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1

HPGe Detector Efficiency Calibration Using HEU Standards  

SciTech Connect

The Analytical Development Section of SRTC was requested by the Facilities Disposition Division (FDD) to determine the holdup of enriched uranium in the 321-M facility as part of an overall deactivation project of the facility. The 321-M facility was used to fabricate enriched uranium fuel assemblies, lithium-aluminum target tubes, neptunium assemblies, and miscellaneous components for the production reactors. The facility also includes the 324-M storage building and the passageway connecting it to 321-M. The results of the holdup assays are essential for determining compliance with the Solid Waste's Waste Acceptance Criteria, Material Control and Accountability, and to meet criticality safety controls. Two measurement systems will be used to determine highly enriched uranium (HEU) holdup: One is a portable HPGe detector and EG and G Dart system that contains high voltage power supply and signal processing electronics. A personal computer with Gamma-Vision software was used to provide an MCA card, and space to store and manipulate multiple 4096-channel g-ray spectra. The other is a 2 inches x 2 inches NaI crystal with an MCA that uses a portable computer with a Canberra NaI plus card installed. This card converts the PC to a full function MCA and contains the ancillary electronics, high voltage power supply and amplifier, required for data acquisition. This report describes and documents the HPGe point, line, area, and constant geometry-constant transmission detector efficiency calibrations acquired and calculated for use in conducting holdup measurements as part of the overall deactivation project of building 321-M.

Salaymeh, S.R.

2000-10-12

2

A software package using a mesh-grid method for simulating HPGe detector efficiencies  

SciTech Connect

Traditional ways of determining the absolute full-energy peak efficiencies of high-purity germanium (HPGe) detectors are often time consuming, cost prohibitive, or not feasible. A software package, KMESS (Kevin's Mesh Efficiency Simulator Software), was developed to assist in predicting these efficiencies. It uses a semiempirical mesh-grid method and works for arbitrary source shapes and counting geometries. The model assumes that any gamma-ray source shape can be treated as a large enough collection of point sources. The code is readily adaptable, has a web-based graphical front-end. and could easily be coupled to a 3D scanner. As will be shown. this software can estimate absolute full-energy peak efficiencies with good accuracy in reasonable computation times. It has applications to the field of gamma-ray spectroscopy because it is a quick and accurate way to assist in performing quantitative analyses using HPGe detectors.

Gritzo, Russell E [Los Alamos National Laboratory; Jackman, Kevin R [REMOTE SENSING LAB; Biegalski, Steven R [UT AUSTIN

2009-01-01

3

New approach for calibration the efficiency of HpGe detectors  

NASA Astrophysics Data System (ADS)

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 214Am, 57Co, 133Ba, 152Eu, 137Cs and 60Co. 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.

Alnour, I. A.; Wagiran, H.; Ibrahim, N.; Hamzah, S.; Siong, W. B.; Elias, M. S.

2014-02-01

4

Evaluation of ANGLE(R), a code for calculating HPGe detector efficiencies  

SciTech Connect

This paper evaluates the ANGLE(reg sign) software package, an advanced efficiency calibration software for high purity germanium detectors that is distributed by ORTEC(reg sign). ANGLE(reg sign) uses a semi-empirical approach, by way of the efficiency transfer method, based on the calculated effective solid angle. This approach would have an advantage over the traditional relative and stochastic methods by decreasing the chances for systematic errors and reducing sensitivity to uncertainties in detector parameters. For experimental confirmation, a closed-end coaxial HPGe detector was used with sample geometries frequently encountered at the Los Alamos National Laboratory. The results obtained were sufficient for detector-source configurations which included intercepting layers of plexiglass and carbon graphite, but somewhat insufficient for bare source configurations.

Homan, Victoria M [Los Alamos National Laboratory

2010-10-25

5

New approach for calibration the efficiency of HpGe detectors  

SciTech Connect

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 {sup 214}Am, {sup 57}Co, {sup 133}Ba, {sup 152}Eu, {sup 137}Cs and {sup 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.

Alnour, I. A. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia and 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.; Siong, W. B.; Elias, M. S. [Malaysia Nuclear Agency (MNA), Bangi, 43000 Kajang, Selangor (Malaysia)

2014-02-12

6

Low background shielding of HPGe detector  

Microsoft Academic Search

National Radiation Protection Institute in Prague is equipped with 14 HPGe detectors with relative efficiency up to 150%. Steel shielding with one of these detectors (relative efficiency 100%) was chosen to be rebuilt to decrease minimum detectable activity (MDA). Additional lead and copper shielding was built up inside the original steel shielding to reduce the volume of the inner space

L. Trnková; P. Rulík

2009-01-01

7

Optimum condition of efficiency functions for HPGe ?-ray detectors in the 121-1408 keV energy range  

NASA Astrophysics Data System (ADS)

The optimum condition of three commonly used functions in the Genie 2000 ? spectra analysis software have been studied in the 121-1408 keV energy range. The three functions are applied for fitting the full-energy peak efficiency of the HPGe gamma-ray detector. A detailed procedure to obtain the optimum condition is described. The HPGe detector is calibrated at 11 cm by three radioactive sources of point form (152Eu, 137Cs, 60Co) providing 11 energy peaks. After data processing, results shows that the three functions used in the Genie 2000 gamma spectra analysis software fit best at orders 3-5. Lastly the standard radioactive source 133Ba is chosen to validate the results. Differences between the standard activity of 133Ba and the result obtained from the fitting functions are below 1.5%. Therefore the optimum orders of the three functions used in the Genie 2000 ? spectra analysis software are 3-5 with the 11 energy peaks.

Chen, Zhi-Lin; Song, Guo-Yang; Mu, Long; Wang, He-Yi; Xing, Shi-Xiong; Guo, Hong-Bo; Liao, Zhen-Xing; Chen, Ping; Hua, Sheng

2010-05-01

8

Efficiency calibration of an HPGe X-ray detector for quantitative PIXE analysis  

NASA Astrophysics Data System (ADS)

Particle Induced X-ray Emission (PIXE) is an analytical technique, which provides reliably and accurately quantitative results without the need of standards when the efficiency of the X-ray detection system is calibrated. The ion beam microprobe of the Ion Beam Modification and Analysis Laboratory at the University of North Texas is equipped with a 100 mm2 high purity germanium X-ray detector (Canberra GUL0110 Ultra-LEGe). In order to calibrate the efficiency of the detector for standard less PIXE analysis we have measured the X-ray yield of a set of commercially available X-ray fluorescence standards. The set contained elements from low atomic number Z = 11 (sodium) to higher atomic numbers to cover the X-ray energy region from 1.25 keV to about 20 keV where the detector is most efficient. The effective charge was obtained from the proton backscattering yield of a calibrated particle detector.

Mulware, Stephen J.; Baxley, Jacob D.; Rout, Bibhudutta; Reinert, Tilo

2014-08-01

9

Experimental and MC determination of HPGe detector efficiency in the 40-2754 keV energy range for measuring point source geometry with the source-to-detector distance of 25 cm.  

PubMed

A precise model of a 40% relative efficiency p-type HPGe detector was created for photon detection efficiency calculation using the MCNP code. All detector parameters were determined by different experiments. No experimental calibration points were used for the modification of detector parameters. The model was validated by comparing calculated and experimental full energy peak efficiencies in the 40-2754 keV energy range, for point-source geometry with the source-to-detector distance of 25 cm. PMID:16564693

Dryak, Pavel; Kovar, Petr

2006-01-01

10

Performance of HPGe Detectors in High Magnetic Fields  

E-print Network

A new generation of high-resolution hypernuclear gamma$-spectroscopy experiments with high-purity germanium detectors (HPGe) are presently designed at the FINUDA spectrometer at DAPhiNE, the Frascati phi-factory, and at PANDA, the antiproton proton hadron spectrometer at the future FAIR facility. Both, the FINUDA and PANDA spectrometers are built around the target region covering a large solid angle. To maximise the detection efficiency the HPGe detectors have to be located near the target, and therefore they have to be operated in strong magnetic fields B ~ 1 T. The performance of HPGe detectors in such an environment has not been well investigated so far. In the present work VEGA and EUROBALL Cluster HPGe detectors were tested in the field provided by the ALADiN magnet at GSI. No significant degradation of the energy resolution was found, and a change in the rise time distribution of the pulses from preamplifiers was observed. A correlation between rise time and pulse height was observed and is used to correct the measured energy, recovering the energy resolution almost completely. Moreover, no problems in the electronics due to the magnetic field were observed.

A. Sanchez Lorente; P. Achenbach; M. Agnello; T. Bressani; S. Bufalino; B. Cederwall; A. Feliciello; F. Ferro; J. Gerl; F. Iazzi; M. Kavatsyuk; I. Kojouharov; L. Majling; A. Pantaleo; M. Palomba; J. Pochodzalla; G. Raciti; N. Saito; T. R. Saito; H. Schaffner; C. Sfienti; K. Szymanska; P. -E. Tegnér

2006-12-18

11

Spectroscopy of Actinide Nuclei - Perspectives with Position Sensitive HPGe Detectors  

NASA Astrophysics Data System (ADS)

Recent advances in in-beam gamma-ray spectroscopy of actinide nuclei are based on highly efficient arrays of escape-suppressed spectrometers. The sensitivity of these detector arrays is greatly enhanced by the combination with powerful mass separators or particle detector systems. This technique is demonstrated by an experiment to investigate excited states in 234U after the one-neutron-transfer reaction 235U(d,t). In coincidence with the outgoing tritons, ?-rays were detected with the highly efficient MINIBALL spectrometer. In the near future an even enhanced sensitivity will be achieved by utilizing position sensitive HPGe detectors which will exploit the novel detection method of gamma-ray energy tracking in electrically segmented germanium detectors. An example for this novel approach is the investigation neutron-rich actinide Th and U nuclei after multi nucleon transfer reactions employing the AGATA demonstrator and PRISMA setup at LNL, Italy. A primary 136Xe beam hitting a 238U target was used to produce the nuclei of interest. Beam-like reaction products after neutron transfer were selected by the PRISMA spectrometer. Coincident ?-rays from excited states in beam and target like particles were measured with the position sensitive AGATA HPGe detectors. Improved Doppler correction and quality of the ?-spectra is based on the novel ?-ray tracking technique, which was successfully exploited in this region.

Reiter, P.; Birkenbach, B.; Kotthaus, T.

12

Measurement of ?-decay end point energy with planar HPGe detector  

NASA Astrophysics Data System (ADS)

The ? - ? coincidence measurement has been performed with a segmented planar Hyper-Pure Germanium (HPGe) detector and a single coaxial HPGe detector to determine the end point energies of nuclear ?-decays. The experimental end point energies have been determined for some of the known ?-decays in 106Rh ?106Pd. The end point energies corresponding to three weak branches in 106Rh ?106Pd decay have been measured for the first time. The ? ray and ? particle responses for the planar HPGe detector were simulated using the Monte Carlo based code GEANT3. The experimentally obtained ? spectra were successfully reproduced with the simulation.

Bhattacharjee, T.; Pandit, Deepak; Das, S. K.; Chowdhury, A.; Das, P.; Banerjee, D.; Saha, A.; Mukhopadhyay, S.; Pal, S.; Banerjee, S. R.

2014-12-01

13

Characterization and modeling of a low background HPGe detector  

E-print Network

A high efficiency, low background counting setup has been made at TIFR consisting of a special HPGe detector ($\\sim$70$\\%$) surrounded by a low activity copper+lead shield. Detailed measurements are performed with point and extended geometry sources to obtain a complete response of the detector. An effective model of the detector has been made with GEANT4 based Monte Carlo simulations which agrees with experimental data within 5$\\%$. This setup will be used for qualification and selection of radio-pure materials to be used in a cryogenic bolometer for the study of Neutrinoless Double Beta Decay in $^{124}$Sn as well as for other rare event studies. Using this setup, radio-impurities in the rock sample from India-based Neutrino Observatory (INO) site have been estimated.

Dokania, N; Mathimalar, S; Nanal, V; Pal, S; Pillay, R G

2013-01-01

14

Characterization and modeling of a low background HPGe detector  

NASA Astrophysics Data System (ADS)

A high efficiency, low background counting setup has been made at TIFR consisting of a special HPGe detector (~70%) surrounded by a low activity copper+lead shield. Detailed measurements are performed with point and extended geometry sources to obtain a complete response of the detector. An effective model of the detector has been made with GEANT4 based Monte Carlo simulations which agrees with experimental data within 5%. This setup will be used for qualification and selection of radio-pure materials to be used in a cryogenic bolometer for the study of Neutrinoless Double Beta Decay in 124Sn as well as for other rare event studies. Using this setup, radio-impurities in the rock sample from India-based Neutrino Observatory (INO) site have been estimated.

Dokania, N.; Singh, V.; Mathimalar, S.; Nanal, V.; Pal, S.; Pillay, R. G.

2014-05-01

15

Gamma-ray imaging with coaxial HPGe detector  

SciTech Connect

We report on the first experimental demonstration of Compton imaging of gamma rays with a single coaxial high-purity germanium (HPGe) detector. This imaging capability is realized by two-dimensional segmentation of the outside contact in combination with digital pulse-shape analysis, which enables to image gamma rays in 4{pi} without employing a collimator. We are able to demonstrate the ability to image the 662keV gamma ray from a {sup 137}Cs source with preliminary event selection with an angular accuracy of 5 degree with an relative efficiency of 0.2%. In addition to the 4{pi} imaging capability, such a system is characterized by its excellent energy resolution and can be implemented in any size possible for Ge detectors to achieve high efficiency.

Niedermayr, T; Vetter, K; Mihailescu, L; Schmid, G J; Beckedahl, D; Kammeraad, J; Blair, J

2005-04-12

16

Optimization of Compton-suppression and summing schemes for the TIGRESS HPGe detector array  

Microsoft Academic Search

Methods of optimizing the performance of an array of Compton-suppressed, segmented HPGe clover detectors have been developed which rely on the physical position sensitivity of both the HPGe crystals and the Compton-suppression shields. These relatively simple analysis procedures promise to improve the precision of experiments with the TRIUMF-ISAC Gamma-Ray Escape-Suppressed Spectrometer (TIGRESS). Suppression schemes will improve the efficiency and peak-to-total

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

2007-01-01

17

HPGe detectors long time behaviour in high-resolution ? spectrometry  

Microsoft Academic Search

A large set of data on long term performance of n-type HPGe detectors used in GASP, EUROBALL and CLARA ? 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,

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

2011-01-01

18

Initial Field Measurements with the Multisensor Airborne Radiation Survey (MARS) High Purity Germanium (HPGe) Detector Array  

SciTech Connect

Abstract: The Multi-sensor Airborne Radiation Survey (MARS) project has developed a new single cryostat detector array design for high purity germanium (HPGe) gamma ray spectrometers that achieves the high detection efficiency required for stand-off detection and actionable characterization of radiological threats. This approach is necessary since a high efficiency HPGe detector can only be built as an array due to limitations in growing large germanium crystals. The system is ruggedized and shock mounted for use in a variety of field applications. This paper reports on results from initial field measurements conducted in a truck and on two different boats.

Fast, James E.; Bonebrake, Christopher A.; Dorow, Kevin E.; Glasgow, Brian D.; Jensen, Jeffrey L.; Morris, Scott J.; Orrell, John L.; Pitts, W. Karl; Rohrer, John S.; Todd, Lindsay C.

2010-06-29

19

Support of low-level instrument background for HPGe detectors  

SciTech Connect

The development results for the cryostats with the low-level of instrument background supported by special design, the reduction of mass of the materials surrounding detector and application of the materials with very low content of radiation impurities are presented. The development results for HPGe detector with ultra low-level of instrument background for gamma spectrometer under the GEMMA project for investigation of the neutrino magnetic moment are presented. (authors)

Sokolov, A. D. [Baltic Scientific Instruments, Riga, LV-1005 (Latvia); Starostin, A. S. [Inst. of Theoretical and Experimental Physics, Moscow, 117218 (Russian Federation); Kuzmenko, V. I.; Rozite, A. R. [Baltic Scientific Instruments, Riga, LV-1005 (Latvia)

2011-07-01

20

Calculation of Gamma-ray Responses for HPGe Detectors with TRIPOLI-4 Monte Carlo Code  

NASA Astrophysics Data System (ADS)

The gamma-ray response calculation of HPGe (High Purity Germanium) detector is one of the most important topics of the Monte Carlo transport codes for nuclear instrumentation applications. In this study the new options of TRIPOLI-4 Monte Carlo transport code for gamma-ray spectrometry were investigated. Recent improvements include the gamma-rays modeling of the electron-position annihilation, the low energy electron transport modeling, and the low energy characteristic X-ray production. The impact of these improvements on the detector efficiency of the gamma-ray spectrometry calculations was verified. Four models of HPGe detectors and sample sources were studied. The germanium crystal, the dead layer of the crystal, the central hole, the beryllium window, and the metal housing are the essential parts in detector modeling. A point source, a disc source, and a cylindrical extended source containing a liquid radioactive solution were used to study the TRIPOLI-4 calculations for the gamma-ray energy deposition and the gamma-ray self-shielding. The calculations of full-energy-peak and total detector efficiencies for different sample-detector geometries were performed. Using TRIPOLI-4 code, different gamma-ray energies were applied in order to establish the efficiency curves of the HPGe gamma-ray detectors.

Lee, Yi-Kang; Garg, Ruchi

2014-06-01

21

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

PubMed

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. PMID:25569199

Azli, Tarek; Chaoui, Zine-El-Abidine

2015-03-01

22

Measured and simulated performance of Compton-suppressed TIGRESS HPGe clover detectors  

Microsoft Academic Search

Tests of the performance of a 32-fold segmented HPGe clover detector coupled to a 20-fold segmented Compton-suppression shield, which form a prototype element of the TRIUMF-ISAC Gamma-Ray Escape-Suppressed Spectrometer (TIGRESS), have been made. Peak-to-total ratios and relative efficiencies have been measured for a variety of ?-ray energies. These measurements were used to validate a GEANT4 simulation of the TIGRESS detectors,

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

2007-01-01

23

Employing Thin HPGe Detectors for Gamma-Ray Imaging  

SciTech Connect

We have evaluated a collimator-less gamma-ray imaging system, which is based on thin layers of double-sided strip HPGe detectors. The position of individual gamma-ray interactions will be deduced by the strip addresses and the Ge layers which fired. Therefore, high bandwidth pulse processing is not required as in thick Ge detectors. While the drawback of such a device is the increased number of electronics channels to be read out and processed, there are several advantages, which are particularly important for remote applications: the operational voltage can be greatly reduced to fully deplete the detector and no high bandwidth signal processing electronics is required to determine positions. Only a charge sensitive preamplifier, a slow pulse shaping amplifier, and a fast discriminator are required on a per channel basis in order to determine photon energy and interaction position in three dimensions. Therefore, the power consumption and circuit board real estate can be minimized. More importantly, since the high bandwidth signal shapes are not used to determine the depth position, lower energy signals can be processed. The processing of these lower energy signals increases the efficiency for the recovery of small angle scattering. Currently, we are studying systems consisting of up to ten 2mm thick Ge layers with 2mm pitch size. The required electronics of the few hundred channels can be integrated to reduce space and power. We envision applications in nuclear non-proliferation and gamma-ray astronomy where ease of operation and low power consumption, and reliability, are crucial.

Vetter, K; Mihailescu, L; Ziock, K; Burks, M; Hull, E; Madden, N; Pehl, R

2002-04-15

24

Employing Thin HPGe Detectors for Gamma-Ray Imaging  

SciTech Connect

We have evaluated a collimator-less gamma-ray imaging system, which is based on thin layers of double-sided strip HPGe detectors. The positions of individual gamma-ray interactions will be deduced by the strip addresses and the Ge layers which fired. Therefore, high bandwidth pulse processing is not required as in thick Ge detectors. While the drawback of such a device is the increased number of electronics channels to be read out and processed, there are several advantages, which are particularly important for remote applications: the operational voltage can be greatly reduced to fully deplete the detector and no high bandwidth signal processing electronics is required to determine positions. Only a charge sensitive preamplifier, a slow pulse shaping amplifier, and a fast discriminator are required on a per channel basis in order to determine photon energy and interaction position in three dimensions. Therefore, the power consumption and circuit board real estate can be minimized. More importantly, since the high bandwidth signal shapes are not used to determine the depth position, lower energy signals can be processed. The processing of these lower energy signals increases the efficiency for the recovery of small angle scattering. Currently, we are studying systems consisting of up to ten 2mm thick Ge layers with 2mm pitch size. The required electronics of the few hundred channels can be integrated to reduce space and power. We envision applications in nuclear non-proliferation and gamma-ray astronomy where ease of operation and low power consumption, and reliability, are crucial.

Vetter, K; Mihailescu, L; Ziock, K; Burks, M; Hull, E; Madden, N; Pehl, R

2002-05-02

25

Design, fabrication and performance optimization of bi-polar blocking planar HPGe radiation detector  

NASA Astrophysics Data System (ADS)

A prototype planar radiation detector is designed, fabricated and characterized using bi-polar contact deposited on high purity single crystal germanium (HPGe). Performances of planar and semi-planar detectors are carried out for their low background counting and high absolute efficiency for high-energy photons applications. For this study, 40mm ? 15mm (diameter to vertical height) p-type HPGe samples with dislocation density EPD 3000 cm-2 are taken from HPGe ingots grown by Czochralski method. After a successful mechanical preparation, and standard cleaning and polishing procedure, samples are chemically etched by using a mixture of highly concentrated acids HF:HNO3 (1:4) in order to remove the surface oxides. A bi-polar blocking layer of amorphous germanium (a-Ge) is deposited on both the samples using low temperature RF sputtering plasma in a pre-mix precursor of H2 (15%) and Ar. For this, an optimized dose of the plasma power and chamber pressure is used for a controlled low temperature. The process was completed with the evaporation of Ohmic contacts using electron beam evaporator. This is worth noticing that special care is introduced during the handling of these samples, especially for the bi-polar blocking and metal contact layers deposition. Finally, the fabricated detectors are characterized at 77K temperature. In this paper, we show the results from the first prototype detector made of home grown crystals at USD.

Khizar, Muhammad; Wang, Guojian; Mei, Dongming

2013-03-01

26

Comparison of background in underground HPGe-detectors in different lead shield configurations.  

PubMed

In underground HPGe-detector systems where the cosmic ray induced background is low, it is often difficult to assess the location of background sources. In this study, background counting rates of different HPGe-detectors in different lead shields are reported with the aim of better understanding background sources. To further enhance the understanding of the variations of environmental parameters, the background as a function of time over a long period was also studied. PMID:23602708

Hult, Mikael; Lutter, Guillaume; Yüksel, Ayhan; Marissens, Gerd; Misiaszek, Marcin; Rosengård, Ulf

2013-11-01

27

Application of GEANT4 simulation on calibration of HPGe detectors for cylindrical environmental samples.  

PubMed

The determination of radionuclide activity concentration requires a prior knowledge of the full-energy peak (FEP) efficiency at all photon energies for a given measuring geometry. This problem has been partially solved by using procedures based on Monte Carlo simulations, developed in order to complement the experimental calibration procedures used in gamma-ray measurements of environmental samples. The aim of this article is to apply GEANT4 simulation for calibration of two HPGe detectors, for measurement of liquid and soil-like samples in cylindrical geometry. The efficiencies obtained using a simulation were compared with experimental results, and applied to a realistic measurement. Measurement uncertainties for both simulation and experimental values were estimated in order to see whether the results of the realistic measurement fall within acceptable limits. The trueness of the result was checked using the known activity of the measured samples provided by IAEA. PMID:24894534

Nikolic, J D; Jokovic, D; Todorovic, D; Rajacic, M

2014-06-01

28

FRAM isotopic analysis of uranium in thick-walled containers using high energy gamma rays and planar HPGe detectors.  

SciTech Connect

We describe the use of the Los Alamos FRAM isotopic analysis software to make the first reported measurements on thick-walled UF{sub 6} cylinders using small planar HPGe detectors of the type in common use at the IAEA. Heretofore, planar detector isotopic analysis measurements on uranium have used the 100-keV region and can be defeated by 10 mm of steel absorber. The analysis of planar detector measurements through 13-16 mm of steel shows that FRAM can successfully carry out these measurements and analysis in the 120-1024 keV energy range, a range previously thought to be the sole province of more efficient coaxial detectors. This paper describes the measurement conditions and results and also compares the results to other FRAM measurements with coaxial HPGe detectors. The technique of gamma-ray isotopic analysis of arbitrary samples is desirable for measuring the isotopic composition of uranium in UF{sub 6} cylinders because it does not require calibration with standards or knowledge of the cylinder wall thickness. The International Atomic Energy Agency (IAEA) uses the MGAU (Multi Group Analysis Uranium) uranium isotopic analysis software with planar high purity germanium (HPGe) detectors to measure the isotopic composition of uranium. Measurements on UF{sub 6} cylinders with 13-16-mm thick steel walls are usually unsuccessful because of the strong absorption of the 89-100 keV gamma rays and x-rays that MGAU requires for the measurement. This paper describes the use of the Los Alamos FRAM isotopic analysis software to make these measurements on UF{sub 6} cylinders. Uranium measurements with FRAM typically cover the energy range from 120-1001 keV and can easily be made through the walls of UF{sub 6} cylinders. While these measurements are usually performed with efficient coaxial HPGe detectors, this paper reports the first successful measurements using small planar HPGe detectors of the type in common use at the IAEA.

Sampson, Thomas E.; Hypes, P. A. (Philip A.); Vo, Duc T.

2002-01-01

29

Calculation of HPGe efficiency for environmental samples: comparison of EFFTRAN and GEANT4  

NASA Astrophysics Data System (ADS)

Determination of full energy peak efficiency is one of the most important tasks that have to be performed before gamma spectrometry of environmental samples. Many methods, including measurement of specific reference materials, Monte Carlo simulations, efficiency transfer and semi empirical calculations, were developed in order to complete this task. Monte Carlo simulation, based on GEANT4 simulation package and EFFTRAN efficiency transfer software are applied for the efficiency calibration of three detectors, readily used in the Environment and Radiation Protection Laboratory of Institute for Nuclear Sciences Vinca, for measurement of environmental samples. Efficiencies were calculated for water, soil and aerosol samples. The aim of this paper is to perform efficiency calculations for HPGe detectors using both GEANT4 simulation and EFFTRAN efficiency transfer software and to compare obtained results with the experimental results. This comparison should show how the two methods agree with experimentally obtained efficiencies of our measurement system and in which part of the spectrum do the discrepancies appear. The detailed knowledge of accuracy and precision of both methods should enable us to choose an appropriate method for each situation that is presented in our and other laboratories on a daily basis.

Nikolic, Jelena; Vidmar, Tim; Jokovic, Dejan; Rajacic, Milica; Todorovic, Dragana

2014-11-01

30

Phenomenological Model for Predicting the Energy Resolution of Neutron-Damaged Coaxial HPGe Detectors  

SciTech Connect

The peak energy resolution of germanium detectors deteriorates with increasing neutron fluence. This is due to hole capture at neutron-created defects in the crystal which prevents the full energy of the gamma-ray from being recorded by the detector. A phenomenological model of coaxial HPGe detectors is developed that relies on a single, dimensionless parameter that is related to the probability for immediate trapping of a mobile hole in the damaged crystal. As this trap parameter is independent of detector dimensions and type, the model is useful for predicting energy resolution as a function of neutron fluence.

C. DeW. Van Siclen; E. H. Seabury; C. J. Wharton; A. J. Caffrey

2012-10-01

31

Monte Carlo model of HPGe detectors used in routine lung counting.  

PubMed

An MCNP model of a pair of planar HPGe detectors (designated as: detector 3 and detector 4), that are used for routine lung counting at AECL, was developed. The model was benchmarked against experimental results, where a multi-line (152)Eu source was counted in several different geometrical arrangements. The best agreement for both detectors was achieved when side and back dead layers (of both detectors) were quadrupled, with respect to the ones quoted by their manufacturer (Canberra). In the case of detector 4, the agreement between simulated and measured spectra was within 4%, throughout the whole ?-spectrum, spanning 70-1600 keV. The same was true for detector 3 at the lower end of the ?-spectrum. However, at the high end of the ?-spectrum, the agreement was within 7% and 12% for (152)Eu ?-lines at 778.9 and 1408.01 keV. PMID:23747513

Atanackovic, Jovica; Kramer, Gary H; Hogue, Mark

2013-09-01

32

Comparison of the NDA of HEU Oxide between the AWCC and the HPGe Detector  

SciTech Connect

This paper compares the performance of the Active Well Coincidence Counter (AWCC) with the performance of high resolution gamma spectrometry using an HPGe detector to nondestructively assay highly enriched (HEU) oxide. Traditionally the AWCC was considered to be the more appropriate instrument for this measurement. Although the AWCC had a high degree of precision, the HPGe provided the more accurate measurement of this material. The AWCC determines mass of U-235 from the coincident pairs of neutron detections, or doubles rate. The HPGe determines the mass of both U-235 and U238, the enrichment, and the quantity of other radioisotopes. The Tl-208 gamma rays were used to verify the amount of attenuation for the HPGe analysis. Fifty-four cans of enriched U3O8 were shipped to the Y-12 National Security Complex from Los Alamos National Laboratory (LANL) under Scrap Declaration LANL-45. The declared values for net weight, mass of uranium, mass of U-235, and enrichment (percent mass of U-235 to total uranium) are shown in Table A-1. The masses of U-235 range from 104g to 2404g and the enrichment varies from 20% to 98%.

Chiang, L. G.; Oberer, R. B.; Gunn, C. A.; Dukes, E. E.; Akin, J. A.

2009-12-01

33

Surface-Alpha Backgrounds for HPGe Detectors in Neutrinoless Double-Beta Decay Experiments  

Microsoft Academic Search

The Majorana Experiment will use arrays of enriched HPGe detectors to search for the neutrinoless double-beta decay of ^76Ge. Such a decay, if found, would show lepton-number violation, confirm the Majorana nature of the neutrino, and help determine the effective Majorana neutrino mass. A potentially important background contribution to this and other double-beta decay experiments arises from decays of alpha-emitting

R. A. Johnson; T. H. Burritt; S. R. Elliott; V. M. Gehman; V. E. Guiseppe; J. F. Wilkerson

2009-01-01

34

Fabrication and Performance Tests of a Segmented P-Type HPGe Detector  

E-print Network

A p-type HPGe detector has been segmented by cutting, with a diamond saw, and etching six circumferential grooves through the Li-diffused dead layer. The degree of segmentation was tested with the 88 keV gamma rays from a well-collimated source of 109Cd. The fraction of events, recognized as occurring in more than one segment, and rejected from the energy interval 2038 +/- 5 keV, was measured as 0.59.

George S. King III; Frank T. Avignone III; Christopher E. Cox; Todd W. Hossbach; Wayne Jennings; James H. Reeves

2007-05-31

35

Triple- and quadruple-escape peaks in HPGe detectors: Experimental observation and Monte Carlo simulation  

NASA Astrophysics Data System (ADS)

The triple- and quadruple-escape peaks of 6.128 MeV photons from the F(p,??)19O16 nuclear reaction were observed in an HPGe detector. The experimental peak areas, measured in spectra projected with a restriction function that allows quantitative comparison of data from different multiplicities, are in reasonably good agreement with those predicted by Monte Carlo simulations done with the general-purpose radiation-transport code PENELOPE. The behaviour of the escape intensities was simulated for some gamma-ray energies and detector dimensions; the results obtained can be extended to other energies using an empirical function and statistical properties related to the phenomenon.

Maidana, N. L.; Brualla, L.; Vanin, V. R.; Oliveira, J. R. B.; Rizzutto, M. A.; do Nascimento, E.; Fernández-Varea, J. M.

2010-04-01

36

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

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

37

Compton-suppression and add-back techniques for the highly segmented TIGRESS HPGe clover detector array  

Microsoft Academic Search

Methods to optimize the performance of the TRIUMF-ISAC Gamma-Ray Escape-Suppressed Spectrometer (TIGRESS), an array of 12 large-volume, 32-fold segmented HPGe clover detectors to be used at the ISAC-II radioactive ion beam facility, have been developed based on GEANT4 Monte Carlo simulations. These methods rely on the segmentation of the outer electrical contacts of the TIGRESS HPGe clovers, and on the

M. A. Schumaker; C. E. Svensson

2007-01-01

38

A five-HPGe detector system for ?-? angular correlation measurements for mass-separated short-lived nuclei  

NASA Astrophysics Data System (ADS)

A multiple-detector system for ?-? angular correlation measurements has been constructed to study low-spin states populated via the ?-decay of mass-separated short-lived nuclei using an isotope separator on-line. The system consists of five-HPGe detectors which are configured at fixed angles to provide ten correlation angles of 90°, 100°, 110°, 120°, 130°, 130°, 140°, 150°, 160° and 170° simultaneously, and with short source-to-detector distance to enlarge the detection efficiencies. The performance of the system was studied with an 152Eu source in off-line experiments. The contribution of finite solid angle of detectors, random coincidences and Compton-scattered ?-rays were appropriately corrected. Difference in the coincidence efficiency among various detector pairs was experimentally evaluated, and it was concluded that this difference was almost negligible in this system. In an on-line experiment, low-spin states in 126Ba populated via the ?+-decay of 126La were investigated with this system.

Asai, M.; Kawade, K.; Yamamoto, H.; Osa, A.; Koizumi, M.; Sekine, T.

1997-02-01

39

Search for double beta decay with HPGe detectors at the Gran Sasso underground laboratory  

NASA Astrophysics Data System (ADS)

Neutrinoless double-beta decay is practically the only way to establish the Majorana nature of the neutrino mass and its decay rate provides a probe of an effective neutrino mass. Double beta experiments are long-running underground experiments with specific challenges concerning the background reduction and the long term stability. These problems are addressed in this work for the Heidelberg-Moscow (HdM), GENIUS Test Facility (TF) and GERDA experiments. The HdM experiment collected data with enriched 76Ge high purity (HPGe) detectors from 1990 to 2003. An improved analysis of HdM data is presented, exploiting new calibration and spectral shape measurements with the HdM detectors. GENIUS-TF was a test-facility that verified the feasibility of using bare germanium detectors in liquid nitrogen. The first year results of this experiment are discussed. The GERDA experiment has been designed to further increase the sensitivity by operating bare germanium detectors in a high purity cryogenic liquid, which simultaneously serves as a shielding against background and as a cooling media. In the preparatory stage of GERDA, an external background gamma flux measurement was done at the experimental site in the Hall A of the Gran Sasso laboratory. The characterization of the enriched detectors from the HdM and IGEX experiments was performed in the underground detector laboratory for the GERDA collaboration. Long term stability measurements of a bare HPGe detector in liquid argon were carried out. Based on these measurements, the first lower limit on the half-life of neutrinoless double electron capture of 36Ar was established to be 1.85*10^18 years at 68% C.L.

Chkvorets, Oleg

2008-12-01

40

Half-life measurements of lutetium-176 using underground HPGe-detectors.  

PubMed

The half-life of (176)Lu was determined by measuring the (176)Lu activity in metallic lutetium foils. Three different HPGe-detectors located 225 m underground were employed for the study. Measurements using the sum-peak method were performed and resulted in an average massic activity of (52.61±0.36) Bq g(-1). The foils were of natural isotopic abundance so using the massic activity and the value of the natural isotopic abundance of (2.59±0.01)%, a half-life of (3.722±0.029)×10(10)a could be calculated. PMID:24360858

Hult, Mikael; Vidmar, Tim; Rosengård, Ulf; Marissens, Gerd; Lutter, Guillaume; Sahin, Namik

2014-05-01

41

A model for fitting peaks induced by fast neutrons in an HPGe detector  

NASA Astrophysics Data System (ADS)

Inelastic neutron scattering in the HPGe detector produces wide, triangular-shaped peaks in the spectrum. We develop an accurate model for the peak shape and show that the inclusion of the model in the gamma spectrum analysis makes it possible to quantify fast neutron scattering in the Ge crystal and improves the estimation of the baseline. This in turn facilitates the detection of fission products present at trace levels in environmental samples. The model, together with simulations, is used to deduce some properties of the underlying neutron energy distribution. The neutron evaporation temperature of 1.1 MeV is obtained from the analysis of environmental monitoring gamma spectra.

Siiskonen, T.; Toivonen, H.

2005-03-01

42

Determining the Drift Time of Charge Carriers in P-Type Point-Contact HPGe Detectors  

E-print Network

An algorithm to measure the drift time of charge carriers in p-type point contact (PPC) high-purity germanium (HPGe) detectors from the signals processed with a charge-sensitive preamplifier is introduced. It is demonstrated that the drift times can be used to estimate the distance of charge depositions from the point contact and to characterize losses due to charge trapping. A correction for charge trapping effects over a wide range of energies is implemented using the measured drift times and is shown to improve the energy resolution by up to 30%.

R. D. Martin; M. Amman; Y. D. Chan; J. A. Detwiler; J. C. Loach; Q. Looker; P. N. Luke; A. W. P. Poon; J. Qian; K. Vetter; H. Yaver

2011-10-01

43

Search for double beta decay of $^{136}$Ce and $^{138}$Ce with HPGe gamma detector  

E-print Network

Search for double $\\beta$ decay of $^{136}$Ce and $^{138}$Ce was realized with 732 g of deeply purified cerium oxide sample measured over 1900 h with the help of an ultra-low background HPGe $\\gamma$ detector with a volume of 465 cm$^3$ at the STELLA facility of the Gran Sasso National Laboratories of the INFN (Italy). New improved half-life limits on double beta processes in the cerium isotopes were set at the level of $\\lim T_{1/2}\\sim 10^{17}-10^{18}$~yr; many of them are even two orders of magnitude larger than the best previous results.

P. Belli; R. Bernabei; R. S. Boiko; F. Cappella; R. Cerulli; F. A. Danevich; A. Incicchitti; B. N. Kropivyansky; M. Laubenstein; D. V. Poda; O. G. Polischuk; V. I. Tretyak

2014-09-09

44

Cosmic-ray induced background intercomparison with actively shielded HPGe detectors at underground locations  

E-print Network

The main background above 3\\,MeV for in-beam nuclear astrophysics studies with $\\gamma$-ray detectors is caused by cosmic-ray induced secondaries. The two commonly used suppression methods, active and passive shielding, against this kind of background were formerly considered only as alternatives in nuclear astrophysics experiments. In this work the study of the effects of active shielding against cosmic-ray induced events at a medium deep location is performed. Background spectra were recorded with two actively shielded HPGe detectors. The experiment was located at 148\\,m below the surface of the Earth in the Reiche Zeche mine in Freiberg, Germany. The results are compared to data with the same detectors at the Earth's surface, and at depths of 45\\,m and 1400\\,m, respectively.

Szücs, T; Reinhardt, T P; Schmidt, K; Takács, M P; Wagner, A; Wagner, L; Weinberger, D; Zuber, K

2015-01-01

45

Cosmic-ray induced background intercomparison with actively shielded HPGe detectors at underground locations  

E-print Network

The main background above 3\\,MeV for in-beam nuclear astrophysics studies with $\\gamma$-ray detectors is caused by cosmic-ray induced secondaries. The two commonly used suppression methods, active and passive shielding, against this kind of background were formerly considered only as alternatives in nuclear astrophysics experiments. In this work the study of the effects of active shielding against cosmic-ray induced events at a medium deep location is performed. Background spectra were recorded with two actively shielded HPGe detectors. The experiment was located at 148\\,m below the surface of the Earth in the Reiche Zeche mine in Freiberg, Germany. The results are compared to data with the same detectors at the Earth's surface, and at depths of 45\\,m and 1400\\,m, respectively.

T. Szücs; D. Bemmerer; T. P. Reinhardt; K. Schmidt; M. P. Takács; A. Wagner; L. Wagner; D. Weinberger; K. Zuber

2015-03-02

46

GEANT4 simulation of photopeak efficiency of small high purity germanium detectors for nuclear power plant applications  

Microsoft Academic Search

GEANT4 – based Monte Carlo simulations have been carried out for the determination of photo-peak efficiency of heavily shielded small high purity germanium detector (HPGe) used for monitoring radiation levels in nuclear power plants. The GEANT4 simulated values of HPGe detector efficiency for point as well as for disk sources, for two different values of collimator diameter, have been found

Shakeel Ur Rehman; Sikander M. Mirza; Nasir M. Mirza; Muhammad Tariq Siddique

2011-01-01

47

Operation of bare HPGe detectors in LAr/LN2 for the GERDA experiment  

NASA Astrophysics Data System (ADS)

GERDA is designed to search for 0???-decay of 76Ge using high purity germanium detectors (HPGe), enriched (~ 85%) in 76Ge, directly immersed in LAr which acts both as shield against ? 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) lessapprox10-3 cts/(kg-y-keV) and energy resolution (FWHM) <= 4 keV at Q?? = 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 (~ 18 kg) and six reprocessed natural HPGe detectors (~ 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 lessapprox 10-2 cts/(kg·keV·y). With an exposure of ~ 15 kg·y of 76Ge and resolution ~ 3.6 keV, the sensitivity on the half-life will be T0?1/2 3 · 1025 y (90 % C.L.) corresponding to mee < 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 (~ 20 kg of 76Ge with intrinsic b ~ 10-2 cts/(kg·keV·y). With an exposure of ~ 120 kg·y, it is expected T0?1/2 > 1.5 · 1026 y (90% C.L.) corresponding to mee < 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 refurbishment technology on long term stability and spectroscopy performance. The study started on prototype 1 (fully passivated on the borehole side). 60Co ?-irradiation of the detector in LAr resulted in an increase of the leakage current (LC), depending on the rate of LAr ionization which however is reversible. The radiation induced LC is believed to produce pairs of Ar+/e- that are drifted towards the passivation layer by the diode bias electric field (E) dispersed in LAr. In fact, E, numerically calculated by the Maxwell 2D code, resulted strong enough to drift charges before recombination, in the volume surrounding the passivation layer. Charges collected and trapped at the passivation layer cause a decrease of the its resistivity, i.e. an increase of the surface LC. The increase rate depends on the charge collection rate, on the density of trapped charge and on the starting value of the passivation layer resistivity. To study this mechanism two other detector configurations were tested. They have been irradiated in LAr to investigate the influence of both geometry and extension of the passivation layer and measurements with prototype 1 have been also repeated in LN2: prototype 2 (passivation layer only in the groove) shows a ~30 times lower LC increase rate than the case of prototype 1; prototype 3 (no passivation layer) does not show any increase of LC and prototype 1 operated in LN2 does not show any increase. The observed LC is cured by irradiation without HV, explained either by ? ionization of the passivation layer or by effect of the UV LAr scintillation light.

Barnabé Heider, M.; Cattadori, C.; Chkvorets, O.; di Vacri, A.; Gusev, K.; Schönert, S.; Shirchenko, M.

2008-11-01

48

Field analyses of (238)U and (226)Ra in two uranium mill tailings piles from Niger using portable HPGe detector.  

PubMed

The radioactivities of (238)U and (226)Ra in mill tailings from the U mines of COMINAK and SOMAÏR in Niger were measured and quantified using a portable High-Purity Germanium (HPGe) detector. The (238)U and (226)Ra activities were measured under field conditions on drilling cores with 600s measurements and without any sample preparation. Field results were compared with those obtained by Inductive Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and emanometry techniques. This comparison indicates that gamma-ray absorption by such geological samples does not cause significant deviations. This work shows the feasibility of using portable HPGe detector in the field as a preliminary method to observe variations of radionuclides concentration with the aim of identifying samples of interest. The HPGe is particularly useful for samples with strong secular disequilibrium such as mill tailings. PMID:25036918

Déjeant, Adrien; Bourva, Ludovic; Sia, Radia; Galoisy, Laurence; Calas, Georges; Phrommavanh, Vannapha; Descostes, Michael

2014-11-01

49

Estimation of background spectrum in a shielded HPGe detector using Monte Carlo simulations.  

PubMed

Monte Carlo simulations are powerful tools used to estimate the background ?-radiation detected by high-resolution gamma-ray spectrometry systems with a HPGe (high purity germanium) detector contained inside a lead shield. The purpose of this work was to examine the applicability of Monte Carlo simulations to predict the optimal lead thickness necessary to reduce the background effect in spectrometer measurements. GEANT4 code was applied to simulate the background radiation spectrum at different thicknesses of lead. The simulated results were compared with experimental measurements of background radiation taken at the same shielding thickness. The results show that the background radiation detected depends on the thickness, size and lining of the shield. Simulation showed that 12 cm lead thick is the optimal shielding thickness. PMID:24292007

Medhat, M E; Wang, Yifang

2014-02-01

50

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

SciTech Connect

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 {sup 137}Cs concentrations of the pond sediment, indicating that 9.4 {plus_minus} 1.5 Ci is exposed by the drawdown and that 46.6 {plus_minus} 7.2 Ci is the entire pond inventory. The highest individual {sup 137}Cs concentration was 25 {mu}Ci/m{sup 2} for the exposed sediment and 50 {mu}Ci/m{sup 2} for the entire pond. The results are consistent with parallel studies conducted by SREL, as well as historical data. Aside from {sup 137}Cs, the only other SRS-produced isotope observed was {sup 60}Co, with activity of only about 1% of that for {sup 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 {sup 137}Cs concentration were addressed in the calibration. Calibration factors for sediment surface concentrations ({mu}Ci/m{sup 2}/cpm) and sediment mass concentrations (pCi/kg/cpm) were obtained. In general, the {mu}Ci/m{sup 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.

Winn, W.G.

1993-11-01

51

Identifying and quantifying short-lived fission products from thermal fission of HEU using portable HPGe detectors  

SciTech Connect

Due to the emerging potential for trafficking of special nuclear material, research programs are investigating current capabilities of commercially available portable gamma ray detection systems. Presented in this paper are the results of three different portable high-purity germanium (HPGe) detectors used to identify short-lived fission products generated from thermal neutron interrogation of small samples of highly enriched uranium. Samples were irradiated at the Washington State University (WSU) Nuclear Radiation Center’s 1MW TRIGA reactor. The three portable, HPGe detectors used were the ORTEC MicroDetective, the ORTEC Detective, and the Canberra Falcon. Canberra’s GENIE-2000 software was used to analyze the spectral data collected from each detector. Ultimately, these three portable detectors were able to identify a large range of fission products showing potential for material discrimination.

Pierson, Bruce D.; Finn, Erin C.; Friese, Judah I.; Greenwood, Lawrence R.; Kephart, Jeremy D.; Kephart, Rosara F.; Metz, Lori A.

2013-03-01

52

Evaluation of radioactive background rejection in 76Ge neutrino-lessdouble-beta decay experiments using a highly segmented HPGe detector  

SciTech Connect

A highly segmented coaxial HPGe detector was operated in a low background counting facility for over 1 year to experimentally evaluate possible segmentation strategies for the proposed Majorana neutrino-less double-beta decay experiment. Segmentation schemes were evaluated on their ability to reject multi-segment events while retaining single-segment events. To quantify a segmentation scheme's acceptance efficiency the percentage of peak area due to single segment events was calculated for peaks located in the energy region 911-2614 keV. Single interaction site events were represented by the double-escape peak from the 2614 keV decay in {sup 208}Tl located at 1592 keV. In spite of its prototypical nature, the detector performed well under realistic operating conditions and required only minimal human interaction. Though the energy resolution for events with interactions in multiple segments was impacted by inter-segment cross-talk, the implementation of a cross-talk correlation matrix restored acceptable resolution. Additionally, simulations utilizing the MaGe simulation package were performed and found to be in good agreement with experimental observations verifying the external nature of the background radiation.

Chan, Yuen-Dat; Campbell, D.B.; Vetter, K.; Henning, R.; Lesko, K.; Chan, Y.D.; Poon, A.W.P.; Perry, M.; Hurley, D.; Smith, A.R.

2007-02-05

53

Estimation of immediate fallout after the accident at Fukushima Daiichi Nuclear Power Plant by using HPGe detector and EGS5 code.  

PubMed

After the accident at the Fukushima Daiichi nuclear power plant, we managed to carry out emergency measurements of the radioactive fallout. The included nuclides were identified via gamma-ray spectrometry using an HPGe detector. Quantifications of each radionuclide in the fallout were determined based on the efficiency calibrations and relevant corrections. The collected samples had a variety of shapes, densities, and compositions. EGS5 Monte Carlo code was used for the flexible estimation of these parameters. The measurement results show the temporal changes in the fallout quantity about a month after the accident. PMID:23570955

Unno, Yasuhiro; Yunoki, Akira; Sato, Yasushi; Hino, Yoshio

2013-11-01

54

Low background HPGe spectrometer in investigations of 2? decay  

SciTech Connect

The low background high sensitive HPGe spectrometer called OBELIX is briefly described. The calibration measurements using {sup 152}Eu, {sup 133}Ba and La{sub 2}O{sub 3} sources in different geometries, the obtained efficiency curves for OBELIX HPGe detector, the results of measurements of radioactivity of the NEMO-3 sources ({sup 100}Mo, {sup 150}Nd) as well as future plans for OBELIX detector (e.g. 0?EC/EC decay of {sup 106}Cd) are presented.

Rukhadze, Ekaterina [Institute of Experimental and Applied Physics, CTU in Prague, Horska 3a/22, 128 00 Prague 2 (Czech Republic)] [Institute of Experimental and Applied Physics, CTU in Prague, Horska 3a/22, 128 00 Prague 2 (Czech Republic); Collaboration: OBELIX Collaboration; TGV Collaboration; SuperNEMO Collaboration; and others

2013-08-08

55

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

NASA Astrophysics Data System (ADS)

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 ( BS) MRI field along with fast switching gradient fields and radiofrequency from the MRI system has been assessed. The influence of the BS 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 BS 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.

Harkness, L. J.; 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.; Bimson, W. E.; Kemp, G. J.; Groves, J.; Headspith, J.; Lazarus, I.; Simpson, J.; Cooper, R. J.

2011-05-01

56

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

E-print Network

The gamma-ray tracking technique is one of the 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 developed. 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. Therefore, the recoil energy distributions of germanium nuclei due to inelastic scatterings of 1-5 MeV neutrons were obtained both experimentally and using artificial neural networks. Also, for highly nonlinear detector response for recoiling germanium nuclei, we have constructed consistent empirical physical formulas (EPFs) by appropriate layered feed-forward neural networks (LFNNs). These LFNN-EPFs can be used to derive further physical functions which could be relevant to determination of neutron interactions in gamma-ray tracking process.

Serkan Akkoyun; Nihat Yildiz

2012-07-23

57

Multi-element readout of structured HPGe-detectors for high-resolution x-ray spectroscopy using CUBE-preamplifiers  

NASA Astrophysics Data System (ADS)

Very recently we have shown that CUBE-preamplifiers developed by XGLab s.r.l. can be used for the readout of single elements of thick structured planar HPGe- and Si(Li)-detectors produced by SEMIKON [1]. In this paper we will present the results of a simultaneous multi-element readout of structured detectors using the same preamplifiers for measuring high-energy x-rays (more than 100 keV) with a comparable energy resolution as for the single-element readout. Several high-purity germanium detectors (HPGe-detectors) with different position sensitive structures on one detector contact have been used for the first tests. In addition to that we have modified an existing 16-pixel HPGe-polarimeter from GSI-Darmstadt with the new readout. The detector elements (7 mm × 7 mm each, arranged in a 4 × 4 matrix) are connected to CUBE-preamplifiers used in pulse-reset mode. The technological progress achieved with this detector system resulting in a significant improved energy resolution will contribute a lot to much more precise polarization measurements of x-rays emitted from atom-ion collisions which are part of the physics program of the SPARC collaboration (Stored Particles Atomic Physics Research Collaboration) at GSI and the future FAIR accelerator facility (Facility for Antiproton and Ion Research).

Krings, T.; Spillmann, U.; Proti?, D.; Roß, C.; Stöhlker, Th.; Weber, G.; Bombelli, L.; Alberti, R.; Frizzi, T.

2015-02-01

58

Reconstruction of a Radiation Point Source's Radial Location Using Goodness-of-Fit Test on Spectra Obtained from an HPGe Detector  

E-print Network

High purity germanium (HPGe) detectors are ubiquitous in nuclear physics experiments and are also used in numerous low radioactive background detectors. The effect of the position of $^{60}$Co and $^{137}$Cs point sources on the shape of spectra were studied with Monte Carlo and HPGe detector measurements. We briefly confirm previous work on the position dependence of relative heights of peaks. Spectra taken with the radiation sources placed at locations around the detector were then compared using the Kolmogorov-Smirnov (K-S) goodness-of-fit test. We demonstrate that with this method the Compton continuum spectral shape has good sensitivity to the radial location of a point-source, but poor angular resolution. We conclude with a study of the position reconstruction accuracy as a function of the number of counts from the source.

L. T. Evans; K. Andre; R. De; R. Henning; E. D. Morgan

2009-08-16

59

Subspace Detectors: Efficient Implementation  

SciTech Connect

The optimum detector for a known signal in white Gaussian background noise is the matched filter, also known as a correlation detector [Van Trees, 1968]. Correlation detectors offer exquisite sensitivity (high probability of detection at a fixed false alarm rate), but require perfect knowledge of the signal. The sensitivity of correlation detectors is increased by the availability of multichannel data, something common in seismic applications due to the prevalence of three-component stations and arrays. When the signal is imperfectly known, an extension of the correlation detector, the subspace detector, may be able to capture much of the performance of a matched filter [Harris, 2006]. In order to apply a subspace detector, the signal to be detected must be known to lie in a signal subspace of dimension d {ge} 1, which is defined by a set of d linearly-independent basis waveforms. The basis is constructed to span the range of signals anticipated to be emitted by a source of interest. Correlation detectors operate by computing a running correlation coefficient between a template waveform (the signal to be detected) and the data from a window sliding continuously along a data stream. The template waveform and the continuous data stream may be multichannel, as would be true for a three-component seismic station or an array. In such cases, the appropriate correlation operation computes the individual correlations channel-for-channel and sums the result (Figure 1). Both the waveform matching that occurs when a target signal is present and the cross-channel stacking provide processing gain. For a three-component station processing gain occurs from matching the time-history of the signals and their polarization structure. The projection operation that is at the heart of the subspace detector can be expensive to compute if implemented in a straightforward manner, i.e. with direct-form convolutions. The purpose of this report is to indicate how the projection can be computed efficiently for continuous multichannel seismic data. The speed of the calculation is significant as it may become desirable to deploy subspace detectors numbering in the thousands. One application contemplated for these detectors is as screens against signals from repeating sources such as mines or aftershocks of large earthquakes. With many tens of stations and potentially hundreds of sources to screen, efficient implementations are desirable. Speed, of course, can be achieved by procuring faster computers or special-purpose hardware. The approach we examine here is the development of two efficient algorithms that can make the calculations run faster on any machine. In the first section, we describe the subspace detector as we use it for the detection of repeating seismic events, defining terms and the parameterization used in succeeding sections. This section also reviews how the correlation computations central to the matched filter and subspace detectors can be implemented as a collection of convolution operations. Convolution algorithms using fast Fourier transforms, such as the overlap-add and overlap-save methods, have long been known as efficient implementations of discrete-time finite-impulse-response filters [e.g. Oppenheim and Schafer, 1975]. These may be extended in a straightforward manner to implement multichannel correlation detectors. In the second section, we describe how multichannel data can be multiplexed to compute the required convolutions with a single pair of FFT operations instead of a pair for each channel. This approach increases speed approximately twofold. Seismic data, almost invariably, are oversampled. This characteristic provides an opportunity for increased efficiency by decimating the data prior to performing the correlation calculations. In the third section, we describe a bandpass transformation of the data that allows a more aggressive decimation of the data without significant loss of fidelity in the correlation calculation. The transformation computes a complex-analytic representation for the template waveforms and the

Harris, D B; Paik, T

2006-07-26

60

Detection of pulsed, bremsstrahlung-induced, prompt neutron capture gamma-rays with HPGe detector  

SciTech Connect

The Idaho National Engineering Laboratory (INEL) is developing a novel photoneutron-based nondestructive evaluation technique which uses a pulsed, high-energy (up to 8-MeV) electron accelerator and gamma-ray spectrometry. Highly penetrating pulses of bremsstrahlung photons are produced by each pulse of electrons. Interrogating neutrons are generated by the bremsstrahlung photons interacting within a photoneutron source material. The interactions of the neutrons within a target result in the emission of elemental characteristic gamma-rays. Spectrometry is performed by analyzing the photoneutron-induced prompt gamma-rays acquired between accelerator pulses with a unique, high-purity germanium (HPGe) gamma-ray detection system using a modified transistor reset preamplifier. The detection system, the experimental configuration, and the accelerator operation used to characterize the detection system performance are described. Using a 6.5 MeV electron accelerator and a beryllium metal photoneutron source, gamma-ray spectra were successfully acquired for Al, Cu, polyethylene, NaC1, and depleted uranium targets as soon as 30 {mu}s after each bremsstrahlung (or x-ray) flash.

Jones, J.L.

1996-08-01

61

High efficiency photoionization detector  

DOEpatents

A high efficiency photoionization detector is described using tetraaminoethylenes in a gaseous state having a low ionization potential and a relative photoionization cross section which closely matches the emission spectrum of xenon gas. Imaging proportional counters are also disclosed using the novel photoionization detector of the invention. The compound of greatest interest is TMAE which comprises tetrakis(dimethylamino)ethylene which has a measured ionization potential of 5.36 [+-] 0.02 eV, and a vapor pressure of 0.35 torr at 20 C. 6 figs.

Anderson, D.F.

1984-01-31

62

High efficiency photoionization detector  

DOEpatents

A high efficiency photoionization detector using tetraaminoethylenes in a gaseous state having a low ionization potential and a relative photoionization cross section which closely matches the emission spectrum of xenon gas. Imaging proportional counters are also disclosed using the novel photoionization detector of the invention. The compound of greatest interest is TMAE which comprises tetrakis(dimethylamino)ethylene which has a measured ionization potential of 5.36.+-.0.02 eV, and a vapor pressure of 0.35 torr at 20.degree. C.

Anderson, David F. (3055 Trinity, Los Alamos, NM 87544)

1984-01-01

63

Experimental Determination of the HPGe Spectrometer Efficiency Calibration Curves for Various Sample Geometry for Gamma Energy from 50 keV to 2000 keV  

SciTech Connect

Detection efficiency of a gamma-ray spectrometry system is dependent upon among others, energy, sample and detector geometry, volume and density of the samples. In the present study the efficiency calibration curves of newly acquired (August 2008) HPGe gamma-ray spectrometry system was carried out for four sample container geometries, namely Marinelli beaker, disc, cylindrical beaker and vial, normally used for activity determination of gamma-ray from environmental samples. Calibration standards were prepared by using known amount of analytical grade uranium trioxide ore, homogenized in plain flour into the respective containers. The ore produces gamma-rays of energy ranging from 53 keV to 1001 keV. Analytical grade potassium chloride were prepared to determine detection efficiency of 1460 keV gamma-ray emitted by potassium isotope K-40. Plots of detection efficiency against gamma-ray energy for the four sample geometries were found to fit smoothly to a general form of {epsilon} = A{Epsilon}{sup a}+B{Epsilon}{sup b}, where {epsilon} is efficiency, {Epsilon} is energy in keV, A, B, a and b are constants that are dependent on the sample geometries. All calibration curves showed the presence of a ''knee'' at about 180 keV. Comparison between the four geometries showed that the efficiency of Marinelli beaker is higher than cylindrical beaker and vial, while cylindrical disk showed the lowest.

Saat, Ahmad [Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam (Malaysia); Hamzah, Zaini; Yusop, Mohammad Fariz; Zainal, Muhd Amiruddin [Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam (Malaysia)

2010-07-07

64

An approach to evaluate the efficiency of ?-ray detectors to determine the radioactivity in environmental samples  

NASA Astrophysics Data System (ADS)

This work provides an approach to determine the efficiency of ?-ray detectors with a good accuracy in order to determine the concentrations of either naturally occurring or artificially prepared radionuclides. This approach is based on the efficiency transfer formula (ET), the effective solid angles, the self- absorptions of the source matrix, the attenuation by the source container and the detector housing materials on the detector efficiency. The experimental calibration process was done using radioactive (Cylindrical & Marinelli) sources, in different dimensions, that contain aqueous 152Eu radionuclide. The comparison point to a fine agreement between the experimental measured and calculated efficiencies for the (NaI & HPGe) detectors using volumetric radioactive sources.

Mohamed., S. Badawi; Ahmed., M. El-Khatib; Samah., M. Diab; Sherif., S. Nafee; Ekram., A. El-Mallah

2014-06-01

65

A background simulation method for cosmogenic nuclides inside HPGe detectors for rare event experiments  

NASA Astrophysics Data System (ADS)

Cosmogenic nuclides inside germanium detectors contribute background noise spectra quite different from ordinary external sources. We propose and discuss a nuclide decay and level transition model based on graph theory to understand the background contribution of the decay of cosmogenic nuclides inside a germanium crystal. In this work, not only the level transition process, but the detector response time was also taken into consideration to decide whether or not to apply coincidence summing-up. We simulated the background spectrum of the internal cosmogenic nuclides in a germanium detector, and found some unique phenomena caused by the coincidence summing-up effect in the simulated spectrum. Thus, the background spectrum of each cosmogenic nuclide can be quantitatively obtained.

Su, Jian; Zeng, Zhi; Ma, Hao; Yue, Qian; Cheng, Jianping; Li, Jin

2014-11-01

66

Orthogonal Strip HPGe Planar SmartPET Detectors in Compton Configuration  

Microsoft Academic Search

The evolution of germanium detectors over the last decade has lead to the possibility that they can be used in medical imaging and security scanning. The potential of increased sensitivity and energy resolution that germanium affords takes away the necessity of mechanical collimators that would be required in a gamma camera. Without mechanical collimation the resulting increase in statistics leads

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

2006-01-01

67

Improved energy resolution of highly segmented HPGe detectors by noise reduction  

NASA Astrophysics Data System (ADS)

Built-in redundancies in highly segmented high-purity Ge detectors are exploited to increase the energy resolution of these semiconductor devices for detection of electromagnetic radiation in the X-ray and ?-ray regime. The information of the two electronically decoupled independent measurements, the cathode and the anode electrodes, provides an improved signal-to-noise ratio through a combination of the individually measured signals performed on an event-by-event basis. The average energy resolution values of the AGATA triple cluster detector for an energy deposition of 60keV was measured to be 1.1 keV (FWHM) for the 36 segments and 1.2 keV for the core. The averaged signals of the core and the segments show an improved resolution value of 0.87 keV which is close to the expected theoretical limit. At higher ?-ray energy the averaging technique allows for an enhanced energy resolution with a FWHM of 2.15keV at 1.3MeV. By means of the position sensitive operation of AGATA a new value for the Fano factor was determined and the noise contributions to the FWHM of a ?-ray peak separated.

Wiens, A.; Birkenbach, B.; Bruyneel, B.; Eberth, J.; Hess, H.; Pascovici, Gh.; Reiter, P.; Bazzacco, D.; Farnea, E.; Michelagnoli, C.; Recchia, F.

2013-04-01

68

Orthogonal strip HPGe planar SmartPET detectors in Compton configuration  

NASA Astrophysics Data System (ADS)

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.

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.

2007-10-01

69

Efficiencies of Quantum Optical Detectors  

E-print Network

We propose a definition for the efficiency that can be universally applied to all classes of quantum optical detectors. This definition is based on the maximum amount of optical loss that a physically plausible device can experience while still replicating the properties of a given detector. We prove that detector efficiency cannot be increased using linear optical processing. That is, given a set of detectors, as well as arbitrary linear optical elements and ancillary light sources, it is impossible to construct detection devices that would exhibit higher efficiencies than the initial set.

Daniel Hogg; Dominic W. Berry; A. I. Lvovsky

2014-12-15

70

Gamma-ray multiplicity measurement of the spontaneous fission decay of 252Cf in a segmented HPGe/BGO detector array  

SciTech Connect

Coincident {gamma} rays from a {sup 252}Cf source were measured using an array of six segmented high-purity germanium (HPGe) Clover detectors each enclosed by 16 bismuth-germanate (BGO) detectors. The detectors were arranged in a cubic pattern around a 1 {micro}Ci {sup 252}Cf source to cover a large solid angle for {gamma}-ray measurement with a reasonable reconstruction of the multiplicity. Neutron multiplicity was determined in certain cases by identifying the prompt {gamma} rays from individual fission fragment pairs. Multiplicity distributions from previous experiments and theoretical models were convolved with the response function of the array and compared to the present results. These results suggest a {gamma}-ray multiplicity spectrum broader than previous measurements and models, and provide no evidence of correlation with neutron multiplicity.

Bleuel, D L; Bernstein, L A; Burke, J T; Gibelin, J; Heffner, M D; Mintz, J; Norman, E B; Phair, L; Scielzo, N D; Sheets, S A; Snyderman, N J; Stoyer, M A; Wiedeking, M

2008-04-23

71

The gender-specific chest wall thickness prediction equations for routine measurements of 239Pu and 241Am within the lungs using HPGe detectors.  

PubMed

The current chest wall thickness prediction equation is not applicable to use in routine lung counting measurements for detection of low energy photons (17--60 keV) within the lungs of male and female subjects. The current chest wall thickness prediction equation was derived for the NaI-CsI "phoswich" detection system, which is not the routine detection system in use; the subject position was supine, which is not the routine position; the equation did not account for the intercostal tissue thicknesses of muscle and adipose which significantly attenuate low energy photons (17--60keV); it was derived from male subjects only and is used to predict the chest wall thickness of female subjects for whom it is not applicable. The current chest wall thickness prediction equation yields unacceptable percent errors in the HPGe detection efficiency calibration for 239Pu and 241Am (17- and 59.5-keV photons, respectively) relative to the gender-specific HPGe chest wall thickness prediction equations of this paper (+284% to --73% for 239Pu; (+)42% to --39% for 241Am). As a result, use of the current chest wall thickness prediction equation yields unacceptable percent errors (proportional in magnitude to the percent errors in the detection efficiency calibration) in the calculation of the minimum detectable activity (Bq) or in an initial assessment of a radioactive contamination exposure detected by a routine lung count measurement. PMID:8609026

Vickers, L R

1996-03-01

72

The use of Geant4 for simulations of a plastic beta-detector and its application to efficiency calibration  

E-print Network

Precise beta-branching-ratio measurements are required in order to determine ft-values as a part of our program to test the Electroweak Standard Model via unitarity of the Cabibbo-Kobayashi-Moskawa matrix. For the measurements to be useful in this test, their precision must be close to 0.1 %. In a branching-ratio measurement, we position the radioactive sample between a thin plastic scintillator used to detect beta-particles, and a HPGe detector for gamma-rays. Both beta singles and beta-gamma coincidences are recorded. Although the branching ratio depends most strongly on the HPGe detector efficiency, it has some sensitivity to the energy dependence of the beta-detector efficiency. We report here on a study of our beta-detector response function, which used Monte Carlo calculations performed by the Geant4 toolkit. Results of the simulations are compared to measured beta-spectra from several standard beta-sources.

V. V. Golovko; V. E. Iacob; J. C. Hardy

2008-06-15

73

Tests of HPGe- and scintillation-based backpack ?-radiation survey systems.  

PubMed

The performance of three different backpack-mounted ?-radiation survey systems has been investigated. The systems are based on a LaBr3:Ce detector and a NaI(Tl) detector both with active volume dimensions of 76.2 mm in diameter and 76.2 mm length and a 123% relative efficiency HPGe detector. The detection limits of the systems were tested in a controlled outdoor environment in Sweden, followed by field tests of the HPGe- and LaBr3:Ce-based systems at the site of a radioactive waste repository in Georgia (in the Caucasus region of Eurasia). The results showed that the high efficiency HPGe detector performed significantly better than similar sized LaBr3:Ce and NaI(Tl) detectors, however, the HPGe detector was significantly heavier than the other systems. The use of different analysis methods revealed that creating maps of the survey area was the best method for offline analysis of survey data collected from a large area. Using off-site personnel for analysis of the data proved to be beneficial. PMID:24776755

Nilsson, Jonas M C; Östlund, Karl; Söderberg, Joakim; Mattsson, Sören; Rääf, Christopher

2014-09-01

74

Experimentally determined vs. Monte Carlo simulated peak-to-valley ratios for a well-characterised n-type HPGe detector.  

PubMed

Measurements and simulations to investigate the contributing factors to the peak-to-valley (PTV) ratio have been both experimentally determined as well as Monte Carlo simulated for a well-characterised HPGe n-type detector together with a Cs-137 gamma source encapsulated in thin polystyrene. Measurements were carried out in a low-background gamma counting facility at Lund University. The results of the PTV ratio have been compared to distinguish what components or variables in the setup that significantly influence the ratio. In addition to manufacture specifications, the detector components have been examined using planar X-ray, source scanning and computer tomography in order to determine and verify component dimensions when necessary. In spite of these efforts a discrepancy of approximately 25% for thin absorbers in the PTV ratio between measurements and calculations is observed. However, this discrepancy becomes less significant for larger absorbing layers of copper (>1mm). This indicates that it would be difficult to achieve a field calibration for in-situ gamma spectrometry using the PTV ratio that could position a Cs-137 source in soil depth shallower than corresponding 1mm layer of copper. The results also showed that when building a detector in simulations part by part, the inner dead layer, and the contact pin are of great importance for the accuracy of the PTV ratio simulations. PMID:25464184

Ostlund, Karl; Samuelsson, Christer; Rääf, Christopher L

2014-10-23

75

High-efficiency photoionization detector  

SciTech Connect

A high efficiency photoionization detector using tetraaminoethylenes in a gaseous state having a low ionization potential and a relative photoionization cross section which closely matches the emission spectrum of xenon gas. Imaging proportional counters are also disclosed using the novel photoionization detector of the invention. The compound of greatest interest is TMAE which comprises tetrakis(dimethylamino)ethylene which has a measured ionization potential of 5.36 +- 0.02 eV, and a vapor pressure of 0.35 torr at 20/sup 0/C.

Anderson, D.F.

1981-05-12

76

Systematic uncertainties of artificial neural-network pulse-shape discrimination for $0???$-decay searches using true-coaxial HPGe detectors  

E-print Network

A pulse-shape discrimination method based on artificial neural networks was applied to pulses simulated for different background, signal and signal-like interactions inside a germanium detector. The simulated pulses were used to investigate the systematic uncertainties of the method. It is verified that neural networks are well-suited to identify background pulses in true-coaxial high-purity germanium detectors. The systematic uncertainty on the signal recognition efficiency derived using signal-like samples from calibration measurements is estimated to be 5\\%. This uncertainty is due to differences between signal and calibration samples.

I. Abt; A. Caldwell; F. Cossavella; B. Majorovits; D. Palioselitis; O. Volynets

2014-12-02

77

Development of high efficiency neutron detectors  

SciTech Connect

We have designed a novel neutron detector system using conventional {sup 3}He detector tubes and composites of polyethylene, and graphite. At this time the design consists entirely of MCNP simulations of different detector configurations and materials. These detectors are applicable to low-level passive and active neutron assay systems such as the passive add-a-source and the {sup 252}Cf shuffler. Monte Carlo simulations of these neutron detector designs achieved efficiencies of over 35% for assay chambers that can accommodate 55-gal. drums. Only slight increases in the number of detector tubes and helium pressure are required. The detectors also have reduced die-away times. Potential applications are coincident and multiplicity neutron counting for waste disposal and safeguards. We will present the general design philosophy, underlying physics, calculation mechanics, and results.

Pickrell, M.M.; Menlove, H.O.

1993-08-01

78

Efficient nucleus detector in histopathology images.  

PubMed

In traditional cancer diagnosis, (histo)pathological images of biopsy samples are visually analysed by pathologists. However, this judgment is subjective and leads to variability among pathologists. Digital scanners may enable automated objective assessment, improved quality and reduced throughput time. Nucleus detection is seen as the corner stone for a range of applications in automated assessment of (histo)pathological images. In this paper, we propose an efficient nucleus detector designed with machine learning. We applied colour deconvolution to reconstruct each applied stain. Next, we constructed a large feature set and modified AdaBoost to create two detectors, focused on different characteristics in appearance of nuclei. The proposed modification of AdaBoost enables inclusion of the computational cost of each feature during selection, thus improving the computational efficiency of the resulting detectors. The outputs of the two detectors are merged by a globally optimal active contour algorithm to refine the border of the detected nuclei. With a detection rate of 95% (on average 58 incorrectly found objects per field-of-view) based on 51 field-of-view images of Her2 immunohistochemistry stained breast tissue and a complete analysis in 1 s per field-of-view, our nucleus detector shows good performance and could enable a range of applications in automated assessment of (histo)pathological images. PMID:23252774

Vink, J P; Van Leeuwen, M B; Van Deurzen, C H M; De Haan, G

2013-02-01

79

Parameters affecting full energy peak efficiency determination during Monte Carlo simulation.  

PubMed

Aim of this work is to study the effect of various simulation parameters on the calculation of the full energy peak efficiency of HPGe detectors with the Monte Carlo simulation code PENELOPE. PMID:19954990

Karfopoulos, K L; Anagnostakis, M J

2010-01-01

80

Measurement of radionuclide activities induced in target components of an IBA CYCLONE 18/9 by gamma-ray spectrometry with HPGe and LaBr3: Ce detectors.  

PubMed

Cyclotrons are used worldwide to produce radiopharmaceuticals by proton irradiation of a suitable target. The intense secondary neutron beam generated by proton interactions with the target induce high radionuclide activities in the target assembly parts that may result in an exposure to high dose levels of the operators during maintenance. The main goal of this work is to evaluate gamma-emitting radionuclide activities induced in Havar foils and titanium windows of a target assembly and carousel stripper forks of an IBA CYCLONE 18/9 cyclotron. The knowledge of radionuclide inventory for each component is required by many companies to assess risk for operators before waste handling and disposal. Gamma-ray spectrometric analyses were carried out with High Purity Germanium (HPGe) and Lanthanum bromide (LaBr3:Ce) scintillation detectors. HPGe is the most used detector for its high energy resolution although it is more suitable for use in a laboratory. The use of LaBr3:Ce can be considered a viable option, particularly in realizing a portable spectrometric system to perform "on-site" measurements and a fast dose rate evaluation before the disposal of activated parts. Due to a high activity of target assembly components replaced after a typical irradiation cycle (about 5000 ?Ah integrated beam current), gamma-ray spectrometric measurements were performed at a large distance from the detector, even more than 100 cm, or by using a purposely realized Lead-walled collimator. The identification of some key-radionuclides allows to evaluate through simple formulations the dose rate behavior for each component as function of decay time from the last irradiation. The knowledge of the dose rate behavior is a significant piece of information to health physicists for waste handling with safety at work. For an Havar™ foil, the dose rate will be reduced to about 1/1,000 of the starting value after a decay period of approximately 4 y (about 1,500 d), with a relatively safety at product disposal work. For a longer time, only long-lived radionuclides (57)Co, (60)Co, and (54)Mn contribute to dose rate. PMID:24949919

Tomarchio, Elio

2014-08-01

81

Evaluation of the neutron background in an HPGe target for WIMP direct detection when using a reactor neutrino detector as a neutron veto system  

SciTech Connect

A direct WIMP (weakly interacting massive particle) detector with a neutron veto system is designed to better reject neutrons. The experimental configuration is studied in this paper involves 984 Ge modules placed inside a reactor-neutrino detector. The neutrino detector is used as a neutron veto device. The neutron background for the experimental design is estimated using the Geant4 simulation. The results show that the neutron background can decrease to O(0.01) events per year per tonne of high-purity germanium and it can be ignored in comparison with electron recoils.

Ji, Xiangpan; Xu, Ye, E-mail: xuye76@nankai.edu.cn; Lin, Junsong; Feng, Yulong; Li, Haolin [Nankai University, School of Physics (China)

2013-11-15

82

Simulation of background reduction and Compton depression in low-background HPGe spectrometer at a surface laboratory  

E-print Network

High-purity germanium detectors are well suited to analysis the radioactivity of samples. In order to reduce the environmental background, low-activity lead and oxygen free copper are installed outside of the probe to shield gammas, outmost is a plastic scintillator to veto the cosmic rays, and an anti-Compton detector can improve the Peak-to-Compton ratio. Using the GEANT4 tools and taking into account a detailed description of the detector, we optimize the sizes of the detectors to reach the design indexes. A group of experimental data from a HPGe spectrometer in using were used to compare with the simulation. As to new HPGe Detector simulation, considering the different thickness of BGO crystals and anti-coincidence efficiency, the simulation results show that the optimal thickness is 5.5cm, and the Peak-to-Compton ratio of 40K is raised to 1000 when the anti-coincidence efficiency is 0.85. As the background simulation, 15 cm oxygen-free copper plus 10 cm lead can reduce the environmental gamma rays to 0.0024 cps/100 cm3 Ge (50keV~2.8MeV), which is about 10-5 of environmental background.

ShunLi Niu; Xiao Cai; ZhenZhong Wu; YuGuang Xie; BoXiang Yu; ZhiGang Wang; Jian Fang; XiLei Sun; LiJun Sun; YingBiao Liu; Long Gao; Xuan Zhang; Hang Zhao; Li Zhou; JunGuang Lv; Tao Hu

2014-10-16

83

Simulation of background reduction and Compton depression in low-background HPGe spectrometer at a surface laboratory  

E-print Network

High-purity germanium detectors are well suited to analysis the radioactivity of samples. In order to reduce the environmental background, low-activity lead and oxygen free copper are installed outside of the probe to shield gammas, outmost is a plastic scintillator to veto the cosmic rays, and an anti-Compton detector can improve the Peak-to-Compton ratio. Using the GEANT4 tools and taking into account a detailed description of the detector, we optimize the sizes of the detectors to reach the design indexes. A group of experimental data from a HPGe spectrometer in using were used to compare with the simulation. As to new HPGe Detector simulation, considering the different thickness of BGO crystals and anti-coincidence efficiency, the simulation results show that the optimal thickness is 5.5cm, and the Peak-to-Compton ratio of 40K is raised to 1000 when the anti-coincidence efficiency is 0.85. As the background simulation, 15 cm oxygen-free copper plus 10 cm lead can reduce the environmental gamma rays to 0.0...

Niu, ShunLi; Wu, ZhenZhong; Xie, YuGuang; Yu, BoXiang; Wang, ZhiGang; Fang, Jian; Sun, XiLei; Sun, LiJun; Liu, YingBiao; Gao, Long; Zhang, Xuan; Zhao, Hang; Zhou, Li; Lv, JunGuang; Hu, Tao

2014-01-01

84

Quantum Efficient Detectors for Use in Absolute Calibration  

NASA Technical Reports Server (NTRS)

The trap or quantum efficient detector has a quantum efficiency of greater than 0.98 for the region from 450 to 900 nm. The region of flattest response is from 600 to 900 nm. The QED consists of three windowless Hamamatsu silicon detectors. The QED was mounted below AVIRIS to monitor the Spectralon panel for changes in radiance during radiometric calibration. The next step is to permanently mount the detector to AVIRIS and monitor the overall radiance of scenes along with calibration.

Faust, Jessica; Eastwood, Michael; Pavri, Betina; Raney, James

1998-01-01

85

Efficiency of composite boron nitride neutron detectors in comparison with helium-3 detectors  

SciTech Connect

It has been clearly demonstrated that the composite boron nitride (BN) semiconductor polycrystalline bulk detectors with BN grains embedded in a polymer matrix operate as an effective detector of thermal neutrons even if they contain natural boron only. A reasonable signal to noise ratio has been achieved with detector thickness of about 1 mm. A Monte Carlo simulation of neutron reactions in the BN detector was done to estimate the thermal neutron detection efficiency. The result was compared with widely used {sup 3}He based detectors to prove advantages of BN detectors, which are especially promising for neutron imaging and for large area sensors.

Uher, J.; Pospisil, S.; Linhart, V.; Schieber, M. [Institute of Experimental and Applied Physics, Czech Technical University in Prague, Horska 3a/22, 12800 Praha 2, Albertov (Czech Republic); Hebrew University of Jerusalem, Jerusalem 91904 (Israel)

2007-03-19

86

Efficiency study of a big volume well type NaI(Tl) detector by point and voluminous sources and Monte-Carlo simulation.  

PubMed

The activity of environmental samples is usually measured by high resolution HPGe gamma spectrometers. In this work a set-up with a 9in.x9in. NaI well-detector with 3in. thickness and a 3in.×3in. plug detector in a 15-cm-thick lead shielding is considered as an alternative (Hansman, 2014). In spite of its much poorer resolution, it requires shorter measurement times and may possibly give better detection limits. In order to determine the U-238, Th-232, and K-40 content in the samples by this NaI(Tl) detector, the corresponding photopeak efficiencies must be known. These efficiencies can be found for certain source matrix and geometry by Geant4 simulation. We found discrepancy between simulated and experimental efficiencies of 5-50%, which can be mainly due to effects of light collection within the detector volume, an effect which was not taken into account by simulations. The influence of random coincidence summing on detection efficiency for radionuclide activities in the range 130-4000Bq, was negligible. This paper describes also, how the efficiency in the detector depends on the position of the radioactive point source. To avoid large dead time, relatively weak Mn-54, Co-60 and Na-22 point sources of a few kBq were used. Results for single gamma lines and also for coincidence summing gamma lines are presented. PMID:25769009

Hansman, Jan; Mrdja, Dusan; Slivka, Jaroslav; Krmar, Miodrag; Bikit, Istvan

2015-05-01

87

Quantum enhanced estimation of optical detector efficiencies  

E-print Network

Quantum mechanics establishes the ultimate limit to the scaling of the precision on any parameter, by iden- tifying optimal probe states and measurements. While this paradigm is, at least in principle, adequate for the metrology of quantum channels involving the estimation of phase and loss parameters, we show that estimat- ing the loss parameters associated with a quantum channel and a realistic quantum detector are fundamentally different. While Fock states are provably optimal for the former, we identify a crossover in the nature of the optimal probe state for estimating detector imperfections as a function of the loss parameter. We provide explicit results for on-off and homodyne detectors, the most widely used detectors in quantum photonics technologies.

Barbieri, Marco; Bartley, Tim J; Jin, Xian-Min; Kolthammer, W Steven; Walmsley, Ian A

2015-01-01

88

Hit efficiency study of CMS prototype forward pixel detectors  

SciTech Connect

In this paper the author describes the measurement of the hit efficiency of a prototype pixel device for the CMS forward pixel detector. These pixel detectors were FM type sensors with PSI46V1 chip readout. The data were taken with the 120 GeV proton beam at Fermilab during the period of December 2004 to February 2005. The detectors proved to be highly efficient (99.27 {+-} 0.02%). The inefficiency was primarily located near the corners of the individual pixels.

Kim, Dongwook; /Johns Hopkins U.

2006-01-01

89

Detective quantum efficiency of electron area detectors in electron microscopy  

PubMed Central

Recent progress in detector design has created the need for a careful side-by-side comparison of the modulation transfer function (MTF) and resolution-dependent detective quantum efficiency (DQE) of existing electron detectors with those of detectors based on new technology. We present MTF and DQE measurements for four types of detector: Kodak SO-163 film, TVIPS 224 charge coupled device (CCD) detector, the Medipix2 hybrid pixel detector, and an experimental direct electron monolithic active pixel sensor (MAPS) detector. Film and CCD performance was measured at 120 and 300 keV, while results are presented for the Medipix2 at 120 keV and for the MAPS detector at 300 keV. In the case of film, the effects of electron backscattering from both the holder and the plastic support have been investigated. We also show that part of the response of the emulsion in film comes from light generated in the plastic support. Computer simulations of film and the MAPS detector have been carried out and show good agreement with experiment. The agreement enables us to conclude that the DQE of a backthinned direct electron MAPS detector is likely to be equal to, or better than, that of film at 300 keV. PMID:19497671

McMullan, G.; Chen, S.; Henderson, R.; Faruqi, A.R.

2009-01-01

90

Absolute Efficiency Calibration of a Beta-Gamma Detector  

SciTech Connect

Abstract- Identification and quantification of nuclear events such as the Fukushima reactor failure and nuclear explosions rely heavily on the accurate measurement of radioxenon releases. One radioxenon detection method depends on detecting beta-gamma coincident events paired with a stable xenon measurement to determine the concentration of a plume. Like all measurements, the beta-gamma method relies on knowing the detection efficiency for each isotope measured. Several methods are commonly used to characterize the detection efficiency for a beta-gamma detector. The most common method is using a NIST certified sealed source to determine the efficiency. A second method determines the detection efficiencies relative to an already characterized detector. Finally, a potentially more accurate method is to use the expected sample to perform an absolute efficiency calibration; in the case of a beta-gamma detector, this relies on radioxenon gas samples. The complication of the first method is it focuses only on the gamma detectors and does not offer a solution for determining the beta efficiency. The second method listed is not similarly constrained, however it relies on another detector to have a well-known efficiency calibration. The final method using actual radioxenon samples to make an absolute efficiency determination is the most desirable, but until recently it was not possible to produce all four isotopically pure radioxenon. The production, by University of Texas (UT), of isotopically pure radioxenon has allowed the beta-gamma detectors to be calibrated using the absolute efficiency method. The first four radioxenon isotope calibration will be discussed is this paper.

Cooper, Matthew W.; Ely, James H.; Haas, Derek A.; Hayes, James C.; McIntyre, Justin I.; Lidey, Lance S.; Schrom, Brian T.

2013-04-10

91

Random Variation of Detector Efficiency: A Countermeasure against Detector Blinding Attacks for Quantum Key Distribution  

E-print Network

In the recent decade, it has been discovered that QKD systems are extremely vulnerable to side-channel attacks. In particular, by exploiting the internal working knowledge of practical detectors, it is possible to bring them to an operating region whereby only certain target detectors are sensitive to detections. Crucially, the adversary can use this loophole to learn everything about the secret key without introducing any error to the quantum channel. In this work, as a step towards overcoming detector blinding attacks, we focus on an experimentally convenient countermeasure, where the efficiency of the detectors is randomly varied.

Charles Ci Wen Lim; Nino Walenta; Matthieu Legre; Nicolas Gisin; Hugo Zbinden

2015-01-30

92

High efficiency proportional neutron detector with solid liner internal structures  

DOEpatents

A tube-style neutron detector, a panel-style neutron detector incorporating a plurality of tube-style neutron detectors, and a panel-style neutron detector including a plurality of anode wires are provided. A plurality of channels is provided in a neutron detector such that each channel has an inner surface of a coating layer including a neutron-absorbing material. A wire anode is provided at end of each channel so that electrons generated by a charged daughter particle generated by a neutron are collected to detect a neutron-matter interaction. Moderator units can be incorporated into a neutron detector to provide improved detection efficiencies and/or to determine neutron energy spectrum. Gas-based proportional response from the neutron detectors can be employed for special nuclear material (SNM) detection. This neutron detector can provide similar performance to .sup.3He-based detectors without requiring .sup.3He and without containing toxic, flammable, or high-pressure materials.

Kisner, Roger Allen; Holcomb, David Eugene; Brown, Gilbert M.

2014-08-05

93

Existing NaI detectors; an efficient alternative to He-3 detectors  

NASA Astrophysics Data System (ADS)

Neutron detectors are important in various fields of research, safeguards, security, medicine, and industry. The most common methods for detecting neutrons involve utilization of the 10B(n,?), 6Li(n,?), or 3He(n,p) reactions; with the He-3 filled proportional counters being the most widely used because of their high detection efficiency and good gamma ray discrimination. However these counters have severe drawbacks in terms of detector size and scarcity of He-3. The aim of this work is to investigate an alternative neutron detection method by using a boron lining with existing NaI detectors and compare the results with those obtained from a He-3 detector. The results show a good sensitivity of the boron-lined NaI detector to neutrons at different source locations and a considerable improvement in efficiency compared to He-3 detectors. On top of this the NaI detectors are used to detect the gamma rays from the surrounding source and interacting media.

Metwally, Walid A.

2014-11-01

94

Resonant infrared detector with substantially unit quantum efficiency  

NASA Technical Reports Server (NTRS)

A resonant infrared detector includes an infrared-active layer which has first and second parallel faces and which absorbs radiation of a given wavelength. The detector also includes a first tuned reflective layer, disposed opposite the first face of the infrared-active layer, which reflects a specific portion of the radiation incident thereon and allows a specific portion of the incident radiation at the given wavelength to reach the infrared-active layer. A second reflective layer, disposed opposite the second face of the infrared-active layer, reflects back into the infrared-active layer substantially all of the radiation at the given wavelength which passes through the infrared-active layer. The reflective layers have the effect of increasing the quantum efficiency of the infrared detector relative to the quantum efficiency of the infrared-active layer alone.

Farhoomand, Jam (inventor); Mcmurray, Robert E., Jr. (inventor)

1994-01-01

95

Efficient filter for detecting gravitational wave bursts in interferometric detectors  

Microsoft Academic Search

Typical sources of gravitational wave bursts are supernovae, for which no accurate models exist. This calls for search methods with high efficiency and robustness to be used in the data analysis of foreseen interferometric detectors. A set of such filters is designed to detect gravitational wave burst signals. We first present filters based on the linear fit of whitened data

Thierry Pradier; Nicolas Arnaud; Marie-Anne Bizouard; Fabien Cavalier; Michel Davier; Patrice Hello

2001-01-01

96

Determination of the Quantum Efficiency of a Light Detector  

ERIC Educational Resources Information Center

The "quantum efficiency" (QE) is an important property of a light detector. This quantity can be determined in the undergraduate physics laboratory. The experimentally determined QE of a silicon photodiode appeared to be in reasonable agreement with expected values. The experiment confirms the quantum properties of light and seems to be a useful…

Kraftmakher, Yaakov

2008-01-01

97

Designing Efficient Algorithms for the Eventually Perfect Failure Detector Class  

Microsoft Academic Search

This paper focuses on the design of unreliable failure detectors of the Eventually Perfect class (3P) in crash-prone partially synchronous systems. We adopt a monitoring mechanism based on heartbeats over a logi- cal ring arrangement of processes as the common design feature. This provides good communication efficiency, a performance parameter which refers to the number of links that carry messages

Mikel Larrea; Alberto Lafuente; Iratxe Soraluze Arriola; Roberto Cortiñas; Joachim Wieland

2007-01-01

98

Neutron efficiency of LaBr3:Ce detector  

NASA Astrophysics Data System (ADS)

We report on a measurement of the neutron detection efficiency in a LaBr3 detector in the energy range 0.1-2 MeV. The experiment was carried out using a 4 MV Van-de-Graaff accelerator which provided monoenergetic neutrons from T(p,n)3He and 7Li(p,n)7Be reactions. The five most intense ?-rays from the LaBr3(n, n ? ?) reaction have been studied to deduce the neutron sensitivity of the detector. GEANT4 simulations with different nuclear data libraries have been done and a comparison with the data is provided.

Ebran, A.; Roig, O.; Méot, V.; Delaune, O.

2014-12-01

99

High-efficiency neutron detectors and methods of making same  

DOEpatents

Neutron detectors, advanced detector process techniques and advanced compound film designs have greatly increased neutron-detection efficiency. One embodiment of the detectors utilizes a semiconductor wafer with a matrix of spaced cavities filled with one or more types of neutron reactive material such as 10B or 6LiF. The cavities are etched into both the front and back surfaces of the device such that the cavities from one side surround the cavities from the other side. The cavities may be etched via holes or etched slots or trenches. In another embodiment, the cavities are different-sized and the smaller cavities extend into the wafer from the lower surfaces of the larger cavities. In a third embodiment, multiple layers of different neutron-responsive material are formed on one or more sides of the wafer. The new devices operate at room temperature, are compact, rugged, and reliable in design.

McGregor, Douglas S.; Klann, Raymond

2007-01-16

100

Investigation of the quantum efficiency of optical heterodyne detectors  

NASA Technical Reports Server (NTRS)

The frequency response and quantum efficiency of optical photodetectors for heterodyne receivers is investigated. The measurements utilized two spectral lines from the output of two lasers as input to the photodetectors. These lines are easily measurable in power and frequency and hence serve as known inputs. By measuring the output current of the photodetector the quantum efficiency is determined as a function of frequency separation between the two input signals. An investigation of the theoretical basis and accuracy of this type of measurement relative to similar measurements utilizing risetime is undertaken. A theoretical study of the heterodyne process in photodetectors based on semiconductor physics is included so that higher bandwidth detectors may be designed. All measurements are made on commercially available detectors and manufacturers' specifications for normal photodetector operation are compared to the measured heterodyne characteristics.

Batchman, T. E.

1984-01-01

101

The SPICE Detector at ISAC  

NASA Astrophysics Data System (ADS)

A new ancillary detector system for the TIGRESS HPGe array called SPectrometer for Internal Conversion Electrons (SPICE) is currently under development. SPICE consists of a segmented electron detector, photon shield and a permanent magnetic lens. SPICE will enable in-beam electron spectroscopy and, in coupling to the TIGRESS HPGe array, coincident gamma-electron spectroscopy with stable and radioactive beams.

Garnsworthy, A. B.; Moukaddam, M.; Bolton, C.; Ketelhut, S.; Evitts, L. J.; Andreoiu, C.; Constable, M.; Hackman, G.; Henderson, R.; Svensson, C. E.

2013-12-01

102

A new summing-correction method for gamma-efficiency calibration with multi-gamma-ray radionuclides  

NASA Astrophysics Data System (ADS)

Coincidence-summing effects play an important role in HPGe spectrometry at low source-to-detector distances (usual arrangements when environmental samples have to be measured). Although these corrections are not important for environmental samples (less than 5%), they can be significant in the efficiency calibration with multi-gamma-ray radioisotopes as they have to be measured in the same geometry. In this paper we propose a new method for determining summing corrections which does not require other monoenergetic radioisotopes. Thus, a HPGe-detector-efficiency calibration can be performed with radionuclides emitting gamma rays in cascade, such as 152Eu or 226Ra. The method has been successfully validated.

Ramos-Lerate, I.; Barrera, M.; Ligero, R. A.; Casas-Ruiz, M.

1997-02-01

103

Highly Efficient Quantum Key Distribution Immune to All Detector Attacks  

E-print Network

Vulnerabilities and imperfections of single-photon detectors have been shown to compromise security for quantum key distribution (QKD). The measurement-device-independent QKD (MDI-QKD) appears to be the most appealing solution to solve the issues. However, in practice one faces severe obstacles of having significantly lower key generation rate, difficult two photon interferences, and remote synchronization etc. In this letter, we propose a highly efficient and simple quantum key distribution scheme to remove all of these drawbacks. Our proposal can be implemented with only small modifications over the standard decoy BB84 system. Remarkably it enjoys both the advantages of high key generation rate (being almost two orders of magnitude higher than that based on conventional MDI-QKD) comparable to the normal decoy system, and security against any detector side channel attacks. Most favorably one can achieve complete Bell state measurements with resort to single photon interference, which reduces significantly experimental costs. Our approach enables utilization of high speed and efficient secure communication, particularly in real-life scenario of both metropolitan and intercity QKD network, with an attack free fashion from arbitrary detector side channels.

Wen-Fei Cao; Yi-Zheng Zhen; Yu-Lin Zheng; Zeng-Bing Chen; Nai-Le Liu; Kai Chen; Jian-Wei Pan

2014-10-10

104

The active area shadow-shielding effect on detection efficiency of collimated broad energy germanium detectors  

NASA Astrophysics Data System (ADS)

The ISOCS calibration, when utilized for a BEGe detector with a small angled collimator, produces inaccuracies of about 19% for gamma rays with energies greater than 0.4 MeV. Such a discrepancy is caused by the collimator algorithms currently utilized in the ISOCS software which, originally developed for HPGe detectors, are less suited for BEGe detectors. ISOCS's errors are due to the different crystal configurations of broad energy detectors compared to coaxial detectors, i.e. to a different importance of the active area portion obscured by the collimator. This work proposes some solutions for the problem, either using the ISOCS software or implementing a stochastic calibration procedure. In particular, the present work considers a virtual collimator that, maintaining its angular aperture, is capable of continuously enlarging its bottom collimator's aperture cone radius, to expose growing active area portions. In such a way two goals may be achieved: the mathematical characterization of ISOCS' errors and the minimization of observed errors by means of the stochastic calibration procedure.

Altavilla, Massimo; Remetti, Romolo

2014-03-01

105

Optimization of efficiency and response time of diffusion-based nuclear radiation detectors  

Microsoft Academic Search

The charge collection process in a diffusion-based silicon nuclear radiation detector was investigated by illuminating the detector at the backside with optical radiation. The results are compared to calculations and show good agreement. The collection mechanism is characterized, and the detector response to nuclear radiation and its optimum with respect to efficiency and response time are calculated. Efficiency and response

S. E. Wouters; T. Otaredian; E. M. Schooneveld

1991-01-01

106

Efficient readout for carbon nanotube (CNT)-based IR detectors  

NASA Astrophysics Data System (ADS)

By forming a Schottky barrier with the contact metal, a semiconducting CNT based Schottky photodiode is formed at the CNT-metal contact. The photogenerated electron-hole pairs within the depletion region of the Schottky barrier are separated by an external electrical field or the built-in field, producing a photocurrent. How to efficiently read this photocurrent signal out is an essential problem for the photodetectors. Since a semiconducting CNT normally forms a Schottky barrier at each CNT-electrode contact, two Schottky photodiodes are reversely connected and their photocurrents will cancel each other, which makes it difficult to measure the overall photocurrent. With different materials as the contact electrodes, the asymmetric structure enlarged the difference between the two CNT-metal contacts. Hence the measurable photocurrent is also enlarged. Furthermore, since the CNT Schottky barrier is determined by the metal work function and the Fermi level of the CNT, the Schottky barrier is able to be adjusted by controlling the Fermi level of the CNT with a gate electrode. In this way, the photocurrent can be optimized to a maximum value by varying the gate voltage. CNT based infrared detectors with different structures were fabricated and tested. Experimental results showed that the asymmetric structure and the gate controlled CNT based photodiode could significantly improve the performance of CNT based infrared detectors.

Zhang, Jiangbo; Xi, Ning; Chen, Hongzhi; Lai, King W. C.

2007-10-01

107

Validation of efficiency transfer for Marinelli geometries.  

PubMed

In the framework of environmental measurements by gamma-ray spectrometry, some laboratories need to characterize samples in geometries for which a calibration is not directly available. A possibility is to use an efficiency transfer code, e.g., ETNA. However, validation for large volume sources, such as Marinelli geometries, is needed. With this aim in mind, ETNA is compared, initially to a Monte Carlo simulation (PENELOPE) and subsequently to experimental data obtained with a high-purity germanium detector (HPGe). PMID:23623315

Ferreux, Laurent; Pierre, Sylvie; Thanh, Tran Thien; Lépy, Marie-Christine

2013-11-01

108

Study of the charge collection efficiency of CdZnTe radiation detectors  

Microsoft Academic Search

The charge collection efficiency of CdZnTe radiation detectors with two different configurations: aSchottky diode detector and aresistive detector are compared. The average charge collection efficiencies for three different directions of irradiation (negative electrode,\\u000a positive electrode and perpendicular to the electric field) are calculated. The mobility-lifetime product of the CdZnTe substrates\\u000a is evaluated from the dependence of the measured spectra upon

Y. Nemirovsky; A. Ruzin; G. Asa; J. Gorelik

1996-01-01

109

Efficiency of composite boron nitride neutron detectors in comparison with helium-3 detectors  

Microsoft Academic Search

It has been clearly demonstrated that the composite boron nitride (BN) semiconductor polycrystalline bulk detectors with BN grains embedded in a polymer matrix operate as an effective detector of thermal neutrons even if they contain natural boron only. A reasonable signal to noise ratio has been achieved with detector thickness of about 1 mm. A Monte Carlo simulation of neutron

J. Uher; S. Pospisil; V. Linhart; M. Schieber

2007-01-01

110

DESIGN OF A THERMOSIPHON FOR COOLING LOW-BACKGROUND HPGE ARRAYS  

SciTech Connect

ABSTRACT A two-phase nitrogen thermosiphon was developed for the new generation of low-background high-purity germanium (HPGe) arrays. The cooling system for these arrays has to be able to handle the heat load (>20 W) presented by a large detector mass while meeting stringent requirements necessary for low-background systems. The HPGe detector modules should operate as close to liquid nitrogen temperature (<80K) as possible to provide adequate operating conditions for a full range of HPGe impurity concentrations. In addition, exceptional temperature stability (<1 K) is needed to reduce electronic gain shifts due to changes in the front-end electronics operating temperature. In order to meet the background requirements of state-of-the-art systems these arrays are enclosed in passive lead and copper shielding up to 1 m thick. In this paper we present a cooling system for low-background experiments that complies with these stringent geometrical restrictions. Active cooling was integrated via a horizontal thermosiphon that can be fabricated using ultra-pure electroformed copper. It was charged with nitrogen to 434 kPa (63 PSIA) at 292 K, which provided a fill ratio of 10%. The results showed that the thermosiphon can effectively remove in excess of 25 W of heat load.

Aguayo Navarrete, Estanislao; Fast, James E.; Reid, Douglas J.

2012-11-26

111

Investigations of 2? decay measured by low background HPGe spectrometer OBELIX  

SciTech Connect

A low background high sensitive HPGe spectrometer OBELIX was installed at the Modane Underground Laboratory (LSM, France, 4800 m w.e.). The detector was designed to measure a contamination of enriched isotopes and radio-impurities in construction materials, to investigate rare nuclear processes such as resonance neutrinoless double electron capture and two-neutrino double beta decay to excited states of daughter nuclei. Spectrometer sensitivity, contamination of NEMO-3 sources and results of 2?2?{sup ?} decay of {sup 100}Mo to the 0{sup +} (1130 keV) and 2{sup +} (540 keV) excited states as well as future plans for OBELIX detector are given.

Rukhadze, Ekaterina [Institute of Experimental and Applied Physics, CTU in Prague, Horska 3a/22, 128 00 Prague 2 (Czech Republic); Collaboration: OBELIX Collaboration; SuperNEMO Collaboration

2013-12-30

112

Development of A Self Biased High Efficiency Solid-State Neutron Detector for MPACT Applications  

SciTech Connect

Neutron detection is an important aspect of materials protection, accounting, and control for transmutation (MPACT). Currently He-3 filled thermal neutron detectors are utilized in many applications; these detectors require high-voltage bias for operation, which complicates the system when multiple detectors are used. In addition, due to recent increase in homeland security activity and the nuclear renaissance, there is a shortage of He-3, and these detectors become more expensive. Instead, cheap solid-state detectors that can be mass produced like any other computer chips will be developed. The new detector does not require a bias for operation, has low gamma sensitivity, and a fast response. The detection system is based on a honeycomb-like silicon device, which is filled with B-10 as the neutron converter; while a silicon p-n diode (i.e., solar cell type device) formed on the thin silicon wall of the honeycomb structure detects the energetic charged particles emitted from the B-10 conversion layer. Such a detector has ~40% calculated thermal neutron detection efficiency with an overall detector thickness of about 200 ?m. Stacking of these devices allows over 90% thermal neutron detection efficiency. The goal of the proposed research is to develop a high-efficiency, low-noise, self-powered solid-state neutron detector system based on the promising results of the existing research program. A prototype of this solid-state neutron detector system with sufficient detector size (up to 8-inch diam., but still portable and inexpensive) and integrated with interface electronics (e.g., preamplifier) will be designed, fabricated, and tested as a coincidence counter for MPACT applications. All fabrications proposed are based on silicon-compatible processing; thus, an extremely cheap detector system could be massively produced like any other silicon chips. Such detectors will revolutionize current neutron detection systems by providing a solid-state alternative to traditional gas-based neutron detectors.

Danon, Yaron; Bhat, Ishwara; Jian-Qiang Lu, James

2013-09-03

113

Efficient superconducting-nanowire single-photon detectors and their applications in quantum optics  

E-print Network

Superconducting-nanowire single-photon detectors (SNSPDs) are an emerging technology for infrared photon counting and detection. Their advantages include good device efficiency, fast operating speed, low dark-count rate, ...

Hu, Xiaolong, Ph. D. Massachusetts Institute of Technology

2011-01-01

114

Novel energy-efficient scalable soft-output SSFE MIMO detector architectures  

Microsoft Academic Search

Energy-efficient scalable soft-output signal detectors are of significant interest in emerging multiple-input multiple-output (MIMO) wireless communication systems. However, traditional high-performance MIMO detectors consume a rather high amount of power, are typically constraint to one modulation scheme and are not scalable with the number of antennas. Hence, they are not well-suited for future energy-efficient software defined radio (SDR) platforms. This paper

Robert Fasthuber; Min Li; David Novo; Praveen Raghavan; Liesbet Van der Perre; Francky Catthoor

2009-01-01

115

Absolute efficiency estimation of photon-number-resolving detectors using twin beams  

E-print Network

A nonclassical light source is used to demonstrate experimentally the absolute efficiency calibration of a photon-number-resolving detector. The photon-pair detector calibration method developed by Klyshko for single-photon detectors is generalized to take advantage of the higher dynamic range and additional information provided by photon-number-resolving detectors. This enables the use of brighter twin-beam sources including amplified pulse pumped sources, which increases the relevant signal and provides measurement redundancy, making the calibration more robust.

Worsley, A P; Lundeen, J S; Mosley, P J; Smith, B J; Puentes, G; Thomas-Peter, N; Walmsley, I A; 10.1364/OE.17.004397

2009-01-01

116

Absolute efficiency estimation of photon-number-resolving detectors using twin beams.  

PubMed

A nonclassical light source is used to demonstrate experimentally the absolute efficiency calibration of a photon-number-resolving detector. The photon-pair detector calibration method developed by Klyshko for single-photon detectors is generalized to take advantage of the higher dynamic range and additional information provided by photon-number-resolving detectors. This enables the use of brighter twin-beam sources including amplified pulse pumped sources, which increases the relevant signal and provides measurement redundancy, making the calibration more robust. PMID:19293867

Worsley, A P; Coldenstrodt-Ronge, H B; Lundeen, J S; Mosley, P J; Smith, B J; Puentes, G; Thomas-Peter, N; Walmsley, I A

2009-03-16

117

Absolute efficiency estimation of photon-number-resolving detectors using twin beams  

E-print Network

A nonclassical light source is used to demonstrate experimentally the absolute efficiency calibration of a photon-number-resolving detector. The photon-pair detector calibration method developed by Klyshko for single-photon detectors is generalized to take advantage of the higher dynamic range and additional information provided by photon-number-resolving detectors. This enables the use of brighter twin-beam sources including amplified pulse pumped sources, which increases the relevant signal and provides measurement redundancy, making the calibration more robust.

A. P. Worsley; H. B. Coldenstrodt-Ronge; J. S. Lundeen; P. J. Mosley; B. J. Smith; G. Puentes; N. Thomas-Peter; I. A. Walmsley

2009-06-11

118

Absolute and angular efficiencies of a microchannel-plate position-sensitive detector  

NASA Technical Reports Server (NTRS)

This paper presents a characterization of a commercially available position-sensitive detector of energetic ions and neutrals. The detector consists of two microchannel plates followed by a resistive position-encoding anode. The work includes measurement of absolute efficiencies of H(+), He(+), and O(+) ions in the energy range between 250 and 5000 eV, measurement of relative detection efficiencies as a function of particle impact angle, and a simple method for accurate measurement of the time at which a particle strikes the detector.

Gao, R. S.; Gibner, P. S.; Newman, J. H.; Smith, K. A.; Stebbings, R. F.

1984-01-01

119

High-precision efficiency calibration of a high-purity co-axial germanium detector  

E-print Network

A high-purity co-axial germanium detector has been calibrated in efficiency to a precision of about 0.15% over a wide energy range. High-precision scans of the detector crystal and gamma-ray source measurements have been compared to Monte-Carlo simulations to adjust the dimensions of a detector model. For this purpose, standard calibration sources and short-lived on-line sources have been used. The resulting efficiency calibration reaches the precision needed e.g. for branching ratio measurements of super-allowed beta decays for tests of the weak-interaction standard model.

B. Blank; J. Souin; P. Ascher; L. Audirac; G. Canchel; M. Gerbaux; S. Grevy; J. Giovinazzo; H. Guerin; T. Kurtukian Nieto; I. Matea; H. Bouzomita; P. Delahaye; G. F. Grinyer; J. C. Thomas

2014-04-04

120

Note: Fast neutron efficiency in CR-39 nuclear track detectors  

NASA Astrophysics Data System (ADS)

CR-39 samples are commonly employed for fast neutron detection in fusion reactors and in inertial confinement fusion experiments. The literature reported efficiencies are strongly depending on experimental conditions and, in some cases, highly dispersed. The present note analyses the dependence of efficiency as a function of various parameters and experimental conditions in both the radiator-assisted and the stand-alone CR-39 configurations. Comparisons of literature experimental data with Monte Carlo calculations and optimized efficiency values are shown and discussed.

Cavallaro, S.

2015-03-01

121

Efficiency calibration of a large-area neutron detector by using Am\\/Be neutron source  

Microsoft Academic Search

Neutron detection efficiency for a long wedge-shaped plastic scintillation detector was measured by using the Am\\/Be neutron source. The overall efficiency attains 23% at around 2 MeV and decreases to 15% at about 5 MeV. The experimental results are in agreement with the Monte Carlo simulation calculations.

Q. Y. Hu; Y. L. Ye; Z. H. Li; X. Q. Li; D. X. Jiang; T. Zheng; Q. J. Wang; H. Hua; C. E. Wu; Z. Q. Chen; J. Ying; D. Y. Pang; G. L. Zhang; J. Wang

2005-01-01

122

Quantum efficiency test set up performances for NIR detector characterization at ESTEC  

NASA Astrophysics Data System (ADS)

The Payload Technology Validation Section (Future mission preparation Office) at ESTEC is in charge of specific mission oriented validation activities, for science and robotic exploration missions, aiming at reducing development risks in the implementation phase. These activities take place during the early mission phases or during the implementation itself. In this framework, a test set up to characterize the quantum efficiency of near infrared detectors has been developed. The first detector to be tested will an HAWAII-2RG detector with a 2.5?m cut off, it will be used as commissioning device in preparation to the tests of prototypes European detectors developed under ESA funding. The capability to compare on the same setup detectors from different manufacturers will be a unique asset for the future mission preparation office. This publication presents the performances of the quantum efficiency test bench to prepare measurements on the HAWAII-2RG detector. A SOFRADIR Saturn detector has been used as a preliminary test vehicle for the bench. A test set up with a lamp, chopper, monochromator, pinhole and off axis mirrors allows to create a spot of 1mm diameter between 700nm and 2.5?m.The shape of the beam has been measured to match the rms voltage read by the Merlin Lock -in amplifier and the amplitude of the incoming signal. The reference detectors have been inter-calibrated with an uncertainty up to 3 %. For the measurement with HAWAII-2RG detector, the existing cryostat [1] has been modified to adapt cold black baffling, a cold filter wheel and a sapphire window. An statistic uncertainty of +/-2.6% on the quantum efficiency on the detector under test measurement is expected.

Crouzet, P.-E.; Duvet, L.; De Wit, F.; Beaufort, T.; Blommaert, S.; Butler, B.; Van Duinkerken, G.; ter Haar, J.; Heijnen, J.; van der Luijt, K.; Smit, H.; Viale, T.

2014-07-01

123

Note: Fast neutron efficiency in CR-39 nuclear track detectors.  

PubMed

CR-39 samples are commonly employed for fast neutron detection in fusion reactors and in inertial confinement fusion experiments. The literature reported efficiencies are strongly depending on experimental conditions and, in some cases, highly dispersed. The present note analyses the dependence of efficiency as a function of various parameters and experimental conditions in both the radiator-assisted and the stand-alone CR-39 configurations. Comparisons of literature experimental data with Monte Carlo calculations and optimized efficiency values are shown and discussed. PMID:25832287

Cavallaro, S

2015-03-01

124

“Neutron Shell”: a high efficiency array of neutron detectors for ?-ray spectroscopic studies with Gammasphere  

Microsoft Academic Search

A shell of neutron detectors was designed, constructed, and employed in ?-ray spectroscopy with Gammasphere. It consists of up to 35 tapered regular hexagons that replace the same number of forward Ge-detector modules in Gammasphere. The shell was designed for high detection efficiency and very good neutron–? discrimination. The simultaneous use of time-of-flight, and two methods of pulse shape discrimination

D. G. Sarantites; W. Reviol; C. J. Chiara; R. J. Charity; L. G. Sobotka; M. Devlin; M. Furlotti; O. L. Pechenaya; J. Elson; P. Hausladen; S. Fischer; D. Balamuth; R. M. Clark

2004-01-01

125

An energy efficient weakly programmable MIMO detector architecture  

NASA Astrophysics Data System (ADS)

Energy efficient processing is mandatory in todays' mobile devices. For the upcoming multiple-antenna systems, algorithmic flexibility enables the dynamic reaction to changing channel conditions. We show that most of the tree search based MIMO detection algorithms are based on the same algorithmic kernels and present a weakly-programmable architecture based on these observations. In this way, the detection algorithm can be chosen and parameterized during runtime according to the current channel conditions and QoS requirements leading to a highly energy efficient implementation. The architecture has been implemented and synthesized on a 65 nm technology, resulting in an area of 0.26 mm2 and a power consumption of only 15 mW.

Gimmler-Dumont, C.; Wehn, N.

2013-07-01

126

Investigation of the Charge Collection Efficiency of CdMnTe Radiation Detectors  

SciTech Connect

This paper presents the growth, fabrication and characterization of indium-doped cadmium manganese telluride (CdMnTe) crystals grown by the vertical Bridgman technique. The 10 x 10 x 1.9 mm{sup 3} samples have been fabricated, and the charge collection properties of the CdMnTe detectors have been measured. Alpha-particle spectroscopy measurements have yielded an average charge collection efficiency approaching 100%. Ion beam induced charge (IBIC) measurements have been performed by raster scanning focused 5.5 MeV {sup 4}He beams onto the detectors. Spatially resolved charge collection efficiency maps have been produced for a range of detector bias voltages. Inhomogeneities in the charge transport of the CdMnTe crystals have been associated with chains of Te inclusions within the detector bulk, and the reduction in charge collection efficiency in their locality has been quantified. It has been shown that the role of Te inclusions in degrading charge collection is reduced with increasing values of bias voltage. IBIC measurements for a range of low biases have highlighted the evolution of the charge collection uniformity across the detectors.

Bolotnikov A.; Rafiei, R.; Boardman, D.; Sarbutt, A.; Prokopovich, A.; Kim, K.; Reinhard, M.I.; James, R.B.

2012-06-01

127

Impact of geometry on light collection efficiency of scintillation detectors for cryogenic rare event searches  

E-print Network

Simulations of photon propagation in scintillation detectors were performed with the aim to find the optimal scintillator geometry, surface treatment, and shape of external reflector in order to achieve maximum light collection efficiency for detector configurations that avoid direct optical coupling, a situation that is commonly found in cryogenic scintillating bolometers in experimental searches for double beta decay and dark matter. To evaluate the light collection efficiency of various geometrical configurations we used the ZEMAX ray-tracing software. It was found that scintillators in the shape of a triangular prism with an external mirror shaped as truncated cone gives the highest light collection efficiency. The results of the simulations were confirmed by carrying out measurements of the light collection efficiencies of CaWO4 crystal scintillators. A comparison of simulated and measured values of light output shows good agreement

F. A. Danevich; V. V. Kobychev; R. V. Kobychev; H. Kraus; V. B. Mikhailik; V. M. Mokina; I. M. Solsky

2014-04-30

128

Influence of electron traps on charge-collection efficiency in GaAs radiation detectors  

Microsoft Academic Search

This paper deals with the interpretation of the charge-collection efficiency for minimum ionizing particles in terms of electron traps in semi-insulating liquid encapsulated Czochralski gallium arsenide detectors fabricated with thicknesses of 80 mum, 200 mum, and 300 mum. The results, obtained within the context of the RD-8 project, show that low values of charge-collection efficiency cannot be ascribed primarily to

F. Nava; C M Canali; A. Castaldini; A. Cavallini; S D D'Auria; C. del Papa; C. Frigeri; L. Zanotti; A. Cetronio; C. Lanzieri; Antonino Zichichi

1994-01-01

129

Efficiency estimation for detecting U. cap alpha. particles in solid-state nuclear track detectors  

SciTech Connect

The detection efficiencies of solid-state nuclear track detectors, made with cellulose nitrate materials (LR-115 II) or alkyl diglycol carbonate (CR-39) were investigated. Detection efficiency for a surface ..cap alpha.. source was experimentally obtained by changing the dimensions between the detector and the source, while ..cap alpha..-particle incident efficiency was calculated. The ratio of the detection efficiency to the incident efficiency was then determined. It was confirmed that the ratio for LR-115 II was dependent on energy, but for CR-39 the ratio showed almost no dependency. Considering the relationship between solid absorber thickness and detection efficiency of the surface ..cap alpha.. source, detection efficiencies of U in various metals were estimated. The efficiency for U contained in Al and Fe was proposed as 16% for LR-115 II and 22% for CR-39. Using these efficiencies, amounts of U in some Al and Fe ingots were determined. These agreed with concentrations obtained by neutron-activation analysis with deviations of less than 15%.

Uda, T.; Iba, H.

1985-09-01

130

Accurate and Efficient Filtering for the Intel Thread Checker Race Detector  

E-print Network

Accurate and Efficient Filtering for the Intel Thread Checker Race Detector Paul Sack Department@cs.uiuc.edu ABSTRACT Debugging data races in parallel applications is a difficult task. Error-causing data races may or not a debugger is used, and other effects. Further, many race conditions cause incorrect pro- gram behavior only

Torrellas, Josep

131

Fabrication process development for high-purity germanium radiation detectors with amorphous semiconductor contacts  

NASA Astrophysics Data System (ADS)

High-purity germanium (HPGe) radiation detectors are well established as a valuable tool in nuclear science, astrophysics, and nuclear security applications. HPGe detectors excel in gamma-ray spectroscopy, offering excellent energy resolution with large detector sizes for high radiation detection efficiency. Although a robust fabrication process has been developed, improvement is needed, especially in developing electrical contact and surface passivation technology for position-sensitive detectors. A systematic study is needed to understand how the detector fabrication process impacts detector performance and reliability. In order to provide position sensitivity, the electrical contacts are segmented to form multiple electrodes. This segmentation creates new challenges in the fabrication process and warrants consideration of additional detector effects related to the segmentation. A key area of development is the creation of the electrical contacts in a way that enables reliable operation, provides low electronic noise, and allows fine segmentation of electrodes, giving position sensitivity for radiation interactions in the detector. Amorphous semiconductor contacts have great potential to facilitate new HPGe detector designs by providing a thin, high-resistivity surface coating that is the basis for electrical contacts that block both electrons and holes and can easily be finely segmented. Additionally, amorphous semiconductor coatings form a suitable passivation layer to protect the HPGe crystal surface from contamination. This versatility allows a simple fabrication process for fully passivated, finely segmented detectors. However, the fabrication process for detectors with amorphous semiconductors is not as highly developed as for conventional technologies. The amorphous semiconductor layer properties can vary widely based on how they are created and these can translate into varying performance of HPGe detectors with these contacts. Some key challenges include minimizing charge injection leakage current, increasing the long-term stability of the contacts, and achieving good charge collection properties in segmented detectors. A systematic study of contact characteristics is presented where amorphous germanium (a-Ge) and amorphous silicon (a-Si) contacts are sputtered with varying sputter gas hydrogen content, sputter gas pressure, and amorphous film thickness. A set of about 45 detectors fabricated from 11 different crystal samples were analyzed for electron barrier height and effective Richardson constant. Most of these detectors were subjected to as many as 10 temperature cycles over a period of up to several months in order to assess their long-term stability. Additionally, 6 double-sided strip detectors were fabricated with a-Ge and a-Si contacts in order to study their inter-electrode charge collection properties. An attempt is made to relate fabrication process parameters such as hydrogen content, sputter pressure, and film thickness to changes observed in detector performance and assess the level of reproducibility using the current methods. Several important results and conclusions were found that enable more reliable and highly performing detectors with amorphous semiconductor contacts. Utilizing the new information should enable consistent production of finely segmented detectors with excellent energy resolution that can be operated reliably for a long period of time. The passivation process could impact planar detectors as well as other designs, such as the p-type point contact detector. It is demonstrated that the long-term stability of amorphous semiconductor contacts is primarily dependent on the time the detector is at room temperature rather than the number of temperature cycles. For a-Ge contacts, higher sputter pressure yields a more stable process that changes little with time, giving a reliable hole-blocking contact. The a-Si contacts form a good electron-blocking contact with decreasing leakage current over time. Both materials, when 7% hydrogen is included in the argon sputter gas, show acceptab

Looker, Quinn

132

Detectors  

DOEpatents

The apparatus and method provide techniques through which both alpha and beta emission determinations can be made simultaneously using a simple detector structure. The technique uses a beta detector covered in an electrically conducting material, the electrically conducting material discharging ions generated by alpha emissions, and as a consequence providing a measure of those alpha emissions. The technique also offers improved mountings for alpha detectors and other forms of detectors against vibration and the consequential effects vibration has on measurement accuracy.

Orr, Christopher Henry (Calderbridge, GB); Luff, Craig Janson (Calderbridge, GB); Dockray, Thomas (Calderbridge, GB); Macarthur, Duncan Whittemore (Los Alamos, NM); Bounds, John Alan (Los Alamos, NM); Allander, Krag (Los Alamos, NM)

2002-01-01

133

Efficient one-pair experimental system for spatial resolution demonstration of prototype PET detectors.  

PubMed

In the development of depth-of-interaction (DOI)-positron emission tomography (PET) detectors, one of the important steps toward their practical use is an evaluation of their imaging performance, such as the spatial resolution as measured by use of a point source and a one-pair experimental system which simulates actual PET geometries. The DOI-PET detectors have a broad field of view providing good imaging performance compared with conventional detectors. Therefore, evaluation including the region from the center to the periphery close to the detector ring is required in an effort to show their advanced performance regarding uniform spatial resolution. In this study, we aimed to develop and evaluate an efficient one-pair experimental system for demonstration of the DOI-PET detector performance. For this purpose, we propose a one-pair experimental system that can simulate an arbitrary ring diameter and acquire projection data efficiently by skipping unnecessary combinations according to the position of the point source. As a result, the proposed system and our measuring scheme could significantly reduce the total measurement time, especially for a large ring size such as that used in brain PET scanners and whole-body PET scanners. We used the system to evaluate the X'tal cube PET detector with a 2-mm cubic crystal array arranged in simulated PET geometries with ring diameters of 8.2 and 14.6 cm for 12 and 18 detector blocks, respectively. The results showed that a uniform spatial resolution was achieved even in the peripheral region, and measurements were obtained semi-automatically in a short time. PMID:24938490

Tashima, Hideaki; Yoshida, Eiji; Hirano, Yoshiyuki; Nishikido, Fumihiko; Inadama, Naoko; Murayama, Hideo; Yamaya, Taiga

2014-07-01

134

High optical efficiency and photon noise limited sensitivity of microwave kinetic inductance detectors using phase readout  

SciTech Connect

We demonstrate photon noise limited performance in both phase and amplitude readout in microwave kinetic inductance detectors (MKIDs) consisting of NbTiN and Al, down to 100 fW of optical power. We simulate the far field beam pattern of the lens-antenna system used to couple radiation into the MKID and derive an aperture efficiency of 75%. This is close to the theoretical maximum of 80% for a single-moded detector. The beam patterns are verified by a detailed analysis of the optical coupling within our measurement setup.

Janssen, R. M. J., E-mail: r.m.j.janssen@tudelft.nl; Endo, A. [Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628CJ Delft (Netherlands)] [Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628CJ Delft (Netherlands); Baselmans, J. J. A. [SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584CA Utrecht (Netherlands)] [SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584CA Utrecht (Netherlands); Ferrari, L.; Yates, S. J. C. [SRON Netherlands Institute for Space Research, Landleven 12, 9747AD Groningen (Netherlands)] [SRON Netherlands Institute for Space Research, Landleven 12, 9747AD Groningen (Netherlands); Baryshev, A. M. [SRON Netherlands Institute for Space Research, Landleven 12, 9747AD Groningen (Netherlands) [SRON Netherlands Institute for Space Research, Landleven 12, 9747AD Groningen (Netherlands); Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV Groningen (Netherlands); Klapwijk, T. M. [Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628CJ Delft (Netherlands) [Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628CJ Delft (Netherlands); Physics Department, Moscow State Pedagogical University, Moscow 119991 (Russian Federation)

2013-11-11

135

The effect of magnetic field on the intrinsic detection efficiency of superconducting single-photon detectors  

NASA Astrophysics Data System (ADS)

We experimentally investigate the effect of a magnetic field on photon detection in superconducting single-photon detectors (SSPDs). At low fields, the effect of a magnetic field is through the direct modification of the quasiparticle density of states of the superconductor, and magnetic field and bias current are interchangeable, as is expected for homogeneous dirty-limit superconductors. At the field where a first vortex enters the detector, the effect of the magnetic field is reduced, up until the point where the critical current of the detector starts to be determined by flux flow. From this field on, increasing the magnetic field does not alter the detection of photons anymore, whereas it does still change the rate of dark counts. This result points at an intrinsic difference in dark and photon counts, and also shows that no enhancement of the intrinsic detection efficiency of a straight SSPD wire is achievable in a magnetic field.

Renema, J. J.; Rengelink, R. J.; Komen, I.; Wang, Q.; Gaudio, R.; op't Hoog, K. P. M.; Zhou, Z.; Sahin, D.; Fiore, A.; Kes, P.; Aarts, J.; van Exter, M. P.; de Dood, M. J. A.; Driessen, E. F. C.

2015-03-01

136

Study of anomalous charge collection efficiency in heavily irradiated silicon strip detectors  

NASA Astrophysics Data System (ADS)

Anomalous charge collection efficiency observed in heavily irradiated silicon strip detectors operated at high bias voltages has been studied in terms of a simple model and experimentally using 25 ns shaping electronics and transient current technique (TCT) with edge-on laser injection. The model confirmed qualitatively the explanation by electron impact ionization in the high electric field close to the strips, but failed in the quantitative description of the collected charge. First results on a Hamamatsu strip detector irradiated to 5×1015 neq/cm2 and operated at bias voltages in excess of 1000 V exhibit charge collection similar to what obtained on Micron devices. TCT tests with local charge injection by a laser confirm the validity of a linear extrapolation of trapping to very high fluences and reveal significant charge collection from the non-depleted volume of the detector.

Mikuž, M.; Cindro, V.; Kramberger, G.; Mandi?, I.; Zavrtanik, M.

2011-04-01

137

Design and Construction of an Ultra-Low-Background 14 Crystal Germanium Array for High Efficiency and Coincidence Measurements  

SciTech Connect

ABSTRACT Physics experiments, environmental surveillance, and treaty verification techniques continue to require increased sensitivity for detecting and quantifying radionuclides of interest. This can be done by detecting a greater fraction of gamma emissions from a sample (higher detection efficiency) and reducing instrument backgrounds. A current effort for increased sensitivity in high resolution gamma spectroscopy will produce an intrinsic germanium (HPGe) array designed for high detection efficiency, ultra-low-background performance, and useful coincidence efficiencies. The system design is optimized to accommodate filter paper samples, e.g. samples collected by the Radionuclide Aerosol Sampler/Analyzer (RASA). The system will provide high sensitivity for weak collections on atmospheric filter samples, as well as offering the potential to gather additional information from more active filters using gamma cascade coincidence detection. The current effort is constructing an ultra-low-background HPGe crystal array consisting of two vacuum cryostats, each housing a hexagonal array of 7 crystals on the order of 70% relative efficiency per crystal. Traditional methods for constructing ultra-low-background detectors are used, including use of materials known to be low in radioactive contaminants, use of ultra pure reagents, clean room assembly, etc. The cryostat will be constructed mainly from copper electroformed into near-final geometry at PNNL. Details of the detector design, simulation of efficiency and coincidence performance, HPGe crystal testing, and progress on cryostat construction are presented.

Keillor, Martin E.; Aalseth, Craig E.; Day, Anthony R.; Fast, James E.; Hoppe, Eric W.; Hyronimus, Brian J.; Hossbach, Todd W.; Miley, Harry S.; Seifert, Allen; Warren, Glen A.

2009-12-01

138

Novel Approach to Surface Processing for Improving the Efficiency of CdZnTe Detectors  

NASA Astrophysics Data System (ADS)

We emphasize an improvement of the surface processing procedures for cadmium zinc telluride (CZT) detectors, which is one of the principal problems limiting the technology. A rough surface enhances the leakage current into the medium, creating additional trapping centers and thereby degrading the detector's performance. Mechanical polishing followed by chemical treatment yields smoother surfaces as required, but chemical treatment, especially with bromine-based solutions, induces unwanted surface features, increases the surface conductivity, and generates chemical species that alter the material's surface and interfacial properties. It is essential to avoid such adverse consequences of surface etching in the manufacturing of highly efficient radiation detectors. We approached the problem of processing the crystals' surfaces by using two different solutions (a low-concentration bromine-based etchant mixture in conjunction with a surface-passivation reagent and a non-bromine-based etchant). The chemomechanical treatment yielded smooth nonconductive surfaces with fewer detrimental features, therefore allowing us to fabricate better devices. We determined the surface roughness using atomic force microscopy and optical profilometry (OP). We analyzed the surface structure, orientations of the crystals, and formation of chemical species by x-ray photoelectron spectroscopy techniques and delineated their effects on the devices' electrical properties and performance. Our experimental data revealed that our new chemical etching process produced nonconductive surfaces with fewer surface defects and so improved the detectors' charge transport and efficiency. We detail the results of our new etchants and compare them with those for conventional Br-methanol etchants.

Hossain, A.; Bolotnikov, A. E.; Camarda, G. S.; Cui, Y.; Jones, D.; Hall, J.; Kim, K. H.; Mwathi, J.; Tong, X.; Yang, G.; James, R. B.

2014-08-01

139

Efficient phase contrast imaging in STEM using a pixelated detector. Part II: Optimisation of imaging conditions.  

PubMed

In Part I of this series of two papers, we demonstrated the formation of a high efficiency phase-contrast image at atomic resolution using a pixelated detector in the scanning transmission electron microscope (STEM) with ptychography. In this paper we explore the technique more quantitatively using theory and simulations. Compared to other STEM phase contrast modes including annular bright field (ABF) and differential phase contrast (DPC), we show that the ptychographic phase reconstruction method using pixelated detectors offers the highest contrast transfer efficiency and superior low dose performance. Applying the ptychographic reconstruction method to DPC segmented detectors also improves the detector contrast transfer and results in less noisy images than DPC images formed using difference signals. We also find that using a minimum array of 16×16 pixels is sufficient to provide the highest signal-to-noise ratio (SNR) for imaging beam sensitive weak phase objects. Finally, the convergence angle can be adjusted to enhance the contrast transfer based on the spatial frequencies of the specimen under study. PMID:25481091

Yang, Hao; Pennycook, Timothy J; Nellist, Peter D

2015-04-01

140

An efficient, movable single-particle detector for use in cryogenic ultra-high vacuum environments  

NASA Astrophysics Data System (ADS)

A compact, highly efficient single-particle counting detector for ions of keV/u kinetic energy, movable by a long-stroke mechanical translation stage, has been developed at the Max-Planck-Institut für Kernphysik (Max Planck Institute for Nuclear Physics, MPIK). Both, detector and translation mechanics, can operate at ambient temperatures down to ˜10 K and consist fully of ultra-high vacuum compatible, high-temperature bakeable, and non-magnetic materials. The set-up is designed to meet the technical demands of MPIK's Cryogenic Storage Ring. We present a series of functional tests that demonstrate full suitability for this application and characterise the set-up with regard to its particle detection efficiency.

Spruck, Kaija; Becker, Arno; Fellenberger, Florian; Grieser, Manfred; von Hahn, Robert; Klinkhamer, Vincent; Novotný, Old?ich; Schippers, Stefan; Vogel, Stephen; Wolf, Andreas; Krantz, Claude

2015-02-01

141

An efficient, movable single-particle detector for use in cryogenic ultra-high vacuum environments.  

PubMed

A compact, highly efficient single-particle counting detector for ions of keV/u kinetic energy, movable by a long-stroke mechanical translation stage, has been developed at the Max-Planck-Institut für Kernphysik (Max Planck Institute for Nuclear Physics, MPIK). Both, detector and translation mechanics, can operate at ambient temperatures down to ?10 K and consist fully of ultra-high vacuum compatible, high-temperature bakeable, and non-magnetic materials. The set-up is designed to meet the technical demands of MPIK's Cryogenic Storage Ring. We present a series of functional tests that demonstrate full suitability for this application and characterise the set-up with regard to its particle detection efficiency. PMID:25725832

Spruck, Kaija; Becker, Arno; Fellenberger, Florian; Grieser, Manfred; von Hahn, Robert; Klinkhamer, Vincent; Novotný, Old?ich; Schippers, Stefan; Vogel, Stephen; Wolf, Andreas; Krantz, Claude

2015-02-01

142

Investigation of the Charge Collection Efficiency of CdMnTe Radiation Detectors  

Microsoft Academic Search

This paper presents the growth, fabrication and characterization of indium-doped cadmium manganese telluride (CdMnTe) crystals grown by the vertical Bridgman technique. The 10$\\\\,\\\\times\\\\,$ 10$\\\\,\\\\times\\\\,$ 1.9 mm$^{3}$ samples have been fabricated, and the charge collection properties of the CdMnTe detectors have been measured. Alpha-particle spectroscopy measurements have yielded an average charge collection efficiency approaching 100%. Ion beam induced charge (IBIC) measurements

R. Rafiei; D. Boardman; A. Sarbutt; D. A. Prokopovich; K. Kim; M. I. Reinhard; A. E. Bolotnikov; R. B. James

2012-01-01

143

A broad-range detector system with large geometric efficiency for heavy-ion reaction studies  

NASA Astrophysics Data System (ADS)

A detector module sensitive to heavy ions, capable of covering a very large solid angle, and having a broad dynamic range in energy and atomic number has been designed and tested. It is tapered, has a pentagonal cross section and has been constructed to permit close-packing in a spherical array with a minimum of inactive area. The detector consists of a radial-field drift chamber for Bragg-curve spectroscopy, followed by a thin fast-plastic scintillator laminated to a thick slow-plastic scintillator for light-ion detection; the two scintillators are read together in phoswich ?E — E mode. Mixed-mode operation is also possible, with the drift chamber serving as a ?E counter and the fast plastic scintillator providing an energy signal. Tests with a beam of 145 MeV 28Si ions have shown that for 83% geometric efficiency (active/total solid angle) the Bragg curve spectrometer gives ? {Z}/{Z ? 5% at Z = 12 } and ? {E}/{E ? 6%} for silicon ions depositing 100 MeV in the detector. Mixed mode operation has 70% geometric efficiency with a measured ? {Z}/{Z ? 5%} for Z = 8. Phoswich mode operation also has 70% geometric efficiency and gives ? {Z}/{Z ? 6%} for Z = 2; isotopic identification of light ions is unambiguous.

Potvin, L.; Ball, G. C.; Davies, W. G.; Forster, J. S.; Hagberg, E.; Horn, D.; Lone, M. A.; Montaigne, M.; Sims, G. A.; Steer, M. G.; Toone, R. J.; Roy, R.; St-Pierre, C.; Galindo-Uribarri, A.

1989-09-01

144

Real time method and computer system for identifying radioactive materials from HPGe gamma-ray spectroscopy  

DOEpatents

A real-time method and computer system for identifying radioactive materials which collects gamma count rates from a HPGe gamma-radiation detector to produce a high-resolution gamma-ray energy spectrum. A library of nuclear material definitions ("library definitions") is provided, with each uniquely associated with a nuclide or isotope material and each comprising at least one logic condition associated with a spectral parameter of a gamma-ray energy spectrum. The method determines whether the spectral parameters of said high-resolution gamma-ray energy spectrum satisfy all the logic conditions of any one of the library definitions, and subsequently uniquely identifies the material type as that nuclide or isotope material associated with the satisfied library definition. The method is iteratively repeated to update the spectrum and identification in real time.

Rowland, Mark S. (Alamo, CA); Howard, Douglas E. (Livermore, CA); Wong, James L. (Dublin, CA); Jessup, James L. (Tracy, CA); Bianchini, Greg M. (Livermore, CA); Miller, Wayne O. (Livermore, CA)

2007-10-23

145

Comparison of two HPGe counting system used in activation studies for nuclear astrophysics  

SciTech Connect

The activation method is a widely used technique to measure charged-particle induced cross sections for astrophys-ical applications. This two step technique is used for example to measure alpha-induced cross sections in ?-process related studies. The first step – in which a target is irradiated with a proton/alpha beam – is followed by the determination of the produced activity. Especially in p-process related studies in the heavier mass range, the produced radioactive nuclei decays mainly with electron-capture, resulting intense x-rays. The activity of the reaction products hence can be determine via the counting of these x-rays, and not only by counting the usually much weaker ?-rays. In this paper we compare the minimum detectable activity (MDA) of two High Purity Germanium (HPGe) detectors used for x- and ?-ray counting in activation experiments.

Szücs, T.; Kiss, G. G.; Fülöp, Zs. [Institute for Nuclear Research (MTA Atomki), H-4001 Debrecen, POB 51 (Hungary)

2014-05-09

146

A prototype, high-efficiency, position sensitive neutron detector for the proposed neutron spin rotation experiment at the SNS  

Microsoft Academic Search

We are developing a position sensitive (˜ 1 cm resolution) neutron detector with nearly 100% efficiency for use at the high flux (> 5 x10^10 neutrons\\/sec) pulsed beam at the Oak Ridge Spallation Neutron Source (SNS). The prototype detector is important for transmission experiments such as the proposed parity-violating neutron spin rotation in hydrogen measurement. The detector concept integrates the

D. M. Markoff; V. Cianciolo; C. L. Britton; R. G. Cooper; R. J. Warmack

2006-01-01

147

Hand-Held Gamma-Ray Spectrometer Based on High-Efficiency Frisch-Ring CdZnTe Detectors  

Microsoft Academic Search

Frisch-ring CdZnTe detectors have demonstrated both good energy resolution, <1% FWHM at 662 keV, and good efficiency in detecting gamma rays, highlighting the strong potential of CdZnTe materials for such applications. We are designing a hand-held gamma-ray spectrometer based on Frisch-ring detectors at Brookhaven National Laboratory. It employs an 8 times 8 CdZnTe detector array to achieve a high volume

Yonggang Cui; Aleksey Bolotnikov; Giuseppe Camarda; Anwar Hossain; Ralph B. James; Gianluigi De Geronimo; Jack Fried; Paul O'Connor; Alireza Kargar; Mark J. Harrison; Douglas S. McGregor

2008-01-01

148

Detection efficiency of a BEGe detector using the Monte Carlo method and a comparison to other calibration methods  

E-print Network

In this paper we model by using the Monte Carlo simulation code PENELOPE [1, 2] a Broad Energy Germanium (BEGe) detector and determine its efficiency. The simulated geometry consists of a point source located close to the detector as well as volume sources with cylindrical geometry. A comparison of the simulation is made to experimental results as well as to analytical calculations.

Stefanakis, N

2014-01-01

149

Detection efficiency for measuring 241Am in axillary lymph nodes using different types and sizes of detectors.  

PubMed

The detection efficiency and interference susceptibility of four different types of low energy photon detectors, each with a unique geometric arrangement, were compared for direct measurement of Am deposited in the axillary lymph nodes. Although the most efficient detector was a single large 23,226 mm square phoswich detector, it was also the most susceptible to confounding depositions from activity deposited in adjacent organs. The array of two 2,800 mm high purity germanium detectors exhibited the highest efficiency per unit detector area with some resistance to confounding from activity deposited in the lungs. The array of two 4,560 mm NaI(Tl) detectors was the least susceptible to confounding and nearly as efficient per square millimeter as the high purity germanium detector array. Thus, selection of a detector system for in vivo measurement of activity deposited in the axillary lymph nodes should consider whether there is a likelihood for activity deposited in other organs, such as the lungs, skeleton, or liver, to create an interference that will confound the measurement result. PMID:22850233

Lobaugh, Megan L; Spitz, Henry B; Glover, Samuel E

2012-09-01

150

2010 IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 49, NO. 4, AUGUST 2002 Estimate of Large CZT Detector Absolute Efficiency  

E-print Network

quality are proposed. Index Terms--CdZnTe, CZT, Monte Carlo methods, radiation detectors, simulation. I-efficiency gamma radiation detectors. In spite of the improved quality of the material and device con- struction2010 IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 49, NO. 4, AUGUST 2002 Estimate of Large CZT

He, Zhong

151

A 3-dimensional interdigitated electrode geometry for the enhancement of charge collection efficiency in diamond detectors  

NASA Astrophysics Data System (ADS)

In this work, a single crystal CVD diamond film with a novel three-dimensional (3D) interdigitated electrode geometry has been fabricated with the reactive ion etching (RIE) technique in order to increase the charge collection efficiency (CCE) with respect to that obtained by standard superficial electrodes. The geometrical arrangement of the electric field lines due to the 3D patterning of the electrodes results in a shorter travel path for the excess charge carriers, thus contributing to a more efficient charge collection mechanism. The CCE of the device was mapped by means of the ion beam induced charge (IBIC) technique. A 1 MeV proton micro-beam was raster-scanned over the active area of the diamond detector under different bias voltage conditions, enabling to probe the charge transport properties of the detector up to a depth of 8 ? \\text{m} below the sample surface. The experimental results, supported by the numerical simulations, show a significant improvement in the 3D detector performance (i.e. CCE, energy resolution, extension of the active area) if compared with the results obtained by standard surface metallic electrodes.

Forneris, J.; Lo Giudice, A.; Olivero, P.; Picollo, F.; Re, A.; Marinelli, Marco; Pompili, F.; Verona, C.; Verona Rinati, G.; Benetti, M.; Cannata, D.; Di Pietrantonio, F.

2014-10-01

152

High-speed and high-efficiency travelling wave single-photon detectors embedded in nanophotonic circuits  

PubMed Central

Ultrafast, high-efficiency single-photon detectors are among the most sought-after elements in modern quantum optics and quantum communication. However, imperfect modal matching and finite photon absorption rates have usually limited their maximum attainable detection efficiency. Here we demonstrate superconducting nanowire detectors atop nanophotonic waveguides, which enable a drastic increase of the absorption length for incoming photons. This allows us to achieve high on-chip single-photon detection efficiency up to 91% at telecom wavelengths, repeatable across several fabricated chips. We also observe remarkably low dark count rates without significant compromise of the on-chip detection efficiency. The detectors are fully embedded in scalable silicon photonic circuits and provide ultrashort timing jitter of 18?ps. Exploiting this high temporal resolution, we demonstrate ballistic photon transport in silicon ring resonators. Our direct implementation of a high-performance single-photon detector on chip overcomes a major barrier in integrated quantum photonics. PMID:23271658

Pernice, W.H.P.; Schuck, C.; Minaeva, O.; Li, M.; Goltsman, G.N.; Sergienko, A.V.; Tang, H.X.

2012-01-01

153

Effects of neutron energy spectrum on the efficiency calibration of epithermal neutron detectors  

NASA Astrophysics Data System (ADS)

The 235U epithermal neutron fission detector system at TFTR has been calibrated in situ, using three different neutron sources: 252Cf, a D-D, and a D-T neutron generator. These sources produced a continuous spectrum, a line spectrum at ˜2.5 MeV, and a line spectrum at ˜14 MeV, respectively. The toroidally averaged detection efficiencies are 4.61×10-9 (252Cf), 4.80×10-9 (D-D), and 5.42×10-9 (D-T) counts/neutron for a moderated 1.3-g 235U detector placed ˜4 m from the torus centerline. The effects of (n,2n) and (n,n'?) reactions are discussed.

Nieschmidt, E. B.; England, A. C.; Hendel, H. W.; Hillis, D. L.; Isaacson, J. A.; Ku, L. P.; Tsang, F. Y.

1985-05-01

154

Parallel Beam Approximation for Calculation of Detection Efficiency of Crystals in PET Detector Arrays.  

PubMed

In this work we propose a parallel beam approximation for the computation of the detection efficiency of crystals in a PET detector array. In this approximation the detection efficiency of a crystal is estimated using the distance between source and the crystal and the pre-calculated detection cross section of the crystal in a crystal array which is calculated for a uniform parallel beam of gammas. The pre-calculated detection cross sections for a few representative incident angles and gamma energies can be used to create a look-up table to be used in simulation studies or practical implementation of scatter or random correction algorithms. Utilizing the symmetries of the square crystal array, the pre-calculated look-up tables can be relatively small. The detection cross sections can be measured experimentally, calculated analytically or simulated using a Monte Carlo (MC) approach. In this work we used a MC simulation that takes into account the energy windowing, Compton scattering and factors in the "block effect". The parallel beam approximation was validated by a separate MC simulation using point sources located at different positions around a crystal array. Experimentally measured detection efficiencies were compared with Monte Carlo simulated detection efficiencies. Results suggest that the parallel beam approximation provides an efficient and accurate way to compute the crystal detection efficiency, which can be used for estimation of random and scatter coincidences for PET data corrections. PMID:25400292

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

2011-10-01

155

Statistics of the LS-detector in the case of low counting efficiency.  

PubMed

In the case of high-quenched 3H and 63Ni sources a distinct incompatibility of theoretical and experimental detection efficiency in the triple liquid scintillation (LS) detector was observed (Appl. Radiat. Isot. 52 (2000) 643). The authors concluded, that the Poisson distribution does not properly describe the detection process, when less than one photoelectron is expected in one of the photomultipliers. Application of other distributions of photoelectrons, e.g. binomial, does not solve the observable problem of incompatibility. Measurements of a set of 55Fe sources have been performed with phototubes defocusing and grey filters for decreasing the counting efficiency of the TDCR detector. Differences between counting results of the 55Fe source and the light emitting diode (LED), simulating the scintillation source, excited by a pulse generator have been observed. Various distributions (Poisson, binomial and Polya) were used for the determination of the theoretical counting efficiency in both cases. The Poisson law gave a good result in the case of the LED but the Polya law had to be applied in the case of 55Fe. The results were independent of the scintillator volume. It seems that the validity of the Polya law in the case of LS-sources is related to the scintillator itself. Measurements of the 3H solution confirmed that conclusion. PMID:14987684

Broda, R; Jeczmieniowski, A

2004-01-01

156

SPE analysis of high efficiency PMTs for the DEAP-3600 dark matter detector  

NASA Astrophysics Data System (ADS)

The Dark matter Experiment using Argon Pulse-shape discrimination is a collaborative effort to develop a next-generation, tonne-scale dark matter detector at SNOLAB. The detector will feature a single-phase liquid argon (LAr) target surrounded by an array of 266 photomultiplier tubes (PMTs). A new high-efficiency Hamamatsu R877-100 PMT has been delivered to the University of Alberta for evaluation by the DEAP collaboration. The increase in efficiency could lead to a much greater light yield, but other experiments have reported a slower rise time [1],[2]. We have placed the PMT in a small dark box and had a base and preamplifier designed to be used with either an oscilloscope or a multi-channel analyzer. With this setup we have demonstrated the PMT's ability to distinguish single photo-electrons (SPE) and characterized the PMT by measuring the SPE pulse height spectrum, the peak-to-valley ratio, the dark pulse rate, the baseline, time resolution and SPE efficiency for varying the high voltage supplied to the PMT.

Olsen, Kevin; Hallin, Aksel; DEAP/CLEAN Collaboration

2011-09-01

157

Direct-reaction studies by particle-{gamma} coincidence spectroscopy using Csi-Hpge and Si-Hpge arrays  

SciTech Connect

Particle-{gamma} and particle-{gamma}-{gamma} coincidence spectroscopy has several advantages in the study of direct reactions (particularly in inverse kinematics) since it can generally allow determination of: decay paths; high-precision level energies; multipolarities of transitions; and cross sections. Techniques for studying direct reactions by particle-{gamma} coincidence spectroscopy are presented for two cases: (1) heavy-ion reactions with CsI-HPGe, and (2) light-ion reactions with Si-HPGe. Future direct-reaction studies with radioactive ion beams (RIBs) will mostly involve low beam intensities and inverse kinematics (i.e., A{sub beam}>A{sub target}), which eliminates the traditional use of magnetic spectrometers. Particle-{gamma} coincidence spectroscopy currently provides the most viable method to study direct reactions with nuclei of any level density. In the present study, the capabilities and limitations of the technique are explored.

Allmond, J. M. [Joint Institute for Heavy Ion Research, Oak Ridge National Laboratory, Oak Ridge TN 37831 (United States)

2013-04-19

158

Calibration of ? single hexagonal NaI(Tl) detector using a new numerical method based on the efficiency transfer method  

NASA Astrophysics Data System (ADS)

Gamma-ray detector systems are important instruments in a broad range of science and new setup are continually developing. The most recent step in the evolution of detectors for nuclear spectroscopy is the construction of large arrays of detectors of different forms (for example, conical, pentagonal, hexagonal, etc.) and sizes, where the performance and the efficiency can be increased. In this work, a new direct numerical method (NAM), in an integral form and based on the efficiency transfer (ET) method, is used to calculate the full-energy peak efficiency of a single hexagonal NaI(Tl) detector. The algorithms and the calculations of the effective solid angle ratios for a point (isotropic irradiating) gamma-source situated coaxially at different distances from the detector front-end surface, taking into account the attenuation of the gamma-rays in the detector's material, end-cap and the other materials in-between the gamma-source and the detector, are considered as the core of this (ET) method. The calculated full-energy peak efficiency values by the (NAM) are found to be in a good agreement with the measured experimental data.

Abbas, Mahmoud I.; Badawi, M. S.; Ruskov, I. N.; El-Khatib, A. M.; Grozdanov, D. N.; Thabet, A. A.; Kopatch, Yu. N.; Gouda, M. M.; Skoy, V. R.

2015-01-01

159

Majorana: An Ultra-Low Background Enriched-Germanium Detector Array for Fundamental Physics Measurements  

Microsoft Academic Search

The Majorana collaboration will search for neutrinoless double-beta decay (0nubetabeta) by fielding an array of high-purity germanium (HPGe) detectors in ultra-clean electroformed-copper cryostats deep underground. Recent advances in HPGe detector technology, in particular P-type Point-Contact (PPC) detectors, present exciting new techniques for identifying and reducing backgrounds to the 0nubetabeta. This should result in greatly improved sensitivity over previous generation experiments.

Michael Miller

2010-01-01

160

MAJORANA: An Ultra-Low Background Enriched-Germanium Detector Array for Fundamental Physics Measurements  

Microsoft Academic Search

The Majorana collaboration aims to perform a search for neutrinoless double-beta decay (0nubetabeta) by fielding arrays of HPGe detectors mounted in ultra-clean electroformed-copper cryostats located deep underground. Recent advances in HPGe detector technology, in particular P-type Point-Contact (PPC) detectors, show great promise for identifying and reducing backgrounds to the 0nubetabeta signal, which should result in improved sensitivity over previous generation

Jason Detwiler

2009-01-01

161

Efficiency calibration of low-energy electron detectors by means of ?-ray emitters  

NASA Astrophysics Data System (ADS)

The relative efficiency of a channel electron multiplier for 2-9 keV electrons was determined using the ?-spectra of vacuum evaporated 241Pu and 63Ni sources. The results agreed within ±0.8% (1 ?). Conversion electron measurements of 57Co and 169Yb supported the result. The electron scattering and energy losses within the sources were taken into account by means of Monte Carlo simulations of individual elastic and inelastic collisions. The detector was calibrated in the same geometry as it works inside the cylindrical mirror analyzer.

Špalek, A.; Dragoun, O.; Ryšavý, M.; Dragounová, N.

1999-12-01

162

Very high quantum efficiency fast light sensors for cosmic ray detectors.  

NASA Astrophysics Data System (ADS)

Low level light (LLL) sensors are widely used in cosmic ray detectors. Common LLL sensors are the classical photomultiplier tubes (PMT), which provide a peak quantum efficiency (QE) of 20-25% in the wavelength range ?320 - 420 nm. The authors discuss recent progress in the field of hybrid PMTs applying GaAsP photocathodes, which provide a QE of ?45% in the wavelength range 500 - 600 nm and a significantly better amplitude resolution compared to classical PMTs. By application of wavelength shifting technique (WLS) their QE can be enhanced close to the maximum level also in the blue and near ultraviolet parts of the spectrum.

Mirzoyan, R.; Lorenz, E.

1999-03-01

163

Scintillation efficiency for low energy nuclear recoils in liquid xenon dark matter detectors  

NASA Astrophysics Data System (ADS)

We perform a theoretical study of the scintillation efficiency of the low energy region crucial for liquid xenon dark matter detectors. We develop a computer program to simulate the cascading process of the recoiling xenon nucleus in liquid xenon and calculate the nuclear quenching effect due to atomic collisions. We use the electronic stopping power extrapolated from experimental data to the low energy region, and take into account the effects of electron escape from electron-ion pair recombination using the generalized Thomas-Imel model fitted to scintillation data. Our result agrees well with the experiments from neutron scattering and vanishes rapidly as the recoil energy drops below 3 keV.

Mu, Wei; Xiong, Xiaonu; Ji, Xiangdong

2015-02-01

164

Numerical Simulations of Pillar Structured Solid State Thermal Neutron Detector Efficiency and Gamma Discrimination  

SciTech Connect

This work reports numerical simulations of a novel three-dimensionally integrated, {sup 10}boron ({sup 10}B) and silicon p+, intrinsic, n+ (PIN) diode micropillar array for thermal neutron detection. The inter-digitated device structure has a high probability of interaction between the Si PIN pillars and the charged particles (alpha and {sup 7}Li) created from the neutron - {sup 10}B reaction. In this work, the effect of both the 3-D geometry (including pillar diameter, separation and height) and energy loss mechanisms are investigated via simulations to predict the neutron detection efficiency and gamma discrimination of this structure. The simulation results are demonstrated to compare well with the measurement results. This indicates that upon scaling the pillar height, a high efficiency thermal neutron detector is possible.

Conway, A; Wang, T; Deo, N; Cheung, C; Nikolic, R

2008-06-24

165

Derivation of sensitivity of a Geiger mode APDs detector from a given efficiency for QKD experiments  

E-print Network

The detection sensitivity (DS) of the commercial single-photon-receiver based on InGaAs gate-mode avalanche photodiode is estimated. Instalment of a digital-blanking-system (DBS) to reduce dark current makes the difference between DS, which is an efficiency of the detector during its open-gate/active state, and the total/overall detection efficiency (DE). By numerical simulations, it is found that the average number of light-pulses, blanked by DBS, following a registered pulse is 0.333. DS is estimated at 0.216, which can be used for estimating DE for an arbitrary photon arriving rate and a gating frequency of the receiver.

Kiyotaka Hammura; David Williams

2009-01-05

166

Using of the natural radioactive elements for determining Ge-detector efficiencies  

E-print Network

A method is proposed to use of the mixture of Uran oxide and non-active matrix (e.g., NaCl) and also potassium and lanthanum for determining Ge-detector efficiencies. The preparations containing of known amouts of the U or K, or La were measured by means of the Ge-detector, which a efficiency curve has been obtained through the reference solutions of 241Am, 109Cd, 57Co, 139Ce, 137Cs, 60Co. Results the measurements were compared the activities of the preparations calculated from mass of 235U, 238U, 138La, 40K in the samples, its natural abundance, half lives and intensities of gamma lines. Discrepancy of the activities in the energy range between 163 and 1461 keV does not exeed 7 %. For correct comparison of the activities the coefficients {\\omega} were calculated, which took into consideration a varied sorption of gamma-rays in water and in mixture of the Uran oxide and matrix.

E. G. Tertyshnik; I. E. Epifanova

2012-03-30

167

Minimum length Pb/SCIN detector for efficient cosmic ray identification  

NASA Technical Reports Server (NTRS)

A study was made of the performance of a minimal length cosmic ray shower detector that would be light enough for space flight and would provide efficient identification of positions and protons. Cosmic ray positions are mainly produced in the decay chain of: Pion yields Muon yields Positron and they provide a measure of the matter density traversed by primary protons. Present positron flux measurements are consistent with the Leaky Box and Halo models for sources of cosmic rays. Abundant protons in the space environment are a significant source of background that would wash out the positron signal. Protons and positrons produced very distictive showers of particles when they enter matter; many studies have been published on their behavior on large calorimeter detectors. The challenge is to determine the minimal material necessary (minimal calorimeter depth) for positive particles identification. The primary instrument for the investigation is the Monte Carlo code GEANT, a library of programs from CERN that can be used to model experimental geometry, detector responses and particle interaction processes. The use of the Monte Carlo approach is crucial since statistical fluctuations in shower shape are significant. Studies conducted during the 1988 summer program showed that straightforward approaches to the problem achieved 85 to 90 percent correct identification, but left a residue of 10 to 15 percent misidentified particles. This percentage improved to a few percent when multiple shower-cut criteria were applied to the data. This summer, the same study was extended to employ several physical and statistical methods of identifying response of the calorimeter and the efficiency of the optimal shower cuts to off-normal incidence particle was determined.

Snyder, H. David

1989-01-01

168

GRABGAM Analysis of Ultra-Low-Level HPGe Gamma Spectra  

SciTech Connect

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.

Winn, W.G.

1999-07-28

169

``Neutron Shell'': a high efficiency array of neutron detectors for gamma-ray spectroscopic studies with Gammasphere  

Microsoft Academic Search

A shell of neutron detectors was designed, constructed, and employed in gamma-ray spectroscopy with Gammasphere. It consists of up to 35 tapered regular hexagons that replace the same number of forward Ge-detector modules in Gammasphere. The shell was designed for high detection efficiency and very good neutron-gamma discrimination. The simultaneous use of time-of-flight, and two methods of pulse shape discrimination

D. G. Sarantites; W. Reviol; C. J. Chiara; R. J. Charity; L. G. Sobotka; M. Devlin; M. Furlotti; O. L. Pechenaya; J. Elson; P. Hausladen; S. Fischer; D. Balamuth; R. M. Clark

2004-01-01

170

Neutron detection efficiency and capture product energy spectra of all-semiconducting-boron carbide and conversion-layer detectors  

Microsoft Academic Search

Solid-state neutron detectors based only on boron-rich semiconductor are of interest for their potential to provide the highest thermal neutron detection efficiencies of any solid-state neutron detectors. A simplified physical model is shown to generate capture product spectra that agree quantitatively with full-physics GEANT4 simulation. Using this model, comparisons are made between the ideal capture-product energy spectra of planar conversion

A. D. Harken; C. N. Lundstedt; E. E. Day; B. W. Robertson

2004-01-01

171

Reducing the Read Noise of H2RG Detector Arrays by more Efficient use of Reference Signals  

NASA Technical Reports Server (NTRS)

We present a process for characterizing the correlation properties of the noise in large two-dimensional detector arrays, and describe an efficient process for its removal. In the case of the 2k x 2k HAWAII-2RG detectors (H2RG) detectors from Teledyne which are being used on the Near Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope (JWST), we find that we can reduce the read noise by thirty percent. Noise on large spatial scales is dramatically reduced. With this relatively simple process, we provide a performance improvement that is equivalent to a significant increase in telescope collecting area for high resolution spectroscopy with NIRSpec.

Rauscher, Bernard J.; Arendt, Richard G.; Fixen, D. J.; Lindler, Don; Loose, Markus; Moseley, S. H.; Wilson, D. V.

2011-01-01

172

Assessing Lanthanum-Bromide Detectors for Safeguards Applications  

SciTech Connect

Major detector technologies currently being used for gamma-ray spectroscopy in safeguards applications include systems based on sodium iodide (NaI), cadmium-zinc-telluride (CZT), cadmium-telluride (CdTe), and high-purity germanium (HPGe) crystals. Recently, a new scintillation detector based on a lanthanum bromide (LaBr3) crystal has become commercially available. The declared benefits of this new detector technology include higher resolution and improved efficiency compared with similarly configured NaI-based systems. Both detector systems offer the advantage of room-temperature operation. This paper describes the results of a study assessing the safeguards applicability and advantages for isotopic and quantitative analyses of uranium using the LaBr3-based detector, as well as an investigation into the general operating characteristics of the LaBr3-based detector. The results are compared with those from a widely used NaI-based detector system (Canberra's Inspector-1000 multichannel analyzer) operated under similar environmental conditions and hardware configuration, using commercially available software packages (NaIGEM and Genie-2000).

Gariazzo, Claudio Andres [ORNL; Saavedra, Steven F [ORNL; Smith, Steven E [ORNL; Solodov, Alexander A [ORNL

2008-01-01

173

HAND-HELD GAMMA-RAY SPECTROMETER BASED ON HIGH-EFFICIENCY FRISCH-RING CdZnTe DETECTORS.  

SciTech Connect

Frisch-ring CdZnTe detectors have demonstrated good energy resolution, el% FWHM at 662 keV, and good efficiency for detecting gamma rays. This technique facilitates the application of CdZnTe materials for high efficiency gamma-ray detection. A hand-held gamma-ray spectrometer based on Frisch-ring detectors is being designed at Brookhaven National Laboratory. It employs an 8x8 CdZnTe detector array to achieve a high volume of 19.2 cm3, so that detection efficiency is significantly improved. By using the front-end ASICs developed at BNL, this spectrometer has a small profile and high energy resolution. The spectrometer includes signal processing circuit, digitization and storage circuit, high-voltage module, and USB interface. In this paper, we introduce the details of the system structure and report our test results with it.

CUI,Y.

2007-05-01

174

Activity determination of (41)Ar using efficiency extrapolation method and 4??(PS)-4??(NaI) coincidence system.  

PubMed

Noble gas (41)Ar was measured with a 4??-4?? coincidence system, in which gamma- and beta-rays were respectively detected with a well-type NaI(Tl) and plastic scintillator (PS) detector. The activity of (41)Ar was determined from an efficiency extrapolation method, in which the beta detector efficiency was varied by electronic discrimination using the software developed under Visual basic. In addition, high resolution gamma spectroscopy with HPGe detector was also used for activity determination of (41)Ar, and the result was satisfactory in agreement with that obtain by the efficiency extrapolation method. This work demonstrated that the activity of (41)Ar can be accurately measured by efficiency extrapolation method. PMID:25527895

Xie, Feng; Li, Xuesong; Dai, Yihua; Jiang, Wengang; He, Xiaobing; Yu, Gongshuo; Ni, Jianzhong

2015-03-01

175

Majo-ra-na: An Ultra-Low Background Enriched-Germanium Detector Array for Fundamental Physics Measurements  

Microsoft Academic Search

The Majo-ra-na collaboration will search for neutrinoless double-beta decay (0nubetabeta) by fielding an array of high-purity germanium (HPGe) detectors in ultra-clean electroformed-copper cryostats deep underground. Recent advances in HPGe detector technology, in particular P-type Point-Contact (PPC) detectors, present exciting new techniques for identifying and reducing backgrounds to the 0nubetabeta signal. This should result in greatly improved sensitivity over previous generation

Victor Gehman

2010-01-01

176

Measurement of the Charge Collection Efficiency After Heavy Non-Uniform Irradiation in BABAR Silicon Detectors  

SciTech Connect

We have investigated the depletion voltage changes, leakage current increase and charge collection efficiency of a silicon microstrip detector identical to those used in the inner layers of the BABAR Silicon Vertex Tracker (SVT) after heavy nonuniform irradiation. A full SVT module with the front-end electronics connected has been irradiated with a 0.9 GeV electron beam up to a peak fluence of 3.5 x 10{sup 14} e{sup -}/cm{sup 2}, well beyond the level causing substrate type inversion. We have irradiated the silicon with a nonuniform profile having {sigma} = 1.4 mm that simulates the conditions encountered in the BABAR experiment by the modules intersecting the horizontal machine plane. The position dependence of the charge collection properties and the depletion voltage have been investigated in detail using a 1060 nm LED and an innovative measuring technique based only on the digital output of the chip.

Bettarini, S.; Bondioli, M.; Calderini, G.; Forti, F.; Marchiori, G.; Rizzo, G.; Giorgi, M.A.; /INFN, Pisa /Pisa U. /SLAC; Bosisio, L.; Dittongo, S.; /INFN, Trieste; Campagnari, C.; /UC, Santa Barbara

2006-03-01

177

Three-dimensional diamond detectors: Charge collection efficiency of graphitic electrodes  

SciTech Connect

Implementation of 3D-architectures in diamond detectors promises to achieve unreached performances in the radiation-harsh environment of future high-energy physics experiments. This work reports on the collection efficiency under ?-irradiation of graphitic 3D-electrodes, created by laser pulses in the domains of nanoseconds (ns-made-sensors) and femtoseconds (fs-made-sensors). Full collection is achieved with the fs-made-sensors, while a loss of 25%–30% is found for the ns-made-sensors. The peculiar behaviour of ns-made sensors has been explained by the presence of a nano-structured sp{sup 3}-carbon layer around the graphitic electrodes, evidenced by micro-Raman imaging, by means of a numerical model of the charge transport near the electrodes.

Lagomarsino, S., E-mail: lagomarsino@fi.infn.it; Parrini, G.; Sciortino, S. [National Institute of Nuclear Physics (INFN), Via B. Rossi 1-3, 50019 Sesto Fiorentino (Italy) [National Institute of Nuclear Physics (INFN), Via B. Rossi 1-3, 50019 Sesto Fiorentino (Italy); Department of Physics and Astronomy, University of Florence, Via G. Sansone 1, 50019 Sesto Fiorentino (Italy); Bellini, M.; Gorelli, F.; Santoro, M. [European Laboratory for Non-Linear Spectroscopy, Via Nello Carrara 1, 50019 Sesto Fiorentino (Italy) [European Laboratory for Non-Linear Spectroscopy, Via Nello Carrara 1, 50019 Sesto Fiorentino (Italy); Istituto Nazionale di Ottica (INO-CNR), Largo Enrico Fermi 6, 50125 Firenze (Italy); Corsi, C. [European Laboratory for Non-Linear Spectroscopy, Via Nello Carrara 1, 50019 Sesto Fiorentino (Italy)] [European Laboratory for Non-Linear Spectroscopy, Via Nello Carrara 1, 50019 Sesto Fiorentino (Italy)

2013-12-02

178

Photo detector IC for Blu-ray-Disc applications: a realization applying efficient design methodologies  

NASA Astrophysics Data System (ADS)

A high-speed photo detector IC for application in Blu-ray/DVD/CD drives is presented. Bandwidths for the highest gain of 254 MHz and 221 MHz for 405 nm (Blu-ray) and 635 nm (DVD) wavelengths, respectively, were achieved by applying novel design methodologies. The combination of this outstanding speed performance with its low power dissipation of 192 mW at 5V supply and the low noise power of -72 dBm at 300 MHz makes it the best in literature reported optical transceiver IC for Blu-ray and Blu-ray/DVD/CD multi drives. Beside the excellent performance results, the usage of the novel design methodologies gave us an increased design efficiency with 25% compared to earlier similar design processes.

Lange, S.; Reich, T.; Nowak, J.; Dimov, B.; Meister, M.; Hennig, E.

2011-08-01

179

Improvements to the resolution and efficiency of the DEAP-3600 dark matter detector and their effects on background studies  

NASA Astrophysics Data System (ADS)

The Dark matter Experiment using Argon Pulse-shape discrimination will be a tonne scale liquid argon experiment to detect scintillation light produced by interactions with weakly interacting massive particles, leading dark matter candidates. The detector will be constructed out of acrylic and use a spherical array of 266 photo-multiplier tubes (PMTs) to count photons produced by an event and will use properties of liquid argon to discriminate signals from background alpha and gamma events. There is currently a smaller prototype, with a cylindrical geometry and using two PMTs, in operation underground at SNOLAB an underground laboratory in eastern Canada. The goal of the prototype detector is to understand the sources of background signals in a detector of our design and to validate our method of distinguishing different types of background radiation. The work presented herein is a series of studies with the common goal of understanding the source of background signals, and improving the resolution and efficiency of the detector.

Olsen, Kevin S.

180

Efficient detection of an ultra-bright single-photon source using superconducting nanowire single-photon detectors  

NASA Astrophysics Data System (ADS)

We investigate the detection of a single-photon source using highly efficient superconducting nanowire single-photon detectors (SNSPDs) at telecom wavelengths. Both the single-photon source and the detectors are characterized in detail. At a pump power of 100 mW (400 mW), the measured coincidence counts can achieve 400 kcps (1.17 Mcps), which is the highest ever reported at telecom wavelengths to the best of our knowledge. The multi-pair contributions, the experimental and theoretical second order coherence functions, and the saturation property of SNSPD are analyzed in detail. The experimental data and theoretical analysis should be useful for the future experiments to detect ultra-bright down-conversion sources with high-efficiency detectors.

Jin, Rui-Bo; Fujiwara, Mikio; Yamashita, Taro; Miki, Shigehito; Terai, Hirotaka; Wang, Zhen; Wakui, Kentaro; Shimizu, Ryosuke; Sasaki, Masahide

2015-02-01

181

Calculation of Gamma Ray Efficiency and Response Function of a Germanium Detector by the Monte Carlo Method  

Microsoft Academic Search

An interactive Monte Carlo computer code with a relaxed geometry constraint was developed to perform gamma ray efficiency and response function calculations for an intrinsic germanium detector. The code accepts source geometries usually encountered in practice, such as a point isotropic source, a surface source, and a volume source. The code also accepts a beryllium cover on the front of

Bijaya Shrestha

1995-01-01

182

Charged Particle Induced Radiation damage of Germanium Detectors in Space: Two Mars Observer Gamma-Ray Detectors  

NASA Technical Reports Server (NTRS)

The Mars Observer Gamma-Ray Spectrometer (MO GRS) was designed to measure gamma-rays emitted by the Martian surface. This gamma-ray emission is induced by energetic cosmic-ray particles penetrating the Martian surface and producing many secondary particles and gamma rays. The MO GRS consisted of an high-purity germanium (HPGe) detector with a passive cooler. Since radiation damage due to permanent bombardment of energetic cosmic ray particles (with energies up to several GeV) was expected for the MO GRS HPGe crystal, studies on radiation damage effects of HPGe crystals were carried on earth. One of the HPGe crystals (paradoxically called FLIGHT) was similar to the MO GRS crystal. Both detectors, MO GRS and FLIGHT, contained closed-end coaxial n-type HPGe crystals and had the same geometrical dimensions (5.6 x 5.6 cm). Many other parameters, such as HV and operation temperature, differed in space and on earth, which made it somewhat difficult to directly compare the performance of both detector systems. But among other detectors, detector FLIGHT provided many useful data to better understand radiation damage effects.

Bruekner, J.; Koenen, M.; Evans, L. G.; Starr, R.; Bailey, S. H.; Boynton W. V.

1997-01-01

183

Efficient phase contrast imaging in STEM using a pixelated detector. Part 1: Experimental demonstration at atomic resolution.  

PubMed

We demonstrate a method to achieve high efficiency phase contrast imaging in aberration corrected scanning transmission electron microscopy (STEM) with a pixelated detector. The pixelated detector is used to record the Ronchigram as a function of probe position which is then analyzed with ptychography. Ptychography has previously been used to provide super-resolution beyond the diffraction limit of the optics, alongside numerically correcting for spherical aberration. Here we rely on a hardware aberration corrector to eliminate aberrations, but use the pixelated detector data set to utilize the largest possible volume of Fourier space to create high efficiency phase contrast images. The use of ptychography to diagnose the effects of chromatic aberration is also demonstrated. Finally, the four dimensional dataset is used to compare different bright field detector configurations from the same scan for a sample of bilayer graphene. Our method of high efficiency ptychography produces the clearest images, while annular bright field produces almost no contrast for an in-focus aberration-corrected probe. PMID:25458189

Pennycook, Timothy J; Lupini, Andrew R; Yang, Hao; Murfitt, Matthew F; Jones, Lewys; Nellist, Peter D

2015-04-01

184

Intrinsic detection efficiency of superconducting nanowire single photon detector in the modified hot spot model  

NASA Astrophysics Data System (ADS)

We theoretically study the dependence of the intrinsic detection efficiency (IDE) of a superconducting nanowire single photon detector on the applied current, I, and magnetic field, H. We find that the current, at which the resistive state appears in the superconducting film, depends on the position of the hot spot (a region with suppressed superconductivity around the place where the photon has been absorbed) with respect to the edges of the film. This circumstance leads to inevitable smooth dependence IDE(I) when IDE ˜ 0.05-1, even for a homogenous straight superconducting film and in the absence of fluctuations. For IDE ? 0.05, a much sharper current dependence comes from the fluctuation-assisted vortex entry to the hot spot, which is located near the edge of the film. We find that a weak magnetic field strongly affects IDE when the photon detection is connected with fluctuation-assisted vortex entry to the hot spot (IDE \\ll 1), and it weakly affects IDE when the photon detection is connected with the current-induced vortex nucleation in the film with the hot spot (IDE ˜ 0.05-1).

Zotova, A. N.; Vodolazov, D. Yu

2014-12-01

185

Charge Transfer Efficiency and Charge Injection in the HST/WFC3 UVIS Detectors  

NASA Astrophysics Data System (ADS)

Devices in low-earth orbit are particularly susceptible to the cumulative effects of radiation damage and the Hubble Space Telescope Wide Field Camera 3 (HST/WFC3) UVIS detectors, installed on HST in May 2009, are no exception. Such damage not only generates new hot pixels but also degrades the charge transfer efficiency (CTE), causing a loss in source flux due to charge traps as well as a systematic shift in the object centroid as the trapped charge is slowly released during readout. Based on an analysis of both internal and external monitoring data, we provide an overview of the consequences of the more than 2.5 years of radiation damage to the WFC3 CCD cameras. The advantages and disadvantages of available mitigation options are discussed, including use of the WFC3 charge injection capability, a mode now available to observers, and the status of an empirical correction similar to the one adopted for the HST Advanced Camera for Surveys (ACS).

Baggett, Sylvia M.; Noeske, K.; Anderson, J.; Biretta, J.; Borders, T.; Bushouse, H.; Khozhurina-Platais, V.; MacKenty, J.; Petro, L.; WFC3 Team

2012-01-01

186

High quantum efficiency megavoltage imaging with thick scintillator detectors for image guided radiation therapy  

NASA Astrophysics Data System (ADS)

In image guided radiation therapy (IGRT), imaging devices serve as guidance systems to aid patient set-up and tumor volume localization. Traditionally, 2-D megavoltage x-ray imagers, referred to as electronic portal imaging devices (EPIDs), have been used for planar target localization, and have recently been extended to perform 3-D volumetric reconstruction via cone-beam computed tomography (CBCT). However, current EPIDs utilize thin and inefficient phosphor screen detectors and are subsequently limited by poor soft tissue visualization, which limits their use for CBCT. Therefore, the use of thick scintillation media as megavoltage x-ray detectors for greater x-ray sensitivity and enhanced image quality has recently been of significant interest. In this research, two candidates for thick scintillators: CsI(Tl) and terbium doped scintillation glass were investigated in separate imaging configurations. In the first configuration, a thick scintillation crystal (TSC) consisting of a thick, monolithic slab of CsI(Tl) was coupled to a mirror-lens-camera system. The second configuration is based on a fiber-optic scintillation glass array (FOSGA), wherein the scintillation glass is drawn into long fiber-optic conduits, inserted into a grid-type housing constructed out of polymer-tungsten alloy, and coupled to an array of photodiodes for digital read-out. The imaging prototypes were characterized using theoretical studies and imaging measurements to obtain fundamental metrics of imaging performance. Spatial resolution was measured based on a modulation transfer function (MTF), noise was evaluated in terms of a noise power spectrum (NPS), and overall contrast was characterized in the form of detective quantum efficiency (DQE). The imaging studies were used to optimize the TSC and FOSGA imagers and propose prototype configurations for order-of-magnitude improvements in overall image quality. In addition, a fast and simple technique was developed to measure the MTF, NPS, and DQE metrics for clinical EPID and CBCT systems based on a novel adaptation of a traditional line-pair resolution bar-pattern. This research provides two significant benefits to radiotherapy: the characterization of a new generation of thick scintillator based megavoltage x-ray imagers for CBCT based IGRT, and the novel adaptation of fundamental imaging metrics from imaging research to routine clinical performance monitoring.

Gopal, Arun

187

Large Ge Detector Array (GEANIE) at LANSCE  

Microsoft Academic Search

The large scale array GEANIE consists of 20 escape suppressed HPGe detectors and 10 low energy photon spectrometers (LEPS). This array is assembled on the 20 meter flight path 60R at the Weapons Neutron Research (WNR) facility in Los Alamos National Laboratory. The LANSCE spallation source produces high intensity neutrons between 0 and 400 MeV in energy. This unique facility

D. E. Archer; L. A. Bernstein; J. A. Becker; K. Hauschild; R. O. Nelson; S. Wender

1996-01-01

188

Multimode fiber-coupled superconducting nanowire single-photon detector with 70% system efficiency at visible wavelength.  

PubMed

We report the development of the multimode fiber-coupled superconducting nanowire single-photon detector with high system detection efficiency at visible wavelength. The detector consists of a 10.5-nm-thick and 150-nm-wide NbN nanowire meander fabricated on a Si substrate with a multilayer dielectric mirror and a quarter wavelength cavity for obtaining high optical absorptance. The meander area was 35 µm in diameter and coupled with the GRIN-lensed multimode optical fiber with a core diameter of 50 µm. The system reached detection efficiency of 70% with dark count rate of 100 Hz at the wavelength of 635 nm, 3 dB roll-off response counting rate of 8.5 Mcps, and timing jitter of 76 ps. PMID:25321497

Liu, Dengkuan; Miki, Shigehito; Yamashita, Taro; You, Lixing; Wang, Zhen; Terai, Hirotaka

2014-09-01

189

Self-powered micro-structured solid state neutron detector with very low leakage current and high efficiency  

SciTech Connect

We report on the design, fabrication, and performance of solid-state neutron detector based on three-dimensional honeycomb-like silicon micro-structures. The fabricated detectors use boron filled deep holes with aspect ratio of over 12 and showed a very low leakage current density of {approx}7 Multiplication-Sign 10{sup -7} A/cm{sup 2} at -1 V for device sizes varying from 2 Multiplication-Sign 2 to 5 Multiplication-Sign 5 mm{sup 2}. A thermal neutron detection efficiency of 4.5% {+-} 0.5% with discrimination setting of 500 keV and gamma to neutron sensitivity of (1.1 {+-} 0.1) Multiplication-Sign 10{sup -5} for single layer was measured without external bias for these devices. Monte-Carlo simulation predicts a maximum efficiency of 45% for such devices filled with 95% enriched {sup 10}boron.

Dahal, R. [Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Huang, K. C.; LiCausi, N.; Lu, J.-Q.; Bhat, I. [Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Clinton, J.; Danon, Y. [Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

2012-06-11

190

Electron reconstruction and identification efficiency measurements with the ATLAS detector using the 2011 LHC proton-proton collision data  

NASA Astrophysics Data System (ADS)

Many of the interesting physics processes to be measured at the LHC have a signature involving one or more isolated electrons. The electron reconstruction and identification efficiencies of the ATLAS detector at the LHC have been evaluated using proton-proton collision data collected in 2011 at TeV and corresponding to an integrated luminosity of 4.7 fb. Tag-and-probe methods using events with leptonic decays of and bosons and mesons are employed to benchmark these performance parameters. The combination of all measurements results in identification efficiencies determined with an accuracy at the few per mil level for electron transverse energy greater than 30 GeV.

Aad, G.; Abajyan, T.; Abbott, B.; Abdallah, J.; Khalek, S. Abdel; Abdinov, O.; Aben, R.; Abi, B.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Acharya, B. S.; Adamczyk, L.; Adams, D. L.; Addy, T. N.; Adelman, J.; Adomeit, S.; Adye, T.; Agatonovic-Jovin, T.; Aguilar-Saavedra, J. A.; Agustoni, M.; Ahlen, S. P.; Ahmad, A.; Ahmadov, F.; Aielli, G.; Åkesson, T. P. A.; Akimoto, G.; Akimov, A. V.; Albert, J.; Albrand, S.; Verzini, M. J. Alconada; Aleksa, M.; Aleksandrov, I. N.; Alexa, C.; Alexander, G.; Alexandre, G.; Alexopoulos, T.; Alhroob, M.; Alimonti, G.; Alio, L.; Alison, J.; Allbrooke, B. M. M.; Allison, L. J.; Allport, P. P.; Allwood-Spiers, S. E.; Almond, J.; Aloisio, A.; Alon, R.; Alonso, A.; Alonso, F.; Alpigiani, C.; Altheimer, A.; Gonzalez, B. Alvarez; Alviggi, M. G.; Amako, K.; Coutinho, Y. Amaral; Amelung, C.; Amidei, D.; Ammosov, V. V.; Santos, S. P. Amor Dos; Amorim, A.; Amoroso, S.; Amram, N.; Amundsen, G.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, G.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Anduaga, X. S.; Angelidakis, S.; Anger, P.; Angerami, A.; Anghinolfi, F.; Anisenkov, A. V.; Anjos, N.; Annovi, A.; Antonaki, A.; Antonelli, M.; Antonov, A.; Antos, J.; Anulli, F.; Aoki, M.; Bella, L. Aperio; Apolle, R.; Arabidze, G.; Aracena, I.; Arai, Y.; Araque, J. P.; Arce, A. T. H.; Arguin, J.-F.; Argyropoulos, S.; Arik, M.; Armbruster, A. J.; Arnaez, O.; Arnal, V.; Arslan, O.; Artamonov, A.; Artoni, G.; Asai, S.; Asbah, N.; Ashkenazi, A.; Ask, S.; Åsman, B.; Asquith, L.; Assamagan, K.; Astalos, R.; Atkinson, M.; Atlay, N. B.; Auerbach, B.; Auge, E.; Augsten, K.; Aurousseau, M.; Avolio, G.; Azuelos, G.; Azuma, Y.; Baak, M. A.; Bacci, C.; Bach, A. M.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Mayes, J. Backus; Badescu, E.; Bagiacchi, P.; Bagnaia, P.; Bai, Y.; Bailey, D. C.; Bain, T.; Baines, J. T.; Baker, O. K.; Baker, S.; Balek, P.; Balli, F.; Banas, E.; Banerjee, Sw.; Banfi, D.; Bangert, A.; Bannoura, A. A. E.; Bansal, V.; Bansil, H. S.; Barak, L.; Baranov, S. P.; Barber, T.; Barberio, E. L.; Barberis, D.; Barbero, M.; Barillari, T.; Barisonzi, M.; Barklow, T.; Barlow, N.; Barnett, B. M.; Barnett, R. M.; Barnovska, Z.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barreiro, F.; Costa, J. Barreiro Guimarães da; Bartoldus, R.; Barton, A. E.; Bartos, P.; Bartsch, V.; Bassalat, A.; Basye, A.; Bates, R. L.; Batkova, L.; Batley, J. R.; Battistin, M.; Bauer, F.; Bawa, H. S.; Beau, T.; Beauchemin, P. H.; Beccherle, R.; Bechtle, P.; Beck, H. P.; Becker, K.; Becker, S.; Beckingham, M.; Becot, C.; Beddall, A. J.; Beddall, A.; Bedikian, S.; Bednyakov, V. A.; Bee, C. P.; Beemster, L. J.; Beermann, T. A.; Begel, M.; Behr, K.; Belanger-Champagne, C.; Bell, P. J.; Bell, W. H.; Bella, G.; Bellagamba, L.; Bellerive, A.; Bellomo, M.; Belloni, A.; Belotskiy, K.; Beltramello, O.; Benary, O.; Benchekroun, D.; Bendtz, K.; Benekos, N.; Benhammou, Y.; Noccioli, E. Benhar; Garcia, J. A. Benitez; Benjamin, D. P.; Bensinger, J. R.; Benslama, K.; Bentvelsen, S.; Berge, D.; Kuutmann, E. Bergeaas; Berger, N.; Berghaus, F.; Berglund, E.; Beringer, J.; Bernard, C.; Bernat, P.; Bernius, C.; Bernlochner, F. U.; Berry, T.; Berta, P.; Bertella, C.; Bertolucci, F.; Besana, M. I.; Besjes, G. J.; Bessidskaia, O.; Besson, N.; Betancourt, C.; Bethke, S.; Bhimji, W.; Bianchi, R. M.; Bianchini, L.; Bianco, M.; Biebel, O.; Bieniek, S. P.; Bierwagen, K.; Biesiada, J.; Biglietti, M.; De Mendizabal, J. Bilbao; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Black, C. W.; Black, J. E.; Black, K. M.; Blackburn, D.; Blair, R. E.; Blanchard, J.-B.; Blazek, T.; Bloch, I.; Blocker, C.; Blum, W.; Blumenschein, U.; Bobbink, G. J.; Bobrovnikov, V. S.; Bocchetta, S. S.; Bocci, A.; Boddy, C. R.; Boehler, M.; Boek, J.; Boek, T. T.; Bogaerts, J. A.; Bogdanchikov, A. G.; Bogouch, A.; Bohm, C.; Bohm, J.; Boisvert, V.; Bold, T.; Boldea, V.; Boldyrev, A. S.; Bolnet, N. M.; Bomben, M.; Bona, M.; Boonekamp, M.; Borisov, A.; Borissov, G.; Borri, M.; Borroni, S.; Bortfeldt, J.; Bortolotto, V.; Bos, K.; Boscherini, D.; Bosman, M.; Boterenbrood, H.; Boudreau, J.; Bouffard, J.; Bouhova-Thacker, E. V.; Boumediene, D.; Bourdarios, C.; Bousson, N.; Boutouil, S.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bozovic-Jelisavcic, I.; Bracinik, J.; Branchini, P.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Braun, H. M.; Brazzale, S. F.; Brelier, B.; Brendlinger, K.; Brennan, A. J.; Brenner, R.; Bressler, S.; Bristow, K.; Bristow, T. M.; Britton, D.; Brochu, F. M.; Brock, I.; Brock, R.; Bromberg, C.; Bronner, J.; Brooijmans, G.; Brooks, T.; Brooks, W. K.; Brosamer, J.; Brost, E.; Brown, G.; Brown, J.; Renstrom, P. A. Bruckman de; Bruncko, D.

2014-07-01

191

High efficiency and rapid response superconducting NbN nanowire single photon detector based on asymmetric split ring metamaterial  

SciTech Connect

With asymmetric split ring metamaterial periodically placed on top of the niobium nitride (NbN) nanowire meander, we theoretically propose a kind of metal-insulator-metallic metamaterial nanocavity to enhance absorbing efficiency and shorten response time of the superconducting NbN nanowire single photon detector (SNSPD) operating at wavelength of 1550?nm. Up to 99.6% of the energy is absorbed and 96.5% dissipated in the nanowire. Meanwhile, taking advantage of this high efficiency absorbing cavity, we implement a more sparse arrangement of the NbN nanowire of the filling factor 0.2, which significantly lessens the nanowire and crucially boosts the response time to be only 40% of reset time in previous evenly spaced meander design. Together with trapped mode resonance, a standing wave oscillation mechanism is presented to explain the high efficiency and broad bandwidth properties. To further demonstrate the advantages of the nanocavity, a four-pixel SNSPD on 10??m?×?10??m area is designed to further reduce 75% reset time while maintaining 70% absorbing efficiency. Utilizing the asymmetric split ring metamaterial, we show a higher efficiency and more rapid response SNSPD configuration to contribute to the development of single photon detectors.

Li, Guanhai; Chen, Xiaoshuang [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 200083 Shanghai (China); Wang, Shao-Wei, E-mail: wangshw@mail.sitp.ac.cn; Lu, Wei, E-mail: luwei@mail.sitp.ac.cn [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 200083 Shanghai (China); Shanghai Advanced Research Institute, Chinese Academy of Sciences, 201210 Shanghai (China)

2014-06-09

192

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

SciTech Connect

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.

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

1993-10-01

193

Using surface plasmons to enhance the speed and efficiency of superconducting nanowire single-photon detectors  

E-print Network

We report our design and fabrication of superconducting nanowire single-photon detectors integrated with gold plasmonic nanostructures, which can enhance the absorption of TM-polarized light, and can enlarge the effective ...

Hu, Xiaolong

194

Monte Carlo simulation of the BEGe detector response function for in vivo measurements of 241Am in the skull  

NASA Astrophysics Data System (ADS)

This paper reports on the procedure of the BEGe detector characterization for the Monte Carlo calibrations. A project is under way to improve the counting and operating capabilities of the Whole Body Counter (WBC) installed in SÚRO, v.v.i. (NRPI) Prague, Czech Republic. Possible emergency monitoring should mainly benefit from the rapid, safe and flexible operation of the WBC. The system of the WBC for the detection of low energy X and gamma radiation comprises four HPGe detectors intended for the routine, emergency, and research measurements of persons internally contaminated with low-energy photon emitters, mainly actinides. Among them, 241Am is the main subject of interest. A precise detection efficiency calibration of the detector is required for the measurement of activity in individual organs and tissues. The use of physical phantoms in the calibrations is often supplemented with the application of voxel phantoms and a Monte Carlo technique that are used for the calculation of the detector response function and the full energy peak efficiency. Both experimental and computational approaches have been used for the calibration of the BEGe (Broad Energy Germanium) detector. In this paper, the process of the Monte Carlo simulation of the detector response function and the peak efficiency calculation is described. Results of the simulations are provided in the paper and discussed.

Fantínová, K.; Fojtík, P.

2014-11-01

195

Characterization of one-dimensional position sensitive detectors with improved efficiency and position resolution for neutron spectrometers  

SciTech Connect

Development and characterization of one-dimentional (1D) position sensitive detectors (PSDs) with improved efficiency and position resolution for neutron scattering applications are reported. The PSDs are characterized for energy resolution, count rate capability, sensitivity, efficiency, position resolution, and uniformity of response over the sensitive length. The studies are carried out to verify the dependence of position resolution on detector geometry, electronic noise, and stopping power of the fill gas. One of the PSDs is mounted on the small angle neutron scattering spectrometer and spectra from CTAB micelle sample are recorded using 5.4 A neutrons. A gain of factors 1.1 and 1.2 is obtained compared to earlier in house made 1D PSD and LND-made 1D PSD, respectively. The diffraction patterns from standard vanadium, nickel, and silicon samples are recorded on a powder diffractometer using newly designed PSDs. Gain in efficiency obtained at shorter wavelength of 0.783 A is by a factor of 1.6. All high pressure PSDs show improvement in the position resolution by 2-3 mm. It is observed that 1D PSD filled with isobutane as stopping gas improves the gamma tolerance and position resolution at lower partial pressures as compared to Kr. It is advantageous to use two or more 36C-type PSDs stacked together. It is economic and gives better efficiency due to scanning more beam height.

Desai, S. S.; Shaikh, A. M. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

2007-02-15

196

Contribution of pair production process in full-energy peak efficiency calculation of semiconductor detectors for axial point sources with high-energy gamma-rays  

Microsoft Academic Search

Study has been made of the contribution of the pair production process in calculation of detector efficiency. Particular attention has been paid to positron annihilation in flight and subsequent scattering of the annihilation quanta in the detector material. A mathematical formula has been derived to directly calculate the liner attenuation coefficient of the full-energy peak (mup) for a Ge (Li)

Younis S. Selim; Mohamed A. Elzaher; Ahmed M. El-Katib; Mohamed M. Bassiouny

2007-01-01

197

Multielement CdZnTe detectors for high-efficiency, ambient-temperature gamma-ray spectroscopy  

SciTech Connect

CdZnTe is an attractive alternative to scintillator-based technology for ambient-temperature, gamma-ray spectroscopy. Large, single-element devices up to 3500 mm{sup 3} have been developed for gamma-ray spectroscopy and are now available commercially. Because CdZnTe is a wide band-gap semiconductor, it can operate over a wide range of ambient temperatures with minimal power consumption. Over this range, CdZnTe detectors routinely yield better overall performance for gamma-ray spectroscopy than scintillator detectors. Manufacturing issues and material electronic properties limit the maximum size of single-element CdZnTe detectors. The authors are investigating methods to combine CdZnTe detectors together to improve detection efficiency and overall performance of gamma-ray spectroscopy. The applications include the assay and identification of radioisotopes for nuclear material safeguards and nonproliferation (over the energy range 50 keV to 1 MeV), and the analysis of elemental composition for planetary science (over the energy range 1 MeV to 10 MeV). Design issues for the two energy ranges are summarized.

Prettyman, T.H.; Moss, C.E.; Sweet, M.R.; Ianakiev, K.; Reedy, R.C.; Li, J. [Los Alamos National Lab., NM (United States); Valentine, J.D. [Univ. of Cincinnati, OH (United States)

1998-12-31

198

Characterisation of a Si(Li) orthogonal-strip detector  

NASA Astrophysics Data System (ADS)

A Compton camera composed of an orthogonal-strip Si(Li) detector and an orthogonal-strip HPGe SmartPET detector is under investigation at the University of Liverpool. To optimise the performance of the system, it is essential to quantify the response of the detectors to gamma irradiation. Such measurements have previously been reported for the SmartPET detector and in this work we report on the experimental characterisation of the Si(Li) detector. Precision scans of the detector have been performed using a finely collimated 241Am gamma-ray source to determine the uniformity and charge collection properties of the detector.

Harkness, L. J.; Judson, D. S.; Boston, A. J.; Boston, H. C.; Cresswell, J. R.; Nolan, P. J.; Sweeney, A.; Beau, J.; Lampert, M.; Pirard, B.; Zuvic, M.

2013-10-01

199

Free-running InGaAs single photon detector with 1 dark count per second at 10% efficiency  

SciTech Connect

We present a free-running single photon detector for telecom wavelengths based on a negative feedback avalanche photodiode (NFAD). A dark count rate as low as 1?cps was obtained at a detection efficiency of 10%, with an afterpulse probability of 2.2% for 20??s of deadtime. This was achieved by using an active hold-off circuit and cooling the NFAD with a free-piston stirling cooler down to temperatures of ?110?°C. We integrated two detectors into a practical, 625?MHz clocked quantum key distribution system. Stable, real-time key distribution in the presence of 30?dB channel loss was possible, yielding a secret key rate of 350?bps.

Korzh, B., E-mail: Boris.Korzh@unige.ch; Walenta, N.; Lunghi, T.; Gisin, N.; Zbinden, H. [Group of Applied Physics, University of Geneva, Chemin de Pinchat 22, CH-1211 Geneva 4 (Switzerland)

2014-02-24

200

Improvement in the low energy collection efficiency of Si(Li) X-ray detectors  

NASA Astrophysics Data System (ADS)

Soft X-ray beam-line applications are of fundamental importance to material research, and commonly employ high-resolution Si(Li) detectors for energy dispersive spectroscopy. However, the measurement of X-rays below 1 keV is compromised by absorption in the material layers in front of the active crystal and a dead layer at the crystal surface. Various Schottky barrier type contacts were investigated resulting in a 40% reduction of the dead-layer thickness and a factor of two increased sensitivity at carbon K ? compared to the standard Si(Li) detector. Si(Li) detectors were tested on the U7A soft X-ray beam-line at the National Synchrotron Light Source and on a scanning electron microscope (SEM).

Cox, Christopher E.; Fischer, Daniel A.; Schwarz, Willi G.; Song, Yongwei

2005-12-01

201

Status and Performance of an AGATA asymmetric detector  

NASA Astrophysics Data System (ADS)

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 (AGATA) [1] and the USA (GRETA/GRETINA) [2] to build gamma-ray tracking spectrometers. This paper discusses the performance of the first AGATA (Advanced GAmma Tracking Array) 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.

Boston, A. J.; Dimmock, M. R.; Unsworth, C.; Boston, H. C.; Cooper, R. J.; Grint, A. N.; Harkness, L. J.; Lazarus, I. H.; Jones, M.; Nolan, P. J.; Oxley, D. C.; Simpson, J.; Slee, M.

2009-03-01

202

Near-optimal and computationally efficient detectors for weak and sparse graph-structured patterns  

E-print Network

hand, the combina- torial nature of this class renders traditional detectors such as GLRT (aka scan in modern applications ranging from de- tecting contamination or seismic activity by sensor networks, virus disconnected) activated vertices with size |C| = c 1 and cut-size |C| := |(i, j) E : i C, j C| less than

Gordon, Geoffrey J.

203

The effects of detector material and structure on PET spatial resolution and efficiency  

Microsoft Academic Search

Many annihilation photons undergo one or more Compton interactions in PET (positron emission tomography) scintillation crystals before being absorbed photoelectrically or escaping from the crystal. Only the site of the first interaction is on the original trajectory and expresses the exact localization of the annihilation. In larger crystals or block detectors the light from all scintillations appears to originate from

C. J. Thompson

1990-01-01

204

Performance of High Efficiency CdZnTe Gamma-Ray Detectors for Planetary Missions  

Microsoft Academic Search

Results from large-volume CdZnTe semiconductor detectors for ambient-temperature gamma-ray spectroscopy are presented. Our new multi-element-array design is a good low-mass and low-power candidate for elemental mapping on future planetary missions.

C. E. Moss; K. D. Ianakiev; T. H. Prettyman; R. C. Reedy; M. K. Smith; M. R. Sweet; J. D. Valentine

1999-01-01

205

Simulation study comparing high-purity germanium and cadmium zinc telluride detectors for breast imaging  

NASA Astrophysics Data System (ADS)

We conducted simulations to compare the potential imaging performance for breast cancer detection with High-Purity Germanium (HPGe) and Cadmium Zinc Telluride (CZT) systems with 1% and 3.8% energy resolution at 140?keV, respectively. Using the Monte Carlo N-Particle (MCNP5) simulation package, we modelled both 5?mm-thick CZT and 10?mm-thick HPGe detectors with the same parallel-hole collimator for the imaging of a breast/torso phantom. Simulated energy spectra were generated, and planar images were created for various energy windows around the 140?keV photopeak. Relative sensitivity and scatter and the torso fractions were calculated along with tumour contrast and signal-to-noise ratios (SNR). Simulations showed that utilizing a ±1.25% energy window with an HPGe system better suppressed torso background and small-angle scattered photons than a comparable CZT system using a ?5%/+10% energy window. Both systems provided statistically similar contrast and SNR, with HPGe providing higher relative sensitivity. Lowering the counts of HPGe images to match CZT count density still yielded equivalent contrast between HPGe and CZT. Thus, an HPGe system may provide equivalent breast imaging capability at lower injected radioactivity levels when acquiring for equal imaging time.

Campbell, D. L.; Peterson, T. E.

2014-11-01

206

Improving photon detector efficiency using a high-fidelity optical CNOT gate  

E-print Network

A significant problem for optical quantum computing is inefficient, or inaccurate photo-detectors. It is possible to use CNOT gates to improve a detector by making a large cat state then measuring every qubit in that state. In this paper we develop a code that compares five different schemes for making multiple measurements, some of which are capable of detecting loss and some of which are not. We explore how each of these schemes performs in the presence of different errors, and derive a formula to find at what probability of qubit loss is it worth detecting loss, and at what probability does this just lead to further errors than the loss introduces.

Katherine L Brown; Robinjeet Singh; Joshua H. Mendez Plaskus; Hanna E. Broadus; Jonathan P. Dowling

2015-01-07

207

Enhanced quantum efficiency of high-purity silicon imaging detectors by ultralow temperature surface modification using Sb doping  

NASA Technical Reports Server (NTRS)

A low temperature process for Sb doping of silicon has been developed as a backsurface treatment for high-purity n-type imaging detectors. Molecular beam epitaxy (MBE) is used to achieve very high dopant incorporation in a thin, surface-confined layer. The growth temperature is kept below 450 (deg)C for compatibility with Al-metallized devices. Imaging with MBE-modified 1kx1k charge coupled devices (CCDs) operated in full depletion has been demonstrated. Dark current is comparable to the state-of-the-art process, which requires a high temperature step. Quantum efficiency is improved, especially in the UV, for thin doped layers placed closer to the backsurface. Near 100% internal quantum efficiency has been demonstrated in the ultraviolet for a CCD with a 1.5 nm silicon cap layer.

Blacksberg, Jordana; Hoenk, Michael E.; Elliott, S. Tom; Holland, Stephen E.; Nikzad, Shouleh

2005-01-01

208

Electron reconstruction and identification efficiency measurements with the ATLAS detector using the 2011 LHC proton-proton collision data  

E-print Network

Many of the interesting physics processes to be measured at the LHC have a signature involving one or more isolated electrons. The electron reconstruction and identification efficiencies of the ATLAS detector at the LHC have been evaluated using proton-proton collision data collected in 2011 at sqrt(s) = 7 TeV and corresponding to an integrated luminosity of 4.7/fb. Tag-and-probe methods using events with leptonic decays of W and Z bosons and J/psi mesons are employed to benchmark these performance parameters. The combination of all measurements results in identification efficiencies determined with an accuracy at the few per mil level for electron transverse energy greater than 30 GeV.

ATLAS Collaboration

2014-07-22

209

High-efficiency scintillation detector for combined detection of thermal and fast neutrons and gamma radiation  

DOEpatents

A scintillation based radiation detector for the combined detection of thermal neutrons, high-energy neutrons and gamma rays in a single detecting unit. The detector consists of a pair of scintillators sandwiched together and optically coupled to the light sensitive face of a photomultiplier tube. A light tight radiation pervious housing is disposed about the scintillators and a portion of the photomultiplier tube to hold the arrangement in assembly and provides a radiation window adjacent the outer scintillator through which the radiation to be detected enters the detector. The outer scintillator is formed of a material in which scintillations are produced by thermal-neutrons and the inner scintillator is formed of a material in which scintillations are produced by high-energy neutrons and gamma rays. The light pulses produced by events detected in both scintillators are coupled to the photomultiplier tube which produces a current pulse in response to each detected event. These current pulses may be processed in a conventional manner to produce a count rate output indicative of the total detected radiation event count rate. Pulse discrimination techniques may be used to distinguish the different radiations and their energy distribution.

Chiles, M.M.; Mihalczo, J.T.; Blakeman, E.D.

1987-02-27

210

High-efficiency scintillation detector for combined of thermal and fast neutrons and gamma radiation  

DOEpatents

A scintillation based radiation detector for the combined detection of thermal neutrons, high-energy neutrons and gamma rays in a single detecting unit. The detector consists of a pair of scintillators sandwiched together and optically coupled to the light sensitive face of a photomultiplier tube. A light tight radiation pervious housing is disposed about the scintillators and a portion of the photomultiplier tube to hold the arrangement in assembly and provides a radiation window adjacent the outer scintillator through which the radiation to be detected enters the detector. The outer scintillator is formed of a material in which scintillations are produced by thermal-neutrons and the inner scintillator is formed of a material in which scintillations are produced by high-energy neutrons and gamma rays. The light pulses produced by events detected in both scintillators are coupled to the photomultiplier tube which produces a current pulse in response to each detected event. These current pulses may be processed in a conventional manner to produce a count rate output indicative of the total detected radiation even count rate. Pulse discrimination techniques may be used to distinguish the different radiations and their energy distribution.

Chiles, Marion M. (Knoxville, TN); Mihalczo, John T. (Oak Ridge, TN); Blakeman, Edward D. (Oak Ridge, TN)

1989-01-01

211

First demonstration of plasmonic GaN quantum cascade detectors with enhanced efficiency at normal incidence.  

PubMed

We have designed, fabricated and measured the first plasmon-assisted normal incidence GaN/AlN quantum cascade detector (QCD) making use of the surface plasmon resonance of a two-dimensional nanohole Au array integrated on top of the detector absorption region. The spectral response of the detector at room temperature is peaked at the plasmon resonance of 1.82 ?m. We show that the presence of the nanohole array induces an absolute enhancement of the responsivity by a factor of ~30 over that of the bare device at normal incidence and by a factor of 3 with respect to illumination by the 45° polished side facet. We show that this significant improvement arises from two phenomena, namely, the polarization rotation of the impinging light from tangential to normal induced by the plasmonic structure and from the enhancement of the absorption cross-section per quantum well due to the near-field optical intensity of the plasmonic wave. PMID:25321307

Pesach, Asaf; Sakr, Salam; Giraud, Etienne; Sorias, Ofir; Gal, Lior; Tchernycheva, Maria; Orenstein, Meir; Grandjean, Nicolas; Julien, Francois H; Bahir, Gad

2014-08-25

212

Solar Panel Energetic Efficiency Optimization Method, based on an Specific Detector and Orientation Microsystem  

Microsoft Academic Search

The increase of the solar cells efficiency implies high technological and scientific efforts. A significant efficiency increase of the photovoltaic panels can be also obtained by optimal exposure of the panels to the sunlight, using automatic solar trackers. For wide scale use of these control systems, it is very important to find low cost and reliable solutions. In the current

O. Oltu; P. L. Milea; M. Dragulinescu; E. Franti

2007-01-01

213

TECHNICAL DESIGN NOTE: Monte Carlo calculation for the geometrical efficiency of a multi-detector system for heavy ion reaction products  

NASA Astrophysics Data System (ADS)

The Monte Carlo method is employed to calculate the geometrical efficiency of a multi-detector system for fragments produced in heavy ion reactions. This efficiency is defined as a quotient of the number of fragments intercepted by the system and the total number of fragments emitted by the fissioning nucleus in all directions. The multi-detector system consists of six parallel-plate avalanche counters in a hexagonal configuration around the target. Its geometrical efficiency was calculated with respect to the 36Ar + 238U reaction at a 7 MeV/u projectile energy.

Savovi?, Svetislav; Djordjevich, Alexandar; Joki?, Stevan

2010-08-01

214

Comparison of two methods for high purity germanium detector efficiency calibration for charcoal canister radon measurement.  

PubMed

The charcoal canister method of radon measurement according to US Environment Protection Agency protocol 520/5-87-005 is widely used for screening. This method is based on radon adsorption on coal and measurement of gamma radiation of radon daughters. For the purpose of gamma spectrometry, appropriate efficiency calibration of the measuring system must be performed. The most usual method of calibration is using standard canister, a sealed canister with the same matrix and geometry as the canisters used for measurements, but with the known activity of radon. In the absence of standard canister, a different method of efficiency calibration has to be implemented. This study presents the results of efficiency calibration using the EFFTRAN efficiency transfer software. Efficiency was calculated using a soil matrix cylindrical secondary reference material as a starting point. Calculated efficiency is then compared with the one obtained using standard canister and applied to a realistic measurement in order to evaluate the results of the efficiency transfer. PMID:25377751

Nikolic, J; Pantelic, G; Zivanovic, M; Rajacic, M; Todorovic, D

2014-11-01

215

Systematic Effects in Pulse Shape Analysis of HPGe Detector Signals for Neutrinoless Double-Beta Decay  

Microsoft Academic Search

Pulse shape analysis is an important background reduction and signal\\u000aidentification technique for next generation of neutrinoless double-beta decay\\u000aexperiments examining 76Ge. We present a study of the systematic uncertainties\\u000ain one such parametric pulse-shape analysis technique for separating multi-site\\u000abackgrounds from single-site signal events. We examined systematic\\u000auncertainties for events in full-energy gamma peaks (predominantly multi-site),\\u000adouble escape peaks

Victor M Gehman; Steven R Elliott; Dongming Mei

2009-01-01

216

New fission mode of the {sup 252}Cf spontaneous fission obtained with modern HPGE detectors  

SciTech Connect

The data of Independent yields of secondary fission fragment pairs (emerging after prompt neutron emission from primary fragment pairs) obtained by detecting coincidences between {gamma} rays following the spontaneous fission of {sup 252}Cf have been expanded. Our approach to estimate characteristics of the primary fragments pairs (mass and excitation energy distributions) by unfolding the yields of secondary fragment pairs is discussed. Mew model parameters were introduced and results are presented here. The new results confirmed our old assumption that in case of Mo-Ba charge split the two fission modes differing with average total kinetic energy on {approx}36 MeV are realized.

Daniel, A. V.; Ter-Akopian, G. M.; Oganessian, Yu. Ts.; Popeko, G. S. [Flerov Laboratory of Nuclear Reactions, JINR, Dubna 141980 (Russian Federation); Hamilton, J. H.; Kormicki, J.; Ramayya, A. V.; Babu, B. R. S.; Ginter, T.; Zhu, S. J. [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States); Ma, W.-C. [Department of Physics, Mississippi State University, Mississippi State, Mississippi 39762 (United States); Rasmussen, J.; Stoyer, M. A.; Lee, I. Y.; Asztalos, S.; Chu, S. Y.; Gregorich, K. E.; Macchiavelli, A. O.; Mohar, M. F.; Prussin, S. G. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] (and others)

1998-02-15

217

New fission mode of the {sup 252}Cf spontaneous fission obtained with modern HPGE detectors  

SciTech Connect

The data of Independent yields of secondary fission fragment pairs (emerging after prompt neutron emission from primary fragment pairs) obtained by detecting coincidences between {gamma} rays following the spontaneous fission of {sup 252}Cf have been expanded. Our approach to estimate characteristics of the primary fragments pairs (mass and excitation energy distributions) by unfolding the yields of secondary fragment pairs is discussed. Mew model parameters were introduced and results are presented here. The new results confirmed our old assumption that in case of Mo-Ba charge split the two fission modes differing with average total kinetic energy {l_angle}TKE{r_angle} on {approximately}36 MeV are realized. {copyright} {ital 1998 American Institute of Physics.}

Daniel, A.V.; Ter-Akopian, G.M.; Oganessian, Y.T.; Popeko, G.S. [Flerov Laboratory of Nuclear Reactions, JINR, Dubna 141980 (Russia); Hamilton, J.H.; Kormicki, J.; Ramayya, A.V.; Babu, B.R.; Ginter, T.; Zhu, S.J. [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States); Ma, W. [Department of Physics, Mississippi State University, Mississippi State, Mississippi 39762 (United States); Rasmussen, J.; Stoyer, M.A.; Lee, I.Y.; Asztalos, S.; Chu, S.Y.; Gregorich, K.E.; Macchiavelli, A.O.; Mohar, M.F.; Prussin, S.G. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kliman, J.; Morhac, M. [Institute of Physics, Slovak Academy of Sciences, Bratislava (Slovak Republic); Cole, J.D.; Aryaeinejad, R.; Dardenne, Y.K.; Driger, M. [Idaho National Engineering Laboratory, Idaho Falls, Idaho 83415 (United States)

1998-02-01

218

Search for rare nuclear decays with HPGe detectors at the STELLA facility of the LNGS  

SciTech Connect

Results on the search for rare nuclear decays with the ultra low background facility STELLA at the LNGS using gamma ray spectrometry are presented. In particular, the best T{sub 1/2} limits were obtained for double beta processes in {sup 96}Ru and {sup 104}Ru. Several isotopes, which potentially decay through different 2? channels, including also possible resonant double electron captures, were investigated for the first time ({sup 156}Dy, {sup 158}Dy, {sup 184}Os, {sup 192}Os, {sup 190}Pt, {sup 198}Pt). Search for resonant absorption of solar {sup 7}Li axions in a LiF crystal gave the best limit for the mass of {sup 7}Li axions (< 8.6 keV). Rare alpha decay of {sup 190}Pt to the first excited level of {sup 186}Os(E{sub exc}?=?137.2keV) was observed for the first time.

Belli, P.; Di Marco, A. [INFN, Sezione di Roma Tor Vergata, Rome (Italy); Bernabei, R.; D'Angelo, S. [INFN, Sezione di Roma Tor Vergata, Rome, Italy and Dipartimento di Fisica, Università di Roma Tor Vergata, Rome (Italy); Cappella, F.; D'Angelo, A.; Incicchitti, A. [INFN, Sezione di Roma La Sapienza, Rome, Italy and Dipartimento di Fisica, Università di Roma La Sapienza, Rome (Italy); Cerulli, R.; Di Vacri, M. L.; Laubenstein, M.; Nisi, S. [INFN, Laboratori Nazionali del Gran Sasso, Assergi (AQ) (Italy); Danevich, F. A.; Kobychev, V. V.; Poda, D. V.; Tretyak, V. I. [Institute for Nuclear Research, Kyiv (Ukraine); Kovtun, G. P.; Kovtun, N. G.; Shcherban, A. P.; Solopikhin, D. A. [Kharkiv Institute of Physics and Technology, Kharkiv (Ukraine); Polischuk, O. G. [INFN, Sezione di Roma La Sapienza, Rome, Italy and Institute for Nuclear Research, Kyiv (Ukraine); and others

2013-12-30

219

A low-energy HPGE detector dedicated to radioactivity measurements far below environmental levels  

Microsoft Academic Search

Successive background reduction factors of a low-background high-purity semi-planar Germanium detection system, N type, were achieved with various shielding conditions, at ground level and underground locations. The optimal working conditions, achieved at a depth of 500 m water equivalent (m w.e.) lead to a background reduction factor of about 100 in the energy region from 5 to 1000 keV in

D. Mouchel; R. Wordel

1996-01-01

220

Spatial resolution and efficiency of microchannel plate detectors with neutron converter films  

NASA Astrophysics Data System (ADS)

An investigation into the potential neutron detection efficiency gains that could be made to microchannel plates (MCPs) has been conducted by a GEANT4 simulation. Thin-film neutron converters are coupled to the upstream-side of the MCP. MCPs with and without pre-existing neutron sensitivity were examined. A study into potential film materials favors a Gd2O3 converter film utilized in thin-film and pillar geometries for straight-channel MCPs. The objective was to increase thermal neutron detection efficiency without sacrificing the spatial resolution of the system by studying (1) the balance between capture efficiency and charged particle product production and range to optimize detection efficiency, and (2) the extent of radial straggling that the reaction products undergo as they are transmitted through the neutron converter and MCP, which affects spatial resolution. Our investigation reveals that an increase in efficiency of 9.9% can be achieved for an MCP without preexisting neutron sensitivity using a film geometry neutron converter of 4-?m thickness. An increase in efficiency of 4.3% can be achieved for a neutron-sensitive MCP using a pillar-type converter of 4-?m thickness. Degradation of spatial resolution is not significant for either film or pillar geometries with thicknesses in the range 0.5-10 ?m.

Cazalas, Edward; Trivelpiece, Cory; Jovanovic, Igor

2014-12-01

221

Proton-induced radiation damage in germanium detectors  

NASA Technical Reports Server (NTRS)

High-purity germanium (HPGe) detectors will be used in future space missions for gamma-ray measurements and will be subject to interactions with energetic particles. To simulate this process, several large-volume n-type HPGe detectors were incrementally exposed to a particle fluence of up to 10 to the 8th protons/sq cm (proton energy: 1.5 GeV) at different operating temperatures (90 to 120 K) to induce radiation damage. Basic scientific and engineering data on detector performance were collected. During the incremental irradiation, the peak shape produced by the detectors showed a significant change from a Gaussian shape to a broad complex structure. After the irradiation, all detectors were thoroughly characterized by measuring many parameters. To remove the accumulated radiation damage, the detectors were stepwise-annealed at temperatures below 110 C, while kept in their specially designed cryostats. This study shows that n-type HPGe detectors can be used in charged-particle environments as high-energy resolution devices until a certain level of radiation damage is accumulated and that the damage can be removed at moderate annealing temperatures and the detector returned to operating condition.

Brueckner, J.; Koerfer, M.; Waenke, H.; Schroeder, A. N. F.; Filges, D.; Dragovitsch, P.; Englert, P. A. J.; Starr, R.; Trombka, J. I.

1991-01-01

222

Active noise canceling system for mechanically cooled germanium radiation detectors  

DOEpatents

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.

Nelson, Karl Einar; Burks, Morgan T

2014-04-22

223

Calculation of total counting efficiency of a NaI(Tl) detector by hybrid Monte-Carlo method for point and disk sources  

Microsoft Academic Search

This paper presents results on the total gamma counting efficiency of a NaI(Tl) detector from point and disk sources. The directions of photons emitted from the source were determined by Monte-Carlo techniques and the photon path lengths in the detector were determined by analytic equations depending on photon directions. This is called the hybrid Monte-Carlo method where analytical expressions are

S. Yalcin; O. Gurler; G. Kaynak; O. Gundogdu

2007-01-01

224

Analysis of factors affecting the estimation of detective quantum efficiency of digital X-ray detectors within high and low spatial frequency ranges  

Microsoft Academic Search

After harmonizing the corresponding international standard and introduction of GOST R IEC 62220?1?06, there is an opportunity to estimate the general character? istic of image quality in digital Xray detectors—detective quantum efficiency (DQE). DQE is a function of spatial frequency in the radiation dose detector plane. The func? tion should be measured using standard monitoring sys? tems and methods (2).

M. I. Zelikman; S. P. Kabanov; S. A. Kruchinin; D. P. Lobov

2007-01-01

225

Approaching the Ultimate Limits of Communication Efficiency with a Photon-Counting Detector  

NASA Technical Reports Server (NTRS)

Coherent states achieve the Holevo capacity of a pure-loss channel when paired with an optimal measurement, but a physical realization of this measurement is as of yet unknown, and it is also likely to be of high complexity. In this paper, we focus on the photon-counting measurement and study the photon and dimensional efficiencies attainable with modulations over classical- and nonclassical-state alphabets. We first review the state-of-the-art coherent on-off-keying (OOK) with a photoncounting measurement, illustrating its asymptotic inefficiency relative to the Holevo limit. We show that a commonly made Poisson approximation in thermal noise leads to unbounded photon information efficiencies, violating the conjectured Holevo limit. We analyze two binary-modulation architectures that improve upon the dimensional versus photon efficiency tradeoff achievable with conventional OOK. We show that at high photon efficiency these architectures achieve an efficiency tradeoff that differs from the best possible tradeoff--determined by the Holevo capacity--by only a constant factor. The first architecture we analyze is a coherent-state transmitter that relies on feedback from the receiver to control the transmitted energy. The second architecture uses a single-photon number-state source.

Erkmen, Baris; Moision, Bruce; Dolinar, Samuel J.; Birnbaum, Kevin M.; Divsalar, Dariush

2012-01-01

226

GEANT4 calibration of gamma spectrometry efficiency for measurements of airborne radioactivity on filter paper.  

PubMed

A simple method of efficiency calibration for gamma spectrometry was performed. This method, which focused on measuring airborne radioactivity collected on filter paper, was based on Monte Carlo simulations using the toolkit GEANT4. Experimentally, the efficiency values of an HPGe detector were calculated for a multi-gamma disk source. These efficiency values were compared to their counterparts produced by a computer code that simulated experimental conditions. Such comparison revealed biases of 24, 10, 1, 3, 7, and 3% for the radionuclides (photon energies in keV) of Ce (166), Sn (392), Cs (662), Co (1,173), Co (1,333), and Y (1,836), respectively. The output of the simulation code was in acceptable agreement with the experimental findings, thus validating the proposed method. PMID:25271933

Alrefae, Tareq

2014-11-01

227

Experimental investigation of ?-ray attenuation in Jordanian building materials using HPGe-spectrometer  

Microsoft Academic Search

The capabilities of some building materials used in Jordan to attenuate gamma radiation were tested. Measurements of the attenuation coefficients of limestone, bricks and concrete have been carried out using a HPGe-spectrometer. Narrow beam technique was used, with a multiple gamma radiation source of different energy lines. Results indicate that variations in the attenuation coefficient for all limestone samples, at

Mohammad I. Awadallah; Mousa M. A. Imran

2007-01-01

228

Improving photon detector efficiency using a high-fidelity optical controlled-not gate  

NASA Astrophysics Data System (ADS)

A significant problem for optical quantum computing is inefficient or inaccurate photodetectors. It is possible to use controlled-not (cnot) gates to improve a detector by making a large cat state, then measuring every qubit in that state. In this paper we develop a code that compares five different schemes for making multiple measurements, some of which are capable of detecting loss and some of which are not. We explore how each of these schemes performs in the presence of different errors, and derive a formula to find at what probability of qubit loss it is worth detecting loss, and at what probability does this just lead to further errors than the loss introduces.

Brown, Katherine L.; Singh, Robinjeet; Plaskus, Joshua H. Mendez; Broadus, Hanna E.; Dowling, Jonathan P.

2015-02-01

229

High quantum efficiency and low dark count rate in multi-layer superconducting nanowire single-photon detectors  

SciTech Connect

In this paper, we theoretically show that a multi-layer superconducting nanowire single-photon detector (SNSPD) is capable of approaching characteristics of an ideal SNSPD in terms of the quantum efficiency, dark count, and band-width. A multi-layer structure improves the performance in two ways. First, the potential barrier for thermally activated vortex crossing, which is the major source of dark counts and the reduction of the critical current in SNSPDs is elevated. In a multi-layer SNSPD, a vortex is made of 2D-pancake vortices that form a stack. It will be shown that the stack of pancake vortices effectively experiences a larger potential barrier compared to a vortex in a single-layer SNSPD. This leads to an increase in the experimental critical current as well as significant decrease in the dark count rate. In consequence, an increase in the quantum efficiency for photons of the same energy or an increase in the sensitivity to photons of lower energy is achieved. Second, a multi-layer structure improves the efficiency of single-photon absorption by increasing the effective optical thickness without compromising the single-photon sensitivity.

Jafari Salim, A., E-mail: ajafaris@uwaterloo.ca; Eftekharian, A. [Institute for Quantum Computing, Waterloo, Ontario N2L 3G1 (Canada); University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Hamed Majedi, A., E-mail: ahmajedi@uwaterloo.ca [Institute for Quantum Computing, Waterloo, Ontario N2L 3G1 (Canada); University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Harvard University, Cambridge, Massachusetts 02138 (United States); Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5 (Canada)

2014-02-07

230

Carbon-based coatings for thermal detectors: laser damage and thermal efficiency  

Microsoft Academic Search

The laser damage threshold and absorption efficiency of a variety of carbon based thermal coatings for laser power and energy measurements have been investigated. Carbon based paint, carbon fibers, as well as single wall carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs), were applied to a water cooled copper substrate. The heating of the water was measured to determine power

Krishna Ramadurai; Laurence Lewis; Chris Cromer; Roop L. Mahajan; Katherine E. Hurst; John H. Lehman

2007-01-01

231

An Efficient Detector for STBC-VBLAST Space-Time Code for MIMO Wireless Communications  

Microsoft Academic Search

Hybrid MIMO communication systems are defined as a combination of architectures designed to achieve both multiplexing gain (such as VBLAST), and diversity gain, (such as STBC) such that transmission schemes that have both high spectral efficiency and link reliability can be developed.In this paper we introduce a new way to represent hybrid systems, in which the detection process is carried

J. Cortez; M. Bazdresch; A. Garcia; J. M. Campoy; A. Pizarro

2009-01-01

232

decay and conventional radioactive sources to determine efficiency of semiconductor detectors  

E-print Network

background4, 8 under the main peaks, which result from the photoelectric effect. The energy efficiency is entirely based on the knowledge of photon-matter processes, i.e., mainly the photoelectric effect and the Compton scattering, and allows to reach a precision of a few % in absolute X-ray yield

233

The detective quantum efficiency of photon-counting x-ray detectors using cascaded-systems analyses  

SciTech Connect

Purpose: Single-photon counting (SPC) x-ray imaging has the potential to improve image quality and enable new advanced energy-dependent methods. The purpose of this study is to extend cascaded-systems analyses (CSA) to the description of image quality and the detective quantum efficiency (DQE) of SPC systems. Methods: Point-process theory is used to develop a method of propagating the mean signal and Wiener noise-power spectrum through a thresholding stage (required to identify x-ray interaction events). The new transfer relationships are used to describe the zero-frequency DQE of a hypothetical SPC detector including the effects of stochastic conversion of incident photons to secondary quanta, secondary quantum sinks, additive noise, and threshold level. Theoretical results are compared with Monte Carlo calculations assuming the same detector model. Results: Under certain conditions, the CSA approach can be applied to SPC systems with the additional requirement of propagating the probability density function describing the total number of image-forming quanta through each stage of a cascaded model. Theoretical results including DQE show excellent agreement with Monte Carlo calculations under all conditions considered. Conclusions: Application of the CSA method shows that false counts due to additive electronic noise results in both a nonlinear image signal and increased image noise. There is a window of allowable threshold values to achieve a high DQE that depends on conversion gain, secondary quantum sinks, and additive noise.

Tanguay, Jesse [Robarts Research Institute and Department of Medical Biophysics, Western University, London, Ontario N6A 5C1 (Canada); Yun, Seungman [Biomedical Engineering Program, Western University, London, Ontario N6A 5C1 (Canada); School of Mechanical Engineering, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Kim, Ho Kyung [School of Mechanical Engineering, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Cunningham, Ian A. [Robarts Research Institute, Department of Medical Biophysics, and Biomedical Engineering Program, Western University, London, Ontario N6A 5C1 (Canada)

2013-04-15

234

Efficient luminescent down-shifting detectors based on colloidal quantum dots for dual-band detection applications.  

PubMed

A colloidal quantum dot (QD) luminescent down-shifting (LDS) layer is used to sensitize an InGaAs short wavelength infrared photodetector to the near UV spectral band. An average improvement in the external quantum efficiency (EQE) from 1.8% to 21% across the near UV is realized using an LDS layer consisting of PbS/CdS core/shell QDs embedded in PMMA. A simple model is used to fit the experimental EQE data. A UV sensitive InGaAs imaging array is demonstrated and the effect of the LDS layer on the optical resolution is calculated. The bandwidth of the LDS detector under UV illumination is characterized and shown to be determined by the photoluminescence lifetime of the QDs. PMID:21591692

Geyer, Scott M; Scherer, Jennifer M; Moloto, Nosipho; Jaworski, Frank B; Bawendi, Moungi G

2011-07-26

235

New measurement of the Fano factor of mercuric iodide. [astronomical x-ray detector charge collection efficiency  

NASA Technical Reports Server (NTRS)

It is pointed out that mercuric iodide (HgI2) shows great promise as a high-resolution X-ray detector for use in X-ray astronomy. Development of mercuric iodide for astronomical work has required investigation of the temperature dependence of the HgI2 crystal parameters such as leakage current, resolution, and mobility of the charge carriers. The first studies in connection with these investigations have led to a new value of the Fano factor of 0.19 + or - 0.03. The best value previously reported was 0.27 measured at room temperature. The new upper limit of 0.19 for the HgI2 Fano factor was determined by cooling the HgI2 crystal and preamp to -20 C. It is concluded that room-temperature energy resolution of HgI2 is not limited by charge generation statistics but rather by collection efficiency.

Ricker, G. R.; Vallerga, J. V.; Dabrowski, A. J.; Iwanczyk, J. S.; Entine, G.

1982-01-01

236

The effect of the displacement damage on the Charge Collection Efficiency in Silicon Drift Detectors for the LOFT satellite  

E-print Network

The technology of Silicon Drift Detectors (SDDs) has been selected for the two instruments aboard the Large Observatory For X-ray Timing (LOFT) space mission. LOFT underwent a three year long assessment phase as candidate for the M3 launch opportunity within the "Cosmic Vision 2015 -- 2025" long-term science plan of the European Space Agency. During the LOFT assessment phase, we studied the displacement damage produced in the SDDs by the protons trapped in the Earth's magnetosphere. In a previous paper we discussed the effects of the Non Ionising Energy Losses from protons on the SDD leakage current. In this paper we report the measurement of the variation of Charge Collection Efficiency produced by displacement damage caused by protons and the comparison with the expected damage in orbit.

Del Monte, E; Bozzo, E; Cadoux, F; Rachevski, A; Zampa, G; Zampa, N; Feroci, M; Pohl, M; Vacchi, A

2015-01-01

237

Characterization measurement of a thick CdTe detector for BNCT-SPECT - detection efficiency and energy resolution.  

PubMed

Author?s group is carrying out development of BNCT-SPECT with CdTe device, which monitors the therapy effect of BNCT in real-time. From the design calculations, the dimensions were fixed to 1.5×2×30mm(3). For the collimator it was confirmed that it would have a good spatial resolution and simultaneously the number of counts would be acceptably large. After producing the CdTe crystal, the characterization measurement was carried out. For the detection efficiency an excellent agreement between calculation and measurement was obtained. Also, the detector has a very good energy resolution so that gamma-rays of 478keV and 511keV could be distinguished in the spectrum. PMID:24581600

Murata, Isao; Nakamura, Soichiro; Manabe, Masanobu; Miyamaru, Hiroyuki; Kato, Itsuro

2014-06-01

238

Cosmic Microwave Background Polarization Detector with High Efficiency, Broad Bandwidth, and Highly Symmetric Coupling to Transition Edge Sensor Bolometers  

NASA Technical Reports Server (NTRS)

Four probe antennas transfer signals from waveguide to microstrip lines. The probes not only provide broadband impedance matching, but also thermally isolate waveguide and detector. In addition, we developed a new photonic waveguide choke joint design, with four-fold symmetry, to suppress power leakage at the interface. We have developed facilities to test superconducting circuit elements using a cryogenic microwave probe station, and more complete systems in waveguide. We used the ring resonator shown below to measure a dielectric loss tangent < 7x10(exp -4) over 10 - 45 GHz. We have combined component simulations to predict the overall coupling from waveguide modes to bolometers. The result below shows the planar circuit and waveguide interface can utilize the high beam symmetry of HE11 circular feedhorns with > 99% coupling efficiency over 30% fractional bandwidth.

Wollack, E.; Cao, N.; Chuss, D.; Denis, K.; Hsieh, W.-T.; Moseley, S. Harvey; Schneider, G.; Stevenson, T.; Travers, D.; U-yen, K.

2008-01-01

239

High-detection efficiency and picosecond timing compact detector modules with red-enhanced SPADs  

NASA Astrophysics Data System (ADS)

In the last years many progresses have been made in the field of silicon Single Photon Avalanche Diodes (SPAD) thanks to the improvements both in device design and in fabrication technology. Particularly, the Dipartimento di Elettronica e Informazione of Politecnico di Milano and the CNR-IMM of Bologna have been in the forefront of this research activity by designing and fabricating a new device structure enabling the fabrication of SPADs with red enhanced photon detection efficiency. In this paper we present a compact photon counting and timing module that fills the gap between the high temporal resolution and the high detection efficiency systems. The module exploits Red-Enhanced SPAD technology to attain a Photon Detection Efficiency (PDE) as high as 37% at 800 nm (peak of 58% at 600 nm) while maintaining a temporal resolution of about 100 ps FWHM, even with light diffused across the whole active area. A thermo-electric cooling system guarantees a noise as low as few counts per second for a 50 ?m diameter SPAD while a low threshold avalanche pick-up circuit assures a limited shift in the temporal response.

Giudice, Andrea; Simmerle, Georg; Veronese, Daniele; Biasi, Roberto; Gulinatti, Angelo; Rech, Ivan; Ghioni, Massimo; Maccagnani, Piera

2012-06-01

240

Efficiency Calibration Using HEU Standards of 2-Inch by 2-Inch NaI Detector  

SciTech Connect

The Analytical Development Section of SRTC was requested by the Facilities Disposition Division (FDD) to determine the holdup of highly enriched uranium (HEU) in the 321-M facility as part of an overall deactivation project of the facility. The 321-M facility was used to fabricate enriched uranium fuel assemblies, lithium-aluminum target tubes, neptunium assemblies, and miscellaneous components for the production reactors. The facility also includes the 324-M storage building and the passageway connecting it to 321-M. The results of the holdup assays are essential for determining compliance with the solid waste Waste Acceptance Criteria, Material Control and Accountability, and to meet criticality safety controls. Two measurement systems will be used to determine HEU holdup: One is a portable EG and G Dart system that contains Gamma-Vision software to support a Multichannel Analyzer (MCA) card, high voltage power, and space to store and manipulate multiple 4096-channel gamma-ray spect ra. The other is a 2-inch x 2-inch NaI crystal with an MCA that uses a portable computer with a Canberra NaI plus card installed. This card converts the PC to a full function MCA and contains the ancillary electronics, high voltage power supply and amplifier, required for data acquisition. This report will discuss the calibration of the 2-inch x 2-inch NaI detector.

Dewberry, R. A.

2000-10-24

241

An efficient procedure for tomotherapy treatment plan verification using the on-board detector  

NASA Astrophysics Data System (ADS)

In this work, a fast and simple procedure for tomotherapy treatment plan verification using the on-board detector (OBD) has been developed. This procedure allows verification of plans with static and dynamic jaws (TomoEDGE). A convolution-based calculation model has been derived in order to link the leaf control sinogram from the treatment planning system to the data acquired by the OBD during a static couch procedure. The convolution kernel has been optimized using simple plans calculated in the Tomotherapy Cheese phantom. The optimal kernel has been found to be a lorentzian function, whose parameter ? is 0.186 for the 1 cm jaw opening, 0.232 for the 2.5 cm jaw opening and 0.373 for the 5 cm jaw opening. The evaluation has been performed with a ?-index analysis. The dose criterion was 3% of the 95th percentile of the dose distribution and the distance-to-agreement criterion is 2 mm. In order to validate the procedure, it has been applied to around 50 clinical treatment plans, which had already been validated by the Delta4 phantom (Scandidos, Sweden). 96% of the tested plans have passed the criteria. Concerning the other 4%, significant discrepancies between the leaf pattern in the leaf control sinogram and the OBD data have been shown, which might be due to differences in the leaf open time. This corresponds also to a higher sensitivity of this method over the Delta4, adding the possibility of better monitoring the treatment delivery.

Pisaturo, O.; Miéville, F.; Tercier, P.-A.; Allal, A. S.

2015-02-01

242

Neutron Damage in Mechanically-Cooled High-Purity Germanium Detectors for Field-Portable Prompt Gamma Neutron Activation Analysis (PGNAA) Systems  

SciTech Connect

Prompt Gamma Neutron Activation (PGNAA) systems require the use of a gamma-ray spectrometer to record the gamma-ray spectrum of an object under test and allow the determination of the object’s composition. Field-portable systems, such as Idaho National Laboratory’s PINS system, have used standard liquid-nitrogen-cooled high-purity germanium (HPGe) detectors to perform this function. These detectors have performed very well in the past, but the requirement of liquid-nitrogen cooling limits their use to areas where liquid nitrogen is readily available or produced on-site. Also, having a relatively large volume of liquid nitrogen close to the detector can impact some assessments, possibly leading to a false detection of explosives or other nitrogen-containing chemical. Use of a mechanically-cooled HPGe detector is therefore very attractive for PGNAA applications where nitrogen detection is critical or where liquid-nitrogen logistics are problematic. Mechanically-cooled HPGe detectors constructed from p-type germanium, such as Ortec’s trans-SPEC, have been commercially available for several years. In order to assess whether these detectors would be suitable for use in a fielded PGNAA system, Idaho National Laboratory (INL) has been performing a number of tests of the resistance of mechanically-cooled HPGe detectors to neutron damage. These detectors have been standard commercially-available p-type HPGe detectors as well as prototype n-type HPGe detectors. These tests compare the performance of these different detector types as a function of crystal temperature and incident neutron fluence on the crystal.

E.H. Seabury; C.J. Wharton; A.J. Caffrey; J.B. McCabe; C. DeW. Van Siclen

2013-10-01

243

An efficient procedure for tomotherapy treatment plan verification using the on-board detector.  

PubMed

In this work, a fast and simple procedure for tomotherapy treatment plan verification using the on-board detector (OBD) has been developed. This procedure allows verification of plans with static and dynamic jaws (TomoEDGE). A convolution-based calculation model has been derived in order to link the leaf control sinogram from the treatment planning system to the data acquired by the OBD during a static couch procedure. The convolution kernel has been optimized using simple plans calculated in the Tomotherapy Cheese phantom. The optimal kernel has been found to be a lorentzian function, whose parameter ? is 0.186 for the 1 cm jaw opening, 0.232 for the 2.5 cm jaw opening and 0.373 for the 5 cm jaw opening. The evaluation has been performed with a ?-index analysis. The dose criterion was 3% of the 95th percentile of the dose distribution and the distance-to-agreement criterion is 2 mm. In order to validate the procedure, it has been applied to around 50 clinical treatment plans, which had already been validated by the Delta4 phantom (Scandidos, Sweden). 96% of the tested plans have passed the criteria. Concerning the other 4%, significant discrepancies between the leaf pattern in the leaf control sinogram and the OBD data have been shown, which might be due to differences in the leaf open time. This corresponds also to a higher sensitivity of this method over the Delta4, adding the possibility of better monitoring the treatment delivery. PMID:25622205

Pisaturo, O; Miéville, F; Tercier, P-A; Allal, A S

2015-02-21

244

Study on the novel neutron-to-proton convertor for improving the detection efficiency of a triple GEM based fast neutron detector  

NASA Astrophysics Data System (ADS)

A high-efficiency fast neutron detector prototype based on a triple Gas Electron Multiplier (GEM) detector, which, coupled with a novel multi-layered high-density polyethylene (HDPE) as a neutron-to-proton converter for improving the neutron detection efficiency, is introduced and tested with the Am-Be neutron source in the Institute of Modern Physics (IMP) at Lanzhou in the present work. First, the developed triple GEM detector is tested by measuring its effective gain and energy resolution with 55Fe X-ray source to ensure that it has a good performance. The effective gain and obtained energy resolution is 5.0×104 and around 19.2%, respectively. Secondly, the novel multi-layered HDPE converter is coupled with the cathode of the triple GEM detector making it a high-efficiency fast neutron detector. Its effective neutron response is four times higher than that of the traditional single-layered conversion technique when the converter layer number is 38. Supported by National Natural Science Foundation of China (11135002, 11305232, 11175076)

Wang, Xiao-Dong; Yang, He-Run; Ren, Zhong-Guo; Zhang, Jun-We; Yang, Lei; Zhang, Chun-Hui; Ha, Ri-Ba-La; An, Lü-Xing; Hu, Bi-Tao

2015-02-01

245

Effects of characteristic x rays on the noise power spectra and detective quantum efficiency of photoconductive x-ray detectors.  

PubMed

The effects of K fluorescence on the imaging performance of photoconductor-based x-ray imaging systems are investigated. A cascaded linear systems model was developed, where a parallel cascaded process was implemented to take into account the effect of K-fluorescence reabsorption on the modulation transfer function (MTF), noise power spectrum (NPS), and the spatial frequency dependent detective quantum efficiency [DQE(f)] of an imaging system. The investigation was focused on amorphous selenium (a-Se), which is the most highly developed photoconductor material for x-ray imaging. The results were compared to those obtained with Monte Carlo simulation using the same imaging condition and detector parameters, so that the validity of the cascaded linear system model could be confirmed. Our results revealed that K-fluorescence reabsorption in a-Se is responsible for a 18% drop in NPS at high spatial frequencies with an incident x-ray photon energy of E=20 keV (which is just above the K edge of 12.5 keV). When E increases to 60 keV, the effects of K-fluorescence reabsorption on NPS decrease to approximately 12% at high spatial frequencies. Because the high frequency drop is present in both MTF and NPS, the effect of K fluorescence on DQE(f) is minimal, especially for E that is much higher than the K edge. We also applied the cascaded linear system model to a newly developed compound photoconductor, lead iodide (PbI2), and found that at 60 keV there is a high frequency drop in NPS of 19%. The calculated NPS were compared to previously published measurements of PbI2 detectors. PMID:11695766

Zhao, W; Ji, W G; Rowlands, J A

2001-10-01

246

Self-powered micro-structured solid state neutron detector with very low leakage current and high efficiency  

E-print Network

micro-structures. The fabricated detectors use boron filled deep holes with aspect ratio of over 12Self-powered micro-structured solid state neutron detector with very low leakage current and high, fabrication, and performance of solid-state neutron detector based on three-dimensional honeycomb-like silicon

Danon, Yaron

247

Compact high-efficiency linear cryocooler in single-piston moving magnet design for HOT detectors  

NASA Astrophysics Data System (ADS)

State of the art Mid Wave IR-technology has the potential to rise the FPA temperature from 77K to 130-150K (High Operation Temperature, HOT). Using a HOT FPA will significantly lower SWaP and keep those parameters finally dominated by the employed cryocooler. Therefore, compact high performance cryocoolers are mandatory. AIM has developed the SX040 cooler, optimized for FPA temperatures of about 95K (presented at SPIE 2010). The SX040 cooler incorporates a high efficient dual piston driving mechanism resulting in a very compact compressor of less than 100mm length. Higher compactness - especially shorter compressors - can be achieved by change from dual to single piston design. The new SX030 compressor has such a single piston Moving Magnet driving mechanism resulting in a compressor length of about 60mm. Common for SX040 and SX030 family is a Moving Magnet driving mechanism with coils placed outside the helium vessel. In combination with high performance plastics for the piston surfaces this design enables lifetimes in excess of 20,000h MTTF. Because of the higher FPA temperature and a higher operating frequency also a new displacer needs to be developed. Based on the existing 1/4" coldfinger interface AIM developed a new displacer optimized for an FPA temperature of 140K and above. This paper gives an overview on the development of this new compact single piston cryocooler. Technical details and performance data will be shown.

Rühlich, I.; Mai, M.; Rosenhagen, C.; Withopf, A.; Zehner, S.

2012-06-01

248

Using a 2D detector array for meaningful and efficient linear accelerator beam property validations.  

PubMed

Following linear accelerator commissioning, the qualified medical physicist is responsible for monitoring the machine's ongoing performance, detecting and investigating any changes in beam properties, and assessing the impact of unscheduled repairs. In support of these responsibilities, the authors developed a method of using a 2D ionization chamber array to efficiently test and validate important linear accelerator photon beam properties. A team of three physicists identified critical properties of the accelerator and developed constancy tests that were sensitive to each of the properties. The result was a 14-field test plan. The test plan includes large and small fields at varying depths, a reduced SSD field at shallow depth for sensitivity to extra focal photon and electron components, and analysis of flatness, symmetry, dose, dose profiles, and dose ratios. Constancy tests were repeated five times over a period of six weeks and used to set upper and lower investigation levels at ± 3 SDs. Deliberate variations in output, penumbra, and energy were tested to determine the suitability of the proposed method. Measurements were also performed on a similar, but distinct, machine to assess test sensitivity. The results demonstrated upper and lower investigation levels significantly smaller than the comparable TG-142 annual recommendations, with the exception of the surrogate used for output calibration, which still fell within the TG-142 monthly recommendation. Subtle changes in output, beam energy, and penumbra were swiftly identified for further investigation. The test set identified the distinct nature of the second accelerator. The beam properties of two photon energies can be validated in approximately 1.5 hrs using this method. The test suite can be used to evaluate the impact of minor repairs, detect changes in machine performance over time, and supplement other machine quality assurance testing. PMID:25493506

Ritter, Timothy A; Gallagher, Ian; Roberson, Peter L

2014-01-01

249

Study on the novel neutron-to-proton concept for improving the detection efficiency of triple GEM based fast neutron detector  

E-print Network

A high-efficiency fast neutron detector prototype based on a triple Gas Electron Multiplier (GEM) detector, which coupled with a novel multi-layered High-Density PolyEthylene (HDPE) as a neutron-to-proton converter for improving the neutron detection efficiency, is introduced and tested with the Am-Be neutron source in Institute of Modern Physics (IMP) at Lanzhou in present work. Firstly, the developed triple GEM detector is tested by measuring its effective gain and energy resolution with $^{55}$Fe X-ray source to ensure that it has a good performance. The effective gain and obtained energy resolution is 5.0$\\times$10$^{4}$ and around of 19.2\\%, respectively. And secondly, the novel multi-layered HDPE converter is coupled with the cathode of the triple GEM detector make it a high-effective fast neutron detector. And its effective neutron response is four times higher than that of the traditional single-layered conversion technique when the converter layer number is 38.

Wang, Xiao-Dong; Ren, Zhong-Guo; Zhang, Jun-Wei; Yang, Lei; Zhang, Chun-Hui; Ha, Ri-Ba-La; An, Lv-Xing

2014-01-01

250

Gigahertz-gated InGaAs/InP single-photon detector with detection efficiency exceeding 55% at 1550 nm  

NASA Astrophysics Data System (ADS)

We report on a gated single-photon detector based on InGaAs/InP avalanche photodiodes (APDs) with a single-photon detection efficiency exceeding 55% at 1550 nm. Our detector is gated at 1 GHz and employs the self-differencing technique for gate transient suppression. It can operate nearly dead time free, except for the one clock cycle dead time intrinsic to self-differencing, and we demonstrate a count rate of 500 Mcps. We present a careful analysis of the optimal driving conditions of the APD measured with a dead time free detector characterization setup. It is found that a shortened gate width of 360 ps together with an increased driving signal amplitude and operation at higher temperatures leads to improved performance of the detector. We achieve an afterpulse probability of 7% at 50% detection efficiency with dead time free measurement and a record efficiency for InGaAs/InP APDs of 55% at an afterpulse probability of only 10.2% with a moderate dead time of 10 ns.

Comandar, L. C.; Fröhlich, B.; Dynes, J. F.; Sharpe, A. W.; Lucamarini, M.; Yuan, Z. L.; Penty, R. V.; Shields, A. J.

2015-02-01

251

FOUR PI CALIBRATION AND MODELING OF A BARE GERMANIUM DETECTOR IN A CYLINDRICAL FIELD SOURCE  

SciTech Connect

In reference 1 the authors described {gamma}-ray holdup assay of a Mossbauer spectroscopy instrument where they utilized two axial symmetric cylindrical shell acquisitions and two disk source acquisitions to determine Am-241 and Np-237 contamination. The measured contents of the two species were determined using a general detector efficiency calibration taken from a 12-inch point source.2 The authors corrected the raw spectra for container absorption as well as for geometry corrections to transform the calibration curve to the applicable axial symmetric cylindrical source - and disk source - of contamination. The authors derived the geometry corrections with exact calculus that are shown in equations (1) and (2) of our Experimental section. A cylindrical shell (oven source) acquisition configuration is described in reference 3, where the authors disclosed this configuration to gain improved sensitivity for holdup measure of U-235 in a ten-chamber oven. The oven was a piece of process equipment used in the Savannah River Plant M-Area Uranium Fuel Fabrication plant for which a U-235 holdup measurement was necessary for its decontamination and decommissioning in 2003.4 In reference 4 the authors calibrated a bare NaI detector for these U-235 holdup measurements. In references 5 and 6 the authors calibrated a bare HpGe detector in a cylindrical shell configuration for improved sensitivity measurements of U-235 in other M-Area process equipment. Sensitivity was vastly improved compared to a close field view of the sample, with detection efficiency of greater than 1% for the 185.7-keV {gamma}-ray from U-235. In none of references 3 - 7 did the authors resolve the exact calculus descriptions of the acquisition configurations. Only the empirical efficiency for detection of the 185.7-keV photon from U-235 decay was obtained. Not until the 2010 paper of reference 1 did the authors derive a good theoretical description of the flux of photons onto the front face of a detector from an axially symmetric cylindrical shell. Subsequent to publication of 1, the theoretical treatment of the cylindrical shell and disk source acquisition sources was recognized by the Los Alamos National Laboratory as suitable for including in the Safeguards Training Program.8 Therefore, we felt it was important to accurately demonstrate the calculus describing the cylindrical shell configuration for the HpGe detector and to theoretically account for the observed bare-detector efficiencies measured in references (3-6). In this paper we demonstrate the applicability of the cylindrical shell derivation to a flexible planar sheet of known Am-241, Eu-152, and Cs-137 activity that we rolled into a symmetrical cylindrical shell of radioactivity. Using the geometry correction equation of reference 1, we calculate geometry correction values using the known detector and source dimensions combined with source to detector distances. We then compare measured detection efficiencies from a cylindrical shell of activity for the 185.7-keV photon (U-235) and for the 414.3-keV photon (Pu-239) with those determined for a 12-inch point source(2,7) to demonstrate agreement between experiment and the theoretically calculated values derived by the Savannah River National Laboratory (SRNL) authors of reference 1. We demonstrate this geometry correction first for the 185.7- and 414.3-keV {gamma}-rays. But because the detector was point source calibrated at 12 inches for the energy range (60 -1700) keV (using two distinct sources) to map its intrinsic efficiency, the geometry correction for any acquisition configuration holds for all photon energies.2 We demonstrate that for ten photon energies in the range 121 keV to 967 keV. The good agreement between experiment and calculation is demonstrated at five source to detector distances using the identical shielded HpGe detector of references 4-7 as well as with a separate HpGe detector. We then extend the measurement to include a single acquisition where the flexible source is wrapped around the bare detector in a symmetrical cylinder tha

Dewberry, R.; Young, J.

2011-04-29

252

Performance of an AGATA asymmetric detector  

NASA Astrophysics Data System (ADS)

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.

Boston, A. J.; Dimmock, M. R.; Unsworth, C.; Boston, H. C.; Cooper, R. J.; Grint, A. N.; Harkness, L. J.; Lazarus, I. H.; Jones, M.; Nolan, P. J.; Oxley, D. C.; Simpson, J.; Slee, M.; Agata Collaboration

2009-06-01

253

Small Scale Assessment of Spatial and Vertical Redistribution of Fukushima Fallouts Radiocaesium in Contaminated Soil Using in-situ HPGe Gamma Ray Spectrometry  

NASA Astrophysics Data System (ADS)

After Tohoku earthquake on March 11th 2011, the subsequent tsunami and the resulting Fukushima Daiichi Nuclear Power Plant disaster, gamma emitting particles, first release into the atmosphere, were quickly deposited on the soil surface, with potentially harmful level in the surroundings of the nuclear power plant. Thus, the evaluation of soil deposition pattern, depth migration and afterward radionuclides redistribution and export by erosion and hydrological processes is fundamental for contamination assessments and to plan future actions. Our study site is located 37km from Fukushima power plant, inside the evacuated zone. In this study, we used a bounded erosion plot of 22.1m x 5m to assess global export of sediments and 137Cs. This plot, previously cropped with tobacco, is morphologically divided into inter-rill areas separated by rills that formed into former wheel tracks. The bottom of the plot is subject to deposition of sediments. In order to determine and quantify the internal processes responsible of the export of sediment, the depth distribution of 137Cs is estimated using a portable High Purity Germanium (HPGe) detector. Such a portable device, associated to the high radiation levels, allow an acquisition of spatially distributed data within the plot in a reasonable time (1 min/sample). At the same time, depth distribution of 137Cs are measured using the scrapper plate technique, adapted to obtain a fine resolution in the first, highly contaminated, centimeters of soil. Finally, 137Cs depth profiles, associated with in situ and laboratory gamma spectrums acquired with the portable detector, allow for the detector calibration. Although the initial deposit can reasonably be supposed homogeneous at the plot scale, the dataset obtained 3 months later shows high spatial and temporal variability due to erosion processes. Measurements with the portable HPGe detector proved to be useful at this small scale, avoiding the needs of a large number of soil samples, and our results are promising to understand erosion at larger scale where horizontal patterns of deposition and redistribution are usually supposed homogeneous over quite larger areas.

Patin, J.; Onda, Y.; Yoda, H.; Kato, H.

2011-12-01

254

Cascaded-systems analyses and the detective quantum efficiency of single-Z x-ray detectors including photoelectric, coherent and incoherent interactions  

SciTech Connect

Purpose: Theoretical models of the detective quantum efficiency (DQE) of x-ray detectors are an important step in new detector development by providing an understanding of performance limitations and benchmarks. Previous cascaded-systems analysis (CSA) models accounted for photoelectric interactions only. This paper describes an extension of the CSA approach to incorporate coherent and incoherent interactions, important for low-Z detectors such as silicon and selenium. Methods: A parallel-cascade approach is used to describe the three types of x-ray interactions. The description of incoherent scatter required developing expressions for signal and noise transfer through an 'energy-labeled reabsorption' process where the parameters describing reabsorption are random functions of the scatter photon energy. The description of coherent scatter requires the use of scatter form factors that may not be accurate for some crystalline detector materials. The model includes the effects of scatter reabsorption and escape, charge collection, secondary quantum sinks, noise aliasing, and additive noise. Model results are validated by Monte Carlo calculations for Si and Se detectors assuming free-atom atomic form factors. Results: The new signal and noise transfer expressions were validated by showing agreement with Monte Carlo results. Coherent and incoherent scatter can degrade the DQE of Si and sometimes Se detectors depending on detector thickness and incident-photon energy. Incoherent scatter can produce a substantial low-frequency drop in the modulation transfer function and DQE. Conclusions: A generally useful CSA model of the DQE is described that is believed valid for any single-Z material up to 10 cycles/mm at both mammographic and radiographic energies within the limitations of Fourier-based linear-systems models and the use of coherent-scatter form factors. The model describes a substantial low-frequency drop in the DQE of Si systems due to incoherent scatter above 20-40 keV.

Yun, Seungman [Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, 100 Perth Drive, London, Ontario N6A 5K8 (Canada); School of Mechanical Engineering, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Tanguay, Jesse; Cunningham, Ian A. [Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, 100 Perth Drive, London, Ontario N6A 5K8 (Canada); Kim, Ho Kyung [School of Mechanical Engineering, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of)

2013-04-15

255

Versatile Silicon Photodiode Detector Technology for Scanning Electron Microscopy with High-Efficiency Sub-5 keV Electron Detection  

E-print Network

Versatile Silicon Photodiode Detector Technology for Scanning Electron Microscopy with High: +31 (0)15 26 22163, Email: a.sakic@tudelft.nl Abstract A new silicon electron detector technology for Scanning Electron Microscopy, based on ultrashallow p+ n boron-layer photodiodes, features nm-thin anodes

Technische Universiteit Delft

256

Operation of a GERDA Phase I prototype detector in liquid argon and nitrogen  

E-print Network

The GERDA (GERmanium Detector Array) experiment aiming to search for the neutrinoless double beta decay of 76Ge at the Laboratori Nazionali Del Gran Sasso (LNGS), Italy, will operate bare enriched high-purity germanium (HPGe) detectors in liquid argon. GERDA Phase I will use the enriched diodes from the previous Heidelberg-Moscow (HdM) and IGEX experiments. With the HPGe detectors mounted in a low-mass holder, GERDA aims at an excellent energy resolution and extremely low background. The goal is to check the claim for the neutrinoless double beta decay evidence in the HdM 76Ge experiment within one year of data taking. Before dismounting the enriched diodes from their cryostat, the performance parameters of the HdM and the IGEX detectors have been measured. The diodes have been removed from their cryostats, their dimensions measured and they have been put under va-cuum in a transportation container. They are now being refurbished for GERDA Phase I at Canberra Semiconductor NV. Before operating the enriched diodes, a non-enriched HPGe p-type detector mounted in a low-mass holder is operated in the liquid argon test facility of the GERDA Detector Laboratory (GDL) at LNGS. Since January 2006, the testing of the prototype detector is being carried out in the GDL as well as at the site of the detector manufacturer.

M. Barnabé Heider; A. Bakalyarov; L. Bezrukov; C. Cattadori; O. Chkvorets; K. Gusev; M. Hult; I. Kirpichnikov; V. Lebedev; G. Marissens; P. Peiffer; S. Schönert; M. Shirchenko; A. Smolnikov; A. Vasenko; S. Vasiliev; S. Zhukov

2008-12-20

257

Local State Transition of Feedback Controlled Quantum Systems with Imperfect Detector Efficiency: Part I: Differential Geometric Analysis for Dynamical Systems with Matrix-Valued States  

NASA Astrophysics Data System (ADS)

We consider a new class of dynamical systems whose state is represented by a Hermitian matrix motivated by treating quantum control problems. We develop theory and techniques of differential geometric analysis for dynamical systems in that class, where a Lie product of matrix functions is introduced and plays an important role. We provide a simple and coordinate-free calculation method for the Lie product of matrix functions which enables efficient differential geometric analysis. The result of this paper will be used in a follow-up paper on analysis of local state transition of controlled quantum systems under continuous quantum measurement with imperfect detector efficiency.

Sasaki, Tomotake; Hara, Shinji; Tsumura, Koji

258

Strategy of HPGe screening measurements in the SuperNEMO experiment  

SciTech Connect

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}(0?)>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.

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)] [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

259

Semiconductor detectors for Compton imaging in nuclear medicine  

NASA Astrophysics Data System (ADS)

An investigation is underway at the University of Liverpool to assess the suitability of two position sensitive semiconductor detectors as components of a Compton camera for nuclear medical imaging. The ProSPECTus project aims to improve image quality, provide shorter data acquisition times and lower patient doses by replacing conventional Single Photon Emission Computed Tomography (SPECT) systems. These mechanically collimated systems are employed to locate a radioactive tracer that has been administered to a patient to study specifically targeted physiological processes. The ProSPECTus system will be composed of a Si(Li) detector and a High Purity Germanium (HPGe) detector, a configuration deemed optimum using a validated Geant4 simulation package. Characterising the response of the detectors to gamma irradiation is essential in maximising the sensitivity and image resolution of the system. To this end, the performance of the HPGe ProSPECTus detector and a suitable Si(Li) detector has been assessed at the University of Liverpool. The energy resolution of the detectors has been measured and a surface scan of the Si(Li) detector has been performed using a finely collimated 241Am gamma ray source. Results from the investigation will be presented.

Harkness, LJ; Judson, D. S.; Kennedy, H.; Sweeney, A.; Boston, A. J.; Boston, H. C.; Cresswell, J. R.; Nolan, P. J.; Sampson, J. A.; Burrows, I.; Groves, J.; Headspith, J.; Lazarus, I. H.; Simpson, J.; Bimson, W. E.; Kemp, G. J.

2012-01-01

260

Beta-gamma coincidence counting efficiency and energy resolution optimization by Geant4 Monte Carlo simulations for a phoswich well detector.  

PubMed

A single-channel phoswich well detector has been assessed and analysed in order to improve beta-gamma coincidence measurement sensitivity of (131m)Xe and (133m)Xe. This newly designed phoswich well detector consists of a plastic cell (BC-404) embedded in a CsI(Tl) crystal coupled to a photomultiplier tube (PMT). It can be used to distinguish 30.0-keV X-ray signals of (131m)Xe and (133m)Xe using their unique coincidence signatures between the conversion electrons (CEs) and the 30.0-keV X-rays. The optimum coincidence efficiency signal depends on the energy resolutions of the two CE peaks, which could be affected by relative positions of the plastic cell to the CsI(Tl) because the embedded plastic cell would interrupt scintillation light path from the CsI(Tl) crystal to the PMT. In this study, several relative positions between the embedded plastic cell and the CsI(Tl) crystal have been evaluated using Monte Carlo modeling for its effects on coincidence detection efficiency and X-ray and CE energy resolutions. The results indicate that the energy resolution and beta-gamma coincidence counting efficiency of X-ray and CE depend significantly on the plastic cell locations inside the CsI(Tl). The degraded X-ray and CE peak energy resolutions due to light collection efficiency deterioration by the embedded cell can be minimised. The optimum of CE and X-ray energy resolution, beta-gamma coincidence efficiency as well as the ease of manufacturing could be achieved by varying the embedded plastic cell positions inside the CsI(Tl) and consequently setting the most efficient geometry. PMID:20598559

Zhang, Weihua; Mekarski, Pawel; Ungar, Kurt

2010-12-01

261

Photon detectors  

SciTech Connect

J. Seguinot and T. Ypsilantis have recently described the theory and history of Ring Imaging Cherenkov (RICH) detectors. In this paper, I will expand on these excellent review papers, by covering the various photon detector designs in greater detail, and by including discussion of mistakes made, and detector problems encountered, along the way. Photon detectors are among the most difficult devices used in physics experiments, because they must achieve high efficiency for photon transport and for the detection of single photo-electrons. For gaseous devices, this requires the correct choice of gas gain in order to prevent breakdown and wire aging, together with the use of low noise electronics having the maximum possible amplification. In addition, the detector must be constructed of materials which resist corrosion due to photosensitive materials such as, the detector enclosure must be tightly sealed in order to prevent oxygen leaks, etc. The most critical step is the selection of the photocathode material. Typically, a choice must be made between a solid (CsI) or gaseous photocathode (TMAE, TEA). A conservative approach favors a gaseous photocathode, since it is continuously being replaced by flushing, and permits the photon detectors to be easily serviced (the air sensitive photocathode can be removed at any time). In addition, it can be argued that we now know how to handle TMAE, which, as is generally accepted, is the best photocathode material available as far as quantum efficiency is concerned. However, it is a very fragile molecule, and therefore its use may result in relatively fast wire aging. A possible alternative is TEA, which, in the early days, was rejected because it requires expensive CaF{sub 2} windows, which could be contaminated easily in the region of 8.3 eV and thus lose their UV transmission.

Va`vra, J.

1995-10-01

262

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

NASA Astrophysics Data System (ADS)

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.

Cooper, R. J.; Boston, A. J.; Boston, H. C.; Cresswell, J. R.; Grint, A. N.; Harkness, L. J.; Nolan, P. J.; Oxley, D. C.; Scraggs, D. P.; Lazarus, I.; Simpson, J.; Dobson, J.

2008-10-01

263

K114 (trans, trans)-bromo-2,5-bis(4-hydroxystyryl)benzene is an efficient detector of cationic amyloid fibrils.  

PubMed

Cationic amyloid fibrils found in human semen enhance the transmission of the human immunodeficiency virus (HIV) and thus, are named semen-derived enhancer of virus infection (SEVI). The mechanism for the enhancement of transmission is not completely understood but it has been proposed that SEVI neutralizes the repulsion that exists between the negatively charged viral envelope and host cell membrane. Consistent with this view, here we show that the fluorescence of cationic thioflavin T (ThT) in the presence of SEVI is weak, and thus ThT is not an efficient detector of SEVI. On the other hand, K114 ((trans, trans)-bromo-2,5-bis(4-hydroxystyryl)benzene) forms a highly fluorescent, phenolate-like species on the cationic surface of SEVI. This species does not form in the presence of amyloid fibrils from insulin and amyloid-? protein, both of which are efficiently detected by ThT fluorescence. Together, our results show that K114 is an efficient detector of SEVI. PMID:25524064

Selmani, Veli; Robbins, Kevin J; Ivancic, Valerie A; Lazo, Noel D

2015-03-01

264

Enhanced Detection Efficiency of Direct Conversion X-ray Detector Using Polyimide as Hole-Blocking Layer  

PubMed Central

In this article we demonstrate the performance of a direct conversion amorphous selenium (a-Se) X-ray detector using biphenyldisnhydride/1,4 phenylenediamine (BPDA/PPD) polyimide (PI) as a hole-blocking layer. The use of a PI layer with a-Se allows detector operation at high electric fields (?10?V/?m) while maintaining low dark current, without deterioration of transient performance. The hole mobility of the PI/a-Se device is measured by the time-of-flight method at different electric fields to investigate the effect of the PI layer on detector performance. It was found that hole mobility as high as 0.75?cm2/Vs is achievable by increasing the electric field in the PI/a-Se device structure. Avalanche multiplication is also shown to be achievable when using PI as a blocking layer. Increasing the electric field within a-Se reduces the X-ray ionization energy, increases hole mobility, and improves the dynamic range and sensitivity of the detector. PMID:24285255

Abbaszadeh, Shiva; Scott, Christopher C.; Bubon, Oleksandr; Reznik, Alla; Karim, Karim S.

2013-01-01

265

Monte Carlo simulation of a PhosWatch detector using Geant4 for xenon isotope beta-gamma coincidence spectrum profile and detection efficiency calculations.  

PubMed

A simulation tool has been developed using the Geant4 Toolkit to simulate a PhosWatch single channel beta-gamma coincidence detection system consisting of a CsI(Tl)/BC404 Phoswich well detector and pulse shape analysis algorithms implemented digital signal processor. The tool can be used to simulate the detector's response for all the gamma rays and beta particles emitted from (135)Xe, (133m)Xe, (133)Xe, (131m)Xe and (214)Pb. Two- and three-dimensional beta-gamma coincidence spectra from the PhosWatch detector can be produced using the simulation tool. The accurately simulated spectra could be used to calculate system coincidence detection efficiency for each xenon isotope, the corrections for the interference from the various spectral components from radon and xenon isotopes, and system gain calibration. Also, it can generate two- and three-dimensional xenon reference spectra to test beta-gamma coincidence spectral deconvolution analysis software. PMID:19647444

Mekarski, P; Zhang, W; Ungar, K; Bean, M; Korpach, E

2009-10-01

266

Empirical assessment of the detection efficiency of CR-39 at high proton fluence and a compact, proton detector for high-fluence applications  

DOE PAGESBeta

CR-39 solid-state nuclear track detectors are widely used in physics and in many inertial confinement fusion (ICF) experiments, and under ideal conditions these detectors have 100% detection efficiency for ?0.5–8 MeV protons. When the fluence of incident particles becomes too high, overlap of particle tracks leads to under-counting at typical processing conditions (5 h etch in 6N NaOH at 80?°C). Short etch times required to avoid overlap can cause under-counting as well, as tracks are not fully developed. Experiments have determined the minimum etch times for 100% detection of 1.7–4.3-MeV protons and established that for 2.4-MeV protons, relevant for detection of DD protons, the maximum fluence that can be detected using normal processing techniques is ?3?×?106 cm?2. A CR-39-based proton detector has been developed to mitigate issues related to high particle fluences on ICF facilities. Using a pinhole and scattering foil several mm in front of the CR-39, proton fluences at the CR-39 are reduced by more than a factor of ?50, increasing the operating yield upper limit by a comparable amount.

Rosenberg, M. J.; Seguin, F. H.; Waugh, C. J.; Rinderknecht, H. G.; Orozco, D.; Frenje, J. A.; Johnson, M. Gatu; Sio, H.; Zylstra, A. B.; Sinenian, N.; Li, C. K.; Petrasso, R. D.; Glebov, V. Yu.; Stoeckl, C.; Hohenberger, M.; Sangster, T. C.; LePape, S.; Mackinnon, A. J.; Bionta, R. M.; Landen, O. L.; Zacharias, R. A.; Kim, Y.; Herrmann, H. W.; Kilkenny, J. D.

2014-04-01

267

Empirical assessment of the detection efficiency of CR-39 at high proton fluence and a compact, proton detector for high-fluence applications  

NASA Astrophysics Data System (ADS)

CR-39 solid-state nuclear track detectors are widely used in physics and in many inertial confinement fusion (ICF) experiments, and under ideal conditions these detectors have 100% detection efficiency for ˜0.5-8 MeV protons. When the fluence of incident particles becomes too high, overlap of particle tracks leads to under-counting at typical processing conditions (5 h etch in 6N NaOH at 80 °C). Short etch times required to avoid overlap can cause under-counting as well, as tracks are not fully developed. Experiments have determined the minimum etch times for 100% detection of 1.7-4.3-MeV protons and established that for 2.4-MeV protons, relevant for detection of DD protons, the maximum fluence that can be detected using normal processing techniques is ?3 × 106 cm-2. A CR-39-based proton detector has been developed to mitigate issues related to high particle fluences on ICF facilities. Using a pinhole and scattering foil several mm in front of the CR-39, proton fluences at the CR-39 are reduced by more than a factor of ˜50, increasing the operating yield upper limit by a comparable amount.

Rosenberg, M. J.; Séguin, F. H.; Waugh, C. J.; Rinderknecht, H. G.; Orozco, D.; Frenje, J. A.; Johnson, M. Gatu; Sio, H.; Zylstra, A. B.; Sinenian, N.; Li, C. K.; Petrasso, R. D.; Glebov, V. Yu.; Stoeckl, C.; Hohenberger, M.; Sangster, T. C.; LePape, S.; Mackinnon, A. J.; Bionta, R. M.; Landen, O. L.; Zacharias, R. A.; Kim, Y.; Herrmann, H. W.; Kilkenny, J. D.

2014-04-01

268

Comparison of calculated and measured spectral response and intrinsic efficiency for a boron-loaded plastic neutron detector  

Microsoft Academic Search

Boron-loaded scintillators offer the potential for neutron spectrometers with a simplified, peak-shaped response. The Monte Carlo code, MCNP, has been used to calculate the detector characteristics of a scintillator made of a boron-loaded plastic, BC454, for neutrons between 1 and 7 MeV. Comparisons with measurements are made of spectral response for neutron energies between 4 and 6 MeV and of

E. A. Kamykowski

1992-01-01

269

Multielement CdZnTe detectors for high-efficiency, ambient-temperature gamma-ray spectroscopy  

Microsoft Academic Search

CdZnTe is an attractive alternative to scintillator-based technology for ambient-temperature, gamma-ray spectroscopy. Large, single-element devices up to 3500 mm³ have been developed for gamma-ray spectroscopy and are now available commercially. Because CdZnTe is a wide band-gap semiconductor, it can operate over a wide range of ambient temperatures with minimal power consumption. Over this range, CdZnTe detectors routinely yield better overall

T. H. Prettyman; C. E. Moss; M. R. Sweet; K. Ianakiev; R. C. Reedy; J. Li; J. D. Valentine

1998-01-01

270

Investigation of quantum efficiency in mid-wave infrared (MWIR) InAs/GaSb type-II strained layer superlattice (T2SL) detectors  

NASA Astrophysics Data System (ADS)

The objective of this study is to optimize the absorption in the active region of InAs/GaSb T2SL photodetectors for the realization of high-performance MWIR devices. Two sets of MWIR (?100% cut-off ~ 5.5?m at 77K) T2SL detectors were realized; one set with varied detector absorber thickness, the other set with varied T2SL period. The T2SL material quality was evaluated on the basis of room temperature photoluminescence (RTPL) and the high-resolution X-ray diffraction (HRXRD) data. Then the device performance was compared using spectral response, dark current and responsivity measurements. Finally, quantum efficiency was calculated and employed as a metric for the definition of the optimal T2SL period and active region thickness. For the first part of the study, a homojunction pin architecture based on 8 monolayers (MLs) InAs/8MLs GaSb T2SL was used. The thickness of the non-intentionally doped absorber layers were 1.5?m, 2.5?m, and 3.5?m. For the second part of the study, unipolar barrier (pBiBn) devices were grown. The thickness of the absorber region and the T2SL constituent InAs layer thicknesses were kept the same (1.5 ?m and 8 MLs, respectively) whereas the T2SL constituent GaSb thickness was varied as 6 MLs, 8 MLs, and 10 MLs. We have found that the pin detector with 2.5 ?m thick absorber and the pBiBn detector with 8 ML InAs/ 8 ML GaSb T2SL composition are, within the scope of this study, optimal for the realization of MWIR single-element devices and FPAs with corresponding architectures.

Acosta, Lilian; Klein, Brianna; Tian, Zhao-Bing; Frantz, Eric; Myers, Stephen; Gautam, Nutan; Schuler-Sandy, Ted; Plis, Elena; Krishna, Sanjay

2014-02-01

271

Spatio-temporal Monte Carlo modeling of a-Se detectors for breast imaging: energy-weighted Swank noise and detective quantum efficiency  

NASA Astrophysics Data System (ADS)

We study the effect of energy weighting in Swank noise and Detective Quantum Efficiency (DQE) at zero spatial frequency with a detailed Monte Carlo (MC) transport code that includes the three-dimensional spatial and temporal transport of electron-hole pairs in semiconductor x-ray detectors. The transport model takes into account recombination and trapping of carriers including effects of Coulomb forces and external applied electric field. We report pulse-height spectra (PHS) for mono-energetic x rays from 6 to 28 keV photon energy with 0.5 keV step size, and for clinical mammography spectra. A first-approximation electronic noise model is included in the simulations. The Swank calculations take into account the entire PHS distribution while the DQE(0) is calculated from the simulated Swank factor, and quantum efficiency values from the PENELOPE database of attenuation coefficients. The simulated DQE(0) is based on the entire clinical x-ray spectrum and takes into account the energy distribution following Tapiovaara and Wagner's (Phys. Med. Biol. 30, 1985) description for the weighting of carrier transport processes. Swank and DQE simulations for semiconductor detectors can provide insight into the fundamental limitations and possible optimization of breast imaging systems.

Fang, Yuan; Badal, Andreu; Karim, Karim S.; Badano, Aldo

2012-03-01

272

Neutrinoless double-beta decay of76Ge: First results from the International Germanium Experiment (IGEX) with six isotopically enriched detectors  

Microsoft Academic Search

The International Germanium Experiment (IGEX) has six HPGe detectors, isotopically enriched to 86% in 76Ge, containing approximately 90 active moles of 76Ge. Three detectors of 2 kg each operate in the Canfranc Underground Laboratory (Spain) with pulse-shape analysis electronics. One detector (~0.7 kg active volume) has been operating in the Baksan Low-Background Laboratory for several years, and two additional similar

C. E. Aalseth; F. T. Avignone; R. L. Brodzinski; J. I. Collar; E. Garcia; D. González; F. Hasenbalg; W. K. Hensley; I. V. Kirpichnikov; A. A. Klimenko; H. S. Miley; A. Morales; J. Morales; A. Ortiz de Solórzano; S. B. Osetrov; V. S. Pogosov; J. Puimedón; J. H. Reeves; A. Salinas; M. L. Sarsa; A. A. Smolnikov; A. S. Starostin; A. G. Tamanyan; A. A. Vasenko; S. I. Vasiliev; J. A. Villar

1999-01-01

273

Versatile silicon photodiode detector technology for scanning electron microscopy with high-efficiency sub-5 keV electron detection  

Microsoft Academic Search

A new silicon electron detector technology for Scanning Electron Microscopy, based on ultrashallow p+n boron-layer photodiodes, features nm-thin anodes enabling low-energy electron detection with record-high sensitivity down to 200 eV. Designs with segmented, closely-packed photodiodes and through-wafer apertures allow flexible configurations for optimal material and\\/or topographical contrasts. A high scanning speed is obtained by growing a well-controlled, lightly-doped, tens-of-microns-thick epi-layer

L. K. Nanver; G. van Veen; K. Kooijman; P. Vogelsang; T. L. M. Scholtes; W. de Boer; W. H. A. Wien; S. Milosavljevic?; C. T. H. Heerkens; I. Spee

2010-01-01

274

Boron carbide based solid state neutron detectors: the effects of bias and time constant on detection efficiency  

Microsoft Academic Search

Neutron detection in thick boron carbide(BC)\\/n-type Si heterojunction diodes shows a threefold increase in efficiency with applied bias and longer time constants. The improved efficiencies resulting from long time constants have been conclusively linked to the much longer charge collection times in the BC layer. Neutron detection signals from both the p-type BC layer and the n-type Si side of

Nina Hong; John Mullins; Keith Foreman; S. Adenwalla

2010-01-01

275

Neutron generator flux enhancement techniques and construction of a more efficient neutron detector for borehole-logging gamma-ray spectroscopy  

NASA Astrophysics Data System (ADS)

Neutron activation methods and bore-hole gamma-ray spectrometry have been versatile techniques for real time field evaluation in mineral exploration. The most common neutron generators producing 14 MeV and 2.5 MeV neutrons accelerate deuterium ions into a tritium or deuterium target via the 3H( 2H,n)4He or the 2H(2H,n) 3H reactions. The development and design of bore-hole 2.5 MeV high flux neutron generator coupled with an efficient gamma-ray detector is the primary focus of this work, which is needed by the coal and petroleum industries. A 2.5 MeV neutron generator, which used the D(D,n)T reaction, was constructed similar to a conventional Zetatron 14 MeV generator. The performance of the low energy neutron generator was studied under various operating conditions. In order to enhance the neutron flux of the generator, an r.f. field was applied to the ion source which increased the neutron yield per pulse by about thirty percent. A theoretical study of the r.f enhancement has been made to explain the operation of the r.f. added Zetatron tube. An alternative, method of neutron flux enhancement by use of laser-excitation is discussed and explained theoretically. The laser technique although not experimentally verified, is based on the recent development of vibronic lasers, the neutron flux can be enhanced several orders of magnitude by precise tuning of the wavelength within vibronic band. Activation experiments using a large coal sample (about I ton) were conducted, and studies were made on inter and intrapulse counting, detector gated spectra, and comparison of the spectra using different neutron sources. Preliminary results on coal analysis reveal that lower energy (2.5 MeV) is superior to high energy (14 MeV) neutrons. During the course of this work it became necessary to measure fast neutrons, efficiently and in real time. A new type of detector was consequently developed using SnO2 as sheath material around a BGO detector to measure the capture gamma-rays of oxygen. Using neutron activation studies of coal, the feasibility of applying the technique to aid medical diagnostics is also discussed in this dissertation.

Ghias, Asghar

1999-11-01

276

Study of the material photon and electron background and the liquid argon detector veto efficiency of the CDEX-10 experiment  

E-print Network

The China Dark Matter Experiment (CDEX) is located at the China Jinping underground laboratory (CJPL) and aims to directly detect the WIMP flux with high sensitivity in the low mass region. Here we present a study of the predicted photon and electron backgrounds including the background contribution of the structure materials of the germanium detector, the passive shielding materials, and the intrinsic radioactivity of the liquid argon that serves as an anti-Compton active shielding detector. A detailed geometry is modeled and the background contribution has been simulated based on the measured radioactivities of all possible components within the GEANT4 program. Then the photon and electron background level in the energy region of interest (<10^-2 events kg-1 day-1 keV-1 (cpkkd)) is predicted based on Monte Carlo simulations. The simulated result is consistent with the design goal of CDEX-10 experiment, 0.1 cpkkd, which shows that the active and passive shield design of CDEX-10 is effective and feasible.

Jian Su; Zhi Zeng; Hao MA; Qian Yue; Jian-Ping Cheng; Jian-Ping Chang; Nan Chen; Ning Chen; Qing-Hao Chen; Yun-Hua Chen; Yo-Chun Chuang; Zhi Deng; Qiang Du; Hui Gong; Xi-Qing Hao; Qing-Ju He; Han-Xiong Huang; Teng-Rui Huang; Hao Jiang; Ke-Jun Kang; Hau-Bin Li; Jian-Min Li; Jin Li; Jun Li; Xia Li; Xin-Ying Li; Xue-Qian Li; Yu-Lan Li; Yuan-Jing Li; Heng-Yi Liao; Fong-Kay Lin; Shin-Ted Lin; Shu-Kui Liu; Lan-Chun Lü; Shao-Ji Mao; Jian-Qiang Qin; Jie Ren; Jing Ren; Xi-Chao Ruan; Man-Bin Shen; Lakhwinder Singh; Manoj Kumar Singh; Arun Kumar Soma; Chang-Jian Tang; Chao-Hsiung Tseng; Ji-Min Wang; Li Wang; Qing Wang; Henry Tsz-King Wong; Shi-Yong Wu; Yu-Cheng Wu; Hao-Yang Xing; Yin Xu; Tao Xue; Li-Tao Yang; Song-Wei Yang; Nan Yi; Chun-Xu Yu; Hao Yu; Xun-Zhen Yu; Xiong-Hui Zeng; Lan Zhang; Yun-Hua Zhang; Ming-Gang Zhao; Wei Zhao; Zu-Ying Zhou; Jing-Jun Zhu; Wei-Bin Zhu; Xue-Zhou Zhu; Zhong-Hua Zhu

2014-02-19

277

Advanced UV Detectors and Detector Arrays  

NASA Technical Reports Server (NTRS)

Gallium Nitride (GaN) with its wide energy bandgap of 3.4 eV holds excellent promise for solar blind UV detectors. We have successfully designed, fabricated and tested GaN p-i-n detectors and detector arrays. The detectors have a peak responsivity of 0.14A/W at 363 nm (3.42 eV) at room temperature. This corresponds to an internal quantum efficiency of 56%. The responsivity decreases by several orders of magnitude to 0.008 A/W at 400 nm (3.10 eV) giving the excellent visible rejection ratio needed for solar-blind applications.

Pankove, Jacques I.; Torvik, John

1998-01-01

278

The measurement of gamma-emitting radionuclides in beach sand cores of coastal regions of Ramsar, Iran using HPGe detectors.  

PubMed

Radionuclides which present in different beach sands are sources of external exposure that contribute to the total radiation exposure of human. (226)Ra, (235)U, (232)Th, (40)K and (137)Cs analysis has been carried out in sand samples collected at six depth levels, from eight locations of the northern coast of Iran, Ramsar, using high-resolution gamma-ray spectroscopy. The average Specific activities of natural radionuclides viz., (226)Ra, (235)U, (232)Th, (40)K and (137)Cs, in the 0-36 cm depth sand were found as: 19.2±0.04, 2.67±0.17, 17.9±0.06, 337.5±0.61 and 3.35±0.12 Bq kg(-1), respectively. The effects of organic matter content and pH value of sand samples on the natural radionuclide levels were also investigated. Finally, the measured radionuclide concentrations in the Ramsar beach were compared with the world average values, as reported by UNSCEAR (2000). None of the studied beaches were considered as a radiological risk. PMID:23850123

Tari, Marziyeh; Moussavi Zarandi, Sayyed Ali; Mohammadi, Kheirollah; Zare, Mohammad Reza

2013-09-15

279

Compact, inexpensive, high-energy-resolution, room-temperature-operated, semiconductor gamma-ray detectors for isotope identification  

Microsoft Academic Search

Many homeland security applications involving gamma-ray detectors require energy resolution of better than 1%-2% for isotope identification. Existing High-Purity germanium (HPGe) detectors have the needed energy resolution but suffer from large size and the need for liquid-nitrogen or electromechanical cooling. Compact, inexpensive, room-temperature-operated devices are needed for handheld monitors, portal monitors, and monitors for nuclear materials in storage or transit.

P. Ugorowski; A. Ariesanti; D. S. McGregor; A. Kargar

2010-01-01

280

Measurement and calculation of the efficiency of fission detectors designed to monitor the time dependence of the neutron production of JET  

NASA Astrophysics Data System (ADS)

Three pairs of fission counters (each pair one 235U and one 238U) are used at the Joint European Torus to determine the time dependence of the neutron production. In order to determine the absolute value of the neutron flux at the detector location it is necessary to know the neutron detection efficiency of the counter assemblies. This was measured using monoenergetic neutrons (at 2.5 and 14 MeV) and Cf and Am/Be sources. The fraction of fissions detected was determined by extrapolation of the pulse-height spectrum to zero pulse height. The calculation of efficiency was made with the Monte-Carlo neutron transport code MORSE. It was found that the detailed structure of the counter significantly affected the calculated efficiency and that the thermal cross-section values of the DLC37F nuclear data library had to be replaced with room-temperature values. The mean difference between calculation and experiment is (5.5±6.3)%.

Swinhoe, M. T.; Jarvis, O. N.

1985-05-01

281

Experimental investigation of gamma-ray attenuation in Jordanian building materials using HPGe-spectrometer.  

PubMed

The capabilities of some building materials used in Jordan to attenuate gamma radiation were tested. Measurements of the attenuation coefficients of limestone, bricks and concrete have been carried out using a HPGe-spectrometer. Narrow beam technique was used, with a multiple gamma radiation source of different energy lines. Results indicate that variations in the attenuation coefficient for all limestone samples, at the same energy line, are within the experimental uncertainties. On the basis of the results achieved, an empirical formula mu(m)=AE(-0.44) was proposed to calculate attenuation at various incident energies. Limestone of average thickness 7cm was found to stop 75% of a gamma beam of energy 662keV. Meanwhile a brick of effective thickness 7cm was found to stop 60% of the same beam. The total attenuation coefficient of concrete calculated at 1333keV was 11.2m(-1), which is less than that of limestone and bricks. PMID:17368884

Awadallah, Mohammad I; Imran, Mousa M A

2007-01-01

282

Intelligent Detector Design  

SciTech Connect

As the complexity and resolution of imaging detectors increases, the need for detailed simulation of the experimental setup also becomes more important. Designing the detectors requires efficient tools to simulate the detector response and reconstruct the events. We have developed efficient and flexible tools for detailed physics and detector response simulation as well as event reconstruction and analysis. The primary goal has been to develop a software toolkit and computing infrastructure to allow physicists from universities and labs to quickly and easily conduct physics analyses and contribute to detector research and development. The application harnesses the full power of the Geant4 toolkit without requiring the end user to have any experience with either Geant4 or C++, thereby allowing the user to concentrate on the physics of the detector system.

Graf, N.A.; /SLAC

2012-06-11

283

Neutron detector  

DOEpatents

A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.

Stephan, Andrew C. (Knoxville, TN); Jardret; Vincent D. (Powell, TN)

2011-04-05

284

Analytical model for pixellated SPECT detector concepts  

Microsoft Academic Search

Pixellated CZT detectors provide a new opportunity to improve the image quality of SPECT detector systems. Their performance has to he evaluated in terms of resolution and efficiency, in a similar way as done earlier for Nal detectors. We have developed an analytical model for spatial resolution and geometric efficiency of collimators specifically for pixellated CZT based detectors. We derive

Herfried Wieczorek; Andreas Goedicke; Ling Shao; Micheal Petrillo; J. Ye; J. Vesel

2004-01-01

285

Large Area and High Efficiency Photon Counting Imaging Detectors with High Time and Spatial Resolution for Night Time Sensing and Astronomy  

NASA Astrophysics Data System (ADS)

The development of large area photon counting, imaging, timing detectors with high performance has significance for applications in astronomy (such as our sensor on the SAAO SALT 10m telescope), night time remote reconnaissance, airborne/space situational awareness, and high-speed adaptive optics. Sealed tube configurations for optical/IR sensing also have applications in detection of Cherenkov light (RICH), biological single-molecule fluorescence lifetime imaging microscopy and neutron imaging applications. In open faced configurations these devices are important for UV and particle detection in space astrophysics, mass spectroscopy and many time-of flight applications. Currently available devices are limited to sizes of about 5 cm and use either conventional microchannel plates, or dynode multipliers for amplification, coupled coarse pad array readouts. Extension of these schemes to devices as large as 20 cm with high spatial resolution presents significant problems and potentially considerable cost. A collaboration (Large Area Picosecond Photon Detector) of the U. Chicago, Argonne National Laboratory, U.C. Berkeley, U. Hawaii and a number of other institutions has developed novel technologies to realize 20 cm format detectors in open face or sealed tube configurations. One critical component of this development is novel microchannel plates employing borosilicate micro-capillary arrays. The microchannel plates are based on a novel concept where the substrate is constructed from a borosilicate micro-capillary array that is made to function as a microchannel plate by deposition of resistive and secondary emissive layers using atomic layer deposition. The process is relatively inexpensive compared with conventional microchannel plates and allows very large microchannel plates to be produced with pore sizes as small as 10 microns. These provide many performance characteristics typical of conventional microchannel plates, but have been made in sizes up to 20 cm, have low intrinsic background (<0.1 events/sq-cm/sec) and high stability with no observed gain degradation behavior over at least 5 Coul/sq-cm of charge extraction. Initial tests in a 20 cm detector with a cross strip electronic readout have achieved 4k x 4k pixel imaging with single photon sub-ns timing and MHz event rates. In concert with this effort we have made stable, uniform 20 cm bialkali photocathodes with >20% quantum efficiency on borosilicate windows compatible with a large sealed tube device. Other related efforts have also produced small sealed tubes with 30% quantum efficiency GaAs sealed tubes with high resolution imaging and timing that are immediately applicable to current applications, and opaque GaN UV photocathodes directly deposited onto these novel microchannel plates. We will discuss the details and implications of these novel microchannel plates with respect to the realization of novel detectors up to 20 cm format with reasonable cost and performance, robust construction, high flexibility of format and readout, reduction of fabrication effort, dramatically increased lifetime and stability, and their potential applications.

Siegmund, O.; Vallerga, J.; Tremsin, A.; McPhate, J.; Frisch, H.; Elam, J.; Mane, A.; Wagner, R.; Varner, G.

2012-09-01

286

Power and area efficient 4-bit column-level ADC in a CMOS pixel sensor for the ILD vertex detector  

NASA Astrophysics Data System (ADS)

A 48 × 64 pixels prototype CMOS pixel sensor (CPS) integrated with 4-bit column-level, self triggered ADCs for the outer layers of the ILD vertex detector (VTX) was developed and fabricated in a 0.35 ?m CMOS process with a pixel pitch of 35 ?m. The pixel concept combines in-pixel amplification with a correlated double sampling (CDS) operation. The ADCs accommodating the pixel read out in a rolling shutter mode complete the conversion by performing a multi-bit/step approximation. The design was optimised for power saving at sampling frequency. The prototype sensor is currently at the stage of being started testing and evaluation. So what is described is based on post simulation results rather than test data. This 4-bit ADC dissipates, at a 3-V supply and 6.25-MS/s sampling rate, 486 ?W in its inactive mode, which is by far the most frequent. This value rises to 714 ?W in case of the active mode. Its footprint amounts to 35 × 545 ?m2.

Zhang, L.; Morel, F.; Hu-Guo, Ch; Hu, Y.

2013-01-01

287

Application of cadmium-zinc-telluride detectors in U-235 enrichment measurements  

SciTech Connect

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 mostly performed with high-purity germanium (HPGe) detectors, that require cooling to liquid-nitrogen temperatures, thus limiting their utility in field and unattended safeguards measurement applications. NaI scintillation detectors do not require cooling, but their moderate energy resolution (10% at 122 keV) is insufficient in most cases for reliable verification measurements. Semiconductor detectors that operate at room temperature, such as cadmium-zinc-telluride (CdZnTe) detectors, with energy resolution performance reaching 2.0% at 122 keV may complement HPGe detectors for certain safeguards verification applications. The authors used a 5x5x5 mm CdZnTe detector to measure U-235 enrichments ranging from 3% to 75%. They use a spectrum analysis technique that fits U-235, U-238, and U K x-ray response profiles to data in the 89- to 100-keV region of gamma-ray spectrum. From the relative magnitudes of the U-235 and U-238 profiles they determine the U-235 enrichment with an accuracy of about 10% with CdZnTe detectors.

Ruhter, W.D.; Gunnink, R. [Lawrence Livermore National Lab., CA (United States). Nuclear Chemistry Div.

1994-04-01

288

LEDs for Efficient Energy  

ERIC Educational Resources Information Center

Light-emitting diodes (LEDs) are described and three classroom experiments are given, one to prove the, low power requirements and efficiency of LEDs, an LED on-off detector circuit, and the third an LED photoelectric smoke detector. (BB)

Guerin, David A.

1978-01-01

289

Ultraviolet detectors Photon detectors  

E-print Network

such as silicon and gallium arsenide, are making strides in detecting UV radiation--from 400 nm to x-rays, as well and sul- fur dioxide in the iono- sphere, in space-based instrumentation for UV astronomy (see www photoelec- tric or photographic. Photographic detectors are used for imaging high-energy radiation because

290

Effects of Incorrect Interaction Identification on Image Resolution in HPGe Compton Cameras  

Microsoft Academic Search

The performance of Compton imaging systems is limited by the angular uncertainty arising from the detector geometry and spatial resolution [Ordonez et al., 1997 amd 1999], When closely spaced multiple interactions are incorrectly recorded as a single event [Solomon and Ott, 1988], termed \\

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

2006-01-01

291

Analytical model for SPECT detector concepts  

Microsoft Academic Search

Pixellated cadmium-zinc telluride (CZT) detectors, providing higher spatial resolution and energy resolution than current gamma cameras, will improve the image quality of SPECT detector systems. Their performance has to be evaluated in terms of resolution, detector efficiency and image quality in a similar way as has been done earlier for NaI detectors. We have developed an analytical model for spatial

Herfried Wieczorek; Andreas Goedicke

2006-01-01

292

Gammasphere and Orruba:. Dual Detectors for Experimental Structure Studies  

NASA Astrophysics Data System (ADS)

An outstanding question in nuclear structure is the evolution of single-neutron strength in open-shell neutron-rich nuclei. In the near term, accelerated beams of 252Cf fission fragments will be available with the ATLAS facility at Argonne National Laboratory through the CARIBU initiative. To exploit these beams, the Oak Ridge Rutgers University Barrel Array (ORRUBA) of positionsensitive silicon strip detectors is being coupled to the Gammasphere array of Compton-suppressed HPGe detectors. ORRUBA will be supplemented with up to four annular arrays of silicon strip detectors at backward and forward angles. The realization of this effort will enable high resolution studies of single-neutron excitations populated in (d,p) and (d,t) reaction studies in inverse kinematics with open-shell 252Cf fission fragment beams through the coincident detection of ? rays and particles.

Ratkiewicz, A.; Cizewski, J. A.; Hardy, S.; Howard, M. E.; Manning, B.; Shand, C. M.; Pain, S. D.; Bardayan, D. W.; Matoš, M.; Blackmon, J. C.; Carpenter, M. P.; Lister, C. J.; Seweryniak, D.; Zhu, S.; Chipps, K. A.; Jones, K. L.; Kozub, R. L.; Peters, W. A.

2014-09-01

293

Study of the counting efficiency of a WBC setup by using a computational 3D human body library in sitting position based on polygonal mesh surfaces.  

PubMed

A realistic computational 3D human body library, called MaMP and FeMP (Male and Female Mesh Phantoms), based on polygonal mesh surface geometry, has been created to be used for numerical calibration of the whole body counter (WBC) system of the nuclear power plant (NPP) in Doel, Belgium. The main objective was to create flexible computational models varying in gender, body height, and mass for studying the morphology-induced variation of the detector counting efficiency (CE) and reducing the measurement uncertainties. First, the counting room and an HPGe detector were modeled using MCNPX (Monte Carlo radiation transport code). The validation of the model was carried out for different sample-detector geometries with point sources and a physical phantom. Second, CE values were calculated for a total of 36 different mesh phantoms in a seated position using the validated Monte Carlo model. This paper reports on the validation process of the in vivo whole body system and the CE calculated for different body heights and weights. The results reveal that the CE is strongly dependent on the individual body shape, size, and gender and may vary by a factor of 1.5 to 3 depending on the morphology aspects of the individual to be measured. PMID:24562069

Fonseca, T C Ferreira; Bogaerts, R; Lebacq, A L; Mihailescu, C L; Vanhavere, F

2014-04-01

294

Simultaneous Compensation for Attenuation, Scatter and Detector Response for 2DEmission Tomography on Nuclear Waste with Reduced Data  

Microsoft Academic Search

We propose a simultaneous correction including three-dimensionnal detector\\/collimator response, attenuation and diffusion for characterization and appraisal of Nuclear Waste. An Emission Computed Tomography (ECT) imagery was developed in the framework of parallel-hole collimation associated with a HyperPure Germanium (HpGe) detection system. The procedure involves the evaluation of the analytical line spread function (LSF) model with the acquisition of the system

Raphaël Thierry; Jean-Luc Pettier; Laurent Desbat

1999-01-01

295

Determination of full-energy peak efficiency at the center position of a through-hole-type clover detector between 0.05 MeV and 3.2 MeV by source measurements and Monte Carlo simulations.  

PubMed

Full-energy peak efficiency at the center position of a through-hole-type clover detector was determined by the measurement of standard sources and by Monte Carlo simulation. The coincidence summing under the large-solid-angle condition was corrected using Monte Carlo calculation based on the specific decay scheme for (133)Ba, (152,154)Eu, and (56)Co. This allowed the peak efficiency to be extended from 0.05 MeV to 3.2 MeV with an approximate uncertainty of 3%. PMID:24922554

Shima, Yosuke; Hayashi, Hiroaki; Kojima, Yasuaki; Shibata, Michihiro

2014-09-01

296

Layered semiconductor neutron detectors  

DOEpatents

Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

Mao, Samuel S; Perry, Dale L

2013-12-10

297

Particle Detectors  

NASA Astrophysics Data System (ADS)

Preface to the first edition; Preface to the second edition; Introduction; 1. Interactions of particles and radiation with matter; 2. Characteristic properties of detectors; 3. Units of radiation measurements and radiation sources; 4. Accelerators; 5. Main physical phenomena used for particle detection and basic counter types; 6. Historical track detectors; 7. Track detectors; 8. Calorimetry; 9. Particle identification; 10. Neutrino detectors; 11. Momentum measurement and muon detection; 12. Ageing and radiation effects; 13. Example of a general-purpose detector: Belle; 14. Electronics; 15. Data analysis; 16. Applications of particle detectors outside particle physics; 17. Glossary; 18. Solutions; 19. Resumé; Appendixes; Index.

Grupen, Claus; Shwartz, Boris

2008-03-01

298

Particle Detectors  

NASA Astrophysics Data System (ADS)

Preface to the first edition; Preface to the second edition; Introduction; 1. Interactions of particles and radiation with matter; 2. Characteristic properties of detectors; 3. Units of radiation measurements and radiation sources; 4. Accelerators; 5. Main physical phenomena used for particle detection and basic counter types; 6. Historical track detectors; 7. Track detectors; 8. Calorimetry; 9. Particle identification; 10. Neutrino detectors; 11. Momentum measurement and muon detection; 12. Ageing and radiation effects; 13. Example of a general-purpose detector: Belle; 14. Electronics; 15. Data analysis; 16. Applications of particle detectors outside particle physics; 17. Glossary; 18. Solutions; 19. Resumé; Appendixes; Index.

Grupen, Claus; Shwartz, Boris

2011-09-01

299

HIgh Rate X-ray Fluorescence Detector  

SciTech Connect

The purpose of this project was to develop a compact, modular multi-channel x-ray detector with integrated electronics. This detector, based upon emerging silicon drift detector (SDD) technology, will be capable of high data rate operation superior to the current state of the art offered by high purity germanium (HPGe) detectors, without the need for liquid nitrogen. In addition, by integrating the processing electronics inside the detector housing, the detector performance will be much less affected by the typically noisy electrical environment of a synchrotron hutch, and will also be much more compact than current systems, which can include a detector involving a large LN2 dewar and multiple racks of electronics. The combined detector/processor system is designed to match or exceed the performance and features of currently available detector systems, at a lower cost and with more ease of use due to the small size of the detector. In addition, the detector system is designed to be modular, so a small system might just have one detector module, while a larger system can have many â?? you can start with one detector module, and add more as needs grow and budget allows. The modular nature also serves to simplify repair. In large part, we were successful in achieving our goals. We did develop a very high performance, large area multi-channel SDD detector, packaged with all associated electronics, which is easy to use and requires minimal external support (a simple power supply module and a closed-loop water cooling system). However, we did fall short of some of our stated goals. We had intended to base the detector on modular, large-area detectors from Ketek GmbH in Munich, Germany; however, these were not available in a suitable time frame for this project, so we worked instead with pnDetector GmbH (also located in Munich). They were able to provide a front-end detector module with six 100 m^2 SDD detectors (two monolithic arrays of three elements each) along with associated preamplifiers; these detectors surpassed the performance we expected to get from the Ketek detectors, however they are housed in a sealed module, which does not offer the ease of repair and expandability weâ??d hoped to achieve with the Ketek SDDâ??s. Our packaging efforts were quite successful, as we came up with a very compact way to mount the detector and to house the associated electronics, as well as a very effective way to reliably take out the heat (from the electronics as well as the detectorâ??s Peltier coolers) without risk of condensation and without external airflow or vibration, which could create problems for the target applications. While we were able to design compact processing electronics that fit into the detector assembly, they are still at the prototype stage, and would require a significant redesign to achieve product status. We have not yet tested this detector at a synchrotron facility; we do still plan on working with some close contacts at the nearby Stanford Synchrotron Radiation Laboratory (SSRL) to get some testing with the beam (using existing commercial electronics for readout, as the integrated processor is not ready for use).

Grudberg, Peter Matthew [XIA LLC

2013-04-30

300

Electron-Photon Coincidence Calibration Of Photon Detectors  

NASA Technical Reports Server (NTRS)

Absolute and relative detector efficiencies measured. Apparatus uses coincidence-counting techniques to measure efficiency of ultraviolet or vacuum ultraviolet detector at very low radiation intensity. Crossed electron and atomic beams generate photons used to calibrate photon detector. Pulses from electron counter and photon detector(s) processed by standard coincidence-counting techniques. Used to calibrate other detectors or make absolute measurements of incident photon fluxes.

Srivastava, Santosh K.

1988-01-01

301

Performance of IRD-WBC HPGe detection system for low energy photon emitters in lungs.  

PubMed

The Whole Body Counter Facility (WBC) of IRD-CNEN in Brazil has been operating since 1986. The first system installed to perform in vivo measurements of low energy photon emitters radionuclides used Phoswich detectors. In 1998, the WBC unit was upgraded by the installation of an array of four low energy high purity germanium detectors. The performance and suitability of the detection system for lung measurements were evaluated by comparison with the annual dose limits and the detection limits obtained for 238U, 235U, 226Ra and 241Am. This evaluation determined whether the in vivo measurements are adequate. In order to compare the dose limit of 20 mSv y(-1), recommended by the International Commission on Radiological Protection (ICRP), with the in vivo monitoring technique, the minimum detectable intake (MDI) was calculated using the appropriate biokinetic models described in the ICRP Publications. The results were obtained for a single intake through inhalation. The AMAD considered was 5 microm. PMID:14527013

Azeredo, A M G F; Lourenço, M C; Dantas, A L A; Dantas, B M

2003-01-01

302

New setup for the characterisation of the AGATA detectors  

NASA Astrophysics Data System (ADS)

A crucial step in the process of ?-ray tracking is related to the location of the interaction points of all the ?-rays within the AGATA (Advanced GAmma Tracking Array) segmented detectors. This requires a full understanding of the sensitivity of each highly segmented high-purity germanium (HPGe) detectors via the characterisation of the 2D and 3D position response. In this paper, we describe the experimental scanning setup that we developed at Orsay for the AGATA detectors. A collimated 137Cs source on an automated x-y positioning table was used for the front face scanning of the AGATA symmetric prototype detector. The 3D scanning measurement is performed using coincidence techniques based on ?-ray Compton scattering from the AGATA detector into an ancillary coupled detector. In our setup, TOHR (high resolution tomograph developed for small animal imaging) is used as an ancillary detector. The data is collected using TIGRESS cards for digital signal processing. The data flow, readout and storage is NARVAL as used for the full AGATA project. The analysis of the collected data and the obtained results is shown to illustrate our device performances.

Ha, T. M. H.; Korichi, A.; Le Blanc, F.; Désesquelles, P.; Dosme, N.; Grave, X.; Karkour, N.; Leboutelier, S.; Legay, E.; Linget, D.; Travers, B.; Pariset, P.

2013-01-01

303

Radiation detectors in nuclear medicine.  

PubMed

Single-photon-emitting or positron-emitting radionuclides employed in nuclear medicine are detected by using sophisticated imaging devices, whereas simpler detection devices are used to quantify activity for the following applications: measuring doses of radiopharmaceuticals, performing radiotracer bioassays, and monitoring and controlling radiation risk in the clinical environment. Detectors are categorized in terms of function, the physical state of the transducer, or the mode of operation. The performance of a detector is described by the parameters efficiency, energy resolution and discrimination, and dead time. A detector may be used to detect single events (pulse mode) or to measure the rate of energy deposition (current mode). Some detectors are operated as simple counting systems by using a single-channel pulse height analyzer to discriminate against background or other extraneous events. Other detectors are operated as spectrometers and use a multichannel analyzer to form an energy spectrum. The types of detectors encountered in nuclear medicine are gas-filled detectors, scintillation detectors, and semiconductor detectors. The ionization detector, Geiger-Müller detector, extremity and area monitor, dose calibrator, well counter, thyroid uptake probe, Anger scintillation camera, positron emission tomographic scanner, solid-state personnel dosimeter, and intraoperative probe are examples of detectors used in clinical nuclear medicine practice. PMID:10194791

Ranger, N T

1999-01-01

304

Direct Detectors for Electron Microscopy  

NASA Astrophysics Data System (ADS)

There is interest in improving the detectors used to capture images in transmission electron microscopy. Detectors with an improved modulation transfer function at high spatial frequencies allow for higher resolution in images at lower magnification, which leads to an increased effective field of view. Detectors with improved detective quantum efficiency are important for low dose applications. One way in which these performance enhancements can be achieved is through direct detection, where primary electrons are converted directly into suitable electrical signals by the detector rather than relying on an indirect electron to photon conversion before detection. In this paper we present the characterisation of detector performance for a number of different direct detection technologies, and compare these technologies to traditional indirect detectors. Overall our results show that direct detection enables a significant improvement in all aspects of detector performance.

Clough, R. N.; Moldovan, G.; Kirkland, A. I.

2014-06-01

305

Pocked surface neutron detector  

DOEpatents

The detection efficiency, or sensitivity, of a neutron detector material such as of Si, SiC, amorphous Si, GaAs, or diamond is substantially increased by forming one or more cavities, or holes, in its surface. A neutron reactive material such as of elemental, or any compound of, .sup.10 B, .sup.6 Li, .sup.6 LiF, U, or Gd is deposited on the surface of the detector material so as to be disposed within the cavities therein. The portions of the neutron reactive material extending into the detector material substantially increase the probability of an energetic neutron reaction product in the form of a charged particle being directed into and detected by the neutron detector material.

McGregor, Douglas (Whitmore Lake, MI); Klann, Raymond (Bolingbrook, IL)

2003-04-08

306

Transition radiation detectors  

Microsoft Academic Search

The use of transition radiation (TR) as a means of identifying high energy particles has now become a subject of intensive experimental investigations and applications. Our intention is first to study the physics of these phenomena and to describe ways of building detectors which can efficiently identify particles.

Boris Dolgoshein

1993-01-01

307

PET detector modules based on novel detector technologies  

SciTech Connect

A successful PET detector module must identify 511 keV photons with: high efficiency (>85%), high spatial resolution (<5 mm fwhm), low cost (<$600 / in{sup 2}), low dead time (<4 {mu}s in{sup 2}), good timing resolution (<5 ns fwhm for conventional PET, <200 ps fwhm for time of flight), and good energy resolution (<100 keV fwhm), where these requirements are listed in decreasing order of importance. The ``high efficiency`` requirement also implies that the detector modules must pack together without inactive gaps. Several novel and emerging radiation detector technologies could improve the performance of PET detectors. Avalanche photodiodes, PIN photodiodes, metal channel dynode photomultiplier tubes, and new scintillators all have the potential to improve PET detectors significantly.

Moses, W.W.; Derenzo, S.E.; Budinger, T.F.

1994-05-01

308

Smoke Detector  

NASA Technical Reports Server (NTRS)

In the photo, Fire Chief Jay Stout of Safety Harbor, Florida, is explaining to young Richard Davis the workings of the Honeywell smoke and fire detector which probably saved Richard's life and that of his teen-age brother. Alerted by the detector's warning, the pair were able to escape their burning home. The detector in the Davis home was one of 1,500 installed in Safety Harbor residences in a cooperative program conducted by the city and Honeywell Inc.

1979-01-01

309

A Feasibility Study to Determine Cooling Time and Burnup of ATR Fuel Using a Nondestructive Technique and Three Types of Gamma-ray Detectors  

SciTech Connect

A Feasibility Study to Determine Cooling Time and Burnup of ATR Fuel Using a Nondestructive Technique1 Rahmat Aryaeinejad, Jorge Navarro, and David W Nigg Idaho National Laboratory Abstract Effective and efficient Advanced Test Reactor (ATR) fuel management require state of the art core modeling tools. These new tools will need isotopic and burnup validation data before they are put into production. To create isotopic, burn up validation libraries and to determine the setup for permanent fuel scanner system a feasibility study was perform. The study consisted in measuring short and long cooling time fuel elements at the ATR canal. Three gamma spectroscopy detectors (HPGe, LaBr3, and HPXe) and two system configurations (above and under water) were used in the feasibility study. The first stage of the study was to investigate which detector and system configuration would be better suited for different scenarios. The second stage of the feasibility study was to create burnup and cooling time calibrations using experimental isotopic data collected and ORIGEN 2.2 burnup data. The results of the study establish that a better spectra resolution is achieve with an above the water configuration and that three detectors can be used in the permanent fuel scanner system for different situations. In addition it was conclude that a number of isotopic ratios and absolute measurements could be used to predict ATR fuel burnup and cooling times. 1This work was supported by the U.S. Depart¬ment of Energy (DOE) under Battelle Energy Alliance, LLC Contract No. DE-AC07-05ID14517.

Jorge Navarro; Rahmat Aryaeinejad,; David W. Nigg

2011-05-01

310

A mobile antineutrino detector with plastic scintillators  

E-print Network

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.

Yasuhiro Kuroda; Shugo Oguri; Yo Kato; Ryoko Nakata; Yoshizumi Inoue; Chikara Ito; Makoto Minowa

2012-06-28

311

A Scintillation Detector for Fast Neutrons  

Microsoft Academic Search

A fast neutron detector has been prepared by suspending ZnS phosphor powder in ``Bio-Plastic''. The detector can be easily prepared using only simple laboratory equipment. In the presence of the gamma rays from a Ra-Be source, the neutrons from the source can be counted using this detector with about one percent efficiency.

L. W. Seagondollar; K. A. Esch; L. M. CARTWRIGHTt

1954-01-01

312

Response of a LaBr3(Ce) Detector to 2-11 MeV Gamma Rays  

SciTech Connect

The development of lanthanum halide scintillation detectors has great potential application in field-portable prompt-gamma neutron activation analysis systems. Because the low-energy response of these detectors has already been well-characterized [1[-[2], we have measured their response to higher energy gamma rays in the region between 2 and 11 MeV. We have measured the response of a 2-inch (5.08 cm) by 2-inch long LaBr3(Ce) detector to high energy gamma rays produced by neutron interactions on chlorine, hydrogen, iron, nitrogen, phosphorous, and sulfur. The response of the LaBr3(Ce) detector is compared to that of HPGe and NaI(Tl) detectors.

Not Available

2006-10-01

313

Mossbauer spectrometer radiation detector  

NASA Technical Reports Server (NTRS)

A Mossbauer spectrometer with high efficiencies in both transmission and backscattering techniques is described. The device contains a sodium iodide crystal for detecting radiation caused by the Mossbauer effect, and two photomultipliers to collect the radiation detected by the crystal. When used in the transmission technique, the sample or scatterer is placed between the incident radiation source and the detector. When used in a backscattering technique, the detector is placed between the incident radiation source and the sample of scatterer such that the incident radiation will pass through a hole in the crystal and strike the sample. Diagrams of the instrument are provided.

Singh, J. J. (inventor)

1973-01-01

314

Radiation damage of germanium detectors  

NASA Technical Reports Server (NTRS)

Energetic particles can produce interstitial-vacancy pairs in a crystal by knocking the atoms from their normal positions. Detectors are unique among semiconductor devices in depending on very low concentrations of electrically active impurities, and also on efficient transport of holes and electrons over relatively large distances. Because the dense regions of damage produced by energetic particles may result in donors and/or acceptors, and also provide trapping sites for holes and electrons, detectors are very sensitive to radiation damage. In addition to these effects occurring within the detector, radiation may also change the characteristics of the exposed surfaces causing unpredictable effects on the detector leakage current. Radiation-induced surface degradation has rarely, if ever, been observed for germanium detectors. The possibility of minimizing hole trapping in charge collection by the use of a high-purity germanium coaxial detector configured with the p (+) contact on the coaxial periphery is discussed.

Pehl, R. H.

1978-01-01

315

A multiparametric HPGe-NaI acquisition system for low gamma activity measurements of meteorites  

NASA Astrophysics Data System (ADS)

The study of long-term solar activity variations in the past requires the use of radioisotopic data planetary reservoirs. At the Laboratory of Monte dei Cappuccini in Torino (IFSI-Torino, INAF) for many years we have been studying radioisotopes in meteorites, because their production, which is related to galactic cosmic ray flux in the heliosphere, is anticorrelated with the heliospheric magnetic field variations. We have developed very sensitive gamma detection techniques, in particular to measure 44Ti activity in meteorites; due to its half-life (t1/2=59.2 years), this radioisotope is an ideal index to reveal the imprint of solar activity variations on the centennial scale. Recently we have improved the spectrometer by a new multiparametric acquisition system, which allows to extract efficiently the 44Ti peak from the natural background.

Taricco, C.; Bhandari, N.; Colombetti, P.; Mariani, I.; Verma, N.; Vivaldo, G.

316

Detector arrays in spectroscopy  

NASA Astrophysics Data System (ADS)

Spatially dispersed spectra of ions, electrons or photons are traditionally measured by scanning the spectra across a narrow slit behind which is a detector. However, the efficiency increase offered by arrays of detectors is so large that their development is increasingly demanding the attention of spectrometer manufacturers. One-dimensional arrays of independent detectors (discrete electrode arrays) offer the highest data accumulation rate as detection can occur simultaneously at many sites, but a high resolution array of this type requires much associated electronics and this has limited the size and the market of such devices. The design and performance issues relating to discrete electrode arrays are discussed and a new high resolution array with all electronics integrated on a single silicon chip developed at Aberystwyth is described. A familiarity with silicon technology is not required by the reader. It is shown that integration brings not only advantages of scale but also of performance.

Birkinshaw, K.

317

Imaging MAMA detector systems  

NASA Astrophysics Data System (ADS)

Imaging multianode microchannel array (MAMA) detector systems with 1024 x 1024 pixel formats have been produced for visible and UV wavelengths; the UV types employ 'solar blind' photocathodes whose detective quantum efficiencies are significantly higher than those of currently available CCDs operating at far-UV and EUV wavelengths. Attention is presently given to the configurations and performance capabilities of state-of-the-art MAMA detectors, with a view to the development requirements of the hybrid electronic circuits needed for forthcoming spacecraft-sensor applications. Gain, dark noise, uniformity, and dynamic range performance data are presented for the curved-channel 'chevron', 'Z-plate', and helical-channel high gain microchannel plate configurations that are currently under evaluation with MAMA detector systems.

Slater, David C.; Timothy, J. G.; Morgan, Jeffrey S.; Kasle, David B.

1990-07-01

318

Continuum Background in Space-Borne Gamma-Ray Detectors  

NASA Technical Reports Server (NTRS)

The background measured with space-borne gamma-ray spectrometers (GRS) in the 100 keV-10 MeV energy region consists of both discrete lines and continuum. The discrete lines originate in the decay of radioactive species. The continuum originates from a number of different processes and can be an important factor in the detection, for example, of weak gamma-ray lines from a planetary surface. Measurements of the gamma-ray background have been made during the cruise portion of a number of planetary missions. The three missions described here are the Apollo 15 and 16 missions each of which carried a 7 cm x 7 cm NaI scintillation detector, the Mars Observer (MO) mission which used a 5.5 cm X 5.5 cm high-purity germanium (HPGe) detector, and the Near Earth Rendezvous Asteroid (NEAR) mission that has a 2.54 cm x 7.6 cm NaI detector. A comparison of the intensity and spectral shape of these background spectra can be useful to help understand how these backgrounds vary with spacecraft size, detector position, and detector size. The use of shields to reduce the background components on these three missions is a test of the effectiveness of different shield designs.

Evans, Larry G.; Trombka, Jacob I; Starr, Richard; Boyton, William V.; Bailey, S.

1997-01-01

319

The CLIC Vertex Detector  

NASA Astrophysics Data System (ADS)

The precision physics needs at TeV-scale linear electron-positron colliders (ILC and CLIC) require a vertex-detector system with excellent flavour-tagging capabilities through a measurement of displaced vertices. This is essential, for example, for an explicit measurement of the Higgs decays to pairs of b-quarks, c-quarks and gluons. Efficient identification of top quarks in the decay t ? Wb will give access to the ttH-coupling measurement. In addition to those requirements driven by physics arguments, the CLIC bunch structure calls for hit timing at the few-ns level. As a result, the CLIC vertex-detector system needs to have excellent spatial resolution, full geometrical coverage extending to low polar angles, extremely low material budget, low occupancy facilitated by time-tagging, and sufficient heat removal from sensors and readout. These considerations challenge current technological limits. A detector concept based on hybrid pixel-detector technology is under development for the CLIC vertex detector. It comprises fast, low-power and small-pitch readout ASICs implemented in 65 nm CMOS technology (CLICpix) coupled to ultra-thin planar or active HV-CMOS sensors via low-mass interconnects. The power dissipation of the readout chips is reduced by means of power pulsing, allowing for a cooling system based on forced gas flow. This contribution reviews the requirements and design optimisation for the CLIC vertex detector and gives an overview of recent R&D achievements in the domains of sensors, readout and detector integration.

Dannheim, D.

2015-03-01

320

Novel neutron detectors  

NASA Astrophysics Data System (ADS)

A new set of thermal neutron detectors has been developed as a near term 3He tube replacement. The zinc oxide scintillator is an ultrafast scintillator which can be doped to have performance equal to or superior to 3He tubes. Originally investigated in the early 1950s, this room temperature semiconductor has been evaluated as a thermal neutron scintillator. Zinc oxide can be doped with different nuclei to tune the band gap, improve optical clarity, and improve the thermal neutron detection efficiency. The effects of various dopant effects on the scintillation properties, materials properties, and crystal growth parameters have been analyzed. Two different growth modalities were investigated: bulk melt grown materials as well as thin film scintillators grown by metalorganic chemical vapor deposition (MOCVD). MOCVD has shown significant advantages including precise thickness control, high dopant incorporation, and epitaxial coatings of neutron target nuclei. Detector designs were modeled and simulated to design an improved thermal neutron detector using doped ZnO layers, conformal coatings and light collection improvements including Bragg reflectors and photonic crystal structures. The detectors have been tested for crystalline quality by XRD and FTIR spectroscopy, for scintillation efficiency by photo-luminescence spectroscopy, and for neutron detection efficiency by alpha and neutron radiation tests. Lastly, a novel method for improving light collection efficiency has been investigated, the creation of a photonic crystal scintillator. Here, the flow of optical light photons is controlled through an engineered structure created with the scintillator materials. This work has resulted in a novel radiation detection material for the near term replacement of 3He tubes with performance characteristics equal to or superior to that of 3He.

Burgett, Eric Anthony

321

The detector control system of the LHCb RICH detector  

Microsoft Academic Search

The LHCb experiment at the Large Hadron Collider (LHC) is dedicated to the study of b-quark properties. A key element of the LHCb detector is particle identification, a task performed by the ring imaging Cherenkov (RICH) subsystem. Efficient particle identification over the full momentum range of 1 to 100 GeV\\/c requires an extensive system of detector control and monitoring. The

F. Fontanelli

2005-01-01

322

Multi-layer boron thin-film detectors for neutrons  

Microsoft Academic Search

Intrinsic efficiencies of the multilayer boron detectors have been examined both theoretically and experimentally. It is shown that due to the charge loss in the boron layers, the practical efficiencies of most multi-layer ¹°B detectors are limited up to about 42%, much less than 77% of the 2 bar 2-inch diameter ³He detectors. It is suggested that the same charge

Zhehui Wang; Christopher L Morris

2010-01-01

323

New detectors for the kaon and hypernuclear experiments with KaoS at MAMI and with PANDA at GSI  

E-print Network

The KaoS spectrometer at the Mainz Microtron MAMI, Germany, is perceived as the ideal candidate for a dedicated spectrometer in kaon and hypernuclei electroproduction. KaoS will be equipped with new read-out electronics, a completely new focal plane detector package consisting of scintillating fibres, and a new trigger system. First prototypes of the fibre detectors and the associated new front-end electronics are shown in this contribution. The Mainz hypernuclei research program will complement the hypernuclear experiments at the planned FAIR facility at GSI, Germany. At the proposed antiproton storage ring the spectroscopy of double Lambda hypernuclei is one of the four main topics which will be addressed by the PANDA Collaboration. The experiments require the operation of high purity germanium (HPGe) detectors in high magnetic fields (B= 1T) in the presence of a large hadronic background. The performance of high resolution Ge detectors in such an environment has been investigated.

P. Achenbach; C. Ayerbe Gayoso; R. Böhm; M. O. Distler; J. Friedrich; K. W. Krygier; H. Merkel; U. Müller; R. Neuhausen; L. Nungesser; J. Pochodzalla; A. Sanchez Lorente; S. Sánchez Majos; Th. Walcher; J. Gerl; M. Kavatsyuk; I. Kojouhavorv; N. Saito; T. R. Saito; H. Schaffner; T. Bressani; S. Bufalino; A. Feliciello; A. Pantaleo; M. Palomba; G. Raciti; C. Sfienti; M. Agnello; F. Ferro; F. Iazzi; K. Szymanska; P. -E. Tegnér; B. Cederwall; L. Majling

2006-05-31

324

Neutron detectors comprising boron powder  

DOEpatents

High-efficiency neutron detector substrate assemblies comprising a first conductive substrate, wherein a first side of the substrate is in direct contact with a first layer of a powder material comprising .sup.10boron, .sup.10boron carbide or combinations thereof, and wherein a conductive material is in proximity to the first layer of powder material; and processes of making said neutron detector substrate assemblies.

Wang, Zhehui; Morris, Christopher; Bacon, Jeffrey Darnell; Makela, Mark F; Spaulding, Randy Jay

2013-05-21

325

Characteristics of Signals Originating near the Lithium-Diffused N+ Contact of High Purity Germanium P-Type Point Contact Detectors  

SciTech Connect

A study of signals originating near the lithium-diffused n+ contact of p-type point contact (PPC) high purity germanium detectors (HPGe) is presented. The transition region between the active germanium and the fully dead layer of the n+ contact is examined. Energy depositions in this transition region are shown to result in partial charge collection. This provides a mechanism for events with a well defined energy to contribute to the continuum of the energy spectrum at lower energies. A novel technique to quantify the contribution from this source of background is introduced. Experiments that operate germanium detectors with a very low energy threshold may benefit from the methods presented herein.

Aguayo, E. [Pacific Northwest National Laboratory (PNNL); Amman, M. [Lawrence Berkeley National Laboratory (LBNL); Avignone, F. T. [University of South Carolina/ORNL; Barabash, A.S. [Institute of Theoretical & Experimental Physics, Moscow, Russia; Barton, P. J. [Lawrence Berkeley National Laboratory (LBNL); Beene, James R [ORNL; Bertrand Jr, Fred E [ORNL; Boswell, M. [Los Alamos National Laboratory (LANL); Brudanin, V. [Joint Institute for Nuclear Research, Dubna, Russia; Busch, M. [Duke University; Chan, Y-D [Lawrence Berkeley National Laboratory (LBNL); Christofferson, C. D. [South Dakota School of Mines & Technology, Rapid City, SD; Collar, Juan I. [University of Chicago; Combs, D. C. [University of North Carolina / Triangle Universities Nuclear Lababoratory, Durham; Cooper, Reynold J [ORNL; Detwiler, J.A. [Lawrence Berkeley National Laboratory (LBNL); Doe, P. J. [University of Washington; Efremenko, Yuri [University of Tennessee (UTK) and Oak Ridge National Laboratory (ORNL); Egorov, V. [Joint Institute for Nuclear Research, Dubna, Russia; Ejiri, H. [Osaka University; Elliott, S. R. [Los Alamos National Laboratory (LANL); Esterline, J. [Duke University; Fast, J.E. [Pacific Northwest National Laboratory (PNNL); Fields, N. [University of Chicago; Finnerty, P. [University of North Carolina / Triangle Universities Nuclear Lababoratory, Durham; Fraenkle, F. M. [University of North Carolina / Triangle Universities Nuclear Lababoratory, Durham; Galindo-Uribarri, Alfredo {nmn} [ORNL; Gehman, V. M. [Los Alamos National Laboratory (LANL); Giovanetti, G. K. [Univ, of North Carolina & Triangle Universities Nucl. Lab - Durham, NC; Green, M. P. [University of North Carolina / Triangle Universities Nuclear Lababoratory, Durham; Guiseppe, V.E. [University of South Dakota; Gusey, K. [Joint Institute for Nuclear Research, Dubna, Russia; Hallin, A. L. [University of Alberta, Edmonton, Canada; Hazama, R. [Osaka University; Henning, R. [Univ, of North Carolina & Triangle Universities Nucl. Lab - Durham, NC; Hoppe, E.W. [Pacific Northwest National Laboratory (PNNL); Horton, M. [South Dakota School of Mines & Technology, Rapid City, SD; Howard, S. [South Dakota School of Mines and Technology; Howe, M. A. [University of North Carolina / Triangle Universities Nuclear Lababoratory, Durham; Johnson, R. A. [University of Washington, Seattle; Keeter, K.J. [Black Hills State University, Spearfish, SD; Kidd, M. F. [Los Alamos National Laboratory (LANL); Knecht, A. [University of Washington, Seattle; Kochetov, O. [Joint Institute for Nuclear Research, Dubna, Russia; Konovalov, S.I. [Institute of Theoretical & Experimental Physics, Moscow, Russia; Kouzes, R. T. [Pacific Northwest National Laboratory (PNNL); LaFerriere, B. D. [Pacific Northwest National Laboratory (PNNL); Leon, J. [University of Washington, Seattle; Leviner, L. E. [University of North Carolina / Triangle Universities Nuclear Lababoratory, Durham; Loach, J.C. [Lawrence Berkeley National Laboratory (LBNL); Looker, Q. [Lawrence Berkeley National Laboratory (LBNL); Luke, P.N. [Lawrence Berkeley National Laboratory (LBNL); MacMullin, S. [University of North Carolina / Triangle Universities Nuclear Lababoratory, Durham; Marino, M. G. [University of Washington, Seattle; Martin, R.D. [Lawrence Berkeley National Laboratory (LBNL); Merriman, J. H. [Pacific Northwest National Laboratory (PNNL); Miller, M. L. [University of Washington, Seattle; Mizouni, L. [PPNL/Univ. of South Carolina; Nomachi, M. [Osaka University; Orrell, John L. [Pacific Northwest National Laboratory (PNNL); Overman, N. R. [Pacific Northwest National Laboratory (PNNL); Perumpilly, G. [University of South Dakota; Phillips II, D. G. [University of North Carolina / Triangle Universities Nuclear Lababoratory, Durham; Poon, A.W.P. [Lawrence Berkeley National Laboratory (LBNL); et al.

2013-01-01

326

Characteristics of Signals Originating Near the Lithium-Diffused N+ Contact of High Purity Germanium P-Type Point Contact Detectors  

E-print Network

A study of signals originating near the lithium-diffused n+ contact of p-type point contact (PPC) high purity germanium detectors (HPGe) is presented. The transition region between the active germanium and the fully dead layer of the n+ contact is examined. Energy depositions in this transition region are shown to result in partial charge collection. This provides a mechanism for events with a well defined energy to contribute to the continuum of the energy spectrum at lower energies. A novel technique to quantify the contribution from this source of background is introduced. Experiments that operate germanium detectors with a very low energy threshold may benefit from the methods presented herein.

The MAJORANA Collaboration; E. Aguayo; M. Amman; F. T. Avignone III; A. S. Barabash; P. J. Barton; J. R. Beene; F. E. Bertrand; M. Boswell; V. Brudanin; M. Busch; Y-D. Chan; C. D. Christofferson; J. I. Collar; D. C. Combs; R. J. Cooper; J. A. Detwiler; P. J. Doe; Yu. Efremenko; V. Egorov; H. Ejiri; S. R. Elliott; J. Esterline; J. E. Fast; N. Fields; P. Finnerty; F. M. Fraenkle; A. Galindo-Uribarri; V. M. Gehman; G. K. Giovanetti; M. P. Green; V. E. Guiseppe; K. Gusey; A. L. Hallin; R. Hazama; R. Henning; E. W. Hoppe; M. Horton; S. Howard; M. A. Howe; R. A. Johnson; K. J. Keeter; M. F. Kidd; A. Knecht; O. Kochetov; S. I. Konovalov; R. T. Kouzes; B. D. LaFerriere; J. Leon; L. E. Leviner; J. C. Loach; Q. Looker; P. N. Luke; S. MacMullin; M. G. Marino; R. D. Martin; J. H. Merriman; M. L. Miller; L. Mizouni; M. Nomachi; J. L. Orrell; N. R. Overman; G. Perumpilly; D. G. Phillips II; A. W. P. Poon; D. C. Radford; K. Rielage; R. G. H. Robertson; M. C. Ronquest; A. G. Schubert; T. Shima; M. Shirchenko; K. J. Snavely; D. Steele; J. Strain; V. Timkin; W. Tornow; R. L. Varner; K. Vetter; K. Vorren; J. F. Wilkerson; E. Yakushev; H. Yaver; A. R. Young; C. -H. Yu; V. Yumatov

2012-07-28

327

Pyroelectric detectors  

NASA Technical Reports Server (NTRS)

The multi-agency, long-term Global Change programs, and specifically NASA's Earth Observing system, will require some new and advanced photon detector technology which must be specifically tailored for long-term stability, broad spectral range, cooling constraints, and other parameters. Whereas MCT and GaAs alloy based photovoltaic detectors and detector arrays reach most impressive results to wavelengths as long as 12 microns when cooled to below 70 K, other materials, such as ferroelectrics and pyroelectrics, appear to offer special opportunities beyond 12 microns and above 70 K. These materials have found very broad use in a wide variety of room temperature applications. Little is known about these classes of materials at sub-room temperatures and no photon detector results have been reported. From the limited information available, researchers conclude that the room temperature values of D asterisk greater than or equal to 10(exp 9) cm Hz(exp 1/2)/W may be improved by one to two orders of magnitude upon cooling to temperatures around 70 K. Improvements of up to one order of magnitude appear feasible for temperatures achievable by passive cooling. The flat detector response over a wavelength range reaching from the visible to beyond 50 microns, which is an intrinsic advantage of bolometric devices, makes for easy calibration. The fact that these materials have been developed for reduced temperature applications makes ferro- and pyroelectric materials most attractive candidates for serious exploration.

Haller, Eugene E.; Beeman, Jeffrey; Hansen, William L.; Hubbard, G. Scott; Mcmurray, Robert E., Jr.

1990-01-01

328

MAMA Detector  

NASA Technical Reports Server (NTRS)

Work carried out under this grant led to fundamental discoveries and over one hundred publications in the scientific literature. Fundamental developments in instrumentation were made including all the instrumentation on the EUVE satellite, the invention of a whole new type of grazing instrument spectrometer and the development of fundamentally new photon counting detectors including the Wedge and Strip used on EUVE and many other missions and the Time Delay detector used on OREFUS and FUSE. The Wedge and Strip and Time Delay detectors were developed under this grant for less than two million dollars and have been used in numerous missions most recently for the FUSE mission. In addition, a fundamentally new type of diffuse spectrometer has been developed under this grant which has been used in instrumentation on the MMSAT spacecraft and the Lewis spacecraft. Plans are underway to use this instrumentation on several other missions as well.

Bowyer, Stuart

1998-01-01

329

Hydrogen detector  

DOEpatents

A hydrogen detector of the type in which the interior of the detector is partitioned by a metal membrane into a fluid section and a vacuum section. Two units of the metal membrane are provided and vacuum pipes are provided independently in connection to the respective units of the metal membrane. One of the vacuum pipes is connected to a vacuum gauge for static equilibrium operation while the other vacuum pipe is connected to an ion pump or a set of an ion pump and a vacuum gauge both designed for dynamic equilibrium operation.

Kanegae, Naomichi (Mito, JP); Ikemoto, Ichiro (Mito, JP)

1980-01-01

330

Microwave detector  

DOEpatents

A microwave detector (10) is provided for measuring the envelope shape of a microwave pulse comprised of high-frequency oscillations. A biased ferrite (26, 28) produces a magnetization field flux that links a B-dot loop (16, 20). The magnetic field of the microwave pulse participates in the formation of the magnetization field flux. High-frequency insensitive means (18, 22) are provided for measuring electric voltage or current induced in the B-dot loop. The recorded output of the detector is proportional to the time derivative of the square of the envelope shape of the microwave pulse.

Meldner, Heiner W. (Moss Beach, CA); Cusson, Ronald Y. (Chapel Hill, NC); Johnson, Ray M. (San Ramon, CA)

1986-01-01

331

Microwave detector  

DOEpatents

A microwave detector is provided for measuring the envelope shape of a microwave pulse comprised of high-frequency oscillations. A biased ferrite produces a magnetization field flux that links a B-dot loop. The magnetic field of the microwave pulse participates in the formation of the magnetization field flux. High-frequency insensitive means are provided for measuring electric voltage or current induced in the B-dot loop. The recorded output of the detector is proportional to the time derivative of the square of the envelope shape of the microwave pulse.

Meldner, H.W.; Cusson, R.Y.; Johnson, R.M.

1985-02-08

332

Rapid HPGE gamma spectroscopic mapping of transuranic and high energy gamma ray-emitting radionuclides for remediation planning  

SciTech Connect

Tank W-1A collected liquid wastes from several high radiation level facilities at the Oak Ridge National Laboratory. Previous environmental samples taken in the general area, particularly at Corehole 8, indicated radiological contamination in adjacent soil. The purpose of this characterization project was to generate three-dimensional maps of the extent of contamination in soil around the tank in order to estimate the volume of transuranic waste (TRU) and low level waste (LLW) for disposal and to plan the remediation operation. A dynamic sampling plan was implemented in which results from each round of sampling determined which subsequent locations would be sampled. This plan maximized the value of data obtained while minimizing project costs and risk. To be effective, dynamic sampling requires that analytical results be available very rapidly. Geo-probe dual-tube soil sampling was used to collect soil cores up to 76 cm long. These cores were immediately brought to two adjacent high purity germanium (HPGe) gamma spectroscopy stations utilizing the In Situ Object Counting System (ISOCS) for quantitative analysis of gamma-emitting radionuclide activity levels. Typically, a 38-cm long core segment was measured for 15 minutes, and the results were reported within 30 minutes, satisfying the requirement for rapid turnaround times. The primary detected radioactive contaminants were {sup 241}Am, {sup 137}Cs, {sup 152}Eu, {sup 154}Eu, and daughters of {sup 232}U, {sup 233}U, and {sup 232}Th. The quantification of {sup 241}Am in the presence of high concentrations of {sup 137}Cs presented some special challenges since Compton effect from the 662 keV {sup 137}Cs gamma rays raised the detection limits in the area of the characteristic 59.5 keV gamma line of {sup 241}Am. This problem was solved using customized counting geometries, lead shielding, and collimators. It was possible to quantify 1.7 x 10{sup 3} Bq/g of {sup 241}Am in the presence of 7.8 x 10{sup 5} Bq/g of {sup 137}Cs. Detection limits for {sup 241}Am were typically less than 370 Bq/g. Transuranic radionuclide detection limits as a function of {sup 137}Cs activity concentration were compared for similar projects using geometries including 150 g sludge samples and 55 gallon waste drums. (authors)

Meyer, K.; Remington, D.L.; Wojtaszek, P.A. [CANBERRA Industries, Inc., Greenwood Village, Colorado (United States)

2007-07-01

333

Vertex detectors  

SciTech Connect

The purpose of a vertex detector is to measure position and angles of charged particle tracks to sufficient precision so as to be able to separate tracks originating from decay vertices from those produced at the interaction vertex. Such measurements are interesting because they permit the detection of weakly decaying particles with lifetimes down to 10{sup {minus}13} s, among them the {tau} lepton and charm and beauty hadrons. These two lectures are intended to introduce the reader to the different techniques for the detection of secondary vertices that have been developed over the past decades. The first lecture includes a brief introduction to the methods used to detect secondary vertices and to estimate particle lifetimes. It describes the traditional technologies, based on photographic recording in emulsions and on film of bubble chambers, and introduces fast electronic registration of signals derived from scintillating fibers, drift chambers and gaseous micro-strip chambers. The second lecture is devoted to solid state detectors. It begins with a brief introduction into semiconductor devices, and then describes the application of large arrays of strip and pixel diodes for charged particle tracking. These lectures can only serve as an introduction the topic of vertex detectors. Time and space do not allow for an in-depth coverage of many of the interesting aspects of vertex detector design and operation.

Lueth, V.

1992-07-01

334

Detector Detail  

NSDL National Science Digital Library

This game requires users to match the â??shower shapesâ? and the energies of particles produced in a particle collision. There is also a movie (or animated gif) in the Calorimetry section which allows students to see the workings of the detector. It is part of a collection of games that allows students to explore concepts in particle physics.

335

Radiation detector  

SciTech Connect

A radiation detector adapted to be used with a computerized tomographic apparatus, wherein filters prepared from a radiation-absorbing material are provided on the outside of a radiation-permeable window in the positions facing radiation-detecting cells. The filters compensate for differences between the radiation-detecting properties of the detection cells, thereby equalizing said radiation-detecting properties.

Rifu, T.

1984-10-16

336

Terahertz sources and detectors  

NASA Astrophysics Data System (ADS)

Through the support of the US Army Research Office we are developing terahertz sources and detectors suitable for use in the spectroscopy of chemical and biological materials as well as for use in imaging systems to detect concealed weapons. Our technology relies on nonlinear diodes to translate the functionality achieved at microwave frequencies to the terahertz band. Basic building blocks that have been developed for this application include low-noise mixers, frequency multipliers, sideband generators and direct detectors. These components rely on planar Schottky diodes and integrated diode circuits and are therefore easy to assemble and robust. They require no mechanical tuners to achieve high efficiency and broad bandwidth. This paper will review the range of performance that has been achieved with these terahertz components and briefly discuss preliminary results achieved with a spectroscopy system and the development of sources for imaging systems.

Crowe, Thomas W.; Porterfield, David W.; Hesler, Jeffrey L.; Bishop, William L.; Kurtz, David S.; Hui, Kai

2005-05-01

337

Leak detector  

NASA Technical Reports Server (NTRS)

A detector for sensing a leaking of fluid pressures is reported. The detector is characterized by an hermetically sealed housing confining therewithin a first normalized pressure, a connector for coupling the housing in direct communication with a suspected leak established within a substantially sealed body, an electrical circuit having a first or normalized configuration and including a pair of circuit completing electrical contacts and means mounting at least one contact of said pair of contacts on a flexible wall of the housing supporting the contact for movement from a first position along a linear path to a second position in response to an altering of the pressure confined within the housing for thereby altering the configuration of the circuit.

Sawyer, J. T. (inventor)

1975-01-01

338

Flame Detector  

NASA Technical Reports Server (NTRS)

Scientific Instruments, Inc. has now developed a second generation, commercially available instrument to detect flames in hazardous environments, typically refineries, chemical plants and offshore drilling platforms. The Model 74000 detector incorporates a sensing circuit that detects UV radiation in a 100 degree conical field of view extending as far as 250 feet from the instrument. It operates in a bandwidth that makes it virtually 'blind' to solar radiation while affording extremely high sensitivity to ultraviolet flame detection. A 'windowing' technique accurately discriminates between background UV radiation and ultraviolet emitted from an actual flame, hence the user is assured of no false alarms. Model 7410CP is a combination controller and annunciator panel designed to monitor and control as many as 24 flame detectors. *Model 74000 is no longer being manufactured.

1990-01-01

339

THE 15 LAYER SILICON DRIFT DETECTOR TRACKER IN EXPERIMENT 896.  

SciTech Connect

Large linear silicon drift detectors have been developed and are in production for use in several experiments. Recently 15 detectors were used as a tracking device in BNL-AGS heavy ion experiment (E896). The detectors were successfully operated in a 6.2 T magnetic field. The behavior of the detectors, such as drift uniformity, resolution, and charge collection efficiency are presented. The effect of the environment on the detector performance is discussed. Some results from the experimental run are presented. The detectors performed well in an experimental environment. This is the first tracking application of these detectors.

PANDY,S.U.

1998-11-08

340

Neutrino Detectors  

NASA Astrophysics Data System (ADS)

The neutrino was postulated by Wolfgang Pauli in the early 1930s, but could only be detected for the first time in the 1950s. Ever since scientists all around the world have worked on the detection and understanding of this particle which so scarcely interacts with matter. Depending on the origin and nature of the neutrino, various types of experiments have been developed and operated. In this entry, we will review neutrino detectors in terms of neutrino energy and associated detection technique as well as the scientific outcome of some selected examples. After a brief historical introduction, the detection of low-energy neutrinos originating from nuclear reactors or from the Earth is used to illustrate the principles and difficulties which are encountered in detecting neutrinos. In the context of solar neutrino spectroscopy, where the neutrino is used as a probe for astrophysics, three different types of neutrino detectors are presented - water ?erenkov, radiochemical, and liquid-scintillator detectors. Moving to higher neutrino energies, we discuss neutrinos produced by astrophysical sources and from accelerators. The entry concludes with an overview of a selection of future neutrino experiments and their scientific goals.

von Feilitzsch, Franz; Lanfranchi, Jean-Côme; Wurm, Michael

341

PET detector modules based on novel detector technologies  

Microsoft Academic Search

A successful PET detector module must identify 511 keV photons with: high efficiency (> 85%), high spatial resolution (< 5 mm fwhm), low cost (<$600\\/in.2), low dead time (< 4 mus in.2), good timing resolution (< 5 ns fwhm for conventional PET, < 200 ps fwhm for time of flight), and good energy resolution (< 100 keV fwhm), where these

William W. Moses; Stephen E. Derenzo; Thomas F. Budinger

1994-01-01

342

CZT pixel detectors for improved SPECT imaging  

Microsoft Academic Search

CZT pixel detectors show interesting capabilities for SPECT imaging. They combine a high energy resolution, good detection efficiency and a very good intrinsic spatial resolution. As these performances are superior to those obtained with scintillation detectors, a resulting improvement of image quality is expected. However, SPECT imaging performances are mostly limited by the collimation geometry and CZT based imagers cannot

Guillaume Montemont; Thomas Bordy; Veronique Rebuffel; Charlotte Robert; Loick Verger

2008-01-01

343

Improved Scintillator Materials for Compact Electron Antineutrino Detectors  

SciTech Connect

Developments in the fields of chemistry and materials science provide new components that hold the potential to improve the performance of liquid scintillation electron antineutrino detectors used for the monitoring of nuclear reactors. New compounds can provide for more efficient, stable, and safer operation of these detectors. Current detectors and their detector materials raise issues regarding size, quantum efficiency, stability, and spatial resolution for the vertex detection. For compact detectors (1 m{sup 3} active volume) improvement of these issues with existing liquid scintillation cocktails can be obtained by means of developing stable and efficient neutron capture agents. These agents comprise of boron or lithium containing coordination compounds, in addition advances in fluorescence detection technologies and optimization of solvent characteristics can improve the overall efficiency. Focus points of the new detector material design are to enable a compact, robust, and direction sensitive electron antineutrino detector.

Dijkstra, Peter; Wortche, Heinrich J. [INCAS3 (Innovative Centre for Advanced Sensors and Sensor Systems), P.O. Box 797, 9400AT, Assen (Netherlands); Browne, Wesley R. [Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands)

2011-04-27

344

Detector requirements for space infrared astronomy  

NASA Technical Reports Server (NTRS)

Requirements for background-limited (BLIP) detectors are discussed in terms of number of photons falling on each pixel, dark current, high detective quantum efficiencies, large numbers of pixels, and array size.

Wright, E. L.

1986-01-01

345

Pillar Structured Thermal Neutron Detector  

SciTech Connect

This work describes an innovative solid state device structure that leverages advanced semiconductor fabrication technology to produce an efficient device for thermal neutron detection which we have coined the 'Pillar Detector'. State-of-the-art thermal neutron detectors have shortcomings in simultaneously achieving high efficiency, low operating voltage while maintaining adequate fieldability performance. By using a three dimensional silicon PIN diode pillar array filled with isotopic {sup 10}boron ({sup 10}B), a high efficiency device is theoretically possible. Here we review the design considerations for going from a 2-D to 3-D device and discuss the materials trade-offs. The relationship between the geometrical features and efficiency within our 3-D device is investigated by Monte Carlo radiation transport method coupled with finite element drift-diffusion carrier transport simulations. To benchmark our simulations and validate the predicted efficiency scaling, experimental results of a prototype device are illustrated. The fabricated pillar structures reported in this work are composed of 2 {micro}m diameter silicon pillars with a 2 {micro}m spacing and pillar height of 12 {micro}m. The pillar detector with a 12 {micro}m height achieved a thermal neutron detection efficiency of 7.3% at a reverse bias of -2 V.

Nikolic, R; Conway, A; Reinhardt, C; Graff, R; Wang, T; Deo, N; Cheung, C

2008-06-10

346

Flexible composite radiation detector  

DOEpatents

A flexible composite scintillator was prepared by mixing fast, bright, dense rare-earth doped powdered oxyorthosilicate (such as LSO:Ce, LSO:Sm, and GSO:Ce) scintillator with a polymer binder. The binder is transparent to the scintillator emission. The composite is seamless and can be made large and in a wide variety of shapes. Importantly, the composite can be tailored to emit light in a spectral region that matches the optimum response of photomultipliers (about 400 nanometers) or photodiodes (about 600 nanometers), which maximizes the overall detector efficiency.

Cooke, D. Wayne (Santa Fe, NM); Bennett, Bryan L. (Los Alamos, NM); Muenchausen, Ross E. (Los Alamos, NM); Wrobleski, Debra A. (Los Alamos, NM); Orler, Edward B. (Los Alamos, NM)

2006-12-05

347

Neutrinoless double-{beta} decay of {sup 76}Ge: First results from the International Germanium Experiment (IGEX) with six isotopically enriched detectors  

SciTech Connect

The International Germanium Experiment (IGEX) has six HPGe detectors, isotopically enriched to 86{percent} in {sup 76}Ge, containing approximately 90 active moles of {sup 76}Ge. Three detectors of 2 kg each operate in the Canfranc Underground Laboratory (Spain) with pulse-shape analysis electronics. One detector ({approximately}0.7 kg active volume) has been operating in the Baksan Low-Background Laboratory for several years, and two additional similar detectors will operate in Baksan. A maximum likelihood analysis of 74.84 active mole years of data yields a lower bound T{sub 1/2}{sup 0{nu}}{ge}0.8{times}10{sup 25}yr (90{percent} C.L.), corresponding to {l_angle}m{sub {nu}}{r_angle}{lt}(0.5{endash}1.5)eV, depending on the theoretical nuclear matrix elements used to extract the neutrino mass parameter. {copyright} {ital 1999} {ital The American Physical Society}

Aalseth, C.E.; Avignone, F.T. III; Collar, J.I.; Hasenbalg, F. [University of South Carolina, Columbia, South Carolina 29208 (United States)] [University of South Carolina, Columbia, South Carolina 29208 (United States); Brodzinski, R.L.; Hensley, W.K.; Miley, H.S.; Reeves, J.H. [Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)] [Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Garcia, E.; Gonzalez, D.; Morales, A.; Morales, J.; Ortiz de Solorzano, A.; Puimedon, J.; Salinas, A.; Sarsa, M.L.; Villar, J.A. [University of Zaragoza, 50009 Zaragoza (Spain)] [University of Zaragoza, 50009 Zaragoza (Spain); Kirpichnikov, I.V.; Starostin, A.S.; Vasenko, A.A. [Institute for Theoretical and Experimental Physics, 117259 Moscow (Russia)] [Institute for Theoretical and Experimental Physics, 117259 Moscow (Russia); Klimenko, A.A.; Osetrov, S.B.; Smolnikov, A.A.; Vasiliev, S.I. [Institute for Nuclear Research, Baksan Neutrino Observatory, 361609 Neutrino (Russia)] [Institute for Nuclear Research, Baksan Neutrino Observatory, 361609 Neutrino (Russia); Pogosov, V.S.; Tamanyan, A.G. [Yerevan Physical Institute, 375 036 Yerevan (Armenia)] [Yerevan Physical Institute, 375 036 Yerevan (Armenia)

1999-04-01

348

Neutron detector characterization for SCINTIA array  

SciTech Connect

SCINTIA is a new detector array of organic scintillators under development at the Inst. for Reference Materials and Measurements (IRMM). The present design of SCINTIA includes NE213, p-terphenyl and Li glass neutron detectors positioned in a spherical configuration around the target. The properties of a novel p-terphenyl neutron detector to be used with SCINTIA have been investigated using photon sources and neutrons from a time tagged {sup 252}Cf(sf) source. The results show that the p-terphenyl crystal has better energy resolution, increased proton light output and neutron efficiency when compared to a similar size NE213 equivalent neutron detector. (authors)

Matei, C.; Hambsch, F. J.; Oberstedt, S. [EC-JRC - Inst. for Reference Materials and Measurements, B-2440 Geel (Belgium)

2011-07-01

349

High precision thermal neutron detectors  

SciTech Connect

Two-dimensional position sensitive detectors are indispensable in neutron diffraction experiments for determination of molecular and crystal structures in biology, solid-state physics and polymer chemistry. Some performance characteristics of these detectors are elementary and obvious, such as the position resolution, number of resolution elements, neutron detection efficiency, counting rate and sensitivity to gamma-ray background. High performance detectors are distinguished by more subtle characteristics such as the stability of the response (efficiency) versus position, stability of the recorded neutron positions, dynamic range, blooming or halo effects. While relatively few of them are needed around the world, these high performance devices are sophisticated and fairly complex; their development requires very specialized efforts. In this context, we describe here a program of detector development, based on {sup 3}He filled proportional chambers, which has been underway for some years at Brookhaven. Fundamental approaches and practical considerations are outlined that have resulted in a series of high performance detectors with the best known position resolution, position stability, uniformity of reliability over time of this type.

Radeka, V.; Schaknowski, N.A.; Smith, G.C.; and Yu, B.

1994-10-01

350

High precision thermal neutron detectors  

SciTech Connect

Two-dimensional position sensitive detectors are indispensable in neutron diffraction experiments for determination of molecular and crystal structures in biology, solid-state physics and polymer chemistry. Some performance characteristics of these detectors are elementary and obvious, such as the position resolution, number of resolution elements, neutron detection efficiency, counting rate and sensitivity to gamma-ray background. High performance detectors are distinguished by more subtle characteristics such as the stability of the response (efficiency) versus position, stability of the recorded neutron positions, dynamic range, blooming or halo effects. While relatively few of them are needed around the world, these high performance devices are sophisticated and fairly complex, their development requires very specialized efforts. In this context, we describe here a program of detector development, based on {sup 3}He filled proportional chambers, which has been underway for some years at the Brookhaven National Laboratory. Fundamental approaches and practical considerations are outlined that have resulted in a series of high performance detectors with the best known position resolution, position stability, uniformity of response and reliability over time, for devices of this type.

Radeka, V.; Schaknowski, N.A.; Smith, G.C.; Yu, B. [Brookhaven National Laboratory, Upton, NY (United States)

1994-12-31

351

Fast skin color detector for face extraction  

NASA Astrophysics Data System (ADS)

Face detection is the first step for an automatic face recognition system. For color images, skin color filter is considered as an important method for removing non-face pixels. In the paper, we will propose a novel and efficient detector for skin color regions for face extraction. The detector processes the image in four steps: lighting compensation, skin color filter and mask refinement and fast patch identification. Experimental results show that our detector is more robust and efficient than other skin color filters.

Chen, Lihui; Grecos, Christos

2005-02-01

352

Radiation induced polarization in CdTe detectors  

Microsoft Academic Search

Polarization induced by irradiation with intense gamma ray sources has been studied in chlorine-compensated CdTe detectors. The influence of several parameters, such as applied field strength, temperature and incident photon flux, on the polarization effect have been investigated. A relationship was found between the degree of polarization, detector efficiency and detector leakage current.

D. Vartsky; M. Goldberg; Y. Eisen; Y. Shamai; R. Dukhan; P. Siffert; J. M. Koebel; R. Regal; J. Gerber

1988-01-01

353

Thallium bromide radiation detectors  

Microsoft Academic Search

Radiation detectors have been fabricated from crystals of the semiconductor material thallium bromide (TlBr) and the performance of these detectors as room temperature photon spectrometers has been measured. These detectors exhibit improved energy resolution over previously reported TlBr detectors. These results indicate that TlBr is a very promising radiation detector material.

K. S. Shah; J. C. Lund; F. Olschner; L. Moy; M. R. Squillante

1989-01-01

354

Nuclear Radiation Detectors  

Microsoft Academic Search

Nuclear radiation detectors are required in all the major fields of nuclear science and technology. They fall into two principal categories, single element detectors and imaging detectors. Single element detectors can be classified into four types, based upon their physical mode of operation. These are 1) Scintillation counters, 2) Gas ionization detectors, a) Ionization chambers, b) Proportional counters, c) Geiger-Mueller

G. A. Morton

1962-01-01

355

Oscillator detector  

SciTech Connect

An alien liquid detector employs a monitoring element and an oscillatory electronic circuit for maintaining the temperature of the monitoring element substantially above ambient temperature. The output wave form, eg., frequency of oscillation or wave shape, of the oscillatory circuit depends upon the temperaturedependent electrical characteristic of the monitoring element. A predetermined change in the output waveform allows water to be discriminated from another liquid, eg., oil. Features of the invention employing two thermistors in two oscillatory circuits include positioning one thermistor for contact with water and the other thermistor above the oil-water interface to detect a layer of oil if present. Unique oscillatory circuit arrangements are shown that achieve effective thermistor action with an economy of parts and energizing power. These include an operational amplifier employed in an astable multivibrator circuit, a discrete transistor-powered tank circuit, and use of an integrated circuit chip.

Potter, B.M.

1980-05-13

356

Design and construction of an ultra-low-background 14-crystal germanium array for high efficiency and coincidence measurements  

Microsoft Academic Search

Physics experiments, environmental surveillance, and treaty verification techniques continue to require increased sensitivity\\u000a for detecting and quantifying radionuclides of interest. This can be done by detecting a greater fraction of gamma emissions\\u000a from a sample (higher detection efficiency) and reducing instrument backgrounds. A current effort for increased sensitivity\\u000a in high resolution gamma spectroscopy will produce an intrinsic germanium (HPGe) array

Martin E. Keillor; Craig E. Aalseth; Anthony R. Day; James E. Fast; Eric W. Hoppe; Brian J. Hyronimus; Todd W. Hossbach; Harry S. Miley; Allen Seifert; Glen A. Warren

2009-01-01

357

A new CdZnTe detector system for low-energy gamma-ray measurement  

Microsoft Academic Search

The major problems with CdTe-based radiation detectors have been excess noise and operation instabilities due to poor charge-collection efficiency. New fabrication methods have removed these problems and made CdZnTe detectors attractive in applications where compact room-temperature detectors with high stopping efficiency are required. The improvements in this detector technology are demonstrated. The noise performance of these detectors is comparable with

G. A Johansen; E Åbro

1996-01-01

358

A New CdZnTe Detector System For Low Energy Gamma-ray Measurement  

Microsoft Academic Search

SUMMARY The major problems with CdTe-based radiation detectors have been excess noise and operation instabilities due to poor charge collection efficiency. New fabrication methods have removed these problems and made CdZnTe detectors attractive in applications where compact, room temperature detectors with high stopping efficiency are required. The improvements in this detector technology are demonstrated. The noise performance of these detectors

Geir Anton Johansen; Eirik Abro

1995-01-01

359

Development of a large-area silicon ?-particle detector.  

PubMed

Circular ion-implanted silicon detector of ?-particles with a large, 5-cm(2), sensitive area has been developed. An advantage of the detector is that the detector surface is easily cleanable with chemicals. The hardened surface of the detector shows no signs of deterioration of the spectroscopic and electrical characteristics upon repeated cleaning. The energy resolution along the diameters of the detector was (1.0±0.1)% for the 5.486-MeV ?-particles. Detailed tests of the charge collection efficiency and uniformity of the detector entrance window were also performed with a 5.5-MeV He(2+) microbeam. PMID:25016328

Tran, Linh T; Prokopovich, Dale A; Lerch, Michael L F; Petasecca, Marco; Siegele, Rainer; Reinhard, Mark I; Perevertaylo, Vladimir; Rosenfeld, Anatoly B

2014-09-01

360

Multi-layer boron thin-film detectors for neutrons  

Microsoft Academic Search

Intrinsic efficiencies of multi-layer boron-10 thin-film detectors were studied theoretically and experimentally. For multi-layer schemes based on an optimized single-layer film thickness, the practical efficiency is limited to about 42% for thermal neutrons. This is about half the efficiency of a moderated 3He detectors in commercial use for portal monitoring. The efficiency limitation is due to charged particle loss in

Zhehui Wang; C. L. Morris

2011-01-01

361

Nuclear radiation detectors  

Microsoft Academic Search

Detectors of nuclear radiation, such as gaseous detectors, scintillators, and semiconductors, are presented through their general properties and with their operating systems. The semiconductor detectors are studied with more details.

Luiz Alexandre Schuch; Daniel Jean Roger Nordemann

1990-01-01

362

Important detector parameters: 1. Quantum efficiency  

E-print Network

photography dominated astronomical detection for more than a century: ~1870-1980 pro's and con of photography first sky object photographs (daguerrotypes): 1840 Moon J.W. Draper 1843 Solar spectrum ,, 1845 Sun Foucault +Fizeau 1870 invention of dry gelatine emulsions this enabled astronomical applications

Peletier, Reynier

363

High-resolution gamma-ray detectors for nuclear spectroscopy  

Microsoft Academic Search

Transition-edge sensor (TES) calorimeters are an attractive technology for precision measurements of electromagnetic radiation. However, in order to have a high-energy resolution detector, a small detector volume must be used, thereby limiting the count-rate and efficiency of the detector. As a result, many TES calorimeters must be operated simultaneously in order to achieve an appreciable detector count rate and stopping

Mark Forrest Cunningham

2002-01-01

364

CdTe stacked detectors for gamma-ray detection  

Microsoft Academic Search

We describe a stacked detector made of thin CdTe diode detectors. By using a thin CdTe device, we can overcome the charge loss problem due to the small mobility and short lifetime of holes in CdTe or CdZnTe detectors. However, a CdTe detector with a thickness of more than 5 mm is needed for adequate detection efficiency for gamma-rays of

Shin Watanabe; Tadayuki Takahashi; Yuu Okada; C. Sato; Manabu Kouda; Takefumi Mitani; Y. Kobavashi; Kazuhiro Nakazawa; Yoshikatsu Kuroda; Mitsunobu Onishi

2001-01-01

365

SU-E-I-62: Assessing Radiation Dose Reduction and CT Image Optimization Through the Measurement and Analysis of the Detector Quantum Efficiency (DQE) of CT Images Using Different Beam Hardening Filters  

SciTech Connect

Purpose: Reducing patient dose while maintaining (or even improving) image quality is one of the foremost goals in CT imaging. To this end, we consider the feasibility of optimizing CT scan protocols in conjunction with the application of different beam-hardening filtrations and assess this augmentation through noise-power spectrum (NPS) and detector quantum efficiency (DQE) analysis. Methods: American College of Radiology (ACR) and Catphan phantoms (The Phantom Laboratory) were scanned with a 64 slice CT scanner when additional filtration of thickness and composition (e.g., copper, nickel, tantalum, titanium, and tungsten) had been applied. A MATLAB-based code was employed to calculate the image of noise NPS. The Catphan Image Owl software suite was then used to compute the modulated transfer function (MTF) responses of the scanner. The DQE for each additional filter, including the inherent filtration, was then computed from these values. Finally, CT dose index (CTDIvol) values were obtained for each applied filtration through the use of a 100 mm pencil ionization chamber and CT dose phantom. Results: NPS, MTF, and DQE values were computed for each applied filtration and compared to the reference case of inherent beam-hardening filtration only. Results showed that the NPS values were reduced between 5 and 12% compared to inherent filtration case. Additionally, CTDIvol values were reduced between 15 and 27% depending on the composition of filtration applied. However, no noticeable changes in image contrast-to-noise ratios were noted. Conclusion: The reduction in the quanta noise section of the NPS profile found in this phantom-based study is encouraging. The reduction in both noise and dose through the application of beam-hardening filters is reflected in our phantom image quality. However, further investigation is needed to ascertain the applicability of this approach to reducing patient dose while maintaining diagnostically acceptable image qualities in a clinical setting.

Collier, J; Aldoohan, S; Gill, K

2014-06-01

366

PET detector modules based on novel detector technologies  

Microsoft Academic Search

A successful PET detector module must identify 511 keV photons with: high efficiency (>85%), high spatial resolution (<5 mm fwhm), low cost (<$600 \\/ in2), low dead time (<4 µs in2), good timing resolution (<5 ns fwhm for conventional PET, <200 ps fwhm for time of flight), and good energy resolution (<100 keV fwhm), where these requirements are listed in

William W. Moses; Stephen E. Derenzo; Thomas F. Budinger

1994-01-01

367

The role of the false events on the DQE measurement of the radiation detectors  

E-print Network

The efficiency of a radiation detector, intended as probability of detection of an incident quantum, depends on various factors: the detected fraction of quanta ascribed to the noise-less detector, the intrinsic noise of the detector, the false events introduced by the detection process and the false events generated by the detector itself. In this paper is treated the role of the false events on the measurement of the detective quantum efficiency (DQE) of the radiation detectors, indifferently for counting detectors and imaging detectors.

Giovanni Zanella

2012-11-12

368

Optimizing indium antimonide (InSb) detectors for low background operation. [infrared astronomy  

NASA Technical Reports Server (NTRS)

The various noise sources that affect InSb detectors (and similar voltaic devices) are discussed and calculated. Methods are given for measuring detector resistance, photon loading, detector and amplifier capacitance, amplifier frequency response, amplifier noise, and quantum efficiency. A photovoltaic InSb detector with increased sensitivity in the 1 to 5.6 mu region is dicussed.

Treffers, R. R.

1978-01-01

369

Large-Mass Ultra-Low Noise Germanium Detectors: Performance and Applications in Neutrino and Astroparticle Physics  

E-print Network

A new type of radiation detector, a p-type modified electrode germanium diode, is presented. The prototype displays, for the first time, a combination of features (mass, energy threshold and background expectation) required for a measurement of coherent neutrino-nucleus scattering in a nuclear reactor experiment. The device hybridizes the mass and energy resolution of a conventional HPGe coaxial gamma spectrometer with the low electronic noise and threshold of a small x-ray semiconductor detector, also displaying an intrinsic ability to distinguish multiple from single-site particle interactions. The present performance of the prototype and possible further improvements are discussed, as well as other applications for this new type of device in neutrino and astroparticle physics (double-beta decay, neutrino magnetic moment and WIMP searches).

P. S. Barbeau; J. I. Collar; O. Tench

2007-01-07

370

The DØ detector  

Microsoft Academic Search

The DØ detector is a large general purpose detector for the study of short-distance phenomena in high energy antiproton-proton collisions, now in operation at the Fermilab Tevatron collider. The detector focusses upon the detection of electrons, muons, jets and missing transverse momentum. We describe the design and performance of the major elements of the detector, including the tracking chambers, transition

S. Abachi; M. Abolins; B. S. Acharya; I. Adam; S. Ahn; H. Aihara; G. Alvarez; G. A. Alves; N. Amos; W. Anderson; Yu. Antipov; S. H. Aronson; R. Astur; R. E. Avery; A. Baden; J. Balderston; B. Baldin; J. Bantly; E. Barasch; J. F. Bartlett; K. Bazizi; T. Behnke; V. Bezzubov; P. C. Bhat; G. Blazey; S. Blessing; A. Boehnlein; F. Borcherding; J. Borders; N. Bozko; A. Brandt; R. Brock; A. Bross; D. Buchholz; V. Burtovoy; J. M. Butler; O. Callot; D. Chakraborty; S. Chekulaev; J. Chen; L.-P. Chen; W. Chen; B. C. Choudhary; J. H. Christenson; D. Claes; A. R. Clark; W. G. Cobau; J. Cochran; W. E. Cooper; C. Cretsinger; D. Cullen-Vidal; M. Cummings; D. Cutts; O. I. Dahl; B. Daniels; K. de; M. Demarteau; K. Denisenko; N. Denisenko; D. Denisov; S. Denisov; W. Dharmaratna; H. T. Diehl; M. Diesburg; R. Dixon; P. Draper; Y. Ducros; S. Durston-Johnson; D. Eartly; P. H. Eberhard; D. Edmunds; A. Efimov; J. Ellison; V. D. Elvira; R. Engelmann; O. Eroshin; V. Evdokimov; S. Fahey; G. Fanourakis; M. Fatyga; J. Featherly; S. Feher; D. Fein; T. Ferbel; D. Finley; G. Finocchiaro; H. E. Fisk; E. Flattum; G. E. Forden; M. Fortner; P. Franzini; S. Fuess; E. Gallas; C. S. Gao; T. L. Geld; K. Genser; C. E. Gerber; B. Gibbard; V. Glebov; J. F. Glicenstein; B. Gobbi; M. Goforth; M. L. Good; F. Goozen; H. Gordon; N. Graf; P. D. Grannis; D. R. Green; J. Green; H. Greenlee; N. Grossman; P. Grudberg; J. A. Guida; J. M. Guida; W. Guryn; N. J. Hadley; H. Haggerty; S. Hagopian; V. Hagopian; R. E. Hall; S. Hansen; J. Hauptman; D. Hedin; A. P. Heinson; U. Heintz; T. Heuring; R. Hirosky; K. Hodel; J. S. Hoftun; J. R. Hubbard; T. Huehn; R. Huson; S. Igarashi; A. S. Ito; E. James; J. Jiang; K. Johns; C. R. Johnson; M. Johnson; A. Jonckheere; M. Jones; H. Jöstlein; C. K. Jung; S. Kahn; S. Kanekal; A. Kernan; L. Kerth; A. Kirunin; A. Klatchko; B. Klima; B. Klochkov; C. Klopfenstein; V. Klyukhin; V. Kochetkov; J. M. Kohli; W. Kononenko; J. Kotcher; I. Kotov; J. Kourlas; A. Kozelov; E. Kozlovsky; G. Krafczyk; K. Krempetz; M. R. Krishnaswamy; P. Kroon; S. Krzywdzinski; S. Kunori; S. Lami; G. Landsberg; R. E. Lanou; P. Laurens; J. Lee-Franzini; J. Li; R. Li; Q. Z. Li-Demarteau; J. G. R. Lima; S. L. Linn; J. Linnemann; R. Lipton; Y.-C. Liu; D. Lloyd-Owen; F. Lobkowicz; S. C. Loken; S. Lokos; L. Lueking; A. K. A. Maciel; R. J. Madaras; R. Madden; E. Malamud; Ph. Mangeot; I. Manning; B. Mansoulié; V. Manzella; H.-S. Mao; M. Marcin; L. Markosky; T. Marshall; H. J. Martin; M. I. Martin; P. S. Martin; M. Marx; B. May; A. Mayorov; R. McCarthy; J. McKinley; D. Mendoza; X.-C. Meng; K. W. Merritt; A. Milder; A. Mincer; N. K. Mondal; M. Montag; P. Mooney; M. Mudan; G. T. Mulholland; C. Murphy; F. Nang; M. Narain; V. S. Narasimham; H. A. Neal; P. Nemethy; D. Nesic; K. K. Ng; D. Norman; L. Oesch; V. Oguri; E. Oltman; N. Oshima; D. Owen; M. Pang; A. Para; C. H. Park; R. Partridge; M. Paterno; A. Peryshkin; M. Peters; B. Pi; H. Piekarz; Yu. Pischalnikov; D. Pizzuto; A. Pluquet; V. Podstavkov; B. G. Pope; H. B. Prosper; S. Protopopescu; Y.-K. Que; P. Z. Quintas; G. Rahal-Callot; R. Raja; S. Rajagopalan; M. V. S. Rao; L. Rasmussen; A. L. Read; T. Regan; S. Repond; V. Riadovikov; M. Rijssenbeek; N. A. Roe; P. Rubinov; J. Rutherfoord; A. Santoro; L. Sawyer; R. D. Schamberger; J. Sculli; W. Selove; M. Shea; A. Shkurenkov; M. Shupe; J. B. Singh; V. Sirotenko; W. Smart; A. Smith; D. Smith; R. P. Smith; G. R. Snow; S. Snyder; M. Sosebee; M. Souza; A. L. Spadafora; S. Stampke; R. Stephens; M. L. Stevenson; D. Stewart; F. Stocker; D. Stoyanova; H. Stredde; K. Streets; M. Strovink; A. Suhanov; A. Taketani; M. Tartaglia; J. D. Taylor; J. Teiger; G. Theodosiou; J. Thompson; S. Tisserant; T. G. Trippe; P. M. Tuts; R. van Berg; M. Vaz; P. R. Vishwanath; A. Volkov; A. Vorobiev; H. D. Wahl; D.-C. Wang; L.-Z. Wang; H. Weerts; W. A. Wenzel; A. White; J. T. White; J. Wightman; S. Willis; S. J. Wimpenny; Z. Wolf; J. Womersley; D. R. Wood; Y. Xia; D. Xiao; P. Xie; H. Xu; R. Yamada; P. Yamin; C. Yanagisawa; J. Yang; C. Yoshikawa; S. Youssef; J. Yu; R. Zeller; S. Zhang; Y. H. Zhou; Q. Zhu; Y.-S. Zhu; D. Zieminska; A. Zieminski; A. Zinchenko; A. Zylberstejn

1994-01-01

371

Spiral silicon drift detectors  

SciTech Connect

An advanced large area silicon photodiode (and x-ray detector), called Spiral Drift Detector, was designed, produced and tested. The Spiral Detector belongs to the family of silicon drift detectors and is an improvement of the well known Cylindrical Drift Detector. In both detectors, signal electrons created in silicon by fast charged particles or photons are drifting toward a practically point-like collection anode. The capacitance of the anode is therefore kept at the minimum (0.1pF). The concentric rings of the cylindrical detector are replaced by a continuous spiral in the new detector. The spiral geometry detector design leads to a decrease of the detector leakage current. In the spiral detector all electrons generated at the silicon-silicon oxide interface are collected on a guard sink rather than contributing to the detector leakage current. The decrease of the leakage current reduces the parallel noise of the detector. This decrease of the leakage current and the very small capacities of the detector anode with a capacitively matched preamplifier may improve the energy resolution of Spiral Drift Detectors operating at room temperature down to about 50 electrons rms. This resolution is in the range attainable at present only by cooled semiconductor detectors. 5 refs., 10 figs.

Rehak, P.; Gatti, E.; Longoni, A.; Sampietro, M.; Holl, P.; Lutz, G.; Kemmer, J.; Prechtel, U.; Ziemann, T.

1988-01-01

372

Boron layer scintillation neutron detectors  

Microsoft Academic Search

Summary  Neutron detection with layers of crystalline powder mixtures of a boron compound and of a scintillator, used in connection\\u000a with a photomultiplier, has been studied. Efficiency of 6% for incident thermal neutrons and almost complete insensitivity\\u000a to ? and cosmic rays is reached. Detector's geometry approaches that of an infinitely thin sheet. Pulses may be shaped so\\u000a as to have

E. Gatti; E. Germagnoli; A. Persano; E. Zimmer

1952-01-01

373

Neutron spectrometer for ITER using silicon detectors.  

PubMed

High resolution neutron spectrometers provide information about plasma parameters at existing fusion experiments. Such a system may also be employed at ITER. Proton recoil telescopes have classically been used to detect neutrons with good energy resolution but poor efficiency. Using annular silicon detectors, it is possible to greatly increase the solid angle coverage and hence improve efficiency. Based on a simulation (MCNPX) study, the scaling of energy resolution, efficiency, and time to determine an ion temperature to 10% accuracy on foil thickness and detector location is shown. The latter quantity is used to determine the optimum foil thickness and detector geometry for specific plasma temperatures. For a 20 keV deuterium-tritium (DT) plasma, 5.3% resolution with efficiency of 2.9x10(-4) n cm(2) is attainable using the available detectors. This gives a temperature measurement with 10% accuracy in 1.1 ms for a neutron flux of 2x10(9) n cm(-2). Multiple detectors can be used to further increase the efficiency if needed. A system of this kind could be tested in a future DT campaign at, for example, JET. PMID:19044493

Conroy, Sean W; Weiszflog, Matthias; Andersson-Sunden, Erik; Ericsson, Goran; Gatu-Johnson, Maria; Hellesen, Carl; Ronchi, Emanuel; Sjostrand, Henrik

2008-10-01

374

Superconducting quantum detectors  

NASA Astrophysics Data System (ADS)

The discovery of high-temperature superconductors spawned many potential applications, including optical detectors. Realizing viable superconducting detectors requires achieving performance superior to competing and more mature semiconductor detector technologies, and quantum detector technologies in particular. We review why quantum detectors are inherently more sensitive than thermal or bolometric detectors. This sensitivity advantage suggests that for operation at cryogenic temperatures, we should be developing only quantum superconducting detectors. Accordingly, we introduce and describe the structure and the operation of a superconducting quantum detector with a superconducting quantum interference device (SQUID) readout circuit. The superconducting quantum detector, consisting of a superconducting loop, produces a photosignal in response to photoinduced changes in the superconducting condensate's kinetic inductance. The superconducting quantum detector is designed to operate only in the superconducting state and not in the resistive or transition states.

Bluzer, Nathan; Forrester, Martin G.

1994-03-01

375

Superconducting quantum detectors  

NASA Astrophysics Data System (ADS)

The discovery of high temperature superconductors (HTS) spawned many potential applications, including optical detectors. Realizing viable superconducting detectors requires achieving performance superior to competing and more mature semiconductor detector technologies, and quantum detector technologies in particular. We review why quantum detectors are inherently more sensitive than thermal or bolometric detectors. This sensitivity advantage suggests that for operation at cryogenic temperatures we should be developing only quantum superconducting detectors. Accordingly, we introduce and describe the structure and the operation of a superconducting quantum detector with a SQUID read-out circuit. The superconducting quantum detector, consisting of a superconducting loop, produces a photosignal in response to photoinduced changes in the condensate's kinetic inductance. The superconducting quantum detector is designed to operate only in the superconducting state and not in the resistive or transition states.

Bluzer, Nathan; Forrester, Martin G.

1993-11-01

376

Large area liquid argon detectors for interrogation systems  

SciTech Connect

Measurements of the efficiency, pulse shape, and energy and time resolution of liquid argon (LAr) detectors are presented. Liquefied noble gas-based (LNbG) detectors have been developed for the detection of dark matter and neutrinoless double-beta decay. However, the same qualities that make LNbG detectors ideal for these applications, namely their size, cost, efficiency, pulse shape discrimination and resolution, make them promising for portal screening and the detection of Special Nuclear Materials (SNM). Two 18-liter prototype detectors were designed, fabricated, and tested, one with pure LAr and the other doped with liquid Xe (LArXe). The LArXe detector presented the better time and energy resolution of 3.3 ns and 20% at 662 KeV, respectively. The total efficiency of the detector was measured to be 35% with 4.5% of the total photons detected in the photopeak.

Gary, Charles; Kane, Steve; Firestone, Murray I.; Smith, Gregory [Adelphi Technology LLC, Purdue Technology Center, 5225 Exploration Drive, Indianapolis, IN 46241 (United States); Gozani, Tsahi; Brown, Craig; Kwong, John; King, Michael J. [Rapiscan Laboratories, 520 Almanor Avenue, Sunnyvale, CA 94085 (United States); Nikkel, James A.; McKinsey, Dan [Physics Department, Yale University, New Haven, CT 06520 (United States)

2013-04-19

377

The flexible embedded-fiber neutron detector  

Microsoft Academic Search

We present a novel area-detector design, the flexible embedded-fiber detector (FEFD), which combines high-efficiency, low-cost, and very simple signal processing. It consists of wavelength-shifting fibers embedded in a zinc-sulfide lithium-fluoride-based scintillator and a physically flexible binder that allows the detecting surface to be wrapped into circular paths, so that each fiber is concentric with a single Debye–Scherrer cone. The FEFD

T. K. McKnight; J. B. Czirr; K. Littrell; B. J. Campbell

2008-01-01

378

Thallium Bromide Nuclear Radiation Detector Development  

Microsoft Academic Search

Thallium bromide (TlBr) is a dense, high-Z, wide bandgap semiconductor that has potential as an efficient, compact, room temperature nuclear radiation detector. In this paper we report on our recent progress in TlBr nuclear detector development. In particular, improvements in material purification have led to an order of magnitude increase in the mobility-lifetime product of electrons, (mutau)e, to as high

Alexei V. Churilov; Guido Ciampi; Hadong Kim; Leonard J. Cirignano; William M. Higgins; Fred Olschner; Kanai S. Shah

2009-01-01

379

The CLEO III silicon vertex detector  

Microsoft Academic Search

The design and operation of the CLEO III silicon vertex detector is described in this report. This detector consists of four layers of double-sided silicon wafers covering 93% of the solid angle. After initially meeting its signal-to-noise and spatial resolution design goals, the r?? side efficiency of layers 1 and 2 decreased dramatically due to radiation-induced sensor effects.

R. Kass; M. S. Alam; J. P. Alexander; A. Anastassov; K. Arndt; A. Bean; F. Blanc; G. Boyd; G. W. Brandenburg; J. W. Cherwinka; J. E. Duboscq; E. Eckhart; A. Ershov; J. Fast; A. D. Foland; P. I. Hopman; K. K. Gan; Y. Gao; H. P. Kagan; S. Kane; L. Kazkaz; D. Kim; J. Lee; A. J. Magerkurth; D. Miller; J. Miyamoto; M. Neustadt; J. Oliver; V. Pavlunin; C. Rush; T. Selby; H. Severini; I. Shipsey; P. Skubic; T. Smith; P. Sterner; S. Timm; E. von Toerne; D. Tournear; C. W. Ward; Q. Zhang; X. Zhao; M. M. Zoeller

2003-01-01

380

Single photon detector with high polarization sensitivity.  

PubMed

Polarization is one of the key parameters of light. Most optical detectors are intensity detectors that are insensitive to the polarization of light. A superconducting nanowire single photon detector (SNSPD) is naturally sensitive to polarization due to its nanowire structure. Previous studies focused on producing a polarization-insensitive SNSPD. In this study, by adjusting the width and pitch of the nanowire, we systematically investigate the preparation of an SNSPD with high polarization sensitivity. Subsequently, an SNSPD with a system detection efficiency of 12% and a polarization extinction ratio of 22 was successfully prepared. PMID:25875225

Guo, Qi; Li, Hao; You, LiXing; Zhang, WeiJun; Zhang, Lu; Wang, Zhen; Xie, XiaoMing; Qi, Ming

2015-01-01

381

Single photon detector with high polarization sensitivity  

PubMed Central

Polarization is one of the key parameters of light. Most optical detectors are intensity detectors that are insensitive to the polarization of light. A superconducting nanowire single photon detector (SNSPD) is naturally sensitive to polarization due to its nanowire structure. Previous studies focused on producing a polarization-insensitive SNSPD. In this study, by adjusting the width and pitch of the nanowire, we systematically investigate the preparation of an SNSPD with high polarization sensitivity. Subsequently, an SNSPD with a system detection efficiency of 12% and a polarization extinction ratio of 22 was successfully prepared. PMID:25875225

Guo, Qi; Li, Hao; You, LiXing; Zhang, WeiJun; Zhang, Lu; Wang, Zhen; Xie, XiaoMing; Qi, Ming

2015-01-01

382

Microstructured silicon neutron detectors for security applications  

NASA Astrophysics Data System (ADS)

In this paper we present the design and performance of a perforated thermal neutron silicon detector with a 6LiF neutron converter. This device was manufactured within the REWARD project workplace whose aim is to develop and enhance technologies for the detection of nuclear and radiological materials. The sensor perforated structure results in a higher efficiency than that obtained with an equivalent planar sensor. The detectors were tested in a thermal neutron beam at the nuclear reactor at the Instituto Superior Técnico in Lisbon and the intrinsic detection efficiency for thermal neutrons and the gamma sensitivity were obtained. The Geant4 Monte Carlo code was used to simulate the experimental conditions, i.e. thermal neutron beam and the whole detector geometry. An intrinsic thermal neutron detection efficiency of 8.6%±0.4% with a discrimination setting of 450 keV was measured.

Esteban, S.; Fleta, C.; Guardiola, C.; Jumilla, C.; Pellegrini, G.; Quirion, D.; Rodriguez, J.; Lozano, M.

2014-12-01

383

Noise performance of the D0 layer 0 silicon detector  

SciTech Connect

A new inner detector called Layer 0 has been added to the existing silicon detector for the DZero colliding beams experiment. This detector has an all carbon fiber support structure that employs thin copper clad Kapton sheets embedded in the surface of the carbon fiber structure to improve the grounding of the structure and a readout system that fully isolates the local detector ground from the rest of the detector. Initial measurements show efficiencies greater than 90% and 0.3 ADC count common mode contribution to the signal noise.

Johnson, M.; /Fermilab

2006-11-01

384

Detectors for ground-based reception of laser communications from Mars  

Microsoft Academic Search

Ground-based receivers at Earth require single photon counting detectors with 30% photo-detection efficiency (PDE) at 1.06-?m, for optical communications from deep space. Design drivers and detector selection criteria are discussed.

A. Biswas; W. H. Farr

2004-01-01

385

The upgraded DØ detector  

NASA Astrophysics Data System (ADS)

The DØ experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid-argon calorimeters and central muon detector, remaining from Run I, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to DØ.

Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, D. L.; Adams, M.; Adams, T.; Agelou, M.; Agram, J.-L.; Ahmed, S. N.; Ahn, S. H.; Ahsan, M.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Alverson, G.; Alves, G. A.; Anastasoaie, M.; Andeen, T.; Anderson, J. T.; Anderson, S.; Andrieu, B.; Angstadt, R.; Anosov, V.; Arnoud, Y.; Arov, M.; Askew, A.; Åsman, B.; Assis Jesus, A. C. S.; Atramentov, O.; Autermann, C.; Avila, C.; Babukhadia, L.; Bacon, T. C.; Badaud, F.; Baden, A.; Baffioni, S.; Bagby, L.; Baldin, B.; Balm, P. W.; Banerjee, P.; Banerjee, S.; Barberis, E.; Bardon, O.; Barg, W.; Bargassa, P.; Baringer, P.; Barnes, C.; Barreto, J.; Bartlett, J. F.; Bassler, U.; Bhattacharjee, M.; Baturitsky, M. A.; Bauer, D.; Bean, A.; Baumbaugh, B.; Beauceron, S.; Begalli, M.; Beaudette, F.; Begel, M.; Bellavance, A.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besançon, M.; Besson, A.; Beuselinck, R.; Beutel, D.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Binder, M.; Biscarat, C.; Bishoff, A.; Black, K. M.; Blackler, I.; Blazey, G.; Blekman, F.; Blessing, S.; Bloch, D.; Blumenschein, U.; Bockenthien, E.; Bodyagin, V.; Boehnlein, A.; Boeriu, O.; Bolton, T. A.; Bonamy, P.; Bonifas, D.; Borcherding, F.; Borissov, G.; Bos, K.; Bose, T.; Boswell, C.; Bowden, M.; Brandt, A.; Briskin, G.; Brock, R.; Brooijmans, G.; Bross, A.; Buchanan, N. J.; Buchholz, D.; Buehler, M.; Buescher, V.; Burdin, S.; Burke, S.; Burnett, T. H.; Busato, E.; Buszello, C. P.; Butler, D.; Butler, J. M.; Cammin, J.; Caron, S.; Bystricky, J.; Canal, L.; Canelli, F.; Carvalho, W.; Casey, B. C. K.; Casey, D.; Cason, N. M.; Castilla-Valdez, H.; Chakrabarti, S.; Chakraborty, D.; Chan, K. M.; Chandra, A.; Chapin, D.; Charles, F.; Cheu, E.; Chevalier, L.; Chi, E.; Chiche, R.; Cho, D. K.; Choate, R.; Choi, S.; Choudhary, B.; Chopra, S.; Christenson, J. H.; Christiansen, T.; Christofek, L.; Churin, I.; Cisko, G.; Claes, D.; Clark, A. R.; Clément, B.; Clément, C.; Coadou, Y.; Colling, D. J.; Coney, L.; Connolly, B.; Cooke, M.; Cooper, W. E.; Coppage, D.; Corcoran, M.; Coss, J.; Cothenet, A.; Cousinou, M.-C.; Cox, B.; Crépé-Renaudin, S.; Cristetiu, M.; Cummings, M. A. C.; Cutts, D.; da Motta, H.; Das, M.; Davies, B.; Davies, G.; Davis, G. A.; Davis, W.; De, K.; de Jong, P.; de Jong, S. J.; De La Cruz-Burelo, E.; De La Taille, C.; De Oliveira Martins, C.; Dean, S.; Degenhardt, J. D.; Déliot, F.; Delsart, P. A.; Del Signore, K.; DeMaat, R.; Demarteau, M.; Demina, R.; Demine, P.; Denisov, D.; Denisov, S. P.; Desai, S.; Diehl, H. T.; Diesburg, M.; Doets, M.; Doidge, M.; Dong, H.; Doulas, S.; Dudko, L. V.; Duflot, L.; Dugad, S. R.; Duperrin, A.; Dvornikov, O.; Dyer, J.; Dyshkant, A.; Eads, M.; Edmunds, D.; Edwards, T.; Ellison, J.; Elmsheuser, J.; Eltzroth, J. T.; Elvira, V. D.; Eno, S.; Ermolov, P.; Eroshin, O. V.; Estrada, J.; Evans, D.; Evans, H.; Evdokimov, A.; Evdokimov, V. N.; Fagan, J.; Fast, J.; Fatakia, S. N.; Fein, D.; Feligioni, L.; Ferapontov, A. V.; Ferbel, T.; Ferreira, M. J.; Fiedler, F.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Fleck, I.; Fitzpatrick, T.; Flattum, E.; Fleuret, F.; Flores, R.; Foglesong, J.; Fortner, M.; Fox, H.; Franklin, C.; Freeman, W.; Fu, S.; Fuess, S.; Gadfort, T.; Galea, C. F.; Gallas, E.; Galyaev, E.; Gao, M.; Garcia, C.; Garcia-Bellido, A.; Gardner, J.; Gavrilov, V.; Gay, A.; Gay, P.; Gelé, D.; Gelhaus, R.; Genser, K.; Gerber, C. E.; Gershtein, Y.; Gillberg, D.; Geurkov, G.; Ginther, G.; Gobbi, B.; Goldmann, K.; Golling, T.; Gollub, N.; Golovtsov, V.; Gómez, B.; Gomez, G.; Gomez, R.; Goodwin, R.; Gornushkin, Y.; Gounder, K.; Goussiou, A.; Graham, D.; Graham, G.; Grannis, P. D.; Gray, K.; Greder, S.; Green, D. R.; Green, J.; Green, J. A.; Greenlee, H.; Greenwood, Z. D.; Gregores, E. M.; Grinstein, S.; Gris, Ph.; Grivaz, J.-F.; Groer, L.; Grünendahl, S.; Grünewald, M. W.; Gu, W.; Guglielmo, J.; Gupta, A.; Gurzhiev, S. N.; Gutierrez, G.; Gutierrez, P.; Haas, A.; Hadley, N. J.; Haggard, E.; Haggerty, H.; Hagopian, S.; Hall, I.; Hall, R. E.; Han, C.; Han, L.; Hance, R.; Hanagaki, K.; Hanlet, P.; Hansen, S.; Harder, K.; Harel, A.; Harrington, R.; Hauptman, J. M.; Hauser, R.; Hays, C.; Hays, J.; Hazen, E.; Hebbeker, T.; Hebert, C.; Hedin, D.; Heinmiller, J. M.; Heinson, A. P.; Heintz, U.; Hensel, C.; Hesketh, G.; Hildreth, M. D.; Hirosky, R.; Hobbs, J. D.; Hoeneisen, B.; Hohlfeld, M.; Hong, S. J.; Hooper, R.; Hou, S.; Houben, P.; Hu, Y.; Huang, J.; Huang, Y.; Hynek, V.; Huffman, D.; Iashvili, I.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jacquier, Y.; Jaffré, M.; Jain, S.; Jain, V.; Jakobs, K.; Jayanti, R.; Jenkins, A.; Jesik, R.; Jiang, Y.; Johns, K.; Johnson, M.; Johnson, P.; Jonckheere, A.; Jonsson, P.; Jöstlein, H.; Jouravlev, N.; Juarez, M.; Juste, A.; Kaan, A. P.; Kado, M. M.; Käfer, D.; Kahl, W.; Kahn, S.; Kajfasz, E.

2006-09-01

386

GADRAS Detector Response Function.  

SciTech Connect

The Gamma Detector Response and Analysis Software (GADRAS) applies a Detector Response Function (DRF) to compute the output of gamma-ray and neutron detectors when they are exposed to radiation sources. The DRF is fundamental to the ability to perform forward calculations (i.e., computation of the response of a detector to a known source), as well as the ability to analyze spectra to deduce the types and quantities of radioactive material to which the detectors are exposed. This document describes how gamma-ray spectra are computed and the significance of response function parameters that define characteristics of particular detectors.

Mitchell, Dean J.; Harding, Lee; Thoreson, Gregory G; Horne, Steven M.

2014-11-01

387

Optimization of a neutron detector design using adjoint transport simulation  

SciTech Connect

A synthetic aperture approach has been developed and investigated for Special Nuclear Materials (SNM) detection in vehicles passing a checkpoint at highway speeds. SNM is postulated to be stored in a moving vehicle and detector assemblies are placed on the road-side or in chambers embedded below the road surface. Neutron and gamma spectral awareness is important for the detector assembly design besides high efficiencies, so that different SNMs can be detected and identified with various possible shielding settings. The detector assembly design is composed of a CsI gamma-ray detector block and five neutron detector blocks, with peak efficiencies targeting different energy ranges determined by adjoint simulations. In this study, formulations are derived using adjoint transport simulations to estimate detector efficiencies. The formulations is applied to investigate several neutron detector designs for Block IV, which has its peak efficiency in the thermal range, and Block V, designed to maximize the total neutron counts over the entire energy spectrum. Other Blocks detect different neutron energies. All five neutron detector blocks and the gamma-ray block are assembled in both MCNP and deterministic simulation models, with detector responses calculated to validate the fully assembled design using a 30-group library. The simulation results show that the 30-group library, collapsed from an 80-group library using an adjoint-weighting approach with the YGROUP code, significantly reduced the computational cost while maintaining accuracy. (authors)

Yi, C.; Manalo, K.; Huang, M.; Chin, M.; Edgar, C.; Applegate, S.; Sjoden, G. [Georgia Inst. of Technology, Gilhouse Boggs Bldg., 770 State St, Atlanta, GA 30332-0745 (United States)

2012-07-01

388

Simulation and Comparison of Various Gamma-Ray Imaging Detector Configurations for IPRL Devices  

SciTech Connect

Simulations are performed for seven different geometrical configurations of CdZnTe (CZT) detector arrays for Intelligent Personal Radiation Locator (IPRL) devices. IPRL devices are portable radiation detectors that have gamma-ray imaging capability. The detector performance is analyzed for each type of IPRL configuration, and the intrinsic photopeak efficiency, intrinsic photopeak count rate, detector image resolution, imaging efficiency, and imaging count rate are determined.

Manini, H A

2006-12-27

389

Trustworthiness of detectors in quantum key distribution with untrusted detectors  

NASA Astrophysics Data System (ADS)

Measurement-device-independent quantum key distribution (MDI-QKD) protocol has been demonstrated as a viable solution to detector side-channel attacks. Recently, to bridge the strong security of MDI-QKD with the high efficiency of conventional QKD, the detector-device-independent (DDI) QKD has been proposed. One crucial assumption made in DDI-QKD is that the untrusted Bell state measurement (BSM) located inside the receiver's laboratory cannot send any unwanted information to the outside. Here, we show that if the BSM is completely untrusted, a simple scheme would allow the BSM to send information to the outside. Combined with Trojan horse attacks, this scheme could allow an eavesdropper to gain information of the quantum key without being detected. To prevent the above attack, either countermeasures to Trojan horse attacks or some trustworthiness to the "untrusted" BSM device is required.

Qi, Bing

2015-02-01

390

Infrared Detector: Card Model  

NSDL National Science Digital Library

This resource describes the physics of a simple infra-red detector. A simulation is used to illustrate energy level dependence and electron transitions in the detector. Discussion problems and comparison with other physical applications are included.

Zollman, Dean

391

Tin Can Radiation Detector.  

ERIC Educational Resources Information Center

Provides instructions for making tin can radiation detectors from empty aluminum cans, aluminum foil, clear plastic, copper wire, silica gel, and fine, unwaxed dental floss put together with tape or glue. Also provides suggestions for activities using the detectors. (JN)

Crull, John L.

1986-01-01

392

Segmented pyroelector detector  

DOEpatents

A pyroelectric detector is described which has increased voltage output and improved responsivity over equivalent size detectors. The device comprises a plurality of edge-type pyroelectric detectors which have a length which is much greater than the width of the segments between the edge-type electrodes. External circuitry connects the pyroelectric detector segments in parallel to provide a single output which maintains 50 ohm impedance characteristics.

Stotlar, S.C.; McLellan, E.J.

1981-01-21

393

Tevatron detector upgrades  

SciTech Connect

The D0 and CDF experiments are in the process of upgrading their detectors to cope with the high luminosities projected for the remainder of Tevatron Run II. They discuss the expected Tevatron environment through 2009, the detector challenges due to increasing luminosity in this period, and the solutions undertaken by the two experiments to mitigate detector problems and maximize physics results.

Lipton, R.; /Fermilab

2005-01-01

394

NUV Detector Dark Monitor  

NASA Astrophysics Data System (ADS)

Perform routine monitoring of MAMA detector dark current. The main purpose isto look for evidence of a change in the dark rates, both to track on-orbit timedependence and to check for a detector problem developing. The spatial distribution of dark rates on the detector and the effect of SAA will also be studied.

Zheng, Wei

2010-09-01

395

NUV Detector Dark Monitor  

NASA Astrophysics Data System (ADS)

Perform routine monitoring of MAMA detector dark current. The main purpose isto look for evidence of a change in the dark rates, both to track on-orbit timedependence and to check for a detector problem developing. The spatial distribution of dark rates on the detector and the effect of SAA will also be studied.

Ely, Justin

2013-10-01

396

NUV Detector Dark Monitor  

NASA Astrophysics Data System (ADS)

Perform routine monitoring of MAMA detector dark current. The main purpose isto look for evidence of a change in the dark rates, both to track on-orbit timedependence and to check for a detector problem developing. The spatial distribution of dark rates on the detector and the effect of SAA will also be studied.

Cox, Colin

2011-10-01

397

NUV Detector Dark Monitor  

NASA Astrophysics Data System (ADS)

Perform routine monitoring of MAMA detector dark current. The main purpose isto look for evidence of a change in the dark rates, both to track on-orbit timedependence and to check for a detector problem developing. The spatial distribution of dark rates on the detector and the effect of SAA will also be studied.

Ely, Justin

2012-10-01

398

The upgraded DØ detector  

Microsoft Academic Search

The DØ experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward

V. M. Abazov; B. Abbott; M. Abolins; B. S. Acharya; D. L. Adams; M. Adams; T. Adams; M. Agelou; J.-L. Agram; S. N. Ahmed; S. H. Ahn; M. Ahsan; G. D. Alexeev; G. Alkhazov; A. Alton; G. Alverson; G. A. Alves; M. Anastasoaie; T. Andeen; J. T. Anderson; S. Anderson; B. Andrieu; R. Angstadt; V. Anosov; Y. Arnoud; M. Arov; A. Askew; B. Åsman; A. C. S. Assis Jesus; O. Atramentov; C. Autermann; C. Avila; L. Babukhadia; T. C. Bacon; F. Badaud; A. Baden; S. Baffioni; L. Bagby; B. Baldin; P. W. Balm; P. Banerjee; S. Banerjee; E. Barberis; O. Bardon; W. Barg; P. Bargassa; P. Baringer; C. Barnes; J. Barreto; J. F. Bartlett; U. Bassler; M. Bhattacharjee; M. A. Baturitsky; D. Bauer; A. Bean; B. Baumbaugh; S. Beauceron; M. Begalli; F. Beaudette; M. Begel; A. Bellavance; S. B. Beri; G. Bernardi; R. Bernhard; I. Bertram; M. Besançon; A. Besson; R. Beuselinck; D. Beutel; V. A. Bezzubov; P. C. Bhat; V. Bhatnagar; M. Binder; C. Biscarat; A. Bishoff; K. M. Black; I. Blackler; G. Blazey; F. Blekman; S. Blessing; D. Bloch; U. Blumenschein; E. Bockenthien; V. Bodyagin; A. Boehnlein; O. Boeriu; T. A. Bolton; P. Bonamy; D. Bonifas; F. Borcherding; G. Borissov; K. Bos; T. Bose; C. Boswell; M. Bowden; A. Brandt; G. Briskin; R. Brock; G. Brooijmans; A. Bross; N. J. Buchanan; D. Buchholz; M. Buehler; V. Buescher; S. Burdin; S. Burke; T. H. Burnett; E. Busato; C. P. Buszello; D. Butler; J. M. Butler; J. Cammin; S. Caron; J. Bystricky; L. Canal; F. Canelli; W. Carvalho; B. C. K. Casey; D. Casey; N. M. Cason; H. Castilla-Valdez; S. Chakrabarti; D. Chakraborty; K. M. Chan; A. Chandra; D. Chapin; F. Charles; E. Cheu; L. Chevalier; E. Chi; R. Chiche; D. K. Cho; R. Choate; S. Choi; B. Choudhary; S. Chopra; J. H. Christenson; T. Christiansen; L. Christofek; I. Churin; G. Cisko; D. Claes; A. R. Clark; B. Clément; C. Clément; Y. Coadou; D. J. Colling; L. Coney; B. Connolly; M. Cooke; W. E. Cooper; D. Coppage; M. Corcoran; J. Coss; A. Cothenet; M.-C. Cousinou; B. Cox; S. Crépé-Renaudin; M. Cristetiu; M. A. C. Cummings; D. Cutts; H. da Motta; M. Das; B. Davies; G. Davies; G. A. Davis; W. Davis; K. de; P. de Jong; S. J. de Jong; E. De La Cruz-Burelo; C. De La Taille; C. De Oliveira Martins; S. Dean; J. D. Degenhardt; F. Déliot; P. A. Delsart; K. Del Signore; R. Demaat; M. Demarteau; R. Demina; P. Demine; D. Denisov; S. P. Denisov; S. Desai; H. T. Diehl; M. Diesburg; M. Doets; M. Doidge; H. Dong; S. Doulas; L. V. Dudko; L. Duflot; S. R. Dugad; A. Duperrin; O. Dvornikov; J. Dyer; A. Dyshkant; M. Eads; D. Edmunds; T. Edwards; J. Ellison; J. Elmsheuser; J. T. Eltzroth; V. D. Elvira; S. Eno; P. Ermolov; O. V. Eroshin; J. Estrada; D. Evans; H. Evans; A. Evdokimov; V. N. Evdokimov; J. Fagan; J. Fast; S. N. Fatakia; D. Fein; L. Feligioni; A. V. Ferapontov; T. Ferbel; M. J. Ferreira; F. Fiedler; F. Filthaut; W. Fisher; H. E. Fisk; I. Fleck; T. Fitzpatrick; E. Flattum; F. Fleuret; R. Flores; J. Foglesong; M. Fortner; H. Fox; C. Franklin; W. Freeman; S. Fu; S. Fuess; T. Gadfort; C. F. Galea; E. Gallas; E. Galyaev; M. Gao; C. Garcia; A. Garcia-Bellido; J. Gardner; V. Gavrilov; A. Gay; P. Gay; D. Gelé; R. Gelhaus; K. Genser; C. E. Gerber; Y. Gershtein; D. Gillberg; G. Geurkov; G. Ginther; B. Gobbi; K. Goldmann; T. Golling; N. Gollub; V. Golovtsov; B. Gómez; G. Gomez; R. Gomez; R. Goodwin; Y. Gornushkin; K. Gounder; A. Goussiou; D. Graham; G. Graham; P. D. Grannis; K. Gray; S. Greder; D. R. Green; J. Green; H. Greenlee; Z. D. Greenwood; E. M. Gregores; S. Grinstein; Ph. Gris; J.-F. Grivaz; L. Groer; S. Grünendahl; M. W. Grünewald; W. Gu; J. Guglielmo; A. Gupta; S. N. Gurzhiev; G. Gutierrez; P. Gutierrez; A. Haas; N. J. Hadley; E. Haggard; H. Haggerty; S. Hagopian; I. Hall; R. E. Hall; C. Han; L. Han; R. Hance; K. Hanagaki; P. Hanlet; S. Hansen; K. Harder; A. Harel; R. Harrington; J. M. Hauptman; R. Hauser; C. Hays; J. Hays; E. Hazen; T. Hebbeker; C. Hebert; D. Hedin; J. M. Heinmiller; A. P. Heinson; U. Heintz; C. Hensel; G. Hesketh; M. D. Hildreth; R. Hirosky; J. D. Hobbs; B. Hoeneisen; M. Hohlfeld; S. J. Hong; R. Hooper; S. Hou; P. Houben; Y. Hu; J. Huang; Y. Huang; V. Hynek; D. Huffman; I. Iashvili; R. Illingworth; A. S. Ito; S. Jabeen; Y. Jacquier; M. Jaffré; S. Jain; V. Jain; K. Jakobs; R. Jayanti; A. Jenkins; R. Jesik; Y. Jiang; K. Johns; M. Johnson; P. Johnson; A. Jonckheere; P. Jonsson; H. Jöstlein; N. Jouravlev; M. Juarez; A. Juste; A. P. Kaan; M. M. Kado; D. Käfer; W. Kahl; S. Kahn; E. Kajfasz; A. M. Kalinin; J. Kalk; S. D. Kalmani; D. Karmanov; J. Kasper; I. Katsanos; D. Kau; R. Kaur; Z. Ke; R. Kehoe; S. Kermiche; S. Kesisoglou; A. Khanov; A. Kharchilava; Y. M. Kharzheev; H. Kim; K. H. Kim; T. J. Kim; N. Kirsch; B. Klima; M. Klute; J. M. Kohli; J.-P. Konrath; E. V. Komissarov; M. Kopal; V. M. Korablev; A. Kostritski; J. Kotcher; B. Kothari; A. V. Kotwal; A. Koubarovsky; A. V. Kozelov; J. Kozminski; A. Kryemadhi; O. Kouznetsov

2006-01-01

399

Gamma ray detector shield  

DOEpatents

A gamma ray detector shield comprised of a rigid, lead, cylindrical-shaped vessel having upper and lower portions with an pneumatically driven, sliding top assembly. Disposed inside the lead shield is a gamma ray scintillation crystal detector. Access to the gamma detector is through the sliding top assembly.

Ohlinger, R.D.; Humphrey, H.W.

1985-08-26

400

Gamma ray detector shield  

Microsoft Academic Search

A gamma ray detector shield comprised of a rigid, lead, cylindrical-shaped vessel having upper and lower portions with an pneumatically driven, sliding top assembly. Disposed inside the lead shield is a gamma ray scintillation crystal detector. Access to the gamma detector is through the sliding top assembly.

R. D. Ohlinger; H. W. Humphrey

1985-01-01

401

Electronics for pixel detectors  

Microsoft Academic Search

Most modern HEP experiments use pixel detectors for vertex finding because these detectors provide clean and unambiguous position information even in a high multiplicity environment. At LHC three of the four main experiments will use pixel vertex detectors. There is also a strong development effort in the US centred around the proposed BTeV experiment. The chips being developed for these

M. Campbell

402

The ATLAS Detector Control System  

NASA Astrophysics Data System (ADS)

The ATLAS experiment is one of the multi-purpose experiments at the Large Hadron Collider (LHC) at CERN, constructed to study elementary particle interactions in collisions of high-energy proton beams. Twelve different sub detectors as well as the common experimental infrastructure are controlled and monitored by the Detector Control System (DCS) using a highly distributed system of 140 server machines running the industrial SCADA product PVSS. Higher level control system layers allow for automatic control procedures, efficient error recognition and handling, manage the communication with external systems such as the LHC controls, and provide a synchronization mechanism with the ATLAS data acquisition system. Different databases are used to store the online parameters of the experiment, replicate a subset used for physics reconstruction, and store the configuration parameters of the systems. This contribution describes the computing architecture and software tools to handle this complex and highly interconnected control system.

Lantzsch, K.; Arfaoui, S.; Franz, S.; Gutzwiller, O.; Schlenker, S.; Tsarouchas, C. A.; Mindur, B.; Hartert, J.; Zimmermann, S.; Talyshev, A.; Oliveira Damazio, D.; Poblaguev, A.; Braun, H.; Hirschbuehl, D.; Kersten, S.; Martin, T.; Thompson, P. D.; Caforio, D.; Sbarra, C.; Hoffmann, D.; Nemecek, S.; Robichaud-Veronneau, A.; Wynne, B.; Banas, E.; Hajduk, Z.; Olszowska, J.; Stanecka, E.; Bindi, M.; Polini, A.; Deliyergiyev, M.; Mandic, I.; Ertel, E.; Marques Vinagre, F.; Ribeiro, G.; Santos, H. F.; Barillari, T.; Habring, J.; Huber, J.; Arabidze, G.; Boterenbrood, H.; Hart, R.; Iakovidis, G.; Karakostas, K.; Leontsinis, S.; Mountricha, E.; Ntekas, K.; Filimonov, V.; Khomutnikov, V.; Kovalenko, S.; Grassi, V.; Mitrevski, J.; Phillips, P.; Chekulaev, S.; D'Auria, S.; Nagai, K.; Tartarelli, G. F.; Aielli, G.; Marchese, F.; Lafarguette, P.; Brenner, R.

2012-12-01

403

Coated Fiber Neutron Detector Test  

SciTech Connect

Radiation portal monitors used for interdiction of illicit materials at borders include highly sensitive neutron detection systems. The main reason for having neutron detection capability is to detect fission neutrons from plutonium. The currently deployed radiation portal monitors (RPMs) from Ludlum and Science Applications International Corporation (SAIC) use neutron detectors based upon 3He-filled gas proportional counters, which are the most common large neutron detector. There is a declining supply of 3He in the world, and thus, methods to reduce the use of this gas in RPMs with minimal changes to the current system designs and sensitivity to cargo-borne neutrons are being investigated. Reported here are the results of tests of the 6Li/ZnS(Ag)-coated non-scintillating plastic fibers option. This testing measured the required performance for neutron detection efficiency and gamma ray rejection capabilities of a system manufactured by Innovative American Technology (IAT).

Lintereur, Azaree T.; Ely, James H.; Kouzes, Richard T.; Stromswold, David C.

2009-10-23

404

The vertex detector for the Lepton/Photon collaboration  

SciTech Connect

The conceptual design of the vertex detector for the Lepton/Photon Collaboration at RHIC is described, including simulations of its expected performance. The design consists of two con- centric layers of single-sided Si strips. The expected performance as a multiplicity detector and in measuring the pseudo-rapidity ({nu}) distribution is discussed as well as the expected vertex finding efficiency and accuracy. Various options which could be used to reduce the cost of the detector are also discussed.

Sullivan, J.P.; Boissevain, J.G.; Fox, D.; Hecke, H. van; Jacak, B.V.; Kapustinsky, J.S.; Leitch, M.J.; McGaughey, P.L.; Moss, J.M.; Sondheim, W.E. [Los Alamos National Lab., NM (United States)

1991-12-31

405

Fabrication and Characterization of Superconducting NbN Nanowire Single Photon Detectors  

NASA Technical Reports Server (NTRS)

We report on the fabrication and characterization of high-speed, single photon detectors using superconducting NbN nanowires at a wavelength of 1064 nm. A 15 by 15 micron detector with a detector efficiency of 40% has been measured. Due to kinetic inductance, the recovery time of such large area detectors is longer than that of smaller or single wire detectors. The recovery time of our detectors (50 ns) has been characterized by measuring the inter-arrival time statistics of our detector.

Stern, Jeffrey A.; Farr, William H.

2006-01-01

406

High-energy detector  

DOEpatents

The preferred embodiments are directed to a high-energy detector that is electrically shielded using an anode, a cathode, and a conducting shield to substantially reduce or eliminate electrically unshielded area. The anode and the cathode are disposed at opposite ends of the detector and the conducting shield substantially surrounds at least a portion of the longitudinal surface of the detector. The conducting shield extends longitudinally to the anode end of the detector and substantially surrounds at least a portion of the detector. Signals read from one or more of the anode, cathode, and conducting shield can be used to determine the number of electrons that are liberated as a result of high-energy particles impinge on the detector. A correction technique can be implemented to correct for liberated electron that become trapped to improve the energy resolution of the high-energy detectors disclosed herein.

Bolotnikov, Aleksey E. (South Setauket, NY); Camarda, Giuseppe (Farmingville, NY); Cui, Yonggang (Upton, NY); James, Ralph B. (Ridge, NY)

2011-11-22

407

A multilayer surface detector for ultracold neutrons  

E-print Network

A multilayer surface detector for ultracold neutrons (UCNs) is described. The top $^{10}$B layer is exposed to the vacuum chamber and directly captures UCNs. The ZnS:Ag layer beneath the $^{10}$B layer is a few microns thick, which is sufficient to detect the charged particles from the $^{10}$B(n,$\\alpha$)$^7$Li neutron-capture reaction, while thin enough so that ample light due to $\\alpha$ and $^7$Li escapes for detection by photomultiplier tubes. One-hundred-nm thick $^{10}$B layer gives high UCN detection efficiency, as determined by the mean UCN kinetic energy, detector materials and others. Low background, including negligible sensitivity to ambient neutrons, has also been verified through pulse-shape analysis and comparisons with other existing $^3$He and $^{10}$B detectors. This type of detector has been configured in different ways for UCN flux monitoring, development of UCN guides and neutron lifetime research.

Wang, Zhehui; Callahan, N B; Adamek, E R; Bacon, J D; Blatnik, M; Brandt, A E; Broussard, L J; Clayton, S M; Cude-Woods, C; Currie, S; Dees, E B; Ding, X; Gao, J; Gray, F E; Hoffbauer, M A; Holley, A T; Ito, T M; Liu, C -Y; Makela, M; Ramsey, J C; Pattie,, R W; Salvat, D J; Saunders, A; Schmidt, D W; Schulze, R K; Seestrom, S J; Sharapov, E I; Sprow, A; Tang, Z; Wei, W; Wexler, J W; Womack, T L; Young, A R; Zeck, B A

2015-01-01

408

Monolithic short wave infrared (SWIR) detector array  

NASA Technical Reports Server (NTRS)

A monolithic self-scanned linear detector array was developed for remote sensing in the 1.1- 2.4-micron spectral region. A high-density IRCCD test chip was fabricated to verify new design approaches required for the detector array. The driving factors in the Schottky barrier IRCCD (Pdsub2Si) process development are the attainment of detector yield, uniformity, adequate quantum efficiency, and lowest possible dark current consistent with radiometric accuracy. A dual-band module was designed that consists of two linear detector arrays. The sensor architecture places the floating diffusion output structure in the middle of the chip, away from the butt edges. A focal plane package was conceptualized and includes a polycrystalline silicon substrate carrying a two-layer, thick-film interconnecting conductor pattern and five epoxy-mounted modules. A polycrystalline silicon cover encloses the modules and bond wires, and serves as a radiation and EMI shield, thermal conductor, and contamination seal.

1983-01-01

409

Throughput of Coded Optical CDMA Systems with AND Detectors  

NASA Astrophysics Data System (ADS)

Conventional detection techniques used in optical code-division multiple access (OCDMA) systems are not optimal and result in poor bit error rate performance. This paper analyzes the coded performance of optical CDMA systems with AND detectors for enhanced throughput efficiencies and improved error rate performance. The results show that the use of AND detectors significantly improve the performance of an optical channel.

Memon, Kehkashan A.; Umrani, Fahim A.; Umrani, A. W.; Umrani, Naveed A.

2012-09-01

410

Method for mapping charge pulses in semiconductor radiation detectors  

Microsoft Academic Search

An efficient method for determining the distribution of charge pulses produced by semiconductor detectors is presented. The method is based on a quasi-steady-state model for semiconductor detector operation. A complete description of the model and the underlying assumptions are given. Mapping of charge pulses is accomplished by solving an adjoint carrier continuity equation. The solution of the adjoint equation yields

T. H. Prettyman

1999-01-01

411

The role of contacts in semiconductor gamma radiation detectors  

Microsoft Academic Search

It is proposed that the operation of semiconductor gamma radiation detectors, equipped with ohmic contacts, which allow free electron flow between the contacts and bulk material, will not be sensitive to low hole mobility, hole collection efficiency, or hole trapping. Such fast-operating detectors may be readily integrated into monolithic arrays. The detection mechanism and various material aspects are discussed and

Uri Lachish

1998-01-01

412

Special Nuclear Material Detection with a Water Cherenkov based Detector  

SciTech Connect

Fission events from Special Nuclear Material (SNM), such as highly enriched uranium or plutonium, produce a number of neutrons and high energy gamma-rays. Assuming the neutron multiplicity is approximately Poissonian with an average of 2 to 3, the observation of time correlations between these particles from a cargo container would constitute a robust signature of the presence of SNM inside. However, in order to be sensitive to the multiplicity, one would require a high total efficiency. There are two approaches to maximize the total efficiency; maximizing the detector efficiency or maximizing the detector solid angle coverage. The advanced detector group at LLNL is investigating one way to maximize the detector size. We are designing and building a water Cerenkov based gamma and neutron detector for the purpose of developing an efficient and cost effective way to deploy a large solid angle car wash style detector. We report on our progress in constructing a larger detector and also present preliminary results from our prototype detector that indicates detection of neutrons.

Sweany, M; Bernstein, A; Bowden, N; Dazeley, S; Svoboda, R

2008-11-10

413

Cs based photocathodes for gaseous detectors  

SciTech Connect

We demonstrated that some standard photocathodes SbCs, GaAs(Cs), Au(Cs) can easily be manufactured for use inside gaseous detectors. When filed with clean quenched gases such detectors have a quantum efficiency of a few percent in the visible region of the spectra and can operate at a gain >10{sup 3}. We tried to make these photocathodes more air stable by protecting their surfaces with a thin layer of CsI or liquid TMAE. The most air stable were photocathodes with a CsI protective layer. A wavelengths {le}185 nm such photocathodes have the highest quantum efficiency among all known air stable photocathodes, including CsI. Gaseous detectors with such photocathodes can operate at a gain of 10{sup 5}. Results of first tests of doped CsI photocathode are also presented. Possible fields of application of new photocathodes are discussed.

Borovick-Romanov, A. [Inst. for Physical Problems (Russian Federation); Peskov, V. [Fermi National Accelerator Lab., Batavia, IL (United States)

1993-08-01

414

Explosives (and other threats) detection using pulsed neutron interrogation and optimized detectors  

NASA Astrophysics Data System (ADS)

We have previously reported results from a human-portable system using neutron interrogation to detect contraband and explosives. We summarized our methodology for distinguishing threat materials such as narcotics, C4, and mustard gas in the myriad of backgrounds present in the maritime environment. We are expanding our mission for the Domestic Nuclear Detection Office (DNDO) to detect Special Nuclear Material (SNM) through the detection of multiple fission signatures without compromising the conventional threat detection performance. This paper covers our initial investigations into using neutrons from compact pulsed neutron generators via the d(D,n)3He or d(T,n)? reactions with energies of ~2.5 and 14 MeV, respectively, for explosives (and other threats) detection along with a variety of gamma-ray detectors. Fast neutrons and thermal neutrons (after successive collisions) can stimulate the emission of various threat detection signatures. For explosives detection, element-specific gamma-ray signatures via the (n,n'?) inelastic scattering reaction and the (n,'?) thermal capture reaction are detected. For SNM, delayed gamma-rays following fission can be measured with the same detector. Our initial trade-off investigations of several gamma-ray detectors types (NaI, CsI, LaBr3, HPGe) for measuring gamma-ray signatures in a pulsed neutron environment for potential application in a human-portable active interrogation system are covered in this paper.

Strellis, Dan A.; Elsalim, Mashal; Gozani, Tsahi

2011-06-01

415

Can scintillation detectors with low spectral resolution accurately determine radionuclides content of building materials?  

PubMed

The current paper makes an attempt to check whether the scintillation NaI(Tl) detectors, in spite of their poor energy resolution, can determine accurately the content of NORM in building materials. The activity concentrations of natural radionuclides were measured using two types of detectors: (a) NaI(Tl) spectrometer equipped with the special software based on the matrix method of least squares, and (b) high-purity germanium spectrometer. Synthetic compositions with activity concentrations varying in a wide range, from 1/5 to 5 times median activity concentrations of the natural radionuclides available in the earth crust and the samples of popular building materials, such as concrete, pumice and gypsum, were tested, while the density of the tested samples changed in a wide range (from 860 up to 2,410 kg/m(3)). The results obtained in the NaI(Tl) system were similar to those obtained with the HPGe spectrometer, mostly within the uncertainty range. This comparison shows that scintillation spectrometers equipped with a special software aimed to compensate for the lower spectral resolution of NaI(Tl) detectors can be successfully used for the radiation control of mass construction products. PMID:23542118

Kovler, K; Prilutskiy, Z; Antropov, S; Antropova, N; Bozhko, V; Alfassi, Z B; Lavi, N

2013-07-01

416

Comparison of the LLNL and JAERI torso phantoms using Ge detectors and phoswich detectors.  

PubMed

The Human Monitoring Laboratory has compared the LLNL and JAERI torso phantoms using its germanium detector lung counting system by measuring the counting efficiencies for radioactive materials in the phantoms at photon energies of 17.7 keV, 59.5 keV, 121.8 keV, and 344 keV to assess the similarity (or differences) in performance characteristics. The counting efficiencies obtained from the two phantoms were compared by converting the Chest Wall Thickness data and Adipose Mass Fractions of the phantoms to Muscle Equivalent Chest Wall Thicknesses. The counting efficiencies for the two phantoms were found to be within a factor of 1.44 of each other at 17.7 keV, 1.30 at 59.5 keV, 1.25 at 121.8 keV, and 1.17 at 344 keV when using a four detector array (JAERI efficiency divided by LLNL efficiency). However, individual detector responses show that the counting efficiencies from the two phantoms differ considerably in the region of the heart (up to a factor of 6 at 17 keV). Other areas above the lungs give counting efficiencies that are similar to each other. A routine intercomparison exercise with Cameco Corporation has shown that the counting efficiencies derived from the LLNL and JAERI phantoms were found to be within a factor of 1.18 (JAERI/LLNL) when a natural uranium lung set was used to calibrate a lung counter consisting of phoswich detectors. This work has also shown that over the energy range 63 keV-185 keV the LLNL phantom can be used to calibrate phoswich detector systems that are positioned on the back of the subject. PMID:9570163

Kramer, G H; Hauck, B M; Allen, S A

1998-05-01

417

Charge transport properties of CdMnTe radiation detectors  

Microsoft Academic Search

Growth, fabrication and characterization of indium-doped cadmium manganese telluride (CdMnTe)radiation detectors have been described. Alpha-particle spectroscopy measurements and time resolved current transient measurements have yielded an average charge collection efficiency approaching 100 %. Spatially resolved charge collection efficiency maps have been produced for a range of detector bias voltages. Inhomogeneities in the charge transport of the CdMnTe crystals have been

Kim K; R. Rafiel; M. Boardman; I. Reinhard; A. Sarbutt; G. Watt; C. Watt; S. Uxa; D. A. Prokopovich; E. Belas; A. E. Bolotnikov; R. B. James

2012-01-01

418

1-D array of perforated diode neutron detectors  

Microsoft Academic Search

Performance of a 4cm long 64-pixel perforated diode neutron detector array is compared with an identical array of thin-film coated diodes. The perforated neutron detector design has been adapted to a 1-D pixel array capable of 120?m spatial resolution and counting efficiency greater than 12%. Deep vertical trenches filled with 6LiF provide outstanding improvement in efficiency over thin-film coated diode

Walter J. McNeil; Steven L. Bellinger; Troy C. Unruh; Chris M. Henderson; Phil Ugorowski; Bryce Morris-Lee; Russell D. Taylor; Douglas S. McGregor

2009-01-01

419

1-D array of perforated diode neutron detectors  

Microsoft Academic Search

Performance of a 4 cm long 64-pixel perforated diode neutron detector array is compared with an identical array of thin-film coated diodes. The perforated neutron detector design has been adapted to a 1-D pixel array capable of 120 mum spatial resolution and counting efficiency greater than 12%. Deep vertical trenches filled with 6LiF provide outstanding improvement in efficiency over thin-film

Walter J. McNeil; Steven L. Bellinger; Troy C. Unruh; Chris M. Henderson; Phil Ugorowski; Bryce Morris-Lee; Russell D. Taylor; Douglas S. McGregor

2009-01-01

420

Lumped Element Kinetic Inductance Detectors  

NASA Astrophysics Data System (ADS)

Kinetic Inductance Detectors (KIDs) provide a promising solution to the problem of producing large format arrays of ultra sensitive detectors for astronomy. Traditionally KIDs have been constructed from superconducting quarter-wave resonant elements capacitively coupled to a co-planar feed line [1]. Photon detection is achieved by measuring the change in quasi-particle density caused by the splitting of Cooper pairs in the superconducting resonant element. This change in quasi-particle density alters the kinetic inductance, and hence the resonant frequency of the resonant element. This arrangement requires the quasi-particles generated by photon absorption to be concentrated at positions of high current density in the resonator. This is usually achieved through antenna coupling or quasi-particle trapping. For these detectors to work at wavelengths shorter than around 500 ?m where antenna coupling can introduce a significant loss of efficiency, then a direct absorption method needs to be considered. One solution to this problem is the Lumped Element KID (LEKID), which shows no current variation along its length and can be arranged into a photon absorbing area coupled to free space and therefore requiring no antennas or quasi-particle trapping. This paper outlines the relevant microwave theory of a LEKID, along with theoretical and measured performance for these devices.

Doyle, S.; Mauskopf, P.; Naylon, J.; Porch, A.; Duncombe, C.

2008-04-01

421

Radiation Effect On Gas Electron Multiplier Detector Performance  

NASA Astrophysics Data System (ADS)

Gas Electron Multiplier (GEM) detector is a gas device with high gain and high efficiency. These detectors use chemically perforated 65 ?m thick copper clad Kapton polyimide foils. Given its potential for detecting X-rays and other radiations, GEM detectors may be used in an environment with high radioactivity. The Kapton foils manufacturer, Du Pont Inc., claims that the foils are radioactive resistant. To verify whether the GEM detector performance is affected by the exposure to radiation, several GEM foils were irradiated to a 60Co source at the gamma-ray irradiation facility at Sterigenics, Tustin, CA. Four sets of GEM foils were exposed to the level of 10 kGy, 100 kGy, 1,000 kGy and 10,000 kGy. The output signal from the GEM detectors with irradiated GEM foils were measured and compared to the detector with no irradiation. We observed that the shapes of the peaks from 5.9 KeV 55Fe X-ray were distorted and that the detector gain increased compared to that of the un-irradiated detector. In particular, the detector with 10,000 kGy irradiation appeared to have the biggest peak distortion and increased gain. It was also found from that additional electrons from radiation-induced free radicals in the Kapton film contribute to output signal of the irradiated GEM detectors. Further studies are needed to explain the mechanism of these detector performance changes.

Park, Kwang June; Baldeloma, Edwin; Park, Seongtae; White, Andrew P.; Yu, Jaehoon

2011-06-01

422

Germanium detector vacuum encapsulation  

NASA Technical Reports Server (NTRS)

This paper describes an encapsulation technology that should significantly improve the viability of germanium gamma-ray detectors for a number of important applications. A specialized vacuum chamber has been constructed in which the detector and the encapsulating module are processed in high vacuum. Very high vacuum conductance is achieved within the valveless encapsulating module. The detector module is then sealed without breaking the chamber vacuum. The details of the vacuum chamber, valveless module, processing, and sealing method are presented.

Madden, N. W.; Malone, D. F.; Pehl, R. H.; Cork, C. P.; Luke, P. N.; Landis, D. A.; Pollard, M. J.

1991-01-01

423

Detectors (4/5)  

ScienceCinema

This lecture will serve as an introduction to particle detectors and detection techniques. In the first lecture, a historic overview of particle detector development will be given. In the second lecture, some basic techniques and concepts for particle detection will be discussed. In the third lecture, the interaction of particles with matter, the basis of particle detection, will be presented. The fourth and fifth lectures will discuss different detector types used for particle tracking, energy measurement and particle identification.

None

2011-10-06

424

Detectors (5/5)  

ScienceCinema

This lecture will serve as an introduction to particle detectors and detection techniques. In the first lecture, a historic overview of particle detector development will be given. In the second lecture, some basic techniques and concepts for particle detection will be discussed. In the third lecture, the interaction of particles with matter, the basis of particle detection, will be presented. The fourth and fifth lectures will discuss different detector types used for particle tracking, energy measurement and particle identification.

None

2011-10-06

425

History of infrared detectors  

NASA Astrophysics Data System (ADS)

This paper overviews the history of infrared detector materials starting with Herschel's experiment with thermometer on February 11th, 1800. Infrared detectors are in general used to detect, image, and measure patterns of the thermal heat radiation which all objects emit. At the beginning, their development was connected with thermal detectors, such as thermocouples and bolometers, which are still used today and which are generally sensitive to all infrared wavelengths and operate at room temperature. The second kind of detectors, called the photon detectors, was mainly developed during the 20th Century to improve sensitivity and response time. These detectors have been extensively developed since the 1940's. Lead sulphide (PbS) was the first practical IR detector with sensitivity to infrared wavelengths up to ˜3 ?m. After World War II infrared detector technology development was and continues to be primarily driven by military applications. Discovery of variable band gap HgCdTe ternary alloy by Lawson and co-workers in 1959 opened a new area in IR detector technology and has provided an unprecedented degree of freedom in infrared detector design. Many of these advances were transferred to IR astronomy from Departments of Defence research. Later on civilian applications of infrared technology are frequently called "dual-use technology applications." One should point out the growing utilisation of IR technologies in the civilian sphere based on the use of new materials and technologies, as well as the noticeable price decrease in these high cost technologies. In the last four decades different types of detectors are combined with electronic readouts to make detector focal plane arrays (FPAs). Development in FPA technology has revolutionized infrared imaging. Progress in integrated circuit design and fabrication techniques has resulted in continued rapid growth in the size and performance of these solid state arrays.

Rogalski, A.

2012-09-01

426

Plasmonic lens enhanced mid-infrared quantum cascade detector  

NASA Astrophysics Data System (ADS)

We demonstrate monolithic integrated quantum cascade detectors enhanced by plasmonic lenses. Surface normal incident mid-infrared radiation is coupled to surface plasmon polaritons guided to and detected by the active region of the detector. The lens extends the optical effective active area of the device up to a 5 times larger area than for standard mesa detectors or pixel devices while the electrical active region stays the same. The extended optical area increases the absorption efficiency of the presented device as well as the room temperature performance while it offers a flexible platform for various detector geometries. A photocurrent response increase at room temperature up to a factor of 6 was observed.

Harrer, Andreas; Schwarz, Benedikt; Gansch, Roman; Reininger, Peter; Detz, Hermann; Zederbauer, Tobias; Andrews, Aaron Maxwell; Schrenk, Werner; Strasser, Gottfried

2014-10-01

427

Plasmonic lens enhanced mid-infrared quantum cascade detector  

SciTech Connect

We demonstrate monolithic integrated quantum cascade detectors enhanced by plasmonic lenses. Surface normal incident mid-infrared radiation is coupled to surface plasmon polaritons guided to and detected by the active region of the detector. The lens extends the optical effective active area of the device up to a 5 times larger area than for standard mesa detectors or pixel devices while the electrical active region stays the same. The extended optical area increases the absorption efficiency of the presented device as well as the room temperature performance while it offers a flexible platform for various detector geometries. A photocurrent response increase at room temperature up to a factor of 6 was observed.

Harrer, Andreas, E-mail: andreas.harrer@tuwien.ac.at; Schwarz, Benedikt; Gansch, Roman; Reininger, Peter; Detz, Hermann; Zederbauer, Tobias; Andrews, Aaron Maxwell; Schrenk, Werner; Strasser, Gottfried [Institute for Solid State Electronics and Center for Micro- and Nanostructures, Vienna University of Technology, 1040 Vienna (Austria)

2014-10-27

428

Status of the D0 fiber tracker and preshower detectors  

SciTech Connect

In this report we focus on the performance of the D0 central fiber tracker and preshower detectors during the high luminosity p{bar p} collisions at {radical}s = 1.96 GeV delivered by the Tevatron collider at Fermilab (Run IIb). Both fiber tracker and preshower detectors utilize a similar readout system based on high quantum efficiency solid state photo-detectors capable of converting light into electrical signals. We also give a brief description of the D0 detector and the central track trigger, and conclude with a summary on the central tracker performance.

Smirnov, Dmitri; /Notre Dame U.; ,

2009-01-01

429

First sensitivity limits of the ALPS TES detector  

E-print Network

The Any Light Particle Search II (ALPS II) requires a sensitive detection of 1064 nm photons. Thus, a low dark count rate (DC) and a high detection efficiency (DE) is needed. ALPS has set up a transition-edge sensor (TES) detector system, namely the ALPS TES detector. It is found that thermal photons from room temperature surfaces are the main contribution of dark counts for 1064 nm photon signals. Furthermore, the current setup of the ALPS TES detector shows an improvement compared to using the ALPS I detector.

Jan Dreyling-Eschweiler; for the ALPS-II collaboration

2014-09-29

430

LHCb detector performance  

NASA Astrophysics Data System (ADS)

The LHCb detector is a forward spectrometer at the Large Hadron Collider (LHC) at CERN. The experiment is designed for precision measurements of CP violation and rare decays of beauty and charm hadrons. In this paper the performance of the various LHCb sub-detectors and the trigger system are described, using data taken from 2010 to 2012. It is shown that the design criteria of the experiment have been met. The excellent performance of the detector has allowed the LHCb collaboration to publish a wide range of physics results, demonstrating LHCb's unique role, both as a heavy flavour experiment and as a general purpose detector in the forward region.

Lhcb Collaboration

2015-03-01

431

The CDFII Silicon Detector  

SciTech Connect

The CDFII silicon detector consists of 8 layers of double-sided silicon micro-strip sensors totaling 722,432 readout channels, making it one of the largest silicon detectors in present use by an HEP experiment. After two years of data taking, we report on our experience operating the complex device. The performance of the CDFII silicon detector is presented and its impact on physics analyses is discussed. We have already observed measurable effects from radiation damage. These results and their impact on the expected lifetime of the detector are briefly reviewed.

Julia Thom

2004-07-23

432

ALFA Detector Control System  

E-print Network

ALFA (Absolute Luminosity For ATLAS) is one of the sub-detectors of ATLAS (A Toroidal LHC Apparatus). The ALFA system is composed by four stations installed in the LHC tunnel 240 m away from the ATLAS interaction point. Each station has a vacuum and ventilation system, movement control and all the required electronics for signal processing. The Detector Control System (DCS) provides control and monitoring of several components and ensures the safe operation of the detector contributing to good Data Quality. This paper describes the ALFA DCS system including a detector overview, operation aspects and hardware control through a SCADA system, WinCC OA.

Oleiro Seabra, Luis Filipe; The ATLAS collaboration

2015-01-01

433

ALFA Detector Control System  

E-print Network

ALFA (Absolute Luminosity For ATLAS) is one of the sub-detectors of ATLAS/LHC. The ALFA system is composed by two stations installed in the LHC tunnel 240 m away from each side of the ATLAS interaction point. Each station has a vacuum and ventilation system, movement control and all the required electronic for signal processing. The Detector Control System (DCS) provides control and monitoring of several components and ensures the safe operation of the detector contributing to good Data Quality. This paper describes the ALFA DCS system including a detector overview, operation aspects and hardware control through a SCADA system, WinCC OA.

Oleiro Seabra, Luis Filipe; The ATLAS collaboration

2015-01-01

434

Adaptors for radiation detectors  

SciTech Connect

Described herein are adaptors and other devices for radiation detectors that can be used to make accurate spectral measurements of both small and large bulk sources of radioactivity, such as building structures, soils, vessels, large equipment, and liquid bodies. Some exemplary devices comprise an adaptor for a radiation detector, wherein the adaptor can be configured to collimate radiation passing through the adapter from an external radiation source to the radiation detector and the adaptor can be configured to enclose a radiation source within the adapter to allow the radiation detector to measure radiation emitted from the enclosed radiation source.

Livesay, Ronald Jason

2014-04-22

435

Gamma-ray observations of SN 1987A with an array of high-purity germanium detectors  

NASA Technical Reports Server (NTRS)

A balloonborne gamma-ray spectrometer comprising an array of high-purity n-type germanium (HPGe) detectors surrounded by an active NaI(T1) collimator and Compton suppressing anticoincidence shield was flown on May 29-30, 1987. The average column depth of residual atmosphere in the direction of SN 1987A at float altitude was 6.3 g/sq cm during the observation. The 3-sigma upper limit obtained for the 1238-keV line from Co-56 is 0.0013 photons/sq cm s. The corresponding limit for the 847-keV line is 0.0017 photons/sq cm s.

Sandie, W. G.; Nakano, G. H.; Chase, L. F., Jr.; Fishman, G. J.; Meegan, C. A.; Wilson, R. B.; Paciesas, W.

1988-01-01

436

Scintillator\\/Photomultiplier Ablation Detector \\/SPAD\\/ for use in reentry vehicles  

Microsoft Academic Search

The Scintillation\\/Photomultiplier Ablation Detector (SPAD), a flight-qualified radiation detector, has been developed for measuring the shape change and ablation characteristics of various reentry vehicle nosetip materials. The removal of many implanted radioactive line sources can be monitored through collimation holes by an equal number of SPADs. The key design features include high gamma ray detection efficiency, small detector cross sectional

W. A. Fitzgerald Jr.; A. W. Mitton Jr.

1977-01-01

437