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1

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

2

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

3

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

4

The determination of the efficiency of a Compton suppressed HPGe detector using Monte Carlo simulations.  

PubMed

A Compton suppressed high-purity germanium (HPGe) detector is well suited to the analysis of low levels of radioactivity in environmental samples. The difference in geometry, density and composition of environmental calibration standards (e.g. soil) can contribute to excessive experimental uncertainty to the measured efficiency curve. Furthermore multiple detectors, like those used in a Compton suppressed system, can add complexities to the calibration process. Monte Carlo simulations can be a powerful complement in calibrating these types of detector systems, provided enough physical information on the system is known. A full detector model using the Geant4 simulation toolkit is presented and the system is modelled in both the suppressed and unsuppressed mode of operation. The full energy peak efficiencies of radionuclides from a standard source sample is calculated and compared to experimental measurements. The experimental results agree relatively well with the simulated values (within ?5 - 20%). The simulations show that coincidence losses in the Compton suppression system can cause radionuclide specific effects on the detector efficiency, especially in the Compton suppressed mode of the detector. Additionally since low energy photons are more sensitive to small inaccuracies in the computational detector model than high energy photons, large discrepancies may occur at energies lower than ?100 keV. PMID:22304994

McNamara, A L; Heijnis, H; Fierro, D; Reinhard, M I

2012-04-01

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

Application of the Monte Carlo efficiency transfer method to an HPGe detector with the purpose of environmental samples measurement.  

PubMed

Monte Carlo efficiency transfer method was used to determine the full energy peak efficiency of a coaxial n-type HPGe detector. The efficiencies calibration curves for three Certificate Reference Materials were determined by efficiency transfer using a (152)Eu reference source. The efficiency values obtained after efficiency transfer were used to calculate the activity concentration of the radionuclides detected in the three materials, which were measured in a low-background gamma spectrometry system. Reported and calculated activity concentration show a good agreement with mean deviations of 5%, which is satisfactory for environmental samples measurement. PMID:25544663

Morera-Gómez, Yasser; Cartas-Aguila, Héctor A; Alonso-Hernández, Carlos M; Bernal-Castillo, Jose L; Guillén-Arruebarrena, Aniel

2015-03-01

7

The influence of dead layer thickness increase on efficiency decrease for a coaxial HPGe p-type detector  

NASA Astrophysics Data System (ADS)

The present work aims at studying the decrease in an HPGe p-type detector efficiency over its operation period and the influence of the dead layer thickness increase on this efficiency decreasing process. The study was conducted with the Canberra coaxial GC1518 p-type detector using MCNP5 code. It is found that the efficiency of this detector has reduced by 18.5% over its 13 years of operation, corresponding to the increase of dead layer thickness from 0.35 to 1.46 mm. The relative reduction in efficiency linearly depends on the dead layer thickness and both these parameters are linearly grown versus operation time. The increase of the dead layer thickness causes two effects influencing the decrease in efficiency. They are the additional shielding effect of increase in dead layer thickness (shielding effect) and the effect of decrease in germanium active volume (volume effect). It is found that for 59 keV gamma energy, the efficiency decrease is determined only by the shielding effect whilst the volume effect can be negligible. As for 511-1332 keV gamma energies, the efficiency decrease is determined by both the volume and the shielding effects.

Quang Huy, Ngo

2010-09-01

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

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

PubMed

A procedure to optimize the geometrical model of an n-type detector is described. Sixteen lines from seven point sources ((241)Am, (133)Ba, (22)Na, (60)Co, (57)Co, (137)Cs and (152)Eu) placed at three different source-to-detector distances (10, 20 and 30 cm) were used to calibrate a low-background gamma spectrometer between 26 and 1408 keV. Direct Monte Carlo techniques using the MCNPX 2.6 and GEANT 4 9.2 codes, and a semi-empirical procedure were performed to obtain theoretical efficiency curves. Since discrepancies were found between experimental and calculated data using the manufacturer parameters of the detector, a detail study of the crystal dimensions and the geometrical configuration is carried out. The relative deviation with experimental data decreases from a mean value of 18-4%, after the parameters were optimized. PMID:20643556

Cabal, Fatima Padilla; Lopez-Pino, Neivy; Bernal-Castillo, Jose Luis; Martinez-Palenzuela, Yisel; Aguilar-Mena, Jimmy; D'Alessandro, Katia; Arbelo, Yuniesky; Corrales, Yasser; Diaz, Oscar

2010-12-01

10

Wavelet Analysis in Point Contact HPGe Detectors  

NASA Astrophysics Data System (ADS)

The low-noise and pulse-shape discrimination characteristics of point-contact High-Purity Germanium (HPGe) detectors have made them a promising detector technology for neutrinoless double-beta (0???) decay experiments and direct dark matter searches. In 0??? searches, substantial background rejection can be achieved if one can identify and reject multiple site interactions. Dark matter searches require low energy thresholds and noise reduction in the events is thus highly desirable. This talk will introduce some of the techniques of wavelet analysis that can be used to de-noise pulse shapes from point contact HPGe detectors, and to separate multi-site interactions from single-site interactions. The work presented here was done in the context of the Majorana Demonstrator project, which will search for neutrinoless double beta decay as well as direct dark matter interactions using an array of point contact HPGe detectors.

Martin, Ryan

2010-11-01

11

Determining HPGe Total Detection Efficiency Using ?–? Coincidence  

SciTech Connect

Abstract Both the peak and total detection efficiencies are generally needed in order to calculate sample activity from a gamma spectroscopic measurement, except in the case of isotope specific calibration. This is particularly true when the sample is in close proximity to the detector and corrections for cascade summing effects are required to avoid significant inaccuracy in the result. These corrections use the total detection efficiency to correct for summing-in and summing-out events, and the extent of the correction depends on both the geometry and the gamma cascade for the isotope in question. Experimentally determining the total efficiency is a labor intensive endeavor requiring multiple measurements with a set of single-gamma-emitting standards. Modeling the total efficiency vs. energy may be less time consuming, but is also likely to produce less confidence in the final result. Pacific Northwest National Laboratory's Radiation Detection and Nuclear Sciences group has constructed a low background 14-crystal HPGe array for sample measurement; in all measurements, samples will be in close proximity to the germanium crystals. This close geometry and the sheer number efficiency calibrations required for the system have led us to investigate methods to simplify the efficiency calibration procedure. One method we are developing uses the Y-Y coincidence plane to isolate Compton scattering event populations, allowing experimental determination of total detection efficiency values from the measurement of a single mixed isotope standard. A description of the analysis and experimental results of this method are presented.

Erikson, Luke E.; Keillor, Martin E.; Aalseth, Craig E.; Hossbach, Todd W.; Mizouni, Leila K.; Stavenger, Timothy J.; McDonald, Benjamin S.; Lepel, Elwood A.; Greenwood, Lawrence R.; Rutherford, Crystal E.

2013-05-01

12

Monte Carlo analysis of the influence of germanium dead layer thickness on the HPGe gamma detector experimental efficiency measured by use of extended sources.  

PubMed

We have carried out a study to figure out the influence of crystal inactive-layer thickness on gamma spectra measured by an HPGe detector. The thickness of this dead layer (DL) is not known (no information about it was delivered by the manufacturer) due to the existence of a transition zone where photons are increasingly absorbed. To perform this analyses a virtual model of a Canberra HPGe detector was produced with the aid of MCNPX 2.7 code. The main objective of this work is to produce an optimal modeling for our GPGe detector. To this end, the study included the analysis of the total inactive germanium layer thickness and the active volume that are needed in order to obtain the smallest discrepancy between calculated and experimental efficiencies. Calculations and measurements were performed for all of the radionuclides included in a standard calibration gamma cocktail solution. Different geometry sources were used: a Marinelli and two other new sources represented as S(1) and S(2). The former was used for the determination of the active volume, whereas the two latter were used for the determination of the face and lateral DL, respectively. The model was validated by comparing calculated and experimental full energy peak efficiencies in the 50-1900keV energy range. the results show that the insertion of the DL parameter in the modeling is absolutely essential to reproduce the experimental results, and that the thickness of this DL varies from one position to the other on the detector surface. PMID:25464173

Chham, E; García, F Piñero; El Bardouni, T; Ferro-García, M Angeles; Azahra, M; Benaalilou, K; Krikiz, M; Elyaakoubi, H; El Bakkali, J; Kaddour, M

2014-09-22

13

Constraining solar hidden photons using HPGe detector  

NASA Astrophysics Data System (ADS)

In this Letter we report on the results of our search for photons from a U(1) gauge factor in the hidden sector of the full theory. With our experimental setup we observe the single spectrum in a HPGe detector arising as a result of the photoelectric-like absorption of hidden photons emitted from the Sun on germanium atoms inside the detector. The main ingredient of the theory used in our analysis, a severely constrained kinetic mixing from the two U(1) gauge factors and massive hidden photons, entails both photon into hidden state oscillations and a minuscule coupling of hidden photons to visible matter, of which the latter our experimental setup has been designed to observe. On a theoretical side, full account was taken of the effects of refraction and damping of photons while propagating in Sun's interior as well as in the detector. We exclude hidden photons with kinetic couplings ?>(2.2×10-13-3×10-7) in the mass region 0.2 eV?m???30 keV. Our constraints on the mixing parameter ? in the mass region from 20 eV up to 15 keV prove even slightly better then those obtained recently by using data from the CAST experiment, albeit still somewhat weaker than those obtained from solar and HB stars lifetime arguments.

Horvat, R.; Kekez, D.; Kr?mar, M.; Kre?ak, Z.; Ljubi?i?, A.

2013-04-01

14

A trapezoid approach for the experimental total-to-peak efficiency curve used in the determination of true coincidence summing correction factors in a HPGe detector  

NASA Astrophysics Data System (ADS)

In this work, a simple method for true coincidence correction is suggested for a voluminous source measured in close detection geometry for a HPGe detector. TrueCoinc program based on Sudár's algorithm was used to determine true coincidence summing correction (TCS) factors by using full energy peak (FEP) efficiency, and total-to-peak (TTP) efficiency curves in which experimental efficiencies are obtained from almost coincident-free radionuclides such as 54Mn, 57Co, 65Zn, 109Cd, 137Cs and 241Am. In order to calculate TTP efficiency curve three different approaches were tested. One of them is new and here called trapezoid approach which was used successfully in determining total count of spectrum for the TTP efficiency curves. According to different TTP determination methods, the changes in true coincidence factors are observed. The FEP efficiency curves are also established for a cylindrical source. Then, TCS factors were determined for the particular peaks of daughters of 226Ra, 238U, and 232Th using the suggested method. Those activities measured from some certified reference materials such as IAEA RGU-1 and RGTh-1 are used to validate the present TCS correction procedure.

?ahiner, Eren; Meriç, Niyazi

2014-03-01

15

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

16

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

17

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

18

Performance of CdTe, HPGe and NaI(Tl) detectors for radioactivity measurements.  

PubMed

The characteristics and performances of the NIST High-Purity Germanium (HPGe), Sodium Iodide (NaI(Tl)) and Cadmium Telluride (CdTe) gamma-ray detectors were studied. The efficiencies, the minimum detectable activities and the energy resolutions of each were measured and compared. The data were analyzed using different software packages. The measurements were performed in a low background radiation environment using calibrated point sources. The CdTe detector showed a higher energy resolution than the NaI(Tl) detector but a lower efficiency than both the HPGe and NaI(Tl) detectors. This makes it a suitable detector only for relatively high activity measurements restricted to the 35 keV to 200 keV energy range. PMID:14687635

Perez-Andujar, A; Pibida, L

2004-01-01

19

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

20

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

21

A fast VLSI preamplifier for segmented HPGe ?-ray detectors  

Microsoft Academic Search

We developed and realized a fast integrated charge-sensitive preamplifier for segmented High Purity Germanium (HPGe) detectors, able to directly drive long 50 ? coaxial cables. The circuit is realized in a 5V 0.8?m CMOS technology. It includes an external input FET, mod. BF862, which can be easily replaced if necessary. The charge-to-voltage gain and the fall time are set by

A. Pullia; F. Zocca; S. Riboldi; C. Cattadori

2006-01-01

22

Experimental determination of the HPGe spectrometer efficiency curve.  

PubMed

A review of the calibration procedures of the semiconductor HPGe spectrometer is presented in this paper. Calibration standards were prepared using the standardized radioactive solution of the common monoenergetic radionuclides mixture and standardized multigamma (152)Eu solution. The matrix materials were spiked using the activated carbon, and homogenized mechanically or by suspension in C(2)H(5)OH. Experimentally determined efficiency curves were compared with those obtained by Monte Carlo simulation. PMID:18343144

Vukanac, I; Djurasevi?, M; Kandi?, A; Novkovi?, D; Nadjerdj, L; Milosevi?, Z

2008-01-01

23

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

24

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

25

Interaction position resolution simulations and in-beam measurements of the AGATA HPGe detectors  

Microsoft Academic Search

The interaction position resolution of the segmented HPGe detectors of an AGATA triple cluster detector has been studied through Monte Carlo simulations and in an in-beam experiment. A new method based on measuring the energy resolution of Doppler-corrected ??ray spectra at two different target to detector distances is described. This gives the two-dimensional position resolution in the plane perpendicular to

P.-A. Söderström; F. Recchia; J. Nyberg; A. Al-Adili; S. Aydin; D. Bazzacco; P. Bednarczyk; B. Birkenbach; D. Bortolato; A. J. Boston; H. C. Boston; B. Bruyneel; D. Bucurescu; E. Calore; S. Colosimo; F. C. L. Crespi; N. Dosme; J. Eberth; E. Farnea; F. Filmer; A. Gadea; A. Gottardo; X. Grave; J. Grebosz; R. Griffiths; M. Gulmini; T. Habermann; H. Hess; G. Jaworski; P. Jones; D. S. Judson; R. Kempley; A. Khaplanov; E. Legay; D. Lersch; J. Ljungvall; A. Lopez-Martens; W. Meczynski; D. Mengoni; C. Michelagnoli; P. Molini; D. R. Napoli; R. Orlandi; G. Pascovici; A. Pullia; P. Reiter; E. Sahin; J. F. Smith; J. Strachan; D. Tonev; C. Unsworth; J. J. Valiente-Dobón; C. Veyssiere; A. Wiens

2011-01-01

26

Evaluation of sup 137 Cs in pond sediment with an underwater HPGe detector  

SciTech Connect

The amount of 137Cs was measured in the PAR pond on the Savannah River Site. An underwater HPGe detector was used to inventory the gamma-emitting radionuclides in the sediment of the pond. The description and process of the equipment was given in this report. From the analysis of the compiled data, the drawdown can proceed in radiological guide lines.

Winn, W.G.

1992-01-01

27

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

28

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

29

Effects due to a PuC source on a HPGe detector and the corresponding neutron shielding  

Microsoft Academic Search

A gamma spectrum of a Pu-C source is measured using a p-type HPGe detector, whose three peaks (full energy, single-escape and double-escape peak) can be used as a calibration source for the beam energy measurement system of BEPCII. The effect of fast neutron damage on the energy resolution of the HPGe detector is studied, which indicates that the energy resolution

Jian-Yong Zhang; Cheng-Dong Fu; Xiao-Hu Mo; Zi-Liang Zhang; Dao-Wu Li; Bao-Yi Wang

2011-01-01

30

Single channel beta-gamma coincidence system for radioxenon measurement using well-type HPGe and plastic scintillator detectors  

NASA Astrophysics Data System (ADS)

In order to improve detection sensitivity for radioxenon isotopes, a new single channel beta-gamma coincidence system has been developed. The system combines a well-type High-purity Germanium (HPGe) detector to measure gamma or X radiation and a plastic scintillator detector to obtain electron radiation. A 133Xe sample has been produced and the radioactive concentration was determined with length-compensated method based on three internal gas proportional counters. The performance of system has been checked by measuring 133Xe sample with and without coincidence. The coincidence detection efficiency of 81 keV gamma-ray from decay of 133Xe was calibrated to be 0.34 (1±2.4%), and the Minimum detectable activity (MDA) of the beta-gamma coincidence system for 133Xe was determined to be 1.8 mBq after one day of measurement.

Xie, Feng; Jiang, Wengang; Li, Xuesong; He, Xiaobing; Zhang, Jiamei; Yu, Gongshuo

2013-11-01

31

Effects due to a Pu-C source on a HPGe detector and the corresponding neutron shielding  

NASA Astrophysics Data System (ADS)

A gamma spectrum of a Pu-C source is measured using a p-type HPGe detector, whose three peaks (full energy, single-escape and double-escape peak) can be used as a calibration source for the beam energy measurement system of BEPCII. The effect of fast neutron damage on the energy resolution of the HPGe detector is studied, which indicates that the energy resolution begins to deteriorate when the detector is subject to 2×107 n/cm2 fast neutrons. The neutron damage mechanism and detector repair methods are reviewed. The Monte Carlo simulation technique is utilized to study the shielding of the HPGe detector from the fast neutron radiation damage, which is of great significance for the future commissioning of the beam energy measurement system.

Zhang, Jian-Yong; Fu, Cheng-Dong; Mo, Xiao-Hu; Zhang, Zi-Liang; Li, Dao-Wu; Wang, Bao-Yi

2011-07-01

32

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

33

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

E-print Network

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.

Oleg Chkvorets

2008-12-05

34

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

35

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

36

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

37

Dead-layer thickness effect for gamma spectra measured in an HPGe p-type detector  

NASA Astrophysics Data System (ADS)

The present work studies the influence of the dead-layer thickness effect on the gamma spectra of a high purity germanium (HPGe) p-type detector at two different points in time. The study was conducted with the Canberra GC1518 detector, which had a dead-layer thickness of 1.15 mm in 2005 and 1.46 mm in 2009. The measurement of gamma spectra for the reference point-like sources, 137Cs, 60Co and 22Na, indicated that the spectra in the energy region of 50-170 keV measured in 2009 were higher than those measured in 2005. This result implies that, in this energy interval, the dead-layer thickness effect is observed, which can be explained by the contribution of the delayed signals. Furthermore, the measured spectra in this energy region were higher than those calculated by MCNP5 code. These findings make it possible to evaluate the contribution of delayed signals, which are proportional to the thickness of the dead layer.

Huy, Ngo Quang

2011-06-01

38

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

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

39

Double {beta} experiments with the help of scintillation and HPGe detectors at Gran Sasso  

SciTech Connect

A search for double beta decay of {sup 64,70}Zn, {sup 180,186}W was carried out by using low background ZnWO{sub 4} crystal scintillators, while a CeCl{sub 3} scintillation detector was applied to investigate 2{beta} processes in {sup 136,138,142}Ce. A search for 2{beta} decay of {sup 96,104}Ru, {sup 156,158}Dy, {sup 190,198}Pt and study of 2{nu}2{beta} decay of {sup 100}Mo to the first excited 0{sup +} level of {sup 100}Ru were realized by ultra-low background HPGe {gamma} spectrometry. Moreover, CdWO{sub 4} crystal scintillators from enriched {sup 106}Cd and {sup 116}Cd isotopes were developed to search for 2{beta} decay of {sup 106}Cd and {sup 116}Cd. Finally, experiments aimed to investigate {sup 96,104}Ru and {sup 116}Cd are in progress and a new phase of the experiment to search for 2{beta} processes in {sup 106}Cd is in preparation.

Barabash, A.; Konovalov, S. I.; Umatov, V. I. [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Belli, P.; D'Angelo, S.; Di Marco, A. [INFN, Sezione di Roma ''Tor Vergata'', Rome (Italy); Bernabei, R. [INFN, Sezione di Roma ''Tor Vergata '', Rome (Italy); Dipartimento di Fisica, Universita di Roma ''Tor Vergata'', Rome (Italy); Boiko, R. S.; Chernyak, D. M.; Danevich, F. A.; Kobychev, V. V.; Kropivyansky, B. N.; Kudovbenko, V. M.; Nagorny, S. S.; Podviyanuk, R. B.; Polischuk, O. G.; Tretyak, V. I.; Vyshnevskyi, I. M.; Yurchenko, S. S. [Institute for Nuclear Research, Kyiv (Ukraine); Brudanin, V. B. [Joint Institute for Nuclear Research, Dubna (Russian Federation); and others

2011-12-16

40

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

41

Low background HPGe spectrometer in investigations of 2? decay  

NASA Astrophysics Data System (ADS)

The low background high sensitive HPGe spectrometer called OBELIX is briefly described. The calibration measurements using 152Eu, 133Ba and La2O3 sources in different geometries, the obtained efficiency curves for OBELIX HPGe detector, the results of measurements of radioactivity of the NEMO-3 sources (100Mo, 150Nd) as well as future plans for OBELIX detector (e.g. 0?EC/EC decay of 106Cd) are presented.

Rukhadze, Ekaterina; Obelix Collaboration, Tgv Collaboration, Supernemo Collaboration

2013-08-01

42

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

NASA Astrophysics Data System (ADS)

Coincident ? rays from a 252Cf 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 ?Ci252Cf source to cover a large solid angle for ?-ray measurement with a reasonable reconstruction of the multiplicity. Neutron multiplicity was determined in certain cases by identifying the prompt ? 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 ?-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.

2010-12-01

43

Monte-Carlo optimisation of a Compton suppression system for use with a broad-energy HPGe detector  

NASA Astrophysics Data System (ADS)

Monte-Carlo simulations are used to evaluate and optimise multiple components of a Compton Suppression System based upon a Broad-energy HPGe primary detector. Several materials for the secondary crystal are evaluated, including NaI(Tl), BGO and LaBr3(Ce). BGO was found to be the most effective across the required energy range, with the sizes of the proposed veto detector then optimised to extract the maximum performance for a given volume of material. Suppression factors are calculated for a range of nuclides (both single and cascade emitters) with improvements of 2 for the Compton Suppression Factors, and 10 for the continuum reduction when compared to the Compton suppression system currently in use. This equates to a reduction in the continuum by up to a factor of ~240 for radionuclides such as 60Co, which is crucial for the detection of low-energy, low-activity ? emitters typically swamped by such a continuum.

Britton, R.; Burnett, J. L.; Davies, A. V.; Regan, P. H.

2014-10-01

44

Spatial calibration via imaging techniques of a novel scanning system for the pulse shape characterisation of position sensitive HPGe detectors  

NASA Astrophysics Data System (ADS)

In this work, a novel imaging technique for the spatial calibration of a gamma camera is presented. The latter is aimed for the characterisation of the charge signals of 3D-position sensitive HPGe detectors. The characterisation method itself is based on pulse shape comparison (PSC) technique. The performance of the device is improved by implementing a gamma camera or position sensitive detector (PSD). This PSD consists of a uniform LYSO scintillating crystal optically glued to a crossed-wire position sensitive photomultiplier tube (PSPMT) from Hamamatsu. The individual multianode readout (IMAR) approach is used to improve its spatial resolution and to enlarge its field of view. A Compton scattering imaging technique is implemented to perform an accurate position calibration of the gamma camera.

Goel, N.; Domingo-Pardo, C.; Engert, T.; Gerl, J.; Kojouharov, I.; Schaffner, H.

2011-10-01

45

High efficiency photoionization detector  

Microsoft Academic Search

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

1984-01-01

46

High efficiency photoionization detector  

Microsoft Academic Search

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

David F

1984-01-01

47

Response of AGATA Segmented HPGe Detectors to Gamma Rays up to 15.1 MeV  

E-print Network

The response of AGATA segmented HPGe detectors to gamma rays in the energy range 2-15 MeV was measured. The 15.1 MeV gamma rays were produced using the reaction d(11B,ng)12C at Ebeam = 19.1 MeV, while gamma-rays between 2 to 9 MeV were produced using an Am-Be-Fe radioactive source. The energy resolution and linearity were studied and the energy-to-pulse-height conversion resulted to be linear within 0.05%. Experimental interaction multiplicity distributions are discussed and compared with the results of Geant4 simulations. It is shown that the application of gamma-ray tracking allows a suppression of background radiation following neutron capture by Ge nuclei. Finally the Doppler correction for the 15.1 MeV gamma line, performed using the position information extracted with Pulse-shape Analysis, is discussed.

F. C. L. Crespi; R. Avigo; F. Camera; S. Akkoyun; A. Atac; D. Bazzacco; M. Bellato; G. Benzoni; N. Blasi; D. Bortolato; S. Bottoni; A. Bracco; S. Brambilla; B. Bruyneel; S. Cerutia; M. Ciemala; S. Coelli; J. Eberth; C. Fanin; E. Farnea; A. Gadea; A. Giaz; A. Gottardo; H. Hess; M. Kmiecik; S. Leoni; A. Maj; D. Mengoni; C. Michelagnoli; B. Million; D. Montanari; L. Pellegri; F. Recchia; P. Reiter; S. Riboldi; C. A. Ur; V. Vandone; J. J. Valiente-Dobon; O. Wieland; A. Wiens; The AGATA Collaboration

2012-09-06

48

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

49

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

50

Uranium Isotopic and Quantitative Analysis Using a Mechanically-Cooled HPGe Detector  

SciTech Connect

A new, portable high-resolution spectroscopy system based on a high-purity germanium detector cooled with a miniature Stirling-cycle cooler, ORTEC trans-SPEC, has recently become commercially available. The use of a long-life mechanical cooling system eliminates the need for liquid nitrogen. The purpose of this study was to determine the applicability of this new instrument for isotopic and quantitative analyses of uranium samples. The results of the performance of the trans-SPEC with the combination of PC-FRAM and ISOTOPIC software packages are described in this paper. An optimal set of analysis parameters for uranium measurements is proposed.

Solodov, Alexander A [ORNL

2008-01-01

51

Fast neutron sensitivity with HPGe  

Microsoft Academic Search

In addition to being excellent gamma-ray detectors, germanium detectors are also sensitive to fast neutrons. Incident neutrons undergo inelastic scattering {Ge(n,n')Ge*} off germanium nuclei and the resulting excited states emit gamma rays or conversion electrons. The response of a standard 140% high-purity germanium (HPGe) detector with a bismuth germanate (BGO) anti-coincidence shield was measured for several neutron sources to characterize

Allen Seifert; Walter K. Hensley; Edward R. Siciliano; W. Karl Pitts

2007-01-01

52

High-efficiency photoionization detector  

Microsoft Academic Search

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

1981-01-01

53

Study of the real part (f') of anomalous scattering factors for the elements of atomic number from Z = 64 to 73 using HPGe detector  

NASA Astrophysics Data System (ADS)

The real part ( f') of the anomalous scattering factors for the targets of atomic number ranging from Z = 64 to 73 (Gd, Dy, Yb, Hf and Ta) are determined using low-energy external bremsstrahlung (EB) radiations. In this method, the EB photons are produced by beta particles from a weak beta source of 90Sr - 90Y in a nickel foil. The emitted EB photons are incident on the elemental targets of our study and the transmitted spectrum of the emerging photons from the target is measured using an ORTEC-made High-Purity Germanium (HPGe) detector coupled to an 8 K multichannel analyzer. The transmitted spectra show a sharp decrease in intensity at the K shell binding energies of the target atoms. The regions around the decreased portion have been used to determine the real part of the anomalous scattering factors. The experimentally measured values are found to be in good agreement with the available theoretical values.

Hosur, Savita B.; Naik, L. R.; Badiger, N. M.

2013-05-01

54

Calibration of an HPGe detector and self-attenuation correction for 210Pb: Verification by alpha spectrometry of 210Po in environmental samples  

NASA Astrophysics Data System (ADS)

In this work the calibration of an HPGe detector for 210Pb measurement is realised by a liquid standard source and the determination of this radionuclide in solid environmental samples by gamma spectrometry takes into account a correction factor for self-attenuation of its 46.5 keV line. Experimental, theoretical and Monte Carlo investigations are undertaken to evaluate self-attenuation for cylindrical sample geometry. To validate this correction factor, 210Po (at equilibrium with 210Pb) alpha spectrometry procedure using microwave acid digestion under pressure is developed and proposed. The different self-attenuation correction methods are in coherence, and corrected 210Pb activities are in good agreement with the results of 210Po. Finally, self-attenuation corrections are proposed for environmental solid samples whose density ranges between 0.8 and 1.4 g/cm 3 and whose mass attenuation coefficient is around 0.4 cm 2/g.

Saïdou; Bochud, François; Laedermann, Jean-Pascal; Buchillier, Thierry; Njock Moïse, Kwato; Froidevaux, Pascal

2007-08-01

55

Fast Neutron Sensitivity with HPGe  

SciTech Connect

In addition to being excellent gamma-ray detectors, germanium detectors are also sensitive to fast neutrons. Incident neutrons undergo inelastic scattering {Ge(n,n?)Ge*} off germanium nuclei and the resulting excited states emit gamma rays or conversion electrons. The response of a standard 140% high-purity germanium (HPGe) detector with a bismuth germanate (BGO) anti-coincidence shield was measured for several neutron sources to characterize the ability of the HPGe detector to detect fast neutrons. For a sensitivity calculation performed using the characteristic fast neutron response peak that occurs at 692 keV, the 140% germanium detector system exhibited a sensitivity of ~175 counts / kg of WGPumetal in 1000 seconds at a source-detector distance of 1 meter with 4 in. of lead shielding between source and detector. Theoretical work also indicates that it might be possible to use the shape of the fast-neutron inelastic scattering signatures (specifically, the end-point energy of the long high energy tail of the resulting asymmetric peak) to gain additional information about the energy distribution of the incident neutron spectrum. However, the experimentally observed end-point energies appear to be almost identical for each of the fast neutron sources counted. Detailed MCNP calculations show that the neutron energy distributions impingent on the detector for these sources are very similar in this experimental configuration, due to neutron scattering in a lead shield (placed between the neutron source and HPGe detector to reduce the gamma ray flux), the BGO anti-coincidence detector, and the concrete floor.

Seifert, Allen; Hensley, Walter K.; Siciliano, Edward R.; Pitts, W. K.

2008-01-22

56

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

57

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

58

A noninvasive dose estimation system for clinical BNCT based on PG-SPECT--conceptual study and fundamental experiments using HPGe and CdTe semiconductor detectors.  

PubMed

A noninvasive method for measuring the absorbed dose distribution during the administration of clinical boron neutron capture therapy (BNCT) using an online three-dimensional (3D) imaging system is presented. This system is designed to provide more accurate information for treatment planning and dosimetry. The single-photon emission computed tomography (SPECT) technique is combined with prompt gamma-ray analysis (PGA) to provide an ideal dose estimation system for BNCT. This system is termed PG-SPECT. The fundamental feasibility of the PG-SPECT system for BNCT is confirmed under the following conditions: (1) a voxel size of 1 x 1 x 1 cm3, comparable to the spatial resolution of our standard dosimetric technique using gold wire activation, where data are available for every 5-10 mm of wire length; (2) a reaction rate of 10B(n,alpha)7Li within the measurement volume is greater than 1.1 x l0(6) interactions/cm3/s, corresponding to a thermal neutron flux of 5 x 10(8) n/cm2/s and a 10B concentration of greater than 10 ppm for the deepest part of the tumor volume under typical BNCT clinical conditions; (3) statistical uncertainty of the count rate for 10B(n,alpha)7Li prompt gamma rays is 10% or less. The desirable characteristics of a detector for the PG-SPECT system were determined by basic experiments using both HPGe and CdTe semiconductor detectors. The CdTe semiconductor detector has the greatest potential for this system because of its compactness and simplicity of maintenance. PMID:11011742

Kobayashi, T; Sakurai, Y; Ishikawa, M

2000-09-01

59

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

NASA Astrophysics Data System (ADS)

The absolute total and absolute peak detection efficiencies of gamma ray detector materials NaI:Tl, CdZnTe, HPGe, HPXe, LaBr 3:Ce and LaCl 3:Ce were simulated and compared to that of polyvinyltoluene (PVT). The dimensions of the PVT detector were 188.82 cm×60.96 cm×5.08 cm, which is a typical size for a single-panel portal monitor. The absolute total and peak detection efficiencies for these detector materials for the point, line and spherical source geometries of 60Co (1332 keV), 137Cs (662 keV) and 241Am (59.5 keV) were simulated at various source-to-detector distances using the Monte Carlo N-Particle software (MCNP5-V1.30). The comparison of the absolute total detection efficiencies for a point, line and spherical source geometry of 60Co and 137Cs at different source-to-detector distance showed that the absolute detection efficiency for PVT is higher relative to the other detectors of typical dimensions for that material. However, the absolute peak detection efficiency of some of these detectors are higher relative to PVT, for example the absolute peak detection efficiency of NaI:Tl (7.62 cm diameter×7.62 cm long), HPGe (7.62 cm diameter×7.62 cm long), HPXe (11.43 cm diameter×60.96 cm long), and LaCl 3:Ce (5.08 cm diameter×5.08 cm long) are all greater than that of a 188.82 cm×60.96 cm×5.08 cm PVT detector for 60Co and 137Cs for all geometries studied. The absolute total and absolute peak detection efficiencies of a right circular cylinder of NaI:Tl with various diameters and thicknesses were determined for a point source. The effect of changing the solid angle on the NaI:Tl detectors showed that with increasing solid angle and detector thickness, the absolute efficiency increases. This work establishes a common basis for differentiating detector materials for passive portal monitoring of gamma ray radiation.

Ayaz-Maierhafer, Birsen; DeVol, Timothy A.

2007-08-01

60

Average neutron detection efficiency for DEMON detectors  

NASA Astrophysics Data System (ADS)

The neutron detection efficiency of a DEMON detector, averaged over the whole volume, was calculated using GEANT and applied to determine neutron multiplicities in an intermediate heavy ion reaction. When a neutron source is set at a distance of about 1 m from the front surface of the detector, the average efficiency, ?av, is found to be significantly lower (20-30%) than the efficiency measured at the center of the detector, ?0. In the GEANT simulation the ratio R=?av/?0 was calculated as a function of neutron energy. The experimental central efficiency multiplied by R was then used to determine the average efficiency. The results were applied to a study of the 64Zn+112Sn reaction at 40 A MeV which employed 16 DEMON detectors. The neutron multiplicity was extracted using a moving source fit. The derived multiplicities are compared well with those determined using the neutron ball in the NIMROD detector array in a separate experiment. Both are in good agreement with multiplicities predicted by a transport model calculation using an antisymmetric molecular dynamics (AMD) model code.

Zhang, S.; Lin, W.; Rodrigues, M. R. D.; Huang, M.; Wada, R.; Liu, X.; Zhao, M.; Jin, Z.; Chen, Z.; Keutgen, T.; Kowalski, S.; Hagel, K.; Barbui, M.; Bonasera, A.; Bottosso, C.; Materna, T.; Natowitz, J. B.; Qin, L.; Sahu, P. K.; Schmidt, K. J.; Wang, J.

2013-05-01

61

High efficiency CCD detectors at UV wavelengths  

NASA Astrophysics Data System (ADS)

The Faint Intergalactic Redshifted Emission Balloon (FIREBall) is a NASA/CNES balloon-borne ultraviolet multi-object spectrograph designed to observe the diffuse gas around galaxies (the circumgalactic medium) via line emission redshifted to ~205 nm. FIREBall uses a ultraviolet-optimized delta doped e2v CCD201 with a custom designed high efficiency five layer anti-reflection coating. This combination achieves very high quantum efficiency (QE) and photon-counting capability, a first for a CCD detector in this wavelength range. We also present new work on red blocking mirror coatings to reduce red leak.

Hamden, Erika T.; Jewell, April D.; Gordon, Samuel; Hennessy, John; Hoenk, Michael E.; Nikzad, Shouleh; Schiminovich, David; Martin, D. Christopher

2014-07-01

62

Efficiency of thermoluminescent detectors to heavy charged particles  

Microsoft Academic Search

The efficiency of TLD-700 thermoluminescent detectors is studied for various ions as a function of energy. A new model for calculation of efficiency has been developed, based on the detector response to reference radiation, and the radial dose distribution of heavy ions only. No free parameters have to be used to calculate the thermoluminescence detector (TLD) efficiency as a function

O. B. Geiß; M. Krämer; G. Kraft

1998-01-01

63

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

64

Absolute efficiency measurements with the 10B based Jalousie detector  

NASA Astrophysics Data System (ADS)

The 10B based Jalousie detector is a replacement for 3He counter tubes, which are nowadays less affordable for large area detectors due to the 3He crisis. In this paper we investigate and verify the performance of the new 10B based detector concept and its adoption for the POWTEX diffractometer, which is designed for the detection of thermal neutrons with predicted detection efficiencies of 75-50% for neutron energies of 10-100 meV, respectively. The predicted detection efficiency has been verified by absolute measurements using neutrons with a wavelength of 1.17 Å (59 meV).

Modzel, G.; Henske, M.; Houben, A.; Klein, M.; Köhli, M.; Lennert, P.; Meven, M.; Schmidt, C. J.; Schmidt, U.; Schweika, W.

2014-04-01

65

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

66

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

67

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

SciTech Connect

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

Winn, W.G.

1999-07-28

68

Testing the Ge detectors for the MAJORANA DEMONSTRATOR  

E-print Network

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

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

2014-04-29

69

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

70

High-efficiency fast-neutron threshold detector  

Microsoft Academic Search

This patent application discloses a high-efficiency apparatus for detecting fast neutrons includes an assembly of disks of solid state charged particle detector material, or other appropriate charged particle detecting devices, disposed between adjacent thick (on the order of 1 mm) disks of a fissionable material. The fissionable material must be an isotope that has a sharp increase in the neutron-induced

1990-01-01

71

Si(Li) detector parameters optimization using efficiency calibration  

NASA Astrophysics Data System (ADS)

The efficiency of a Si(Li) detector was determined experimentally and adequately simulated with the GEANT4 code in the energy range from 5 to 27 keV. The point-like sources used were 55Fe, 65Zn, 85Sr, 109Cd and 241Am. For simulation of the detector response we have used a recent version of GEANT4 8.0 (Released 10 February 2006). In this version, all needed electro-magnetic processes are considered, essentially Compton scattering, photo-electric effect, Raleigh effect, multiple scattering, fluorescence and Auger effect and ionization. The detector was firstly modeled using its technical dimensions supplied by the manufacturer. Then these dimensions were optimized in order to reproduce the experimental efficiency. An agreement better than 98 % for almost all the energy lines (5 to 27 keV) between experimental and simulated efficiency values was obtained by adjusting some detector parameters. Those optimized parameters are the front dead layer of the crystal which is increased by 1.3 ?m and the crystal-to-window distance which is increased by 0.7 mm. Those results indicated that our simulation code is operational for a reliable interpolation and extrapolation of experimental efficiency data and can be accurately used for simulation of X-ray fluorescence spectrum acquisition.

Haifa, Ben Abdelwahed; Omrane, Kadri; Adel, Trabelsi

2007-09-01

72

Electromechanically cooled germanium radiation detector system  

Microsoft Academic Search

We have successfully developed and fielded an electromechanically cooled germanium radiation detector (EMC-HPGe) at Lawrence Livermore National Laboratory (LLNL). This detector system was designed to provide optimum energy resolution, long lifetime, and extremely reliable operation for unattended and portable applications. For most analytical applications, high purity germanium (HPGe) detectors are the standard detectors of choice, providing an unsurpassed combination of

A. D. Lavietes; G. Joseph Mauger; E. H. Anderson

1999-01-01

73

Direct determination of the hit locations from experimental HPGe pulses  

NASA Astrophysics Data System (ADS)

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

Désesquelles, P.; Boston, A. J.; Boston, H. C.; Cresswell, J. R.; Dimmock, M. R.; Lazarus, I. H.; Ljungvall, J.; Nelson, L.; Nga, D.-T.; Nolan, P. J.; Rigby, S. V.; Simpson, J.; Van-Oanh, N.-T.

2013-11-01

74

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

75

Charge collection efficiency simulations of irradiated silicon strip detectors  

NASA Astrophysics Data System (ADS)

During the scheduled high luminosity upgrade of LHC, the world's largest particle physics accelerator at CERN, the position sensitive silicon detectors installed in the vertex and tracking part of the CMS experiment will face a more intense radiation environment than the present system was designed for. Thus, to upgrade the tracker to the required performance level, comprehensive measurements and simulation studies have already been carried out. Essential information of the performance of an irradiated silicon detector is obtained by monitoring its charge collection efficiency (CCE). From the evolution of CCE with fluence, it is possible to directly observe the effect of the radiation induced defects on the ability of the detector to collect charge carriers generated by traversing minimum ionizing particles (MIPs). In this paper the numerically simulated CCE and CCE loss between the strips of irradiated silicon strip detectors are presented. The simulations based on the Synopsys Sentaurus TCAD framework were performed before and after irradiation for fluences up to 1.5 × 1015 neqcm?2 for n-on-p sensors. A two level defect model and non-uniform three level defect model were applied for the proton irradiation simulations, and a two level model for neutrons. The results are presented together with the measurements of strip detectors irradiated by different particles and fluences and show considerable agreement for both CCE and its position dependency.

Peltola, T.

2014-12-01

76

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

77

Roadmap for High Efficiency Solid-State Neutron Detectors  

SciTech Connect

Solid-state thermal neutron detectors are generally fabricated in a planar configuration by coating a layer of neutron-to-alpha converter material onto a semiconductor. The as-created alpha particles in the material are expected to impinge the semiconductor and create electron-hole pairs which provide the electrical signal. These devices are limited in efficiency to a range near (2-5%)/cm{sup 2} due to the conflicting thickness requirements of the converter layer. In this case, the layer is required to be thick enough to capture the incoming neutron flux while at the same time adequately thin to allow the alpha particles to reach the semiconductor. A three dimensional matrix structure has great potential to satisfy these two requirements in one device. Such structures can be realized by using PIN diode pillar elements to extend in the third dimension with the converter material filling the rest of the matrix. Our strategy to fabricate this structure is based on both ''top-down'' and ''bottom-up'' approaches. The ''top down'' approach employs high-density plasma etching techniques, while the ''bottom up'' approach draws on the growth of nanowires by chemical vapor deposition. From our simulations for structures with pillar diameters from 2 {micro}m down to 100 nm, the detector efficiency is expected to increase with a decrease in pillar size. Moreover, in the optimized configuration, the detector efficiency could be higher than 75%/cm{sup 2}. Finally, the road map for the relationship between detector diameter and efficiency will be outlined.

Nikolic, R; Cheung, C; Reinhardt, C; Wang, T

2005-07-12

78

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

79

The GMRF detector for hyperspectral imagery: An efficient fully-adaptive maximum likelihood detector  

NASA Astrophysics Data System (ADS)

Hyperspectral sensors collect hundreds of narrow and contiguously spaced spectral bands of data organized in the so called hyperspectral cube. The hyperspectral imagery provides fully registered spatial and high resolution spectral information that is invaluable in discriminating between man-made objects and natural clutter backgrounds, since the objects and clutter have unique spectral signatures that are captured by the data. This comes at a cost. The high volume of data in the hyperspectral cube and the associated processing that is required, has precluded the development of computationally practical Maximum-Likelihood (ML) detectors of man-made anomalies in clutter. This thesis solves this problem. We derive the Gauss- Markov random field (GMRF) detector, a computationally efficient ML anomaly detector that fully adapts to the unknown statistics of the clutter, and fully exploits the spatial and spectral correlation of the hyperspectral imagery. We test extensively our clutter adaptive GMRF detector with real imagery from several hyperspectral sensors. Our results show that the GMRF detector is significantly simpler computationally and noticeably improves the detection performance over the benchmark anomaly detection algorithm. Our approach avoids the costly step of inverting the large sample covariance matrix of the clutter. We parameterize directly the inverse of the clutter covariance and develop several alternative methods to match this inverse to the actual clutter statistics.

Schweizer, Susan Marie

80

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

81

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

82

Development of a stochastic detection efficiency calibration procedure for studying collimation effects on a broad energy germanium detector  

NASA Astrophysics Data System (ADS)

ISPRA, the Italian nuclear safety regulatory body, has started a measurement campaign for validating the performances of in situ gamma-ray spectrometry based on BEGe detectors and ISOCS software. The goal of the validation program is to verify if the mathematical algorithms used by Canberra to account for collimation effects of HpGe detectors continue to work well also for BEGe detectors. This has required the development of a calibration methodology, based on MCNPX code, which, by avoiding any mathematical algorithm utilization, is purely stochastic.Experimental results obtained by such a new procedure, were generally found to be 5% of the reference values. While, in the case of gamma-ray energies greater than 400 keV and small angles collimation, results given by ISOCS software produced larger deviations, around 20%. This work presents a detailed description of the simulation procedure and of the first experimental results.

Altavilla, Massimo; Remetti, Romolo

2013-06-01

83

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

84

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

85

Non-streaming high-efficiency perforated semiconductor neutron detectors, methods of making same and measuring wand and detector modules utilizing same  

DOEpatents

Non-streaming high-efficiency perforated semiconductor neutron detectors, method of making same and measuring wands and detector modules utilizing same are disclosed. The detectors have improved mechanical structure, flattened angular detector responses, and reduced leakage current. A plurality of such detectors can be assembled into imaging arrays, and can be used for neutron radiography, remote neutron sensing, cold neutron imaging, SNM monitoring, and various other applications.

McGregor, Douglas S. (Riley, KS); Shultis, John K. (Manhattan, KS); Rice, Blake B. (Manhattan, KS); McNeil, Walter J. (Winnfield, KS); Solomon, Clell J. (Wichita, KS); Patterson, Eric L. (Manhattan, KS); Bellinger, Steven L. (Manhattan, KS)

2010-12-21

86

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

87

AN EFFICIENT BINARY CORNER DETECTOR P. Saeedi, P. Lawrence and D. Lowe  

E-print Network

AN EFFICIENT BINARY CORNER DETECTOR P. Saeedi, P. Lawrence and D. Lowe Department of Electrical and Computer Engineering, Department of Computer Science University of British Columbia Vancouver, BC, V6T 1Z4

Saeedi, Parvaneh

88

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

89

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

90

Study of the charge collection efficiency of CdZnTe radiation detectors  

NASA Astrophysics Data System (ADS)

The charge collection efficiency of CdZnTe radiation detectors with two different configurations: a Schottky diode detector and a resistive detector are compared. The average charge collection efficiencies for three different directions of irradiation (negative electrode, positive electrode and perpendicular to the electric field) are calculated. The mobility-lifetime product of the CdZnTe substrates is evaluated from the dependence of the measured spectra upon detector bias voltage. The measurement of the average charge collection efficiency is based on monitoring the shift of the peak channel with bias voltage in an experimental setup which is well calibrated. Two types of radiation are used: gamma photons from several radioactive sources and alpha particles from an241Am source. The models for the evaluation of mobility-lifetime product from the measured data for the two types of detector configurations as well as for the two types of radiation sources, are compared and discussed. The CdZnTe (Zn = 10%) substrates under study are obtained commercially and are grown by the high pressure Bridgeman method. The mobility-lifetime products and specific resistivity of the two types of detectors are evaluated and compared. A lower resistivity material has a narrower depletion region and behaves like a thinner detector thus exhibiting better collection efficiencies. Therefore, medium resistivity material which is completely inadequate for resistive detectors can still yield high performance Schottky detectors. The preferred direction of irradiation, i.e. from the negative electrode, is possible only in the case of n-type material which is reverse biased by negative voltages applied to the Schottky gate. The mobility-lifetime products that are derived on both the resistive detector (with specific resistivity of ?1.1010 ?.cm) and the Schottky diode (with specific resistivity of ?1.106 ?.cm) are ?n?n ?-4.10-4 cm2V-1 and ?p?p? 8.10-5 cm2V-1.

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

1996-08-01

91

Development of a high efficiency annular detector system for RIB experiments at NSC  

NASA Astrophysics Data System (ADS)

7Be radioactive ion beam (RIB) has been successfully extracted by the in-flight separation technique (J. Phys. G. Nucl. Part. Phys. 24 (1998) 1371) [1] using the recoil mass spectrometer (RMS) HIRA (Nucl. Instr. and Meth. A 339 (1994) 543) [2] at NSC. Many experiments measuring elastic scattering and transfer reactions using low intensity 7Be beam have been performed. To compensate for low beam intensity, a new, compact geometry, large-area, high-efficiency detector system has been developed. The detector setup consists of two position-sensitive silicon annular strip detectors, a large-area two-dimensional position-sensitive silicon detector and a transmission-type gas ionization detector. The silicon detectors give the energy as well as the position of the implanted particles and the gas ionization chamber gives the differential energy loss for particle identification.

Jhingan, Akhil; Barua, S.; Das, J. J.; Varughese, T.; Sugathan, P.; Madhavan, N.; Nath, S.; Kalita, K.; Verma, S.

2005-02-01

92

Studying the full energy peak efficiency for a two ?-detectors combination of different dimensions  

NASA Astrophysics Data System (ADS)

The present work investigates the validity of extending the efficiency transfer technique (ET) to accommodate detection system composed of more than one detector [two NaI (Tl) detectors]. An arbitrary located radioactive point and volumetric cylindrical sources [152Eu aqueous radioactive sources covering the energy range from 121 keV up to 1408 keV] were used in order to get the full-energy peak efficiency (FEPE) based on the effective solid angle ratio. In addition, self attenuation of source matrix, the attenuation by the source container and the detector housing materials are also treated. Results are compared with those measured by a combination of two NaI(Tl) detectors of different volumes (3?×3? and 2?×2?) with resolution (FWHM) at 662 keV equal to 7.5% and 8.5% respectively. The comparison between the calculated and the measured full-energy peak efficiency values reveal a good agreement.

El-Khatib, Ahmed M.; Krar, Mohamed E.; Badawi, Mohamed S.

2013-08-01

93

Performance of SEM scintillation detector evaluated by modulation transfer function and detective quantum efficiency function.  

PubMed

In the paper, the SEM detector is evaluated by the modulation transfer function (MTF) which expresses the detector's influence on the SEM image contrast. This is a novel approach, since the MTF was used previously to describe only the area imaging detectors, or whole imaging systems. The measurement technique and calculation of the MTF for the SEM detector are presented. In addition, the measurement and calculation of the detective quantum efficiency (DQE) as a function of the spatial frequency for the SEM detector are described. In this technique, the time modulated e-beam is used in order to create well-defined input signal for the detector. The MTF and DQE measurements are demonstrated on the Everhart-Thornley scintillation detector. This detector was alternated using the YAG:Ce, YAP:Ce, and CRY18 single-crystal scintillators. The presented MTF and DQE characteristics show good imaging properties of the detectors with the YAP:Ce or CRY18 scintillator, especially for a specific type of the e-beam scan. The results demonstrate the great benefit of the description of SEM detectors using the MTF and DQE. In addition, point-by-point and continual-sweep e-beam scans in SEM were discussed and their influence on the image quality was revealed using the MTF. PMID:24323770

Bok, Jan; Schauer, Petr

2014-01-01

94

Efficiency of Moderated Neutron Lithium Glass Detectors Using Monte Carlo Techniques  

NASA Astrophysics Data System (ADS)

Due to national security concerns over the smuggling of special nuclear materials and the small supply of He-3 for use in neutron detectors, there is a great need for a new kind of neutron detector. Using Monte Carlo techniques I have been studying the use of lithium glass in varying configurations for neutron detectors. My research has included the effects of using a detector with two thin sheets of lithium at varying distances apart. I have also researched the effects of varying amounts of shielding a californium source with varying amounts of water. This is important since shielding would likely be used to make nuclear material more difficult to detect. The addition of one sheet of lithium-6 glass on the front surface of the detector significantly improves the efficiency for the detection of neutrons from a moderated fission source.

James, Brian

2011-10-01

95

Analyzing the Efficiency of the Forward Radiation Shielding for the CMS Detector at the LHC  

Microsoft Academic Search

The forward radiation shielding of the CMS detector is developed for the LHC by the Institute for High-Energy Physics. The efficiency of this shielding is analyzed on the basis of the results of numerical simulation. The computed particle-flux densities are compared to those of the ideal model of the shielding. The secondary-radiation field near the detector is investigated with different

I. L. Azhgirei; V. V. Talanov

2002-01-01

96

Absolute detector quantum-efficiency measurements using correlated photons  

E-print Network

and Technology (NIST). We use pairs of correlated photons to produce spatial maps of the absolute efficiency of parametric down-conversion, which produces optical photons in pairs within a nonlinear crystal. Within the crystal, photons from a pump laser beam, in effect "decay" into pairs of photons under the restrictions

Migdall, Alan

97

Direct conversion detectors: the effect of incomplete charge collection on detective quantum efficiency.  

PubMed

Direct conversion detectors offer the potential for very high resolution and high quantum efficiency for x-ray imaging, however, variations in signal can arise due to incomplete charge collection. A charge transport model was developed to describe the signal and noise resulting from incomplete charge collection. This signal to noise ratio (SNR) reduction was incorporated into the cascaded systems model for a simple x-ray detector. A new excess noise factor, A(c) (termed the collection noise factor) is introduced to describe the reduction in detective quantum efficiency (DQE). The DQE is proportional to the product of the quantum efficiency and the collection noise factor. If the trapping cross sections for electrons and holes are very different, and if the detector is biased improperly, the collection noise factor can drop to as low as 50%. In addition, the signal loss due to incomplete charge collection will reduce the DQE in the presence of added noise. Because of this, the DQE generally does not continue to improve with greater detector thickness. The collection noise factor and DQE are predicted for CdZnTe, PbI2, and Se. The optimization of detector thickness should be based not only on quantum efficiency but also on the charge collection statistics, which are influenced by bias field and polarity. PMID:12094993

Mainprize, James G; Hunt, Dylan C; Yaffe, Martin J

2002-06-01

98

Monte Carlo simulation of the LENA detector system  

NASA Astrophysics Data System (ADS)

Many nuclear astrophysics experiments use the singles energy spectrum to measure nuclear cross-sections. It has been shown in previous publications that the use of a high purity germanium (HPGe) detector and a NaI(Tl) annulus in coincidence can lower the background, allowing the measurement of smaller cross-sections. In our previous work, our simulation was only capable of determining both full-energy peak relative efficiencies. Here, we present work which extends our simulation so that we can predict absolute efficiencies, and both coincidence gate efficiencies. We first show that the full-energy peak and the total energy singles efficiency of our HPGe detector simulation agrees well with calibration data. We then present the full-energy peak and total energy efficiency for the NaI(Tl) annulus. Results are presented for our coincidence efficiencies, using three examples. These examples are a comparison to the decay of the 151 keV resonance in the 18O(p, ?)19F reaction, a 22Na point-like calibration source, and 26Al nuclei distributed in a meteorite fragment. In each case, we present a comparison of data to the simulation and show that, within our uncertainties, we can accurately simulate our measured intensities.

Howard, C.; Iliadis, C.; Champagne, A. E.

2013-11-01

99

Soft x-ray quantum efficiency of silicon hybrid CMOS detectors  

NASA Astrophysics Data System (ADS)

Si Hybrid CMOS detectors (HCDs) are sensitive to X-rays between approximately 0.2 - 20 keV. HCDs can provide superior performance to traditional CCDs in multiple areas: faster read out time, windowed read out mode, less susceptible to radiation & micrometeoroid damage, and lower power consumption. X-ray detectors designed for use in astronomical observatories must have an optical blocking filter to prevent the detectors from being saturated by optical light. We have previously reported on the successful deposition of an Al optical blocking layer directly onto the surface of HCDs. These blocking filters were deposited with multiple thicknesses from 180 - 1000 Å and successfully block optical light at all thicknesses, with minimal impact expected on quantum efficiency at the energies of interest for these detectors. The thin Al layer is not expected to impact quantum efficiency at the energies of interest for these detectors. We report energy dependent soft X-ray quantum efficiency measurements for multiple HCDs with different optical blocking filter thicknesses.

Prieskorn, Zachary R.; Bongiorno, Stephen D.; Burrows, David N.; Falcone, Abraham D.; Griffith, Christopher V.; Nikoleyczik, Jonathan

2014-07-01

100

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

101

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

102

Coincidence summing corrections for a clover detector  

NASA Astrophysics Data System (ADS)

The true coincidence summing effect on the full energy peak efficiency calibration of a clover HPGe detector for point sources has been determined as a function of sample-to-detector distance using mono-energetic and multi-energetic gamma ray sources. The coincidence summing effect has been observed to increase at closer distances with the correction factors as high as 1.25 at closest distance studied. The correction factors for the total and the photopeak efficiencies have been obtained using the analytical method. The clover detector response has been simulated using MCNP code, taking care of the bevels and the flat surfaces of the clover detector. The geometry of the clover detector has been optimized to match the experimental and the theoretical efficiencies. The true coincidence summing correction factors (kTCS) have also been experimentally obtained by taking the ratio of corresponding mono-energetic extrapolated efficiencies to multi-energetic efficiencies. The kTCS obtained from analytical method has been found to match with the experimental kTCS with the simulated values within 1-5%.

Agarwal, Chhavi; Danu, L. S.; Gathibandhe, M.; Goswami, A.; Biswas, D. C.

2014-11-01

103

Critique of the Rowe 2001 Detector Efficiency Experiment  

E-print Network

The Rowe 2001 experiment scattered photons from two prepared 9Be+ ions. Measurement of the scattered photons used a single photomultiplier tube (PMT). The resultant histograms appear to be a superposition of the individual ions' distribution, but that is not correct. The PMT records the convolution of the joint probability density of the ions. There are many different joint densities which yield the same PMT histograms. Each density has a different correlation. For a fixed PMT histogram the range of those correlations can be large, e.g. -0.730 to +0.997. The reported correlations based on discriminator levels and the categories 'zero bright', 'one bright', and 'two bright' are unsupported. As such the claim that the detection efficiency loophole is closed is invalid. For this experiment, the detection loophole remains open.

Douglas G. Danforth

2014-12-18

104

A study of the validity of the efficiency transfer method to calculate the peak efficiency using ?-ray detectors at extremely large distances  

NASA Astrophysics Data System (ADS)

The full-energy peak efficiency (FEPE) curves of the (2? × 2? and 3? × 3?) NaI (Tl) detectors were measured at seven different axial positions from their surfaces. The calibration process was done using radioactive point sources, which produce a wide energy range from 59.53 up to 1,408.01 keV. This work has been undertaken to explain the effects of source energy and sourcE-to-detector distance on the detector efficiency calculations. The study provides an empirical formula to calculate FEPE based on the efficiency transfer method for different detectors using the effective solid angle ratio at very large distances and for higher energies. A remarkable agreement between the measured and calculated efficiencies for the detectors at the sourcE-to-detector distances <35 cm and above that slight difference was observed.

El-Khatib, Ahmed M.; Badawi, Mohamed S.; Elzaher, Mohamed A.; Thabet, Abouzeid A.

2014-04-01

105

A radially dependent photopeak efficiency model for Si(Li) detectors  

NASA Astrophysics Data System (ADS)

A simple five parameter model for the efficiency of a Si(Li) detector has been developed. It was found necessary to include a radially dependent efficiency even for small detectors. The model is an extension of the pioneering work of Hansen et al. [1] but correction factors include more up to date data and explicit equations for the mass attenuation coefficients over a wide range of photons energies. Four of the five parameters needed are generally supplied by most commercial manufacturers of Si(Li) detectors. 54Mn and 241Am sources have been used to calibrate a Si(Li) to ˜±3% over the energy range 3-60 keV.

Cohen, David Damien

1980-12-01

106

High quantum-efficiency photon-number-resolving detector for photonic on-chip information processing.  

PubMed

The integrated optical circuit is a promising architecture for the realization of complex quantum optical states and information networks. One element that is required for many of these applications is a high-efficiency photon detector capable of photon-number discrimination. We present an integrated photonic system in the telecom band at 1550 nm based on UV-written silica-on-silicon waveguides and modified transition-edge sensors capable of number resolution and over 40 % efficiency. Exploiting the mode transmission failure of these devices, we multiplex three detectors in series to demonstrate a combined 79 % ± 2 % detection efficiency with a single pass, and 88 % ± 3 % at the operating wavelength of an on-chip terminal reflection grating. Furthermore, our optical measurements clearly demonstrate no significant unexplained loss in this system due to scattering or reflections. This waveguide and detector design therefore allows the placement of number-resolving single-photon detectors of predictable efficiency at arbitrary locations within a photonic circuit - a capability that offers great potential for many quantum optical applications. PMID:24104153

Calkins, Brice; Mennea, Paolo L; Lita, Adriana E; Metcalf, Benjamin J; Kolthammer, W Steven; Lamas-Linares, Antia; Spring, Justin B; Humphreys, Peter C; Mirin, Richard P; Gates, James C; Smith, Peter G R; Walmsley, Ian A; Gerrits, Thomas; Nam, Sae Woo

2013-09-23

107

High Speed Travelling Wave Single-Photon Detectors With Near-Unity Quantum Efficiency  

E-print Network

to-date are still realized off-chip. Therefore a scalable and efficient detector architecture are among the most sought-after elements in modern quantum optics and quantum communication. Close is an essential element of cluster state quantum computing and error correction schemes, as well as entanglement

Sergienko, Alexander

108

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

109

Electromechanically cooled germanium radiation detector system 1 Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under Contract W-7405Eng48. 1  

Microsoft Academic Search

We have successfully developed and fielded an electromechanically cooled germanium radiation detector (EMC-HPGe) at Lawrence Livermore National Laboratory (LLNL). This detector system was designed to provide optimum energy resolution, long lifetime, and extremely reliable operation for unattended and portable applications. For most analytical applications, high purity germanium (HPGe) detectors are the standard detectors of choice, providing an unsurpassed combination of

Anthony D Lavietes; G Joseph Mauger; Eric H Anderson

1999-01-01

110

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

111

Absolute detection efficiencies for keV energy atoms incident on a microchannel plate detector  

NASA Astrophysics Data System (ADS)

The absolute detection efficiencies of a microchannel plate detector (MCP) were determined experimentally for neutral hydrogen, carbon, and tungsten atoms with impact energies of 0.5-4.5 keV. We measured detection efficiencies using our recently developed method, which uses coincidence counting between neutralized incident ions and ionized target atoms in single-electron capture collisions. The obtained detection efficiencies showed similar impact-energy and mass dependence to those of rare gas atoms (Ne, Ar, Kr, and Xe), measured previously using our method. The detection efficiencies increased with increasing impact energy and converged to the open area ratio (?50%) of the MCP used. The efficiencies at fixed energies decreased as the mass of the incident atom increased. The absolute detection efficiencies obtained for H, C, W, Ne, Ar, Kr, and Xe atoms could be scaled according to the average electron emission yield estimated using the formulas for electronic and nuclear stopping powers.

Takahashi, N.; Adachi, Y.; Saito, M.; Haruyama, Y.

2013-11-01

112

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

113

Gamma radiation detectors for safeguards applications  

Microsoft Academic Search

The IAEA uses extensively a variety of gamma radiation detectors to verify nuclear material. These detectors are part of standardized spectrometry systems: germanium detectors for High-Resolution Gamma Spectrometry (HRGS); Cadmium Zinc Telluride (CZT) detectors for Room Temperature Gamma Spectrometry (RTGS); and NaI(Tl) detectors for Low Resolution Gamma Spectrometry (LRGS). HRGS with high-purity Germanium (HpGe) detectors cooled by liquid nitrogen is

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

2007-01-01

114

CdTe detector efficiency calibration using thick targets of pure and stable compounds  

NASA Astrophysics Data System (ADS)

Quantitative PIXE measurements require perfectly calibrated set-ups. Cooled CdTe detectors have good efficiency for energies above those covered by Si(Li) detectors and turn on the possibility of studying K X-rays lines instead of L X-rays lines for medium and eventually heavy elements, which is an important advantage in various cases, if only limited resolution systems are available in the low energy range. In this work we present and discuss spectra from a CdTe semiconductor detector covering the energy region from Cu (K ?1 = 8.047 keV) to U (K ?1 = 98.439 keV). Pure thick samples were irradiated with proton beams at the ITN 3.0 MV Tandetron accelerator in the High Resolution High Energy PIXE set-up. Results and the application to the study of a Portuguese Ossa Morena region Dark Stone sample are presented in this work.

Chaves, P. C.; Taborda, A.; Reis, M. A.

2012-02-01

115

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

116

Accurate and efficient modeling of the detector response in small animal multi-head PET systems  

NASA Astrophysics Data System (ADS)

In fully three-dimensional PET imaging, iterative image reconstruction techniques usually outperform analytical algorithms in terms of image quality provided that an appropriate system model is used. In this study we concentrate on the calculation of an accurate system model for the YAP-(S)PET II small animal scanner, with the aim to obtain fully resolution- and contrast-recovered images at low levels of image roughness. For this purpose we calculate the system model by decomposing it into a product of five matrices: (1) a detector response component obtained via Monte Carlo simulations, (2) a geometric component which describes the scanner geometry and which is calculated via a multi-ray method, (3) a detector normalization component derived from the acquisition of a planar source, (4) a photon attenuation component calculated from x-ray computed tomography data, and finally, (5) a positron range component is formally included. This system model factorization allows the optimization of each component in terms of computation time, storage requirements and accuracy. The main contribution of this work is a new, efficient way to calculate the detector response component for rotating, planar detectors, that consists of a GEANT4 based simulation of a subset of lines of flight (LOFs) for a single detector head whereas the missing LOFs are obtained by using intrinsic detector symmetries. Additionally, we introduce and analyze a probability threshold for matrix elements of the detector component to optimize the trade-off between the matrix size in terms of non-zero elements and the resulting quality of the reconstructed images. In order to evaluate our proposed system model we reconstructed various images of objects, acquired according to the NEMA NU 4-2008 standard, and we compared them to the images reconstructed with two other system models: a model that does not include any detector response component and a model that approximates analytically the depth of interaction as detector response component. The comparisons confirm previous research results, showing that the usage of an accurate system model with a realistic detector response leads to reconstructed images with better resolution and contrast recovery at low levels of image roughness.

Cecchetti, Matteo; Moehrs, Sascha; Belcari, Nicola; Del Guerra, Alberto

2013-10-01

117

Accurate and efficient modeling of the detector response in small animal multi-head PET systems.  

PubMed

In fully three-dimensional PET imaging, iterative image reconstruction techniques usually outperform analytical algorithms in terms of image quality provided that an appropriate system model is used. In this study we concentrate on the calculation of an accurate system model for the YAP-(S)PET II small animal scanner, with the aim to obtain fully resolution- and contrast-recovered images at low levels of image roughness. For this purpose we calculate the system model by decomposing it into a product of five matrices: (1) a detector response component obtained via Monte Carlo simulations, (2) a geometric component which describes the scanner geometry and which is calculated via a multi-ray method, (3) a detector normalization component derived from the acquisition of a planar source, (4) a photon attenuation component calculated from x-ray computed tomography data, and finally, (5) a positron range component is formally included. This system model factorization allows the optimization of each component in terms of computation time, storage requirements and accuracy. The main contribution of this work is a new, efficient way to calculate the detector response component for rotating, planar detectors, that consists of a GEANT4 based simulation of a subset of lines of flight (LOFs) for a single detector head whereas the missing LOFs are obtained by using intrinsic detector symmetries. Additionally, we introduce and analyze a probability threshold for matrix elements of the detector component to optimize the trade-off between the matrix size in terms of non-zero elements and the resulting quality of the reconstructed images. In order to evaluate our proposed system model we reconstructed various images of objects, acquired according to the NEMA NU 4-2008 standard, and we compared them to the images reconstructed with two other system models: a model that does not include any detector response component and a model that approximates analytically the depth of interaction as detector response component. The comparisons confirm previous research results, showing that the usage of an accurate system model with a realistic detector response leads to reconstructed images with better resolution and contrast recovery at low levels of image roughness. PMID:24018780

Cecchetti, Matteo; Moehrs, Sascha; Belcari, Nicola; Del Guerra, Alberto

2013-10-01

118

High Efficiency Photon Counting Detectors for the FAUST Spacelab Far Ultraviolet Astronomy Payload  

Microsoft Academic Search

We compare the performance of sealed tube microchannel-plate position sensitive detectors having transmission CsI photocathodes or opaque CsI photocathodes. These devices were developed for the FAUST Spacelab payload to accomplish imaging surveys in the band between 1300?? and 1800??. We demonstrate that photocathode quantum efficiencies in excess of 40% at 1216?? have been achieved with the transmission and the opaque

O. H. W. Siegmund; M. Lampton; J. Bixler; J. Vallerga; S. Bowyer

1987-01-01

119

[Specrozonal X-ray detector and determination of the efficient atomic number of absorbing tissue].  

PubMed

A method is described for determining the efficient atomic number of inclusion-tissue substance, visualized in image, by the characteristic angle estimated by means of spectronazal X-ray detector. Described are study results of the influence of inclusion's geometric dimensions and of the whole radiation filtration exerted on the value of characteristic angles for different substances. The experimental values of effective atomic numbers are shown to fit well, within the range limited by radiation contrast, the theoretical ones. PMID:15568505

Leliukhin, A S; Kornev, E A; Kan'shin, V V

2004-01-01

120

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

121

A biomimetic olfactory-based biosensor with high efficiency immobilization of molecular detectors.  

PubMed

The immobilization efficiency of molecular detectors is of great importance with regard to the performances of biosensors such as the sensitivity, stability, and reproducibility. This paper presents a biomimetic olfactory receptor-based biosensor with better performances by improving the immobilization efficiency of molecular detectors for odorant sensing. A mixed self-assembled monolayers (SAMs) functionalized with specific olfactory receptors (ODR-10) was constructed on the sensitive area of surface acoustic wave (SAW) chip. The immobilization of ODR-10 was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The responses of this biosensor to various odorants were recorded by monitoring the resonance frequency shifts of SAW, which is correlated to the mass loading on its sensitive area. All the results demonstrate this biosensor can specifically respond to the natural ligand of ODR-10, diacetyl, with high sensitivity and stability. The sensitivity is 4 kHz/ng, which is 2× higher than that of previous work. The detection limit is 1.2×10(-11) mM. The major advances on immobilization efficiency of molecular detectors presented in this work could substantially promote and accelerate the researches and applications of olfactory receptor-based biosensors with different transducers, such as quartz crystal microbalance (QCM), surface plasma resonance (SPR), and field effect transistors (FET). PMID:22040748

Wu, Chunsheng; Du, Liping; Wang, Di; Zhao, Luhang; Wang, Ping

2012-01-15

122

Nuclear Resonance Fluorescence of 235U Measured with High-Resolution LaBr3(Ce) Scintillation Detectors  

NASA Astrophysics Data System (ADS)

A nuclear resonance fluorescence (NRF) experiment was performed on a 235U target with quasi-monochromatic ?-rays at the High Intensity ?-ray Source (HI?S) facility using a 1733 keV resonant energy. A LaBr3(Ce) detector array consisting of eight cylindrical detectors, each with a length of 7.62 cm and a diameter of 3.81 cm, was implemented in this measurement. Moreover, a high-purity germanium (HPGe) detector array consisting of four detectors, each of which has a relative efficiency of 60%, was used as the benchmark for the measurement taken using the LaBr3(Ce) detector array. The integrated cross section of the NRF level, measured with LaBr3(Ce) detectors, showed good agreement with the available data.

Omer, Mohamed; Negm, Hani; Zen, Heishun; Daito, Izuru; Kii, Toshiteru; Masuda, Kai; Ohgaki, Hideaki; Hajima, Ryoichi; Shizuma, Toshiyuki; Hayakawa, Takehito; Kikuzawa, Nobuhiro

2013-10-01

123

An efficient depth- and energy-dependent Monte Carlo model for columnar CsI detectors  

NASA Astrophysics Data System (ADS)

We developed an efficient, depth- and energy-dependent Monte Carlo model for columnar CsI detectors. The optical photon, electron/positron Monte Carlo package MANTIS developed by our group, was used to generate optical photon response and collection efficiency as a function of the x-ray/electron interaction depth for a realistic scintillator geometry. The detector geometry we used for the simulations was reported in the past and is based on a 500 ?m thick columnar CsI scintilator. The resulting depth-dependent optical photon responses were fit to a parametrized Gaussian mixture model. The model parameters were the depth-dependent radial shift of the response peak, the depth dependent widths of the Gaussians, and the depth-dependent magnitude of the Gaussians in the mixture. The depth-dependent optical spread has a maximum spatial shift of 53 ?m. The optical collection efficiency at the photo-diode layer followed a power law varying from 90% for interactions at the scintillator exit surface to 20% for interactions at the detector entrance. The responses were consequently incorporated into penMesh, a PENELOPE based Monte Carlo x-ray, electron/positron transport simulation package for generating clinically realistic images of triangular mesh phantoms. The resulting detector responses from this empirical model were compared against the full x-ray/electron/optical photon simulation using the package MANTIS, showing good agreement. The simulation speed, using the optical transport model in penMesh, increases by two orders of magnitude compared to MANTIS.

Kyprianou, Iacovos S.; Brackman, Gabriel; Myers, Kyle J.; Badal, Andreu; Badano, Aldo

2008-03-01

124

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

NASA Astrophysics Data System (ADS)

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.

2014-05-01

125

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

126

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

127

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

128

Proton-induced radiation damage in germanium detectors  

Microsoft Academic Search

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 108 protons cm-2 (proton energy: 1.5 GeV) at different operating temperatures (90 to 120 K) to induce radiation

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

1991-01-01

129

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 ...

Taylor, Frank E.

130

Analysis of the Texas A&M impact lightning detector to determine detection efficiency and site error corrections  

E-print Network

The Texas A&M IMProved Accuracy from Combined Technology (IMPACT) lightning detector has been analyzed for 1997 and 1998-99 to determine detection characteristics. These characteristics include stroke detection efficiency as a function of range...

Leahy, Frank Byron

2012-06-07

131

112-Pixel Arrays of High-Efficiency STJ X-Ray Detectors  

NASA Astrophysics Data System (ADS)

We are developing the next generation of high-resolution high-speed X-ray detectors based on superconducting tunnel junctions (STJs). They consist of 112-pixel arrays of 208 m 208 m Ta-Al--Al-Ta tunnel junctions whose Ta absorber increases the detection efficiency compared to earlier Nb-based STJs. To read out these medium size detector arrays we have also developed a compact and scalable 32-channel preamplifier with an input voltage noise 1 nV/Hz and a dc voltage bias for stable STJ operation between Fiske mode resonances. The pixels have a uniform response across the array, an energy resolution between 7.5 and 9.5 eV FWHM at 525 eV, and can be operated at several 1,000 counts/s per pixel.

Friedrich, S.; Harris, J.; Warburton, W. K.; Carpenter, M. H.; Hall, J. A.; Cantor, R.

2014-08-01

132

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

133

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

134

The trigger system of the Pierre Auger Surface Detector: operation, efficiency and stablility  

SciTech Connect

The trigger system of the Surface Detector (SD) of the Pierre Auger Observatory is described, from the identification of candidate showers (E > 1 EeV) at the level of a single station, among a huge background (mainly single muons), up to the selection of real events and the rejection of random coincidences at a higher central trigger level (including the reconstruction accuracy). Efficiency of a single station trigger is evaluated using real data, and the high performance of event selection hierarchy will be demonstrated.

Allard, D.; Armengaud, E.; Allekotte, I.; Allison, P.; Aublin, J.; Ave, M.; Bauleo, P.; Beatty, J.; Beau, T.; Bertou, Xavier; Billoir, P.; Bonifazi, C.; Chou, A.; Chye,; Dagoret-Campagne, S.; Dorofeev, A.; Ghia, P.L.; Gomez Berisso, M.; Gorgi, A.; Hamilton, J.C.; Harton, J.

2005-08-01

135

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

136

Maximizing the quantum efficiency of microchannel plate detectors - The collection of photoelectrons from the interchannel web using an electric field  

NASA Technical Reports Server (NTRS)

High quantum efficiency and two-dimensional imaging capabilities make the microchannel plate (MCP) a suitable detector for a sky survey instrument. The Extreme Ultraviolet Explorer satellite, to be launched in 1987, will use MCP detectors. A feature which limits MCP efficiency is related to the walls of individual channels. The walls are of finite thickness and thus form an interchannel web. Under normal circumstances, this web does not contribute to the detector's quantum efficiency. Panitz and Foesch (1976) have found that in the case of a bombardment with ions, electrons were ejected from the electrode material coating the web. By applying a small electric field, the electrons were returned to the MCP surface where they were detected. The present investigation is concerned with the enhancement of quantum efficiencies in the case of extreme UV wavelengths. Attention is given to a model and a computer simulation which quantitatively reproduce the experimental results.

Taylor, R. C.; Hettrick, M. C.; Malina, R. F.

1983-01-01

137

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

138

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

139

Efficient waveguide-integrated tunnel junction detectors at 1.6 mum.  

PubMed

Near-infrared detectors based on metal-insulator-metal tunnel junctions integrated with planarized silicon nanowire waveguides are presented, which we believe to be the first of their kind. The junction is coupled to the waveguide via a thin-film metal antenna feeding a plasmonic travelling wave structure that includes the tunnel junction. These devices are inherently broadband; the design presented here operates throughout the 1500-1700 nm region. Careful design of the antenna and travelling wave region substantially eliminates losses due to poor mode matching and RC rolloff, allowing efficient operation. The antennas are made from multilayer stacks of gold and nickel, and the active devices are Ni-NiO-Ni edge junctions. The waveguides are made via shallow trench isolation technology, resulting in a planar oxide surface with the waveguides buried a few nanometres beneath.The antennas are fabricated using directional deposition through a suspended Ge shadow mask, using a single level of electron-beam lithography. The waveguides are patterned with conventional 248-nm optical lithography and reactive-ion etching, then planarized using shallow-trench isolation technology. We also present measurements showing overall quantum efficiencies of 6% (responsivity 0.08 A/W at 1.605 mum), thus demonstrating that the previously very low overall quantum efficiencies reported for antenna-coupled tunnel junction devices are due to poor electromagnetic coupling and poor choices of antenna metal, not to any inherent limitations of the technology. PMID:19550928

Hobbs, Philip C D; Laibowitz, Robert B; Libsch, Frank R; Labianca, Nancy C; Chiniwalla, Punit P

2007-12-10

140

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

141

A high efficiency, low background neutron and gamma detector for cold fusion experiments  

NASA Astrophysics Data System (ADS)

The present apparatus (named by the acrostic "FERMI" also to celebrate the 60 yr of the discovery, by Enrico Fermi and collaborators at Rome University, of the effects of moderation of neutrons) is mainly a moderated neutron detector developed for the search of cold fusion events. It is based on 7 BF 3 and 2 3He proportional counters with detection efficiency for neutrons 40%-8% in the range 1 keV-20 MeV, pulse shape acquisition and good time resolution for neutron bursts; it also allows us to perform a good reconstruction of the average original neutron energy. The neutron background measured in the Gran Sasso INFN underground laboratory is about 0.09 Hz. Gamma rays are revealed mostly by a complementary low background NaI detector with 26% solid angle coverage. The performances are controlled by a full MC simulation, experimentally tested. A high multiplicity (up to ˜ 100) neutrons' event has been detected during background runs. The system is being upgraded by the detection and identification of charged hadrons.

Stella, B.; Celani, F.; Corradi, M.; Ferrarotto, F.; Iucci, N.; Milone, V.; Spallone, A.; Villoresi, G.

1995-02-01

142

High efficiency photon counting detectors for the FAUST Spacelab far ultraviolet astronomy payload  

NASA Technical Reports Server (NTRS)

The performances of sealed tube microchannel-plate position sensitive detectors having transmission CsI photocathodes or opaque CsI photocathodes are compared. These devices were developed for the FAUST Spacelab payload to accomplish imaging surveys in the band between 1300 A and 1800 A. It is demonstrated that photocathode quantum efficiencies in excess of 40 percent at 1216 A have been achieved with the transmission and the opaque CsI photocathodes. The effect of the photoelectron trajectory on the spatial resolution is assessed. Spatial resolution of less than 70 microns FWHM has been obtained and is maintained up to event rates of 50,000/sec. Background rates of 0.55 events sq cm per sec have been achieved and low distortion (less than 1 percent) imaging has been demonstrated.

Siegmund, O. H. W.; Lampton, M.; Bixler, J.; Vallerga, J.; Bowyer, S.

1987-01-01

143

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

144

Diameter Control of HP-Ge Crystal Growth  

NASA Astrophysics Data System (ADS)

Large single crystals of germanium are being grown using the Czochralski technique, in which a precisely cut seed crystal is dipped into the molten germanium and then withdrawn slowly, while maintaining the temperature of the melt just above the freezing point. Typically the seed is rotated while the crystal is being formed. The resulting crystal is typically oriented with a (100) crystal axis parallel to the growth direction. The crystal growth process is conducted in a hydrogen (H2) atmosphere, with the H2 flowing inside a quartz envelope. High purity germanium (HP-Ge) crystals with diameter 3 ˜ 9 cm are grown on weekly basis at university of South Dakota. As Czochralski growth is a dynamic process, the thermal geometry in the furnace undergoes a considerable change during the crystal growth process. A load cell was introduced to control the crystal growth process. Growing crystals with automation system is studied. In order to grow crystal automatically, the relationship between input power and crystal weight or crystal diameter is investigated. We show that HP-Ge crystal growth could be controlled automatically using software with feedback system.

Mei, Hao

2013-03-01

145

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

146

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

147

High efficiency microfluidic beta detector for pharmacokinetic studies in small animals  

NASA Astrophysics Data System (ADS)

New radiotracers are continuously being developed to improve diagnostic efficiency using Single Photon Emission Computed Tomography (SPECT) or Positron Emission Tomography (PET). The characterization of their pharmacokinetics requires blood radioactivity monitoring over time during the scan and is very challenging in small animals because of the low volume of blood available. In this work, a prototype microfluidic blood counter made of a microchannel atop a silicon substrate containing PIN photodiodes is proposed to improve beta detection efficiency in a small volume by eliminating unnecessary interfaces between fluid and detector. A flat rectangular-shaped epoxy channel, 36 ?m×1.26 mm cross section and 31.5 mm in length, was microfabricated over a die containing an array of 2×2 mm 2 PIN photodiodes, leaving only a few micrometers of epoxy floor layer between the fluid and the photodiode sensitive surface. This geometry leads to a quasi 2D source, optimizing geometrical detection efficiency that was estimated at 41% using solid angle calculation. CV- IV measurements were made at each fabrication step to confirm that the microchannel components had no significant effects on the diodes' electrical characteristics. The chip was wire-bonded to a PCB and connected to charge sensitive preamplifier and amplifier modules for pulse shaping. Energy spectra recorded for different isotopes showed continuous beta distribution for PET isotopes and monoenergetic conversion electron peaks for 99mTc. Absolute sensitivity was determined for the most popular PET and SPECT radioisotopes and ranged from 26% to 33% for PET tracers ( 18F, 13N, 11C, 68Ga) and more than 2% for 99mTc. Input functions were successfully simulated with 18F, confirming the setup's suitability for pharmacokinetic modeling of PET and SPECT radiotracers in animal experiments. By using standard materials and procedures, the fabrication process is well suited to on-chip microfluidic functionality, allowing full characterization of new radiotracers.

Convert, Laurence; Girard-Baril, Frédérique; Renaudin, Alan; Grondin, Étienne; Jaouad, Abdelatif; Aimez, Vincent; Charette, Paul; Lecomte, Roger

2011-10-01

148

Performance of a HPGe System for Surface and Container Measurements - 13582  

SciTech Connect

The decommissioning of a nuclear facility or post-accident cleanup is an immense engineering effort requiring an array of specialist tools and techniques. The decommissioning and cleanup activities generate large quantities of low activity waste. For economic disposal, it is desirable to certify the waste as suitable for free release. Every container must be assayed to a sufficient degree of accuracy and sensitivity so that it may be certified to be or not to be suitable for 'free release'. In a previous work, the performance of a highly-automated system for free release of large numbers of containers was presented in which the spectroscopy hardware comprised four ORTEC Interchangeable Detector Module (IDM) mechanically cooled HPGe spectrometers in conjunction with ORTEC ISOPlus waste assay software. It was shown that the system was capable of assaying large containers to free release levels in reasonable measurement times. Not all operations have enough waste to justify an automated system or rapid assay results may be required, perhaps in a remote location. To meet this need, a new mobile system has been developed for the assay of smaller objects (drums, boxes, and surfaces) In-Situ. The system incorporates the latest generation IDM-200 and ISOPlus software and a new variant of the ISOCart hardware. This paper will describe the system and performance. (authors)

Twomey, Timothy R. [ORTEC - AMETEK, 801 South Illinois Avenue, Oak Ridge, TN 37830 (United States)] [ORTEC - AMETEK, 801 South Illinois Avenue, Oak Ridge, TN 37830 (United States); Keyser, Ronald M. [Software and Information Services, 562 Bacon Springs Ln, Clinton, TN 37716 (United States)] [Software and Information Services, 562 Bacon Springs Ln, Clinton, TN 37716 (United States)

2013-07-01

149

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

150

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

2014-10-15

151

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

152

Modelling Detector Responses to Neutrons Using MCNP  

NASA Astrophysics Data System (ADS)

This paper describes a method for modelling the neutron response of common gamma-ray detectors, such as sodium iodide (Nal), bismuth germanate (BGO) and hyperpure germanium (HPGe) devices. This response often constitutes an important source of background in neutron-gamma instruments.

Tickner, J.

153

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

154

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

NASA Astrophysics Data System (ADS)

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 ˜7 × 10-7 A/cm2 at -1 V for device sizes varying from 2 × 2 to 5 × 5 mm2. 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) × 10-5 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 10boron.

Dahal, R.; Huang, K. C.; Clinton, J.; LiCausi, N.; Lu, J.-Q.; Danon, Y.; Bhat, I.

2012-06-01

155

Multiband detectors and application of nanostructured anti-reflection coatings for improved efficiency  

NASA Astrophysics Data System (ADS)

This work describes multiband photon detection techniques based on novel semiconductor device concepts and detector designs with simultaneous detection of different wavelength radiation such as UV and IR. One aim of this investigation is to examine UV and IR detection concepts with a view to resolve some of the issues of existing IR detectors such as high dark current, non uniformity, and low operating temperature and to avoid having additional optical components such as filters in multiband detection. Structures were fabricated to demonstrate the UV and IR detection concepts and determine detector parameters: (i) UV/IR detection based on GaN/AlGaN heterostructures, (ii) Optical characterization of p-type InP thin films were carried out with the idea of developing InP based detectors, (iii) Intervalence band transitions in InGaAsP/InP heterojunction interfacial workfunction internal photoemission (HEIWIP) detectors. Device concepts, detector structures, and experimental results are discussed. In order to reduce reflection, TiO2 and SiO2 nanostructured thin film characterization and application of these as anti-reflection coatings on above mentioned detectors is also discussed.

Jayasinghe, J. A. Ranga Chaminda

156

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

NASA Astrophysics Data System (ADS)

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 segmented ^3He ionization chamber designed for the preliminary spin-rotation in helium experiment and the position sensitive, charged particle collection technology currently being developed at ORNL for low-efficiency beam-transmission monitors for the SNS. Neutron absorption on ^3He produces ^1H and ^3H that pass through a wire grid producing an e^- shower detected in current mode by wire strips mounted on a substrate. For 100% efficiency, regions are created with a series of high-voltage plates, grids, and wire strips each strategically located along the beam axis. Analysis over several regions with alternating wire strip orientation provides a two-dimensional beam profile. We will present our prototype model and test results. S.D. Penn et al., Nucl. Instr. and Meth. 457 332 (2001) C.L. Britton et al., IEEE Trans. Nucl. Sci., 51, 1016 (2004).

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

2006-10-01

157

Quantum efficiencies of imaging detectors with alkali halide photocathodes. I - Microchannel plates with separate and integral CsI photocathodes  

NASA Technical Reports Server (NTRS)

Measurements and comparisons have been made of the quantum efficiencies of microchannel plate (MCP) detectors in the far-UV (below 2000-A) wavelength range using CsI photocathodes (a) deposited on the front surfaces of microchannel plates and (b) deposited on solid substrates as opaque photocathodes with the resulting photoelectrons input to microchannel plates. The efficiences were measured in both pulse-counting and photodiode modes of operation. Typical efficiencies are about 15 percent at 1216 A for a CsI-coated MCP compared with 65 percent for an opaque CsI photocathode MCP detector. Special processing has yielded an efficiency as high as 20 percent for a CsI-coated MCP. This may possibly be further improved by optimization of the tilt angle of the MCP channels relative to the front face of the MCP and incident radiation. However, at present there still remains a factor of at least 3 quantum efficiency advantage in the separate opaque CsI photocathode configuration.

Carruthers, George R.

1987-01-01

158

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

159

Polar-azimuthal angle dependent efficiency of different infrared superconducting nanowire single-photon detector designs  

E-print Network

The illumination-angle-dependent absorptance was determined for three types of superconducting-nanowire singlephoton detector (SNSPD) designs: 1. periodic bare niobium-nitride (NbN) stripes with dimensions of conventional ...

Csete, Maria

160

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

E-print Network

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 {\\mu}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${^o}$C. We integrated two detectors into a practical, 625 MHz clocked quantum key distribution system. Stable, real-time key distribution in presence of 30 dB channel loss was possible, yielding a secret key rate of 350 bps.

Boris Korzh; Nino Walenta; Tommaso Lunghi; Nicolas Gisin; Hugo Zbinden

2014-12-03

161

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

162

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

NASA Astrophysics Data System (ADS)

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.; Walenta, N.; Lunghi, T.; Gisin, N.; Zbinden, H.

2014-02-01

163

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

164

High efficiency plastic scintillator detector with wavelength-shifting fiber readout for the GLAST Large Area Telescope  

NASA Astrophysics Data System (ADS)

This paper describes the design and performance studies of the scintillator tile detectors for the anti-coincidence detector (ACD) of the Large Area Telescope (LAT) on the Gamma ray Large Area Space Telescope (GLAST), scheduled for launch in early 2008. The scintillator tile detectors utilize wavelength-shifting fibers and have dual-photomultiplier-tube readout. The design requires highly efficient and uniform detection of singly charged relativistic particles over the tile area and must meet all requirements for a launch, as well as operation in a space environment. We present here the design of three basic types of tiles used in the ACD, ranging in size from ˜450 to ˜2500 cm2, all ˜1 cm thick, with different shapes, and with photoelectron yield of ˜20 photoelectrons per minimum ionizing particle at normal tile incidence, uniform over the tile area. Some tiles require flexible clear fiber cables up to 1.5 m long to deliver scintillator light to remotely located photomultiplier tubes.

Moiseev, A. A.; Deering, P. L.; Hartman, R. C.; Johnson, T. E.; Nebel, T. R.; Ormes, J. F.; Thompson, D. J.

2007-12-01

165

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

166

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

167

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

168

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

169

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

170

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

Microsoft Academic Search

Real-time digital pulse shaping techniques allow synthesis of pulse shapes that have been difficult to realize using the traditional analog methods. Using real-time digital shapers, triangular\\/trapezoidal filters can be synthesized in real time. These filters exhibit digital control on the rise time, fall time, and flat-top of the trapezoidal shape. Thus, the trapezoidal shape can be adjusted for optimum performance

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

2011-01-01

171

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

NASA Astrophysics Data System (ADS)

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 T1/2 limits were obtained for double beta processes in 96Ru and 104Ru. Several isotopes, which potentially decay through different 2? channels, including also possible resonant double electron captures, were investigated for the first time (156Dy, 158Dy, 184Os, 192Os, 190Pt, 198Pt). Search for resonant absorption of solar 7Li axions in a LiF crystal gave the best limit for the mass of 7Li axions (< 8.6 keV). Rare alpha decay of 190Pt to the first excited level of 186Os(Eexc = 137.2keV) was observed for the first time.

Belli, P.; Bernabei, R.; Cappella, F.; Cerulli, R.; Danevich, F. A.; d'Angelo, A.; d'Angelo, S.; Di Marco, A.; Di Vacri, M. L.; Incicchitti, A.; Kobychev, V. V.; Kovtun, G. P.; Kovtun, N. G.; Laubenstein, M.; Nisi, S.; Poda, D. V.; Polischuk, O. G.; Shcherban, A. P.; Solopikhin, D. A.; Suhonen, J.; Tolmachev, A. V.; Tretyak, V. I.; Yavetskiy, R. P.

2013-12-01

172

Calibration Analyses and Efficiency Studies for the Anti Coincidence Detector on the Fermi Gamma Ray Space Telescope  

SciTech Connect

The Anti Coincidence Detector (ACD) on the Fermi Gamma Ray Space Telescope provides charged particle rejection for the Large Area Telescope (LAT). We use two calibrations used by the ACD to conduct three studies on the performance of the ACD. We examine the trending of the calibrations to search for damage and find a timescale over which the calibrations can be considered reliable. We also calculated the number of photoelectrons counted by a PMT on the ACD from a normal proton. Third, we calculated the veto efficiencies of the ACD for two different veto settings. The trends of the calibrations exhibited no signs of damage, and indicated timescales of reliability for the calibrations of one to two years. The number of photoelectrons calculated ranged from 5 to 25. Large errors in the effect of the energy spectrum of the charged particles caused these values to have very large errors of around 60 percent. Finally, the veto efficiencies were found to be very high at both veto values, both for charged particles and for the lower energy backsplash spectrum. The Anti Coincidence Detector (ACD) on the Fermi Gamma Ray Space Telescope is a detector system built around the silicon strip tracker on the Large Area Telescope (LAT). The purpose of the ACD is to provide charged particle rejection for the LAT. To do this, the ACD must be calibrated correctly in flight, and must be able to efficiently veto charged particle events while minimizing false vetoes due to 'backsplash' from photons in the calorimeter. There are eleven calibrations used by the ACD. In this paper, we discuss the use of two of these calibrations to preform three studies on the performance of the ACD. The first study examines trending of the calibrations to check for possible hardware degradation. The second study uses the calibrations to explore the efficiency of an on-board hardware veto. The third study uses the calibrations to calculate the number of photoelectrons seen by each PMT when a minimum ionizing particle is detected, which is a useful value for performing simulations.

Kachulis, Chris; /Yale U. /SLAC

2011-06-22

173

The neutron detection efficiency of NE213 detectors measured by means of a 252Cf source  

Microsoft Academic Search

The neutron detection efficiency of a NE213 scintillator was determined by comparing the measured neutron time-of-flight spectrum of a 252Cf source with its reference neutron energy distribution. Below En = 8 MeV an accuracy of better than 3% could be achieved. The measured efficiency agreed reasonably well in shape with a Monte Carlo simulation in the entire energy range 0.8

J. Cub; E. Finckh; K. Gebhardt; K. Geissdörfer; R. Lin; J. Strate; H. Klein

1989-01-01

174

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

175

Digital Timing Algorithm for High Purity Germanium Detectors  

NASA Astrophysics Data System (ADS)

The next generation of ?-ray detector arrays will be composed of large volume high purity germanium (HPGE) detectors that are electronically segmented. These detectors will be able to track ?-rays as they Compton scatter within the crystal and between adjacent crystals, eliminating the need for Compton suppression detectors and improving angular resolution. The new arrays will have much higher sensitivity, but require a shift from analog signal processing (ASP) to digital signal processing (DSP). The scope of the current project is to test the resolution of digital timing algorithms, a critical component of any ?-ray tracking system. A ?-? coincidence experiment was performed with a 60Co source and two small volume HPGE detectors using the Digital Data Acquisition System at the National Superconducting Cyclotron Laboratory. The resultant digitized waveforms were analyzed using multiple algorithms. These included digital models of ASP leading edge and constant fraction discriminators, and simple novel digital techniques..

Andrew, Knox; Starosta, Krzysztof; Miller, David; Vaman, Constantin; Voss, Phillip; Weisshaar, Dirk

2007-10-01

176

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

177

Proton-induced radiation damage in germanium detectors  

SciTech Connect

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{sub 8} protons cm{sup {minus}2} (proton energy: 1.5 GeV) at different operating temperatures (90 to 120 K) to induce radiation damage. Basic scientific as well as 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 T {le} 110{degrees}C while staying specially designed cryostats. This paper shows that n-type HPGe detectors can be used in charged particles 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.

Bruckner, J.; Korfer, M.; Wanke, H. (Max-Planck-Institut fuer Chemie (Otto-Hahn-Institut), Mainz (Germany)); Schroeder, A.N.F. (Univ. zu Koln, D-5000 Koln 41 (DE)); Figes, D.; Dragovitsch, P. (Inst. fur Kernphysik, KFA Julich, D-5170 Julich (DE)); Englert, P.A.J. (San Jose State Univ., CA (United States)); Starr, R.; Trombka, J.I. (National Aeronautics and Space Administration, Greenbelt, MD (United States). Goddard Space Flight Center); Taylor, I. (Princeton Gamma-Tech, Princeton, NJ (US)); Drake, D.M.; Shunk, E.R. (Los Alamos National Lab., NM (United States))

1991-04-01

178

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

179

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

180

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

181

An efficient Novelty Detector for online fault diagnosis based on Least Squares Support Vector Machines  

Microsoft Academic Search

A paradigm shift in the standard operating procedures (SOP) is underway in the reliability and health management industry. As the community transitions from traditional preventive maintenance procedures to modern predictive or health-based management systems, areas such as efficient online monitoring and diagnosis schemes based on real-time observations have emerged as key research subjects for engineers. Most diagnostic systems require data

Taimoor S. Khawaja; George Georgoulas; George Vachtsevanos

2008-01-01

182

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

183

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

NASA Astrophysics Data System (ADS)

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.; Eftekharian, A.; Hamed Majedi, A.

2014-02-01

184

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

185

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

186

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

187

Measurement of the efficiency of the pattern recognition of tracks generated by ionizing radiation in a TIMEPIX detector  

NASA Astrophysics Data System (ADS)

A hybrid silicon pixelated TIMEPIX detector (256 × 256 square pixels with a pitch of 55 ?m) operated in Time Over Threshold (TOT) mode was exposed to radioactive sources and protons after Rutherford Backscattering on a thin gold foil of protons beams delivered by the Tandem Accelerator of the Montreal University. Simultaneous exposure of TIMEPIX to radioactive sources and to protons beams on top of the radioactive sources allowed measurements with different mixed radiation fields of protons, alpha-particles, photons and electrons. All measurements were performed in vacuum. The comparison of the experimental activities (determined from the measurement of the number of tracks left in the device by incoming particles) of the radioactive sources with their expected activities allowed the test of the device efficiency for track recognition. The efficiency of track recognition of incident protons of different energies as a function of the incidence angle was measured. The cluster size left by protons in the device was measured as a function of their incident energy at normal and large (75°) incident angles. The operation of TIMEPIX in TOT mode has allowed a 3D mapping of the charge spreading effect in the whole volume of the silicon sensor. The results of the present measurements demonstrate the TIMEPIX capability of differentiating between different types of particles species from mixed radiation fields and measuring their energy deposition. Single track analysis gives a good precision (significantly better than the 55 ?m size of one detector pixel) on the coordinates of the impact point of protons with normal incidence interacting in the TIMEPIX silicon layer.

Asbah, N.; Leroy, C.; Pospisil, S.; Soueid, P.

2014-05-01

188

A hybrid method for coupled neutron ion transport calculations for 10B and 6LiF coated and perforated detector efficiencies  

NASA Astrophysics Data System (ADS)

A hybrid method for neutron-ion transport has been developed and applied to modeling coated and perforated neutron semiconductor detectors. The method couples the MCNP transport code developed by Los Alamos National Laboratory and a specialized ion transport code. Output from MCNP is passed to the ion transport code to perform ion energy deposition calculations, and in this manner the two codes are married. The process is controlled by a PERL script. Angle dependent efficiency calculation results for perforated rod detectors are presented, and neutron absorption efficiencies are presented for channel and chevron type perforations to show how problems with rod perforations may be overcome.

Solomon, C. J.; Shultis, J. K.; McNeil, W. J.; Unruh, T. C.; Rice, B. B.; McGregor, D. S.

2007-09-01

189

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

190

Efficient entanglement purification for Greenberger-Horne-Zeilinger states via the distributed parity-check detector  

NASA Astrophysics Data System (ADS)

A scheme is proposed to implement multipartite entanglement purification of quantum systems in a Greenberger-Horne-Zeilinger (GHZ) state by using the distributed parity-check detector and quantum non-demolition (QND) photon-number-resolving measurement based on the weak cross-Kerr nonlinearities. The prominent feature of the scheme does not need either ancillary entangled photon pairs or the iterative purification procedure. Hence this represents a huge saving in the physical resources to implement entanglement purification. For the purification protocol to improve the fidelity of the output state, it is not essential that the fidelity of the resource states shared is more than 1/4. In addition, the total success probability and fidelity of the present purification scheme can approach unit in principle. The present scheme uses only basic tools in quantum optical laboratories and can be implemented in the regime of the weak cross-Kerr nonlinearity. Therefore, this makes us more confident in the feasibility of the proposed scheme.

Zhu, Meng-Zheng; Ye, Liu

2015-01-01

191

Characterization of detection efficiency as function of energy for soft x-ray detectors.  

PubMed

A new technique has been especially developed for determining the detection efficiency of the silicon surface barrier diodes used for tomography reconstructions at Tore Supra, as function of the energy of the x-ray photons, in the range of 4-25 keV. The response of these diodes has been studied for different bias voltages (0-120 V), with a portable x-ray electronic tube and a cooled Si-p-i-n diode, working in photon counting mode, for the absolute calibration. PMID:19044484

Pacella, D; Mazon, D; Romano, A; Malard, P; Pizzicaroli, G

2008-10-01

192

Characterization of detection efficiency as function of energy for soft x-ray detectors  

SciTech Connect

A new technique has been especially developed for determining the detection efficiency of the silicon surface barrier diodes used for tomography reconstructions at Tore Supra, as function of the energy of the x-ray photons, in the range of 4-25 keV. The response of these diodes has been studied for different bias voltages (0-120 V), with a portable x-ray electronic tube and a cooled Si-p-i-n diode, working in photon counting mode, for the absolute calibration.

Pacella, D.; Romano, A.; Pizzicaroli, G. [Associazione Euratom-ENEA sulla Fusione, Centro Ricerche Frascati, Via E. Fermi, 45-00044 Frascati, Rome (Italy); Mazon, D.; Malard, P. [Euratom-CEA Association, DSM-DRFC, Cadarache 13108, St. Paul lez Durance (France)

2008-10-15

193

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

NASA Astrophysics Data System (ADS)

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 absorbed by the sample during laser exposure. Before and after exposure to 10.6 µm laser radiation, optical and electron microscopy as well as Raman spectroscopy were employed to evaluate the coating topology and composition. These early measurement results demonstrate that a MWCNT coating has a damage threshold of approximately 1686 W/cm2, which is four times as large as that measured for SWCNTs and fifteen times greater than that of carbon based paint.

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

2007-01-01

194

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

NASA Astrophysics Data System (ADS)

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

Marchal, J.

2010-01-01

195

Gamma radiation detectors for safeguards applications  

NASA Astrophysics Data System (ADS)

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

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

2007-08-01

196

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

197

Resolution and efficiency of silicon drift detectors (SDD) compared with other solid state X-ray systems 1  

Microsoft Academic Search

Silicon Drift Detector (SDD) belongs to a new kind of solid state X-ray detectors which are small and easy to use and particularly well suited for X-ray spectroscopy. In this work we have compared their characteristics with that of three other types of solid state detectors suited for detecting X-ray in the 3-50 keV region. We have analyzed the energy

H. P. Garnir; G. Weber; D. Strivay

198

KMESS: An open source software package using a semi-empirical mesh-grid method for the modeling of germanium detector efficiencies  

NASA Astrophysics Data System (ADS)

Traditional approaches in gamma-ray spectroscopy for determining the absolute full-energy peak efficiencies of germanium detectors are primarily either too time consuming or not economically viable. In addition, these approaches are difficult to use for arbitrary source shapes and counting geometries. An open source software package, KMESS (Kevin's Mesh Efficiency Simulator Software), was developed to address these problems. KMESS uses a new semi-empirical mesh-grid method to predict the absolute full-energy peak efficiencies of n- and p-type germanium detectors in both coaxial and closed-ended configurations. The model assumes that any gamma-ray source shape can be treated as a collection of point sources. The code was written in a modular form, making it easy to adapt for other detector configurations and materials. A suite of web-based graphical front-end tools was also developed to make the execution of KMESS user-friendly. KMESS can predict most full-energy peak efficiencies to within 10% accuracy for the energy range 100--1800 keV in less than 10 minutes.

Jackman, Kevin Richard

199

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

200

High detection efficiency micro-structured solid-state neutron detector with extremely low leakage current fabricated with continuous p-n junction  

SciTech Connect

We report the continuous p-n junction formation in honeycomb structured Si diode by in situ boron deposition and diffusion process using low pressure chemical vapor deposition for solid-state thermal neutron detection applications. Optimized diffusion temperature of 800 Degree-Sign C was obtained by current density-voltage characteristics for fabricated p{sup +}-n diodes. A very low leakage current density of {approx}2 Multiplication-Sign 10{sup -8} A/cm{sup 2} at -1 V was measured for enriched boron filled honeycomb structured neutron detector with a continuous p{sup +}-n junction. The neutron detection efficiency for a Maxwellian spectrum incident on the face of the detector was measured under zero bias voltage to be {approx}26%. These results are very encouraging for fabrication of large area solid-state neutron detector that could be a viable alternative to {sup 3}He tube based technology.

Huang, Kuan-Chih; Lu, James J.-Q.; Bhat, Ishwara B. [Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3522 (United States)] [Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3522 (United States); Dahal, Rajendra [Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3522 (United States) [Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3522 (United States); Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3522 (United States); Danon, Yaron [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3522 (United States)] [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3522 (United States)

2013-04-15

201

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

202

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

203

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

204

New approach to study the response of portable gamma detector for in-situ measurement of terrestrial gamma ray field  

E-print Network

A new approach to study the response of portable gamma detector to terrestrial gamma ray is proposed. This approach is based on two-stage Monte Carlo simulation. First, the probability distributions of the phase space coordinates of the events that are most likely to be detected are reconstructed at the phase space shell level. The phase space shell is a closed surface enclosing the detector. The detector response to events originating from the phase space shell is then studied. The full absorption spectra as well as the partial absorption spectra are obtained for natural radionuclides uniformly distributed in the ground. For validation, this method is applied to a HpGe portable detector previously studied. The previous study is based on a semi-empirical model. Good agreement is achieved when we compare the full energy peak efficiencies and the total in-situ spectra obtained by the two methods. As an application, the effective depth of the activity of the 137Cs artificial radionuclide in the soil is determine...

Askri, Boubaker

2014-01-01

205

Neutrino Detectors: Challenges and Opportunities  

SciTech Connect

This paper covers possible detector options suitable at future neutrino facilities, such as Neutrino Factories, Super Beams and Beta Beams. The Magnetised Iron Neutrino Detector (MIND), which is the baseline detector at a Neutrino Factory, will be described and a new analysis which improves the efficiency of this detector at low energies will be shown. Other detectors covered include the Totally Active Scintillating Detectors (TASD), particularly relevant for a low energy Neutrino Factory, emulsion detectors for tau detection, liquid argon detectors and megaton scale water Cherenkov detectors. Finally the requirements of near detectors for long-baseline neutrino experiments will be demonstrated.

Soler, F. J. P. [School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom)

2011-10-06

206

BARGEIN: a simple detector to test evidence for dark matter  

NASA Astrophysics Data System (ADS)

We propose to install a Box ARrangement of GErmanium detectors In liquid Nitrogen (BARGEIN) applying the new detector concept of operating high-purity germanium (HP-Ge) detectors directly in liquid nitrogen as it was developed for the GENIUS project. This setup will improve the sensitivity towards weakly interacting massive particles (WIMPs) dark matter detection by an order of magnitude compared to the Heidelberg-Moscow experiment. The evidence contour claimed by the DAMA collaboration would be fully tested on a short time scale.

Majorovits, B.; Baudis, L.; Heusser, G.; Strecker, H.; Klapdor-Kleingrothaus, H. V.

2000-12-01

207

DETECTORS AND EXPERIMENTAL METHODS: Measurement of the response function and the detection efficiency of an organic liquid scintillator for neutrons between 1 and 30 MeV  

NASA Astrophysics Data System (ADS)

The light output function of a varphi50.8 mm × 50.8 mm BC501A scintillation detector was measured in the neutron energy region of 1 to 30 MeV by fitting the pulse height (PH) spectra for neutrons with the simulations from the NRESP code at the edge range. Using the new light output function, the neutron detection efficiency was determined with two Monte-Carlo codes, NEFF and SCINFUL. The calculated efficiency was corrected by comparing the simulated PH spectra with the measured ones. The determined efficiency was verified at the near threshold region and normalized with a Proton-Recoil-Telescope (PRT) at the 8-14 MeV energy region.

Huang, Han-Xiong; Ruan, Xi-Chao; Chen, Guo-Chang; Zhou, Zu-Ying; Li, Xia; Bao, Jie; Nie, Yang-Bo; Zhong, Qi-Ping

2009-08-01

208

Gamma-ray detection efficiency of the microchannel plate installed as an ion detector in the low energy particle instrument onboard the GEOTAIL satellite  

SciTech Connect

A microchannel plate (MCP) assembly has been used as an ion detector in the low energy particle (LEP) instrument onboard the magnetospheric satellite GEOTAIL. Recently the MCP assembly has detected gamma rays emitted from an astronomical object and has been shown to provide unique information of gamma rays if they are intense enough. However, the detection efficiency for gamma rays was not measured before launch, and therefore we could not analyze the LEP data quantitatively. In this article, we report the gamma-ray detection efficiency of the MCP assembly. The measured efficiencies are 1.29%{+-}0.71% and 0.21%{+-}0.14% for normal incidence 60 and 662 keV gamma rays, respectively. The incident angle dependence is also presented. Our calibration is crucial to study high energy astrophysical phenomena by using the LEP.

Tanaka, Y. T.; Yoshikawa, I.; Yoshioka, K.; Terasawa, T.; Saito, Y.; Mukai, T. [Department of Earth and Planetary Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan)

2007-03-15

209

Enhanced detection efficiency of direct conversion X-ray detector using polyimide as hole-blocking layer.  

PubMed

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 cm(2)/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

210

Setup of cryogenic front-end electronic systems for germanium detectors read-out  

Microsoft Academic Search

Front-end electronic devices for the read-out of ionizing radiation detectors must operate in many cases at cryogenic temperatures. In this work we focus in particular on front-end read-out systems for high-purity germanium (HPGe) detectors, which are usually operated at liquid nitrogen (LN) temperature. We analyze the strong effects that the changed characteristics of the electronic active and passive devices have

F. Zocca; A. Pullia; S. Riboldi; A. D'Andragora; C. Cattadori

2009-01-01

211

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

212

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

PubMed

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?×?10(6) 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. PMID:24784597

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

213

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

SciTech Connect

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?×?10{sup 6} cm{sup ?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., E-mail: mrosenbe@mit.edu; 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. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Glebov, V. Yu.; Stoeckl, C.; Hohenberger, M.; Sangster, T. C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)] [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); LePape, S.; Mackinnon, A. J.; Bionta, R. M.; Landen, O. L. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

2014-04-15

214

Mathematical efficiency calibration with uncertain source geometries using smart optimization  

SciTech Connect

The In Situ Object Counting Software (ISOCS), a mathematical method developed by CANBERRA, is a well established technique for computing High Purity Germanium (HPGe) detector efficiencies for a wide variety of source shapes and sizes. In the ISOCS method, the user needs to input the geometry related parameters such as: the source dimensions, matrix composition and density, along with the source-to-detector distance. In many applications, the source dimensions, the matrix material and density may not be well known. Under such circumstances, the efficiencies may not be very accurate since the modeled source geometry may not be very representative of the measured geometry. CANBERRA developed an efficiency optimization software known as 'Advanced ISOCS' that varies the not well known parameters within user specified intervals and determines the optimal efficiency shape and magnitude based on available benchmarks in the measured spectra. The benchmarks could be results from isotopic codes such as MGAU, MGA, IGA, or FRAM, activities from multi-line nuclides, and multiple counts of the same item taken in different geometries (from the side, bottom, top etc). The efficiency optimization is carried out using either a random search based on standard probability distributions, or using numerical techniques that carry out a more directed (referred to as 'smart' in this paper) search. Measurements were carried out using representative source geometries and radionuclide distributions. The radionuclide activities were determined using the optimum efficiency and compared against the true activities. The 'Advanced ISOCS' method has many applications among which are: Safeguards, Decommissioning and Decontamination, Non-Destructive Assay systems and Nuclear reactor outages maintenance. (authors)

Menaa, N. [AREVA/CANBERRA Nuclear Measurements Business Unit, Saint Quentin-en-Yvelines 78182 (France); Bosko, A.; Bronson, F.; Venkataraman, R.; Russ, W. R.; Mueller, W. [AREVA/CANBERRA Nuclear Measurements Business Unit, Meriden, CT (United States); Nizhnik, V. [International Atomic Energy Agency, Vienna (Austria); Mirolo, L. [AREVA/CANBERRA Nuclear Measurements Business Unit, Saint Quentin-en-Yvelines 78182 (France)

2011-07-01

215

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 (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

216

Ultraviolet detectors Photon detectors  

E-print Network

of aluminum gallium nitride (AlxGa1-xN)-based thin films varies as a function of x, with x ranging from 0 to 1Ultraviolet detectors Photon detectors Photoelectric Semiconductor Photoconductive Schottky barrier

217

Segmented crystalline scintillators: Empirical and theoretical investigation of a high quantum efficiency EPID based on an initial engineering prototype CsI(Tl) detector  

SciTech Connect

Modern-day radiotherapy relies on highly sophisticated forms of image guidance in order to implement increasingly conformal treatment plans and achieve precise dose delivery. One of the most important goals of such image guidance is to delineate the clinical target volume from surrounding normal tissue during patient setup and dose delivery, thereby avoiding dependence on surrogates such as bony landmarks. In order to achieve this goal, it is necessary to integrate highly efficient imaging technology, capable of resolving soft-tissue contrast at very low doses, within the treatment setup. In this paper we report on the development of one such modality, which comprises a nonoptimized, prototype electronic portal imaging device (EPID) based on a 40 mm thick, segmented crystalline CsI(Tl) detector incorporated into an indirect-detection active matrix flat panel imager (AMFPI). The segmented detector consists of a matrix of 160x160 optically isolated, crystalline CsI(Tl) elements spaced at 1016 {mu}m pitch. The detector was coupled to an indirect detection-based active matrix array having a pixel pitch of 508 {mu}m, with each detector element registered to 2x2 array pixels. The performance of the prototype imager was evaluated under very low-dose radiotherapy conditions and compared to that of a conventional megavoltage AMFPI based on a Lanex Fast-B phosphor screen. Detailed quantitative measurements were performed in order to determine the x-ray sensitivity, modulation transfer function, noise power spectrum, and detective quantum efficiency (DQE). In addition, images of a contrast-detail phantom and an anthropomorphic head phantom were also acquired. The prototype imager exhibited approximately 22 times higher zero-frequency DQE ({approx}22%) compared to that of the conventional AMFPI ({approx}1%). The measured zero-frequency DQE was found to be lower than theoretical upper limits ({approx}27%) calculated from Monte Carlo simulations, which were based solely on the x-ray energy absorbed in the detector--indicating the presence of optical Swank noise. Moreover, due to the nonoptimized nature of this prototype, the spatial resolution was observed to be significantly lower than theoretical expectations. Nevertheless, due to its high quantum efficiency ({approx}55%), the prototype imager exhibited significantly higher DQE than that of the conventional AMFPI across all spatial frequencies. In addition, the frequency-dependent DQE was observed to be relatively invariant with respect to the amount of incident radiation, indicating x-ray quantum limited behavior. Images of the contrast-detail phantom and the head phantom obtained using the prototype system exhibit good visualization of relatively large, low-contrast features, and appear significantly less noisy compared to similar images from a conventional AMFPI. Finally, Monte Carlo-based theoretical calculations indicate that, with proper optimization, further, significant improvements in the DQE performance of such imagers could be achieved. It is strongly anticipated that the realization of optimized versions of such very high-DQE EPIDs would enable megavoltage projection imaging at very low doses, and tomographic imaging from a 'beam's eye view' at clinically acceptable doses.

Sawant, Amit; Antonuk, Larry E.; El-Mohri, Youcef; Zhao Qihua; Wang Yi; Li Yixin; Du Hong; Perna, Louis [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48103 (United States); Saint Gobain Crystals, Newbury, Ohio 44065 (United States)

2006-04-15

218

Development of high quantum efficiency, flat panel, thick detectors for megavoltage x-ray imaging: a novel direct-conversion design and its feasibility.  

PubMed

Most electronic portal imaging devices (EPIDs) developed to date, including recently developed flat panel systems, have low x-ray absorption, i.e., low quantum efficiency (QE) of 2%-4% as compared to the theoretical limit of 100%. A significant increase of QE is desirable for applications such as a megavoltage cone-beam computed tomography (MVCT) and megavoltage fluoroscopy. However, the spatial resolution of an imaging system usually decreases significantly with an increase of QE. The key to the success in the design of a high QE detector is therefore to maintain the spatial resolution. Recently, we demonstrated theoretically that it is possible to design a portal imaging detector with both high QE and high resolution [see Pang and Rowlands, Med. Phys. 29, 2274 (2002)]. In this paper, we introduce such a novel design consisting of a large number of microstructured plates (made by, e.g., photolithographic patterning of evaporated or electroplated layers) packed together and aligned with the incident x rays. On each plate, microstrip charge collectors are focused toward the x-ray source to collect charges generated in the ionization medium (e.g., air or gas) surrounded by high-density materials that act as x-ray converters. The collected charges represent the x-ray image and can be read out by various means, including a two-dimensional (2-D) active readout matrix. The QE, spatial resolution, and sensitivity of the detector have been calculated. It has been shown that the new design will have a QE of more than an order of magnitude higher and a spatial resolution equivalent to that of flat panel systems currently used for portal imaging. The new design is also quantum noise limited down to very low doses (approximately 1-2 radiation pulses of the linear accelerator). PMID:15587653

Pang, G; Rowlands, J A

2004-11-01

219

An efficient approach for the removal of impulse noise from the corrupted image using neural network based impulse detector  

Microsoft Academic Search

A new efficient approach to detect the impulse noise from the corrupted image using feed forward neural network (FFNN) is presented. A modified version of the arithmetic mean filter is proposed to remove the detected impulse noise. The performance of proposed noise detection approach is analyzed using the performance measures such as False Alarm Ratio (FAR), Missed Noise (MN) pixels

G. Kaliraj; S. Baskar

2010-01-01

220

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

221

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

222

Preliminary uranium enrichment analysis results using cadmium zinc telluride detectors  

NASA Astrophysics Data System (ADS)

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

Lavietes, Anthony D.; McQuaid, James H.; Paulus, T. J.

1996-10-01

223

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

224

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

225

The effects of Doppler broadening and detector resolution on the performance of three-stage Compton cameras  

PubMed Central

Purpose: The authors investigated how the characteristics of the detectors used in a three-stage Compton camera (CC) affect the CC's ability to accurately measure the emission distribution and energy spectrum of prompt gammas (PG) emitted by nuclear de-excitations during proton therapy. The detector characteristics they studied included the material (high-purity germanium [HPGe] and cadmium zinc telluride [CZT]), Doppler broadening (DB), and resolution (lateral, depth, and energy). Methods: The authors simulated three-stage HPGe and CZT CCs of various configurations, detecting gammas from point sources with energies ranging from 0.511 to 7.12 MeV. They also simulated a proton pencil beam irradiating a tissue target to study how the detector characteristics affect the PG data measured by CCs in a clinical proton therapy setting. They used three figures of merit: the distance of closest approach (DCA) and the point of closest approach (PCA) between the measured and actual position of the PG emission origin, and the calculated energy resolution. Results: For CCs with HPGe detectors, DB caused the DCA to be greater than 3 mm for 14% of the 6.13 MeV gammas and 20% of the 0.511 MeV gammas. For CCs with CZT detectors, DB caused the DCA to be greater than 3 mm for 18% of the 6.13 MeV gammas and 25% of the 0.511 MeV gammas. The full width at half maximum (FWHM) of the PCA in the \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}\\hat z\\end{equation*} \\end{document}z^ direction for HPGe and CZT detectors ranged from 1.3 to 0.4 mm for gammas with incident energy ranging from 0.511 to 7.12 MeV. For CCs composed of HPGe detectors, the resolution of incident gamma energy calculated by the CC ranged from 6% to 1% for gammas with true incident energies from 0.511 to 7.12 MeV. For CCs composed of CZT detectors, the resolution of gamma energy calculated by the CC ranged from 10% to 1% for gammas with true incident energies from 0.511 to 7.12 MeV. For HPGe and CZT CCs in which all detector effect were included, the DCA was less than 3 mm for 75% and 68% of the detected gammas, respectively, and restricting gammas to those having energy greater than 2.0 MeV increased these percentages to 83% and 77% for HPGe and CZT, respectively. Distributions of the true gamma origins and the PCA after detector characteristics had been included showed good agreement on beam range and some loss of resolution for the lateral profile of the PG emission. Characteristic energy lines were evident in the calculated gamma energy spectrum. Conclusions: The authors found the following: (1) DB is the dominant source of spatial and energy resolution loss in the CCs at all energy levels; (2) the largest difference in the spatial resolution of HPGe and CZT CCs is that the spatial resolution distributions of CZT have broader tails. The differences in the FWHM of these distributions are small; (3) the energy resolution of both HPGe and CZT three-stage CCs is adequate for PG spectroscopy; and (4) restricting the gammas to those having energy greater than 2.0 MeV can improve the achievable image resolution. PMID:23298111

Mackin, Dennis; Polf, Jerimy; Peterson, Steve; Beddar, Sam

2013-01-01

226

New electronically black neutron detectors  

SciTech Connect

Two neutron detectors are described that can function in a continuous radiation background. Both detectors identify neutrons by recording a proton recoil pulse followed by a characteristic capture pulse. This peculiar signature indicates that the neutron has lost all its energy in the scintillator. Resolutions and efficiencies have been measured for both detectors.

Drake, D.M.; Feldman, W.C.; Hurlbut, C.

1986-03-01

227

GLAS 532nm Optical Detector  

NASA Technical Reports Server (NTRS)

This report documents fabrication and testing of 532nm optical detectors. Testing procedures included 532nm quantum efficiency, detector gain, and photon counting performance, in particular, photon counting efficiency. 532nm quantum efficiency was measured to be 36% to 39% for the detectors fabricated. Detectors with a GaAs APD anode had measured gains of 12,000 to 15,000 maximum. Photon counting efficiency for the detector with an APD anode was measured to be approximately 80% with a detector gain of 11,000. Measurements made on an identical detector, not fabricated under this contract, had a photon counting efficiency exceeding 90% with a gain of 13,000. A formula is derived in which the photon counting efficiency is determined by the system preamp noise and the peak single photon pulse height which is proportional to detector gain. This formula agrees well with the measured results and indicates that a detector gain of 15,000 is sufficient to provide a counting efficiency of 99.6%.

LaRue, Ross A.

1997-01-01

228

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

E-print Network

; published online 14 April 2014) CR-39 solid-state nuclear track detectors are widely used in physics LLC. [http://dx.doi.org/10.1063/1.4870898] I. INTRODUCTION CR-39 solid-state nuclear track detectors in imploding capsules,2­6 as well as electric and magnetic fields in laser-driven high- energy-density physics

229

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

230

Semiconductor Detectors (Solid State Detectors)  

E-print Network

Semiconductor Detectors (Solid State Detectors) energy, position particles & photons energy loss conversion electron-hole pairs energetic "cheap" improved resolution #12;Semiconductor Detectors (Solid State electrons holes ni = Nc Nv exp -Eg 2kT = AT 3/ 2 exp -Eg 2kT #12;Semiconductor Detectors how

Peletier, Reynier

231

Gallium arsenide pixel detectors  

NASA Astrophysics Data System (ADS)

GaAs detectors can be fabricated with bidimensional single-sided electrode segmentation. They have been successfully bonded using flip-chip technology to the Omega-3 silicon read-out chip. We present here the design features of the GaAs pixel detectors and results from a test performed at the CERN SpS with a 120 GeV ?- beam. The detection efficiency was 99.2% with a nominal threshold of 5000 e -.

Bates, R.; Campbell, M.; Cantatore, E.; D'Auria, S.; da Vià, C.; del Papa, C.; Heijne, E. M.; Middelkamp, P.; O'Shea, V.; Raine, C.; Ropotar, I.; Scharfetter, L.; Smith, K.; Snoeys, W.

1998-02-01

232

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

233

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

234

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

235

Measurement of the detective quantum efficiency in digital detectors consistent with the IEC 62220-1 standard: practical considerations regarding the choice of filter material.  

PubMed

As part of a larger evaluation we attempted to measure the detective quantum efficiency (DQE) of an amorphous silicon flat-panel detector using the method described in the International Electrotechnical Commission standard 62220-1 published in October 2003. To achieve the radiographic beam conditions specified in the standard, we purchased scientific-grade ultrahigh purity aluminum (99.999% purity, type-11999 alloy) filters in thicknesses ranging from 0.1 through 10.0 mm from a well-known, specialty metals supplier. Qualitative evaluation of flat field images acquired at 71 kV (RQA5 beam quality) with 21 mm of ultrahigh purity aluminum filtration demonstrated a low frequency mottle that was reproducible and was not observed when the measurement was repeated at 74 kV (RQA5 beam quality) with 21 mm of lower-purity aluminum (99.0% purity, type-1100 alloy) filtration. This finding was ultimately attributed to the larger grain size (approximately 1-2 mm) of high purity aluminum metal, which is a well-known characteristic, particularly in thicknesses greater than 1 mm. The impact of this low frequency mottle is to significantly overestimate the noise power spectrum (NPS) at spatial frequencies < or = 0.2 mm(-1), which in turn would cause an underestimation of the DQE in this range. A subsequent evaluation of ultrahigh purity aluminum, purchased from a second source, suggests, that reduced grain size can be achieved by the process of annealing. Images acquired with this sample demonstrated vertical striated nonuniformities that are attributed to the manufacturing method and which do not appear to appreciably impact the NPS at spatial frequencies > or = 0.5 mm(-1), but do result in an asymmetry in the x- and y-NPS at spatial frequencies < or = 0.2 mm(-1). Our observations of markedly visible nonuniformities in images acquired with high purity aluminum filtration suggest that the uniformity of filter materials should be carefully evaluated and taken into consideration when measuring the DQE. PMID:16121586

Ranger, Nicole T; Samei, Ehsan; Dobbins, James T; Ravin, Carl E

2005-07-01

236

Tracing the phosphorus contamination sources and reducing the phosphorus contamination in HPGe crystal growth  

NASA Astrophysics Data System (ADS)

The net impurity concentration and the dislocation density for the grown crystals must be controlled within a narrow range of values to produce crystals acceptable for large-volume coaxial germanium detector fabrication. Phosphorus is the main shallow level donor in high purity germanium crystal. The phosphorus contamination is a disaster for growing p-type high-purity germanium crystal. The phosphorus contamination mainly comes from crucible, insulation, ambient gas or crystal growth chamber. Regrowth method was used to trace the phosphorus contamination sources. The contamination level from sources was discussed in detail in this paper. For different contamination source, targeted approaches were used to reduce the contamination.

Wang, Guojian; Guan, Yutong; Yang, Gang; Govani, Jayesh; Khizar, Muhammad; Mei, Hao; Mei, Dongming

2013-03-01

237

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

238

The effect of detector resolution for quantitative analysis of neutron stimulated emission computed tomography  

NASA Astrophysics Data System (ADS)

Previous research has shown benign and cancerous tissues to have different chemical make-ups. To measure the elemental concentration of biological samples noninvasively, we used neutron stimulated emission computed tomography (NSECT). When an incident neutron scatters inelastically from an atomic nucleus, it emits characteristic gamma energies, allowing for measurement of the elemental concentration of biological samples. Thus NSECT has the potential to be a method for precancerous tissue detection. In Monte Carlo simulations, we bombarded both a benign and a malignant human breast with 50 million neutrons. The resulting photon spectra were blurred to model the detector resolutions and then analyzed for peak detection. This simulation study analyzed the characteristic spectra using three detectors of different resolutions: a High-Purity Germanium (HPGe) semiconductor, a Bismuth Germanate (BGO) scintillator, and a Sodium Iodide (NaI) scintillator. The effective energy resolutions of these detectors are 0.1%, 7%, and 12%, respectively. The detectability of element peaks in the breast model was greatly reduced when the blur increased from just 0.1% to 7%. These initial experiments are valuable in choosing optimal detectors for peak detection in further NSECT studies and indicate that high-resolution detectors, such as HPGe, are required for using spectral peak analysis for breast cancer prediction.

Bender, Janelle E.; Floyd, Carey E.; Harrawood, Brian P.; Kapadia, Anuj J.; Sharma, Amy C.; Jesneck, Jonathan L.

2006-03-01

239

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

240

Enhanced efficiency of segmented silicon detectors of different thicknesses after proton irradiations up to 1×10 16 n eq cm 2  

NASA Astrophysics Data System (ADS)

Silicon sensors are used as tracker and vertex detectors in all the main current high energy physics experiments because of their unsurpassed performance in terms of granularity, resolution and speed while offering relatively low mass. The anticipated future upgrade of the present Large Hadron Collider (the Super LHC, sLHC) will require similar performance in terms of speed and low mass, but with increased granularity and a factor of ten more radiation tolerance. The radiation hardening of silicon detectors, given the sLHC requirements, is being investigated from many angles: different silicon materials, different electrode geometries and varying the thickness of the active substrate. It has been proposed that possible advantages could be achieved with detectors thinner than the accepted standard of 300 ?m. The charge collection properties of microstrip detectors made on thin (140 ?m) and standard p-type devices is here presented after various proton irradiation fluences up to 1×10 16 n eq cm -2. This is about the maximum dose expected for the pixel layers (excluding the innermost b-layer) located at the lower distance from the p-p collisions, where the reduction in thickness of the silicon sensors is a beneficial feature, due to the requirements for low mass at the innermost space points.

Casse, Gianluigi; Affolder, A.; Allport, P. P.; Brown, H.; Wormald, M.

2010-12-01

241

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

242

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

243

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

244

InI nuclear radiation detectors  

Microsoft Academic Search

Semiconductor radiation detectors were fabricated on single crystal wafers on indium iodide and tested both as direct radiation detectors and as optical detectors coupled to a scintillator crystal. Indium iodide is shown to be a promising material for fabricating room-temperature photodetectors for use in scintillation spectroscopy due to its high resistivity, good charge transport properties, and high quantum efficiency in

M. R. Squillante; C. Zhou; J. Zhang; L. P. Moy; K. S. Shah

1992-01-01

245

Characterization of naturally occurring radioactive materials in Libyan oil pipe scale using a germanium detector and Monte Carlo simulation  

NASA Astrophysics Data System (ADS)

Radioactive scale formation in various oil production facilities is acknowledged to pose a potential significant health and environmental issue. The presence of such an issue in Libyan oil fields was recognized as early as 1998. The naturally occurring radioactive materials (NORM) involved in this matter are radium isotopes (226Ra and 228Ra) and their decay products, precipitating into scales formed on the surfaces of production equipment. A field trip to a number of onshore Libyan oil fields has indicated the existence of elevated levels of specific activity in a number of locations in some of the more mature oil fields. In this study, oil scale samples collected from different parts of Libya have been characterized using gamma spectroscopy through use of a well shielded HPGe spectrometer. To avoid potential alpha-bearing dust inhalation and in accord with safe working practices at this University, the samples, contained in plastic bags and existing in different geometries, are not permitted to be opened. MCNP, a Monte Carlo simulation code, is being used to simulate the spectrometer and the scale samples in order to obtain the system absolute efficiency and then to calculate sample specific activities. The samples are assumed to have uniform densities and homogeneously distributed activity. Present results are compared to two extreme situations that were assumed in a previous study: (i) with the entire activity concentrated at a point on the sample surface proximal to the detector, simulating the sample lowest activity, and; (ii) with the entire activity concentrated at a point on the sample surface distal to the detector, simulating the sample highest activity.

Habib, A. S.; Shutt, A. L.; Regan, P. H.; Matthews, M. C.; Alsulaiti, H.; Bradley, D. A.

2014-02-01

246

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

247

Lanthanum Bromide Detectors for Safeguards Measurements  

SciTech Connect

Lanthanum bromide has advantages over other popular inorganic scintillator detectors. Lanthanum bromide offers superior resolution, and good efficiency when compared to sodium iodide and lanthanum chloride. It is a good alternative to high purity germanium detectors for some safeguards applications. This paper offers an initial look at lanthanum bromide detectors. Resolution of lanthanum bromide will be compared lanthanum chloride and sodium-iodide detectors through check source measurements. Relative efficiency and angular dependence will be looked at. Nuclear material spectra, to include plutonium and highly enriched uranium, will be compared between detector types.

Wright, J.

2011-05-25

248

Analysis of Cadmium Based Neutron Detector Configurations  

NASA Astrophysics Data System (ADS)

Due to national security concerns pertaining to the smuggling of special nuclear materials and a small supply of He-3 for use in neutron detectors, there is currently a need for a new kind of neutron detector. Using Monte Carlo techniques I have studied the neutron capture efficiency of an array of cadmium wedge detectors in the presence of a californium source. By using varying numbers of wedges and comparing their capture ratios we will be better able to design future detectors.

James, Brian; Rees, Lawrence; Czirr, J. Bart

2012-10-01

249

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

250

MS Detectors  

SciTech Connect

Good eyesight is often taken for granted, a situation that everyone appreciates once vision begins to fade with age. New eyeglasses or contact lenses are traditional ways to improve vision, but recent new technology, i.e. LASIK laser eye surgery, provides a new and exciting means for marked vision restoration and improvement. In mass spectrometry, detectors are the 'eyes' of the MS instrument. These 'eyes' have also been taken for granted. New detectors and new technologies are likewise needed to correct, improve, and extend ion detection and hence, our 'chemical vision'. The purpose of this report is to review and assess current MS detector technology and to provide a glimpse towards future detector technologies. It is hoped that the report will also serve to motivate interest, prompt ideas, and inspire new visions for ion detection research.

Koppenaal, David W.; Barinaga, Charles J.; Denton, M Bonner B.; Sperline, Roger P.; Hieftje, Gary M.; Schilling, G. D.; Andrade, Francisco J.; Barnes IV., James H.

2005-11-01

251

Detector Ensemble  

Microsoft Academic Search

Component-baseddetection methods have demonstrated their promise by integrating a set of part-detectors to deal with large appearance variations of the target. However, an essential and critical issue, i.e., how to handle the im- perfectness of part-detectors in the integration, is not well addressed in the literature. This paper proposes a detec- tor ensemble model that consists of a set of

Shengyang Dai; Ming Yang; Ying Wu; Aggelos K. Katsaggelos

2007-01-01

252

The BES detector  

Microsoft Academic Search

The Beijing Spectrometer (BES) is a general purpose solenoidal detector at the Beijing Electron Positron Collider (BEPC). It is designed to study exclusive final states in e+e- annihilations at the center of mass energy from 3.0 to 5.6 GeV. This requires large solid angle coverage combined with good charged particle momentum resolution, good particle identification and high photon detection efficiency

J. Z. Bai; Q. Bian; G. M. Chen; L. J. Chen; S. N. Chen; Y. Q. Chen; Z. Q. Chen; Y. K. Chi; H. C. Cui; X. Z. Cui; S. S. Deng; Y. W. Deng; H. L. Ding; B. Z. Dong; X. S. Dong; X. Du; Z. Z. Du; C. Feng; Z. Feng; Z. S. Fu; C. S. Gao; M. L. Gao; S. Q. Gao; W. X. Gao; Y. N. Gao; S. D. Gu; W. X. Gu; Y. Z. Guan; H. F. Guo; Y. N. Guo; Y. Y. Guo; S. W. Han; Y. Han; W. Hao; J. He; K. R. He; M. J. He; X. J. Hou; G. Y. Hu; J. S. Hu; J. W. Hu; D. Q. Huang; Y. Z. Huang; Q. P. Jia; C. H. Jiang; Q. Ju; Y. F. Lai; P. F. Lang; D. S. Li; F. Li; H. Li; Jia Li; J. T. Li; Jin Li; L. L. Li; P. Q. Li; Q. M. Li; R. B. Li; S. Q. Li; W. Li; Z. X. Li; G. N. Liang; F. C. Lin; S. Z. Lin; W. Lin; Q. Liu; R. G. Liu; W. Liu; X. Liu; Z. A. Liu; Z. Y. Liu; C. G. Lu; W. D. Lu; Z. Y. Lu; J. G. Lu; D. H. Ma; E. C. Ma; J. M. Ma; H. S. Mao; Z. P. Mao; X. C. Meng; H. L. Ni; J. Nie; Z. D. Nie; W. P. Niu; L. J. Pan; N. D. Qi; J. J. Qian; Y. H. Qu; Y. K. Que; G. Rong; T. Z. Ruan; Y. Y. Shao; B. W. Shen; D. L. Shen; J. Shen; H. Y. Sheng; J. P. Sheng; H. Z. Shi; X. F. Song; H. S. Sun; F. K. Tang; S. Q. Tang; W. H. Tian; F. Wang; G. Y. Wang; J. G. Wang; J. Y. Wang; L. S. Wang; L. Z. Wang; M. Wang; P. Wang; S. M. Wang; S. Q. Wang; T. J. Wang; X. W. Wang; Y. Y. Wang; Z. H. Wang; Z. J. Wang; C. L. Wei; Z. Z. Wei; J. W. Wu; S. H. Wu; S. Q. Wu; W. M. Wu; X. D. Wu; Z. D. Wu; D. M. Xi; X. M. Xia; J. Xiao; P. P. Xie; X. X. Xie; J. G. Xu; R. S. Xu; Z. Q. Xu; B. C. Xuan; S. T. Xue; J. Yan; S. P. Yan; W. G. Yan; C. Z. Yang; C. M. Yang; C. Y. Yang; X. F. Yang; X. R. Yang; M. H. Ye; C. H. Yu; C. S. Yu; Z. Q. Yu; B. Y. Zhang; C. D. Zhang; C. C. Zhang; C. Y. Zhang; D. H. Zhang; G. Zhang; H. Y. Zhang; H. L. Zhang; J. W. Zhang; L. S. Zhang; S. Q. Zhang; Y. P. Zhang; Y. M. Zhang; D. X. Zhao; J. W. Zhao; M. Zhao; P. D. Zhao; P. P. Zhao; W. R. Zhao; Z. G. Zhao; Z. Q. Zhao; J. P. Zheng; L. S. Zheng; M. Zheng; W. S. Zheng; Z. P. Zheng; G. P. Zhong; G. P. Zhou; H. S. Zhou; J. Zhou; Li Zhou; Lin Zhou; M. Zhou; Y. S. Zhou; Y. H. Zhou; G. S. Zhu; Q. M. Zhu; S. G. Zhu; Y. C. Zhu; Y. S. Zhu; B. A. Zhuang

1994-01-01

253

CdZnTe detector in diagnostic x-ray spectroscopy.  

PubMed

A method to utilize CdZnTe (CZT) detectors in diagnostic x-ray spectroscopy is described in this article. Spectral distortion due to transmission of primary x rays, the escape of cadmium- and tellurium-K fluorescent x rays, and tailing was severe in measured x-ray spectra. Therefore, correction for the distortion was performed with the stripping method using response functions. The response functions were calculated with the Monte Carlo method. The Hecht equation was employed to approximate the effects of carrier trapping in the calculations. The parameters in the Hecht equation, the mean-free path (lambda) of electrons and holes, were determined such that the tailing in calculated response functions fit that in measured gamma-ray spectra. Corrected x-ray spectra agreed well with the reference spectra measured with an HPGe detector. The results indicate that CZT detectors are suitable for diagnostic x-ray spectroscopy with appropriate corrections. PMID:12148722

Miyajima, Satoshi; Imagawa, Kotaro; Matsumoto, Masao

2002-07-01

254

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

255

Current readout of infrared detectors  

NASA Astrophysics Data System (ADS)

A buffered direct-injection (BDI) current readout for infrared detectors is described and analyzed. It is compared with the common direct-injection circuit with respect to injection efficiency, noise, and tolerance of low R(0)A product photovoltaic detectors. Power requirements and threshold control are also discussed. Throughout the analysis, it is clear that much advantage is gained at relatively little cost by the use of a BDI structure for an integrated circuit focal plane.

Bluzer, Nathan; Jensen, Arthur S.

1987-03-01

256

Neutron detectors comprising boron powder  

SciTech Connect

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

257

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 Navarrete, Estanislao; Amman, M.; Avignone, F. T.; Barabash, A.; Barton, P. J.; Beene, Jim; Bertrand, F.; Boswell, M.; Brudanin, V.; Busch, Matthew; Chan, Yuen-Dat; Christofferson, Cabot-Ann; Collar, Juan; Combs, Dustin C.; Cooper, R. J.; Detwiler, Jason A.; Doe, Peter J.; Efremenko, Yuri; Egorov, Viatcheslav; Ejiri, H.; Elliott, S. R.; Esterline, James H.; Fast, James E.; Fields, N.; Finnerty, P.; Fraenkle, Florian; Galindo-Uribarri, A.; Gehman, Victor M.; Giovanetti, G. K.; Green, Matthew P.; Guiseppe, Vincente; Gusey, K.; Hallin, A. L.; Hazama, R.; Henning, Reyco; Hoppe, Eric W.; Horton, Mark; Howard, Stanley; Howe, Mark; Johnson, R. A.; Keeter, K.; Kidd, Mary; Knecht, A.; Kochetov, Oleg; Konovalov, S.; Kouzes, Richard T.; LaFerriere, Brian D.; Leon, Jonathan D.; Leviner, L.; Loach, J. C.; Looker, Ron L.; Luke, P.; MacMullin, S.; Marino, Michael G.; Martin, R. D.; Merriman, Jason H.; Miller, M. L.; Mizouni, Leila K.; Nomachi, Masaharu; Orrell, John L.; Overman, Nicole R.; Perumpilly, Gopakumar; Phillips, D.; Poon, Alan; Radford, Davis; Rielage, Keith; Robertson, R. G. H.; Ronquest, M. C.; Schubert, Alexis G.; Shima, T.; Shirchenko, M.; Snavely, Kyle J.; Steele, David; Strain, J.; Timkin, V.; Tornow, W.; Varner, R. L.; Vetter, Kai; Vorren, Kris R.; Wilkerson, J. F.; Yakushev, E.; Yaver, Harold; Young, A.; Yu, Chang-Hong; Yumatov, Vladimir

2013-02-11

258

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

259

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

260

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

261

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

262

MS Detectors  

Microsoft Academic Search

Good eyesight is often taken for granted, a situation that everyone appreciates once vision begins to fade with age. New eyeglasses or contact lenses are traditional ways to improve vision, but recent new technology, i.e. LASIK laser eye surgery, provides a new and exciting means for marked vision restoration and improvement. In mass spectrometry, detectors are the 'eyes' of the

David W. Koppenaal; Charles J. Barinaga; M Bonner B. Denton; Roger P. Sperline; Gary M. Hieftje; Gregory D. Schilling; Francisco J. Andrade; James H. Barnes IV; IV IV

2005-01-01

263

The CLIC Vertex Detector  

E-print Network

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 meas- urement 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 ? W b will give access to the ttH-coupling measurement. In addition to those requirements driven by physics arguments, the CLIC bunch structure calls for hit tim- ing 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 ver- tex det...

Dannheim, D.

2014-01-01

264

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

265

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

266

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

267

Waste Characterization Using Gamma Ray Spectrometry with Automated Efficiency Optimization - 13404  

SciTech Connect

Gamma ray spectrometry using High Purity Germanium (HPGe) detectors is commonly employed in assaying radioactive waste streams from a variety of sources: nuclear power plants, Department of Energy (DOE) laboratories, medical facilities, decontamination and decommissioning activities etc. The radioactive material is typically packaged in boxes or drums (for e.g. B-25 boxes or 208 liter drums) and assayed to identify and quantify radionuclides. Depending on the origin of the waste stream, the radionuclides could be special nuclear materials (SNM), fission products, or activation products. Efficiency calibration of the measurement geometry is a critical step in the achieving accurate quantification of radionuclide content. Due to the large size of the waste items, it is impractical and expensive to manufacture gamma ray standard sources for performing a measurement based calibration. For well over a decade, mathematical efficiency methods such as those in Canberra's In Situ Object Counting System (ISOCS) have been successfully employed in the efficiency calibration of gamma based waste assay systems. In the traditional ISOCS based calibrations, the user provides input data such as the dimensions of the waste item, the average density and fill height of the matrix, and matrix composition. As in measurement based calibrations, the user typically defines a homogeneous matrix with a uniform distribution of radioactivity. Actual waste containers can be quite nonuniform, however. Such simplifying assumptions in the efficiency calibration could lead to a large Total Measurement Uncertainty (TMU), thus limiting the amount of waste that can be disposed of as intermediate or low activity level waste. To improve the accuracy of radionuclide quantification, and reduce the TMU, Canberra has developed the capability to optimize the efficiency calibration using the ISOCS method. The optimization is based on benchmarking the efficiency shape and magnitude to the data available in the analyzed gamma ray spectra. Data from measurements of a given item in multiple counting geometries are among the powerful benchmarks that could be used in the optimization. Also, while assaying a waste stream with fission products and activation products emitting gamma lines of multiple energies, optimizing the efficiency on the basis of line activity consistency is very effective. In the present paper, the ISOCS- based optimization methodology is applied to measurement scenarios involving multiple counting geometries, and multi-gamma-line radionuclides. Results will be presented along with accuracy and precision estimates for each measurement. (authors)

Bosko, A.; Venkataraman, R.; Bronson, F.L.; Ilie, G.; Russ, W.R. [Canberra Industries, 800 Research Parkway, Meriden, CT 06450 (United States)] [Canberra Industries, 800 Research Parkway, Meriden, CT 06450 (United States)

2013-07-01

268

Testing of radiation detectors by IBIC imaging  

Microsoft Academic Search

The nuclear microprobe technique IBIC (Ion Beam Induced Charge) was used for tests of different radiation detectors. By using a 2–6 MeV proton microbeam with a current of less than 1000 protons per second, images and profiles of charge collection efficiency in radiation detectors can be produced. This application of the IBIC technique provides results that can be used to

M. JaksiC; I. Bogdanovi?; M. Bogovac; S. Fazini?; S. Galassini; K. Kova?evi?; C. Manfredotti; E. Vittone

1996-01-01

269

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

270

A multiple-detector Radioactive Material Detection Spectroscopic (RMDS) portal  

NASA Astrophysics Data System (ADS)

This paper describes an optimization process for a Radioactive Material Detection Spectroscopic (RMDS) portal, designed to detect and identify radioactive materials concealed inside cargo containers. The system is based on a combination of conventional 3 in. NaI(Tl) gamma detectors and 3He neutron detection tubes. The basic concept and the advantages of the new segmented spectroscopic detector approach are presented with several algorithms that were developed to enhance the detection capability of the portal and improve the signal to noise ratio. The results of field tests performed in several locations in Israel are also presented. The RMDS portal fully meets the demands of new ANSI Standard 42.38 for spectroscopic portals. In addition, the portal has some unique features, such as the ability to find the exact location of a point source inside the cargo and the ability to differentiate between a point source and Naturally Occurring Radioactive Materials (NORM) radiation. During the tests, the RMDS portal was compared to other detection systems, such as a PVT-based portal and a handheld spectroscopic HPGe detector. In these tests, the RMDS system was found to have a unique technique for background subtraction, which results in a higher detection sensitivity.

Yaar, Ilan; Peysakhov, Ilya

2013-06-01

271

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

272

Fundamental properties of semiconductor materials, and material performance in detectors  

NASA Technical Reports Server (NTRS)

Procedures for determining fundamental properties of semiconductor materials, their performance as radiation detectors, and their service life as such detectors are given. Relationships were established between the minority carrier lifetime in the bulk of the material and the charge collection efficiency of the detector.

Casper, K. J.

1973-01-01

273

Physics and Detector Response Simulations  

NASA Astrophysics Data System (ADS)

As the complexity and resolution of modern detectors increases, the need for detailed simulation of the experimental setup also becomes more important. Designing detector systems composed of many disparate subsystems requires ef?cient tools to simulate the detector response and reconstruct the events. Comparisons of different technology options, or geometric layouts, are facilitated if the results can be obtained with a common simulation and reconstruction framework. We have developed efficient and ?exible 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 with a minimal investment of time and effort. 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. The reconstruction software and analysis environment are written in Java, providing a modern, object-oriented platform which is independent of the computing operating system.

Graf, Norman A.; McCormick, Jeremy

274

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

275

Microradiography with Semiconductor Pixel Detectors  

NASA Astrophysics Data System (ADS)

High resolution radiography (with X-rays, neutrons, heavy charged particles, …) often exploited also in tomographic mode to provide 3D images stands as a powerful imaging technique for instant and nondestructive visualization of fine internal structure of objects. Novel types of semiconductor single particle counting pixel detectors offer many advantages for radiation imaging: high detection efficiency, energy discrimination or direct energy measurement, noiseless digital integration (counting), high frame rate and virtually unlimited dynamic range. This article shows the application and potential of pixel detectors (such as Medipix2 or TimePix) in different fields of radiation imaging.

Jakubek, Jan; Cejnarova, Andrea; Dammer, Ji?í; Holý, Tomáš; Platkevi?, Michal; Pospíšil, Stanislav; Vav?ík, Daniel; Vykydal, Zden?k

2007-11-01

276

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

277

Works of art investigation with silicon drift detectors  

NASA Astrophysics Data System (ADS)

The X-ray fluorescence (XRF) spectroscopy analysis is a non-destructive technique widely used in archeometry to investigate the chemical composition of pigments, metal alloys and stones for restoration and historical investigation. The classical detection systems for archeometrical investigations utilize cryogenic detectors, like Si(Li) and HPGe, characterized by a satisfactory energy resolution (of the order of 140 eV FWHM at 6 keV). However, the requirements of liquid N 2 drastically limit the portability of such systems, limiting the possibility of making measurements "on the field". Recently new silicon PIN diodes Peltier cooled were introduced, allowing the construction of portable instrumentation. However, their energy resolution (of the order of 250 eV FWHM at 6 keV) results in some cases unsatisfactory (for instance in the identification of light elements). Both the requirements of portability and good energy resolution are fulfilled by the silicon drift detector (SDD). The SDD, cooled by a Peltier element, can reach resolutions better than 150 eV FWHM at 6 keV. These features make the device ideal for portable high resolution XRF spectrometers. A portable XRF spectrometer was realized at the research laboratories of Politecnico di Milano, and used for investigation on different kinds of works of art. Experimental results obtained in analysis of paintings of different ages and of metal alloys performed directly "on the field" are summarized.

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

2000-01-01

278

Detector simulation needs for detector designers  

SciTech Connect

Computer simulation of the components of SSC detectors and of the complete detectors will be very important for the designs of the detectors. The ratio of events from interesting physics to events from background processes is very low, so detailed understanding of detector response to the backgrounds is needed. Any large detector for the SSC will be very complex and expensive and every effort must be made to design detectors which will have excellent performance and will not have to undergo major rebuilding. Some areas in which computer simulation is particularly needed are pattern recognition in tracking detectors and development of shower simulation code which can be trusted as an aid in the design and optimization of calorimeters, including their electron identification performance. Existing codes require too much computer time to be practical and need to be compared with test beam data at energies of several hundred GeV. Computer simulation of the processing of the data, including electronics response to the signals from the detector components, processing of the data by microprocessors on the detector, the trigger, and data acquisition will be required. In this report we discuss the detector simulation needs for detector designers.

Hanson, G.G.

1987-11-01

279

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

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

280

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

281

Direct digital conversion detector technology  

Microsoft Academic Search

Future imaging sensors for the aerospace and commercial video markets will depend on low cost, high speed analog-to-digital (A\\/D) conversion to efficiently process optical detector signals. Current A\\/D methods place a heavy burden on system resources, increase noise, and limit the throughput. This paper describes a unique method for incorporating A\\/D conversion right on the focal plane array. This concept

William J. Mandl; Richard Fedors

1995-01-01

282

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

283

Thermal detector of solar energy with selective coating and vacuum thermal-insulation  

Microsoft Academic Search

The paper describes two design modifications of a solar-thermal-radiation detector with selective coating and screening vacuum insulation which operates reliably up to temperatures of 400 C. A method for calculating the operational characteristics of the detector is presented. Curves reflecting the dependence of thermal losses and efficiency on detector temperature for different modifications of the detector system and different solar

G. Ia. Umarov; V. S. Trukhov; U. Kh. Gaziev; T. Baimatov; T. Z. Abidov; Iu. E. Kliuchevskii

1978-01-01

284

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

285

D Simulation for Maximizing Electron Transfer Efficiency in Thick GEMS  

NASA Astrophysics Data System (ADS)

Thick GEM for UV detector applications must provide high detection efficiency for a single photoelectron produced by UV light. Electron Transfer Efficiency (ETE) of GEM detector determines the detection efficiency. We have used GARFIELD simulation for estimation of ETE at various operating parameters, which are to be optimized for high detection efficiency.

Garai, Baishali; Rajanna, K.; Radhakrishna, V.

2012-08-01

286

Large area liquid argon detectors for interrogation systems  

NASA Astrophysics Data System (ADS)

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; Gozani, Tsahi; Brown, Craig; Kwong, John; King, Michael J.; Nikkel, James A.; McKinsey, Dan

2013-04-01

287

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

288

Thallium bromide nuclear radiation detector development  

Microsoft Academic Search

Thallium bromide (TlBr) is a dense, high-Z, wide band gap 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, (??)e, to as

Alexei V. Churilov; Guido Ciampi; Hadong Kim; Leonard J. Cirignano; William M. Higgins; Fred Olschner; Kanai S. Shah

2008-01-01

289

Operation and performance of new NIR detectors from SELEX  

NASA Astrophysics Data System (ADS)

The European Space Agency (ESA) has funded SELEX Galileo, Southampton, UK to develop large format near infrared (NIR) detectors for its future space and ground based programmes. The UKATC has worked in collaboration with SELEX Galileo to test and characterise the new detectors produced during phase-1 of the development. In order to demonstrate the detector material performance, the HgCdTe (MCT) detector diodes (grown on GaAs substrate through MOVPE process in small 320×256, 24?m pixel format) are hybridised to the existing SELEX Galileo SWALLOW CMOS readout chip. The substrate removed and MCT thinned detector arrays were then tested and evaluated at the UKATC following screening tests at SELEX. This paper briefly describes the test setup, the operational aspects of the readout multiplexer and presents the performance parameters of the detector arrays including: conversion gain, detector dark current, read noise, linearity, quantum efficiency and persistence for various detector temperatures between 80K and 140K.

Atkinson, D.; Bezawada, N.; Hipwood, L. G.; Shorrocks, N.; Milne, H.

2012-07-01

290

7Li-induced reactions for fast-timing with LaBr3:Ce detectors  

NASA Astrophysics Data System (ADS)

7Li induced-reactions have been used with a 186W target to populate nuclei around A˜180-190 at the National Institute of Physics and Nuclear Engineering in Bucharest, Romania. An array of high-purity germanium (HPGe) and cerium-doped lanthanum bromide (LaBr3:Ce) detectors have been used to measure sub-nanosecond half-lives with fast-timing techniques. The yrast 2+ state in 190Os was measured to be t1/2 = 375(20)ps, in excellent agreement with the literature value. The previously unreported half-life of the 564-keV state in 189Ir has also been measured and a value of t1/2 = 540(100)ps ps obtained.

Mason, P. J. R.; Podolyàk, Zs.; M?rginean, N.; Regan, P. H.; Alexander, T.; Algora, A.; Alharbi, T.; Bowry, M.; Britton, R.; Bucurescu, D.; Bruce, A. M.; Bunce, M.; C?ta-Danil, G.; C?ta-Danil, I.; Cooper, N.; Deleanu, D.; Delion, D.; Filipescu, D.; Gelletly, W.; Glodariu, T.; Gheorghe, I.; Ghi??, D.; Ilie, G.; Ivanova, D.; Kisyov, S.; Lalkovski, S.; Lica, R.; Liddick, S. N.; M?rginean, R.; Mihai, C.; Mulholland, K.; Negret, A.; Nita, C. R.; Rice, S.; Roberts, O. J.; Sava, T.; Smith, J. F.; Söderström, P.-A.; Stevenson, P. D.; Stroe, L.; Toma, S.; Townsley, C.; Werner, V.; Wilson, E.; Wood, R. T.; Zamfir, N. V.; Zhekova, M.

2012-10-01

291

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

292

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

293

The MINOS detectors  

SciTech Connect

The Main Injector Neutrino Oscillation Search (MINOS) experiment's primary goal is the precision measurement of the neutrino oscillation parameters in the atmospheric neutrino sector. This long-baseline experiment uses Fermilab's NuMI beam, measured with a Near Detector at Fermilab, and again 735 km later using a Far Detector in the Soudan Mine Underground Lab in northern Minnesota. The detectors are magnetized iron/scintillator calorimeters. The Far Detector has been operational for cosmic ray and atmospheric neutrino data from July of 2003, the Near Detector from September 2004, and the NuMI beam started in early 2005. This poster presents details of the two detectors.

Habig, A.; Grashorn, E.W.; /Minnesota U., Duluth

2005-07-01

294

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

295

Construction and performance of silicon detectors for the small angle spectrometers of the collider detector of fermilab  

NASA Astrophysics Data System (ADS)

The manufacturing process of a series of position sensitive silicon detectors is described together with the tests performed to optimize the performance of the detectors. The detectors are Schottky diodes with strips on the ohmic contract which allow to determine the position of the incoming ionizing particles by charge partition. Four detectors were assembled in a telescope and tested inside the vacuum pipe of the Tevatron Collider at Fermilab. The system is a prototype of the Small Angle Silicon Spectrometer, designed primarily to study p- overlinep elastic and diffractive cross sections, and is a part of the Collider Detector of Fermilab (CDF). Several tests were performed to check the efficiency and the linearity of response of various regions of the detectors. Scans of the beam halo were also done both in high and low ? optics to check how close to the beam the detectors could be operated. Finally, the dependence of the detector response on temperature and integrated radiation dose was investigated.

Apollinari, G.; Bedeschi, F.; Bellettini, G.; Bosi, F.; Bosisio, L.; Cervelli, F.; Del Fabbro, R.; Dell'Orso, M.; Di Virgilio, A.; Focardi, E.; Giannetti, P.; Giorgi, M.; Menzione, A.; Ristori, L.; Scribano, A.; Sestini, P.; Stefanini, A.; Tonelli, G.; Zetti, F.; Bertolucci, S.; Cordelli, M.; Curatolo, M.; Dulach, B.; Esposito, B.; Giromini, P.; Miscetti, S.; Sansoni, A.; Belforte, S.; Chapin, T.; Chiarelli, G.; Giokaris, N.; Goulianos, K.; Plunkett, R.; White, S. N.

1987-01-01

296

Test vehicle detector characterization system for the Boeing YAL-1 airborne laser  

E-print Network

The test vehicle detector characterization system provides a convenient and efficient tool for rapidly evaluating the optical sensitivity of the GAP6012, GAP100, GAP300, and GAP1000 indium gallium arsenide detectors used ...

Steininger-Holmes, Jason Thomas

2008-01-01

297

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

298

CALIFA Barrel prototype detector characterisation  

NASA Astrophysics Data System (ADS)

Well established in the field of scintillator detection, Caesium Iodide remains at the forefront of scintillators for use in modern calorimeters. Recent developments in photosensor technology have lead to the production of Large Area Avalanche Photo Diodes (LAAPDs), a huge advancement on traditional photosensors in terms of high internal gain, dynamic range, magnetic field insensitivity, high quantum efficiency and fast recovery time. The R3B physics programme has a number of requirements for its calorimeter, one of the most challenging being the dual functionality as both a calorimeter and a spectrometer. This involves the simultaneous detection of ?300 MeV protons and gamma rays ranging from 0.1 to 20 MeV. This scintillator - photosensor coupling provides an excellent solution in this capacity, in part due to the near perfect match of the LAAPD quantum efficiency peak to the light output wavelength of CsI(Tl). Modern detector development is guided by use of Monte Carlo simulations to predict detector performance, nonetheless it is essential to benchmark these simulations against real data taken with prototype detector arrays. Here follows an account of the performance of two such prototypes representing different polar regions of the Barrel section of the forthcoming CALIFA calorimeter. Measurements were taken for gamma-ray energies up to 15.1 MeV (Maier-Leibnitz Laboratory, Garching, Germany) and for direct irradiation with a 180 MeV proton beam (The Svedberg Laboratoriet, Uppsala, Sweden). Results are discussed in light of complementary GEANT4 simulations.

Pietras, B.; Gascón, M.; Álvarez-Pol, H.; Bendel, M.; Bloch, T.; Casarejos, E.; Cortina-Gil, D.; Durán, I.; Fiori, E.; Gernhäuser, R.; González, D.; Kröll, T.; Le Bleis, T.; Montes, N.; Nácher, E.; Robles, M.; Perea, A.; Vilán, J. A.; Winkel, M.

2013-11-01

299

Asynchronous Failure Detectors  

E-print Network

Failure detectors -- oracles that provide information about process crashes -- are an important abstraction for crash tolerance in distributed systems. The generality of failure-detector theory, while providing great ...

Cornejo, Alejandro

2013-10-10

300

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.

Group, Kansas S.; Zollman, Dean A.

2004-03-05

301

Event-sequence detector  

NASA Technical Reports Server (NTRS)

Detector consists of matrix of storage elements which are activated by coincidence of failure-voltage pulses and clock pulses. Clock frequency used for event sequence detector can be selected to provide time resolution demanded by test at hand.

Hanna, M. F.

1973-01-01

302

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

303

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

304

LGB neutron detector  

NASA Astrophysics Data System (ADS)

The double pulse signature of the Gadolinium Lithium Borate Cerium doped plastic detector suggests its effectiveness for analyzing neutrons while providing gamma ray insensitivity. To better understand this detector, a californium gamma/neutron time of flight facility was constructed in our lab. Reported here are efforts to understand the properties and applications of the LGB detector with regards to neutron spectroscopy.

Quist, Nicole

2012-10-01

305

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

306

Preshower detector for ? +? - hadronic atom studies  

NASA Astrophysics Data System (ADS)

A preshower (PSh) detector has been prepared, tested and used at the CERN-DIRAC experiment [B. Adeva, et al., DIRAC proposal, CERN/SPSLC 95-1, SPSLC/P 284, 1995]. The aim of this experiment was to test some nonperturbative QCD predictions [J. Gasser, H. Leutwyler, Phys. Lett. B 125 (1983) 325; J. Gasser, H. Leutwyler, Ann. Phys. 158 (1984) 142; J. Gasser, H. Leutwyler, Nucl. Phys. B 250 (1985) 465; J. Bijnens, G. Colangelo, G. Ecker, J. Gasser, M.E. Sainio, Phys. Lett. B 374 (1996) 210] by measuring pionium (? +? - hadronic atom) lifetime. In this context the PSh detector, together with the Cherenkov detector, pursued to reject the background electron pairs in the region 1-4 GeV where the pion pairs from atom breakup were present. The technique used for pion/electron separation was to probe the electron shower development in the early formation stage in Pb converter. We have studied the dependence of the amplitude spectra on particle momentum and converter and scintillator thickness. The estimated electron rejection efficiency was better than 85% with a pion loss less than 5% for a preshower detector with Pb converter thickness w Pb=2.5 cm and scintillator slab w Sc=1 cm. The PSh track efficiency within the DIRAC setup has been measured with a global efficiency per arm better than 99%, slab efficiency per arm better than 96% and corresponding pair events efficiency per arm ˜99% and per slab ˜93%.

Pentia, M.; Ciocarlan, C.; Constantinescu, S.; Gugiu, M.; Caragheorgheopol, Gh.

2009-05-01

307

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

308

Plastic neutron detectors.  

SciTech Connect

This work demonstrated the feasibility and limitations of semiconducting {pi}-conjugated organic polymers for fast neutron detection via n-p elastic scattering. Charge collection in conjugated polymers in the family of substituted poly(p-phenylene vinylene)s (PPV) was evaluated using band-edge laser and proton beam ionization. These semiconducting materials can have high H/C ratio, wide bandgap, high resistivity and high dielectric strength, allowing high field operation with low leakage current and capacitance noise. The materials can also be solution cast, allowing possible low-cost radiation detector fabrication and scale-up. However, improvements in charge collection efficiency are necessary in order to achieve single particle detection with a reasonable sensitivity. The work examined processing variables, additives and environmental effects. Proton beam exposure was used to verify particle sensitivity and radiation hardness to a total exposure of approximately 1 MRAD. Conductivity exhibited sensitivity to temperature and humidity. The effects of molecular ordering were investigated in stretched films, and FTIR was used to quantify the order in films using the Hermans orientation function. The photoconductive response approximately doubled for stretch-aligned films with the stretch direction parallel to the electric field direction, when compared to as-cast films. The response was decreased when the stretch direction was orthogonal to the electric field. Stretch-aligned films also exhibited a significant sensitivity to the polarization of the laser excitation, whereas drop-cast films showed none, indicating improved mobility along the backbone, but poor {pi}-overlap in the orthogonal direction. Drop-cast composites of PPV with substituted fullerenes showed approximately a two order of magnitude increase in photoresponse, nearly independent of nanoparticle concentration. Interestingly, stretch-aligned composite films showed a substantial decrease in photoresponse with increasing stretch ratio. Other additives examined, including small molecules and cosolvents, did not cause any significant increase in photoresponse. Finally, we discovered an inverse-geometric particle track effect wherein increased track lengths created by tilting the detector off normal incidence resulted in decreased signal collection. This is interpreted as a trap-filling effect, leading to increased carrier mobility along the particle track direction. Estimated collection efficiency along the track direction was near 20 electrons/micron of track length, sufficient for particle counting in 50 micron thick films.

Wilson, Tiffany M.S; King, Michael J.; Doty, F. Patrick

2008-12-01

309

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

310

Semiconductor detector performance for low-energy x-rays  

SciTech Connect

Factors that limit the capabilities of semiconductor detectors at photon energies below 5 keV include energy resolution, detector efficiency, and detector-related continuum background. These properties can be controlled to a certain extent by optimal detector design and fabrication techniques. We describe measurements on the low-energy response of Si(Li) detectors obtained using a tunable, low-energy monochromatic source. Window thicknesses have been measured for a number of devices using different materials for the entry contact. The interpretation of these results in terms of existing detector window models is discussed. Results obtained using a new contact structure demonstrate that a dramatic reduction in window-related absorption in Si(Li) detectors can be achieved.

Jaklevic, J.M.; Walton, J.T.; McMurray, R.E. Jr.; Madden, N.W.; Goulding, F.S.

1987-06-01

311

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

312

Semiconductor detectors for the ATLAS inner tracker  

NASA Astrophysics Data System (ADS)

The ATLAS experiment currently under design for the CERN LHC contains an inner detector which tracks charged particles from the LHC beam-pipe to the electromagnetic calorimeter system. The main task is to reconstruct event tracks with high efficiency, to assist electron, photon and muon recognition and to reconstruct signatures of short-lived particles. Track densities at the LHC will be extremely large, and hence high precision measurements are required. This will be achieved using semiconductor tracking detectors, making use of silicon microstrip and pixel technology. For detectors closest to the beam interaction point the radiation levels are extremely high-up to 10 MRad. At the time of the ATLAS technical proposal, it was envisaged that gallium arsenide detectors could withstand such an environment. However, it has since become clear that GaAs is not as radiation hard as first expected, and that detectors would not perform sufficiently for the required time. In addition, progress on silicon detectors has indicated that they are able to withstand harsh radiation environments, and hence further work on silicon detectors now continues.

Morgan, Debbie

1998-02-01

313

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

314

High Resolution Scintillating Fiber Gamma Ray Detectors For Medical Imaging  

Microsoft Academic Search

High spatial and time resolution gamma ray detectors have been developed using plastic 'scintillating fibers coupled to position sensitive vacuum photomultipliers under development. These detectors can significantly improve the spatial resolution, time resolution, and efficiency of both SPECT and PET, extend the application of these technologies into new fields of medical research, and improve currently existing methods of medical diagnosis.

M. Atac; D. B. Cline; R. C. Chancy; E. J. Fenyves; G. Hademenos; P. P. Antich; M. D. Petroff

1990-01-01

315

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

316

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

317

Quasiparticle Trapping in Microwave Kinetic Inductance Strip Detectors  

E-print Network

in a WIMP dark matter detector. Various materials have been tested including tantalum, tin, and aluminum volume absorbers with high absorption efficiency. Quasiparticle trapping is also used by the Cryogenic-sided detector coverage due to their natural frequency domain multi- plexing. Additionally, the cryogenic

Golwala, Sunil

318

Smart detectors for Monte Carlo radiative transfer  

E-print Network

Many optimization techniques have been invented to reduce the noise that is inherent in Monte Carlo radiative transfer simulations. As the typical detectors used in Monte Carlo simulations do not take into account all the information contained in the impacting photon packages, there is still room to optimize this detection process and the corresponding estimate of the surface brightness distributions. We want to investigate how all the information contained in the distribution of impacting photon packages can be optimally used to decrease the noise in the surface brightness distributions and hence to increase the efficiency of Monte Carlo radiative transfer simulations. We demonstrate that the estimate of the surface brightness distribution in a Monte Carlo radiative transfer simulation is similar to the estimate of the density distribution in an SPH simulation. Based on this similarity, a recipe is constructed for smart detectors that take full advantage of the exact location of the impact of the photon packages. Several types of smart detectors, each corresponding to a different smoothing kernel, are presented. We show that smart detectors, while preserving the same effective resolution, reduce the noise in the surface brightness distributions compared to the classical detectors. The most efficient smart detector realizes a noise reduction of about 10%, which corresponds to a reduction of the required number of photon packages (i.e. a reduction of the simulation run time) of 20%. As the practical implementation of the smart detectors is straightforward and the additional computational cost is completely negligible, we recommend the use of smart detectors in Monte Carlo radiative transfer simulations.

Maarten Baes

2008-09-11

319

Smart detectors for Monte Carlo radiative transfer  

NASA Astrophysics Data System (ADS)

Many optimization techniques have been invented to reduce the noise that is inherent in Monte Carlo radiative transfer simulations. As the typical detectors used in Monte Carlo simulations do not take into account all the information contained in the impacting photon packages, there is still room to optimize this detection process and the corresponding estimate of the surface brightness distributions. We want to investigate how all the information contained in the distribution of impacting photon packages can be optimally used to decrease the noise in the surface brightness distributions and hence to increase the efficiency of Monte Carlo radiative transfer simulations. We demonstrate that the estimate of the surface brightness distribution in a Monte Carlo radiative transfer simulation is similar to the estimate of the density distribution in a smoothed particle hydrodynamics simulation. Based on this similarity, a recipe is constructed for smart detectors that take full advantage of the exact location of the impact of the photon packages. Several types of smart detectors, each corresponding to a different smoothing kernel, are presented. We show that smart detectors, while preserving the same effective resolution, reduce the noise in the surface brightness distributions compared to the classical detectors. The most efficient smart detector realizes a noise reduction of about 10 per cent, which corresponds to a reduction of the required number of photon packages (i.e. a reduction of the simulation run time) of 20 per cent. As the practical implementation of the smart detectors is straightforward and the additional computational cost is completely negligible, we recommend the use of smart detectors in Monte Carlo radiative transfer simulations.

Baes, Maarten

2008-12-01

320

The Belle Silicon Vertex Detector  

NASA Astrophysics Data System (ADS)

The Belle Silicon Vertex Detector (SVD) started working from June 1999 at the KEK B-factory experiment. The main purpose of the SVD is to make precise measurements of the B decay vertex position, which are essential for the observation of CP asymmetries. Excellent vertex resolution and a good detection efficiency are required for the SVD. In the present paper, the performance of Belle SVD is reviewed. The upgrade plan for the SVD2, which is under construction and will be installed in summer 2002, is also presented.

Kawasaki, T.

2002-11-01

321

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

322

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

323

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

324

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

325

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

326

Adaptors for radiation detectors  

DOEpatents

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

327

Radiation Effect On Gas Electron Multiplier Detector Performance  

SciTech Connect

Gas Electron Multiplier (GEM) detector is a gas device with high gain and high efficiency. These detectors use chemically perforated 65 {mu}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 {sup 60}Co 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 {sup 55}Fe 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 [Korean Atomic Energy Research Institute, Daejeon, 305-600 (Korea, Republic of); Baldeloma, Edwin; Park, Seongtae; White, Andrew P.; Yu, Jaehoon [Department of Physics, University of Texas at Arlington, Arlington TX 76019 (United States)

2011-06-01

328

Assessing CZT detector performance for environmental radioactivity investigations.  

PubMed

Cadmium zinc telluride (CdZnTe or CZT) is the leading semiconductor detector for gamma spectroscopy at room temperature. In the present study, a coplanar-grid CZT detector was used for gamma-ray measurements of environmental radioactivity on a contaminated saltmarsh sediment core in comparison with results from a coaxial high-purity germanium detector to assess their comparative performance. The findings reveal that the CZT performs well for both (241)Am and (137)Cs measurements over a broad range of activities, despite limited detector efficiency, and can be used to good effect in the study of environmental radioactivity in contaminated estuarine settings. PMID:23060429

Rahman, Rubina; Plater, A J; Nolan, P J; Appleby, P G

2013-05-01

329

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

330

Calibration of single-photon detectors using quantum statistics  

SciTech Connect

I show that calibration of the single-photon detector can be performed without knowledge of the signal parameters. Only partial information about the state statistics is sufficient for that. If one knows that the state is the squeezed one or the squeezed one mixed with the incoherent radiation, one can infer both the parameters of the state and the efficiency of the detector. For that one needs only to measure on/off statistics of detector clicks for the number of known absorbers placed before the detector. Thus, I suggest a scheme that performs a tomography of the signal and the measuring apparatus simultaneously.

Mogilevtsev, D. [Institute of Physics, Belarus National Academy of Sciences, F.Skarina Ave. 68, Minsk 220072 (Belarus) and Instituto de Fisica, UNICAMP, CP 6165, Campinas-SP, 13083-970 (Brazil)

2010-08-15

331

Scintillation detectors in gamma spectral logging; geometry, absorption and calibration  

USGS Publications Warehouse

The theory for the evaluation of the effects of geometry in gamma ray absorption is developed for cylindrical scintillation detectors as applicable to borehole gamma spectrometry. The results of a laboratory experiment are shown for comparison. A calibration procedure to determine detector efficiency is given for application to borehole probes. It is shown that the response of a crystal can be separated in terms of geometric effects and instrumentation effects. It is also shown that approximating crystal detectors with point detectors in mathematical theory is grossly oversimplified. (USGS)

Schimschal, Ulrich

1980-01-01

332

Analysis of nuclear resonance fluorescence excitation measured with LaBr3(Ce) detectors near 2 MeV  

NASA Astrophysics Data System (ADS)

The performance of LaBr3(Ce) to measure nuclear resonance fluorescence (NRF) excitations is discussed in terms of limits of detection and in comparison with high-purity germanium (HPGe) detectors near the 2 MeV region where many NRF excitation levels from special nuclear materials are located. The NRF experiment was performed at the High Intensity ?-ray Source (HI?S) facility. The incident ?-rays, of 2.12 MeV energy, hit a B4C target to excite the 11B nuclei to the first excitation level. The statistical-sensitive non-linear peak clipping (SNIP) algorithm was implemented to eliminate the background and enhance the limits of detection for the spectra measured with LaBr3(Ce). Both detection and determination limits were deduced from the experimental data.

Omer, Mohamed; Negm, Hani; Ohgaki, Hideaki; Daito, Izuru; Hayakawa, Takehito; Bakr, Mahmoud; Zen, Heishun; Hori, Toshitada; Kii, Toshiteru; Masuda, Kai; Hajima, Ryoichi; Shizuma, Toshiyuki; Toyokawa, Hiroyuki; Kikuzawa, Nobuhiro

2013-11-01

333

NaI Detector Network at Aragats  

NASA Astrophysics Data System (ADS)

The Aragats Space Environmental Center (ASEC) [1] provides monitoring of different species of secondary cosmic rays and consists of two high altitude research stations on Mt. Aragats in Armenia. Along with solar modulation effects, ASEC detectors register several coherent enhancements associated with thunderstorm activity. The experimental techniques used allowed for the first time to simultaneously measure fluxes of the electrons, muons, gamma rays, and neutrons correlated with thunderstorm activity [2,3]. Ground-based observations by a complex of surface particle detectors, measuring in systematically and repeatable fashion, gamma quanta, electrons, muons and neutrons from atmospheric sources are necessary for proving the theory of particle acceleration and multiplication during thunderstorms. Energy spectra and correlations between fluxes of different particles, measured on Earth's surface address the important issues of research of the solar modulation effects and the atmospheric high-energy phenomena. In May 26 2011, launched 5 NaI(Tl) (thallium-doped sodium iodide) scintillation detectors and 1 plastic one in the new ASEC laboratory on Aragats to detect low energy gamma rays from the thunderclouds and short particle bursts. Including NaI(Tl) detectors in ASEC detectors system is of great importance for investigation thunderstorm phenomena because NaI(Tl) detectors have high efficiency of gamma ray detecting in comparison with plastic ones.

Avakyan, Karen; Arakelyan, Karen; Chilingarian, Ashot; Daryan, Ara; Kozliner, Lev; Mailyan, Bagrat; Hovsepyan, Gagik; Pokhsraryan, David; Sargsyan, David

2013-02-01

334

6Li foil thermal neutron detector  

SciTech Connect

In this paper we report on the design of a multilayer thermal neutron detector based on {sup 6}Li reactive foil and thin film plastic scintillators. The {sup 6}Li foils have about twice the intrinsic efficiency of {sup 10}B films and about four times higher light output due to a unique combination of high energy of reaction particles, low self absorption, and low ionization density of tritons. The design configuration provides for double sided readout of the lithium foil resulting in a doubling of the efficiency relative to a classical reactive film detector and generating a pulse height distribution with a valley between neutron and gamma signals similar to {sup 3}He tubes. The tens of microns thickness of plastic scintillator limits the energy deposited by gamma rays, which provides the necessary neutron/gamma discrimination. We used MCNPX to model a multilayer Li foil detector design and compared it with the standard HLNCC-II (18 {sup 3}He tubes operated at 4 atm). The preliminary results of the {sup 6}Li configuration show higher efficiency and one third of the die-away time. These properties, combined with the very short dead time of the plastic scintillator, offer the potential of a very high performance detector.

Ianakiev, Kiril D [Los Alamos National Laboratory; Swinhoe, Martyn T [Los Alamos National Laboratory; Favalli, Andrea [Los Alamos National Laboratory; Chung, Kiwhan [Los Alamos National Laboratory; Macarthur, Duncan W [Los Alamos National Laboratory

2010-01-01

335

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

SciTech Connect

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

Amaré, J.; Borjabad, S.; Cebrián, S.; Cuesta, C.; Fortuño, D.; García, E.; Ginestra, C.; Gómez, H.; Martínez, M.; Oliván, M. A.; Ortigoza, Y.; Solórzano, A. Ortiz de; Pobes, C.; Puimedón, J.; Sarsa, M. L.; Villar, J. A.; Villar, P. [Laboratorio de Física Nuclear y Astropartículas, Universidad de Zaragoza, Calle Pedro Cerbuna 12, 50009 Zaragoza, Spain and Laboratorio Subterráneo de Canfranc, Paseo de los Ayerbe s/n, 22880 Canfranc Estación, Huesca (Spain)] [Laboratorio de Física Nuclear y Astropartículas, Universidad de Zaragoza, Calle Pedro Cerbuna 12, 50009 Zaragoza, Spain and Laboratorio Subterráneo de Canfranc, Paseo de los Ayerbe s/n, 22880 Canfranc Estación, Huesca (Spain)

2013-08-08

336

Instrumentation and Detectors  

NASA Astrophysics Data System (ADS)

This chapter contains a broad introduction to astronomical instruments and detectors. The basic design principles for cameras, spectrometers, polarimeters, and interferometers are given, together with some practical material on instrument building techniques, including vacuum-cryogenic methods. Different detector technologies are introduced, such as CCDs and infrared arrays, together with basic information on semiconductors.

McLean, Ian S.; Larkin, James; Fitzgerald, Michael

337

Arsenic activation neutron detector  

DOEpatents

A detector of bursts of neutrons from a deuterium-deuteron reaction includes a quantity of arsenic adjacent a gamma detector such as a scintillator and photomultiplier tube. The arsenic is activated by the 2.5-MeV neutrons to release gamma radiation which is detected to give a quantitative representation of detected neutrons.

Jacobs, E.L.

1980-01-28

338

Arsenic activation neutron detector  

DOEpatents

A detector of bursts of neutrons from a deuterium-deuteron reaction includes a quantity of arsenic adjacent a gamma detector such as a scintillator and photomultiplier tube. The arsenic is activated by the 2.5 Mev neutrons to release gamma radiation which is detected to give a quantitative representation of detected neutrons.

Jacobs, Eddy L. (Albuquerque, NM)

1981-01-01

339

Cable-splice detector  

NASA Technical Reports Server (NTRS)

Detector has possible uses in aerial cable-car systems, equipment handling in mines, boreholes, and undersea operations, and other applications where moving steel cable must be measured, monitored, or controlled. Detector consists of Hall-effect magnetic sensor located close to cable. Magnetic markings on cable are converted to electrical signals. Signals are filtered, amplified, and can actuate alarm.

Lee, R. D.; Iufer, E. J.; Giovannetti, A.

1980-01-01

340

Alkali ionization detector  

DOEpatents

A calibration filament containing a sodium-bearing compound is included in combination with the sensing filament and ion collector plate of a sodium ionization detector to permit periodic generation of sodium atoms for the in-situ calibration of the detector.

Hrizo, John (Monroeville, PA); Bauerle, James E. (Plum Borough, PA); Witkowski, Robert E. (West Mifflin, PA)

1982-01-01

341

BESII detector simulation  

Microsoft Academic Search

A Monte Carlo program based on GEANT3 has been developed for BESII detector simulation. The organization of the program is outlined, and the digitization procedure for simulating the response of various sub-detectors is described. Comparisons with data show that the performance of the program is generally satisfactory.

M. Ablikim; J. Z. Bai; Y. Ban; J. G. Bian; X. Cai; J. F. Chang; H. F. Chen; H. S. Chen; H. X. Chen; J. C. Chen; Jin Chen; Jun Chen; M. L. Chen; Y. B. Chen; B. S. Cheng; S. P. Chi; Y. P. Chu; X. Z. Cui; H. L. Dai; Y. S. Dai; Z. Y. Deng; L. Y. Dong; Q. F. Dong; S. X. Du; Z. Z. Du; J. Fang; S. S. Fang; C. D. Fu; H. Y. Fu; C. S. Gao; Y. N. Gao; M. Y. Gong; W. X. Gong; S. D. Gu; Y. N. Guo; Y. Q. Guo; Z. J. Guo; F. A. Harris; K. L. He; M. He; X. He; Y. K. Heng; H. M. Hu; T. Hu; G. S. Huang; X. P. Huang; X. T. Huang; X. B. Ji; C. H. Jiang; X. S. Jiang; D. P. Jin; S. Jin; Y. Jin; Y. F. Lai; C. G. Li; F. Li; G. Li; H. H. Li; J. Li; Q. J. Li; R. Y. Li; S. M. Li; W. D. Li; W. G. Li; X. L. Li; X. Q. Li; Y. L. Li; Y. F. Liang; H. B. Liao; C. X. Liu; F. Liu; Fang Liu; H. H. Liu; H. M. Liu; J. Liu; J. P. Liu; R. G. Liu; Z. A. Liu; Z. X. Liu; F. Lu; G. R. Lu; H. J. Lu; J. G. Lu; C. L. Luo; L. X. Luo; X. L. Luo; F. C. Ma; H. L. Ma; J. M. Ma; L. L. Ma; Q. M. Ma; X. B. Ma; X. Y. Ma; Z. P. Mao; X. H. Mo; J. Nie; Z. D. Nie; S. L. Olsen; H. P. Peng; N. D. Qi; C. D. Qian; H. Qin; J. F. Qiu; Z. Y. Ren; G. Rong; L. Y. Shan; L. Shang; D. L. Shen; X. Y. Shen; H. Y. Sheng; F. Shi; X. Shi; H. S. Sun; J. F. Sun; S. S. Sun; Y. Z. Sun; Z. J. Sun; X. Tang; N. Tao; Y. R. Tian; G. L. Tong; G. S. Varner; D. Y. Wang; J. Z. Wang; K. Wang; L. Wang; M. Wang; P. Wang; S. Z. Wang; W. F. Wang; Y. F. Wang; Z. Wang; Zheng Wang; C. L. Wei; D. H. Wei; N. Wu; Y. M. Wu; X. M. Xia; X. X. Xie; B. Xin; G. F. Xu; H. Xu; S. T. Xue; M. L. Yan; F. Yang; H. X. Yang; J. Yang; Y. X. Yang; M. Ye; Y. X. Ye; L. H. Yi; Z. Y. Yi; C. S. Yu; G. W. Yu; C. Z. Yuan; J. M. Yuan; Y. Yuan; S. L. Zang; Y. Zeng; Yu Zeng; B. X. Zhang; C. C. Zhang; D. H. Zhang; H. Y. Zhang; J. Zhang; Q. J. Zhang; S. Q. Zhang; X. M. Zhang; X. Y. Zhang; Y. Y. Zhang; Yiyun Zhang; Z. P. Zhang; Z. Q. Zhang; D. X. Zhao; J. B. Zhao; J. W. Zhao; M. G. Zhao; P. P. Zhao; W. R. Zhao; X. J. Zhao; Y. B. Zhao; Z. G. Zhao; H. Q. Zheng; J. P. Zheng; L. S. Zheng; Z. P. Zheng; X. C. Zhong; B. Q. Zhou; G. M. Zhou; L. Zhou; N. F. Zhou; K. J. Zhu; Q. M. Zhu; Y. C. Zhu; Y. S. Zhu; Yingchun Zhu; Z. A. Zhu; B. A. Zhuang; X. A. Zhuang; B. S. Zou

2005-01-01

342

Infrared Detector Spectroscopy  

NSDL National Science Digital Library

This resource, part of the Spectroscopy Lab Suite, simulates optical transitions in a pumped infrared detector. In this simulated experiment, impurity states are initially populated with visible light. Infrared radiation can then then be detected by de-populating the impurity levels, causing the material to glow. The energy levels and transitions in this material detector can be changed.

Group, Kansas S.; Zollman, Dean A.

2004-03-05

343

Smoke Detectors and Legislation.  

ERIC Educational Resources Information Center

This manual, one of a series for use in public education, provides an in-depth review of the current status of state and local smoke detector legislation. First, for the community considering a smoke detector law or ordinance, six decision points are discussed: which residential occupancy sub-classes will be affected; what the time factors are for…

National Fire Prevention and Control Administration (DOC), Washington, DC.

344

Third generation infrared detectors  

Microsoft Academic Search

In the paper, issues associated with the development and exploitation of materials used in fabrication of third generation infrared photon detectors are discussed. In this class of detectors two main competitors, HgCdTe photodiodes and quantum well photoconductors are considered. The metallurgical issues of the epitaxial layers such as uniformity and number of defected elements are the serious problems in the

A. Rogalski

2006-01-01

345

Modeling photo-detectors in quantum optics  

E-print Network

Photo-detection plays a fundamental role in experimental quantum optics and is of particular importance in the emerging field of linear optics quantum computing. Present theoretical treatment of photo-detectors is highly idealized and fails to consider many important physical effects. We present a physically motivated model for photo-detectors which accommodates for the effects of finite resolution, bandwidth and efficiency, as well as dark-counts and dead-time. We apply our model to two simple well known applications, which illustrates the significance of these characteristics.

Peter P. Rohde; Timothy C. Ralph

2005-11-10

346

Advances in Detector Technology for Infrared Astronomy  

NASA Technical Reports Server (NTRS)

Progress in semiconductor materials and processing technology has allowed the development of infrared detector arrays with unprecedented sensitivity, for imaging and spectroscopic applications in astronomy. The earlier discrete-detector approach has been replaced by large-element (up to 1024 x 1024 pixel), multiplexed devices. Progress has been made against a number of key limiting factors, such as quantum efficiency, noise, spectral response, linearity, and dark current. Future developments will focus on the need for even larger arrays, which operate at higher temperatures.

McCreight, Craig; Cheng, P. L. (Technical Monitor)

1995-01-01

347

Study of solid-conversion gaseous detector based on GEM for high energy X-ray industrial CT.  

PubMed

The general gaseous ionization detectors are not suitable for high energy X-ray industrial computed tomography (HEICT) because of their inherent limitations, especially low detective efficiency and large volume. The goal of this study was to investigate a new type of gaseous detector to solve these problems. The novel detector was made by a metal foil as X-ray convertor to improve the conversion efficiency, and the Gas Electron Multiplier (hereinafter "GEM") was used as electron amplifier to lessen its volume. The detective mechanism and signal formation of the detector was discussed in detail. The conversion efficiency was calculated by using EGSnrc Monte Carlo code, and the transport course of photon and secondary electron avalanche in the detector was simulated with the Maxwell and Garfield codes. The result indicated that this detector has higher conversion efficiency as well as less volume. Theoretically this kind of detector could be a perfect candidate for replacing the conventional detector in HEICT. PMID:24865206

Zhou, Rifeng; Zhou, Yaling

2014-01-01

348

Advanced far infrared detectors  

SciTech Connect

Recent advances in photoconductive and bolometric semiconductor detectors for wavelength 1 mm > {lambda} > 50 {mu}m are reviewed. Progress in detector performance in this photon energy range has been stimulated by new and stringent requirements for ground based, high altitude and space-borne telescopes for astronomical and astrophysical observations. The paper consists of chapters dealing with the various types of detectors: Be and Ga doped Ge photoconductors, stressed Ge:Ga devices and neutron transmutation doped Ge thermistors. Advances in the understanding of basic detector physics and the introduction of modern semiconductor device technology have led to predictable and reliable fabrication techniques. Integration of detectors into functional arrays has become feasible and is vigorously pursued by groups worldwide.

Haller, E.E.

1993-05-01

349

Nanomechanical resonance detector  

DOEpatents

An embodiment of a nanomechanical frequency detector includes a support structure and a plurality of elongated nanostructures coupled to the support structure. Each of the elongated nanostructures has a particular resonant frequency. The plurality of elongated nanostructures has a range of resonant frequencies. An embodiment of a method of identifying an object includes introducing the object to the nanomechanical resonance detector. A resonant response by at least one of the elongated nanostructures of the nanomechanical resonance detector indicates a vibrational mode of the object. An embodiment of a method of identifying a molecular species of the present invention includes introducing the molecular species to the nanomechanical resonance detector. A resonant response by at least one of the elongated nanostructures of the nanomechanical resonance detector indicates a vibrational mode of the molecular species.

Grossman, Jeffrey C; Zettl, Alexander K

2013-10-29

350

Performance characteristics of STIS detectors  

NASA Technical Reports Server (NTRS)

We report quantum efficiency measurements of back-illuminated, ion-implanted, laser-annealed charge coupled devices (CCD's) in the wavelength range 13-10,000 A. The equivalent quantum efficiency (EQE = effective photons detected per incident photon) ranges from a minimum of 5 percent as 1216 A to a maximum of 87 percent at 135 A. Using a simple relationship for the charge collection efficiency of the CCD pixels as a function of depth, we present a semi-empirical model with few parameters which reproduces our measurements with a fair degree of accuracy. The advantage of this model is that is can be used to predict CCD QE performance for shallow backside implanted devices without detailed solution of a system of differential equations, as in conventional approaches, and yields a simple analytic form for the charge collection efficiency which is adequate for detector calibration purposes. Making detailed assumptions about the dopant profile, we also solve the carrier density and continuity equations in order to relate our semi-empirical model parameters to surface and bulk device properties. The latter procedure helps to better establish device processing parameters for a given level of CCD QE performance.

Stern, Robert A.

1992-01-01

351

TM Failed Detectors Data Replacement  

NASA Technical Reports Server (NTRS)

Some of the LANDSAT 4 Thematic Mapper detectors (band 2 detector 4 and band 5 detector 3) have inadequate performances. The operational system correction processing will disregard the data sensed by the failed detectors and replace them by data coming from the neighbor detectors of the same spectra band. The analysis performed by ESA Earthnet and attempts to suggest an operational failed detector replacement algorithm are described.

Fusco, L.; Trevese, D.

1984-01-01

352

The HERMES recoil detector  

NASA Astrophysics Data System (ADS)

For the final running period of HERA, a recoil detector was installed at the HERMES experiment to improve measurements of hard exclusive processes in charged-lepton nucleon scattering. Here, deeply virtual Compton scattering is of particular interest as this process provides constraints on generalised parton distributions that give access to the total angular momenta of quarks within the nucleon. The HERMES recoil detector was designed to improve the selection of exclusive events by a direct measurement of the four-momentum of the recoiling particle. It consisted of three components: two layers of double-sided silicon strip sensors inside the HERA beam vacuum, a two-barrel scintillating fibre tracker, and a photon detector. All sub-detectors were located inside a solenoidal magnetic field with a field strength of 1T. The recoil detector was installed in late 2005. After the commissioning of all components was finished in September 2006, it operated stably until the end of data taking at HERA end of June 2007. The present paper gives a brief overview of the physics processes of interest and the general detector design. The recoil detector components, their calibration, the momentum reconstruction of charged particles, and the event selection are described in detail. The paper closes with a summary of the performance of the detection system.

Airapetian, A.; Aschenauer, E. C.; Belostotski, S.; Borisenko, A.; Bowles, J.; Brodski, I.; Bryzgalov, V.; Burns, J.; Capitani, G. P.; Carassiti, V.; Ciullo, G.; Clarkson, A.; Contalbrigo, M.; De Leo, R.; De Sanctis, E.; Diefenthaler, M.; Di Nezza, P.; Düren, M.; Ehrenfried, M.; Guler, H.; Gregor, I. M.; Hartig, M.; Hill, G.; Hoek, M.; Holler, Y.; Hristova, I.; Jo, H. S.; Kaiser, R.; Keri, T.; Kisselev, A.; Krause, B.; Krauss, B.; Lagamba, L.; Lehmann, I.; Lenisa, P.; Lu, S.; Lu, X.-G.; Lumsden, S.; Mahon, D.; Martinez de la Ossa, A.; Murray, M.; Mussgiller, A.; Nowak, W.-D.; Naryshkin, Y.; Osborne, A.; Pappalardo, L. L.; Perez-Benito, R.; Petrov, A.; Pickert, N.; Prahl, V.; Protopopescu, D.; Reinecke, M.; Riedl, C.; Rith, K.; Rosner, G.; Rubacek, L.; Ryckbosch, D.; Salomatin, Y.; Schnell, G.; Seitz, B.; Shearer, C.; Shutov, V.; Statera, M.; Steijger, J. J. M.; Stenzel, H.; Stewart, J.; Stinzing, F.; Trzcinski, A.; Tytgat, M.; Vandenbroucke, A.; Van Haarlem, Y.; Van Hulse, C.; Varanda, M.; Veretennikov, D.; Vilardi, I.; Vikhrov, V.; Vogel, C.; Yaschenko, S.; Ye, Z.; Yu, W.; Zeiler, D.; Zihlmann, B.

2013-05-01

353

Detectors for Tomorrow's Instruments  

NASA Technical Reports Server (NTRS)

Cryogenically cooled superconducting detectors have become essential tools for a wide range of measurement applications, ranging from quantum limited heterodyne detection in the millimeter range to direct searches for dark matter with superconducting phonon detectors operating at 20 mK. Superconducting detectors have several fundamental and practical advantages which have resulted in their rapid adoption by experimenters. Their excellent performance arises in part from reductions in noise resulting from their low operating temperatures, but unique superconducting properties provide a wide range of mechanisms for detection. For example, the steep dependence of resistance with temperature on the superconductor/normal transition provides a sensitive thermometer for calorimetric and bolometric applications. Parametric changes in the properties of superconducting resonators provides a mechanism for high sensitivity detection of submillimeter photons. From a practical point of view, the use of superconducting detectors has grown rapidly because many of these devices couple well to SQUID amplifiers, which are easily integrated with the detectors. These SQUID-based amplifiers and multiplexers have matured with the detectors; they are convenient to use, and have excellent noise performance. The first generation of fully integrated large scale superconducting detection systems are now being deployed. I will discuss the prospects for a new generation of instruments designed to take full advantage of the revolution in detector technology.

Moseley, Harvey

2009-01-01

354

Centroid tracking with area array detectors  

NASA Technical Reports Server (NTRS)

A computer program (ALGEVAL) has been developed to simulate the position estimating behavior of a centroid estimator algorithm using data typical of optical point spread function data recorded by an area array detector. Typical results are shown of varying detector properties and optical point spread function types. The detector parameters currently available for study include read noise mean value, dark current mean value and spatial variation, charge transfer efficiency and point spread function location, saturation level, signal level and pixel size. The program is capable of calculating any order centroid using an array size from 2 x 2 to 15 x 15 pixels. The output of the program is either a performance map, histogram data or tabluar data. A number of further developments are recommended.

Glavich, T. A.

1986-01-01

355

Extrinsic germanium Blocked Impurity Bank (BIB) detectors  

NASA Technical Reports Server (NTRS)

Ge:Ga blocked-impurity-band (BIB) detectors with long wavelength thresholds greater than 190 microns and peak quantum efficiencies of 4 percent, at an operating temperature of 1.8 K, have been fabricated. These proof of concept devices consist of a high purity germanium blocking layer epitaxially grown on a Ga-doped Ge substrate. This demonstration of BIB behavior in germanium enables the development of far infrared detector arrays similar to the current silicon-based devices. Present efforts are focussed on improving the chemical vapor deposition process used to create the blocking layer and on the lithographic processing required to produce monolithic detector arrays in germanium. Approaches to test the impurity levels in both the blocking and active layers are considered.

Krabach, Timothy N.; Huffman, James E.; Watson, Dan M.

1989-01-01

356

The fine grained detector readout electronics  

NASA Astrophysics Data System (ADS)

The Fine Grained Detector (FGD) readout electronics was designed to record a snapshot of the detector activity before, during and after the neutrino beam spill produced by the J-PARC accelerator complex in Tokai, Japan. The FGD is a key element of T2K near detector currently being constructed. It will act as an active target detecting charged particles produced within its scintillator bars. The original feature of the FGD electronics is to readout Multi-Pixel Photon Counters by recording waveforms using Switch Capacitor Array chips (AFTER ASIC) designed for T2K Time Projection Chamber. In these proceedings, we describe the architecture of the FGD electronics. Beam results show that the physics requirements are met or exceeded. The relatively slow sampling frequency of the AFTER ASIC does not impair the timing resolution significantly. In addition, the very good efficiency of the system for detecting Michel electrons produced by pions or muons decay has been demonstrated.

Retière, F.; T2K/FGD Collaboration

2010-11-01

357

Micropattern Gaseous Detectors  

NASA Astrophysics Data System (ADS)

Introduced in 1988, microstrip gas chambers perform considerably better than classic multiwire detectors. Excellent localization, high rate capability, and good granularity make them attractive for charged-particle tracking at high-luminosity colliders, among other applications. The technology continues to improve; for example, substrates have been developed that prevent charge accumulations. Some problems persist, namely the slow degradation under sustained irradiation (aging) and the serious damage that can result from accidental discharges. New types of detectors aim at improving on these points; the microdot, micromegas, and gas electron multiplier detectors are promising examples. They are generally more reliable and cheaper.

Sauli, Fabio; Sharma, Archana

358

Measurement of terrestrial gamma radiation dose-rate (TGRD) level in soil samples from the district of Rembau, Malaysia, using high-purity Germanium detectors  

NASA Astrophysics Data System (ADS)

This study assesses the gamma radiation levels and associated dose rates from the naturally occurring radionuclides 232Th, 238U and 40K in soil samples collected from the district of Rembau, Malaysia using High-purity Germanium (HPGe) Detectors. A 105 measurement were performed on surface soil using NaI (Tl) gamma-ray detector with crystal size 1"x1", covering about 83% land of the Rembau district. The concentration of the naturally occurring radionuclides 232Th, 238U and 40K in soil samples collected were determined by using HPGe detector based on high-resolution gamma spectrometry system at Malaysia Nuclear Agency. The range of natural gamma radiation measured was from 114±14 nGy h?1 to 857±14 nGy h?1. The range of activity concentrations of U, Th and °K in soil from the studied areas varies from 151-401 Bq kg?1, 113-342 Bq kg?1 and 674-1526 Bq kg?1 with mean values of 245 Bq kg?1, 186 Bq kg?1 and 1152 Bq kg1 respectively. The mean values of terrestrial gamma radiation dose rate measured in Rembau district is 383±18 nGy h?1 compared to the Malaysian average is 92 nGy h?1 and world average is 59 nGy h?1 (UNSCEAR, 2000). The average annual dose from such terrestrial gamma radiation dose rates to an individual in Rembau district, assuming a tropical rural setting is estimated to be 0.78 mSv per year, which is considered to be within the normal range for doses from natural sources. An isodose map for the Rembau district has been plotted.

Norbani, N. E.; Abdullah Salim, N. A.; Rahman, A. T. Abdul

2014-11-01

359

Trustworthiness of detectors in quantum key distribution with untrusted detectors  

E-print Network

Measurement-device-independent quantum key distribution (MDI-QKD) protocol has been demonstrated as a viable solution to detector side-channel attacks. One of the main advantages of MDI-QKD is that the security can be proved without making any assumptions about how the measurement device works. The price to pay is the relatively low secure key rate comparing with conventional quantum key distribution (QKD), such as the decoy-state BB84 protocol. Recently a new QKD protocol, aiming at bridging the strong security of MDI-QKD with the high efficiency of conventional QKD, has been proposed. In this protocol, the legitimate receiver employs a trusted linear optics network to encode information on photons received from an insecure quantum channel, and then performs a Bell state measurement (BSM) using untrusted detectors. One crucial assumption made in most of these studies is that the untrusted 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 Eve 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.

Bing Qi

2014-11-14

360

On the absolute source activity measurement with a single detector: The 133Ba case  

NASA Astrophysics Data System (ADS)

The activity of a 133Ba point source is measured with a single HPGe detector by placing the source on the detector end-cap. Activity is obtained using net peak areas and total spectrum area, as well as true and random (pile-up) peaks. For data analysis, two different methods are applied. In one, the method for activity observation that implies an exact treatment of the decay scheme and all possible outcomes introduced by Novkovi? et al. [9] (D. Novkovi?, A. Kandi?, M. ?uraševi?, I. Vukanac, Z. Miloševi?, L. Na??er?, Nucl. Instr. and Meth. A 582 (2007) 592.) is extended to pile-up events of first order, which predicts 2375 different peaks in the spectrum of 133Ba. In the second method, since the 133Ba decay is followed by emission of one dominant cascade, a simple method was developed for activity measurement of 133Ba source where the summing probability of X-rays with gamma rays can be neglected. It is shown that by taking into account the pile-up events in the spectrum, via the methods described here, accurate direct activity measurements of 133Ba source are possible even at higher count rates. The methods are applied to the spectra with count rates up to 36×10 3 s -1, and the measured activity values agree with the reference values within 1%.

Bikit, I.; Nemes, T.; Mrda, D.; Jovan?evi?, N.

2009-12-01

361

Modular optical detector system  

DOEpatents

A modular optical detector system. The detector system is designed to detect the presence of molecules or molecular species by inducing fluorescence with exciting radiation and detecting the emitted fluorescence. Because the system is capable of accurately detecting and measuring picomolar concentrations it is ideally suited for use with microchemical analysis systems generally and capillary chromatographic systems in particular. By employing a modular design, the detector system provides both the ability to replace various elements of the detector system without requiring extensive realignment or recalibration of the components as well as minimal user interaction with the system. In addition, the modular concept provides for the use and addition of a wide variety of components, including optical elements (lenses and filters), light sources, and detection means, to fit particular needs.

Horn, Brent A. (Livermore, CA); Renzi, Ronald F. (Tracy, CA)

2006-02-14

362

Ultrafast neutron detector  

DOEpatents

A neutron detector of very high temporal resolution is described. It may be used to measure distributions of neutrons produced by fusion reactions that persist for times as short as about 50 picoseconds.

Wang, C.L.

1985-06-19

363

SRAM Detector Calibration  

NASA Technical Reports Server (NTRS)

Custom proton sensitive SRAM chips are being flown on the BMDO Clementine missions and Space Technology Research Vehicle experiments. This paper describes the calibration procedure for the SRAM proton detectors and their response to the space environment.

Soli, G. A.; Blaes, B. R.; Beuhler, M. G.

1994-01-01

364

Lightning Current Detector  

NASA Technical Reports Server (NTRS)

Lightning Current Detector (LCD) was developed to monitor the magnitude of lightning strikes. Information it supplies is useful in evaluating lightning protection designs for such systems as telephone cables, radio broadcast towers, power transmission equipment and oil well towers.

1981-01-01

365

Improved gaseous leak detector  

DOEpatents

In a short path length mass-spectrometer type of helium leak detector wherein the helium trace gas is ionized, accelerated and deflected onto a particle counter, an arrangement is provided for converting the detector to neon leak detection. The magnetic field of the deflection system is lowered so as to bring the nonlinear fringe area of the magnetic field across the ion path, thereby increasing the amount of deflection of the heavier neon ions.

Juravic, F.E. Jr.

1983-10-06

366

A photoionization detector  

Microsoft Academic Search

A photoionization detector (P.I.D.) with separated discharge and detection compartments, enabling detection of eluted substances under normal pressure, has been developed. A detection mechanism was formulated for these conditions and relations for the P.I.D. signal were derived. The detector can measure all substances with ionization potentials less than 11.4 eV. A detection limit of 10?14 mol\\/s for benzene, with a

J. Šev?ik; S. Krýsl

1973-01-01

367

Fiber optic detector  

SciTech Connect

This invention is comprised of a portable fiber optic detector that senses the presence of specific target chemicals by exchanging the target chemical for a fluorescently-tagged antigen that is bound to an antibody which is in turn attached to an optical fiber. Replacing the fluorescently-tagged antigen reduces the fluorescence so that a photon sensing detector records the reduced light level and activates an appropriate alarm or indicator.

Partin, J.K.; Ward, T.E.; Grey, A.E.

1990-12-31

368

Gaseous leak detector  

DOEpatents

In a short path length mass-spectrometer type of helium leak detector wherein the helium trace gas is ionized, accelerated and deflected onto a particle counter, an arrangement is provided for converting the detector to neon leak detection. The magnetic field of the deflection system is lowered so as to bring the non linear fringe area of the magnetic field across the ion path, thereby increasing the amount of deflection of the heavier neon ions.

Juravic, Jr., Frank E. (Aurora, IL)

1988-01-01

369

Fiber optic detector  

NASA Astrophysics Data System (ADS)

This invention is comprised of a portable fiber optic detector that senses the presence of specific target chemicals by exchanging the target chemical for a fluorescently-tagged antigen that is bound to an antibody which is in turn attached to an optical fiber. Replacing the fluorescently-tagged antigen reduces the fluorescence so that a photon sensing detector records the reduced light level and activates an appropriate alarm or indicator.

Partin, Judy K.; Ward, Thomas E.; Grey, Alan E.

1990-04-01

370

The ATLAS Inner Detector commissioning and calibration  

NASA Astrophysics Data System (ADS)

The ATLAS Inner Detector is a composite tracking system consisting of silicon pixels, silicon strips and straw tubes in a 2 T magnetic field. Its installation was completed in August 2008 and the detector took part in data-taking with single LHC beams and cosmic rays. The initial detector operation, hardware commissioning and in-situ calibrations are described. Tracking performance has been measured with 7.6 million cosmic-ray events, collected using a tracking trigger and reconstructed with modular pattern-recognition and fitting software. The intrinsic hit efficiency and tracking trigger efficiencies are close to 100%. Lorentz angle measurements for both electrons and holes, specific energy-loss calibration and transition radiation turn-on measurements have been performed. Different alignment techniques have been used to reconstruct the detector geometry. After the initial alignment, a transverse impact parameter resolution of 22.1±0.9 ?m and a relative momentum resolution ? p / p=(4.83±0.16)×10-4 GeV-1× p T have been measured for high momentum tracks.

Aad, G.; Abbott, B.; Abdallah, J.; Abdelalim, A. A.; Abdesselam, A.; Abdinov, O.; Abi, B.; Abolins, M.; Abramowicz, H.; Abreu, H.; Acharya, B. S.; Adams, D. L.; Addy, T. N.; Adelman, J.; Adorisio, C.; Adragna, P.; Adye, T.; Aefsky, S.; Aguilar-Saavedra, J. A.; Aharrouche, M.; Ahlen, S. P.; Ahles, F.; Ahmad, A.; Ahsan, M.; Aielli, G.; Akdogan, T.; Åkesson, T. P. A.; Akimoto, G.; Akimov, A. V.; Aktas, A.; Alam, M. S.; Alam, M. A.; Albrand, S.; Aleksa, M.; Aleksandrov, I. N.; Alexa, C.; Alexander, G.; Alexandre, G.; Alexopoulos, T.; Alhroob, M.; Aliev, M.; Alimonti, G.; Alison, J.; Aliyev, M.; Allport, P. P.; Allwood-Spiers, S. E.; Almond, J.; Aloisio, A.; Alon, R.; Alonso, A.; Alviggi, M. G.; Amako, K.; Amelung, C.; Amorim, A.; Amorós, G.; Amram, N.; Anastopoulos, C.; Andeen, T.; Anders, C. F.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Anduaga, X. S.; Angerami, A.; Anghinolfi, F.; Anjos, N.; Annovi, A.; Antonaki, A.; Antonelli, M.; Antonelli, S.; Antos, J.; Antunovic, B.; Anulli, F.; Aoun, S.; Arabidze, G.; Aracena, I.; Arai, Y.; Arce, A. T. H.; Archambault, J. P.; Arfaoui, S.; Arguin, J.-F.; Argyropoulos, T.; Arik, M.; Armbruster, A. J.; Arnaez, O.; Arnault, C.; Artamonov, A.; Arutinov, D.; Asai, M.; Asai, S.; Asfandiyarov, R.; Ask, S.; Åsman, B.; Asner, D.; Asquith, L.; Assamagan, K.; Astvatsatourov, A.; Atoian, G.; Auerbach, B.; Augsten, K.; Aurousseau, M.; Austin, N.; Avolio, G.; Avramidou, R.; Ay, C.; Azuelos, G.; Azuma, Y.; Baak, M. A.; Bach, A. M.; Bachacou, H.; Bachas, K.; Backes, M.; Badescu, E.; Bagnaia, P.; Bai, Y.; Bain, T.; Baines, J. T.; Baker, O. K.; Baker, M. D.; Baker, S.; Dos Santos Pedrosa, F. Baltasar; Banas, E.; Banerjee, P.; Banerjee, S.; Banfi, D.; Bangert, A.; Bansal, V.; Baranov, S. P.; Barashkou, A.; Barber, T.; Barberio, E. L.; Barberis, D.; Barbero, M.; Bardin, D. Y.; Barillari, T.; Barisonzi, M.; Barklow, T.; Barlow, N.; Barnett, B. M.; Barnett, R. M.; Baroncelli, A.; Barr, A. J.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Barrillon, P.; Bartoldus, R.; Bartsch, D.; Bates, R. L.; Batkova, L.; Batley, J. R.; Battaglia, A.; Battistin, M.; Bauer, F.; Bawa, H. S.; Bazalova, M.; Beare, B.; Beau, T.; Beauchemin, P. H.; Beccherle, R.; Bechtle, P.; Beck, G. A.; Beck, H. P.; Beckingham, M.; Becks, K. H.; Beddall, A. J.; Beddall, A.; Bednyakov, V. A.; Bee, C.; Begel, M.; Harpaz, S. Behar; Behera, P. K.; Beimforde, M.; Belanger-Champagne, C.; Bell, P. J.; Bell, W. H.; Bella, G.; Bellagamba, L.; Bellina, F.; Bellomo, M.; Belloni, A.; Belotskiy, K.; Beltramello, O.; Ami, S. Ben; Benary, O.; Benchekroun, D.; Bendel, M.; Benedict, B. H.; Benekos, N.; Benhammou, Y.; Benjamin, D. P.; Benoit, M.; Bensinger, J. R.; Benslama, K.; Bentvelsen, S.; Beretta, M.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Berghaus, F.; Berglund, E.; Beringer, J.; Bernabéu, J.; Bernat, P.; Bernhard, R.; Bernius, C.; Berry, T.; Bertin, A.; Besana, M. I.; Besson, N.; Bethke, S.; Bianchi, R. M.; Bianco, M.; Biebel, O.; Biesiada, J.; Biglietti, M.; Bilokon, H.; Bindi, M.; Bingul, A.; Bini, C.; Biscarat, C.; Bitenc, U.; Black, K. M.; Blair, R. E.; Blanchard, J.-B.; Blanchot, G.; Blocker, C.; Blondel, A.; Blum, W.; Blumenschein, U.; Bobbink, G. J.; Bocci, A.; Boehler, M.; Boek, J.; Boelaert, N.; Böser, S.; Bogaerts, J. A.; Bogouch, A.; Bohm, C.; Bohm, J.; Boisvert, V.; Bold, T.; Boldea, V.; Bondarenko, V. G.; Bondioli, M.; Boonekamp, M.; Bordoni, S.; Borer, C.; Borisov, A.; Borissov, G.; Borjanovic, I.; Borroni, S.; Bos, K.; Boscherini, D.; Bosman, M.; Boterenbrood, H.; Bouchami, J.; Boudreau, J.; Bouhova-Thacker, E. V.; Boulahouache, C.; Bourdarios, C.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bozovic-Jelisavcic, I.; Bracinik, J.; Braem, A.; Branchini, P.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Braun, H. M.; Brelier, B.; Bremer, J.; Brenner, R.; Bressler, S.; Britton, D.; Brochu, F. M.; Brock, I.; Brock, R.; Brodet, E.; Bromberg, C.; Brooijmans, G.; Brooks, W. K.; Brown, G.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruneliere, R.; Brunet, S.; Bruni, A.; Bruni, G.; Bruschi, M.; Bucci, F.; Buchanan, J.; Buchholz, P.; Buckley, A. G.; Budagov, I. A.; Budick, B.; Büscher, V.; Bugge, L.; Bulekov, O.; Bunse, M.; Buran, T.; Burckhart, H.; Burdin, S.; Burgess, T.; Burke, S.; Busato, E.; Bussey, P.; Buszello, C. P.; Butin, F.; Butler, B.; Butler, J. M.; Buttar, C. M.; Butterworth, J. M.; Byatt, T.; Caballero, J.; Cabrera Urbán, S.; Caforio, D.; Cakir, O.; Calafiura, P.; Calderini, G.; Calfayan, P.; Calkins, R.; Caloba, L. P.; Calvet, D.; Camarri, P.; Cameron, D.; Campana, S.; Campanelli, M.; Canale, V.; Canelli, F.; Canepa, A.; Cantero, J.; Capasso, L.; Capeans Garrido, M. D. M.; Caprini, I.; Caprini, M.; Capua, M.; Caputo, R.; Caramarcu, C.; Cardarelli, R.; Carli, T.; Carlino, G.

2010-12-01

371

Improved ?-? Coincidence Detector For Radioxenon Detection  

SciTech Connect

The Automated Radio-xenon Analyzer/Sampler (ARSA), built by Pacific Northwest National Laboratory (PNNL), can collect and detect several radioxenon isotopes. ARSA is very sensitive to 133Xe, 131mXe, 133mXe and 135Xe due to the compact high efficiency ?-? coincidence detector it uses. For this reason it is an excellent treaty monitoring and environmental sampling device. Although the system is shown to be both robust and reliable, based on several field tests, it is also complex due to a detailed photomultiplier tube gain matching regime. This complexity is a problem from a maintenance and quality assurance/quality control (QA/QC) standpoint. To reduce these issues a simplified ??? coincident detector has been developed. A comparison of three different well detectors has been completed. In addition, a new plastic scintillator gas cell was constructed. The new simplified detector system has been demonstrated to equal or better performance compared with the original ARSA design in spectral resolution and efficiency and significantly easier to setup and calibrate.

Cooper, Matthew W.; Carman, April J.; Hayes, James C.; Heimbigner, Tom R.; Hubbard, Charles W.; Litke, Kevin E.; McIntyre, Justin I.; Morris, Scott J.; Ripplinger, Michael D.; Suarez, Reynold

2005-08-31

372

Gamma ray detector modules  

NASA Technical Reports Server (NTRS)

A radiation detector assembly has a semiconductor detector array substrate of CdZnTe or CdTe, having a plurality of detector cell pads on a first surface thereof, the pads having a contact metallization and a solder barrier metallization. An interposer card has planar dimensions no larger than planar dimensions of the semiconductor detector array substrate, a plurality of interconnect pads on a first surface thereof, at least one readout semiconductor chip and at least one connector on a second surface thereof, each having planar dimensions no larger than the planar dimensions of the interposer card. Solder columns extend from contacts on the interposer first surface to the plurality of pads on the semiconductor detector array substrate first surface, the solder columns having at least one solder having a melting point or liquidus less than 120 degrees C. An encapsulant is disposed between the interposer circuit card first surface and the semiconductor detector array substrate first surface, encapsulating the solder columns, the encapsulant curing at a temperature no greater than 120 degrees C.

Capote, M. Albert (Inventor); Lenos, Howard A. (Inventor)

2009-01-01

373

The Belle detector  

NASA Astrophysics Data System (ADS)

The Belle detector was designed and constructed to carry out quantitative studies of rare B-meson decay modes with very small branching fractions using an asymmetric e +e - collider operating at the ?(4S) resonance, the KEK-B-factory. Such studies require data samples containing ˜10 7 B-meson decays. The Belle detector is configured around a 1.5 T superconducting solenoid and iron structure surrounding the KEK-B beams at the Tsukuba interaction region. B-meson decay vertices are measured by a silicon vertex detector situated just outside of a cylindrical beryllium beam pipe. Charged particle tracking is performed by a wire drift chamber (CDC). Particle identification is provided by d E/d x measurements in CDC, aerogel threshold Cherenkov counter and time-of-flight counter placed radially outside of CDC. Electromagnetic showers are detected in an array of CsI( Tl) crystals located inside the solenoid coil. Muons and K L mesons are identified by arrays of resistive plate counters interspersed in the iron yoke. The detector covers the ? region extending from 17° to 150°. The part of the uncovered small-angle region is instrumented with a pair of BGO crystal arrays placed on the surfaces of the QCS cryostats in the forward and backward directions. Details of the design and development works of the detector subsystems, which include trigger, data acquisition and computer systems, are described. Results of performance of the detector subsystems are also presented.

Abashian, A.; Gotow, K.; Morgan, N.; Piilonen, L.; Schrenk, S.; Abe, K.; Adachi, I.; Alexander, J. P.; Aoki, K.; Behari, S.; Doi, Y.; Enomoto, R.; Fujii, H.; Fujita, Y.; Funahashi, Y.; Haba, J.; Hamasaki, H.; Haruyama, T.; Hayashi, K.; Higashi, Y.; Hitomi, N.; Igarashi, S.; Igarashi, Y.; Iijima, T.; Ikeda, Hirokazu; Ikeda, Hitomi; Itoh, R.; Iwai, M.; Iwasaki, H.; Iwasaki, Y.; Joo, K. K.; Kasami, K.; Katayama, N.; Kawai, M.; Kichimi, H.; Kobayashi, T.; Koike, S.; Kondo, Y.; Lee, M. H.; Makida, Y.; Manabe, A.; Matsuda, T.; Murakami, T.; Nagayama, S.; Nakao, M.; Nozaki, T.; Ogawa, K.; Ohkubo, R.; Ohnishi, Y.; Ozaki, H.; Sagawa, H.; Saito, M.; Sakai, Y.; Sasaki, T.; Sato, N.; Sumiyoshi, T.; Suzuki, J.; Suzuki, J. I.; Suzuki, S.; Takasaki, F.; Tamai, K.; Tanaka, M.; Tatomi, T.; Tsuboyama, T.; Tsukada, K.; Tsukamoto, T.; Uehara, S.; Ujiie, N.; Uno, S.; Yabsley, B.; Yamada, Y.; Yamaguchi, H.; Yamaoka, H.; Yamaoka, Y.; Yamauchi, M.; Yoshimura, Y.; Zhao, H.; Abe, R.; Iwai, G.; Kawasaki, T.; Miyata, H.; Shimada, K.; Takahashi, S.; Tamura, N.; Abe, K.; Hanada, H.; Nagamine, T.; Nakajima, M.; Nakajima, T.; Narita, S.; Sanpei, M.; Takayama, T.; Ueki, M.; Yamaga, M.; Yamaguchi, A.; Ahn, B. S.; Kang, J. S.; Kim, Hyunwoo; Park, C. W.; Park, H.; Ahn, H. S.; Jang, H. K.; Kim, C. H.; Kim, S. K.; Lee, S. H.; Park, C. S.; Won, E.; Aihara, H.; Higuchi, T.; Kawai, H.; Matsubara, T.; Nakadaira, T.; Tajima, H.; Tanaka, J.; Tomura, T.; Yokoyama, M.; Akatsu, M.; Fujimoto, K.; Hirose, M.; Inami, K.; Ishikawa, A.; Itami, S.; Kani, T.; Matsumoto, T.; Nagai, I.; Okabe, T.; Oshima, T.; Senyo, K.; Sugi, A.; Sugiyama, A.; Suitoh, S.; Suzuki, S.; Tomoto, M.; Yoshida, K.; Akhmetshin, R.; Chang, P.; Chao, Y.; Chen, Y. Q.; Hou, W. S.; Hsu, S. C.; Huang, H. C.; Huang, T. J.; Lee, M. C.; Lu, R. S.; Peng, J. C.; Peng, K. C.; Sahu, S.; Sung, H. F.; Tsai, K. L.; Ueno, K.; Wang, C. C.; Wang, M. Z.; Alimonti, G.; Browder, T. E.; Casey, B. C. K.; Fang, F.; Guler, H.; Jones, M.; Li, Y.; Olsen, S. L.; Peters, M.; Rodriguez, J. L.; Rosen, M.; Swain, S.; Trabelsi, K.; Varner, G.; Yamamoto, H.; Zheng, Y. H.; An, Q.; Chen, H. F.; Wang, Y. F.; Xu, Z. Z.; Ye, S. W.; Zhang, Z. P.; Asai, M.; Asano, Y.; Mori, S.; Stani?, S.; Tsujita, Y.; Zhang, J.; Žontar, D.; Aso, T.; Aulchenko, V.; Beiline, D.; Bondar, A.; Dneprovsky, L.; Eidelman, S.; Garmash, A.; Kuzmin, A.; Romanov, L.; Root, N.; Shwartz, B.; Sidorov, A.; Sidorov, V.; Usov, Y.; Zhilich, V.; Bakich, A. M.; Peak, L. S.; Varvell, K. E.; Banas, E.; Bozek, A.; Jalocha, P.; Kapusta, P.; Natkaniec, Z.; Ostrowicz, W.; Palka, H.; Rozanka, M.; Rybicki, K.; Behera, P. K.; Mohapatra, A.; Satapathy, M.; Chang, Y. H.; Chen, H. S.; Dong, L. Y.; Li, J.; Liu, H. M.; Mao, Z. P.; Yu, C. X.; Zhang, C. C.; Zhang, S. Q.; Zhao, Z. G.; Zheng, Z. P.; Cheon, B. G.; Choi, Y.; Kim, D. W.; Nam, J. W.; Chidzik, S.; Korotuschenko, K.; Leonidopoulos, C.; Liu, T.; Marlow, D.; Mindas, C.; Prebys, E.; Rabberman, R.; Sands, W.; Wixted, R.; Choi, S.; Dragic, J.; Everton, C. W.; Gordon, A.; Hastings, N. C.; Heenan, E. M.; Moffitt, L. C.; Moloney, G. R.; Moorhead, G. F.; Sevior, M. E.; Taylor, G. N.; Tovey, S. N.; Drutskoy, A.; Kagan, R.; Pakhlov, P.; Semenov, S.; Fukunaga, C.; Suda, R.; Fukushima, M.; Goriletsky, V. I.; Grinyov, B. V.; Lyubinsky, V. R.; Panova, A. I.; Shakhova, K. V.; Shpilinskaya, L. I.; Vinograd, E. L.; Zaslavsky, B. G.; Guo, R. S.; Haitani, F.; Hoshi, Y.; Neichi, K.; Hara, K.; Hara, T.; Hazumi, M.; Hojo, T.; Jackson, D.; Miyake, H.; Nagashima, Y.; Ryuko, J.; Sumisawa, K.; Takita, M.; Yamanaka, T.; Hayashii, H.; Miyabayashi, K.; Noguchi, S.; Hikita, S.; Hirano, H.; Hoshina, K.; Mamada, H.; Nitoh, O.; Okazaki, N.; Yokoyama, T.; Ishino, H.; Ichizawa, S.; Hirai, T.; Kakuno, H.; Kaneko, J.; Nakamura, T.; Ohshima, Y.; Watanabe, Y.; Yanaka, S.; Inoue, Y.; Nakano, E.; Takahashi, T.; Teramoto, Y.; Kang, J. H.; Kim, H. J.; Kim, Heejong; Kwon, Y.-J.; Kawai, H.; Kurihara, E.; Ooba, T.; Suzuki, K.; Unno, Y.; Kawamura, N.; Yuta, H.; Kinoshita, K.; Satpathy, A.; Kobayashi, S.; Kuniya, T.; Murakami, A.; Tsukamoto, T.; Kumar, S.; Singh, J.; Lange, J.; Stock, R.; Matsumoto, S.; Watanabe, M.; Matsuo, H.; Nishida, S.; Nomura, T.; Sakamoto, H.; Sasao, N.; Ushiroda, Y.; Nagasaka, Y.; Tanaka, Y.; Ogawa, S.; Shibuya, H.; Hanagaki, K.; Okuno, S.; Shen, D. Z.; Yan, D. S.; Yin, Z. W.; Tan, N.; Wang, C. H.; Yamaki, T.; Yamashita, Y.

2002-02-01

374

Optical lumped element microwave kinetic inductance detectors  

NASA Astrophysics Data System (ADS)

Microwave Kinetic Inductance Detectors, or MKIDs, have proven to be a powerful cryogenic detector technology due to their sensitivity and the ease with which they can be multiplexed into large arrays. An MKID is an energy sensor based on a photon-variable superconducting inductance in a lithographed microresonator. It is capable of functioning as both a photon detector across the electromagnetic spectrum and a particle detector. We have recently demonstrated the world's first photon-counting, energy-resolving, ultraviolet, optical, and near infrared MKID focal plane array in the ARCONS camera at the Palomar 200" telescope. Optical Lumped Element (OLE) MKID arrays have significant advantages over semiconductor detectors such as charge coupled devices (CCDs). They can count individual photons with essentially no false counts and determine the energy (to a few percent) and arrival time (to ?1?s) of every photon, with good quantum efficiency. Initial devices were degraded by substrate events from photons passing through the Titanium Nitride (TiN) material of the resonator and being absorbed in the substrate. Recent work has eliminated this issue, with a solution found to be increasing the thickness of the TiN resonator from 20 to 60 nm.

Marsden, Danica; Mazin, Benjamin A.; Bumble, Bruce; Meeker, Seth; O'Brien, Kieran; McHugh, Sean; Strader, Matthew; Langman, Eric

2012-07-01

375

Detector analysis for shallow water active sonar  

NASA Astrophysics Data System (ADS)

SPAWAR Systems Center-San Diego, in concert with the Office of Naval Research (ONR) and Defense Advanced Research Projects Agency (DARPA) has designed and built a proof-of-concept broadband biomimetic sonar. This proof-of-concept sonar emulates a dolphin biosonar system; emitted broadband signals approximate the frequency and time domain characteristics of signals produced by echolocating dolphins, the receive system is spatially modeled after the binaural geometry of the dolphin, and signal processing algorithms incorporate sequential integration of aspect varying returns. As with any sonar, object detection in shallow water while maintaining an acceptable false alarm rate is an important problem. A comprehensive parametric analysis of detection algorithms is presented, focusing primarily on two detector strategies: a matched filter and a spectral detector. The spectral detector compares the ratio of in-band to out-of-band power, and thus functions something like a phase-incoherent matched filter. This computationally efficient detector is shown to perform well with high proportional bandwidth signals. The detector (either matched filter or spectral) is coupled with an alpha-beta tracker which maintains a running noise estimate and calculates signal excess above the estimated noise level which is compared to a fixed threshold.

Pastore, Thomas J.; Phillips, Michael E.

2002-11-01

376

Charged-coupled detector sky surveys.  

PubMed Central

Sky surveys have played a fundamental role in advancing our understanding of the cosmos. The current pictures of stellar evolution and structure and kinematics of our Galaxy were made possible by the extensive photographic and spectrographic programs performed in the early part of the 20th century. The Palomar Sky Survey, completed in the 1950s, is still the principal source for many investigations. In the past few decades surveys have been undertaken at radio, millimeter, infrared, and x-ray wavelengths; each has provided insights into new astronomical phenomena (e.g., quasars, pulsars, and the 3 degrees cosmic background radiation). The advent of high quantum efficiency, linear solid-state devices, in particular charged-coupled detectors, has brought about a revolution in optical astronomy. With the recent development of large-format charged-coupled detectors and the rapidly increasing capabilities of data acquisition and processing systems, it is now feasible to employ the full capabilities of electronic detectors in projects that cover an appreciable fraction of the sky. This talk reviews the first "large scale" charged-coupled detector survey. This program, designed to detect very distant quasars, reveals the powers and limitations of charged-coupled detector surveys. PMID:11607431

Schneider, D P

1993-01-01

377

Trends and new developments in gaseous detectors  

NASA Astrophysics Data System (ADS)

Almost one century ago the method of particle detection with gaseous detectors was invented. Since then they have been exploited successfully in many experiments using a wide variety of different applications. The development is still going on today. The underlying working principles are today well understood and with the help of modern simulation techniques, new configurations can be easily examined and optimized before a first experimental test. Traditional wire chamber ensembles demonstrate that they are still up to date and are well prepared to meet also the challenges of LHC. Applications will be discussed using TPCs in high multiplicity environments with standard Multi-Wire Proportional Chamber (MWPC) as readout as well as drift tubes in a muon spectrometer for a Large Hardron Collider (LHC) experiment. Triggered by the evolving printed circuit technology, a new generation of gaseous detectors with very high position resolution and rate capability has emerged. Two representatives (MICROMEGAS, GEM) have proved their reliability in various experiments and are promising candidates for future projects. Performance and results will be discussed for these detectors. Furthermore, achievements in RPC-based detectors will be discussed. The standard Trigger RPC is a reliable low-cost semi-industrial manufactured device with good time resolution. Thin gap RPCs (Multigap-, and High Rate Timing RPC) show very fast signal response at high efficiency and significantly increased rate capability and will be applied in TOF detectors.

Hoch, M.

378

Direct digital conversion detector technology  

NASA Astrophysics Data System (ADS)

Future imaging sensors for the aerospace and commercial video markets will depend on low cost, high speed analog-to-digital (A/D) conversion to efficiently process optical detector signals. Current A/D methods place a heavy burden on system resources, increase noise, and limit the throughput. This paper describes a unique method for incorporating A/D conversion right on the focal plane array. This concept is based on Sigma-Delta sampling, and makes optimum use of the active detector real estate. Combined with modern digital signal processors, such devices will significantly increase data rates off the focal plane. Early conversion to digital format will also decrease the signal susceptibility to noise, lowering the communications bit error rate. Computer modeling of this concept is described, along with results from several simulation runs. A potential application for direct digital conversion is also reviewed. Future uses for this technology could range from scientific instruments to remote sensors, telecommunications gear, medical diagnostic tools, and consumer products.

Mandl, William J.; Fedors, Richard

1995-06-01

379

Progress in semiconductor drift detectors  

SciTech Connect

Progress in testing semiconductor drift detectors is reported. Generally better position and energy resolutions were obtained than resolutions published previously. The improvement is mostly due to new electronics better matched to different detectors. It is shown that semiconductor drift detectors are becoming versatile and reliable detectors for position and energy measurements.

Rehak, P.; Walton, J.; Gatti, E.; Longoni, A.; Sanpietro, M.; Kemmer, J.; Dietl, H.; Holl, P.; Klanner, R.; Lutz, G.

1985-01-01

380

The Bugey 3 neutrino detector  

NASA Astrophysics Data System (ADS)

The Bugey 3 experiment, designed to measure oscillations of reactor neutrinos, has used 3 identical detection modules, each of 600 liters, filled with a new 6Li-loaded liquid scintillator. These modules were located in two shielding bunkers, respectively 15 and 40 m away from the reactor core. We describe here the mechanical characteristics of these modules, their shielding, the associated electronics, the trigger, the acquisition systems, the calibration and monitoring of these detectors, and the Monte Carlo simulations of their response to particles. We conclude on the overall performance of this new detection technique which has allowed the recording of 120000 neutrino interactions with good neutron efficiency (49%), low background (2.5 evts/hr) and good energy resolution (4% at 4.4 MeV).

Abbes, M.; Achkar, B.; Ait-Boubker, S.; Aleksan, R.; Avenier, M.; Bagieu, G.; Ballansat, J.; Barnoux, Ch.; Bazzoli, R.; Berger, J.; Bermond, M.; Besson, P.; Billault, M.; Boucher, J.; Bouchez, J.; Bouriant, M.; Brissot, R.; Camberlin, B.; Cavaignac, J. F.; Charvin, Ph.; Collot, J.; Commerçon, A.; Cousinou, M.-C.; Cussonneau, J. P.; Daguin-Moynot, G.; Declais, Y.; Desanlis, Th.; Dubois, J.-M.; Dufour, Y.; Farrache, G.; Favier, J.; Gally, Y.; Garciaz, F.; Giacobone, L.; Guerre-Chaley, B.; Jobez, J.-P.; Jourde, D.; Kajfasz, E.; de Kerret, H.; Koang, D. H.; Lefièvre, B.; Léon, F.; Lesquoy, E.; Mallet, J.; Menthe, A.; Metref, A.; Mullié, J.; Nagy, E.; Obolensky, M.; Ollive, P.; Oriboni, A.; Pessard, H.; Pierre, F.; Poinsignon, J.; Potheau, R.; Provasi, R.; Stutz, A.; Thion, J.; Thomas, J.-F.; Wuthrick, J. P.

1996-02-01

381

Development of high gain GEM detectors  

E-print Network

We describe systematic measurements carried out with single and double GEM detectors with printed circuit readout. The maximum safe operating gain has been measured at increasing radiation flux and under exposure to heavily ionizing tracks. Detection efficiency, localization accuracy and cluster size have been measured in a minimum ionizing particle beam. With a suitably configured readout electrode, fast, two-dimensional localization of radiation is demonstrated. (15 refs).

Bressan, A; Sauli, Fabio; Mörmann, D

2000-01-01

382

Solid-state single-photon detectors  

Microsoft Academic Search

This paper reviews the state of the art of some new photon-counting detectors. We measured the performance of various commercial silicon, germanium, and InGaAs\\/InP single-photon avalanche diodes (SPADs) in the 0.8- to 1.55-micrometer wavelength range. Optimized silicon devices reach 70% quantum efficiency at 800 nm and can work up to 1.1 micrometer. However, germanium and InGaAs SPADs are sensitive up

Franco Zappa; Andrea L. Lacaita; Sergio D. Cova; Piergiorgio G. Lovati

1996-01-01

383

Microchannel Plate Imaging Detectors for the Ultraviolet  

NASA Technical Reports Server (NTRS)

There has been significant progress over the last few years in the development of technologies for microchannel plate imaging detectors in the Ultraviolet (UV). Areas where significant developments have occurred include enhancements of quantum detection efficiency through improved photocathodes, advances in microchannel plate performance characteristics, and development of high performance image readout techniques. The current developments in these areas are summarized, with their applications in astrophysical instrumentation.

Siegmund, O. H. W.; Gummin, M. A.; Stock, J.; Marsh, D.

1992-01-01

384

Two dimensional and linear scintillation detectors for fast neutron imaging — comparative analysis  

NASA Astrophysics Data System (ADS)

The paper was aimed to compare performance capabilities of two types of scintillation detectors commonly used for fast neutron imaging: two dimensional and linear ones. Best-case values of quantum efficiency, spatial resolution and capacity were estimated for detectors with plastic converter-screen in case of 14 MeV neutrons. For that there were examined nuclear reactions produced in converter-screen by fast neutrons, spatial distributions of energy release of emerged charged particles and amplitude distributions of scintillations generated by these particles. The paper shows that the efficiency of the linear detector is essentially higher and this detector provides potentially better spatial resolution in comparison with the two dimensional detector. But, the two dimensional detector surpasses the linear one in capacity. The presented results can be used for designing radiographic fast neutron detectors with organic scintillators.

Mikerov, V. I.; Koshelev, A. P.; Ozerov, O. V.; Sviridov, A. S.; Yurkov, D. I.

2014-05-01

385

New technologies for UV detectors  

NASA Technical Reports Server (NTRS)

Several technologies are currently being developed, leading to substantial improvements in the performance of UV detectors or significant reductions in power or weight. Four technologies discussed are (1) thin-film coatings to enhance the UV sensitivity of CCD's, (2) highly innovative magnet assemblies that dramatically reduce weight and result in virtually no external flux, (3) new techniques for curving microchannel plates (MCP's) so that single plates can be used to prevent ion feedback and present highly localized charge clouds to an anode structure, and (4) high-performance alternatives to glass-based MCP's. In item (2), for example, very robust magnets are made out of rare earth materials such as samarium cobalt, and cladding magnets are employed to prevent flux from escaping from the detector into the external environment. These new ultralight magnet assemblies are able to create strong, exceptionally uniform magnetic fields for image intensification and focusing of photoelectrons. The principle advantage of such detectors is the quantum efficiencies of 70-80 percent obtained throughout ultraviolet wavelengths (900-2000 A), the highest of any device. Despite the improvements achieved under item (3), high-performance alternatives to conventional glass-based MCP's potentially offer three distinct new advantages that include (1) a 30-100-fold improvement in dynamic range resulting in correspondingly higher signal-to-noise ratios, (2) the use of pure dielectric and semiconductor materials that will not outgas contaminants that eventually destroy photocathodes, and (3) channels that have constant spacing providing long-ranged order since the plates are made using photolithography techniques from the semiconductor industry. The manufacturers of these advanced-technology MCP's, however, are a couple of years away from actually producing a functioning image intensifier. In contrast to the use of CCD's for optical, ground based observations, there is no single detector technology in the ultraviolet that dominates or is as universally suitable for all applications. Thus, several technological problems, recent advances, and the impact that these new enabling technologies represent for UV applications are addressed.

Joseph, C. L.

1993-01-01

386

High voltage optimization in CdZnTe detectors  

NASA Astrophysics Data System (ADS)

The focus of this paper is to investigate, experimentally and theoretical, the optimum operating bias, in cadmium zinc telluride Cd 0.9Zn0.1Te (CZT) crystals grown using the traveling heater method (THM), required to achieve maximum energy resolution. It was found that 5 mm thick detectors that have low electron trapping, (??)e?1×10-2 cm2/V, operates efficiently at relatively low applied bias, 200 V; while detectors with high electron trapping, (??)e?5×10-3 cm2/V, required relative high voltage: as high as 1000 V for 5 mm thick detectors. Similarly 10 mm thick detectors can be operated at as low as 500 V. Moreover, both charge collection efficiency (CCE) and energy resolution(ER) were found to follow the same trend.

Awadalla, S. A.; Al-Grafi, M.; Iniewski, K.

2014-11-01

387

Development of an advanced antineutrino detector for reactor monitoring  

NASA Astrophysics Data System (ADS)

Here we present the development of a compact antineutrino detector for the purpose of nuclear reactor monitoring, improving upon a previously successful design. This paper will describe the design improvements of the detector which increases the antineutrino detection efficiency threefold over the previous effort. There are two main design improvements over previous generations of detectors for nuclear reactor monitoring: dual-ended optical readout and single volume detection mass. The dual-ended optical readout eliminates the need for fiducialization and increases the uniformity of the detector's optical response. The containment of the detection mass in a single active volume provides more target mass per detector footprint, a key design criteria for operating within a nuclear power plant. This technology could allow for real-time monitoring of the evolution of a nuclear reactor core, independent of reactor operator declarations of fuel inventories, and may be of interest to the safeguards community.

Classen, T.; Bernstein, A.; Bowden, N. S.; Cabrera-Palmer, B.; Ho, A.; Jonkmans, G.; Kogler, L.; Reyna, D.; Sur, B.

2015-01-01

388

Quantitative characterization of electron detectors for transmission electron microscopy  

PubMed Central

A new generation of direct electron detectors for transmission electron microscopy (TEM) promises significant improvement over previous detectors in terms of their modulation transfer function (MTF) and detective quantum efficiency (DQE). However, the performance of these new detectors needs to be carefully monitored in order to optimize imaging conditions and check for degradation over time. We have developed an easy-to-use software tool, FindDQE, to measure MTF and DQE of electron detectors using images of a microscope’s built-in beam stop. Using this software, we have determined the DQE curves of four direct electron detectors currently available: the Gatan K2 Summit, the FEI Falcon I and II, and the Direct Electron DE-12, under a variety of total dose and dose rate conditions. We have additionally measured the curves for the Gatan US4000 and TVIPS F416 scintillator-based cameras. We compare the results from our new method with published curves. PMID:24189638

Ruskin, Rachel S.; Yu, Zhiheng; Grigorieff, Nikolaus

2013-01-01

389

Hexagonal boron nitride epitaxial layers as neutron detector materials  

NASA Astrophysics Data System (ADS)

Micro-strip metal-semiconductor-metal detectors for thermal neutron sensing were fabricated from hexagonal boron nitride (hBN) epilayers synthesized by metal organic chemical vapor deposition. Experimental measurements indicated that the thermal neutron absorption coefficient and length of natural hBN epilayers are about 0.00361 ?m -1 and 277 ?m, respectively. A continuous irradiation with a thermal neutron beam generated an appreciable current response in hBN detectors, corresponding to an effective conversion efficiency approaching ˜80% for absorbed neutrons. Our results indicate that hBN semiconductors would enable the development of essentially ideal solid-state thermal neutron detectors in which both neutron capture and carrier collection are accomplished in the same hBN semiconductor. These solid-state detectors have the potential to replace 3He gas detectors, which faces the very serious issue of 3He gas shortage.

Li, J.; Dahal, R.; Majety, S.; Lin, J. Y.; Jiang, H. X.

2011-10-01

390

Performance Improvement of CZT Detectors by Line Electrode Geometry  

NASA Astrophysics Data System (ADS)

Due to their high efficiency and high energy resolution, applications of CdZnTe (CZT) detectors have spread into many areas such as room temperature detectors. To improve the performance and decrease the effects of hole trapping and crystal non-uniformity, special contact geometries are applied to the detectors, such as Coplanar, 3D pixel, Frisch grid, Capture and so on. In this paper, we introduce a new line electrode geometry to greatly improve CZT detector performance. A line anode collects electrons, while a planar cathode collects holes. Due to the low electric field close to the cathode and the low hole ?? value, this geometry is also a single charge sensitive structure. The calculated energy resolution of a 20 mm x 20 mm x 15 mm detector could be improved up to 1.51% for 662 keV gamma rays. Both simulations and experimental results are presented here.

Zhang, Lan; Zhang, Wei; Li, Jun; Liu, Yanqing; Li, Yulan; Li, Yuanjing; Liu, Yinong; Fu, Jianqiang; Jiang, Hao; Deng, Zhi; Xue, Tao; Luo, Jie

2014-02-01

391

Silicon planar technology for single-photon optical detectors  

Microsoft Academic Search

Design and fabrication of single photon avalanche detector (SPAD) in planar technology is reported. Device design and critical issues in the technology are discussed. Experimental test procedures are described for dark-counting rate, afterpulsing probability, photon timing resolution, and quantum detection efficiency. Low-noise detectors are obtained, with dark counting rates down to 10 c\\/s for devices with 10 ?m diameter, down

Emilio Sciacca; Andrea C. Giudice; Delfo Sanfilippo; Franco Zappa; Salvatore Lombardo; Rosario Consentino; C. Di Franco; M. Ghioni; G. Fallica; G. Bonanno; S. Cova; E. Rimini

2003-01-01

392

Readout chip for the CMS pixel detector upgrade  

NASA Astrophysics Data System (ADS)

For the CMS experiment a new pixel detector is planned for installation during the extended shutdown in winter 2016/2017. Among the changes of the detector modified front end electronics will be used for higher efficiency at peak luminosity of the LHC and faster readout. The first prototype versions of the new readout chip have been designed and produced. The results of qualification and calibration for the new chip are presented in this paper.

Rossini, Marco

2014-11-01

393

Semiconductor radiation detector  

DOEpatents

A semiconductor radiation detector is provided to detect x-ray and light photons. The entrance electrode is segmented by using variable doping concentrations. Further, the entrance electrode is physically segmented by inserting n+ regions between p+ regions. The p+ regions and the n+ regions are individually biased. The detector elements can be used in an array, and the p+ regions and the n+ regions can be biased by applying potential at a single point. The back side of the semiconductor radiation detector has an n+ anode for collecting created charges and a number of p+ cathodes. Biased n+ inserts can be placed between the p+ cathodes, and an internal resistor divider can be used to bias the n+ inserts as well as the p+ cathodes. A polysilicon spiral guard can be implemented surrounding the active area of the entrance electrode or surrounding an array of entrance electrodes.

Patt, Bradley E. (Sherman Oaks, CA); Iwanczyk, Jan S. (Los Angeles, CA); Tull, Carolyn R. (Orinda, CA); Vilkelis, Gintas (Westlake Village, CA)

2002-01-01

394

Johnson Noise Limited Operation of Photovoltaic InSb Detectors.  

PubMed

Photovoltaic indium antimonide detectors have been operated at temperatures detector operating temperature, resistance, and quantum efficiency. Optimization of these parameters in the manufacture of commercially available detectors has led to 5-mum NEP's as low as 10(-15) W. The particular preamplifier is critical to the achievement of Johnson noise limited operation and is described in detail. PMID:20134905

Hall, D N; Aikens, R S; Joyce, R; McCurnin, T W

1975-02-01

395

Radiation detectors as surveillance monitors for IAEA safeguards  

SciTech Connect

Radiation detectors used for personnel dosimetry are examined for use under IAEA Safeguards as monitors to confirm the passage or nonpassage (YES/NO) of plutonium-bearing nuclear material at barrier penetrations declared closed. In this application where backgrounds are ill defined, no advantage is found for a particular detector type because of intrinsic efficiency. Secondary considerations such as complexity, ease of tamper-proofing, and ease of readout are used to recommend specific detector types for routine monitoring and for data-base measurements. Recommendations are made for applications, data acquisition, and instrument development.

Fehlau, P.E.; Dowdy, E.J.

1980-10-01

396

nGEM fast neutron detectors for beam diagnostics  

NASA Astrophysics Data System (ADS)

Fast neutron detectors with a sub-millimetric space resolution are required in order to qualify neutron beams in applications related to magnetically-controlled nuclear fusion plasmas and to spallation sources. A nGEM detector has been developed for the CNESM diagnostic system of the SPIDER NBI prototype for ITER and as beam monitor for fast neutrons lines at spallation sources. The nGEM is a triple GEM gaseous detector equipped with polypropylene and polyethylene layers used to convert fast neutrons into recoil protons through the elastic scattering process. This paper describes the results obtained by testing a nGEM detector at the ISIS spallation source on the VESUVIO beam line. Beam profiles (?x=14.35 mm, ?y=15.75 mm), nGEM counting efficiency (around 10-4 for 3 MeVdetector stability (?4.5%) and the effect of filtering the beam with different type of materials were successfully measured. The x beam profile was compared to the one measured by a single crystal diamond detector. Finally, the efficiency of the detector was simulated exploiting the GEANT4 tool.

Croci, G.; Claps, G.; Cavenago, M.; Dalla Palma, M.; Grosso, G.; Murtas, F.; Pasqualotto, R.; Perelli Cippo, E.; Pietropaolo, A.; Rebai, M.; Tardocchi, M.; Tollin, M.; Gorini, G.

2013-08-01

397

Detector driver systems and photometric estimates for RIMAS  

NASA Astrophysics Data System (ADS)

The Rapid infrared IMAger-Spectrometer (RIMAS) is a rapid gamma-ray burst afterglow instrument that will provide photometric and spectroscopic coverage of the Y, J, H, and K bands. RIMAS separates light into two optical arms, YJ and HK, which allows for simultaneous coverage in two photometric bands. RIMAS utilizes two 2048 x 2048 pixel Teledyne HgCdTe (HAWAII-2RG) detectors along with a Spitzer Legacy Indium- Antimonide (InSb) guiding detector in spectroscopic mode to position and keep the source on the slit. We describe the software and hardware development for the detector driver and acquisition systems. The HAWAII- 2RG detectors simultaneously acquire images using Astronomical Research Cameras, Inc. driver, timing, and processing boards with two C++ wrappers running assembly code. The InSb detector clocking and acquisition system runs on a National Instruments cRIO-9074 with a Labview user interface and clocks written in an easily alterable ASCII file. We report the read noise, linearity, and dynamic range of our guide detector. Finally, we present RIMAS's estimated instrument efficiency in photometric imaging mode (for all three detectors) and expected limiting magnitudes. Our efficiency calculations include atmospheric transmission models, filter models, telescope components, and optics components for each optical arm.

Toy, Vicki L.; Kutyrev, Alexander S.; Lyness, Eric I.; Muench, Marius; Robinson, Frederick D.; Lotkin, Gennadiy N.; Capone, John I.; Veilleux, Sylvain; Moseley, Samuel H.; Gehrels, Neil A.; Vogel, Stuart N.

2014-07-01

398

Bipolar ion detector based on sequential conversion reactions.  

PubMed

This work demonstrates the feasibility of a novel scintillation detector with greater detection efficiency than that of chevron-type microchannel plate (MCP) detectors. The detection mechanism involves sequential conversion reactions induced by ion-surface impacts. Identical detection conditions can be utilized to monitor both positive and negative ions in mass spectrometers. The proposed detector comprises an ion beam guiding device, a negatively biased washer-shaped conversion dynode, and an aluminum-coated scintillation detector. The beam guide changes the electric field around the washer-shaped conversion dynode, and it allows the primary and secondary ions to propagate toward the scintillation phosphor and the conversion dynode, respectively. The detection is achieved by the detection of electron-induced luminescence on a phosphor. The amplification efficiency of this bipolar ion detector increases as the conversion dynode voltage increases. For ions with a mass-to-charge ratio of up to 90 000, the sensitivity of the BID is 1.4-14.4 times that of the MCP. Further improvement of the sensitivity can be achieved by increasing the conversion dynode voltage or the ion acceleration voltage. Results of this study demonstrate that this detector is a promising alternative for efficient ion detection. PMID:17297924

Li, Ming-Hsin; Tsai, Shang-Ting; Chen, Chung-Hsuan; Chen, Chiu Wen; Lee, Yuan Tseh; Wang, Yi-Sheng

2007-02-15

399

Intelligent Detector Design  

SciTech Connect

At a future e+e- linear collider, precision measurements of jets will be required in order to understand physics at and beyond the electroweak scale. Calorimetry will be used with other detectors in an optimal way to reconstruct particle 4-vectors with unprecedented precision. This Particle Flow Algorithm (PFA) approach is seen as the best way to achieve particle mass resolutions from dijet measurements in the range of {approx}30%/{radical}E, resulting in innovative methods for choosing the calorimeter technology and optimizing the detector design.

Graf, Norman; Cassell, Ron; Johnson, Tony; McCormick, Jeremy [Stanford Linear Accelerator Laboratory, Menlo Park, CA 94025 (United States); Magill, Steve; Kuhlmann, Steve [Argonne National Laboratory, Argonne, IL 60439 (United States)

2006-10-27

400

Fissile material detector  

DOEpatents

A detector for fissile materials which provides for integrity monitoring of fissile materials and can be used for nondestructive assay to confirm the presence of a stable content of fissile material in items. The detector has a sample cavity large enough to enable assay of large items of arbitrary configuration, utilizes neutron sources fabricated in spatially extended shapes mounted on the endcaps of the sample cavity, incorporates a thermal neutron filter insert with reflector properties, and the electronics module includes a neutron multiplicity coincidence counter.

Ivanov, Alexander I. (Dubna, RU); Lushchikov, Vladislav I. (Dubna, RU); Shabalin, Eugeny P. (Dubna, RU); Maznyy, Nikita G. (Dubna, RU); Khvastunov, Michael M. (Dubna, RU); Rowland, Mark (Alamo, CA)

2002-01-01

401

Semiconductor neutron detector  

DOEpatents

A neutron detector has a compound of lithium in a single crystal form as a neutron sensor element. The lithium compound, containing improved charge transport properties, is either lithium niobate or lithium tantalate. The sensor element is in direct contact with a monitor that detects an electric current. A signal proportional to the electric current is produced and is calibrated to indicate the neutrons sensed. The neutron detector is particularly useful for detecting neutrons in a radiation environment. Such radiation environment may, e.g. include gamma radiation and noise.

Ianakiev, Kiril D. (Los Alamos, NM); Littlewood, Peter B. (Cambridge, GB); Blagoev, Krastan B. (Arlington, VA); Swinhoe, Martyn T. (Los Alamos, NM); Smith, James L. (Los Alamos, NM); Sullivan, Clair J. (Los Alamos, NM); Alexandrov, Boian S. (Los Alamos, NM); Lashley, Jason Charles (Santa Fe, NM)

2011-03-08

402

The G ERDA muon veto Cherenkov detector  

NASA Astrophysics Data System (ADS)

The GERmanium Detector Array, G ERDA, is a new experiment designed to examine the neutrinoless double beta decay 0??? of 76Ge which has a lifetime of at least 1026 years and a single energy deposition of 2039 keV. To reach the goal of 10-3 background events/( keV kg y), several background reduction techniques like anti-coincidence and pulse shape analysis will be used. Cosmic muons can produce background in form of particles and radioactivity. To reject them, two independent detector systems will be integrated in G ERDA. One of these is a Cherenkov muon veto detector, that uses the water tank around the cryostat in which the crystals will be operated. It is equipped with 66 photomultipliers (PMTs) with 8 in. diameter. The PMT distribution was found via extensive Monte Carlo studies to reach the highest efficiencies for dangerous muons (these are muons that cause an energy deposition of around 2 MeV in the germanium detectors), even though the PMTs cover less than 0.1% of the water tank surface. High efficiencies depend strongly on the amount of detected photons. For this, as many surfaces as possible will be covered with 'VM2000', a highly reflective foil from 3 M. This foil has a high reflectivity in a wide range of wavelength and it also shifts photons from the UV into the optical range. It, more or less, doubles the amount of detectable photons, because the photomultipliers used, have an detection maximum between 370 and 400 nm. Thus, a detection efficiency of 98% should be easily achieved.

Knapp, M.; Grabmayr, P.; Jochum, J.; Lubsandorzhiev, B.; Meierhofer, G.; Ritter, F.; Shaibonov, B.

2009-10-01

403

Absolute calibration of fiber-coupled single-photon detector.  

PubMed

We show a setup for characterising the efficiency of a single-photon-detector absolutely and with a precision better than 1%. Since the setup does not rely on calibrated devices and can be implemented with standard-optic components, it can be realised in any laboratory. Our approach is based on an Erbium-Doped-Fiber-Amplifier (EDFA) radiometer as a primary measurement standard for optical power, and on an ultra-stable source of spontaneous emission. As a proof of principle, we characterise the efficiency of an InGaAs/InP single-photon detector. We verified the correctness of the characterisation with independent measurements. In particular, the measurement of the optical power made with the EDFA radiometer has been compared to that of the Federal Institute of Metrology using a transfer power meter. Our approach is suitable for frequent characterisations of high-efficient single-photon detectors. PMID:25089427

Lunghi, Tommaso; Korzh, Boris; Sanguinetti, Bruno; Zbinden, Hugo

2014-07-28

404

Absolute calibration of fiber-coupled single-photon detector  

E-print Network

We show a setup for characterising the efficiency of a single-photon-detector absolutely and with a precision better of 1%. Since the setup does not rely on calibrated devices and can be implemented with standard-optic components, it can be realised in any laboratory. Our approach is based on an Erbium-Doped-Fiber-Amplifier (EDFA) radiometer as a primary measurement standard for optical power, and on an ultra-stable source of spontaneous emission. As a proof of principle, we characterise the efficiency of an InGaAs/InP single-photon detector. We verified the correctness of the characterisation with independent measurements. In particular, the measurement of the optical power made with the EDFA radiometer has been compared to that of the Swiss Federal Office of Metrology using a transfer power meter. Our approach is suitable for frequent characterisations of high-efficient single-photon detectors.

Tommaso Lunghi; Boris Korzh; Bruno Sanguinetti; Hugo Zbinden

2014-04-14

405

Absolute calibration of fiber-coupled single-photon detector  

E-print Network

We show a setup for characterising the efficiency of a single-photon-detector absolutely and with a precision better of 1%. Since the setup does not rely on calibrated devices and can be implemented with standard-optic components, it can be realised in any laboratory. Our approach is based on an Erbium-Doped-Fiber-Amplifier (EDFA) radiometer as a primary measurement standard for optical power, and on an ultra-stable source of spontaneous emission. As a proof of principle, we characterise the efficiency of an InGaAs/InP single-photon detector. We verified the correctness of the characterisation with independent measurements. In particular, the measurement of the optical power made with the EDFA radiometer has been compared to that of the Swiss Federal Office of Metrology using a transfer power meter. Our approach is suitable for frequent characterisations of high-efficient single-photon detectors.

Lunghi, Tommaso; Sanguinetti, Bruno; Zbinden, Hugo

2014-01-01

406

Fabrication of Pillar-Structured Thermal Neutron Detectors  

SciTech Connect

Pillar detector is an innovative solid state device structure that leverages advanced semiconductor fabrication technology to produce a device for thermal neutron detection. State-of-the-art thermal neutron detectors have shortcomings in achieving simultaneously high efficiency, low operating voltage while maintaining adequate fieldability performance. By using a 3-dimensional silicon PIN diode pillar array filled with isotopic boron 10, ({sup 10}B) a high efficiency device is theoretically possible. The fabricated pillar structures reported in this work are composed of 2 {micro}m diameter silicon pillars with a 4 {micro}m pitch and pillar heights of 6 and 12 {micro}m. The pillar detector with a 12 {micro}m height achieved a thermal neutron detection efficiency of 7.3% at 2V.

Nikolic, R J; Conway, A M; Reinhardt, C E; Graff, R T; Wang, T F; Deo, N; Cheung, C L

2007-11-19

407

The Upgraded D0 detector  

SciTech Connect

The D0 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 D0.

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.; /Buenos Aires U. /Rio de Janeiro, CBPF /Sao Paulo, IFT /Alberta U./Simon Fraser U. /York U., Canada /McGill U. /Beijing, Inst. High Energy Phys. /Hefei, CUST /Andes U., Bogota /Charles U. /Prague, Tech. U. /Prague, Inst. Phys. /San Francisco deQuito U. /Clermont-Ferrand U. /LPSC, Grenoble /Marseille, CPPM /Orsay, LAL /Paris U., VI-VII /DAPNIA, Saclay /Strasbourg, IReS; ,

2005-07-01

408

Neutron detectors made from chemically vapor deposited semiconductors  

SciTech Connect

In this paper, the authors present the results of investigations on the use of semiconductors deposited by chemical vapor deposition (CVD) for the fabrication of neutron detectors. For this purpose, 20 {micro}m thick hydrogenated amorphous silicon (a-Si:H) pin diodes and 100 {micro}m thick polycrystalline diamond resistive detectors were fabricated. The detectors were coupled to a neutron-charged particle converter: a layer of either gadolinium or boron (isotope 10 enriched) deposited by evaporation. They have demonstrated the capability of such neutron detectors to operate at neutron fluxes ranging from 10{sup 1} to 10{sup 6} neutrons/cm{sup 2}.s. The fabrication of large area detectors for neutron counting or cartography through the use of multichannel reading circuits is discussed. The advantages of these detectors include the ability to produce large area detectors at low cost, radiation hardness ({approximately} 4 Mrad for a-Si:H and {approximately} 100 Mrad for diamond), and for diamond, operation at temperatures up to 500 C. These properties enable the use of these devices for neutron detection in harsh environments. Thermal neutron detection efficiency up to 22% and 3% are expected by coupling a-Si:H diodes and diamond detectors to 3 {micro}m thick gadolinium (isotope 157) and 2 {micro}m thick boron layers, respectively.

Foulon, F.; Bergonzo, P.; Brambilla, A.; Jany, C.; Guizard, B.; Marshall, R.D. [CEA/Saclay, Gif-sur-Yvette (France)

1998-12-31

409

Photovoltaic radiation detector element  

DOEpatents

A radiation detector element is formed of a body of semiconductor material, a coating on the body which forms a photovoltaic junction therewith, and a current collector consisting of narrow metallic strips, the aforesaid coating having an opening therein in the edge of which closely approaches but is spaced from the current collector strips.

Agouridis, D.C.

1980-12-17

410

Smoke Detector Technology.  

ERIC Educational Resources Information Center

This manual, one in a series developed for public education, provides information on smoke detector selection, installation, operation, and maintenance. For the prospective buyer, the importance of looking for the seal of a recognized national testing laboratory--such as Underwriters' Laboratories, Inc. (UL)--indicating adequate laboratory testing…

Powell, Pamela, Ed.; Portugill, Jestyn, Ed.

411

Directional gamma detector  

DOEpatents

An improved directional gamma radiation detector has a collector sandwiched etween two layers of insulation of varying thicknesses. The collector and insulation layers are contained within an evacuated casing, or emitter, which releases electrons upon exposure to gamma radiation. Delayed electrons and electrons entering the collector at oblique angles are attenuated as they pass through the insulation layers on route to the collector.

LeVert, Francis E. (Downers Grove, Knoxville, TN); Cox, Samson A. (Downers Grove, IL)

1981-01-01

412

MPD Detector at NICA  

NASA Astrophysics Data System (ADS)

The goal of this article is to give information about the new accelerator complex NICA at JINR, Dubna and especially, to provide overview of the MultiPurpose Detector (MPD) and its subdetectors. The current results of the MPD performance for dileptons, hyperons, hypernuclei and phi-meson are presented.

Yordanova, L.; Vasendina, V.

2014-04-01

413

Sensitive hydrogen leak detector  

DOEpatents

A sensitive hydrogen leak detector system is described which uses passivation of a stainless steel vacuum chamber for low hydrogen outgassing, a high compression ratio vacuum system, a getter operating at 77.5 K and a residual gas analyzer as a quantitative hydrogen sensor. 1 fig.

Myneni, G.R.

1999-08-03

414

Gas Detectors, Volume 1.  

ERIC Educational Resources Information Center

The report contains annotated references on gas detectors compiled from the Defense Documentation Center's data bank. The range of the topics deals with detection of toxic propellants, odors, gas leaks, oxygen, etc. Included with the bibliographic reference are the corporate author-monitoring agency, subject, and title indexes. (Author/JR)

Defense Documentation Center, Alexandria, VA.

415

Ionizations scintillation detectors  

NASA Astrophysics Data System (ADS)

A few references are made to factors which affect the energy resolution of proportional scintillation. The coupling of proportional or primary scintillation devices to photoionization detectors (PIPS chamber) is considered, both in the gas and liquid phases, and using the data available some information is given concerning its expected characteristics of energy, position and time resolution.

Policarpo, A. J. P. L.

416

Leak detector uses ultrasonics  

NASA Technical Reports Server (NTRS)

Probe located on outer wall of vacuum-jacketed fluid lines detects leaks on inner wall. Probe picks up and amplifies vibrations that occur when gas rushes through leak and converts them to audible signal or CRT display. System is considerably simpler to use than helium leak detectors and allows rapid checks to be made as part of routine maintenance.

Heisman, R. M.; Iceland, W. F.; Keir, A. R.

1978-01-01

417

Optical detector calibrator system  

NASA Technical Reports Server (NTRS)

An optical detector calibrator system simulates a source of optical radiation to which a detector to be calibrated is responsive. A light source selected to emit radiation in a range of wavelengths corresponding to the spectral signature of the source is disposed within a housing containing a microprocessor for controlling the light source and other system elements. An adjustable iris and a multiple aperture filter wheel are provided for controlling the intensity of radiation emitted from the housing by the light source to adjust the simulated distance between the light source and the detector to be calibrated. The geared iris has an aperture whose size is adjustable by means of a first stepper motor controlled by the microprocessor. The multiple aperture filter wheel contains neutral density filters of different attenuation levels which are selectively positioned in the path of the emitted radiation by a second stepper motor that is also controlled by the microprocessor. An operator can select a number of detector tests including range, maximum and minimum sensitivity, and basic functionality. During the range test, the geared iris and filter wheel are repeatedly adjusted by the microprocessor as necessary to simulate an incrementally increasing simulated source distance. A light source calibration subsystem is incorporated in the system which insures that the intensity of the light source is maintained at a constant level over time.

Strobel, James P. (Inventor); Moerk, John S. (Inventor); Youngquist, Robert C. (Inventor)

1996-01-01

418

Activation neutron detector  

Microsoft Academic Search

An activation neutron detector made as a moulded and cured composition of a material capable of being neutron-activated is described. The material is selected from a group consisting of at least two chemical elements, a compound of at least two chemical elements and their mixture, each of the chemical elements and their mixture, each of the chemical elements being capable

T. S. Ambardanishvili; M. A. Kolomiitsev; T. Y. Zakharina; V. J. Dundua; N. V. Chikhladze

1976-01-01

419

The Friendship Detector  

ERIC Educational Resources Information Center

After years of using Rube Goldberg-inspired projects to teach concepts of simple machines, the author sought a comparable project to reinforce electricity lessons in his ninth-grade Science and Technology course. The Friendship Detector gives students a chance to design, test, and build a complex circuit with multiple switches and battery-powered…

Cox, Scott

2012-01-01

420

Chemochromic Hydrogen Leak Detectors  

NASA Technical Reports Server (NTRS)

At NASA, hydrogen safety is a key concern for space shuttle processing. Leaks of any level must be quickly recognized and addressed due to hydrogen s lower explosion limit. Chemo - chromic devices have been developed to detect hydrogen gas in several embodiments. Because hydrogen is odorless and colorless and poses an explosion hazard, there is an emerging need for sensors to quickly and accurately detect low levels of leaking hydrogen in fuel cells and other advanced energy- generating systems in which hydrogen is used as fuel. The device incorporates a chemo - chromic pigment into a base polymer. The article can reversibly or irreversibly change color upon exposure to hydrogen. The irreversible pigment changes color from a light beige to a dark gray. The sensitivity of the pigment can be tailored to its application by altering its exposure to gas through the incorporation of one or more additives or polymer matrix. Furthermore, through the incorporation of insulating additives, the chemochromic sensor can operate at cryogenic temperatures as low as 78 K. A chemochromic detector of this type can be manufactured into any feasible polymer part including injection molded plastic parts, fiber-spun textiles, or extruded tapes. The detectors are simple, inexpensive, portable, and do not require an external power source. The chemochromic detectors were installed and removed easily at the KSC launch pad without need for special expertise. These detectors may require an external monitor such as the human eye, camera, or electronic detector; however, they could be left in place, unmonitored, and examined later for color change to determine whether there had been exposure to hydrogen. In one type of envisioned application, chemochromic detectors would be fabricated as outer layers (e.g., casings or coatings) on high-pressure hydrogen storage tanks and other components of hydrogen-handling systems to provide visible indications of hydrogen leaks caused by fatigue failures or other failures in those systems. In another type of envisioned application, chemochromic detectors of this type could be optoelectronically instrumented for monitoring to provide measured digital indications of color changes indicative of the presence of hydrogen.

Roberson, Luke; Captain, Janine; Williams, Martha; Smith, Trent; Tate, LaNetra; Raissi, Ali; Mohajeri, Nahid; Muradov, Nazim; Bokerman, Gary

2009-01-01

421

The SKED: speckle knife edge detector  

NASA Astrophysics Data System (ADS)

The knife edge detector—also known as optical beam deflection—is a simple and robust method of detecting ultrasonic waves using a laser. It is particularly suitable for detection of high frequency surface acoustic waves as the response is proportional to variation of the local tilt of the surface. In the case of a specular reflection of the incident laser beam from a smooth surface, any lateral movement of the reflected beam caused by the ultrasonic waves is easily detected by a pair of photodiodes. The major disadvantage of the knife edge detector is that it does not cope well with optically rough surfaces, those that give a speckled reflection. The optical speckles from a rough surface adversely affect the efficiency of the knife edge detector, because 'dark' speckles move synchronously with 'bright' speckles, and their contributions to the ultrasonic signal cancel each other out. We have developed a new self-adapting sensor which can cope with the optical speckles reflected from a rough surface. It is inelegantly called the SKED—speckle knife edge detector—and like its smooth surface namesake it is simple, cheap, compact, and robust. We describe the theory of its operation, and present preliminary experimental results validating the overall concept and the operation of the prototype device.

Sharpies, S. D.; Light, R. A.; Achamfuo-Yeboah, S. O.; Clark, M.; Somekh, M. G.

2014-06-01

422

Calibration of the Super-Kamiokande Detector  

E-print Network

Procedures and results on hardware level detector calibration in Super-Kamiokande (SK) are presented in this paper. In particular, we report improvements made in our calibration methods for the experimental phase IV in which new readout electronics have been operating since 2008. The topics are separated into two parts. The first part describes the determination of constants needed to interpret the digitized output of our electronics so that we can obtain physical numbers such as photon counts and their arrival times for each photomultiplier tube (PMT). In this context, we developed an in-situ procedure to determine high-voltage settings for PMTs in large detectors like SK, as well as a new method for measuring PMT quantum efficiency and gain in such a detector. The second part describes the modeling of the detector in our Monte Carlo simulation, including in particular the optical properties of its water target and their variability over time. Detailed studies on the water quality are also presented. As a result of this work, we achieved a precision sufficient for physics analysis over a wide energy range (from a few MeV to above a TeV). For example, the charge determination was understood at the 1% level, and the timing resolution was 2.1 nsec at the one-photoelectron charge level and 0.5 nsec at the 100-photoelectron charge level.

K. Abe; Y. Hayato; T. Iida; K. Iyogi; J. Kameda; Y. Kishimoto; Y. Koshio; Ll. Marti; M. Miura; S. Moriyama; M. Nakahata; Y. Nakano; S. Nakayama; Y. Obayashi; H. Sekiya; M. Shiozawa; Y. Suzuki; A. Takeda; Y. Takenaga; H. Tanaka; T. Tomura; K. Ueno; R. A. Wendell; T. Yokozawa; T. J. Irvine; H. Kaji; T. Kajita; K. Kaneyuki; K. P. Lee; Y. Nishimura; K. Okumura; T. McLachlan; L. Labarga; E. Kearns; J. L. Raaf; J. L. Stone; L. R. Sulak; S. Berkman; H. A. Tanaka; S. Tobayama; M. Goldhaber; K. Bays; G. Carminati; W. R. Kropp; S. Mine; A. Renshaw; M. B. Smy; H. W. Sobel; K. S. Ganezer; J. Hill; W. E. Keig; J. S. Jang; J. Y. Kim; I. T. Lim; N. Hong; T. Akiri; J. B. Albert; A. Himmel; K. Scholberg; C. W. Walter; T. Wongjirad; T. Ishizuka; S. Tasaka; J. G. Learned; S. Matsuno; S. N. Smith; T. Hasegawa; T. Ishida; T. Ishii; T. Kobayashi; T. Nakadaira; K. Nakamura; K. Nishikawa; Y. Oyama; K. Sakashita; T. Sekiguchi; T. Tsukamoto; A. T. Suzuki; Y. Takeuchi; K. Huang; K. Ieki; M. Ikeda; T. Kikawa; H. Kubo; A. Minamino; A. Murakami; T. Nakaya; M. Otani; K. Suzuki; S. Takahashi; Y. Fukuda; K. Choi; Y. Itow; G. Mitsuka; M. Miyake; P. Mijakowski; R. Tacik; J. Hignight; J. Imber; C. K. Jung; I. Taylor; C. Yanagisawa; Y. Idehara; H. Ishino; A. Kibayashi; T. Mori; M. Sakuda; R. Yamaguchi; T. Yano; Y. Kuno; S. B. Kim; B. S. Yang; H. Okazawa; Y. Choi; K. Nishijima; M. Koshiba; Y. Totsuka; M. Yokoyama; K. Martens; M. R. Vagins; J. F. Martin; P. de Perio; A. Konaka; M. J. Wilking; S. Chen; Y. Heng; H. Sui; Z. Yang; H. Zhang; Y. Zhenwei; K. Connolly; M. Dziomba; R. J. Wilkes

2013-06-29

423

High-resolution ionization detector and array of such detectors  

DOEpatents

A high-resolution ionization detector and an array of such detectors are described which utilize a reference pattern of conductive or semiconductive material to form interaction, pervious and measurement regions in an ionization substrate of, for example, CdZnTe material. The ionization detector is a room temperature semiconductor radiation detector. Various geometries of such a detector and an array of such detectors produce room temperature operated gamma ray spectrometers with relatively high resolution. For example, a 1 cm.sup.3 detector is capable of measuring .sup.137 Cs 662 keV gamma rays with room temperature energy resolution approaching 2% at FWHM. Two major types of such detectors include a parallel strip semiconductor Frisch grid detector and the geometrically weighted trapezoid prism semiconductor Frisch grid detector. The geometrically weighted detector records room temperature (24.degree. C.) energy resolutions of 2.68% FWHM for .sup.137 Cs 662 keV gamma rays and 2.45% FWHM for .sup.60 Co 1.332 MeV gamma rays. The detectors perform well without any electronic pulse rejection, correction or compensation techniques. The devices operate at room temperature with simple commercially available NIM bin electronics and do not require special preamplifiers or cooling stages for good spectroscopic results.

McGregor, Douglas S. (Ypsilanti, MI); Rojeski, Ronald A. (Pleasanton, CA)

2001-01-16

424

Carbon monoxide detector. [electrochemical gas detector for spacecraft use  

NASA Technical Reports Server (NTRS)

A sensitive carbon monoxide detector, developed specifically for spacecraft use, is described. An instrument range of 0 to 60 ppm CO in air was devised. The fuel cell type detector is used as a highly sensitive electrolysis cell for electrochemically detecting gases. The concept of an electrochemical CO detector is discussed and the CO oxidation behavior in phosphoric and sulfuric acid electrolytes is reported.

Holleck, G. L.; Bradspies, J. L.; Brummer, S. B.; Nelsen, L. L.

1973-01-01

425

Background model for a NaI (Tl) detector devoted to dark matter searches  

NASA Astrophysics Data System (ADS)

NaI (Tl) is a well known high light yield scintillator. Very large crystals can be grown to be used in a wide range of applications. In particular, such large crystals are very good-performing detectors in the search for dark matter, where they have been used for a long time and reported first evidence of the presence of an annual modulation in the detection rate, compatible with that expected for a dark matter signal. In the frame of the ANAIS (Annual modulation with NaI Scintillators) dark matter search project, a large and long effort has been carried out in order to characterize the background of sodium iodide crystals. In this paper we present in detail our background model for a 9.6 kg NaI (Tl) detector taking data at the Canfranc Underground Laboratory (LSC): most of the contaminations contributing to the background have been precisely identified and quantified by different complementary techniques such as HPGe spectrometry, discrimination of alpha particles vs. beta/gamma background by Pulse Shape Analysis (PSA) and coincidence techniques; then, Monte Carlo (MC) simulations using Geant4 package have been carried out for the different contributions. Only a few assumptions are required in order to explain most of the measured background at high energy, supporting the goodness of the proposed model for the present ANAIS prototype whose background is dominated by 40K bulk contamination. At low energy, some non-explained background components are still present and additional work is required to improve background understanding, but some plausible background sources contributing in this range have been studied in this work. Prospects of achievable backgrounds, at low and high energy, for the ANAIS-upgraded detectors, relying on the proposed background model conveniently scaled, are also presented.

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

2012-09-01

426

The Multi-sensor Airborne Radiation Survey (MARS) instrument  

NASA Astrophysics Data System (ADS)

The Multi-sensor Airborne Radiation Survey (MARS) project has developed a new single cryostat detector array design for high purity germanium (HPGe) gama 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, including airborne and maritime operations.

Fast, J. E.; Aalseth, C. E.; Asner, D. M.; Bonebrake, C. A.; Day, A. R.; Dorow, K. E.; Fuller, E. S.; Glasgow, B. D.; Hossbach, T. W.; Hyronimus, B. J.; Jensen, J. L.; Johnson, K. I.; Jordan, D. V.; Morgen, G. P.; Morris, S. J.; Mullen, O. D.; Myers, A. W.; Pitts, W. K.; Rohrer, J. S.; Runkle, R. C.; Seifert, A.; Shergur, J. M.; Stave, S. C.; Tatishvili, G.; Thompson, R. C.; Todd, L. C.; Warren, G. A.; Willett, J. A.; Wood, L. S.

2013-01-01

427

Detection of nitrite by flow injection analysis using a novel paired emitter-detector diode (PEDD) as a photometric detector  

NASA Astrophysics Data System (ADS)

An inexpensive flow injection analysis system for determining low concentration levels of nitrite employing the Griess reagent spectrophotometric method is reported. The novel photometric detector applied within this manifold is a highly sensitive, low cost, miniaturized light emitting diode (LED) based flow detector. This colorimetric detector employs two LEDs, operating one as a light source and the other as a light detector. The emitter LED is forward biased and the detector reverse biased. The emitter and detector LED had a ?max of 530 nm and 623 nm respectively. The emission spectrum of the emitter LED efficiently overlapped with the absorbance spectrum of 9 µM NO2 and Griess reagent complex. A sim