counting geometries. Following that, efficiency curves for non punctual samples were determined by using standard solutions of radionuclides in 500 ml and 1000 ml wash bottle Marinelli

Full energy peak efficiency of composite detectors for high energy gamma-rays

International Nuclear Information System (INIS)

Kshetri, Ritesh

2015-01-01

Experiments involving radioactive beams demand high detection efficiencies. One of the ways to obtain high detection efficiency without deteriorating the energy resolution or timing characteristics is the use of composite detectors which are composed of standard HPGe crystals arranged in a compact way. Two simplest composite detectors are the clover and cluster detectors. The TRIUMF-ISAC Gamma-Ray Escape-Suppressed Spectrometer (TIGRESS) comprises of 16 large volume, 32-fold segmented HPGe clover detectors, where each detector is shielded by a 20-fold segmented escape suppression shield (ESS)

Performance revaluation of a N-type coaxial HPGe detector with front edges crystal using MCNPX.

Science.gov (United States)

Azli, Tarek; Chaoui, Zine-El-Abidine

2015-03-01

The MCNPX code was used to determine the efficiency of a N-type HPGe detector after two decades of operation. Accounting for the roundedness of the crystal`s front edges and an inhomogeneous description of the detector's dead layers were shown to achieve better agreement between measurements and simulation efficiency determination. The calculations were experimentally verified using point sources in the energy range from 50keV to 1400keV, and an overall uncertainty less than 2% was achieved. In order to use the detector for different matrices and geometries in radioactivity, the suggested model was validated by changing the counting geometry and by using multi-gamma disc sources. The introduced simulation approach permitted the revaluation of the performance of an HPGe detector in comparison of its initial condition, which is a useful tool for precise determination of the thickness of the inhomogeneous dead layer. Copyright © 2014 Elsevier Ltd. All rights reserved.

Using lattice tools and unfolding methods for hpge detector efficiency simulation with the Monte Carlo code MCNP5

International Nuclear Information System (INIS)

Querol, A.; Gallardo, S.; Ródenas, J.; Verdú, G.

2015-01-01

In environmental radioactivity measurements, High Purity Germanium (HPGe) detectors are commonly used due to their excellent resolution. Efficiency calibration of detectors is essential to determine activity of radionuclides. The Monte Carlo method has been proved to be a powerful tool to complement efficiency calculations. In aged detectors, efficiency is partially deteriorated due to the dead layer increasing and consequently, the active volume decreasing. The characterization of the radiation transport in the dead layer is essential for a realistic HPGe simulation. In this work, the MCNP5 code is used to calculate the detector efficiency. The F4MESH tally is used to determine the photon and electron fluence in the dead layer and the active volume. The energy deposited in the Ge has been analyzed using the ⁎F8 tally. The F8 tally is used to obtain spectra and to calculate the detector efficiency. When the photon fluence and the energy deposition in the crystal are known, some unfolding methods can be used to estimate the activity of a given source. In this way, the efficiency is obtained and serves to verify the value obtained by other methods. - Highlights: • The MCNP5 code is used to estimate the dead layer thickness of an HPGe detector. • The F4MESH tally is applied to verify where interactions occur into the Ge crystal. • PHD and the energy deposited are obtained with F8 and ⁎F8 tallies, respectively. • An average dead layer between 70 and 80 µm is obtained for the HPGe studied. • The efficiency is calculated applying the TSVD method to the response matrix.

High precision efficiency calibration of a HPGe detector

International Nuclear Information System (INIS)

Nica, N.; Hardy, J.C.; Iacob, V.E.; Helmer, R.G.

2003-01-01

Many experiments involving measurements of γ rays require a very precise efficiency calibration. Since γ-ray detection and identification also requires good energy resolution, the most commonly used detectors are of the coaxial HPGe type. We have calibrated our 70% HPGe to ∼ 0.2% precision, motivated by the measurement of precise branching ratios (BR) in superallowed 0 + → 0 + β decays. These BRs are essential ingredients in extracting ft-values needed to test the Standard Model via the unitarity of the Cabibbo-Kobayashi-Maskawa matrix, a test that it currently fails by more than two standard deviations. To achieve the required high precision in our efficiency calibration, we measured 17 radioactive sources at a source-detector distance of 15 cm. Some of these were commercial 'standard' sources but we achieved the highest relative precision with 'home-made' sources selected because they have simple decay schemes with negligible side feeding, thus providing exactly matched γ-ray intensities. These latter sources were produced by us at Texas A and M by n-activation or by nuclear reactions. Another critical source among the 17 was a 60 Co source produced by Physikalisch-Technische Bundesanstalt, Braunschweig, Germany: its absolute activity was quoted to better than 0.06%. We used it to establish our absolute efficiency, while all the other sources were used to determine relative efficiencies, extending our calibration over a large energy range (40-3500 keV). Efficiencies were also determined with Monte Carlo calculations performed with the CYLTRAN code. The physical parameters of the Ge crystal were independently determined and only two (unmeasurable) dead-layers were adjusted, within physically reasonable limits, to achieve precise absolute agreement with our measured efficiencies. The combination of measured efficiencies at more than 60 individual energies and Monte Carlo calculations to interpolate between them allows us to quote the efficiency of our

New approach for calibration the efficiency of HPGe detectors

International Nuclear Information System (INIS)

Alnour, I.A.; Wagiran, H.; Suhaimi Hamzah; Siong, W.B.; Mohd Suhaimi Elias

2013-01-01

Full-text: This work evaluates the efficiency calibrating of HPGe detector coupled with Canberra GC3018 with Genie 2000 software and Ortec GEM25-76-XLB-C with Gamma Vision software; available at Neutron activation analysis laboratory in Malaysian Nuclear Agency (NM). The efficiency calibration curve was constructed from measurement of an IAEA, standard gamma point sources set composed by 214 Am, 57 Co, 133 Ba, 152 Eu, 137 Cs and 60 Co. The efficiency calibrations were performed for three different geometries: 5, 10 and 15 cm distances from the end cap detector. The polynomial parameters functions were simulated through a computer program, MATLAB in order to find an accurate fit to the experimental data points. The efficiency equation was established from the known fitted parameters which allow for the efficiency evaluation at particular energy of interest. The study shows that significant deviations in the efficiency, depending on the source-detector distance and photon energy. (author)

Uncertainty analysis in the simulation of an HPGe detector using the Monte Carlo Code MCNP5

International Nuclear Information System (INIS)

Gallardo, Sergio; Pozuelo, Fausto; Querol, Andrea; Verdu, Gumersindo; Rodenas, Jose; Ortiz, J.; Pereira, Claubia

2013-01-01

A gamma spectrometer including an HPGe detector is commonly used for environmental radioactivity measurements. Many works have been focused on the simulation of the HPGe detector using Monte Carlo codes such as MCNP5. However, the simulation of this kind of detectors presents important difficulties due to the lack of information from manufacturers and due to loss of intrinsic properties in aging detectors. Some parameters such as the active volume or the Ge dead layer thickness are many times unknown and are estimated during simulations. In this work, a detailed model of an HPGe detector and a petri dish containing a certified gamma source has been done. The certified gamma source contains nuclides to cover the energy range between 50 and 1800 keV. As a result of the simulation, the Pulse Height Distribution (PHD) is obtained and the efficiency curve can be calculated from net peak areas and taking into account the certified activity of the source. In order to avoid errors due to the net area calculation, the simulated PHD is treated using the GammaVision software. On the other hand, it is proposed to use the Noether-Wilks formula to do an uncertainty analysis of model with the main goal of determining the efficiency curve of this detector and its associated uncertainty. The uncertainty analysis has been focused on dead layer thickness at different positions of the crystal. Results confirm the important role of the dead layer thickness in the low energy range of the efficiency curve. In the high energy range (from 300 to 1800 keV) the main contribution to the absolute uncertainty is due to variations in the active volume. (author)

Uncertainty analysis in the simulation of an HPGe detector using the Monte Carlo Code MCNP5

Energy Technology Data Exchange (ETDEWEB)

Gallardo, Sergio; Pozuelo, Fausto; Querol, Andrea; Verdu, Gumersindo; Rodenas, Jose, E-mail: sergalbe@upv.es [Universitat Politecnica de Valencia, Valencia, (Spain). Instituto de Seguridad Industrial, Radiofisica y Medioambiental (ISIRYM); Ortiz, J. [Universitat Politecnica de Valencia, Valencia, (Spain). Servicio de Radiaciones. Lab. de Radiactividad Ambiental; Pereira, Claubia [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear

2013-07-01

A gamma spectrometer including an HPGe detector is commonly used for environmental radioactivity measurements. Many works have been focused on the simulation of the HPGe detector using Monte Carlo codes such as MCNP5. However, the simulation of this kind of detectors presents important difficulties due to the lack of information from manufacturers and due to loss of intrinsic properties in aging detectors. Some parameters such as the active volume or the Ge dead layer thickness are many times unknown and are estimated during simulations. In this work, a detailed model of an HPGe detector and a petri dish containing a certified gamma source has been done. The certified gamma source contains nuclides to cover the energy range between 50 and 1800 keV. As a result of the simulation, the Pulse Height Distribution (PHD) is obtained and the efficiency curve can be calculated from net peak areas and taking into account the certified activity of the source. In order to avoid errors due to the net area calculation, the simulated PHD is treated using the GammaVision software. On the other hand, it is proposed to use the Noether-Wilks formula to do an uncertainty analysis of model with the main goal of determining the efficiency curve of this detector and its associated uncertainty. The uncertainty analysis has been focused on dead layer thickness at different positions of the crystal. Results confirm the important role of the dead layer thickness in the low energy range of the efficiency curve. In the high energy range (from 300 to 1800 keV) the main contribution to the absolute uncertainty is due to variations in the active volume. (author)

HPGe detectors long time behaviour in high-resolution γ spectrometry

International Nuclear Information System (INIS)

Sajo-Bohus, L.; Rosso, D.; Sajo Castelli, A.M.; Napoli, D.R.; Fioretto, E.; Menegazzo, R.; Barros, H.; Ur, C.A.; Palacios, D.; Liendo, J.

2011-01-01

A large set of data on long term performance of n-type HPGe detectors used in GASP, EUROBALL and CLARA γ spectrometers, as well as environmental measurements have been collected over two decades. In this paper a detailed statistical analysis of this data is given and detector long term behaviour is provided to the scientific community. We include failure, failure mode, repair frequency, repair outcome and its influence in the energy efficiency and energy resolution. A remarkable result is that the life span distribution is exponential. A detector's failure is a memory-less process, where a previous failure does not influence the upcoming one. Repaired spectrometers result in high reliability with deep implications in the management of large scale high-resolution gamma spectrometry related projects. Findings show that on average, detectors initial counting efficiency is slightly lower (∼2%) than that reported by the manufacturers and the repair process (including annealing) does not affect significantly the energy efficiency, even after a long period of use. Repaired detector energy resolution statistics show that the probability, that a repaired detector will be at least as good as it was originally, is more than 3/4.

Spectral response of multi-element silicon detectors

Energy Technology Data Exchange (ETDEWEB)

Ludewigt, B.A.; Rossington, C.S.; Chapman, K. [Univ. of California, Berkeley, CA (United States)

1997-04-01

Multi-element silicon strip detectors, in conjunction with integrated circuit pulse-processing electronics, offer an attractive alternative to conventional lithium-drifted silicon Si(Li) and high purity germanium detectors (HPGe) for high count rate, low noise synchrotron x-ray fluorescence applications. One of the major differences between the segmented Si detectors and the commercially available single-element Si(Li) or HPGe detectors is that hundreds of elements can be fabricated on a single Si substrate using standard silicon processing technologies. The segmentation of the detector substrate into many small elements results in very low noise performance at or near, room temperature, and the count rate of the detector is increased many-fold due to the multiplication in the total number of detectors. Traditionally, a single channel of detector with electronics can handle {approximately}100 kHz count rates while maintaining good energy resolution; the segmented detectors can operate at greater than MHz count rates merely due to the multiplication in the number of channels. One of the most critical aspects in the development of the segmented detectors is characterizing the charge sharing and charge loss that occur between the individual detector strips, and determining how these affect the spectral response of the detectors.

True coincidence summing corrections for an extended energy range HPGe detector

Energy Technology Data Exchange (ETDEWEB)

Venegas-Argumedo, Y. [Centro de Investigación en Materiales Avanzados (CIMAV), Miguel de Cervantes 120, Chihuahua, Chih 31109 (Mexico); M.S. Student at CIMAV (Mexico); Montero-Cabrera, M. E., E-mail: elena.montero@cimav.edu.mx [Centro de Investigación en Materiales Avanzados (CIMAV), Miguel de Cervantes 120, Chihuahua, Chih 31109 (Mexico)

2015-07-23

True coincidence summing (TCS) effect for natural radioactive families of U-238 and Th-232 represents a problem when an environmental sample with a close source-detector geometry measurement is performed. By using a certified multi-nuclide standard source to calibrate an energy extended range (XtRa) HPGe detector, it is possible to obtain an intensity spectrum slightly affected by the TCS effect with energies from 46 to 1836 keV. In this work, the equations and some other considerations required to calculate the TCS correction factor for isotopes of natural radioactive chains are described. It is projected a validation of the calibration, performed with the IAEA-CU-2006-03 samples (soil and water)

SU-F-T-368: Improved HPGe Detector Precise Efficiency Calibration with Monte Carlo Simulations and Radioactive Sources

Energy Technology Data Exchange (ETDEWEB)

Zhai, Y. John [Vanderbilt University, Vanderbilt-Ingram Cancer Center, Nashville, TN 37232 (United States)

2016-06-15

Purpose: To obtain an improved precise gamma efficiency calibration curve of HPGe (High Purity Germanium) detector with a new comprehensive approach. Methods: Both of radioactive sources and Monte Carlo simulation (CYLTRAN) are used to determine HPGe gamma efficiency for energy range of 0–8 MeV. The HPGe is a GMX coaxial 280 cm{sup 3} N-type 70% gamma detector. Using Momentum Achromat Recoil Spectrometer (MARS) at the K500 superconducting cyclotron of Texas A&M University, the radioactive nucleus {sup 24} Al was produced and separated. This nucleus has positron decays followed by gamma transitions up to 8 MeV from {sup 24} Mg excited states which is used to do HPGe efficiency calibration. Results: With {sup 24} Al gamma energy spectrum up to 8MeV, the efficiency for γ ray 7.07 MeV at 4.9 cm distance away from the radioactive source {sup 24} Al was obtained at a value of 0.194(4)%, by carefully considering various factors such as positron annihilation, peak summing effect, beta detector efficiency and internal conversion effect. The Monte Carlo simulation (CYLTRAN) gave a value of 0.189%, which was in agreement with the experimental measurements. Applying to different energy points, then a precise efficiency calibration curve of HPGe detector up to 7.07 MeV at 4.9 cm distance away from the source {sup 24} Al was obtained. Using the same data analysis procedure, the efficiency for the 7.07 MeV gamma ray at 15.1 cm from the source {sup 24} Al was obtained at a value of 0.0387(6)%. MC simulation got a similar value of 0.0395%. This discrepancy led us to assign an uncertainty of 3% to the efficiency at 15.1 cm up to 7.07 MeV. The MC calculations also reproduced the intensity of observed single-and double-escape peaks, providing that the effects of positron annihilation-in-flight were incorporated. Conclusion: The precision improved gamma efficiency calibration curve provides more accurate radiation detection and dose calculation for cancer radiotherapy treatment.

Experimental and simulated efficiency of a HPGe detector in the energy range of 0.06∼11 MeV

International Nuclear Information System (INIS)

Park, Chang Su; Choi, H. D.; Sun, Gwang Min

2003-01-01

The full energy peak efficiency of a Hyper Pure Germanium (HPGe) detector was calibrated in a wide energy range from 0.06 to 11 MeV. Both the experimental technique and the Monte Carlo method were used for the efficiency calibration. The measurement was performed using the standard radioisotopes in the low energy region of 60∼1408 keV, which was further extended up to 11 MeV by using the 14 N(n,γ) and 35 Cl(n,γ) reactions. The GEANT Monte Carlo code was used for efficiency calculation. The calculated efficiency had the same dependency on the γ-ray energy with the measurement, and the discrepancy between the calculation and the measurement was minimized by fine-tuning of the detector geometry. From the calculated result, the efficiency curve of the HPGe detector was reliably determined particularly in the high energy region above several MeV, where the number of measured efficiency points is relatively small despite the wide energy region. The calculated efficiency agreed with the measurement within about 7%. In addition to the efficiency calculation, the origin of the local minimum near 600 keV on the efficiency curve was analyzed as a general characteristics of a HPGe detector

A Comparison between HPGe and NaI(Tl) detectors performance for gamma-spectrometry of low level measurement

International Nuclear Information System (INIS)

Poursiamy, N. H.; Tajikahmadi, H.; Mirshojaei, S. F.

2005-01-01

According to progressive usage of nuclear technology, it's important to prevent the contamination of the environment by man-made radioisotopes and exposures of human being. Radioisotopes can enter the human body by inhalation and ingestion which are the most important ways to internal exposures. Measurement of radiation level in foodstuff is one of the most important parameters in environmental safety which is performed according to constitution and standard tests in most countries such as Iran. Gamma spectrometry is carried out by NaI(Tl) and HPGe detector systems for foodstuffs. In this research operation of HPGe and NaI(Tl) detectors in gamma spectrometry with a standard radioactive source are investigated and compared. Also the result of NaI superiority in foodstuff radiation measurement given

Development of a technique for the efficiency calibration of a HPGe detector for the off gas samples of a nuclear reactor

International Nuclear Information System (INIS)

Singh, Sarbjit; Agarwal, Chhavi; Ramaswami, A.; Manchanda, V.K.

2007-01-01

Regular monitoring of off gases released to the environment from a nuclear reactor is mandatory. The gaseous fission products are estimated by gamma ray spectrometry using a HPGe detector coupled to a multichannel analyser. In view of the lack of availability of gaseous fission products standards, an indirect method based on the charcoal absorption technique was developed for the efficiency calibration of HPGe detector system using 133B a and 152E u standards. The known activities of 133B a and 152E u are uniformly distributed in a vial having activated charcoal and counted on the HPGe detector system at liquid nitrogen temperature to determine the gamma ray efficiency for the vial having activated charcoal. The ratio of the gamma ray efficiencies of off gas present in the normal vial and the vial having activated charcoal at liquid nitrogen temperature are used to determine the gamma ray efficiency of off gas present in the normal vial. (author)

Calibration of a HPGe detector for Marinelli vessel geometry for measurement of gaseous 41Ar activity using MCNP

International Nuclear Information System (INIS)

Raghunath, T.; Narasimhanath, V.; Sunil, C.N.; Kumaravel, S.; Ramakrishna, V.; Prashanth Kumar, M.; Nair, B.S.K.; Purohit, R.G.; Sarkar, P.K.

2012-01-01

To carry out measurement of 41 Ar gaseous activity an attempt is made to calibrate the detector (HPGe) for Standard Measuring Flask (SMF) and Marinelli vessel geometry and compare their efficiencies. As standard gaseous source of 41 Ar is not available the calibration is done using liquid standard source of 22 Na (having 1274.5 KeV gamma energy close to the 1293.6 KeV gamma energy of 41 Ar). The HPGe detector and both the geometries are simulated and efficiencies for Full Energy Peak (FEP) are obtained using MCNP. The correction factor for energy and sample matrix is obtained from simulated efficiencies. By applying these correction factors the calibration is done. (author)

Mod 1 ICS TI Report: ICS Conversion of a 140% HPGe Detector

Energy Technology Data Exchange (ETDEWEB)

Bounds, John Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-07-05

This report evaluates the Mod 1 ICS, an electrically cooled 140% HPGe detector. It is a custom version of the ORTEC Integrated Cooling System (ICS) modified to make it more practical for us to use in the field. Performance and operating characteristics of the Mod 1 ICS are documented, noting both pros and cons. The Mod 1 ICS is deemed a success. Recommendations for a Mod 2 ICS, a true field prototype, are provided.

Soucreless efficiency calibration for HPGe detector based on medical images

International Nuclear Information System (INIS)

Chen Chaobin; She Ruogu; Xiao Gang; Zuo Li

2012-01-01

Digital phantom of patient and region of interest (supposed to be filled with isotropy volume source) are built from medical CT images. They are used to calculate the detection efficiency of HPGe detectors located outside of human body by sourceless calibration method based on a fast integral technique and MCNP code respectively, and the results from two codes are in good accord besides a max difference about 5% at intermediate energy region. The software produced in this work are in better behavior than Monte Carlo code not only in time consume but also in complexity of problem to solve. (authors)

Theoretical determination of spectrum-exposure rate conversion operator of HPGe detector and its application to the measurement of environmental gamma-ray exposure rate

International Nuclear Information System (INIS)

Park, Ch.M.; Choi, B.I.; Kwak, S.S.; Ji, P.K.; Kim, T.W.; Park, Y.W.; Yoon, B.K.

1993-01-01

A conversion operator between spectrum and exposure rate, using a portable HPGe detector for environmental radiation monitoring, was determined theoretically under the assumption of uniform distribution of radiation source on the ground surface. The measurement results were compared with those of a pressurized ionization chamber. The results obtained with the HPGe detector were slightly lower. The method can be easily applied to any gamma ray detector to obtain a spectrum - exposure-rate conversion factor for computing the exposure rate of environmental gamma radiation. (N.T.) 15 refs.; 6 figs.; 3 tabs

A fitting algorithm based on simulated annealing techniques for efficiency calibration of HPGe detectors using different mathematical functions

Energy Technology Data Exchange (ETDEWEB)

Hurtado, S. [Servicio de Radioisotopos, Centro de Investigacion, Tecnologia e Innovacion (CITIUS), Universidad de Sevilla, Avda. Reina Mercedes s/n, 41012 Sevilla (Spain)], E-mail: shurtado@us.es; Garcia-Leon, M. [Departamento de Fisica Atomica, Molecular y Nuclear, Facultad de Fisica, Universidad de Sevilla, Aptd. 1065, 41080 Sevilla (Spain); Garcia-Tenorio, R. [Departamento de Fisica Aplicada II, E.T.S.A. Universidad de Sevilla, Avda, Reina Mercedes 2, 41012 Sevilla (Spain)

2008-09-11

In this work several mathematical functions are compared in order to perform the full-energy peak efficiency calibration of HPGe detectors using a 126cm{sup 3} HPGe coaxial detector and gamma-ray energies ranging from 36 to 1460 keV. Statistical tests and Monte Carlo simulations were used to study the performance of the fitting curve equations. Furthermore the fitting procedure of these complex functional forms to experimental data is a non-linear multi-parameter minimization problem. In gamma-ray spectrometry usually non-linear least-squares fitting algorithms (Levenberg-Marquardt method) provide a fast convergence while minimizing {chi}{sub R}{sup 2}, however, sometimes reaching only local minima. In order to overcome that shortcoming a hybrid algorithm based on simulated annealing (HSA) techniques is proposed. Additionally a new function is suggested that models the efficiency curve of germanium detectors in gamma-ray spectrometry.

Assessment of applicability of portable HPGe detector with in situ object counting system based on performance evaluation of thyroid radiobioassays

Energy Technology Data Exchange (ETDEWEB)

Park, Min Seok; Kwon, Tae Eun; Pak, Min Jung; Park, Se Young; Ha, Wi Ho; Jin, Young Woo [National Radiation Emergency Medical Center, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)

2017-06-15

Different cases exist in the measurement of thyroid radiobioassays owing to the individual characteristics of the subjects, especially the potential variation in the counting efficiency. An In situ Object Counting System (ISOCS) was developed to perform an efficiency calibration based on the Monte Carlo calculation, as an alternative to conventional calibration methods. The purpose of this study is to evaluate the applicability of ISOCS to thyroid radiobioassays by comparison with a conventional thyroid monitoring system. The efficiency calibration of a portable high-purity germanium (HPGe) detector was performed using ISOCS software. In contrast, the conventional efficiency calibration, which needed a radioactive material, was applied to a scintillator-based thyroid monitor. Four radioiodine samples that contained 125I and 131I in both aqueous solution and gel forms were measured to evaluate radioactivity in the thyroid. ANSI/HPS N13.30 performance criteria, which included the relative bias, relative precision, and root-mean-squared error, were applied to evaluate the performance of the measurement system. The portable HPGe detector could measure both radioiodines with ISOCS but the thyroid monitor could not measure 125I because of the limited energy resolution of the NaI(Tl) scintillator. The 131I results from both detectors agreed to within 5% with the certified results. Moreover, the 125I results from the portable HPGe detector agreed to within 10% with the certified results. All measurement results complied with the ANSI/HPS N13.30 performance criteria. The results of the intercomparison program indicated the feasibility of applying ISOCS software to direct thyroid radiobioassays. The portable HPGe detector with ISOCS software can provide the convenience of efficiency calibration and higher energy resolution for identifying photopeaks, compared with a conventional thyroid monitor with a NaI(Tl) scintillator. The application of ISOCS software in a radiation

Scoping measurements of radionuclides in L Lake with an underwater HPGe detector

International Nuclear Information System (INIS)

Dunn, D.L.; Win, W.G.; Bresnahan, P.J.

1996-01-01

This study of L Lake was conducted to determine whether the distribution of man-made radiation levels had changed from the time preceding the filling of the newly created lake in 1985. Overflight gamma measurements by EG ampersand G in 1985 mapped the man-made radiation levels, indicating that significant levels were only detected from former stream beds that were to be covered by the lake. the present scoping gamma measurements were consistent with these earlier findings, indicating no major evidence of movement of the radioactivity. These results will be available to guide decisions concerning future plans for the lake. Gamma-emitting radionuclides of L Lake were examined in situ with an underwater HPGe detector and further studied by retrieving various sediment samples for analysis by HPGe gamma spectrometry in the Underground Counting Facility. The predominant man-made radionuclide detected was 137 Cs; it had about 100 times greater activity than 60 Co, which was the only other man-made radionuclide that was detected above trace levels

Fitted curve parameters for the efficiency of a coaxial HPGe Detector

International Nuclear Information System (INIS)

Supian Samat

1996-01-01

Using Ngraph software, the parameters of various functions were determined by least squares analysis of fits to experimental efficiencies , ε sub f of a coaxial HPGe detector for gamma rays in the energy range 59 keV to 1836 keV. When these parameters had been determined, their reliability was tested by the calculated goodness-of-fit parameter χ sup 2 sub cal. It is shown that the function, ln ε sub f = Σ sup n sub j=0 a sub j (ln E/E sub 0) sup j , where n=3, gives satisfactory results

Use of planar HPGe detector as a part of X-ray fluorescent spectrometer for educational purposes

International Nuclear Information System (INIS)

Verenchikova, M.S.; Kalinin, V.N.; Mikhajlov, V.A.

2011-01-01

This work shows the possibility of use of the nondedicated gamma and X-ray detection head on the basis of planar HPGe detector with a big sensitive area equal to 2000 mm''2 as a part of X-ray fluorescent spectrometer during students' practicum.

Tow efficiency correction functions of source self-absorption of an HPGe detector

International Nuclear Information System (INIS)

Gao Zheng; Ma Yusheng; Luo Jianghua; Chen Luning

2007-01-01

The efficiency correction function of source absorption of an HPGe γ detector is determined by experiment in energy range from 59.5 keV to 1408 keV and density range from 0.3 g/cm 3 to 2.0 g/cm 3 . Fit Polynomial and fit Sigmoidal are compared. The results show that fit Sigmoidal is better than fit polynomial, and the detection efficiency at any points of energy and density could be conveniently calculated with it in calibrated range. (authors)

Validation of an efficiency calibration procedure for a coaxial n-type and a well-type HPGe detector used for the measurement of environmental radioactivity

Energy Technology Data Exchange (ETDEWEB)

Morera-Gómez, Yasser, E-mail: ymore24@gamail.com [Centro de Estudios Ambientales de Cienfuegos, AP 5. Ciudad Nuclear, CP 59350 Cienfuegos (Cuba); Departamento de Química y Edafología, Universidad de Navarra, Irunlarrea No 1, Pamplona 31009, Navarra (Spain); Cartas-Aguila, Héctor A.; Alonso-Hernández, Carlos M.; Nuñez-Duartes, Carlos [Centro de Estudios Ambientales de Cienfuegos, AP 5. Ciudad Nuclear, CP 59350 Cienfuegos (Cuba)

2016-05-11

To obtain reliable measurements of the environmental radionuclide activity using HPGe (High Purity Germanium) detectors, the knowledge of the absolute peak efficiency is required. This work presents a practical procedure for efficiency calibration of a coaxial n-type and a well-type HPGe detector using experimental and Monte Carlo simulations methods. The method was performed in an energy range from 40 to 1460 keV and it can be used for both, solid and liquid environmental samples. The calibration was initially verified measuring several reference materials provided by the IAEA (International Atomic Energy Agency). Finally, through the participation in two Proficiency Tests organized by IAEA for the members of the ALMERA network (Analytical Laboratories for the Measurement of Environmental Radioactivity) the validity of the developed procedure was confirmed. The validation also showed that measurement of {sup 226}Ra should be conducted using coaxial n-type HPGe detector in order to minimize the true coincidence summing effect. - Highlights: • An efficiency calibration for a coaxial and a well-type HPGe detector was performed. • The calibration was made using experimental and Monte Carlo simulations methods. • The procedure was verified measuring several reference materials provided by IAEA. • Calibrations were validated through the participation in 2 ALMERA Proficiency Tests.

Simulated minimum detectable activity concentration (MDAC) for a real-time UAV airborne radioactivity monitoring system with HPGe and LaBr_3 detectors

International Nuclear Information System (INIS)

Tang, Xiao-Bin; Meng, Jia; Wang, Peng; Cao, Ye; Huang, Xi; Wen, Liang-Sheng; Chen, Da

2016-01-01

An automatic real-time UAV airborne radioactivity monitoring system with high-purity germanium (HPGe) and lanthanum bromide (LaBr_3) detectors (NH-UAV) was developed to precisely obtain small-scope nuclide information in major nuclear accidents. The specific minimum detectable activity concentration (MDAC) calculation method for NH-UAV in the atmospheric environment was deduced in this study for a priori evaluation and quantification of the suitability of NH-UAV in the Fukushima nuclear accident, where the MDAC values of this new equipment were calculated based on Monte Carlo simulation. The effects of radioactive source term size and activity concentration on the MDAC values were analyzed to assess the detection performance of NH-UAV in more realistic environments. Finally, the MDAC values were calculated at different shielding thicknesses of the HPGe detector to improve the detection capabilities of the HPGe detector, and the relationship between the MDAC and the acquisition time of the system was deduced. The MDAC calculation method and data results in this study may be used as a reference for in-situ radioactivity measurement of NH-UAV. - Highlights: • A real-time UAV airborne radioactivity monitoring system (NH-UAV) was developed. • The efficiency calculations and MDAC values are given. • NH-UAV is able to monitor major nuclear accidents, such as the Fukushima accident. • The source term size can influence the detection sensitivity of the system. • The HPGe detector possesses measurement thresholds on activity concentration.

Ninth degree polynomial fit function for calculation of efficiency calibrations for Ge(Li) and HPGe detectors

International Nuclear Information System (INIS)

Uosif, M.A.M.

2006-01-01

A new 9 th degree polynomial fit function has been constructed to calculate the absolute γ-ray detection efficiencies (ηth) of Ge(Li) and HPGe Detectors, for calculating the absolute efficiency at any interesting γ-energy in the energy range between 25 and 2000 keV and distance between 6 and 148 cm. The total absolute γ -ray detection efficiencies have been calculated for six detectors, three of them are Ge(Li) and three HPGe at different distances. The absolute efficiency of the different detectors was calculated at the specific energy of the standard sources for each measuring distances. In this calculation, experimental (η e xp) and fitting (η f it) efficiency have been calculated. Seven calibrated point sources Am-241, Ba-133, Co-57, Co-60, Cs-137, Eu-152 and Ra-226 were used. The uncertainties of efficiency calibration have been calculated also for quality control. The measured (η e xp) and (η f it) calculated efficiency values were compared with efficiency, which calculated, by Gray fit function (time)- The results obtained on the basis of (η e xp)and (η f it) seem to be in very good agreement

Correction for hole trapping in AGATA detectors using pulse shape analysis

Energy Technology Data Exchange (ETDEWEB)

Bruyneel, B. [CEA Saclay, DSM/IRFU/SPhN, Gif-sur-Yvette Cedex (France); Universitaet zu Koeln, Institut fuer Kernphysik, Koeln (Germany); Birkenbach, B.; Eberth, J.; Hess, H.; Pascovici, Gh.; Reiter, P.; Wiens, A. [Universitaet zu Koeln, Institut fuer Kernphysik, Koeln (Germany); Bazzacco, D.; Farnea, E.; Michelagnoli, C.; Recchia, F. [INFN, Sezione di Padova, Padova (Italy); Collaboration: for the AGATA Collaboration

2013-05-15

Data from the highly segmented High-Purity Germanium (HPGe) detectors of the AGATA spectrometer show that segments are more sensitive to neutron damage than the central core contact. Calculations on the collection efficiency of charge carriers inside the HPGe detector were performed in order to understand this phenomenon. The trapping sensitivity, an expression based on the collection efficiencies for electrons and holes, is put forward to quantify the effect of charge carrier trapping. The sensitivity is evaluated for each position in the detector volume with respect to the different electrodes and the collected charge carrier type. Using the position information obtained by pulse shape analysis from the position-sensitive AGATA detectors, it is possible to correct for the energy deficit employing detector specific sensitivity values. We report on the successful correction of the energy peaks from heavily neutron-damaged AGATA detectors for core and segment electrode signals. The original energy resolution can optimally be recovered up to a certain quantifiable limit of degradation due to statistical fluctuations caused by trapping effects. (orig.)

Computational characterization of HPGe detectors usable for a wide variety of source geometries by using Monte Carlo simulation and a multi-objective evolutionary algorithm

Energy Technology Data Exchange (ETDEWEB)

Guerra, J.G., E-mail: jglezg2002@gmail.es [Departamento de Física, Universidad de Las Palmas de Gran Canaria, 35001 Las Palmas de Gran Canaria (Spain); Rubiano, J.G. [Departamento de Física, Universidad de Las Palmas de Gran Canaria, 35001 Las Palmas de Gran Canaria (Spain); Instituto Universitario de Estudios Ambientales y Recursos Naturales, Universidad de Las Palmas de Gran Canaria, 35001 Las Palmas de Gran Canaria (Spain); Winter, G. [Instituto Universitario de Sistemas Inteligentes y Aplicaciones Numéricas en la Ingeniería, Universidad de Las Palmas de Gran Canaria, 35001 Las Palmas de Gran Canaria (Spain); Guerra, A.G.; Alonso, H.; Arnedo, M.A.; Tejera, A.; Martel, P. [Departamento de Física, Universidad de Las Palmas de Gran Canaria, 35001 Las Palmas de Gran Canaria (Spain); Instituto Universitario de Estudios Ambientales y Recursos Naturales, Universidad de Las Palmas de Gran Canaria, 35001 Las Palmas de Gran Canaria (Spain); Bolivar, J.P. [Departamento de Física Aplicada, Universidad de Huelva, 21071 Huelva (Spain)

2017-06-21

In this work, we have developed a computational methodology for characterizing HPGe detectors by implementing in parallel a multi-objective evolutionary algorithm, together with a Monte Carlo simulation code. The evolutionary algorithm is used for searching the geometrical parameters of a model of detector by minimizing the differences between the efficiencies calculated by Monte Carlo simulation and two reference sets of Full Energy Peak Efficiencies (FEPEs) corresponding to two given sample geometries, a beaker of small diameter laid over the detector window and a beaker of large capacity which wrap the detector. This methodology is a generalization of a previously published work, which was limited to beakers placed over the window of the detector with a diameter equal or smaller than the crystal diameter, so that the crystal mount cap (which surround the lateral surface of the crystal), was not considered in the detector model. The generalization has been accomplished not only by including such a mount cap in the model, but also using multi-objective optimization instead of mono-objective, with the aim of building a model sufficiently accurate for a wider variety of beakers commonly used for the measurement of environmental samples by gamma spectrometry, like for instance, Marinellis, Petris, or any other beaker with a diameter larger than the crystal diameter, for which part of the detected radiation have to pass through the mount cap. The proposed methodology has been applied to an HPGe XtRa detector, providing a model of detector which has been successfully verificated for different source-detector geometries and materials and experimentally validated using CRMs. - Highlights: • A computational method for characterizing HPGe detectors has been generalized. • The new version is usable for a wider range of sample geometries. • It starts from reference FEPEs obtained through a standard calibration procedure. • A model of an HPGe XtRa detector has been

Computational characterization of HPGe detectors usable for a wide variety of source geometries by using Monte Carlo simulation and a multi-objective evolutionary algorithm

International Nuclear Information System (INIS)

Guerra, J.G.; Rubiano, J.G.; Winter, G.; Guerra, A.G.; Alonso, H.; Arnedo, M.A.; Tejera, A.; Martel, P.; Bolivar, J.P.

2017-01-01

In this work, we have developed a computational methodology for characterizing HPGe detectors by implementing in parallel a multi-objective evolutionary algorithm, together with a Monte Carlo simulation code. The evolutionary algorithm is used for searching the geometrical parameters of a model of detector by minimizing the differences between the efficiencies calculated by Monte Carlo simulation and two reference sets of Full Energy Peak Efficiencies (FEPEs) corresponding to two given sample geometries, a beaker of small diameter laid over the detector window and a beaker of large capacity which wrap the detector. This methodology is a generalization of a previously published work, which was limited to beakers placed over the window of the detector with a diameter equal or smaller than the crystal diameter, so that the crystal mount cap (which surround the lateral surface of the crystal), was not considered in the detector model. The generalization has been accomplished not only by including such a mount cap in the model, but also using multi-objective optimization instead of mono-objective, with the aim of building a model sufficiently accurate for a wider variety of beakers commonly used for the measurement of environmental samples by gamma spectrometry, like for instance, Marinellis, Petris, or any other beaker with a diameter larger than the crystal diameter, for which part of the detected radiation have to pass through the mount cap. The proposed methodology has been applied to an HPGe XtRa detector, providing a model of detector which has been successfully verificated for different source-detector geometries and materials and experimentally validated using CRMs. - Highlights: • A computational method for characterizing HPGe detectors has been generalized. • The new version is usable for a wider range of sample geometries. • It starts from reference FEPEs obtained through a standard calibration procedure. • A model of an HPGe XtRa detector has been

Influence of the geometrical characteristics of an HpGe detector on its efficiency

International Nuclear Information System (INIS)

Vargas, M.J.; Timon, A.F.; Sanchez, D.P.

2002-01-01

Computer codes based on Monte Carlo calculations have been extensively developed for the computation of the efficiency in gamma-ray spectrometry. The errors in the specific parameters of the detector due to the lack of precise knowledge of its characteristics usually represent one of the most important sources of inaccuracy in this simulation technique. Influence of several detector parameters on the efficiency for a typical coaxial n-type HpGe detector is presented. Calculations of the full-energy peak efficiencies were performed by means of a Monte Carlo code in the range 122-1836 keV for several types of source configuration: point source, cellulose filter, and two different cylindrical boxes containing a solid matrix of SiO 2 . The detector parameters varied were the crystal diameter, crystal height, diameter of the internal core, and the position of the crystal with respect to the beryllium window. Significant deviations in the efficiency, depending on the source geometry and the photon energy, can be produced by varying only slightly some of the detector parameters. (author)

Determination of the dead layer and full-energy peak efficiency of an HPGe detector using the MCNP code and experimental results

Directory of Open Access Journals (Sweden)

M Moeinifar

2017-02-01

Full Text Available One important factor in using an High Purity Germanium (HPGe detector is its efficiency that highly depends on the geometry and absorption factors, so that when the configuration of source-detector geometry is changed, the detector efficiency must be re-measured. The best way of determining the efficiency of a detector is measuring the efficiency of standard sources. But considering the fact that standard sources are hardly available and it is time consuming to find them, determinig the efficiency by simulation which gives enough efficiency in less time, is important. In this study, the dead layer thickness and the full-energy peak efficiency of an HPGe detector was obtained by Monte Carlo simulation, using MCNPX code. For this, we first measured gamma–ray spectra for different sources placed at various distances from the detector and stored the measured spectra obtained. Then the obtained spectra were simulated under similar conditions in vitro.At first, the whole volume of germanium was regarded as active, and the obtaind spectra from calculation were compared with the corresponding experimental spectra. Comparison of the calculated spectra with the measured spectra showed considerable differences. By making small variations in the dead layer thickness of the detector (about a few hundredths of a millimeter in the simulation program, we tried to remove these differences and in this way a dead layer of 0.57 mm was obtained for the detector. By incorporating this value for the dead layer in the simulating program, the full-energy peak efficiency of the detector was then obtained both by experiment and by simulation, for various sources at various distances from the detector, and both methods showed good agreements. Then, using MCNP code and considering the exact measurement system, one can conclude that the efficiency of an HPGe detector for various source-detector geometries can be calculated with rather good accuracy by simulation method

An investigation of the performance of a coaxial HPGe detector operating in a magnetic resonance imaging field

Energy Technology Data Exchange (ETDEWEB)

Harkness, L.J., E-mail: ljh@ns.ph.liv.ac.u [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Boston, A.J.; Boston, H.C.; Cole, P.; Cresswell, J.R.; Filmer, F.; Jones, M.; Judson, D.S.; Nolan, P.J.; Oxley, D.C.; Sampson, J.A.; Scraggs, D.P.; Slee, M.J. [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Bimson, W.E.; Kemp, G.J. [MARIARC, University of Liverpool, Liverpool L69 3GE (United Kingdom); Groves, J.; Headspith, J.; Lazarus, I.; Simpson, J. [STFC Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom); Cooper, R.J. [Joint Institute for Heavy Ion Research, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6371 (United States)

2011-05-11

Nuclear medical imaging modalities such as positron emission tomography and single photon emission computed tomography are used to probe physiological functions of the body by detecting gamma rays emitted from biologically targeted radiopharmaceuticals. A system which is capable of simultaneous data acquisition for nuclear medical imaging and magnetic resonance imaging is highly sought after by the medical imaging community. Such a device could provide a more complete medical insight into the functions of the body within a well-defined structural context. However, acquiring simultaneous nuclear/MRI sequences are technically challenging due to the conventional photomultiplier tube readout employed by most existing scintillator detector systems. A promising solution is a nuclear imaging device composed of semiconductor detectors that can be operated with a standard MRI scanner. However, the influence of placing a semiconductor detector such as high purity germanium (HPGe) within or close to the bore of an MRI scanner, where high magnetic fields are present, is not well understood. In this paper, the performance of a HPGe detector operating in a high strength static (B{sub S}) MRI field along with fast switching gradient fields and radiofrequency from the MRI system has been assessed. The influence of the B{sub S} field on the energy resolution of the detector has been investigated for various positions and orientations of the detector within the magnetic field. The results have then been interpreted in terms of the influence of the B{sub S} field on the charge collection properties. MRI images have been acquired with the detector situated at the entrance of the MRI bore to investigate the effects of simultaneous data acquisition on detector performance and MRI imaging.

Development of CANDLES low background HPGe detector and half-life measurement of 180Tam

Science.gov (United States)

Chan, W. M.; Kishimoto, T.; Umehara, S.; Matsuoka, K.; Suzuki, K.; Yoshida, S.; Nakajima, K.; Iida, T.; Fushimi, K.; Nomachi, M.; Ogawa, I.; Tamagawa, Y.; Hazama, R.; Takemoto, Y.; Nakatani, N.; Takihira, Y.; Tozawa, M.; Kakubata, H.; Trang, V. T. T.; Ohata, T.; Tetsuno, K.; Maeda, T.; Khai, B. T.; Li, X. L.; Batpurev, T.

2018-01-01

A low background HPGe detector system was developed at CANDLES Experimental Hall for multipurpose use. Various low background techniques were employed, including hermatic shield design, radon gas suppression, and background reduction analysis. A new pulse shape discrimination (PSD) method was specially created for coaxial Ge detector. Using this PSD method, microphonics noise and background event at low energy region less than 200 keV can be rejected effectively. Monte Carlo simulation by GEANT4 was performed to acquire the detection efficiency and study the interaction of gamma-rays with detector system. For rare decay measurement, the detector was utilized to detect the nature's most stable isomer tantalum-180m (180Tam) decay. Two phases of tantalum physics run were completed with total livetime of 358.2 days, which Phase II has upgraded shield configuration. The world most stringent half-life limit of 180Tam has been successfully achieved.

Performance of an AGATA asymmetric detector

Energy Technology Data Exchange (ETDEWEB)

Boston, A.J. [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom)], E-mail: ajboston@liv.ac.uk; Dimmock, M.R.; Unsworth, C.; Boston, H.C.; Cooper, R.J.; Grint, A.N.; Harkness, L.J. [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Lazarus, I.H. [STFC Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom); Jones, M.; Nolan, P.J.; Oxley, D.C. [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Simpson, J. [STFC Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom); Slee, M. [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom)

2009-06-01

High-resolution gamma-ray detectors based on high-purity germanium crystals (HPGe) are one of the key workhorses of experimental nuclear science. The technical development of such detector technology has been dramatic in recent years. Large volume, high-granularity, electrically segmented HPGe detectors have been realised and a methodology to improve position sensitivity using pulse-shape analysis coupled with the novel technique of gamma-ray tracking has been developed. Collaborations have been established in Europe (Advanced GAmma Tracking Array (AGATA)) [J. Simpson, Acta Phys. Pol. B 36 (2005) 1383] and the USA (GRETA/GRETINA) [C.W. Beausang, Nucl. Instr. and Meth. B 204 (2003)] to build gamma-ray tracking spectrometers. This paper discusses the performance of the first AGATA asymmetric detector that has been tested at the University of Liverpool. The use of a fully digital data acquisition system has allowed detector charge pulse shapes from a selection of well-defined photon interaction positions to be analysed, yielding important information on the position sensitivity of the detector.

Placement of HPGE detectors for whole body counting applications using simulations of voxel phantoms

International Nuclear Information System (INIS)

Marzocchi, O.; Breustedt, B.; Zankl, M.

2010-01-01

The partial body counter at KIT is going to be rebuilt in order to replace the old Ge detectors with four new HPGe detectors. The new installation will also add whole body capabilities to the system, thanks to an improved mechanics able to position the detectors with a high degree of freedom in the chamber. During the definition of the position of the detectors a compromise between the opposite goals of high efficiency and small dependence of the detection efficiency on the position of the source had to be sought. High detection efficiency involves placing the detector near the skin, where the photon flux is maximal, while the second goal involves placing the detectors at a greater distance from the body. The same concept was applied during the definition of the partial body measurement configurations, but the goal was the increase of the specificity of the measurement. In addition, the mechanical installation poses some constraints: two detectors are mounted on carts and therefore can be placed independently around the subjects, but not in front of it, while the other two detectors are mounted on carts hanging from the same rail on the ceiling, therefore their distance from the subject is constrained by the maximum offset between them. (orig.)

Direct determination of the hit locations from experimental HPGe pulses

Energy Technology Data Exchange (ETDEWEB)

Désesquelles, P., E-mail: Pierre.Desesquelles@in2p3.fr [Univ. Paris-Sud, CSNSM CNRS/IN2P3, 15 rue G. Clémenceau, 91405 Orsay (France); Boston, A.J.; Boston, H.C.; Cresswell, J.R.; Dimmock, M.R. [Oliver Lodge Laboratory, The University of Liverpool, Oxford Street, Liverpool L69 7ZE (United Kingdom); Lazarus, I.H. [STFC Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom); Ljungvall, J. [Univ. Paris-Sud, CSNSM CNRS/IN2P3, 15 rue G. Clémenceau, 91405 Orsay (France); Nelson, L. [Oliver Lodge Laboratory, The University of Liverpool, Oxford Street, Liverpool L69 7ZE (United Kingdom); Nga, D.-T. [Univ. Paris-Sud, CSNSM CNRS/IN2P3, 15 rue G. Clémenceau, 91405 Orsay (France); Nolan, P.J.; Rigby, S.V. [Oliver Lodge Laboratory, The University of Liverpool, Oxford Street, Liverpool L69 7ZE (United Kingdom); Simpson, J. [STFC Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom); Van-Oanh, N.-T. [Univ. Paris-Sud, LCP UMR8000 CNRS, 15 rue G. Clémenceau, 91405 Orsay (France)

2013-11-21

The gamma-tracking technique optimises the determination of the energy and emission angle of gamma-rays detected by modern segmented HPGe detectors. This entails the determination, using the delivered pulse shapes, of the interaction points of the gamma-ray within the crystal. The direct method presented here allows the localisation of the hits using only a large sample of pulses detected in the actual operating conditions. No external crystal scanning system or pulse shape simulation code is needed. In order to validate this method, it is applied to sets of pulses obtained using the University of Liverpool scanning system. The hit locations are determined by the method with good precision.

An automated measuring system based on gamma spectrometry with HPGe detectors

International Nuclear Information System (INIS)

Mala, Helena; Rulik, Petr; Hyza, Miroslav; Dragounova, Lenka; Helebrant, Jan; Hroznicek, Marek; Jelinek, Pavel; Zak, Jan

2016-01-01

An automatic system for unattended gamma spectrometric measurements of bulk samples ( “Gamma Automat”, GA) was developed by the National Radiation Protection Institute and Nuvia, Inc. as a part of a research project. The basic parts include a detection system with two HPGe detectors in the lead shielded chambers, sample changer, sample tray and a control unit. The GA enables counting in two geometries: (i) with cylindrical containers (200 ml) either one placed at the detector face or 2-6 placed around the detector or (II) with Marinelli beakers (600 ml). The shelf can accommodate 180 cylindrical containers or 54 Marinelli beakers. Samples are changed by a robotic arm. The sample data and the analysis required are passed to the GA by a matrix code (generated within the laboratory system) located on the lid of a sample container, whence the GA reads information. Spectrometric analysis is performed automatically after the counting. Current status of GA can be remotely monitored. Information about the activities of the GA, measurement completion or failures of the equipment are automatically generated and sent to a mobile phone and the operator PC. A presentation of the GA is available at https://youtu.be/1lQhfo0Fljo. (orig.)

Operation of bare HPGe detectors in LAr/LN{sub 2} for the GERDA experiment

Energy Technology Data Exchange (ETDEWEB)

Heider, M Barnabe; Chkvorets, O; Schoenert, S [MPI fuer Kernphysik, Heidelberg (Germany); Cattadori, C [INFN-Milano Bicocca, Milano (Italy); Vacri, A di [INFN-LNGS, L' Aquila (Italy); Gusev, K; Shirchenko, M [Russian Research Center Kurchatov Institute, Moscow, Russia and JINR, Dubna (Russian Federation)], E-mail: assunta.divacri@lngs.infn.it

2008-11-01

GERDA is designed to search for 0{nu}{beta}{beta}-decay of {sup 76}Ge using high purity germanium detectors (HPGe), enriched ({approx} 85%) in {sup 76}Ge, directly immersed in LAr which acts both as shield against {gamma} radiation and as cooling medium. The cryostat is located in a stainless steel water tank providing an additional shield against external background. The GERDA experiment aims at a background (b) {approx}<10{sup -3} cts/(kg-y-keV) and energy resolution (FWHM) {<=} 4 keV at Q{sub {beta}}{sub {beta}} = 2039 keV. GERDA experiment is foreseen to proceed in two phases. For Phase I, eight reprocessed enriched HPGe detectors from the past HdM [C Balysh et al., Phys. Rev. D 66 (1997) 54] and IGEX [C E Aalseth et al., Phys. of Atomic Nuclei 63 (2000) 1225] experiments ({approx} 18 kg) and six reprocessed natural HPGe detectors ({approx} 15 kg) from the Genius Test-Facility [H V Klapdor et al., HIM A 481 (2002) 149] will be deployed in strings. GERDA aims at b {approx}< 10{sup -2} cts/(kg{center_dot}keV{center_dot}y). With an exposure of {approx} 15 kg{center_dot}y of {sup 76}Ge and resolution {approx} 3.6 keV, the sensitivity on the half-life will be T{sup 0{nu}}{sub 1/2} 3 {center_dot} 10{sup 25} y (90 % C.L.) corresponding to m{sub ee} < 270 meV [V A Rodin et al., Nucl. Phys. A 766 (2006) 107]. In Phase II, new diodes, able to discriminate between single- and multi-site events, will be added ({approx} 20 kg of {sup 76}Ge with intrinsic b {approx} 10{sup -2} cts/(kg{center_dot}keV{center_dot}y). With an exposure of {approx} 120 kg{center_dot}y, it is expected T{sup 0{nu}}{sub 1/2} > 1.5 {center_dot} 10{sup 26} y (90% C.L.) corresponding to m{sub ee} < 110 meV [V A Rodin et al., Nucl. Phys. A 766 (2006) 107]. Three natural p-type HPGe prototypes (different passivation layer designs) are available in the GERDA underground facility at LNGS to investigate the effect of the detector assembly (low-mass low-activity holder), of the handling procedure and of the

Interference of escape peaks from HPGe(LEPS) detector on characteristic X-ray spectrum

International Nuclear Information System (INIS)

Pimjun, S.

1992-01-01

Analyses for concentrations of iron, niobium and tantalum in valuable ores by X-ray fluorescence analysis (XRF) method, characteristic X-rays of Fe was interfered by the escape peak of Nb from HPGe(LEPS) detector. To solve this problem, normalizations of Nb spectra with the computer program were used. The result analyzed for Fe, Nb and Ta concentration in the sample, compared to those with the neutron activation analysis (NAA) method, the corresponding errors about 5% were obtained satisfactorily. This method of XRF can be applied efficiently instead of NAA method during the reactor shut-down for a long period

Peak-to-valley ratios for three different HPGe detectors for the assessment of 137Cs deposition on the ground and the impact of the detector field-of-view.

Science.gov (United States)

Östlund, Karl; Samuelsson, Christer; Mattsson, Sören; Rääf, Christopher L

2017-02-01

The peak-to-valley (PTV) method was investigated experimentally comparing PTV ratios for three HPGe detectors, with complementary Monte Carlo simulations of scatter in air for larger source-detector distances. The measured PTV ratios for 137Cs in air were similar for three different detectors for incident angles between 0 and 90°. The study indicated that the PTV method can differentiate between surface and shallow depth sources if the detector field of view is limited to a radius of less than 3.5m. Copyright © 2016 Elsevier Ltd. All rights reserved.

Measurements of radionuclide in Par Pond sediments with an underwater HPGe detector

International Nuclear Information System (INIS)

Winn, W.G.

1993-01-01

Savannah River Site (SRS) effluent gamma emitting radionuclides in Par Pond sediment were examined in situ with an underwater HPGe detector prior to and following a 19 ft drawdown of the pond in 1991 to address dam repairs. These measurements provide a map of the 137 Cs concentrations of the pond sediment, indicating that 9.4 ± 1.5 Ci is exposed by the drawdown and that 46.6 ± 7.2 Ci is the entire pond inventory. The highest individual 137 Cs concentration was 25 μCi/m 2 for the exposed sediment and 50 μCi/m 2 for the entire pond. The results are consistent with parallel studies conducted by SREL, as well as historical data. Aside from 137 Cs, the only other SRS-produced isotope observed was 60 Co, with activity of only about 1% of that for 137 Cs. This observation was also confirmed in grab samples of pond sediment and vegetation, which were returned to the laboratory for ultra-low-level gamma spectrometry analysis. A special effort was required to calibrate the underwater HPGe detector, where both measurements and calculational models were used. The effects of sediment depth profiles for density and 137 Cs concentration were addressed in the calibration. Calibration factors for sediment surface concentrations (μCi/m 2 /cpm) and sediment mass concentrations (pCi/kg/cpm) were obtained. In general, the μCi/m 2 /cpm factor is recommended, as the pCi/kg/cpm factor depends on the depth location of the sediment of interest. However, a pCi/kg/cpm factor, which is dependent on the depth within the sediment is presented to address dose calculations that require it

Development of portable HPGe spectrometer for in situ measurements

Directory of Open Access Journals (Sweden)

Kail Artjoms

2015-01-01

Full Text Available In situ applications require a very high level of portability of high-resolution spectrometric equipment. Usage of HPGe detectors for radioactivity measurements in the environment or for nuclear safeguard applications, to combat illicit trafficking of nuclear materials or uranium and plutonium monitoring in nuclear wastes, has become a norm in the recent years. Portable HPGe-based radionuclide spectrometer with electrical cooling has lately appeared on the market for in situ applications. At the same time deterioration of energy resolution associated with vibrations produced by cryocooler or high weight of the instrument, short time of autonomous operation and high price of these spectrometers are limiting their usage in many cases. In this paper we present development results of ultra compact hand held all-in-one spectrometer for in situ measurements based on HPGe detector cooled by liquid nitrogen without listing the above disadvantages.

Development of Educational Simulation on Spectrum of HPGe Detector and Implementation of Education Program

International Nuclear Information System (INIS)

Seo, K. W.; Joo, Y. C.; Ji, Y. J.; Lee, M. O.; Lee, S. Y.; Jun, Y. K.

2005-12-01

In this development, characteristics of Aptec, Genie2000(Canberra Co, USA), GammaVision(Ortec Co, USA) which are usually used in Korea radioactive measure laboratory, such as peak search, peak fitting, central area position and area calculation, spectrum correction and method for radioactive calculation are included. And radioactive source geometry, absorption of sample itself, methods for correcting coincidence summing effect is developed and the result effected on spectrum analysis teaching material. Developed simulation HPGe detector spectrum are spectrum for correction, spectrum for correcting radio source-detection duration geometry, sample spectrum which need self absorption correction of radio source, peak search spectrum for optimizing peak search offset setting and background spectrum. These spectrum are made similar to real spectrum by processing peak and background which were measured from mix standard volume radio source. Spectrum analysis teaching material is developed more focus on practical thing than theoretical thing, simulation spectrum must be used in spectrum analysis practise. Optimal method for spectrum analysis condition, spectrum correction, Geometry correction and background spectrum analysis are included in teaching material and also ANSI N42 recommended 'Spectrum analysis program test' procedure is included too. Aptec, Genie2000, Gamma Vision software manuals are included in appendix. In order to check the text of developed simulation on spectrum of HPGe detector, in 2004 and 2005, these was implemented in the other regular course as a course for superviser of the handling with RI. And the text and practical procedure were reviewed through the course and were revised

Monte Carlo Calculation Of HPGe GEM 15P4 Detector Efficiency In The 59 - 2000 keV Energy Range

International Nuclear Information System (INIS)

Trinh Hoai Vinh; Pham Nguyen Thanh Vinh; Hoang Ba Kim; Vo Xuan An

2011-01-01

A precise model of a 15% relative efficiency p-type HPGe GEM 15P4 detector was created for peak efficiency curves determination using the MCNP5 code developed by The Los Alamos Laboratory. The dependence of peak efficiency on distance from the source to detector was also investigated. That model was validated by comparing experimental and calculated results using six standard point sources including 133 Ba, 109 Cd, 57 Co, 60 Co, 22 Na and 65 Zn. The sources used for more simulating are 241 Am, 75 Se, 113 Sn, 85 Sr, 54 Mn, 137 Cs, 56 Co, 94 Nb, 111 In, 139 Ce, 228 Th, 243 Am, 154 Eu, 152 Eu and 88 Y according to IAEA-TECDOC-619 document. All these sources have the same geometry. The ratio of the experimental efficiencies to calculated ones are higher than 0.94. This result indicates that our simulation program based on MCNP5 code is good enough for later studies on this HPGe spectrometer which is located in Nuclear Physics Laboratory at HCMC University of Pedagogy. (author)

Application of PHOTON simulation software on calibration of HPGe detectors

Energy Technology Data Exchange (ETDEWEB)

Nikolic, J., E-mail: jnikolic@vinca.rs [University of Belgrade Institute for Nuclear Sciences Vinča, Mike Petrovica Alasa 12-16, 11001 Belgrade (Serbia); Puzovic, J. [University of Belgrade Faculty of Physics, Studentski trg 6, 11000 Belgrade (Serbia); Todorovic, D.; Rajacic, M. [University of Belgrade Institute for Nuclear Sciences Vinča, Mike Petrovica Alasa 12-16, 11001 Belgrade (Serbia)

2015-11-01

One of the major difficulties in gamma spectrometry of voluminous environmental samples is the efficiency calibration of the detectors used for the measurement. The direct measurement of different calibration sources, containing isolated γ-ray emitters within the energy range of interest, and subsequent fitting to a parametric function, is the most accurate and at the same time most complicated and time consuming method of efficiency calibration. Many other methods are developed in time, some of them using Monte Carlo simulation. One of such methods is a dedicated and user-friendly program PHOTON, developed to simulate the passage of photons through different media with different geometries. This program was used for efficiency calibration of three HPGe detectors, readily used in Laboratory for Environment and Radiation Protection of the Institute for Nuclear Sciences Vinca, Belgrade, Serbia. The simulation produced the spectral response of the detectors for fixed energy and for different sample geometries and matrices. Thus obtained efficiencies were compared to the values obtained by the measurement of the secondary reference materials and to the results obtained by GEANT4 simulation, in order to establish whether the simulated values agree with the experimental ones. To further analyze the results, a realistic measurement of the materials provided by the IAEA within different interlaboratory proficiency tests, was performed. The activities obtained using simulated efficiencies were compared to the reference values provided by the organizer. A good agreement in the mid energy section of the spectrum was obtained, while for low energies the lack of some parameters in the simulation libraries proved to produce unacceptable discrepancies.

Measurements on a prototype segmented Clover detector

CERN Document Server

Shepherd, S L; Cullen, D M; Appelbe, D E; Simpson, J; Gerl, J; Kaspar, M; Kleinböhl, A; Peter, I; Rejmund, M; Schaffner, H; Schlegel, C; France, G D

1999-01-01

The performance of a segmented Clover germanium detector has been measured. The segmented Clover detector is a composite germanium detector, consisting of four individual germanium crystals in the configuration of a four-leaf Clover, housed in a single cryostat. Each crystal is electrically segmented on its outer surface into four quadrants, with separate energy read-outs from nine crystal zones. Signals are also taken from the inner contact of each crystal. This effectively produces a detector with 16 active elements. One of the purposes of this segmentation is to improve the overall spectral resolution when detecting gamma radiation emitted following a nuclear reaction, by minimising Doppler broadening caused by the opening angle subtended by each detector element. Results of the tests with sources and in beam will be presented. The improved granularity of the detector also leads to an improved isolated hit probability compared with an unsegmented Clover detector. (author)

Study of Efficiency Calibrations of HPGe Detectors for Radioactivity Measurements of Environmental Samples

International Nuclear Information System (INIS)

Harb, S.; Salahel Din, K.; Abbady, A.

2009-01-01

In this paper, we describe a method of calibrating of efficiency of a HPGe gamma-ray spectrometry of bulk environmental samples (Tea, crops, water, and soil) is a significant part of the environmental radioactivity measurements. Here we will discuss the full energy peak efficiency (FEPE) of three HPGe detectors it as a consequence, it is essential that the efficiency is determined for each set-up employed. Besides to take full advantage at gamma-ray spectrometry, a set of efficiency at several energies which covers the wide the range in energy, the large the number of radionuclides whose concentration can be determined to measure the main natural gamma-ray emitters, the efficiency should be known at least from 46.54 keV ( 210 Pb) to 1836 keV ( 88 Y). Radioactive sources were prepared from two different standards, a first mixed standard QC Y 40 containing 210 Pb, 241 Am, 109 Cd, and Co 57 , and the second QC Y 48 containing 241 Am, 109 Cd, 57 Co, 139 Ce, 113 Sn, 85 Sr, 137 Cs, 88 Y, and 60 Co is necessary in order to calculate the activity of the different radionuclides contained in a sample. In this work, we will study the efficiency calibration as a function of different parameters as:- Energy of gamma ray from 46.54 keV ( 210 Pb) to 1836 keV ( 88 Y), three different detectors A, B, and C, geometry of containers (point source, marinelli beaker, and cylindrical bottle 1 L), height of standard soil samples in bottle 250 ml, and density of standard environmental samples. These standard environmental sample must be measured before added standard solution because we will use the same environmental samples in order to consider the self absorption especially and composition in the case of volume samples.

Dual photon absorptiometer utilizing a HpGe detector and microprocessor controller

International Nuclear Information System (INIS)

Ellis, K.J.; Vartsky, D.; Pearlstein, T.B.; Alberi, J.L.; Cohn, S.H.

1978-01-01

The analysis of bone mineral content (BMC) using a single energy-photon beam assumes that there are only two materials present, bone mineral and a uniform soft tissue component. Uncertainty in the value of BMC increases with different adipose tissue components in the transmitted beam. These errors, however, are reduced by the dual energy technique. Also, extension to additional energies further identifies the separate constituents of the soft tissue component. A multi-energy bone scanning apparatus with data acquisition and analysis capability sufficient to perform multi-energy analysis of bone mineral content was designed and developed. The present work reports on the development of device operated in the dual energy mode. The high purity germanium (HpGe) detector is an integral component of the scanner. Errors in BMC due to multiple small angle scatters are reduced due to the excellent energy resolution of the detector (530 eV at 60 keV). Also, the need to filter the source or additional collimation on the detector is eliminated. A new dual source holder was designed using 200 mCi 125 I and 100 mCi 241 Am. The active areas of the two source capsules are aligned on a common axis. The congruence of the dual source was verified by measuring the collimator response function. This new holder design insures that the same tissue mass simultaneously attenuates both sources. The controller portion of the microprocessor allows for variation in total scan length, step size, and counting time per step. These options allow for multiple measurements without changes in the detector, source, or collimator. The system has been successfully used to determine the BMC content of different bones

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)

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)

Measurement of radiation shielding properties of polymer composites by using HPGe detector

International Nuclear Information System (INIS)

Gupta, Anil; Pillay, H.C.M.; Kale, P.K.; Datta, D.; Suman, S.K.; Gover, V.

2014-01-01

Lead is the most common radiation shield and its composite with polymers can be used as flexible radiation shields for different applications. However, lead is very hazardous and has been found to be associated with neurological disorders, kidney failure and hematotoxicity. Lead free radiation shield material has been developed by synthesizing radiation cross linked PDMS/Bi 2 O 3 polymer composites. In order to have a lead free radiation shield the relevant shielding properties such as linear attenuation, half value thickness (HVT) and tenth value thickness (TVT) have been measured by using HPGe detector. The present study describes the methodology of measurement of the shielding properties of the lead free shield material. In the measurement gamma energies such as 59.537 keV ( 241 Am), 122.061 keV and 136.474 keV ( 57 Co) are taken into consideration

Computational characterization of HPGe detectors usable for a wide variety of source geometries by using Monte Carlo simulation and a multi-objective evolutionary algorithm

Science.gov (United States)

Guerra, J. G.; Rubiano, J. G.; Winter, G.; Guerra, A. G.; Alonso, H.; Arnedo, M. A.; Tejera, A.; Martel, P.; Bolivar, J. P.

2017-06-01

In this work, we have developed a computational methodology for characterizing HPGe detectors by implementing in parallel a multi-objective evolutionary algorithm, together with a Monte Carlo simulation code. The evolutionary algorithm is used for searching the geometrical parameters of a model of detector by minimizing the differences between the efficiencies calculated by Monte Carlo simulation and two reference sets of Full Energy Peak Efficiencies (FEPEs) corresponding to two given sample geometries, a beaker of small diameter laid over the detector window and a beaker of large capacity which wrap the detector. This methodology is a generalization of a previously published work, which was limited to beakers placed over the window of the detector with a diameter equal or smaller than the crystal diameter, so that the crystal mount cap (which surround the lateral surface of the crystal), was not considered in the detector model. The generalization has been accomplished not only by including such a mount cap in the model, but also using multi-objective optimization instead of mono-objective, with the aim of building a model sufficiently accurate for a wider variety of beakers commonly used for the measurement of environmental samples by gamma spectrometry, like for instance, Marinellis, Petris, or any other beaker with a diameter larger than the crystal diameter, for which part of the detected radiation have to pass through the mount cap. The proposed methodology has been applied to an HPGe XtRa detector, providing a model of detector which has been successfully verificated for different source-detector geometries and materials and experimentally validated using CRMs.

Pulse shapes and surface effects in segmented germanium detectors

Energy Technology Data Exchange (ETDEWEB)

Lenz, Daniel

2010-03-24

It is well established that at least two neutrinos are massive. The absolute neutrino mass scale and the neutrino hierarchy are still unknown. In addition, it is not known whether the neutrino is a Dirac or a Majorana particle. The GERmanium Detector Array (GERDA) will be used to search for neutrinoless double beta decay of {sup 76}Ge. The discovery of this decay could help to answer the open questions. In the GERDA experiment, germanium detectors enriched in the isotope {sup 76}Ge are used as source and detector at the same time. The experiment is planned in two phases. In the first, phase existing detectors are deployed. In the second phase, additional detectors will be added. These detectors can be segmented. A low background index around the Q value of the decay is important to maximize the sensitivity of the experiment. This can be achieved through anti-coincidences between segments and through pulse shape analysis. The background index due to radioactive decays in the detector strings and the detectors themselves was estimated, using Monte Carlo simulations for a nominal GERDA Phase II array with 18-fold segmented germanium detectors. A pulse shape simulation package was developed for segmented high-purity germanium detectors. The pulse shape simulation was validated with data taken with an 19-fold segmented high-purity germanium detector. The main part of the detector is 18-fold segmented, 6-fold in the azimuthal angle and 3-fold in the height. A 19th segment of 5mm thickness was created on the top surface of the detector. The detector was characterized and events with energy deposited in the top segment were studied in detail. It was found that the metalization close to the end of the detector is very important with respect to the length of the of the pulses observed. In addition indications for n-type and p-type surface channels were found. (orig.)

Pulse shapes and surface effects in segmented germanium detectors

International Nuclear Information System (INIS)

Lenz, Daniel

2010-01-01

It is well established that at least two neutrinos are massive. The absolute neutrino mass scale and the neutrino hierarchy are still unknown. In addition, it is not known whether the neutrino is a Dirac or a Majorana particle. The GERmanium Detector Array (GERDA) will be used to search for neutrinoless double beta decay of 76 Ge. The discovery of this decay could help to answer the open questions. In the GERDA experiment, germanium detectors enriched in the isotope 76 Ge are used as source and detector at the same time. The experiment is planned in two phases. In the first, phase existing detectors are deployed. In the second phase, additional detectors will be added. These detectors can be segmented. A low background index around the Q value of the decay is important to maximize the sensitivity of the experiment. This can be achieved through anti-coincidences between segments and through pulse shape analysis. The background index due to radioactive decays in the detector strings and the detectors themselves was estimated, using Monte Carlo simulations for a nominal GERDA Phase II array with 18-fold segmented germanium detectors. A pulse shape simulation package was developed for segmented high-purity germanium detectors. The pulse shape simulation was validated with data taken with an 19-fold segmented high-purity germanium detector. The main part of the detector is 18-fold segmented, 6-fold in the azimuthal angle and 3-fold in the height. A 19th segment of 5mm thickness was created on the top surface of the detector. The detector was characterized and events with energy deposited in the top segment were studied in detail. It was found that the metalization close to the end of the detector is very important with respect to the length of the of the pulses observed. In addition indications for n-type and p-type surface channels were found. (orig.)

Calibration comparative results for X - and gamma ray spectrometry with HPGe and BEGe detectors for a radon reference chamber

International Nuclear Information System (INIS)

Zoran, Maria; Paul, Annette; Arnold, Dirk

2002-01-01

Inhaled decay products of 222 Rn are the dominant components of the natural radiation exposure being responsible for about 30% of the whole human radioactive exposure. Field instruments for 222 Rn and his progeny monitoring are calibrated in 'radon climate rooms', where it is possible to vary and monitor 222 Rn and the indoor air parameters ( temperature, humidity, ventilation rate, aerosol concentration). German radon reference chamber used was developed and installed at the Physikalisch-Technische Bundesanstalt in order to serve as a metrological standard for radon and his progeny calibration of active and passive, indoor and outdoor radon monitoring devices in air climate. The basic parts of experimental setup for this γ and X -ray spectrometry analysis consists of a γ-X ray source in a lead shield/collimator, the detectors, the electronics necessary for pulse-height analysis (PHA) to obtain energy spectra. For calibrating system with 226 Ra standard sources (multienergy X ray and gamma emitters), two germanium detectors HPGe (12.5 nominal efficiency) and BEGe (22.5 nominal efficiency) were used. Germanium detectors are semiconductor diodes having a P-I-N structure in which the Intrinsic (I) region is sensitive to ionizing radiation, particularly X-rays and gamma rays. The BEGe is designed with an electrode structure that enhances low energy resolution and is fabricated from selected germanium having an impurity profile that improves charge collection (thus resolution and peak shape) at high energies which is really important in analysis of the complex spectra for uranium and finally for 226 Ra. MAESTRO MCA software and GNUPLOT program were used for spectra acquisition and spectra analysis, respectively . The main aim of this paper was to do a comparatively analysis of the detector performances for this radon chamber spectrometric chain. The calibration data analysis includes energy calibrations for both detection systems as well as comparative X and gamma

Optimization of statistical methods for HpGe gamma-ray spectrometer used in wide count rate ranges

Energy Technology Data Exchange (ETDEWEB)

Gervino, G., E-mail: gervino@to.infn.it [UNITO - Università di Torino, Dipartimento di Fisica, Turin (Italy); INFN - Istituto Nazionale di Fisica Nucleare, Sez. Torino, Turin (Italy); Mana, G. [INRIM - Istituto Nazionale di Ricerca Metrologica, Turin (Italy); Palmisano, C. [UNITO - Università di Torino, Dipartimento di Fisica, Turin (Italy); INRIM - Istituto Nazionale di Ricerca Metrologica, Turin (Italy)

2016-07-11

The need to perform γ-ray measurements with HpGe detectors is a common technique in many fields such as nuclear physics, radiochemistry, nuclear medicine and neutron activation analysis. The use of HpGe detectors is chosen in situations where isotope identification is needed because of their excellent resolution. Our challenge is to obtain the “best” spectroscopy data possible in every measurement situation. “Best” is a combination of statistical (number of counts) and spectral quality (peak, width and position) over a wide range of counting rates. In this framework, we applied Bayesian methods and the Ellipsoidal Nested Sampling (a multidimensional integration technique) to study the most likely distribution for the shape of HpGe spectra. In treating these experiments, the prior information suggests to model the likelihood function with a product of Poisson distributions. We present the efforts that have been done in order to optimize the statistical methods to HpGe detector outputs with the aim to evaluate to a better order of precision the detector efficiency, the absolute measured activity and the spectra background. Reaching a more precise knowledge of statistical and systematic uncertainties for the measured physical observables is the final goal of this research project.

Development results of portable gamma-radiation HPGe spectrometer with electric cooling for field applications

International Nuclear Information System (INIS)

Kondrat'ev, V.; Loshevich, E.; Pchelintsev, A.; Sokolov, A.; Gostilo, V.

2015-01-01

The paper presents development results of a portable spectrometer based on high purity germanium (HPGe spectrometer) with Stirling electric cooler for field applications. The spectrometer cryostat allows installation of HPGe coaxial detectors with efficiency up to 40% and planar detectors with sensitive area up to 3000 mm2. The detector cooling time is not more than 8 hours. Despite the mechanical vibrations due to electric cooler operation, the obtained energy resolution of the spectrometer with coaxial detector of 10% efficiency was less than 1,0 and 2,0 keV by energies 122 and 1332 keV accordingly. Miniature processor device (Android) allows control for all operation modes of the spectrometer, provides self diagnostics, initial procession, indication and spectra accumulation

In situ prompt gamma-ray activation analysis of water pollutants using a shallow 252Cf-HPGe probe

International Nuclear Information System (INIS)

Chung Chien; Tseng Tzucheng

1988-01-01

A shallow 252 Cf-HPGe probe used for in situ prompt γ-ray activation of water pollutants is described. A 2.7 μg 252 Cf neutron source and a 10% HPGe detector are inserted into a waterproof stainless steel probe, which is designed to be submerged and recovered in field operation. A laboratory test is performed to obtain the neutron flux distribution and prompt γ-ray contribution to the HPGe detector counts from around the submerged probe. The concentrations of toxic cadmium and chlorine in water are determined in the prompt γ-ray spectrum. The detection limit of industrial pollutants and some improvements of the current design are discussed. (orig.)

Deep-water gamma-spectrometer based on HP(Ge) detector

International Nuclear Information System (INIS)

Sokolov, A.; Danengirsh, S.; Popov, S.; Pchelincev, A; Gostilo, V.; Kravchenko, S.; Shapovalov, V.; Druzhinin, A.

1995-01-01

Full text: For radionuclide monitoring of the sea bottom near underwater storage of high active waste of nuclear industries and near places of accidents with nuclear submarines the spectrometers of gamma-radiation, which allow to carry out the measurements on the great depth, are needed. Usually, these problems are solved with devices, which are cast down into the water, using the rope, and transmit the signals on the surface by the cable. However, the depth of immersion is limited by this construction and often the conditions of measurement are complicated. The deep water gamma-spectrometer based on HP(Ge) detector for the measurement on the depth up to 3000 m is developed. The spectrometer is completely autonomic and is put up in the selected place, using the manipulator of a deep-water apparatus. The spectrometer is created in two cylindrical cases with 170 mm diameter and 1100 mm length, bearing the high hydrostatic pressure. The part of the case around the detector is created from titanium and has especial construction with a thin wall for increasing the efficiency of registration in the region of low-energy gamma-radiation. The cooling of the semiconductor detector is provided by a coolant which supports the working temperature of the detector during more than 24 hours. The electronic system of the spectrometer includes high voltage supply f or the detector, preamplifier, analog processor, analog-digital converter and a device for collecting and storing information in flash memory. The power supply of the spectrometer is provided by a battery of accumulators, which can be recharged on the surface. The programming of the processor is carried out before immersion by connecting the spectrometer to personal computer using standard interface RS-232. During 24 hours the spectrometer provides registration of 16 spectrums each in 4096 channels. The reading of the information by the computer is carried out after lifting up the spectrometer on the surface in the same

Numerical expressions for the computation of coincidence-summing correction factors in gamma-ray spectrometry with HPGe detectors

International Nuclear Information System (INIS)

Rizzo, S.; Tomarchio, E.

2008-01-01

to a 60% relative efficiency HPGe detector - are also reported. Point source peak and total efficiency curves are determined by measuring 'single-line' calibration sources while the computation of 'effective efficiencies' was performed by means of a Monte Carlo MCNP5 simulation of HPGe detector response

Electromechanically cooled germanium radiation detector system

International Nuclear Information System (INIS)

Lavietes, Anthony D.; Joseph Mauger, G.; Anderson, Eric H.

1999-01-01

We have successfully developed and fielded an electromechanically cooled germanium radiation detector (EMC-HPGe) at Lawrence Livermore National Laboratory (LLNL). This detector system was designed to provide optimum energy resolution, long lifetime, and extremely reliable operation for unattended and portable applications. For most analytical applications, high purity germanium (HPGe) detectors are the standard detectors of choice, providing an unsurpassed combination of high energy resolution performance and exceptional detection efficiency. Logistical difficulties associated with providing the required liquid nitrogen (LN) for cooling is the primary reason that these systems are found mainly in laboratories. The EMC-HPGe detector system described in this paper successfully provides HPGe detector performance in a portable instrument that allows for isotopic analysis in the field. It incorporates a unique active vibration control system that allows the use of a Sunpower Stirling cycle cryocooler unit without significant spectral degradation from microphonics. All standard isotopic analysis codes, including MGA and MGA++, GAMANL, GRPANL and MGAU, typically used with HPGe detectors can be used with this system with excellent results. Several national and international Safeguards organisations including the International Atomic Energy Agency (IAEA) and U.S. Department of Energy (DOE) have expressed interest in this system. The detector was combined with custom software and demonstrated as a rapid Field Radiometric Identification System (FRIS) for the U.S. Customs Service . The European Communities' Safeguards Directorate (EURATOM) is field-testing the first Safeguards prototype in their applications. The EMC-HPGe detector system design, recent applications, and results will be highlighted

Novel HPGe Probe solution for Harsh Environments

Energy Technology Data Exchange (ETDEWEB)

Clauss, J.; Pirard, B.; Menaa, N.; Quirin, P.; Flamanc, J.; Marian, V.; Lampert, M.O. [CANBERRA France, Parc des Tanneries, 1, chemin de la roseraie, 67380 Lingolsheim (France)

2015-07-01

In situ measurement is a privileged way of monitoring radioactive contamination compared to analyzing samples in a distant, specialized laboratory. Scintillators based spectrometers offer small footprints and are easy to easy to use, however they do not provide an accurate nuclide identification capability and activities measurement because notably of their limited energy resolution, for instance when low minimum detectable activity (MDA) are required, or in complex mixture of sources. On the other hand, High Purity Germanium (HPGe) detectors provide unmatched nuclide identification capability with the lowest MDA but they are not always of practical use on the field because the crystal needs to be cooled down to liquid nitrogen temperature, increasing the overall weight, bulkiness and complexity of the measurement. This paper presents the configuration and performance of a novel turnkey and compact HPGe solution developed by Canberra for radionuclide identification under harsh environments. Radio-contaminations surveys now can be undertaken outdoor under various weather conditions, in contaminated areas, underground or underwater locations (including under sea water), with fast on site deployment. The spectrometer is also designed in a small diameter tubular shape to offer minimal footprint for an operation in narrow and confined spaces. Besides, this innovative design does not mitigate the performances nor the reliability experienced with standard laboratory-grade HPGe spectrometers. This achievement relies on advanced technologies such as the encapsulation of the crystal in ultra-high vacuum (UHV) which provides higher robustness and does not requires thermal cycles faced with regular HPGe equipment. It also relies on a low vibration, low consumption electrical cooler so that no liquid nitrogen is being used. The detector is connected to a state-of-the-art digital spectroscopy suite embedded in an autonomous acquisition station monitoring the cryo-cooler and

Efficiency calibration of x-ray HPGe detectors for photons with energies above the Ge K binding energy

Energy Technology Data Exchange (ETDEWEB)

Maidana, Nora L., E-mail: nmaidana@if.usp.br [Instituto de Física, Universidade de São Paulo, Travessa R 187, Cidade Universitária, CEP:05508-900 São Paulo, SP (Brazil); Vanin, Vito R.; Jahnke, Viktor [Instituto de Física, Universidade de São Paulo, Travessa R 187, Cidade Universitária, CEP:05508-900 São Paulo, SP (Brazil); Fernández-Varea, José M. [Facultat de Física (ECM and ICC), Universitat de Barcelona, Diagonal 645, E-08028 Barcelona (Spain); Martins, Marcos N. [Instituto de Física, Universidade de São Paulo, Travessa R 187, Cidade Universitária, CEP:05508-900 São Paulo, SP (Brazil); Brualla, Lorenzo [NCTeam, Strahlenklinik, Universitätsklinikum Essen, Hufelandstraße 55, D-45122 Essen (Germany)

2013-11-21

We report on the efficiency calibration of a HPGe x-ray detector using radioactive sources and an analytical expression taken from the literature, in two different arrangements, with and without a broad-angle collimator. The frontal surface of the Ge crystal was scanned with pencil beams of photons. The Ge dead layer was found to be nonuniform, with central and intermediate regions that have thin (μm range) and thick (mm range) dead layers, respectively, surrounded by an insensitive ring. We discuss how this fact explains the observed efficiency curves and generalize the adopted model. We show that changes in the thickness of the Ge-crystal dead layer affect the efficiency of x-ray detectors, but the use of an appropriate broad-beam external collimator limiting the photon flux to the thin dead layer in the central region leads to the expected efficiency dependence with energy and renders the calibration simpler.

Alpha-event and surface characterisation in segmented true-coaxial HPGe detectors

Energy Technology Data Exchange (ETDEWEB)

Abt, I.; Garbini, L., E-mail: luciagarbini86@gmail.com.mpg.de; Gooch, C.; Irlbeck, S.; Liu, X.; Palermo, M.; Schulz, O.

2017-06-21

A detailed study of alpha interactions on the passivation layer on the end-plate of a true-coaxial high-purity germanium detector is presented. The observation of alpha events on such a surface indicates an unexpectedly thin so-called “effective dead layer” of less than 20 µm thickness. In addition, the influence of the metalisation close to the end-plate on the time evolution of the output pulses is discussed. The results indicate that alpha contamination can result in events which could be mistaken as signals for neutrinoless double beta decay and provide some guidance on how to prevent this.

Segmentation of the Outer Contact on P-Type Coaxial Germanium Detectors

Energy Technology Data Exchange (ETDEWEB)

Hull, Ethan L.; Pehl, Richard H.; Lathrop, James R.; Martin, Gregory N.; Mashburn, R. B.; Miley, Harry S.; Aalseth, Craig E.; Hossbach, Todd W.

2006-09-21

Germanium detector arrays are needed for low-level counting facilities. The practical applications of such user facilities include characterization of low-level radioactive samples. In addition, the same detector arrays can also perform important fundamental physics measurements including the search for rare events like neutrino-less double-beta decay. Coaxial germanium detectors having segmented outer contacts will provide the next level of sensitivity improvement in low background measurements. The segmented outer detector contact allows performance of advanced pulse shape analysis measurements that provide additional background reduction. Currently, n-type (reverse electrode) germanium coaxial detectors are used whenever a segmented coaxial detector is needed because the outer boron (electron barrier) contact is thin and can be segmented. Coaxial detectors fabricated from p-type germanium cost less, have better resolution, and are larger than n-type coaxial detectors. However, it is difficult to reliably segment p-type coaxial detectors because thick (~1 mm) lithium-diffused (hole barrier) contacts are the standard outside contact for p-type coaxial detectors. During this Phase 1 Small Business Innovation Research (SBIR) we have researched the possibility of using amorphous germanium contacts as a thin outer contact of p-type coaxial detectors that can be segmented. We have developed amorphous germanium contacts that provide a very high hole barrier on small planar detectors. These easily segmented amorphous germanium contacts have been demonstrated to withstand several thousand volts/cm electric fields with no measurable leakage current (<1 pA) from charge injection over the hole barrier. We have also demonstrated that the contact can be sputter deposited around and over the curved outside surface of a small p-type coaxial detector. The amorphous contact has shown good rectification properties on the outside of a small p-type coaxial detector. These encouraging

SmartPET: Applying HPGe and pulse shape analysis to small-animal PET

Energy Technology Data Exchange (ETDEWEB)

Cooper, R.J. [Department of Physics, University of Liverpool (United Kingdom)], E-mail: rjc@ns.ph.liv.ac.uk; Boston, A.J.; Boston, H.C.; Cresswell, J.R.; Grint, A.N.; Mather, A.R.; Nolan, P.J.; Scraggs, D.P.; Turk, G. [Department of Physics, University of Liverpool (United Kingdom); Hall, C.J.; Lazarus, I. [CCLRC Daresbury Laboratory, Warrington, Cheshire (United Kingdom); Berry, A.; Beveridge, T.; Gillam, J.; Lewis, R.A. [School of Physics and Materials Engineering, Monash University, Melbourne (Australia)

2007-08-21

The SmartPET project is the development of a prototype small-animal imaging system based on the use of Hyperpure Germanium (HPGe) detectors. The use of digital electronics and application of Pulse Shape Analysis (PSA) techniques provide fine spatial resolution, while the excellent intrinsic energy resolution of HPGe detectors makes the system ideal for multi-nuclide imaging. As a result, the SmartPET system has the potential to function as a dual modality imager, operating as a dual-head Positron Emission Tomography (PET) camera or in a Compton Camera configuration for Single Photon Emission Computed Tomography (SPECT) imaging. In this paper, we discuss how the use of simple PSA techniques greatly improves the position sensitivity of the detector yielding improved spatial resolution in reconstructed images. The PSA methods presented have been validated by comparison to data from high-precision scanning of the detectors. Results from this analysis are presented along with initial images from the SmartPET system, which demonstrates the impact of these techniques on PET images.

Improvement of the Ca determination accuracy with k (0)-INAA using an HPGe coaxial detector with extended energy range efficiency calibration

Czech Academy of Sciences Publication Activity Database

Kučera, Jan; Kubešová, Marie; Lebeda, Ondřej

2018-01-01

Roč. 315, č. 3 (2018), s. 671-675 ISSN 0236-5731. [7th International K0-Users Workshop. Montreal, 03.09.2017-08.09.2017] R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk LM2015056 Institutional support: RVO:61389005 Keywords : k(0)-INAA * Ca determination * HPGe detector * High-energy efficiency calibration * Co-56 activity standard Subject RIV: CB - Analytical Chemistry, Separation OBOR OECD: Analytical chemistry Impact factor: 1.282, year: 2016

Segmented focal plane detector for light and heavy ions

International Nuclear Information System (INIS)

Wolfs, F.L.H.; Bryan, D.C.; Kurz, K.L.; Herrick, D.M.; Perera, P.A.A.; White, C.A.

1992-01-01

A segmented focal plane detector for an Enge split-pole spectrograph has been developed for the study of breakup reactions at very low relative energies. It consists of a 61 cm long segmented position-sensitive parallel plate avalanche counter backed by a large Bragg curve detector. A segmented plastic scintillator is mounted behind the anode of the Bragg curve detector and is used for particle identification of low-ionizing particles. The dead space between the two sections of the focal plane detector is 2.5 mm. The intrinsic position resolution of the detector is 1 mm. The intrinsic energy resolution depends on the energy of the incident ion and can be as good as 0.55%. The nuclear charge and mass resolutions are 0.3 e and 0.3 u, respectively. (orig.)

Automatic modeling using PENELOPE of two HPGe detectors used for measurement of environmental samples by γ-spectrometry from a few sets of experimental efficiencies

Science.gov (United States)

Guerra, J. G.; Rubiano, J. G.; Winter, G.; Guerra, A. G.; Alonso, H.; Arnedo, M. A.; Tejera, A.; Mosqueda, F.; Martel, P.; Bolivar, J. P.

2018-02-01

The aim of this paper is to characterize two HPGe gamma-ray detectors used in two different laboratories for environmental radioactivity measurements, so as to perform efficiency calibrations by means of Monte Carlo Simulation. To achieve such an aim, methodologies developed in previous papers have been applied, based on the automatic optimization of the model of detector, so that the differences between computational and reference FEPEs are minimized. In this work, such reference FEPEs have been obtained experimentally from several measurements of the IAEA RGU-1 reference material for specific source-detector arrangements. The models of both detectors built through these methodologies have been validated by comparing with experimental results for several reference materials and different measurement geometries, showing deviations below 10% in most cases.

X-ray fluorescence analysis in environmental radiological surveillance using HPGe detectors

International Nuclear Information System (INIS)

Herrera Peraza, E.; Renteria Villalobos, M.; Montero Cabrera, M.E.; Munoz Romero, A.

2004-01-01

X-ray fluorescence (XRF) has been proven to be a valuable tool for determining trace quantities of heavy metals, such as uranium and lead, in different types of samples. The present paper demonstrates the applicability of XRF spectrometry to measure the concentrations of these heavy metals in samples from natural ore and soil. The values of uranium concentrations in rock from the Pena Blanca uranium ore, in Chihuahua, Mexico, were calculated for the purpose of precertifying the rock powders samples. The comparison with other techniques, such as inductively coupled plasma atomic emission spectrometry, atomic absorption spectrometry, alpha spectrometry and electron microscopy, was used to complete the precertification process, so that the sample powders may be used as secondary standards. The source-sample-detector geometry and the incident angle are the most important factors for obtaining low detection limits. The selected system uses a 57 Co source of about 0.1 mCi to excite the K X-rays from uranium and lead. X-rays were recorded on a CANBERRA HPGe coaxial detector. The comparative results for two incident angles (90 deg and 180 deg ) performed previously by other authors show that the best geometry is the backscattering geometry. In the present paper, using EGS4 code system with Monte Carlo simulation, it was possible to determine the location and distribution of background produced by the Compton edge in the optimized geometry. This procedure allowed to find the minimum detectable concentration of uranium and lead, which was experimentally calculated using standards. The possibility of performing in vivo measurements rapidly and easily, as well as the factors affecting accuracy and the minimum detectable concentration in several samples are also discussed

X-ray fluorescence analysis in environmental radiological surveillance using HPGe detectors

Energy Technology Data Exchange (ETDEWEB)

Herrera Peraza, E. [Department of Environmental Radiological Surveillance, Centro de Investigacion en Materiales Avanzados (CIMAV), P.O. Box 31109, Miguel de Cervantes no. 120, Complejo Industrial Chihuahua, Chihuahua (Mexico)]. E-mail: eduardo.herrera@cimav.edu.mx; Renteria Villalobos, M. [Department of Environmental Radiological Surveillance, Centro de Investigacion en Materiales Avanzados (CIMAV), P.O. Box 31109, Miguel de Cervantes no. 120, Complejo Industrial Chihuahua, Chihuahua (Mexico); Montero Cabrera, M.E. [Department of Environmental Radiological Surveillance, Centro de Investigacion en Materiales Avanzados (CIMAV), P.O. Box 31109, Miguel de Cervantes no. 120, Complejo Industrial Chihuahua, Chihuahua (Mexico); Munoz Romero, A. [Department of Environmental Radiological Surveillance, Centro de Investigacion en Materiales Avanzados (CIMAV), P.O. Box 31109, Miguel de Cervantes no. 120, Complejo Industrial Chihuahua, Chihuahua (Mexico)

2004-10-08

X-ray fluorescence (XRF) has been proven to be a valuable tool for determining trace quantities of heavy metals, such as uranium and lead, in different types of samples. The present paper demonstrates the applicability of XRF spectrometry to measure the concentrations of these heavy metals in samples from natural ore and soil. The values of uranium concentrations in rock from the Pena Blanca uranium ore, in Chihuahua, Mexico, were calculated for the purpose of precertifying the rock powders samples. The comparison with other techniques, such as inductively coupled plasma atomic emission spectrometry, atomic absorption spectrometry, alpha spectrometry and electron microscopy, was used to complete the precertification process, so that the sample powders may be used as secondary standards. The source-sample-detector geometry and the incident angle are the most important factors for obtaining low detection limits. The selected system uses a {sup 57}Co source of about 0.1 mCi to excite the K X-rays from uranium and lead. X-rays were recorded on a CANBERRA HPGe coaxial detector. The comparative results for two incident angles (90 deg and 180 deg ) performed previously by other authors show that the best geometry is the backscattering geometry. In the present paper, using EGS4 code system with Monte Carlo simulation, it was possible to determine the location and distribution of background produced by the Compton edge in the optimized geometry. This procedure allowed to find the minimum detectable concentration of uranium and lead, which was experimentally calculated using standards. The possibility of performing in vivo measurements rapidly and easily, as well as the factors affecting accuracy and the minimum detectable concentration in several samples are also discussed.

Detection limits of the NaI(Tl) shielded HPGe spectrometer

International Nuclear Information System (INIS)

Bikit, I.; Slivka, J.; Krmar, M.; Durcic, Z.; Zikic, N.; Conkic, Lj.; Veskovic, M.; Anicin, I.

1999-01-01

The results of a detailed study of the low-level performance of a NaI(Tl) shield added to an iron shielded HPGe spectrometer are presented. Both the 'slow' and the 'fast' anticoincidence gating modes were tested, the 'slow' mode being found better suited for general low-level spectroscopy applications. In long runs the stability of the system in this mode is satisfactory. The anticoincidence action of the NaI(T1) shield lowers the integral background of the iron shielded HPGe detector in the energy range from 30 keV to 2 MeV by a factor of 6.5, and suppresses the continuum above 150 keV by a factor larger than 10

Evaluation of real-time digital pulse shapers with various HPGe and silicon radiation detectors

International Nuclear Information System (INIS)

Menaa, N.; D'Agostino, P.; Zakrzewski, B.; Jordanov, V.T.

2011-01-01

Real-time digital pulse shaping techniques allow synthesis of pulse shapes that have been difficult to realize using the traditional analog methods. Using real-time digital shapers, triangular/trapezoidal filters can be synthesized in real time. These filters exhibit digital control on the rise time, fall time, and flat-top of the trapezoidal shape. Thus, the trapezoidal shape can be adjusted for optimum performance at different distributions of the series and parallel noise. The trapezoidal weighting function (WF) represents the optimum time-limited pulse shape when only parallel and series noises are present in the detector system. In the presence of 1/F noise, the optimum WF changes depending on the 1/F noise contribution. In this paper, we report on the results of the evaluation of new filter types for processing signals from CANBERRA high purity germanium (HPGe) and passivated, implanted, planar silicon (PIPS) detectors. The objective of the evaluation is to determine improvements in performance over the current trapezoidal (digital) filter. The evaluation is performed using a customized CANBERRA digital signal processing unit that is fitted with new FPGA designs and any required firmware modifications to support operation of the new filters. The evaluated filters include the Cusp, one-over-F (1/F), and pseudo-Gaussian filters. The results are compared with the CANBERRA trapezoidal shaper.

Precision measurement of radioactivity in gamma-rays spectrometry using two HPGe detectors (BEGe-6530 and GC0818-7600SL models comparison techniques: Application to the soil measurement

Directory of Open Access Journals (Sweden)

Guembou Shouop Cebastien Joel

2017-01-01

• Proved that the activity concentration determination in gamma spectrometry depended on the energy range emitted by a radionuclide. This study showed that the standard deviation measurement was less important to the result realized with BEGe-6530 HPGe model. Our findings were demonstrated that the results of the Broad Energy Germanium detector were more reliable.

Comparison of HPGe detector response data for low energy photons using MCNP, EGS, and its codes

International Nuclear Information System (INIS)

Kim, Soon Young; Kim, Jong Kyung

1995-01-01

In this study, the photopeak efficiency, K α and K β escape fractions of HPGe detector(100mm 2 X 10mm) are calculated and tabulated as a function of incident X-ray energies from 12 to 60keV in 2-keV increments. Compton, elastic, and penetration fractions are not tabulated from this work since they are negligible amounts in this energy range. The results calculated from this work are compared with earlier Monte Carlo results which had been carried out by Chin-Tu Chen et al.. From the comparison, it is found that the results calculated from each code show a large difference when the incident photon energy approaches to 12keV as compared with energy ranges from 50 to 60keV. In X-ray dosimetry and diagnostic radiology, it is essential to have accurate knowledge of X-ray spectra for studies of patient dose and image quality. Being X-ray spectra measured with a detection system, some distortions due to the incomplete absorption of primary photon or escape before interacting with the detector which have finite dimension can take place

Fold distributions at clover, crystal and segment levels for segmented clover detectors

International Nuclear Information System (INIS)

Kshetri, R; Bhattacharya, P

2014-01-01

Fold distributions at clover, crystal and segment levels have been extracted for an array of segmented clover detectors for various gamma energies. A simple analysis of the results based on a model independant approach has been presented. For the first time, the clover fold distribution of an array and associated array addback factor have been extracted. We have calculated the percentages of the number of crystals and segments that fire for a full energy peak event

Development of segmented germanium detectors for neutrinoless double beta decay experiments

International Nuclear Information System (INIS)

Liu, Jing

2009-01-01

The results from neutrino oscillation experiments indicate that at least two neutrinos have mass. However, the value of the masses and whether neutrinos and anti-neutrinos are identical, i.e., Majorana particles, remain unknown. Neutrinoless double beta decay experiments can help to improve our understanding in both cases and are the only method currently possible to tackle the second question. The GERmanium Detector Array (GERDA) experiment, which will search for the neutrinoless double beta decay of 76 Ge, is currently under construction in Hall A of the INFN Gran Sasso National Laboratory (LNGS), Italy. In order to achieve an extremely low background level, segmented germanium detectors are considered to be operated directly in liquid argon which serves simultaneously as cooling and shielding medium. Several test cryostats were built at the Max-Planck-Institut fuer Physik in Muenchen to operate segmented germanium detectors both in vacuum and submerged in cryogenic liquid. The performance and the background discrimination power of segmented germanium detectors were studied in detail. It was proven for the first time that segmented germanium detectors can be operated stably over long periods submerged in a cryogenic liquid. It was confirmed that the segmentation scheme employed does well in the identification of photon induced background and demonstrated for the first time that also neutron interactions can be identified. The C++ Monte Carlo framework, MaGe (Majorana-GERDA), is a joint development of the Majorana and GERDA collaborations. It is based on GEANT4, but tailored especially to simulate the response of ultra-low background detectors to ionizing radiation. The predictions of the simulation were veri ed to be accurate for a wide range of conditions. Some shortcomings were found and corrected. Pulse shape analysis is complementary to segmentation in identifying background events. Its efficiency can only be correctly determined using reliable pulse shape

Development of segmented germanium detectors for neutrinoless double beta decay experiments

Energy Technology Data Exchange (ETDEWEB)

Liu, Jing

2009-06-09

The results from neutrino oscillation experiments indicate that at least two neutrinos have mass. However, the value of the masses and whether neutrinos and anti-neutrinos are identical, i.e., Majorana particles, remain unknown. Neutrinoless double beta decay experiments can help to improve our understanding in both cases and are the only method currently possible to tackle the second question. The GERmanium Detector Array (GERDA) experiment, which will search for the neutrinoless double beta decay of {sup 76}Ge, is currently under construction in Hall A of the INFN Gran Sasso National Laboratory (LNGS), Italy. In order to achieve an extremely low background level, segmented germanium detectors are considered to be operated directly in liquid argon which serves simultaneously as cooling and shielding medium. Several test cryostats were built at the Max-Planck-Institut fuer Physik in Muenchen to operate segmented germanium detectors both in vacuum and submerged in cryogenic liquid. The performance and the background discrimination power of segmented germanium detectors were studied in detail. It was proven for the first time that segmented germanium detectors can be operated stably over long periods submerged in a cryogenic liquid. It was confirmed that the segmentation scheme employed does well in the identification of photon induced background and demonstrated for the first time that also neutron interactions can be identified. The C++ Monte Carlo framework, MaGe (Majorana-GERDA), is a joint development of the Majorana and GERDA collaborations. It is based on GEANT4, but tailored especially to simulate the response of ultra-low background detectors to ionizing radiation. The predictions of the simulation were veri ed to be accurate for a wide range of conditions. Some shortcomings were found and corrected. Pulse shape analysis is complementary to segmentation in identifying background events. Its efficiency can only be correctly determined using reliable pulse

Efficiency transfer using the GEANT4 code of CERN for HPGe gamma spectrometry.

Science.gov (United States)

Chagren, S; Tekaya, M Ben; Reguigui, N; Gharbi, F

2016-01-01

In this work we apply the GEANT4 code of CERN to calculate the peak efficiency in High Pure Germanium (HPGe) gamma spectrometry using three different procedures. The first is a direct calculation. The second corresponds to the usual case of efficiency transfer between two different configurations at constant emission energy assuming a reference point detection configuration and the third, a new procedure, consists on the transfer of the peak efficiency between two detection configurations emitting the gamma ray in different energies assuming a "virtual" reference point detection configuration. No pre-optimization of the detector geometrical characteristics was performed before the transfer to test the ability of the efficiency transfer to reduce the effect of the ignorance on their real magnitude on the quality of the transferred efficiency. The obtained and measured efficiencies were found in good agreement for the two investigated methods of efficiency transfer. The obtained agreement proves that Monte Carlo method and especially the GEANT4 code constitute an efficient tool to obtain accurate detection efficiency values. The second investigated efficiency transfer procedure is useful to calibrate the HPGe gamma detector for any emission energy value for a voluminous source using one point source detection efficiency emitting in a different energy as a reference efficiency. The calculations preformed in this work were applied to the measurement exercise of the EUROMET428 project. A measurement exercise where an evaluation of the full energy peak efficiencies in the energy range 60-2000 keV for a typical coaxial p-type HpGe detector and several types of source configuration: point sources located at various distances from the detector and a cylindrical box containing three matrices was performed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Development of twin Ge detector for high energy photon measurement and its performance

Energy Technology Data Exchange (ETDEWEB)

Shigetome, Yoshiaki; Harada, Hideo [Power Reactor and Nuclear Fuel Development Corp., Tokai, Ibaraki (Japan). Tokai Works

1998-03-01

Prototype twin HPGe detector composed of two large HPGe crystals was developed to obtain better detection efficiency ({epsilon}) and P/T ratio, which was required for high energy photon spectroscopy. In this work, the performances of the twin HPGe detector were evaluated by computer simulation employing EGS4 code. (author)

Direct and precise determination of environmental radionuclides in solid materials using a modified Marinelli beaker and a HPGe detector

International Nuclear Information System (INIS)

Seo, B.K.; Lee, D.W.; Lee, K.Y.; Yoon, Y.Y.

2001-01-01

A simple but precise detection method was studied for the determination of natural radionuclides using a conventional HPGe detector. A new aluminium beaker instead of a plastic Marinelli beaker was constructed and examined to reach radioactive equilibrium conditions between radon and its daughter elements without the escape of gaseous radon. Using this beaker fifteen natural radionuclides from three natural decay series could be determined by direct γ-ray measurement and sixteen radionuclides could be determined indirectly after radioactive equilibrium had been reached. Analytical results from ground water were compared with those from conventional α spectroscopy and the results agreed well within 12% difference. Nitrogen gas purge was used to replace the surrounding air of the detector to obtain a stable background and reducing the interference of radon daughter nuclides in the atmosphere. The use of nitrogen purging and the aluminium Marinelli beaker results in an approximately tenfold increase of sensitivity and a decrease of the detection limit of 226 Ra to about 0.74 Bq kg -1 in soil samples. (orig.)

Direct and precise determination of environmental radionuclides in solid materials using a modified Marinelli beaker and a HPGe detector.

Science.gov (United States)

Seo, B K; Lee, K Y; Yoon, Y Y; Lee, D W

2001-06-01

A simple but precise detection method was studied for the determination of natural radionuclides using a conventional HPGe detector. A new aluminium beaker instead of a plastic Marinelli beaker was constructed and examined to reach radioactive equilibrium conditions between radon and its daughter elements without the escape of gaseous radon. Using this beaker fifteen natural radionuclides from three natural decay series could be determined by direct gamma-ray measurement and sixteen radionuclides could be determined indirectly after radioactive equilibrium had been reached. Analytical results from ground water were compared with those from conventional alpha spectroscopy and the results agreed well within 12% difference. Nitrogen gas purge was used to replace the surrounding air of the detector to obtain a stable background and reducing the interference of radon daughter nuclides in the atmosphere. The use of nitrogen purging and the aluminium Marinelli beaker results in an approximately tenfold increase of sensitivity and a decrease of the detection limit of 226Ra to about 0.74 Bq kg(-1) in soil samples.

A Multi-Contact, Low Capacitance HPGe Detector for High Rate Gamma Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Cox, Christopher [XIA LLC, Hayward, CA (United States)

2014-12-04

The detection, identification and non-destructive assay of special nuclear materials and nuclear fission by-products are critically important activities in support of nuclear non-proliferation programs. Both national and international nuclear safeguard agencies recognize that current accounting methods for spent nuclear fuel are inadequate from a safeguards perspective. Radiation detection and analysis by gamma-ray spectroscopy is a key tool in this field, but no instrument exists that can deliver the required performance (energy resolution and detection sensitivity) in the presence of very high background count rates encountered in the nuclear safeguards arena. The work of this project addresses this critical need by developing a unique gamma-ray detector based on high purity germanium that has the previously unachievable property of operating in the 1 million counts-per-second range while achieving state-of-the-art energy resolution necessary to identify and analyze the isotopes of interest. The technical approach was to design and fabricate a germanium detector with multiple segmented electrodes coupled to multi-channel high rate spectroscopy electronics. Dividing the germanium detector’s signal electrode into smaller sections offers two advantages; firstly, the energy resolution of the detector is potentially improved, and secondly, the detector is able to operate at higher count rates. The design challenges included the following; determining the optimum electrode configuration to meet the stringent energy resolution and count rate requirements; determining the electronic noise (and therefore energy resolution) of the completed system after multiple signals are recombined; designing the germanium crystal housing and vacuum cryostat; and customizing electronics to perform the signal recombination function in real time. In this phase I work, commercial off-the-shelf electrostatic modeling software was used to develop the segmented germanium crystal geometry

Material screening with HPGe counting station for PandaX experiment

International Nuclear Information System (INIS)

Wang, X.; Chen, X.; Fu, C.; Ji, X.; Liu, X.; Xie, P.; Zhang, T.; Mao, Y.; Wang, S.; Wang, H.

2016-01-01

A gamma counting station based on high-purity germanium (HPGe) detector was set up for the material screening of the PandaX dark matter experiments in the China Jinping Underground Laboratory. Low background gamma rate of 2.6 counts/min within the energy range of 20 to 2700 keV is achieved due to the well-designed passive shield. The sentivities of the HPGe detetector reach mBq/kg level for isotopes like K, U, Th, and even better for Co and Cs, resulted from the low-background rate and the high relative detection efficiency of 175%. The structure and performance of the counting station are described in this article. Detailed counting results for the radioactivity in materials used by the PandaX dark-matter experiment are presented. The upgrading plan of the counting station is also discussed.

Performance of A Compact Multi-crystal High-purity Germanium Detector Array for Measuring Coincident Gamma-ray Emissions

Energy Technology Data Exchange (ETDEWEB)

Howard, Chris [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Daigle, Stephen [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Buckner, Matt [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Erikson, Luke E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Runkle, Robert C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Stave, Sean C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Champagne, Art [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Cooper, Andrew [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Downen, Lori [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Glasgow, Brian D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kelly, Keegan [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Sallaska, Anne [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States)

2015-02-18

The Multi-sensor Airborne Radiation Survey (MARS) detector is a 14-crystal array of high-purity germanium (HPGe) detectors housed in a single cryostat. The array was used to measure the astrophysical S-factor for the ¹⁴N(p,γ)¹⁵O* reaction for several transition energies at an effective center of mass energy of 163 keV. Owing to the segmented nature of the MARS detector, the effect of gamma-ray summing was greatly reduced in comparison to past experiments which utilized large, single-crystal detectors. The new S-factor values agree within the uncertainties with the past measurements. Details of the analysis and detector performance will be presented.

Analysis of fold distributions of segmented clover detectors

International Nuclear Information System (INIS)

Bhattacharya, Pintu; Kshetri, Ritesh

2015-01-01

We have studied the effect of segmentation on the full energy energy deposition of a gamma-ray through the studies on fold distribution. The response of seven segmented TIGRESS detectors up to an energy of 8 MeV has been studied by utilizing standard sources of 152 Eu, 56,60 Co and a radioactive 11 Be beam with an energy of 16.5 MeV. Experiment was performed at the ISAC-II facility at TRIUMF, using a thick gold target. The β¯ decay of 11 Be (τ 1/2 = 13.81(8) sec) produces high energy gamma-rays up to 7974 keV. A 1 mm thick annular double-sided silicon detector of the BAMBINO detector, was mounted 19.4 mm downstream of the target position and used for detection of the electrons in coincidence with the gamma-rays from the seven TIGRESS detectors. The master trigger allowed data to be collected either in Ge singles mode or with a Ge-Si coincidence condition. Standard sources of 152 Eu and 56,60 Co were also used to obtain low energy data

Efficiency transfer using the GEANT4 code of CERN for HPGe gamma spectrometry

International Nuclear Information System (INIS)

Chagren, S.; Tekaya, M.Ben; Reguigui, N.; Gharbi, F.

2016-01-01

In this work we apply the GEANT4 code of CERN to calculate the peak efficiency in High Pure Germanium (HPGe) gamma spectrometry using three different procedures. The first is a direct calculation. The second corresponds to the usual case of efficiency transfer between two different configurations at constant emission energy assuming a reference point detection configuration and the third, a new procedure, consists on the transfer of the peak efficiency between two detection configurations emitting the gamma ray in different energies assuming a “virtual” reference point detection configuration. No pre-optimization of the detector geometrical characteristics was performed before the transfer to test the ability of the efficiency transfer to reduce the effect of the ignorance on their real magnitude on the quality of the transferred efficiency. The obtained and measured efficiencies were found in good agreement for the two investigated methods of efficiency transfer. The obtained agreement proves that Monte Carlo method and especially the GEANT4 code constitute an efficient tool to obtain accurate detection efficiency values. The second investigated efficiency transfer procedure is useful to calibrate the HPGe gamma detector for any emission energy value for a voluminous source using one point source detection efficiency emitting in a different energy as a reference efficiency. The calculations preformed in this work were applied to the measurement exercise of the EUROMET428 project. A measurement exercise where an evaluation of the full energy peak efficiencies in the energy range 60–2000 keV for a typical coaxial p-type HpGe detector and several types of source configuration: point sources located at various distances from the detector and a cylindrical box containing three matrices was performed. - Highlights: • The GEANT4 code of CERN has been used to transfer the peak efficiency from point to points and voluminous detection configurations in HPGe gamma

Design of A HPGe-Plastic Scintillator Compton Suppression Spectrometer for Neutron Activation Analysis and Radio environmental Studies

International Nuclear Information System (INIS)

Sharshar, T.; Badran, H.; Elnimr, T.

1998-01-01

The design of a compton suppression spectrometer consisting of a 10% p-type HPGe detector and an annular anti-Compton shield made of N E-102 A plastic scintillator is described. The height of the guard plastic- scintillation detector was optimized experimentally using a NaI(Ti) ring, consisting of five NaI(Ti) detectors. The annular guard detector is divided to four optically isolated quarters to enhance the light collection. Each quarter of the guard detector was tested and satisfying results are obtained

Sub-nanosecond time-of-flight for segmented silicon detectors

International Nuclear Information System (INIS)

Souza, R.T. de; Alexander, A.; Brown, K.; Floyd, B.; Gosser, Z.Q.; Hudan, S.; Poehlman, J.; Rudolph, M.J.

2011-01-01

Development of a multichannel time-of-flight system for readout of a segmented, ion-passivated, ion-implanted silicon detector is described. This system provides sub-nanosecond resolution (δt∼370ps) even for low energy α particles which deposit E≤7.687MeV in the detector.

Modeling an array of encapsulated germanium detectors

International Nuclear Information System (INIS)

Kshetri, R

2012-01-01

A probability model has been presented for understanding the operation of an array of encapsulated germanium detectors generally known as composite detector. The addback mode of operation of a composite detector has been described considering the absorption and scattering of γ-rays. Considering up to triple detector hit events, we have obtained expressions for peak-to-total and peak-to-background ratios of the cluster detector, which consists of seven hexagonal closely packed encapsulated HPGe detectors. Results have been obtained for the miniball detectors comprising of three and four seven hexagonal closely packed encapsulated HPGe detectors. The formalism has been extended to the SPI spectrometer which is a telescope of the INTEGRAL satellite and consists of nineteen hexagonal closely packed encapsulated HPGe detectors. This spectrometer comprises of twelve detector modules surrounding the cluster detector. For comparison, we have considered a spectrometer comprising of nine detector modules surrounding the three detector configuration of miniball detector. In the present formalism, the operation of these sophisticated detectors could be described in terms of six probability amplitudes only. Using experimental data on relative efficiency and fold distribution of cluster detector as input, the fold distribution and the peak-to-total, peak-to-background ratios have been calculated for the SPI spectrometer and other composite detectors at 1332 keV. Remarkable agreement between experimental data and results from the present formalism has been observed for the SPI spectrometer.

Orthogonal strip HPGe planar SmartPET detectors in Compton configuration

International Nuclear Information System (INIS)

Boston, H.C.; Gillam, J.; Boston, A.J.; Cooper, R.J.; Cresswell, J.; Grint, A.N.; Mather, A.R.; Nolan, P.J.; Scraggs, D.P.; Turk, G.; Hall, C.J.; Lazarus, I.; Berry, A.; Beveridge, T.; Lewis, R.

2007-01-01

The evolution of Germanium detector technology over the last decade has lead to the possibility that they can be employed in medical and security imaging. The potential of excellent energy resolution coupled with good position information that Germanium affords removes the necessity for mechanical collimators that would be required in a conventional gamma camera system. By removing this constraint, the overall dose to the patient can be reduced or the throughput of the system can be increased. An additional benefit of excellent energy resolution is that tight gates can be placed on energies from either a multi-lined gamma source or from multi-nuclide sources increasing the number of sources that can be used in medical imaging. In terms of security imaging, segmented Germanium gives directionality and excellent spectroscopic information

Orthogonal strip HPGe planar SmartPET detectors in Compton configuration

Energy Technology Data Exchange (ETDEWEB)

Boston, H.C. [Department of Physics, University of Liverpool, Oliver Lodge Laboratory, Liverpool, L69 7ZE (United Kingdom)], E-mail: H.C.Boston@liverpool.ac.uk; Gillam, J. [School of Physics and Materials Engineering, Monash University, Melbourne (Australia); Boston, A.J.; Cooper, R.J.; Cresswell, J.; Grint, A.N.; Mather, A.R.; Nolan, P.J.; Scraggs, D.P.; Turk, G. [Department of Physics, University of Liverpool, Oliver Lodge Laboratory, Liverpool, L69 7ZE (United Kingdom); Hall, C.J.; Lazarus, I. [STFC Daresbury Laboratory, Warrington, WA4 4AD (United Kingdom); Berry, A.; Beveridge, T.; Lewis, R. [School of Physics and Materials Engineering, Monash University, Melbourne (Australia)

2007-10-01

The evolution of Germanium detector technology over the last decade has lead to the possibility that they can be employed in medical and security imaging. The potential of excellent energy resolution coupled with good position information that Germanium affords removes the necessity for mechanical collimators that would be required in a conventional gamma camera system. By removing this constraint, the overall dose to the patient can be reduced or the throughput of the system can be increased. An additional benefit of excellent energy resolution is that tight gates can be placed on energies from either a multi-lined gamma source or from multi-nuclide sources increasing the number of sources that can be used in medical imaging. In terms of security imaging, segmented Germanium gives directionality and excellent spectroscopic information.

Applying a low energy HPGe detector gamma ray spectrometric technique for the evaluation of Pu/Am ratio in biological samples.

Science.gov (United States)

Singh, I S; Mishra, Lokpati; Yadav, J R; Nadar, M Y; Rao, D D; Pradeepkumar, K S

2015-10-01

The estimation of Pu/(241)Am ratio in the biological samples is an important input for the assessment of internal dose received by the workers. The radiochemical separation of Pu isotopes and (241)Am in a sample followed by alpha spectrometry is a widely used technique for the determination of Pu/(241)Am ratio. However, this method is time consuming and many times quick estimation is required. In this work, Pu/(241)Am ratio in the biological sample was estimated with HPGe detector based measurements using gamma/X-rays emitted by these radionuclides. These results were compared with those obtained from alpha spectroscopy of sample after radiochemical analysis and found to be in good agreement. Copyright © 2015 Elsevier Ltd. All rights reserved.

Germanium detectors for nuclear spectroscopy: Current research and development activity at LNL

Energy Technology Data Exchange (ETDEWEB)

Napoli, D. R., E-mail: daniel.r.napoli@lnl.infn.it [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Viale dell’Università 2, 35020 Legnaro, Padova (Italy); Maggioni, G., E-mail: maggioni@lnl.infn.it; Carturan, S.; Gelain, M. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Viale dell’Università 2, 35020 Legnaro, Padova (Italy); Department of Physics and Astronomy “G. Galilei”, University of Padova, Via Marzolo 8, 35121 Padova (Italy); Eberth, J. [Institut für Kernphysik, Universität zu Köln, Zülpicher Straße 77, D-50937 Köln (Germany); Grimaldi, M. G.; Tatí, S. [Department of Physics and Astronomy, University of Catania (Italy); Riccetto, S. [University of Camerino and INFN of Perugia (Italy); Mea, G. Della [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Viale dell’Università 2, 35020 Legnaro, Padova (Italy); University of Trento (Italy)

2016-07-07

High-purity Germanium (HPGe) detectors have reached an unprecedented level of sophistication and are still the best solution for high-resolution gamma spectroscopy. In the present work, we will show the results of the characterization of new surface treatments for the production of these detectors, studied in the framework of our multidisciplinary research program in HPGe detector technologies.

Resolution, efficiency and stability of HPGe detector operating in a magnetic field at various gamma-ray energies

International Nuclear Information System (INIS)

Szymanska, K.; Achenbach, P.; Agnello, M.; Botta, E.; Bracco, A.; Bressani, T.; Camera, F.; Cederwall, B.; Feliciello, A.; Ferro, F.; Gerl, J.; Iazzi, F.; Kavatsyuk, M.; Kojouharov, I.; Pochodzalla, J.; Raciti, G.; Saito, T.R.; Sanchez Lorente, A.; Tegner, P.-E.; Wieland, O.

2008-01-01

The use of High Purity Germanium detectors (HPGe) has been planned in some future experiments of hadronic physics. The crystals will be located close to large spectrometers where the magnetic fringing field will not be negligible and their performances might change. Moreover high precision is required in these experiments. The contribution of magnetic field presence and long term measurements is unique. In this paper the results of systematic measurements of the resolution, stability and efficiency of a crystal operating inside a magnetic field of 0.8 T, using radioactive sources in the energy range from 0.08 to 1.33 MeV, are reported. The measurements have been repeated during several months in order to test if any permanent damage occurred. The resolution at 1.117 and 1.332 MeV gamma-rays from a 60 Co source has been measured at different magnetic fields in the range of 0-0.8 T and the results are compared with the previous data

The position response of a large-volume segmented germanium detector

International Nuclear Information System (INIS)

Descovich, M.; Nolan, P.J.; Boston, A.J.; Dobson, J.; Gros, S.; Cresswell, J.R.; Simpson, J.; Lazarus, I.; Regan, P.H.; Valiente-Dobon, J.J.; Sellin, P.; Pearson, C.J.

2005-01-01

The position response of a large-volume segmented coaxial germanium detector is reported. The detector has 24-fold segmentation on its outer contact. The output from each contact was sampled with fast digital signal processing electronics in order to determine the position of the γ-ray interaction from the signal pulse shape. The interaction position was reconstructed in a polar coordinate system by combining the radial information, contained in the rise-time of the pulse leading edge, with the azimuthal information, obtained from the magnitude of the transient charge signals induced on the neighbouring segments. With this method, a position resolution of 3-7mm is achieved in both the radial and the azimuthal directions

The position response of a large-volume segmented germanium detector

Energy Technology Data Exchange (ETDEWEB)

Descovich, M. [Oliver Lodge Laboratory, Physics Department, University of Liverpool, Liverpool L69 7ZE (United Kingdom)]. E-mail: mdescovich@lbl.gov; Nolan, P.J. [Oliver Lodge Laboratory, Physics Department, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Boston, A.J. [Oliver Lodge Laboratory, Physics Department, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Dobson, J. [Oliver Lodge Laboratory, Physics Department, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Gros, S. [Oliver Lodge Laboratory, Physics Department, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Cresswell, J.R. [Oliver Lodge Laboratory, Physics Department, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Simpson, J. [CCLRC Daresbury Laboratory, Daresbury, Warrington, Cheshire WA4 4AD (United Kingdom); Lazarus, I. [CCLRC Daresbury Laboratory, Daresbury, Warrington, Cheshire WA4 4AD (United Kingdom); Regan, P.H. [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Valiente-Dobon, J.J. [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Sellin, P. [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Pearson, C.J. [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom)

2005-11-21

The position response of a large-volume segmented coaxial germanium detector is reported. The detector has 24-fold segmentation on its outer contact. The output from each contact was sampled with fast digital signal processing electronics in order to determine the position of the {gamma}-ray interaction from the signal pulse shape. The interaction position was reconstructed in a polar coordinate system by combining the radial information, contained in the rise-time of the pulse leading edge, with the azimuthal information, obtained from the magnitude of the transient charge signals induced on the neighbouring segments. With this method, a position resolution of 3-7mm is achieved in both the radial and the azimuthal directions.

Techniques to distinguish between electron and photon induced events using segmented germanium detectors

International Nuclear Information System (INIS)

Kroeninger, K.

2007-01-01

Two techniques to distinguish between electron and photon induced events in germanium detectors were studied: (1) anti-coincidence requirements between the segments of segmented germanium detectors and (2) the analysis of the time structure of the detector response. An 18-fold segmented germanium prototype detector for the GERDA neutrinoless double beta-decay experiment was characterized. The rejection of photon induced events was measured for the strongest lines in 60 Co, 152 Eu and 228 Th. An accompanying Monte Carlo simulation was performed and the results were compared to data. An overall agreement with deviations of the order of 5-10% was obtained. The expected background index of the GERDA experiment was estimated. The sensitivity of the GERDA experiment was determined. Special statistical tools were developed to correctly treat the small number of events expected. The GERDA experiment uses a cryogenic liquid as the operational medium for the germanium detectors. It was shown that germanium detectors can be reliably operated through several cooling cycles. (orig.)

Techniques to distinguish between electron and photon induced events using segmented germanium detectors

Energy Technology Data Exchange (ETDEWEB)

Kroeninger, K.

2007-06-05

Two techniques to distinguish between electron and photon induced events in germanium detectors were studied: (1) anti-coincidence requirements between the segments of segmented germanium detectors and (2) the analysis of the time structure of the detector response. An 18-fold segmented germanium prototype detector for the GERDA neutrinoless double beta-decay experiment was characterized. The rejection of photon induced events was measured for the strongest lines in {sup 60}Co, {sup 152}Eu and {sup 228}Th. An accompanying Monte Carlo simulation was performed and the results were compared to data. An overall agreement with deviations of the order of 5-10% was obtained. The expected background index of the GERDA experiment was estimated. The sensitivity of the GERDA experiment was determined. Special statistical tools were developed to correctly treat the small number of events expected. The GERDA experiment uses a cryogenic liquid as the operational medium for the germanium detectors. It was shown that germanium detectors can be reliably operated through several cooling cycles. (orig.)

High-resolution imaging gamma-ray spectroscopy with externally segmented germanium detectors

Science.gov (United States)

Callas, J. L.; Mahoney, W. A.; Varnell, L. S.; Wheaton, W. A.

1993-01-01

Externally segmented germanium detectors promise a breakthrough in gamma-ray imaging capabilities while retaining the superb energy resolution of germanium spectrometers. An angular resolution of 0.2 deg becomes practical by combining position-sensitive germanium detectors having a segment thickness of a few millimeters with a one-dimensional coded aperture located about a meter from the detectors. Correspondingly higher angular resolutions are possible with larger separations between the detectors and the coded aperture. Two-dimensional images can be obtained by rotating the instrument. Although the basic concept is similar to optical or X-ray coded-aperture imaging techniques, several complicating effects arise because of the penetrating nature of gamma rays. The complications include partial transmission through the coded aperture elements, Compton scattering in the germanium detectors, and high background count rates. Extensive electron-photon Monte Carlo modeling of a realistic detector/coded-aperture/collimator system has been performed. Results show that these complicating effects can be characterized and accounted for with no significant loss in instrument sensitivity.

Automation of the Characterization of High Purity Germanium Detectors

Science.gov (United States)

Dugger, Charles ``Chip''

2014-09-01

Neutrinoless double beta decay is a rare hypothesized process that may yield valuable insight into the fundamental properties of the neutrino. Currently there are several experiments trying to observe this process, including the Majorana DEMONSTRAOR experiment, which uses high purity germanium (HPGe) detectors to generate and search for these events. Because the event happens internally, it is essential to have the lowest background possible. This is done through passive detector shielding, as well as event discrimination techniques that distinguish between multi-site events characteristic of gamma-radiation, and single-site events characteristic of neutrinoless double beta decay. Before fielding such an experiment, the radiation response of the detectors must be characterized. A robotic arm is being tested for future calibration of HPGe detectors. The arm will hold a source at locations relative to the crystal while data is acquired. Several radioactive sources of varying energy levels will be used to determine the characteristics of the crystal. In this poster, I will present our work with the robot, as well as the characterization of data we took with an underground HPGe detector at the WIPP facility in Carlsbad, NM (2013). Neutrinoless double beta decay is a rare hypothesized process that may yield valuable insight into the fundamental properties of the neutrino. Currently there are several experiments trying to observe this process, including the Majorana DEMONSTRAOR experiment, which uses high purity germanium (HPGe) detectors to generate and search for these events. Because the event happens internally, it is essential to have the lowest background possible. This is done through passive detector shielding, as well as event discrimination techniques that distinguish between multi-site events characteristic of gamma-radiation, and single-site events characteristic of neutrinoless double beta decay. Before fielding such an experiment, the radiation response of

High-Resolution Gamma-Ray Imaging Measurements Using Externally Segmented Germanium Detectors

Science.gov (United States)

Callas, J.; Mahoney, W.; Skelton, R.; Varnell, L.; Wheaton, W.

1994-01-01

Fully two-dimensional gamma-ray imaging with simultaneous high-resolution spectroscopy has been demonstrated using an externally segmented germanium sensor. The system employs a single high-purity coaxial detector with its outer electrode segmented into 5 distinct charge collection regions and a lead coded aperture with a uniformly redundant array (URA) pattern. A series of one-dimensional responses was collected around 511 keV while the system was rotated in steps through 180 degrees. A non-negative, linear least-squares algorithm was then employed to reconstruct a 2-dimensional image. Corrections for multiple scattering in the detector, and the finite distance of source and detector are made in the reconstruction process.

A segmented, enriched N-type germanium detector for neutrinoless double beta-decay experiments

Science.gov (United States)

Leviner, L. E.; Aalseth, C. E.; Ahmed, M. W.; Avignone, F. T.; Back, H. O.; Barabash, A. S.; Boswell, M.; De Braeckeleer, L.; Brudanin, V. B.; Chan, Y.-D.; Egorov, V. G.; Elliott, S. R.; Gehman, V. M.; Hossbach, T. W.; Kephart, J. D.; Kidd, M. F.; Konovalov, S. I.; Lesko, K. T.; Li, Jingyi; Mei, D.-M.; Mikhailov, S.; Miley, H.; Radford, D. C.; Reeves, J.; Sandukovsky, V. G.; Umatov, V. I.; Underwood, T. A.; Tornow, W.; Wu, Y. K.; Young, A. R.

2014-01-01

We present data characterizing the performance of the first segmented, N-type Ge detector, isotopically enriched to 85% 76Ge. This detector, based on the Ortec PT6×2 design and referred to as SEGA (Segmented, Enriched Germanium Assembly), was developed as a possible prototype for neutrinoless double beta-decay measurements by the MAJORANA collaboration. We present some of the general characteristics (including bias potential, efficiency, leakage current, and integral cross-talk) for this detector in its temporary cryostat. We also present an analysis of the resolution of the detector, and demonstrate that for all but two segments there is at least one channel that reaches the MAJORANA resolution goal below 4 keV FWHM at 2039 keV, and all channels are below 4.5 keV FWHM.

Using the IEC Standard to Describe Low-Background Detectors-What Can You Expect?

International Nuclear Information System (INIS)

Ronald M. Keyser; Sanford Wagner

1998-01-01

The new International Electrotechnical Commission (IEC) standard for describing the background makes the specification of the background in a high-purity germanium (HPGe) detector simple, unambiguous, and related to how the detector will be used. Users and manufacturers will finally be speaking the same language on this subject. Because this standard extends the specification of the performance of an HPGe detector, there is little history available for comparison and thus no means of determining a ''good'' value. To develop a history, the background spectrum for 500 low-background HPGe ORTEC detectors were all counted in similar low-background shields. These detectors were in a variety of mechanical cryostat and endcap configurations. The continuum background is a function of energy and detector size/configuration. The peak area for the peak energies listed in the standard is a function of detector size and configuration. The results thus give practical guidance for obtaining the most appropriate low-background detector for a specific measurement problem

Development of an underground HPGe array facility for ultra low radioactivity measurements

Energy Technology Data Exchange (ETDEWEB)

Sala, E.; Kang, W. G.; Kim, Y. D.; Lee, M. H.; Leonard, D. S. [Center for Underground Physics - Institute for Basic Science, Daejeon (Korea, Republic of); Hahn, I. S.; Kim, G. W.; Park, S. Y. [Ewha Womans University, Physics Department, Seoul (Korea, Republic of)

2015-08-17

Low Level Counting techniques using low background facilities are continuously under development to increase the possible sensitivity needed for rare physics events experiments. The CUP (Center for Underground Physics) group of IBS is developing, in collaboration with Canberra, a ultra low background instrument composed of two arrays facing each other with 7 HPGe detectors each. The low radioactive background of each detector has been evaluated and improved by the material selection of the detector components. Samples of all the building materials have been provided by the manufacturer and the contaminations had been measured using an optimized low background 100% HPGe with a dedicated shielding. The evaluation of the intrinsic background has been performed using MonteCarlo simulations and considering the contribution of each material with the measured contamination. To further reduce the background, the instrument will be placed in the new underground laboratory at YangYang exploiting the 700m mountain coverage and radon-free air supplying system. The array has been designed to perform various Ultra Low background measurements; the sensitivity we are expecting will allow not only low level measurements of Ra and Th contaminations in Copper or other usually pure materials, but also the search for rare decays. In particular some possible candidates and configurations to detect the 0νECEC (for example {sup 106}Cd and {sup 156}Dy) and rare β decays ({sup 96}Zr, {sup 180m}Ta , etc ) are under study.

Wilcoxon signed-rank-based technique for the pulse-shape analysis of HPGe detectors

Science.gov (United States)

Martín, S.; Quintana, B.; Barrientos, D.

2016-07-01

The characterization of the electric response of segmented-contact high-purity germanium detectors requires scanning systems capable of accurately associating each pulse with the position of the interaction that generated it. This process requires an algorithm sensitive to changes above the electronic noise in the pulse shapes produced at different positions, depending on the resolution of the Ge crystal. In this work, a pulse-shape comparison technique based on the Wilcoxon signed-rank test has been developed. It provides a method to distinguish pulses coming from different interaction points in the germanium crystal. Therefore, this technique is a necessary step for building a reliable pulse-shape database that can be used later for the determination of the position of interaction for γ-ray tracking spectrometry devices such as AGATA, GRETA or GERDA. The method was validated by comparison with a χ2 test using simulated and experimental pulses corresponding to a Broad Energy germanium detector (BEGe).

Wilcoxon signed-rank-based technique for the pulse-shape analysis of HPGe detectors

Energy Technology Data Exchange (ETDEWEB)

Martín, S., E-mail: sergiomr@usal.es; Quintana, B.; Barrientos, D.

2016-07-01

The characterization of the electric response of segmented-contact high-purity germanium detectors requires scanning systems capable of accurately associating each pulse with the position of the interaction that generated it. This process requires an algorithm sensitive to changes above the electronic noise in the pulse shapes produced at different positions, depending on the resolution of the Ge crystal. In this work, a pulse-shape comparison technique based on the Wilcoxon signed-rank test has been developed. It provides a method to distinguish pulses coming from different interaction points in the germanium crystal. Therefore, this technique is a necessary step for building a reliable pulse-shape database that can be used later for the determination of the position of interaction for γ-ray tracking spectrometry devices such as AGATA, GRETA or GERDA. The method was validated by comparison with a χ{sup 2} test using simulated and experimental pulses corresponding to a Broad Energy germanium detector (BEGe).

Wilcoxon signed-rank-based technique for the pulse-shape analysis of HPGe detectors

International Nuclear Information System (INIS)

Martín, S.; Quintana, B.; Barrientos, D.

2016-01-01

The characterization of the electric response of segmented-contact high-purity germanium detectors requires scanning systems capable of accurately associating each pulse with the position of the interaction that generated it. This process requires an algorithm sensitive to changes above the electronic noise in the pulse shapes produced at different positions, depending on the resolution of the Ge crystal. In this work, a pulse-shape comparison technique based on the Wilcoxon signed-rank test has been developed. It provides a method to distinguish pulses coming from different interaction points in the germanium crystal. Therefore, this technique is a necessary step for building a reliable pulse-shape database that can be used later for the determination of the position of interaction for γ-ray tracking spectrometry devices such as AGATA, GRETA or GERDA. The method was validated by comparison with a χ"2 test using simulated and experimental pulses corresponding to a Broad Energy germanium detector (BEGe).

Performance of a 6x6 segmented germanium detector for {gamma}-ray tracking

Energy Technology Data Exchange (ETDEWEB)

Valiente-Dobon, J.J. E-mail: j.valiente-dobon@surrey.ac.uk; Pearson, C.J.; Regan, P.H.; Sellin, P.J.; Gelletly, W.; Morton, E.; Boston, A.; Descovich, M.; Nolan, P.J.; Simpson, J.; Lazarus, I.; Warner, D

2003-06-01

A 36 fold segmented germanium coaxial detector has been supplied by EURISYS MESURES. The outer contact is segmented both radially and longitudinally. The signals from the fast preamplifiers have been digitised by 12 bit, 40 MHz ADCs. In this article we report preliminary results obtained using this detector and their relevance for future germanium {gamma}-ray tracking arrays.

Testing the Ge Detectors for the MAJORANA DEMONSTRATOR

Science.gov (United States)

Xu, W.; Abgrall, N.; Aguayo, E.; Avignone, F. T.; Barabash, A. S.; Bertrand, F. E.; Boswell, M.; Brudanin, V.; Busch, M.; Byram, D.; Caldwell, A. S.; Chan, Y.-D.; Christofferson, C. D.; Combs, D. C.; Cuesta, C.; Detwiler, J. A.; Doe, P. J.; Efremenko, Yu.; Egorov, V.; Ejiri, H.; Elliott, S. R.; Fast, J. E.; Finnerty, P.; Fraenkle, F. M.; Galindo-Uribarri, A.; Giovanetti, G. K.; Goett, J.; Green, M. P.; Gruszko, J.; Guiseppe, V. E.; Gusev, K.; Hallin, A. L.; Hazama, R.; Hegai, A.; Henning, R.; Hoppe, E. W.; Howard, S.; Howe, M. A.; Keeter, K. J.; Kidd, M. F.; Kochetov, O.; Konovalov, S. I.; Kouzes, R. T.; LaFerriere, B. D.; Leon, J.; Leviner, L. E.; Loach, J. C.; MacMullin, J.; MacMullin, S.; Martin, R. D.; Meijer, S.; Mertens, S.; Nomachi, M.; Orrell, J. L.; O'Shaughnessy, C.; Overman, N. R.; Phillips, D. G.; Poon, A. W. P.; Pushkin, K.; Radford, D. C.; Rager, J.; Rielage, K.; Robertson, R. G. H.; Romero-Romero, E.; Ronquest, M. C.; Schubert, A. G.; Shanks, B.; Shima, T.; Shirchenko, M.; Snavely, K. J.; Snyder, N.; Suriano, A. M.; Thompson, J.; Timkin, V.; Tornow, W.; Trimble, J. E.; Varner, R. L.; Vasilyev, S.; Vetter, K.; Vorren, K.; White, B. R.; Wilkerson, J. F.; Wiseman, C.; Yakushev, E.; Young, A. R.; Yu, C.-H.; Yumatov, V.

High purity germanium (HPGe) crystals will be used for the MAJORANA DEMONSTRATOR, where they serve as both the source and the detector for neutrinoless double beta decay. It is crucial for the experiment to understand the performance of the HPGe crystals. A variety of crystal properties are being investigated, including basic properties such as energy resolution, efficiency, uniformity, capacitance, leakage current and crystal axis orientation, as well as more sophisticated properties, e.g. pulse shapes and dead layer and transition layer distributions. In this talk, we will present our measurements that characterize the HPGe crystals. We will also discuss the our simulation package for the detector characterization setup, and show that additional information can be extracted from data-simulation comparisons.

Optimization of a partially segmented block detector for MR-compatible small animal PET

International Nuclear Information System (INIS)

Hwang, Ji Yeon; Chung, Yong Hyun; Baek, Cheol-Ha; An, Su Jung; Kim, Hyun-Il; Kim, Kwang Hyun

2011-01-01

In recent years, there has been an increasing interest in the magnetic resonance (MR)-compatible positron emission tomography (PET) scanners for both clinical and preclinical practice. The aim of this study was to design a novel PET detector module using a segmented block crystal readout with an array of multi-pixel photon counters (MPPCs). A 16.5x16.5x10.0 mm 3 LSO block was segmented into an 11x11 array, and reflective material was used to fill in the cuts to optically isolate the elements. The block was attached to a 4x4 MPPC array (Hamamatsu S11064) of 3.0x3.0 mm 2 detectors to give a total effective area of 144 mm 2 . To visualize all the individual detector elements in this 11x11 detector module, the depth of the cuts was optimized by DETECT2000 simulations. The depth of the cuts determines the spread of scintillation light onto the MPPC array. The accuracy of positioning was evaluated by varying the depth of the cuts from 0.0 to 10.0 mm in steps of 0.5 mm. A spatial resolution of 1.5 mm was achieved using the optimized partially segmented block detector. The simulation results of this study can be used effectively as a guide for parameter optimization for the development of a partially segmented block detector for high-resolution MR-compatible PET scanners.

A normalisation for the four - detector system for gamma - gamma angular correlation studies

International Nuclear Information System (INIS)

Kiang, G.C.; Chen, C.H.; Niu, W.F.

1994-01-01

A normalisation method for the multiple - HPGe - detector system is described. The system consists of four coaxial HPGe detectors with a CAMAC event - by - event data acquisition system, enabling to measure six gamma -gamma coincidences of angles simultaneously. An application for gamma - gamma correlation studies of Kr 82 is presented and discussed. 3 figs., 6 refs. (author)

Assessment of ambient-temperature, high-resolution detectors for nuclear safeguards applications

International Nuclear Information System (INIS)

Ruhter, W.D.; McQuaid, J.H.; Lavietes, A.

1993-01-01

High-resolution, gamma- and x-ray spectrometry are used routinely in nuclear safeguards verification measurements of plutonium and uranium in the field. These measurements are now performed with high-purity germanium (HPGe) detectors that require cooling liquid-nitrogen temperatures, thus limiting their utility in field and unattended safeguards measurement applications. Ambient temperature semiconductor detectors may complement HPGe detectors for certain safeguards verification applications. Their potential will be determined by criteria such as their performance, commercial availability, stage of development, and costs. We have conducted as assessment of ambient temperature detectors for safeguards measurement applications with these criteria in mind

Charge Spreading and Position Sensitivity in a Segmented Planar Germanium Detector (Preprint)

National Research Council Canada - National Science Library

Kroeger, R. A; Gehrels, N; Johnson, W. N; Kurfess, J. D; Phlips, B. P; Tueller, J

1998-01-01

The size of the charge cloud collected in a segmented germanium detector is limited by the size of the initial cloud, uniformity of the electric field, and the diffusion of electrons and holes through the detector...

Study of function response of a detector HPGe to photons of reaction 19F(p,αγ)16O

International Nuclear Information System (INIS)

Tridapalli, D.B.

2006-01-01

In the 19 F(p,αγ) 16 O reaction, characteristic gamma-rays with energies: 6.1 MeV; 6.9 MeV and 7.1 keV can be observed. These photons can be used in many important applications such as Proton Induced Gamma-ray Emission (PIGE), gamma radiography and calibration purposes. It has another advantage in calibration procedures, which is the observed photon flux is greater than other reactions studied, 27 Al(p,αγ) 28 Si and 23 Na(p,αγ) 24 Mg. In our laboratory, we are studying the efficiency and response function of HPGe detectors for high energy photons, and for this it is necessary a source with a level scheme with few gamma-ray transitions and known relative yields. The 19 F(p,αγ) 16 O reaction satisfies the first condition but in the literature we found relative yields for thick targets or reaction cross section for thin targets. However, we use targets of intermediate thickness, therefore in this work we measure the relative gamma-ray yields for protons with energies between 1.36 MeV and 1.42 MeV. The experiments were performed at the 1.7 MV Pelletron tandem accelerator of the Laboratorio de Analise de Materiais por Feixes Ionicos (LAMFI) located at Instituto de Fisica da Universidade de Sao Paulo, using a reverse-electrode closed-end coaxial HPGe detector with 72.5 mm in diameter and 60.5 mm in length, at 0 deg. The proton irradiation current was 50 nA, and the target consisted of 250 μg/cm 2 CaF 2 evaporated on a 0.1 mm Ta backing. In this reaction the 20 Ne resonant state fissions in flight, and the resulting 16 O excited states have different half-lives; all observed peaks are deformed due to either Doppler broadening from 16 O random velocity direction or Doppler shift from nuclei that leave the target toward the vacuum chamber. Moreover, the peak deformations vary with the proton energy. These deformations were modeled by a Monte Carlo simulation that follows the oxygen nuclei in its trajectory until photon emission, considering the changes in spatial

Evaluation of HPGe spectrometric devices in monitoring the level of radioactive contamination in metallurgical industry

Energy Technology Data Exchange (ETDEWEB)

Petrucci, A., E-mail: andrea.petrucci@enea.it [ENEA – Istituto Nazionale di Metrologia delle Radiazione Ionizzanti, Rome (Italy); Arnold, D.; Burda, O. [PTB – Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany); De Felice, P. [ENEA – Istituto Nazionale di Metrologia delle Radiazione Ionizzanti, Rome (Italy); Garcia-Toraño, E.; Mejuto, M.; Peyres, V. [CIEMAT – Laboratorio de Metrologia de Radiaciones Ionizantes, Avda. Complutense 40, 28040 Madrid (Spain); Šolc, J. [CMI – Czech Metrology Institute, Radiova 1a, 102 00 Praha 10 (Czech Republic); Vodenik, B. [IJS – Laboratory for Radioactivity Measurements, Institute Jožef Stefan, Jamova 39, 1000 Ljubljana Slovenia (Slovenia)

2015-10-11

This paper presents the results of the tests of High Purity Germanium (HPGe) based gamma spectrometers employed for radioactivity control carried out on a daily basis in steel factories. This new application of this type of detector is part of the Joint Research Project (JRP) MetroMETAL supported by the European Metrology Research Programme (EMRP). The final purpose of the project was the improvement and standardisation of the measurement methods and systems for the control of radioactivity of recycled metal scraps at the beginning of the working process and for the certification of the absence of any radioactive contamination above the clearance levels (IAEA-TECDOC-8S5) in final steel products, Clearance levels for radionuclides in solid materials: application of exemption principles). Two prototypes based on HPGe detectors were designed and assembled to suit the needs of steel mills which had been examined previously. The evaluation of the two prototypes, carried out at three steel factories with standard sources of {sup 60}Co, {sup 137}Cs, {sup 192}Ir, {sup 226}Ra and {sup 241}Am in three different matrices (slag, fume dust and cast steel) and with samples provided on-site by the factories, was successful. The measurements proved the superiority of the prototypes over the scintillation detectors now commonly used regarding energy resolution and multi-nuclide identification capability. The detection limits were assessed and are presented as well.

The Influence Of Dead Layer Effect On The Characteristics Of The High Purity Germanium P-Type Detector

International Nuclear Information System (INIS)

Ngo Quang Huy

2011-01-01

The present work aims at reviewing the studies of the influence of dead layer effect on the characteristics of a high purity germanium (HPGe) p-type detector, obtained by the author and his colleagues in the recent years. The object for study was the HPGe GC1518 detector-based gamma spectrometer of the Center for Nuclear Techniques, Ho Chi Minh City. The studying problems were: The modeling of an HPGe detector-based gamma spectrometer with using the MCNP code; the method of determining the thickness of dead layer by experimental measurements of gamma spectra and the calculations using MCNP code; the influence of material parameters and dead layer on detector efficiency; the increase of dead layer thickness over the operating time of the GC1518 detector; the influence of dead layer thickness increase on the decrease of detector efficiency; the dead layer effect for the gamma spectra measured in the GC1518 detector. (author)

A detailed investigation of interactions within the shielding to HPGe detector response using MCNP code

Energy Technology Data Exchange (ETDEWEB)

Thanh, Tran Thien; Tao, Chau Van; Loan, Truong Thi Hong; Nhon, Mai Van; Chuong, Huynh Dinh; Au, Bui Hai [Vietnam National Univ., Ho Chi Minh City (Viet Nam). Dept. of Nuclear Physics

2012-12-15

The accuracy of the coincidence-summing corrections in gamma spectrometry depends on the total efficiency calibration that is hardly obtained over the whole energy as the required experimental conditions are not easily attained. Monte Carlo simulations using MCNP5 code was performed in order to estimate the affect of the shielding to total efficiency. The effect of HPGe response are also shown. (orig.)

Looking for anomalons with a segmented Cerenkov detector

International Nuclear Information System (INIS)

Olson, D.L.

1984-10-01

An experiment performed at the Lawrence Berkeley Laboratory Bevalac, Expt. 676H, to study the anomalon effect with a segmented total-internal-reflection Cerenkov detector is reported. Radiators of 3mm thick BK7W optical glass and 2mm thick fused silica and a beam of 40 Ca at 2.1 GeV/nucleon were used. Results are presented and discussed

Characterization of Compton-suppressed TIGRESS detectors for high energy gamma-rays

International Nuclear Information System (INIS)

Kshetri, R.; Andreoiu, C.; Cross, D.S.; Galinski, N.; Ball, G.C.; Djongolov, M.; Garnsworthy, A.B.; Hackman, G.; Orce, J.N.; Pearson, C.; Triambak, S.; Williams, S.J.; Drake, T.; Smalley, D.; Svensson, C.E.

2009-01-01

The TRIUMF-ISAC Gamma-Ray Escape- Suppressed Spectrometer (TIGRESS) will consist of 12 large-volume, 32-fold segmented HPGe clover detectors. Each detector is shielded by a 20-fold segmented Compton suppression shield. For performing discrete gamma-ray spectroscopy of light mass nuclei with TIGRESS, we need information about full energy peak efficiency, resolution and lineshape of full energy peaks for high energy gamma-rays. However, suitable radioactive sources having decay gamma-rays of energies greater than ∼ 3.5 MeV are not easily available. So the characteristics of gamma spectrometers at energies higher than 3.5 MeV are usually determined from simulation data. Predictions from GEANT4 simulations (experimentally validated from 0.3 to 3 MeV) indicate that TIGRESS will be capable for single 10 MeV gamma-rays of absolute detection efficiency of 1.5% for backward configuration of the array. It has been observed experimentally that simulation results work well up to certain energies and might deviate at higher energies. So, it is essential to check the validity of simulation results for energies above 3.3 MeV. We have investigated the high energy performance of seven TIGRESS detectors up to 8 MeV

Using the IEC standard to describe low-background detectors -- What can you expect?

International Nuclear Information System (INIS)

Keyser, R.M.; Wagner, S.

1998-01-01

Many measurements for environmental levels of the radioactive content require that the gamma-ray detector be low background, that is, free of any radioactive content. This is, of course, not possible, but the radioactivity in the detector must be reduced to as low a value as possible. The description or specification of the background spectrum necessary to achieve the desired results is needed. The new International Electrotechnical Commission (IEC) standard for describing the background makes the specification of the background in a high-purity germanium (HPGe) detector simple, unambiguous, and related to how the detector will be used. Users and manufacturers will finally be speaking the same language on this subject. Because this standard extends the specification of the performance of an HPGe detector, there is little history available for comparison and thus no means of determining a good value. To develop a history, the background spectrum for 500 low-background HPGe ORTEC detectors were all counted in similar low-background shields. These detectors were in a variety of mechanical cryostat and endcap configurations. The continuum background is a function of energy and detector size/configuration. The peak area for the peak energies listed in the standard is a function of detector size and configuration. The results thus give practical guidance for obtaining the most appropriate low-background detector for a specific measurement problem

Lithium-drifted silicon detector with segmented contacts

Science.gov (United States)

Tindall, Craig S.; Luke, Paul N.

2006-06-13

A method and apparatus for creating both segmented and unsegmented radiation detectors which can operate at room temperature. The devices include a metal contact layer, and an n-type blocking contact formed from a thin layer of amorphous semiconductor. In one embodiment the material beneath the n-type contact is n-type material, such as lithium compensated silicon that forms the active region of the device. The active layer has been compensated to a degree at which the device may be fully depleted at low bias voltages. A p-type blocking contact layer, or a p-type donor material can be formed beneath a second metal contact layer to complete the device structure. When the contacts to the device are segmented, the device is capable of position sensitive detection and spectroscopy of ionizing radiation, such as photons, electrons, and ions.

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

CERN Document Server

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

2004-01-01

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

A novel technique for detection efficiency determination of HPGe

International Nuclear Information System (INIS)

Tayyebi, Pouneh; Abbasi Davani, Fereydoun; Tabasi, Mohsen; Afarideh, Hossein

2017-01-01

In this work, we present an experimental method to determine the detection efficiency of HPGe when the reference source according to the geometry of interest is not accessible. We use known activity point sources (PS) of 152 Eu, 137 Cs, 241 Am and 133 Ba to find the detection efficiency for disc source (DS) geometry. It can be assumed that a DS consists of several PS's. Mapping the detector surface by means of 137 Cs PS shows that there is radial symmetry for detection efficiency vs. energy. Each radial distance on the detector surface contains some points, which can be considered as a PS. By selecting two points in two different radii and central point, the DS efficiency is obtained. To ensure that the method is correct, we measure the activity of a known activity DS considering DS efficiency obtained by PS's. The DS comprises 137 Cs, 133 Ba and 60 Co. The relative difference between the measured and the reported activity of DS in most energies is less than 5%. - Highlights: • Exact knowledge of the detector dimension is not necessary • There is no need to have standard source according to the sample • It is a simple method that can be done at any laboratories

Gamma radiation detectors for safeguards applications

International Nuclear Information System (INIS)

Carchon, R.; Moeslinger, M.; Bourva, L.; Bass, C.; Zendel, M.

2007-01-01

The IAEA uses extensively a variety of gamma radiation detectors to verify nuclear material. These detectors are part of standardized spectrometry systems: germanium detectors for High-Resolution Gamma Spectrometry (HRGS); Cadmium Zinc Telluride (CZT) detectors for Room Temperature Gamma Spectrometry (RTGS); and NaI(Tl) detectors for Low Resolution Gamma Spectrometry (LRGS). HRGS with high-purity Germanium (HpGe) detectors cooled by liquid nitrogen is widely used in nuclear safeguards to verify the isotopic composition of plutonium or uranium in non-irradiated material. Alternative cooling systems have been evaluated and electrically cooled HpGe detectors show a potential added value, especially for unattended measurements. The spectrometric performance of CZT detectors, their robustness and simplicity are key to the successful verification of irradiated materials. Further development, such as limiting the charge trapping effects in CZT to provide improved sensitivity and energy resolution are discussed. NaI(Tl) detectors have many applications-specifically in hand-held radioisotope identification devices (RID) which are used to detect the presence of radioactive material where a lower resolution is sufficient, as they benefit from a generally higher sensitivity. The Agency is also continuously involved in the review and evaluation of new and emerging technologies in the field of radiation detection such as: Peltier-cooled CdTe detectors; semiconductor detectors operating at room temperature such as HgI 2 and GaAs; and, scintillator detectors using glass fibres or LaBr 3 . A final conclusion, proposing recommendations for future action, is made

Position sensitivity of the first SmartPET HPGe detector

Energy Technology Data Exchange (ETDEWEB)

Cooper, R.J. [Department of Physics, University of Liverpool, Liverpool (United Kingdom)]. E-mail: rjc@ns.ph.liv.ac.uk; Turk, G. [Department of Physics, University of Liverpool, Liverpool (United Kingdom); Boston, A.J. [Department of Physics, University of Liverpool, Liverpool (United Kingdom); Boston, H.C. [Department of Physics, University of Liverpool, Liverpool (United Kingdom); Cresswell, J.R. [Department of Physics, University of Liverpool, Liverpool (United Kingdom); Mather, A.R. [Department of Physics, University of Liverpool, Liverpool (United Kingdom); Nolan, P.J. [Department of Physics, University of Liverpool, Liverpool (United Kingdom); Hall, C.J. [CCLRC Daresbury, Warrington, Cheshire (United Kingdom); Lazarus, I. [CCLRC Daresbury, Warrington, Cheshire (United Kingdom); Simpson, J. [CCLRC Daresbury, Warrington, Cheshire (United Kingdom); Berry, A. [School of Physics and materials Engineering, Monash University, Melbourne (Australia); Beveridge, T. [School of Physics and materials Engineering, Monash University, Melbourne (Australia); Gillam, J. [School of Physics and materials Engineering, Monash University, Melbourne (Australia); Lewis, R.A. [School of Physics and materials Engineering, Monash University, Melbourne (Australia)

2007-04-01

In this paper we discuss the Smart Positron Emission Tomography (PET) imaging system being developed by University of Liverpool in conjunction with CCLRC Daresbury Laboratory. We describe the motivation for the development of a semiconductor-based PET system and the advantages it will offer over current tomographs. Details of the detectors and associated electronics are discussed and results of high precision scans are presented. Analysis of this scan data has facilitated full characterization of the detector response function and calibration of the three-dimensional position sensitivity. This work presents the analysis of the depth sensitivity of the detector.

Characterisation of GERDA Phase-I detectors in liquid argon

Energy Technology Data Exchange (ETDEWEB)

Barnabe Heider, Marik; Schoenert, Stefan [Max-Planck-Institut fuer Kernphysik (Germany); Gusev, Konstantin [Russian Research Center, Kurchatov Institute (Russian Federation); Joint Institute for Nuclear Research (Russian Federation)

2009-07-01

GERDA will search for neutrinoless double beta decay in {sup 76}Ge by submerging bare enriched HPGe detectors in liquid argon. In GERDA Phase-I, reprocessed enriched-Ge detectors, which were previously operated by the Heidelberg-Moscow and IGEX collaborations, and reprocessed natural-Ge detectors from Genius-TF, will be redeployed. We have tested the operation and performance of bare HPGe detectors in liquid nitrogen and in liquid argon over more than three years with three non-enriched p-type prototype detectors. The detector handling and mounting procedures have been defined and the Phase-I detector technology, the low-mass assembly and the long-term stability in liquid argon have been tested successfully. The Phase-I detectors were reprocessed by Canberra Semiconductor NV, Olen, according to their standard technology but without the evaporation of a passivation layer. After their reprocessing, the detectors have been mounted in their low-mass holders and their characterisation in liquid argon performed. The leakage current, the counting characteristics and the efficiency of the detectors have been measured. The testing of the detectors was carried out in the liquid argon test stand of the GERDA underground Detector Laboratory (GDL) at LNGS. The detectors are now stored underground under vacuum until their operation in GERDA.

Development of a hadron blind detector using a finely segmented pad readout

International Nuclear Information System (INIS)

Kanno, Koki; Aoki, Kazuya; Aramaki, Yoki; En'yo, Hideto; Kawama, Daisuke; Komatsu, Yusuke; Masumoto, Shinichi; Nakai, Wataru; Obara, Yuki; Ozawa, Kyoichiro; Sekimoto, Michiko; Shibukawa, Takuya; Takahashi, Tomonori; Watanabe, Yosuke; Yokkaichi, Satoshi

2016-01-01

We constructed a hadron blind detector (HBD) using a finely segmented pad readout. The finely segmented pad readout enabled us to adopt an advanced particle identification method which applies a threshold to the number of pad hits in addition to the total amount of collected charge. The responses of the detector to electrons and pions were evaluated using a negatively charged secondary beam at 1.0 GeV/c containing 20% electrons at the J-PARC K1.1BR beam line. We observed 7.3 photoelectrons per incident electron. Using the advanced particle identification method, an electron detection efficiency of 83% was achieved with a pion rejection factor of 120. The method improved the pion rejection by approximately a factor of five, compared to the one which just applies a threshold to the amount of collected charge. The newly introduced finely segmented pad readout was found to be effective in rejecting pions.

Development of a hadron blind detector using a finely segmented pad readout

Energy Technology Data Exchange (ETDEWEB)

Kanno, Koki, E-mail: kkanno@post.kek.jp [Department of Physics, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); RIKEN Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Aoki, Kazuya [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba-shi, Ibaraki 305-0801 (Japan); Aramaki, Yoki; En' yo, Hideto; Kawama, Daisuke [RIKEN Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Komatsu, Yusuke; Masumoto, Shinichi [Department of Physics, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Nakai, Wataru [Department of Physics, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); RIKEN Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Obara, Yuki [Department of Physics, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Ozawa, Kyoichiro; Sekimoto, Michiko [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba-shi, Ibaraki 305-0801 (Japan); Shibukawa, Takuya [Department of Physics, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Takahashi, Tomonori [Research Center for Nuclear Physics (RCNP), Osaka University, 10-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Watanabe, Yosuke [Department of Physics, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Yokkaichi, Satoshi [RIKEN Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

2016-05-21

We constructed a hadron blind detector (HBD) using a finely segmented pad readout. The finely segmented pad readout enabled us to adopt an advanced particle identification method which applies a threshold to the number of pad hits in addition to the total amount of collected charge. The responses of the detector to electrons and pions were evaluated using a negatively charged secondary beam at 1.0 GeV/c containing 20% electrons at the J-PARC K1.1BR beam line. We observed 7.3 photoelectrons per incident electron. Using the advanced particle identification method, an electron detection efficiency of 83% was achieved with a pion rejection factor of 120. The method improved the pion rejection by approximately a factor of five, compared to the one which just applies a threshold to the amount of collected charge. The newly introduced finely segmented pad readout was found to be effective in rejecting pions.

Improvement of crystal identification performance for a four-layer DOI detector composed of crystals segmented by laser processing

Science.gov (United States)

Mohammadi, Akram; Inadama, Naoko; Yoshida, Eiji; Nishikido, Fumihiko; Shimizu, Keiji; Yamaya, Taiga

2017-09-01

We have developed a four-layer depth of interaction (DOI) detector with single-side photon readout, in which segmented crystals with the patterned reflector insertion are separately identified by the Anger-type calculation. Optical conditions between segmented crystals, where there is no reflector, affect crystal identification ability. Our objective of this work was to improve crystal identification performance of the four-layer DOI detector that uses crystals segmented with a recently developed laser processing technique to include laser processed boundaries (LPBs). The detector consisted of 2 × 2 × 4mm3 LYSO crystals and a 4 × 4 array multianode photomultiplier tube (PMT) with 4.5 mm anode pitch. The 2D position map of the detector was calculated by the Anger calculation method. At first, influence of optical condition on crystal identification was evaluated for a one-layer detector consisting of a 2 × 2 crystal array with three different optical conditions between the crystals: crystals stuck together using room temperature vulcanized (RTV) rubber, crystals with air coupling and segmented crystals with LPBs. The crystal array with LPBs gave the shortest distance between crystal responses in the 2D position map compared with the crystal array coupled with RTV rubber or air due to the great amount of cross-talk between segmented crystals with LPBs. These results were used to find optical conditions offering the optimum distance between crystal responses in the 2D position map for the four-layer DOI detector. Crystal identification performance for the four-layer DOI detector consisting of an 8 × 8 array of crystals segmented with LPBs was examined and it was not acceptable for the crystals in the first layer. The crystal identification was improved for the first layer by changing the optical conditions between all 2 × 2 crystal arrays of the first layer to RTV coupling. More improvement was observed by combining different optical conditions between all

Multichannel prototype of coordinate detector based on segmented straws

International Nuclear Information System (INIS)

Gusakov, Yu.V.; Davkov, V.I.; Davkov, K.I.; Zhukov, I.A.; Lutsenko, V.M.; Myalkovskij, V.V.; Peshekhonov, V.D.; Savenkov, A.A.

2010-01-01

The design and assembly technology of a detector prototype based on segmented straws is considered. The granularity of the prototype is 4 cm 2 . The prototype has a sensitive area of 400 x 200 mm, and contains two straw planes displaced against each other by 2 mm. The number of registration channels is 360. Preliminary results of the bench study of the prototype are presented

Improvement of core monitoring code cecor by the virtual segmentation of the self powered neutron detector loaded at Korean Standard Nuclear Plant

International Nuclear Information System (INIS)

Choi, T.; Jung, Y.S.

2006-01-01

Full text: Full text: Korean Standard Nuclear Plant uses Self Powered Neutron Detectors (SPNDs) to measure the neutron flux in the reactor core. The SPND's height is 40 cm and is located axially at the five different positions and 45 radial places. The design code simulated a reactor core is calculated by segmentation of the core. The segmentation is called as 'node', of which size is normally 20 cm. The axial height of the detector is larger than that of the node, and the larger detector's height maybe product some error on the axially complex shape. The analysis with the detector's signals showed some errors at the non-cosine axial flux shape. In order to reduce the errors for the shape, we tried to divide the detector by introducing the virtual boundary in the detector. Then, each axially 5 detectors had two virtual segmentations respectively and the detector's signal was divided by the inputs. So the more virtual detector's signals were gotten, the more accurate axial shape was produced. The result with virtual segmentations in a detector gave less deviation than the case without virtual segmentation (the current model). After the middle of cycle at the initial core specially, the axial neutron flux shape is changed to the saddle type one. The current model gave some error in Root Mean Square (RMS) between the measured value and the calculated one. The virtual segmentation model gave the better agreement at that time

Analysis of the dead layer of a detector of germanium with code ultrapure Monte Carlo SWORD-GEANT; Analisis del dead layer de un detector de germanio ultrapuro con el codigo de Monte Carlo SWORDS-GEANT

Energy Technology Data Exchange (ETDEWEB)

Gallardo, S.; Querol, A.; Ortiz, J.; Rodenas, J.; Verdu, G.

2014-07-01

In this paper the use of Monte Carlo code SWORD-GEANT is proposed to simulate an ultra pure germanium detector High Purity Germanium detector (HPGe) detector ORTEC specifically GMX40P4, coaxial geometry. (Author)

Status of the development of a HPGe-BGO pair spectrometer for ELI-NP

Energy Technology Data Exchange (ETDEWEB)

Homm, Ilja; Ignatov, Alexander; Ilieva, Stoyanka; Kroell, Thorsten [Technische Universitaet Darmstadt, Darmstadt (Germany)

2016-07-01

At the moment, the new European research facility called ELI-NP (The Extreme Light Infrastructure - Nuclear Physics) is being built in Bucharest-Magurele, Romania. It is one of three parts of the ELI project and offers applications for the investigation of questions concerning nuclear physics. The 8 HPGe (High-Purity Germanium) CLOVER detectors of ELIADE (ELI-NP Array of DEtectors) with four crystals each and high resolution are important components for the gamma spectroscopic study of photonuclear reactions. These detectors are surrounded by standard anti-Compton shields (AC shield). We investigate the possibility to operate for two of the ELIADE CLOVERS an advanced version of an AC shield as escape γ-rays pair spectrometers to extend the high-resolution spectroscopy to photon energies of several MeV where the pair production process dominates. The main tasks in this work are to develop and test such an AC shield: a pair spectrometer with BGO and CsI(Tl) crystals with APD (avalanche photodiode) or SPM (silicon photomultiplier) readout. The results of prototype testing are reported.

Segmented detector for recoil neutrons in the p(γ, n)π+ reaction

International Nuclear Information System (INIS)

Korkmaz, E.; O'Rielly, G.V.; Hutcheon, D.A.; Feldman, G.; Jordan, D.; Kolb, N.R.; Pywell, R.E.; Retzlaff, G.A.; Sawatzky, B.D.; Skopik, D.M.; Vogt, J.M.; Cairns, E.; Giesen, U.; Holm, L.; Opper, A.K.; Rozon, F.M.; Soukup, J.

1999-01-01

A segmented neutron detector has been constructed and used for recoil neutron (6-13 MeV) measurements of the reaction γp→nπ + very close to threshold. BC-505 liquid scintillator was used to allow pulse shape discrimination between neutrons and photons. A measurement of the absolute efficiency of the detector was performed using stopped pions in the reaction π - p→nγ. Results of the efficiency calibration are compared to a Monte Carlo simulation. (author)

Determination of relative efficiency of a detector using Monte Carlo method

International Nuclear Information System (INIS)

Medeiros, M.P.C.; Rebello, W.F.; Lopes, J.M.; Silva, A.X.

2015-01-01

High-purity germanium detectors (HPGe) are mandatory tools for spectrometry because of their excellent energy resolution. The efficiency of such detectors, quoted in the list of specifications by the manufacturer, frequently refers to the relative full-energy peak efficiency, related to the absolute full-energy peak efficiency of a 7.6 cm x 7.6 cm (diameter x height) NaI(Tl) crystal, based on the 1.33 MeV peak of a 60 Co source positioned 25 cm from the detector. In this study, we used MCNPX code to simulate an HPGe detector (Canberra GC3020), from Real-Time Neutrongraphy Laboratory of UFRJ, to survey the spectrum of a 60 Co source located 25 cm from the detector in order to calculate and confirm the efficiency declared by the manufacturer. Agreement between experimental and simulated data was achieved. The model under development will be used for calculating and comparison purposes with the detector calibration curve from software Genie2000™, also serving as a reference for future studies. (author)

Preliminary uranium enrichment analysis results using cadmium zinc telluride detectors

International Nuclear Information System (INIS)

Lavietes, A.D.; McQuaid, J.H.; Paulus, T.J.

1995-01-01

Lawrence Livermore National Laboratory (LLNL) and EG ampersand G ORTEC have jointly developed a portable ambient-temperature detection system that can be used in a number of application scenarios. The detection system uses a planar cadmium zinc telluride (CZT) detector with custom-designed detector support electronics developed at LLNL and is based on the recently released MicroNOMAD multichannel analyzer (MCA) produced by ORTEC. Spectral analysis is performed using software developed at LLNL that was originally designed for use with high-purity germanium (HPGe) detector systems. In one application, the CZT detection system determines uranium enrichments ranging from less than 3% to over 75% to within accuracies of 20%. The analysis was performed using sample sizes of 200 g or larger and acquisition times of 30 min. The authors have demonstrated the capabilities of this system by analyzing the spectra gathered by the CZT detection system from uranium sources of several enrichments. These experiments demonstrate that current CZT detectors can, in some cases, approach performance criteria that were previously the exclusive domain of larger HPGe detector systems

TIGRESS: TRIUMF-ISAC gamma-ray escape-suppressed spectrometer

Science.gov (United States)

Svensson, C. E.; Amaudruz, P.; Andreoiu, C.; Andreyev, A.; Austin, R. A. E.; Ball, G. C.; Bandyopadhyay, D.; Boston, A. J.; Chakrawarthy, R. S.; Chen, A. A.; Churchman, R.; Drake, T. E.; Finlay, P.; Garrett, P. E.; Grinyer, G. F.; Hackman, G.; Hyland, B.; Jones, B.; Kanungo, R.; Maharaj, R.; Martin, J. P.; Morris, D.; Morton, A. C.; Pearson, C. J.; Phillips, A. A.; Ressler, J. J.; Roy, R.; Sarazin, F.; Schumaker, M. A.; Scraggs, H. C.; Smith, M. B.; Starinsky, N.; Valiente-Dobón, J. J.; Waddington, J. C.; Watters, L. M.

2005-10-01

The TRIUMF-ISAC gamma-ray escape-suppressed spectrometer (TIGRESS) is a new γ-ray detector array being developed for use at TRIUMF's Isotope Separator and Accelerator (ISAC) radioactive ion beam facility. TIGRESS will comprise 12 32-fold segmented clover-type HPGe detectors coupled with 20-fold segmented modular Compton suppression shields and custom digital signal processing electronics. This paper provides an overview of the TIGRESS project and progress in its development to date.

Extrapolated HPGe efficiency estimates based on a single calibration measurement

International Nuclear Information System (INIS)

Winn, W.G.

1994-01-01

Gamma spectroscopists often must analyze samples with geometries for which their detectors are not calibrated. The effort to experimentally recalibrate a detector for a new geometry can be quite time consuming, causing delay in reporting useful results. Such concerns have motivated development of a method for extrapolating HPGe efficiency estimates from an existing single measured efficiency. Overall, the method provides useful preliminary results for analyses that do not require exceptional accuracy, while reliably bracketing the credible range. The estimated efficiency element-of for a uniform sample in a geometry with volume V is extrapolated from the measured element-of 0 of the base sample of volume V 0 . Assuming all samples are centered atop the detector for maximum efficiency, element-of decreases monotonically as V increases about V 0 , and vice versa. Extrapolation of high and low efficiency estimates element-of h and element-of L provides an average estimate of element-of = 1/2 [element-of h + element-of L ] ± 1/2 [element-of h - element-of L ] (general) where an uncertainty D element-of = 1/2 (element-of h - element-of L ] brackets limits for a maximum possible error. The element-of h and element-of L both diverge from element-of 0 as V deviates from V 0 , causing D element-of to increase accordingly. The above concepts guided development of both conservative and refined estimates for element-of

Full energy peak efficiency of NaI(Tl) gamma detectors and its analytical and semi-empirical representations

International Nuclear Information System (INIS)

Sudarshan, M.; Joseph, J.; Singh, R.

1992-01-01

The validity of various analytical functions and semi-empirical formulae proposed for representing the full energy peak efficiency (FEPE) curves of Ge(Li) and HPGe detectors has been tested for the FEPE of 7.6 cm x 7.6 cm and 5 cm x 5 cm Nal(Tl) detectors in the gamma energy range from 59.5 to 1408.03 keV. The functions proposed by East, and McNelles and Campbell provide by far the best representations of the present data. The semi-empirical formula of Mowatt describes the present data very well. The present investigation shows that some of the analytical functions and semi-empirical formulae, which represent the FEPE of the Ge(Li) and HPGe detectors very well, can be quite fruitfully used for Nal(Tl) detectors. (Author)

Evaluation of Segmented Amorphous-Contact Planar Germanium Detectors for Heavy-Element Research

Science.gov (United States)

Jackson, Emily G.

The challenge of improving our understanding of the very heaviest nuclei is at the forefront of contemporary low-energy nuclear physics. In the last two decades, "in-beam" spectroscopy experiments have advanced from Z=98 to Z=104, Rutherfordium, allowing insights into the dynamics of the fission barrier, high-order deformations, and pairing correlations. However, new detector technologies are needed to advance to even heavier nuclei. This dissertation is aimed at evaluating one promising new technology; large segmented planar germanium wafers for this area of research. The current frontier in gamma-ray spectroscopy involves large-volume (>9 cm thick) coaxial detectors that are position sensitive and employ gamma-ray "tracking". In contrast, the detectors assessed in this dissertation are relatively thin (~1 cm) segmented planar wafers with amorphous-germanium strip contacts that can tolerate extremely high gamma-ray count rates, and can accommodate hostile neutron fluxes. They may be the only path to heavier "in-beam" spectroscopy with production rates below 1 nanobarn. The resiliency of these detectors against neutron-induced damage is examined. Two detectors were deliberately subjected to a non-uniform neutron fluence leading to considerable degradation of performance. The neutrons were produced using the 7Li(p, n)7Be reaction at the UMass Lowell Van-de-Graaff accelerator with a 3.7-MeV proton beam incident on a natural Li target. The energy of the neutrons emitted at zero degrees was 2.0 MeV, close to the mean energy of the fission neutron spectrum, and each detector was exposed to a fluence >3.6 x109 n/cm2. A 3-D software "trap-corrector" gain-matching algorithm considerably restored the overall performance. Other neutron damage mitigation tactics were explored including over biasing the detector and flooding the detector with a high gamma-ray count rate. Various annealing processes to remove neutron damage were investigated. An array of very large diameter

Metrological tests of a 200 L calibration source for HPGE detector systems for assay of radioactive waste drums

International Nuclear Information System (INIS)

Boshkova, T.; Mitev, K.

2016-01-01

In this work we present test procedures, approval criteria and results from two metrological inspections of a certified large volume "1"5"2Eu source (drum about 200 L) intended for calibration of HPGe gamma assay systems used for activity measurement of radioactive waste drums. The aim of the inspections was to prove the stability of the calibration source during its working life. The large volume source was designed and produced in 2007. It consists of 448 identical sealed radioactive sources (modules) apportioned in 32 transparent plastic tubes which were placed in a wooden matrix which filled the drum. During the inspections the modules were subjected to tests for verification of their certified characteristics. The results show a perfect compliance with the NIST basic guidelines for the properties of a radioactive certified reference material (CRM) and demonstrate the stability of the large volume CRM-drum after 7 years of operation. - Highlights: • Large (200 L) volume drum source designed, produced and certified as CRM in 2007. • Source contains 448 identical sealed radioactive "1"5"2Eu sources (modules). • Two metrological inspections in 2011 and 2014. • No statistically significant changes of the certified characteristics over time. • Stable calibration source for HPGe-gamma radioactive waste assay systems.

Segment-Tube: Spatio-Temporal Action Localization in Untrimmed Videos with Per-Frame Segmentation

OpenAIRE

Le Wang; Xuhuan Duan; Qilin Zhang; Zhenxing Niu; Gang Hua; Nanning Zheng

2018-01-01

Inspired by the recent spatio-temporal action localization efforts with tubelets (sequences of bounding boxes), we present a new spatio-temporal action localization detector Segment-tube, which consists of sequences of per-frame segmentation masks. The proposed Segment-tube detector can temporally pinpoint the starting/ending frame of each action category in the presence of preceding/subsequent interference actions in untrimmed videos. Simultaneously, the Segment-tube detector produces per-fr...

Surface Alpha Interactions in P-Type Point-Contact HPGe Detectors: Maximizing Sensitivity of 76Ge Neutrinoless Double-Beta Decay Searches

Science.gov (United States)

Gruszko, Julieta

Though the existence of neutrino oscillations proves that neutrinos must have non-zero mass, Beyond-the-Standard-Model physics is needed to explain the origins of that mass. One intriguing possibility is that neutrinos are Majorana particles, i.e., they are their own anti-particles. Such a mechanism could naturally explain the observed smallness of the neutrino masses, and would have consequences that go far beyond neutrino physics, with implications for Grand Unification and leptogenesis. If neutrinos are Majorana particles, they could undergo neutrinoless double-beta decay (0nBB), a hypothesized rare decay in which two antineutrinos annihilate one another. This process, if it exists, would be exceedingly rare, with a half-life over 1E25 years. Therefore, searching for it requires experiments with extremely low background rates. One promising technique in the search for 0nBB is the use of P-type point-contact (P-PC) high-purity Germanium (HPGe) detectors enriched in 76Ge, operated in large low-background arrays. This approach is used, with some key differences, by the MAJORANA and GERDA Collaborations. A problematic background in such large granular detector arrays is posed by alpha particles incident on the surfaces of the detectors, often caused by 222Rn contamination of parts or of the detectors themselves. In the MAJORANA DEMONSTRATOR, events have been observed that are consistent with energy-degraded alphas originating near the passivated surface of the detectors, leading to a potential background contribution in the region-of-interest for neutrinoless double-beta decay. However, it is also observed that when energy deposition occurs very close to the passivated surface, high charge trapping occurs along with subsequent slow charge re-release. This leads to both a reduced prompt signal and a measurable change in slope of the tail of a recorded pulse. Here we discuss the characteristics of these events and the development of a filter that can identify the

The Edge Detectors Suitable for Retinal OCT Image Segmentation

Directory of Open Access Journals (Sweden)

Su Luo

2017-01-01

Full Text Available Retinal layer thickness measurement offers important information for reliable diagnosis of retinal diseases and for the evaluation of disease development and medical treatment responses. This task critically depends on the accurate edge detection of the retinal layers in OCT images. Here, we intended to search for the most suitable edge detectors for the retinal OCT image segmentation task. The three most promising edge detection algorithms were identified in the related literature: Canny edge detector, the two-pass method, and the EdgeFlow technique. The quantitative evaluation results show that the two-pass method outperforms consistently the Canny detector and the EdgeFlow technique in delineating the retinal layer boundaries in the OCT images. In addition, the mean localization deviation metrics show that the two-pass method caused the smallest edge shifting problem. These findings suggest that the two-pass method is the best among the three algorithms for detecting retinal layer boundaries. The overall better performance of Canny and two-pass methods over EdgeFlow technique implies that the OCT images contain more intensity gradient information than texture changes along the retinal layer boundaries. The results will guide our future efforts in the quantitative analysis of retinal OCT images for the effective use of OCT technologies in the field of ophthalmology.

Virtual point detector: On the interpolation and extrapolation of scintillation detectors counting efficiencies

International Nuclear Information System (INIS)

Presler, Oren; German, Uzi; Pushkarsky, Vitaly; Alfassi, Zeev B.

2006-01-01

The concept of transforming the detector volume to a virtual point detector, in order to facilitate efficiency evaluations for different source locations, was proposed in the past for HPGe and Ge(Li) detectors. The validity of this model for NaI(Tl) and BGO scintillation detectors was studied in the present work. It was found that for both scintillation detectors, the point detector model does not seem to fit too well to the experimental data, for the whole range of source-to-detector distances; however, for source-to-detector cap distances larger than 4 cm, the accuracy was found to be high. A two-parameter polynomial expression describing the dependence of the normalized count rate versus the source-to-detector distance was fitted to the experimental data. For this fit, the maximum deviations are up to about 12%. These deviations are much smaller than the values obtained by applying the virtual point concept, even for distances greater than 4 cm, thus the polynomial fitting is to be preferred for scintillation detectors

Qualitative and quantitative validation of the SINBAD code on complex HPGe gamma-ray spectra

Energy Technology Data Exchange (ETDEWEB)

Rohee, E.; Coulon, R.; Normand, S.; Carrel, F. [CEA, LIST, Laboratoire Capteurs et Architectures electroniques, F-91191 Gif-sur-Yvette, (France); Dautremer, T.; Barat, E.; Montagu, T. [CEA, LIST, Laboratoire Modelisation, Simulation et Systemes, F-91191 Gif-sur-Yvette, (France); Jammes, C. [CEA/DEN/SPEx/LDCI, Centre de Cadarache, F-13109 Saint-Paul-lez-Durance, (France)

2015-07-01

Radionuclides identification and quantification is a serious concern for many applications as safety or security of nuclear power plant or fuel cycle facility, CBRN risk identification, environmental radioprotection and waste measurements. High resolution gamma-ray spectrometry based on HPGe detectors is a performing solution for all these topics. During last decades, a great number of software has been developed to improve gamma spectra analysis. However, some difficulties remain in the analysis when photoelectric peaks are folded together with a high ratio between theirs amplitudes, when the Compton background is much larger compared to the signal of a single peak and when spectra are composed of a great number of peaks. This study deals with the comparison between conventional methods in radionuclides identification and quantification and the code called SINBAD ('Spectrometrie par Inference Non parametrique Bayesienne Deconvolutive'). For many years, SINBAD has been developed by CEA LIST for unfolding complex spectra from HPGe detectors. Contrary to conventional methods using fitting procedures, SINBAD uses a probabilistic approach with Bayesian inference to describe spectrum data. This conventional fitting method founded for example in Genie 2000 is compared with the nonparametric SINBAD approach regarding some key figures of merit as the peak centroid evaluation (identification) and peak surface evaluation (quantification). Unfriendly cases are studied for nuclides detection with closed gamma-rays energies and high photoelectric peak intensity differences. Tests are performed with spectra from the International Atomic Energy Agency (IAEA) for gamma spectra analysis software benchmark and with spectra acquired at the laboratory. Results show that SINBAD and Genie 2000 performances are quite similar with sometimes best results for SINBAD with the important difference that to achieve same performances the nonparametric method is user-friendly compared

Lung counting: Comparison of a four detector array that has either metal or carbon fiber end caps, and the effect on array performance characteristics

International Nuclear Information System (INIS)

Sabbir Ahmed, Asm; Kramer, Gary H.

2011-01-01

This study described the performance of an array of HPGe detectors, made by ORTEC. In the existing system, a metal end cap was used in the detector construction. In general, the natural metal contains some radioactive materials, create high background noises and signals during in vivo counting. ORTEC proposed a novel carbon fiber to be used in end cap, without any radio active content. This paper described the methodology of developing a model of the given HPGe array-detectors, comparing the detection efficiency and cross talk among the detectors using two end cap materials: either metal or carbon fiber and to provide a recommendation about the end cap material. The detector's counting efficiency were studied using point and plane sources. The cross talk among the array detectors were studied using a homogeneous attenuating medium made of tissue equivalent material. The cross talk was significant when single or multiple point sources (simulated to heterogeneous hot spots) were embedded inside the attenuating medium. With carbon fiber, the cross talk increased about 100% for photon energy at about 100 keV. For a uniform distribution of radioactive material, the cross talk increased about 5-10% when the end cap was made of carbon instead of steel. Metal end cap was recommended for the array of HPGe detectors.

Test of GERDA Phase II detector assembly

Energy Technology Data Exchange (ETDEWEB)

Bode, Tobias; Gusev, Konstantin [Technische Universitaet Muenchen (Germany); Schwingenheuer, Bernhard; Wagner, Victoria [Max-Planck Institut fuer Kernphysik, Heidelberg (Germany); Collaboration: GERDA-Collaboration

2014-07-01

The GERDA experiment searches for the lepton number violating neutrinoless double beta decay (0νββ) of {sup 76}Ge. The experiment uses HPGe detectors enriched in {sup 76}Ge as source and detection material. In GERDA Phase I five BEGe detectors were operated successfully. These detectors are distinguished for improved energy resolution and enhanced pulse shape discrimination (PSD) against background events. In Phase II additional 25 BEGe detectors will be installed. New electronics and radio-pure low-mass holders were specially designed for Phase II. Prior to the installation in GERDA all BEGe detectors are tested in their final assembly in the LNGS underground laboratory. This talk presents the mechanics and performance of the GERDA Phase II detector assembly.

Germanium nitride and oxynitride films for surface passivation of Ge radiation detectors

Energy Technology Data Exchange (ETDEWEB)

Maggioni, G., E-mail: maggioni@lnl.infn.it [Dipartimento di Fisica e Astronomia G. Galilei, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Laboratori Nazionali di Legnaro, Istituto Nazionale di Fisica Nucleare, Viale dell’Universita’2, I-35020 Legnaro, Padova (Italy); Carturan, S. [Dipartimento di Fisica e Astronomia G. Galilei, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Laboratori Nazionali di Legnaro, Istituto Nazionale di Fisica Nucleare, Viale dell’Universita’2, I-35020 Legnaro, Padova (Italy); Fiorese, L. [Laboratori Nazionali di Legnaro, Istituto Nazionale di Fisica Nucleare, Viale dell’Universita’2, I-35020 Legnaro, Padova (Italy); Dipartimento di Ingegneria dei Materiali e delle Tecnologie Industriali, Università di Trento, Via Mesiano 77, I-38050 Povo, Trento (Italy); Pinto, N.; Caproli, F. [Scuola di Scienze e Tecnologie, Sezione di Fisica, Università di Camerino, Via Madonna delle Carceri 9, Camerino (Italy); INFN, Sezione di Perugia, Perugia (Italy); Napoli, D.R. [Laboratori Nazionali di Legnaro, Istituto Nazionale di Fisica Nucleare, Viale dell’Universita’2, I-35020 Legnaro, Padova (Italy); Giarola, M.; Mariotto, G. [Dipartimento di Informatica—Università di Verona, Strada le Grazie 15, I-37134 Verona (Italy)

2017-01-30

Highlights: • A surface passivation method for HPGe radiation detectors is proposed. • Highly insulating GeNx- and GeOxNy-based layers are deposited at room temperature. • Deposition parameters affect composition and electrical properties of the layers. • The improved performance of a GeNx-coated HPGe diode is assessed. - Abstract: This work reports a detailed investigation of the properties of germanium nitride and oxynitride films to be applied as passivation layers to Ge radiation detectors. All the samples were deposited at room temperature by reactive RF magnetron sputtering. A strong correlation was found between the deposition parameters, such as deposition rate, substrate bias and atmosphere composition, and the oxygen and nitrogen content in the film matrix. We found that all the films were very poorly crystallized, consisting of very small Ge nitride and oxynitride nanocrystallites, and electrically insulating, with the resistivity changing from three to six orders of magnitude as a function of temperature. A preliminary test of these films as passivation layers was successfully performed by depositing a germanium nitride film on the intrinsic surface of a high-purity germanium (HPGe) diode and measuring the improved performance, in terms of leakage current, with respect to a reference passivated diode. All these interesting results allow us to envisage the application of this coating technology to the surface passivation of germanium-based radiation detectors.

Multiagency Urban Search Experiment Detector and Algorithm Test Bed

Science.gov (United States)

Nicholson, Andrew D.; Garishvili, Irakli; Peplow, Douglas E.; Archer, Daniel E.; Ray, William R.; Swinney, Mathew W.; Willis, Michael J.; Davidson, Gregory G.; Cleveland, Steven L.; Patton, Bruce W.; Hornback, Donald E.; Peltz, James J.; McLean, M. S. Lance; Plionis, Alexander A.; Quiter, Brian J.; Bandstra, Mark S.

2017-07-01

In order to provide benchmark data sets for radiation detector and algorithm development, a particle transport test bed has been created using experimental data as model input and validation. A detailed radiation measurement campaign at the Combined Arms Collective Training Facility in Fort Indiantown Gap, PA (FTIG), USA, provides sample background radiation levels for a variety of materials present at the site (including cinder block, gravel, asphalt, and soil) using long dwell high-purity germanium (HPGe) measurements. In addition, detailed light detection and ranging data and ground-truth measurements inform model geometry. This paper describes the collected data and the application of these data to create background and injected source synthetic data for an arbitrary gamma-ray detection system using particle transport model detector response calculations and statistical sampling. In the methodology presented here, HPGe measurements inform model source terms while detector response calculations are validated via long dwell measurements using 2"×4"×16" NaI(Tl) detectors at a variety of measurement points. A collection of responses, along with sampling methods and interpolation, can be used to create data sets to gauge radiation detector and algorithm (including detection, identification, and localization) performance under a variety of scenarios. Data collected at the FTIG site are available for query, filtering, visualization, and download at muse.lbl.gov.

GRABGAM: A Gamma Analysis Code for Ultra-Low-Level HPGe SPECTRA

Energy Technology Data Exchange (ETDEWEB)

Winn, W.G.

1999-07-28

The GRABGAM code has been developed for analysis of ultra-low-level HPGe gamma spectra. The code employs three different size filters for the peak search, where the largest filter provides best sensitivity for identifying low-level peaks and the smallest filter has the best resolution for distinguishing peaks within a multiplet. GRABGAM basically generates an integral probability F-function for each singlet or multiplet peak analysis, bypassing the usual peak fitting analysis for a differential f-function probability model. Because F is defined by the peak data, statistical limitations for peak fitting are avoided; however, the F-function does provide generic values for peak centroid, full width at half maximum, and tail that are consistent with a Gaussian formalism. GRABGAM has successfully analyzed over 10,000 customer samples, and it interfaces with a variety of supplementary codes for deriving detector efficiencies, backgrounds, and quality checks.

On the achievable field sensitivity of a segmented annular detector for differential phase contrast measurements

International Nuclear Information System (INIS)

Schwarzhuber, Felix; Melzl, Peter; Zweck, Josef

2017-01-01

Highlights: • Practical guide to calibrate a DPC setup considering geometrical parameters. • Optimizing the field sensitivity of a segmented annular DPC detector. • Determination of maximum electric and magnetic field sensitivity of a DPC setup. - Abstract: Differential phase contrast microscopy measures minute deflections of the electron probe due to electric and/or magnetic fields, using a position sensitive device. Although recently, pixelated detectors have become available which also serve as a position sensitive device, the most frequently used detector is a four-segmented annular semiconducting detector ring (or variations thereof), where the difference signals of opposing detector elements represent the components of the deflection vector. This deflection vector can be used directly to quantitatively determine the deflecting field, provided the specimen’s thickness is known. While there exist many measurements of both electric and magnetic fields, even at an atomic level, until now the question of the smallest clearly resolvable field value for this detector has not yet been answered. This paper treats the problem theoretically first, leading to a calibration factor κ which depends solely on simple, experimentally accessible parameters and relates the deflecting field to the measured deflection vector. In a second step, the calibration factor for our combination of microscope and detector is determined experimentally for various combinations of camera length, condenser aperture and spot size to determine the optimum setup. From this optimized condition we determine the minimum change in field which leads to a clearly measurable signal change for both HMSTEM and LMSTEM operation. A strategy is described which allows the experimenter to choose the setup giving the highest field sensitivity. Quantification problems due to scattering processes in the specimen are addressed and ways are shown to choose a setup which is less sensitive to these artefacts.

On the achievable field sensitivity of a segmented annular detector for differential phase contrast measurements

Energy Technology Data Exchange (ETDEWEB)

Schwarzhuber, Felix, E-mail: felix.schwarzhuber@ur.de; Melzl, Peter; Zweck, Josef

2017-06-15

Highlights: • Practical guide to calibrate a DPC setup considering geometrical parameters. • Optimizing the field sensitivity of a segmented annular DPC detector. • Determination of maximum electric and magnetic field sensitivity of a DPC setup. - Abstract: Differential phase contrast microscopy measures minute deflections of the electron probe due to electric and/or magnetic fields, using a position sensitive device. Although recently, pixelated detectors have become available which also serve as a position sensitive device, the most frequently used detector is a four-segmented annular semiconducting detector ring (or variations thereof), where the difference signals of opposing detector elements represent the components of the deflection vector. This deflection vector can be used directly to quantitatively determine the deflecting field, provided the specimen’s thickness is known. While there exist many measurements of both electric and magnetic fields, even at an atomic level, until now the question of the smallest clearly resolvable field value for this detector has not yet been answered. This paper treats the problem theoretically first, leading to a calibration factor κ which depends solely on simple, experimentally accessible parameters and relates the deflecting field to the measured deflection vector. In a second step, the calibration factor for our combination of microscope and detector is determined experimentally for various combinations of camera length, condenser aperture and spot size to determine the optimum setup. From this optimized condition we determine the minimum change in field which leads to a clearly measurable signal change for both HMSTEM and LMSTEM operation. A strategy is described which allows the experimenter to choose the setup giving the highest field sensitivity. Quantification problems due to scattering processes in the specimen are addressed and ways are shown to choose a setup which is less sensitive to these artefacts.

Efficiency correction for disk sources using coaxial High-Purity Ge detectors

International Nuclear Information System (INIS)

Chatani, Hiroshi.

1993-03-01

Efficiency correction factors for disk sources were determined by making use of closed-ended coaxial High-Purity Ge (HPGe) detectors, their relative efficiencies for a 3' 'x3' ' NaI(Tl) with the 1.3 MeV γ-rays were 30 % and 10 %, respectively. Parameters for the correction by mapping method were obtained systematically, using several monoenergetic (i.e. no coincidence summing loses) γ-ray sources produced by irradiation in the Kyoto University Reactor (KUR) core. These were found out that (1) the systematics of the Gaussian fitting parameters, which were calculated using the relative efficiency distributions of HPGe, to the γ-ray energies are recognized, (2) the efficiency distributions deviate from the Gaussian distributions outside of the radii of HPGe. (3) mapping method is a practical use in satisfactory accuracy, as the results in comparison with the disk source measurements. (author)

Evaluation of detectors for blood bioanalysis in Lu-177 and I-131 therapies for bone marrow dosimetry; Avaliacao de detectores para bioanalise de sangue em terapias com Lu-177 and I-131 para dosimetria de medula ossea

Energy Technology Data Exchange (ETDEWEB)

Degenhardt, Amilie Louize

2016-10-01

The measures traceability is mandatory for minimizing uncertainties in internal dosimetry for radiopharmaceuticals clinical studies and ensures the quality of the standard. Equipment should have resolution and efficiency compatible with radionuclides energies and, additionally, be able to quantify variations in human bodies' activities samples since the initial administration near the minimum residual activities. For testing three equipment (ionization chamber Capintec 25R, sodium iodine scintillator LTI Genesys Gamma-1 and high hyperpure germanium detector Canberra), they were prepared Lu-177 and I-131 radiation sources simulating patient's blood samples activities by adopting the following hypothesis: (1) initial activities according the Brazilian protocols; (2) blood volume in the whole body (5.3 L for adult men and 1.4 L for 5 years-old children); (3) effective half-lives (1.61 h and 42.9 h for Lu-177 bi-exponential adjustment and 15.7 h for I-131 mono-exponential adjustment); (4) sampling between 30 min and 168 h; (v) blood density adjustments. The standard sources were measured in the secondary standard ionization chamber Centronics IG11 at the Laboratorio Nacional de Metrologia das Radiacoes Ionizantes. The Capintec ionization chamber efficiencies ranged, respectively for I-131 and Lu-177, between (111.58±0.02)% and (102.27±0.01)% and HPGe semiconductor detector efficiencies ranged, respectively, between (89.40±0.03)% and (87.80±0.04)%. For the NaI detector, when the Lu-177 sources were positioned inside the detector the efficiencies ranged between (12.66±0.01)% and (11.54± 0.07)% and when the sources were positioned at 5 cm and 10 cm from the detector the efficiencies decreased to less than 5%. For I-131 sources positioned inside the detector, the efficiencies ranged between (29.76±0.21)% and (30.20±0.04)% and they decreased to less than 5% when they were positioned at 5 cm and 10 cm from the detector (deviation greater than 95

A segmented Hybrid Photon Detector with integrated auto-triggering front-end electronics for a PET scanner

CERN Document Server

Chesi, Enrico Guido; Joram, C; Mathot, S; Séguinot, Jacques; Weilhammer, P; Ciocia, F; De Leo, R; Nappi, E; Vilardi, I; Argentieri, A; Corsi, F; Dragone, A; Pasqua, D

2006-01-01

We describe the design, fabrication and test results of a segmented Hybrid Photon Detector with integrated auto-triggering front-end electronics. Both the photodetector and its VLSI readout electronics are custom designed and have been tailored to the requirements of a recently proposed novel geometrical concept of a Positron Emission Tomograph. Emphasis is put on the PET specific features of the device. The detector has been fabricated in the photocathode facility at CERN.

Shaped detector

International Nuclear Information System (INIS)

Carlson, R.W.

1981-01-01

A radiation detector or detector array which has a non-constant spatial response, is disclosed individually and in combination with a tomographic scanner. The detector has a first dimension which is oriented parallel to the plane of the scan circle in the scanner. Along the first dimension, the detector is most responsive to radiation received along a centered segment of the dimension and less responsive to radiation received along edge segments. This non-constant spatial response can be achieved in a detector comprised of a scintillation crystal and a photoelectric transducer. The scintillation crystal in one embodiment is composed of three crystals arranged in layers, with the center crystal having the greatest light conversion efficiency. In another embodiment, the crystal is covered with a reflective substance around the center segment and a less reflective substance around the remainder. In another embodiment, an optical coupling which transmits light from adjacent the center segment with the greatest intensity couples the scintillation crystal and the photoelectric transducer. In yet another embodiment, the photoelectric transducer comprises three photodiodes, one receiving light produced adjacent the central segment and the other two receiving light produced adjacent the edge segments. The outputs of the three photodiodes are combined with a differential amplifier

Study of semiconductor detectors applied to diagnostic X-ray

International Nuclear Information System (INIS)

Salgado, Cesar Marques

2003-08-01

This work aims an evaluation of procedures for photons spectrum determination, produced by a X ray tube, normally used for medical diagnoses which operation voltage ranges from 20 to 150 kVp, to allow more precise characterization of the photon beam. The use of spectrum analysis will contribute to reduce the uncertainty in the ionization camera calibrations. For this purpose, two kind of detectors were selected, a Cadmium Zinc Telluride (CZT) and a planar HPGe detector. The X ray interaction with the detector's crystal produces, by electronic processes, a pulse high distribution as an output, which is no the true photon spectrum, due to the presence of K shell escape peaks, Compton scattering and to the fact that the detectors efficiency diminish rapidly with the increase of the photon energy. A detailed analysis of the contributing factors to distortions in the spectrum is necessary and was performed by Monte Carlo calculation with the MCNP 4B computer code. In order to determine the actual photon spectrum for a X ray tube a spectra stripping procedure is described for the HPGe detector. The detector's response curves, determined by the Monte Carlo calculation, were compared to the experimental ones, for isotropic point sources. For the methodology validation, stripped spectra were compared to the theoretical ones, for the same X ray tube's settings, for a qualitative evaluation. The air kerma rate calculated with the photon spectra were compared to the direct measurement using an ionization chamber, for a quantitative evaluation. (author)

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

Evaluation of detectors for blood bioanalysis in Lu-177 and I-131 therapies for bone marrow dosimetry

International Nuclear Information System (INIS)

Degenhardt, Amilie Louize

2016-01-01

The measures traceability is mandatory for minimizing uncertainties in internal dosimetry for radiopharmaceuticals clinical studies and ensures the quality of the standard. Equipment should have resolution and efficiency compatible with radionuclides energies and, additionally, be able to quantify variations in human bodies' activities samples since the initial administration near the minimum residual activities. For testing three equipment (ionization chamber Capintec 25R, sodium iodine scintillator LTI Genesys Gamma-1 and high hyperpure germanium detector Canberra), they were prepared Lu-177 and I-131 radiation sources simulating patient's blood samples activities by adopting the following hypothesis: (1) initial activities according the Brazilian protocols; (2) blood volume in the whole body (5.3 L for adult men and 1.4 L for 5 years-old children); (3) effective half-lives (1.61 h and 42.9 h for Lu-177 bi-exponential adjustment and 15.7 h for I-131 mono-exponential adjustment); (4) sampling between 30 min and 168 h; (v) blood density adjustments. The standard sources were measured in the secondary standard ionization chamber Centronics IG11 at the Laboratorio Nacional de Metrologia das Radiacoes Ionizantes. The Capintec ionization chamber efficiencies ranged, respectively for I-131 and Lu-177, between (111.58±0.02)% and (102.27±0.01)% and HPGe semiconductor detector efficiencies ranged, respectively, between (89.40±0.03)% and (87.80±0.04)%. For the NaI detector, when the Lu-177 sources were positioned inside the detector the efficiencies ranged between (12.66±0.01)% and (11.54± 0.07)% and when the sources were positioned at 5 cm and 10 cm from the detector the efficiencies decreased to less than 5%. For I-131 sources positioned inside the detector, the efficiencies ranged between (29.76±0.21)% and (30.20±0.04)% and they decreased to less than 5% when they were positioned at 5 cm and 10 cm from the detector (deviation greater than 95

Active noise canceling system for mechanically cooled germanium radiation detectors

Science.gov (United States)

Nelson, Karl Einar; Burks, Morgan T

2014-04-22

A microphonics noise cancellation system and method for improving the energy resolution for mechanically cooled high-purity Germanium (HPGe) detector systems. A classical adaptive noise canceling digital processing system using an adaptive predictor is used in an MCA to attenuate the microphonics noise source making the system more deployable.

Development of a segmented gamma ray scanning system

International Nuclear Information System (INIS)

Zhu Rongbao; Tan Yajun; Yuan Xiaoxin

1994-01-01

A segmented gamma ray scanning system is developed for the purposes of non-destructive assay of the contents of uranium, plutonium or fission products existing in packed low density or medium density nuclear residuals, scrapes or wastes. The near field three-dimensional model for computing CF(AT) is used for cylindrical sample and container, the system developed consists of a transmission source wheel, a rotatable scanning plate, a beam shutter, and annular shielding body, stepping motors and control system, HPGe detector, nuclear electronics and computer. The full scale scanning of samples, spectrum accumulation and data reduction could be fulfilled automatically according to preset standard procedures. The radioisotopes of 169 Yb and 75 Se and used as the transmission sources for assaying 235 U and potential 239 Pu respectively. The calibration experiments using 1 liter solution sample of 192 Ir and 235 U is performed. The standard deviations were obtained for 192 Ir γ rays of 295 keV, 308 keV and 316 keV are +- 0.41%, +- 0.29% and +-0.42% respectively. The standard divination for 235 U 185 keV γ ray is +- 0.62%

Segmented scintillation detectors with silicon photomultiplier readout for measuring antiproton annihilations

CERN Document Server

Sótér, A.; Kobayashi, T.; Barna, D.; Horváth, D.; Hori, M.

2014-01-01

The Atomic Spectroscopy and Collisions Using Slow Antiprotons (ASACUSA) experiment at the Antiproton Decelerator (AD) facility of CERN constructed segmented scintillators to detect and track the charged pions which emerge from antiproton annihilations in a future superconducting radiofrequency Paul trap for antiprotons. A system of 541 cast and extruded scintillator bars were arranged in 11 detector modules which provided a spatial resolution of 17 mm. Green wavelength-shifting fibers were embedded in the scintillators, and read out by silicon photomultipliers which had a sensitive area of 1 x 1 mm^2. The photoelectron yields of various scintillator configurations were measured using a negative pion beam of momentum p ~ 1 GeV/c. Various fibers and silicon photomultipliers, fiber end terminations, and couplings between the fibers and scintillators were compared. The detectors were also tested using the antiproton beam of the AD. Nonlinear effects due to the saturation of the silicon photomultiplier were seen a...

Charged-particle induced radiation damage of a HPGe gamma-ray detector during spaceflight

Energy Technology Data Exchange (ETDEWEB)

Evans, Larry G. [Computer Sciences Corporation, Science Programs, Lanham, MD 20706 (United States); Starr, Richard [The Catholic University of America, Department of Physics, Washington, DC 20064 (United States); Brueckner, Johannes [Max-Planck-Institut fuer Chemie, Mainz (Germany); Boynton, William V. [University of Arizona, Lunar and Planetary Laboratory, Tucson, AZ 85721 (United States); Bailey, S.H. [University of Arizona, Lunar and Planetary Laboratory, Tucson, AZ 85721 (United States); Trombka, J.I. [NASA Goddard Space Flight Center, Code 691, Greenbelt, MD 20771 (United States)

1999-02-11

The Mars Observer spacecraft was launched on September 26, 1992 with a planned arrival at Mars after an 11-month cruise. Among the scientific instruments carried on the spacecraft was a Gamma-Ray Spectrometer (GRS) experiment to measure the composition of Mars. The GRS used a passively cooled high-purity germanium detector for measurements in the 0.2-10 MeV region. The sensor was a closed-end co-axial detector, 5.5 cm diameter by 5.5 cm long, and had an efficiency along its axis of 28% at 1332 keV relative to a standard NaI(Tl) detector. The sensor was surrounded by a thin (0.5 cm) plastic charged-particle shield. This was the first planetary mission to use a cooled Ge detector. It was expected that the long duration in space of three years would cause an increase in the energy resolution of the detector due to radiation damage and could affect the expected science return of the GRS. Shortly before arrival, on August 21, 1993, contact was lost with the spacecraft following the pressurization of the propellent tank for the orbital-insertion rocket motor. During much of the cruise to Mars, the GRS was actively collecting background data. The instrument provided over 1200 h of data collection during periods of both quiescent sun and solar flares. From the charged particle interactions in the shield, the total number of cosmic ray hits on the detector could be determined. The average cosmic ray flux at the MO GRS was about 2.5 cm{sup -2} s{sup -1}. The estimated fluence of charged particles during cruise was about 10{sup 8} particles cm{sup -2} with 31% of these occurring during a single solar proton event of approximately 10 days duration. During cruise, the detector energy resolution determined from a background gamma-ray at 1312 keV degraded from 2.4 keV full-width at half-maximum shortly after launch to 6.4 keV 11 months later. This result agrees well with measurements from ground-based accelerator irradiations (at 1.5 GeV) on a similar size detector.

Optimized digital filtering techniques for radiation detection with HPGe detectors

Energy Technology Data Exchange (ETDEWEB)

Salathe, Marco, E-mail: marco.salathe@mpi-hd.mpg.de; Kihm, Thomas, E-mail: mizzi@mpi-hd.mpg.de

2016-02-01

This paper describes state-of-the-art digital filtering techniques that are part of GEANA, an automatic data analysis software used for the GERDA experiment. The discussed filters include a novel, nonlinear correction method for ballistic deficits, which is combined with one of three shaping filters: a pseudo-Gaussian, a modified trapezoidal, or a modified cusp filter. The performance of the filters is demonstrated with a 762 g Broad Energy Germanium (BEGe) detector, produced by Canberra, that measures γ-ray lines from radioactive sources in an energy range between 59.5 and 2614.5 keV. At 1332.5 keV, together with the ballistic deficit correction method, all filters produce a comparable energy resolution of ~1.61 keV FWHM. This value is superior to those measured by the manufacturer and those found in publications with detectors of a similar design and mass. At 59.5 keV, the modified cusp filter without a ballistic deficit correction produced the best result, with an energy resolution of 0.46 keV. It is observed that the loss in resolution by using a constant shaping time over the entire energy range is small when using the ballistic deficit correction method.

Arrays of Segmented, Tapered Light Guides for Use With Large, Planar Scintillation Detectors

Science.gov (United States)

Raylman, Raymond R.; Vaigneur, Keith; Stolin, Alexander V.; Jaliparthi, Gangadhar

2015-06-01

Metabolic imaging techniques can potentially improve detection and diagnosis of cancer in women with radiodense and/or fibrocystic breasts. Our group has previously developed a high-resolution positron emission tomography imaging and biopsy device (PEM-PET) to detect and guide the biopsy of suspicious breast lesions. Initial testing revealed that the imaging field-of-view (FOV) of the scanner was smaller than the physical size of the detector's active area, which could hinder sampling of breast areas close to the chest wall. The purpose of this work was to utilize segmented, tapered light guides for optically coupling the scintillator arrays to arrays of position-sensitive photomultipliers to increase both the active FOV and identification of individual scintillator elements. Testing of the new system revealed that the optics of these structures made it possible to discern detector elements from the complete active area of the detector face. In the previous system the top and bottom rows and left and right columns were not identifiable. Additionally, use of the new light guides increased the contrast of individual detector elements by up to 129%. Improved element identification led to a spatial resolution increase by approximately 12%. Due to attenuation of light in the light guides the detector energy resolution decreased from 18.5% to 19.1%. Overall, these improvements should increase the field-of-view and spatial resolution of the dedicated breast-PET system.

Recent Results with a segmented Hybrid Photon Detector for a novel parallax-free PET Scanner for Brain Imaging

CERN Document Server

Braem, André; Joram, Christian; Mathot, Serge; Séguinot, Jacques; Weilhammer, Peter; Ciocia, F; De Leo, R; Nappi, E; Vilardi, I; Argentieri, A; Corsi, F; Dragone, A; Pasqua, D

2007-01-01

We describe the design, fabrication and test results of a segmented Hybrid Photon Detector with integrated auto-triggering front-end electronics. Both the photodetector and its VLSI readout electronics are custom designed and have been tailored to the requirements of a recently proposed novel geometrical concept of a Positron Emission Tomograph. Emphasis is laid on the PET specific features of the device. The detector has been fabricated in the photocathode facility at CERN.

Upgrade of the muon veto and current status of the Dortmund low background HPGe facility

Energy Technology Data Exchange (ETDEWEB)

Goessling, Claus; Kroeninger, Kevin; Neddermann, Till; Nitsch, Christian; Quante, Thomas [TU Dortmund, Physik EIV, D-44221 Dortmund (Germany)

2015-07-01

The Dortmund Low Background HPGe Facility (DLB) is a germanium facility with heavy shielding located above ground. It's primary task is to provide material screening support for the COBRA experiment which was built to search for neutrinoless double beta decay. Germanium detectors used for low background gamma spectroscopy are usually operated under either a fairly low overburden (O(1m) water equivalent (mwe)) or high overburden, e.g. in specialised underground laboratories (O(>100 mwe)). In between, only a few facilities exist, such as the DLB. The artificial overburden of 10 mwe already shields the weak component of cosmic rays. The lead castle with a state-of-the-art neutron shielding as well as the active anti-cosmics veto detector enable low background gamma spectrometry with the advantage of good accessibility on the university campus. Throughout the last years improvements have been made especially on the cosmics veto and the MC simulation leading to an remarkable low integral background counting rate (40-2700 keV) of about 2.5228(52) counts/kg/min. The talk summarises the completed tasks and presents the current status.

Reproducibility of multi-detector spiral computed tomography in detection of sub-segmental acute pulmonary embolism

International Nuclear Information System (INIS)

Brunot, S.; Corneloup, O.; Latrabe, V.; Montaudon, M.; Laurent, F.

2005-01-01

The aim of this study was to evaluate the inter-observer and intra-observer agreement of the diagnosis of sub-segmental acute pulmonary embolism (PE) in an inpatient population explored by 16 slice multi-detector spiral computed tomography (MDCT). Four hundred consecutive inpatients were referred for MDCT for the clinical suspicion of acute PE. One hundred and seventy seven (44.2%) had a known cardio-respiratory disease at the time of examination. Inter-observer and intra-observer agreements for the diagnosis of acute PE and of sub-segmental acute PE were assessed blind and independently by three experienced readers and by kappa statistics. Seventy-five patients were diagnosed as having acute PE findings (19.5%), and clots were located exclusively within sub-segmental arteries in nine patients (12%). When clots were limited to sub-segmental or more distal branches of the pulmonary arteries, kappa values were found to be moderate (0.56) to very good (0.85) for the diagnosis of sub-segmental acute PE, whereas for the diagnosis of acute PE in the whole population, kappa values ranged from 0.84 to 0.97. Intra-observer agreement was found to be perfect (kappa=1). MDCT is a reproducible technique for the diagnosis of sub-segmental acute PE as well as for acute PE. In this inpatient population, sub-segmental acute PE was not a rare event. (orig.)

High performance p-i-n CdTe and CdZnTe detectors

CERN Document Server

Khusainov, A K; Ilves, A G; Morozov, V F; Pustovoit, A K; Arlt, R D

1999-01-01

A breakthrough in the performance of p-i-n CdTe and CdZnTe detectors is reported. The detector stability has been significantly improved, allowing their use in precise gamma and XRF applications. Detectors with energy resolution close to Si and Ge were produced operating with only -30--35 deg. C cooling (by a Peltier cooler of 15x15x10 mm size and a consumed power less than 5 W). Presently detectors with volume of up to 300 mm sup 3 are available. In terms of photoelectric effect efficiency it corresponds to HPGe detectors with volumes of about 1.5 cm sup 3. The possibilities of further improvement of CdTe and CdZnTe detector characteristics are discussed in this paper.

Monte Carlo simulation of gamma-ray interactions in an over-square high-purity germanium detector for in-vivo measurements

Science.gov (United States)

Saizu, Mirela Angela

2016-09-01

The developments of high-purity germanium detectors match very well the requirements of the in-vivo human body measurements regarding the gamma energy ranges of the radionuclides intended to be measured, the shape of the extended radioactive sources, and the measurement geometries. The Whole Body Counter (WBC) from IFIN-HH is based on an “over-square” high-purity germanium detector (HPGe) to perform accurate measurements of the incorporated radionuclides emitting X and gamma rays in the energy range of 10 keV-1500 keV, under conditions of good shielding, suitable collimation, and calibration. As an alternative to the experimental efficiency calibration method consisting of using reference calibration sources with gamma energy lines that cover all the considered energy range, it is proposed to use the Monte Carlo method for the efficiency calibration of the WBC using the radiation transport code MCNP5. The HPGe detector was modelled and the gamma energy lines of 241Am, 57Co, 133Ba, 137Cs, 60Co, and 152Eu were simulated in order to obtain the virtual efficiency calibration curve of the WBC. The Monte Carlo method was validated by comparing the simulated results with the experimental measurements using point-like sources. For their optimum matching, the impact of the variation of the front dead layer thickness and of the detector photon absorbing layers materials on the HPGe detector efficiency was studied, and the detector’s model was refined. In order to perform the WBC efficiency calibration for realistic people monitoring, more numerical calculations were generated simulating extended sources of specific shape according to the standard man characteristics.

Methods for fitting of efficiency curves obtained by means of HPGe gamma rays spectrometers; Metodos de ajuste de curvas de eficiencia obtidas por meio de espectrometros de HPGe

Energy Technology Data Exchange (ETDEWEB)

Cardoso, Vanderlei

2002-07-01

The present work describes a few methodologies developed for fitting efficiency curves obtained by means of a HPGe gamma-ray spectrometer. The interpolated values were determined by simple polynomial fitting and polynomial fitting between the ratio of experimental peak efficiency and total efficiency, calculated by Monte Carlo technique, as a function of gamma-ray energy. Moreover, non-linear fitting has been performed using a segmented polynomial function and applying the Gauss-Marquardt method. For the peak area obtainment different methodologies were developed in order to estimate the background area under the peak. This information was obtained by numerical integration or by using analytical functions associated to the background. One non-calibrated radioactive source has been included in the curve efficiency in order to provide additional calibration points. As a by-product, it was possible to determine the activity of this non-calibrated source. For all fittings developed in the present work the covariance matrix methodology was used, which is an essential procedure in order to give a complete description of the partial uncertainties involved. (author)

High Purity Germanium Detector as part of Health Canada's Mobile Nuclear Laboratory

Energy Technology Data Exchange (ETDEWEB)

Stocki, Trevor J.; Bouchard, Claude; Rollings, John; Boudreau, Marc-Oliver; McCutcheon- Wickham, Rory; Bergman, Lauren [Radiation Protection Bureau, Health Canada, AL6302D, 775 Brookfield Road, Ottawa, K1A 0K9 (Canada)

2014-07-01

In the event of a nuclear emergency on Canadian soil, Health Canada has designed and equipped two Mobile Nuclear Labs (MNLs) which can be deployed near a radiological accident site to provide radiological measurement capabilities. These measurements would help public authorities to make informed decisions for radiation protection recommendations. One of the MNLs has been outfitted with a High Purity Germanium (HPGe) detector within a lead castle, which can be used for identification as well as quantification of gamma emitting radioisotopes in contaminated soil, water, and other samples. By spring 2014, Health Canada's second MNL will be equipped with a similar detector to increase sample analysis capacity and also provide redundancy if one of the detectors requires maintenance. The Mobile Nuclear Lab (MNL) with the HPGe detector has been successfully deployed in the field for various exercises. One of these field exercises was a dirty bomb scenario where an unknown radioisotope required identification. A second exercise was an inter-comparison between the measurements of spiked soil and water samples, by two field teams and a certified laboratory. A third exercise was the deployment of the MNL as part of a full scale nuclear exercise simulating an emergency at a Canadian nuclear power plant. The lessons learned from these experiences will be discussed. (authors)

First results on the charge collection properties of segmented detectors made with p-type bulk silicon

International Nuclear Information System (INIS)

Casse, G.; Allport, P.P.; Bowcock, T.J.V.; Greenall, A.; Hanlon, M.; Jackson, J.N.

2002-01-01

Radiation damage of n-type bulk detectors introduces stable defects acting as effective p-type doping and leads to the change of the conductivity type of the silicon substrate (type inversion) after a fluence of a few times 10 13 protons cm -2 . The diode junction after inversion migrates from the original side to the back plane of the detector. The migration of the junction can be prevented using silicon detectors with p-type substrates. Furthermore, the use of n-side readout gives higher charge collection efficiency for segmented devices operated below the full depletion voltage. Large area (∼6.4x6.4 cm 2 ) capacitively coupled 80 μm pitch detectors using polysilicon bias resistors have been fabricated on p-type substrates (n-in-p diode structure). These detectors have been irradiated with 24 GeV/c protons to an integrated fluence of 3x10 14 cm -2 and kept for 7 days at 25 deg. C to reach the broad minimum of the annealing curve. Results are presented on the comparison of their charge collection properties with detectors using p-strip read-out after corresponding dose and annealing

Study of the γ decay of high-lying states in 208Pb via inelastic scattering of 17O ions

Directory of Open Access Journals (Sweden)

Crespi F.C.L.

2014-03-01

Full Text Available A measurement of the high-lying states in 208Pb has been made using 17O beams at 20 MeV/u. The gamma decay following inelastic excitation was measured with the detector system AGATA Demonstrator based on segmented HPGe detectors, coupled to an array of large volume LaBr3:Ce scintillators and to an array of Si detectors. Preliminary results in comparison with (γ,γ’ data, for states in the 5-8 MeV energy interval, are presented.

Accounting for segment correlations in segmented gamma-ray scans

International Nuclear Information System (INIS)

Sheppard, G.A.; Prettyman, T.H.; Piquette, E.C.

1994-01-01

In a typical segmented gamma-ray scanner (SGS), the detector's field of view is collimated so that a complete horizontal slice or segment of the desired thickness is visible. Ordinarily, the collimator is not deep enough to exclude gamma rays emitted from sample volumes above and below the segment aligned with the collimator. This can lead to assay biases, particularly for certain radioactive-material distributions. Another consequence of the collimator's low aspect ratio is that segment assays at the top and bottom of the sample are biased low because the detector's field of view is not filled. This effect is ordinarily countered by placing the sample on a low-Z pedestal and scanning one or more segment thicknesses below and above the sample. This takes extra time, however, We have investigated a number of techniques that both account for correlated segments and correct for end effects in SGS assays. Also, we have developed an algorithm that facilitates estimates of assay precision. Six calculation methods have been compared by evaluating the results of thousands of simulated, assays for three types of gamma-ray source distribution and ten masses. We will report on these computational studies and their experimental verification

Characterisation of the SmartPET planar Germanium detectors

Energy Technology Data Exchange (ETDEWEB)

Boston, H.C. [Department of Physics, University of Liverpool, Oliver Lodge Laboratory, Liverpool L69 7ZE (United Kingdom)], E-mail: H.C.Boston@liverpool.ac.uk; Boston, A.J.; Cooper, R.J.; Cresswell, J.; Grint, A.N.; Mather, A.R.; Nolan, P.J.; Scraggs, D.P.; Turk, G. [Department of Physics, University of Liverpool, Oliver Lodge Laboratory, Liverpool L69 7ZE (United Kingdom); Hall, C.J.; Lazarus, I. [CCLRC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Berry, A.; Beveridge, T.; Gillam, J.; Lewis, R. [School of Physics and Materials Engineering, Monash University, Melbourne (Australia)

2007-08-21

Small Animal Reconstruction PET (SmartPET) is a project funded by the UK medical research council (MRC) to demonstrate proof of principle that Germanium can be utilised in Positron Emission Tomography (PET). The SmartPET demonstrator consists of two orthogonal strip High Purity Germanium (HPGe) planar detectors manufactured by ORTEC. The aim of the project is to produce images of an internal source with sub mm{sup 3} spatial resolution. Before this image can be achieved the detectors have to be fully characterised to understand the response at any given location to a {gamma}-ray interaction. This has been achieved by probing the two detectors at a number of specified points with collimated sources of various energies and strengths. A 1 mm diameter collimated beam of photons was raster scanned in 1 mm steps across the detector. Digital pulse shape data were recorded from all the detector channels and the performance of the detector for energy and position determination has been assessed. Data will be presented for the first SmartPET detector.

Determination of absolute detection efficiencies for detectors of interest in homeland security

International Nuclear Information System (INIS)

Ayaz-Maierhafer, Birsen; DeVol, Timothy A.

2007-01-01

The absolute total and absolute peak detection efficiencies of gamma ray detector materials NaI:Tl, CdZnTe, HPGe, HPXe, LaBr 3 :Ce and LaCl 3 :Ce were simulated and compared to that of polyvinyltoluene (PVT). The dimensions of the PVT detector were 188.82 cmx60.96 cmx5.08 cm, which is a typical size for a single-panel portal monitor. The absolute total and peak detection efficiencies for these detector materials for the point, line and spherical source geometries of 60 Co (1332 keV), 137 Cs (662 keV) and 241 Am (59.5 keV) were simulated at various source-to-detector distances using the Monte Carlo N-Particle software (MCNP5-V1.30). The comparison of the absolute total detection efficiencies for a point, line and spherical source geometry of 60 Co and 137 Cs at different source-to-detector distance showed that the absolute detection efficiency for PVT is higher relative to the other detectors of typical dimensions for that material. However, the absolute peak detection efficiency of some of these detectors are higher relative to PVT, for example the absolute peak detection efficiency of NaI:Tl (7.62 cm diameterx7.62 cm long), HPGe (7.62 cm diameterx7.62 cm long), HPXe (11.43 cm diameterx60.96 cm long), and LaCl 3 :Ce (5.08 cm diameterx5.08 cm long) are all greater than that of a 188.82 cmx60.96 cmx5.08 cm PVT detector for 60 Co and 137 Cs for all geometries studied. The absolute total and absolute peak detection efficiencies of a right circular cylinder of NaI:Tl with various diameters and thicknesses were determined for a point source. The effect of changing the solid angle on the NaI:Tl detectors showed that with increasing solid angle and detector thickness, the absolute efficiency increases. This work establishes a common basis for differentiating detector materials for passive portal monitoring of gamma ray radiation

A simple semi-empirical way of accounting for the contribution of pair production process to the efficiency of Ge detectors

International Nuclear Information System (INIS)

Sudarshan, M.; Singh, R.

1991-01-01

By considering the data for a 38cm 3 Ge(Li) detector from E γ = 319.80 to 2598.80 keV, and for a 68 cm 3 HPGe detector from E γ = 223.430 to 3253.610 keV, it has been demonstrated that the contribution of the pair production process to the full energy peak efficiency (FEPE) of germanium detectors can be quite adequately accounted for in a semi-empirical way. (author)

Spectroscopic Imaging Using Ge and CdTe Based Detector Systems for Hard X-ray Applications

Science.gov (United States)

Astromskas, Vytautas

Third generation synchrotron facilities such as the Diamond Light Source (DLS) have a wide range of experiments performed for a wide range of science fields. The DLS operates at energies up to 150 keV which introduces great challenges to radiation detector technology. This work focuses on the requirements that the detector technology faces for X-ray Absorption Fine Structure (XAFS) and powder diffraction experiments in I12 and I15 beam lines, respectively. A segmented HPGe demonstrator detector with in-built charge sensitive CUBE preamplifiers and a Schottky e- collection CdTe Medipix3RX detector systems were investigated to understand the underlying mechanisms that limit spectroscopic, imaging performances and stability and to find ways to overcome or minimise those limitations. The energy resolution and stability of the Ge demonstrator detector was found to have the required characteristics for XAFS measurements. Charge sharing was identified as a limiting factor to the resolution which is going to be addressed in the future development of a full detector system as well as reductions in electronic noise and cross-talk effects. The stability study of the Schottky CdTe Medipix3RX detector showed that polarization is highly dependent on temperature, irradiation duration and incoming flux. A new pixel behaviour called tri-phase (3-P) pixel was identified and a novel method for determining optimum operational conditions was developed. The use of the 3-P pixels as a criterion for depolarization resulted in a stable performance of the detector. Furthermore, the detector was applied in powder diffraction measurement at the I15 beam line and resulted in the detector diffraction pattern matching the simulated data. CdTe Medipix3RX and HEXITEC spectroscopic imaging detectors were applied in identification and discrimination of transitional metals for security application and K-edge subtraction for medical applications. The results showed that both detectors have potential

Simulation for photon detection in spectrometric system of high purity (HPGe) using MCNPX code

International Nuclear Information System (INIS)

Correa, Guilherme Jorge de Souza

2013-01-01

The Brazilian National Commission of Nuclear Energy defines parameters for classification and management of radioactive waste in accordance with the activity of materials. The efficiency of a detection system is crucial to determine the real activity of a radioactive source. When it's possible, the system's calibration should be performed using a standard source. Unfortunately, there are only a few cases that it can be done this way, considering the difficulty of obtaining appropriate standard sources for each type of measurement. So, computer simulations can be performed to assist in calculating of the efficiency of the system and, consequently, also auxiliary the classification of radioactive waste. This study aims to model a high purity germanium (HPGe) detector with MCNPX code, approaching the spectral values computationally obtained of the values experimentally obtained for the photopeak of 137 Cs. The approach will be made through changes in outer dead layer of the germanium crystal modeled. (author)

Experimental test of the background rejection, through imaging capability, of a highly segmented AGATA germanium detector

International Nuclear Information System (INIS)

Doncel, M.; Recchia, F.; Quintana, B.; Gadea, A.; Farnea, E.

2010-01-01

The development of highly segmented germanium detectors as well as the algorithms to identify the position of the interaction within the crystal opens the possibility to locate the γ-ray source using Compton imaging algorithms. While the Compton-suppression shield, coupled to the germanium detector in conventional arrays, works also as an active filter against the γ rays originated outside the target, the new generation of position sensitive γ-ray detector arrays has to fully rely on tracking capabilities for this purpose. In specific experimental conditions, as the ones foreseen at radioactive beam facilities, the ability to discriminate background radiation improves the sensitivity of the gamma spectrometer. In this work we present the results of a measurement performed at the Laboratori Nazionali di Legnaro (LNL) aiming the evaluation of the AGATA detector capabilities to discriminate the origin of the γ rays on an event-by-event basis. It will be shown that, exploiting the Compton scattering formula, it is possible to track back γ rays coming from different positions, assigning them to specific emitting locations. These imaging capabilities are quantified for a single crystal AGATA detector.

High-resolution gamma-ray measurement systems using a compact electro- mechanically cooled detector system and intelligent software

International Nuclear Information System (INIS)

Buckley, W.M.; Carlson, J.B.; Neufeld, K.W.

1995-01-01

Obtaining high-resolution gamma-ray measurements using high-purity germanium (HPGe) detectors in the field has been of limited practicality due to the need to use and maintain a supply of liquid nitrogen (LN 2 ). This same constraint limits high-resolution gamma measurements in unattended safeguards or treaty Verification applications. We are developing detectors and software to greatly extend the applicability of high-resolution germanium-based measurements for these situations

BEGe detectors in GERDA Phase I - performance, physics analysis and surface events

Energy Technology Data Exchange (ETDEWEB)

Lazzaro, Andrea [Physik-Department E15, Technische Universitaet Muenchen (Germany); Collaboration: GERDA-Collaboration

2014-07-01

The Phase I of the Gerda experiment, which has concluded its data taking in Summer 2013, was based on coaxial HPGe detectors already used for IGEX and HdM experiments. In the upcoming Phase II customized Broad Energy Germanium (BEGe) detectors will provide the major contribution to the total exposure. The first set of BEGe detectors has been deployed in Gerda since June 2012. The data collected in Phase I show the performance achieved in terms of spectroscopy and pulse shape discrimination. In particular the strongest background source, the {sup 42}K beta decay from the liquid argon surrounding the detectors, has been effectively rejected. The signals due to beta decay on the detector surface are indeed characterized by a longer charge collection time. This talk focuses on this key feature of the BEGe-PSD.

Theoretical analysis of the effect of charge-sharing on the Detective Quantum Efficiency of single-photon counting segmented silicon detectors

Energy Technology Data Exchange (ETDEWEB)

Marchal, J [Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom)], E-mail: julien.marchal@diamond.ac.uk

2010-01-15

A detector cascaded model is proposed to describe charge-sharing effect in single-photon counting segmented silicon detectors. Linear system theory is applied to this cascaded model in order to derive detector performance parameters such as large-area gain, presampling Modulation Transfer Function (MTF), Noise Power Spectrum (NPS) and Detective Quantum Efficiency (DQE) as a function of energy detection threshold. This theory is used to model one-dimensional detectors (i.e. strip detectors) where X-ray-generated charge can be shared between two sampling elements, but the concepts developed in this article can be generalized to two-dimensional arrays of detecting elements (i.e. pixels detectors). The zero-frequency DQE derived from this model is consistent with expressions reported in the literature using a different method. The ability of this model to simulate the effect of charge sharing on image quality in the spatial frequency domain is demonstrated by applying it to a hypothetical one-dimensional single-photon counting detector illuminated with a typical mammography spectrum.

18F half-life measurement using a high-purity germanium detector

International Nuclear Information System (INIS)

Han, Jubong; Lee, K.B.; Park, T.S.; Lee, J.M.; Oh, P.J.; Lee, S.H.; Kang, Y.S.; Ahn, J.K.

2012-01-01

The half-life of 18 F has been measured using HPGe detectors with a 137 Cs reference source. The counting ratio of 511 keV γ-rays from 18 F to 622 keV γ-rays from 137 Cs was fitted for the half-life with a weighted least-square method. Uncertainties due to the systematic effects arising from the measurement of a high activity 18 F source were studied in detail. The half-life of 18 F was found to be (109.72±0.19) min. The result is in a good agreement with the recommended value of (109.728±0.019) min evaluated at the Laborotaire National Henri Becquerel (LNHB). - Highlights: ► The 18 F half-life was measured with a reference source and without it using HPGe detectors. ► We found the systematic effect ‘activity dynamic range effect’ by monitoring the counts of the reference source. ► This activity dynamic range effect was corrected by using the reference source method. ► The 18 F half-life using the reference source method was in a good agreement with the recommended value of LNHB.

Experimental study on the CsI (Tl) crystal anti-compton detector in CDEX

International Nuclear Information System (INIS)

Liu Shukui; Yue Qian; Tang Changjian

2012-01-01

CDEX (China Dark matter Experiment) Collaboration will carry out direct search for dark matter with Ultra-Low Energy Threshold High Purity germanium (ULE-HPGe) detector at CJPL (China Jinping deep underground Laboratory). Before underground research, some experiments of the CsI (Tl) crystal Anti-Compton detector have been done on the ground, including light guide choice, wrapping material choice, height uniformity of CsI (Tl) crystal, side uniformity of CsI (Tl) crystal and the test results of all the crystals. Through the preliminary work on the ground, we have got some knowledge of the anti-compton detector and prepared for the underground experiment. (authors)

The Simulation of Energy Distribution of Electrons Detected by Segmental Ionization Detector in High Pressure Conditions of ESEM

Czech Academy of Sciences Publication Activity Database

Neděla, Vilém; Konvalina, Ivo; Oral, Martin; Hudec, Jiří

2015-01-01

Roč. 21, S4 (2015), s. 264-269 ISSN 1431-9276 R&D Projects: GA ČR(CZ) GA14-22777S Institutional support: RVO:68081731 Keywords : electron-gas interactions * Monte Carlo simulation * signal amplification * segmented ionization detector Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.730, year: 2015

Monte Carlo based geometrical model for efficiency calculation of an n-type HPGe detector

Energy Technology Data Exchange (ETDEWEB)

Padilla Cabal, Fatima, E-mail: fpadilla@instec.c [Instituto Superior de Tecnologias y Ciencias Aplicadas, ' Quinta de los Molinos' Ave. Salvador Allende, esq. Luaces, Plaza de la Revolucion, Ciudad de la Habana, CP 10400 (Cuba); Lopez-Pino, Neivy; Luis Bernal-Castillo, Jose; Martinez-Palenzuela, Yisel; Aguilar-Mena, Jimmy; D' Alessandro, Katia; Arbelo, Yuniesky; Corrales, Yasser; Diaz, Oscar [Instituto Superior de Tecnologias y Ciencias Aplicadas, ' Quinta de los Molinos' Ave. Salvador Allende, esq. Luaces, Plaza de la Revolucion, Ciudad de la Habana, CP 10400 (Cuba)

2010-12-15

A procedure to optimize the geometrical model of an n-type detector is described. Sixteen lines from seven point sources ({sup 241}Am, {sup 133}Ba, {sup 22}Na, {sup 60}Co, {sup 57}Co, {sup 137}Cs and {sup 152}Eu) placed at three different source-to-detector distances (10, 20 and 30 cm) were used to calibrate a low-background gamma spectrometer between 26 and 1408 keV. Direct Monte Carlo techniques using the MCNPX 2.6 and GEANT 4 9.2 codes, and a semi-empirical procedure were performed to obtain theoretical efficiency curves. Since discrepancies were found between experimental and calculated data using the manufacturer parameters of the detector, a detail study of the crystal dimensions and the geometrical configuration is carried out. The relative deviation with experimental data decreases from a mean value of 18-4%, after the parameters were optimized.

Ultra low energy-ultra low background high purity germanium detectors for studies on dark matter

International Nuclear Information System (INIS)

Soma, A.K.; Singh, V.; Singh, L.; Singh, M.K.; Wong, H.T.

2009-01-01

Weakly Interacting Massive Particles (WIMP) are the leading DM candidates. Super symmetric particles (SUSY) are one of the leading WIMP candidates. To probe this least explored region Taiwan EXperiments On NeutrinO collaboration is pursuing research and development program by using High Purity Germanium detectors (HPGe). These detectors offer a matured technology to scale up the detectors and achieve sub-keV level threshold i.e. few hundreds of eV, economically. The various detectors developed by the collaboration is shown in the below figure. The current goal of the collaboration is to develop detectors of kg-scale target mass, ∼100 eV threshold and low-background specification for the studies on WIMPs, μ v and neutrino - nucleus coherent scattering

Performance of a compact multi-crystal high-purity germanium detector array for measuring coincident gamma-ray emissions

Energy Technology Data Exchange (ETDEWEB)

Howard, Chris; Daigle, Stephen; Buckner, Matt [University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Erikson, Luke E.; Runkle, Robert C. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Stave, Sean C., E-mail: Sean.Stave@pnnl.gov [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Champagne, Arthur E.; Cooper, Andrew; Downen, Lori [University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Glasgow, Brian D. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Kelly, Keegan; Sallaska, Anne [University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States)

2015-05-21

The Multi-sensor Airborne Radiation Survey (MARS) detector is a 14-crystal array of high-purity germanium (HPGe) detectors housed in a single cryostat. The array was used to measure the astrophysical S-factor for the {sup 14}N(p,γ){sup 15}O{sup ⁎} reaction for several transition energies at an effective center-of-mass energy of 163 keV. Owing to the granular nature of the MARS detector, the effect of gamma-ray summing was greatly reduced in comparison to past experiments which utilized large, single-crystal detectors. The new S-factor values agree within their uncertainties with the past measurements. Details of the analysis and detector performance are presented.

Methods for fitting of efficiency curves obtained by means of HPGe gamma rays spectrometers

International Nuclear Information System (INIS)

Cardoso, Vanderlei

2002-01-01

The present work describes a few methodologies developed for fitting efficiency curves obtained by means of a HPGe gamma-ray spectrometer. The interpolated values were determined by simple polynomial fitting and polynomial fitting between the ratio of experimental peak efficiency and total efficiency, calculated by Monte Carlo technique, as a function of gamma-ray energy. Moreover, non-linear fitting has been performed using a segmented polynomial function and applying the Gauss-Marquardt method. For the peak area obtainment different methodologies were developed in order to estimate the background area under the peak. This information was obtained by numerical integration or by using analytical functions associated to the background. One non-calibrated radioactive source has been included in the curve efficiency in order to provide additional calibration points. As a by-product, it was possible to determine the activity of this non-calibrated source. For all fittings developed in the present work the covariance matrix methodology was used, which is an essential procedure in order to give a complete description of the partial uncertainties involved. (author)

Proportional crosstalk correction for the segmented clover at iThemba LABS

International Nuclear Information System (INIS)

Bucher, T D; Noncolela, S P; Lawrie, E A; Dinoko, T R S; Easton, J L; Erasmus, N; Lawrie, J J; Mthembu, S H; Mtshali, W X; Shirinda, O; Orce, J N

2017-01-01

Reaching new depths in nuclear structure investigations requires new experimental equipment and new techniques of data analysis. The modern γ -ray spectrometers, like AGATA and GRETINA are now built of new-generation segmented germanium detectors. These most advanced detectors are able to reconstruct the trajectory of a γ -ray inside the detector. These are powerful detectors, but they need careful characterization, since their output signals are more complex. For instance for each γ -ray interaction that occurs in a segment of such a detector additional output signals (called proportional crosstalk), falsely appearing as an independent (often negative) energy depositions, are registered on the non-interacting segments. A failure to implement crosstalk correction results in incorrectly measured energies on the segments for two- and higher-fold events. It affects all experiments which rely on the recorded segment energies. Furthermore incorrectly recorded energies on the segments cause a failure to reconstruct the γ -ray trajectories using Compton scattering analysis. The proportional crosstalk for the iThemba LABS segmented clover was measured and a crosstalk correction was successfully implemented. The measured crosstalk-corrected energies show good agreement with the true γ -ray energies independent on the number of hit segments and an improved energy resolution for the segment sum energy was obtained. (paper)

Metrological tests of a 200 L calibration source for HPGE detector systems for assay of radioactive waste drums.

Science.gov (United States)

Boshkova, T; Mitev, K

2016-03-01

In this work we present test procedures, approval criteria and results from two metrological inspections of a certified large volume (152)Eu source (drum about 200L) intended for calibration of HPGe gamma assay systems used for activity measurement of radioactive waste drums. The aim of the inspections was to prove the stability of the calibration source during its working life. The large volume source was designed and produced in 2007. It consists of 448 identical sealed radioactive sources (modules) apportioned in 32 transparent plastic tubes which were placed in a wooden matrix which filled the drum. During the inspections the modules were subjected to tests for verification of their certified characteristics. The results show a perfect compliance with the NIST basic guidelines for the properties of a radioactive certified reference material (CRM) and demonstrate the stability of the large volume CRM-drum after 7 years of operation. Copyright © 2015 Elsevier Ltd. All rights reserved.

A region segmentation based algorithm for building a crystal position lookup table in a scintillation detector

International Nuclear Information System (INIS)

Wang Haipeng; Fan Xin; Yun Mingkai; Liu Shuangquan; Cao Xuexiang; Chai Pei; Shan Baoci

2015-01-01

In a scintillation detector, scintillation crystals are typically made into a 2-dimensional modular array. The location of incident gamma-ray needs be calibrated due to spatial response nonlinearity. Generally, position histograms-the characteristic flood response of scintillation detectors-are used for position calibration. In this paper, a position calibration method based on a crystal position lookup table which maps the inaccurate location calculated by Anger logic to the exact hitting crystal position has been proposed. Firstly, the position histogram is preprocessed, such as noise reduction and image enhancement. Then the processed position histogram is segmented into disconnected regions, and crystal marking points are labeled by finding the centroids of regions. Finally, crystal boundaries are determined and the crystal position lookup table is generated. The scheme is evaluated by the whole-body positron emission tomography (PET) scanner and breast dedicated single photon emission computed tomography scanner developed by the Institute of High Energy Physics, Chinese Academy of Sciences. The results demonstrate that the algorithm is accurate, efficient, robust and applicable to any configurations of scintillation detector. (authors)

Spectrum correction algorithm for detectors in airborne radioactivity monitoring equipment NH-UAV based on a ratio processing method

International Nuclear Information System (INIS)

Cao, Ye; Tang, Xiao-Bin; Wang, Peng; Meng, Jia; Huang, Xi; Wen, Liang-Sheng; Chen, Da

2015-01-01

The unmanned aerial vehicle (UAV) radiation monitoring method plays an important role in nuclear accidents emergency. In this research, a spectrum correction algorithm about the UAV airborne radioactivity monitoring equipment NH-UAV was studied to measure the radioactive nuclides within a small area in real time and in a fixed place. The simulation spectra of the high-purity germanium (HPGe) detector and the lanthanum bromide (LaBr 3 ) detector in the equipment were obtained using the Monte Carlo technique. Spectrum correction coefficients were calculated after performing ratio processing techniques about the net peak areas between the double detectors on the detection spectrum of the LaBr 3 detector according to the accuracy of the detection spectrum of the HPGe detector. The relationship between the spectrum correction coefficient and the size of the source term was also investigated. A good linear relation exists between the spectrum correction coefficient and the corresponding energy (R 2 =0.9765). The maximum relative deviation from the real condition reduced from 1.65 to 0.035. The spectrum correction method was verified as feasible. - Highlights: • An airborne radioactivity monitoring equipment NH-UAV was developed to measure radionuclide after a nuclear accident. • A spectrum correction algorithm was proposed to obtain precise information on the detected radioactivity within a small area. • The spectrum correction method was verified as feasible. • The corresponding spectrum correction coefficients increase first and then stay constant

Spectrum correction algorithm for detectors in airborne radioactivity monitoring equipment NH-UAV based on a ratio processing method

Energy Technology Data Exchange (ETDEWEB)

Cao, Ye [Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Tang, Xiao-Bin, E-mail: tangxiaobin@nuaa.edu.cn [Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Jiangsu Key Laboratory of Nuclear Energy Equipment Materials Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Wang, Peng; Meng, Jia; Huang, Xi; Wen, Liang-Sheng [Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Chen, Da [Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Jiangsu Key Laboratory of Nuclear Energy Equipment Materials Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

2015-10-11

The unmanned aerial vehicle (UAV) radiation monitoring method plays an important role in nuclear accidents emergency. In this research, a spectrum correction algorithm about the UAV airborne radioactivity monitoring equipment NH-UAV was studied to measure the radioactive nuclides within a small area in real time and in a fixed place. The simulation spectra of the high-purity germanium (HPGe) detector and the lanthanum bromide (LaBr{sub 3}) detector in the equipment were obtained using the Monte Carlo technique. Spectrum correction coefficients were calculated after performing ratio processing techniques about the net peak areas between the double detectors on the detection spectrum of the LaBr{sub 3} detector according to the accuracy of the detection spectrum of the HPGe detector. The relationship between the spectrum correction coefficient and the size of the source term was also investigated. A good linear relation exists between the spectrum correction coefficient and the corresponding energy (R{sup 2}=0.9765). The maximum relative deviation from the real condition reduced from 1.65 to 0.035. The spectrum correction method was verified as feasible. - Highlights: • An airborne radioactivity monitoring equipment NH-UAV was developed to measure radionuclide after a nuclear accident. • A spectrum correction algorithm was proposed to obtain precise information on the detected radioactivity within a small area. • The spectrum correction method was verified as feasible. • The corresponding spectrum correction coefficients increase first and then stay constant.

Electrical Signal Path Study and Component Assay for the MAJORANA N-Type Segmented Contact Detector

International Nuclear Information System (INIS)

Amman, Mark; Bergevin, Marc; Chan, Yuen-Dat; Detwiler, Jason A.; Fujikawa, Brian; Lesko, Kevin T.; Luke, Paul N.; Prior, Gersende; Poon, Alan W.; Smith, Alan R.; Vetter, Kai; Yaver, Harold; Zimmermann, Sergio

2009-01-01

The purpose of the present electrical signal path study is to explore the various issues related to the deployment of highly-segmented low-background Ge detectors for the MAJORANA double-beta decay experiment. A significant challenge is to simultaneously satisfy competing requirements for the mechanical design, electrical readout performance, and radiopurity specifications from the MAJORANA project. Common to all rare search experiments, there is a very stringent limit on the acceptable radioactivity level of all the electronics components involved. Some of the findings are summarized in this report.

Electrical Signal Path Study and Component Assay for the MAJORANA N-Type Segmented Contact Detector

Energy Technology Data Exchange (ETDEWEB)

Amman, Mark; Bergevin, Marc; Chan, Yuen-Dat; Detwiler, Jason A.; Fujikawa, Brian .; Lesko, Kevin T.; Luke, Paul N.; Prior, Gersende; Poon, Alan W.; Smith, Alan R.; Vetter, Kai; Yaver, Harold; Zimmermann, Sergio

2009-02-24

The purpose of the present electrical signal path study is to explore the various issues related to the deployment of highly-segmented low-background Ge detectors for the MAJORANA double-beta decay experiment. A significant challenge is to simultaneously satisfy competing requirements for the mechanical design, electrical readout performance, and radiopurity specifications from the MAJORANA project. Common to all rare search experiments, there is a very stringent limit on the acceptable radioactivity level of all the electronics components involved. Some of the findings are summarized in this report.

Gamma-Ray Spectroscopy at TRIUMF-ISAC: the New Frontier of Radioactive Ion Beam Research

Science.gov (United States)

Ball, G. C.; Andreoiu, C.; Austin, R. A. E.; Bandyopadhyay, D.; Becker, J. A.; Bricault, P.; Brown, N.; Chan, S.; Churchman, R.; Colosimo, S.; Coombes, H.; Cross, D.; Demand, G.; Drake, T. E.; Dombsky, M.; Ettenauer, S.; Finlay, P.; Furse, D.; Garnsworthy, A.; Garrett, P. E.; Green, K. L.; Grinyer, G. F.; Hyland, B.; Hackman, G.; Kanungo, R.; Kulp, W. D.; Lassen, J.; Leach, K. G.; Leslie, J. R.; Mattoon, C.; Melconian, D.; Morton, A. C.; Pearson, C. J.; Phillips, A. A.; Rand, E.; Sarazin, F.; Svensson, C. E.; Sumithrarachchi, S.; Schumaker, M. A.; Triambak, S.; Waddington, J. C.; Walker, P. M.; Williams, S. J.; Wood, J. L.; Wong, J.; Zganjar, E. F.

2009-03-01

High-resolution gamma-ray spectroscopy is essential to fully exploit the unique scientific opportunities at the next generation radioactive ion beam facilities such as the TRIUMF Isotope Separator and Accelerator (ISAC). At ISAC the 8π spectrometer and its associated auxiliary detectors is optimize for β-decay studies while TIGRESS an array of segmented clover HPGe detectors has been designed for studies with accelerated beams. This paper gives a brief overview of these facilities and also presents recent examples of the diverse experimental program carried out at the 8π spectrometer.

Semiconductor detectors with proximity signal readout

International Nuclear Information System (INIS)

Asztalos, Stephen J.

2012-01-01

Semiconductor-based radiation detectors are routinely used for the detection, imaging, and spectroscopy of x-rays, gamma rays, and charged particles for applications in the areas of nuclear and medical physics, astrophysics, environmental remediation, nuclear nonproliferation, and homeland security. Detectors used for imaging and particle tracking are more complex in that they typically must also measure the location of the radiation interaction in addition to the deposited energy. In such detectors, the position measurement is often achieved by dividing or segmenting the electrodes into many strips or pixels and then reading out the signals from all of the electrode segments. Fine electrode segmentation is problematic for many of the standard semiconductor detector technologies. Clearly there is a need for a semiconductor-based radiation detector technology that can achieve fine position resolution while maintaining the excellent energy resolution intrinsic to semiconductor detectors, can be fabricated through simple processes, does not require complex electrical interconnections to the detector, and can reduce the number of required channels of readout electronics. Proximity electrode signal readout (PESR), in which the electrodes are not in physical contact with the detector surface, satisfies this need

Compton suppression system at Penn State Radiation Science and Engineering Center

International Nuclear Information System (INIS)

Cetiner, N.Oe.; Uenlue, K.; Brenizer, J.S.

2008-01-01

A Compton suppression system is used to reduce the contribution of scattered gamma-rays that originate within the HPGe detector to the gamma ray spectrum. The HPGe detector is surrounded by an assembly of guard detectors, usually NaI(Tl). The HPGe and NaI(Tl) detectors are operated in anti-coincidence mode. The NaI(Tl) guard detector detects the photons that Compton scatter within, and subsequently escape from the HPGe detector. Since these photons are correlated with the partial energy deposition within the detector, much of the resulting Compton continuum can be subtracted from the spectrum reducing the unwanted background in gamma-ray spectra. A commercially available Compton suppression spectrometer (CSS) was purchased from Canberra Industries and tested at the Radiation Science and Engineering Center at Penn State University. The PSU-CSS includes a reverse bias HPGe detector, four annulus NaI(Tl) detectors, a NaI(Tl) plug detector, detector shields, data acquisition electronics, and a data processing computer. The HPGe detector is n-type with 54% relative efficiency. The guard detectors form an annulus with 9-inch diameter and 9-inch height, and have a plug detector that goes into/out of the annulus with the help of a special lift apparatus to raise/lower. The detector assembly is placed in a shielding cave. State-of-the-art electronics and software are used. The system was tested using standard sources, neutron activated NIST SRM sample and Dendrochronologically Dated Tree Ring samples. The PSU-CSS dramatically improved the peak-to-Compton ratio, up to 1000 : 1 for the 137 Cs source. (author)

Digital Data Acquisition System for experiments with segmented detectors at National Superconducting Cyclotron Laboratory

Energy Technology Data Exchange (ETDEWEB)

Starosta, K., E-mail: starosta@sfu.c [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Vaman, C.; Miller, D.; Voss, P.; Bazin, D.; Glasmacher, T. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Crawford, H.; Mantica, P. [National Superconducting Cyclotron Laboratory and Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Tan, H.; Hennig, W.; Walby, M.; Fallu-Labruyere, A.; Harris, J.; Breus, D.; Grudberg, P.; Warburton, W.K. [XIA LLC, Hayward, CA 94544 (United States)

2009-11-11

A 624-channel Digital Data Acquisition System capable of instrumenting the Segmented Germanium Array at National Superconducting Cyclotron Laboratory has been implemented using Pixie-16 Digital Gamma Finder modules by XIA LLC. The system opens an opportunity for determination of the first interaction position of a gamma ray in a SeGA detector from implementation of gamma-ray tracking. This will translate into a significantly improved determination of angle of emission, and in consequence much better Doppler corrections for experiments with fast beams. For stopped-beam experiments the system provides means for zero dead time measurements of rare decays, which occur on time scales of microseconds.

Digital Data Acquisition System for experiments with segmented detectors at National Superconducting Cyclotron Laboratory

International Nuclear Information System (INIS)

Starosta, K.; Vaman, C.; Miller, D.; Voss, P.; Bazin, D.; Glasmacher, T.; Crawford, H.; Mantica, P.; Tan, H.; Hennig, W.; Walby, M.; Fallu-Labruyere, A.; Harris, J.; Breus, D.; Grudberg, P.; Warburton, W.K.

2009-01-01

A 624-channel Digital Data Acquisition System capable of instrumenting the Segmented Germanium Array at National Superconducting Cyclotron Laboratory has been implemented using Pixie-16 Digital Gamma Finder modules by XIA LLC. The system opens an opportunity for determination of the first interaction position of a γ ray in a SeGA detector from implementation of γ-ray tracking. This will translate into a significantly improved determination of angle of emission, and in consequence much better Doppler corrections for experiments with fast beams. For stopped-beam experiments the system provides means for zero dead time measurements of rare decays, which occur on time scales of microseconds.

Digital Data Acquisition System for experiments with segmented detectors at National Superconducting Cyclotron Laboratory

Science.gov (United States)

Starosta, K.; Vaman, C.; Miller, D.; Voss, P.; Bazin, D.; Glasmacher, T.; Crawford, H.; Mantica, P.; Tan, H.; Hennig, W.; Walby, M.; Fallu-Labruyere, A.; Harris, J.; Breus, D.; Grudberg, P.; Warburton, W. K.

2009-11-01

A 624-channel Digital Data Acquisition System capable of instrumenting the Segmented Germanium Array at National Superconducting Cyclotron Laboratory has been implemented using Pixie-16 Digital Gamma Finder modules by XIA LLC. The system opens an opportunity for determination of the first interaction position of a γ ray in a SeGA detector from implementation of γ-ray tracking. This will translate into a significantly improved determination of angle of emission, and in consequence much better Doppler corrections for experiments with fast beams. For stopped-beam experiments the system provides means for zero dead time measurements of rare decays, which occur on time scales of microseconds.

Evaluation of scintillators and semiconductor detectors to image three-photon positron annihilation for positron emission tomography

International Nuclear Information System (INIS)

Abuelhia, E.; Spyrou, N.M.; Kacperski, K.; College University, Middlesex Hospital, London

2008-01-01

Positron emission tomography (PET) is rapidly becoming the main nuclear imaging modality of the present century. The future of PET instrumentation relies on semiconductor detectors because of their excellent characteristics. Three-photon positron annihilation has been recently investigated as a novel imaging modality, which demands the crucial high energy resolution of semiconductor detector. In this work the evaluation of the NaI(Tl) scintillator and HPGe and CdZTe semiconductor detectors, to construct a simple three-photon positron annihilation scanner has been explored. The effect of detector and scanner size on spatial resolution (FWHM) is discussed. The characteristics: energy resolution versus count rate and point-spread function of the three-photon positron annihilation image profile from triple coincidence measurements were investigated. (author)

Recoil distance method lifetime measurements of the 2⁺₁ excited states in ⁸⁴Kr and ⁹⁴Sr

OpenAIRE

Chester, Aaron Stuart

2017-01-01

Intense re-accelerated beams delivered by the Isotope Separator and Accelerator (ISAC-II) facility at TRIUMF, Canada’s national laboratory for particle and nuclear physics, permit access to nuclear structure information for a wide range of radionuclides via in-beam γ-ray spectroscopy with the TRIUMF-ISAC Gamma-Ray Escape Suppressed Spectrometer (TIGRESS), a high-efficiency and Compton-suppressed segmented high-purity germanium (HPGe) detector array. Electromagnetic transition rates measured v...

Performance of GERDA phase II BEGe detectors

Energy Technology Data Exchange (ETDEWEB)

Wagner, Victoria [Max-Planck Institut fuer Kernphysik (Germany); Collaboration: GERDA-Collaboration

2015-07-01

The GERDA experiment searches for the lepton number violating neutrinoless double beta (0νββ) decay of {sup 76}Ge. GERDA uses HPGe detectors enriched in {sup 76}Ge as source and detection material. The experiment proceeds in two phases. In Phase I a background index of 10{sup -2} cts/(keV.kg.yr) was reached and a new lower limit on the half-life of the 0νββ decay of {sup 76}Ge was set to 2.1.10{sup 25} yr (at 95% C.L.). In Phase II the background index will be lowered by an order of magnitude and a sensitivity of 10{sup 26} yr will be reached. In order to achieve this goal 30 new custom-made broad energy germanium (BEGe) detectors and a liquid argon scintillation light veto will be deployed. Five BEGe detectors have been operated successfully in Phase I and demonstrated their improved energy resolution and enhanced pulse shape discrimination (PSD) against background events. Special designed electronics will further improve energy resolution and PSD performance. The first results from commissioning of the new BEGe detectors are presented in this talk.

In vivo measurement of Pb-210 in the skull for retrospective assessment of exposure to radon; Die in-vivo Messung von Pb-210 im Schaedel zur retrospektiven Bestimmung von Radon-Expositionen

Energy Technology Data Exchange (ETDEWEB)

Doerfel, H. [Forschungszentrum Karlsruhe GmbH (Germany). Hauptabteilung Sicherheit/Dosimetrie

1997-12-01

The study shows that the new HPGe detectors with a larger surface are significantly better in terms of results and performance than the Phoswich detectors hitherto used for in vivo measurement of Pb-210 in the human skull. The experimental evaluations indicate that smaller HPGe detectors likewise are better than the Phoswich detectors, but some additional studies are required for final evaluation of these instruments. (orig./CB) [Deutsch] Die Untersuchungen haben gezeigt, dass die neuen grossflaechigen HPGe-Detektoren wesentlich besser zur in-vivo Messung von Pb-210 im Skelett geeignet sind als die bisher eingesetzten Phoswich-Detektoren. Auch kleinere HPGe-Detektoren sind offenbar besser geeignet als Phoswich-Detektoren, allerdings sind hier noch einige ergaenzende Untersuchungen erforderlich. (orig./SR)

Data acquisition system for segmented reactor antineutrino detector

Czech Academy of Sciences Publication Activity Database

Hons, Zdeněk; Vlášek, J.

2017-01-01

Roč. 12, č. 1 (2017), č. článku P01022. ISSN 1748-0221 R&D Projects: GA MŠk LG14004 Institutional support: RVO:61389005 Keywords : Data acquisition concepts * Detector control systems (detector and experiment monitoring and slow-control system, architecture , hardware, algorithms, databases) * Neutrino detectors Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders OBOR OECD: Nuclear physics Impact factor: 1.220, year: 2016

Pulse shape discrimination studies of Phase I Ge-detectors

Energy Technology Data Exchange (ETDEWEB)

Kirsch, Andrea [MPI fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Collaboration: GERDA-Collaboration

2013-07-01

The GERmanium Detector Array experiment aims to search for the neutrinoless double beta decay (0νββ) of {sup 76}Ge by using isotopically enriched germanium crystals as source and detector simultaneously. The bare semiconductor diodes are operated in liquid argon at cryogenic temperatures in an ultra-low background environment. In addition, Gerda applies different active background reduction techniques, one of which is pulse shape discrimination studies of the current Phase I germanium detectors. The analysis of the signal time structure provides an important tool to distinguish single site events (SSE) of the ββ-decay from multi site events (MSE) of common gamma-ray background or surface events. To investigate the correlation between the signal shape and the interaction position, a new, also to the predominantly deployed closed-ended coaxial HPGe detectors applicable analysis technique has been developed. A summary of the used electronic/detector assembly is given and followed by a discussion of the performed classification procedure by means of accurate pulse shape simulations of 0νββ-like signals. Finally, the obtained results are presented along with an evaluation of the relevance for the Gerda experiment.

Study on a new calibration methods of in-situ HPGe γ spectrometers used for non-destructive analyzing radioactivity in nuclear facilities decommissioning

International Nuclear Information System (INIS)

Xiao Xuefu; Song Lijun; Wang Yulai; Wen Fuping; Liao Haitao; Ban Ying; Xia Yihua; Li Ruixiang; Li Hang; Tu Xingmin

2007-06-01

A new calibration technique, which is the Monte Carlo modeling technique, of in-situ HPGe γ spectrometers used for non-destructive analyzing radioactivity in nuclear facilities decommissioning, is presented. A series of assay for some stainless steel pipes and tanks in some nuclear facilities/laboratories of CIAE are taken on site with the in-situ HPGe γ spectrometer. At the same time, some examples are taken and analyzed in laboratories. The relative bias/variation between the values of activity measured by in-situ HPGe γ spectrometers on site and that analyzed in laboratory is less than ±45.0%. (authors)

First Results with TIGRESS and Accelerated Radioactive Ion Beams from ISAC: Coulomb Excitation of 20,21,29Na

Science.gov (United States)

Schumaker, M. A.; Hurst, A. M.; Svensson, C. E.; Wu, C. Y.; Becker, J. A.; Cline, D.; Hackman, G.; Pearson, C. J.; Stoyer, M. A.; Andreyev, A.; Austin, R. A. E.; Ball, G. C.; Bandyopadhyay, D.; Barton, C. J.; Boston, A. J.; Boston, H. C.; Buchmann, L.; Churchman, R.; Cifarelli, F.; Colosimo, S. J.; Cooper, R. J.; Cross, D. S.; Dashdorj, D.; Demand, G. A.; Dimmock, M. R.; Djongolov, M.; Drake, T. E.; Finlay, P.; Gallant, A. T.; Garrett, P. E.; Gray-Jones, C.; Green, K. L.; Grint, A. N.; Grinyer, G. F.; Harkness, L. J.; Hayes, A. B.; Kanungo, R.; Leach, K. G.; Kulp, W. D.; Lisetskiy, A. F.; Lee, G.; Lloyd, S.; Maharaj, R.; Martin, J.-P.; Millar, B. A.; Moisan, F.; Morton, A. C.; Mythili, S.; Nelson, L.; Newman, O.; Nolan, P. J.; Orce, J. N.; Oxley, D. C.; Padilla-Rodal, E.; Phillips, A. A.; Porter-Peden, M.; Ressler, J. J.; Rigby, S. V.; Roy, R.; Ruiz, C.; Sarazin, F.; Scraggs, D. P.; Sumithrarachchi, C. S.; Triambak, S.; Waddington, J. C.; Walker, P. M.; Wan, J.; Whitbeck, A.; Williams, S. J.; Wong, J.; Wood, J. L.

2009-03-01

The TRIUMF-ISAC Gamma-Ray Escape Suppressed Spectrometer (TIGRESS) is a state-of-the-art γ-ray spectrometer being constructed at the ISAC-II radioactive ion beam facility at TRIUMF. TIGRESS will be comprised of twelve 32-fold segmented high-purity germanium (HPGe) clover-type γ-ray detectors, with BGO/CsI(Tl) Compton-suppression shields, and is currently operational at ISAC-II in an early-implementation configuration of six detectors. Results have been obtained for the first experiments performed using TIGRESS, which examined the A = 20, 21, and 29 isotopes of Na by Coulomb excitation.

Background intercomparison with escape-suppressed germanium detectors in underground mines

Energy Technology Data Exchange (ETDEWEB)

Szuecs, Tamas; Bemmerer, Daniel [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany)

2014-07-01

A key requirement for underground nuclear astrophysics experiments is the very low background level in germanium detectors underground. The reference for these purposes is the world's so far only underground accelerator laboratory for nuclear astrophysics, LUNA. LUNA is located deep underground in the Gran Sasso laboratory in Italy, shielded from cosmic rays by 1400 m of rock. The background at LUNA was studied in detail using an escape-suppressed Clover-type HPGe detector. Exactly the same detector was subsequently transported to the Felsenkeller underground laboratory in Dresden, shielded by 45 m of rock, and the background was shown to be only a factor of three higher than at LUNA when comparing the escape-suppressed spectra, with interesting consequences for underground nuclear astrophysics. As the next step of a systematic study of the effects of a combination of active and passive shielding on the cosmic ray induced background, this detector is now being brought to the ''Reiche Zeche'' mine in Freiberg/Sachsen, shielded by 150 m of rock. The data from the Freiberg measurement are shown and discussed.

High resolution gamma-ray spectroscopy at high count rates with a prototype High Purity Germanium detector

Science.gov (United States)

Cooper, R. J.; Amman, M.; Vetter, K.

2018-04-01

High-resolution gamma-ray spectrometers are required for applications in nuclear safeguards, emergency response, and fundamental nuclear physics. To overcome one of the shortcomings of conventional High Purity Germanium (HPGe) detectors, we have developed a prototype device capable of achieving high event throughput and high energy resolution at very high count rates. This device, the design of which we have previously reported on, features a planar HPGe crystal with a reduced-capacitance strip electrode geometry. This design is intended to provide good energy resolution at the short shaping or digital filter times that are required for high rate operation and which are enabled by the fast charge collection afforded by the planar geometry crystal. In this work, we report on the initial performance of the system at count rates up to and including two million counts per second.

Real-time numerical processing for HPGE detectors signals

International Nuclear Information System (INIS)

Eric Barat; Thomas Dautremer; Laurent Laribiere; Jean Christophe Trama

2006-01-01

Full text of publication follows: Concerning the gamma spectrometry, technology progresses in the processor field makes very conceivable and attractive executing complex real-time digital process. Only some simplified and rigid treatments can be find in the market up to now. Indeed, the historical solution used for 50 years consists of performing a so-called 'cusp' filtering and disturbing the optimal shape in order to shrink and/or truncate it. This tuning largely determined by the input count rate (ICR) the user expects to measure is then a compromise between the resolution and the throughput. Because it is not possible to tune it for each pulse, that is a kind of 'leveling down' which is made: the energy of each pulse is not as well estimated as it could be. The new approach proposed here avoids totally this restricting hand tuning. The innovation lies in the modelling of the shot-noise signal as a Jump Markov Linear System. The jump is the occurrence of a pulse in the signal. From this model, we developed an algorithm which makes possible the on-line estimation of the energies without having to temporally enlarge the pulses as the cusp filter does. The algorithm first determines whether there is a pulse or not at each time, then conditionally to this information, it performs an optimal Kalman smoother. Thanks to this global optimization, this allows us to dramatically increase the compromise throughput versus resolution, gaining an important factor on a commercial device concerning the admissible ICR (more than 1 million counts per second admissible). A huge advantage of the absence of hand tuning is that the system accepts fluctuating ICR. To validate the concept we built a real time demonstrator. First, our equipment is composed of an electronic stage which prepared the signal coming from the preamplifier of the detector and optimized the signal-to-noise ratio. Then the signal is sampled at 10 MHz and the powerful of two Pentium running at 3 GHz is enough to

GRABGAM Analysis of Ultra-Low-Level HPGe Gamma Spectra

International Nuclear Information System (INIS)

Winn, W.G.

1999-01-01

The GRABGAM code has been used successfully for ultra-low level HPGe gamma spectrometry analysis since its development in 1985 at Savannah River Technology Center (SRTC). Although numerous gamma analysis codes existed at that time, reviews of institutional and commercial codes indicated that none addressed all features that were desired by SRTC. Furthermore, it was recognized that development of an in-house code would better facilitate future evolution of the code to address SRTC needs based on experience with low-level spectra. GRABGAM derives its name from Gamma Ray Analysis BASIC Generated At MCA/PC

GRABGAM Analysis of Ultra-Low-Level HPGe Gamma Spectra

Energy Technology Data Exchange (ETDEWEB)

Winn, W.G.

1999-07-28

The GRABGAM code has been used successfully for ultra-low level HPGe gamma spectrometry analysis since its development in 1985 at Savannah River Technology Center (SRTC). Although numerous gamma analysis codes existed at that time, reviews of institutional and commercial codes indicated that none addressed all features that were desired by SRTC. Furthermore, it was recognized that development of an in-house code would better facilitate future evolution of the code to address SRTC needs based on experience with low-level spectra. GRABGAM derives its name from Gamma Ray Analysis BASIC Generated At MCA/PC.

Investigation of n{sup +} surface events in HPGe detectors for liquid argon background rejection in GERDA

Energy Technology Data Exchange (ETDEWEB)

Lehnert, Bjoern [TU-Dresden, Dresden (Germany); Collaboration: GERDA-Collaboration

2015-07-01

The GERDA experiment is searching for neutrinoless double beta decay (0νββ) in {sup 76}Ge using an array of germanium detectors immersed in liquid argon (LAr). Phase II of the experiment aims to improve the background level by a factor 10 in order to reach 10{sup -3} counts / (kg.keV.yr). A strong suppression technique is required to suppress the intrinsic LAr background of {sup 42}Ar/{sup 42}K. 30 newly produced p-type Broad Energy Germanium (BEGe) detectors will be deployed in Phase II. The n{sup +} electrode of the GERDA BEGe detectors is covering 96-98 % of the surface and is between 0.5 and 1.2 mm thick. Betas from the {sup 42}K decay can penetrated the detector surface and deposit energies within the 0νββ region. Experiences from GERDA Phase I show that these surface events are the dominate background component without suppression. Energy depositions inside the n{sup +} layer create pulse shapes that are slower than those from interactions in the bulk. This talk presents a rejection technique for those events. The signal development inside the n{sup +} layer is modeled and applied in Geant4 Monte Carlo simulations. The simulations are compared with data for {sup 241}Am and {sup 90}Sr calibration source measurements. The suppression capabilities are extrapolated for {sup 42}K in GERDA Phase II.

The dynamics of monolithic suspensions for advanced detectors: A 3-segment model

Energy Technology Data Exchange (ETDEWEB)

Piergiovanni, F; Campagna, E; Cesarini, E; Martelli, F; Vetrano, F; Vicere, A [Universita di Urbino, Via S.Chiara 27, 61029 Urbino (Italy); Lorenzini, M; Cagnoli, G; Losurdo, G, E-mail: piergiovanni@fi.infn.i [INFN, Istituto Nazionale di Fisica Nucleare, Sez. di Firenze, via G. Sansone 1, 50019 Sesto Fiorentino (Italy)

2010-05-01

In order to reduce the suspension thermal noise, the second generation GW interferometric detectors will employ monolithic suspensions in fused silica to hold the mirrors. The fibres are produced by melting and pulling apart a fused silica rod, obtaining a long thin wire with two thicker heads. The dynamics of such a fibre is in principle different from that of a cylindrical, regular fibre, because most of the deformation energy is stored in the neck region where the diameter is variable. This is an advantage, since adjusting the neck tapering, a thermoelastic noise cancellation effect can be obtained. Therefore, a careful study of the suspensions behavior is necessary to estimate the overall noise and to optimize the control strategy. To simplify the control design, a simple three segment model for the silica fibres has been developed, fully equivalent to the beam equation at low frequencies. The model, analytically proved for a regular cylindrical fibre, can be extended to a fibre with tapered necks, provided that the equivalent bending length is suitably measured. We developed a tool to measure the position of the bending point for each fibre, thus allowing to experimentally check the validity of the model. A numerical code has been written to solve the beam equation for wires with varying diameter. This code confirms the validity of the three segment model. Moreover, it is possible to extend the solution to higher frequencies thus computing the transfer function and the energy distribution of the suspension system and estimating the thermal noise contribution.

Monte Carlo Simulation for the Majorana Neutrinoless Double-beta Decay Experiment

International Nuclear Information System (INIS)

Henning, Reyco; Majorana Collaboration

2005-01-01

The Majorana experiment is a proposed HPGe detector array that will primarily search for neutrinoless double-beta decay and dark matter. It will rely on pulse-shape discrimination and crystal segmentation to suppress backgrounds following careful materials selection. A critical aspect of the design phase of Majorana is a reliable simulation of the detector response, pulse formation, and its radioactive backgrounds. We are developing an adaptable and complete simulation based on GEANT 4 to address these requirements and the requirements of a modern, large collaboration experiment. The salient aspects of the simulation are presented. The Majorana experiment is presented in a parallel poster by Kareem Kazkaz

Works of art investigation with silicon drift detectors

CERN Document Server

Leutenegger, P; Fiorini, C; Strüder, L; Kemmer, J; Lechner, P; Sciuti, S; Cesareo, R

2000-01-01

The X-ray fluorescence (XRF) spectroscopy analysis is a non-destructive technique widely used in archeometry to investigate the chemical composition of pigments, metal alloys and stones for restoration and historical investigation. The classical detection systems for archeometrical investigations utilize cryogenic detectors, like Si(Li) and HPGe, characterized by a satisfactory energy resolution (of the order of 140 eV FWHM at 6 keV). However, the requirements of liquid N sub 2 drastically limit the portability of such systems, limiting the possibility of making measurements 'on the field'. Recently new silicon PIN diodes Peltier cooled were introduced, allowing the construction of portable instrumentation. However, their energy resolution (of the order of 250 eV FWHM at 6 keV) results in some cases unsatisfactory (for instance in the identification of light elements). Both the requirements of portability and good energy resolution are fulfilled by the silicon drift detector (SDD). The SDD, cooled by a Peltie...

PHAROS A pluri-detector, high-resolution, analyser of radiometric properties of soil

CERN Document Server

Rigollet, C

2002-01-01

PHAROS is a new type of core logger, designed to measure activity concentrations of sup 4 sup 0 K, sup 2 sup 3 sup 8 U, sup 2 sup 3 sup 2 Th and sup 1 sup 3 sup 7 Cs in sediment and rock cores with a spatial resolution of a few centimetres along the core. PHAROS has been developed as a non-destructive alternative to the traditional slicing of cores into sub-samples and their analysis on an HPGe detector. The core is scanned at fixed increments by three BGO scintillation detectors and the spectra analysed by the full spectrum analysis method. The core logger is also equipped with a collimated lead castle and a sup 1 sup 3 sup 7 Cs source for transmission measurements. In this paper, we report on the properties of the core logger and its detectors, and on the analysis techniques used for the determination of the radionuclides activity concentrations. Results from initial measurements are presented and discussed.

Pulse shape analysis for γ-ray tracking. Part I: Pulse shape simulation with JASS

International Nuclear Information System (INIS)

Schlarb, M.; Gernhaeuser, R.; Klupp, S.; Kruecken, R.

2011-01-01

Next-generation γ -ray spectrometers based on highly segmented HPGe detectors are using the recent technique of γ -ray tracking to significantly improve on efficiency and Doppler correction capabilities. A precise reconstruction of the individual interaction locations within the active material is possible through the use of pulse shape analysis (PSA) which, in turn, demands an accurate knowledge of the detector response. We developed JASS, a Java-based simulation software package to generate pulse shapes for the AGATA detectors from physics constraints and basic material parameters. For verifying the simulation experimental data from a coincidence scan with known interaction locations was used. The achieved position resolution, in the order of a few millimeters, is within the requirements of the γ -ray tracking array. (orig.)

Numerical simulation and optimal design of Segmented Planar Imaging Detector for Electro-Optical Reconnaissance

Science.gov (United States)

Chu, Qiuhui; Shen, Yijie; Yuan, Meng; Gong, Mali

2017-12-01

Segmented Planar Imaging Detector for Electro-Optical Reconnaissance (SPIDER) is a cutting-edge electro-optical imaging technology to realize miniaturization and complanation of imaging systems. In this paper, the principle of SPIDER has been numerically demonstrated based on the partially coherent light theory, and a novel concept of adjustable baseline pairing SPIDER system has further been proposed. Based on the results of simulation, it is verified that the imaging quality could be effectively improved by adjusting the Nyquist sampling density, optimizing the baseline pairing method and increasing the spectral channel of demultiplexer. Therefore, an adjustable baseline pairing algorithm is established for further enhancing the image quality, and the optimal design procedure in SPIDER for arbitrary targets is also summarized. The SPIDER system with adjustable baseline pairing method can broaden its application and reduce cost under the same imaging quality.

Strategy of HPGe screening measurements in the SuperNEMO experiment

Energy Technology Data Exchange (ETDEWEB)

Perrot, Frédéric [Université de Bordeaux, Centre d' Etudes Nucléaires de Bordeaux Gradignan, UMR 5797, Chemin du Solarium, Le Haut-Vigneau, BP120, F-33175 Gradignan, France and CNRS/IN2P3, Centre d' Etudes Nucléaires de Bordeaux Gradignan, UMR 5797 (France); Collaboration: SuperNEMO Collaboration

2013-08-08

SuperNEMO is a double beta decay experiment that will use a tracko-calorimeter technique. The goal is to reach a sensitivity of T{sub 1/2}(0ν)>10{sup 26} y corresponding to an effective Majorana neutrino mass of 0.04-0.11 eV with 100 kg of {sup 82}Se. The general strategy of the HPGe screening measurements is described for the materials of the SuperNEMO demonstrator, regarding their radiopurity and their location. The two platforms, PRISNA and LSM, used for this screening are also briefly described.

Study on the use of well-type NaI(TI) detector for 210Pb measurements

International Nuclear Information System (INIS)

Al-Azmi, Darwish; Mustapha, A.O.; Karunakara, N.

2013-01-01

The measurements of 210 Pb in environmental or geological samples are usually carried out using HPGe gamma spectrometers or by chemical separation followed by low background beta counting system. In the present study, the possibility of using a well-type NaI(TI) detector for the measurement of 210 Pb in such measurements has been explored. The measurements were tested using a well-type NaI(TI) detector of a standard size 7.6 cm x 7.6 cm (3x3 inches) with a well size of 2.86 cm diameter and 5.08 cm depth, which can accommodate vials of 20 ml capacity. The performance of the detector was tested by measuring the low-energy photons 46.5 keV of 210 Pb from the IAEA standard reference material. It is observed that the shape of the energy spectrum has been found to be comparable with those obtained using thin crystal (1.9 mm) NaI detectors for such low-photon energies. Therefore, it is expected that this well-type detector will prove useful in such low-energy photon measurements. (author)

A combined segmented anode gas ionization chamber and time-of-flight detector for heavy ion elastic recoil detection analysis

Science.gov (United States)

Ström, Petter; Petersson, Per; Rubel, Marek; Possnert, Göran

2016-10-01

A dedicated detector system for heavy ion elastic recoil detection analysis at the Tandem Laboratory of Uppsala University is presented. Benefits of combining a time-of-flight measurement with a segmented anode gas ionization chamber are demonstrated. The capability of ion species identification is improved with the present system, compared to that obtained when using a single solid state silicon detector for the full ion energy signal. The system enables separation of light elements, up to Neon, based on atomic number while signals from heavy elements such as molybdenum and tungsten are separated based on mass, to a sample depth on the order of 1 μm. The performance of the system is discussed and a selection of material analysis applications is given. Plasma-facing materials from fusion experiments, in particular metal mirrors, are used as a main example for the discussion. Marker experiments using nitrogen-15 or oxygen-18 are specific cases for which the described improved species separation and sensitivity are required. Resilience to radiation damage and significantly improved energy resolution for heavy elements at low energies are additional benefits of the gas ionization chamber over a solid state detector based system.

ADC common noise correction and zero suppression in the PIBETA detector

International Nuclear Information System (INIS)

Frlez, E.; Pocanic, D.; Ritt, S.

2001-01-01

We describe a simple procedure for reducing Analog-to-Digital Converter (ADC) common noise in modular detectors that does not require additional hardware. A method using detector noise groups should work well for modular particle detectors such as segmented electromagnetic calorimeters, plastic scintillator hodoscopes, cathode strip wire chambers, segmented active targets, and the like. We demonstrate a 'second pedestal noise correction' method by comparing representative ADC pedestal spectra for various elements of the PIBETA detector before and after the applied correction

Determination of the detection efficiency of a HPGe detector by means of the MCNP 4A simulation code; Determinacion de la eficiencia de deteccion de un detector HPGe mediante el codigo de simulacion MCNP 4A

Energy Technology Data Exchange (ETDEWEB)

Leal, B. [Centro Regional de Estudios Nucleares, A.P. 579C, 98068 Zacatecas (Mexico)

2004-07-01

In the majority of the laboratories, the calibration in efficiency of the detector is carried out by means of the standard sources measurement of gamma photons that have a determined activity, or for matrices that contain a variety of radionuclides that can embrace the energy range of interest. Given the experimental importance that has the determination from the curves of efficiency to the effects of establishing the quantitative results, is appealed to the simulation of the response function of the detector used in the Regional Center of Nuclear Studies inside the energy range of 80 keV to 1400 keV varying the density of the matrix, by means of the application of the Monte Carlo code MCNP-4A. The adjustment obtained shows an acceptance grade in the range of 100 to 600 keV, with a smaller percentage discrepancy to 5%. (Author)

Comparison of MCNP and Experimental Measurements for an HPGe-based Spectroscopy Portal Monitor

International Nuclear Information System (INIS)

Keyser, Ronald M.; Hensley, Walter K.; Twomey, Timothy R.; UPP, Daniel L.

2008-01-01

The necessity to monitor international commercial transportation for illicit nuclear materials resulted in the installation of many nuclear radiation detection systems in Portal Monitors. These were mainly gross counters which alarmed at any indication of high radioactivity in the shipment, the vehicle or even the driver. The innocent alarm rate, due to legal shipments of sources and NORM, or medical isotopes in patients, caused interruptions and delays in commerce while the legality of the shipment was verified. To overcome this difficulty, Department of Homeland Security (DHS) supported the writing of the ANSI N42.38 standard (Performance Criteria for Spectroscopy-Based Portal Monitors used for Homeland Security) to define the performance of a Portal Monitor with nuclide identification capabilities, called a Spectroscopy Portal Monitor. This standard defines detection levels and response characteristics for the system for energies from 25 keV to 3 MeV. To accomplish the necessary performance, several different HPGe detector configurations were modeled using MCNP for the horizontal field of view (FOV) and vertical linearity of response over the detection zone of 5 meters by 4.5 meters for 661 keV as representative of the expected nuclides of interest. The configuration with the best result was built and tested. The results for the FOV as a function of energy and the linearity show good agreement with the model and performance exceeding the requirements of N42.38

Evaluation of radon measuring technique using passive detector activated carbon; Avaliacao da tecnica de medicao do radonio utilizando detector passivo com carvao ativado

Energy Technology Data Exchange (ETDEWEB)

Ferreira, Paulo Roberto Rocha; Lessa, Edmilson de Lima; Oliveira, Evaldo Paulo de, E-mail: epoliveira@aluno.ird.gov.br [Instituto de Radioprotecao e Dosimetria, (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Div. de Radioprotecao Ambiental e Ocupacional

2014-07-01

This study aims to evaluate the efficiency of measuring the radioactive gas Radon ({sup 222} Rn) with passive detector activated carbon. Alpha Guard, exposure chamber, air sampler, default font Radio, calibrator flow, flow adjuster, ducts drivers: For this, various equipment to make the measurement system as were used. An assembly of such equipment, with specific sequence was used allowing for more efficient exposure of passive detectors Radon gas. Twenty samples were heated to remove moisture and then stored in desiccator until the experiment were made. The exhibition was held passive dosimeters being removed from the chamber, and one hour after, subjected to analysis by gamma spectrometry in germanium (HPGe) for an hour. Subsequently, other measurements were made at scheduled times and sequential for one hour. The results were presented in report form and spectra, measures and graphs generated by Alpha Guard were also extracted. Finally we calculated the efficiency of the passive meter activated carbon. (author)

Silicon Drift Detectors - A Novel Technology for Vertex Detectors

Science.gov (United States)

Lynn, D.

1996-10-01

Silicon Drift Detectors (SDD) are novel position sensing silicon detectors which operate in a manner analogous to gas drift detectors. Single SDD's were shown in the CERN NA45 experiment to permit excellent spatial resolution (pseudo-rapidity. Over the last three years we undertook a concentrated R+D effort to optimize the performance of the detector by minimizing the inactive area, the operating voltage and the data volume. We will present test results from several wafer prototypes. The charge produced by the passage of ionizing particles through the bulk of the detectors is collected on segmented anodes, with a pitch of 250 μm, on the far edges of the detector. The anodes are wire-bonded to a thick film multi-chip module which contains preamplifier/shaper chips and CMOS based switched capacitor arrays used as an analog memory pipeline. The ADC is located off-detector. The complete readout chain from the wafer to the DAQ will be presented. Finally we will show physics performance simulations based on the resolution achieved by the SVT prototypes.

Study of the renal segmental arterial anatomy with contrast-enhanced multi-detector computed tomography.

Science.gov (United States)

Rocco, Francesco; Cozzi, Luigi Alberto; Cozzi, Gabriele

2015-07-01

To use triphasic multi-detector computed tomography (MDCT) to study the renal segmental arterial anatomy and its relationship with the urinary tract to plan nephron-sparing surgery (NSS). One hundred and fifty nine patients underwent abdominal contrast-enhanced MDCT. We evaluated renal arteries and parenchymal vasculature. In 61 patients, the arteries and the urinary tract were represented simultaneously. 86.60% presented a single renal artery; 13.4%, multiple arteries. All single renal arteries divided into anterior and posterior branch before the hilum. The anterior artery branched into a superior, middle, and inferior branch. In 43.14%, the inferior artery arose before the others; in 45.75%, the superior artery arose before the others; in 9.80%, the branches shared a common trunk. In 26.80%, the posterior artery supplies the entire posterior surface; in 73.20%, it ends along the inferior calyx. In 96.73%, the upper pole was vascularized by the anterior superior branch and the posterior artery: the "tuning fork". MDCT showed four vascular segments in 96.73% and five in 3.27%. MDCT showed two avascular areas: the first along the projection of the inferior calyx on the posterior aspect, the second between the branches of the "tuning fork". The arterial phase provides the arterial tree representation; the delayed phase shows arteries and urinary tract simultaneously. MDCT provides a useful representation of the renal anatomy prior to intervascular-intrarenal NSS.

Consistent empirical physical formula construction for recoil energy distribution in HPGe detectors by using artificial neural networks

International Nuclear Information System (INIS)

Akkoyun, Serkan; Yildiz, Nihat

2012-01-01

The gamma-ray tracking technique is a highly efficient detection method in experimental nuclear structure physics. On the basis of this method, two gamma-ray tracking arrays, AGATA in Europe and GRETA in the USA, are currently being tested. The interactions of neutrons in these detectors lead to an unwanted background in the gamma-ray spectra. Thus, the interaction points of neutrons in these detectors have to be determined in the gamma-ray tracking process in order to improve photo-peak efficiencies and peak-to-total ratios of the gamma-ray peaks. In this paper, the recoil energy distributions of germanium nuclei due to inelastic scatterings of 1–5 MeV neutrons were first obtained by simulation experiments. Secondly, as a novel approach, for these highly nonlinear detector responses of recoiling germanium nuclei, consistent empirical physical formulas (EPFs) were constructed by appropriate feedforward neural networks (LFNNs). The LFNN-EPFs are of explicit mathematical functional form. Therefore, the LFNN-EPFs can be used to derive further physical functions which could be potentially relevant for the determination of neutron interactions in gamma-ray tracking process.

En analyse af transportabel Ge-detektor tilhørende atomberedskabet

DEFF Research Database (Denmark)

Aage, Helle Karina

1998-01-01

Calibration of HPGe-detector for airborne (and carborne) gamma-ray measurements. Hardware and software performance analysis. Hardware Walklab, software EMCAPLUS. Market analysis of similiar equipment.......Calibration of HPGe-detector for airborne (and carborne) gamma-ray measurements. Hardware and software performance analysis. Hardware Walklab, software EMCAPLUS. Market analysis of similiar equipment....

Calibration of HPGe detector for in situ measurements of 137Cs in soil by 'peak to valley' method

International Nuclear Information System (INIS)

Fueloep, M.

2000-01-01

The contamination of soil with gamma-ray emitters can be measured in two ways: soil sampling method and in situ spectrometry of the ambient gamma-ray radiation. The conventional soil sampling method has two disadvantages: samples may not be representative for a large areas and determination of the depth distribution of radionuclide requires the measurement of several samples taken from different depths. In situ measurement of a radionuclide activity in soil is more sensitive and provides more representative data than data obtained by soil sample collection and subsequent laboratory analysis. In emergency situations time to assess the contamination is critical. For rapid assessment of the deposited activity direct measurement of ambient gamma-ray radiation are used. In order to obtain accurate measurements of radionuclides in the soil, the detector should be placed on relatively even and open terrain. It is our customary practice to place the detector 1 m above the soil surface. At this height, a tripod-mounted detector can be handled easily and still provide a radius of view for gamma emitting sources out to about 10 m. The 'field of view' actually varies, being somewhat larger for higher sources. Depending upon source energy, the detector effectively sees down to a depth of 15-30 cm. Commonly used method for field gamma spectrometry is method by Beck (1). The most important disadvantages of in situ spectrometry by Beck are that the accuracy of the analysis depends on a separate knowledge of the radioactivity distribution with soil depth. This information can be obtained by calculations using data from in situ measurements and energy dependence of absorption and scattering of photons in soil and track length distribution of photons in soil (2). A method of in situ measurements of 137 Cs in soil where radionuclide distribution in soil profile is calculated by unfolding of detector responses in the full energy peak net area at 0.662 MeV and in the valley under the

Deconvolution of gamma energy spectra from NaI (Tl) detector using the Nelder-Mead zero order optimisation method

International Nuclear Information System (INIS)

RAVELONJATO, R.H.M.

2010-01-01

The aim of this work is to develop a method for gamma ray spectrum deconvolution from NaI(Tl) detector. Deconvolution programs edited with Matlab 7.6 using Nelder-Mead method were developed to determine multiplet shape parameters. The simulation parameters were: centroid distance/FWHM ratio, Signal/Continuum ratio and counting rate. The test using synthetic spectrum was built with 3σ uncertainty. The tests gave suitable results for centroid distance/FWHM ratio≥2, Signal/Continuum ratio ≥2 and counting level 100 counts. The technique was applied to measure the activity of soils and rocks samples from the Anosy region. The rock activity varies from (140±8) Bq.kg -1 to (190±17)Bq.kg -1 for potassium-40; from (343±7)Bq.Kg -1 to (881±6)Bq.kg -1 for thorium-213 and from (100±3)Bq.kg -1 to (164 ±4) Bq.kg -1 for uranium-238. The soil activity varies from (148±1) Bq.kg -1 to (652±31)Bq.kg -1 for potassium-40; from (1100±11)Bq.kg -1 to (5700 ± 40)Bq.kg -1 for thorium-232 and from (190 ±2) Bq.kg -1 to (779 ±15) Bq -1 for uranium -238. Among 11 samples, the activity value discrepancies compared to high resolution HPGe detector varies from 0.62% to 42.86%. The fitting residuals are between -20% and +20%. The Figure of Merit values are around 5%. These results show that the method developed is reliable for such activity range and the convergence is good. So, NaI(Tl) detector combined with deconvolution method developed may replace HPGe detector within an acceptable limit, if the identification of each nuclides in the radioactive series is not required [fr

Voluminal modelling for the characterization of wastes packages by gamma emission computed tomography

International Nuclear Information System (INIS)

Pettier, J.L.; Thierry, R.

2001-01-01

The aim of this work is to model the measurement process used for multi-photon emission computed tomography on nuclear waste drum. Our model MEPHISTO (Multi-Energy PHoton Imagery through Segmented TOmography) takes into account all phenomena influencing gamma emergent flux and high resolution spectrometric measurements using an HpGe detector through a collimator aperture. These phenomena are absorption and Compton scattering of gamma photons in waste drum, geometrical blur, spatial and energetic response of the detector. The analysis of results shows better localisation and quantification performances compared with a Ray-Driven method. It proves the importance of an accurate modelization of collimated measurements to reduce noise and stabilize iterative image reconstructions. (authors)

Recommended procedure for selection of detector systems for in vivo measurement of incorporated radioactivity; Empfehlungen zur Auswahl von Detektorsystemen zur Direktmessung der Koerperaktivitaet

Energy Technology Data Exchange (ETDEWEB)

Sahre, P. [Verein fuer Kernverfahrenstechnik und Analytik (VKTA) Rossendorf e.V., Dresden (Germany); Wahl, W. [GSF Forschungszentrum fuer Umwelt und Gesundheit, Neuherberg (Germany). Inst. fuer Strahlenschutz; Doerfel, H. [Forschungszentrum Karlsruhe GmbH (Germany)

1997-12-01

The paper presents and discusses a variety of aspects and objectives to be considered and explains the selection criteria to be applied with reference to the available detector systems. All available detector systems are shown and explained in a table. (orig./CB) [Deutsch] Zur Direktmessung der Koerperaktivitaet werden vorwiegend Halbleiter- und Szintillationsdetektoren verwendet. Bei Halbleiterdetektoren kommen der Regel HPGe-Detektoren und in Einzelfaellen auch Si(Li)-Detektoren zum Einsatz. Bei Szintillationsdetektoren werden hauptsaechlich NaI(TI)-Detektoren sowie NaI(TI)/CsI(TI)-Phoswich-Detektoren verwendet. Verschiedene Gesichtspunkte zur Auswahl von Detektorsystemen werden vorgestellt. (orig./SR)

Design and development of a silicon-segmented detector for 2D dose measurements in radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Menichelli, David [Department of Clinical Phisiopathology, University of Florence, v.le Morgagni, 85-50134 Florence (Italy); INFN, Florence division, Via G. Sansone 1, 50019 Sesto Fiorentino (Italy)], E-mail: david.menichelli@cern.ch; Bruzzi, Mara [Department of Energetics, University of Florence, via S. Marta, 3-50139 Florence (Italy); INFN, Florence division, Via G. Sansone 1, 50019 Sesto Fiorentino (Italy); Bucciolini, Marta; Talamonti, Cinzia; Casati, Marta; Marrazzo, Livia [Department of Clinical Phisiopathology, University of Florence, v.le Morgagni, 85-50134 Florence (Italy); INFN, Florence division, Via G. Sansone 1, 50019 Sesto Fiorentino (Italy); Tesi, Mauro [Department of Energetics, University of Florence, via S. Marta, 3-50139 Florence (Italy); Piemonte, Claudio; Pozza, Alberto; Zorzi, Nicola [ITC-irst, via Sommarive, 18-38050 Trento (Italy); Brianzi, Mirko [INFN, Florence division, Via G. Sansone 1, 50019 Sesto Fiorentino (Italy); De Sio, Antonio [Department of Astronomy and Space Science, University of Florence, L.go E. Fermi, 2-50125 Florence (Italy)

2007-12-11

Modern radiotherapy treatment techniques, such as intensity Modulated Radiation Therapy (IMRT) and protontherapy, require detectors with specific features, usually not available in conventional dosimeters. IMRT dose measurements, for instance, must face non-uniform beam fluences as well as a time-varying dose rate. Two-dimensional detectors present a great interest for dosimetry in beams with steep dose gradients, but they must satisfy a number of requirements and, in particular, they must exhibit high spatial resolution. With the aim of developing a dosimetric system adequate for 2D pre-treatment dose verifications, we designed a modular dosimetric device based on a monolithic silicon-segmented module. State and results of this work in progress are described in this article. The first 441 pixels, 6.29x6.29 cm{sup 2} silicon module has been produced by ion implantation on a 50 {mu}m thick p-type epitaxial layer. This sensor has been connected to a discrete readout electronics performing current integration, and has been tested with satisfactory results. In the final configuration, nine silicon modules will be assembled together to cover an area close to 20x20 cm{sup 2} with 3969 channels. In this case, the readout electronics will be based on an ASIC capable to read 64 channels by performing current-to-frequency conversion.

A mobile antineutrino detector with plastic scintillators

International Nuclear Information System (INIS)

Kuroda, Y.; Oguri, S.; Kato, Y.; Nakata, R.; Inoue, Y.; Ito, C.; Minowa, M.

2012-01-01

We propose a new type segmented antineutrino detector made of plastic scintillators for the nuclear safeguard application. A small prototype was built and tested to measure background events. A satisfactory unmanned field operation of the detector system was demonstrated. Besides, a detailed Monte Carlo simulation code was developed to estimate the antineutrino detection efficiency of the detector.

Characterization and calibration of radiation-damaged double-sided silicon strip detectors

Energy Technology Data Exchange (ETDEWEB)

Kaya, L. [Institut für Kernphysik, Universität zu Köln, D-50937 Köln (Germany); Vogt, A., E-mail: andreas.vogt@ikp.uni-koeln.de [Institut für Kernphysik, Universität zu Köln, D-50937 Köln (Germany); Reiter, P.; Birkenbach, B.; Hirsch, R.; Arnswald, K.; Hess, H.; Seidlitz, M.; Steinbach, T.; Warr, N.; Wolf, K. [Institut für Kernphysik, Universität zu Köln, D-50937 Köln (Germany); Stahl, C.; Pietralla, N. [Institut für Kernphysik, Technische Universität Darmstadt, D-64291 Darmstadt (Germany); Limböck, T.; Meerholz, K. [Physikalische Chemie, Universität zu Köln, D-50939 Köln (Germany); Lutter, R. [Maier-Leibnitz-Laboratorium, Ludwig-Maximilians-Universität München, D-85748 Garching (Germany)

2017-05-21

Double-sided silicon strip detectors (DSSSD) are commonly used for event-by-event identification of charged particles as well as the reconstruction of particle trajectories in nuclear physics experiments with stable and radioactive beams. Intersecting areas of both p- and n-doped front- and back-side segments form individual virtual pixel segments allowing for a high detector granularity. DSSSDs are employed in demanding experimental environments and have to withstand high count rates of impinging nuclei. The illumination of the detector is often not homogeneous. Consequently, radiation damage of the detector is distributed non-uniformly. Position-dependent incomplete charge collection due to radiation damage limits the performance and lifetime of the detectors, the response of different channels may vary drastically. Position-resolved charge-collection losses between front- and back-side segments are investigated in an in-beam experiment and by performing radioactive source measurements. A novel position-resolved calibration method based on mutual consistency of p-side and n-side charges yields a significant enhancement of the energy resolution and the performance of radiation-damaged parts of the detector.

Segmented Monolithic Germanium Detector Arrays for X-ray Absorption Spectroscopy. Final Report

International Nuclear Information System (INIS)

Hull, Ethan L.

2011-01-01

The experimental results from the Phase I effort were extremely encouraging. During Phase I PHDs Co. made the first strides toward a new detector technology that could have great impact on synchrotron x-ray absorption (XAS) measurements, and x-ray detector technology in general. Detector hardware that allowed critical demonstration measurements of our technology was designed and fabricated. This new technology allows good charge collection from many pixels on a single side of a multi-element monolithic germanium planar detector. The detector technology provides 'dot-like' collection electrodes having very low capacitance. The detector technology appears to perform as anticipated in the Phase I proposal. In particular, the 7-pixel detector studied showed remarkable properties; making it an interesting example of detector physics. The technology is enabled by the use of amorphous germanium contact technology on germanium planar detectors. Because of the scalability associated with the fabrication of these technologies at PHDs Co., we anticipate being able to supply larger detector systems at significantly lower cost than systems made in the conventional manner.

Gamma ray spectrum of Am 241 in a backscattering geometry using a high purity germanium detector

International Nuclear Information System (INIS)

Chong Chon Sing; Ibrahim Salih Elyaseery; Ahmad Shukri Mustapa Kamal; Abdul Aziz Tajuddin

1997-01-01

In back scattering geometry using an annular Am-241 source and a HPGE detector has been set up to study both the coherent and incoherent scattering of photon emissions of Am-241 from medium-Z and high-Z elements. Besides the coherent and incoherent scattered peaks of the emissions from the source, the gamma ray spectrum from the different target elements obtained using a microcomputer based multichannel analyser showed the presence of several other peaks. These peaks have been identified to arise from the fluorescence of the targets, the fluorescence of the shielding material Pb, and also as fluorescence sum peaks and X-ray escape peaks of the detector material Ge. The spectra are presented for three target elements viz. Mo, Zn and W

Design, calibration, and performance of the MINERvA detector

Energy Technology Data Exchange (ETDEWEB)

Aliaga, L. [Department of Physics, College of William and Mary, Williamsburg, VA 23187 (United States); Sección Física, Departamento de Ciencias, Pontificia Universidad Católica del Perú, Apartado 1761, Lima, Perú (Peru); Bagby, L.; Baldin, B. [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Baumbaugh, A. [Sección Física, Departamento de Ciencias, Pontificia Universidad Católica del Perú, Apartado 1761, Lima, Perú (Peru); Bodek, A.; Bradford, R. [University of Rochester, Rochester, NY 14610 (United States); Brooks, W.K. [Departamento de Física, Universidad Técnica Federico Santa María, Avda. España 1680, Casilla 110-V, Valparaíso (Chile); Boehnlein, D. [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Boyd, S. [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Budd, H. [University of Rochester, Rochester, NY 14610 (United States); Butkevich, A. [Institute for Nuclear Research of the Russian Academy of Sciences, 117312 Moscow (Russian Federation); Martinez Caicedo, D.A.; Castromonte, C.M. [Hampton University, Department of Physics, Hampton, VA 23668 (United States); Christy, M.E. [Department of Physics, University of Minnesota – Duluth, Duluth, MN 55812 (United States); Chvojka, J. [University of Rochester, Rochester, NY 14610 (United States); Motta, H. da [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, Urca, Rio de Janeiro, RJ 22290-180 (Brazil); and others

2014-04-11

The MINERvA experiment is designed to perform precision studies of neutrino-nucleus scattering using ν{sub μ} and ν{sup ¯}{sub μ} neutrinos incident at 1–20 GeV in the NuMI beam at Fermilab. This article presents a detailed description of the MINERvA detector and describes the ex situ and in situ techniques employed to characterize the detector and monitor its performance. The detector is composed of a finely segmented scintillator-based inner tracking region surrounded by electromagnetic and hadronic sampling calorimetry. The upstream portion of the detector includes planes of graphite, iron and lead interleaved between tracking planes to facilitate the study of nuclear effects in neutrino interactions. Observations concerning the detector response over sustained periods of running are reported. The detector design and methods of operation have relevance to future neutrino experiments in which segmented scintillator tracking is utilized.

Limitations on energy resolution of segmented silicon detectors

Science.gov (United States)

Wiącek, P.; Chudyba, M.; Fiutowski, T.; Dąbrowski, W.

2018-04-01

In the paper experimental study of charge division effects and energy resolution of X-ray silicon pad detectors are presented. The measurements of electrical parameters, capacitances and leakage currents, for six different layouts of pad arrays are reported. The X-ray spectra have been measured using a custom developed dedicated low noise front-end electronics. The spectra measured for six different detector layouts have been analysed in detail with particular emphasis on quantitative evaluation of charge division effects. Main components of the energy resolution due to Fano fluctuations, electronic noise, and charge division, have been estimated for six different sensor layouts. General recommendations regarding optimisation of pad sensor layout for achieving best possible energy resolution have been formulated.

Parity assignments in 140Ce up to 7 MeV using Compton polarimetry

International Nuclear Information System (INIS)

Buessing, M. A.; Elvers, M.; Endres, J.; Hasper, J.; Zilges, A.; Fritzsche, M.; Lindenberg, K.; Mueller, S.; Savran, D.; Sonnabend, K.

2008-01-01

Parity quantum numbers of J=1 states up to 7 MeV in the region of the Pygmy Dipole Resonance in 140 Ce were determined model independently by combining the methods of Nuclear Resonance Fluorescence and Compton polarimetry. For the first time the well-established method of Compton polarimetry was applied at such high energies. The experiment was performed using a fourfold segmented HPGe clover detector for the detection of the scattered photons. For all investigated dipole transitions asymmetries are found which correspond to negative parity of the excited states

A rotation-symmetric, position-sensitive annular detector for maximum counting rates

International Nuclear Information System (INIS)

Igel, S.

1993-12-01

The Germanium Wall is a semiconductor detector system containing up to four annular position sensitive ΔE-detectors from high purity germanium (HPGe) planned to complement the BIG KARL spectrometer in COSY experiments. The first diode of the system, the Quirl-detector, has a two dimensional position sensitive structure defined by 200 Archimedes' spirals on each side with opposite orientation. In this way about 40000 pixels are defined. Since each spiral element detects almost the same number of events in an experiment the whole system can be optimized for maximal counting rates. This paper describes a test setup for a first prototype of the Quirl-detector and the results of test measurements with an α-source. The detector current and the electrical separation of the spiral elements were measured. The splitting of signals due to the spread of charge carriers produced by an incident ionizing particle on several adjacent elements was investigated in detail and found to be twice as high as expected from calculations. Its influence on energy and position resolution is discussed. Electronic crosstalk via signal wires and the influence of noise from the magnetic spectrometer has been tested under experimental conditions. Additionally, vacuum feedthroughs based on printed Kapton foils pressed between Viton seals were fabricated and tested successfully concerning their vacuum and thermal properties. (orig.)

An analysis of the potassium concentrations of soft drinks by HPGe gamma spectrometry

International Nuclear Information System (INIS)

Guillermo Espinosa; Jose-Ignacio Golzarri; Ilsa Hernandez-Ibinarriaga

2009-01-01

Potassium, in a variety of compounds, occurs in abundance in the Earth's crust, and is an essential nutrient for human health. A naturally occurring radioactive isotope of potassium, 40 K, is found in the food and water that we consume. This paper presents the results of a gamma spectrometry analysis of the 40 K concentrations of a selection of commercial soft drinks. The 40 K concentrations are used to calculate the overall potassium concentrations. The analysis was carried out using a hyper-pure germanium (HPGe) detector with Ortec R ASPEC-927 multichannel analyzer module and GammaVision R software. This system was chosen for its high resolution and automatic data processing. The carbonated soft drinks (sodas) Coca-Cola R , Coca-Cola Light R (sold as Diet Coke R in the USA and other countries), Coca-Cola Zero R , Pepsi R , Pepsi Light R , Pepsi Max R , Big Cola R , Lulu-Cola R , Manzana Lift R , Sprite R and Fanta R and the mineral waters Ciel R and Penafiel R were analyzed. These brands are all international registered trademarks. The products analyzed were manufactured and bottled in Mexico. The results show a great variety of potassium concentrations in the different soft drinks analyzed (from 128.0 to 1113.1 mg/L). The concentration of potassium in the sodas, in conjunction with the amounts drank by one person in a year (180 L/year), are high enough to warrant consideration by public health authorities and by people to whom high potassium intakes pose a risk. (author)

Environmental Studies of Natural Radioactivity at Nugrus -Sikait Area, South Eastern Desert, Egypt

International Nuclear Information System (INIS)

Sroor, A.; EI-Shershaby, A.; EI- Bahi, S.; Ali, N.; Ibrahim, M.E.

2008-01-01

Twenty seven representative samples were collected from two locations; Wadi Nugrus and Wadi Sikait, south Eastern Desert, Egypt. The area is characterized by abnormal radioactivity and has several archaeological sites (Sikait Temple). Emerald mining is a wide spread activity since Pharonic times at Sikait - Nugrus area. The concentration of the natural radionuclides ( 238 U-series, 232 Th-series and 40 K) are measured in all the rock samples by two techniques (HpGe detector and NaI(TI) detector). The Ra e q, and H e x for all samples are also determined. A comparative study between NaI and HpGe- detectors were carried out. The present work indicated that the equilibrium/disequilibrium ratios by using HpGe detector are more precise than that of Nal detectors. The radioactivity at Wadi Nugrus is higher than Wadi Sikait and also higher than the permissible level

Concrete Image Segmentation Based on Multiscale Mathematic Morphology Operators and Otsu Method

Directory of Open Access Journals (Sweden)

Sheng-Bo Zhou

2015-01-01

Full Text Available The aim of the current study lies in the development of a reformative technique of image segmentation for Computed Tomography (CT concrete images with the strength grades of C30 and C40. The results, through the comparison of the traditional threshold algorithms, indicate that three threshold algorithms and five edge detectors fail to meet the demand of segmentation for Computed Tomography concrete images. The paper proposes a new segmentation method, by combining multiscale noise suppression morphology edge detector with Otsu method, which is more appropriate for the segmentation of Computed Tomography concrete images with low contrast. This method cannot only locate the boundaries between objects and background with high accuracy, but also obtain a complete edge and eliminate noise.

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

Design of large size segmented GEM foils and Drift PCB for CBM MUCH

International Nuclear Information System (INIS)

Saini, J.; Dubey, A.K.; Chattopadhyay, S.

2016-01-01

Triple GEM (Gas Electron Multiplier), sector shaped detectors will be used for Muon tracking in the Compressed Baryonic Matter (CBM) experiment at Anti-proton Ion Research (FAIR) facility at Darmstadt, Germany. The sizes of the detectors modules in the Muon Chambers (MUCH) are of the order of 1 meter with active area of about 75cms. Progressive pad geometry is chosen for the readout from these detectors. In construction of these chambers, three GEM foils are stacked on top of each other in a 3/2/2/2 gap configuration. The GEM foils are double layered copper clad 50μm thin Kapton foil. Each GEM foil has millions of holes on it. Foils of large surface area are prone to damages due to discharges owing to the high capacitance of the foil. Hence, these foils have their top surfaces divided into segments of about 100 sq.cm. Further segmentation may be necessary when there are high rate requirements, as in the case of CBM. For the GEM foils of CBM MUCH, a 24 segment layout has been adopted. Short-circuit in any of the GEM-holes will make entire foil un-usable. To reduce such occurrences, segment to segment isolation using opto-coupler in series with the GEM-foil segments has been introduced. Hence, a novel design for GEM chamber drift-PCB and foils has been made. In this scheme, each segment is powered and controlled individually. At the same time, the design takes into account, the space constraints, not only in x-y plane, but also in the z, due to compact assembly of MUCH detector layers

Monitoring of absolute mirror alignment at COMPASS RICH-1 detector

NARCIS (Netherlands)

Alexeev, M.; Birsa, R.; Bradamante, F.; Bressan, A.; Chiosso, M.; Ciliberti, P.; Dalla Torre, S.; Denisov, O.; Duic, V.; Ferrero, A.; Finger, M.; Finger, M.; Gayde, J. Ch; Giorgi, M.; Gobbo, B.; Levorato, S.; Maggiora, A.; Martin, A.; Menon, G.; Panzieri, D.; Pesaro, G.; Polak, J.; Rocco, E.; Sbrizzai, G.; Schiavon, P.; Slunecka, M.; Sozzi, F.; Steiger, L.; Sulc, M.; Takekawa, S.; Tessarotto, F.

2014-01-01

The gaseous COMPASS RICH-1 detector uses two spherical mirror surfaces, segmented into 116 individual mirrors, to focus the Cherenkov photons onto the detector plane. Any mirror misalignment directly affects the detector resolution. The on-line Continuous Line Alignment and Monitoring (CLAM)

Parallel segmented outlet flow high performance liquid chromatography with multiplexed detection

International Nuclear Information System (INIS)

Camenzuli, Michelle; Terry, Jessica M.; Shalliker, R. Andrew; Conlan, Xavier A.; Barnett, Neil W.; Francis, Paul S.

2013-01-01

Graphical abstract: -- Highlights: •Multiplexed detection for liquid chromatography. •‘Parallel segmented outlet flow’ distributes inner and outer portions of the analyte zone. •Three detectors were used simultaneously for the determination of opiate alkaloids. -- Abstract: We describe a new approach to multiplex detection for HPLC, exploiting parallel segmented outlet flow – a new column technology that provides pressure-regulated control of eluate flow through multiple outlet channels, which minimises the additional dead volume associated with conventional post-column flow splitting. Using three detectors: one UV-absorbance and two chemiluminescence systems (tris(2,2′-bipyridine)ruthenium(III) and permanganate), we examine the relative responses for six opium poppy (Papaver somniferum) alkaloids under conventional and multiplexed conditions, where approximately 30% of the eluate was distributed to each detector and the remaining solution directed to a collection vessel. The parallel segmented outlet flow mode of operation offers advantages in terms of solvent consumption, waste generation, total analysis time and solute band volume when applying multiple detectors to HPLC, but the manner in which each detection system is influenced by changes in solute concentration and solution flow rates must be carefully considered

Parallel segmented outlet flow high performance liquid chromatography with multiplexed detection

Energy Technology Data Exchange (ETDEWEB)

Camenzuli, Michelle [Australian Centre for Research on Separation Science (ACROSS), School of Science and Health, University of Western Sydney (Parramatta), Sydney, NSW (Australia); Terry, Jessica M. [Centre for Chemistry and Biotechnology, School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3216 (Australia); Shalliker, R. Andrew, E-mail: r.shalliker@uws.edu.au [Australian Centre for Research on Separation Science (ACROSS), School of Science and Health, University of Western Sydney (Parramatta), Sydney, NSW (Australia); Conlan, Xavier A.; Barnett, Neil W. [Centre for Chemistry and Biotechnology, School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3216 (Australia); Francis, Paul S., E-mail: paul.francis@deakin.edu.au [Centre for Chemistry and Biotechnology, School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3216 (Australia)

2013-11-25

Graphical abstract: -- Highlights: •Multiplexed detection for liquid chromatography. •‘Parallel segmented outlet flow’ distributes inner and outer portions of the analyte zone. •Three detectors were used simultaneously for the determination of opiate alkaloids. -- Abstract: We describe a new approach to multiplex detection for HPLC, exploiting parallel segmented outlet flow – a new column technology that provides pressure-regulated control of eluate flow through multiple outlet channels, which minimises the additional dead volume associated with conventional post-column flow splitting. Using three detectors: one UV-absorbance and two chemiluminescence systems (tris(2,2′-bipyridine)ruthenium(III) and permanganate), we examine the relative responses for six opium poppy (Papaver somniferum) alkaloids under conventional and multiplexed conditions, where approximately 30% of the eluate was distributed to each detector and the remaining solution directed to a collection vessel. The parallel segmented outlet flow mode of operation offers advantages in terms of solvent consumption, waste generation, total analysis time and solute band volume when applying multiple detectors to HPLC, but the manner in which each detection system is influenced by changes in solute concentration and solution flow rates must be carefully considered.

Segmented slant hole collimator for stationary cardiac SPECT: Monte Carlo simulations.

Science.gov (United States)

Mao, Yanfei; Yu, Zhicong; Zeng, Gengsheng L

2015-09-01

This work is a preliminary study of a stationary cardiac SPECT system. The goal of this research is to propose a stationary cardiac SPECT system using segmented slant-hole collimators and to perform computer simulations to test the feasibility. Compared to the rotational SPECT, a stationary system has a benefit of acquiring temporally consistent projections. The most challenging issue in building a stationary system is to provide sufficient projection view-angles. A GATE (GEANT4 application for tomographic emission) Monte Carlo model was developed to simulate a two-detector stationary cardiac SPECT that uses segmented slant-hole collimators. Each detector contains seven segmented slant-hole sections that slant to a common volume at the rotation center. Consequently, 14 view-angles over 180° were acquired without any gantry rotation. The NCAT phantom was used for data generation and a tailored maximum-likelihood expectation-maximization algorithm was used for image reconstruction. Effects of limited number of view-angles and data truncation were carefully evaluated in the paper. Simulation results indicated that the proposed segmented slant-hole stationary cardiac SPECT system is able to acquire sufficient data for cardiac imaging without a loss of image quality, even when the uptakes in the liver and kidneys are high. Seven views are acquired simultaneously at each detector, leading to 5-fold sensitivity gain over the conventional dual-head system at the same total acquisition time, which in turn increases the signal-to-noise ratio by 19%. The segmented slant-hole SPECT system also showed a good performance in lesion detection. In our prototype system, a short hole-length was used to reduce the dead zone between neighboring collimator segments. The measured sensitivity gain is about 17-fold over the conventional dual-head system. The gate Monte Carlo simulations confirm the feasibility of the proposed stationary cardiac SPECT system with segmented slant

Segmented slant hole collimator for stationary cardiac SPECT: Monte Carlo simulations

Energy Technology Data Exchange (ETDEWEB)

Mao, Yanfei, E-mail: ymao@ucair.med.utah.edu [Department of Radiology, Utah Center for Advanced Imaging Research (UCAIR), University of Utah, Salt Lake City, Utah 84108 and Department of Bioengineering, University of Utah, Salt Lake City, Utah 84112 (United States); Yu, Zhicong [Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905 (United States); Zeng, Gengsheng L. [Department of Radiology, Utah Center for Advanced Imaging Research (UCAIR), University of Utah, Salt Lake City, Utah 84108 and Department of Engineering, Weber State University, Ogden, Utah 84408 (United States)

2015-09-15

Purpose: This work is a preliminary study of a stationary cardiac SPECT system. The goal of this research is to propose a stationary cardiac SPECT system using segmented slant-hole collimators and to perform computer simulations to test the feasibility. Compared to the rotational SPECT, a stationary system has a benefit of acquiring temporally consistent projections. The most challenging issue in building a stationary system is to provide sufficient projection view-angles. Methods: A GATE (GEANT4 application for tomographic emission) Monte Carlo model was developed to simulate a two-detector stationary cardiac SPECT that uses segmented slant-hole collimators. Each detector contains seven segmented slant-hole sections that slant to a common volume at the rotation center. Consequently, 14 view-angles over 180° were acquired without any gantry rotation. The NCAT phantom was used for data generation and a tailored maximum-likelihood expectation-maximization algorithm was used for image reconstruction. Effects of limited number of view-angles and data truncation were carefully evaluated in the paper. Results: Simulation results indicated that the proposed segmented slant-hole stationary cardiac SPECT system is able to acquire sufficient data for cardiac imaging without a loss of image quality, even when the uptakes in the liver and kidneys are high. Seven views are acquired simultaneously at each detector, leading to 5-fold sensitivity gain over the conventional dual-head system at the same total acquisition time, which in turn increases the signal-to-noise ratio by 19%. The segmented slant-hole SPECT system also showed a good performance in lesion detection. In our prototype system, a short hole-length was used to reduce the dead zone between neighboring collimator segments. The measured sensitivity gain is about 17-fold over the conventional dual-head system. Conclusions: The GATE Monte Carlo simulations confirm the feasibility of the proposed stationary cardiac

Baby MIND: a magnetized segmented neutrino detector for the WAGASCI experiment

Science.gov (United States)

Antonova, M.; Asfandiyarov, R.; Bayes, R.; Benoit, P.; Blondel, A.; Bogomilov, M.; Bross, A.; Cadoux, F.; Cervera, A.; Chikuma, N.; Dudarev, A.; Ekelöf, T.; Favre, Y.; Fedotov, S.; Hallsjö, S.-P.; Izmaylov, A.; Karadzhov, Y.; Khabibullin, M.; Khotyantsev, A.; Kleymenova, A.; Koga, T.; Kostin, A.; Kudenko, Y.; Likhacheva, V.; Martinez, B.; Matev, R.; Medvedeva, M.; Mefodiev, A.; Minamino, A.; Mineev, O.; Nessi, M.; Nicola, L.; Noah, E.; Ovsiannikova, T.; Pais Da Silva, H.; Parsa, S.; Rayner, M.; Rolando, G.; Shaykhiev, A.; Simion, P.; Soler, F. J. P.; Suvorov, S.; Tsenov, R.; Ten Kate, H.; Vankova-Kirilova, G.; Yershov, N.

2017-07-01

T2K (Tokai-to-Kamioka) is a long-baseline neutrino experiment in Japan designed to study various parameters of neutrino oscillations. A near detector complex (ND280) is located 280 m downstream of the production target and measures neutrino beam parameters before any oscillations occur. ND280's measurements are used to predict the number and spectra of neutrinos in the Super-Kamiokande detector at the distance of 295 km. The difference in the target material between the far (water) and near (scintillator, hydrocarbon) detectors leads to the main non-cancelling systematic uncertainty for the oscillation analysis. In order to reduce this uncertainty a new WAter-Grid-And-SCintillator detector (WAGASCI) has been developed. A magnetized iron neutrino detector (Baby MIND) will be used to measure momentum and charge identification of the outgoing muons from charged current interactions. The Baby MIND modules are composed of magnetized iron plates and long plastic scintillator bars read out at the both ends with wavelength shifting fibers and silicon photomultipliers. The front-end electronics board has been developed to perform the readout and digitization of the signals from the scintillator bars. Detector elements were tested with cosmic rays and in the PS beam at CERN. The obtained results are presented in this paper.

Baby MIND: a magnetized segmented neutrino detector for the WAGASCI experiment

International Nuclear Information System (INIS)

Antonova, M.; Fedotov, S.; Izmaylov, A.; Khabibullin, M.; Khotyantsev, A.; Kleymenova, A.; Asfandiyarov, R.; Blondel, A.; Cadoux, F.; Favre, Y.; Karadzhov, Y.; Bayes, R.; Hallsjö, S-P.; Benoit, P.; Dudarev, A.; Bogomilov, M.; Bross, A.; Cervera, A.; Chikuma, N.; Ekelöf, T.

2017-01-01

T2K (Tokai-to-Kamioka) is a long-baseline neutrino experiment in Japan designed to study various parameters of neutrino oscillations. A near detector complex (ND280) is located 280 m downstream of the production target and measures neutrino beam parameters before any oscillations occur. ND280's measurements are used to predict the number and spectra of neutrinos in the Super-Kamiokande detector at the distance of 295 km. The difference in the target material between the far (water) and near (scintillator, hydrocarbon) detectors leads to the main non-cancelling systematic uncertainty for the oscillation analysis. In order to reduce this uncertainty a new WAter-Grid-And-SCintillator detector (WAGASCI) has been developed. A magnetized iron neutrino detector (Baby MIND) will be used to measure momentum and charge identification of the outgoing muons from charged current interactions. The Baby MIND modules are composed of magnetized iron plates and long plastic scintillator bars read out at the both ends with wavelength shifting fibers and silicon photomultipliers. The front-end electronics board has been developed to perform the readout and digitization of the signals from the scintillator bars. Detector elements were tested with cosmic rays and in the PS beam at CERN. The obtained results are presented in this paper.

Baby MIND: A Magnetized Segmented Neutrino Detector for the WAGASCI Experiment

Energy Technology Data Exchange (ETDEWEB)

Antonova, M.; et al.

2017-07-19

T2K (Tokai-to-Kamioka) is a long-baseline neutrino experiment in Japan designed to study various parameters of neutrino oscillations. A near detector complex (ND280) is located 280 m downstream of the production target and measures neutrino beam parameters before any oscillations occur. ND280's measurements are used to predict the number and spectra of neutrinos in the Super-Kamiokande detector at the distance of 295 km. The difference in the target material between the far (water) and near (scintillator, hydrocarbon) detectors leads to the main non-cancelling systematic uncertainty for the oscillation analysis. In order to reduce this uncertainty a new WAter-Grid-And-SCintillator detector (WAGASCI) has been developed. A magnetized iron neutrino detector (Baby MIND) will be used to measure momentum and charge identification of the outgoing muons from charged current interactions. The Baby MIND modules are composed of magnetized iron plates and long plastic scintillator bars read out at the both ends with wavelength shifting fibers and silicon photomultipliers. The front-end electronics board has been developed to perform the readout and digitization of the signals from the scintillator bars. Detector elements were tested with cosmic rays and in the PS beam at CERN. The obtained results are presented in this paper.

Resistor-less charge sensitive amplifier for semiconductor detectors

Energy Technology Data Exchange (ETDEWEB)

Pelczar, K., E-mail: krzysztof.pelczar@doctoral.uj.edu.pl; Panas, K.; Zuzel, G.

2016-11-01

A new concept of a Charge Sensitive Amplifier without a high-value resistor in the feedback loop is presented. Basic spectroscopic parameters of the amplifier coupled to a coaxial High Purity Germanium detector (HPGe) are discussed. The amplifier signal input is realized with an n-channel J-FET transistor. The feedback capacitor is discharged continuously by the second, forward biased n-channel J-FET, driven by an RC low–pass filter. Both the analog—with a standard spectroscopy amplifier and a multi-channel analyzer—and the digital—by applying a Flash Analog to Digital Converter—signal readouts were tested. The achieved resolution in the analog and the digital readouts was 0.17% and 0.21%, respectively, at the Full Width at Half Maximum of the registered {sup 60}Co 1332.5 keV gamma line.

Calibration and application of a HPGe gamma spectrometer for in-situ measurements

International Nuclear Information System (INIS)

Xiao Xuefu; Yue Qingyu

1992-02-01

The principle and methods of the calibration for an in-situ γ spectrometer are introduced. The calibration for a portable HPGe γ spectrometer has been completed. The N f /A(peak count rate per unit activity in soil) and N f /D(peak count rate per unit absorbed dose rate in the air) are listed. The uncertainties of the calibration factors are estimated. The in-situ measurements have been carried out in surroundings near the nuclear facilities and the data are compared with those measured by other methods

235U enrichment determination on UF6 cylinders with CZT detectors

Science.gov (United States)

Berndt, Reinhard; Mortreau, Patricia

2018-04-01

Measurements of uranium enrichment in UF6 transit cylinders are an important nuclear safeguards verification task, which is performed using a non-destructive assay method, the traditional enrichment meter, which involves measuring the count rate of the 186 keV gamma ray. This provides a direct measure of the 235U enrichment. Measurements are typically performed using either high-resolution detectors (Germanium) with e-cooling and battery operation, or portable devices equipped with low resolution detectors (NaI). Despite good results being achieved when measuring Low Enriched Uranium in 30B type cylinders and natural uranium in 48Y type containers using both detector systems, there are situations, which preclude the use of one or both of these systems. The focus of this work is to address some of the recognized limitations in relation to the current use of the above detector systems by considering the feasibility of an inspection instrument for 235U enrichment measurements on UF6 cylinders using the compact and light Cadmium Zinc Telluride (CZT) detectors. In the present work, test measurements were carried out, under field conditions and on full-size objects, with different CZT detectors, in particular for situations where existing systems cannot be used e.g. for stacks of 48Y type containers with depleted uranium. The main result of this study shows that the CZT detectors, actually a cluster of four μCZT1500 micro spectrometers provide as good results as the germanium detector in the ORTEC Micro-trans SPEC HPGe Portable spectrometer, and most importantly in particular for natural and depleted uranium in 48Y cylinders.

Semi-empirical Calculation of Detection Efficiency for Voluminous Source Based on Effective Solid Angle Concept

Energy Technology Data Exchange (ETDEWEB)

Kang, M. Y.; Kim, J. H.; Choi, H. D.; Sun, G. M. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-10-15

To calculate the full energy (FE) absorption peak efficiency for arbitrary volume sample, we developed and verified the Effective Solid Angle (ESA) Code. The procedure for semi-empirical determination of the FE efficiency for the arbitrary volume sources and the calculation principles and processes about ESA code is referred to, and the code was validated with a HPGe detector (relative efficiency 32%, n-type) in previous studies. In this study, we use different type and efficiency of HPGe detectors, in order to verify the performance of the ESA code for the various detectors. We calculated the efficiency curve of voluminous source and compared with experimental data. We will carry out additional validation by measurement of various medium, volume and shape of CRM volume sources with detector of different efficiency and type. And we will reflect the effect of the dead layer of p-type HPGe detector and coincidence summing correction technique in near future.

Feasibility study of segmented-parallel-hole collimator for stationary cardiac SPECT

Energy Technology Data Exchange (ETDEWEB)

Mao, Yanfei [Utah Univ., Salt Lake City, UT (United States). Center for Advanced Imaging Research (UCAIR); Utah Univ., Salt Lake City, UT (United States). Dept. of Bioengineering; Zeng, Gengsheng L. [Utah Univ., Salt Lake City, UT (United States). Center for Advanced Imaging Research (UCAIR)

2011-07-01

The goal of this research is to propose a stationary cardiac SPECT system using the segmented parallel-beam collimator and to perform some computer simulations to test the feasibility. A stationary system has a benefit of acquiring temporally consistent projections. The most challenging issue in building a stationary system is to provide sufficient projection view-angles. A 2-detector, multi-segment collimator system with 14 view-angles over 180 in the transaxial direction and 3 view-angles in the axial directions was designed, where the two detectors are configured 90 apart in an L-shape. We applied the parallel-beam imaging geometry and used segmented parallel-hole collimator to acquire SPECT data. To improve the system condition due to data truncation, we measured more rays within the field-of-view (FOV) of the detector by using a relatively small detector bin-size. In image reconstruction, we used the maximum-likelihood expectation-maximization (ML-EM) algorithm. The criterion for evaluating the system is the summed pixel-to-pixel distance that measures the discrepancy between the 3D gold-standard image and the reconstructed 3D region of interest (ROI) with truncated data. Effects of limited number of view-angles, data truncation, varying body habitus, attenuation, and noise were considered in the system design. As a result, our segmented-parallel-beam stationary cardiac SPECT system is able to acquire sufficient data for cardiac imaging and has a high sensitivity gain. (orig.)

A Monte Carlo investigation of Swank noise for thick, segmented, crystalline scintillators for radiotherapy imaging

International Nuclear Information System (INIS)

Wang Yi; Antonuk, Larry E.; El-Mohri, Youcef; Zhao Qihua

2009-01-01

Thick, segmented scintillating detectors, consisting of 2D matrices of scintillator crystals separated by optically opaque septal walls, hold considerable potential for significantly improving the performance of megavoltage (MV) active matrix, flat-panel imagers (AMFPIs). Initial simulation studies of the radiation transport properties of segmented detectors have indicated the possibility of significant improvement in DQE compared to conventional MV AMFPIs based on phosphor screen detectors. It is therefore interesting to investigate how the generation and transport of secondary optical photons affect the DQE performance of such segmented detectors. One effect that can degrade DQE performance is optical Swank noise (quantified by the optical Swank factor I opt ), which is induced by depth-dependent variations in optical gain. In this study, Monte Carlo simulations of radiation and optical transport have been used to examine I opt and zero-frequency DQE for segmented CsI:Tl and BGO detectors at different thicknesses and element-to-element pitches. For these detectors, I opt and DQE were studied as a function of various optical parameters, including absorption and scattering in the scintillator, absorption at the top reflector and septal walls, as well as scattering at the side surfaces of the scintillator crystals. The results indicate that I opt and DQE are only weakly affected by absorption and scattering in the scintillator, as well as by absorption at the top reflector. However, in some cases, these metrics were found to be significantly degraded by absorption at the septal walls and scattering at the scintillator side surfaces. Moreover, such degradations are more significant for detectors with greater thickness or smaller element pitch. At 1.016 mm pitch and with optimized optical properties, 40 mm thick segmented CsI:Tl and BGO detectors are predicted to provide DQE values of ∼29% and 42%, corresponding to improvement by factors of ∼29 and 42

Determination of soil, sand and ore primordial radionuclide concentrations by full-spectrum analyses of high-purity germanium detector spectra

International Nuclear Information System (INIS)

Newman, R.T.; Lindsay, R.; Maphoto, K.P.; Mlwilo, N.A.; Mohanty, A.K.; Roux, D.G.; Meijer, R.J. de; Hlatshwayo, I.N.

2008-01-01

The full-spectrum analysis (FSA) method was used to determine primordial activity concentrations (ACs) in soil, sand and ore samples, in conjunction with a HPGe detector. FSA involves the least-squares fitting of sample spectra by linear combinations of 238 U, 232 Th and 40 K standard spectra. The differences between the FSA results and those from traditional windows analyses (using regions-of-interest around selected photopeaks) are less than 10% for all samples except zircon ore, where FSA yielded an unphysical 40 K AC

Neutron detector development at Brookhaven

International Nuclear Information System (INIS)

Yu, B.; Harder, J.A.; Mead, J.A.; Radeka, V.; Schaknowski, N.A.; Smith, G.C.

2003-01-01

Two-dimensional thermal neutron detectors have been the subject of research and development at Brookhaven for over 20 years. Based primarily on multi-wire chambers filled with a gas mixture containing 3 He, these detectors have been used in wide-ranging studies of molecular biology and material science samples. At each phase of development, experimenters have sought improvements in key parameters such as position resolution, counting rate, efficiency, solid-angle coverage and stability. A suite of detectors has been developed with sensitive areas ranging from 5x5 to 50x50 cm 2 . These devices incorporate low-noise-position readout and the best position resolution for thermal neutron gas detectors. Recent developments include a 1.5 mx20 cm detector containing multiple segments with continuously sensitive readout, and detectors with unity gain for ultra-high rate capability and long-term stability

Assessment of activity incorporated in human body by means of a HPGe-detector

Energy Technology Data Exchange (ETDEWEB)

Boshkova, T; Minev, L [Sofia Univ. (Bulgaria). Fizicheski Fakultet; Konstantinov, V [Kombinat Atomna Energetika, Kozloduj (Bulgaria)

1996-12-31

Human body models (phantoms) have been used to study relations between efficiency in measurement of radionuclide activity and measurement conditions. A comparison is made between the activity measurement with and without a motion. When the phantom is moved under the detector, an absolute efficiency increase of 30-40% in homogeneously distributed activity and 2-3 times increase in activity concentrated in the lungs are found. Incorrect calibration is found to introduce an error of 30-40% in the measurement with motion while without motion the error can reach 150-300%. The effects of object weight, size and shield are studied. A procedure for accurate measurement has been developed. The incorporated activity in a human body has been measured using this procedure. Two Kozloduy-2 staff members have been subject to measurement. Cs-137 activity was homogeneously distributed with values 175 Bq in person X and 1050 Bq in person Y. Co-60 activity was concentrated in the lungs with values of 110 Bq and 470 Bq respectively. 14 refs., 5 tabs.

Investigation of the PGNAA using the LaBr3 scintillation detector

International Nuclear Information System (INIS)

Favalli, A.; Mehner, H.-C.; Ciriello, V.; Pedersen, B.

2008-01-01

Full text: The Joint Research Centre of the European Commission develops instrumentation and analysis methods for the non-destructive assay of nuclear materials and for detection of contraband materials. In relation to this, a new experimental device was designed and constructed in the laboratory of the Institute for the Protection and the Security of the Citizen (IPSC), Nuclear Safeguards Unit. The device, called the Pulsed Neutron Interrogation Test Assembly (PUNITA), incorporates a pulsed (D-T) neutron generator. In the PUNITA facility we study the methods applying the detection of characteristic gamma rays subsequent to neutron irradiation. This includes the detection of prompt gamma rays from neutron inelastic scattering and neutron capture. The gamma ray energy from these reactions is characteristic for the target elements present in the sample. For the detection of materials such the device employs gamma detectors for characteristic prompt gamma rays. The gamma detectors include HPGe detectors and scintillation detectors based on the Lanthanum Bromide crystal. This new scintillation detector is particularly suited for the detection of activation gamma rays in the MeV range. To prepare the experimental and theoretical considerations with PUNITA facility some experiments have been carried out by means of conventional neutron sources. This work enables both to study gamma-ray spectra due to the prompt gamma rays emitted after the thermal neutron capture, to evaluate the performance of the new type of scintillation detectors for PGNAA applications. The paper presents and discusses the set-up employed and the results obtained so far

Aerial measurements in Finland

Energy Technology Data Exchange (ETDEWEB)

Winkelmann, I.; Thomas, M.; Buchroeder, H.; Brummer, C. [Federal Office for Radiation Protection, Berlin (Germany); Carloff, G. [German Federal Border Police, Grenzschutz-Fliegergruppe, Sankt Augustin (Germany)

1997-12-31

Aerial measurements were performed to determine the {sup 137}Cs soil contamination in a given region to detect unknown radiation sources and to assess their activity. For these measurements a computerized gamma ray spectrometer, equipped with a high purity Ge-semiconductor detector and a 12 l volume Nal(Tl)-detector was used. HPGe-detector measurements from different altitudes over area I were done to test and re-calibrate the aerial measuring system. The known {sup 137}Cs contamination of (50.7 {+-} 5.2) kBq m{sup -2} could be confirmed by the measured value of (57 {+-} 10) kBq m{sup -2}. the Nal(Tl)-detector was re-calibrated at that site for further {sup 137}Cs measurements over area II. The area II was surveyed from an altitude of about 70 m and at a parallel line distance of 150 m at an flying speed of 100 km h{sup -1} to determine the {sup 137}Cs soil contamination. The measuring time was two seconds for the Nal(Tl)-detector. For the spectra measured with the HPGe-detector, a measuring time of 30 s each was chosen. From the Nal(Tl)-measurements, a mean {sup 137}Cs value of (60 {+-} 20) kBq m{sup -2} was determined with a maximum value of 90 kBq m{sup -2}. The corresponding values measured by HPGe-detector were (70 {+-} 20) kBq m{sup -2} and 120 kBq m{sup -2}, respectively. For the evaluation of the HPGe-spectra a depth distribution parameter {alpha}/{rho} = (0.44 {+-} 0.21) cm{sup 2} g{sup -1} for {sup 137}Cs was used measured from soil samples. From data measured with the Nal(Tl)-detector during flights over area III, three{sup 60}Co-sources and one {sup 137}Cs source could be detected, localized and their activity assessed. By HPGe-detector measurements, only scattered {sup 192}lr radiation was registered. (au).

Aerial measurements in Finland

Energy Technology Data Exchange (ETDEWEB)

Winkelmann, I; Thomas, M; Buchroeder, H; Brummer, C [Federal Office for Radiation Protection, Berlin (Germany); Carloff, G [German Federal Border Police, Grenzschutz-Fliegergruppe, Sankt Augustin (Germany)

1998-12-31

Aerial measurements were performed to determine the {sup 137}Cs soil contamination in a given region to detect unknown radiation sources and to assess their activity. For these measurements a computerized gamma ray spectrometer, equipped with a high purity Ge-semiconductor detector and a 12 l volume Nal(Tl)-detector was used. HPGe-detector measurements from different altitudes over area I were done to test and re-calibrate the aerial measuring system. The known {sup 137}Cs contamination of (50.7 {+-} 5.2) kBq m{sup -2} could be confirmed by the measured value of (57 {+-} 10) kBq m{sup -2}. the Nal(Tl)-detector was re-calibrated at that site for further {sup 137}Cs measurements over area II. The area II was surveyed from an altitude of about 70 m and at a parallel line distance of 150 m at an flying speed of 100 km h{sup -1} to determine the {sup 137}Cs soil contamination. The measuring time was two seconds for the Nal(Tl)-detector. For the spectra measured with the HPGe-detector, a measuring time of 30 s each was chosen. From the Nal(Tl)-measurements, a mean {sup 137}Cs value of (60 {+-} 20) kBq m{sup -2} was determined with a maximum value of 90 kBq m{sup -2}. The corresponding values measured by HPGe-detector were (70 {+-} 20) kBq m{sup -2} and 120 kBq m{sup -2}, respectively. For the evaluation of the HPGe-spectra a depth distribution parameter {alpha}/{rho} = (0.44 {+-} 0.21) cm{sup 2} g{sup -1} for {sup 137}Cs was used measured from soil samples. From data measured with the Nal(Tl)-detector during flights over area III, three{sup 60}Co-sources and one {sup 137}Cs source could be detected, localized and their activity assessed. By HPGe-detector measurements, only scattered {sup 192}lr radiation was registered. (au).

Improving axion detection sensitivity in high purity germanium detector based experiments

Science.gov (United States)

Xu, Wenqin; Elliott, Steven

2015-04-01

Thanks to their excellent energy resolution and low energy threshold, high purity germanium (HPGe) crystals are widely used in low background experiments searching for neutrinoless double beta decay, e.g. the MAJORANA DEMONSTRATOR and the GERDA experiments, and low mass dark matter, e.g. the CDMS and the EDELWEISS experiments. A particularly interesting candidate for low mass dark matter is the axion, which arises from the Peccei-Quinn solution to the strong CP problem and has been searched for in many experiments. Due to axion-photon coupling, the postulated solar axions could coherently convert to photons via the Primakeoff effect in periodic crystal lattices, such as those found in HPGe crystals. The conversion rate depends on the angle between axions and crystal lattices, so the knowledge of HPGe crystal axis is important. In this talk, we will present our efforts to improve the HPGe experimental sensitivity to axions by considering the axis orientations in multiple HPGe crystals simultaneously. We acknowledge the support of the U.S. Department of Energy through the LANL/LDRD Program.

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

A novel line segment detection algorithm based on graph search

Science.gov (United States)

Zhao, Hong-dan; Liu, Guo-ying; Song, Xu

2018-02-01

To overcome the problem of extracting line segment from an image, a method of line segment detection was proposed based on the graph search algorithm. After obtaining the edge detection result of the image, the candidate straight line segments are obtained in four directions. For the candidate straight line segments, their adjacency relationships are depicted by a graph model, based on which the depth-first search algorithm is employed to determine how many adjacent line segments need to be merged. Finally we use the least squares method to fit the detected straight lines. The comparative experimental results verify that the proposed algorithm has achieved better results than the line segment detector (LSD).

The EUROBALL neutron wall - design and performance tests of neutron detectors

CERN Document Server

Skeppstedt, Ö; Lindström, L; Wadsworth, R; Hibbert, I; Kelsall, N; Jenkins, D; Grawe, H; aGórska, M; Moszynski, M; Sujkowski, Z; Wolski, D; Kapusta, M; Hellström, M; Kalogeropoulos, S; Oner, D; Johnson, A; Cederkäll, J; Klamra, W; Nyberg, J; Weiszflog, M; Kay, J; Griffiths, R; Garces-Narro, J; Pearson, C; Eberth, J

1999-01-01

The mechanical design of the EUROBALL neutron wall and neutron detectors, and their performance measured with a sup 2 sup 4 sup 6 sup , sup 2 sup 4 sup 8 Cm fission source are described. The array consists of 15 pseudohexaconical detector units subdivided into three, 149 mm high, hermetically separated segments and a smaller central pentagonal unit subdivided into five segments. The detectors are filled with Bicron BC501A liquid scintillator. Each section of the hexaconical detectors is viewed by a 130 mm diameter Philips XP4512PA photomultiplier while the sections of pentagonal detectors are viewed by Philips XP4312B PMTs. The tests of n-gamma discrimination performed by zero-crossing and time-of-flight methods show a full separation of gamma- and neutron events down to 50 keV recoil electron energy. These tests demonstrate the excellent timing properties of the detectors and an average time resolution of 1.56 ns. The factors determining the efficiency of neutron detectors are discussed. The total efficiency...

Investigation of the pulse shape analysis for the position sensitive γ-ray spectrometer AGATA

Energy Technology Data Exchange (ETDEWEB)

Lewandowski, Lars; Birkenbach, Benedikt; Reiter, Peter [Institut fuer Kernphysik Koeln (Germany); Collaboration: AGATA-Collaboration

2015-07-01

The next generation of γ-ray spectrometers like AGATA will provide high quality γ-ray spectra by the new Gamma-Ray Tracking technique (GRT). Position sensitive HPGe detectors will allow for precise Doppler correction and small broadening of lines for spectroscopy at relativistic energies. GRT is based on the interaction position of the γ-rays within the volume of the highly segmented germanium detectors provided by Pulse Shape Analysis (PSA) methods. The proof of principle of GRT was already demonstrated with great success however systematic deviations from expected results occur. The parameterization of the following detector properties and their impact on PSA were thoroughly investigated and optimized: electron and hole mobility, crystal axis orientation, space charge distributions, crystal impurities, response functions of preamplifiers and digitizers, linear and differential crosstalk, time alignment of pulses and the distance metric. Results of an improved PSA performance are presented.

Detector Development for the abBA Experiment.

Science.gov (United States)

Seo, P-N; Bowman, J D; Mitchell, G S; Penttila, S I; Wilburn, W S

2005-01-01

We have developed a new type of field-expansion spectrometer to measure the neutron beta decay correlations (a, b, B, and A). A precision measurement of these correlations places stringent requirements on charged particle detectors. The design employs large area segmented silicon detectors to detect both protons and electrons in coincidence. Other requirements include good energy resolution (electron-backscattering events, and nearly unity efficiency. We report results of testing commercially available surface-barrier silicon detectors for energy resolution and timing performance, and measurement of the dead-layer thickness of ion-implanted silicon detectors with a 3.2 MeV alpha source.

Highly accurate determination of relative gamma-ray detection efficiency for Ge detector and its application

International Nuclear Information System (INIS)

Miyahara, H.; Mori, C.; Fleming, R.F.; Dewaraja, Y.K.

1997-01-01

When quantitative measurements of γ-rays using High-Purity Ge (HPGe) detectors are made for a variety of applications, accurate knowledge of oy-ray detection efficiency is required. The emission rates of γ-rays from sources can be determined quickly in the case that the absolute peak efficiency is calibrated. On the other hand, the relative peak efficiencies can be used for determination of intensity ratios for plural samples and for comparison to the standard source. Thus, both absolute and relative detection efficiencies are important in use of γ-ray detector. The objective of this work is to determine the relative gamma-ray peak detection efficiency for an HPGe detector with the uncertainty approaching 0.1% . We used some nuclides which emit at least two gamma-rays with energies from 700 to 2400 keV for which the relative emission probabilities are known with uncertainties much smaller than 0.1%. The relative peak detection efficiencies were calculated from the measurements of the nuclides, 46 Sc, 48 Sc, 60 Co and 94 Nb, emitting two γ- rays with the emission probabilities of almost unity. It is important that various corrections for the emission probabilities, the cascade summing effect, and the self-absorption are small. A third order polynomial function on both logarithmic scales of energy and efficiency was fitted to the data, and the peak efficiency predicted at certain energy from covariance matrix showed the uncertainty less than 0.5% except for near 700 keV. As an application, the emission probabilities of the 1037.5 and 1212.9 keV γ-rays for 48 Sc were determined using the function of the highly precise relative peak efficiency. Those were 0.9777+0,.00079 and 0.02345+0.00017 for the 1037.5 and 1212.9 keV γ-rays, respectively. The sum of these probabilities is close to unity within the uncertainty which means that the certainties of the results are high and the accuracy has been improved considerably

Performance evaluation of portable HPGe with in situ object counting system (ISOCS) in direct thyroid radiobioassay

Energy Technology Data Exchange (ETDEWEB)

Park, Min Seok; Kwon, Tae Eun; Pak, Min Jung; Park, Se Young; Ha, Wi Ho; Jin, Young Woo [National Radiation Emergency Medical Center (NREMC), Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)

2016-12-15

To evaluate the internal radiation dose, various methods are required to identify and quantify radionuclides in human body. Internal contamination monitoring related with the radioiodine is generally performed by direct radiobioassay which used scintillator-based thyroid monitor. Recently, a semiconductor material such as high purity germanium (HPGe) has been used for in vivo radiobioassay. In this study, broad energy germanium (BEGe) which was a kind of HPGe was used for thyroid radiobioassay. BEGe shows good performance in the radiobioassay due to its high energy resolution. In Situ Object Counting System (ISOCS) was the efficiency calibration software developed by Canberra Industries. The efficiency calibration with this system was performed by the Monte Carlo method. It was useful method as alternative method of conventional calibration. The purpose of this study is to evaluate the performance of measuring radioiodine by means of ISOCS which is equipped with the portable HPG(Falcon 5000, Canberra Industries) in direct thyroid radiobioassay. The ISOCS software ensured compliance with the performance criteria in the radioiodine measurement. These results of participating in intercomparison program indicated the feasibility of applying ISOCS software to direct thyroid radiobioassay with more convenient procedure.

Hadron shower profile and direction measurements in a segmented calorimeter

International Nuclear Information System (INIS)

Auchincloss, P.; Blair, R.; Haber, C.

1982-01-01

Recently a test measurement was made to see how well the direction of the shower induced by neutrino interactions could be determined in the lab-E detector at Fermilab. While the calorimeter in lab-E has very coarse sampling compared to the detectors described at this workshop, the method used to sample the shower could be employed in other more finely segmented detectors. The shower angle resolution obtained (36 mr.FWHM) is largely constrained by the sampling. In this test pulse heights in 2mm. steps across the hadron shower at five points along the shower were recorded. This was done with 20 wires and 20 fast ADC's. A standard MWPC system intended to accomplish the same task would have required about 250 wires and 250 ADC channels. This considerable saving in system complexity should be possible for any system where finely segmented pulse height measurements are required

Automatic segmentation of mandible in panoramic x-ray

OpenAIRE

Abdi, Amir Hossein; Kasaei, Shohreh; Mehdizadeh, Mojdeh

2015-01-01

As the panoramic x-ray is the most common extraoral radiography in dentistry, segmentation of its anatomical structures facilitates diagnosis and registration of dental records. This study presents a fast and accurate method for automatic segmentation of mandible in panoramic x-rays. In the proposed four-step algorithm, a superior border is extracted through horizontal integral projections. A modified Canny edge detector accompanied by morphological operators extracts the inferior border of t...

Testing and Characterization of SuperCDMS Dark Matter Detectors

Energy Technology Data Exchange (ETDEWEB)

Shank, Benjamin [Stanford Univ., CA (United States)

2014-05-01

The Cryogenic Dark Matter Search (SuperCDMS) relies on collection of phonons and charge carriers in semiconductors held at tens of milliKelvin as handles for detection of Weakly Interacting Massive Particles (WIMPs). This thesis begins with a brief overview of the direct dark matter search (Chapter 1) and SuperCDMS detectors (Chapter 2). In Chapter 3, a 3He evaporative refrigerator facility is described. Results from experiments performed in-house at Stanford to measure carrier transport in high-purity germanium (HPGe) crystals operated at sub-Kelvin temperatures are presented in Chapter 4. Finally, in Chapter 5 a new numerical model and a time-domain optimal filtering technique are presented, both developed for use with superconducting Transition Edge Sensors (TESs), that provide excellent event reconstruction for single particle interactions in detectors read out with superconducting W-TESs coupled to energy-collecting films of Al. This thesis is not intended to be read straight through. For those new to CDMS or dark matter searches, the first two chapters are meant to be a gentle introduction for experimentalists. They are by no means exhaustive. The remaining chapters each stand alone, with different audiences.

Treatment of the X and γ rays lung monitoring spectra obtained by using HP-Ge detectors in case of exposures to uranium

International Nuclear Information System (INIS)

Berard, P.; Pourret, O.; Aussel, J.P.; Rongier, E.

1996-01-01

A lung monitoring counting spectrum can be described as a random phenomenon. Channel-by-channel Poisson-type modelling was verified for cases of pure background. When carrying out spectral analysis for qualitative research, one must work with the sum of the detectors. The quantification must be calculated detector by detector. Statistical tests make it possible to certify that one or several peaks are really present in the organism. The calculations are currently made with automatic spectral analysis, peak search, specific area, statistics and probability of the real presence of analytic photo peak taking into account the morphological parameters of the worker. The results are analysed detector by detector, with and without the background of the room. Detection limits obtained in Pierrelatte in monitoring measurement conditions were assessed for variable tissues covering the range of subjects to be examined. For each subject, the calculations are made taking into account the equivalent tissue thicknesses derived from individual morphological parameters. This method makes it possible to quantify lung activities with a detection limit of 3.9 Bq ( 235 U; thirty minutes counting time; reference man parameters) and to monitor exposure to the different compounds of uranium. (author)

High voltage distribution scheme for large size GEM detector

International Nuclear Information System (INIS)

Saini, J.; Kumar, A.; Dubey, A.K.; Negi, V.S.; Chattopadhyay, S.

2016-01-01

Gas Electron Multiplier (GEM) detectors will be used for Muon tracking in the Compressed Baryonic Matter (CBM) experiment at the Facility for Anti-proton Ion Research (FAIR) at Darmstadt, Germany. The sizes of the detector modules in the Muon chambers are of the order of 1 metre x 0.5 metre. For construction of these chambers, three GEM foils are used per chamber. These foils are made by two layered 50μm thin kapton foil. Each GEM foil has millions of holes on it. In such a large scale manufacturing of the foils, even after stringent quality controls, some of the holes may still have defects or defects might develop over the time with operating conditions. These defects may result in short-circuit of the entire GEM foil. A short even in a single hole will make entire foil un-usable. To reduce such occurrences, high voltage (HV) segmentation within the foils has been introduced. These segments are powered either by individual HV supply per segment or through an active HV distribution to manage such a large number of segments across the foil. Individual supplies apart from being costly, are highly complex to implement. Additionally, CBM will have high intensity of particles bombarding on the detector causing the change of resistive chain current feeding the GEM detector with the variation in the intensity. This leads to voltage fluctuations across the foil resulting in the gain variation with the particle intensity. Hence, a low cost active HV distribution is designed to take care of the above discussed issues

Comparison measure of natural radioactivity in environment specimen using HPGe and NaI(Tl) γ-ray spectrometer

International Nuclear Information System (INIS)

Zhou Chunlin; Han Feng; Li Tiantuo; Ma Wenyan; Di Yuming; Guo Huiping; Wu Yuelei

2000-01-01

The author reports the comparison results on natural radioactive nuclide contents of soil specimen from an uranium diggings with HPGe and NaI(Tl) γ-ray spectrometer. Relative method and athwart matrix method are used to analyze natural radioactive nuclide contents in samples of soil. The results are compared and are proven to be in accordance with each other

Determination of the detection efficiency of a HPGe detector by means of the MCNP 4A simulation code

International Nuclear Information System (INIS)

Leal, B.

2004-01-01

In the majority of the laboratories, the calibration in efficiency of the detector is carried out by means of the standard sources measurement of gamma photons that have a determined activity, or for matrices that contain a variety of radionuclides that can embrace the energy range of interest. Given the experimental importance that has the determination from the curves of efficiency to the effects of establishing the quantitative results, is appealed to the simulation of the response function of the detector used in the Regional Center of Nuclear Studies inside the energy range of 80 keV to 1400 keV varying the density of the matrix, by means of the application of the Monte Carlo code MCNP-4A. The adjustment obtained shows an acceptance grade in the range of 100 to 600 keV, with a smaller percentage discrepancy to 5%. (Author)

An improved segmented gamma scanning for radioactive waste drums

International Nuclear Information System (INIS)

Liu Cheng; Wang Dezhong; Bai Yunfei; Qian Nan

2010-01-01

In this paper, the equivalent radius of radioactive sources in each segment is determined by analyzing the different responses of the two identical detectors, and an improved segmented gamma scanning is used to assay waste drums containing mainly organic materials, and proved by an established simulation model. The simulated radioactivity distributions in homogenous waste drum and an experimental heterogeneous waste drum were compared with those of traditional segmented gamma scanning. The results show that our method is good in performance and can be used for analyzing the waste drums. (authors)

Coherently combining data between detectors for all-sky semi-coherent continuous gravitational wave searches

International Nuclear Information System (INIS)

Goetz, E; Riles, K

2016-01-01

We present a method for coherently combining short data segments from gravitational-wave detectors to improve the sensitivity of semi-coherent searches for continuous gravitational waves. All-sky searches for continuous gravitational waves from unknown sources are computationally limited. The semi-coherent approach reduces the computational cost by dividing the entire observation timespan into short segments to be analyzed coherently, then combined together incoherently. Semi-coherent analyses that attempt to improve sensitivity by coherently combining data from multiple detectors face a computational challenge in accounting for uncertainties in signal parameters. In this article, we lay out a technique to meet this challenge using summed Fourier transform coefficients. Applying this technique to one all-sky search algorithm called TwoSpect, we confirm that the sensitivity of all-sky, semi-coherent searches can be improved by coherently combining the short data segments, e.g., by up to 42% over a single detector for an all-sky search. For misaligned detectors, however, this improvement requires careful attention when marginalizing over unknown polarization parameters. In addition, care must be taken in correcting for differential detector velocity due to the Earth’s rotation for high signal frequencies and widely separated detectors. (paper)

Results from the crystal ball detector at SPEAR

International Nuclear Information System (INIS)

Bloom, E.D.

1979-11-01

The Crystal Ball detector is a device particularly suited to the measurement of photons with energies lower than 1 GeV. The detector has as its principal component a 16 radiation length thick, highly segmented shell of NaI(Tl) surrounding cylindrical, proportional, and magnetostrictive spark chambers. The main Ball and various elements of the central chambers cover 94% of 4π sr. Segmented endcap NaI(Tl) detectors of 20 radiation lengths behind magneto strictive spark chambers supplement the main Ball. The Ball and endcaps close the solid angle for charged particle and photon detection to 98% of 4π sr. In addition, detectors of interspersed iron and proportional tubes provide for μ-π separation over 15% of 4π sr, about theta/sub CM/ = 90 0 . In this report preliminary results are presented from the data obtained. In particular, QED at E/sub CM/ = 6.5 GeV, R/sub hadron/ and related inclusive distributions, eta branching fractions at J/psi and psi'', and a detailed study of the psionium system are discussed

Highly segmented CVD diamond detectors and high-resolution momentum measurements in knockout reactions; Hochsegmentierte CVD Diamant Detektoren und hochaufloesende Impulsmessungen in Knockout Reaktionen

Energy Technology Data Exchange (ETDEWEB)

Schwertel, Sabine

2009-11-26

highly segmented detectors with an efficiency {epsilon}>98 % could be built from this material. The diamond detectors were segmented in our laboratory and achieved a time resolution of {sigma}{sub t}=75 ps. Medium-size (25.4 x 25.4 mm{sup 2}) micro-strip detectors were tested at the FRS and at the ALADIN/LAND setup at GSI. The obtained position resolution was in the range of the strip size of 200 {mu}m. First full-size detectors (50 x 50 mm{sup 2}) will be completed soon. (orig.)

Performance analysis of indigenous spectroscopy system based on Lanthanum Bromide (LaBr3(Ce)) scintillation detector

International Nuclear Information System (INIS)

Kulkarni, C.P.; Punnal, Mahesh; Vinod, M.; Padmini, S.; Bhatnagar, P.V.; Behere, Anita; Kulkarni, D.B.; Paranjape, D.B.

2018-01-01

This paper presents detailed performance analysis of LaBr 3 (Ce) based compact spectroscopy system indigenously developed in Electronics Division BARC. The system incorporates state of the art low power electronic components along-with advanced spectroscopy software. Performance parameters and spectral response are experimentally determined and the results are presented in comparison with a standard HPGe system under similar test conditions. These experiments are conducted in Radiation Standards Section, RSSD in BARC using calibration sources for acquiring gamma spectrums in various combinations of source-to-detector (S-D) distances and acquisition times. The acquired data is used for deriving energy calibration and computing FWHM, dead time, count-rate (cps) and efficiency to evaluate system performance; particularly with smaller acquisition times as necessitated by field applications. Self activity of the detector is also determined experimentally and presented along-with comments on its effect on low count-rate applications

Performance of Geant4 in simulating semiconductor particle detector response in the energy range below 1 MeV

Science.gov (United States)

Soti, G.; Wauters, F.; Breitenfeldt, M.; Finlay, P.; Kraev, I. S.; Knecht, A.; Porobić, T.; Zákoucký, D.; Severijns, N.

2013-11-01

Geant4 simulations play a crucial role in the analysis and interpretation of experiments providing low energy precision tests of the Standard Model. This paper focuses on the accuracy of the description of the electron processes in the energy range between 100 and 1000 keV. The effect of the different simulation parameters and multiple scattering models on the backscattering coefficients is investigated. Simulations of the response of HPGe and passivated implanted planar Si detectors to β particles are compared to experimental results. An overall good agreement is found between Geant4 simulations and experimental data.

Development of a self-absorption correction method used for a HPGe detector by means of a Monte Carlo simulation

International Nuclear Information System (INIS)

Itadzu, Hidesuke; Iguchi, Tetsuo; Suzuki, Toshikazu

2013-01-01

Quantitative analysis for food products and natural samples, to determine the activity of each radionuclide, can be made by using a high-purity germanium (HPGe) gamma-ray spectrometer system. The analysis procedure is, in general, based upon the guidelines established by the Nuclear Safety Division of the Ministry of Education, Culture, Sports, Science and Technology in Japan (JP MEXT). In the case of gamma-ray spectrum analysis for large volume samples, re-entrant (marinelli) containers are commonly used. The effect of photon attenuation in a large-volume sample, so-called “self-absorption”, should be corrected for precise determination of the activity. As for marinelli containers, two accurate geometries are shown in the JP MEXT guidelines for 700 milliliter and 2 liter volumes. In the document, the functions to obtain the self-absorption coefficients for these specific shapes are also shown. Therefore, self-absorption corrections have been carried out only for these two containers with practical media. However, to measure radioactivity for samples in containers of volumes other than those described in the guidelines, the self-absorption correction functions must be obtained by measuring at least two standard multinuclide volume sources, which consist of different media or different linear attenuation coefficients. In this work, we developed a method to obtain these functions over a wide range of linear attenuation coefficients for self-absorption in various shapes of marinelli containers using a Monte Carlo simulation. This method was applied to a 1-liter marinelli container, which is widely used for the above quantitative analysis, although its self-absorption correction function has not yet been established. The validity of this method was experimentally checked through an analysis of natural samples with known activity levels. (author)

Characterization of Czochralski silicon detectors

OpenAIRE

Luukka, Panja-Riina

2006-01-01

This thesis describes the characterization of irradiated and non-irradiated segmented detectors made of high-resistivity (>1 kΩcm) magnetic Czochralski (MCZ) silicon. It is shown that the radiation hardness (RH) of the protons of these detectors is higher than that of devices made of traditional materials such as Float Zone (FZ) silicon or Diffusion Oxygenated Float Zone (DOFZ) silicon due to the presence of intrinsic oxygen (> 5 × 1017 cm−3). The MCZ devices therefore present an interesting ...

The hyperion particle-γ detector array

Energy Technology Data Exchange (ETDEWEB)

Hughes, R.O.; Burke, J.T.; Casperson, R.J.; Ota, S. [Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Fisher, S.; Parker, J. [Science, Technology and Engineering Division, Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Beausang, C.W. [Department of Physics, University of Richmond, 28 Westhampton Way, Richmond, VA 23173 (United States); Dag, M. [Cyclotron Institute, Texas A& M University, College Station, TX 77840 (United States); Humby, P. [Department of Physics, University of Richmond, 28 Westhampton Way, Richmond, VA 23173 (United States); Department of Physics, University of Surrey, Surrey GU27XH (United Kingdom); Koglin, J. [Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); McCleskey, E.; McIntosh, A.B.; Saastamoinen, A. [Cyclotron Institute, Texas A& M University, College Station, TX 77840 (United States); Tamashiro, A.S. [Department of Nuclear Science and Engineering, Oregon State University, Corvallis, OR 97331 (United States); Wilson, E. [Department of Physics, University of Richmond, 28 Westhampton Way, Richmond, VA 23173 (United States); Wu, T.C. [Department of Physics and Astronomy, University of Utah, Salt Lake City UT 84112-0830 (United States)

2017-06-01

Hyperion is a new high-efficiency charged-particle γ-ray detector array which consists of a segmented silicon telescope for charged-particle detection and up to fourteen high-purity germanium clover detectors for the detection of coincident γ rays. The array will be used in nuclear physics measurements and Stockpile Stewardship studies and replaces the STARLiTeR array. This article discusses the features of the array and presents data collected with the array in the commissioning experiment.

TH-CD-207B-06: Swank Factor of Segmented Scintillators in Multi-Slice CT Detectors: Pulse Height Spectra and Light Escape

Energy Technology Data Exchange (ETDEWEB)

Howansky, A; Peng, B; Lubinsky, A; Zhao, W [Stony Brook University, Stony Brook, NY (United States)

2016-06-15

Purpose: Pulse height spectra (PHS) have been used to determine the Swank factor of a scintillator by measuring fluctuations in its light output per x-ray interaction. The Swank factor and x-ray quantum efficiency of a scintillator define the upper limit to its imaging performance, i.e. DQE(0). The Swank factor below the K-edge is dominated by optical properties, i.e. variations in light escape efficiency from different depths of interaction, denoted e(z). These variations can be optimized to improve tradeoffs in x-ray absorption, light yield, and spatial resolution. This work develops a quantitative model for interpreting measured PHS, and estimating e(z) on an absolute scale. The method is used to investigate segmented ceramic GOS scintillators used in multi-slice CT detectors. Methods: PHS of a ceramic GOS plate (1 mm thickness) and segmented GOS array (1.4 mm thick) were measured at 46 keV. Signal and noise propagation through x-ray conversion gain, light escape, detection by a photomultiplier tube and dynode amplification were modeled using a cascade of stochastic gain stages. PHS were calculated with these expressions and compared to measurements. Light escape parameters were varied until modeled PHS agreed with measurements. The resulting estimates of e(z) were used to calculate PHS without measurement noise to determine the inherent Swank factor. Results: The variation in e(z) was 67.2–89.7% in the plate and 40.2–70.8% in the segmented sample, corresponding to conversion gains of 28.6–38.1 keV{sup −1} and 17.1–30.1 keV{sup −1}, respectively. The inherent Swank factors of the plate and segmented sample were 0.99 and 0.95, respectively. Conclusion: The high light escape efficiency in the ceramic GOS samples yields high Swank factors and DQE(0) in CT applications. The PHS model allows the intrinsic optical properties of scintillators to be deduced from PHS measurements, thus it provides new insights for evaluating the imaging performance of

Determination of 137Cs and 210Pb using HPGe γ spectrometry as influenced by different sieve diameters

International Nuclear Information System (INIS)

Liu Yehan; Yu Hanqing; Geng Xiaochen; Li Yong

2012-01-01

Standard sieve diameter is often set as 2.00 mm to determine specific activity of 137 Cs and 210 Pb in soil samples, but it is rarely reported that whether the size of the different screening will affect the accuracy of such determination. In this study, three representative soils were employed to assess the effects of different sieve sizes on measurement of 137 Cs and 210 Pb activity in soil samples by using HPGe γ spectrometer. The targeted soil samples each were screened through the four sieve diameters 2.00, 1.00, 0.50 and 0.25 mm, respectively. It was observed that the sample of 0.25 mm took less time to reach the acceptable value of 137 Cs analysis precision and higher value of the specific activity in the three soils compared to the 2.00 mm sifting sample. As for 210 Pb measurement, the decrease of sieve diameters extended to touch the acceptable value of analysis precision but showed no significant effect on the specific activity. These results played an important role in enhancing the analysis precision of the specific activity of 137 Cs and 210 Pb in soil samples using HPGe γ Spectrometry. (authors)

Radiation detectors for use in major public events: classification, requirements, main features, tests and lessons learned

Energy Technology Data Exchange (ETDEWEB)

Souza, Elder Magalhães de, E-mail: elder@ird.gov.br [Instituto de Radioproteção e Dosimetria (DIRAD/IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Div. de Radiometria

2017-07-01

Since September 11, 2001, we have entered a new terrorism era. The possibility of the use of lost/stolen radioactive materials increases the probability of a radiological threat. The real goal intended with the use of a Radiological Dispersal Device (RRD or dirty bomb) or a Radiation Exposure Device (RDE) could be psychological in nature. Panic in the venues and surrounding area would cause more deaths than the RDD itself, therefore these attempts could cause chaos, injury, fear and terror, the main target of terrorists. The response of the national authorities with the support and aid of the IAEA served as an increase of the capability of detection and identification of nuclear and radiological materials. But this response could not be limited only to the MPE, because if the country has radioactive or nuclear facilities they also should be considered in terms of theft, sabotage, illegal transfer, unauthorized access, and any other malicious acts. In 2007, Rio de Janeiro, received the first Brazilian Major Public Event in this new era. This was the first Brazilian operation which largely utilized detectors (personal radiations detectors -PRD- radiological identification detectors, -RID or RIID- and spectral radiations scanners, -backpacks-, HPGe detectors, car-borne and air-borne systems) to protect the venues, the athletes, the population and the environment. (author)

Radiation detectors for use in major public events: classification, requirements, main features, tests and lessons learned

International Nuclear Information System (INIS)

Souza, Elder Magalhães de

2017-01-01

Since September 11, 2001, we have entered a new terrorism era. The possibility of the use of lost/stolen radioactive materials increases the probability of a radiological threat. The real goal intended with the use of a Radiological Dispersal Device (RRD or dirty bomb) or a Radiation Exposure Device (RDE) could be psychological in nature. Panic in the venues and surrounding area would cause more deaths than the RDD itself, therefore these attempts could cause chaos, injury, fear and terror, the main target of terrorists. The response of the national authorities with the support and aid of the IAEA served as an increase of the capability of detection and identification of nuclear and radiological materials. But this response could not be limited only to the MPE, because if the country has radioactive or nuclear facilities they also should be considered in terms of theft, sabotage, illegal transfer, unauthorized access, and any other malicious acts. In 2007, Rio de Janeiro, received the first Brazilian Major Public Event in this new era. This was the first Brazilian operation which largely utilized detectors (personal radiations detectors -PRD- radiological identification detectors, -RID or RIID- and spectral radiations scanners, -backpacks-, HPGe detectors, car-borne and air-borne systems) to protect the venues, the athletes, the population and the environment. (author)

Optimisation of a dual head semiconductor Compton camera using Geant4

Energy Technology Data Exchange (ETDEWEB)

Harkness, L.J. [Department of Physics, University of Liverpool, Oliver Lodge Laboratory, Liverpool L697ZE (United Kingdom)], E-mail: ljh@ns.ph.liv.ac.uk; Boston, A.J.; Boston, H.C.; Cooper, R.J.; Cresswell, J.R.; Grint, A.N.; Nolan, P.J.; Oxley, D.C.; Scraggs, D.P. [Department of Physics, University of Liverpool, Oliver Lodge Laboratory, Liverpool L697ZE (United Kingdom); Beveridge, T.; Gillam, J. [School of Physics and Materials Engineering, Monash University, Melbourne (Australia); Lazarus, I. [STFC Daresbury Laboratory, Warrington, Cheshire (United Kingdom)

2009-06-01

Conventional medical gamma-ray camera systems utilise mechanical collimation to provide information on the position of an incident gamma-ray photon. Systems that use electronic collimation utilising Compton image reconstruction techniques have the potential to offer huge improvements in sensitivity. Position sensitive high purity germanium (HPGe) detector systems are being evaluated as part of a single photon emission computed tomography (SPECT) Compton camera system. Data have been acquired from the orthogonally segmented planar SmartPET detectors, operated in Compton camera mode. The minimum gamma-ray energy which can be imaged by the current system in Compton camera configuration is 244 keV due to the 20 mm thickness of the first scatter detector which causes large gamma-ray absorption. A simulation package for the optimisation of a new semiconductor Compton camera has been developed using the Geant4 toolkit. This paper will show results of preliminary analysis of the validated Geant4 simulation for gamma-ray energies of SPECT, 141 keV.

CHICO, a heavy ion detector for Gammasphere

International Nuclear Information System (INIS)

Simon, M.W.; Cline, D.; Wu, C.Y.; Gray, R.W.; Teng, R.; Long, C.

2000-01-01

A 4π position-sensitive heavy-ion detector system, CHICO, has been developed primarily for use in conjunction with the 4π γ-ray facility, Gammasphere. The CHICO detector comprises an array of 20 Parallel Plate Avalanche Counters (PPACs) covering 12 deg. <θ<85 deg. and 95 deg. <θ<168 deg. and 280 deg. in phi. The PPACs have segmented delay-line cathode boards, measuring the polar scattering angle θ to 1 deg., and segmented anodes, measuring the azimuthal angle phi with 9 deg. resolution, while measuring the time-of-flight difference with 500 ps resolution. For binary reactions the kinematics can be reconstructed from the measured information, allowing identification of the target- and projectile-like nuclei with a mass resolution of Δm/m∼5%. The measured masses, recoil velocities, and recoil angles allow correction for Doppler shift and assignment of individual γ-rays to decay of the correct reaction product. This paper describes the design, operation and performance of the CHICO detector. The powerful combination of CHICO plus Gammasphere provides new research opportunities for the study of nuclear structure and reactions

User-guided segmentation for volumetric retinal optical coherence tomography images

Science.gov (United States)

Yin, Xin; Chao, Jennifer R.; Wang, Ruikang K.

2014-01-01

Abstract. Despite the existence of automatic segmentation techniques, trained graders still rely on manual segmentation to provide retinal layers and features from clinical optical coherence tomography (OCT) images for accurate measurements. To bridge the gap between this time-consuming need of manual segmentation and currently available automatic segmentation techniques, this paper proposes a user-guided segmentation method to perform the segmentation of retinal layers and features in OCT images. With this method, by interactively navigating three-dimensional (3-D) OCT images, the user first manually defines user-defined (or sketched) lines at regions where the retinal layers appear very irregular for which the automatic segmentation method often fails to provide satisfactory results. The algorithm is then guided by these sketched lines to trace the entire 3-D retinal layer and anatomical features by the use of novel layer and edge detectors that are based on robust likelihood estimation. The layer and edge boundaries are finally obtained to achieve segmentation. Segmentation of retinal layers in mouse and human OCT images demonstrates the reliability and efficiency of the proposed user-guided segmentation method. PMID:25147962

Simulated performance of the in-beam conversion-electron spectrometer, SPICE

Energy Technology Data Exchange (ETDEWEB)

Ketelhut, S., E-mail: ketelhut@triumf.ca [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada V6T 2A3 (Canada); Evitts, L.J.; Garnsworthy, A.B.; Bolton, C.; Ball, G.C.; Churchman, R. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada V6T 2A3 (Canada); Dunlop, R. [Department of Physics, University of Guelph, Guelph, Ontario, Canada N1G 2W1 (Canada); Hackman, G.; Henderson, R.; Moukaddam, M. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada V6T 2A3 (Canada); Rand, E.T.; Svensson, C.E. [Department of Physics, University of Guelph, Guelph, Ontario, Canada N1G 2W1 (Canada); Witmer, J. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada V6T 2A3 (Canada)

2014-07-01

The SPICE spectrometer is a new in-beam electron spectrometer designed to operate in conjunction with the TIGRESS HPGe Clover array at TRIUMF-ISAC. The spectrometer consists of a large area, annular, segmented lithium-drifted silicon electron detector shielded from the target by a photon shield. A permanent magnetic lens directs electrons around the photon shield to the detector. Experiments will be performed utilising Coulomb excitation, inelastic-scattering, transfer and fusion–evaporation reactions using stable and radioactive ion beams with suitable heavy-ion detection. Good detection efficiency can be achieved in a large energy range up to 3500 keV electron energy using several magnetic lens designs which are quickly interchangeable. COMSOL and Geant4 simulations have been used to maximise the detection efficiency. In addition, the simulations have guided the design of components to minimise the contributions from various sources of backgrounds.

Accuracy and precision of loss-free counting in γ-ray spectrometry

International Nuclear Information System (INIS)

Pomme, S.; Alzetta, J-P.; Uyttenhove, J.; Denecke, B.; Arana, G.; Robouch, P.

1999-01-01

The performance of a 'Loss-Free Counting' (LFC) method for pulse loss compensation is tested on two HPGe detectors; one with classical RC feedback preamplifier and another with Transistor Reset Preamplifier (TRP). Results are excellent on both, though extra fine-tuning precautions are required for the latter. Pulse loss by pileup is at the origin of an increased count variance in LFC spectra. A new formula for LFC uncertainty is presented and its validity demonstrated for a HPGe detector set-up

320-detector row CT coronary angiography in patients with arrhythmia

International Nuclear Information System (INIS)

Lu Li; Zhang Zhaoqi; Xu Lei; Yang Lin

2011-01-01

Objective: To evaluate the feasibility of CT coronary angiography (CTCA) in patients with arrhythmia using 320-detector row CT. Methods: Thirty-one patients with persistent atrial fibrillation and 8 patients with premature ventricular contraction were enrolled in this study. All patients underwent 320- detector row CTCA. CT image quality was evaluated with 4-point grading scale by two radiologists. Inter- observer agreement was evaluated by Kappa statistics. The radiation dose was calculated. Results: In total 510 coronary segments, 496 (97.2%) segments met diagnostic standard. The mean effective dose was (12.7±4.8) mSv in this study. There was a good agreement in image quality scoring between the two reviewers (Kappa = 0.72). Conclusion: 320-detector row CTCA is feasible in patients with atrial fibrillation and premature ventricular contraction. Arrhythmia may not be considered as a contraindication to CTCA. (authors)

Background studies for NaI(Tl) detectors in the ANAIS dark matter project

International Nuclear Information System (INIS)

Amaré, J.; Borjabad, S.; Cebrián, S.; Cuesta, C.; Fortuño, D.; García, E.; Ginestra, C.; Gómez, H.; Martínez, M.; Oliván, M. A.; Ortigoza, Y.; Solórzano, A. Ortiz de; Pobes, C.; Puimedón, J.; Sarsa, M. L.; Villar, J. A.; Villar, P.

2013-01-01

Several large NaI(Tl) detectors, produced by different companies, have been operated in the Canfranc Underground Laboratory (LSC) in the frame of the ANAIS (Annual modulation with NaI Scintillators) project devoted to the direct detection of dark matter. A complete background model has been developed for a 9.6 kg detector (referred as ANAIS-0 prototype) after a long data taking at LSC. Activities from the natural chains of 238 U and 232 Th, and 40 K in the NaI(Tl) crystal were evaluated applying different methods: discrimination of alpha particles vs beta/gamma background by Pulse Shape Analysis for quantifying the content of the natural chains and coincidence techniques for 40 K. Radioactive contaminations in the detector and shielding components were also determined by HPGe spectrometry. Monte Carlo simulations using Geant4 package were carried out to evaluate their contribution. At high energies, most of the measured background is nicely reproduced; at low energy some non-explained components are still present, although some plausible background sources have been analyzed. The 40 K content of the NaI(Tl) crystal has been confirmed to be the dominant contributor to the measured background with this detector. In addition, preliminary results of the background characterization, presently underway at the LSC, of two recently produced NaI(Tl) detectors, with 12.5 kg mass each, will be presented: cosmogenic induced activity has been clearly observed and is being quantified, and 40 K activity at a level ten times lower than in ANAIS-0 has been determined

Data acquisition for the HILI [Heavy Ion Light Ion] detector

International Nuclear Information System (INIS)

Teh, K.M.; Shapira, D.; McConnell, J.W.; Kim, H.; Novotny, R.

1987-01-01

A large acceptance, multi-segmented detector system capable of the simultaneous detection of heavy and light ions has been constructed. The heavy ions are detected with a segmented gas ionization chamber and a multiwire proportional counter while the light ions are detected with a 192 element plastic phoswich hodoscope. Processing the large number of signals is accomplished through a combination of CAMAC and FASTBUS modules and preprocessors, and a Host minicomputer. Details of the data acquisition system and the reasons for adopting a dual standards system are discussed. In addition, a technique for processing signals from an individual hodoscope detector is presented. 4 refs., 3 figs

Determination of radionuclides for river sediment CRM with HPGe gamma-ray spectrometer

International Nuclear Information System (INIS)

Tan Jinbo; Hao Runlong; Tang Zhenxin

1994-01-01

The authors described the method and results for determination of seven radionuclides: 238 U, 235 U, 226 Ra, 232 Th, 40 K, 60 Co and 137 Cs in the river sediment Certified Reference Material (CRM) using a HPGe gamma-ray spectrometer. The accuracy and reliability of measurement results were improved through varieties of techniques, which include: precise calibration of the gamma-ray spectrometer, coincidence summing correction and interference peak correction, two kinds of peak analysis methods (TPA and function fit), and utilization of as many as possible characteristic gamma-rays. Present measurement results for the seven radionuclides were in agreement with the verification results of the CRM with 1 σ or 2σ uncertainty, and its relative deviation were in the range of +1.0%--6.5%

Development of a CZT drift ring detector for X and γ ray spectroscopy

Science.gov (United States)

Alruhaili, A.; Sellin, P. J.; Lohstroh, A.; Boothman, V.; Veeramani, P.; Veale, M. C.; Sawhney, K. J. S.; Kachkanov, V.

2015-04-01

CdTe and CZT detectors are considered better choices for high energy γ and X-ray spectroscopy in comparison to Si and HPGe detectors due to their good quantum efficiency and room temperature operation. The performance limitations in CdTe and CZT detectors are mainly associated with poor hole transport and trapping phenomena. Among many techniques that can be used to eliminate the effect of the poor charge transport properties of holes in CdTe and CZT material, the drift ring technique shows promising results. In this work, the performance of a 2.3 mm thick CZT drift ring detector is investigated. Spatially resolved measurements were carried out with an X-ray microbeam (25 and 75 keV) at the Diamond Light Source synchrotron to study the response uniformity and extent of the active area. Higher energy photon irradiation was also carried out at up to 662 keV using different radioisotopes to complement the microbeam data. Different biasing schemes were investigated in terms of biasing the cathode rear electrode (bulk field) and the ring electrodes (lateral fields). The results show that increasing the bulk field with fixed-ratio ring biases and lateral fields with fixed bulk fields increase the active area of the device significantly, which contrasts with previous studies in CdTe, where only an increasing lateral field resulted in an improvement of device performance. This difference is attributed to the larger thickness of the CZT device reported here.

The sixfold segmented MINIBALL module simulation and experiment

International Nuclear Information System (INIS)

Gund, C.

2000-01-01

MINIBALL, the new γ-ray spectrometer for REX-ISOLDE and other radioactive beam experiments consists of 42 encapsulated, six-fold segmented germanium modules of the EUROBALL geometry, clustered in cryostats of three modules (3-Cluster). The high full-energy-peak efficiency of the spectrometer allows γ-ray spectroscopy of low intensity beams, the high granularity permits a good energy resolution after Doppler correction, in spite of the high velocity of the γ-emitting reaction products. Detailed simulations were performed to investigate the physical limits of the detector granularity using the segment energies and pulse-shape analysis. Algorithms to locate the γ-ray entry point into the detector were developed. Special attention was paid to the application of these algorithms to the 3-Cluster detector. A position resolution of the γ-ray entry point of 10 mm x 10 mm was obtained and experimentally verified. Finally predictions for the energy resolution after Doppler correction were deduced. An experiment was performed to investigate the problems of low-intensity experiments in inverse kinematics. The use of the MINIBALL germanium modules in conjunction with the REX-ISOLDE PPAC allowed to solve these problems, a good energy resolution and a significant background suppression could be achieved. (orig.)

Iris segmentation using an edge detector based on fuzzy sets theory and cellular learning automata.

Science.gov (United States)

Ghanizadeh, Afshin; Abarghouei, Amir Atapour; Sinaie, Saman; Saad, Puteh; Shamsuddin, Siti Mariyam

2011-07-01

Iris-based biometric systems identify individuals based on the characteristics of their iris, since they are proven to remain unique for a long time. An iris recognition system includes four phases, the most important of which is preprocessing in which the iris segmentation is performed. The accuracy of an iris biometric system critically depends on the segmentation system. In this paper, an iris segmentation system using edge detection techniques and Hough transforms is presented. The newly proposed edge detection system enhances the performance of the segmentation in a way that it performs much more efficiently than the other conventional iris segmentation methods.

Enhancements to the analytical facilities at the GNS proton microprobe

International Nuclear Information System (INIS)

Barry, B.J.; Markwitz, A.; Kennedy, V.J.; Trompetter, W.J.

2005-01-01

In recent years a number of detection systems have been added to the proton microprobe facility at GNS Science. Particular additions have been a large area HPGe detector and a system for scanning transmission imaging microscopy. The HPGe detector has improved detection sensitivity, particularly for higher energy K x-rays where energy resolution is of lesser importance. The scanning microscopy system has enabled mapping of areal densities in biological samples to give accurate elemental maps. Examples are given of these applications. (author). 22 refs., 7 figs

Coincidence gamma-ray spectrometry

DEFF Research Database (Denmark)

Markovic, Nikola; Roos, Per; Nielsen, Sven Poul

2017-01-01

Gamma-ray spectrometry with high-purity germanium (HPGe) detectors is often the technique of choice in an environmental radioactivity laboratory. When measuring environmental samples associated activities are usually low so an important parameter that describes the performance of the spectrometer...... for a nuclide of interest is the minimum detectable activity (MDA). There are many ways for lowering the MDAs in gamma spectrometry. Recently, developments of fast and compact digital acquisition systems have led to growing number of multiple HPGe detector spectrometers. In these applications all detected...

Response function of an HPGe detector simulated through MCNP 4A varying the density and chemical composition of the matrix; Funcion respuesta de un detector HPGe simulada mediante MCNP 4A variando la densidad y composicion quimica de la matriz

Energy Technology Data Exchange (ETDEWEB)

Leal A, B.; Mireles G, F.; Quirino T, L.; Pinedo, J.L. [Universidad Autonoma de Zacatecas, Zacatecas (Mexico)]. e-mail: bleal79@yahoo.com.mx

2005-07-01

In the area of the Radiological Safety it is required of a calibrated detection system in energy and efficiency for the determination of the concentration in activity in samples that vary in chemical composition and by this in density. The area of Nuclear Engineering requires to find the grade of isotopic enrichment of the uranium of the Sub-critic Nuclear Chicago 9000 Mark. Given the experimental importance that has the determination from the curves of efficiency to the effects of establishing the quantitative results, is appealed to the simulation of the response function of the detector used in the Regional Center of Nuclear Studies inside the range of energy of 80 keV to 1400 keV varying the density of the matrix and the chemical composition by means of the application of the Monte Carlo code MCNP-4A. The obtained results in the simulation of the response function of the detector show a grade of acceptance in the range from 500 to 1400 keV energy, with a smaller percentage discrepancy to 10%, in the range of low energy that its go from 59 to 400 keV, the percentage discrepancy varies from 17% until 30%, which is manifested in the opposing isotopic relationship for 5 fuel rods of the Sub critic nuclear assemble. (Author)

A segmented detector for airbone gamma ray spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Burgada, G.; Iovene, A.; Petrucci, S.; Tintori, C., E-mail: g.burgada@caen.it [Costruzioni Apparecchiature Elettroniche Nucleari S.p.A. (CAEN), Viareggio (Italy); Alvarez, M.A.G., E-mail: malvarez@if.usp.br [Universidade de Sao Paulo (IF/USP), Sao Paulo, SP (Brazil). Instituto de Fisica; Baldoncini, M.; Xhixha, G.; Strati, V., E-mail: gerti.xhixha@unife.it [University of Ferrara, Department of Physics and Earth Sciences, Ferrara (Italy); Mantovani, F., E-mail: mantovani@fe.infn.it [Istituto Nazionale di Fisica Nucleare (INFN), Ferrara (Italy); Garosi, P.; Mou, L., E-mail: li.mou@libero.it [University of Siena (Italy); Alvarez, C. Rossi, E-mail: rossialvarez@pd.infn.it [Istituto Nazionale di Fisica Nucleare (INFN), Legnaro (Italy)

2014-07-01

The airborne gamma-ray spectrometry (AGRS) is widely acknowledged as a very efficient technique for large areas monitoring. The detector system mounted on a helicopter allows for an extensive survey in a single flight time, thus reducing the exposure risk for the operator. Results from AGRS techniques are exploited in many fields, from the geological research to the homeland security for the search of orphan radioactive sources, from the mining and hydrocarbon exploration to the construction industry. The new generation of compact digital data acquisition and online processing equipment allows for faster airborne survey campaigns, and enhances the flexibility of operations. In addition, the algorithm for the extrapolation of the nuclide concentrations from the acquired gamma spectra is a challenging step of the entire technique. We are going to present a new device for advanced AGRS measurements, with an innovative detector configuration and data processing algorithms for optimizing the source localization and the on-line response capabilities. The new compact structure makes the system easily portable by a single operator, and rapidly mountable on most common helicopters. Preliminary feasibility studies have been performed to test the mechanics and the hardware of the whole system, which is intended to work without any human attendance. The first flights are planned by the end of 2014, with the aim of detecting artificial point sources having intensities on the order of 10^8 Bq and natural enriched fields already monitored. (author)

A segmented detector for airbone gamma ray spectroscopy

International Nuclear Information System (INIS)

Burgada, G.; Iovene, A.; Petrucci, S.; Tintori, C.; Alvarez, M.A.G.; Mantovani, F.; Garosi, P.; Mou, L.; Alvarez, C. Rossi

2014-01-01

The airborne gamma-ray spectrometry (AGRS) is widely acknowledged as a very efficient technique for large areas monitoring. The detector system mounted on a helicopter allows for an extensive survey in a single flight time, thus reducing the exposure risk for the operator. Results from AGRS techniques are exploited in many fields, from the geological research to the homeland security for the search of orphan radioactive sources, from the mining and hydrocarbon exploration to the construction industry. The new generation of compact digital data acquisition and online processing equipment allows for faster airborne survey campaigns, and enhances the flexibility of operations. In addition, the algorithm for the extrapolation of the nuclide concentrations from the acquired gamma spectra is a challenging step of the entire technique. We are going to present a new device for advanced AGRS measurements, with an innovative detector configuration and data processing algorithms for optimizing the source localization and the on-line response capabilities. The new compact structure makes the system easily portable by a single operator, and rapidly mountable on most common helicopters. Preliminary feasibility studies have been performed to test the mechanics and the hardware of the whole system, which is intended to work without any human attendance. The first flights are planned by the end of 2014, with the aim of detecting artificial point sources having intensities on the order of 10^8 Bq and natural enriched fields already monitored. (author)

A pixel segmented silicon strip detector for ultra fast shaping at low noise and low power consumption

International Nuclear Information System (INIS)

Misiakos, K.; Kavadias, S.

1996-01-01

A new radiation imaging device is proposed based on strips segmented into small pixels. Every pixel contains a submicron transistor that is normally biased in weak inversion. The ionization charge, upon collection by the pixel, changes the bias of the transistor to strong inversion and supplies a current up to several tens of a microA. This is a consequence of the small pixel capacitance (12 fF). The drains and sources of the transistors on the same row and column are shorted to bus lines that effectively become the Y and X coordinates. These bus lines are connected to the off chip ICON amplifiers to provide a 10 ns peaking time at a noise of about 150 electrons and 1 nW power consumption, for a 10x10 cm 2 detector and a MIP excitation. The noise performance is dominated by the ICON transistors. The cross talk between adjacent strips can be kept at a few percentage points provided a low transistor bias current is used

Diagnostic performance of 320-detector CT coronary angiography in patients with atrial fibrillation: preliminary results

Energy Technology Data Exchange (ETDEWEB)

Xu, Lei; Yang, Lin; Fan, Zhanming; Yu, Wei; Lv, Biao; Zhang, Zhaoqi [Capital Medical University, Department of Radiology, Beijing Anzhen Hospital, Beijing (China)

2011-05-15

To evaluate the feasibility, diagnostic accuracy, and radiation dose of CT coronary angiography (CTCA) in patients with atrial fibrillation (AF) using 320-detector CT. Thirty-seven patients with persistent AF and suspected coronary artery disease (CAD) were enrolled. All patients underwent both 320-detector CTCA and conventional coronary angiography (CCA). CT image quality and the presence of significant ({>=}50%) stenosis were evaluated by two radiologists blinded to the results of CCA. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated using CCA as the reference standard. Differences in detection of coronary artery stenosis between 320-detector CTCA and CCA were evaluated with McNemar's test. Patient radiation dose was calculated by multiplying dose length product by conversion coefficient of 0.017. In total 474 evaluated coronary segments, 459 (96.8%) segments were diagnostically evaluable. On per-segment analysis, sensitivity, specificity, PPV and NPV were 90.0% (18 of 20), 99.3% (436 of 439), 85.7% (18 of 21) and 99.5% (436 of 438). No significant difference was found between 320-detector CTCA and CCA on the detection of significant stenosis (P = 1.000). Effective doses of 320-detector CTCA was 13.0 {+-} 4.7 mSv. 320-detector CTCA is feasible and accurate in excluding CAD in patients with AF. (orig.)

Performance of prototype segmented CdZnTe arrays

International Nuclear Information System (INIS)

Parsons, A.; Palmer, D.M.; Kurczynski, P.; Barbier, L.; Barthelmy, S.; Bartlett, L.; Gehrels, N.; Krizmanic, J.; Stahle, C.M.; Tueller, J.; Teegarden, B.

1998-01-01

The Burst and All Sky Imaging Survey (BASIS) is a proposed mission to provide ∼3 arc second locations of approximately 90 Gamma-Ray Bursts (GRBs) per year. The BASIS coded aperture imaging system requires a segmented detector plane able to detect the interaction position of (10--150 keV) photons to less than 100 microm. To develop prototype detector arrays with such fine position resolution the authors have fabricated many 15 mm x 15 mm x 2 mm 100 microm pitch CdZnTe strip detectors. They have assembled these fine pitch CdZnTe strip detectors into prototype 2 x 2 and 6 x 6 element arrays read out by ASIC electronics. The assembly and electronics readout of the 6 x 6 flight prototype array will be discussed, and preliminary data illustrating the uniformity and efficiency of the array will be presented

Fabrication, Quality Assurance, and Quality Control for PROSPECT Detector Component Production

Science.gov (United States)

Gustafson, Ian; Prospect (The Precision Reactor Oscillation; Spectrum Experiment) Collaboration

2017-09-01

The Precision Reactor Oscillation and Spectrum Experiment (PROSPECT) is an electron antineutrino (νe) detector intended to make a precision measurement of the 235U neutrino spectrum and to search for the possible existence of sterile neutrinos with a mass splitting of Δm2 on the order of 1 eV2 . As a short baseline detector, PROSPECT will be located less than 10 meters from the High Flux Isotope Reactor at Oak Ridge National Laboratory. As PROSPECT intends to search for baseline-dependent oscillations, physical segmentation is needed to better measure the interaction position. PROSPECT will therefore be a segmented detector in two dimensions, thereby improving position measurements. PROSPECT will be segmented into 154 (11×14) 1.2-meter long rectangular tubes, using optical separators. Each separator will consist of a carbon fiber core, laminated with optical reflector (to increase light collection) and Teflon (to ensure compatibility with the scintillator). These optical separators will be held in place via strings of 3D printed PLA rods called `pinwheels.' This poster discusses the fabrication and quality assurance (QA) procedures used in the production of both the PROSPECT optical separators and pinwheels. For the PROSPECT collaboration.

A highly-segmented neutron detector for the A1 experiment at MAMI

Energy Technology Data Exchange (ETDEWEB)

Schoth, Matthias [Institut fuer Kernphysik, Mainz (Germany); Collaboration: A1-Collaboration

2015-07-01

Electric and magnetic form factors of the neutron, are one of the defining properties to characterize its structure quantitatively. A planned physics program to improve the data base significantly requires high performance detection of relativistic neutrons. Exploiting the full potential of the high luminosity supplied by the MAMI accelerator, a novel neutron detector is being developed in the scope of the A1 collaboration. A large active detector volume of 0.96 m{sup 3} is required to achieve a high raw detection efficiency. The detector is subdivided into 2048 plastic scintillators to be able to cope with high background rates. The light is extracted via wavelength shifting fibres and then guided to multi anode photomultiplier. The signal is read out with FPGA based TDCs (TRBv3 developed at GSI). The energy of the signal is obtained via time over threshold information in combination with a suitable shaping and discriminating circuit. Prototype tests have been performed to optimize the choice of materials and geometry. The capability to detect neutrons in the relevant momentum range has been demonstrated using pion production. A Geant4 simulation using tracking algorithms evaluating the deposited energy is able to optimize key detector properties like particle id efficiency, multiplicity or the effective analyzing power for double polarized scattering experiments.

UBO Detector - A cluster-based, fully automated pipeline for extracting white matter hyperintensities.

Science.gov (United States)

Jiang, Jiyang; Liu, Tao; Zhu, Wanlin; Koncz, Rebecca; Liu, Hao; Lee, Teresa; Sachdev, Perminder S; Wen, Wei

2018-07-01

We present 'UBO Detector', a cluster-based, fully automated pipeline for extracting and calculating variables for regions of white matter hyperintensities (WMH) (available for download at https://cheba.unsw.edu.au/group/neuroimaging-pipeline). It takes T1-weighted and fluid attenuated inversion recovery (FLAIR) scans as input, and SPM12 and FSL functions are utilised for pre-processing. The candidate clusters are then generated by FMRIB's Automated Segmentation Tool (FAST). A supervised machine learning algorithm, k-nearest neighbor (k-NN), is applied to determine whether the candidate clusters are WMH or non-WMH. UBO Detector generates both image and text (volumes and the number of WMH clusters) outputs for whole brain, periventricular, deep, and lobar WMH, as well as WMH in arterial territories. The computation time for each brain is approximately 15 min. We validated the performance of UBO Detector by showing a) high segmentation (similarity index (SI) = 0.848) and volumetric (intraclass correlation coefficient (ICC) = 0.985) agreement between the UBO Detector-derived and manually traced WMH; b) highly correlated (r 2  > 0.9) and a steady increase of WMH volumes over time; and c) significant associations of periventricular (t = 22.591, p deep (t = 14.523, p < 0.001) WMH volumes generated by UBO Detector with Fazekas rating scores. With parallel computing enabled in UBO Detector, the processing can take advantage of multi-core CPU's that are commonly available on workstations. In conclusion, UBO Detector is a reliable, efficient and fully automated WMH segmentation pipeline. Copyright © 2018 Elsevier Inc. All rights reserved.

In situ prompt gamma-ray measurement of river water salinity in northern Taiwan using HPGe-252Cf probe

International Nuclear Information System (INIS)

Jiunnhsing Chao; Chien Chung

1991-01-01

A portable HPGe- 252 Cf probe dedicated to in situ survey of river water salinity was placed on board a fishing boat to survey the Tamsui River in northern Taiwan. The variation of water salinity is surveyed by measuring the 6111 keV chlorine prompt photopeak along the river. Results indicate that the probe can be used as a salinometer for rapid, in situ measurement in polluted rivers or sea. (author)

Conditioning the gamma spectrometer for activity measurement at very high background

OpenAIRE

Yan, Weihua; Zhang, Liguo; Zhang, Zhao; Xiao, Zhigang

2013-01-01

The application of a high purity germanium (HPGe) gamma spectrometer in determining the fuel element burnup in a future reactor is studied. The HPGe detector is exposed by a Co60 source with varying irradiation rate from 10 kcps to 150 kcps to simulate the input counting rate in real reactor environment. A Cs137 and a Eu152 source are positioned at given distances to generate certain event rate in the detector with the former being proposed as a labeling nuclide to measure the burnup of fuel ...

The GALATEA test facility and a first study of α-induced surface events in a germanium detector

Energy Technology Data Exchange (ETDEWEB)

Irlbeck, Sabine

2014-01-30

Germanium detectors are a choice technology in fundamental research. They are suitable for the search for rare events due to their high sensitivity and excellent energy resolution. As an example, the GERDA (GERmanium Detector Array) experiment searching for neutrinoless double beta decay is described. The observation of this decay would resolve the fundamental question whether the neutrino is its own antiparticle. Especially adapted detector technologies and low background rates needed to detect very rare events such as neutrinoless double beta decays are discussed. The identification of backgrounds originating from the interaction of radiation, especially α-particles, is a focus of this thesis. Low background experiments face problems from α-particles due to unavoidable surface contaminations of the germanium detectors. The segmentation of detectors is used to obtain information about the special characteristics of selected events. The high precision test stand GALATEA was especially designed for surface scans of germanium detectors. As part of this work, GALATEA was completed and commissioned. The final commissioning required major upgrades of the original design which are described in detail. Collimator studies with two commercial germanium detectors are presented. Different collimation levels for a β-source were investigated and crystal axis effects were examined. The first scan with an α-source of the passivated end-plate of a special 19-fold segmented prototype detector mounted in GALATEA is described. The α-induced surface events were studied and characterized. Crosstalk and mirror pulses seen in the segments of the germanium detector were analyzed. The detector studies presented in this thesis will help to further improve the design of germanium detectors for low background experiments.

The GALATEA test facility and a first study of α-induced surface events in a germanium detector

International Nuclear Information System (INIS)

Irlbeck, Sabine

2014-01-01

Germanium detectors are a choice technology in fundamental research. They are suitable for the search for rare events due to their high sensitivity and excellent energy resolution. As an example, the GERDA (GERmanium Detector Array) experiment searching for neutrinoless double beta decay is described. The observation of this decay would resolve the fundamental question whether the neutrino is its own antiparticle. Especially adapted detector technologies and low background rates needed to detect very rare events such as neutrinoless double beta decays are discussed. The identification of backgrounds originating from the interaction of radiation, especially α-particles, is a focus of this thesis. Low background experiments face problems from α-particles due to unavoidable surface contaminations of the germanium detectors. The segmentation of detectors is used to obtain information about the special characteristics of selected events. The high precision test stand GALATEA was especially designed for surface scans of germanium detectors. As part of this work, GALATEA was completed and commissioned. The final commissioning required major upgrades of the original design which are described in detail. Collimator studies with two commercial germanium detectors are presented. Different collimation levels for a β-source were investigated and crystal axis effects were examined. The first scan with an α-source of the passivated end-plate of a special 19-fold segmented prototype detector mounted in GALATEA is described. The α-induced surface events were studied and characterized. Crosstalk and mirror pulses seen in the segments of the germanium detector were analyzed. The detector studies presented in this thesis will help to further improve the design of germanium detectors for low background experiments.

Assessment of uncertainties in the lung activity measurement of low-energy photon emitters using Monte Carlo simulation of ICRP male thorax voxel phantom.

Science.gov (United States)

Nadar, M Y; Akar, D K; Rao, D D; Kulkarni, M S; Pradeepkumar, K S

2015-12-01

Assessment of intake due to long-lived actinides by inhalation pathway is carried out by lung monitoring of the radiation workers inside totally shielded steel room using sensitive detection systems such as Phoswich and an array of HPGe detectors. In this paper, uncertainties in the lung activity estimation due to positional errors, chest wall thickness (CWT) and detector background variation are evaluated. First, calibration factors (CFs) of Phoswich and an array of three HPGe detectors are estimated by incorporating ICRP male thorax voxel phantom and detectors in Monte Carlo code 'FLUKA'. CFs are estimated for the uniform source distribution in lungs of the phantom for various photon energies. The variation in the CFs for positional errors of ±0.5, 1 and 1.5 cm in horizontal and vertical direction along the chest are studied. The positional errors are also evaluated by resizing the voxel phantom. Combined uncertainties are estimated at different energies using the uncertainties due to CWT, detector positioning, detector background variation of an uncontaminated adult person and counting statistics in the form of scattering factors (SFs). SFs are found to decrease with increase in energy. With HPGe array, highest SF of 1.84 is found at 18 keV. It reduces to 1.36 at 238 keV. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Measurement of secondary gamma-ray skyshine and groundshine from intense 14 MeV neutron source facility

Energy Technology Data Exchange (ETDEWEB)

Yoshida, Shigeo; Morotomi, Ryutaro; Kondo, Tetsuo; Murata, Isao; Takahashi, Akito [Osaka Univ., Suita (Japan). Dept. of Nuclear Engineering

2000-03-01

Secondary gamma-ray skyshine and groundshine, including the direct contribution from the facility building, have been measured with an Hp-Ge detector and an NaI(Tl) detector at the Intense 14 MeV Neutron Source Facility OKTAVIAN of Osaka University, Japan. The mechanism of secondary gamma-rays propagation were analyzed with the measured spectrum with the Hp-Ge detector. The contribution of the skyshine was shown to be a continuum spectrum that was composed of mainly Compton scattered high energy secondary gamma-rays generated in the facility building created by (n, {gamma}) reaction. The contribution of the groundshine considerably contained secondary gamma-rays generated by {sup nat}Si (n, {gamma}) reaction in soil, including the albedo contribution from the ground. And the total contribution contained capture gamma-rays from iron (Fe) and other nuclides. The measurements with the NaI(Tl) detector as well as the Hp-Ge detector were carried out to investigate the dependence of gamma-ray dose as a function of distance from the neutron source up to hundreds meters. Consequently, it was found that the dependence could be fitted with the function of const.{center_dot}exp(-r/{lambda})/r{sup n}, where n values were around 2 except for the skyshine (n {approx} 1). It was thus indicated that the contribution of the skyshine could be propagated farther downfield than the direct contribution from the facility. The measured ratios of the three contributions (skyshine, groundshine, and direct contributions) and the distance dependence in each path were shown to be in good agreement with calculated results by the Monte Carlo transport code MCNP-4A. And the total contributions for the two detectors of NaI(Tl) and Hp-Ge agree excellently with each other. (author)

First runs with the ORPHEUS dark matter detector

CERN Document Server

Czapek, G; Hauser, M; Janos, S; Loaiza, P; Moser, U; Pretzl, K; Brandt, B V D; Konter, J A; Mango, S; Ebert, T; Kainer, K U; Knoop, K M

2002-01-01

The ORPHEUS dark matter experiment is completed at our shallow depth laboratory in Bern (70 m.w.e.). The detector relies on measuring the magnetic flux variation produced by weakly interacting massive particles (WIMPs) as they heat 30 mu m diameter superheated superconducting tin granules (SSG) and induce superconducting-to-normal phase transitions. In an initial phase, 0.45 kg of tin granules in a segmented detector volume have been used. Preliminary results of the experiment will be reported.

Schottky barrier CdTe(Cl) detectors for planetary missions

International Nuclear Information System (INIS)

Eisen, Yosef; Floyd, Samuel

2002-01-01

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

Track segments in hadronic showers in a highly granular scintillator-steel hadron calorimeter

CERN Document Server

Adloff, C.; Chefdeville, M.; Drancourt, C.; Gaglione, R.; Geffroy, N.; Karyotakis, Y.; Koletsou, I.; Prast, J.; Vouters, G.; Francis, K.; Repond, J.; Schlereth, J.; Smith, J.; Xia, L.; Baldolemar, E.; Li, J.; Park, S.T.; Sosebee, M.; White, A.P.; Yu, J.; Eigen, G.; Mikami, Y.; Watson, N.K.; Mavromanolakis, G.; Thomson, M.A.; Ward, D.R.; Yan, W.; Benchekroun, D.; Hoummada, A.; Khoulaki, Y.; Apostolakis, J.; Dannheim, D.; Dotti, A.; Folger, G.; Ivantchenko, V.; Klempt, W.; Kraaij, E.van der; Lucaci-Timoce, A.-I; Ribon, A.; Schlatter, D.; Uzhinskiy, V.; Cârloganu, C.; Gay, P.; Manen, S.; Royer, L.; Tytgat, M.; Zaganidis, N.; Blazey, G.C.; Dyshkant, A.; Lima, J.G.R.; Zutshi, V.; Hostachy, J.-Y; Morin, L.; Cornett, U.; David, D.; Falley, G.; Gadow, K.; Göttlicher, P.; Günter, C.; Hartbrich, O.; Hermberg, B.; Karstensen, S.; Krivan, F.; Krüger, K.; Lu, S.; Morozov, S.; Morgunov, V.; Reinecke, M.; Sefkow, F.; Smirnov, P.; Terwort, M.; Feege, N.; Garutti, E.; Laurien, S.; Marchesini, I.; Matysek, M.; Ramilli, M.; Briggl, K.; Eckert, P.; Harion, T.; Schultz-Coulon, H.-Ch; Shen, W.; Stamen, R.; Bilki, B.; Norbeck, E.; Onel, Y.; Wilson, G.W.; Kawagoe, K.; Sudo, Y.; Yoshioka, T.; Dauncey, P.D.; Magnan, A.-M; Bartsch, V.; Wing, M.; Salvatore, F.; Gil, E.Cortina; Mannai, S.; Baulieu, G.; Calabria, P.; Caponetto, L.; Combaret, C.; Negra, R.Della; Grenier, G.; Han, R.; Ianigro, J-C; Kieffer, R.; Laktineh, I.; Lumb, N.; Mathez, H.; Mirabito, L.; Petrukhin, A.; Steen, A.; Tromeur, W.; Donckt, M.Vander; Zoccarato, Y.; Alamillo, E.Calvo; Fouz, M.-C; Puerta-Pelayo, J.; Corriveau, F.; Bobchenko, B.; Chadeeva, M.; Danilov, M.; Epifantsev, A.; Markin, O.; Mizuk, R.; Novikov, E.; Popov, V.; Rusinov, V.; Tarkovsky, E.; Kirikova, N.; Kozlov, V.; Smirnov, P.; Soloviev, Y.; Buzhan, P.; Ilyin, A.; Kantserov, V.; Kaplin, V.; Karakash, A.; Popova, E.; Tikhomirov, V.; Kiesling, C.; Seidel, K.; Simon, F.; Soldner, C.; Szalay, M.; Tesar, M.; Weuste, L.; Amjad, M.S.; Bonis, J.; Callier, S.; Lorenzo, S.Conforti di; Cornebise, P.; Doublet, Ph; Dulucq, F.; Fleury, J.; Frisson, T.; der Kolk, N.van; Li, H.; Martin-Chassard, G.; Richard, F.; Taille, Ch de la; Pöschl, R.; Raux, L.; Rouëné, J.; Seguin-Moreau, N.; Anduze, M.; Balagura, V.; Boudry, V.; Brient, J-C; Cornat, R.; Frotin, M.; Gastaldi, F.; Guliyev, E.; Haddad, Y.; Magniette, F.; Musat, G.; Ruan, M.; Tran, T.H.; Videau, H.; Bulanek, B.; Zacek, J.; Cvach, J.; Gallus, P.; Havranek, M.; Janata, M.; Kvasnicka, J.; Lednicky, D.; Marcisovsky, M.; Polak, I.; Popule, J.; Tomasek, L.; Tomasek, M.; Ruzicka, P.; Sicho, P.; Smolik, J.; Vrba, V.; Zalesak, J.; Belhorma, B.; Ghazlane, H.; Kotera, K.; Takeshita, T.; Uozumi, S.; Jeans, D.; Götze, M.; Sauer, J.; Weber, S.; Zeitnitz, C.

2013-01-01

We investigate the three dimensional substructure of hadronic showers in the CALICE scintillator-steel hadronic calorimeter. The high granularity of the detector is used to find track segments of minimum ionising particles within hadronic showers, providing sensitivity to the spatial structure and the details of secondary particle production in hadronic cascades. The multiplicity, length and angular distribution of identified track segments are compared to GEANT4 simulations with several different shower models. Track segments also provide the possibility for in-situ calibration of highly granular calorimeters.

Delayed gamma-ray spectroscopy with lanthanum bromide detector for non-destructive assay of nuclear material

Science.gov (United States)

Favalli, Andrea; Iliev, Metodi; Ianakiev, Kiril; Hunt, Alan W.; Ludewigt, Bernhard

2018-01-01

High-energy delayed γ-ray spectroscopy is a potential technique for directly assaying spent fuel assemblies and achieving the safeguards goal of quantifying nuclear material inventories for spent fuel handling, interim storage, reprocessing facilities, repository sites, and final disposal. Requirements for the γ-ray detection system, up to ∼6 MeV, can be summarized as follows: high efficiency at high γ-ray energies, high energy resolution, good linearity between γ-ray energy and output signal amplitude, ability to operate at very high count rates, and ease of use in industrial environments such as nuclear facilities. High Purity Germanium Detectors (HPGe) are the state of the art and provide excellent energy resolution but are limited in their count rate capability. Lanthanum Bromide (LaBr3) scintillation detectors offer significantly higher count rate capabilities at lower energy resolution. Thus, LaBr3 detectors may be an effective alternative for nuclear spent-fuel applications, where count-rate capability is a requirement. This paper documents the measured performance of a 2" (length) × 2" (diameter) of LaBr3 scintillation detector system, coupled to a negatively biased PMT and a tapered active high voltage divider, with count-rates up to ∼3 Mcps. An experimental methodology was developed that uses the average current from the PMT's anode and a dual source method to characterize the detector system at specific very high count rate values. Delayed γ-ray spectra were acquired with the LaBr3 detector system at the Idaho Accelerator Center, Idaho State University, where samples of ∼3g of 235U were irradiated with moderated neutrons from a photo-neutron source. Results of the spectroscopy characterization and analysis of the delayed γ-ray spectra acquired indicate the possible use of LaBr3 scintillation detectors when high count rate capability may outweigh the lower energy resolution.

Electronics for the RHIC PHENIX detector

International Nuclear Information System (INIS)

Young, G.R.

1992-01-01

The PHENIX detector for RHIC is being designed to measure lepton pairs, direct photons and hadrons emitted in collisions of heavy nuclei at center of mass energies up to 200 GeV/(nucleon-pair). The physics goal is tests of predictions concerning the existence and nature of a deconfined state of strongly-interacting matter. The relatively large final state multiplicities, which reach 1500 charged particles per unit of rapidity, place strong demands on detector segmentation and control of electronics cost and power consumption. An overview of present ideas concerning signal processing and data rates for PHENIX will be presented

Superpixel-based segmentation of muscle fibers in multi-channel microscopy.

Science.gov (United States)

Nguyen, Binh P; Heemskerk, Hans; So, Peter T C; Tucker-Kellogg, Lisa

2016-12-05

Confetti fluorescence and other multi-color genetic labelling strategies are useful for observing stem cell regeneration and for other problems of cell lineage tracing. One difficulty of such strategies is segmenting the cell boundaries, which is a very different problem from segmenting color images from the real world. This paper addresses the difficulties and presents a superpixel-based framework for segmentation of regenerated muscle fibers in mice. We propose to integrate an edge detector into a superpixel algorithm and customize the method for multi-channel images. The enhanced superpixel method outperforms the original and another advanced superpixel algorithm in terms of both boundary recall and under-segmentation error. Our framework was applied to cross-section and lateral section images of regenerated muscle fibers from confetti-fluorescent mice. Compared with "ground-truth" segmentations, our framework yielded median Dice similarity coefficients of 0.92 and higher. Our segmentation framework is flexible and provides very good segmentations of multi-color muscle fibers. We anticipate our methods will be useful for segmenting a variety of tissues in confetti fluorecent mice and in mice with similar multi-color labels.

arXiv On the localization properties of an RPWELL gas-avalanche detector

CERN Document Server

Moleri, Luca; Coimbra, Artur E. C.; Breskin, Amos; Bressler, Shikma

2017-10-23

A study of the localization properties of a single-element Resistive Plate WELL (RPWELL) detector is presented. The detector comprises of a single-sided THick Gaseous Electron Multiplier (THGEM) coupled to a segmented readout anode through a doped silicate-glass plate of 10(10) Ω⋅cm bulk resistivity. Operated in ambient \

SAMPO80, Ge(Li) Detector Gamma Spectra Unfolding with Isotope Identification

International Nuclear Information System (INIS)

Koskelo, M.J.; Aarnio, P.A.; Routti, J.T.

1998-01-01

1 - Description of problem or function: Analysis of gamma spectra measured with Ge(Li) or HPGe detectors. 2 - Method of solution: - Shape calibration using a non-linear least squares algorithm with a variable metric method. - Peak location with a smoothed second difference method. - Peak area calculation with a linear least squares fit to predefined peak shapes. - Nuclide identification with a linear least squares fit based on associated lines. 3 - Restrictions on the complexity of the problem: Number of shape calibration points allowed: 20; Number of energy calibration points allowed: 20; Number of efficiency calibration points allowed: 20; Maximum number of found peaks: 100; Maximum number of fitted peaks: 100; Maximum number of peaks in a multiplet: 5; Maximum number of channels in a fitting interval: 50; Maximum number of peaks for nuclide identification: 80; Maximum number of identified nuclides: 30; Maximum number of lines per nuclide: 30

Application of position-sensitive detectors to positron imaging

International Nuclear Information System (INIS)

Yamashita, Takaji; Uchida, Hiroshi; Watanabe, Mitsuo; Omura, Tomohide

1994-01-01

Positron imaging including positron emission tomography (PET) is expected to be a promising tool for basic and clinical research, because it makes possible the study of regional chemistry within multiple organs of the body in living human beings and experimental animals. New schemes of high resolution block detectors have been developed to improve the performance of positron imaging systems, which employ small segments of bismuth germanate (BGO) arrays and position-sensitive photomultiplier tubes (PS-PMT). The coincidence detector resolution of less than 2.0 mm in full width at half maximum was achieved with the detectors, which is very close to the theoretical resolution limit in positron imaging. (author)

CHICO, a heavy ion detector for Gammasphere

CERN Document Server

Simon, M W; Wu, C Y; Gray, R W; Teng, R; Long, C

2000-01-01

A 4 pi position-sensitive heavy-ion detector system, CHICO, has been developed primarily for use in conjunction with the 4 pi gamma-ray facility, Gammasphere. The CHICO detector comprises an array of 20 Parallel Plate Avalanche Counters (PPACs) covering 12 deg. segmented delay-line cathode boards, measuring the polar scattering angle theta to 1 deg., and segmented anodes, measuring the azimuthal angle phi with 9 deg. resolution, while measuring the time-of-flight difference with 500 ps resolution. For binary reactions the kinematics can be reconstructed from the measured information, allowing identification of the target- and projectile-like nuclei with a mass resolution of DELTA m/m approx 5%. The measured masses, recoil velocities, and recoil angles allow correction for Doppler shift and assignment of individual gamma-rays to decay of the correct reaction product. This paper describes the design, operation and perform...

Status of the KATRIN focal-plane detector

Energy Technology Data Exchange (ETDEWEB)

Seher, Agnes [Karlsruher Institute of Technology (KIT) (Germany). Institut fuer Kernphysik (IKP); Collaboration: KATRIN-Collaboration

2016-07-01

The KArlsruhe TRItium Neutrino (KATRIN) experiment aims to determine the mass of the electron anti-neutrino with a sensitivity of 200 meV/c{sup 2} by measuring the kinematics of tritium β-electrons close to the enpoint of the energy spectrum. The energy analysis of the experiment is performed with a high-resolution electrostatic spectrometer of MAC-E filter type which acts as an integranting high pass filter. Transmitted electrons are counted with a segmented silicon detector system located at the downstream end of the experiment. The detector system consists of two super-conducting solenoids (B{sub max}=6 T), a post-acceleration electrode, a detector wafer with silicon pixel-diodes, readout electronics as well as a calibration and monitoring devices. This talk gives an overview of the detector system and its current status as well as key performance parameters.

Measurement of the pulse pileup correction for the HPGe gamma spectrometer

International Nuclear Information System (INIS)

Kulkarni, D.B.; Anuradha, R.; Joseph, Leena; Kulkarni, M.S.

2018-01-01

Radiation Standards Section (RSS), RSSD, has HPGe gamma spectrometry system maintained as a secondary standard for standardization of gamma emitting radionuclides. This system is also used to detect the impurities in the radioactivity samples supplied for the international inter-comparison exercises, so that the appropriate correction can be made for the standardized activity of principle radionuclide. The system is calibrated as per the recommended procedure (ANSI standard N42.14, 1999). As a part of this calibration, measurement of the pulse pile up correction was carried out in the energy range of 81 keV to 1408 keV. The measurement of pileup correction is very important for the standardization of sources having higher counting rates where the extent of the pileup effect is more and considerable deviation from the true counting rates was observed. For these sources the measured photo peak counting rate is less than true counting rate and needs to be corrected for pileup effect. The details of experiments are discussed in this paper

A large, high performance, curved 2D position-sensitive neutron detector

CERN Document Server

Fried, J W; Mahler, G J; Makowiecki, D S; Mead, J A; Radeka, V; Schaknowski, N A; Smith, G C; Yu, B

2002-01-01

A new position-sensitive neutron detector has been designed and constructed for a protein crystallography station at LANL's pulsed neutron source. This station will be one of the most advanced instruments at a major neutron user facility for protein crystallography, fiber and membrane diffraction. The detector, based on neutron absorption in sup 3 He, has a large sensitive area of 3000 cm sup 2 , angular coverage of 120 deg. , timing resolution of 1 mu s, rate capability in excess of 10 sup 6 s sup - sup 1 , position resolution of about 1.5 mm FWHM, and efficiency >50% for neutrons of interest in the range 1-10 A. Features that are key to these remarkable specifications are the utilization of eight independently operating segments within a single gas volume, fabrication of the detector vessel and internal segments with a radius of curvature of about 70 cm, optimized position readout based on charge division and signal shaping with gated baseline restoration, and engineering design with high-strength aluminum ...

The ALICE Transition Radiation Detector: status and perspectives for Run II

CERN Document Server

Klein, Jochen

2016-01-01

The ALICE Transition Radiation Detector contributes to the tracking, particle identification, and triggering capabilities of the experiment. It is composed of six layers of multi-wire proportional chambers, each of which is preceded by a radiator and a Xe/CO$_2$-filled drift volume. The signal is sampled in timebins of 100~ns over the drift length which allows for the reconstruction of chamber-wise track segments, both online and offline. The particle identification is based on the specific energy loss of charged particles and additional transition radiation photons, the latter being a signature for electrons. The detector is segmented into 18 sectors, of which 13 were installed in Run I. The TRD was included in data taking since the LHC start-up and was successfully used for electron identification and triggering. During the Long Shutdown 1, the detector was completed and now covers the full azimuthal acceptance. Furthermore, the readout and trigger components were upgraded. When data taking was started for ...

Detector Simulations with DD4hep

Science.gov (United States)

Petrič, M.; Frank, M.; Gaede, F.; Lu, S.; Nikiforou, N.; Sailer, A.

2017-10-01

Detector description is a key component of detector design studies, test beam analyses, and most of particle physics experiments that require the simulation of more and more different detector geometries and event types. This paper describes DD4hep, which is an easy-to-use yet flexible and powerful detector description framework that can be used for detector simulation and also extended to specific needs for a particular working environment. Linear collider detector concepts ILD, SiD and CLICdp as well as detector development collaborations CALICE and FCal have chosen to adopt the DD4hep geometry framework and its DDG4 pathway to Geant4 as its core simulation and reconstruction tools. The DDG4 plugins suite includes a wide variety of input formats, provides access to the Geant4 particle gun or general particles source and allows for handling of Monte Carlo truth information, eg. by linking hits and the primary particle that caused them, which is indispensable for performance and efficiency studies. An extendable array of segmentations and sensitive detectors allows the simulation of a wide variety of detector technologies. This paper shows how DD4hep allows to perform complex Geant4 detector simulations without compiling a single line of additional code by providing a palette of sub-detector components that can be combined and configured via compact XML files. Simulation is controlled either completely via the command line or via simple Python steering files interpreted by a Python executable. It also discusses how additional plugins and extensions can be created to increase the functionality.

Quality Control Of Compton Suppression System As An Environmental Sample Counting System

International Nuclear Information System (INIS)

Siswohartoyo, Sudarti; Soepardi, Dewita

1996-01-01

Quality control on Compton Suppression System has been done, i.e : 1) testing of HPGe as the main detector (FWHM, P/C d c level /n oise ) , 2) the Nal(Tl) detector shielding characteristic, 3) timing spectrum (FWHM), and 4) suppression factor. From the collected data, the characteristic of HPGe were found to be in the same range as shown in the manual. From the Nal(Tl) testing, it was found that the resolution was about 9%. From the time spectrum testing, the resolution was about 12-13 ns, while the suppression factor measurement was found to be about 4 - 4.6

Image feature detectors and descriptors foundations and applications

CERN Document Server

Hassaballah, Mahmoud

2016-01-01

This book provides readers with a selection of high-quality chapters that cover both theoretical concepts and practical applications of image feature detectors and descriptors. It serves as reference for researchers and practitioners by featuring survey chapters and research contributions on image feature detectors and descriptors. Additionally, it emphasizes several keywords in both theoretical and practical aspects of image feature extraction. The keywords include acceleration of feature detection and extraction, hardware implantations, image segmentation, evolutionary algorithm, ordinal measures, as well as visual speech recognition. .

Detection of hidden sources. Prompt reports by airborne teams in Resume95

International Nuclear Information System (INIS)

Toivonen, H.

1997-01-01

An exercise to locate and identify lost radioactive sources was arranged near Padasjoki Auttoinen village. Ten sources, consisting of caesium, cobolt, iridium and technetium, were hidden. The teams (10) were asked to report their findings immediately after the landing and 24 h later. The teams that had a large NaI detector at their disposal could locate more sources than the teams with HPGe detectors. However, for source identification and activity calculation and HPGe detector is superior. Thus, it is highly recommended for operational purposes that both measuring systems are used simultaneously. The best location results were provided by the Danish Emergency Management Agency; the team reported four sources at landing and two other sources were found in prompt data processing after the landing. (au)

Detection of hidden sources. Prompt reports by airborne teams in Resume95

Energy Technology Data Exchange (ETDEWEB)

Toivonen, H. [Finnish Centre for Radiation and Nuclear Safety, Helsinki (Finland)

1997-12-31

An exercise to locate and identify lost radioactive sources was arranged near Padasjoki Auttoinen village. Ten sources, consisting of caesium, cobolt, iridium and technetium, were hidden. The teams (10) were asked to report their findings immediately after the landing and 24 h later. The teams that had a large NaI detector at their disposal could locate more sources than the teams with HPGe detectors. However, for source identification and activity calculation and HPGe detector is superior. Thus, it is highly recommended for operational purposes that both measuring systems are used simultaneously. The best location results were provided by the Danish Emergency Management Agency; the team reported four sources at landing and two other sources were found in prompt data processing after the landing. (au).

Detection of hidden sources. Prompt reports by airborne teams in Resume95

Energy Technology Data Exchange (ETDEWEB)

Toivonen, H [Finnish Centre for Radiation and Nuclear Safety, Helsinki (Finland)

1998-12-31

An exercise to locate and identify lost radioactive sources was arranged near Padasjoki Auttoinen village. Ten sources, consisting of caesium, cobolt, iridium and technetium, were hidden. The teams (10) were asked to report their findings immediately after the landing and 24 h later. The teams that had a large NaI detector at their disposal could locate more sources than the teams with HPGe detectors. However, for source identification and activity calculation and HPGe detector is superior. Thus, it is highly recommended for operational purposes that both measuring systems are used simultaneously. The best location results were provided by the Danish Emergency Management Agency; the team reported four sources at landing and two other sources were found in prompt data processing after the landing. (au).

The presampler for the forward and rear calorimeter in the ZEUS detector

Energy Technology Data Exchange (ETDEWEB)

Bamberger, A; Bornheim, A; Crittenden, J; Grabosch, H -J; Grothe, M; Hervas, L; Hilger, E; Holm, U; Horstmann, D; Kaufmann, V; Kharchilava, A; Koetz, U; Kummerow, D; Mallik, U; Meyer, A; Nowoczyn, M; Ossowski, R; Schlenstedt, S; Tiecke, H; Verkerke, W; Vossebeld, J; Vreeswijk, M; Wang, S M; Wu, J [Bonn Univ. (Germany). Phys. Inst.; [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); [DESY-IfH Zeuthen, Zeuthen (Germany); [Fakultaet fuer Physik der Universitaet Freiburg, Freiburg i.Br. (Germany); [Hamburg University, I. Institute of Exp. Physics, Hamburg (Germany); [University of Iowa Physics and Astronomy Dept, Iowa City (United States); [Univer. Autonoma Madrid, Depto de Fisica Teorica, Madrid (Spain); [NIKHEF and University of Amsterdam, Amsterdam (Netherlands)

1996-11-21

The ZEUS detector at HERA has been supplemented with a presampler detector in front of the forward and rear calorimeters. It consists of a segmented scintillator array read out with wavelength-shifting fibers. We discuss its design, construction and performance. Test beam data obtained with a prototype presampler and the ZEUS prototype calorimeter demonstrate the main function of this detector, i.e. the correction for the energy lost by an electron interacting in inactive material in front of the calorimeter. (orig.).

A contrario line segment detection

CERN Document Server

von Gioi, Rafael Grompone

2014-01-01

The reliable detection of low-level image structures is an old and still challenging problem in computer vision. This?book leads a detailed tour through the LSD algorithm, a line segment detector designed to be fully automatic. Based on the a contrario framework, the algorithm works efficiently without the need of any parameter tuning. The design criteria are thoroughly explained and the algorithm's good and bad results are illustrated on real and synthetic images. The issues involved, as well as the strategies used, are common to many geometrical structure detection problems and some possible

16-Detector row computed tomographic coronary angiography in patients undergoing evaluation for aortic valve replacement: comparison with catheter angiography

International Nuclear Information System (INIS)

Manghat, N.E.; Morgan-Hughes, G.J.; Broadley, A.J.; Undy, M.B.; Wright, D.; Marshall, A.J.; Roobottom, C.A.

2006-01-01

Aim: To evaluate the diagnostic accuracy of 16-detector row computed tomography (CT) in assessing haemodynamically significant coronary artery stenoses in patients under evaluation for aortic stenosis pre-aortic valve replacement. Subjects and methods: Forty consecutive patients under evaluation for severe aortic stenosis and listed for cardiac catheterization before potential aortic valve replacement underwent coronary artery calcium (CAC) scoring and retrospective electrocardiogram (ECG)-gated multi-detector row computed tomographic coronary angiography (MDCTA) using a GE Lightspeed 16-detector row CT within 1 month of invasive coronary angiography (ICA) for comparative purposes. All 13 major coronary artery segments of the American Heart Association model were evaluated for the presence of ≥50% stenosis and compared to the reference standard. Data were analysed on a segment-by-segment basis and also in 'whole patient' terms. Results: A total of 412/450 segments from 35 patients were suitable for analysis. The overall accuracy of MDCTA for detection of segments with ≥50% stenosis was high, with a sensitivity of 81.3%, specificity 95.0%, positive predictive value (PPV) 57.8%, and negative predictive value (NPV) 98.4%. On a 'whole-patient' basis, 100% (19/19) of patients with significant coronary disease were correctly identified and there were no false-negatives. Excluding patients with CAC >1000 from the analysis improved the accuracy of MDCTA to: sensitivity 90%, specificity 98.1%, PPV 60%, NPV 99.7%. Conclusion: Non-invasive 16-detector row MDCTA accurately excludes significant coronary disease in patients with severe aortic stenosis undergoing evaluation before aortic valve replacement and in whom ICA can therefore be avoided. Its segment-by-segment accuracy is improved further if CAC > 1000 is used as a gatekeeper to MDCTA

Complete system for portable gamma spectroscopy

International Nuclear Information System (INIS)

Fuess, D.A.

1978-01-01

The report described a system built around the Computing Gamma Spectrometer (PSA) LEA 74-008. The software primarily supports high-resolution gamma-ray spectroscopy using either a high-purity intrinsic germanium detector (HPGe) or a lithium-drifted germanium detector [Ge(Li)

CdTe and CdZnTe gamma ray detectors for medical and industrial imaging systems

International Nuclear Information System (INIS)

Eisen, Y.; Shor, A.; Mardor, I.

1999-01-01

CdTe and CdZnTe X-ray and gamma ray detectors in the form of single elements or as segmented monolithic detectors have been shown to be useful in medical and industrial imaging systems. These detectors possess inherently better energy resolution than scintillators coupled to either photodiodes or photomultipliers, and together with application specific integrated circuits they lead to compact imaging systems of enhanced spatial resolution and better contrast resolution. Photopeak efficiencies of these detectors is greatly affected by a relatively low hole mobility-lifetime product. Utilizing these detectors as highly efficient good spectrometers, demands use of techniques to improve their charge collection properties, i.e., correct for variations in charge losses at different depths of interaction in the detector. The corrections for the large hole trapping are made either by applying electronic techniques or by fabricating detector or electrical contacts configurations which differ from the commonly used planar detectors. The following review paper is divided into three parts: The first part discusses detector contact configurations for enhancing photopeak efficiencies and the single carrier collection approach which leads to improved energy resolutions and photopeak efficiencies at high gamma ray energies. The second part demonstrates excellent spectroscopic results using thick CdZnTe segmented monolithic pad and strip detectors showing energy resolutions less than 2% FWHM at 356 keV gamma rays. The third part discusses advantages and disadvantages of CdTe and CdZnTe detectors in imaging systems and describes new developments for medical diagnostics imaging systems

Heavy Ion Physics at the LHC with the ATLAS Detector

CERN Document Server

Steinberg, P.

2007-01-01

The ATLAS detector at CERN will provide a high-resolution longitudinally-segmented calorimeter and precision tracking for the upcoming study of heavy ion collisions at the LHC (sqrt{s_{NN}=5520 GeV). The calorimeter covers |eta|<5 with both electromagnetic and hadronic sections, while the inner detector spectrometer covers |eta|<2.5. ATLAS will study a full range of observables necessary to characterize the hot and dense matter formed at the LHC. Global measurements (particle multiplicities, collective flow) will provide access into its thermodynamic and hydrodynamic properties. Measuring complete jets out to 100's of GeV will allow detailed studies of energy loss and its effect on jets. Quarkonia will provide a handle on deconfinement mechanisms. ATLAS will also study the structure of the nucleon and nucleus using forward physics probes and ultraperipheral collisions, both enabled by segmented Zero Degree Calorimeters.

Heavy ion physics at the LHC with the ATLAS detector

International Nuclear Information System (INIS)

Steinberg, P

2007-01-01

The ATLAS detector at CERN will provide a high-resolution longitudinally segmented calorimeter and precision tracking for the upcoming study of heavy ion collisions at the LHC (√s NN = 5520 GeV). The calorimeter covers |η| < 5 with both electromagnetic and hadronic sections, while the inner detector spectrometer covers |η| < 2.5. ATLAS will study a full range of observables necessary to characterize the hot and dense matter formed at the LHC. Global measurements (particle multiplicities, collective flow) will provide access into its thermodynamic and hydrodynamic properties. Measuring complete jets out to 100's of GeV will allow detailed studies of energy loss and its effect on jets. Quarkonia will provide a handle on deconfinement mechanisms. ATLAS will also study the structure of the nucleon and nucleus using forward physics probes and ultraperipheral collisions, both enabled by segmented zero degree calorimeters

The BaBar LST Detector High Voltage System: Design And Implementation

International Nuclear Information System (INIS)

Benelli, G.; Honscheid, K.; Lewis, E.A.; Regensburger, J.J.; Smith, D.S.; Ohio State U.

2006-01-01

In 2004, the first two sextants of the new Limited Streamer Tube (LST) detector were installed in the BABAR experiment to replace the ageing Resistive Plate Chambers (RPCs) as active detectors for the BABAR Instrumented Flux Return (IFR) muon system. Each streamer tube of the new detector consists of 8 cells. The cell walls are coated with graphite paint and a 100 (micro)m wire forms the anode. These wires are coupled in pairs inside the tubes resulting in 4 independent two-cell segments per LST. High voltage (HV) is applied to the 4 segments through a custom connector that also provides the decoupling capacitor to pick up the detector signals from the anode wires. The BABAR LST detector is operated at 5.5 kV. The high voltage system for the LST detector was designed and built at The Ohio State University (OSU HVPS). Each of the 25 supplies built for BaBar provides 80 output channels with individual current monitoring and overcurrent protection. For each group of 20 channels the HV can be adjusted between 0 and 6 kV. A 4-fold fan-out is integrated in the power supplies to provide a total of 320 outputs. The power supplies are controlled through built-in CANbus and Ethernet (TCP/IP) interfaces. In this presentation we will discuss the design and novel features of the OSU HVPS system and its integration into the BABAR EPICS detector control framework. Experience with the supplies operation during the LST extensive quality control program and their performance during the initial data taking period will be discussed

Segmented-spectrum detection mechanism for medical x-ray in CdTe

Science.gov (United States)

Shi, Zaifeng; Meng, Qingzhen; Cao, Qingjie; Yao, Suying

2016-01-01

This paper presents a segmented X-ray spectrum detection method based on a layered X-ray detector in Cadmium Telluride (CdTe) substrate. We describe the three-dimensional structure of proposed detector pixel and investigate the matched spectrum-resolving method. Polychromatic X-ray beam enter the CdTe substrate edge on and will be absorbed completely in different thickness varying with photon energy. Discrete potential wells are formed under external controlling voltage to collect the photo-electrons generated in different layers, and segmented X-ray spectrum can be deduced from the quantity of photo-electrons. In this work, we verify the feasibility of the segmented-spectrum detection mechanism by simulating the absorption of monochromatic X-ray in a CdTe substrate. Experiments in simulation show that the number of photo-electrons grow exponentially with the increase of incident thickness, and photons with different energy will be absorbed in various thickness. The charges generated in different layers are collected into adjacent potential wells, and collection efficiency is estimated to be about 87% for different incident intensity under the 40000V/cm electric field. Errors caused by charge sharing between neighboring layers are also analyzed, and it can be considered negligible by setting appropriate size of electrodes.

Assay of plutonium contaminated waste by gamma spectrometry

International Nuclear Information System (INIS)

Adsley, I.; Bull, R.; Davies, M.; Green, M.

2011-01-01

The extreme toxicity of plutonium necessitates the segregation of plutonium contaminated materials (PCM) with extremely small (sub-μg) levels of contamination. The driver to measure accurately these small quantities of plutonium within (relatively) large volumes of waste is (in part) financial. In particular the cost of disposal (per unit volume) rises steeply with increasing waste-category. Within the UK, there has been a historical reluctance to use low energy gamma radiation to sentence PCM because of the potential for self attenuation by dense materials. This is unfortunate because the low-energy gamma radiation from PCM offers the only practicable technique for segregating PCM within the various Low Level Waste (LLW) (>0.4Bq/g) and sub-LLW categories. Whilst passive neutron counting techniques have proved successful for assay of waste well into the Intermediate Level Waste (ILW) (>100Bq/g) category, a cursory study reveals that these techniques are barely capable of detecting mg quantities of plutonium -- let alone the sub-μg quantities present in LLW. This paper considers the use of two types of gamma detector for assay of PCM: the thin sodium iodide FIDLER (Field Instrument for the Detection of Low Energy Radiation) and the HPGe (High Purity Germanium) detector. Systems utilising these two types of detector can provide complementary information. FIDLER measurements are conducted by careful, local, systematic monitoring of surfaces. By contrast a HPGe detector can be used to monitor entire walls, or even rooms, in one measurement. Thus, a HPGe detector placed in the centre of room (from which any radioactive hot-spots have previously been removed) could be used to demonstrate that the average activity remaining close to the surface of the walls/floor/ceiling is below a given limit. The Monte Carlo Code MCNP 1 has been used to model both FIDLER probe and HPGe detector in the measurement geometries described above. The MCNP simulations have been validated

Nuclear techniques and results of Romanian Black sea monitoring in the radioecological laboratory of Romanian Marine Research Institute

International Nuclear Information System (INIS)

Patrascu, V.

1999-01-01

Preliminary studies included measurement of total beta radioactivity in environmental samples using plastic scintillation detectors. For gamma detection HPGe detector with a multi-channel analyzer ORTEC-NORLAND 5500 was used and for measurements of tritium and 14 C liquid scintillation counting was used

An analytical calculation of the peak efficiency for cylindrical sources perpendicular to the detector axis in gamma-ray spectrometry

Energy Technology Data Exchange (ETDEWEB)

Aguiar, Julio C. [Autoridad Regulatoria Nuclear, Laboratorio de Espectrometria Gamma-CTBTO, Av. Del Libertador 8250, C1429BNP Buenos Aires (Argentina)], E-mail: jaguiar@sede.arn.gov.ar

2008-08-15

An analytical expression for the so-called full-energy peak efficiency {epsilon}(E) for cylindrical source with perpendicular axis to an HPGe detector is derived, using point-source measurements. The formula covers different measuring distances, matrix compositions, densities and gamma-ray energies; the only assumption is that the radioactivity is homogeneously distributed within the source. The term for the photon self-attenuation is included in the calculation. Measurements were made using three different sized cylindrical sources of {sup 241}Am, {sup 57}Co, {sup 137}Cs, {sup 54}Mn, and {sup 60}Co with corresponding peaks of 59.5, 122, 662, 835, 1173, and 1332 keV, respectively, and one measurement of radioactive waste drum for 662, 1173, and 1332 keV.

Automatic segmentation of mandible in panoramic x-ray.

Science.gov (United States)

Abdi, Amir Hossein; Kasaei, Shohreh; Mehdizadeh, Mojdeh

2015-10-01

As the panoramic x-ray is the most common extraoral radiography in dentistry, segmentation of its anatomical structures facilitates diagnosis and registration of dental records. This study presents a fast and accurate method for automatic segmentation of mandible in panoramic x-rays. In the proposed four-step algorithm, a superior border is extracted through horizontal integral projections. A modified Canny edge detector accompanied by morphological operators extracts the inferior border of the mandible body. The exterior borders of ramuses are extracted through a contour tracing method based on the average model of mandible. The best-matched template is fetched from the atlas of mandibles to complete the contour of left and right processes. The algorithm was tested on a set of 95 panoramic x-rays. Evaluating the results against manual segmentations of three expert dentists showed that the method is robust. It achieved an average performance of [Formula: see text] in Dice similarity, specificity, and sensitivity.

Interesting detector shapes for 3rd generation CT

Energy Technology Data Exchange (ETDEWEB)

Kachelriess, Marc [Erlangen-Nuernberg Univ., Erlangen (Germany). Inst. of Medical Physics (IMP)

2011-07-01

Third generation CT scanners typically comprise detectors which are flat or whose shape is the segment of a cylinder or a sphere that is focussed onto the focal spot of the X-ray source. There appear to be two design criteria that favor this choice of detector shape. One is the possibility of performing fan-beam and cone-beam filtered backprojection in the native geometry (without rebinning) and the other criterium is to enable the use of focussed anti scatter grids. It is less known, however, that other detector shapes may also have these properties. While these designs have been evaluated for 2D CT from a rather theoretical standpoint more than one decade ago we revisit and generalize these considerations, extend them to 3D circular, sequential and spiral cone-beam CT and propose an optimal design in terms of detector costs. (orig.)

Fast neutron activation analysis and radioisotope X-ray fluorescence study on KALEWA and NAMMA coal

Energy Technology Data Exchange (ETDEWEB)

Naing-Win, [Arts and Science University, Yangon (Myanmar)

1981-07-01

Kalewa coal was studied with Fast Neutron Activation Analysis (FNAA) technique, employing KAMAN A-710 neutron generator and HP(Ge) detector coupled to ``Canberra`` series 30 MCA. Sequential irradiation and dual aluminium foil monitoring method was employed. Simultaneous multielement analysis was carried out. Namma Coal was studied with radioisotope X-ray Fluorescence (XRF) technique, employing Co-57 exciter source and HP(Ge) detector coupled to ``Canberra`` series 40 MCA. In both FNAA and XRF study, the results obtained were compared to that obtained with Atomic Absorption Spectrophotometry (AAS) technique. Finally, the results were reviewed together with those obtained from similar work on coal with FNAA and XRF techniques. (author).

Fast neutron activation analysis and radioisotope X-ray fluorescence study on KALEWA and NAMMA coal

International Nuclear Information System (INIS)

Naing-Win

1981-07-01

Kalewa coal was studied with Fast Neutron Activation Analysis (FNAA) technique, employing KAMAN A-710 neutron generator and HP(Ge) detector coupled to ''Canberra'' series 30 MCA. Sequential irradiation and dual aluminium foil monitoring method was employed. Simultaneous multielement analysis was carried out. Namma Coal was studied with radioisotope X-ray Fluorescence (XRF) technique, employing Co-57 exciter source and HP(Ge) detector coupled to ''Canberra'' series 40 MCA. In both FNAA and XRF study, the results obtained were compared to that obtained with Atomic Absorption Spectrophotometry (AAS) technique. Finally, the results were reviewed together with those obtained from similar work on coal with FNAA and XRF techniques. (author)

A many particle-tracking detector with drift planes and segmented cathode readout

International Nuclear Information System (INIS)

Fischer, J.; Lissauer, D.; Ludlam, T.; Makowiecki, D.; O'Brien, E.; Radeka, V.; Rescia, S.; Rogers, L.; Smith, G.C.; Stephani, D.; Yu, B.; Greene, S.V.; Hemmick, T.K.; Mitchell, J.T.; Shivakumar, B.

1990-01-01

We describe the design and performance of a detector system for tracking charged particles in an environment of high track density and rates up to 1 MHz. The system operates in the forward spectrometer of the BNL Heavy Ion experiment E814 and uses principles of general interest in high rate, high multiplicity applications such as at RHIC or SSC. We require our system to perform over a large dynamic range, detecting singly charged particles as well as fully ionized relativistic 28 Si. Results on gas gain saturation, δ-ray suppression, and overall detector performance in the presence of a 14.6 GeV/nucleon 28 Si beam and a 14 GeV proton beam are presented. 6 refs., 9 figs

BFROST: binary features from robust orientation segment tests accelerated on the GPU

CSIR Research Space (South Africa)

Cronje, J

2011-11-01

Full Text Available purpose parallel algo- rithms. The CUDA (Compute Unified Device Architecture) [1] framework from NVidia provides a programmable interface for GPUs. FAST (Features from Accelerated Segment Tests) [2], [3] is one of the fastest and most reliable corner... runs. Our detector detects slightly more keypoints because the decision tree of FAST does not perform a complete segment test. Timing comparisons were performed on a NVidia GeForce GTX 460 for our GPU implementation and on a Intel Core i7 2.67 GHz...

A neural method for determining electromagnetic shower positions in laterally segmented calorimeters

International Nuclear Information System (INIS)

Roy, A.; Ray, A.; Mitra, T.; Roy, A.

1995-01-01

A method based on a neural network technique is proposed to calculate the coordinates of an incident photon striking a laterally segmented calorimeter and depositing shower energies in different segments. The technique uses a multilayer perceptron trained by back-propagation implemented through standard gradient descent followed by conjugate gradient algorithms and has been demonstrated with GEANT simulations of a BAF2 detector array. The position resolution results obtained by using this method are found to be substantially better than the first moment method with logarithmic weighting. (orig.)

Development of Trigger and Readout Electronics for the ATLAS New Small Wheel Detector Upgrade

CERN Document Server

Antrim, Daniel Joseph; The ATLAS collaboration

2017-01-01

The present small wheel muon detector at ATLAS will be replaced with a New Small Wheel (NSW) detector to handle the increase in data rates and harsh radiation environment expected at the LHC. Resistive Micromegas and small-strip Thin Gap Chambers will be used to provide both trigger and tracking primitives. Muon segments found at NSW will be combined with the segments found at the Big Wheel to determine the muon transverse momentum at the first-level trigger. A new trigger and readout system is developed for the NSW detector. The new system has about 2.4 million trigger and readout channels and about 8,000 frontend boards. The large number of input channels, short time available to prepare and transmit data, harsh radiation environment, and low power consumption all impose great challenges on the design. We will discuss the overall electronics design and studies with various ASIC and board prototypes.

Computer-aided design and construction of an antineutrino detector

International Nuclear Information System (INIS)

Stutz, A.

1989-01-01

The Bugey group is setting-up a new detector for another neutrino oscillation experiment. This thesis reports on the different steps concerning its realisation. Light yield, light transmission and pulse shape discrimination properties of NE 320 a new liquid scintillator loaded with 0.15% of Lithium 6 allow to realise a large volume detector (3 x 600 l) with an order of magnitude increase in sensitivity. The benefit of the neutron capture on Lithium 6 has been conserved owing to the segmentation of the whole detector volume in 98 cells and to energy resolution and pulse shape discrimination properties of the liquid. The efficiency is expected to be 0.5 and the essential component of the background is the natural activity of the scintillator. This makes this detector the most performant for neutrino oscillation experiment at reactor [fr

Flat detectors and their clinical applications

International Nuclear Information System (INIS)

Spahn, Martin

2005-01-01

Diagnostic and interventional flat detector X-ray systems are penetrating the market in all application segments. First introduced in radiography and mammography, they have conquered cardiac and general angiography and are getting increasing attention in fluoroscopy. Two flat detector technologies prevail. The dominating method is based on an indirect X-ray conversion process, using cesium iodide scintillators. It offers considerable advantages in radiography, angiography and fluoroscopy. The other method employs a direct converter such as selenium which is particularly suitable for mammography. Both flat detector technologies are based on amorphous silicon active pixel matrices. Flat detectors facilitate the clinical workflow in radiographic rooms, foster improved image quality and provide the potential to reduce dose. This added value is based on their large dynamic range, their high sensitivity to X-rays and the instant availability of the image. Advanced image processing is instrumental in these improvements and expand the range of conventional diagnostic methods. In angiography and fluoroscopy the transition from image intensifiers to flat detectors is facilitated by ample advantages they offer, such as distortion-free images, excellent coarse contrast, large dynamic range and high X-ray sensitivity. These characteristics and their compatibility with strong magnetic fields are the basis for improved diagnostic methods and innovative interventional applications. (orig.)

A new detector array for charged particle spectroscopy

CERN Document Server

Cowin, R L; Chappell, S P G; Clarke, N M; Freer, M; Fulton, B R; Cunningham, R A; Curtis, N; Dillon, G; Lilley, J; Jones, C D; Lee, P; Rae, W D M

1999-01-01

A compact and highly segmented detector array consisting of 44 gas-silicon-caesium iodide, position sensitive, particle identification detector telescopes and up to 10 position-sensitive, silicon strip detectors has been constructed for the study of light-ion-heavy-ion reactions including cluster break-up in the energy range 5-15 MeV/nucleon. The detectors are housed in a purpose built vacuum chamber. The telescopes are placed in fixed positions, covering the forward hemisphere from 3 to 30 deg. in the laboratory with the target placed at 535 mm from the front of the telescopes or 6-52 deg. with the target placed at 215 mm. The strip detectors are placed in any of 30 fixed positions in the forward hemisphere. For 85 MeV sup 1 sup 2 C ions the telescope energy resolution (gas plus silicon) is 345 keV with an angular resolution of 0.03 deg. . Using the gas-silicon section ions with Z up to 21 can be identified. For ions that pass through the silicon isotopic identification is achieved using the silicon-CsI comb...

Learning to Segment Human by Watching YouTube.

Science.gov (United States)

Liang, Xiaodan; Wei, Yunchao; Chen, Yunpeng; Shen, Xiaohui; Yang, Jianchao; Lin, Liang; Yan, Shuicheng

2016-08-05

An intuition on human segmentation is that when a human is moving in a video, the video-context (e.g., appearance and motion clues) may potentially infer reasonable mask information for the whole human body. Inspired by this, based on popular deep convolutional neural networks (CNN), we explore a very-weakly supervised learning framework for human segmentation task, where only an imperfect human detector is available along with massive weakly-labeled YouTube videos. In our solution, the video-context guided human mask inference and CNN based segmentation network learning iterate to mutually enhance each other until no further improvement gains. In the first step, each video is decomposed into supervoxels by the unsupervised video segmentation. The superpixels within the supervoxels are then classified as human or non-human by graph optimization with unary energies from the imperfect human detection results and the predicted confidence maps by the CNN trained in the previous iteration. In the second step, the video-context derived human masks are used as direct labels to train CNN. Extensive experiments on the challenging PASCAL VOC 2012 semantic segmentation benchmark demonstrate that the proposed framework has already achieved superior results than all previous weakly-supervised methods with object class or bounding box annotations. In addition, by augmenting with the annotated masks from PASCAL VOC 2012, our method reaches a new stateof- the-art performance on the human segmentation task.

Studies on MCM-D pixel-detector-modules

CERN Document Server

Flick, T; Gerlach, P; Grah, C; Mättig, P; Rohe, T

2003-01-01

In the context of the development of the ATLAS-pixel-detector, a technology for building up the high density interconnects has been studied, the MCM-D (multichip module deposited) technology. Results of building up first assemblies have been reported. MCM-D technology allows to build up assemblies with uniformly segmented sensors. Especially the use of 'equal-sized(-bricked)' sensor geometry has been studied.

A large-acceptance Bragg curve spectrometer with a longitudinal electric field and a segmented anode

International Nuclear Information System (INIS)

Farrar, K.A.; Hasan, A.T.; Prosser, F.W.; Sanders, S.J.; Henderson, D.J.

1994-01-01

A large-acceptance Bragg curve spectrometer with a longitudinal electron collection field and a segmented anode has been constructed and tested. The effects on the charge resolution of the entrance angle and entrance position of the incident particle have been studied. Simulations have been done in order to isolate the contribution to the overall detector performance of the signal-shaping electronics from that of the intrinsic design of the detector. ((orig.))

Monitoring of absolute mirror alignment at COMPASS RICH-1 detector

Energy Technology Data Exchange (ETDEWEB)

Alexeev, M. [INFN, Sezione di Torino and University of East Piemonte, Alessandria (Italy); INFN, Sezione di Trieste and University of Bari, Bari (Italy); Birsa, R. [INFN, Sezione di Trieste, Trieste (Italy); Bradamante, F.; Bressan, A. [INFN, Sezione di Trieste and University of Trieste, Trieste (Italy); Chiosso, M. [INFN, Sezione di Torino and University of Torino, Torino (Italy); Ciliberti, P. [INFN, Sezione di Trieste and University of Trieste, Trieste (Italy); Dalla Torre, S. [INFN, Sezione di Trieste, Trieste (Italy); Denisov, O. [INFN, Sezione di Torino, Torino (Italy); Duic, V. [INFN, Sezione di Trieste and University of Trieste, Trieste (Italy); Ferrero, A. [INFN, Sezione di Torino and University of Torino, Torino (Italy); Finger, M.; Finger, M. [Charles University, Prague (Czech Republic); JINR, Dubna (Russian Federation); Gayde, J.Ch. [CERN, European Organization for Nuclear Research, Geneva (Switzerland); Giorgi, M. [INFN, Sezione di Trieste and University of Trieste, Trieste (Italy); Gobbo, B.; Levorato, S. [INFN, Sezione di Trieste, Trieste (Italy); Maggiora, A. [INFN, Sezione di Torino, Torino (Italy); Martin, A. [INFN, Sezione di Trieste and University of Trieste, Trieste (Italy); Menon, G. [INFN, Sezione di Trieste, Trieste (Italy); Panzieri, D. [INFN, Sezione di Torino and University of East Piemonte, Alessandria (Italy); and others

2014-12-01

The gaseous COMPASS RICH-1 detector uses two spherical mirror surfaces, segmented into 116 individual mirrors, to focus the Cherenkov photons onto the detector plane. Any mirror misalignment directly affects the detector resolution. The on-line Continuous Line Alignment and Monitoring (CLAM) photogrammetry-based method has been implemented to measure the alignment of individual mirrors which can be characterized by the center of curvature. The mirror wall reflects a regular grid of retroreflective strips placed inside the detector vessel. Then, the position of each mirror is determined from the image of the grid reflection. The images are collected by four cameras. Any small mirror misalignment results in changes of the grid lines’ positions in the image. The accuracy limits of the CLAM method were checked by laser interferometry and are below 0.1 mrad.

Response function of an HPGe detector simulated through MCNP 4A varying the density and chemical composition of the matrix

International Nuclear Information System (INIS)

Leal A, B.; Mireles G, F.; Quirino T, L.; Pinedo, J.L.

2005-01-01

In the area of the Radiological Safety it is required of a calibrated detection system in energy and efficiency for the determination of the concentration in activity in samples that vary in chemical composition and by this in density. The area of Nuclear Engineering requires to find the grade of isotopic enrichment of the uranium of the Sub-critic Nuclear Chicago 9000 Mark. Given the experimental importance that has the determination from the curves of efficiency to the effects of establishing the quantitative results, is appealed to the simulation of the response function of the detector used in the Regional Center of Nuclear Studies inside the range of energy of 80 keV to 1400 keV varying the density of the matrix and the chemical composition by means of the application of the Monte Carlo code MCNP-4A. The obtained results in the simulation of the response function of the detector show a grade of acceptance in the range from 500 to 1400 keV energy, with a smaller percentage discrepancy to 10%, in the range of low energy that its go from 59 to 400 keV, the percentage discrepancy varies from 17% until 30%, which is manifested in the opposing isotopic relationship for 5 fuel rods of the Sub critic nuclear assemble. (Author)

Software for the on-off-line A-A-T coincidence experiment with use of semiconductor detector of nuclear radiation

International Nuclear Information System (INIS)

Samatov, Zh.K.; Fominyh, V.I.; Gromov, K.Ya; Samatov, Zh.K.; Safarov, A.N.

2006-01-01

Full text: In γ-spectra measurements with 200 cm 3 HPGe-detector with energy resolution (FWHM) of 3.5 keV for α-rays 1.33 MeV 60 Co, 60 cm 3 Ge(Li)-detector with energy resolution of 1.9 keV for γ -rays 1.33 MeV 60 Co, 2 cm 3 HPGe-detector with energy resolution of 1.0 keV for α-rays 122 keV 57 Co and planar 250 mm 3 HPGe-detector with energy resolution of 0.5 keV for γ -rays 53 keV 133 Ba. For accumulation and analysis of the experimental information the analog electronics produced companies ORTEC, CANBERRA, Dzhelepov Laboratory of Nuclear Problem of JINR, units of the digital electronics of standard KAMAK, personal computers were used. The accumulation of information on the coincidence spectra was provided by record of each event (E 1 , E 2 , t)-coincidence (in list mode) and single spectra E 1 and E 2 that gave the broad possibilities for analysis result after completion experiment by means of the multiple sorting of information on spectra of the coincidences with installation the energy and time windows. In the report, a description of programs of the management and control of the on-off-line experiment designed at the begin 90-s being performed in Dubna by the YASNAPP-2 program [1-3] on the experimental complex for study nuclei far from the drip-line β-stability is given. The publication of the description of controlling programs is retard from publication of descriptions of the measuring equipment and result of the physical studies [4-6] due to in particular with creation in Institute of Nuclear Physics in Tashkent of the experimental complex γ-γ -coincidences, which can be used to accumulate the unpublished material by authors. The programs are formed in the Turbo-Pascal language with reference to the KAMAK-standard digital equipment and spectrometric equipment in standard NIM. It is properly to classify beforehand the programs in amount of 50 items: Program of the accumulation coincidence spectra of the type A-A-T with using the digital windows and

TH-CD-201-02: A Monte Carlo Investigation of a Novel Detector Arrangement for the Energy Spectrum Measurement of a 6MV Linear Accelerator

Energy Technology Data Exchange (ETDEWEB)

Taneja, S; Bartol, L; Culberson, W; DeWerd, L [School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI (United States)

2016-06-15

Purpose: Direct measurement of the energy spectrum of a 6MV linear accelerator has not been successful due to the high fluence rate, high energy nature of these photon beams. Previous work used a Compton Scattering (CS) spectrometry setup with a shielded spectrometer for spectrum measurements. Despite substantial lead shielding, excessive pulse pile-up was seen. MCNP6 transport code was used to investigate the feasibility and effectiveness of performing measurements using a novel detector setup. Methods: Simulations were performed with a shielded high-purity germanium (HPGe) semiconductor detector placed in the accelerator vault’s maze, with a 2 cm diameter collimator through a 92 cm thick concrete wall. The detector was positioned 660 cm from a scattering rod (placed at isocenter) at an angle of 45° relative to the central axis. This setup was compared with the shielded detector positioned in the room, 200 cm from the scattering rod at the same CS angle. Simulations were used to determine fluence contributions from three sources: (1) CS photons traveling through the collimator aperture, the intended signal, (2) CS scatter photons penetrating the detector shield, and (3) room-scattered photons penetrating the detector shield. Variance reduction techniques including weight windows, DXTRAN spheres, forced collisions, and energy cutoffs were used. Results: Simulations showed that the number of pulses per starting particle from an F8 detector tally for the intended signal decreased by a factor of 10{sup 2} when moving the detector out of the vault. This reduction in signal was amplified for the unwanted scatter signal which decreased by up to a factor of 10{sup 9}. Conclusion: This work used MCNP6 to show that using a vault wall to shield unwanted scatter and increasing isocenter-to-detector distance reduces unwanted fluence to the detector. This study aimed to provide motivation for future experimental work using the proposed setup.

Charge collection in silicon strip detectors

International Nuclear Information System (INIS)

Kraner, H.W.; Beuttenmuller, R.; Ludlam, T.; Hanson, A.L.; Jones, K.W.; Radeka, V.; Heijne, E.H.M.

1982-11-01

The use of position sensitive silicon detectors as very high resolution tracking devices in high energy physics experiments has been a subject of intense development over the past few years. Typical applications call for the detection of minimum ionizing particles with position measurement accuracy of 10 μm in each detector plane. The most straightforward detector geometry is that in which one of the collecting electrodes is subdivided into closely spaced strips, giving a high degree of segmentation in one coordinate. Each strip may be read out as a separate detection element, or, alternatively, resistive and/or capacitive coupling between adjacent strips may be exploited to interpolate the position via charge division measrurements. With readout techniques that couple several strips, the numer of readout channels can, in principle, be reduced by large factors without sacrificing the intrinsic position accuracy. The testing of individual strip properties and charge division between strips has been carried out with minimum ionizing particles or beams for the most part except in one case which used alphs particless scans. This paper describes the use of a highly collimated MeV proton beam for studies of the position sensing properties of representative one dimensional strip detectors

Development of Trigger and Readout Electronics for the ATLAS New Small Wheel Detector Upgrade

CERN Document Server

Guan, Liang; The ATLAS collaboration

2017-01-01

The present small wheel muon detector at ATLAS will be replaced with a New Small Wheel (NSW) detector to handle the increase in data rates and harsh radiation environment expected at the LHC. Resistive Micromegas and small strip Thin Gap Chambers will be used to provide both trigger and tracking primitives. Muon segments found at NSW will be combined with the segments found at the Big Wheel to determine the muon transverse momentum at the first-level trigger. A new trigger and readout system is developed for the NSW detector. The new system has about 2.4 million trigger and readout channels and about 8,000 Front-End boards. The large number of input channels, short time available to prepare and transmit data, harsh radiation environment, and low power consumption all impose great challenges on the design. We will discuss the overall electronics design and studies with various ASICs and high-speed circuit board prototypes.

The feasibility of well-logging measurements of arsenic levels using neutron-activation analysis

Science.gov (United States)

Oden, C.P.; Schweitzer, J.S.; McDowell, G.M.

2006-01-01

Arsenic is an extremely toxic metal, which poses a significant problem in many mining environments. Arsenic contamination is also a major problem in ground and surface waters. A feasibility study was conducted to determine if neutron-activation analysis is a practical method of measuring in situ arsenic levels. The response of hypothetical well-logging tools to arsenic was simulated using a readily available Monte Carlo simulation code (MCNP). Simulations were made for probes with both hyperpure germanium (HPGe) and bismuth germanate (BGO) detectors using accelerator and isotopic neutron sources. Both sources produce similar results; however, the BGO detector is much more susceptible to spectral interference than the HPGe detector. Spectral interference from copper can preclude low-level arsenic measurements when using the BGO detector. Results show that a borehole probe could be built that would measure arsenic concentrations of 100 ppm by weight to an uncertainty of 50 ppm in about 15 min. ?? 2006 Elsevier Ltd. All rights reserved.

Segmented gamma scanning method for measuring holdup in the spherical container

International Nuclear Information System (INIS)

Deng Jingshan; Li Ze; Gan Lin; Lu Wenguang; Dong Mingli

2007-01-01

Some special nuclear material (SNM) is inevitably deposited in the facilities (mixer, reactor) of nuclear material process line. Exactly knowing the quantity of nuclear material holdup is very important for nuclear material accountability and critical safety. This paper presents segmented gamma scanning method for SNM holdup measurement of spherical container, at the left, right and back of which other equipments exist so that the detectors can be put at the only front of container for measurement. The nuclear material deposited in the spherical container can be looked as spherical shell source, which is divided into many layers. The detectors scanning spherical shell source are moved layer by layer from the top to the bottom to obtain projection data, with which deposited material distribution can be reconstructed by using Least Square (LS) method or Maximum Likelihood (ML) method. With these methods accurate total holdup can be obtained by summing up all the segmental values reconstructed. In this paper this measurement method for holdup in the spherical container was verified with Monte-Carlo simulation calculation and experiment. (authors)

Monte Carlo simulation of muon-induced background of an anti-Compton gamma-ray spectrometer placed in a surface and underground laboratory

CERN Document Server

Vojtyla, P

2005-01-01

Simulations of cosmic ray muon induced background of an HPGe detector placed inside an anti-Compton shield on the surface and in shallow underground is described. Investigation of several model set-ups revealed some trends useful for design of low-level gamma-ray spectrometers. It has been found that background spectrum of an HPGe detector can be scaled down with the shielding depth. No important difference is observed when the same set-up of the anti-Compton spectrometer is positioned horizontally or vertically. A cosmic-muon rejection factor of at least 40 (at around 1 MeV) can be reached when the anti-Compton suppression is operational. The cosmicmuon background can be reduced to such a level that other background components prevail, like those from the residual contamination of the detector and shield materials and/or from radon, especially for the underground facilities.

Positron Emission Tomography imaging with the SmartPET system

Energy Technology Data Exchange (ETDEWEB)

Cooper, R.J. [Department of Physics, University of Liverpool, Liverpool, Merseyside L69 7ZE (United Kingdom)], E-mail: cooperrj@ornl.gov; Boston, A.J.; Boston, H.C.; Cresswell, J.R.; Grint, A.N.; Harkness, L.J.; Nolan, P.J.; Oxley, D.C.; Scraggs, D.P.; Mather, A.R. [Department of Physics, University of Liverpool, Liverpool, Merseyside L69 7ZE (United Kingdom); Lazarus, I.; Simpson, J. [STFC Daresbury Laboratory, Daresbury, Warrington, Cheshire WA4 4AD (United Kingdom)

2009-07-21