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Sample records for purity germanium detectors

  1. The GALATEA test-facility for High Purity Germanium Detectors

    CERN Document Server

    Abt, I; Doenmez, B; Garbini, L; Irlbeck, S; Majorovits, B; Palermo, M; Schulz, O; Seitz, H; Stelzer, F

    2014-01-01

    GALATEA is a test facility designed to investigate bulk and surface effects in high purity germanium detectors. A vacuum tank houses an infrared screened volume with a cooled detector inside. A system of three stages allows an almost complete scan of the detector. The main feature of GALATEA is that there is no material between source and detector. This allows the usage of alpha and beta sources as well as of a laser beam to study surface effects. A 19-fold segmented true-coaxial germanium detector was used for commissioning.

  2. The GALATEA test-facility for high purity germanium detectors

    Science.gov (United States)

    Abt, I.; Caldwell, A.; Dönmez, B.; Garbini, L.; Irlbeck, S.; Majorovits, B.; Palermo, M.; Schulz, O.; Seitz, H.; Stelzer, F.

    2015-05-01

    GALATEA is a test facility designed to investigate bulk and surface effects in high purity germanium detectors. A vacuum tank houses a cold volume with the detector inside. A system of three precision motorized stages allows an almost complete scan of the detector. The main feature of GALATEA is that there is no material between source and detector. This allows the usage of alpha and beta sources to study surface effects. A 19-fold segmented true-coaxial germanium detector was used for commissioning. A first analysis of data obtained with an alpha source is presented here.

  3. The GALATEA test-facility for high purity germanium detectors

    Energy Technology Data Exchange (ETDEWEB)

    Abt, I.; Caldwell, A.; Dönmez, B.; Garbini, L.; Irlbeck, S.; Majorovits, B.; Palermo, M., E-mail: palermo@mpp.mpg.de; Schulz, O.; Seitz, H.; Stelzer, F.

    2015-05-11

    GALATEA is a test facility designed to investigate bulk and surface effects in high purity germanium detectors. A vacuum tank houses a cold volume with the detector inside. A system of three precision motorized stages allows an almost complete scan of the detector. The main feature of GALATEA is that there is no material between source and detector. This allows the usage of alpha and beta sources to study surface effects. A 19-fold segmented true-coaxial germanium detector was used for commissioning. A first analysis of data obtained with an alpha source is presented here.

  4. Characteristics of GRIFFIN high-purity germanium clover detectors

    Science.gov (United States)

    Rizwan, U.; Garnsworthy, A. B.; Andreoiu, C.; Ball, G. C.; Chester, A.; Domingo, T.; Dunlop, R.; Hackman, G.; Rand, E. T.; Smith, J. K.; Starosta, K.; Svensson, C. E.; Voss, P.; Williams, J.

    2016-06-01

    The Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei, GRIFFIN, is a new experimental facility for radioactive decay studies at the TRIUMF-ISAC laboratory. The performance of the 16 high-purity germanium (HPGe) clover detectors that will make up the GRIFFIN spectrometer is reported. The energy resolution, efficiency, timing resolution, crosstalk and preamplifier properties of each crystal were measured using a combination of analog and digital data acquisition techniques. The absolute efficiency and add-back factors are determined for the energy range of 80-3450 keV. The detectors show excellent performance with an average over all 64 crystals of a FWHM energy resolution of 1.89(6) keV and relative efficiency with respect to a 3 in . × 3 in . NaI detector of 41(1)% at 1.3 MeV.

  5. Impurity distribution in high purity germanium crystal and its impact on the detector performance

    Science.gov (United States)

    Wang, Guojian; Amman, Mark; Mei, Hao; Mei, Dongming; Irmscher, Klaus; Guan, Yutong; Yang, Gang

    High-purity germanium crystals were grown in a hydrogen atmosphere using the Czochralski method. The axial and radial distributions of impurities in the crystals were measured by Hall effect and Photo-thermal ionization spectroscopy (PTIS). Amorphous semiconductor contacts were deposited on the germanium crystals to make detectors. Three planar detectors were fabricated from three crystals with different net carrier concentrations (1.7, 7.9 and 10x1010 cm-3). We evaluated the electrical and spectral performance of three detectors. Measurements of gamma-ray spectra from 137Cs, 241Am and 60Co sources demonstrate that the detectors have excellent energy resolution. The relationship between the impurities and detector's energy resolution was analyzed. Keywords: High-purity germanium crystal, High-purity germanium detector This work is supported by DOE grant DE-FG02-10ER46709 and the state of South Dakota..

  6. Performance of bare high-purity germanium detectors in liquid argon for the GERDA experiment

    CERN Document Server

    Heider, Marik Barnabé; Chkvorets, Oleg; Di Vacri, Assunta; Gusev, Konstantin; Schönert, Stefan; Shirchenko, Mark

    2008-01-01

    The GERmanium Detector Array, GERDA, will search for neutrinoless double beta decay in 76Ge at the National Gran Sasso Laboratory of the INFN. Bare high-purity germanium detectors enriched in 76Ge will be submerged in liquid argon serving simultaneously as a shield against external radioactivity and as a cooling medium. In GERDA Phase-I, reprocessed enriched-Ge detectors, which were previously operated by the Heidelberg-Moscow and IGEX collaborations, will be redeployed. Before operating the enriched detectors, tests are performed with non-enriched bare HPGe detectors in the GERDA underground Detector Laboratory to test the Phase-I detector assembly, the detector handling protocols, the refurbishment technology and to study the long-term stability in liquid argon. The leakage currents in liquid argon and liquid nitrogen have been extensively studied under varying gamma irradiation conditions. In total three non-enriched high-purity p-type prototype germanium detectors have been operated successfully. The dete...

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

    Energy Technology Data Exchange (ETDEWEB)

    Blank, B., E-mail: blank@cenbg.in2p3.fr [Centre d' Etudes Nucléaires de Bordeaux Gradignan, UMR 5797, CNRS/IN2P3, Université de Bordeaux, Chemin du Solarium, BP 120, 33175 Gradignan Cedex (France); Souin, J.; Ascher, P.; Audirac, L.; Canchel, G.; Gerbaux, M.; Grévy, S.; Giovinazzo, J.; Guérin, H.; Nieto, T. Kurtukian; Matea, I. [Centre d' Etudes Nucléaires de Bordeaux Gradignan, UMR 5797, CNRS/IN2P3, Université de Bordeaux, Chemin du Solarium, BP 120, 33175 Gradignan Cedex (France); Bouzomita, H.; Delahaye, P.; Grinyer, G.F.; Thomas, J.C. [Grand Accélérateur National d' Ions Lourds, CEA/DSM, CNRS/IN2P3, Bvd Henri Becquerel, BP 55027, F-14076 CAEN Cedex 5 (France)

    2015-03-11

    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 γ-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 online sources have been used. The resulting efficiency calibration reaches the precision needed e.g. for branching ratio measurements of super-allowed β decays for tests of the weak-interaction standard model.

  8. Characterization of segmented large volume, high purity germanium detectors

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-07-01

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

  9. Methods to improve and understand the sensitivity of high purity germanium detectors for searches of rare events

    Energy Technology Data Exchange (ETDEWEB)

    Volynets, Oleksandr

    2012-07-27

    Observation of neutrinoless double beta-decay could answer fundamental questions on the nature of neutrinos. High purity germanium detectors are well suited to search for this rare process in germanium. Successful operation of such experiments requires a good understanding of the detectors and the sources of background. Possible background sources not considered before in the presently running GERDA high purity germanium detector experiment were studied. Pulse shape analysis using artificial neural networks was used to distinguish between signal-like and background-like events. Pulse shape simulation was used to investigate systematic effects influencing the efficiency of the method. Possibilities to localize the origin of unwanted radiation using Compton back-tracking in a granular detector system were examined. Systematic effects in high purity germanium detectors influencing their performance have been further investigated using segmented detectors. The behavior of the detector response at different operational temperatures was studied. The anisotropy effects due to the crystallographic structure of germanium were facilitated in a novel way to determine the orientation of the crystallographic axes.

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

    Science.gov (United States)

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

    2014-11-01

    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.

  11. A prototype High Purity Germanium detector for high resolution gamma-ray spectroscopy at high count rates

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, R.J., E-mail: rjcooper@lbl.gov [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Amman, M.; Luke, P.N. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Vetter, K. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Department of Nuclear Engineering, University of California, Berkeley, CA 94720 (United States)

    2015-09-21

    Where energy resolution is paramount, High Purity Germanium (HPGe) detectors continue to provide the optimum solution for gamma-ray detection and spectroscopy. Conventional large-volume HPGe detectors are typically limited to count rates on the order of ten thousand counts per second, however, limiting their effectiveness for high count rate applications. To address this limitation, we have developed a novel prototype HPGe detector designed to be capable of achieving fine energy resolution and high event throughput at count rates in excess of one million counts per second. We report here on the concept, design, and initial performance of the first prototype device.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-05-21

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-02-18

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

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

    CERN Document Server

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

    2012-01-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-01-01

    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.

  16. Gamma-ray observations of SN 1987A with an array of high-purity germanium detectors

    Science.gov (United States)

    Sandie, W. G.; Nakano, G. H.; Chase, L. F., Jr.; Fishman, G. J.; Meegan, C. A.; Wilson, R. B.; Paciesas, W.

    A balloonborne gamma-ray spectrometer comprising an array of high-purity n-type germanium detectors was flown from Alice Springs, Northern Territory, Australia, on May 29 - 30, 1987, 96 days after the observed neutrino pulse. SN 1987A was within the 22-deg field of view for about 3300 s during May 29.9 - 30.3 UT. No excess gamma rays were observed at energies appropriate to the Ni(56) - Co(56) decay chain or from other lines in the energy region from 0.1 to 3.0 MeV. The data imply that there was less than 2.5×10-4 solar masses of Co(56) exposed to the Earth at the time of the observation. Additional balloon-borne observations are planned.

  17. GEANT4 simulation of photo-peak efficiency of small high purity germanium detectors for nuclear power plant applications

    Energy Technology Data Exchange (ETDEWEB)

    Rehman, Shakeel Ur; Mirza, Sikander M. [Department of Physics and Applied Mathematics, Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad 45650 (Pakistan); Mirza, Nasir M., E-mail: nmm@pieas.edu.p [Department of Physics and Applied Mathematics, Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad 45650 (Pakistan); Siddique, Muhammad Tariq [Department of Physics and Applied Mathematics, Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad 45650 (Pakistan)

    2011-01-15

    GEANT4 - based Monte Carlo simulations have been carried out for the determination of photo-peak efficiency of heavily shielded small high purity germanium detector (HPGe) used for monitoring radiation levels in nuclear power plants. The GEANT4 simulated values of HPGe detector efficiency for point as well as for disk sources, for two different values of collimator diameter, have been found in good agreement with the corresponding published results obtained by using the MCNP code. The work has been extended to study the effect of radial displacement of a source relative to a detector on photo-peak efficiency for both point and disk source, and at various values of {gamma}-ray energies. Also the effect of disk source radius on photo-peak efficiency has been studied. Besides the results of different available physics models in GEANT4 have also been compared. The computed values of efficiency for point as well as for disk sources using the Penelope and Livermore physics models have been found correspondingly consistent for various values of {gamma}-ray energies while some differences (e.g., Penelope model yields 6.3% higher values of photo-peak efficiency for E{gamma} = 1.332 MeV, 10 mm collimator diameter) have been observed in the corresponding valued obtained by using the Standard physics model.

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

    Science.gov (United States)

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

    2012-11-01

    The half-life of (18)F has been measured using HPGe detectors with a (137)Cs reference source. The counting ratio of 511 keV γ-rays from (18)F to 622 keV γ-rays from (137)Cs was fitted for the half-life with a weighted least-square method. Uncertainties due to the systematic effects arising from the measurement of a high activity (18)F source were studied in detail. The half-life of (18)F was found to be (109.72±0.19) min. The result is in a good agreement with the recommended value of (109.728±0.019) min evaluated at the Laborotaire National Henri Becquerel (LNHB).

  19. Performance and stability tests of bare high purity germanium detectors in liquid argon for the GERDA experiment

    Energy Technology Data Exchange (ETDEWEB)

    Barnabe Heider, Marik

    2009-05-27

    GERDA will search for neutrinoless double beta decay of {sup 76}Ge by using a novel approach of bare germanium detectors in liquid argon (LAr). Enriched germanium detectors from the previous Heidelberg-Moscow and IGEX experiments have been reprocessed and will be deployed in GERDA Phase-I. At the center of this thesis project is the study of the performance of bare germanium detectors in cryogenic liquids. Identical detector performance as in vacuum cryostats (2.2 keV FWHM at 1.3 MeV) was achieved in cryogenic liquids with a new low-mass detector assembly and contacts. One major result is the discovery of a radiation induced leakage current (LC) increase when operating bare detectors with standard passivation layers in LAr. Charge collection and build-up on the passivation layer were identified as the origin of the LC increase. It was found that diodes without passivation do not exhibit this feature. Three month-long stable operation in LAr at {proportional_to} 5 pA LC under periodic gamma irradiation demonstrated the suitability of the modi ed detector design. Based on these results, all Phase-I detectors were reprocessed without passivation layer and subsequently successfully characterized in LAr in the GERDA underground Detector Laboratory. The mass loss during the reprocessing was {proportional_to}300 g out of 17.9 kg and the exposure above ground {proportional_to} 5 days. This results in a negligible cosmogenic background increase of {proportional_to} 5.10{sup -4} cts/(keV.kg.y) at {sup 76}Ge Q{sub {beta}}{sub {beta}} for {sup 60}Co and {sup 68}Ge. (orig.)

  20. Characterisation of two AGATA asymmetric high purity germanium capsules

    Energy Technology Data Exchange (ETDEWEB)

    Colosimo, S.J., E-mail: sjc@ns.ph.liv.ac.uk [Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Moon, S.; Boston, A.J.; Boston, H.C.; Cresswell, J.R.; Harkness-Brennan, L.; Judson, D.S. [Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Lazarus, I.H. [STFC Daresbury, Daresbury, Warrington WA4 4AD (United Kingdom); Nolan, P.J. [Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Simpson, J. [STFC Daresbury, Daresbury, Warrington WA4 4AD (United Kingdom); Unsworth, C. [Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE (United Kingdom)

    2015-02-11

    The AGATA spectrometer is an array of highly segmented high purity germanium detectors. The spectrometer uses pulse shape analysis in order to track Compton scattered γ-rays to increase the efficiency of nuclear spectroscopy studies. The characterisation of two high purity germanium detector capsules for AGATA of the same A-type has been performed at the University of Liverpool. This work will examine the uniformity of performance of the two capsules, including a comparison of the resolution and efficiency as well as a study of charge collection. The performance of the capsules shows good agreement, which is essential for the efficient operation of the γ-ray tracking array.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-10-01

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

  2. Effect of Advanced Synthetically Enhanced Detector Resolution Algorithm on Specificity and Sensitivity of Portable High Purity Germanium Gamma Detector Spectra

    Science.gov (United States)

    2009-06-01

    with a 50 mm diameter and 30 mm deep Ge crystal and low power Stirling Cooler . The detector is shown in Figure 9. 28 Figure 9. Ortec...recording some characteristics of their average behavior. The common behavior of particles in the physical system is then concluded from the 14...modeling. With increased computational power, Monte Carlo simulations of detector systems have become a complement to experimental detector work

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

    Science.gov (United States)

    Saizu, Mirela Angela

    2016-09-01

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

  4. Extrinsic germanium Blocked Impurity Bank (BIB) detectors

    Science.gov (United States)

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

    1989-01-01

    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.

  5. Using standard calibrated geometries to characterize a coaxial high purity germanium gamma detector for Monte Carlo simulations

    NARCIS (Netherlands)

    van der Graaf, E. R.; Dendooven, P.; Brandenburg, S.

    2014-01-01

    A detector model optimization procedure based on matching Monte Carlo simulations with measurements for two experimentally calibrated sample geometries which are frequently used in radioactivity measurement laboratories results in relative agreement within 5% between simulated and measured efficienc

  6. MAJORANA Collaboration's Experience with Germanium Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Mertens, S. [Lawrence Berkeley National Laboratory (LBNL); Abgrall, N. [Lawrence Berkeley National Laboratory (LBNL); Avignone, III, F. T. [University of South Carolina/Oak Ridge National Laboratory (ORNL); Barabash, A.S. [Institute of Theoretical & Experimental Physics (ITEP), Moscow, Russia; Bertrand, F. E. [Oak Ridge National Laboratory (ORNL); Efremenko, Yuri [University of Tennessee (UTK) and Oak Ridge National Laboratory (ORNL); Galindo-Uribarri, A [Oak Ridge National Laboratory (ORNL); Radford, D. C. [Oak Ridge National Laboratory (ORNL); Romero-Romero, E. [UTK/ORNL; Varner, R. L. [Oak Ridge National Laboratory (ORNL); White, B. R. [Oak Ridge National Laboratory (ORNL); Wilkerson, J. F. [UNC/Triangle Univ. Nucl. Lab, Durham, NC/ORNL; Yu, C.-H. [Oak Ridge National Laboratory (ORNL); Majorana, [MAJORANA Collaboration

    2015-01-01

    The goal of the Majorana Demonstrator project is to search for 0v beta beta decay in Ge-76. Of all candidate isotopes for 0v beta beta, Ge-76 has some of the most favorable characteristics. Germanium detectors are a well established technology, and in searches for 0v beta beta, the high purity germanium crystal acts simultaneously as source and detector. Furthermore, p-type germanium detectors provide excellent energy resolution and a specially designed point contact geometry allows for sensitive pulse shape discrimination. This paper will summarize the experiences the MAJORANA collaboration made with enriched germanium detectors manufactured by ORTEC (R)(R). The process from production, to characterization and integration in MAJORANA mounting structure will be described. A summary of the performance of all enriched germanium detectors will be given.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-07-01

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

  8. Cryogenic readout techniques for germanium detectors

    Energy Technology Data Exchange (ETDEWEB)

    Benato, G. [University of Zurich, (Switzerland); Cattadori, C. [INFN - Milano Bicocca, (Italy); Di Vacri, A. [INFN LNGS, (Italy); Ferri, E. [Universita Milano Bicocca/INFN Milano Bicocca, (Italy); D' Andrea, V.; Macolino, C. [GSSI/INFN LNGS, (Italy); Riboldi, S. [Universita degli Studi di Milano/INFN Milano, (Italy); Salamida, F. [Universita Milano Bicocca/INFN Milano Bicocca, (Italy)

    2015-07-01

    High Purity Germanium detectors are used in many applications, from nuclear and astro-particle physics, to homeland security or environment protection. Although quite standard configurations are often used, with cryostats, charge sensitive amplifiers and analog or digital acquisition systems all commercially available, it might be the case that a few specific applications, e.g. satellites, portable devices, cryogenic physics experiments, etc. also require the development of a few additional or complementary techniques. An interesting case is for sure GERDA, the Germanium Detector Array experiment, searching for neutrino-less double beta decay of {sup 76}Ge at the Gran Sasso National Laboratory of INFN - Italy. In GERDA the entire detector array, composed of semi-coaxial and BEGe naked crystals, is operated suspended inside a cryostat filled with liquid argon, that acts not only as cooling medium and but also as an active shield, thanks to its scintillation properties. These peculiar circumstances, together with the additional requirement of a very low radioactive background from all the materials adjacent to the detectors, clearly introduce significant constraints on the design of the Ge front-end readout electronics. All the Ge readout solutions developed within the framework of the GERDA collaboration, for both Phase I and Phase II, will be briefly reviewed, with their relative strength and weakness compared together and with respect to ideal Ge readout. Finally, the digital processing techniques developed by the GERDA collaboration for energy estimation of Ge detector signals will be recalled. (authors)

  9. Pulse shapes and surface effects in segmented germanium detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lenz, Daniel

    2010-03-24

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

  10. Electromechanically cooled germanium radiation detector system

    Science.gov (United States)

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

    1999-02-01

    We have successfully developed and fielded an electromechanically cooled germanium radiation detector (EMC-HPGe) at Lawrence Livermore National Laboratory (LLNL). This detector system was designed to provide optimum energy resolution, long lifetime, and extremely reliable operation for unattended and portable applications. For most analytical applications, high purity germanium (HPGe) detectors are the standard detectors of choice, providing an unsurpassed combination of high energy resolution performance and exceptional detection efficiency. Logistical difficulties associated with providing the required liquid nitrogen (LN) for cooling is the primary reason that these systems are found mainly in laboratories. The EMC-HPGe detector system described in this paper successfully provides HPGe detector performance in a portable instrument that allows for isotopic analysis in the field. It incorporates a unique active vibration control system that allows the use of a Sunpower Stirling cycle cryocooler unit without significant spectral degradation from microphonics. All standard isotopic analysis codes, including MGA and MGA++ [1], GAMANL [2], GRPANL [3]and MGAU [4], typically used with HPGe detectors can be used with this system with excellent results. Several national and international Safeguards organisations including the International Atomic Energy Agency (IAEA) and U.S. Department of Energy (DOE) have expressed interest in this system. The detector was combined with custom software and demonstrated as a rapid Field Radiometric Identification System (FRIS) for the U.S. Customs Service [5]. The European Communities' Safeguards Directorate (EURATOM) is field-testing the first Safeguards prototype in their applications. The EMC-HPGe detector system design, recent applications, and results will be highlighted.

  11. Active noise canceling system for mechanically cooled germanium radiation detectors

    Science.gov (United States)

    Nelson, Karl Einar; Burks, Morgan T

    2014-04-22

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-07-07

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

  13. Front End Spectroscopy ASIC for Germanium Detectors

    Science.gov (United States)

    Wulf, Eric

    Large-area, tracking, semiconductor detectors with excellent spatial and spectral resolution enable exciting new access to soft (0.2-5 MeV) gamma-ray astrophysics. The improvements from semiconductor tracking detectors come with the burden of high density of strips and/or pixels that require high-density, low-power, spectroscopy quality readout electronics. CMOS ASIC technologies are a natural fit to this requirement and have led to high-quality readout systems for all current semiconducting tracking detectors except for germanium detectors. The Compton Spectrometer and Imager (COSI), formerly NCT, at University of California Berkeley and the Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) at Goddard Space Flight Center utilize germanium cross-strip detectors and are on the forefront of NASA's Compton telescope research with funded missions of long duration balloon flights. The development of a readout ASIC for germanium detectors would allow COSI to replace their discrete electronics readout and would enable the proposed Gamma-Ray Explorer (GRX) mission utilizing germanium strip-detectors. We propose a 3-year program to develop and test a germanium readout ASIC to TRL 5 and to integrate the ASIC readout onto a COSI detector allowing a TRL 6 demonstration for the following COSI balloon flight. Our group at NRL led a program, sponsored by another government agency, to produce and integrate a cross-strip silicon detector ASIC, designed and fabricated by Dr. De Geronimo at Brookhaven National Laboratory. The ASIC was designed to handle the large (>30 pF) capacitance of three 10 cm^2 detectors daisy-chained together. The front-end preamplifier, selectable inverter, shaping times, and gains make this ASIC compatible with a germanium cross-strip detector as well. We therefore have the opportunity and expertise to leverage the previous investment in the silicon ASIC for a new mission. A germanium strip detector ASIC will also require precise timing of the signals at

  14. Discrimination of nuclear and electronic recoil events using plasma effect in germanium detectors

    Science.gov (United States)

    Wei, W.-Z.; Liu, J.; Mei, D.-M.

    2016-07-01

    We report a new method of using the plasma time difference, which results from the plasma effect, between the nuclear and electronic recoil events in high-purity germanium detectors to distinguish these two types of events in the search for rare physics processes. The physics mechanism of the plasma effect is discussed in detail. A numerical model is developed to calculate the plasma time for nuclear and electronic recoils at various energies in germanium detectors. It can be shown that under certain conditions the plasma time difference is large enough to be observable. The experimental aspects in realizing such a discrimination in germanium detectors is discussed.

  15. Discrimination of nuclear and electronic recoil events using plasma effect in germanium detectors

    CERN Document Server

    Wei, W -Z; Mei, D -M

    2016-01-01

    We report a new method of using the plasma time difference, which results from the plasma effect, between the nuclear and electronic recoil events in high-purity germanium detectors to distinguish these two types of events in the search for rare physics processes. The physics mechanism of the plasma effect is discussed in detail. A numerical model is developed to calculate the plasma time for nuclear and electronic recoils at various energies in germanium detectors. It can be shown that under certain conditions the plasma time difference is large enough to be observable. The experimental aspects in realizing such a discrimination in germanium detectors is discussed.

  16. Phonon Quasidiffusion in Cryogenic Dark Matter Search Large Germanium Detectors

    CERN Document Server

    Leman, S W; McCarthy, K A; Pyle, M; Resch, R; Sadoulet, B; Sundqvist, K M; Brink, P L; Cherry, M; Silva, E Do Couto E; Figueroa-Feliciano, E; Mirabolfathi, N; Serfass, B; Tomada, A

    2011-01-01

    We present results on quasidiffusion studies in large, 3 inch diameter, 1 inch thick [100] high purity germanium crystals, cooled to 50 mK in the vacuum of a dilution refrigerator, and exposed with 59.5 keV gamma-rays from an Am-241 calibration source. We compare data obtained in two different detector types, with different phonon sensor area coverage, with results from a Monte Carlo. The Monte Carlo includes phonon quasidiffusion and the generation of phonons created by charge carriers as they are drifted across the detector by ionization readout channels.

  17. Sensitivity comparison of intrinsic germanium detectors with various efficiencies

    Energy Technology Data Exchange (ETDEWEB)

    Buker, L.M.L.

    1990-12-01

    Scientists today are being asked to measure concentrations of radionuclides at increasingly lower levels. This creates a demand for better resolution detectors with larger efficiencies that can provide the necessary sensitivity to accurately determine low levels of radioactivity. This study has acquired a large volume of empirical data for a wide range of relative efficiency germanium detectors. The purpose was to determine the sensitivity of various efficiency high-purity (P-type) germanium detectors produced by a single manufacturer. Selecting efficiency as the only variable and essentially all other variables remaining constant narrowed the field of detectors to 30. This investigation compares the response for the lower limit of detection (LLD), figure-of-merit (FOM), and minimum detectable activity (MDA) versus efficiency. In addition to the efficiency, the resolution, background, peak-to-Compton (P/C), and crystal shape of a p-type detector are of particular importance when considering the parameters of a detectors performance. A concise summary of the results is that the detector of choice for low energy measurements would be a 25% detector with resolution better than 1.8 keV FWHM for the 1.332 keV energy of Co-60. The detector of choice for energy levels greater than 500 keV would be a high efficiency low background detector. If the entire energy range is of interest, then a 70% low background detector with a high P/C and a resolution better than 1.9 keV would yield the lowest MDA and assure the most efficient counting times. 9 refs., 25 figs., 6 tabs.

  18. Surface purity control during XMASS detector refurbishment

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Kazuyoshi, E-mail: kenkou@icrr.u-tokyo.ac.jp [Kamioka observatory, Institute for Cosmic Ray Research, the University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu, 506-1205 (Japan); Kavl Institute for the Physics and Mathematics of the Universe (WPI), the University of Tokyo, Kashiwa, Chiba, 277-8582 (Japan)

    2015-08-17

    The XMASS project aims at detecting dark matter, pp and {sup 7}Be solar neutrinos, and neutrino less double beta decay using large volume of pure liquid xenon. The first physics target of the XMASS project is to detect dark matter with 835 kg liquid xenon. After the commissioning runs, XMASS detector was refurbished to minimize the background contribution mainly from PMT sealing material and we restarted data taking in November 2013. We report how we control surface purity, especially how we prevent radon daughter accumulation on the detector copper surface, during XMASS detector refurbishment. The result and future plan of XMASS are also reported.

  19. HEROICA: an underground facility for the fast screening of germanium detectors

    Science.gov (United States)

    Andreotti, E.; Garfagnini, A.; Maneschg, W.; Barros, N.; Benato, G.; Brugnera, R.; Costa, F.; Falkenstein, R.; Guthikonda, K. K.; Hegai, A.; Hemmer, S.; Hult, M.; Jänner, K.; Kihm, T.; Lehnert, B.; Liao, H.; Lubashevskiy, A.; Lutter, G.; Marissens, G.; Modenese, L.; Pandola, L.; Reissfelder, M.; Sada, C.; Salathe, M.; Schmitt, C.; Schulz, O.; Schwingenheuer, B.; Turcato, M.; Ur, C.; von Sturm, K.; Wagner, V.; Westermann, J.

    2013-06-01

    HEROICA (Hades Experimental Research Of Intrinsic Crystal Appliances) is an infrastructure to characterize germanium detectors and has been designed and constructed at the HADES Underground Research Laboratory, located in Mol (Belgium). Thanks to the 223 m overburden of clay and sand, the muon flux is lowered by four orders of magnitude. This natural shield minimizes the exposure of radio-pure germanium material to cosmic radiation resulting in a significant suppression of cosmogenic activation in the germanium detectors. The project has been strongly motivated by a special production of germanium detectors for the GERDA experiment. GERDA, currently collecting data at the Laboratori Nazionali del Gran Sasso of INFN, is searching for the neutrinoless double beta decay of 76Ge. In the near future, GERDA will increase its mass and sensitivity by adding new Broad Energy Germanium (BEGe) detectors. The production of the BEGe detectors is done at Canberra in Olen (Belgium), located about 30 km from the underground test site. Therefore, HADES is used both for storage of the crystals over night, during diode production, and for the characterization measurements. A full quality control chain has been setup and tested on the first seven prototype detectors delivered by the manufacturer at the beginning of 2012. The screening capabilities demonstrate that the installed setup fulfills a fast and complete set of measurements on the diodes and it can be seen as a general test facility for the fast screening of high purity germanium detectors. The results are of major importance for a future massive production and characterization chain of germanium diodes foreseen for a possible next generation 1-tonne double beta decay experiment with 76Ge.

  20. Measurements of gamma (γ)-emitting radionuclides with a high-purity germanium detector: the methods and reliability of our environmental assessments on the Fukushima 1 Nuclear Power Plant accident.

    Science.gov (United States)

    Mimura, Tetsuro; Mimura, Mari; Komiyama, Chiyo; Miyamoto, Masaaki; Kitamura, Akira

    2014-01-01

    The severe accident of Fukushima 1 Nuclear Power Plant due to the Tohoku Region Pacific Coast Earthquake in 11 March 2011 caused wide contamination and pollution by radionuclides in Fukushima and surrounding prefectures. In the current JPR symposium, a group of plant scientists attempted to examine the impact of the radioactive contamination on wild and cultivated plants. Measurements of gamma (γ) radiation from radionuclides in "Fukushima samples", which we called and collected from natural and agricultural areas in Fukushima prefecture were mostly done with a high-purity Ge detector in the Graduate School of Maritime Sciences, Kobe University. In this technical note, we describe the methods of sample preparation and measurements of radioactivity of the samples and discuss the reliability of our data in regards to the International Atomic Energy Agency (IAEA) Interlaboratory comparisons and proficiency test (IAEA proficiency test).

  1. Crystal growth and detector performance of large size high-purity Ge crystals

    CERN Document Server

    Wang, Guojian; Mei, Hao; Mei, Dongming; Irmscher, Klaus; Guan, Yutong; Yang, Gang

    2015-01-01

    High-purity germanium crystals approximately 12 cm in diameter were grown in a hydrogen atmosphere using the Czochralski method. The dislocation density of the crystals was determined to be in the range of 2000 - 4200 cm-2, which meets a requirement for use as a radiation detector. The axial and radial distributions of impurities in the crystals were measured and are discussed. A planar detector was also fabricated from one of the crystals and then evaluated for electrical and spectral performance. Measurements of gamma-ray spectra from Cs-137 and Am-241 sources demonstrate that the detector has excellent energy resolution.

  2. Germanium detectors and natural radioactivity in food

    Energy Technology Data Exchange (ETDEWEB)

    Garbini, Lucia [Max-Planck-Institut fuer Physik, Muenchen (Germany); Collaboration: GeDet-Collaboration

    2013-07-01

    Potassium is a very important mineral for many physiological processes, like fluid balance, protein synthesis and signal transmission in nerves. Many aliments like raisins, bananas or chocolate contain potassium. Natural potassium contains 0.012% of the radioactive isotope Potassium 40. This isotope decays via β{sup +} decay into a metastable state of Argon 40, which reaches its ground state emitting a gamma of 1460 keV. A commercially produced Germanium detector has been used to measure the energy spectra of different selected food samples. It was calibrated with KCl and potassium contents were extracted. Results verify the high potassium content of commonly recommended food samples. However, the measurement quantitatively differ from the expectations in several cases. One of the most interesting results concerns chocolate bars with different percentages of cacao.

  3. Characterisation of a Broad Energy Germanium (BEGe) detector

    Energy Technology Data Exchange (ETDEWEB)

    Barrientos, D., E-mail: diego_barrientos@usal.es [Laboratorio de Radiaciones Ionizantes, University of Salamanca (Spain); Boston, A.J.; Boston, H.C. [Nuclear Physics Group, University of Liverpool (United Kingdom); Quintana, B.; Sagrado, I.C. [Laboratorio de Radiaciones Ionizantes, University of Salamanca (Spain); Unsworth, C.; Moon, S.; Cresswell, J.R. [Nuclear Physics Group, University of Liverpool (United Kingdom)

    2011-08-21

    Characterisation of Germanium detectors used for gamma-ray tracking or medical imaging is one of the current goals in the Nuclear physics community. Good knowledge of detector response to different gamma radiations is needed for this purpose. In order to develop this task, Pulse Shape Analysis (PSA) techniques have been developed for different detector geometries or setups. In this work, we present the results of the application of PSA for a Canberra Broad Energy Germanium (BEGe) detector. This detector was scanned across its front and bottom face using a fully digital data acquisition system; allowing to record detector charge pulse shapes from well defined positions with collimated sources of {sup 241}Am, {sup 22}Na and {sup 137}Cs. With the study of the data acquired, characteristics of the inner detector geometry like crystal limits or positions of contact and isolate can be found, as well as the direction of the axes for the Germanium crystal.

  4. Germanium detector studies in the framework of the GERDA experiment

    Energy Technology Data Exchange (ETDEWEB)

    Budjas, Dusan

    2009-05-06

    The GERmanium Detector Array (GERDA) is an ultra-low background experiment under construction at Laboratori Nazionali del Gran Sasso. GERDA will search for {sup 76}Ge neutrinoless double beta decay with an aim for 100-fold reduction in background compared to predecessor experiments. This ambition necessitates innovative design approaches, strict selection of low-radioactivity materials, and novel techniques for active background suppression. The core feature of GERDA is its array of germanium detectors for ionizing radiation, which are enriched in {sup 76}Ge. Germanium detectors are the central theme of this dissertation. The first part describes the implementation, testing, and optimisation of Monte Carlo simulations of germanium spectrometers, intensively involved in the selection of low-radioactivity materials. The simulations are essential for evaluations of the gamma ray measurements. The second part concerns the development and validation of an active background suppression technique based on germanium detector signal shape analysis. This was performed for the first time using a BEGe-type detector, which features a small read-out electrode. As a result of this work, BEGe is now one of the two detector technologies included in research and development for the second phase of the GERDA experiment. A suppression of major GERDA backgrounds is demonstrated, with (0.93{+-}0.08)% survival probability for events from {sup 60}Co, (21{+-}3)% for {sup 226}Ra, and (40{+-}2)% for {sup 228}Th. The acceptance of {sup 228}Th double escape events, which are analogous to double beta decay, was kept at (89{+-}1)%. (orig.)

  5. Low-energy neutrino and dark matter physics with sub-keV germanium detectors

    Indian Academy of Sciences (India)

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

    2012-11-01

    The TEXONO-CDEX Collaboration (Taiwan experiment on neutrino–China dark matter experiment) explores high-purity germanium (HPGe) detection technology to develop a sub-keV threshold detector for pursuing studies on low mass weakly interacting massive particles (WIMPs), properties of neutrino and the possibilities of neutrino-nucleus coherent scattering observation. This article will introduce the facilities of newly established China Jing-Ping Underground Laboratory (CJPL), preliminary result of cosmic ray background studies at CJPL, the dark matter studies pursued at Kuo-Sheng Neutrino Laboratory (KSNL) and research efforts to accomplish our physics goals.

  6. Ameliorating neutron damage in orthogonal-strip planar germanium detectors

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, E.G., E-mail: Emily_Jackson@student.uml.edu [Department of Physics and Applied Physics, University of Massachusetts Lowell, Lowell, MA 01854 (United States); Hull, E.L. [PHDS Company, 3011 Amherst Road, Knoxville, TN 37921 (United States); Lister, C.J. [Department of Physics and Applied Physics, University of Massachusetts Lowell, Lowell, MA 01854 (United States); Pehl, R.H. [PHDS Company, 3011 Amherst Road, Knoxville, TN 37921 (United States)

    2015-02-21

    The segmentation of the electrodes of germanium detectors facilitates gamma-ray imaging and tracking. Replacing the traditional n-type lithium drifted contact is a key to finer segmentation. Amorphous-germanium is a promising alternative contact technology, and large, highly segmented detectors have been fabricated. One factor in adopting any new detector technology is its robustness in hostile environments. Therefore, to explore the effects of neutron damage on position sensitive amorphous-contact germanium gamma-ray detectors and investigate methods for mitigation and repair of damage, two detectors were intentionally exposed to a non-uniform neutron fluence of greater than 4(1) ×10{sup 9} n/cm{sup 2} produced in the {sup 7}Li(p, n){sup 7}Be reaction at the UMass Lowell Van-de-Graaff accelerator. Post-irradiation tests were made on the counters by varying the electric field, the charge deposition rate, the operating temperature, and utilizing various annealing cycles in order to ascertain the robustness of their performance after irradiation.

  7. Germanium Blocked Impurity Band (BIB) detectors

    Science.gov (United States)

    Haller, E. E.; Baumann, H.; Beeman, J. W.; Hansen, W. L.; Luke, P. N.; Lutz, M.; Rossington, C. S.; Wu, I. C.

    1989-01-01

    Information is given in viewgraph form. The advantages of the Si blocked impurity band (BIB) detector invented by M. D. Petroff and M. G. Stabelbroek are noted: smaller detection volume leading to a reduction of cosmic ray interference, extended wavelength response because of dopant wavefunction overlap, and photoconductive gain of unity. It is argued that the stated advantages of Si BIB detectors should be realizable for Ge BIB detectors. Information is given on detector development, subtrate choice and preparation, wafer polising, epitaxy, characterization of epi layers, and preliminary Ge BIB detector test results.

  8. Germanium 70: a gamma ray detector for astrophysics; Le germanium 70: un detecteur de rayons gamma en astrophysique

    Energy Technology Data Exchange (ETDEWEB)

    Durouchoux, P. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l`Instrumentation Associee

    1994-12-31

    A thorough study concerning the background noise generated from the germanium detectors used in astrophysics spatial experiences, is presented. These detectors, selected for their energy high definition, are sensitive to cosmic radiations that activate some isotopes contained in the natural germanium and induce background noise through a beta+ decay. This noise component may be notably reduced with utilization of {sup 70}Ge isotope enriched detectors, which do not present such interactions. The predictions have been verified through space tests conducted from Australia in 1992. Preliminary results and prospectives for astrophysics application of the Germanium 70 isotope, are discussed. 6 figs., 2 tabs., 3 refs.

  9. Astroparticle physics with a customized low-background broad energy Germanium detector

    Energy Technology Data Exchange (ETDEWEB)

    Aalseth, Craig E.; Amman, M.; Avignone, Frank T.; Back, Henning O.; Barabash, Alexander S.; Barbeau, P. S.; Bergevin, M.; Bertrand, F.; Boswell, M.; Brudanin, V.; Bugg, William; Burritt, Tom H.; Busch, Matthew; Capps, Greg L.; Chan, Yuen-Dat; Collar, J. I.; Cooper, R. J.; Creswick, R.; Detwiler, Jason A.; Diaz, J.; Doe, Peter J.; Efremenko, Yuri; Egorov, Viatcheslav; Ejiri, H.; Elliott, Steven R.; Ely, James H.; Esterline, James H.; Farach, H. A.; Fast, James E.; Fields, N.; Finnerty, P.; Fujikawa, Brian; Fuller, Erin S.; Gehman, Victor M.; Giovanetti, G. K.; Guiseppe, Vincente; Gusey, K.; Hallin, A. L.; Harper, Gregory; Hazama, R.; Henning, Reyco; Hime, Andrew; Hoppe, Eric W.; Hossbach, Todd W.; Howe, M. A.; Johnson, R. A.; Keeter, K.; Keillor, Martin E.; Keller, C.; Kephart, Jeremy D.; Kidd, Mary; Knecht, A.; Kochetov, Oleg; Konovalov, S.; Kouzes, Richard T.; Leviner, L.; Loach, J. C.; Luke, P.; MacMullin, S.; Marino, Michael G.; Martin, R. D.; Mei, Dong-Ming; Miley, Harry S.; Miller, M. L.; Mizouni, Leila; Myers, Allan W.; Nomachi, Masaharu; Orrell, John L.; Peterson, David; Phillips, D.; Poon, Alan; Prior, Gersende; Qian, J.; Radford, D. C.; Rielage, Keith; Robertson, R. G. H.; Rodriguez, Larry; Rykaczewski, Krzysztof P.; Salazar, Harold; Schubert, Alexis G.; Shima, T.; Shirchenko, M.; Steele, David; Strain, J.; Swift, Gary; Thomas, K.; Timkin, V.; Tornow, W.; Van Wechel, T. D.; Vanyushin, I.; Varner, R. L.; Vetter, Kai; Wilkerson, J. F.; Wolfe, B. A.; Xiang, W.; Yakushev, E.; Yaver, Harold; Young, A.; Yu, Chang-Hong; Yumatov, Vladimir; Zhang, C.; Zimmerman, S.

    2011-10-01

    The Majorana Collaboration is building the Majorana Demonstrator, a 60 kg array of high purity germanium detectors housed in an ultra-low background shield at the Sanford Underground Laboratory in Lead, SD. The Majorana Demonstrator will search for neutrinoless double-beta decay of 76Ge while demonstrating the feasibility of a tonne-scale experiment. It may also carry out a dark matter search in the 1-10 GeV/c² mass range. We have found that customized Broad Energy Germanium (BEGe) detectors produced by Canberra have several desirable features for a neutrinoless double-beta decay experiment, including low electronic noise, excellent pulse shape analysis capabilities, and simple fabrication. We have deployed a customized BEGe, the Majorana Low-Background BEGe at Kimballton (MALBEK), in a low-background cryostat and shield at the Kimballton Underground Research Facility in Virginia. This paper will focus on the detector characteristics and measurements that can be performed with such a radiation detector in a low-background environment.

  10. Astroparticle Physics with a Customized Low-Background Broad Energy Germanium Detector

    CERN Document Server

    Aalseth, C E; Avignone, F T; Back, H O; Barabash, A S; Barbeau, P S; Bergevin, M; Bertrand, F E; Boswell, M; Brudanin, V; Bugg, W; Burritt, T H; Busch, M; Capps, G; Chan, Y-D; Collar, J I; Cooper, R J; Creswick, R; Detwiler, J A; Diaz, J; Doe, P J; Efremenko, Yu; Egorov, V; Ejiri, H; Elliott, S R; Ely, J; Esterline, J; Farach, H; Fast, J E; Fields, N; Finnerty, P; Fujikawa, B; Fuller, E; Gehman, V M; Giovanetti, G K; Guiseppe, V E; Gusey, K; Hallin, A L; Harper, G C; Hazama, R; Henning, R; Hime, A; Hoppe, E W; Hossbach, T W; Howe, M A; Johnson, R A; Keeter, K J; Keillor, M; Keller, C; Kephart, J D; Kidd, M F; Knecht, A; Kochetov, O; Konovalov, S I; Kouzes, R T; Leviner, L; Loach, J C; Luke, P N; MacMullin, S; Marino, M G; Martin, R D; Mei, D -M; Miley, H S; Miller, M L; Mizouni, L; Meyers, A W; Nomachi, M; Orrell, J L; Peterson, D; Phillips, D G; Poon, A W P; Prior, G; Qian, J; Radford, D C; Rielage, K; Robertson, R G H; Rodriguez, L; Rykaczewski, K P; Salazar, H; Schubert, A G; Shima, T; Shirchenko, M; Steele, D; Strain, J; Swift, G; Thomas, K; Timkin, V; Tornow, W; Van Wechel, T D; Vanyushin, I; Varner, R L; Vetter, K; Wilkerson, J F; Wolfe, B A; Xiang, W; Yakushev, E; Yaver, H; Young, A R; Yu, C -H; Yumatov, V; Zhang, C; Zimmerman, S

    2010-01-01

    The MAJORANA Collaboration is building the MAJORANA DEMONSTRATOR, a 60 kg array of high purity germanium detectors housed in an ultra-low background shield at the Sanford Underground Laboratory in Lead, SD. The MAJORANA DEMONSTRATOR will search for neutrinoless double-beta decay of 76Ge while demonstrating the feasibility of a tonne-scale experiment. It may also carry out a dark matter search in the 1-10 GeV/c^2 mass range. We have found that customized Broad Energy Germanium (BEGe) detectors produced by Canberra have several desirable features for a neutrinoless double-beta decay experiment, including low electronic noise, excellent pulse shape analysis capabilities, and simple fabrication. We have deployed a customized BEGe, the MAJORANA Low-Background BEGe at Kimballton (MALBEK), in a low-background cryostat and shield at the Kimballton Underground Research Facility in Virginia. This paper will focus on the detector characteristics and measurements that can be performed with such a radiation detector in a ...

  11. Environmental applications for an intrinsic germanium well detector

    Energy Technology Data Exchange (ETDEWEB)

    Stegnar, P.; Eldridge, J.S.; Teasley, N.A.; Oakes, T.W.

    1983-01-01

    The overall performance of an intrinsic germanium well detector for /sup 125/I measurements was investigated in a program of environmental surveillance. Concentrations of /sup 125/I and /sup 131/I were determined in thyroids of road-killed deer showing the highest activities of /sup 125/I in the animals from the near vicinity of Oak Ridge National Laboratory. This demonstrates the utility of road-killed deer as a bioindicator for radioiodine around nuclear facilities. 6 refs., 2 figs., 3 tabs.

  12. Massive silicon or germanium detectors at cryogenic temperature

    Energy Technology Data Exchange (ETDEWEB)

    Braggio, C. [Dip. Fisica dell' Universita di Ferrara and INFN, via del Paradiso 12, 44100 Ferrara (Italy); Bressi, G. [INFN, sez.Pavia, Via U. Bassi 6, 27100 Pavia (Italy); Carugno, G. [INFN, sez. Padova, Via Marzolo 8, 35131 Padova (Italy); Feltrin, E. [INFN, Lab. Naz. Legnaro, Via dell' Universita 1, 35020 Legnaro (PD) (Italy)]. E-mail: feltrin@lnl.infn.it; Galeazzi, G. [INFN, Lab. Naz. Legnaro, Via dell' Universita 1, 35020 Legnaro (PD) (Italy)

    2006-11-30

    Several massive silicon and germanium home-made detectors, working at cryogenic temperature, have been studied. They are the benchmarking schemes to check the possibility of realizing a semiconductor time projection chamber that could have various interesting applications in weak interaction problems. Reported here are the first results on investigations of charge collection efficiency and metal-semiconductor contact hardness. The leakage current, total depletion voltage and alpha or gamma spectroscopy are presented.

  13. A precise method to determine the activity of a weak neutron source using a germanium detector

    CERN Document Server

    Duke, M J M; Krauss, C B; Mekarski, P; Sibley, L

    2015-01-01

    A standard high purity germanium detector (HPGe) was used to determine the neutron activity of a weak americium-beryllium (AmBe) neutron source. Gamma rays were created through 27Al(n,n'), 27Al(n,gamma) and 1H(n,gamma) reactions induced by the neutrons on aluminum and acrylic disks. A Monte Carlo simulation was developed to model the efficiency of the detector system. The activity of our neutron source was determined to be 305.6 +/- 4.9 n/s. The result is consistent for the different gamma rays and was verified using additional simulations and measurements of the 4483 keV gamma ray produced directly from the AmBe source.

  14. Silicon-Germanium Alloys for Infrared Detectors.

    Science.gov (United States)

    1980-04-01

    crystals, aiming at improved crystallinity and higher resistivity and to extend the Czochralski growth method to indium-doped Si-Ge alloys. Our intention...of the disappointingly high boron concentrations achieved in Czochralski growth, we decided to explore a crucible-free method for preparing Si-Ge...material was not high enough to allow an adequately long depletion region in a p-i-n detector. It does not appear that any Czochralski -type growth method

  15. Positional calibrations of the germanium double sided strip detectors for the Compton spectrometer and imager

    Science.gov (United States)

    Lowell, A.; Boggs, S.; Chiu, J. L.; Kierans, C.; McBride, S.; Tseng, C. H.; Zoglauer, A.; Amman, M.; Chang, H. K.; Jean, P.; Lin, C. H.; Sleator, C.; Tomsick, J.; von Ballmoos, P.; Yang, C. Y.

    2016-08-01

    The Compton Spectrometer and Imager (COSI) is a medium energy gamma ray (0.2 - 10 MeV) imager designed to observe high-energy processes in the universe from a high altitude balloon platform. At its core, COSI is comprised of twelve high purity germanium double sided strip detectors which measure particle interaction energies and locations with high precision. This manuscript focuses on the positional calibrations of the COSI detectors. The interaction depth in a detector is inferred from the charge collection time difference between the two sides of the detector. We outline our previous approach to this depth calibration and also describe a new approach we have recently developed. Two dimensional localization of interactions along the faces of the detector (x and y) is straightforward, as the location of the triggering strips is simply used. However, we describe a possible technique to improve the x/y position resolution beyond the detector strip pitch of 2 mm. With the current positional calibrations, COSI achieves an angular resolution of 5.6 +/- 0.1 degrees at 662 keV, close to our expectations from simulations.

  16. Modeling of germanium detector and its sourceless calibration

    Directory of Open Access Journals (Sweden)

    Steljić Milijana

    2008-01-01

    Full Text Available The paper describes the procedure of adapting a coaxial high-precision germanium detector to a device with numerical calibration. The procedure includes the determination of detector dimensions and establishing the corresponding model of the system. In order to achieve a successful calibration of the system without the usage of standard sources, Monte Carlo simulations were performed to determine its efficiency and pulse-height response function. A detailed Monte Carlo model was developed using the MCNP-5.0 code. The obtained results have indicated that this method represents a valuable tool for the quantitative uncertainty analysis of radiation spectrometers and gamma-ray detector calibration, thus minimizing the need for the deployment of radioactive sources.

  17. Gamma ray polarimetry using a position sensitive germanium detector

    CERN Document Server

    Kroeger, R A; Kurfess, J D; Phlips, B F

    1999-01-01

    Imaging gamma-ray detectors make sensitive polarimeters in the Compton energy regime by measuring the scatter direction of gamma rays. The principle is to capitalize on the angular dependence of the Compton scattering cross section to polarized gamma rays and measure the distribution of scatter directions within the detector. This technique is effective in a double-sided germanium detector between roughly 50 keV and 1 MeV. This paper reviews device characteristics important to the optimization of a Compton polarimeter, and summarizes measurements we have made using a device with a 5x5 cm active area, 1 cm thickness, and strip-electrodes on a 2 mm pitch.

  18. HEROICA: an Underground Facility for the Fast Screening of Germanium Detectors

    CERN Document Server

    Andreotti, E; Maneschg, W; Barros, N; Benato, G; Brugnera, R; Costa, F; Falkenstein, R; Guthikonda, K K; Hegai, A; Hemmer, S; Hult, M; Jaenner, K; Kihm, T; Lehnert, B; Liao, H; Lubashevskiy, A; Lutter, G; Marissens, G; Modenese, L; Pandola, L; Reissfelder, M; Sada, C; Salathe, M; Schmitt, C; Schulz, O; Schwingenheuer, B; Turcato, M; Ur, C; von Sturm, K; Wagner, V; Westermann, J

    2013-01-01

    An infrastructure to characterize germanium detectors has been designed and constructed at the HADES Underground Research Laboratory, located in Mol (Belgium). Thanks to the 223m overburden of clay and sand, the muon flux is lowered by four orders of magnitude. This natural shield minimizes the exposure of radio-pure germanium material to cosmic radiation resulting in a significant suppression of cosmogenic activation in the germanium detectors. The project has been strongly motivated by a special production of germanium detectors for the GERDA experiment. GERDA, currently collecting data at the Laboratori Nazionali del Gran Sasso of INFN, is searching for the neutrinoless double beta decay of 76Ge. In the near future, GERDA will increase its mass and sensitivity by adding new Broad Energy Germanium (BEGe) detectors. The production of the BEGe detectors is done at Canberra in Olen (Belgium), located about 30km from the underground test site. Therefore, HADES is used both for storage of the crystals over night...

  19. Contribution of a germanium detector in mobile gamma-ray spectrometry. Spectral analysis and performance

    CERN Document Server

    Gutierrez, S; Bourgeois, C

    2002-01-01

    The sensitivity of the germanium semi-conductor detector is 30 times lower than that of the sodium iodide (NaI) detectors frequently used in airborne spectrometry. Its energy resolution however, is 20 times better, giving more accurate identification of radionuclides, especially when complex spectra are involved. The use of the germanium detector in mobile gamma-ray spectrometry provides a large amount of qualitative and quantitative information. In post-accident situations a germanium detector will be sufficient, and should therefore be used in preference to a NaI detector. An algorithm for detecting the total absorption peaks by studying the variations in the spectral profile of germanium gamma-ray spectra has been developed at the CEA. The use of digital filters that take into account the characteristics of the absorption peaks reduces the statistical fluctuations, making possible detection based on the analysis of the first and second derivatives. The absorption peak is then estimated by subtracting the b...

  20. An Implant-Passivated Blocked Impurity Band Germanium Detector for the Far Infrared Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to fabricate a germanium blocked-impurity-band (BIB) detector using a novel process which will enable us to: 1- fabricate a suitably-doped active layer...

  1. An Implant-Passivated Blocked Impurity Band Germanium Detector for the Far Infrared Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to investigate the feasibility of fabricating a germanium blocked-impurity-band (BIB) detector using a novel process which will enable us to: 1- fabricate...

  2. Environmental Radioactivity: Gamma Ray Spectroscopy with Germanium detector

    Science.gov (United States)

    Vyas, Gargi; Beausang, Cornelius; Hughes, Richard; Tarlow, Thomas; Gell, Kristen; University of Richmond Physics Team

    2013-10-01

    A CF-1000BRL series portable Air Particle Sampler with filter paper as filter media was placed in one indoor and one outdoor location at 100 LPM flow rate on six dates under alternating rainy and warm weather conditions over the course of sixteen days in May 2013. The machine running times spanned between 6 to 69 hours. Each filter paper was then put in a germanium gamma ray detector, and the counts ranged from 93000 to 250000 seconds. The spectra obtained were analyzed by the CANBERRA Genie 2000 software, corrected using a background spectrum, and calibrated using a 20.27 kBq activity multi-nuclide source. We graphed the corrected counts (from detector analysis time)/second (from air sampler running time)/liter (from the air sampler's flow rate) of sharp, significantly big peaks corresponding to a nuclide in every sample against the sample number along with error bars. The graphs were then used to compare the samples and they showed a similar trend. The slight differences were usually due to the different running times of the air sampler. The graphs of about 22 nuclides were analyzed. We also tried to recognize the nuclei to which several gamma rays belonged that were displayed but not recognized by the Genie 2000 software.

  3. PREFACE: 2nd Workshop on Germanium Detectors and Technologies

    Science.gov (United States)

    Abt, I.; Majorovits, B.; Keller, C.; Mei, D.; Wang, G.; Wei, W.

    2015-05-01

    The 2nd workshop on Germanium (Ge) detectors and technology was held at the University of South Dakota on September 14-17th 2014, with more than 113 participants from 8 countries, 22 institutions, 15 national laboratories, and 8 companies. The participants represented the following big projects: (1) GERDA and Majorana for the search of neutrinoless double-beta decay (0νββ) (2) SuperCDMS, EDELWEISS, CDEX, and CoGeNT for search of dark matter; (3) TEXONO for sub-keV neutrino physics; (4) AGATA and GRETINA for gamma tracking; (5) AARM and others for low background radiation counting; (5) as well as PNNL and LBNL for applications of Ge detectors in homeland security. All participants have expressed a strong desire on having better understanding of Ge detector performance and advancing Ge technology for large-scale applications. The purpose of this workshop was to leverage the unique aspects of the underground laboratories in the world and the germanium (Ge) crystal growing infrastructure at the University of South Dakota (USD) by brining researchers from several institutions taking part in the Experimental Program to Stimulate Competitive Research (EPSCoR) together with key leaders from international laboratories and prestigious universities, working on the forefront of the intensity to advance underground physics focusing on the searches for dark matter, neutrinoless double-beta decay (0νββ), and neutrino properties. The goal of the workshop was to develop opportunities for EPSCoR institutions to play key roles in the planned world-class research experiments. The workshop was to integrate individual talents and existing research capabilities, from multiple disciplines and multiple institutions, to develop research collaborations, which includes EPSCor institutions from South Dakota, North Dakota, Alabama, Iowa, and South Carolina to support multi-ton scale experiments for future. The topic areas covered in the workshop were: 1) science related to Ge

  4. Charge-trap correction and radiation damage in orthogonal-strip planar germanium detectors

    Energy Technology Data Exchange (ETDEWEB)

    Hull, E.L. [PHDS Corporation, 3011 Amherst Road, Knoxville, TN 37921 (United States); Jackson, E.G.; Lister, C.J. [Physics Department, University of Massachusetts Lowell, Lowell, MA 01854 (United States); Pehl, R.H. [PHDS Corporation, 3011 Amherst Road, Knoxville, TN 37921 (United States)

    2014-10-21

    A charge-carrier trap correction technique was developed for orthogonal strip planar germanium gamma-ray detectors. The trap corrector significantly improves the gamma-ray energy resolution of detectors with charge-carrier trapping from crystal-growth defects and radiation damage. Two orthogonal-strip planar germanium detectors were radiation damaged with 2-MeV neutron fluences of ∼8×10{sup 9} n/cm{sup 2}. The radiation-damaged detectors were studied in the 60–80 K temperature range.

  5. Radium needle used to calibrate germanium gamma-ray detector.

    Science.gov (United States)

    Kamboj, S; Lovett, D; Kahn, B; Walker, D

    1993-03-01

    A standard platinum-iridium needle that contains 374 MBq 226Ra was tested as a source for calibrating a portable germanium detector used with a gamma-ray spectrometer for environmental radioactivity measurements. The counting efficiencies of the 11 most intense gamma rays emitted by 226Ra and its short-lived radioactive progeny at energies between 186 and 2,448 keV were determined, at the full energy peaks, to construct a curve of counting efficiency vs. energy. The curve was compared to another curve between 43 and 1,596 keV obtained with a NIST mixed-radionuclide standard. It was also compared to the results of a Monte Carlo simulation. The 226Ra source results were consistent with the NIST standard between 248 and 1,596 keV. The Monte Carlo simulation gave a curve parallel to the curve for the combined radium and NIST standard data between 250 and 2,000 keV, but at higher efficiency.

  6. Search for Pauli exclusion principle violating atomic transitions and electron decay with a p-type point contact germanium detector

    Energy Technology Data Exchange (ETDEWEB)

    Abgrall, N.; Arnquist, I. J.; Avignone, F. T.; Barabash, A. S.; Bertrand, F. E.; Bradley, A. W.; Brudanin, V.; Busch, M.; Buuck, M.; Caldwell, A. S.; Chan, Y. -D.; Christofferson, C. D.; Chu, P. -H.; Cuesta, C.; Detwiler, J. A.; Dunagan, C.; Efremenko, Yu.; Ejiri, H.; Elliott, S. R.; Finnerty, P. S.; Galindo-Uribarri, A.; Gilliss, T.; Giovanetti, G. K.; Goett, J.; Green, M. P.; Gruszko, J.; Guinn, I. S.; Guiseppe, V. E.; Henning, R.; Hoppe, E. W.; Howard, S.; Howe, M. A.; Jasinski, B. R.; Keeter, K. J.; Kidd, M. F.; Konovalov, S. I.; Kouzes, R. T.; LaFerriere, B. D.; Leon, J.; MacMullin, J.; Martin, R. D.; Massarczyk, R.; Meijer, S. J.; Mertens, S.; Orrell, J. L.; O’Shaughnessy, C.; Poon, A. W. P.; Radford, D. C.; Rager, J.; Rielage, K.; Robertson, R. G. H.; Romero-Romero, E.; Shanks, B.; Shirchenko, M.; Suriano, A. M.; Tedeschi, D.; Trimble, J. E.; Varner, R. L.; Vasilyev, S.; Vetter, K.; Vorren, K.; White, B. R.; Wilkerson, J. F.; Wiseman, C.; Xu, W.; Yakushev, E.; Yu, C. -H.; Yumatov, V.; Zhitnikov, I.

    2016-11-11

    A search for Pauli-exclusion-principle-violating K electron transitions was performed using 89.5 kg-d of data collected with a p-type point contact high-purity germanium detector operated at the Kimballton Underground Research Facility. A lower limit on the transition lifetime of s at 90% C.L. was set by looking for a peak at 10.6 keV resulting from the X-ray and Auger electrons present following the transition. A similar analysis was done to look for the decay of atomic K-shell electrons into neutrinos, resulting in a lower limit of s at 90% C.L. It is estimated that the Majorana Demonstrator, a 44 kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kroeninger, K.

    2007-06-05

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

  8. High bit rate germanium single photon detectors for 1310nm

    Science.gov (United States)

    Seamons, J. A.; Carroll, M. S.

    2008-04-01

    There is increasing interest in development of high speed, low noise and readily fieldable near infrared (NIR) single photon detectors. InGaAs/InP Avalanche photodiodes (APD) operated in Geiger mode (GM) are a leading choice for NIR due to their preeminence in optical networking. After-pulsing is, however, a primary challenge to operating InGaAs/InP single photon detectors at high frequencies1. After-pulsing is the effect of charge being released from traps that trigger false ("dark") counts. To overcome this problem, hold-off times between detection windows are used to allow the traps to discharge to suppress after-pulsing. The hold-off time represents, however, an upper limit on detection frequency that shows degradation beginning at frequencies of ~100 kHz in InGaAs/InP. Alternatively, germanium (Ge) single photon avalanche photodiodes (SPAD) have been reported to have more than an order of magnitude smaller charge trap densities than InGaAs/InP SPADs2, which allowed them to be successfully operated with passive quenching2 (i.e., no gated hold off times necessary), which is not possible with InGaAs/InP SPADs, indicating a much weaker dark count dependence on hold-off time consistent with fewer charge traps. Despite these encouraging results suggesting a possible higher operating frequency limit for Ge SPADs, little has been reported on Ge SPAD performance at high frequencies presumably because previous work with Ge SPADs has been discouraged by a strong demand to work at 1550 nm. NIR SPADs require cooling, which in the case of Ge SPADs dramatically reduces the quantum efficiency of the Ge at 1550 nm. Recently, however, advantages to working at 1310 nm have been suggested which combined with a need to increase quantum bit rates for quantum key distribution (QKD) motivates examination of Ge detectors performance at very high detection rates where InGaAs/InP does not perform as well. Presented in this paper are measurements of a commercially available Ge APD

  9. Extraction of Physics Signals Near Threshold with Germanium Detectors in Neutrino and Dark Matter Experiments

    CERN Document Server

    Soma, A K; Lin, F K; Singh, M K; Jiang, H; Liu, S K; Singh, L; Wu, Y C; Yang, L T; Zhao, W; Agartioglu, M; Asryan, G; Chuang, Y C; Deniz, M; Hsu, C L; Hsu, Y H; Huang, T R; Li, H B; Li, J; Liao, F T; Liao, H Y; Lin, C W; Lin, S T; Ma, J L; Sharma, V; Shen, Y T; Singh, V; Su, J; Subrahmanyam, V S; Tseng, C H; Wang, J J; Wong, H T; Xu, Y; Yang, S W; Yu, C X; Yuan, X C; Yue, Q; Zeyre, M

    2014-01-01

    Germanium ionization detectors with sensitivities as low as 100 eVee open new windows for the studies of neutrino and dark matter physics. The physics motivations of sub-keV germanium detectors are summarized. The amplitude of physics signals is comparable to those due to fluctuations of the pedestal electronic noise. Various experimental issues have to be attended before the promises of this new detector technique can be fully exploited. These include quenching factors, energy definition and calibration, signal triggering and selection together with their associated inefficiencies derivation. The efforts and results of an R&D program to address these challenges are presented.

  10. GIOVE: a new detector setup for high sensitivity germanium spectroscopy at shallow depth

    Energy Technology Data Exchange (ETDEWEB)

    Heusser, G.; Weber, M.; Hakenmueller, J.; Lindner, M.; Maneschg, W.; Simgen, H.; Stolzenburg, D.; Strecker, H. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Laubenstein, M. [Laboratori Nazionali del Gran Sasso, Assergi (Italy)

    2015-11-15

    We report on the development and construction of the high-purity germanium spectrometer setup GIOVE (Germanium Inner Outer VEto), recently built and now operated at the shallow underground laboratory of the Max-Planck-Institut fuer Kernphysik, Heidelberg. Particular attention was paid to the design of a novel passive and active shield, aiming at efficient rejection of environmental and muon induced radiation backgrounds. The achieved sensitivity level of ≤ 100μBq kg{sup -1} for primordial radionuclides from U and Th in typical γ ray sample screening measurements is unique among instruments located at comparably shallow depths and can compete with instruments at far deeper underground sites. (orig.)

  11. GIOVE - A New Detector Setup for High Sensitivity Germanium Spectroscopy At Shallow Depth

    CERN Document Server

    Heusser, Gerd; Hakenmüller, Janina; Laubenstein, Matthias; Lindner, Manfred; Maneschg, Werner; Simgen, Hardy; Stolzenburg, Dominik; Strecker, Herbert

    2015-01-01

    We report on the development and construction of the high-purity germanium spectrometer setup GIOVE (Germanium Inner Outer Veto), recently built and now operated at the shallow underground laboratory of the Max-Planck-Institut f\\"ur Kernphysik, Heidelberg. Particular attention was paid to the design of a novel passive and active shield, aiming at efficient rejection of environmental and muon induced radiation backgrounds. The achieved sensitivity level of <100 {\\mu}Bq/kg for primordial radionuclides from U and Th in typical {\\gamma} ray sample screening measurements is unique among instruments located at comparably shallow depths and can compete with instruments at far deeper underground sites.

  12. Dark Matter Search with sub-keV Germanium Detectors at the China Jinping Underground Laboratory

    CERN Document Server

    Yue, Qian

    2012-01-01

    Germanium detectors with sub-keV sensitivities open a window to search for low-mass WIMP dark matter. The CDEX-TEXONO Collaboration is conducting the first research program at the new China Jinping Underground Laboratory with this approach. The status and plans of the laboratory and the experiment are discussed.

  13. Dark Matter Search with Sub-Kev Germanium Detectors at the China Jinping Underground Laboratory

    Science.gov (United States)

    Yue, Qian; Wong, Henry T.

    2013-12-01

    Germanium detectors with sub-keV sensitivities open a window to search for low-mass WIMP dark matter. The CDEX-TEXONO Collaboration is conducting the first research program at the new China Jinping Underground Laboratory with this approach. The status and plans of the laboratory and the experiment are discussed.

  14. Development of segmented germanium detectors for neutrinoless double beta decay experiments

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jing

    2009-06-09

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

  15. High Purity Germanium Gamma-PHA Assay of Uranium Scrap Cans Used in 321-M Facility

    Science.gov (United States)

    Salaymeh, S. R.; Dewberry, R. A.; Casella, V.

    2001-12-01

    The Analytical Development Section of SRTC was requested by the Facilities Disposition Division (FDD) to determine the holdup of enriched uranium in the 321-M facility as part of an overall deactivation project of the facility. The 321-M facility was used to fabricate enriched uranium fuel assemblies, lithium-aluminum target tubes, neptunium assemblies, and miscellaneous components for the production reactors. The facility also includes the 324-M storage building and the passageway connecting it to 321-M. The results of the holdup assays are essential for determining compliance with the Solid Waste's Waste Acceptance Criteria, Material Control & Accountability, and to meet criticality safety controls. This report describes and documents the use of a portable HPGe detector and EG&G DART system that contains a high voltage power supply, signal processing electronics, a personal computer with Gamma-Vision software, and space to store and manipulate multiple 4096-channel gamma-ray spectra to assay for 235U content. The system was used to assay a large number of scrap cans used to store highly enriched uranium (HEU) chips and filings. This report includes a description of two efficiency calibration configurations and also the results of the assay. A description of the quality control checks is included as well.

  16. Resonance-enhanced waveguide-coupled silicon-germanium detector

    CERN Document Server

    Alloatti, Luca

    2016-01-01

    A photodiode with 0.55$\\pm$0.1 A/W responsivity at a wavelength of 1176.9 nm has been fabricated in a 45 nm microelectronics silicon-on-insulator foundry process. The resonant waveguide photodetector exploits carrier generation in silicon-germanium (SiGe) within a microring which is compatible with high-performance electronics. A 3 dB bandwidth of 5 GHz at -4 V bias is obtained with a dark current of less than 20 pA.

  17. GIOVE: a new detector setup for high sensitivity germanium spectroscopy at shallow depth

    Energy Technology Data Exchange (ETDEWEB)

    Heusser, G., E-mail: gerd.heusser@mpi-hd.mpg.de; Weber, M., E-mail: marc.weber@mpi-hd.mpg.de; Hakenmüller, J. [Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117, Heidelberg (Germany); Laubenstein, M. [Laboratori Nazionali del Gran Sasso, Via G. Acitelli 22, 67100, Assergi, AQ (Italy); Lindner, M.; Maneschg, W.; Simgen, H.; Stolzenburg, D.; Strecker, H. [Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117, Heidelberg (Germany)

    2015-11-09

    We report on the development and construction of the high-purity germanium spectrometer setup GIOVE (Germanium Inner Outer VEto), recently built and now operated at the shallow underground laboratory of the Max-Planck-Institut für Kernphysik, Heidelberg. Particular attention was paid to the design of a novel passive and active shield, aiming at efficient rejection of environmental and muon induced radiation backgrounds. The achieved sensitivity level of ≤100 μBq kg{sup -1} for primordial radionuclides from U and Th in typical γ ray sample screening measurements is unique among instruments located at comparably shallow depths and can compete with instruments at far deeper underground sites.

  18. A New Expression for the Full Energy Peak Efficiency of a High Pure Germanium Detector

    CERN Document Server

    Medhat, M E; Awaad, Z

    2001-01-01

    An empirical expression for the full energy photo-peak efficiency in terms of gamma-ray energy (E) and the vertical distance from the detector surface (d) (i.e. efficiency = function (d,E)) has been obtained for a high pure germanium detector (HPGe) using different standard sources. Comparison of the calculated efficiencies and the experimentally measured values for the energy range from 59.5-1332.2 keV and a source-to-detector distance of 5-30 cm showed that the theoretical values agree with the experiment.

  19. The GALATEA test facility and a first study of α-induced surface events in a germanium detector

    Energy Technology Data Exchange (ETDEWEB)

    Irlbeck, Sabine

    2014-01-30

    Germanium detectors are a choice technology in fundamental research. They are suitable for the search for rare events due to their high sensitivity and excellent energy resolution. As an example, the GERDA (GERmanium Detector Array) experiment searching for neutrinoless double beta decay is described. The observation of this decay would resolve the fundamental question whether the neutrino is its own antiparticle. Especially adapted detector technologies and low background rates needed to detect very rare events such as neutrinoless double beta decays are discussed. The identification of backgrounds originating from the interaction of radiation, especially α-particles, is a focus of this thesis. Low background experiments face problems from α-particles due to unavoidable surface contaminations of the germanium detectors. The segmentation of detectors is used to obtain information about the special characteristics of selected events. The high precision test stand GALATEA was especially designed for surface scans of germanium detectors. As part of this work, GALATEA was completed and commissioned. The final commissioning required major upgrades of the original design which are described in detail. Collimator studies with two commercial germanium detectors are presented. Different collimation levels for a β-source were investigated and crystal axis effects were examined. The first scan with an α-source of the passivated end-plate of a special 19-fold segmented prototype detector mounted in GALATEA is described. The α-induced surface events were studied and characterized. Crosstalk and mirror pulses seen in the segments of the germanium detector were analyzed. The detector studies presented in this thesis will help to further improve the design of germanium detectors for low background experiments.

  20. CDEX-1 1 kg point-contact germanium detector for low mass dark matter searches

    Science.gov (United States)

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

    2013-12-01

    The CDEX collaboration has been established for direct detection of light dark matter particles, using ultra-low energy threshold point-contact p-type germanium detectors, in China JinPing underground Laboratory (CJPL). The first 1 kg point-contact germanium detector with a sub-keV energy threshold has been tested in a passive shielding system located in CJPL. The outputs from both the point-contact P+ electrode and the outside N+ electrode make it possible to scan the lower energy range of less than 1 keV and at the same time to detect the higher energy range up to 3 MeV. The outputs from both P+ and N+ electrode may also provide a more powerful method for signal discrimination for dark matter experiment. Some key parameters, including energy resolution, dead time, decay times of internal X-rays, and system stability, have been tested and measured. The results show that the 1 kg point-contact germanium detector, together with its shielding system and electronics, can run smoothly with good performances. This detector system will be deployed for dark matter search experiments.

  1. Neutrino and dark matter physics with sub-keV germanium detectors

    Indian Academy of Sciences (India)

    Arun Kumar Soma; Lakhwinder Singh; Manoj Kumar Singh; Venktesh Singh; Henry T Wong; on behalf of the TEXONO Collaboration

    2014-11-01

    Germanium detectors with sub-keV sensitivities open a window to study neutrino physics to search for light weakly interacting massive particle (WIMP) dark matter. We summarize the recent results on spin-independent couplings of light WIMPs from the TEXONO experiment at the Kuo-Sheng Reactor Neutrino Laboratory. Highlights of the physics motivation, our R&D programme, as well as the status and plans are presented.

  2. Development of a one-dimensional microstrip germanium detector for Compton scattering experiment at SPring-8

    CERN Document Server

    Toyokawa, H; Mizumaki, M; Sakurai, Y; Suzuki, M; Hiraoka, N; Sakai, N

    2001-01-01

    Two prototypes of a one-dimensional microstrip germanium detector were fabricated with seven strips, having different pitches of 200 and 350 mu m. Owing to its insensitivity to hole-diffusion process, the latter one has attained a spatial resolution as high as 350 mu m, an energy resolution better than 1.4%, and a peak efficiency around 50% at an X-ray energy of 80 keV.

  3. Search for Pauli Exclusion Principle Violating Atomic Transitions and Electron Decay with a P-type Point Contact Germanium Detector

    CERN Document Server

    Abgrall, N; Avignone, F T; Barabash, A S; Bertrand, F E; Bradley, A W; Brudanin, V; Busch, M; Buuck, M; Caldwell, A S; Chan, Y-D; Christofferson, C D; Chu, P -H; Cuesta, C; Detwiler, J A; Dunagan, C; Efremenko, Yu; Ejiri, H; Elliott, S R; Finnerty, P S; Galindo-Uribarri, A; Gilliss, T; Giovanetti, G K; Goett, J; Green, M P; Gruszko, J; Guinn, I S; Guiseppe, V E; Henning, R; Hoppe, E W; Howard, S; Howe, M A; Jasinski, B R; Keeter, K J; Kidd, M F; Konovalov, S I; Kouzes, R T; LaFerriere, B D; Leon, J; MacMullin, J; Martin, R D; Massarczyk, R; Meijer, S J; Mertens, S; Orrell, J L; O'Shaughnessy, C; Poon, A W P; Radford, D C; Rager, J; Rielage, K; Robertson, R G H; Romero-Romero, E; Shanks, B; Shirchenko, M; Suriano, A M; Tedeschi, D; Trimble, J E; Varner, R L; Vasilyev, S; Vetter, K; Vorren, K; White, B R; Wilkerson, J F; Wiseman, C; Xu, W; Yakushev, E; Yu, C -H; Yumatov, V; Zhitnikov, I

    2016-01-01

    A search for Pauli-exclusion-principle-violating K-alpha electron transitions was performed using 89.5 kg-d of data collected with a p-type point contact high-purity germanium detector operated at the Kimballton Underground Research Facility. A lower limit on the transition lifetime of 5.8x10^30 seconds at 90% C.L. was set by looking for a peak at 10.6 keV resulting from the x-ray and Auger electrons present following the transition. A similar analysis was done to look for the decay of atomic K-shell electrons into neutrinos, resulting in a lower limit of 6.8x10^30 seconds at 90 C.L. It is estimated that the MAJORANA DEMONSTRATOR, a 44 kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of 76-Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation.

  4. Search for Pauli exclusion principle violating atomic transitions and electron decay with a p-type point contact germanium detector

    Energy Technology Data Exchange (ETDEWEB)

    Abgrall, N.; Bradley, A.W.; Chan, Y.D.; Mertens, S.; Poon, A.W.P. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Arnquist, I.J.; Hoppe, E.W.; Kouzes, R.T.; LaFerriere, B.D.; Orrell, J.L. [Pacific Northwest National Laboratory, Richland, WA (United States); Avignone, F.T. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of South Carolina, Department of Physics and Astronomy, Columbia, SC (United States); Barabash, A.S.; Konovalov, S.I.; Yumatov, V. [National Research Center ' ' Kurchatov Institute' ' Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Bertrand, F.E.; Galindo-Uribarri, A.; Radford, D.C.; Varner, R.L.; White, B.R.; Yu, C.H. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Brudanin, V.; Shirchenko, M.; Vasilyev, S.; Yakushev, E.; Zhitnikov, I. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Busch, M. [Duke University, Department of Physics, Durham, NC (United States); Triangle Universities Nuclear Laboratory, Durham, NC (United States); Buuck, M.; Cuesta, C.; Detwiler, J.A.; Gruszko, J.; Guinn, I.S.; Leon, J.; Robertson, R.G.H. [University of Washington, Department of Physics, Center for Experimental Nuclear Physics and Astrophysics, Seattle, WA (United States); Caldwell, A.S.; Christofferson, C.D.; Dunagan, C.; Howard, S.; Suriano, A.M. [South Dakota School of Mines and Technology, Rapid City, SD (United States); Chu, P.H.; Elliott, S.R.; Goett, J.; Massarczyk, R.; Rielage, K. [Los Alamos National Laboratory, Los Alamos, NM (United States); Efremenko, Yu. [University of Tennessee, Department of Physics and Astronomy, Knoxville, TN (United States); Ejiri, H. [Osaka University, Research Center for Nuclear Physics, Ibaraki, Osaka (Japan); Finnerty, P.S.; Gilliss, T.; Giovanetti, G.K.; Henning, R.; Howe, M.A.; MacMullin, J.; Meijer, S.J.; O' Shaughnessy, C.; Rager, J.; Shanks, B.; Trimble, J.E.; Vorren, K.; Xu, W. [Triangle Universities Nuclear Laboratory, Durham, NC (United States); University of North Carolina, Department of Physics and Astronomy, Chapel Hill, NC (United States); Green, M.P. [North Carolina State University, Department of Physics, Raleigh, NC (United States); Oak Ridge National Laboratory, Oak Ridge, TN (United States); Triangle Universities Nuclear Laboratory, Durham, NC (United States); Guiseppe, V.E.; Tedeschi, D.; Wiseman, C. [University of South Carolina, Department of Physics and Astronomy, Columbia, SC (United States); Jasinski, B.R. [University of South Dakota, Department of Physics, Vermillion, SD (United States); Keeter, K.J. [Black Hills State University, Department of Physics, Spearfish, SD (United States); Kidd, M.F. [Tennessee Tech University, Cookeville, TN (United States); Martin, R.D. [Queen' s University, Department of Physics, Engineering Physics and Astronomy, Kingston, ON (Canada); Romero-Romero, E. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of Tennessee, Department of Physics and Astronomy, Knoxville, TN (United States); Vetter, K. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); University of California, Department of Nuclear Engineering, Berkeley, CA (United States); Wilkerson, J.F. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Triangle Universities Nuclear Laboratory, Durham, NC (United States); University of North Carolina, Department of Physics and Astronomy, Chapel Hill, NC (United States)

    2016-11-15

    A search for Pauli-exclusion-principle-violating K{sub α} electron transitions was performed using 89.5 kg-d of data collected with a p-type point contact high-purity germanium detector operated at the Kimballton Underground Research Facility. A lower limit on the transition lifetime of 5.8 x 10{sup 30} s at 90% C.L. was set by looking for a peak at 10.6 keV resulting from the X-ray and Auger electrons present following the transition. A similar analysis was done to look for the decay of atomic K-shell electrons into neutrinos, resulting in a lower limit of 6.8 x 10{sup 30} s at 90% C.L. It is estimated that the Majorana Demonstrator, a 44 kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of {sup 76}Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation. (orig.)

  5. The CDEX-1 1 kg Point-Contact Germanium Detector for Low Mass Dark Matter Searches

    CERN Document Server

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

    2013-01-01

    The CDEX Collaboration has been established for direct detection of light dark matter particles, using ultra-low energy threshold p-type point-contact germanium detectors, in China JinPing underground Laboratory (CJPL). The first 1 kg point-contact germanium detector with a sub-keV energy threshold has been tested in a passive shielding system located in CJPL. The outputs from both the point-contact p+ electrode and the outside n+ electrode make it possible to scan the lower energy range of less than 1 keV and at the same time to detect the higher energy range up to 3 MeV. The outputs from both p+ and n+ electrode may also provide a more powerful method for signal discrimination for dark matter experiment. Some key parameters, including energy resolution, dead time, decay times of internal X-rays, and system stability, have been tested and measured. The results show that the 1 kg point-contact germanium detector, together with its shielding system and electronics, can run smoothly with good performances. This...

  6. Ultra-Low-Energy Germanium Detector for Neutrino-Nucleus Coherent Scattering and Dark Matter Searches

    CERN Document Server

    Wong, Henry T

    2008-01-01

    The status and plans of a research program on the development of ultra-low-energy germanium detectors with sub-keV sensitivities are reported. We survey the scientific goals which include the observation of neutrino-nucleus coherent scattering, the studies of neutrino magnetic moments, as well as the searches of WIMP dark matter. In particular, a threshold of 100-200 eV and a sub-keV background comparable to underground experiments were achieved with prototype detectors. New limits were set for WIMPs with mass between 3-6 GeV. The prospects of the realization of full-scale experiments are discussed.

  7. A high resolution germanium detector array for hypernuclear studies at PANDA

    Energy Technology Data Exchange (ETDEWEB)

    Bleser, Sebastian; Sanchez Lorente, Alicia; Steinen, Marcell [Helmholtz-Institut Mainz (Germany); Gerl, Juergen; Kojouharova, Jasmina; Kojouharov, Ivan [GSI Darmstadt (Germany); Iazzi, Felice [Politecnico, Torino (Italy); INFN, Torino (Italy); Pochodzalla, Josef; Rittgen, Kai; Sahin, Cihan [Institute for Nuclear Physics, JGU Mainz (Germany)

    2014-07-01

    The PANDA experiment, planned at the FAIR facility in Darmstadt, aims at the high resolution γ-spectroscopy of double Λ hypernuclei. For this purpose a devoted detector setup is required, consisting of a primary nuclear target, an active secondary target and a germanium detector array for the γ-spectroscopy. Due to the limited space within the PANDA detector a compact design is required. In particular the conventional LN{sub 2} cooling system must be replaced by an electro mechanical device and a new arrangement of the crystals is needed. This presentation shows the progress in the development of the germanium detectors. First results of in-beam measurements at COSY with a new electro mechanically cooled single crystal prototype are presented. Digital pulse shape analysis is used to disentangle pile up events due to the high event rate. This analysis technique also allows to recover the high original energy resolution in case of neutron damage. Finally the status of the new triple crystal detector prototype is given.

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

    Energy Technology Data Exchange (ETDEWEB)

    Doncel, M., E-mail: doncel@usal.e [Laboratorio de Radiaciones Ionizantes, Universidad de Salamanca (Spain); Recchia, F. [INFN sezione di Padova, Padova (Italy); Quintana, B. [Laboratorio de Radiaciones Ionizantes, Universidad de Salamanca (Spain); Gadea, A. [IFIC Valencia, Valencia (Spain); INFN Laboratori Nazionali di Legnaro, Legnaro (Italy); Farnea, E. [INFN sezione di Padova, Padova (Italy)

    2010-10-21

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

  9. Amorphous Silicon-Germanium Films with Embedded Nanocrystals for Thermal Detectors with Very High Sensitivity

    Directory of Open Access Journals (Sweden)

    Cesar Calleja

    2016-01-01

    Full Text Available We have optimized the deposition conditions of amorphous silicon-germanium films with embedded nanocrystals in a plasma enhanced chemical vapor deposition (PECVD reactor, working at a standard frequency of 13.56 MHz. The objective was to produce films with very large Temperature Coefficient of Resistance (TCR, which is a signature of the sensitivity in thermal detectors (microbolometers. Morphological, electrical, and optical characterization were performed in the films, and we found optimal conditions for obtaining films with very high values of thermal coefficient of resistance (TCR = 7.9% K−1. Our results show that amorphous silicon-germanium films with embedded nanocrystals can be used as thermosensitive films in high performance infrared focal plane arrays (IRFPAs used in commercial thermal cameras.

  10. Automatic energy calibration of germanium detectors using fuzzy set theory

    CERN Document Server

    Stezowski, O; Prevost, A; Smith, A G; Wall, R

    2002-01-01

    With the advent of multi-detector arrays, many tasks that are usually performed by physicists, such as energy calibration, become very time consuming. There is therefore a need to develop more and more complex algorithms able to mimic human expertise. Fuzzy logic proposes a theoretical framework to build algorithms that are close to the human way of thinking. In this paper we apply fuzzy set theory in order to develop an automatic procedure for energy calibration. The algorithm, based on fuzzy concepts, has been tested on data taken with the EUROBALL IV gamma-ray array.

  11. Monte Carlo uncertainty analysis of germanium detector response to gamma-rays with energies below 1 MeV

    NARCIS (Netherlands)

    Maleka, PP; Maucec, M

    2005-01-01

    Monte Carlo method was used to simulate the pulse-height response function of high-precision germanium (HPGe) detector for photon energies below 1 MeV. The calculations address the uncertainty estimation due to inadequate specifications of source positioning and to variations in the detector's physi

  12. Prospects of cold dark matter searches with an ultra-low-energy germanium detector

    CERN Document Server

    Wong, H T

    2007-01-01

    The report describes the research program on the development of ultra-low-energy germanium detectors, with emphasis on WIMP dark matter searches. A threshold of 100 eV is achieved with a 20 g detector array, providing a unique probe to the low-mas WIMP. Present data at a surface laboratory is expected to give rise to comparable sensitivities with the existing limits at the $\\rm{5 - 10 GeV}$ WIMP-mass range. The projected parameter space to be probed with a full-scale, kilogram mass-range experiment is presented. Such a detector would also allow the studies of neutrino-nucleus coherent scattering and neutrino magnetic moments.

  13. Measurement of the dead layer thickness in a p-type point contact germanium detector

    Science.gov (United States)

    Jiang, Hao; Yue, Qian; Li, Yu-Lan; Kang, Ke-Jun; Li, Yuan-Jing; Li, Jin; Lin, Shin-Ted; Liu, Shu-Kui; Ma, Hao; Ma, Jing-Lu; Su, Jian; Tsz-King Wong, Henry; Yang, Li-Tao; Zhao, Wei; Zeng, Zhi

    2016-09-01

    A 994 g mass p-type PCGe detector has been deployed during the first phase of the China Dark matter EXperiment, aiming at direct searches for light weakly interacting massive particles. Measuring the thickness of the dead layer of a p-type germanium detector is an issue of major importance since it determines the fiducial mass of the detector. This work reports a method using an uncollimated 133Ba source to determine the dead layer thickness. The experimental design, data analysis and Monte Carlo simulation processes, as well as the statistical and systematic uncertainties are described. A dead layer thickness of 1.02 mm was obtained based on a comparison between the experimental data and the simulated results. Supported by National Natural Science Foundation of China (10935005, 10945002, 11275107, 11175099)

  14. Evaluations of the commercial spectrometer systems for safeguards applications using the germanium detectors

    Energy Technology Data Exchange (ETDEWEB)

    Vo, D.T.

    1998-12-31

    Safeguards applications require the best spectrometer systems with excellent resolution, stability, and throughput. Instruments must perform well in all the situations and environments. Data communication to the computer should be convenient, fast, and reliable. The software should have all the necessary tools and be ease to use. Portable systems should be small in size, lightweight, and have a long battery life. Nine commercially available spectrometer systems are tested with both the planar and coaxial germanium detectors. Considering the performance of the Digital Signal Processors (DSP), digital-based spectroscopy may be the future of gamma-ray spectroscopy.

  15. Program LEP to addition of gamma spectra from germanium detectors; Programa LEPS para suma de espectros gammas de detectores de germanio

    Energy Technology Data Exchange (ETDEWEB)

    Romero, L.

    1986-07-01

    The LEP program, written in FORTRAN IV, performs the addition of two spectra, collected with different detectors, from the same sample. This application, adds the two gamma spectra obtained from two opposite LEPS Germanium Detectors (Low Energy Photon Spectrometer), correcting the differences (channel/energy) between both two spectra, and fitting them before adding. The total-spectrum is recorded at the computer memory as a single spectrum. The necessary equipment, to run this program is: - Two opposite germanium detectors, with their associate electronics. - Multichannel analyzer (2048 memory channel minimum) - Computer on-line interfacing to multichannel analyzer. (Author) 4 refs.

  16. Program LEP to addition of gamma spectra from germanium detectors; Programa LEPS para suma de espectros gammas de detectores de germanio

    Energy Technology Data Exchange (ETDEWEB)

    Romero, L.

    1986-07-01

    The LEP program, written in FORTRAN IV, performs the addition of two spectra, collected with different detectors, from the same sample. This application, adds the two gamma spectra obtained from two opposite LEPS Germanium Detectors (Low Energy Photon Spectrometer), correcting the differences (channel/energy) between both two spectra, and fitting them before adding. The total-spectrum is recorded at the computer memory as a single spectrum. The necessary equipment, to run this program is: - Two opposite germanium detectors, with their associate electronics. - Multichannel analyzer (2048 memory channel minimum) - Computer on-line interfacing to multichannel analyzer. (Author) 4 refs.

  17. CDMS Detector Fabrication Improvements and Low Energy Nuclear Recoil Measurements in Germanium

    Energy Technology Data Exchange (ETDEWEB)

    Jastram, Andrew [Texas A & M Univ., College Station, TX (United States)

    2015-12-01

    As the CDMS (Cryogenic Dark Matter Search) experiment is scaled up to tackle new dark matter parameter spaces (lower masses and cross-sections), detector production efficiency and repeatability becomes ever more important. A dedicated facility has been commissioned for SuperCDMS detector fabrication at Texas A&M University (TAMU). The fabrication process has been carefully tuned using this facility and its equipment. Production of successfully tested detectors has been demonstrated. Significant improvements in detector performance have been made using new fabrication methods, equipment, and tuning of process parameters. This work has demonstrated the capability for production of next generation CDMS SNOLAB detectors. Additionally, as the dark matter parameter space is probed further, careful calibrations of detector response to nuclear recoil interactions must be performed in order to extract useful information (in relation to dark matter particle characterzations) from experimental results. A neutron beam of tunable energy is used in conjunction with a commercial radiation detector to characterize ionization energy losses in germanium during nuclear recoil events. Data indicates agreement with values predicted by the Lindhard equation, providing a best-t k-value of 0.146.

  18. Development of a segmented n-type germanium detector, and its application to astronomical gamma-ray spectroscopy

    Science.gov (United States)

    Gehrels, N.; Cline, T. L.; Teegarden, B. J.; Tueller, J.; Leventhal, M.; Maccallum, C. J.; Ryge, P.

    1983-01-01

    Extensive calculations and simulations have shown that the instrumental background in a coaxial germanium photon detector flown at balloon altitudes or in space, can be substantially reduced by segmenting the outer contact. The contact is divided into horizontal strips around the side of the detector, giving it many characteristics similar to that of a stack of planar detectors. By choosing different segment coincidence requirements in different energy ranges, one can obtain a factor of approx. 2 increase in sensitivity to spectral lines between 40 keV and 1 MeV, compared with an unsegmented detector. The reverse electrode configuration (using n-type germanium), with the p contact outside, is preferred for this application due to its thin dead layer and resistance to radiation damage in space. A small two segment n type detector is being developed to serve as a prototype for larger multisegment devices. Results of this development effort and of detector tests are presented.

  19. Exploration Of Activity Measurements And Equilibrium Checks For Sediment Dating Using Thick-Window Germanium Detectors

    Science.gov (United States)

    Warner, Jacob A.; Fitzsimmons, Kathryn E.; Reynolds, Eva M.; Gladkis, Laura G.; Timmers, Heiko

    2011-06-01

    Activity measurements on sediment samples for trapped-charge geological dating using gamma-ray spectroscopy are an important verification of the field-site dose rate determination. Furthermore gamma-ray spectroscopy can check if the natural decay series are in secular equilibrium which is a crucial assumption in such dating. Typically the activities of leading members of the Thorium and Uranium decay series are measured, which requires Germanium detectors with thin windows and good energy resolution in order to effectively detect the associated low energy gamma-rays. Such equipment is not always readily available. The potential of conventional Germanium detectors with thick entrance window has been explored towards routine gamma-ray spectroscopy of sediment samples using higher energy gamma-rays. Alternative isotopes, such as Ac-228 and Pb-212 for the Thorium series, and Pa-234m, Ra-226 and Bi-214 for the Uranium series, have been measured in order to determine the mass-specific activity for the respective series and possibly provide a check of secular equilibrium. In addition to measurements of the K-40 activity, with the alternative approach, the activities of both decay series can be accurately determined. The secular equilibrium condition may be tested for the Thorium series. Measurement accuracy for Pa-234m is, however, not sufficient to permit also a reliable check of equilibrium for the Uranium series.

  20. Pulse shape analysis for segmented germanium detectors implemented in graphics processing units

    Energy Technology Data Exchange (ETDEWEB)

    Calore, Enrico, E-mail: enrico.calore@lnl.infn.it [INFN Laboratori Nazionali di Legnaro, Viale Dell' Università 2, I-35020 Legnaro, Padova (Italy); Bazzacco, Dino, E-mail: dino.bazzacco@pd.infn.it [INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy); Recchia, Francesco, E-mail: francesco.recchia@pd.infn.it [INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy); Dipartimento di Fisica e Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy)

    2013-08-11

    Position sensitive highly segmented germanium detectors constitute the state-of-the-art of the technology employed for γ-spectroscopy studies. The operation of large spectrometers composed of tens to hundreds of such detectors demands enormous amounts of computing power for the digital treatment of the signals. The use of Graphics Processing Units (GPUs) has been evaluated as a cost-effective solution to meet such requirements. Different implementations and the hardware constraints limiting the performance of the system are examined. -- Highlights: • We implemented the grid-search algorithm in OpenCL in order to be run on GPUs. • We compared its performances in respect to an optimized CPU implementation in C++. • We analyzed the results highlighting the most probable factors limiting their speed. • We propose some solutions to overcome their speed limits.

  1. Bulk and Surface Event Identification in p-type Germanium Detectors

    CERN Document Server

    Yang, L T; Jia, L P; Jiang, H; Li, J; Lin, F K; Lin, S T; Liu, S K; Ma, J L; Sharma, V; Singh, L; Singh, M K; Soma, A K; Yang, S W; Wang, L; Wang, Q; Wong, H T; Yue, Q; Zhao, W

    2016-01-01

    The p-type point-contact germanium detectors, due to its sub-keV sensitivities and low internal radioactivity background, are demonstrated to be competitive tools for light dark matter WIMPs searches and may have potential applications in neutrino physics. These detectors exhibit anomalous surface behavior, which has been characterized and dealt with in previous analysis. However, the analysis method rely on spectral shape assumptions and must use external calibration sources. In this report, we purpose an improved method, where in situ data could be used as calibration sources. Data from CDEX-1 and TEXONO experiments will be re-examined and the results are shown to be consistent with both analysis.

  2. Measurement of the cosmogenic activation of germanium detectors in EDELWEISS-III

    CERN Document Server

    Armengaud, E; Augier, C; Benoît, A; Bergé, L; Billard, J; Blümer, J; de Boissière, T; Broniatowski, A; Camus, P; Cazes, A; Chapellier, M; Charlieux, F; De Jésus, M; Dumoulin, L; Eitel, K; Foerster, N; Gascon, J; Giuliani, A; Gros, M; Hehn, L; Heuermann, G; Jin, Y; Juillard, A; Kéfélian, C; Kleifges, M; Kozlov, V; Kraus, H; Kudryavtsev, V A; Le-Sueur, H; Marnieros, S; Navick, X -F; Nones, C; Olivieri, E; Pari, P; Paul, B; Piro, M -C; Poda, D; Queguiner, E; Rozov, S; Sanglard, V; Schmidt, B; Scorza, S; Siebenborn, B; Tcherniakhovski, D; Vagneron, L; Weber, M; Yakushev, E

    2016-01-01

    We present a measurement of the cosmogenic activation in the germanium cryogenic detectors of the EDELWEISS III direct dark matter search experiment. The decay rates measured in detectors with different exposures to cosmic rays above ground are converted into production rates of different isotopes. The measured production rates in units of nuclei/kg/day are 82 $\\pm$ 21 for $^3$H, 2.8 $\\pm$ 0.6 for $^{49}$V, 4.6 $\\pm$ 0.7 for $^{55}$Fe, and 106 $\\pm$ 13 for $^{65}$Zn. These results are the most accurate for these isotopes. A lower limit on the production rate of $^{68}$Ge of 74 nuclei/kg/day is also presented. They are compared to model predictions present in literature and to estimates calculated with the ACTIVIA code.

  3. Improved Multinuclide Imaging of Special Nuclear Material Using a High Purity Germanium Double Sided Strip Detector

    Science.gov (United States)

    2005-06-01

    CAMAC Interface: The CAMAC interface is the means of communication with the DGF-4C. 30 Input logic unit [11] The input logic unit used is an...Initially, only a single DGF-4C module was used to verify that the communication with the host computer was functioning properly. All internal jumper...Appendix A. Collimator Design Code Graphics’Graphics’ Purpose: This code is used to help design efective collimators for imaging special mm

  4. Background intercomparison with escape-suppressed germanium detectors in underground mines

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-07-01

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

  5. Demonstration of Surface Electron Rejection with Interleaved Germanium Detectors for Dark Matter Search

    CERN Document Server

    Agnese, R; Balakishiyeva, D; Thakur, R Basu; Bauer, D A; Borgland, A; Brandt, D; Brink, P L; Bunker, R; Cabrera, B; Caldwell, D O; Cerdeno, D G; Chagani, H; Cherry, M; Cooley, J; Cornell, B; Crewdson, C H; Cushman, P; Daal, M; Di Stefano, P C F; Silva, E Do Couto E; Doughty, T; Esteban, L; Fallows, S; Figueroa-Feliciano, E; Fox, J; Fritts, M; Godfrey, G L; Golwala, S R; Hall, J; Harris, H R; Hasi, J; Hertel, S A; Hines, B A; Hofer, T; Holmgren, D; Hsu, L; Huber, M E; Jastram, A; Kamaev, O; Kara, B; Kelsey, M H; Kenany, S A; Kennedy, A; Kenney, C J; Kiveni, M; Koch, K; Loer, B; Asamar, E Lopez; Mahapatra, R; Mandic, V; Martinez, C; McCarthy, K A; Mirabolfathi, N; Moffatt, R A; Moore, D C; Nadeau, P; Nelson, R H; Novak, L; Page, K; Partridge, R; Pepin, M; Phipps, A; Prasad, K; Pyle, M; Qiu, H; Radpour, R; Rau, W; Redl, P; Reisetter, A; Resch, R W; Ricci, Y; Saab, T; Sadoulet, B; Sander, J; Schmitt, R; Schneck, K; Schnee, R W; Scorza, S; Seitz, D; Serfass, B; Shank, B; Speller, D; Tomada, A; Villano, A N; Welliver, B; Wright, D H; Yellin, S; Yen, J J; Young, B A; Zhang, J

    2013-01-01

    SuperCDMS, a direct search for WIMPs, is currently operating a 9-kg array of cryogenic germanium (Ge) detectors in the Soudan Underground Laboratory. These detectors, known as iZIPs, use ionization and phonon sensors placed symmetrically on both sides of a Ge crystal to measure both charge and athermal phonons from each particle interaction. The information from each event provides excellent discrimination between electron recoils and nuclear recoils, as well as discrimination between events on the detector surface and those in the interior. To demonstrate the surface electron rejection capabilities, two $^{210}$Pb sources were installed facing detectors, producing $\\sim$130 beta decays/hr. In $\\sim$800 live hours, no events leaked into the WIMP signal region in the recoil energy range 8--115 keVr, providing an upper limit to the surface event leakage fraction of $1.7 \\times 10^{-5}$ at 90% C.L. This rejection factor demonstrates that surface electrons would produce $< 0.6$ event background in the 0.3 ton-...

  6. Real-time digital signal processor implementation of self-calibrating pulse-shape discriminator for high purity germanium

    CERN Document Server

    Suarez, R; Aalseth, C E; Hossbach, T W; Miley, H S

    2007-01-01

    Pulse-shape analysis of the ionization signals from germanium gamma-ray spectrometers is a method for obtaining information that can characterize an event beyond just the total energy deposited in the crystal. However, as typically employed, this method is data-intensive requiring the digitization, transfer, and recording of electronic signals from the spectrometer. A hardware realization of a real-time digital signal processor for implementing a parametric pulse shape is presented. Specifically, a previously developed method for distinguishing between single-site and multi-site gamma-ray interactions is demonstrated in an on-line digital signal processor, compared with the original off-line pulse-shape analysis routine, and shown to have no significant difference. Reduction of the amount of the recorded information per event is shown to translate into higher duty-cycle data acquisition rates while retaining the benefits of additional event characterization from pulse-shape analysis.

  7. Demonstration of surface electron rejection with interleaved germanium detectors for dark matter searches

    Energy Technology Data Exchange (ETDEWEB)

    Agnese, R.; Balakishiyeva, D.; Saab, T.; Welliver, B. [Department of Physics, University of Florida, Gainesville, Florida 32611 (United States); Anderson, A. J.; Figueroa-Feliciano, E.; Hertel, S. A.; McCarthy, K. A. [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Basu Thakur, R. [Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States); Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illnois 61801 (United States); Bauer, D. A.; Holmgren, D.; Hsu, L.; Loer, B.; Schmitt, R. [Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States); Borgland, A.; Brandt, D.; Brink, P. L.; Do Couto E Silva, E.; Godfrey, G. L.; Hasi, J. [SLAC National Accelerator Laboratory/Kavli Institute for Particle Astrophysics and Cosmology, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Collaboration: The SuperCDMS Collaboration; and others

    2013-10-14

    The SuperCDMS experiment in the Soudan Underground Laboratory searches for dark matter with a 9-kg array of cryogenic germanium detectors. Symmetric sensors on opposite sides measure both charge and phonons from each particle interaction, providing excellent discrimination between electron and nuclear recoils, and between surface and interior events. Surface event rejection capabilities were tested with two {sup 210}Pb sources producing ∼130 beta decays/hr. In ∼800 live hours, no events leaked into the 8–115 keV signal region, giving upper limit leakage fraction 1.7 × 10{sup −5} at 90% C.L., corresponding to < 0.6 surface event background in the future 200-kg SuperCDMS SNOLAB experiment.

  8. Measurement of 238U muonic x-rays with a germanium detector setup

    Energy Technology Data Exchange (ETDEWEB)

    Esch, Ernst I [Los Alamos National Laboratory; Jason, Andrew [Los Alamos National Laboratory; Miyadera, Haruo [Los Alamos National Laboratory; Hoteling, Nathan J [Los Alamos National Laboratory; Heffner, Robert H [Los Alamos National Laboratory; Adelmann, Andreas [PAUL SCHERRER INSTITUT; Stocki, Trevor [HEALTH CANADA; Mitchell, Lee [NAVAL RESEARCH LAB

    2009-01-01

    In the field of nuclear non-proliferation muon interactions with materials are of great interest. This paper describes an experiment conducted at the Paul Scherrer Institut (PSI) in Switzerland where a muon beam is stopped in a uranium target. The muons produce characteristic muonic x-rays. Muons will penetrate shielding easily and the produced characteristic x-rays can be used for positive isotope identification. Furthermore, the x-rays for uranium isotopes lie in the energy range of 6-7 MeV, which allows them to have an almost optimal mean free path in heavy shielding such as lead or steel. A measurement was conducted at PSI to prove the feasibility of detecting muonic x-rays from a large sample of depleted uranium (several kilograms) with a germanium detector. In this paper, the experimental setup and analysis of the measurement itself is presented.

  9. Demonstration of Surface Electron Rejection with Interleaved Germanium Detectors for Dark Matter Searches

    Energy Technology Data Exchange (ETDEWEB)

    Agnese, R.; Anderson, A. J.; Balakishiyeva, D.; Basu Thakur, R.; Bauer, D. A.; Borgland, A.; Brandt, D.; Brink, P. L.; Bunker, R.; Cabrera, B.; Caldwell, D. O.; Cerdeno, D. G.; Chagani, H.; Cherry, M.; Cooley, J.; Cornell, B.; Crewdson, C. H.; Cushman, Priscilla B.; Daal, M.; Di Stefano, P. C.; Do Couto E Silva, E.; Doughty, T.; Esteban, L.; Fallows, S.; Figueroa-Feliciano, E.; Fox, J.; Fritts, M.; Godfrey, G. L.; Golwala, S. R.; Hall, Jeter C.; Harris, H. R.; Hasi, J.; Hertel, S. A.; Hines, B. A.; Hofer, T.; Holmgren, D.; Hsu, L.; Huber, M. E.; Jastram, A.; Kamaev, O.; Kara, B.; Kelsey, M. H.; Kenany, S.; Kennedy, A.; Kenney, C. J.; Kiveni, M.; Koch, K.; Loer, B.; Lopez Asamar, E.; Mahapatra, R.; Mandic, V.; Martinez, C.; McCarthy, K. A.; Mirabolfathi, N.; Moffatt, R. A.; Moore, D. C.; Nadeau, P.; Nelson, R. H.; Novak, L.; Page, K.; Partridge, R.; Pepin, M.; Phipps, A.; Prasad, K.; Pyle, M.; Qiu, H.; Radpour, R.; Rau, W.; Redl, P.; Reisetter, A.; Resch, R. W.; Ricci, Y.; Saab, T.; Sadoulet, B.; Sander, J.; Schmitt, R.; Schneck, K.; Schnee, Richard; Scorza, S.; Seitz, D.; Serfass, B.; Shank, B.; Speller, D.; Tomada, A.; Villano, A. N.; Welliver, B.; Wright, D. H.; Yellin, S.; Yen, J. J.; Young, B. A.; Zhang, J.

    2013-10-17

    The SuperCDMS experiment in the Soudan Underground Laboratory searches for dark matter with a 9-kg array of cryogenic germanium detectors. Symmetric sensors on opposite sides measure both charge and phonons from each particle interaction, providing excellent discrimination between electron and nuclear recoils, and between surface and interior events. Furthermore, surface event rejection capabilities were tested with two 210Pb sources producing ~130 beta decays/hr. We found that in ~800 live hours, no events leaked into the 8–115 keV signal region, giving upper limit leakage fraction 1.7 x 10-5 at 90% C.L., corresponding to<0.6 surface event background in the future 200-kg SuperCDMS SNOLAB experiment.

  10. Study of the inactive layer of a germanium detector: experimental and Monte Carlo simulation treatments

    Energy Technology Data Exchange (ETDEWEB)

    Zevallos-Chavez, Juan Y.; Pires, Carlos Augusto; Zahn, Guilherme Soares [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)]. E-mail: juan@if.usp.br; Genezini, Frederico Antonio [Centro Regional de Ciencias Nucleares (CRCN), Recife, PE (Brazil)). E-mail: Cruz, Manoel Tiago F. da (Sao Paulo Univ., SP (Brazil). Inst. de Fisica

    2005-07-01

    The detection efficiency of a Germanium detector was measured in the energy range of 80 keV up to 1 MeV. A model function to fit the efficiency data was used, containing an absorbing window factor. The results were compared with a Monte Carlo simulation of the photon interactions where, the nominal dimensions were varied in order to check the low-energy behavior of the efficiency curve. The Monte Carlo results showed to be in good agreement with the experimental ones when the nominal dimensions of the crystal, except for its dead layer thickness, were used. This difference in the dead layer was attributed to its non-uniformity. (author)

  11. Large-aperture germanium detector package for picosecond photon counting in the 0.5-1.6-microm range.

    Science.gov (United States)

    Prochazka, I; Hamal, K; Greene, B; Kunimori, H

    1996-09-01

    We report the design, construction, and parameters of a detector package based on a germanium avalanche photodiode operated in the Geiger mode cooled to 77 K. The new design of the active quenching circuit, proper diode structure, and cryogenic cooling setup permitted us to increase the detector's active area to 0.1-mm diameter while maintaining an acceptable dark-count rate, timing resolution, and photon-counting sensitivity at 1.54 microm. The active-area size and the compact design of the detector package permitted its application in satellite laser ranging at 0.532- and 1.543-microm wavelengths, yielding subcentimeter ranging precision.

  12. Characterization and performance of germanium detectors with sub-keV sensitivities for neutrino and dark matter experiments

    Science.gov (United States)

    Soma, A. K.; Singh, M. K.; Singh, L.; Kumar, G. Kiran; Lin, F. K.; Du, Q.; Jiang, H.; Liu, S. K.; Ma, J. L.; Sharma, V.; Wang, L.; Wu, Y. C.; Yang, L. T.; Zhao, W.; Agartioglu, M.; Asryan, G.; Chang, Y. Y.; Chen, J. H.; Chuang, Y. C.; Deniz, M.; Hsu, C. L.; Hsu, Y. H.; Huang, T. R.; Jia, L. P.; Kerman, S.; Li, H. B.; Li, J.; Liao, F. T.; Liao, H. Y.; Lin, C. W.; Lin, S. T.; Marian, V.; Ruan, X. C.; Sevda, B.; Shen, Y. T.; Singh, M. K.; Singh, V.; Sonay, A.; Su, J.; Subrahmanyam, V. S.; Tseng, C. H.; Wang, J. J.; Wong, H. T.; Xu, Y.; Yang, S. W.; Yu, C. X.; Yue, Q.; Zeyrek, M.

    2016-11-01

    Germanium ionization detectors with sensitivities as low as 100 eVee (electron-equivalent energy) open new windows for studies on neutrino and dark matter physics. The relevant physics subjects are summarized. The detectors have to measure physics signals whose amplitude is comparable to that of pedestal electronic noise. To fully exploit this new detector technique, various experimental issues including quenching factors, energy reconstruction and calibration, signal triggering and selection as well as evaluation of their associated efficiencies have to be attended. The efforts and results of a research program to address these challenges are presented.

  13. Radial position of single-site gamma-ray interactions from a parametric pulse shape analysis of germanium detector signals

    CERN Document Server

    Orrell, J L; Cooper, M W; Kephart, J D; Seifert, C E; Orrell, John L.; Aalseth, Craig E.; Cooper, Matthew W.; Kephart, Jeremy D.; Seifert, Carolyn E.

    2007-01-01

    Pulse shape analysis of germanium gamma-ray spectrometer signals can yield information on the radial position of individual gamma-ray interactions within the germanium crystal. A parametric pulse shape analysis based on calculation of moments of the reconstructed current pulses from a closed-ended coaxial germanium detector is used to preferentially select single-site gamma-ray interactions. The double escape peak events from the 2614.5 keV gamma-ray of 208-Tl are used as a training set to optimize the single-site event selection region in the pulse shape parameter space. A collimated source of 320.1 keV gamma-rays from 51-Cr is used to scan different radial positions of the same semi-coaxial germanium detector. The previously trained single-site selection region is used to preferentially identify the single-site photoelectric absorption events from the 320.1 keV full-energy peak. From the identified events, a comparison of the pulse shape parameter space distributions between different scan positions allows ...

  14. Limits on Light WIMPs with a Germanium Detector at 172 eVee threshold at the China Jinping Underground Laboratory

    CERN Document Server

    Liu, S K; Kang, K J; Cheng, J P; Wong, H T; Li, Y J; Lin, S T; Chang, J P; Chen, N; Chen, Q H; Chen, Y H; Chuang, Y C; Deng, Z; Du, Q; Gong, H; Hao, X Q; He, H J; He, Q J; Huang, H X; Huang, T R; Jiang, H; Li, H B; Li, J M; Li, J; Li, X; Li, X Q; Li, X Y; Li, Y L; Liao, H Y; Lin, F K; Lü, L C; Ma, H; Mao, S J; Qin, J Q; Ren, J; Ruan, X C; Shen, M B; Singh, L; Singh, M K; Soma, A K; Su, J; Tang, C J; Tseng, C H; Wang, J M; Wang, L; Wang, Q; Wu, S Y; Wu, Y C; Xianyu, Z Z; Xiao, R Q; Xing, H Y; Xu, F Z; Xu, Y; Xu, X J; Xue, T; Yang, C W; Yang, L T; Yang, S W; Yi, N; Yu, C X; Yu, H; Yu, X Z; Zeng, X H; Zeng, Z; Zhang, L; Zhang, Y H; Zhao, M G; Zhao, W; Zhou, Z Y; Zhu, J J; Zhu, W B; Zhu, X Z; Zhu, Z H

    2014-01-01

    The China Dark Matter Experiment reports results on light WIMP dark matter searches at the China Jinping Underground Laboratory with a germanium detector array with a total mass of 20 g. The physics threshold achieved is 172 eVee at 50% signal efficiency. With 0.784 kg-days of data, exclusion region on spin-independent coupling with the nucleon is derived, improving over our earlier bounds at WIMP mass less than 4.6 GeV.

  15. A germanium hybrid pixel detector with 55μm pixel size and 65,000 channels

    Science.gov (United States)

    Pennicard, D.; Struth, B.; Hirsemann, H.; Sarajlic, M.; Smoljanin, S.; Zuvic, M.; Lampert, M. O.; Fritzsch, T.; Rothermund, M.; Graafsma, H.

    2014-12-01

    Hybrid pixel semiconductor detectors provide high performance through a combination of direct detection, a relatively small pixel size, fast readout and sophisticated signal processing circuitry in each pixel. For X-ray detection above 20 keV, high-Z sensor layers rather than silicon are needed to achieve high quantum efficiency, but many high-Z materials such as GaAs and CdTe often suffer from poor material properties or nonuniformities. Germanium is available in large wafers of extremely high quality, making it an appealing option for high-performance hybrid pixel X-ray detectors, but suitable technologies for finely pixelating and bump-bonding germanium have not previously been available. A finely-pixelated germanium photodiode sensor with a 256 by 256 array of 55μm pixels has been produced. The sensor has an n-on-p structure, with 700μm thickness. Using a low-temperature indium bump process, this sensor has been bonded to the Medipix3RX photoncounting readout chip. Tests with the LAMBDA readout system have shown that the detector works successfully, with a high bond yield and higher image uniformity than comparable high-Z systems. During cooling, the system is functional around -80°C (with warmer temperatures resulting in excessive leakage current), with -100°C sufficient for good performance.

  16. A Search of Low-Mass WIMPs with p-type Point Contact Germanium Detector in the CDEX-1 Experiment

    CERN Document Server

    Zhao, W; Kang, K J; Cheng, J P; Li, Y J; Wong, H T; Lin, S T; Chang, J P; Chen, J H; Chen, Q H; Chen, Y H; Deng, Z; Du, Q; Gong, H; Hao, X Q; He, H J; He, Q J; Huang, H X; Huang, T R; Jiang, H; Li, H B; Li, J; Li, J M; Li, X; Li, X Y; Li, Y L; Lin, F K; Liu, S K; Lü, L C; Ma, H; Ma, J L; Mao, S J; Qin, J Q; Ren, J; Ruan, X C; Sharma, V; Shen, M B; Singh, L; Singh, M K; Soma, A K; Su, J; Tang, C J; Wang, J M; Wang, L; Wang, Q; Wu, S Y; Wu, Y C; Xianyu, Z Z; Xiao, R Q; Xing, H Y; Xu, F Z; Xu, Y; Xu, X J; Xue, T; Yang, L T; Yang, S W; Yi, N; Yu, C X; Yu, H; Yu, X Z; Zeng, M; Zeng, X H; Zeng, Z; Zhang, L; Zhang, Y H; Zhao, M G; Zhou, Z Y; Zhu, J J; Zhu, W B; Zhu, X Z; Zhu, Z H

    2016-01-01

    The CDEX-1 experiment conducted a search of low-mass (< 10 GeV/c2) Weakly Interacting Massive Particles (WIMPs) dark matter at the China Jinping Underground Laboratory using a p-type point-contact germanium detector with a fiducial mass of 915 g at a physics analysis threshold of 475 eVee. We report the hardware set-up, detector characterization, data acquisition and analysis procedures of this experiment. No excess of unidentified events are observed after subtraction of known background. Using 335.6 kg-days of data, exclusion constraints on the WIMP-nucleon spin-independent and spin-dependent couplings are derived.

  17. The 14N(p,gamma)15O reaction studied with a composite germanium detector

    CERN Document Server

    Marta, M; Bemmerer, D; Broggini, C; Caciolli, A; Corvisiero, P; Costantini, H; Elekes, Z; Fulop, Zs; Gervino, G; Guglielmetti, A; Gustavino, C; Gyurky, Gy; Imbriani, G; Junker, M; Lemut, A; Limata, B; Mazzocchi, C; Menegazzo, R; Prati, P; Roca, V; Rolfs, C; Alvarez, C Rossi; Somorjai, E; Straniero, O; Strieder, F; Terrasi, F; Trautvetter, H P; Vomiero, A

    2011-01-01

    The rate of the carbon-nitrogen-oxygen (CNO) cycle of hydrogen burning is controlled by the 14N(p,gamma)15O reaction. The reaction proceeds by capture to the ground states and several excited states in O-15. In order to obtain a reliable extrapolation of the excitation curve to astrophysical energy, fits in the R-matrix framework are needed. In an energy range that sensitively tests such fits, new cross section data are reported here for the four major transitions in the 14N(p,gamma)15O reaction. The experiment has been performed at the Laboratory for Underground Nuclear Astrophysics (LUNA) 400 kV accelerator placed deep underground in the Gran Sasso facility in Italy. Using a composite germanium detector, summing corrections have been considerably reduced with respect to previous studies. The cross sections for capture to the ground state and to the 5181, 6172, and 6792 keV excited states in O-15 have been determined at 359, 380, and 399 keV beam energy. In addition, the branching ratios for the decay of the...

  18. Ge/GaAs heterostructure matrix detector

    Energy Technology Data Exchange (ETDEWEB)

    Kostamo, P. [Optoelectronics Laboratory, Helsinki University of Technology, P.O. Box 3500, 02015 HUT (Finland)]. E-mail: pasi.kostamo@hut.fi; Saeynaetjoki, A. [Optoelectronics Laboratory, Helsinki University of Technology, P.O. Box 3500, 02015 HUT (Finland); Knuuttila, L. [Optoelectronics Laboratory, Helsinki University of Technology, P.O. Box 3500, 02015 HUT (Finland); Lipsanen, H. [Optoelectronics Laboratory, Helsinki University of Technology, P.O. Box 3500, 02015 HUT (Finland); Andersson, H. [Oxford Instruments Analytical Oy (United Kingdom); Banzuzi, K. [Oxford Instruments Analytical Oy (United Kingdom); Nenonen, S. [Oxford Instruments Analytical Oy (United Kingdom); Sipilae, H. [Oxford Instruments Analytical Oy (United Kingdom); Vaijaervi, S. [Oxford Instruments Analytical Oy (United Kingdom); Lumb, D. [Science Payload and Advanced Concepts Office, ESA/ESTEC, Nordwijk (Netherlands)

    2006-07-01

    In this paper we present a novel germanium/gallium arsenide heterostructure X-ray detector with the active volume of germanium. The heterostructure is fabricated by depositing a gallium arsenide layer on a high-purity germanium wafer in a vertical metalorganic vapor-phase epitaxy system. This approach provides a new alternative to traditional lithium diffused n+ contact which is not easily applicable for finely pixelated detectors. The detector chip fabrication utilizing this kind of heterostructure is straightforward and only standard lithographic processes need to be applied. Electrical properties of the small format detector matrices are studied. Very low reverse biased current at 77 K is observed. It is concluded that the diffusion of arsenic in germanium results in an n-type germanium layer under the epitaxial gallium arsenide.

  19. GELATIO: a general framework for modular digital analysis of high-purity Ge detector signals

    CERN Document Server

    Agostini, M; Zavarise, P; Volynets, O

    2011-01-01

    GELATIO is a new software framework for advanced data analysis and digital signal processing developed for the GERDA neutrinoless double beta decay experiment. The framework is tailored to handle the full analysis flow of signals recorded by high purity Ge detectors and photo-multipliers from the veto counters. It is designed to support a multi-channel modular and flexible analysis, widely customizable by the user either via human-readable initialization files or via a graphical interface. The framework organizes the data into a multi-level structure, from the raw data up to the condensed analysis parameters, and includes tools and utilities to handle the data stream between the different levels. GELATIO is implemented in C++. It relies upon ROOT and its extension TAM, which provides compatibility with PROOF, enabling the software to run in parallel on clusters of computers or many-core machines. It was tested on different platforms and benchmarked in several GERDA-related applications. A stable version is pr...

  20. Limits on light WIMPs with a germanium detector at 177 eVee threshold at the China Jinping Underground Laboratory

    Science.gov (United States)

    Liu, S. K.; Yue, Q.; Kang, K. J.; Cheng, J. P.; Wong, H. T.; Li, Y. J.; Lin, S. T.; Chang, J. P.; Chen, N.; Chen, Q. H.; Chen, Y. H.; Chuang, Y. C.; Deng, Z.; Du, Q.; Gong, H.; Hao, X. Q.; He, H. J.; He, Q. J.; Huang, H. X.; Huang, T. R.; Jiang, H.; Li, H. B.; Li, J. M.; Li, J.; Li, J.; Li, X.; Li, X. Q.; Li, X. Y.; Li, Y. L.; Liao, H. Y.; Lin, F. K.; Lü, L. C.; Ma, H.; Mao, S. J.; Qin, J. Q.; Ren, J.; Ren, J.; Ruan, X. C.; Shen, M. B.; Singh, L.; Singh, M. K.; Soma, A. K.; Su, J.; Tang, C. J.; Tseng, C. H.; Wang, J. M.; Wang, L.; Wang, Q.; Wu, S. Y.; Wu, Y. C.; Wu, Y. C.; Xianyu, Z. Z.; Xiao, R. Q.; Xing, H. Y.; Xu, F. Z.; Xu, Y.; Xu, X. J.; Xue, T.; Yang, C. W.; Yang, L. T.; Yang, S. W.; Yi, N.; Yu, C. X.; Yu, H.; Yu, X. Z.; Zeng, X. H.; Zeng, Z.; Zhang, L.; Zhang, Y. H.; Zhao, M. G.; Zhao, W.; Zhou, Z. Y.; Zhu, J. J.; Zhu, W. B.; Zhu, X. Z.; Zhu, Z. H.; CDEX Collaboration

    2014-08-01

    The China Dark Matter Experiment reports results on light WIMP dark matter searches at the China Jinping Underground Laboratory with a germanium detector array with a total mass of 20 g. The physics threshold achieved is 177 eVee ("ee" represents electron equivalent energy) at 50% signal efficiency. With 0.784 kg-days of data, exclusion region on spin-independent coupling with the nucleon is derived, improving over our earlier bounds at WIMP mass less than 4.6 GeV.

  1. Differentiation of Bulk and Surface Events in p-type Point-Contact Germanium Detectors for Light WIMP Searches

    CERN Document Server

    Li, H B

    2013-01-01

    The p-type point-contact germanium detectors are novel techniques offering kg-scale radiation sensors with sub-keV sensitivities. They have been used for light Dark Matter WIMPs searches and may have potential applications in neutrino physics. There are, however, anomalous surface behaviour which needs to be characterized and understood. We describe the methods and results of a research program whose goals are to identify the bulk and surface events via software pulse shape analysis techniques, and to devise calibration schemes to evaluate the selection efficiency factors. Efficiencies-corrected background spectra from the low-background facility at Kuo-Sheng Neutrino Laboratory are derived.

  2. Germanium detector test-stands at the Max Planck Institute for Physics and alpha interactions on passivated surfaces

    Science.gov (United States)

    Gooch, C.; Garbini, L.; Abt, I.; Schulz, O.; Palermo, M.; Majorovits, B.; Liao, H.-Y.; Liu, X.; Seitz, H.

    2015-05-01

    The GeDetgroup at the Max Planck Institute for Physics in Munich, Germany, operates a number of test stands in order to conduct research on novel germanium detectors. The test stands are of a unique design and construction that provide the ability to probe the properties of new detector types. The GALATEA test stand was especially designed for surface scans, specifically a-induced surface events, a problem faced in low background experiments due to unavoidable surface contamination of detectors. A special 19-fold segmented coaxial prototype detector has already been investigated inside GALATEA with an a-source. A top surface scan provided insight into the physics underneath the passivation layer. Detector segmentation provides a direct path towards background identification and characterisation. With this in mind, a 4-fold segmentation scheme was implemented on a broad-energy point-contact detector and is being investigated inside the groups K1 test stand. A cryogenic test-stand where detectors can be submerged directly in liquid nitrogen or argon is also available. The goal is to establish segmentation as a viable option to reduce background in future large scale experiments.

  3. Status of the Germanium Detector Array (GERDA) in the search of neutrinoless ββ decays of 76Ge at LNGS

    Science.gov (United States)

    Schönert, S.; Abt, I.; Altmann, M.; Bakalyarov, A. M.; Barabanov, I.; Bauer, C.; Bauer, M.; Bellotti, E.; Belogurov, S.; Belyaev, S. T.; Bettini, A.; Bezrukov, L.; Brudanin, V.; Bolotsky, V. P.; Caldwell, A.; Cattadori, C.; Chirchenko, M. V.; Chkvorets, O.; Demidova, E.; di Vacri, A.; Eberth, J.; Egorov, V.; Farnea, E.; Gangapshev, A.; Gasparro, J.; Grabmayr, P.; Grigoriev, G. Y.; Gurentsov, V.; Gusev, K.; Hampel, W.; Heusser, G.; Heisel, M.; Hofmann, W.; Hult, M.; Inzhechik, L. V.; Jochum, J.; Junker, M.; Katulina, S.; Kiko, J.; Kirpichnikov, I. V.; Klimenko, A.; Knapp, M.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kröninger, K.; Kuzminov, V. V.; Laubenstein, M.; Lebedev, V. I.; Liu, X.; Majorovits, B.; Marissens, G.; Nemchenok, I.; Pandola, L.; Peiffer, P.; Pullia, A.; Alvarez, C. R.; Sandukovsky, V.; Scholl, S.; Schreiner, J.; Schwan, U.; Schwingenheuer, B.; Simgen, H.; Smolnikov, A.; Stelzer, F.; Tikhomirov, A. V.; Tomei, C.; Ur, C. A.; Vasenko, A. A.; Vasiliev, S.; Weißhaar, D.; Wojcik, M.; Yanovich, E.; Yurkowski, J.; Zhukov, S. V.; Zocca, F.; Zuzel, G.

    2006-12-01

    The Germanium Detector Array (GERDA) in the search for neutrinoless ββ decays of 76Ge at LNGS will operate bare germanium diodes enriched in 76Ge in an (optional active) cryogenic fluid shield to investigate neutrinoless ββ decay with a sensitivity of T 1/2 > 2 × 1026 yr after an exposure of 100 kg yr. Recent progress includes the installation of the first underground infrastructures at Gran Sasso, the completion of the enrichment of 37.5 kg of germanium material for detector construction, prototyping of low-mass detector support and contacts, and front-end and DAQ electronics, as well as the preparation for construction of the cryogenic vessel and water tank.

  4. CoGeNT: A Search for Low-Mass Dark Matter using p-type Point Contact Germanium Detectors

    CERN Document Server

    Aalseth, C E; Colaresi, J; Collar, J I; Leon, J Diaz; Fast, J E; Fields, N E; Hossbach, T W; Knecht, A; Kos, M S; Marino, M G; Miley, H S; Miller, M L; Orrell, J L; Yocum, K M

    2013-01-01

    CoGeNT employs p-type point-contact (PPC) germanium detectors to search for Weakly Interacting Massive Particles (WIMPs). By virtue of its low energy threshold and ability to reject surface backgrounds, this type of device allows an emphasis on low-mass dark matter candidates (WIMP mass around 10 GeV/c2). We report on the characteristics of the PPC detector presently taking data at the Soudan Underground Laboratory, elaborating on aspects of shielding, data acquisition, instrumental stability, data analysis, and background estimation. A detailed background model is used to investigate the low energy excess of events previously reported, and to assess the possibility of temporal modulations in the low-energy event rate. We conclude that the technique is ideally suited to search for the annual modulation signature expected from dark matter particle interactions in the region of WIMP mass and coupling favored by the DAMA/LIBRA claim.

  5. Characterization of a broad energy germanium detector and application to neutrinoless double beta decay search in Ge-76

    CERN Document Server

    Agostini, M; Brugnera, R; Cattadori, C M; D'Andragora, A; di Vacri, A; Garfagnini, A; Laubenstein, M; Pandola, L; Ur, C A

    2010-01-01

    The performance of a 630 g commercial broad energy germanium (BEGe) detector has been systematically investigated. Energy resolution, linearity, stability vs. high-voltage (HV) bias, thickness and uniformity of dead layers have been measured and found to be excellent. Special attention has been dedicated to the study of the detector response as a function of bias HV. The nominal depletion voltage being 3000 V, the detector under investigation shows a peculiar behavior for biases around 2000 V: in a narrow range of about 100 V the charge collection is strongly reduced. The detector seems to be composed by two parts: a small volume around the HV contact where charges are efficiently collected as at higher voltage, and a large volume where charges are poorly collected. A qualitative explanation of this behavior is presented. An event-by-event pulse shape analysis based on A/E (maximum amplitude of the current pulse over the total energy released in the detector) has been applied to events in different energy reg...

  6. Focusing of a new germanium counter type : the composite detector. Uses of the TREFLE detector in the EUROGAM multidetector; Mise au point d`un nouveau type de compteur germanium: le detecteur composite. Utilisation du detecteur TREFLE dans le multidetecteur EUROGAM

    Energy Technology Data Exchange (ETDEWEB)

    Han, L.

    1995-05-01

    The aim of this thesis is the development of new types of germanium detectors: the composite detectors. Two types of prototypes are then conceived: the stacked planar detector (EDP) and the assembly of coaxial diodes (TREFLE). They are designed for the multidetector EUROGAM destined to the research of nuclear structure at high angular momentum. The four planar diodes of EDP detector were of 7 cm diameter and of 15 to 20 mm thick. The difference between the calculated and measured photopic efficiency is observed. The importance of surface channel induces a weak resistance of neutron damages. The sputtering method for the surface treatment reducing the germanium dead layer as well as a rule of selection concerning the impurity concentration and the thickness of crystal is helpful for the later production of germanium detector. The CLOVER detector consist of for mean size crystals in the same cryostat. The photopic efficiency is much larger than that of the greatest monocrystal detector. And the granulation of composite detector allowed the Doppler broadening correction of gamma ray observed in the nuclear reaction where the recoil velocity is very high. This new type of detector enable the linear polarization measurement of gamma ray. Twenty-four CLOVER detector are actually mounted in the EUROGAM array. The characteristics measured in source as well as in beam, reported in this thesis, meet exactly the charge account. (author). 47 refs., 61 figs., 18 tabs.

  7. Infrared microspectroscopic imaging using a large radius germanium internal reflection element and a focal plane array detector.

    Science.gov (United States)

    Patterson, Brian M; Havrilla, George J; Marcott, Curtis; Story, Gloria M

    2007-11-01

    Previously, we established the ability to collect infrared microspectroscopic images of large areas using a large radius hemisphere internal reflection element (IRE) with both a single point and a linear array detector. In this paper, preliminary work in applying this same method to a focal plane array (FPA) infrared imaging system is demonstrated. Mosaic tile imaging using a large radius germanium hemispherical IRE on a FPA Fourier transform infrared microscope imaging system can be used to image samples nearly 1.5 mm x 2 mm in size. A polymer film with a metal mask is imaged using this method for comparison to previous work. Images of hair and skin samples are presented, highlighting the complexity of this method. Comparisons are made between the linear array and FPA methods.

  8. Atomic ionization by sterile-to-active neutrino conversion and constraints on dark matter sterile neutrinos with germanium detectors

    Science.gov (United States)

    Chen, Jiunn-Wei; Chi, Hsin-Chang; Lin, Shin-Ted; Liu, C.-P.; Singh, Lakhwinder; Wong, Henry T.; Wu, Chih-Liang; Wu, Chih-Pan

    2016-05-01

    The transition magnetic moment of a sterile neutrino can give rise to its conversion to an active neutrino through radiative decay or nonstandard interaction (NSI) with matter. For sterile neutrinos of keV-mass as dark matter candidates, their decay signals are actively searched for in cosmic x-ray spectra. In this work, we consider the NSI that leads to atomic ionization, which can be detected by direct dark matter experiments. It is found that this inelastic scattering process for a nonrelativistic sterile neutrino has a pronounced enhancement in the differential cross section at energy transfer about half of its mass, manifesting experimentally as peaks in the measurable energy spectra. The enhancement effects gradually smear out as the sterile neutrino becomes relativistic. Using data taken with low-threshold low-background germanium detectors, constraints on sterile neutrino mass and its transition magnetic moment are derived and compared with those from astrophysical observations.

  9. Mineral commodity profiles: Germanium

    Science.gov (United States)

    Butterman, W.C.; Jorgenson, John D.

    2005-01-01

    Overview -- Germanium is a hard, brittle semimetal that first came into use a half-century ago as a semiconductor material in radar units and as the material from which the first transistor was made. Today it is used principally as a component of the glass in telecommunications fiber optics; as a polymerization catalyst for polyethylene terephthalate (PET), a commercially important plastic; in infrared (IR) night vision devices; and as a semiconductor and substrate in electronics circuitry. Most germanium is recovered as a byproduct of zinc smelting, although it also has been recovered at some copper smelters and from the fly ash of coal-burning industrial powerplants. It is a highly dispersed element, associated primarily with base-metal sulfide ores. In the United States, germanium is recovered from zinc smelter residues and manufacturing scrap and is refined by two companies at four germanium refineries. One of the four refineries is dedicated to processing scrap. In 2000, producers sold zone-refined (high-purity) germanium at about $1,250 per kilogram and electronic-grade germanium dioxide (GeO2) at $800 per kilogram. Domestic refined production was valued at $22 million. Germanium is a critical component in highly technical devices and processes. It is likely to remain in demand in the future at levels at least as high as those of 2000. U.S. resources of germanium are probably adequate to meet domestic needs for several decades.

  10. Application of the Broad Energy Germanium detector: A technique for elucidating β-decay schemes which involve daughter nuclei with very low energy excited states

    Science.gov (United States)

    Venhart, M.; Wood, J. L.; Boston, A. J.; Cocolios, T. E.; Harkness-Brennan, L. J.; Herzberg, R.-D.; Joss, D. T.; Judson, D. S.; Kliman, J.; Matoušek, V.; Motyčák, Š.; Page, R. D.; Patel, A.; Petrík, K.; Sedlák, M.; Veselský, M.

    2017-03-01

    A technique for elucidating β-decay schemes of isotopes with a large density of states at low excitation energy has been developed, in which a Broad Energy Germanium (BEGe) detector is used in conjunction with coaxial hyper-pure germanium detectors. The power of this technique is demonstrated using the example of 183Hg decay. Mass-separated samples of 183Hg were produced by a deposition of the low-energy radioactive-ion beam delivered by the ISOLDE facility at CERN. The excellent energy resolution of the BEGe detector allowed γ-ray energies to be determined with a precision of a few tens of eV, which was sufficient for the analysis of the Rydberg-Ritz combinations (in conjunction with γ-γ coincidences) in the level scheme. The timestamped structure of the data was used for unambiguous separation of γ rays arising from the decay of 183Hg from those due to the daughter decays.

  11. Mechanically Cooled Large-Volume Germanium Detector Systems for Nuclear Explosion Monitoring

    Science.gov (United States)

    2008-09-01

    cm3, ~ 3 kg, ~ 140 %, or larger). Maintenance-free Stirling -cycle mechanical coolers are being used. These coolers have operating lifetimes...photograph of the complete RASA 1 detector system is shown in Figure 1. The detector is cooled to temperatures below 50 K when the cooler is...cryostat- cooler combination can ultimately serve as a viable detector unit for RASA detector systems . During the pursuit of the microphonic noise

  12. Final Report for Monitoring of Reactor Antineutrinos with Compact Germanium Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Orrell, John L.; Collar, J. I.

    2009-07-01

    This 2008 NCMR project has pursued measurement of the antineutrino-nucleus coherent scattering interaction using a low-energy threshold germanium gamma-ray spectrometer of roughly one-half kilogram total mass. These efforts support development of a compact system for monitoring the antineutrino emission from nuclear reactor cores. Such a monitoring system is relevant to nuclear safeguards and nuclear non-proliferation in general by adding a strong method for assuring quantitative material balance of special nuclear material in the nuclear fuel cycle used in electricity generation.

  13. Surface events in HPGe detectors

    Energy Technology Data Exchange (ETDEWEB)

    Abt, Iris; Dinter, Sabine; Faulstich, Florian; Majorovits, Bela; Stelzer, Franz [Max-Planck-Institut fuer Physik, Munich (Germany)

    2011-07-01

    Events on or close to the surface of high purity germanium, HPGe, detectors can introduce backgrounds in low background applications of such devices. The Galatea test-stand, especially developed and constructed at the MPI fuer Physik allows an almost full surface scan of a detector with alpha and beta sources. Events induced by alpha and beta particles can be characterized and surface effects can be studied. First comparisons between data and Monte Carlo are presented.

  14. Simulation and modeling of BEGe detectors for GERDA phase II

    Energy Technology Data Exchange (ETDEWEB)

    Agostini, Matteo; Barnabe Heider, Marik; Budjas, Dusan; Schoenert, Stefan [Max-Plank-Institute fuer Kernphysik, Heidelberg (Germany); Ur, Calin A. [INFN - Padova (Italy); Bellotti, Enrico; Cattadori, Carla [INFN - Milano (Italy); Di Vacri, Assunta; Pandola, Luciano [INFN - LNGS, L' Aquila (Italy); Garfagnini, Alberto [INFN - Padova (Italy); University of Padova (Italy)

    2010-07-01

    The GERDA experiment aims to search for the neutrinoless double beta decay of {sup 76}Ge by using high purity germanium detectors enriched in {sup 76}Ge. The background suppression in the GERDA experiment can be achieved by analyzing the time-development of the detector signals. To investigate the pulse shape discrimination capabilities of Broad Energy Germanium (BEGe) detectors, a complete simulation of the signal formation and evolution was developed. The results of the simulations will be presented and compared with measurements. The characteristic shapes of the BEGe detector signals and their dependence of the interaction position are discussed.

  15. Status report on the International Germanium Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Brodzinski, R.L.; Avignone, F.T.; Collar, J.I.; Courant, H.; Garcia, E.; Guerard, C.K.; Hensley, W.K.; Kirpichnikov, I.V.; Miley, H.S.; Morales, A.; Morales, J.; Nunez-Lagos, R.; Osetrov, S.B.; Pogosov, V.S.; Pomansky, A.A.; Puimedon, J.; Reeves, J.H.; Ruddick, K.; Saenz, C.; Salinas, A.; Sarsa, M.L.; Smolnikov, A.A.; Starostin, A.S.; Tamanyan, A.G.; Vasiliev, S.I.; Villar, J.A. (Pacific Northwest Lab., Richland, WA (United States) Univ. of South Carolina, Columbia, SC (United States) Univ. of Minnesota, Minneapolis, MN (United States) Univ. of Zaragoza (Spain) Inst. for Theoretical and Experimental Physics, Moscow (Russian Federation) Inst. for Nuclear Research, Baksan Neutrino Observatory (Russian Federation) Yerevan Physical Inst., Yerevan (Armenia))

    1993-04-01

    Phase II detector fabrication for the International Germanium Experiment is in progress. Sources of background observed during Phase I are discussed. Cosmogenic [sup 7]Be is measured in germanium. Radium contamination, presumably in electroformed copper, is reported. (orig.)

  16. Status report on the International Germanium Experiment

    Science.gov (United States)

    Brodzinski, R. L.; Avignone, F. T.; Collar, J. I.; Courant, H.; García, E.; Guerard, C. K.; Hensley, W. K.; Kirpichnikov, I. V.; Miley, H. S.; Morales, A.; Morales, J.; Núñez-Lagos, R.; Osetrov, S. B.; Pogosov, V. S.; Pomansky, A. A.; Puimedón, J.; Reeves, J. H.; Ruddick, K.; Sáenz, C.; Salinas, A.; Sarsa, M. L.; Smolnikov, A. A.; Starostin, A. S.; Tamanyan, A. G.; Vasiliev, S. I.; Villar, J. A.

    1993-04-01

    Phase II detector fabrication for the International Germanium Experiment is in progress. Sources of background observed during Phase I are discussed. Cosmogenic 7Be is measured in germanium. Radium contamination, presumably in electroformed copper, is reported.

  17. Effect of prolonged annealing on the performance of coaxial Ge gamma-ray detectors

    NARCIS (Netherlands)

    Owens, A.; Brandenburg, S.; Buis, E. -J.; Kozorezov, A. G.; Kraft, S.; Ostendorf, R. W.; Quarati, F.

    2007-01-01

    The effects of prolonged annealing at elevated temperatures have been investigated in a 53 cm(3) closed-end coaxial high purity germanium detector in the reverse electrode configuration. The detector was multiply annealed at 100 degrees C in block periods of 7 days. After each anneal cycle it was co

  18. Advanced far infrared blocked impurity band detectors based on germanium liquid phase epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Olsen, Christopher Sean [Univ. of California, Berkeley, CA (United States)

    1998-05-01

    This research has shown that epilayers with residual impurity concentrations of 5 x 1013 cm-3 can be grown by producing the purest Pb available in the world. These epilayers have extremely low minority acceptor concentrations, which is ideal for fabrication of IR absorbing layers. The Pb LPE growth of Ge also has the advantageous property of gettering Cu from the epilayer and the substrate. Epilayers have been grown with intentional Sb doping for IR absorption on lightly doped substrates. This research has proven that properly working Ge BIB detectors can be fabricated from the liquid phase as long as pure enough solvents are available. The detectors have responded at proper wavelengths when reversed biased even though the response did not quite reach minimum wavenumbers. Optimization of the Sb doping concentration should further decrease the photoionization energy of these detectors. Ge BIB detectors have been fabricated that respond to 60 cm-1 with low responsivity. Through reduction of the minority residual impurities, detector performance has reached responsivities of 1 A/W. These detectors have exhibited quantum efficiency and NEP values that rival conventional photoconductors and are expected to provide a much more sensitive tool for new scientific discoveries in a number of fields, including solid state studies, astronomy, and cosmology.

  19. Differentiating hidden sector dark matter from light WIMPs with Germanium detectors

    Science.gov (United States)

    Foot, R.

    2013-06-01

    Light WIMP dark matter and hidden sector dark matter have been proposed to explain the DAMA, CoGeNT and CRESST-II data. Both of these approaches feature spin independent elastic scattering of dark matter particles on nuclei. Light WIMP dark matter invokes a single particle species which interacts with ordinary matter via contact interactions. By contrast hidden sector dark matter is typically multi-component and is assumed to interact via the exchange of a massless mediator. Such hidden sector dark matter thereby predicts a sharply rising nuclear recoil spectrum, dR/dER∼1/ER2 due to this dynamics, while WIMP dark matter predicts a spectrum which depends sensitively on the WIMP mass, mχ. We compare and contrast these two very different possible origins of the CoGeNT low energy excess. In the relevant energy range, the recoil spectra predicted by these two theories approximately agree provided mχ ≃ 8.5 GeV - close to the value favoured from fits to the CoGeNT and CDMS low energy data. Forthcoming experiments including C-4, CDEX, and the MAJORANA demonstrator, are expected to provide reasonably precise measurements of the low energy Germanium recoil spectrum, including the annual modulation amplitude, which should differentiate between these two theoretical possibilities.

  20. Hard X-ray polarimetry with position sensitve germanium detectors. Studies of the recombination transitions into highly charged ions

    Energy Technology Data Exchange (ETDEWEB)

    Tashenov, Stanislav

    2005-07-01

    In this work a first study of the photon polarization for the process of radiative recombination has been performed. This was done at the ESR storage ring at GSI for uranium ions colliding with N2 at various collision energies. For this measurement a high purity Ge Pixel Detector with a 4 x 4 segmentation matrix was applied. The investigation was performed at the Gas-jet target of the ESR. The detector was placed at 60 and 90 observation angles. The sensitivity of the Compton scattering effect to the linear polarization of the X-Ray radiation was employed for the polarization measurement. Detailed investigations of the scattering and geometrical effects inside the detector were performed in order to develop a method to interpret the experimental data and extract the degree of the linear polarization in the hard X-Ray regime with a high precision. A special emphasis was given to the geometry of the detector and it's influence on the measured pixel-to-pixel Compton scattering intensities. The developed method enabled to achieve a precision of the order of 10% with the Pixel Detector which is dominated by the statistical uncertainties. The obtained results show a good agreement with the theoretical values derived from the exact relativistic calculations. For the case of the linear polarization of the K-REC photons, the measured data con rm the theoretical prediction that strong depolarization effects occur for high projectile charges in the forward hemisphere. The latter is in disagreement with the nonrelativistic theory which predicts a 100 % polarization regardless of the emission angle. (orig.)

  1. Liquid argon as active shielding and coolant for bare germanium detectors. A novel background suppression method for the GERDA 0{nu}{beta}{beta} experiment

    Energy Technology Data Exchange (ETDEWEB)

    Peiffer, J.P.

    2007-07-25

    Two of the most important open questions in particle physics are whether neutrinos are their own anti-particles (Majorana particles) as required by most extensions of the StandardModel and the absolute values of the neutrino masses. The neutrinoless double beta (0{nu}{beta}{beta}) decay, which can be investigated using {sup 76}Ge (a double beta isotope), is the most sensitive probe for these properties. There is a claim for an evidence for the 0{nu}{beta}{beta} decay in the Heidelberg-Moscow (HdM) {sup 76}Ge experiment by a part of the HdM collaboration. The new {sup 76}Ge experiment Gerda aims to check this claim within one year with 15 kg.y of statistics in Phase I at a background level of {<=}10{sup -2} events/(kg.keV.y) and to go to higher sensitivity with 100 kg.y of statistics in Phase II at a background level of {<=}10{sup -3} events/(kg.keV.y). In Gerda bare germanium semiconductor detectors (enriched in {sup 76}Ge) will be operated in liquid argon (LAr). LAr serves as cryogenic coolant and as high purity shielding against external background. To reach the background level for Phase II, new methods are required to suppress the cosmogenic background of the diodes. The background from cosmogenically produced {sup 60}Co is expected to be {proportional_to}2.5.10{sup -3} events/(kg.keV.y). LAr scintillates in UV ({lambda}=128 nm) and a novel concept is to use this scintillation light as anti-coincidence signal for background suppression. In this work the efficiency of such a LAr scintillation veto was investigated for the first time. In a setup with 19 kg active LAr mass a suppression of a factor 3 has been achieved for {sup 60}Co and a factor 17 for {sup 232}Th around Q{sub {beta}}{sub {beta}} = 2039 keV. This suppression will further increase for a one ton active volume (factor O(100) for {sup 232}Th and {sup 60}Co). LAr scintillation can also be used as a powerful tool for background diagnostics. For this purpose a new, very stable and robust wavelength

  2. Atomic ionization by sterile-to-active neutrino conversion and constraints on dark matter sterile neutrinos with germanium detectors

    CERN Document Server

    Chen, Jiunn-Wei; Lin, Shin-Ted; Liu, C -P; Singh, Lakhwinder; Wong, Henry T; Wu, Chih-Liang; Wu, Chih-Pan

    2016-01-01

    The transition magnetic moment of a sterile-to-active neutrino conversion gives rise to not only radiative decay of a sterile neutrino, but also its non-standard interaction (NSI) with matter. For sterile neutrinos of keV-mass as dark matter candidates, their decay signals are actively searched for in cosmic X-ray spectra. In this work, we consider the NSI that leads to atomic ionization, which can be detected by direct dark matter experiments. It is found that this inelastic scattering process for a nonrelativistic sterile neutrino has a pronounced enhancement in the differential cross section at energy transfer about half of its mass, manifesting experimentally as peaks in the measurable energy spectra. The enhancement effects gradually smear out as the sterile neutrino becomes relativistic. Using data taken with germanium detectors that have fine energy resolution in keV and sub-keV regimes, constraints on sterile neutrino mass and its transition magnetic moment are derived and compared with those from ast...

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

    Energy Technology Data Exchange (ETDEWEB)

    Dewberry, R.; Young, J.

    2011-04-29

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Dewberry, R.; Young, J.

    2011-04-29

    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

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

    Science.gov (United States)

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

    1999-04-01

    The International Germanium Experiment (IGEX) has six HPGe detectors, isotopically enriched to 86% in 76Ge, containing approximately 90 active moles of 76Ge. Three detectors of 2 kg each operate in the Canfranc Underground Laboratory (Spain) with pulse-shape analysis electronics. One detector (~0.7 kg active volume) has been operating in the Baksan Low-Background Laboratory for several years, and two additional similar detectors will operate in Baksan. A maximum likelihood analysis of 74.84 active mole years of data yields a lower bound T0ν1/2>=0.8×1025 yr (90% C.L.), corresponding to <(0.5-1.5) eV, depending on the theoretical nuclear matrix elements used to extract the neutrino mass parameter.

  6. Neutrinoless double-{beta} decay of {sup 76}Ge: First results from the International Germanium Experiment (IGEX) with six isotopically enriched detectors

    Energy Technology Data Exchange (ETDEWEB)

    Aalseth, C.E.; Avignone, F.T. III; Collar, J.I.; Hasenbalg, F. [University of South Carolina, Columbia, South Carolina 29208 (United States); Brodzinski, R.L.; Hensley, W.K.; Miley, H.S.; Reeves, J.H. [Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Garcia, E.; Gonzalez, D.; Morales, A.; Morales, J.; Ortiz de Solorzano, A.; Puimedon, J.; Salinas, A.; Sarsa, M.L.; Villar, J.A. [University of Zaragoza, 50009 Zaragoza (Spain); Kirpichnikov, I.V.; Starostin, A.S.; Vasenko, A.A. [Institute for Theoretical and Experimental Physics, 117259 Moscow (Russia); Klimenko, A.A.; Osetrov, S.B.; Smolnikov, A.A.; Vasiliev, S.I. [Institute for Nuclear Research, Baksan Neutrino Observatory, 361609 Neutrino (Russia); Pogosov, V.S.; Tamanyan, A.G. [Yerevan Physical Institute, 375 036 Yerevan (Armenia)

    1999-04-01

    The International Germanium Experiment (IGEX) has six HPGe detectors, isotopically enriched to 86{percent} in {sup 76}Ge, containing approximately 90 active moles of {sup 76}Ge. Three detectors of 2 kg each operate in the Canfranc Underground Laboratory (Spain) with pulse-shape analysis electronics. One detector ({approximately}0.7 kg active volume) has been operating in the Baksan Low-Background Laboratory for several years, and two additional similar detectors will operate in Baksan. A maximum likelihood analysis of 74.84 active mole years of data yields a lower bound T{sub 1/2}{sup 0{nu}}{ge}0.8{times}10{sup 25}yr (90{percent} C.L.), corresponding to {l_angle}m{sub {nu}}{r_angle}{lt}(0.5{endash}1.5)eV, depending on the theoretical nuclear matrix elements used to extract the neutrino mass parameter. {copyright} {ital 1999} {ital The American Physical Society}

  7. Low background germanium detectors: From environmental laboratory to underground counting facility

    Energy Technology Data Exchange (ETDEWEB)

    Ceuppens, M. [Canberra Semiconductor N.V., Geel (Belgium)]|[Canberra Industries, Inc., Meriden (United States); Verplancke, J. [Canberra Semiconductor N.V., Geel (Belgium)]|[Canberra Industries, Inc., Meriden (United States); Tench, O. [Canberra Semiconductor N.V., Geel (Belgium)]|[Canberra Industries, Inc., Meriden (United States)

    1997-03-01

    Presentation and overview of different Low Level measuring systems ranging from the environmental lab to low-background detection systems and to the deep underground counting facility. Examples and performances for each of these will be given. Attention will be given to the standardised ultra low-background detectors and shields which provide excellent performance without the high cost in time and money associated with custom designed systems. (orig./DG)

  8. Development of ultra pure germanium epi layers for blocked impurity band far infrared detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lutz, M.P.

    1991-05-01

    The main goals of this paper are: (1) To develop a low-pressure CVD (LPCVD) process that allows epitaxial growth at lower temperatures. Lower temperatures will allow the achievement of a sharp dopant profile at the substrate/epi-layer interface. Less out-diffusion from the substrate would allow the use of thinner epitaxial layers, which would lead to a larger depletion width in the photoactive region. LPCVD also avoids, to a great extent, gas-phase nucleation, which would cause Ge particulates to fall onto the wafer surface during growth. (2) To reduce high levels of oxygen and copper present at the wafer interface, as observed by secondary ion mass spectroscopy (SIMS). In order to achieve high-quality epitaxial layers, it is imperative that the substrate surface be of excellent quality. (3) To make and test detectors, after satisfactory epitaxial layers have been made.

  9. Limits on light weakly interacting massive particles from the CDEX-1 experiment with a p -type point-contact germanium detector at the China Jinping Underground Laboratory

    Science.gov (United States)

    Yue, Q.; Zhao, W.; Kang, K. J.; Cheng, J. P.; Li, Y. J.; Lin, S. T.; Chang, J. P.; Chen, N.; Chen, Q. H.; Chen, Y. H.; Chuang, Y. C.; Deng, Z.; Du, Q.; Gong, H.; Hao, X. Q.; He, H. J.; He, Q. J.; Huang, H. X.; Huang, T. R.; Jiang, H.; Li, H. B.; Li, J. M.; Li, J.; Li, J.; Li, X.; Li, X. Y.; Li, Y. L.; Liao, H. Y.; Lin, F. K.; Liu, S. K.; Lü, L. C.; Ma, H.; Mao, S. J.; Qin, J. Q.; Ren, J.; Ren, J.; Ruan, X. C.; Shen, M. B.; Singh, L.; Singh, M. K.; Soma, A. K.; Su, J.; Tang, C. J.; Tseng, C. H.; Wang, J. M.; Wang, L.; Wang, Q.; Wong, H. T.; Wu, S. Y.; Wu, Y. C.; Wu, Y. C.; Xianyu, Z. Z.; Xiao, R. Q.; Xing, H. Y.; Xu, F. Z.; Xu, Y.; Xu, X. J.; Xue, T.; Yang, L. T.; Yang, S. W.; Yi, N.; Yu, C. X.; Yu, H.; Yu, X. Z.; Zeng, X. H.; Zeng, Z.; Zhang, L.; Zhang, Y. H.; Zhao, M. G.; Zhou, Z. Y.; Zhu, J. J.; Zhu, W. B.; Zhu, X. Z.; Zhu, Z. H.; CDEX Collaboration

    2014-11-01

    We report results of a search for light dark matter weakly interacting massive particles (WIMPs) with CDEX-1 experiment at the China Jinping Underground Laboratory, based on 53.9 kg-days of data from a p -type point-contact germanium detector enclosed by a NaI(Tl) crystal scintillator as anti-Compton detector. The event rate and spectrum above the analysis threshold of 475 eVee are consistent with the understood background model. Part of the allowed regions for WIMP-nucleus coherent elastic scattering at WIMP mass of 6-20 GeV are probed and excluded. Independent of interaction channels, this result contradicts the interpretation that the anomalous excesses of the CoGeNT experiment are induced by dark matter, since identical detector techniques are used in both experiments.

  10. 高纯锗(HPGe)γ谱仪测定铀矿石中镭的方法研究%The Experiment Study on the Radium Measurment in Uranium ore with High Purity Germanium(HPGe) γSpectrometer

    Institute of Scientific and Technical Information of China (English)

    薛志伟; 高明明; 乔宁强; 王强; 朱晓贤

    2014-01-01

    为了改善由样品密度不同、厚度不同引起的测量误差,笔者采用压片法制样,然后密封于样品盒达到平衡,通过152 Eu对外界的电磁干扰进行内标校正,在高纯锗( HPGe)γ谱仪上测定铀矿石中镭的含量。测定结果的相对标准偏差( RSD/%)为2.43%,与射气法结果进行比较,相对误差在-5.31%~6.62%之间,方法的精密度和准确度均能满足实际生产需求,可操作性强,简便快速。%In order to reduce the measurement error caused by different sample thickness and density , the author uses compression method to get detection sample .The sample is sealed in a sample box to achieve balance , then we measure the radium content of uranium ore by using High purity germanium (HPGe) γspectrometer. The result is corrected by 152 Eu to avoid the electromagnetic disturbances .The relative standard deviation ( RSD%) of the determination results is 2.43%.Comparing with the emanation method results , the relative error are between -5.31%~6.62%.The method is able to meet the demands due to its advantages of easy operation and rapidness , the high precision and accuracy .

  11. A Low-Noise Germanium Ionization Spectrometer for Low-Background Science

    Energy Technology Data Exchange (ETDEWEB)

    Aalseth, Craig E.; Colaresi, Jim; Collar, Juan I.; Fast, James E.; Hossbach, Todd W.; Orrell, John L.; Overman, Cory T.; Scholz, Bjorn; Vandevender, Brent A.; Yocum, K. Michael

    2016-12-01

    Recent progress on the development of very low energy threshold high purity germanium ionization spectrometers has produced an instrument of 1.2 kg mass and excellent noise performance. The detector was installed in a low-background cryostat intended for use in a low mass, WIMP dark matter direct detection search. The integrated detector and low background cryostat achieved noise performance of 98 eV full-width half-maximum of an input electronic pulse generator peak and gamma-ray energy resolution of 1.9 keV full-width half-maximum at the 60Co gamma-ray energy of 1332 keV. This Transaction reports the thermal characterization of the low-background cryostat, specifications of the newly prepared 1.2 kg p-type point contact germanium detector, and the ionization spectroscopy – energy resolution and energy threshold – performance of the integrated system.

  12. Limits on light WIMPs from the CDEX-1 experiment with a p-type point-contact germanium detector at the China Jingping Underground Laboratory

    CERN Document Server

    Yue, Q; Kang, K J; Cheng, J P; Li, Y J; Lin, S T; Chang, J P; Chen, N; Chen, Q H; Chen, Y H; Chuang, Y C; Deng, Z; Du, Q; Gong, H; Hao, X Q; He, H J; He, Q J; Huang, H X; Huang, T R; Jiang, H; Li, H B; Li, J M; Li, J; Li, X; Li, X Y; Li, Y L; Liao, H Y; Lin, F K; Liu, S K; Lv, L C; Ma, H; Mao, S J; Qin, J Q; Ren, J; Ruan, X C; Shen, M B; Singh, L; Singh, M K; Soma, A K; Su, J; Tang, C J; Tseng, C H; Wang, J M; Wang, L; Wang, Q; Wong, H T; Wu, S Y; Wu, Y C; Xianyu, Z Z; Xiao, R Q; Xing, H Y; Xu, F Z; Xu, Y; Xu, X J; Xue, T; Yang, L T; Yang, S W; Yi, N; Yu, C X; Yu, H; Yu, X Z; Zeng, X H; Zeng, Z; Zhang, L; Zhang, Y H; Zhao, M G; Zhou, Z Y; Zhu, J J; Zhu, W B; Zhu, X Z; Zhu, Z H

    2014-01-01

    We report results of a search for light Dark Matter WIMPs with CDEX-1 experiment at the China Jingping Underground Laboratory, based on 53.9 kg-days of data from a p-type point-contact germanium detector enclosed by a NaI(Tl) crystal scintillator as anti-Compton detector. All events above the analysis threshold of 475 eVee can be quantitatively accounted for with the understood background channels, and there is no excess of residual events. An order of magnitude improvement in the sensitivities of spin-independent elastic cross-section over our previous results is achieved. Part of the allowed regions at WIMP mass of 6-20 GeV are probed and excluded.

  13. Limits on Low-Mass WIMP Dark Matter with an Ultra-Low-Energy Germanium Detector at 220 eV Threshold

    CERN Document Server

    Lin, Shin-Ted

    2008-01-01

    An energy threshold of (220$\\pm$10) eV was achieved at an efficiency of 50% with a four-channel ultra-low-energy germanium detector each with an active mass of 5 g\\cite{wimppaper}. This provides a unique probe to WIMP dark matter with mass below 10 GeV. With low background data taken at the Kuo-Sheng Laboratory, constraints on WIMPs in the galactic halo were derived. Both spin-independent WIMP-nucleon and spin-dependent WIMP-neutron bounds improve over previous results for WIMP mass between 3$-$6 GeV. These results, together with those on spin-dependent couplings, will be presented. Sensitivities for full-scale experiments were projected. This detector technique makes the unexplored sub-keV energy window accessible for new neutrino and dark matter experiments.

  14. Characteristics of a 4-fold segmented clover detectore

    Institute of Scientific and Technical Information of China (English)

    LOU Jian-Ling; LI Zhi-Huan; YE Yan-Lin; JIANG Dong-Xing; HUA Hui; LI Xiang-Qing; ZHANG Shuang-Quan; ZHENG Tao; GE Yu-Cheng; KONG Zan; L(U) Lin-Hui; LI Chen; LU Fei; FAN Feng-Ying; LI Zhong-Yu; CAO Zhong-Xin; MA Li-Ying; Faisal. J. Q.; XU Hu-Shan; HU Zheng-Guo; WANG Meng; LEI Xiang-Guo; DUAN Li-Min; XIAO Zhi-Gang; ZHAN Wen-Long; XIAO Guo-Qing; HUANG Tian-Heng; FU Fen; ZHANG Xue-Heng; ZHENG Chuan; YU Yu-Song; TU Xiao-Lin; ZHANG Ya-Peng; YANG Yan-Yun; ZHANG Hong-Bin; TANG Bin; TIAN Yu-Lin; OUYANG Zhen; HUANG Mei-Rong; XU Zhi-Guo; YUE Ke; GAO Qi

    2009-01-01

    Four high-purity germanium 4-fold segmented Clover detectors have been applied in the experiment of neutron-rich nucleus 21N. The performance of those four Clovers have been tested with radioactive sources and in-beam experiments, and the main results including energy resolution, peak-to-total ratios, the variation of the hit pattern distribution in different crystals of one Clover detector with the energy of γ ray, and absolute full energy peak detection efficiency curve, were presented.

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

    Science.gov (United States)

    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

    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.

  16. Research on the application of germanium detectors in GPON%面向GPON的硅基锗探测器应用研究

    Institute of Scientific and Technical Information of China (English)

    程鲁腾; 杨楠; 杨华山; 刘光祖; 陈相宁; 张洪国; 江伟

    2016-01-01

    In past several decades,silicon photonics technology has been well-developed and applied to optical inter-connects,data communications,and sensing.Many key components,such as waveguides,modulators,isolators, detectors and lasers on silicon-on-isolator, have been studied and reached high performance. Silicon-based germanium detectors have become a hot research topic in recent years because of their excellent photoelectric properties,such as high bandwidth,small footprint,and CMOS(Complementary Metal Oxide Semiconductor)com-patibility.Recently,they have been widely applied to many optical-electronic devices or communication systems.In this work,silicon-based germanium detectors for GPON(Gigabit-capable Passive Optical Networks)applications have been systematically studied.In order to meet the current requirements of GPON access network standard,the photoelectric conversion characteristics of the silicon-based germanium detectors have been investigated.A simple and practical testing platform utilizing a BERT(bit error rate tester)has been built up to take experimental data and characterize the photoelectric performance of germanium detectors which have important properties in practical optical communication technologies. Eye diagrams have shown that the detector can reliably perform under 2.5 Gbps rate, detecting 2-level modulation symbols, which may be potentially useful in GPON optical communication networks.Several schemes of reducing bit error rate have also been discussed.The CDR(clock and data recovery)has significantly improved the eye diagram and reduced the bit error rate.Other related data or result analysis have also been measured and analyzed in the paper.Data have shown that the proposed testing scheme is feasible.This test provides a possible solution and technical data for the application of silicon based germanium detectors in GPON.Further experimental test and data analysis are in process,and may be reported in the forth-coming publications.%锗硅

  17. Realization of the low background neutrino detector Double Chooz. From the development of a high-purity liquid and gas handling concept to first neutrino data

    Energy Technology Data Exchange (ETDEWEB)

    Pfahler, Patrick

    2012-12-17

    Neutrino physics is one of the most vivid fields in particle physics. Within this field, neutrino oscillations are of special interest as they allow to determine driving oscillation parameters, which are collected as mixing angles in the leptonic mixing matrix. The exact knowledge of these parameters is the main key for the investigation of new physics beyond the currently known Standard Model of particle physics. The Double Chooz experiment is one of three reactor disappearance experiments currently taking data, which recently succeeded to discover a non-zero value for the last neutrino mixing angle {Theta}{sub 13}. As successor of the CHOOZ experiment, Double Chooz will use two detectors with improved design, each of them now composed of four concentrically nested detector vessels each filled with different detector liquid. The integrity of this multi-layered structure and the quality of the used detector liquids are essential for the success of the experiment. Within this frame, the here presented work describes the production of two detector liquids, the filling and handling of the Double Chooz far detector and the installation of all necessary hardware components therefore. In order to meet the strict requirements existing for the detector liquids, all components were individually selected in an extensive material selection process at TUM, which compared samples from different companies for their key properties: density, transparency, light yield and radio purity. Based on these measurements, the composition of muon veto scintillator and buffer liquid were determined. For the production of the detector liquids, a simple surface building close to the far detector site was upgraded into a large-scale storage and mixing facility, which allowed to separately, mix, handle and store 90 m{sup 3} of muon veto scintillator and 110 m{sup 3} of buffer liquid. For the muon veto scintillator, a master-solution composed of 4800 l LAB, 180 kg PPO and 1.8 kg of bis/MSB was

  18. The automatic liquid nitrogen filling system for GDA detectors

    Indian Academy of Sciences (India)

    Rakesh Kumar; A J Malyadri; S Muralithar; Ruby Shanti; S K Saini Kusum Rani; B P Ajith Kumar; Rajesh Kumar; R K Bhowmik

    2001-07-01

    An indigenously developed automatic liquid nitrogen (LN2) filling system has been installed in gamma detector array (GDA) facility at Nuclear Science Centre. Electro-pneumatic valves are used for filling the liquid nitrogen into the high purity germanium detector cryostat. The temperature of the out-flowing gas/liquid from the cryostat is monitored using platinum resistor thermometer. The program allows for automatic filling at regular intervals with temperature monitoring from a remote terminal.

  19. Experimental and simulated efficiency of a HPGe detector with point-like and extended sources

    CERN Document Server

    Karamanis, D; Andriamonje, Samuel A; Barreau, G; Petit, M

    2002-01-01

    The absolute efficiency of a high purity germanium (HPGe) detector was determined with a point-like calibrated sup 1 sup 5 sup 2 Eu source at two distances from the detector and three pure metallic thorium foils of different thicknesses. The experimental values are compared with the ones determined with the simulation codes MCNP4B and GEANT 3.21. A procedure for HPGe absolute efficiency calibration is proposed for gamma-ray energies higher than 200 keV.

  20. A search for particle dark matter using cryogenic germanium and silicon detectors in the one- and two- tower runs of CDMS-II at Soudan

    Energy Technology Data Exchange (ETDEWEB)

    Ogburn, IV, Reuben Walter [Stanford Univ., CA (United States)

    2008-06-01

    Images of the Bullet Cluster of galaxies in visible light, X-rays, and through gravitational lensing confirm that most of the matter in the universe is not composed of any known form of matter. The combined evidence from the dynamics of galaxies and clusters of galaxies, the cosmic microwave background, big bang nucleosynthesis, and other observations indicates that 80% of the universe's matter is dark, nearly collisionless, and cold. The identify of the dar, matter remains unknown, but weakly interacting massive particles (WIMPs) are a very good candidate. They are a natural part of many supersymmetric extensions to the standard model, and could be produced as a nonrelativistic, thermal relic in the early universe with about the right density to account for the missing mass. The dark matter of a galaxy should exist as a spherical or ellipsoidal cloud, called a 'halo' because it extends well past the edge of the visible galaxy. The Cryogenic Dark Matter Search (CDMS) seeks to directly detect interactions between WIMPs in the Milky Way's galactic dark matter halo using crystals of germanium and silicon. Our Z-sensitive ionization and phonon ('ZIP') detectors simultaneously measure both phonons and ionization produced by particle interactions. In order to find very rare, low-energy WIMP interactions, they must identify and reject background events caused by environmental radioactivity, radioactive contaminants on the detector,s and cosmic rays. In particular, sophisticated analysis of the timing of phonon signals is needed to eliminate signals caused by beta decays at the detector surfaces. This thesis presents the firs two dark matter data sets from the deep underground experimental site at the Soudan Underground Laboratory in Minnesota. These are known as 'Run 118', with six detectors (1 kg Ge, 65.2 live days before cuts) and 'Run 119', with twelve detectors (1.5 kg Ge, 74.5 live days before cuts). They have

  1. A search for bremsstrahlung solar axions using the Majorana low-background BEGe detector at Kimballton (MALBEK)

    CERN Document Server

    Abgrall, N; Avignone, F T; Barabash, A S; Bertrand, F E; Boswell, M; Brudanin, V; Busch, M; Caldwell, A S; Chan, Y-D; Christofferson, C D; Combs, D C; Cooper, R J; Creswick, R J; Detwiler, J A; Doe, P J; Efremenko, Yu; Egorov, V; Elliott, S R; Fast, J E; Finnerty, P; Giovanetti, G K; Goett, J; Green, M P; Gruszko, J; Guiseppe, V E; Gusev, K; Hegai, A; Henning, R; Hoppe, E W; Howard, S; Howe, M A; Keeter, K J; Kidd, M F; Knecht, A; Kochetov, O; Konovalov, S I; Kouzes, R T; LaFerriere, B D; Leon, J; Leviner, L E; Loach, J C; MacMullin, J; MacMullin, S; Marino, M G; Martin, R D; Mertens, S; Orrell, J L; O'Shaughnessy, C; Overman, N R; Phillips, D G; Poon, A W P; Pushkin, K; Radford, D C; Robertson, R G H; Ronquest, M C; Schubert, A G; Shanks, B; Shirchenko, M; Snavely, K J; Snyder, N; Steele, D; Suriano, A M; Thompson, J; Timkin, V; Varner, R L; Vasilyev, S; Vetter, K; Vorren, K; White, B R; Wilkerson, J F; Xu, W; Yakushev, E; Young, A R; Yu, C H; Yumatov, V

    2014-01-01

    A low-background, high-purity germanium detector has been used to search for evidence of low-energy, bremsstrahlung-generated solar axions. An upper bound of $1.36\\times 10^{-11}$ $(95\\% CL)$ is placed on the direct coupling of DFSZ model axions to electrons. The prospects for the sensitivity of the Majorana Demonstrator array of point-contact germanium detectors to solar axions are discussed in the context of the model-independent annual modulation due to the seasonal variation of the earth-sun distance.

  2. A simple methodology for characterization of germanium coaxial detectors by using Monte Carlo simulation and evolutionary algorithms.

    Science.gov (United States)

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

    2015-11-01

    The determination in a sample of the activity concentration of a specific radionuclide by gamma spectrometry needs to know the full energy peak efficiency (FEPE) for the energy of interest. The difficulties related to the experimental calibration make it advisable to have alternative methods for FEPE determination, such as the simulation of the transport of photons in the crystal by the Monte Carlo method, which requires an accurate knowledge of the characteristics and geometry of the detector. The characterization process is mainly carried out by Canberra Industries Inc. using proprietary techniques and methodologies developed by that company. It is a costly procedure (due to shipping and to the cost of the process itself) and for some research laboratories an alternative in situ procedure can be very useful. The main goal of this paper is to find an alternative to this costly characterization process, by establishing a method for optimizing the parameters of characterizing the detector, through a computational procedure which could be reproduced at a standard research lab. This method consists in the determination of the detector geometric parameters by using Monte Carlo simulation in parallel with an optimization process, based on evolutionary algorithms, starting from a set of reference FEPEs determined experimentally or computationally. The proposed method has proven to be effective and simple to implement. It provides a set of characterization parameters which it has been successfully validated for different source-detector geometries, and also for a wide range of environmental samples and certified materials.

  3. Enhancing the Detector for Advanced Neutron Capture Experiments

    Directory of Open Access Journals (Sweden)

    Couture A.

    2015-01-01

    Full Text Available The Detector for Advanced Neutron Capture Experiments (DANCE has been used for extensive studies of neutron capture, gamma decay, photon strength functions, and prompt and delayed fission-gamma emission. Despite these successes, the potential measurements have been limited by the data acquisition hardware. We report on a major upgrade of the DANCE data acquisition that simultaneously enables strait-forward coupling to auxiliary detectors, including high-resolution high-purity germanium detectors and neutron tagging array. The upgrade will enhance the time domain accessible for time-of-flight neutron measurements as well as improve the resolution in the DANCE barium fluoride crystals for photons.

  4. Final Technical Report for DUSEL Research and Development on Sub-Kelvin Germanium Detectors for Ton Scale Dark Matter Search

    Energy Technology Data Exchange (ETDEWEB)

    Cabrera, Blas

    2012-09-10

    We have supported one graduate student and a small percentage of fabrication staff on $135k per year for three years plus one no cost extension year on this DUSEL R&D grant. There were three themes within our research program: (1) how to improve the radial sensitivity for single sided phonon readout with four equal area sensors of which three form a central circle and fourth a surrounding ring; (2) how to instrument double sided phonon readouts which will give us better surface event rejection and increased fiducial volume for future CDMS style detectors; and (3) can we manufacture much larger Ge detectors using six inch diameter material which is not suitable for standard gamma ray spectroscopy.

  5. New results in the ITEP/YePI double beta-decay experiment with enriched germanium detectors

    Energy Technology Data Exchange (ETDEWEB)

    Vasenko, A.A.; Kirpichnikov, I.V.; Kuznetsov, V.A.; Starostin, A.S. (Institute for Theoretical and Experimental Physics, Bolshaya Cheremushkinskaya 25, Moscow 117259 (SU)); Djanyan, A.G.; Pogosov, V.S.; Shachysisyan, S.P.; Tamanyan, A.G. (Yerevan Physical Institute, Markaryan 2, Yerevan 375036 (SU))

    1990-07-20

    This paper reports the search for double beta-decay of {sup 76}Ge carried out with a detector fabricated of enriched material (85% abundance of {sup 76}Ge compared with 7.8% natural abundance). Measurements have been performed by the ITEP/YePI team in the Avan salt mine, 245 meters underground, situated in Yerevan, Armenia. Evidence for two-neutrino double beta-decay of {sub 76}Ge with half-life of T{sub 1/2}(2v) = (9 {plus minus} 1 {center dot} 10{sup 20})y was obtained. New limits for neutrinoless double beta-decay, T{sub 1/2}(Ov) {gt} 1.3 {times} 10{sup 24}y, and double beta-decay with majoron emission T{sub 1/2}(Ov,B) {gt} 1 {times} 10{sup 22}y were obtained at 68% CL from mean background fluctuations. Limit for Ov-decay derived by the maximum likelihood method was T{sub 1/2} {gt} 2.0 {times} 10{sup 24}y.

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

    CERN Document Server

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

    2000-01-01

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

  7. Detector resolution in positron annihilation Doppler broadening experiments

    Science.gov (United States)

    Heikinheimo, J.; Ala-Heikkilä, J.; Tuomisto, F.

    2017-09-01

    Positron annihilation Doppler broadening spectroscopy characterizes lattice point defects and is sensitive to very small vacancy densities. High-purity germanium detectors are generally used for recording the Doppler broadening spectrum because they provide good energy resolution and stability. However, the energy resolution of a germanium detector is somewhat dependent on the photon absorption geometry in the detector crystal. This change in the energy resolution changes also the Doppler broadening parameters. To observe the dependency of the resolution function and the Doppler broadening parameters, we performed experiments on Si samples in standard sandwich configuration with a Na-22 source. We changed the radiation geometry of the incident gamma photons via altering the distance of the sample-source package from the detector and by adding steel between the source and the detector. We observed the change of the absorption geometry in the germanium detector crystal by doing Monte Carlo simulations. The aim of this study is to help understand and decide what is the best way to compare the Doppler broadening parameters obtained with different measurement setups and even with the same setup when the geometry in the measurements has changed.

  8. Detector developments for the hypernuclear programme at PANDA

    CERN Document Server

    Achenbach, P; Lorente, A Sanchez; Majos, S Sánchez

    2011-01-01

    The technical design of the PANDA experiment at the future FAIR facility next to GSI is progressing. At the proposed anti-proton storage ring the spectroscopy of double Lambda hypernuclei is one of the four main topics which will be addressed by the Collaboration. The hypernuclear experiments require (i) a dedicated internal target, (ii) an active secondary target of alternating silicon and absorber material layers, (iii) high purity germanium (HPGe) detectors, and (iv) a good particle identification system for low momentum kaons. All systems need to operate in the presence of a high magnetic field and a large hadronic background. The status of the detector developments for this programme is summarized.

  9. MSE/SSE discrimination methods of the PC-HPGe detector

    Institute of Scientific and Technical Information of China (English)

    L(U) Zi-Feng; LI Yu-Lan; LI Jin; YUE Qian; LI Yuan-Jing

    2012-01-01

    Having advantages of low capacitance and low energy threshold,the PC-HPGe (Point-Contact High Purity Germanium) detector has found its application in the direct detection of WIMP(Weak Interaction Massive Particle) in CDEX (China Darkmatter Experiment).The MSE (Multi-Site Event) and SSE(Single-Site Event) discrimination methods of the PC-HPGe detector are introduced in this article,including their physical basis,the electronics system and the algorithms to implement them.Behaviors of the PC-HPGe detector are studied intensively through this research and finally the experimental results of the LE discrimination method are presented.

  10. Imaging the oblique propagation of electrons in germanium crystals at low temperature and low electric field

    Energy Technology Data Exchange (ETDEWEB)

    Moffatt, R. A., E-mail: rmoffatt@stanford.edu; Cabrera, B.; Corcoran, B. M.; Kreikebaum, J. M.; Redl, P.; Shank, B.; Yen, J. J. [Department of Physics, Stanford University, Stanford, California 94305 (United States); Young, B. A. [Department of Physics, Stanford University, Stanford, California 94305 (United States); Department of Physics, Santa Clara University, Santa Clara, California 95053 (United States); Brink, P. L.; Cherry, M.; Tomada, A. [SLAC National Accelerator Facility, Menlo Park, California 94025 (United States); Phipps, A.; Sadoulet, B.; Sundqvist, K. M. [Department of Physics, University of California, Berkeley, California 94720 (United States)

    2016-01-11

    Excited electrons in the conduction band of germanium collect into four energy minima, or valleys, in momentum space. These local minima have highly anisotropic mass tensors which cause the electrons to travel in directions which are oblique to an applied electric field at sub-Kelvin temperatures and low electric fields, in contrast to the more isotropic behavior of the holes. This experiment produces a full two-dimensional image of the oblique electron and hole propagation and the quantum transitions of electrons between valleys for electric fields oriented along the [0,0,1] direction. Charge carriers are excited with a focused laser pulse on one face of a germanium crystal and then drifted through the crystal by a uniform electric field of strength between 0.5 and 6 V/cm. The pattern of charge density arriving on the opposite face is used to reconstruct the trajectories of the carriers. Measurements of the two-dimensional pattern of charge density are compared in detail with Monte Carlo simulations developed for the Cryogenic Dark Matter Search (SuperCDMS) to model the transport of charge carriers in high-purity germanium detectors.

  11. Status report on the International Germanium Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Brodzinski, R.L.; Hensley, W.K.; Miley, H.S.; Reeves, J.H. [Pacific Northwest Lab., Richland, WA (United States); Avignone, F.T.; Collar, J.I.; Guerard, C.K. [South Carolina Univ., Columbia, SC (United States); Courant, H.; Ruddick, K. [Minnesota Univ., Minneapolis, MN (United States); Kirpichnikov, I.V.; Starostin, A.S. [AN SSSR, Moscow (Russian Federation). Inst. Teoreticheskoj i Eksperimental`noj Fiziki; Garcia, E.; Morales, A.; Morales, J.; Nunez-Lagos, R.; Puimedon, J.; Saenz, C.; Salinas, A.; Sarasa, M.L.; Villar, J.A. [Zaragoza Univ. (Spain); Osetrov, S.B.; Pomansky, A.A.; Smolnikov, A.A.; Vasiliev, S.I. [AN SSSR, Moscow (Russian Federation). Inst. Yadernykh Issledovanij; Pogosov, V.S.; Tamanyan, A.G. [Erevanskij Fizicheskij Inst., Erevan (Armenia)

    1992-06-01

    Phase II detector fabrication for the International Germanium Experiment is awaiting resolution of technical details observed during Phase I. Measurements of fiducial volume, configuration of the tansistor-reset preamplifier stage, and sources of background are discussed. Cosmogenic {sup 7}Be is measured in germanium. Radium contamination in electroformed copper reported. The 2{nu} double- beta decay half-life of {sup 76}Ge measured with a Phase I detector is in reasonable agreement with previously reported values. No events are observed in the vicinity of the O{nu} double-beta decay energy.

  12. The International Germanium Experiment (IGEX) in 1993

    Energy Technology Data Exchange (ETDEWEB)

    Avignone, F.T. (University of South Carolina, Columbia, SC 29208 (United States)); Brodzinski, R.L. (Pacific Northwest Laboratory, Battelle Blvd., Richland, WA 99352 (United States)); Collar, J.I. (University of South Carolina, Columbia, SC 29208 (United States)); Courant, H. (University of Minnesota, Minneapolis, MN 55455 (United States)); Garcia, E. (University of Zaragoza, Zaragoza (Spain)); Guerard, C.K. (University of South Carolina, Columbia, SC 29208 (United States)); Hensley, W.K. (Pacific Northwest Laboratory, Battelle Blvd., Richland, WA 99352 (United States)); Kirpichnikov, I.V. (Institute for Theoretical and Experimental Physics, 117 259 Moscow (Russian Federation)); Klimenko, A.A. (Institute for Nuclear Research, Baksan Neutrino Observatory, 361 609 Neutrino (Russian Federation)); Morales, A. (University of Zaragoza, Zaragoza (Spain)); Morales, J. (University of Zaragoza, Zaragoza (Spain)); Miley, H.S. (Pacific Northwest Laboratory, Battelle Blvd., Richland, WA

    1994-05-01

    The data collected from the first set of three IGEX enriched germanium detectors have been analyzed. The best background obtained was less than 0.3counts/keV/kg/y near 2MeV, obtained in the Homestake gold mine in Lead, SD, USA. Data combined from all the detectors yield T[sub 1/2][sup 0][>=]qslant1.0x10[sup 24]y (90% CL). The first detector produced in the second phase of the experiment is a 2.15kg germanium crystal of 2.16keV FWHM at 1332keV. Several experiences with the first group of detectors have led to improvements in the mechanical design of the copper cryostat. Also, low background materials research done in the last two years has lowered the specific activity of the electroformed copper. The new detector is currently operating in the Homestake gold mine. ((orig.))

  13. The International Germanium Experiment (IGEX) in 1993

    Science.gov (United States)

    Avignone, F. T.; Brodzinski, R. L.; Collar, J. I.; Courant, H.; Garcia, E.; Guerard, C. K.; Hensley, W. K.; Kirpichnikov, I. V.; Klimenko, A. A.; Morales, A.; Morales, J.; Miley, H. S.; Nunez-Lagos, R.; Osetrov, S. B.; Pogosov, V. S.; Pomansky, A. A.; Puimedon, J.; Reeves, J. H.; Ruddick, K.; Saenz, C.; Salinas, A.; Sarsa, M. L.; Smolnikov, A. A.; Starostin, A. S.; Tamanyan, A. G.; Umatov, V. I.; Vasiliev, S. I.; Villar, J. A.

    1994-05-01

    The data collected from the first set of three IGEX enriched germanium detectors have been analyzed. The best background obtained was less than 0.3 counts/keV/kg/y near 2 MeV, obtained in the Homestake gold mine in Lead, SD, USA. Data combined from all the detectors yield T{1}/{2}0τ ≥ 1.0 × 10 24y (90% CL) . The first detector produced in the second phase of the experiment is a 2.15 kg germanium crystal of 2.16 keV FWHM at 1332 keV. Several experiences with the first group of detectors have led to improvements in the mechanical design of the copper cryostat. Also, low background materials research done in the last two years has lowered the specific activity of the electroformed copper. The new detector is currently operating in the Homestake gold mine.

  14. Germanium: From Its Discovery to SiGe Devices

    Energy Technology Data Exchange (ETDEWEB)

    Haller, E.E.

    2006-06-14

    Germanium, element No.32, was discovered in 1886 by Clemens Winkler. Its first broad application was in the form of point contact Schottky diodes for radar reception during WWII. The addition of a closely spaced second contact led to the first all-solid-state electronic amplifier device, the transistor. The relatively low bandgap, the lack of a stable oxide and large surface state densities relegated germanium to the number 2 position behind silicon. The discovery of the lithium drift process, which made possible the formation of p-i-n diodes with fully depletable i-regions several centimeters thick, led germanium to new prominence as the premier gamma-ray detector. The development of ultra-pure germanium yielded highly stable detectors which have remained unsurpassed in their performance. New acceptors and donors were discovered and the electrically active role of hydrogen was clearly established several years before similar findings in silicon. Lightly doped germanium has found applications as far infrared detectors and heavily Neutron Transmutation Doped (NTD) germanium is used in thermistor devices operating at a few milliKelvin. Recently germanium has been rediscovered by the silicon device community because of its superior electron and hole mobility and its ability to induce strains when alloyed with silicon. Germanium is again a mainstream electronic material.

  15. Gamma-gamma coincidence performance of LaBr3:Ce scintillation detectors vs HPGe detectors in high count-rate scenarios.

    Science.gov (United States)

    Drescher, A; Yoho, M; Landsberger, S; Durbin, M; Biegalski, S; Meier, D; Schwantes, J

    2017-04-01

    A radiation detection system consisting of two cerium doped lanthanum bromide (LaBr3:Ce) scintillation detectors in a gamma-gamma coincidence configuration has been used to demonstrate the advantages that coincident detection provides relative to a single detector, and the advantages that LaBr3:Ce detectors provide relative to high purity germanium (HPGe) detectors. Signal to noise ratios of select photopeak pairs for these detectors have been compared to high-purity germanium (HPGe) detectors in both single and coincident detector configurations in order to quantify the performance of each detector configuration. The efficiency and energy resolution of LaBr3:Ce detectors have been determined and compared to HPGe detectors. Coincident gamma-ray pairs from the radionuclides (152)Eu and (133)Ba have been identified in a sample that is dominated by (137)Cs. Gamma-gamma coincidence successfully reduced the Compton continuum from the large (137)Cs peak, revealed several coincident gamma energies characteristic of these nuclides, and improved the signal-to-noise ratio relative to single detector measurements. LaBr3:Ce detectors performed at count rates multiple times higher than can be achieved with HPGe detectors. The standard background spectrum consisting of peaks associated with transitions within the LaBr3:Ce crystal has also been significantly reduced. It is shown that LaBr3:Ce detectors have the unique capability to perform gamma-gamma coincidence measurements in very high count rate scenarios, which can potentially benefit nuclear safeguards in situ measurements of spent nuclear fuel. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. The effect of incremental gamma-ray doses and incremental neutron fluences upon the performance of self-biased sup 1 sup 0 B-coated high-purity epitaxial GaAs thermal neutron detectors

    CERN Document Server

    Gersch, H K; Simpson, P A

    2002-01-01

    High-purity epitaxial GaAs sup 1 sup 0 B-coated thermal neutron detectors advantageously operate at room temperature without externally applied voltage. Sample detectors were systematically irradiated at fixed grid locations near the core of a 2 MW research reactor to determine their operational neutron dose threshold. Reactor pool locations were assigned so that fast and thermal neutron fluxes to the devices were similar. Neutron fluences ranged between 10 sup 1 sup 1 and 10 sup 1 sup 4 n/cm sup 2. GaAs detectors were exposed to exponential fluences of base ten. Ten detector designs were irradiated and studied, differentiated between p-i-n diodes and Schottky barrier diodes. The irradiated sup 1 sup 0 B-coated detectors were tested for neutron detection sensitivity in a thermalized neutron beam. Little damage was observed for detectors irradiated at neutron fluences of 10 sup 1 sup 2 n/cm sup 2 and below, but signals noticeably degraded at fluences of 10 sup 1 sup 3 n/cm sup 2. Catastrophic damage was appare...

  17. Characterization and first experimental application of space-resolving, energy-dispersive germanium detectors for the precision spectroscopy on heavy ions; Charakterisierung und erster experimenteller Einsatz von ortsaufloesenden, energiedispersiven Germanium-Detektoren zur Praezisionsspektroskopie an schweren Ionen

    Energy Technology Data Exchange (ETDEWEB)

    Spillmann, Uwe

    2009-02-15

    First the actual status of the research for the 1s Lamb shift on heaviest systems as well as studies on the polarization of the radiative recombination radiation into the K shell of uranium are presented. On this base future precision experiments at storage rings are discussed. then follows a survey presentation of the GSI accelerator facility. Especially the experimental storage ring ESR is described, at which the experiments mentioned above were performed. Then an introduction to the fundamental understanding of the physical processes in the detection of X-radiation in semiconductor detectors is given. The following chapter discusses the detection technique of the Compton polarimetry and some experimental concepts for this. Then by means of a 4 x 4 pixel Ge(i) detector system, by which for the first time the K-REC radiation from uranium was measured at the ESR, an overview about the Monte-Carlo software EGS4 is given, which was applied to the efficiency correction in the evaluation phase and for the estimation of the detector behaviour during the planning phase of the new detectors. A presentation of the 1D and 2D microstrip detector system as well as the performed laboratory measurements follows. The results for the characterization of the 2D microstrip detector system at the synchrotron-radiation source ESRF in view of its application with the FOCAL spectrometer are thereafter described. The results of first test measurement on the Compton polarimetry, which were also performed at the ESRF, are then presented. Finally first experimental results, which wer obtained by the novel planar structured Ge(i) detectors, are shown.

  18. Systematic Uncertainties in High-Rate Germanium Data

    Energy Technology Data Exchange (ETDEWEB)

    Gilbert, Andrew J.; Fast, James E.; Fulsom, Bryan G.; Pitts, William K.; VanDevender, Brent A.; Wood, Lynn S.

    2016-10-06

    For many nuclear material safeguards inspections, spectroscopic gamma detectors are required which can achieve high event rates (in excess of 10^6 s^-1) while maintaining very good energy resolution for discrimination of neighboring gamma signatures in complex backgrounds. Such spectra can be useful for non-destructive assay (NDA) of spent nuclear fuel with long cooling times, which contains many potentially useful low-rate gamma lines, e.g., Cs-134, in the presence of a few dominating gamma lines, such as Cs-137. Detectors in use typically sacrifice energy resolution for count rate, e.g., LaBr3, or visa versa, e.g., CdZnTe. In contrast, we anticipate that beginning with a detector with high energy resolution, e.g., high-purity germanium (HPGe), and adapting the data acquisition for high throughput will be able to achieve the goals of the ideal detector. In this work, we present quantification of Cs-134 and Cs-137 activities, useful for fuel burn-up quantification, in fuel that has been cooling for 22.3 years. A segmented, planar HPGe detector is used for this inspection, which has been adapted for a high-rate throughput in excess of 500k counts/s. Using a very-high-statistic spectrum of 2.4*10^11 counts, isotope activities can be determined with very low statistical uncertainty. However, it is determined that systematic uncertainties dominate in such a data set, e.g., the uncertainty in the pulse line shape. This spectrum offers a unique opportunity to quantify this uncertainty and subsequently determine required counting times for given precision on values of interest.

  19. Fission-product yields for thermal-neutron fission of /sup 243/Cm determined from measurements with a high-resolution low-energy germanium gamma-ray detector

    Energy Technology Data Exchange (ETDEWEB)

    Merriman, L.D.

    1984-04-01

    Cumulative fission-product yields have been determined for 13 gamma rays emitted during the decay of 12 fission products created by thermal-neutron fission of /sup 243/Cm. A high-resolution low-energy germanium detector was used to measure the pulse-height spectra of gamma rays emitted from a 77-nanogram sample of /sup 243/Cm after the sample had been irradiated by thermal neutrons. Analysis of the data resulted in the identification and matching of gamma-ray energies and half-lives to individual radioisotopes. From these results, 12 cumulative fission product yields were deduced for radionuclides with half-lives between 4.2 min and 84.2 min. 7 references.

  20. Germanium junction detectors. Theoretical and practical factors governing their use in radiation spectrometry; Detecteurs a jonction au germanium. Elements theoriques et pratiques pour l'utilisation en spectrometrie de rayonnements

    Energy Technology Data Exchange (ETDEWEB)

    Hors, M.; Philis, C. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-07-01

    Semi-conductor detectors have recently greatly increased the possibilities available to nuclear spectroscopists for the study of {alpha}, {beta} and {gamma} radiations. Their use in radio-chemistry has encouraged us to study their principle, their mechanism and also the conditions under which they can be used. The first part, which is theoretical, consists of a summary of what should be known concerning the best use of junction detectors, in particular Ge (Li) detectors. The second part, which is experimental, summarizes the laboratory work carried out over a period of one year on Ge (Li) detectors. Stress is laid on the possibilities presented by the use of these detectors as photo-electric spectrometers, and also on the precautions required. Amongst the numerous results presented, the resolution of 2.52 keV obtained for the {gamma} radiation of 145.5 keV for {sup 141}Ce may be particularly noted. (authors) [French] Les detecteurs a semi-conducteurs ont recemment accru les possibilites offertes aux spectroscopistes nucleaires pour l'etude des radiations {alpha}, {beta}, {gamma}. Leurs utilisations en radiochimie nous ont incite a en etudier le principe, le mecanisme et d'autre part les conditions d'emploi. La premiere partie, theorique, rappelle l'essentiel de ce qu'il est utile de connaitre pour une utilisation optimale des detecteurs a jonctions et en particulier des detecteurs Ge (Li). La deuxieme partie, experimentale, resume les travaux realises au laboratoire pendant un an avec des detecteurs Ge (Li). Nous insistons sur les possibilites offertes et les precautions a prendre dans l'utilisation de ces detecteurs comme spectrometres photoelectriques. Parmi les nombreux resultats presentes, citons la resolution de 2,52 keV obtenue pour le rayonnement {gamma} de 145 f5 keV du {sup 141}Ce. (auteurs)

  1. Characterization of different surface passivation routes applied to a planar HPGe detector

    Energy Technology Data Exchange (ETDEWEB)

    Maggioni, G.; Gelain, M.; Carturan, S. [University of Padova, Department of Physics and Astronomy ' ' G. Galilei' ' , Padova (Italy); Laboratori Nazionali di Legnaro, Istituto Nazionale di Fisica Nucleare, Legnaro (Italy); Napoli, D.R. [Laboratori Nazionali di Legnaro, Istituto Nazionale di Fisica Nucleare, Legnaro (Italy); Eberth, J. [Universitaet zu Koeln, Institut fuer Kernphysik, Koeln (Germany); Grimaldi, M.G.; Tati, S. [University of Catania, Department of Physics and Astronomy, Catania (Italy)

    2015-11-15

    The effects of different passivation methods applied to the same planar high-purity germanium gamma radiation detector have been studied. By means of the scanning with a low-energy collimated gamma source, it has been found that the surface passivation gives rise to a dead layer below the intrinsic Ge surface, whose thickness and distribution are strongly dependent on the passivation type. Measured bulk detector properties like the peak-to-Compton ratio and efficiency have shown a dependence on the passivation and an influence of the passivation type on the depletion voltage, whilst the optimal energy resolution has been the same for all the passivations. (orig.)

  2. \\textsc{MaGe} - a {\\sc Geant4}-based Monte Carlo Application Framework for Low-background Germanium Experiments

    CERN Document Server

    Boswell, Melissa; Detwiler, Jason A; Finnerty, Padraic; Henning, Reyco; Gehman, Victor M; Johnson, Rob A; Jordan, David V; Kazkaz, Kareem; Knapp, Markus; Kröninger, Kevin; Lenz, Daniel; Leviner, Lance; Liu, Jing; Liu, Xiang; MacMullin, Sean; Marino, Michael G; Mokhtarani, Akbar; Pandola, Luciano; Schubert, Alexis G; Schubert, Jens; Tomei, Claudia; Volynets, Oleksandr

    2010-01-01

    We describe a physics simulation software framework, MAGE, that is based on the GEANT4 simulation toolkit. MAGE is used to simulate the response of ultra-low radioactive background radiation detectors to ionizing radiation, specifically the MAJORANA and GERDA neutrinoless double-beta decay experiments. MAJORANA and GERDA use high-purity germanium detectors to search for the neutrinoless double-beta decay of 76Ge, and MAGE is jointly developed between these two collaborations. The MAGE framework contains the geometry models of common objects, prototypes, test stands, and the actual experiments. It also implements customized event generators, GEANT4 physics lists, and output formats. All of these features are available as class libraries that are typically compiled into a single executable. The user selects the particular experimental setup implementation at run-time via macros. The combination of all these common classes into one framework reduces duplication of efforts, eases comparison between simulated data...

  3. Radioxenon detector calibration spike production and delivery systems

    Energy Technology Data Exchange (ETDEWEB)

    Foxe, Michael P.; Cameron, Ian M.; Cooper, Matthew W.; Haas, Derek A.; Hayes, James C.; Kriss, Aaron A.; Lidey, Lance S.; Mendez, Jennifer M.; Prinke, Amanda M.; Riedmann, Robin A.

    2016-03-01

    Abstract Beta-Gamma coincidence radioxenon detectors must be calibrated for each of the four-radioxenon isotopes (135Xe, 133Xe, 133mXe, and 131mXe). Without a proper calibration, there is potential for the misidentification of the amount of each isotope detected. It is important to accurately determine the amount of each radioxenon isotope, as the ratios can be used to distinguish between an anthropogenic source and a nuclear explosion. We have developed a xenon calibration system (XeCalS) that produces calibration spikes of known activity and pressure for field calibration of detectors. The activity concentrations of these calibration spikes are measured using a beta-gamma coincidence detector and a high purity germanium (HPGe) detector. We will present the results from the development and commissioning of XeCalS, along with the future plans for a portable spike implementation system.

  4. Spectral response of multi-element silicon detectors

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-04-01

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

  5. Crystal-growth Underground Breeding Extra-sensitive Detectors

    Science.gov (United States)

    Mei, Dongming

    2012-02-01

    CUBED (Center for Ultra-Low Background Experiments at DUSEL) collaborators from USD, SDSMT, SDSU, Sanford Lab, and Lawrence Berkeley National Laboratory are working on the development of techniques to manufacture crystals with unprecedented purity levels in an underground environment that may be used by experiments proposed for DUSEL. The collaboration continues to make significant progress toward its goal of producing high purity germanium crystals. High quality crystals are being pulled on a weekly basis at the temporary surface growth facility located on the USD campus. The characterization of the grown crystals demonstrates that the impurity levels are nearly in the range of the needed impurity level for detector-grade crystals. Currently, the crystals are being grown in high-purity hydrogen atmosphere. With an increase in purity due to the zone refining, the group expects to grow high-purity crystals by the end of 2011. The one third of the grown crystals will be manufactured to be detectors; the remaining will be fabricated in to wafers that have large applications in electro and optical devices as well as solar panels. This would allow the research to be connected to market and create more than 30 jobs and multi millions revenues in a few years.

  6. Limits on uranium and thorium bulk content in GERDA Phase I detectors

    CERN Document Server

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

    2016-01-01

    Internal contaminations of $^{238}$U, $^{235}$U and $^{232}$Th in the bulk of high purity germanium detectors are potential backgrounds for experiments searching for neutrinoless double beta decay of $^{76}$Ge. The data from GERDA Phase~I have been analyzed for alpha events from the decay chain of these contaminations by looking for full decay chains and for time correlations between successive decays in the same detector. No candidate events for a full chain have been found. Upper limits on the activities in the range of a few nBq/kg for $^{226}$Ra, $^{227}$Ac and $^{228}$Th, the long-lived daughter nuclides of $^{238}$U, $^{235}$U and $^{232}$Th, respectively, have been derived. With these upper limits a background index in the energy region of interest from $^{226}$Ra and $^{228}$Th contamination is estimated which satisfies the prerequisites of a future ton scale germanium double beta decay experiment.

  7. Simulation for photon detection in spectrometric system of high purity (HPGe) using MCNPX code; Simulacao de deteccao de fotons em sistema espectrometrico de alta pureza (HPGe) usando o codigo MCNPX

    Energy Technology Data Exchange (ETDEWEB)

    Correa, Guilherme Jorge de Souza

    2013-07-01

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

  8. An actively vetoed Clover gamma-detector for nuclear astrophysics at LUNA

    CERN Document Server

    Szucs, T; Broggini, C; Caciolli, A; Confortola, F; Corvisiero, P; Elekes, Z; Formicola, A; Fulop, Zs; Gervino, G; Guglielmetti, A; Gustavino, C; Gyurky, Gy; Imbriani, G; Junker, M; Lemut, A; Marta, M; Mazzocchi, C; Menegazzo, R; Prati, P; Roca, V; Rolfs, C; Alvarez, C Rossi; Somorjai, E; Straniero, O; Strieder, F; Terrasi, F; Trautvetter, H P

    2010-01-01

    An escape-suppressed, composite high-purity germanium detector of the Clover type has been installed at the Laboratory for Underground Nuclear Astrophysics (LUNA) facility, deep underground in the Gran Sasso Laboratory, Italy. The laboratory gamma-ray background of the Clover detector has been studied underground at LUNA and, for comparison, also in an overground laboratory. Spectra have been recorded both for the single segments and for the virtual detector formed by online addition of all four segments. The effect of the escape-suppression shield has been studied as well. Despite their generally higher intrinsic background, escape-suppressed detectors are found to be well suited for underground nuclear astrophysics studies. As an example for the advantage of using a composite detector deep underground, the weak ground state branching of the Ep = 223 keV resonance in the 24Mg(p,gamma)25Al reaction is determined with improved precision.

  9. The Liquid Argon Purity Demonstrator

    CERN Document Server

    Adamowski, M; Dvorak, E; Hahn, A; Jaskierny, W; Johnson, C; Jostlein, H; Kendziora, C; Lockwitz, S; Pahlka, B; Plunkett, R; Pordes, S; Rebel, B; Schmitt, R; Stancari, M; Tope, T; Voirin, E; Yang, T

    2014-01-01

    The Liquid Argon Purity Demonstrator was an R&D test stand designed to determine if electron drift lifetimes adequate for large neutrino detectors could be achieved without first evacuating the cryostat. We describe here the cryogenic system, its operations, and the apparatus used to determine the contaminant levels in the argon and to measure the electron drift lifetime. The liquid purity obtained by this system was facilitated by a gaseous argon purge. Additionally, gaseous impurities from the ullage were prevented from entering the liquid at the gas-liquid interface by condensing the gas and filtering the resulting liquid before returning to the cryostat. The measured electron drift lifetime in this test was greater than 6 ms, sustained over several periods of many weeks. Measurements of the temperature profile in the argon, to assess convective flow and boiling, were also made and are compared to simulation.

  10. The Liquid Argon Purity Demonstrator

    Energy Technology Data Exchange (ETDEWEB)

    Adamowski, M.; Carls, B.; Dvorak, E.; Hahn, A.; Jaskierny, W.; Johnson, C.; Jostlein, H.; Kendziora, C.; Lockwitz, S.; Pahlka, B.; Plunkett, R.; Pordes, S.; Rebel, B.; Schmitt, R.; Stancari, M.; Tope, T.; Voirin, E.; Yang, T.

    2014-07-01

    The Liquid Argon Purity Demonstrator was an R&D test stand designed to determine if electron drift lifetimes adequate for large neutrino detectors could be achieved without first evacuating the cryostat. We describe here the cryogenic system, its operations, and the apparatus used to determine the contaminant levels in the argon and to measure the electron drift lifetime. The liquid purity obtained by this system was facilitated by a gaseous argon purge. Additionally, gaseous impurities from the ullage were prevented from entering the liquid at the gas-liquid interface by condensing the gas and filtering the resulting liquid before returning to the cryostat. The measured electron drift lifetime in this test was greater than 6 ms, sustained over several periods of many weeks. Measurements of the temperature profile in the argon, to assess convective flow and boiling, were also made and are compared to simulation.

  11. Lung counting: comparison of detector performance with a four detector array that has either metal or carbon fibre end caps, and the effect on mda calculation.

    Science.gov (United States)

    Ahmed, Asm Sabbir; Hauck, Barry; Kramer, Gary H

    2012-08-01

    This study described the performance of an array of high-purity Germanium detectors, designed with two different end cap materials-steel and carbon fibre. The advantages and disadvantages of using this detector type in the estimation of the minimum detectable activity (MDA) for different energy peaks of isotope (152)Eu were illustrated. A Monte Carlo model was developed to study the detection efficiency for the detector array. A voxelised Lawrence Livermore torso phantom, equipped with lung, chest plates and overlay plates, was used to mimic a typical lung counting protocol with the array of detectors. The lung of the phantom simulated the volumetric source organ. A significantly low MDA was estimated for energy peaks at 40 keV and at a chest wall thickness of 6.64 cm.

  12. Modeling of dislocation dynamics in germanium Czochralski growth

    Science.gov (United States)

    Artemyev, V. V.; Smirnov, A. D.; Kalaev, V. V.; Mamedov, V. M.; Sidko, A. P.; Podkopaev, O. I.; Kravtsova, E. D.; Shimansky, A. F.

    2017-06-01

    Obtaining very high-purity germanium crystals with low dislocation density is a practically difficult problem, which requires knowledge and experience in growth processes. Dislocation density is one of the most important parameters defining the quality of germanium crystal. In this paper, we have performed experimental study of dislocation density during 4-in. germanium crystal growth using the Czochralski method and comprehensive unsteady modeling of the same crystal growth processes, taking into account global heat transfer, melt flow and melt/crystal interface shape evolution. Thermal stresses in the crystal and their relaxation with generation of dislocations within the Alexander-Haasen model have been calculated simultaneously with crystallization dynamics. Comparison to experimental data showed reasonable agreement for the temperature, interface shape and dislocation density in the crystal between calculation and experiment.

  13. Ultra-Low Noise Germanium Neutrino Detection system (ULGeN).

    Energy Technology Data Exchange (ETDEWEB)

    Cabrera-Palmer, Belkis [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Barton, Paul [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2017-07-01

    Monitoring nuclear power plant operation by measuring the antineutrino flux has become an active research field for safeguards and non-proliferation. We describe various efforts to demonstrate the feasibility of reactor monitoring based on the detection of the Coherent Neutrino Nucleus Scattering (CNNS) process with High Purity Germanium (HPGe) technology. CNNS detection for reactor antineutrino energies requires lowering the electronic noise in low-capacitance kg-scale HPGe detectors below 100 eV as well as stringent reduction in other particle backgrounds. Existing state- of-the-art detectors are limited to an electronic noise of 95 eV-FWHM. In this work, we employed an ultra-low capacitance point-contact detector with a commercial integrated circuit preamplifier- on-a-chip in an ultra-low vibration mechanically cooled cryostat to achieve an electronic noise of 39 eV-FWHM at 43 K. We also present the results of a background measurement campaign at the Spallation Neutron Source to select the area with sufficient low background to allow a successful first-time measurement of the CNNS process.

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

    Energy Technology Data Exchange (ETDEWEB)

    Homan, Victoria M [Los Alamos National Laboratory

    2010-10-25

    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.

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

    CERN Document Server

    Abt, Iris; Gooch, Chris; Irlbeck, Sabine; Liu, Xiang; Palermo, Matteo; Schulz, Oliver

    2016-01-01

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

  16. Quantum key distribution over 120 km using ultrahigh purity single-photon source and superconducting single-photon detectors

    Science.gov (United States)

    Takemoto, Kazuya; Nambu, Yoshihiro; Miyazawa, Toshiyuki; Sakuma, Yoshiki; Yamamoto, Tsuyoshi; Yorozu, Shinichi; Arakawa, Yasuhiko

    2015-09-01

    Advances in single-photon sources (SPSs) and single-photon detectors (SPDs) promise unique applications in the field of quantum information technology. In this paper, we report long-distance quantum key distribution (QKD) by using state-of-the-art devices: a quantum-dot SPS (QD SPS) emitting a photon in the telecom band of 1.5 μm and a superconducting nanowire SPD (SNSPD). At the distance of 100 km, we obtained the maximal secure key rate of 27.6 bps without using decoy states, which is at least threefold larger than the rate obtained in the previously reported 50-km-long QKD experiment. We also succeeded in transmitting secure keys at the rate of 0.307 bps over 120 km. This is the longest QKD distance yet reported by using known true SPSs. The ultralow multiphoton emissions of our SPS and ultralow dark count of the SNSPD contributed to this result. The experimental results demonstrate the potential applicability of QD SPSs to practical telecom QKD networks.

  17. In vivo measurement of actinides in the human lung. [Calibration and comparison of Phoswich, large-area proportional counter, and intrinsic germanium planar array detector systems

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, A.L.; Campbell, G.W.; Griffith, R.V.

    1979-11-06

    The problems associated with the in vivo detection and measurement of actinides in the human lung are discussed together with various measurement systems currently in use. In particular, the methods and calibration procedures employed at the Lawrence Livermore Laboratory, namely, the use of twin Phoswich detectors and a new, more realistic, tissue-equivalent phantom, are described. Methods for the measurement of chest-wall thickness, fat content, and normal human background counts are also discussed. Detection-efficiency values and minimum detectable activity estimates are given for three common actinides, /sup 238/Pu, /sup 239/Pu, and /sup 241/Am.

  18. Testing the Ge detectors for the MAJORANA DEMONSTRATOR

    CERN Document Server

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

    2014-01-01

    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.

  19. Attenuated total internal reflection infrared microspectroscopic imaging using a large-radius germanium internal reflection element and a linear array detector.

    Science.gov (United States)

    Patterson, Brian M; Havrilla, George J

    2006-11-01

    The number of techniques and instruments available for Fourier transform infrared (FT-IR) microspectroscopic imaging has grown significantly over the past few years. Attenuated total internal reflectance (ATR) FT-IR microspectroscopy reduces sample preparation time and has simplified the analysis of many difficult samples. FT-IR imaging has become a powerful analytical tool using either a focal plane array or a linear array detector, especially when coupled with a chemometric analysis package. The field of view of the ATR-IR microspectroscopic imaging area can be greatly increased from 300 x 300 microm to 2500 x 2500 microm using a larger internal reflection element of 12.5 mm radius instead of the typical 1.5 mm radius. This gives an area increase of 70x before aberrant effects become too great. Parameters evaluated include the change in penetration depth as a function of beam displacement, measurements of the active area, magnification factor, and change in spatial resolution over the imaging area. Drawbacks such as large file size will also be discussed. This technique has been successfully applied to the FT-IR imaging of polydimethylsiloxane foam cross-sections, latent human fingerprints, and a model inorganic mixture, which demonstrates the usefulness of the method for pharmaceuticals.

  20. Monte Carlo Comparisons to a Cryogenic Dark Matter Search Detector with low Transition-Edge-Sensor Transition Temperature

    CERN Document Server

    Leman, S W; Brink, P L; Cabrera, B; Cherry, M; Silva, E Do Couto E; Figueroa-Feliciano, E; Kim, P; Mirabolfathi, N; Pyle, M; Resch, R; Sadoulet, B; Serfass, B; Sundqvist, K M; Tomada, A; Young, B A

    2011-01-01

    We present results on phonon quasidiffusion and Transition Edge Sensor (TES) studies in a large, 3 inch diameter, 1 inch thick [100] high purity germanium crystal, cooled to 50 mK in the vacuum of a dilution refrigerator, and exposed with 59.5 keV gamma-rays from an Am-241 calibration source. We compare calibration data with results from a Monte Carlo which includes phonon quasidiffusion and the generation of phonons created by charge carriers as they are drifted across the detector by ionization readout channels. The phonon energy is then parsed into TES based phonon readout channels and input into a TES simulator.

  1. The MAJORANA DEMONSTRATOR: A Search for Neutrinoless Double-beta Decay of Germanium-76

    CERN Document Server

    Elliott, S R; Aguayo, E; Avignone, F T; Barabash, A S; Bertrand, F E; Boswell, M; Brudanin, V; Busch, M; Caldwell, A S; Chan, Y-D; Christofferson, C D; Combs, D C; Detwiler, J A; Doe, P J; Efremenko, Yu; Egorov, V; Ejiri, H; Esterline, J; Fast, J E; Finnerty, P; Fraenkleo, F M; Galindo-Uribarri, A; Giovanetti, G K; Goett, J; Green, M P; Gruszko, J; Guiseppe, V E; Gusev, K; Hallin, A L; Hazama, R; Hegai, A; Henning, R; Hoppe, E W; Howard, S; Howe, M A; Keeter, K J; Kidd, M F; Kochetov, O; Konovalov, S I; Kouzes, R T; LaFerriere, B D; Leon, J; Leviner, L E; Loach, J C; MacMullin, S; Martin, R D; Mertens, S; Mizouni, L; Nomachi, M; Orrell, J L; OShaughnessy, C; Overman, N R; Phillips, D G; Poon, A W P; Pushkin, K; Radford, D C; Rielage, K; Robertson, R G H; Ronquest, M C; Schubert, A G; Shanks, B; Shima, T; Shirchenko, M; Snavely, K J; Snyder, N; Soin, A; Strain, J; Suriano, A M; Timkin, V; Tornow, W; Varner, R L; Vasilyev, S; Vetter, K; Vorren, K; White, B R; Wilkerson, J F; Xu, W; Yakushev, E; Young, A R; Yu, C -H; Yumatov, V

    2013-01-01

    The {\\sc Majorana} collaboration is searching for neutrinoless double beta decay using $^{76}$Ge, which has been shown to have a number of advantages in terms of sensitivities and backgrounds. The observation of neutrinoless double-beta decay would show that lepton number is violated and that neutrinos are Majorana particles and would simultaneously provide information on neutrino mass. Attaining sensitivities for neutrino masses in the inverted hierarchy region, $15 - 50$ meV, will require large, tonne-scale detectors with extremely low backgrounds, at the level of $\\sim$1 count/t-y or lower in the region of the signal. The {\\sc Majorana} collaboration, with funding support from DOE Office of Nuclear Physics and NSF Particle Astrophysics, is constructing the {\\sc Demonstrator}, an array consisting of 40 kg of p-type point-contact high-purity germanium (HPGe) detectors, of which $\\sim$30 kg will be enriched to 87% in $^{76}$Ge. The {\\sc Demonstrator} is being constructed in a clean room laboratory facility at...

  2. Relative efficiency calculation of a HPGe detector using MCNPX code

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros, Marcos P.C.; Rebello, Wilson F., E-mail: eng.cavaliere@ime.eb.br, E-mail: rebello@ime.eb.br [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Secao de Engenharia Nuclear; Lopes, Jose M.; Silva, Ademir X., E-mail: marqueslopez@yahoo.com.br, E-mail: ademir@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear

    2015-07-01

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

  3. The use of CdTe detectors for dental X-ray spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Marcus Aurelio P. dos; Fragoso, Maria da Conceicao F.; Oliveira, Mercia L.; Lima, Ricardo de A.; Hazin, Clovis A. [Centro Regional de Ciencias Nucleares (CRCN/CNEN-PE), Recife, PE (Brazil)]. E-mails: masantos@cnen.gov.br; mariacc05@yahoo.com.br; mercial@cnen.gov.br; ralima@cnen.gov.br; chazin@cnen.gov.br

    2007-07-01

    he cadmium telluride (CdTe) semiconductor detector provides high detection efficiency for use in the diagnostic x-rays energy range, because of the high atomic number and high density of the crystal. Moreover, it has the great advantage of working at room temperature, in contrast to the germanium detector, which operates in liquid nitrogen temperature. The CdTe detector has been utilized in diagnostic x-ray spectroscopy, but only scarce information about its use in dental X-ray beams has been published. In this way, a portable 3x3x1 mm{sup 3} CdTe solid state detector (XR-100T CdTe by Amptek, Inc.) with tungsten pinhole collimators, alignment device and associated software was utilized in this work for measuring the photon spectra in the dental x-ray kVp range. A single-phase dental unit with adjustable kVp and mA was employed and the x-ray spectra were experimentally determined at 50, 60 and 70 kVp with 0.5 mA tube current. The pulse height distribution obtained with this detector, however, does not represent the 'true' photon spectra. For this reason, a stripping procedure was implemented to correct the distribution in order to determine the real photon spectra. The x-ray spectra obtained with the CdTe detector were compared with the ones measured with a high-purity germanium detector (EGP200-13-TR by Eurisys Mesures). The reasonable agreement between the results obtained with both detectors for the 50 to 70 keV range show that CdTe detectors can be utilized for dental x-ray spectrometry. (author)

  4. Measurement of photoelectron yield of the CDEX-10 liquid argon detector prototype

    Science.gov (United States)

    Chen, Qing-Hao; Yue, Qian; Cheng, Jian-Ping; Kang, Ke-Jun; Li, Yuan-Jing; Lin, Shin-Ted; Tang, Chang-Jian; Xing, Hao-Yang; Yu, Xun-Zhen; Zeng, Ming; Zhu, Jing-Jun

    2016-11-01

    The China Dark Matter Experiment (CDEX) is a low background experiment at China Jinping Underground Laboratory (CJPL) designed to directly detect dark matter with a high-purity germanium (HPGe) detector. In the second phase, CDEX-10, which has a 10 kg germanium array detector system, a liquid argon (LAr) anti-Compton active shielding and cooling system is proposed. To study the properties of the LAr detector, a prototype with an active volume of 7 liters of liquid argon was built and operated. The photoelectron yields, as a critically important parameter for the prototype detector, have been measured to be 0.051-0.079 p.e./keV for 662 keV γ rays at different positions. The good agreement between the experimental and simulation results has provided a reasonable understanding and determination of the important parameters such as the surviving fraction of the excimers, the absorption length for 128 nm photons in liquid argon, the reflectivity of Teflon and so on.

  5. Photoelectron yield in the prototype of the liquid argon detector for CDEX-10

    CERN Document Server

    Chen, Qing-Hao; Cheng, Jian-Ping; Kang, Ke-Jun; Li, Yuan-Jing; Lin, Shin-Ted; Tang, Chang-Jian; Xing, Hao-Yang; Yu, Xun-Zhen; Zeng, Ming

    2015-01-01

    The China Dark Matter Experiment (CDEX) is a low background experiment at China Jinping Underground Laboratory (CJPL) designed to directly detect dark matter with a high-purity germanium (HPGe) detector. In the second phase CDEX-10 with 10 kg germanium array detector system, the liquid argon (LAr) anti-Compton active shielding and cooling system is proposed. For purpose of studying the properties of LAr detector, a prototype with an active volume of 7 liters of liquid argon was built and operated. The photoelectron yields, as a critically important parameter for the LAr detector, have been measured to be 0.051-0.079 p.e./keV for 662 keV gamma lines at different positions. The good agreement between the experimental and simulation results has provided a quite reasonable understanding and determination of the important parameters such as the Surviving Fraction of the $Ar_{2}^{*}$ excimers, the absorption length for 128 nm photons in liquid argon, the reflectivity of Teflon and so on.

  6. Study of accuracy in the position determination with SALSA, a γ-scanning system for the characterization of segmented HPGe detectors

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Prieto, A., E-mail: alvaro.prieto@usal.es [Laboratorio de Radiaciones Ionizantes, Departamento de Física Fundamental, Universidad de Salamanca, C /Espejo s/n, Salamanca (Spain); Quintana, B.; Martìn, S. [Laboratorio de Radiaciones Ionizantes, Departamento de Física Fundamental, Universidad de Salamanca, C /Espejo s/n, Salamanca (Spain); Domingo-Pardo, C. [Instituto de Física Corpuscular, C /Catedrático José Beltrán, 2, Paterna (Spain)

    2016-07-01

    Accurate characterization of the electric response of segmented high-purity germanium (HPGe) detectors as a function of the interaction position is one of the current goals of the Nuclear Physics community seeking to perform γ-ray tracking or even imaging with these detectors. For this purpose, scanning devices must be developed to achieve the signal-position association with the highest precision. With a view to studying the accuracy achieved with SALSA, the SAlamanca Lyso-based Scanning Array, here we report a detailed study on the uncertainty sources and their effect in the position determination inside the HPGe detector to be scanned. The optimization performed on the design of SALSA, aimed at minimizing the effect of the uncertainty sources, afforded an intrinsic uncertainty of ∼2 mm for large coaxial detectors and ∼1 mm for planar ones.

  7. Search for $2\\beta$ decay of $^{106}$Cd with enriched $^{106}$CdWO$_4$ crystal scintillator in coincidence with four HPGe detectors

    CERN Document Server

    Belli, P; Brudanin, V B; Cappella, F; Caracciolo, V; Cerulli, R; Chernyak, D M; Danevich, F A; d'Angelo, S; Di Marco, A; Incicchitti, A; Laubenstein, M; Mokina, V M; Poda, D V; Polischuk, O G; Tretyak, V I; Tupitsyna, I A

    2016-01-01

    A radiopure cadmium tungstate crystal scintillator, enriched in $^{106}$Cd to 66%, with mass of 216 g ($^{106}$CdWO$_4$), was used to search for double beta decay processes in $^{106}$Cd in coincidence with four ultra-low background high purity germanium detectors in a single cryostat. New improved limits on the double beta processes in $^{106}$Cd have been set on the level of $10^{20}- 10^{21}$ yr after 13085 h of data taking. In particular, the half-life limit on the two neutrino electron capture with positron emission, $T_{1/2}^{2\

  8. Monte Carlo simulation of background characteristics of a HPGe detector operating underground in the Gran Sasso National Laboratory.

    Science.gov (United States)

    Breier, R; Laubenstein, M; Povinec, P P

    2017-08-01

    Monte Carlo (MC) simulation of background components of an ultra-low background high purity germanium (HPGe) detector operating in a deep underground laboratory was carried out. The results show that the background of the HPGe detector is about two orders of magnitude higher than the MC prediction when accounting only for cosmic-ray induced background. The difference is due to natural radioactivity in the parts surrounding the Ge detector. To get reasonable agreement between MC simulations and the experiment, a contamination in the parts surrounding the Ge crystal from (40)K, (208)Tl and (214)Bi of 0.1mBqkg(-1) was required to include in the simulations. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    M Moeinifar

    2017-02-01

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

  10. Germanium recovery from gasification fly ash: evaluation of end-products obtained by precipitation methods.

    Science.gov (United States)

    Arroyo, Fátima; Font, Oriol; Fernández-Pereira, Constantino; Querol, Xavier; Juan, Roberto; Ruiz, Carmen; Coca, Pilar

    2009-08-15

    In this study the purity of the germanium end-products obtained by two different precipitation methods carried out on germanium-bearing solutions was evaluated as a last step of a hydrometallurgy process for the recovery of this valuable element from the Puertollano Integrated Gasification Combined Cycle (IGCC) fly ash. Since H(2)S is produced as a by-product in the gas cleaning system of the Puertollano IGCC plant, precipitation of germanium as GeS(2) was tested by sulfiding the Ge-bearing solutions. The technological and hazardous issues that surround H(2)S handling conducted to investigate a novel precipitation procedure: precipitation as an organic complex by adding 1,2-dihydroxy benzene pyrocatechol (CAT) and cetyltrimethylammonium bromide (CTAB) to the Ge-bearing solutions. Relatively high purity Ge end-products (90 and 93% hexagonal-GeO(2) purity, respectively) were obtained by precipitating Ge from enriched solutions, as GeS(2) sulfiding the solutions with H(2)S, or as organic complex with CAT/CTAB mixtures and subsequent roasting of the precipitates. Both methods showed high efficiency (>99%) to precipitate selectively Ge using a single precipitation stage from germanium-bearing solutions.

  11. High-pressure xenon detector development at Constellation Technology Corporation

    Energy Technology Data Exchange (ETDEWEB)

    Austin, Robert A. [Constellation Technology Corporation, 7887 Bryan Dairy Road, Suite 100, Largo, FL 33777 (United States)], E-mail: austin@contech.com

    2007-08-21

    Xenon-filled ionization detectors, due to their high atomic number fill gas (Z=54), moderate densities ({approx}0.3-0.5 g/cm{sup 3}) and good energy resolution (2-4% at 662 keV), fill an important niche between more familiar technologies such as NaI(Tl) scintillators and germanium detectors. Until recently, difficulties with obtaining sufficient xenon purity, reducing microphonic sensitivity, and developing low-noise electronics compatible with small ionization signals have hampered the development of this nuclear detection field. Constellation Technology Corporation, whose experience with xenon detectors goes back to the mid 1990s, has made significant progress in these areas and has developed a commercial line of detectors with active volumes ranging from small (35 g Xe) to large (1400 g Xe). Current applications for Constellation's detectors are principally in the area of defense (Unmanned Aerial Vehicles and Advanced Spectroscopic Portals), but as awareness of this technology grows, it will surely find applications in a much expanded range of fields.

  12. High-pressure xenon detector development at Constellation Technology Corporation

    Science.gov (United States)

    Austin, Robert A.

    2007-08-01

    Xenon-filled ionization detectors, due to their high atomic number fill gas ( Z=54), moderate densities (˜0.3-0.5 g/cm 3) and good energy resolution (2-4% at 662 keV), fill an important niche between more familiar technologies such as NaI(Tl) scintillators and germanium detectors. Until recently, difficulties with obtaining sufficient xenon purity, reducing microphonic sensitivity, and developing low-noise electronics compatible with small ionization signals have hampered the development of this nuclear detection field. Constellation Technology Corporation, whose experience with xenon detectors goes back to the mid 1990s, has made significant progress in these areas and has developed a commercial line of detectors with active volumes ranging from small (35 g Xe) to large (1400 g Xe). Current applications for Constellation's detectors are principally in the area of defense (Unmanned Aerial Vehicles and Advanced Spectroscopic Portals), but as awareness of this technology grows, it will surely find applications in a much expanded range of fields.

  13. Multiagency Urban Search Experiment Detector and Algorithm Test Bed

    Science.gov (United States)

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

    2017-07-01

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

  14. A cooled avalanche photodiode detector for X-ray magnetic diffraction experiments

    CERN Document Server

    Kishimoto, S; Ito, M

    2001-01-01

    A cooled avalanche photodiode (APD) detector was developed for X-ray magnetic diffraction experiments. A stack of four silicon APDs was cooled down to 243 K by a thermoelectric cooler. The energy widths of 0.89 and 1.55 keV (FWHM) were obtained for 8.05 keV X-rays at 1x10 sup 6 s sup - sup 1 and for 16.53 keV X-rays at 2x10 sup 6 s sup - sup 1 , respectively. Test measurements of X-ray magnetic diffraction were executed using a terbium single crystal and white synchrotron radiation. A peak width of (1 0 3) reflection (5.4 keV) was roughly three times wider than that with a high-purity germanium detector.

  15. A Software Package Using a Mesh-grid Method for Simulating HPGe Detector Efficiencies

    Energy Technology Data Exchange (ETDEWEB)

    Kevin Jackman

    2009-10-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-01-01

    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.

  17. Germanium geochemistry and mineralogy

    Science.gov (United States)

    Bernstein, L.R.

    1985-01-01

    Germanium is enriched in the following geologic environments: 1. (1) iron meteorites and terrestrial iron-nickel; 2. (2) sulfide ore deposits, particularly those hosted by sedimentary rocks; 3. (3) iron oxide deposits; 4. (4) oxidized zones of Ge-bearing sulfide deposits; 5. (5) pegmatites, greisens, and skarns; and 6. (6) coal and lignitized wood. In silicate melts, Ge is highly siderophile in the presence of native iron-nickel; otherwise, it is highly lithophile. Among silicate minerals, Ge is concentrated in those having less polymerized silicate tetrahedra such as olivine and topaz. In deposits formed from hydrothermal solutions, Ge tends to be enriched mostly in either sulfides or in fluorine-bearing phases; it is thus concentrated both in some hydrothermal sulfide deposits and in pegmatites, greisens, and skarns. In sulfide deposits that formed from solutions having low to moderate sulfur activity, Ge is concentrated in sphalerite in amounts up to 3000 ppm. Sulfide deposits that formed from solutions having higher sulfur activity allowed Ge to either form its own sulfides, particularly with Cu, or to substitute for As, Sn, or other metals in sulfosalts. The Ge in hydrothermal fluids probably derives from enrichment during the fractional crystallization of igneous fluids, or is due to the incorporation of Ge from the country rocks, particularly from those containing organic material. Germanium bonds to lignin-derivative organic compounds that are found in peat and lignite, accounting for its common concentration in coals and related organic material. Germanium is precipitated from water together with iron hydroxide, accounting for its concentration in some sedimentary and supergene iron oxide deposits. It also is able to substitute for Fe in magnetite in a variety of geologic environments. In the oxidized zone of Ge-bearing sulfide deposits, Ge is concentrated in oxides, hydroxides, and hydroxy-sulfates, sometimes forming its own minerals. It is particularly

  18. Magnetic Microcalorimeter Gamma Detectors for High-Precision Non-Destructive Analysis, FY14 Extended Annual Report

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-02-06

    Cryogenic gamma (γ) detectors with operating temperatures of ~0.1 K or below offer 10× better energy resolution than conventional high-purity germanium detectors that are currently used for non-destructive analysis (NDA) of nuclear materials. This can greatly increase the accuracy of NDA, especially at low-energies where gamma rays often have similar energies and cannot be resolved by Ge detectors. We are developing cryogenic γ–detectors based on metallic magnetic calorimeters (MMCs), which have the potential of higher resolution, faster count rates and better linearity than other cryogenic detector technologies. High linearity is essential to add spectra from different pixels in detector arrays that are needed for high sensitivity. Here we discuss the fabrication of a new generation of MMC γ–detectors in FY2014, and the resulting improvements in energy resolution and linearity of the new design. As an example of the type of NDA that cryogenic detectors enable, we demonstrate the direct detection of Pu-242 emissions with our MMC γ–detectors in the presence of Pu-240, and show that a quantitative NDA analysis agrees with the mass spectrometry

  19. Long-term radiation damage to a spaceborne germanium spectrometer

    CERN Document Server

    Kurczynski, P; Hull, E L; Palmer, D; Harris, M J; Seifert, H; Teegarden, B J; Gehrels, N; Cline, T L; Ramaty, R; Sheppard, D; Madden, N W; Luke, P N; Cork, C P; Landis, D A; Malone, D F; Hurley, K

    1999-01-01

    The Transient Gamma-Ray Spectrometer aboard the Wind spacecraft in deep space has observed gamma-ray bursts and solar events for four years. The germanium detector in the instrument has gradually deteriorated from exposure to the approx 10 sup 8 p/cm sup 2 /yr(>100 MeV) cosmic-ray flux. Low-energy tailing and loss of efficiency, attributed to hole trapping and conversion of the germanium from n- to p-type as a result of crystal damage, were observed. Raising the detector bias voltage ameliorated both difficulties and restored the spectrometer to working operation. Together, these observations extend our understanding of the effects of radiation damage to include the previously unsuccessfully studied regime of long-term operation in space. (author)

  20. Hafnium germanium telluride

    Science.gov (United States)

    Jang, Gyung-Joo; Yun, Hoseop

    2008-01-01

    The title hafnium germanium telluride, HfGeTe4, has been synthesized by the use of a halide flux and structurally characterized by X-ray diffraction. HfGeTe4 is isostructural with stoichiometric ZrGeTe4 and the Hf site in this compound is also fully occupied. The crystal structure of HfGeTe4 adopts a two-dimensional layered structure, each layer being composed of two unique one-dimensional chains of face-sharing Hf-centered bicapped trigonal prisms and corner-sharing Ge-centered tetra­hedra. These layers stack on top of each other to complete the three-dimensional structure with undulating van der Waals gaps. PMID:21202163

  1. Hafnium germanium telluride

    Directory of Open Access Journals (Sweden)

    Hoseop Yun

    2008-05-01

    Full Text Available The title hafnium germanium telluride, HfGeTe4, has been synthesized by the use of a halide flux and structurally characterized by X-ray diffraction. HfGeTe4 is isostructural with stoichiometric ZrGeTe4 and the Hf site in this compound is also fully occupied. The crystal structure of HfGeTe4 adopts a two-dimensional layered structure, each layer being composed of two unique one-dimensional chains of face-sharing Hf-centered bicapped trigonal prisms and corner-sharing Ge-centered tetrahedra. These layers stack on top of each other to complete the three-dimensional structure with undulating van der Waals gaps.

  2. HIgh Rate X-ray Fluorescence Detector

    Energy Technology Data Exchange (ETDEWEB)

    Grudberg, Peter Matthew [XIA LLC

    2013-04-30

    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 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

  3. Measurements on a prototype segmented Clover detector

    CERN Document Server

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

    1999-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-04-23

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

  5. Low background detector with enriched 116CdWO4 crystal scintillators to search for double beta decay of 116Cd

    CERN Document Server

    Barabash, A S; Bernabei, R; Boiko, R S; Cappella, F; Caracciolo, V; Chernyak, D M; Cerulli, R; Danevich, F A; Di Vacri, M L; Dossovitskiy, A E; Galashov, E N; Incicchitti, A; Kobychev, V V; Konovalov, S I; Kovtun, G P; Kudovbenko, V M; Laubenstein, M; Mikhlin, A L; Nisi, S; Poda, D V; Podviyanuk, R B; Polischuk, O G; Shcherban, A P; Shlegel, V N; Solopikhin, D A; Stenin, Yu G; Tretyak, V I; Umatov, V I; Vasiliev, Ya V; Virich, V D

    2011-01-01

    A cadmium tungstate crystal boule enriched in $^{116}$Cd to 82% with mass of 1868 g was grown by the low-thermal-gradient Czochralski technique. The isotopic composition of cadmium and the trace contamination of the crystal were estimated by High Resolution Inductively Coupled Plasma Mass-Spectrometry. The crystal scintillators produced from the boule were subjected to characterization that included measurements of transmittance and energy resolution. A low background scintillation detector with two $^{116}$CdWO$_4$ crystal scintillators (586 g and 589 g) was developed. The detector was running over 1727 h deep underground at the Gran Sasso National Laboratories of the INFN (Italy), which allowed to estimate the radioactive contamination of the enriched crystal scintillators. The radiopurity of a third $^{116}$CdWO$_4$ sample (326 g) was tested with the help of ultra-low background high purity germanium $\\gamma$ detector. Monte Carlo simulations of double $\\beta$ processes in $^{116}$Cd were used to estimate ...

  6. Gamma-ray multiplicity measurement of the spontaneous fission of {sup 252}Cf in a segmented HPGe/BGO detector array

    Energy Technology Data Exchange (ETDEWEB)

    Bleuel, D.L., E-mail: bleuel1@llnl.go [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States); Bernstein, L.A.; Burke, J.T. [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States); Gibelin, J. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Heffner, M.D. [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States); Mintz, J. [Nuclear Engineering Department, University of California, Berkeley, CA 94720 (United States); Norman, E.B. [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Nuclear Engineering Department, University of California, Berkeley, CA 94720 (United States); Phair, L. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Scielzo, N.D.; Sheets, S.A.; Snyderman, N.J.; Stoyer, M.A. [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States); Wiedeking, M. [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2010-12-21

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

  7. Determination of relative efficiency of a detector using Monte Carlo method; Determinacao da eficiencia relativa de um detector usando metodo de Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros, M.P.C.; Rebello, W.F., E-mail: eng.cavaliere@ime.eb.br, E-mail: rebello@ime.eb.br [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Secao de Engenharia Nuclear; Lopes, J.M.; Silva, A.X., E-mail: marqueslopez@yahoo.com.br, E-mail: ademir@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear

    2015-07-01

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

  8. Firewalls From Double Purity

    CERN Document Server

    Bousso, Raphael

    2013-01-01

    The firewall paradox is often presented as arising from double entanglement, but I argue that more generally the paradox is double purity. Near-horizon modes are purified by the interior, in the infalling vacuum. Hence they cannot also be pure alone, or in combination with any third system, as demanded by unitarity. This conflict arises independently of the Page time, for entangled and for pure states. It implies that identifications of Hilbert spaces cannot resolve the paradox. Traditional complementarity requires the unitary identification of infalling matter with a scrambled subsystem of the Hawking radiation. Extending this map to the infalling vacuum overdetermines the out-state. More general complementarity maps ("A=R_B", "ER=EPR") founder when the near-horizon zone is pure. I argue that pure-zone states span the microcanonical ensemble, and that this suffices to make the horizon a special place. I advocate that the ability to detect the horizon locally, rather than the degree or probability of violence...

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

    Science.gov (United States)

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

    2014-11-01

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

  10. The Germanium Dichotomy in Martian Meteorites

    Science.gov (United States)

    Humayun, M.; Yang, S.; Righter, K.; Zanda, B.; Hewins, R. H.

    2016-01-01

    Germanium is a moderately volatile and siderophile element that follows silicon in its compatibility during partial melting of planetary mantles. Despite its obvious usefulness in planetary geochemistry germanium is not analyzed routinely, with there being only three prior studies reporting germanium abundances in Martian meteorites. The broad range (1-3 ppm) observed in Martian igneous rocks is in stark contrast to the narrow range of germanium observed in terrestrial basalts (1.5 plus or minus 0.1 ppm). The germanium data from these studies indicates that nakhlites contain 2-3 ppm germanium, while shergottites contain approximately 1 ppm germanium, a dichotomy with important implications for core formation models. There have been no reliable germanium abundances on chassignites. The ancient meteoritic breccia, NWA 7533 (and paired meteorites) contains numerous clasts, some pristine and some impact melt rocks, that are being studied individually. Because germanium is depleted in the Martian crust relative to chondritic impactors, it has proven useful as an indicator of meteoritic contamination of impact melt clasts in NWA 7533. The germanium/silicon ratio can be applied to minerals that might not partition nickel and iridium, like feldspars. We report germanium in minerals from the 3 known chassignites, 2 nakhlites and 5 shergottites by LAICP- MS using a method optimized for precise germanium analysis.

  11. Compton imaging with a highly-segmented, position-sensitive HPGe detector

    Science.gov (United States)

    Steinbach, T.; Hirsch, R.; Reiter, P.; Birkenbach, B.; Bruyneel, B.; Eberth, J.; Gernhäuser, R.; Hess, H.; Lewandowski, L.; Maier, L.; Schlarb, M.; Weiler, B.; Winkel, M.

    2017-02-01

    A Compton camera based on a highly-segmented high-purity germanium (HPGe) detector and a double-sided silicon-strip detector (DSSD) was developed, tested, and put into operation; the origin of γ radiation was determined successfully. The Compton camera is operated in two different modes. Coincidences from Compton-scattered γ-ray events between DSSD and HPGe detector allow for best angular resolution; while the high-efficiency mode takes advantage of the position sensitivity of the highly-segmented HPGe detector. In this mode the setup is sensitive to the whole 4π solid angle. The interaction-point positions in the 36-fold segmented large-volume HPGe detector are determined by pulse-shape analysis (PSA) of all HPGe detector signals. Imaging algorithms were developed for each mode and successfully implemented. The angular resolution sensitively depends on parameters such as geometry, selected multiplicity and interaction-point distances. Best results were obtained taking into account the crosstalk properties, the time alignment of the signals and the distance metric for the PSA for both operation modes. An angular resolution between 13.8° and 19.1°, depending on the minimal interaction-point distance for the high-efficiency mode at an energy of 1275 keV, was achieved. In the coincidence mode, an increased angular resolution of 4.6° was determined for the same γ-ray energy.

  12. Correction for hole trapping in AGATA detectors using pulse shape analysis

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-05-15

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

  13. Impact of detector efficiency and energy resolution on gamma-ray background rejection in mobile spectroscopy and imaging systems

    Energy Technology Data Exchange (ETDEWEB)

    Aucott, Timothy J., E-mail: Timothy.Aucott@SRS.gov [Lawrence Berkeley National Laboratory, Nuclear Science Division, Berkeley, CA (United States); Bandstra, Mark S. [Lawrence Berkeley National Laboratory, Nuclear Science Division, Berkeley, CA (United States); Negut, Victor; Curtis, Joseph C. [University of California, Berkeley, Department of Nuclear Engineering, Berkeley, CA (United States); Meyer, Ross E.; Chivers, Daniel H. [Lawrence Berkeley National Laboratory, Nuclear Science Division, Berkeley, CA (United States); Vetter, Kai [University of California, Berkeley, Department of Nuclear Engineering, Berkeley, CA (United States); Lawrence Berkeley National Laboratory, Nuclear Science Division, Berkeley, CA (United States)

    2015-07-21

    The presence of gamma-ray background significantly reduces detection sensitivity when searching for radioactive sources in the field, and the systematic variability in the background will limit the size and energy resolution of systems that can be used effectively. An extensive survey of the background was performed using both sodium iodide and high-purity germanium. By using a bivariate negative binomial model for the measured counts, these measurements can be resampled to simulate the performance of a detector array of arbitrary size and resolution. The response of the system as it moved past a stationary source was modeled for spectroscopic and coded aperture imaging algorithms and used for source injection into the background. The performance of both techniques is shown for various sizes and resolutions, as well as the relative performance for sodium iodide and germanium. It was found that at smaller detector sizes or better energy resolution, spectroscopy has higher detection sensitivity than imaging, while imaging is better suited to larger or poorer resolution detectors.

  14. Two-Dimensional Spatial Imaging of Charge Transport in Germanium Crystals at Cryogenic Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Moffatt, Robert [Stanford U.

    2016-01-01

    In this dissertation, I describe a novel apparatus for studying the transport of charge in semiconductors at cryogenic temperatures. The motivation to conduct this experiment originated from an asymmetry observed between the behavior of electrons and holes in the germanium detector crystals used by the Cryogenic Dark Matter Search (CDMS). This asymmetry is a consequence of the anisotropic propagation of electrons in germanium at cryogenic temperatures. To better model our detectors, we incorporated this effect into our Monte Carlo simulations of charge transport. The purpose of the experiment described in this dissertation is to test those models in detail. Our measurements have allowed us to discover a shortcoming in our most recent Monte Carlo simulations of electrons in germanium. This discovery would not have been possible without the measurement of the full, two-dimensional charge distribution, which our experimental apparatus has allowed for the first time at cryogenic temperatures.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-12-04

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Wiens, Andreas

    2011-06-20

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

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

    Science.gov (United States)

    Medhat, M E; Wang, Yifang

    2014-02-01

    Monte Carlo simulations are powerful tools used to estimate the background γ-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.

  18. Study of the {sup 22}Ne(p,γ){sup 23}Na reaction at LUNA with a 4π BGO summing detector

    Energy Technology Data Exchange (ETDEWEB)

    Takacs, Marcell Peter; Bemmerer, Daniel; Szuecs, Tamas [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); Collaboration: LUNA-Collaboration

    2015-07-01

    The {sup 22}Ne(p,γ){sup 23}Na reaction takes part in the neon-sodium cycle of hydrogen burning. This cycle is active in asymptotic giant branch stars as well as in novae and contributes to the nucleosythesis of neon and sodium isotopes. In order to reduce the uncertainties in the predicted nucleosynthesis yields, new experimental efforts to measure the {sup 22}Ne(p,γ){sup 23}Na cross section directly at the astrophysically relevant energies are needed. In the first, recently completed phase of the LUNA {sup 22}Ne(p,γ){sup 23}Na experiment, selected low-energy resonances were studied with two high-purity germanium detectors. In the present talk, the preparations for the second experimental phase are reported. In this phase, a 4π bismuth germanate summing detector will be used to address the lowest-energy resonances as well as direct capture.

  19. The Silicon Cube detector

    Energy Technology Data Exchange (ETDEWEB)

    Matea, I.; Adimi, N. [Centre d' Etudes Nucleaires de Bordeaux Gradignan - Universite Bordeaux 1 - UMR 5797, CNRS/IN2P3, Chemin du Solarium, BP 120, F-33175 Gradignan Cedex (France); Blank, B. [Centre d' Etudes Nucleaires de Bordeaux Gradignan - Universite Bordeaux 1 - UMR 5797, CNRS/IN2P3, Chemin du Solarium, BP 120, F-33175 Gradignan Cedex (France)], E-mail: blank@cenbg.in2p3.fr; Canchel, G.; Giovinazzo, J. [Centre d' Etudes Nucleaires de Bordeaux Gradignan - Universite Bordeaux 1 - UMR 5797, CNRS/IN2P3, Chemin du Solarium, BP 120, F-33175 Gradignan Cedex (France); Borge, M.J.G.; Dominguez-Reyes, R.; Tengblad, O. [Insto. Estructura de la Materia, CSIC, Serrano 113bis, E-28006 Madrid (Spain); Thomas, J.-C. [GANIL, CEA/DSM - CNRS/IN2P3, BP 55027, F-14076 Caen Cedex 5 (France)

    2009-08-21

    A new experimental device, the Silicon Cube detector, consisting of six double-sided silicon strip detectors placed in a compact geometry was developed at CENBG. Having a very good angular coverage and high granularity, it allows simultaneous measurements of energy and angular distributions of charged particles emitted from unbound nuclear states. In addition, large-volume Germanium detectors can be placed close to the collection point of the radioactive species to be studied. The setup is ideally suited for isotope separation on-line (ISOL)-type experiments to study multi-particle emitters and was tested during an experiment at the low-energy beam line of SPIRAL at GANIL.

  20. Study on the local atomic structure of germanium in organic germanium compounds by EXAFS

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Organic germanium compounds have been extensively applied in medicine as tonics,In this paper,the local structures of two organic germanium compounds,carboxyethylgermanium sesquioxide and polymeric germanium glutamate,were determined by EXAFS.The structure parameters including coordination numbers and bond lengths were reported,and possible structure patterns were discussed.

  1. Atomic ionization of germanium by neutrinos from an ab initio approach

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jiunn-Wei [Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China); National Center for Theoretical Sciences and Leung Center for Cosmology and Particle Astrophysics, National Taiwan University, Taipei 10617, Taiwan (China); Chi, Hsin-Chang [Department of Physics, National Dong Hwa University, Shoufeng, Hualien 97401, Taiwan (China); Huang, Keh-Ning [Department of Physics, Sichuan University, Chengdu, Sichuan (China); Department of Physics, Fuzhou University, Fuzhou, Fujian (China); Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China); Liu, C.-P. [Department of Physics, National Dong Hwa University, Shoufeng, Hualien 97401, Taiwan (China); Shiao, Hao-Tse [Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China); Singh, Lakhwinder [Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Department of Physics, Banaras Hindu University, Varanasi 221005 (India); Wong, Henry T. [Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Wu, Chih-Liang; Wu, Chih-Pan [Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China)

    2014-04-04

    An ab initio calculation of atomic ionization of germanium by neutrinos was carried out in the framework of multiconfiguration relativistic random phase approximation and benchmarked by related atomic structure and photoabsorption data. This improves over the conventional approach based on scattering off free electrons whose validity at sub-keV energy transfer is questionable. Limits on neutrino magnetic moments are derived using reactor neutrino data taken with low threshold germanium detectors. Future applications of these atomic techniques will greatly reduce the atomic uncertainties in low-energy neutrino and dark matter detections.

  2. Optimization of the Transport Shield for Neutrinoless Double Beta-decay Enriched Germanium

    Energy Technology Data Exchange (ETDEWEB)

    Aguayo Navarrete, Estanislao; Kouzes, Richard T.; Orrell, John L.; Reid, Douglas J.; Fast, James E.

    2012-04-15

    This document presents results of an investigation of the material and geometry choice for the transport shield of germanium, the active detector material used in 76Ge neutrinoless double beta decay searches. The objective of this work is to select the optimal material and geometry to minimize cosmogenic production of radioactive isotopes in the germanium material. The design of such a shield is based on the calculation of the cosmogenic production rate of isotopes that are known to cause interfering backgrounds in 76Ge neutrinoless double beta decay searches.

  3. Harmonic Lattice Dynamics of Germanium

    Energy Technology Data Exchange (ETDEWEB)

    Nelin, G.

    1974-07-01

    The phonon dispersion relations of the DELTA-, LAMBDA-, and SIGMA-directions of germanium at 80 K are analysed in terms of current harmonic lattice dynamical models. On the basis of this experience, a new model is proposed which gives a unified account of the strong points of the previous models. The principal elements of the presented theory are quasiparticle bond charges combined with a valence force field.

  4. Application of Plasma Emission Detector in Determination of Trace Neon in High Purity Helium%等离子体发射检测器在检测高纯氦气中微量氖气的应用

    Institute of Scientific and Technical Information of China (English)

    胡树国; 张体强

    2016-01-01

    Trace neon in helium prepared by gravimetric method was determined by gas chromatography with plasma emission detector and discharge ionization detector. Sensitivity and repeatability of trace neon in different detector were compared. The results showed that the detection sensitivity of PED was higher, the linear range of neon was 0.03-0.3μmol/mol,the correlation coefficients (r2) was 1.000,the detection limit was less than 1 nmol/mol,the RSD was less than 2%(n=6). By comparing the data of atmosphere pressure ion mass spectrometry,the reliability of the results was verified. The determination of trace neon in helium byplasma emission detector may decrease the uncertainty of neon reference material,which lays the foundation of development of high precision trace neon standard material.%采用等离子发射检测器(PED)和氦离子放电检测器(DID)对重量法制备的氦气中微量氖气进行了检测,对比了微量氖气在两种检测器上的灵敏度和重复性.结果显示,PED对氖气的检测灵敏度较高,氖气含量在0.03~0.3μmol/mol范围与响应值呈良好的线性关系,r2=1.000,检测限小于1 nmol/mol,测定结果的相对偏差小于2%(n=6).利用大气压离子质谱仪对检测限测试结果进行了验证.采用等离子发射检测器检测氦气中微量氖气的方法,可以降低微量氖气标准物质的定值不确定度,为研制高准确度微量氖气标准物质奠定基础.

  5. Black Germanium fabricated by reactive ion etching

    Science.gov (United States)

    Steglich, Martin; Käsebier, Thomas; Kley, Ernst-Bernhard; Tünnermann, Andreas

    2016-09-01

    A reactive ion etching technique for the preparation of statistical "Black Germanium" antireflection surfaces, relying on self-organization in a Cl2 etch chemistry, is presented. The morphology of the fabricated Black Germanium surfaces is the result of a random lateral distribution of pyramidal etch pits with heights around (1450 ± 150) nm and sidewall angles between 80° and 85°. The pyramids' base edges are oriented along the crystal directions of Germanium, indicating a crystal anisotropy of the etching process. In the Vis-NIR, the tapered Black Germanium surface structure suppresses interface reflection to structure in optoelectronics and IR optics.

  6. Hydrothermal synthesis of bismuth germanium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Boyle, Timothy J.

    2016-12-13

    A method for the hydrothermal synthesis of bismuth germanium oxide comprises dissolving a bismuth precursor (e.g., bismuth nitrate pentahydrate) and a germanium precursor (e.g., germanium dioxide) in water and heating the aqueous solution to an elevated reaction temperature for a length of time sufficient to produce the eulytite phase of bismuth germanium oxide (E-BGO) with high yield. The E-BGO produced can be used as a scintillator material. For example, the air stability and radioluminescence response suggest that the E-BGO can be employed for medical applications.

  7. Structural Design Parameters for Germanium

    Science.gov (United States)

    Salem, Jon; Rogers, Richard; Baker, Eric

    2017-01-01

    The fracture toughness and slow crack growth parameters of germanium supplied as single crystal beams and coarse grain disks were measured. Although germanium is anisotropic (A* 1.7), it is not as anisotropic as SiC, NiAl, or Cu. Thus the fracture toughness was similar on the 100, 110, and 111 planes, however, measurements associated with randomly oriented grinding cracks were 6 to 30 higher. Crack extension in ring loaded disks occurred on the 111 planes due to both the lower fracture energy and the higher stresses on stiff 111 planes. Germanium exhibits a Weibull scale effect, but does not exhibit significant slow crack growth in distilled water. (n 100), implying that design for quasi static loading can be performed with scaled strength statistics. Practical values for engineering design are a fracture toughness of 0.69 0.02 MPam (megapascals per square root meter) and a Weibull modulus of m 6 2. For well ground and reasonable handled coupons, average fracture strength should be greater than 40 megapascals. Aggregate, polycrystalline elastic constants are Epoly 131 gigapascals, vpoly 0.22.

  8. Noble Gas Detectors

    CERN Document Server

    Aprile, Elena; Bolozdynya, Alexander I; Doke, Tadayoshi

    2006-01-01

    This book discusses the physical properties of noble fluids, operational principles of detectors based on these media, and the best technical solutions to the design of these detectors. Essential attention is given to detector technology: purification methods and monitoring of purity, information readout methods, electronics, detection of hard ultra-violet light emission, selection of materials, cryogenics etc.The book is mostly addressed to physicists and graduate students involved in the preparation of fundamental next generation experiments, nuclear engineers developing instrumentation

  9. L3 experiment's detector : BGO assembly hall

    CERN Multimedia

    CERN

    1987-01-01

    The detector is a multi-layered cylindrical set of different devices, each of them measuring physical quantities relevant to the reconstruction of the collision under study. The three main outer layers are the electro-magnetic calorimeter (also called BGO because it's made of Bismuth Germanium Oxide), the hadronic calorimeter (HCAL) and the muon detector.

  10. Compound Semiconductor Radiation Detectors

    CERN Document Server

    Owens, Alan

    2012-01-01

    Although elemental semiconductors such as silicon and germanium are standard for energy dispersive spectroscopy in the laboratory, their use for an increasing range of applications is becoming marginalized by their physical limitations, namely the need for ancillary cooling, their modest stopping powers, and radiation intolerance. Compound semiconductors, on the other hand, encompass such a wide range of physical and electronic properties that they have become viable competitors in a number of applications. Compound Semiconductor Radiation Detectors is a consolidated source of information on all aspects of the use of compound semiconductors for radiation detection and measurement. Serious Competitors to Germanium and Silicon Radiation Detectors Wide-gap compound semiconductors offer the ability to operate in a range of hostile thermal and radiation environments while still maintaining sub-keV spectral resolution at X-ray wavelengths. Narrow-gap materials offer the potential of exceeding the spectral resolutio...

  11. Enhanced electromagnetic showers initiated by 20-180 GeV gamma rays on aligned thick germanium crystals

    Energy Technology Data Exchange (ETDEWEB)

    Baurichter, A.; Kirsebom, K.; Medenwaldt, R.; Mikkelsen, U.; Moeller, S.P.; Uggerhoej, E.; Worm, T.; Kononets, Y.V.; Elsener, K.; Ballestrero, S.; Sona, P.; Biino, C.; Connell, S.H.; Sellschop, J.P.F.; Vilakazi, Z.Z.; Apyan, A.; Avakian, R.O.; Ispirian, K.A.; Taroian, S.P

    1999-06-01

    The distribution of the energy released in a silicon detector placed on the downstream side of thick germanium single crystals bombarded by 20-180 GeV gamma rays along directions close to the <1 1 0> axis or along a random direction has been investigated. A large enhancement of the shower for axial incidence of the gamma rays has been found. The response of the system composed of a germanium crystal and a silicon detector to single gamma rays as a function of their energy has been deduced and compared with existing Monte Carlo simulations.

  12. Enhanced electromagnetic showers initiated by 20-180 GeV gamma rays on aligned thick germanium crystals

    Science.gov (United States)

    Baurichter, A.; Kirsebom, K.; Medenwaldt, R.; Mikkelsen, U.; Møller, S. P.; Uggerhøj, E.; Worm, T.; Kononets, Y. V.; Elsener, K.; Ballestrero, S.; Sona, P.; Biino, C.; Connell, S. H.; Sellschop, J. P. F.; Vilakazi, Z. Z.; Apyan, A.; Avakian, R. O.; Ispirian, K. A.; Taroian, S. P.

    1999-06-01

    The distribution of the energy released in a silicon detector placed on the downstream side of thick germanium single crystals bombarded by 20-180 GeV gamma rays along directions close to the axis or along a random direction has been investigated. A large enhancement of the shower for axial incidence of the gamma rays has been found. The response of the system composed of a germanium crystal and a silicon detector to single gamma rays as a function of their energy has been deduced and compared with existing Monte Carlo simulations.

  13. The MAJORANA DEMONSTRATOR: A Search for Neutrinoless Double-beta Decay of Germanium-76

    CERN Document Server

    Schubert, A G; Avignone, F T; Back, H O; Barabash, A S; Bergevin, M; Bertrand, F E; Boswell, M; Brudanin, V; Busch, M; Chan, Y-D; Christofferson, C D; Collar, J I; Combs, D C; Cooper, R J; Detwiler, J A; Leon, J; Doe, P J; Efremenko, Yu; Egorov, V; Ejiri, H; Elliott, S R; Esterline, J; Fast, J E; Fields, N; Finnerty, P; Fraenkle, F M; Gehman, V M; Giovanetti, G K; Green, M P; Guiseppe, V E; Gusey, K; Hallin, A L; Hazama, R; Henning, R; Hime, A; Hoppe, E W; Horton, M; Howard, S; Howe, M A; Johnson, R A; Keeter, K J; Keillor, M E; Keller, C; Kephart, J D; Kidd, M F; Knecht, A; Kochetov, O; Konovalov, S I; Kouzes, R T; LaFerriere, B; LaRoque, B H; Leviner, L E; Loach, J C; MacMullin, S; Marino, M G; Martin, R D; Mei, D -M; Merriman, J; Miller, M L; Mizouni, L; Nomachi, M; Orrell, J L; Overman, N; Phillips, D G; Poon, A W P; Perumpilly, G; Prior, G; Radford, D C; Rielage, K; Robertson, R G H; Ronquest, M C; Shima, T; Shirchenko, M; Snavely, K J; Sobolev, V; Steele, D; Strain, J; Thomas, K; Timkin, V; Tornow, W; Vanyushin, I; Varner, R L; Vetter, K; Vorren, K; Wilkerson, J F; Wolfe, B A; Yakushev, E; Young, A R; Yu, C ?H; Yumatov, V; Zhan, C

    2011-01-01

    The observation of neutrinoless double-beta decay would determine whether the neutrino is a Majorana particle and provide information on the absolute scale of neutrino mass. The MAJORANA Collaboration is constructing the DEMONSTRATOR, an array of germanium detectors, to search for neutrinoless double-beta decay of 76-Ge. The DEMONSTRATOR will contain 40 kg of germanium; up to 30 kg will be enriched to 86% in 76-Ge. The DEMONSTRATOR will be deployed deep underground in an ultra-low-background shielded environment. Operation of the DEMONSTRATOR aims to determine whether a future tonne-scale germanium experiment can achieve a background goal of one count per tonne-year in a 4-keV region of interest around the 76-Ge neutrinoless double-beta decay Q-value of 2039 keV.

  14. The MAJORANA DEMONSTRATOR: A Search for Neutrinoless Double-beta Decay of Germanium-76

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, Alexis G.; Aguayo, Estanislao; Avignone, F. T.; Zhang, C.; Back, Henning O.; Barabash, Alexander S.; Bergevin, M.; Bertrand, F.; Boswell, M.; Brudanin, V.; Busch, Matthew; Chan, Yuen-Dat; Christofferson, Cabot-Ann; Collar, J. I.; Combs, Dustin C.; Cooper, R. J.; Detwiler, Jason A.; Leon, Jonathan D.; Doe, Peter J.; Efremenko, Yuri; Egorov, Viatcheslav; Ejiri, H.; Elliott, S. R.; Esterline, James H.; Fast, James E.; Fields, N.; Finnerty, P.; Fraenkle, Florian; Gehman, Victor M.; Giovanetti, G. K.; Green, M.; Guiseppe, Vincente; Gusey, K.; Hallin, A. L.; Hazama, R.; Henning, Reyco; Hime, Andrew; Hoppe, Eric W.; Horton, Mark; Howard, Stanley; Howe, Mark; Johnson, R. A.; Keeter, K.; Keillor, Martin E.; Keller, C.; Kephart, Jeremy D.; Kidd, M. F.; Knecht, A.; Kochetov, Oleg; Konovalov, S.; Kouzes, Richard T.; LaFerriere, Brian D.; LaRoque, B. H.; Leviner, L.; Loach, J. C.; MacMullin, S.; Marino, Michael G.; Martin, R. D.; Mei, Dong-Ming; Merriman, Jason H.; Miller, M. L.; Mizouni, Leila; Nomachi, Masaharu; Orrell, John L.; Overman, Nicole R.; Phillips, D.; Poon, Alan; Perumpilly, Gopakumar; Prior, Gersende; Radford, D. C.; Rielage, Keith; Robertson, R. G. H.; Ronquest, M. C.; Shima, T.; Shirchenko, M.; Snavely, Kyle J.; Sobolev, V.; Steele, David; Strain, J.; Thomas, K.; Timkin, V.; Tornow, Werner; Vanyushin, I.; Varner, R. L.; Vetter, Kai; Vorren, Kris R.; Wilkerson, J. F.; Wolfe, B. A.; Yakushev, E.; Young, A.; Yu, Chang-Hong; Yumatov, Vladimir

    2012-09-28

    The observation of neutrinoless double-beta decay would determine whether the neutrino is a Majorana particle and provide information on the absolute scale of neutrino mass. The MAJORANA Collaboration is constructing the DEMONSTRATOR, an array of germanium detectors, to search for neutrinoless double-beta decay of 76Ge. The DEMONSTRATOR will contain 40 kg of germanium; up to 30 kg will be enriched to 86% in 76Ge. The DEMONSTRATOR will be deployed deep underground in an ultra-low-background shielded environment. Operation of the DEMONSTRATOR aims to determine whether a future tonne-scale germanium experiment can achieve a background goal of one count per tonne-year in a 4-keV region of interest around the 76Ge neutrinoless double-beta decay Q-value of 2039 keV.

  15. Laser synthesis of germanium tin alloys on virtual germanium

    Science.gov (United States)

    Stefanov, S.; Conde, J. C.; Benedetti, A.; Serra, C.; Werner, J.; Oehme, M.; Schulze, J.; Buca, D.; Holländer, B.; Mantl, S.; Chiussi, S.

    2012-03-01

    Synthesis of heteroepitaxial germanium tin (GeSn) alloys using excimer laser processing of a thin 4 nm Sn layer on Ge has been demonstrated and studied. Laser induced rapid heating, subsequent melting, and re-solidification processes at extremely high cooling rates have been experimentally achieved and also simulated numerically to optimize the processing parameters. "In situ" measured sample reflectivity with nanosecond time resolution was used as feedback for the simulations and directly correlated to alloy composition. Detailed characterization of the GeSn alloys after the optimization of the processing conditions indicated substitutional Sn concentration of up to 1% in the Ge matrix.

  16. L3 detector: BGO assembly

    CERN Multimedia

    CERN

    1989-01-01

    Explanation and presentation of its construction ( Feb-March 1989). The detector is a multi-layered cylindrical set of different devices, each of them measuring physical quantities relevant to the reconstruction of the collision under study. The three main outer layers are the electro-magnetic calorimeter (also called BGO because it's made of Bismuth Germanium Oxide), the hadronic calorimeter (HCAL) and the muon detector.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-11

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

  18. Testing and Characterization of SuperCDMS Dark Matter Detectors

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-05-01

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

  19. Gamma-Ray Background Variability in Mobile Detectors

    Science.gov (United States)

    Aucott, Timothy John

    . This is accomplished by making many hours of background measurements with a truck-mounted system, which utilizes high-purity germanium detectors for spectroscopy and sodium iodide detectors for coded aperture imaging. This system also utilizes various peripheral sensors, such as panoramic cameras, laser ranging systems, global positioning systems, and a weather station to provide context for the gamma-ray data. About three hundred hours of data were taken in the San Francisco Bay Area, covering a wide variety of environments that might be encountered in operational scenarios. These measurements were used in a source injection study to evaluate the sensitivity of different algorithms (imaging and spectroscopy) and hardware (sodium iodide and high-purity germanium detectors). These measurements confirm that background distributions in large, mobile detector systems are dominated by systematic, not statistical variations, and both spectroscopy and imaging were found to substantially reduce this variability. Spectroscopy performed better than the coded aperture for the given scintillator array (one square meter of sodium iodide) for a variety of sources and geometries. By modeling the statistical and systematic uncertainties of the background, the data can be sampled to simulate the performance of a detector array of arbitrary size and resolution. With a larger array or lower resolution detectors, however imaging was better able to compensate for background variability.

  20. Analog Readout and Analysis Software for the Ultra-High Rate Germanium (UHRGe) Project

    Energy Technology Data Exchange (ETDEWEB)

    Fast, James E.; Aguayo Navarrete, Estanislao; Evans, Allan T.; VanDevender, Brent A.; Rodriguez, Douglas C.; Wood, Lynn S.

    2011-09-01

    High-resolution high-purity germanium (HPGe) spectrometers are needed for Safeguards applications such as spent fuel assay and uranium hexafluoride cylinder verification. In addition, these spectrometers would be applicable to other high-rate applications such as non-destructive assay of nuclear materials using nuclear resonance fluorescence. Count-rate limitations of today's HPGe technologies, however, lead to concessions in their use and reduction in their efficacy. Large-volume, very high-rate HPGe spectrometers are needed to enable a new generation of nondestructive assay systems. The Ultra-High Rate Germanium (UHRGe) project is developing HPGe spectrometer systems capable of operating at unprecedented rates, 10 to 100 times those available today. This report documents current status of developments in the analog electronics and analysis software.

  1. Purity homophily in social networks.

    Science.gov (United States)

    Dehghani, Morteza; Johnson, Kate; Hoover, Joe; Sagi, Eyal; Garten, Justin; Parmar, Niki Jitendra; Vaisey, Stephen; Iliev, Rumen; Graham, Jesse

    2016-03-01

    Does sharing moral values encourage people to connect and form communities? The importance of moral homophily (love of same) has been recognized by social scientists, but the types of moral similarities that drive this phenomenon are still unknown. Using both large-scale, observational social-media analyses and behavioral lab experiments, the authors investigated which types of moral similarities influence tie formations. Analysis of a corpus of over 700,000 tweets revealed that the distance between 2 people in a social-network can be predicted based on differences in the moral purity content-but not other moral content-of their messages. The authors replicated this finding by experimentally manipulating perceived moral difference (Study 2) and similarity (Study 3) in the lab and demonstrating that purity differences play a significant role in social distancing. These results indicate that social network processes reflect moral selection, and both online and offline differences in moral purity concerns are particularly predictive of social distance. This research is an attempt to study morality indirectly using an observational big-data study complemented with 2 confirmatory behavioral experiments carried out using traditional social-psychology methodology.

  2. Germanium multiphase equation of state

    Science.gov (United States)

    Crockett, S. D.; De Lorenzi-Venneri, G.; Kress, J. D.; Rudin, S. P.

    2014-05-01

    A new SESAME multiphase germanium equation of state (EOS) has been developed utilizing the best available experimental data and density functional theory (DFT) calculations. The equilibrium EOS includes the Ge I (diamond), the Ge II (β-Sn) and the liquid phases. The foundation of the EOS is based on density functional theory calculations which are used to determine the cold curve and the Debye temperature. Results are compared to Hugoniot data through the solid-solid and solid-liquid transitions. We propose some experiments to better understand the dynamics of this element.

  3. The MAJORANA DEMONSTRATOR: An R&D project towards a tonne-scale germanium neutrinoless double-beta decay search

    Energy Technology Data Exchange (ETDEWEB)

    Aalseth, Craig E; Amman, M; Amsbaugh, John F; Avignone, F. T.; Back, Henning O; Barabash, A; Barbeau, Phil; Beene, Jim; Bergevin, M; Bertrand, F; Boswell, M; Brudanin, V; Bugg, William; Burritt, Tom H; Chan, Yuen-Dat; Collar, J I; Cooper, R J; Creswick, R; Detwiler, Jason A; Doe, P J; Efremenko, Yuri; Egorov, Viatcheslav; Ejiri, H; Elliott, Steven R; Ely, James H; Esterline, James H; Farach, H A; Fast, James E; Fields, N; Finnerty, P; Fujikawa, Brian; Fuller, Erin S; Gehman, Victor; Giovanetti, G K; Guiseppe, Vincente; Gusey, K; Hallin, A L; Hazama, R; Henning, Reyco; Hime, Andrew; Hoppe, Eric W; Hossbach, Todd W; Howe, M A; Johnson, R A; Keeter, K; Keillor, Martin E; Keller, C; Kephart, Jeremy D; Kidd, Mary; Kochetov, Oleg; Konovalov, S; Kouzes, Richard T; Lesko, Kevin; Leviner, L; Loach, J C; Luke, P; MacMullin, S; Marino, Michael G; Mei, Dong-Ming; Miley, Harry S; Miller, M; Mizouni, Leila K; Montoya, A; Myers, A W; Nomachi, Masaharu; Odom, Brian; Orrell, John L; Phillips, D; Poon, Alan; Prior, Gersende; Qian, J; Radford, D C; Rielage, Keith; Robertson, R G. H.; Rodriguez, Larry; Rykaczewski, Krzysztof P; Schubert, Alexis G; Shima, T; Shirchenko, M; Strain, J; Thomas, K; Thompson, Robert C; Timkin, V; Tornow, W; Van Wechel, T D; Vanyushin, I; Vetter, Kai; Warner, Ray A; Wilkerson, J; Wouters, Jan; Yakushev, E; Young, A; Yu, Chang-Hong; Yumatov, Vladimir; Zhang, C L; Zimmerman, S

    2009-12-17

    The MAJORANA collaboration is pursuing the development of the so-called MAJORANA DEMONSTRATOR. The DEMONSTRATOR is intended to perform research and development towards a tonne-scale germanium-based experiment to search for the neutrinoless double-beta decay of 76Ge. The DEMONSTRATOR can also perform a competitive direct dark matter search for light WIMPs in the 1-10GeV/c2 mass range. It will consist of approximately 60 kg. of germanium detectors in an ultra-low background shield located deep underground at the Sanford Underground Laboratory in Lead, SD. The DEMONSTRATOR will also perform background and technology studies, and half of the detector mass will be enriched germanium. This talk will review the motivation, design, technology and status of the Demonstrator.

  4. Neutron damage tests of a highly segmented germanium crystal

    Energy Technology Data Exchange (ETDEWEB)

    Ross, T.J. [Physics Department, University of Richmond, Richmond, VA 23173 (United States); Physics Department, University of Surrey, Guildford GU2 7JL (United Kingdom); Beausang, C.W. [Physics Department, University of Richmond, Richmond, VA 23173 (United States)], E-mail: cbeausan@richmond.edu; Lee, I.Y.; Macchiavelli, A.O.; Gros, S.; Cromaz, M.; Clark, R.M.; Fallon, P.; Jeppesen, H. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Allmond, J.M. [Physics Department, University of Richmond, Richmond, VA 23173 (United States)

    2009-07-21

    To evaluate the effect of neutron damage on the performance of highly segmented germanium detectors the P3 prototype detector for the GRETINA array was subjected to a neutron flux of {approx}3x10{sup 9} n/cm{sup 2} over a period of 5 days. During the irradiation, the resolution (full-width half-maximum (FWHM)) of the 1332 keV {sup 60}Co photopeak increased from {approx}1.8 to {approx}6.0 keV while the full-width at tenth maximum (FWTM) increased from {approx}4 keV to more than 12 keV. Following the irradiation the detector was successfully annealed and the energy resolution returned to pre-irradiation values. All detector segments were fully functional before and after the annealing and following multiple room-temperature cycles. A comparison of digitized pulse shapes in the damaged and annealed detector indicates that the effect of extreme neutron damage (FWHM=6 keV) on the position resolution is on the order of {approx}1.7 mm while for 3 keV resolution the position resolution degrades by {approx}0.5 mm.

  5. Ionization Collection in Detectors of the Cryogenic Dark Matter Search

    Energy Technology Data Exchange (ETDEWEB)

    Phipps, Arran T.J. [Univ. of California, Berkeley, CA (United States)

    2016-01-01

    Determining the composition of dark matter is at the forefront of modern scientific research. There is compelling evidence for the existence of vast quantities of dark matter throughout the universe, however it has so-far eluded all direct detection efforts and its identity remains a mystery. Weakly interacting massive particles (WIMPs) are a favored dark matter candidate and have been the primary focus of direct detection for several decades. The Cryogenic Dark Matter Search (CDMS) has developed the Z-dependent Ionization and Phonon (ZIP) detector to search for such particles. Typically made from germanium, these detectors are capable of distinguishing between electromagnetic background and a putative WIMP signal through the simultaneous measurement of ionization and phonons produced by scattering events. CDMS has operated several arrays of these detectors at the Soudan Underground Laboratory (Soudan, MN, USA) resulting in many competitive (often world-leading) WIMP exclusion limits. This dissertation focuses on ionization collection in these detectors under the sub-Kelvin, low electric field, and high crystal purity conditions unique to CDMS. The design and performance of a fully cryogenic HEMT-based amplifier capable of achieving the SuperCDMS SNOLAB ionization energy resolution goal of 100 eVee is presented. The experimental apparatus which has been used to record electron and hole properties under CDMS conditions is described. Measurements of charge transport, trapping, and impact ionization as a function of electric field in two CDMS detectors are shown, and the ionization collection efficiency is determined. The data is used to predict the error in the nuclear recoil energy scale under both CDMSlite and iZIP operating modes. A two species, two state model is developed to describe how ionization collection and space charge generation in CDMS detectors are controlled by the presence of “overcharged” D- donor and A+ acceptor impurity states. The thermal

  6. Purity assessment of crystalline zearalenone.

    Science.gov (United States)

    Krska, Rudolf; Welzig, Elvira; Josephs, Ralf D; Kandler, Wolfgang; Pettersson, Hans; MacDonald, Susan; Charlton, Adrian; Brereton, Paul; Hametner, Christian; Berner, Diana; Zöllner, Peter

    2003-01-01

    Commercially available solid zearalenone (ZON) to be used as a certified liquid calibrant (BCR-699) in a project funded by the European Commission within the Standard Measurement and Testing program was characterized and its purity determined. The degree of purity of the ZON was examined by UV spectrophotometer, liquid chromatography (LC) with diode array and fluorescence detection, 1H and 13C-NMR spectrometry, LC-mass spectrometry (LC/MS/MS), ion chromatography (IC), and differential scanning calorimetry (DSC). The diagrams obtained from DSC analysis and the UV spectrum showed no detectable impurities. Likewise, no impurities were observed by LC analysis with both diode array and fluorescence detection. IC determination revealed negligible contamination of ZON with chloride of 0.020 +/- 0.005% and nitrate of 0.016 +/- 0.006%. Zearalanone (ZAN) was identified as one of 2 minor (0.2%) impurities by LC/MS/MS. The 1H-NMR measurements revealed an additional peak, which has not been previously reported in the literature. It could be identified as part of the ZON spectrum as the signal arising from the phenolic proton attached to C4'. The manufacturer states an additional contamination with 0.2% methylene chloride, which could be confirmed to an extent of 0.1% by 1H-NMR. Minor impurities, whose structures remain unknown, were discovered at 3.5 and project.

  7. Iodine Absorption Cells Purity Testing

    Directory of Open Access Journals (Sweden)

    Jan Hrabina

    2017-01-01

    Full Text Available This article deals with the evaluation of the chemical purity of iodine-filled absorption cells and the optical frequency references used for the frequency locking of laser standards. We summarize the recent trends and progress in absorption cell technology and we focus on methods for iodine cell purity testing. We compare two independent experimental systems based on the laser-induced fluorescence method, showing an improvement of measurement uncertainty by introducing a compensation system reducing unwanted influences. We show the advantages of this technique, which is relatively simple and does not require extensive hardware equipment. As an alternative to the traditionally used methods we propose an approach of hyperfine transitions’ spectral linewidth measurement. The key characteristic of this method is demonstrated on a set of testing iodine cells. The relationship between laser-induced fluorescence and transition linewidth methods will be presented as well as a summary of the advantages and disadvantages of the proposed technique (in comparison with traditional measurement approaches.

  8. Spectral Study of a Broad Energy HPGe Detector for First Measurement of Coherent Neutrino Scattering

    Science.gov (United States)

    Surbrook, Jason; Green, Matthew

    2014-09-01

    Intense neutrino flux at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) in the energy domain below Eν = 50 MeV makes SNS a suitable location for measurement of Coherent Neutrino Scattering. Coherent scattering is assumed to occupy vital roles in supernovae (SN) events and measurement offers promising insight into SN mechanics and advancements in SN- ν detection. Furthermore, this interaction is well-calculable and therefore, a strong test of the Standard Model. P-Type Point Contact High-purity germanium detectors are excellent candidates for this measurement due to their sensitivity to low-energy nuclear recoils. One such, a Canberra Broad Energy HPGe detector, was tested for quality degradation from exposure to fast neutrons in the SNS target building, to assess usefulness in a future coherent scattering experiment. Analysis of the lead-shielded spectra was handled using tools developed for the Majorana Demonstrator neutrinoless double-beta decay experiment. Broad spectrum energy resolution and 68Ge decay rates were calculated. This poster will present findings that will help determine this detector's eligibility and exposure limitations for measurement in a future coherent neutrino scattering experiment at the SNS.

  9. Direct Detection of Pu-242 with a Metallic Magnetic Calorimeter Gamma-Ray Detector

    Science.gov (United States)

    Bates, C.; Pies, C.; Kempf, S.; Hengstler, D.; Fleischmann, A.; Gastaldo, L.; Enss, C.; Friedrich, S.

    2016-07-01

    Cryogenic high-resolution γ -ray detectors can improve the accuracy of non-destructive assay (NDA) of nuclear materials in cases where conventional high-purity germanium detectors are limited by line overlap or by the Compton background. We have improved the performance of gamma detectors based on metallic magnetic calorimeters (MMCs) by separating the 0.5 × 2 × 0.25 mm3 Au absorber from the Au:Er sensor with sixteen 30-\\upmu m-diameter Au posts. This ensures that the entire γ -ray energy thermalizes in the absorber before heating the Au:Er sensor, and improves the energy resolution at 35 mK to as low as 90 eV FWHM at 60 keV. This energy resolution enables the direct detection of γ -rays from Pu-242, an isotope that cannot be measured by traditional NDA and whose concentration is therefore inferred through correlations with other Pu isotopes. The Pu-242 concentration of 11.11 ± 0.42 % measured by NDA with MMCs agrees with mass spectrometry results and exceeds the accuracy of correlation measurements.

  10. Silicon Germanium Quantum Well Solar Cell Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Quantum-well structures embodied on single crystal silicon germanium drastically enhanced carrier mobilities.  The cell-to-cell circuits of quantum-well PV...

  11. Simulation of the charge collection and signal response of a HPGe double sided strip detector using MGS

    Energy Technology Data Exchange (ETDEWEB)

    Mateu, I., E-mail: isidre.mateu@irap.omp.eu [Université de Toulouse, UPS-OMP, IRAP, Toulouse (France); CNRS, IRAP, 9 Av. colonel Roche, BP 44346, F-31028 Toulouse cedex 4 (France); Medina, P., E-mail: patrice.medina@aero.obs-mip.fr [IPHC, IN2P3 – CNRS/Université Louis Pasteur, 23 rue du Loess, PB28, Strasbourg Cedex 2, F67037 (France); Roques, J.P., E-mail: jean-pierre.roques@irap.omp.eu [Université de Toulouse, UPS-OMP, IRAP, Toulouse (France); CNRS, IRAP, 9 Av. colonel Roche, BP 44346, F-31028 Toulouse cedex 4 (France); Jourdain, E., E-mail: elisabeth.jourdain@irap.omp.eu [Université de Toulouse, UPS-OMP, IRAP, Toulouse (France); CNRS, IRAP, 9 Av. colonel Roche, BP 44346, F-31028 Toulouse cedex 4 (France)

    2014-01-21

    This paper aims to present Multi geometry Simulation (MGS), a software intended for the characterization of the signal response of solid state detectors. Its main feature is the calculation of the pulse shapes induced at the electrodes of the detector by a photon–semiconductor interaction occurring at a specific position inside the detector volume. The program uses numerical methods to simulate the drift of the charge carriers generated by the interaction, as the movement of these particles induces the useful signal for detection to the electrodes. After the description of the tool fundamentals, an example of application is presented where MGS was used for simulating a High Purity Germanium (HPGe) double sided strip detector conceived for hard X-ray astronomy. Simulated and measured pulse shapes are compared for interactions occurring at different depths in the detector volume. The comparison focuses on the difference in time of arrival between the anode and cathode pulses, as this measure allows, together with the X/Y information retrieved from the strips, a 3D determination of the photon interaction point, which is an important feature of the detector. A good matching between simulations and measurements is obtained, with a discrepancy less than 0.5 mm between the measured and the simulated depth of the interaction, for an 11 mm thick detector. -- Highlights: • Description of MGS, a tool for the synthesis of the signal response of solid state detectors. • Validation of the simulator through comparison with measurements on a DSSD prototype. • Discussion on the advantages, drawbacks and possible evolutions of MGS.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-05-11

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

  13. Search for double beta processes in {sup 106}Cd with enriched {sup 106}CdWO{sub 4} crystal scintillator in coincidence with four crystals HPGe detector

    Energy Technology Data Exchange (ETDEWEB)

    Danevich, F. A., E-mail: danevich@kinr.kiev.ua; Chernyak, D. M.; Mokina, V. M. [Institute for Nuclear Research, MSP 03680 Kyiv (Ukraine); Belli, P.; Bernabei, R.; D’Angelo, S. [Dipartimento di Fisica, Università di Roma ”Tor Vergata”, I-00133 Rome (Italy); INFN sezione Roma ”Tor Vergata”, I-00133 Rome (Italy); Brudanin, V. B. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Cappella, F.; Caracciolo, V.; Cerulli, R.; Laubenstein, M. [INFN, Laboratori Nazionali del Gran Sasso, I-67100 Assergi (AQ) (Italy); Incicchitti, A. [INFN, sezione di Roma ”La Sapienza”, I-00185 Rome (Italy); Dipartimento di Fisica, Università di Roma ”La Sapienza”, I-00185 Rome (Italy); Poda, D. V. [Institute for Nuclear Research, MSP 03680 Kyiv (Ukraine); Centre de Sciences Nucléaires et de Sciences de la Matière, 91405 Orsay (France); Polischuk, O. G.; Tretyak, V. I. [Institute for Nuclear Research, MSP 03680 Kyiv (Ukraine); INFN, sezione di Roma ”La Sapienza”, I-00185 Rome (Italy); Tupitsyna, I. A. [Institute of Scintillation Materials, 61001 Kharkiv (Ukraine)

    2015-10-28

    A radiopure cadmium tungstate crystal scintillator, enriched in {sup 106}Cd ({sup 106}CdWO{sub 4}), was used to search for double beta decay processes in {sup 106}Cd in coincidence with an ultra-low background set-up containing four high purity germanium (HPGe) detectors in a single cryostat. The experiment has been completed after 13085 h of data taking. New improved limits on most of the double beta processes in {sup 106}Cd have been set on the level of 10{sup 20}−10{sup 21} yr. Tn particular, the half-life limit on the two neutrino electron capture with positron emission, T{sub 1/2} ≥ 1.8 × 10{sup 21} yr, reached the region of theoretical predictions.

  14. Enhancement of electromagnetic showers initiated by ultrarelativistic electrons in aligned thick germanium crystals

    Science.gov (United States)

    Baurichter, A.; Mikkelsen, U.; Kirsebom, K.; Medenwaldt, R.; Møller, S.; Uggerhøj, E.; Worm, T.; Elsener, K.; Ballestrero, S.; Sona, P.; Romano, J.; Biino, C.; Moore, R.; Vilakazi, Z. Z.

    1996-10-01

    The distribution of the energy deposited in thin silicon detectors placed on the downstream side of a thick germanium single crystal bombarded with a 70, 150 and 250 GeV electron beam along directions close to the axis or {110} and {100} planes has been measured. The enhancement of the shower with respect to random incidence, as reflected in the higher value of the centroid of the distribution, is studied as a function of the incidence angle to the axis or plane.

  15. Metal induced crystallization of silicon germanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gjukic, M.

    2007-05-15

    In the framework of this thesis the applicability of the aluminium-induced layer exchange on binary silicon germanium alloys was studied. It is here for the first time shown that polycrstalline silicon-germanium layers can be fabricated over the whole composition range by the aluminium-induced layer exchange. The experimental results prove thet the resulting material exhibits a polycrystalline character with typocal grain sizes of 10-100 {mu}m. Raman measurements confirm that the structural properties of the resulting layers are because of the large crystallites more comparable with monocrystalline than with nano- or microcrystalline silicon-germanium. The alloy ratio of the polycrystalline layer correspondes to the chemical composition of the amorphous starting layer. The polycrystalline silicon-germanium layers possess in the range of the interband transitions a reflection spectrum, as it is otherwise only known from monocrystalline reference layers. The improvement of the absorption in the photovoltaically relevant spectral range aimed by the application of silicon-germanium could be also proved by absorption measurments. Strongly correlated with the structural properties of the polycrystalline layers and the electronic band structure resulting from this are beside the optical properties also the electrical properties of the material, especially the charge-carrier mobility and the doping concentration. For binary silicon-germanium layers the hole concentration of about 2 x 10{sup 18} cm{sup -3} for pure silicon increrases to about 5 x 10{sup 20} cm{sub -3} for pure germanium. Temperature-resolved measurements were applied in order to detect doping levels respectively semiconductor-metal transitions. In the last part of the thesis the hydrogen passivation of polycrystalline thin silicon-germanium layers, which were fabricated by means of aluminium-induced layer exchange, is treated.

  16. Improved constraints on WIMPs from the International Germanium Experiment IGEX

    CERN Document Server

    Morales, A; Brodzinski, R L; Cebrián, S; García, E; Irastorza, I G; Kirpichnikov, I V; Klimenko, A A; Miley, H S; Morales, J; De Solorzano, A O; Osetrov, S B; Pogosov, V S; Puimedón, J; Reeves, J H; Sarsa, M L; Smolnikov, A A; Tamanyan, A G; Vasenko, A A; Vasilev, S I; Villar, J A

    2002-01-01

    One IGEX 76Ge double-beta decay detector is currently operating in the Canfranc Underground Laboratory in a search for dark matter WIMPs, through the Ge nuclear recoil produced by the WIMP elastic scattering. A new exclusion plot, has been derived for WIMP-nucleon spin-independent interactions. To obtain this result, 40 days of data from the IGEX detector (energy threshold E \\~ 4 keV), recently collected, have been analyzed. These data improve the exclusion limits derived from all the other ionization germanium detectors in the mass region from 20 GeV to 200 GeV, where a WIMP supposedly responsible for the annual modulation effect reported by the DAMA experiment would be located. The new IGEX exclusion contour enters, by the first time, the DAMA region by using only raw data, with no background discrimination, and excludes its upper left part. It is also shown that with a moderate improvement of the detector performances, the DAMA region could be fully explored.

  17. Technology for sodium purity control

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Ji Young; Kim, B. H.; Kim, T. J. [Korea Atomic Energy Research Institute, Taejon (Korea)

    1999-10-01

    When sodium is used as heat transfer fluid, the plugging in coolant flow, the corrosion of structure material and the transfer of radioactive material caused by the impurities in sodium are worth considerable. Accordingly, these impurities must be monitored and controlled continuously by sodium purification devices in the heat transfer system which sodium is used as coolant. Sodium purification loop was constructed for the purpose of accumulating the technology for purity control of the coolant, developing and verifying further efficient instruments for sodium purification. The plugging meter and the cold trap is used as the implement for measuring and controlling the oxygen and the hydrogen, the main impurities in sodium coolant. They are capable of excellent performance as the implements which could detect and monitor the impurities to the concentration limit required for nuclear reactor. Sodium purification loop could be used variably according to the experimental purpose. 18 refs., 34 figs., 8 tabs. (Author)

  18. Xenon purity analysis for EXO-200 via mass spectrometry

    CERN Document Server

    Dobi, A; Slutsky, S; Yen, Y -R; Aharmin, B; Auger, M; Barbeau, P S; Benitez-Medina, C; Breidenbach, M; Cleveland, B; Conley, R; Cook, J; Cook, S; Counts, I; Craddock, W; Daniels, T; Davis, C G; Davis, J; deVoe, R; Dixit, M; Dolinski, M J; Donato, K; Fairbank, W; Farine, J; Fierlinger, P; Franco, D; Giroux, G; Gornea, R; Graham, K; Gratta, G; Green, C; Hagemann, C; Hall, K; Hallman, D; Hargrove, C; Herrin, S; Hughes, M; Hodgson, J; Juget, F; Karelin, A; Kaufman, L J; Kuchenkov, A; Kumar, K; Leonard, D S; Lutter, G; Mackay, D; MacLellan, R; Marino, M; Mong, B; Díez, M Montero; Morgan, P; Müller, A R; Neilson, R; Odian, A; O'Sullivan, K; Piepke, A; Pocar, A; Prescott, C Y; Pushkin, K; Rivas, A; Rollin, E; Rowson, P C; Sabourov, A; Sinclair, D; Skarpaas, K; Stekhanov, V; Strickland, V; Swift, M; Twelker, K; Vuilleumier, J -L; Vuilleumier, J -M; Weber, M; Wichoski, U; Wodin, J; Wright, J D; Yang, L

    2011-01-01

    We describe purity measurements of the natural and enriched xenon stockpiles used by the EXO-200 double beta decay experiment based on a mass spectrometry technique. The sensitivity of the spectrometer is enhanced by several orders of magnitude by the presence of a liquid nitrogen cold trap, and many impurity species of interest can be detected at the level of one part-per-billion or better. We have used the technique to screen the EXO-200 xenon before, during, and after its use in our detector, and these measurements have proven useful. This is the first application of the cold trap mass spectrometry technique to an operating physics experiment.

  19. Germanium content in Polish hard coals

    Directory of Open Access Journals (Sweden)

    Makowska Dorota

    2016-01-01

    Full Text Available Due to the policy of the European Union, it is necessary to search for new sources of scarce raw materials. One of these materials is germanium, listed as a critical element. This semi-metal is widely used in the electronics industry, for example in the production of semiconductors, fibre optics and solar cells. Coal and fly ash from its combustion and gasification for a long time have been considered as a potential source of many critical elements, particularly germanium. The paper presents the results of germanium content determination in the Polish hard coal. 23 coal samples of various coal ranks were analysed. The samples were collected from 15 mines of the Upper Silesian Coal Basin and from one mine of the Lublin Coal Basin. The determination of germanium content was performed with the use of Atomic Absorption Spectrometry with Electrothermal Atomization (GFAAS. The investigation showed that germanium content in the analysed samples was at least twice lower than the average content of this element in the hard coals analysed so far and was in the range of 0.08 ÷ 1.28 mg/kg. Moreover, the content of Ge in the ashes from the studied coals does not exceed 15 mg/kg, which is lower than the average value of Ge content in the coal ashes. The highest content of this element characterizes coals of the Lublin Coal Basin and young coals type 31 from the Vistula region. The results indicate a low utility of the analysed coal ashes as a source of the recovery of germanium. On the basis of the analyses, the lack of the relationship between the content of the element and the ash content in the tested coals was noted. For coals of the Upper Silesian Coal Basin, the relationship between the content of germanium in the ashes and the depth of the seam was observed.

  20. Experimental Search for Solar Axions via Coherent Primakoff Conversion in a Germanium Spectrometer

    CERN Document Server

    Avignone, F T; Brodzinski, R; Collar, J I; Creswick, R J; Di Gregorio, D E; Farach, H A; Gattone, A O; Guérard, C K; Hasenbalg, F; Huck, H; Miley, H S; Morales, A; Morales, J; Nussinov, S; De Solorzano, A O; Reeves, J H; Villar, J; Zioutas, Konstantin

    1998-01-01

    Results are reported of an experimental search for the unique, rapidly varying temporal pattern of solar axions coherently converting into photons via the Primakoff effect in a single crystal germanium detector. This conversion is predicted when axions are incident at a Bragg angle with a crystalline plane. The analysis of approximately 1.94 kg.yr of data from the 1 kg DEMOS detector in Sierra Grande, Argentina, yields a new laboratory bound on axion-photon coupling of $g_{a\\gamma \\gamma} < 2.7\\cdot 10^{-9}$ GeV$^{-1}$, independent of axion mass up to ~ 1 keV.

  1. Monte Carlo simulation of the LENA detector system

    Energy Technology Data Exchange (ETDEWEB)

    Howard, C., E-mail: choward@unc.edu [Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599-3255 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Iliadis, C.; Champagne, A.E. [Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599-3255 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)

    2013-11-21

    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 {sup 18}O(p, γ){sup 19}F reaction, a {sup 22}Na point-like calibration source, and {sup 26}Al 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. -- Highlights: •We create a simulation of our HPGe detector and NaI annulus. •We compare our model to various calibration sources. •We compare energy gating using the simulation. •The simulation predict efficiencies as observed in the data.

  2. Development of silicon-germanium visible-near infrared arrays

    Science.gov (United States)

    Zeller, John W.; Rouse, Caitlin; Efstathiadis, Harry; Haldar, Pradeep; Lewis, Jay S.; Dhar, Nibir K.; Wijewarnasuriya, Priyalal; Puri, Yash R.; Sood, Ashok K.

    2016-05-01

    Photodetectors based on germanium which do not require cooling and can provide good near-infrared (NIR) detection performance offer a low-cost alternative to conventional infrared sensors based on material systems such as InGaAs, InSb, and HgCdTe. As a result of the significant difference in thermal expansion coefficients between germanium and silicon, tensile strain incorporated into Ge epitaxial layers deposited on Si utilizing specialized growth processes can extend the operational range of detection to 1600 nm and longer wavelengths. We have fabricated Ge based PIN photodetectors on 300 mm diameter Si wafers to take advantage of high throughput, large-area complementary metal-oxide semiconductor (CMOS) technology. This device fabrication process involves low temperature epitaxial deposition of Ge to form a thin p+ (boron) Ge seed/buffer layer, and subsequent higher temperature deposition of a thicker Ge intrinsic layer. This is followed by selective ion implantation of phosphorus of various concentrations to form n+ Ge regions, deposition of a passivating oxide cap, and then top copper contacts to complete the PIN detector devices. Various techniques including transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS) have been employed to characterize the material and structural properties of the epitaxially grown layers and fabricated detector devices, and these results are presented. The I-V response of the photodetector devices with and without illumination was also measured, for which the Ge based photodetectors consistently exhibited low dark currents of around ~1 nA at -1 V bias.

  3. Optimized digital filtering techniques for radiation detection with HPGe detectors

    CERN Document Server

    Salathe, M

    2015-01-01

    This paper describes state-of-the-art digital filtering techniques that are part of the tool kit GEANA which is used as a fast automatic data validation tool for the GERDA experiment. The discussed filters include a novel, nonlinear correction method for ballistic deficits, which is combined with one of three shaping filters: the pseudo-Gaussian, a modified trapezoidal, or a modified cusp filter. The performance of the filters is demonstrated using a 762 g high purity germanium detector that measures gamma-ray lines from radioactive sources in an energy range between 59 and 2615 keV. The modified cusp filter was found to be most optimal for individual gamma-ray lines. Furthermore, it was observed, that even though, the shaping time that minimizes the energy resolution is energy dependent, the loss in resolution by using a constant shaping time over the entire energy range is small, i.e. less than 32 eV for the pseudo-Gaussian filter. This together with good energy resolutions, e.g. 1.59 keV at 1333 keV, this ...

  4. Recovering germanium from coal ash by chlorination with ammonium chloride

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A new process of enriching germanium from coal ash was developed. The process involves in mixing the coal ash and ammonium chloride and then roasting the mixture to produce germanium chloride that is then absorbed by dilute hydrochloric acid and hydrolyzed to germanium oxide. The germanium recovery reached to 80.2% at the optimum condition: mass ratio of NH4Cl/coal ash is 0.15, roasting temperature 400℃ and roasting time 90 min.

  5. Germanium nanowires grown using different catalyst metals

    Energy Technology Data Exchange (ETDEWEB)

    Gouveia, R.C., E-mail: riama@ifsp.edu.br [Departamento de Física – NanO Lab, Universidade Federal de São Carlos, Rod. Washington Luís, Km 235 – SP 310, São Carlos, CEP 13565-905 (Brazil); Área de Ciências, Instituto Federal de Educação Ciência e Tecnologia de São Paulo, Rua Américo Ambrósio, 269, Jd. Canaã, Sertãozinho, CEP 14169-263 (Brazil); Kamimura, H.; Munhoz, R.; Rodrigues, A.D. [Departamento de Física – NanO Lab, Universidade Federal de São Carlos, Rod. Washington Luís, Km 235 – SP 310, São Carlos, CEP 13565-905 (Brazil); Leite, E.R. [Departamento de Química – LIEC, Universidade Federal de São Carlos, São Carlos, CEP 13565-905 (Brazil); Chiquito, A.J. [Departamento de Física – NanO Lab, Universidade Federal de São Carlos, Rod. Washington Luís, Km 235 – SP 310, São Carlos, CEP 13565-905 (Brazil)

    2016-11-01

    Germanium nanowires have been synthesized by the well known vapor-liquid-solid growth mechanism using gold, silver, cooper, indium and nickel as catalyst metals. The influence of metal seeds on nanowires structural and electronic transport properties was also investigated. Electron microscopy images demonstrated that, despite differences in diameters, all nanowires obtained presented single crystalline structures. X-ray patterns showed that all nanowires were composed by germanium with a small amount of germanium oxide, and the catalyst metal was restricted at the nanowires' tips. Raman spectroscopy evidenced the long range order in the crystalline structure of each sample. Electrical measurements indicated that variable range hopping was the dominant mechanism in carrier transport for all devices, with similar hopping distance, regardless the material used as catalyst. Then, in spite of the differences in synthesis temperatures and nanowires diameters, the catalyst metals have not affected the composition and crystalline quality of the germanium nanowires nor the carrier transport in the germanium nanowire network devices. - Highlights: • Ge nanowires were grown by VLS method using Au, Ag, Cu, In and Ni as catalysts. • All nanowires presented high single crystalline quality and long range order. • Devices showed semiconducting behavior having VRH as dominant transport mechanism. • The metal catalyst did not influence structural properties or the transport mechanism.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-11

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

  7. Boron doping compensation of hydrogenated amorphous and polymorphous germanium thin films for infrared detection applications

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, M., E-mail: mmoreno@inaoep.mx [National Institute of Astrophysics, Optics and Electronics, INAOE, P.O. Box 51 and 216, Puebla, Z. P. 72840 Puebla (Mexico); Delgadillo, N. [Universidad Autónoma de Tlaxcala, Av. Universidad No. 1, Z. P. 90006 Tlaxcala (Mexico); Torres, A. [National Institute of Astrophysics, Optics and Electronics, INAOE, P.O. Box 51 and 216, Puebla, Z. P. 72840 Puebla (Mexico); Ambrosio, R. [Technology and Engineering Institute, Ciudad Juarez University UACJ, Av. Del Charro 450N, Z. P. 32310 Chihuahua (Mexico); Rosales, P.; Kosarev, A.; Reyes-Betanzo, C.; Hidalga-Wade, J. de la; Zuniga, C.; Calleja, W. [National Institute of Astrophysics, Optics and Electronics, INAOE, P.O. Box 51 and 216, Puebla, Z. P. 72840 Puebla (Mexico)

    2013-12-02

    In this work we have studied boron doping of hydrogenated amorphous germanium a-Ge:H and polymorphous germanium (pm-Ge:H) in low regimes, in order to compensate the material from n-type (due to oxygen contamination that commonly occurs during plasma deposition) to intrinsic, and in this manner improve the properties that are important for infrared (IR) detection, as activation energy (E{sub a}) and temperature coefficient of resistance (TCR). Electrical, structural and optical characterization was performed on the films produced. Measurements of the temperature dependence of conductivity, room temperature conductivity (σ{sub RT}), E{sub a} and current–voltage characteristics under IR radiation were performed in the compensated a-Ge:H and pm-Ge:H films. Our results demonstrate that, effectively, the values of E{sub a}, TCR and IR detection are improved on the a-Ge:H/pm-Ge:H films, using boron doping in low regimes, which results of interest for infrared detectors. - Highlights: • We reported boron doping compensation of amorphous and polymorphous germanium. • The films were deposited by plasma enhanced chemical vapor deposition. • The aim is to use the films as thermo-sensing elements in un-cooled microbolometers. • Those films have advantages over boron doped a-Si:H used in commercial detectors.

  8. Neutron-transmutation-doped germanium bolometers

    Science.gov (United States)

    Palaio, N. P.; Rodder, M.; Haller, E. E.; Kreysa, E.

    1983-01-01

    Six slices of ultra-pure germanium were irradiated with thermal neutron fluences between 7.5 x 10 to the 16th and 1.88 x 10 to the 18th per sq cm. After thermal annealing the resistivity was measured down to low temperatures (less than 4.2 K) and found to follow the relationship rho = rho sub 0 exp(Delta/T) in the hopping conduction regime. Also, several junction FETs were tested for noise performance at room temperature and in an insulating housing in a 4.2 K cryostat. These FETs will be used as first stage amplifiers for neutron-transmutation-doped germanium bolometers.

  9. Cosmogenic activation of Germanium and its reduction for low background experiments

    CERN Document Server

    Barabanov, I; Bezrukov, L; Denisov, A; Kornoukhov, V; Sobolevsky, N

    2006-01-01

    Production of $^{60}$Co and $^{68}$Ge from stable isotopes of Germanium by nuclear active component of cosmic rays is a principal background source for a new generation of $^{76}$Ge double beta decay experiments like GERDA and Majorana. The biggest amount of cosmogenic activity is expected to be produced during transportation of either enriched material or already grown crystal. In this letter properties and feasibility of a movable iron shield are discussed. Activation reduction factor of about 10 is predicted by simulations with SHIELD code for a simple cylindrical configuration. It is sufficient for GERDA Phase II background requirements. Possibility of further increase of reduction factor and physical limitations are considered. Importance of activation reduction during Germanium purification and detector manufacturing is emphasized.

  10. Preparation of High Purity Amorphous Boron Powder

    Directory of Open Access Journals (Sweden)

    K.V. Tilekar

    2005-10-01

    Full Text Available Amorphous boron powder of high purity (92-94 % with a particle size of l-2 mm is preferred as a fuel for fuel-rich propellants for integrated rocket ramjets and for igniter formulations. Thispaper describes the studies on process optimisation of two processes, ie, oxidative roasting of boron (roasting boron in air and roasting boron with zinc in an inert medium for preparing high purity boron. Experimental studies reveal that roasting boron with zinc at optimised process conditions yields boron of purity more than 93 per cent, whereas oxidative roasting method yields boron of purity - 92 per cent. Oxidative roasting has comparative edge over the other processes owing to its ease of scale-up and simplicity

  11. Interstitial oxygen in germanium and silicon

    Energy Technology Data Exchange (ETDEWEB)

    Artacho, E.; Yndurain, F. [Instituto Nicolas Cabrera and Departamento de Fisica de la Materia Condensada, C-III Universidad Autonoma de Madrid, 28049 Madrid (Spain); Pajot, B. [Groupe de Physique des Solides (Unite Associee au CNRS), Tour 23, Universite Denis Diderot, 2 Place Jussieu, 75251 Paris Cedex 05 (France); Ramirez, R.; Herrero, C.P. [Instituto de Ciencia de Materiales, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain); Khirunenko, L.I. [Institute of Physics, National Academy of Sciences of Ukraine, Prospect Nauki 46, 252650 Kiev 22 (Ukraine); Itoh, K.M. [Department of Applied Physics and Physico-Informatics, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223 (Japan); Haller, E.E. [Lawrence Berkeley National Laboratory and University of California, Berkeley, California 94720 (United States)

    1997-08-01

    The microscopic structure of interstitial oxygen in germanium and its associated dynamics are studied both experimentally and theoretically. The infrared absorption spectrum is calculated with a dynamical matrix model based on first-principles total-energy calculations describing the potential energy for the nuclear motions. Spectral features and isotope shifts are calculated and compared with available experimental results. From new spectroscopic data on natural and on quasimonoisotopic germanium samples, new isotope shifts have been obtained and compared with the theoretical predictions. The low-energy spectrum is analyzed in terms of a hindered rotor model. A fair understanding of the center is achieved, which is then compared with interstitial oxygen in silicon. The oxygen atom is nontrivially quantum delocalized both in silicon and in germanium, but the physics is shown to be very different: while the Si-O-Si quasimolecule is essentially linear, the Ge-O-Ge structure is puckered. The delocalization in a highly anharmonic potential well of oxygen in silicon is addressed using path-integral Monte Carlo simulations, for comparison with the oxygen rotation in germanium. The understanding achieved with this new information allows us to explain the striking differences between both systems, in both the infrared and the far-infrared spectral regions, and the prediction of the existence of hidden vibrational modes, never directly observed experimentally, but soundly supported by the isotope-shift analysis. {copyright} {ital 1997} {ital The American Physical Society}

  12. Interstitial oxygen in germanium and silicon

    Science.gov (United States)

    Artacho, Emilio; Ynduráin, Félix; Pajot, Bernard; Ramírez, Rafael; Herrero, Carlos P.; Khirunenko, Ludmila I.; Itoh, Kohei M.; Haller, Eugene E.

    1997-08-01

    The microscopic structure of interstitial oxygen in germanium and its associated dynamics are studied both experimentally and theoretically. The infrared absorption spectrum is calculated with a dynamical matrix model based on first-principles total-energy calculations describing the potential energy for the nuclear motions. Spectral features and isotope shifts are calculated and compared with available experimental results. From new spectroscopic data on natural and on quasimonoisotopic germanium samples, new isotope shifts have been obtained and compared with the theoretical predictions. The low-energy spectrum is analyzed in terms of a hindered rotor model. A fair understanding of the center is achieved, which is then compared with interstitial oxygen in silicon. The oxygen atom is nontrivially quantum delocalized both in silicon and in germanium, but the physics is shown to be very different: while the Si-O-Si quasimolecule is essentially linear, the Ge-O-Ge structure is puckered. The delocalization in a highly anharmonic potential well of oxygen in silicon is addressed using path-integral Monte Carlo simulations, for comparison with the oxygen rotation in germanium. The understanding achieved with this new information allows us to explain the striking differences between both systems, in both the infrared and the far-infrared spectral regions, and the prediction of the existence of hidden vibrational modes, never directly observed experimentally, but soundly supported by the isotope-shift analysis.

  13. Advances in Higher Purity Bi Sample Handling

    Institute of Scientific and Technical Information of China (English)

    ZHAO; Qing-zhang; HE; Ming; DONG; Ke-jun; SHEN; Hong-tao; YIN; Xin-yi; WU; Shao-yong; DOU; Liang; WANG; Xiao-ming; YANG; Xu-ran; XU; Yong-ning; LAN; Xiao-xi; PANG; Fang-fang; CAI; Li; JIANG; Shan

    2013-01-01

    Whether the decay rate of a radionuclide can be influenced by its external environment has always been a hot topic in nuclear science.Higher purity sample is very critical for the half-life measurements.Because using higher purity(6N)Bi metal instead of(4N)Bi target,in 210Po production to reduce the impact of radioactive impurity.The annealing process was performed to remove the damage in the lattice

  14. Polarization sensitivity of a segmented HPGe detector up to 10 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Hutter, C.; Babilon, M.; Bayer, W.; Galaviz, D.; Hartmann, T.; Mohr, P.; Mueller, S.; Rochow, W.; Savran, D.; Sonnabend, K.; Vogt, K.; Volz, S.; Zilges, A. E-mail: zilges@ikp.tu-darmstadt.de

    2002-08-21

    Linear {gamma}-ray polarization can be measured using segmented germanium detectors. The polarization sensitivity of the Compton scattering process leads to asymmetries in the signals of a segmented detector. We have measured the polarization sensitivity of a four-fold segmented large volume germanium detector up to photon energies of approximately 10 MeV for the first time. The detector and its performance are compared to smaller Compton polarimeters which have been analyzed in previous work. A possible application of the described Compton polarimeter will be parity assignments in photon scattering experiments.

  15. Ultra-thin films with highly absorbent porous media fine-tunable for coloration and enhanced color purity.

    Science.gov (United States)

    Yoo, Young Jin; Lim, Jin Ha; Lee, Gil Ju; Jang, Kyung-In; Song, Young Min

    2017-03-02

    We demonstrate ultra-thin, fine-tunable optical coatings with enhanced color purity based on highly absorbent porous media on a metal substrate. We show that the color range provided by these ultra-thin film coatings can be extended by making the absorptive dielectric layer porous. Oblique angle deposition (OAD) of a thin (10-25 nm) germanium (Ge) film by e-beam evaporation onto a thick gold substrate yields controlled porosity. Reflectance spectra and color representations from both calculations and experiments verify the enhancement of resonance tunability and color purity in the nano-tailored coatings. Angle independent reflection properties, and the applicability of such porous Ge on various metal substrates, indicate the strength of these concepts.

  16. Purity calculation method for event samples with two the same particles

    CERN Document Server

    Kuzmin, Valentin

    2016-01-01

    We present a method of the two dimensional background calculation for an analysis of events with two the same particles observing by a detector of high energy physics. Usual two dimensional integration is replaced by an approximation of a specially constructed one-dimensional function. The value of the signal events is found by the subtraction of the background from the value of all selected events. It allows to calculate the purity value of the selected events sample. The procedure does not require a hypothesis about background and signal shapes. The nice performance of the purity calculation method is shown on Monte Carlo examples of double J/psi samples.

  17. Comparison of organic and inorganic germanium compounds in cellular radiosensitivity and preparation of germanium nanoparticles as a radiosensitizer.

    Science.gov (United States)

    Lin, Ming-Hsing; Hsu, Tzu-Sheng; Yang, Pei-Ming; Tsai, Meng-Yen; Perng, Tsong-Pyng; Lin, Lih-Yuan

    2009-03-01

    The aim of this work is to compare the radiosensitizing effect between organic and inorganic germanium compounds and to investigate whether nanometer-sized germanium particles can act as radiosensitizers. Bis (2-carboxyethylgermanium) sesquioxide (Ge-132), germanium oxide (GeO(2)) and germanium nanoparticles were used in this study. Cell viability was determined by clonogenic survival assay. Cellular DNA damage was evaluated by alkaline comet assay, confocal microscopy and the cellular level of phospho-histone H2AX (gamma-H2AX). Nanometer-sized germanium particles were fabricated. They have a similar radiosensitizing effect as that of GeO(2). Conversely, Ge-132 did not enhance the radiosensitivity of cells. Comet assay was employed to evaluate the level of DNA damage and confirmed that inorganic germanium compounds enhanced cellular radiosensitivity. Notably, the comet assay indicated that the nanoparticle itself caused a higher level of DNA damage. The possibility that germanium nanoparticles per se caused DNA damage was ruled out when the cellular level of gamma-H2AX was examined. We demonstrated that inorganic but not organic germanium compounds exerted radiosensitizing effect in cells. Nanometer-sized germanium particles were fabricated and were able to enhance the radiosensitivity of cells. Confounding effect may occur when comet assay is used to estimate the level of DNA damage in the presence of germanium nanoparticles.

  18. A feasibility study to determine cooling time and burnup of ATR fuel using a nondestructive technique and three types of gamma-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, J.; Aryaeinejad, R.; Nigg, D.W. [Idaho National Laboratory, P. O. Box 1625, Idaho Falls, ID 83415 (United States)

    2011-07-01

    The goal of this work was to perform a feasibility study and establish measurement techniques to determine the burnup of the Advanced Test Reactor (ATR) fuels at the Idaho National Laboratory (INL). Three different detectors of high purity germanium (HPGe), lanthanum bromide (LaBr{sub 3}), and high pressure xenon (HPXe) in two detection system configurations of below and above the water pool were used in this study. The last two detectors were used for the first time in fuel burnup measurements. The results showed that a better quality spectra can be achieved with the above the water pool configuration. Both short and long cooling time fuels were investigated in order to determine which measurement technique, absolute or fission product ratio, is better suited in each scenario and also to establish what type of detector should be used in each case for the best burnup measurement. The burnup and cooling time calibrations were established using experimental absolute activities or isotopic ratios and ORIGEN burnup calculations. A method was developed to do burnup and cooling time calibrations using fission isotopes activities without the need to know the exact geometry. (authors)

  19. Experimentally determining the relative efficiency of spherically bent germanium and quartz crystals

    Science.gov (United States)

    Brown, G. V.; Beiersdorfer, P.; Hell, N.; Magee, E.

    2016-11-01

    We have used the EBIT-I electron beam ion trap at the Lawrence Livermore National Laboratory and a duplicate Orion High Resolution X-ray Spectrometer (OHREX) to measure the relative efficiency of a spherically bent quartz (10 1 ¯ 1) crystal (2d = 6.687 Å) and a spherically bent germanium (111) crystal (2d = 6.532 Å). L-shell X-ray photons from highly charged molybdenum ions generated in EBIT-I were simultaneously focussed and Bragg reflected by each crystal, both housed in a single spectrometer, onto a single CCD X-ray detector. The flux from each crystal was then directly compared. Our results show that the germanium crystal has a reflection efficiency significantly better than the quartz crystal, however, the energy resolution is significantly worse. Moreover, we find that the spatial focussing properties of the germanium crystal are worse than those of the quartz crystal. Details of the experiment are presented, and we discuss the advantages of using either crystal on a streak-camera equipped OHREX spectrometer.

  20. Results from a Low-Energy Analysis of the CDMS II Germanium Data

    CERN Document Server

    Ahmed, Z; Arrenberg, S; Bailey, C N; Balakishiyeva, D; Baudis, L; Bauer, D A; Brink, P L; Bruch, T; Bunker, R; Cabrera, B; Caldwell, D O; Cooley, J; Cushman, P; Daal, M; DeJongh, F; Dragowsky, M R; Duong, L; Fallows, S; Figueroa-Feliciano, E; Filippini, J; Fritts, M; Golwala, S R; Hall, J; Hennings-Yeomans, R; Hertel, S A; Holmgren, D; Hsu, L; Huber, M E; Kamaev, O; Kiveni, M; Kos, M; Leman, S W; Mahapatra, R; Mandic, V; McCarthy, K A; Mirabolfathi, N; Moore, D; Nelson, H; Ogburn, R W; Phipps, A; Pyle, M; Qiu, X; Ramberg, E; Rau, W; Reisetter, A; Saab, T; Sadoulet, B; Sander, J; Schnee, R W; Seitz, D N; Serfass, B; Sundqvist, K M; Tarka, M; Wikus, P; Yellin, S; Yoo, J; Young, B A; Zhang, J

    2010-01-01

    We report results from a reanalysis of data from the Cryogenic Dark Matter Search (CDMS II) experiment at the Soudan Underground Laboratory. Data taken between October 2006 and September 2008 using eight germanium detectors are reanalyzed with a lowered, 2 keV recoil-energy threshold, to give increased sensitivity to interactions from Weakly Interacting Massive Particles (WIMPs) with masses below ~10 GeV/c^2. This analysis provides stronger constraints than previous CDMS II results for WIMP masses below 9 GeV/c^2 and excludes parameter space associated with possible low-mass WIMP signals from the DAMA/LIBRA and CoGeNT experiments.

  1. Enhanced shower formation in aligned thick germanium crystals and discrimination against charged hadrons

    Science.gov (United States)

    Baurichter, A.; Kirsebom, K.; Medewaldt, R.; Mikkelsen, U.; Møller, S.; Uggerhøj, E.; Worm, T.; Elsener, K.; Ballestrero, S.; Sona, P.; Romano, J.

    1995-11-01

    The distribution of the energy released in a thin silicon detector placed on the downstream side of a thick germanium single crystal bombarded with a 150 GeV electron or pion beam along directions close to the axis or along random directions has been investigated. In view of a possible application to very high energy gamma ray astronomy and particle physics, the intrinsic capability of such a device to reject, on the basis of energy discrimination, unwanted events due to charged hadrons together with the resulting loss of efficiency for the detection of showers initiated by high energy electrons, is determined as a function of the chosen energy threshold.

  2. Spin transport in p-type germanium.

    Science.gov (United States)

    Rortais, F; Oyarzún, S; Bottegoni, F; Rojas-Sánchez, J-C; Laczkowski, P; Ferrari, A; Vergnaud, C; Ducruet, C; Beigné, C; Reyren, N; Marty, A; Attané, J-P; Vila, L; Gambarelli, S; Widiez, J; Ciccacci, F; Jaffrès, H; George, J-M; Jamet, M

    2016-04-27

    We report on the spin transport properties in p-doped germanium (Ge-p) using low temperature magnetoresistance measurements, electrical spin injection from a ferromagnetic metal and the spin pumping-inverse spin Hall effect method. Electrical spin injection is carried out using three-terminal measurements and the Hanle effect. In the 2-20 K temperature range, weak antilocalization and the Hanle effect provide the same spin lifetime in the germanium valence band (≈1 ps) in agreement with predicted values and previous optical measurements. These results, combined with dynamical spin injection by spin pumping and the inverse spin Hall effect, demonstrate successful spin accumulation in Ge. We also estimate the spin Hall angle θ(SHE) in Ge-p (6-7 x 10(-4) at room temperature, pointing out the essential role of ionized impurities in spin dependent scattering.

  3. Indium-carbon pairs in germanium

    Energy Technology Data Exchange (ETDEWEB)

    Tessema, G; Vianden, R [Helmholtz Institut fuer Strahlen-und Kernphysik, Universitaet Bonn, Nussallee 14-16, 53115 Bonn (Germany)

    2003-08-06

    The interactions of carbon with the probe nucleus {sup 111}In have been studied in germanium using the perturbed angular correlation method, which has the ability to detect the microscopic environments of the probe atom by means of the interaction of the nuclear moments of the probe with the surrounding electromagnetic fields. At high dose carbon implantation in germanium two complexes have been identified by their unique quadrupole interaction frequencies. An interaction frequency of {nu}{sub Q1} = 207(1) MHz ({eta} = 0.16(3)) appeared at annealing temperatures below 650 deg. C. Above 650 deg. C, it was replaced by a second interaction frequency of {nu}{sub Q2} 500(1) MHz ({eta} = 0). The frequencies are attributed to two different carbon-indium pairs. The orientation of the corresponding electric field gradients and the thermal stability of the defect complexes are studied.

  4. Delayed charge recovery discrimination of passivated surface alpha events in P-type point-contact detectors

    CERN Document Server

    Gruszko, J; Arnquist, I J; Avignone, F T; Barabash, A S; Bertrand, F E; Bradley, A W; Brudanin, V; Busch, M; Buuck, M; Caldwell, T S; Chan, Y-D; Christofferson, C D; Chu, P H; Cuesta, C; Detwiler, J A; Dunagan, C; Efremenko, Yu; Ejiri, H; Elliott, S R; Fullmer, A; Galindo-Uribarri, A; Gilliss, T; Giovanetti, G K; Green, M P; Gruszko, J; Guinn, I S; Guiseppe, V E; Henning, R; Hoppe, E W; Howe, M A; Jasinski, B R; Keeter, K J; Kidd, M F; Konovalov, S I; Kouzes, R T; Leon, J; Lopez, A M; MacMullin, J; Martin, R D; Massarczyk, R; Meijer, S J; Mertens, S; Orrell, J L; O'Shaughnessy, C; Poon, A W P; Radford, D C; Rager, J; Rielage, K; Robertson, R G H; Romero-Romero, E; Shanks, B; Shirchenko, M; Suriano, A M; Tedeschi, D; Trimble, J E; Varner, R L; Vasilyev, S; Vetter, K; Vorren, K; White, B R; Wilkerson, J F; Wiseman, C; Xu, W; Yakushev, E; Yu, C H; Yumatov, V; Zhitnikov, I

    2016-01-01

    The Majorana Demonstrator searches for neutrinoless double-beta decay of $^{76}$Ge using arrays of high-purity germanium detectors. If observed, this process would demonstrate that lepton number is not a conserved quantity in nature, with implications for grand-unification and for explaining the predominance of matter over antimatter in the universe. A problematic background in such large granular detector arrays is posed by alpha particles. In the Majorana Demonstrator, events have been observed that are consistent with energy- degraded alphas originating on the passivated surface, leading to a potential background contribution in the region-of-interest for neutrinoless double-beta decay. However, it is also observed that when energy deposition occurs very close to the passivated surface, charges drift through the bulk onto that surface, and then drift along it with greatly reduced mobility. This leads to both a reduced prompt signal and a measurable change in slope of the tail of a recorded pulse. In this c...

  5. Delayed charge recovery discrimination of passivated surface alpha events in P-type point-contact detectors

    Science.gov (United States)

    Gruszko, J.; Majorana Collaboration

    2017-09-01

    The Majorana Demonstrator searches for neutrinoless double-beta decay of 76Ge using arrays of high-purity germanium detectors. If observed, this process would demonstrate that lepton number is not a conserved quantity in nature, with implications for grand-unification and for explaining the predominance of matter over antimatter in the universe. A problematic background in such large granular detector arrays is posed by alpha particles. In the Majorana Demonstrator, events have been observed that are consistent with energy-degraded alphas originating on the passivated surface, leading to a potential background contribution in the region-of-interest for neutrinoless double-beta decay. However, it is also observed that when energy deposition occurs very close to the passivated surface, charges drift through the bulk onto that surface, and then drift along it with greatly reduced mobility. This leads to both a reduced prompt signal and a measurable change in slope of the tail of a recorded pulse. In this contribution we discuss the characteristics of these events and the development of a filter that can identify the occurrence of this delayed charge recovery, allowing for the efficient rejection of passivated surface alpha events in analysis.

  6. Production, characterization and operation of {sup 76}Ge enriched BEGe detectors in GERDA

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-02-01

    The GERmanium Detector Array (GERDA) at the Gran Sasso Underground Laboratory (LNGS) searches for the neutrinoless double beta decay (0νββ) of {sup 76}Ge. Germanium detectors made of material with an enriched {sup 76}Ge fraction act simultaneously as sources and detectors for this decay. During Phase I of the experiment mainly refurbished semi-coaxial Ge detectors from former experiments were used. For the upcoming Phase II, 30 new {sup 76}Ge enriched detectors of broad energy germanium (BEGe)- type were produced. A subgroup of these detectors has already been deployed in GERDA during Phase I. The present paper reviews the complete production chain of these BEGe detectors including isotopic enrichment, purification, crystal growth and diode production. The efforts in optimizing the mass yield and in minimizing the exposure of the {sup 76}Ge enriched germanium to cosmic radiation during processing are described. Furthermore, characterization measurements in vacuum cryostats of the first subgroup of seven BEGe detectors and their long-term behavior in liquid argon are discussed. The detector performance fulfills the requirements needed for the physics goals of GERDA Phase II. (orig.)

  7. Vacancy-indium clusters in implanted germanium

    KAUST Repository

    Chroneos, Alexander I.

    2010-04-01

    Secondary ion mass spectroscopy measurements of heavily indium doped germanium samples revealed that a significant proportion of the indium dose is immobile. Using electronic structure calculations we address the possibility of indium clustering with point defects by predicting the stability of indium-vacancy clusters, InnVm. We find that the formation of large clusters is energetically favorable, which can explain the immobility of the indium ions. © 2010 Elsevier B.V. All rights reserved.

  8. The impact of neutral impurity concentration on charge drift mobility in germanium

    CERN Document Server

    Mei, H; Wang, G -J; Yang, G

    2016-01-01

    We report a new result of the neutral impurity scattering of electrons and holes that has impact on the charge drift mobility in high purity germanium crystals at 77 Kelvin. The charge carrier concentration, mobility and resistivity are measured by Hall Effect system at 77 Kelvin. We investigated the contribution to the total charge drift mobility from ionized impurity scattering, lattice scattering, and neutral impurity scattering with the best theoretical models and experimental data. Several samples with measured Hall mobility from the grown crystals are used for this investigation. With the measured Hall mobility and ionized impurity concentration as well as the theoretical models, we calculated the neutral impurity concentration by the Matthiessen's rule. As a result, the distributions of the neutral impurity concentrations with respect to the radius of the crystals are obtained. Consequently, we demonstrate that neutral impurity scattering is a significant contribution to the charge drift mobility, whic...

  9. Epitaxial silicon and germanium on buried insulator heterostructures and devices

    Science.gov (United States)

    Bojarczuk, N. A.; Copel, M.; Guha, S.; Narayanan, V.; Preisler, E. J.; Ross, F. M.; Shang, H.

    2003-12-01

    Future microelectronics will be based upon silicon or germanium-on-insulator technologies and will require an ultrathin (<10 nm), flat silicon or germanium device layer to reside upon an insulating oxide grown on a silicon wafer. The most convenient means of accomplishing this is by epitaxially growing the entire structure on a silicon substrate. This requires a high quality crystalline oxide and the ability to epitaxially grow two dimensional, single crystal films of silicon or germanium on top of this oxide. We describe a method based upon molecular beam epitaxy and solid-phase epitaxy to make such structures and demonstrate working field-effect transistors on germanium-on-insulator layers.

  10. Smooth germanium nanowires prepared by a hydrothermal deposition process

    Energy Technology Data Exchange (ETDEWEB)

    Pei, L.Z., E-mail: lzpei1977@163.com [School of Materials Science and Engineering, Institute of Molecular Engineering and Applied Chemistry, Key Laboratory of Materials Science and Processing of Anhui Province, Anhui University of Technology, Ma' anshan, Anhui 243002 (China); Zhao, H.S. [School of Materials Science and Engineering, Institute of Molecular Engineering and Applied Chemistry, Key Laboratory of Materials Science and Processing of Anhui Province, Anhui University of Technology, Ma' anshan, Anhui 243002 (China); Tan, W. [Henkel Huawei Electronics Co. Ltd., Lian' yungang, Jiangsu 222006 (China); Yu, H.Y. [School of Materials Science and Engineering, Institute of Molecular Engineering and Applied Chemistry, Key Laboratory of Materials Science and Processing of Anhui Province, Anhui University of Technology, Ma' anshan, Anhui 243002 (China); Chen, Y.W. [Department of Materials Science, Fudan University, Shanghai 200433 (China); Fan, C.G. [School of Materials Science and Engineering, Institute of Molecular Engineering and Applied Chemistry, Key Laboratory of Materials Science and Processing of Anhui Province, Anhui University of Technology, Ma' anshan, Anhui 243002 (China); Zhang, Qian-Feng, E-mail: zhangqf@ahut.edu.cn [School of Materials Science and Engineering, Institute of Molecular Engineering and Applied Chemistry, Key Laboratory of Materials Science and Processing of Anhui Province, Anhui University of Technology, Ma' anshan, Anhui 243002 (China)

    2009-11-15

    Smooth germanium nanowires were prepared using Ge and GeO{sub 2} as the starting materials and Cu sheet as the substrate by a simple hydrothermal deposition process. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations show that the germanium nanowires are smooth and straight with uniform diameter of about 150 nm in average and tens of micrometers in length. X-ray diffraction (XRD) and Raman spectrum of the germanium nanowires display that the germanium nanowires are mainly composed of cubic diamond phase. PL spectrum shows a strong blue light emission at 441 nm. The growth mechanism is also discussed.

  11. Analysis of the effect of true coincidence summing on efficiency calibration for an HP GE detector

    Energy Technology Data Exchange (ETDEWEB)

    Rodenas, J.; Gallardo, S.; Ballester, S.; Primault, V. [Valencia Univ. Politecnica, Dept. de Ingenieria Quimica y Nuclear (Spain); Ortiz, J. [Valencia Univ. Politecnica, Lab. de Radiactividad Ambiental (Spain)

    2006-07-01

    The H.P. (High Purity) Germanium detector is commonly used for gamma spectrometry in environmental radioactivity laboratories. The efficiency of the detector must be calibrated for each geometry considered. This calibration is performed using a standard solution containing gamma emitter sources. The usual goal is the obtaining of an efficiency curve to be used in the determination of the activity of samples with the same geometry. It is evident the importance of the detector calibration. However, the procedure presents some problems as it depends on the source geometry (shape, volume, distance to detector, etc.) and shall be repeated when these factors change. That means an increasing use of standard solutions and consequently an increasing generation of radioactive wastes. Simulation of the calibration procedure with a validated computer program is clearly an important auxiliary tool for environmental radioactivity laboratories. This simulation is useful for both optimising calibration procedures and reducing the amount of radioactivity wastes produced. The M.C.N.P. code, based on the Monte Carlo method, has been used in this work for the simulation of detector calibration. A model has been developed for the detector as well as for the source contained in a Petri box. The source is a standard solution that contains the following radionuclides: {sup 241}Am, {sup 109}Cd, {sup 57}Co, {sup 139}Ce, {sup 203}Hg, {sup 113}Sn, {sup 85}Sr, {sup 137}Cs, {sup 88}Y and {sup 60}Co; covering a wide energy range (50 to 2000 keV). However, there are two radionuclides in the solution ({sup 60}Co and {sup 88}Y) that emit gamma rays in true coincidence. The effect of the true coincidence summing produces a distortion of the calibration curve at higher energies. To decrease this effect some measurements have been performed at increasing distances between the source and the detector. As the true coincidence effect is observed in experimental measurements but not in the Monte Carlo

  12. Bottom-up assembly of metallic germanium.

    Science.gov (United States)

    Scappucci, Giordano; Klesse, Wolfgang M; Yeoh, LaReine A; Carter, Damien J; Warschkow, Oliver; Marks, Nigel A; Jaeger, David L; Capellini, Giovanni; Simmons, Michelle Y; Hamilton, Alexander R

    2015-08-10

    Extending chip performance beyond current limits of miniaturisation requires new materials and functionalities that integrate well with the silicon platform. Germanium fits these requirements and has been proposed as a high-mobility channel material, a light emitting medium in silicon-integrated lasers, and a plasmonic conductor for bio-sensing. Common to these diverse applications is the need for homogeneous, high electron densities in three-dimensions (3D). Here we use a bottom-up approach to demonstrate the 3D assembly of atomically sharp doping profiles in germanium by a repeated stacking of two-dimensional (2D) high-density phosphorus layers. This produces high-density (10(19) to 10(20) cm(-3)) low-resistivity (10(-4)Ω · cm) metallic germanium of precisely defined thickness, beyond the capabilities of diffusion-based doping technologies. We demonstrate that free electrons from distinct 2D dopant layers coalesce into a homogeneous 3D conductor using anisotropic quantum interference measurements, atom probe tomography, and density functional theory.

  13. Platinum germanium ordering in UPtGe

    Science.gov (United States)

    Hoffmann, Rolf-Dieter; Pöttgen, Rainer; Lander, Gerry H.; Rebizant, Jean

    2001-09-01

    The non-centrosymmetric structure of UPtGe was investigated by X-ray diffraction on both powders and single crystals: EuAuGe type, Imm2, a=432.86(5), b=718.81(8), c=751.66(9) pm, wR2=0.0738 for 399 F2 values and 22 variables. The platinum and germanium atoms form two-dimensional layers of puckered Pt 3Ge 3 hexagons with short PtGe intralayer distances of 252 and 253 pm. These condensed two-dimensionally infinite nets are interconnected to each other via weak PtPt contacts with bond distances of 300 pm. The two crystallographically independent uranium atoms are situated above and below the six-membered platinum-germanium rings. The U1 atoms have six closer germanium neighbors while the U2 atoms have six closer platinum neighbors. The group-subgroup relation with the KHg 2 type structure is presented.

  14. Nanoscale resonant-cavity-enhanced germanium photodetectors with lithographically defined spectral response for improved performance at telecommunications wavelengths.

    Science.gov (United States)

    Balram, Krishna C; Audet, Ross M; Miller, David A B

    2013-04-22

    We demonstrate the use of a subwavelength planar metal-dielectric resonant cavity to enhance the absorption of germanium photodetectors at wavelengths beyond the material's direct absorption edge, enabling high responsivity across the entire telecommunications C and L bands. The resonant wavelength of the detectors can be tuned linearly by varying the width of the Ge fin, allowing multiple detectors, each resonant at a different wavelength, to be fabricated in a single-step process. This approach is promising for the development of CMOS-compatible devices suitable for integrated, high-speed, and energy-efficient photodetection at telecommunications wavelengths.

  15. Shape rheocasting of high purity aluminium

    CSIR Research Space (South Africa)

    Curle, UA

    2011-03-01

    Full Text Available It is demonstrated experimentally that using the Council for Scientific and Industrial Research Rheo Casting System and high pressure die casting it is possible to semi-solid process and cast into a shape high purity aluminium without a...

  16. Pristine Purity : New Political Parties in Canada

    NARCIS (Netherlands)

    Lucardie, Anthonie

    2007-01-01

    Success sells better than failure; hence new parties receive very little attention from political scientists as long as they remain marginal and fail to win seats in Parliament. Yet in the margins of the party system, they may maintain the pristine purity of political principles and ideas better tha

  17. Estimating purity in terms of correlation functions

    CERN Document Server

    Prosen, T; Znidaric, M; Prosen, Tomaz; Seligman, Thomas H.; Znidaric, Marko

    2003-01-01

    We prove a rigorous inequality estimating the purity of a reduced density matrix of a composite quantum system in terms of cross-correlation of the same state and an arbitrary product state. Various immediate applications of our result are proposed, in particular concerning Gaussian wave-packet propagation under classically regular dynamics.

  18. Radiation Hardening of Silicon Detectors

    CERN Multimedia

    Leroy, C; Glaser, M

    2002-01-01

    %RD48 %title\\\\ \\\\Silicon detectors will be widely used in experiments at the CERN Large Hadron Collider where high radiation levels will cause significant bulk damage. In addition to increased leakage current and charge collection losses worsening the signal to noise, the induced radiation damage changes the effective doping concentration and represents the limiting factor to long term operation of silicon detectors. The objectives are to develop radiation hard silicon detectors that can operate beyond the limits of the present devices and that ensure guaranteed operation for the whole lifetime of the LHC experimental programme. Radiation induced defect modelling and experimental results show that the silicon radiation hardness depends on the atomic impurities present in the initial monocrystalline material.\\\\ \\\\ Float zone (FZ) silicon materials with addition of oxygen, carbon, nitrogen, germanium and tin were produced as well as epitaxial silicon materials with epilayers up to 200 $\\mu$m thickness. Their im...

  19. Ultraviolet-light-induced processes in germanium-doped silica

    DEFF Research Database (Denmark)

    Kristensen, Martin

    2001-01-01

    A model is presented for the interaction of ultraviolet (UV) light with germanium-doped silica glass. It is assumed that germanium sites work as gates for transferring the excitation energy into the silica. In the material the excitation induces forbidden transitions to two different defect states...

  20. Yunnan Chihong Zinc & Germanium Co.,Ltd.Invested RMB 300 Million for Germanium Project with Output 30 Tons/Year

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>Recently,Yunnan Chihong Zinc & Germanium Co.,Ltd.,an A-share listed company held by Yunnan Metallurgical Group Co.,Ltd.,kicked off its construction of a project for comprehen- sive utilization of lead-zinc associated metal germanium resources to be output at 30 tons/year.It is introduced that the investment

  1. Silicon/Germanium Molecular Beam Epitaxy

    OpenAIRE

    2006-01-01

    Molecular Beam Epitaxy (MBE) is a well-established method to grow low-dimensional structures for research applications. MBE has given many contributions to the rapid expanding research-area of nano-technology and will probably continuing doing so. The MBE equipment, dedicated for Silicon/Germanium (Si/Ge) systems, at Karlstads University (Kau) has been studied and started for the first time. In the work of starting the system, all the built in interlocks has been surveyed and connected, and t...

  2. Tensile strain mapping in flat germanium membranes

    Energy Technology Data Exchange (ETDEWEB)

    Rhead, S. D., E-mail: S.Rhead@warwick.ac.uk; Halpin, J. E.; Myronov, M.; Patchett, D. H.; Allred, P. S.; Wilson, N. R.; Leadley, D. R. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Shah, V. A. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Department of Engineering, University of Warwick, Coventry, CV4 7AL (United Kingdom); Kachkanov, V.; Dolbnya, I. P. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE (United Kingdom); Reparaz, J. S. [ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona) (Spain); Sotomayor Torres, C. M. [ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona) (Spain)

    2014-04-28

    Scanning X-ray micro-diffraction has been used as a non-destructive probe of the local crystalline quality of a thin suspended germanium (Ge) membrane. A series of reciprocal space maps were obtained with ∼4 μm spatial resolution, from which detailed information on the strain distribution, thickness, and crystalline tilt of the membrane was obtained. We are able to detect a systematic strain variation across the membranes, but show that this is negligible in the context of using the membranes as platforms for further growth. In addition, we show evidence that the interface and surface quality is improved by suspending the Ge.

  3. Radiation piezoelectric effect in germanium single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kikoin, I.K.; Kikoin, L.I.; Lazarev, S.D.

    1977-06-01

    Irradiation with ionizing particles of a germanium single crystal and uniaxial deformation at right-angles to the particle beam produced an electric field and a corresponding emf due to the radiation piezoelectric effect. Measurements were carried out when such a single crystal was irradiated with ..cap alpha.. particles and protons. The piezoelectric emf increased linearly with the compressive stress and the ..cap alpha..-particle flux intensity. The emf depended weakly on the particle energy. The observed effect was due to the anisotropy resulting from uniaxial deformation.

  4. Silicon germanium mask for deep silicon etching

    KAUST Repository

    Serry, Mohamed

    2014-07-29

    Polycrystalline silicon germanium (SiGe) can offer excellent etch selectivity to silicon during cryogenic deep reactive ion etching in an SF.sub.6/O.sub.2 plasma. Etch selectivity of over 800:1 (Si:SiGe) may be achieved at etch temperatures from -80 degrees Celsius to -140 degrees Celsius. High aspect ratio structures with high resolution may be patterned into Si substrates using SiGe as a hard mask layer for construction of microelectromechanical systems (MEMS) devices and semiconductor devices.

  5. Results from the characterisation of Advanced GAmma Tracking Array prototype detectors and their consequences for the next-generation nuclear physics spectrometer

    Science.gov (United States)

    Dimmock, M. R.; Boston, A. J.; Boston, H. C.; Cresswell, J. R.; Nelson, L.; Nolan, P.; Rigby, S.; Unsworth, C.; Lazarus, I.; Simpson, J.; Medina, P.; Parisel, C.; Santos, C.

    2007-09-01

    The Advanced GAmma Tracking Array (AGATA) is a European project that is aiming to construct a complete 4π High Purity Germanium (HPGe) gamma-ray spectrometer for nuclear structure studies at future Radioactive Ion Beam (RIB) Facilities. The proposed array will utilise digital electronics, Pulse Shape Analysis (PSA) and Gamma-Ray Tracking (GRT) algorithms, to overcome the limited efficiencies encountered by current Escape Suppressed Spectrometers (ESS), whilst maintaining the high Peak-to-Total ratio. Two AGATA symmetrical segmented Canberra Eurisys (CE) prototype HPGe detectors have been tested at the University of Liverpool. A highly collimated Cs-137 (662keV) beam was raster scanned across each detector and data were collected in both singles and coincidence modes. The charge sensitive preamplifier output pulse shapes from all 37 channels (one for each of the 36 segments and one for the centre contact) were digitised and stored for offline analysis. The shapes of the real charge and image charge pulses have been studied to give detailed information on the position dependent response of each detector. 1mm position sensitivity has been achieved with the parameterisation of average pulse shapes, calculated from data collected with each of the detectors. The coincidence data has also been utilised to validate the electric field simulation code Multi Geometry Simulation (MGS). The precisely determined 3D interaction positions allow the comparison of experimental pulse shapes from single site interactions with those generated by the simulation. It is intended that the validated software will be used to calculate a basis data set of pulse shapes for the array, from which any interaction site can be determined through a χ2 minimisation of the digitized pulse with linear combinations of basis pulseshapes. The results from this partial validation, along with those from the investigation into the position sensitivity of each detector are presented.

  6. Nonlinear control of high purity distillation columns

    OpenAIRE

    Groebel, Markus; Allgöwer, Frank; Storz, Markus; Gilles, Ernst Dieter

    1994-01-01

    Two simple models of distillation columns are studied to investigate their suitability for the practical use with exact I/O-linearization. An extension of exact I/O-linearization, the asymptotically exact I/O-linearization is applied to the control of a high purity distillation column, using one of these models to derive the static state feedback law. Simulation studies demonstrate the advantage of asymptotically exact I/O-linearization versus classical exact I/O-linearization techniques. Exp...

  7. Purity of targets prepared on Cu substrates

    Science.gov (United States)

    Méens, A.; Rossini, I.; Sens, J. C.

    1993-09-01

    The purity of several elemental self-supporting targets usually prepared by evaporation onto soluble Cu substrates has been studied. The targets were analysed by Rutherford backscattering and instrumental neutron activation analysis. Because of the high percentage of Cu observed in some Si targets, further measurements, including transmission electron microscopy, have been performed on Si targets deposited by e-gun bombardment onto Cu and ion-beam sputtering onto betaine.

  8. Effects of Germanium on Movement of Dislocations in p-Type Czochralski Silicon

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    By indentation at room temperature followed by annealing at high temperatures, the pinning effect of germanium on dislocations in germanium-doped Czochralski silicon was investigated. Experimental results show that the dislocations in germanium-doped Czochralski silicon move shorter and slower than those in Czochralski silicon undoping with germanium when the concentration of germanium is over 1×1018 cm-3. The retarding velocity of dislocations is contributed to the dislocations pinning effect of the strain field introduced by the high concentration germanium, and the Ge4B cluster and the oxygen precipitation those are preferred to form at higher concentration germanium.

  9. Liquid-purity monitor for the LUX-ZEPLIN dark matter search

    Science.gov (United States)

    Manalaysay, Aaron; Lux-Zeplin Collaboration

    2016-03-01

    The LUX-ZEPLIN (LZ) experiment will be the first liquid-xenon (LXe) dark matter search to feature a multi-tonne fiducial target. Drawing on the lessons learned in the LUX and ZEPLIN experiments, this next step will probe dark-matter candidates with unprecedented sensitivity. As these LXe detectors have grown larger, so too has the distance over which ionization electrons (from particle interactions) must be drifted through the liquid. Because of this, even minute levels of electronegative impurities can significantly attenuate the ionization signal, and must therefore be closely monitored. I will present the concept of a liquid-purity monitor which uses new and novel techniques, including state-of-the-art UV LEDs and low-work-function materials, and will measure levels of impurities in LZ's liquid circulation line in real time. This device will provide vital supplemental data to the roughly weekly in-situ purity measurements carried out within the detector's active volume, will greatly improve the resolution of the ionization channel in this detector, and will yield instant feedback in response to changing detector conditions.

  10. Oxygen defect processes in silicon and silicon germanium

    KAUST Repository

    Chroneos, A.

    2015-06-18

    Silicon and silicon germanium are the archetypical elemental and alloy semiconductor materials for nanoelectronic, sensor, and photovoltaic applications. The investigation of radiation induced defects involving oxygen, carbon, and intrinsic defects is important for the improvement of devices as these defects can have a deleterious impact on the properties of silicon and silicon germanium. In the present review, we mainly focus on oxygen-related defects and the impact of isovalent doping on their properties in silicon and silicon germanium. The efficacy of the isovalent doping strategies to constrain the oxygen-related defects is discussed in view of recent infrared spectroscopy and density functional theory studies.

  11. The Genesis of Lincang Germanium Deposit—A Preliminary Investigation

    Institute of Scientific and Technical Information of China (English)

    胡瑞忠; 叶造军; 等

    1996-01-01

    The mechanism of formation of the Lincang germanium deposit is discussed in the light of the spatial distribution of Ge-rich coal and siliceous rocks,the sulfur isotopic composition of pyrite in the Ge-rich coal,the variation of Ge abundance in the coal seams and the geochemical characteristics of the siliceous rocks.The results show that the siliceous rocks intercalated with the coal seamw were deposited from a hyrothermal medium through which germanium was enriched in the coal beds.The primary source of germanium is thought to be the Gerich granite in the basement of the sedimentary basin.

  12. Temperature-dependant study of phosphorus ion implantation in germanium

    Science.gov (United States)

    Razali, M. A.; Smith, A. J.; Jeynes, C.; Gwilliam, R. M.

    2012-11-01

    We present experimental results on shallow junction formation in germanium by phosphorus ion implantation and standard rapid thermal processing. An attempt is made to improve phosphorus activation by implanting phosphorus at high and low temperature. The focus is on studying the germanium damage and phosphorus activation as a function of implant temperature. Rutherford backscattering spectrometry with channelling and Hall Effect measurements are employed for characterisation of germanium damage and phosphorus activation, respectively. High and low temperature implants were found to be better compared to room temperature implant.

  13. Oxygen defect processes in silicon and silicon germanium

    Energy Technology Data Exchange (ETDEWEB)

    Chroneos, A., E-mail: alexander.chroneos@imperial.ac.uk [Faculty of Engineering and Computing, Coventry University, Priory Street, Coventry CV1 5FB (United Kingdom); Department of Materials, Imperial College London, London SW7 2BP (United Kingdom); Sgourou, E. N.; Londos, C. A. [Solid State Section, Physics Department, University of Athens, Panepistimiopolis, Zografos, 157 84 Athens (Greece); Schwingenschlögl, U. [PSE Division, KAUST, Thuwal 23955-6900 (Saudi Arabia)

    2015-06-15

    Silicon and silicon germanium are the archetypical elemental and alloy semiconductor materials for nanoelectronic, sensor, and photovoltaic applications. The investigation of radiation induced defects involving oxygen, carbon, and intrinsic defects is important for the improvement of devices as these defects can have a deleterious impact on the properties of silicon and silicon germanium. In the present review, we mainly focus on oxygen-related defects and the impact of isovalent doping on their properties in silicon and silicon germanium. The efficacy of the isovalent doping strategies to constrain the oxygen-related defects is discussed in view of recent infrared spectroscopy and density functional theory studies.

  14. A xenon gas purity monitor for EXO

    CERN Document Server

    Dobi, A; Herrin, S; Odian, A; Prescott, C Y; Rowson, P C; Ackerman, N; Aharmin, B; Auger, M; Barbeau, P S; Barry, K; Benitez-Medina, C; Breidenbach, M; Cook, S; Counts, I; Daniels, T; DeVoe, R; Dolinski, M J; Donato, K; Fairbank, W; Farine, J; Giroux, G; Gornea, R; Graham, K; Gratta, G; Green, M; Hagemann, C; Hall, K; Hallman, D; Hargrove, C; Karelin, A; Kaufman, L J; Kuchenkov, A; Kumar, K; Lacey, J; Leonard, D S; LePort, F; Mackay, D; MacLellan, R; Mong, B; Diez, M Montero; Muller, A R; Neilson, R; Niner, E; O'Sullivan, K; Piepke, A; Pocar, A; Pushkin, K; Rollin, E; Sinclair, D; Slutsky, S; Stekhanov, V; Twelker, K; Voskanian, N; Vuilleumier, J -L; Wichoski, U; Wodin, J; Yang, L; Yen, Y -R

    2011-01-01

    We discuss the design, operation, and calibration of two versions of a xenon gas purity monitor (GPM) developed for the EXO double beta decay program. The devices are sensitive to concentrations of oxygen well below 1 ppb at an ambient gas pressure of one atmosphere or more. The theory of operation of the GPM is discussed along with the interactions of oxygen and other impurities with the GPM's tungsten filament. Lab tests and experiences in commissioning the EXO-200 double beta decay experiment are described. These devices can also be used on other noble gases.

  15. Analysis of the liquid argon purity in the ICARUS T600 TPC

    Energy Technology Data Exchange (ETDEWEB)

    Amoruso, S.; Antonello, M.; Aprili, P.; Arneodo, F.; Badertscher, A.; Baiboussinov, B.; Baldo Ceolin, M.; Battistoni, G.; Bekman, B.; Benetti, P.; Bernardini, E.; Bischofberger, M.; Borio di Tigliole, A.; Brunetti, R.; Bruzzese, R.; Bueno, A.; Buzzanca, M.; Calligarich, E.; Campanelli, M.; Carbonara, F.; Carpanese, C.; Cavalli, D.; Cavanna, F.; Cennini, P.; Centro, S.; Cesana, A.; Chen, C.; Chen, D.; Chen, D.B.; Chen, Y.; Cieslik, X.; Cline, D.; Cocco, A.G.; Dai, Z.; De Vecchi, C.; Dabrowska, A.; Di Cicco, A.; Dolfini, R.; Ereditato, A.; Felcini, M.; Ferrari, A.; Ferri, F.; Fiorillo, G.; Galli, S.; Ge, Y.; Gibin, D.; Gigli Berzolari, A.; Gil-Botella, I.; Graczyk, K.; Grandi, L.; Guglielmi, A.; He, K.; Holeczek, J.; Huang, X.; Juszczak, C.; Kielczewska, D.; Kisiel, J.; Kozlowski, T.; Laffranchi, M.; Lagoda, J.; Li, Z.; Lu, F.; Ma, J.; Mangano, G.; Markiewicz, M.; Martinez de la Ossa, A.; Matthey, C.; Mauri, F.; Meng, G.; Messina, M.; Montanari, C.; Muraro, S.; Navas-Concha, S. E-mail: navas@ugr.es; Nurzia, G.; Otwinowski, S.; Ouyang, Q.; Palamara, O.; Pascoli, D.; Periale, L.; Piano Mortari, G.B.; Piazzoli, A.; Picchi, P.; Pietropaolo, F.; Polchlopek, W.; Rancati, T.; Rappoldi, A.; Raselli, G.L.; Rico, J.; Rondio, E.; Rossella, M.; Rubbia, A.; Rubbia, C.; Sala, P.; Santorelli, R.; Scannicchio, D.; Segreto, E.; Seo, Y.; Sergiampietri, F.; Sobczyk, J.; Spinelli, N.; Stepaniak, J.; Szarska, M.; Szeptycka, M.; Szleper, M.; Terrani, M.; Velotta, R.; Ventura, S.; Vignoli, C.; Wang, H.; Wang, X.; Woo, J.; Xu, G.; Xu, Z.; Zalewska, A.; Zalipska, J.; Zhang, C.; Zhang, Q.; Zhen, S.; Zipper, W

    2004-01-01

    The results reported in this paper are based on the analysis of the data recorded with the first half-module of the ICARUS T600 liquid argon Time Projection Chamber (LAr TPC), during a technical run that took place on surface in Pavia (Italy). We include results from the linearity, uniformity and calibration of the electronics, measurements on the electron drift velocity in LAr at different electric fields, as well as the LAr purity achievement of the detector. Two complementary techniques were used to measure the drift electron lifetime inside the active volume: the first, from the data of a purity monitor, gives a measurement localized in space; the second, based on the study of the signals produced by long minimum ionizing tracks crossing the detector, provides a LAr volume averaged value. Both methods yield consistent results over the whole data taking period and are compatible with an uniform LAr purity over the whole volume. The maximal drift electron lifetime value was recorded before the run stop and was about 1.8 ms. From an interpretation of the observed drift electron lifetime as a function of time, we conclude that the adopted technology would allow for drift distances exceeding 3 m.

  16. Heteroepitaxial growth of relaxed germanium on silicon

    Science.gov (United States)

    Nayfeh, Ammar

    Germanium has a many advantages to silicon as a semiconductor material. Most importantly, Ge has a larger lattice mobility (hole and electron) compared to Si. The larger mobility provides a higher source injection velocity, which translates into higher drive current and smaller gate delay. In addition, the near-infrared photodetection and compatibility with Si technology of Ge-based materials, allow simultaneous fabrication of photodetectors and Si CMOS receiver circuits in a monolithically integrated fashion. The main disadvantage is that germanium based oxides are not stable and but rather soluble in water. But the inevitable shift to high-kappa/metal gate has made Ge a serious option nevertheless. In order for the semiconductor industry to take advantage of the properties of Ge, heterogeneous integration of Ge and Si must be possible since using bulk Ge is not viable. However, Ge growth on Si is hampered by the large lattice mismatch (4%) between Ge and Si which results in growth that is dominated by "islanding" and misfit dislocations. The following thesis, investigates both the islanding and dislocation density issues associated with this problem. A 90% reduction of surface roughness by hydrogen annealing is demonstrated accompanied with a theoretical model to explain these results. Using multi-steps of growth and hydrogen annealing, Ge layers on Si were achieved with dislocation density as low as 1x107cm-2 and Rrms surface roughness of 2.5nm. The method was patented and named, Multiple Hydrogen Annealing for Heteroexpitaxy (MHAH). A complete experimentally based theoretical model is provided that explains these results. In addition, MOSCAPS, a pMOS transistor, and a MSM photodetector are fabricated on the MHAH-Ge substrates. Also high-kappa/metal gate compatibility is demonstrated on MHAH-Ge. The electrical results indicate that MHAH-Ge approaches the electrical quality of bulk Ge. These results point to a promising step in achieving heterogeneous integration

  17. Positron annihilation in neutron-irradiated germanium

    Energy Technology Data Exchange (ETDEWEB)

    Bartenev, G.M.; Bardyshev, I.I.; Erchak, D.P.; Stel' makh, V.F.; Tsyganov, A.D.

    1979-04-01

    The annealing of radiation defects in a germanium single crystal irradiated with 10/sup 18/ neutrons/cm/sup 2/ was studied by positron annihilation, ESR, and resistivity measurements. It was found that positrons are trapped by radiation defects. The intensity of the narrow component of the angular correlation of the annihilation radiation yielded the concentration of defect clusters in the irradiated sample n/sub d/approx. =3 x 10/sup 14/ cm/sup -3/. Three characteristic annealing stages were identified. At 160--200 /sup 0/C, point defects were annealed within the crystal. At 200--320 /sup 0/C, there was ''loosening'' of the clusters, and the charge state of the defects changed. At 320--550 /sup 0/C, the clusters were annealed.

  18. Raman spectroscopy of hydrogen molecules in germanium

    Energy Technology Data Exchange (ETDEWEB)

    Hiller, M. [Technische Universitaet Dresden, 01062 Dresden (Germany)]. E-mail: martin.hiller@physik.phy.tu-dresden.de; Lavrov, E.V. [Technische Universitaet Dresden, 01062 Dresden (Germany); Weber, J. [Technische Universitaet Dresden, 01062 Dresden (Germany)

    2006-04-01

    Single-crystalline germanium samples exposed to hydrogen and/or deuterium plasma are studied by Raman scattering. Two bands at 1980 and 4155cm{sup -1} are assigned to local vibrational modes of Ge-H and H{sub 2}, respectively. Polarization sensitive Raman scattering spectra suggest that the plasma treatment results in {l_brace}111{r_brace} platelets whose basic units are Ge-H bonds. The signal at 4155cm{sup -1} is shown to result from molecular hydrogen trapped within these platelets. Another broad Raman signal around 3930cm{sup -1} seems to be due to H{sub 2} trapped in some other type of voids formed during the plasma treatment. Two sharp peaks at 3826 and 3834cm{sup -1} are assigned to ortho- and para-H{sub 2} trapped at the interstitial T site.

  19. Synthesis of silicon and germanium nanowires.

    Energy Technology Data Exchange (ETDEWEB)

    Clement, Teresa J. (Arizona State University); Hsu, Julia W. P.

    2007-11-01

    The vapor-liquid-solid growth process for synthesis of group-IV semiconducting nanowires using silane, germane, disilane and digermane precursor gases has been investigated. The nanowire growth process combines in situ gold seed formation by vapor deposition on atomically clean silicon (111) surfaces, in situ growth from the gaseous precursor(s), and real-time monitoring of nanowire growth as a function of temperature and pressure by a novel optical reflectometry technique. A significant dependence on precursor pressure and growth temperature for the synthesis of silicon and germanium nanowires is observed, depending on the stability of the specific precursor used. Also, the presence of a nucleation time for the onset of nanowire growth has been found using our new in situ optical reflectometry technique.

  20. Cell culture purity issues and DFAT cells

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Shengjuan [College of Animal Science and Technology, Northwest A and F University, Yangling, Shaanxi Province 712100 (China); Department of Animal Sciences, Washington State University, Pullman, WA 99164 (United States); Bergen, Werner G. [Program in Cellular and Molecular Biosciences/Department of Animal Sciences, Auburn University, Auburn, AL 36849 (United States); Hausman, Gary J. [Animal Science Department, University of Georgia, Athens, GA 30602-2771 (United States); Zan, Linsen, E-mail: zanls@yahoo.com.cn [College of Animal Science and Technology, Northwest A and F University, Yangling, Shaanxi Province 712100 (China); Dodson, Michael V., E-mail: dodson@wsu.edu [Department of Animal Sciences, Washington State University, Pullman, WA 99164 (United States)

    2013-04-12

    Highlights: •DFAT cells are progeny cells derived from dedifferentiated mature adipocytes. •Common problems in this research is potential cell contamination of initial cultures. •The initial cell culture purity is crucial in DFAT cell research field. -- Abstract: Dedifferentiation of mature adipocytes, in vitro, has been pursued/documented for over forty years. The subsequent progeny cells are named dedifferentiated adipocyte-derived progeny cells (DFAT cells). DFAT cells are proliferative and likely to possess mutilineage potential. As a consequence, DFAT cells and their progeny/daughter cells may be useful as a potential tool for various aspects of tissue engineering and as potential vectors for the alleviation of several disease states. Publications in this area have been increasing annually, but the purity of the initial culture of mature adipocytes has seldom been documented. Consequently, it is not always clear whether DFAT cells are derived from dedifferentiated mature (lipid filled) adipocytes or from contaminating cells that reside in an impure culture.

  1. Ultra-high purity arsenic for MBE

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, R.G.L. (Johnson Matthey PLC, Royston (UK)); Emeny, M.T.; Whitehouse, C.R.; Lee, D. (Royal Signals and Radar Ets., Great Malvern (UK))

    1990-11-01

    A requirement for high purity elemental arsenic for use in compound semiconductors has become well established. The capabilities of molecular beam epitaxy as a fabrication technique are best exploited if the arsenic used has particular additional features. Prominent among these are a uniform distribution of impurities at levels down to 10 ppb, and a geometrically uniform distribution of material in the charge used. Once material such as this, of 7N purity or better, emerges from its processing, a major vulernability is from recontamination. Prevention of this is a further important requirement. Detailed examination of possible process strategies has led to an approach targeted on the manufacture of solid arsenic ''charges'' especially suited for MBE application. Factors involved are reviewed. An outline of the consequent production operation is described, based on vapour phase and laser processing. Continuous long-term reproducibility is achieved. Analysis of the product by glow discharge mass spectrometry with state-of-the-art sensitivity is used for qualification of the product and process. Results from this and supplementary techniques which have been used are presented. The utilisation of this material for GaAs has been widely tested successfully. The outcome of some of that work is shown. (orig.).

  2. Lattice site and thermal stability of transition metals in germanium

    CERN Document Server

    Augustyns, Valérie; Pereira, Lino

    Although the first transistor was based on germanium, current chip technology mainly uses silicon due to its larger abundance, a lower price and higher quality silicon-oxide. However, a very important goal in microelectronics is to obtain faster integrated circuits. The advantages of germanium compared to silicon (e.g. a higher mobility of the charge carriers) motivates further research on germanium based materials. Semiconductor doping (e.g. introducing impurities into silicon and germanium in order to alter - and control - their properties) can be done by ion implantation or by in situ doping, whereby the host material is doped during growth. This thesis focuses on introducing dopants by ion implantation. The implantation as well as the subsequent measurements were performed in ISOLDE (CERN) using the emission channeling technique. Although ion implantation generates undesired defects in the host material (e.g. vacancies), such damage can be reduced by performing the implantation at an elevated temperature....

  3. A primary standard source of radon-222 based on the HPGe detector.

    Science.gov (United States)

    Mostafa, M Y A; Vasyanovich, M; Zhukovsky, M

    2017-02-01

    The present paper describes the prototype of a calibration standard system for radon concentrations to be used in establishing the traceability of radon concentration measurements in dwellings. Radon gas was generated with a radium-226 solid source in a certified volume as a closed system. The activity of the radon that was released in the closed system was determined from the difference between the absolute activity of the standard radium solid source and the residual radon decay products ((214)Bi or (214)Pb). A high-purity germanium (HPGe) detector, which was calibrated using gamma reference standard sources, was used to measure the activity of a radium solid source and radon decay products ((214)Bi or (214)Pb). The emanation factor of the (226)Ra source was controlled online with the HPGe detector. Radon activity was achieved at ~1500±45Bq from the radium source at 3.95±0.2kBq under equilibrium conditions. After this activity, the radon gas was transferred into the closed system producing radon activity concentrations of 31.1±0.3kBq/m(3). Systematic errors were found of less than 4% with a random error around 0.5%. The random error is generally associated with the estimation of the count rate of the measured radon progenies ((214)Po and (214)Po for alpha measurements or (214)Pb and (214)Bi for gamma measurements), but systematic errors are associated with the errors introduced by the instrumentation and measurement technique. The system that was developed has a high degree of accuracy and can be recommended as a national or regional prototype standard of radon activity concentration to calibrate different working radon measurement devices.

  4. Solid solubility of germanium in silver

    Energy Technology Data Exchange (ETDEWEB)

    Kazemi, Hamed [Laboratory of Mechanical Metallurgy, Ecole Polytechnique Federale de Lausanne, EPFL, CH-1015 Lausanne (Switzerland); Weber, Ludger, E-mail: ludger.weber@epfl.ch [Laboratory of Mechanical Metallurgy, Ecole Polytechnique Federale de Lausanne, EPFL, CH-1015 Lausanne (Switzerland)

    2012-09-20

    Highlights: Black-Right-Pointing-Pointer The solvus line in the binary Ag-Ge system has been assessed based on measurements of electrical resistivity and specific gravity. Black-Right-Pointing-Pointer The two measurement techniques yield close agreement. Black-Right-Pointing-Pointer The data found in this contribution indicate lower solid solubility than in previous assessments. Black-Right-Pointing-Pointer Redlich-Kister parameters have been evaluated to describe the solvus line. - Abstract: The solid solubility of germanium in silver has been measured in the temperature range of 520 K to 913 K via measurements of density and of electrical conductivity of two near-eutectic Ag-Ge alloys. The atomic fraction of germanium in solid solution varied between 0.014 and 0.089 over the mentioned range of temperature and an extrapolated maximum solubility of 0.093 at the eutectic temperature of 924 K is found. For samples with spheroidized Ge-particles before the equilibrium heat treatments at low temperature for 24 or 48 h, thermodynamic equilibrium was supposedly not achieved at temperatures below 723 K. Much longer heat treatments (tens of days) on the significantly finer as-cast microstructure allowed to reach equilibrium probably down to 600 K. Independently of whether thermodynamic equilibrium was reached or not the electrical conductivity and the density measurements yielded good agreement typically within a few tenth of percent of atomic Ge-concentration in solid solution in {alpha}-Ag for a given temperature. The results are close to, yet consistently slightly lower than, the values given by Owen and Rowland on which the current assessment of the solvus in the Ag-Ge binary is based. More recent results by Filipponi and co-workers are clearly not in agreement with the data presented here.

  5. Precise determination of HPGe detector efficiency for gamma spectrometry measurements of environmental samples with variable geometry and density

    Directory of Open Access Journals (Sweden)

    Barrera Manuel

    2017-03-01

    Full Text Available A methodology to determine the full energy peak efficiency (FEPE for precise gamma spectrometry measurements of environmental samples with high-purity germanium (HPGe detector, valid when this efficiency depends on the energy of the radiation E, the height of the cylindrical sample H, and its density ρ, is introduced. The methodology consists of an initial calibration as a function of E and H and the application of a self-attenuation factor, depending on the density of the sample ρ, in order to correct for the different attenuation of the generic sample in relation to the measured standard. The obtained efficiency can be used in the whole range of interest studied, E = 120–2000 keV, H = 1–5 cm, and ρ = 0.8–1.7 g/cm3, being its uncertainty below 5%. The efficiency has been checked by the measurement of standards, resulting in a good agreement between experimental and expected activities. The described methodology can be extended to similar situations when samples show geometric and compaction differences.

  6. Measurement of gamma-ray intensities of sup 2 sup 3 sup 1 Th using semiconductor detectors

    CERN Document Server

    Chatani, H

    1999-01-01

    Nuclide sup 2 sup 3 sup 1 Th was yielded by the sup 2 sup 3 sup 2 Th(n, 2n) reaction with neutron irradiation in the Kyoto University Reactor (KUR). Moreover, the thorium was purified chemically. Gamma-ray spectra of thorium have been measured using low-energy photon spectrometers and a high-purity germanium detector. Relative gamma-ray intensities ranging from 25 to 352 keV in the decay of sup 2 sup 3 sup 1 Th have been determined with satisfactory accuracy. The results are in very good agreement with those of earlier studies. We observe two new gamma-rays at 77.69 and 177.66 keV, whose intensities are found to be (0.063+-0.010)% and (0.00095+-0.00020)%, respectively, relative to that of 84.21 keV taken as 100%. Absolute intensity of 84.21 keV gamma-ray which is the most prominent one from the decay of sup 2 sup 3 sup 1 Th and that of 185.739 keV following the decay of sup 2 sup 3 sup 5 U are also determined from the secular equilibrium for sup 2 sup 3 sup 5 U- sup 2 sup 3 sup 1 Th. The results obtained in t...

  7. Multielement trace determination in high purity advanced ceramics and high purity metals

    Indian Academy of Sciences (India)

    R Matschat; H-J Heinrich; M Czerwensky; S Kuxenko; H Kipphardt

    2005-07-01

    In the field of advanced ceramics two CRMs were developed in the last few years by the Federal Institute for Materials Research and Testing, one for silicon nitride and one for silicon carbide. Besides their application by industry they are appropriate to be used for the validation of special methods used for trace determination in accordance with high purity materials. This is demonstrated, for example, on ultrapure silicon carbide which was analysed by solid sampling electrothermal atomic absorption spectrometry (SS ET AAS). BAM is also certifying primary pure reference materials used as the National Standards for inorganic analysis in Germany. The crucial point of this project is the certification of the total purity of high purity materials, each representing one element of the periodic table. A variety of different analytical methods was necessary to determine the trace contents of metallic and non-metallic impurities from almost the whole periodic table in the high purity materials. The primary CRMs of copper, iron and molybdenum are used as examples to demonstrate the modus operandi, analytical effects observed by using high resolution ICP mass spectrometry (HR ICP–MS) and the results.

  8. Promoting cell proliferation using water dispersible germanium nanowires.

    Directory of Open Access Journals (Sweden)

    Michael Bezuidenhout

    Full Text Available Group IV Nanowires have strong potential for several biomedical applications. However, to date their use remains limited because many are synthesised using heavy metal seeds and functionalised using organic ligands to make the materials water dispersible. This can result in unpredicted toxic side effects for mammalian cells cultured on the wires. Here, we describe an approach to make seedless and ligand free Germanium nanowires water dispersible using glutamic acid, a natural occurring amino acid that alleviates the environmental and health hazards associated with traditional functionalisation materials. We analysed the treated material extensively using Transmission electron microscopy (TEM, High resolution-TEM, and scanning electron microscope (SEM. Using a series of state of the art biochemical and morphological assays, together with a series of complimentary and synergistic cellular and molecular approaches, we show that the water dispersible germanium nanowires are non-toxic and are biocompatible. We monitored the behaviour of the cells growing on the treated germanium nanowires using a real time impedance based platform (xCELLigence which revealed that the treated germanium nanowires promote cell adhesion and cell proliferation which we believe is as a result of the presence of an etched surface giving rise to a collagen like structure and an oxide layer. Furthermore this study is the first to evaluate the associated effect of Germanium nanowires on mammalian cells. Our studies highlight the potential use of water dispersible Germanium Nanowires in biological platforms that encourage anchorage-dependent cell growth.

  9. Protective infrared antireflection coating based on sputtered germanium carbide

    Science.gov (United States)

    Gibson, Des; Waddell, Ewan; Placido, Frank

    2011-09-01

    This paper describes optical, durablility and environmental performance of a germanium carbide based durable antireflection coating. The coating has been demonstrated on germanium and zinc selenide infra-red material however is applicable to other materials such as zinc sulphide. The material is deposited using a novel reactive closed field magnetron sputtering technique, offering significant advantages over conventional evaporation processes for germanium carbide such as plasma enhanced chemical vapour deposition. The sputtering process is "cold", making it suitable for use on a wide range of substrates. Moreover, the drum format provide more efficient loading for high throughput production. The use of the closed field and unbalanced magnetrons creates a magnetic confinement that extends the electron mean free path leading to high ion current densities. The combination of high current densities with ion energies in the range ~30eV creates optimum thin film growth conditions. As a result the films are dense, spectrally stable, supersmooth and low stress. Films incorporate low hydrogen content resulting in minimal C-H absorption bands within critical infra-red passbands such as 3 to 5um and 8 to 12um. Tuning of germanium carbide (Ge(1-x)Cx) film refractive index from pure germanium (refractive index 4) to pure germanium carbide (refractive index 1.8) will be demonstrated. Use of film grading to achieve single and dual band anti-reflection performance will be shown. Environmental and durability levels are shown to be suitable for use in harsh external environments.

  10. Optical gain in single tensile-strained germanium photonic wire.

    Science.gov (United States)

    de Kersauson, M; El Kurdi, M; David, S; Checoury, X; Fishman, G; Sauvage, S; Jakomin, R; Beaudoin, G; Sagnes, I; Boucaud, P

    2011-09-12

    We have investigated the optical properties of tensile-strained germanium photonic wires. The photonic wires patterned by electron beam lithography (50 μm long, 1 μm wide and 500 nm thick) are obtained by growing a n-doped germanium film on a GaAs substrate. Tensile strain is transferred in the germanium layer using a Si₃N₄ stressor. Tensile strain around 0.4% achieved by the technique corresponds to an optical recombination of tensile-strained germanium involving light hole band around 1690 nm at room temperature. We show that the waveguided emission associated with a single tensile-strained germanium wire increases superlinearly as a function of the illuminated length. A 20% decrease of the spectral broadening is observed as the pump intensity is increased. All these features are signatures of optical gain. A 80 cm⁻¹ modal optical gain is derived from the variable strip length method. This value is accounted for by the calculated gain material value using a 30 band k · p formalism. These germanium wires represent potential building blocks for integration of nanoscale optical sources on silicon.

  11. Recent developments in semiconductor gamma-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Luke, Paul N.; Amman, Mark; Tindall, Craig; Lee, Julie S.

    2003-10-28

    The successful development of lithium-drifted Ge detectors in the 1960's marked the beginning of the significant use of semiconductor crystals for direct detection and spectroscopy of gamma rays. In the 1970's, high-purity Ge became available, which enabled the production of complex detectors and multi-detector systems. In the following decades, the technology of semiconductor gamma-ray detectors continued to advance, with significant developments not only in Ge detectors but also in Si detectors and room-temperature compound-semiconductor detectors. In recent years, our group at Lawrence Berkeley National Laboratory has developed a variety of gamma ray detectors based on these semiconductor materials. Examples include Ge strip detectors, lithium-drifted Si strip detectors, and coplanar-grid CdZnTe detectors. These advances provide new capabilities in the measurement of gamma rays, such as the ability to perform imaging and the realization of highly compact spectroscopy systems.

  12. Cell culture purity issues and DFAT cells.

    Science.gov (United States)

    Wei, Shengjuan; Bergen, Werner G; Hausman, Gary J; Zan, Linsen; Dodson, Michael V

    2013-04-12

    Dedifferentiation of mature adipocytes, in vitro, has been pursued/documented for over forty years. The subsequent progeny cells are named dedifferentiated adipocyte-derived progeny cells (DFAT cells). DFAT cells are proliferative and likely to possess mutilineage potential. As a consequence, DFAT cells and their progeny/daughter cells may be useful as a potential tool for various aspects of tissue engineering and as potential vectors for the alleviation of several disease states. Publications in this area have been increasing annually, but the purity of the initial culture of mature adipocytes has seldom been documented. Consequently, it is not always clear whether DFAT cells are derived from dedifferentiated mature (lipid filled) adipocytes or from contaminating cells that reside in an impure culture.

  13. Workshop on Preserving High Purity Uranium-233

    Energy Technology Data Exchange (ETDEWEB)

    Krichinsky, Alan M [ORNL; Giaquinto, Joseph [ORNL; Canaan, R Douglas {Doug} [ORNL

    2016-01-01

    A workshop was held on at the MARC X conference to provide a forum for the scientific community to communicate needs for high-purity 233U and its by-products in order to preserve critical items otherwise slated for downblending and disposal. Currently, only a small portion of the U.S. holdings of separated 233U is being preserved. However, many additional kilograms of 233U (>97% pure) still are destined to be downblended which will permanently destroy their potential value for many other applications. It is not likely that this material will ever be replaced due to a lack of operating production capability. Summaries of information conveyed at the workshop and feedback obtained from the scientific community are presented herein.

  14. Advanced Radiation Detector Development

    Energy Technology Data Exchange (ETDEWEB)

    The University of Michigan

    1998-07-01

    Since our last progress report, the project at The University of Michigan has continued to concentrate on the development of gamma ray spectrometers fabricated from cadmium zinc telluride (CZT). This material is capable of providing energy resolution that is superior to that of scintillation detectors, while avoiding the necessity for cooling associated with germanium systems. In our past reports, we have described one approach (the coplanar grid electrode) that we have used to partially overcome some of the major limitations on charge collection that is found in samples of CZT. This approach largely eliminates the effect of hole motion in the formation of the output signal, and therefore leads to pulses that depend only on the motion of a single carrier (electrons). Since electrons move much more readily through CZT than do holes, much better energy resolution can be achieved under these conditions. In our past reports, we have described a 1 cm cube CZT spectrometer fitted with coplanar grids that achieved an energy resolution of 1.8% from the entire volume of the crystal. This still represents, to our knowledge, the best energy resolution ever demonstrated in a CZT detector of this size.

  15. Separation and purification of no-carrier-added arsenic from bulk amounts of germanium for use in radiopharmaceutical labelling

    Energy Technology Data Exchange (ETDEWEB)

    Jahn, M.; Radchenko, V.; Roesch, F.; Jennewein, M. [Mainz Univ. (Germany). Inst. of Nuclear Chemsistry; Filosofov, D. [Joint Inst. for Nuclear Research, Dubna (Russian Federation). Lab. of Nuclear Problems; Hauser, H.; Eisenhut, M. [Deutsches Krebsforschungszentrum, Heidelberg (Germany). Radiopharmaceutical Chemistry

    2010-07-01

    Radioarsenic labelled radiopharmaceuticals could add special features to molecular imaging with positron emission tomography (PET). For example the long physical half-lives of {sup 72}As (T{sub 1/2}=26 h) and {sup 74}As (T{sub 1/2}=17.8 d) in conjunction with their high positron branching rates of 88% and 29%, respectively, allow the investigation of slow physiological or metabolical processes, like the enrichment and biodistribution of monoclonal antibodies in tumour tissue or the characterization of stem cell trafficking. A method for separation and purification of no-carrier-added (nca) arsenic from irradiated metallic germanium targets based on distillation and anion exchange is developed. It finally converts the arsenic into an {sup *}As(III) synthon in PBS buffer and pH 7 suitable for labelling of proteins via As-S bond formations. The method delivers radioarsenic in high purity with separation factors of 10{sup 6} from germanium and an overall yield from target to labelling synthon of > 40%. In a proof-of-principle experiment, the monoclonal antibody Bevacizumab, directed against the human VEGF receptor, was labelled with a radiochemical yield > 90% within 1 h at room temperature with nca {sup 72/74/77}As. (orig.)

  16. Conditions for strictly purity-decreasing quantum Markovian dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Lidar, D.A. [Chemical Physics Theory Group, Chemistry Department and Center for Quantum Information and Quantum Control, University of Toronto, 80 St. George St., Toronto, Ont., M5S 3H6 (Canada)], E-mail: lidar@usc.edu; Shabani, A. [Physics Department and Center for Quantum Information and Quantum Control, University of Toronto, 60 St. George St., Toronto, Ont., M5S 1A7 (Canada); Alicki, R. [Institute of Theoretical Physics and Astrophysics, University of Gdansk (Poland)

    2006-03-06

    The purity, Tr({rho} {sup 2}), measures how pure or mixed a quantum state {rho} is. It is well known that quantum dynamical semigroups that preserve the identity operator (which we refer to as unital) are strictly purity-decreasing transformations. Here, we provide an almost complete characterization of the class of strictly purity-decreasing quantum dynamical semigroups. We show that in the case of finite-dimensional Hilbert spaces, a dynamical semigroup is strictly purity-decreasing if and only if it is unital, while in the infinite dimensional case, unitality is only sufficient.

  17. Germanium separation and purification by leaching and precipitation

    Institute of Scientific and Technical Information of China (English)

    Saeid Bayat; Sajjad Aghazadeh; Mohammad Noaparast; Mahdi Gharabaghi; Behrooz Taheri

    2016-01-01

    In this research work, extraction and purification of germanium from zinc leach residues (ZLR) were investigated. The results of ICP, XRF, and atomic adsorption spectroscopy (AAS) tests show that contents of germanium, iron, lead, and zinc within the leaching residue were 105×10−6, 3.53%, 10.35%, and 8.8%, respectively. XRD results indicate that the main minerals were in different forms of sulfates (CaSO4·2H2O, PbSO4 and ZnSO4·6H2O), silicate (SiO2), and oxide (Fe2O3). Dissolution of leaching filter cake was carried out using 5 parameters and each in 4 levels (acid concentration, temperature, time, liquid-to-solid ratio, and stirring speed) by Taguchi method (L16), and then optimization of the effective parameters by response surface method. Under optimum conditions, zinc and germanium dissolution efficiencies were 88.71% and 8%, respectively. Leaching tests with sulfuric acid (added di-ammonium oxalate monohydrate) and hydrochloric acid (HCl) on the residues obtained from previous-stage sulfuric acid dissolution, yielded germanium and iron recoveries of 83%, 88%, 40%, and 90%, respectively. Thus, leaching experiment with sulfuric acid (added di-ammonium oxalate monohydrate) was superior to that with hydrochloric acid due to high and low extraction amounts of germanium and iron, respectively. Precipitation experiments revealed that germanium purification with tannic acid presented a better result compared to sodium hydroxide and ammonia. Under optimum conditions, contents of germanium and iron in the solution after precipitation were 0.1505% and 14.7% with precipitation yields of 91% and 52%, respectively.

  18. Enhanced shower formation in aligned thick germanium crystals and discrimination against charged hadrons

    Energy Technology Data Exchange (ETDEWEB)

    Baurichter, A. [Aarhus Univ. (Denmark). Inst. for Synchrotron Radiat.; Kirsebom, K. [Aarhus Univ. (Denmark). Inst. for Synchrotron Radiat.; Medewaldt, R. [Aarhus Univ. (Denmark). Inst. for Synchrotron Radiat.; Mikkelsen, U. [Aarhus Univ. (Denmark). Inst. for Synchrotron Radiat.; Moeller, S. [Aarhus Univ. (Denmark). Inst. for Synchrotron Radiat.; Uggerhoej, E. [Aarhus Univ. (Denmark). Inst. for Synchrotron Radiat.; Worm, T. [Aarhus Univ. (Denmark). Inst. for Synchrotron Radiat.; Elsener, K. [European Organization for Nuclear Research, Geneva (Switzerland); Ballestrero, S. [Dipartimento di Fisica, University of Florence and INFN Sezione di Firenze, Largo E. Fermi 2, 50125 Florence (Italy); Sona, P. [Dipartimento di Fisica, University of Florence and INFN Sezione di Firenze, Largo E. Fermi 2, 50125 Florence (Italy); Romano, J. [Dipartimento di Fisica, University La Sapienza-Rome and INFN Sezione di Roma, P.le A. Moro 5, 00185 Rome (Italy)

    1995-11-01

    The distribution of the energy released in a thin silicon detector placed on the downstream side of a thick germanium single crystal bombarded with a 150 GeV electron or pion beam along directions close to the left angle 110 right angle axis or along random directions has been investigated. In view of a possible application to very high energy gamma ray astronomy and particle physics, the intrinsic capability of such a device to reject, on the basis of energy discrimination, unwanted events due to charged hadrons together with the resulting loss of efficiency for the detection of showers initiated by high energy electrons, is determined as a function of the chosen energy threshold. (orig.).

  19. A Low Noise 64x64 Germanium Array for Far IR Astronomy Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develope a 64x64 far infrared germanium focal-plane array with the following key design features: 1- Four top-illuminated, 32x32 germanium sub-arrays...

  20. Anisotropic Optical Properties of Layered Germanium Sulfide

    CERN Document Server

    Tan, Dezhi; Wang, Feijiu; Mohamed, Nur Baizura; Mouri, Shinichiro; Sandhaya, Koirala; Zhang, Wenjing; Miyauchi, Yuhei; Ohfuchi, Mari; Matsuda, Kazunari

    2016-01-01

    Two-dimensional (2D) layered materials, transition metal dichalcogenides and black phosphorus, have attracted much interest from the viewpoints of fundamental physics and device applications. The establishment of new functionalities in anisotropic layered 2D materials is a challenging but rewarding frontier, owing to their remarkable optical properties and prospects for new devices. Here, we report the anisotropic optical properties of layered 2D monochalcogenide of germanium sulfide (GeS). Three Raman scattering peaks corresponding to the B3g, A1g, and A2g modes with strong polarization dependence are demonstrated in the GeS flakes, which validates polarized Raman spectroscopy as an effective method for identifying the crystal orientation of anisotropic layered GeS. Photoluminescence (PL) is observed with a peak at around 1.66 eV that originates from the direct optical transition in GeS at room temperature. Moreover, determination of the polarization dependent characteristics of the PL and absorption reveals...

  1. Hydrogen Bonding in Hydrogenated Amorphous Germanium

    Institute of Scientific and Technical Information of China (English)

    M.S.Abo-Ghazala; S. Al Hazmy

    2004-01-01

    Thin films of hydrogenated amorphous germanium (a-Ge:H) were prepared by radio frequency glow discharge deposition at various substrate temperatures. The hydrogen distribution and bonding structure in a-Ge:H were discussed based on infrared absorption data. The correlation between infrared absorption spectra and hydrogen effusion measurements was used to determine the proportionality constant for each vibration mode of the Ge-H bonds. The results reveal that the bending mode appearing at 835 cm?1 is associated with the Ge-H2 (dihydride) groups on the internal surfaces of voids. While 1880 cm?1 is assigned to vibrations of Ge-H (monohydride) groups in the bulk, the 2000 cm?1 stretching mode is attributed to Ge-H and Ge-H2 bonds located on the surfaces of voids. For films associated with bending modes in the infrared spectra, the proportionality constant values of the stretching modes near 1880 and 2000 cm?1 are found to be lower than those of films which had no corresponding bending modes.

  2. Reaction studies of hot silicon, germanium and carbon atoms

    Energy Technology Data Exchange (ETDEWEB)

    Gaspar, P.P.

    1990-11-01

    The goal of this project was to increase the authors understanding of the interplay between the kinetic and electronic energy of free atoms and their chemical reactivity by answering the following questions: (1) what is the chemistry of high-energy carbon silicon and germanium atoms recoiling from nuclear transformations; (2) how do the reactions of recoiling carbon, silicon and germanium atoms take place - what are the operative reaction mechanisms; (3) how does the reactivity of free carbon, silicon and germanium atoms vary with energy and electronic state, and what are the differences in the chemistry of these three isoelectronic atoms This research program consisted of a coordinated set of experiments capable of achieving these goals by defining the structures, the kinetic and internal energy, and the charge states of the intermediates formed in the gas-phase reactions of recoiling silicon and germanium atoms with silane, germane, and unsaturated organic molecules, and of recoiling carbon atoms with aromatic molecules. The reactions of high energy silicon, germanium, and carbon atoms created by nuclear recoil were studied with substrates chosen so that their products illuminated the mechanism of the recoil reactions. Information about the energy and electronic state of the recoiling atoms at reaction was obtained from the variation in end product yields and the extent of decomposition and rearrangement of primary products (usually reactive intermediates) as a function of total pressure and the concentration of inert moderator molecules that remove kinetic energy from the recoiling atoms and can induce transitions between electronic spin states. 29 refs.

  3. Germanium, Arsenic, and Selenium Abundances in Metal-Poor Stars

    CERN Document Server

    Roederer, Ian U

    2012-01-01

    The elements germanium (Ge, Z=32), arsenic (As, Z=33), and selenium (Se, Z=34) span the transition from charged-particle or explosive synthesis of the iron-group elements to neutron-capture synthesis of heavier elements. Among these three elements, only the chemical evolution of germanium has been studied previously. Here we use archive observations made with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope and observations from several ground-based facilities to study the chemical enrichment histories of seven stars with metallicities -2.6 < [Fe/H] < -0.4. We perform a standard abundance analysis of germanium, arsenic, selenium, and several other elements produced by neutron-capture reactions. When combined with previous derivations of germanium abundances in metal-poor stars, our sample reveals an increase in the [Ge/Fe] ratios at higher metallicities. This could mark the onset of the weak s-process contribution to germanium. In contrast, the [As/Fe] and [Se/Fe] ratios rema...

  4. CASCADES: An Ultra-Low-Background Germanium Crystal Array at Pacific Northwest National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Keillor, Martin E.; Aalseth, Craig E.; Day, Anthony R.; Erikson, Luke E.; Fast, James E.; Glasgow, Brian D.; Hoppe, Eric W.; Hossbach, Todd W.; Hyronimus, Brian J.; Miley, Harry S.; Myers, Allan W.; Seifert, Allen; Stavenger, Timothy J.

    2011-07-14

    State-of-the-art treaty verification techniques, environmental surveillance, and physics experiments require increased sensitivity for detecting and quantifying radionuclides of interest. This can be accomplished with new detector designs that establish high detection efficiency and reduced instrument backgrounds. Current research is producing an intrinsic germanium (HPGe) array designed for high detection efficiency, ultra-low-background performance, and sensitive {gamma}-{gamma} coincidence detection. The system design is optimized to accommodate filter paper samples, e.g., samples collected by the Radionuclide Aerosol Sampler/Analyzer. The system will provide high sensitivity for weak collections on atmospheric filter samples (e.g., < 10{sup 5} fissions), as well as offering the potential to gather additional information from higher activity filters using gamma cascade coincidence detection. The first of two HPGe crystal arrays in ultra-low-background vacuum cryostats has been assembled, with the second in progress. Traditional methods for constructing ultra-low-background detectors were followed, including use of materials known to be low in radioactive contaminants, use of ultra-pure reagents, and clean room assembly. The cryostat is constructed mainly from copper electroformed into near-final geometry at Pacific Northwest National Laboratory. Details of the detector assembly and initial background and spectroscopic measurement results are presented; also a description of the custom analysis package used by this project is given.

  5. A dual-PIXE tomography setup for reconstruction of Germanium in ICF target

    Science.gov (United States)

    Guo, N.; Lu, H. Y.; Wang, Q.; Meng, J.; Gao, D. Z.; Zhang, Y. J.; Liang, X. X.; Zhang, W.; Li, J.; Ma, X. J.; Shen, H.

    2017-08-01

    Inertial Confinement Fusion (ICF) is one type of fusion energy research which could initiate nuclear fusion reactions through heating and compressing thermonuclear fuel. Compared to a pure plastic target, Germanium doping into the CH ablator layer by Glow Discharge Polymer (GDP) technique can increase the ablation velocity and the standoff distance between the ablation front and laser-deposition region. During target fabrication process, quantitative doping of Ge should be accurately controlled. Particle Induced X-ray Emission Tomography (PIXE-T) can make not only quantification of the concentration, but also reconstruction of the spatial distribution of doped element. The Si (Li) detector for PIXE tomography technique had a disadvantage of low counting rate. To make up this deficiency, another detector of Si (Li) with the same configuration positioned at the opposite side with the same detective angle 135° have been implemented. Simultaneously acquired elemental maps of Ge obtained using two detectors may be different because of the X-ray absorption along the X-ray exit route in the target. In this paper, the X-ray detection efficiency is drastically improved by this dual-PIXE tomography system.

  6. Fashion Brand Purity and Firm Performance

    Directory of Open Access Journals (Sweden)

    Jin-hui Zheng

    2013-01-01

    Full Text Available A large number of prior empirical research and case studies used qualitative methodology to discuss the fashion brand dilution resulting from consumer base extension from the target group(s to the nontarget groups and its impacts. From a different perspective, this paper establishes a dynamic brand dilution and performance model, demonstrating how dynamic changes of sales volumes involving the two consumer groups affect the degree of brand dilution and the performance of the brand. We incorporate the factor “brand purity” to the model as a quantitative measure of brand dilution level that affects firm annual revenue and profit change comprehensively in iteration. Our model suggests that fashion brands, especially luxury brands, can be easily diluted under the pressure of firm growth, and the brands suffer the significant negative impact on their revenues and profit. While increasing sales volume can aggravate the negative consequences, brand purity can be increased through limiting the consumer base to the target group only.

  7. Dynamic shear deformation in high purity Fe

    Energy Technology Data Exchange (ETDEWEB)

    Cerreta, Ellen K [Los Alamos National Laboratory; Bingert, John F [Los Alamos National Laboratory; Trujillo, Carl P [Los Alamos National Laboratory; Lopez, Mike F [Los Alamos National Laboratory; Gray, George T [Los Alamos National Laboratory

    2009-01-01

    The forced shear test specimen, first developed by Meyer et al. [Meyer L. et al., Critical Adiabatic Shear Strength of Low Alloyed Steel Under Compressive Loading, Metallurgical Applications of Shock Wave and High Strain Rate Phenomena (Marcel Decker, 1986), 657; Hartmann K. et al., Metallurgical Effects on Impact Loaded Materials, Shock Waves and High Strain rate Phenomena in Metals (Plenum, 1981), 325-337.], has been utilized in a number of studies. While the geometry of this specimen does not allow for the microstructure to exactly define the location of shear band formation and the overall mechanical response of a specimen is highly sensitive to the geometry utilized, the forced shear specimen is useful for characterizing the influence of parameters such as strain rate, temperature, strain, and load on the microstructural evolution within a shear band. Additionally, many studies have utilized this geometry to advance the understanding of shear band development. In this study, by varying the geometry, specifically the ratio of the inner hole to the outer hat diameter, the dynamic shear localization response of high purity Fe was examined. Post mortem characterization was performed to quantify the width of the localizations and examine the microstructural and textural evolution of shear deformation in a bcc metal. Increased instability in mechanical response is strongly linked with development of enhanced intergranular misorientations, high angle boundaries, and classical shear textures characterized through orientation distribution functions.

  8. Temporal Purity and Quantum Interference of Single Photons from Two Independent Cold Atomic Ensembles

    Science.gov (United States)

    Qian, Peng; Gu, Zhenjie; Cao, Rong; Wen, Rong; Ou, Z. Y.; Chen, J. F.; Zhang, Weiping

    2016-07-01

    The temporal purity of single photons is crucial to the indistinguishability of independent photon sources for the fundamental study of the quantum nature of light and the development of photonic technologies. Currently, the technique for single photons heralded from time-frequency entangled biphotons created in nonlinear crystals does not guarantee the temporal-quantum purity, except using spectral filtering. Nevertheless, an entirely different situation is anticipated for narrow-band biphotons with a coherence time far longer than the time resolution of a single-photon detector. Here we demonstrate temporally pure single photons with a coherence time of 100 ns, directly heralded from the time-frequency entangled biphotons generated by spontaneous four-wave mixing in cold atomic ensembles, without any supplemented filters or cavities. A near-perfect purity and indistinguishability are both verified through Hong-Ou-Mandel quantum interference using single photons from two independent cold atomic ensembles. The time-frequency entanglement provides a route to manipulate the pure temporal state of the single-photon source.

  9. 10 CFR 36.63 - Pool water purity.

    Science.gov (United States)

    2010-01-01

    ... § 36.63 Pool water purity. (a) Pool water purification system must be run sufficiently to maintain the conductivity of the pool water below 20 microsiemens per centimeter under normal circumstances. If pool water... 10 Energy 1 2010-01-01 2010-01-01 false Pool water purity. 36.63 Section 36.63 Energy...

  10. Determination of continuous variable entanglement by purity measurements

    CERN Document Server

    Adesso, G; Illuminati, F; Adesso, Gerardo; Serafini, Alessio; Illuminati, Fabrizio

    2004-01-01

    We classify the entanglement of two-mode Gaussian states according to their degree of total and partial mixedness. We derive exact bounds that determine maximally and minimally entangled states for fixed global and marginal purities. This characterization allows for an experimentally reliable estimate of continuous variable entanglement based on purity measurements.

  11. Determination of continuous variable entanglement by purity measurements.

    Science.gov (United States)

    Adesso, Gerardo; Serafini, Alessio; Illuminati, Fabrizio

    2004-02-27

    We classify the entanglement of two-mode Gaussian states according to their degree of total and partial mixedness. We derive exact bounds that determine maximally and minimally entangled states for fixed global and marginal purities. This characterization allows for an experimentally reliable estimate of continuous variable entanglement based on measurements of purity.

  12. Analysis of the Purity of Cetrimide by Titrations

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Rasmussen, Claus/Dallerup; Nielsen, Hans/Boye

    2006-01-01

    The purity of cetrimide, trimethyl tetradecyl ammonium bromide (TTAB), that is an important preservative of many cosmetic and pharmaceutical products, was determined by three independent methods of titration. Traditionally, cetrimide was analysed by an assay method of the European Pharmacopoeia (Ph....... Eur.), which showed consistently a low purity of cetrimide with large standard deviations associated, however. A systematic 3% bias of the Ph. Eur. assay method was identified by comparing the result with results of two alternative methods of titration that exhibited high precision and high accuracy....... Titration by perchloric acid showed a 99.69 ± 0.05 % purity of cetrimide and titration by silver nitrate showed a 99.85% ± 0.05 % purity while the traditional assay method predicted a purity of only 97.1 ± 0.4. It was found that the discrepancy could be identified as differences in selectivity during...

  13. Production of ultrahigh purity copper using waste copper nitrate solution.

    Science.gov (United States)

    Choi, J Y; Kim, D S

    2003-04-25

    The production of ultrahigh purity copper (99.9999%) by electrolysis in the presence of a cementation barrier has been attempted employing a waste nitric copper etching solution as the electrolyte. The amount of copper deposited on the cathode increased almost linearly with electrolysis time and the purity of copper was observed to increase as the electrolyte concentration was increased. At some point, however, as the electrolyte concentration increased, the purity of copper decreased slightly. As the total surface area of cementation barrier increased, the purity of product increased. The electrolyte temperature should be maintained below 35 degrees C in the range of investigated electrolysis conditions to obtain the ultrahigh purity copper. Considering that several industrial waste solutions contain valuable metallic components the result of present study may support a claim that electrowinning is a very desirable process for their treatment and recovery.

  14. Measurement of nuclear activity with Ge detectors and its uncertainty

    CERN Document Server

    Cortes, C A P

    1999-01-01

    presented in the fifth chapter and they are applied to establish the optimum conditions for the measurement of the activity of a gamma transmitter isolated radioactive source with a spectrometer with germanium detector. (Author) The objective of this work is to analyse the influence magnitudes which affect the activity measurement of gamma transmitter isolated radioactive sources. They prepared by means of the gravimetric method, as well as, determining the uncertainty of such measurement when this is carried out with a gamma spectrometer system with a germanium detector. This work is developed in five chapters: In the first one, named Basic principles it is made a brief description about the meaning of the word Measurement and its implications and the necessaries concepts are presented which are used in this work. In the second chapter it is exposed the gravimetric method used for the manufacture of the gamma transmitter isolated radioactive sources, it is tackled the problem to determine the main influence ...

  15. Graphene-like monolayer low-buckled honeycomb germanium film

    Science.gov (United States)

    He, Yezeng; Luo, Haibo; Li, Hui; Sui, Yanwei; Wei, Fuxiang; Meng, Qingkun; Yang, Weiming; Qi, Jiqiu

    2017-04-01

    Molecular dynamics simulations have been performed to study the cooling process of two-dimensional liquid germanium under nanoslit confinement. The results clearly indicates that the liquid germanium undergoes an obvious liquid-solid phase transition to a monolayer honeycomb film with the decrease of temperature, accompanying the rapid change in potential energy, atomic volume, coordination number and lateral radial distribution function. During the solidification process, some hexagonal atomic islands first randomly emerge in the disordered liquid film and then grow up to stable crystal grains which keep growing and finally connect together to form a honeycomb polycrystalline film. It is worth noting that the honeycomb germanium film is low-buckled, quite different from the planar graphene.

  16. Next Generation Device Grade Silicon-Germanium on Insulator

    Science.gov (United States)

    Littlejohns, Callum G.; Nedeljkovic, Milos; Mallinson, Christopher F.; Watts, John F.; Mashanovich, Goran Z.; Reed, Graham T.; Gardes, Frederic Y.

    2015-02-01

    High quality single crystal silicon-germanium-on-insulator has the potential to facilitate the next generation of photonic and electronic devices. Using a rapid melt growth technique we engineer tailored single crystal silicon-germanium-on-insulator structures with near constant composition over large areas. The proposed structures avoid the problem of laterally graded SiGe compositions, caused by preferential Si rich solid formation, encountered in straight SiGe wires by providing radiating elements distributed along the structures. This method enables the fabrication of multiple single crystal silicon-germanium-on-insulator layers of different compositions, on the same Si wafer, using only a single deposition process and a single anneal process, simply by modifying the structural design and/or the anneal temperature. This facilitates a host of device designs, within a relatively simple growth environment, as compared to the complexities of other methods, and also offers flexibility in device designs within that growth environment.

  17. Thin Film Electrodes for Rare Event Detectors

    Science.gov (United States)

    Odgers, Kelly; Brown, Ethan; Lewis, Kim; Giordano, Mike; Freedberg, Jennifer

    2017-01-01

    In detectors for rare physics processes, such as neutrinoless double beta decay and dark matter, high sensitivity requires careful reduction of backgrounds due to radioimpurities in detector components. Ultra pure cylindrical resistors are being created through thin film depositions onto high purity substrates, such as quartz glass or sapphire. By using ultra clean materials and depositing very small quantities in the films, low radioactivity electrodes are produced. A new characterization process for cylindrical film resistors has been developed through analytic construction of an analogue to the Van Der Pauw technique commonly used for determining sheet resistance on a planar sample. This technique has been used to characterize high purity cylindrical resistors ranging from several ohms to several tera-ohms for applications in rare event detectors. The technique and results of cylindrical thin film resistor characterization will be presented.

  18. Germanium, Arsenic, and Selenium Abundances in Metal-poor Stars

    Science.gov (United States)

    Roederer, Ian U.

    2012-09-01

    The elements germanium (Ge, Z = 32), arsenic (As, Z = 33), and selenium (Se, Z = 34) span the transition from charged-particle or explosive synthesis of the iron-group elements to neutron-capture synthesis of heavier elements. Among these three elements, only the chemical evolution of germanium has been studied previously. Here we use archive observations made with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope and observations from several ground-based facilities to study the chemical enrichment histories of seven stars with metallicities -2.6 Prochaska).This paper includes data taken at The McDonald Observatory of The University of Texas at Austin.

  19. Tensile-strained germanium microdisks with circular Bragg reflectors

    Science.gov (United States)

    El Kurdi, M.; Prost, M.; Ghrib, A.; Elbaz, A.; Sauvage, S.; Checoury, X.; Beaudoin, G.; Sagnes, I.; Picardi, G.; Ossikovski, R.; Boeuf, F.; Boucaud, P.

    2016-02-01

    We demonstrate the combination of germanium microdisks tensily strained by silicon nitride layers and circular Bragg reflectors. The microdisks with suspended lateral Bragg reflectors form a cavity with quality factors up to 2000 around 2 μm. This represents a key feature to achieve a microlaser with a quasi-direct band gap germanium under a 1.6% biaxial tensile strain. We show that lowering the temperature significantly improves the quality factor of the quasi-radial modes. Linewidth narrowing is observed in a range of weak continuous wave excitation powers. We finally discuss the requirements to achieve lasing with these kind of structures.

  20. Comparative infrared study of silicon and germanium nitrides

    Science.gov (United States)

    Baraton, M. I.; Marchand, R.; Quintard, P.

    1986-03-01

    Silicon and germanium nitride (Si 3N 4 and Ge 3N 4) are isomorphic compounds. They have been studied in the β-phase which crystallises in the hexagonal system. The space group is P6 3/m (C 6h2). The IR transmission spectra of these two nitrides are very similar but the absorption frequencies of germanium nitride are shifted to the lower values in comparison with silicon nitride. We noted that the atomic mass effect is the only cause of this shift for the streching modes but not for the bending modes.

  1. Alpha particle response study of polycrstalline diamond radiation detector

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Amit; Topkar, Anita [Electronics Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085 (India)

    2016-05-23

    Chemical vapor deposition has opened the possibility to grow high purity synthetic diamond at relatively low cost. This has opened up uses of diamond based detectors for wide range of applications. These detectors are most suitable for harsh environments where standard semiconductor detectors cannot work. In this paper, we present the fabrication details and performance study of polycrystalline diamond based radiation detector. Effect of different operating parameters such as bias voltage and shaping time for charge collection on the performance of detector has been studied.

  2. Thermal control of the GRASP detector section

    Science.gov (United States)

    Roig, P. B.

    1988-12-01

    The necessity of keeping GRASP telescope (Gamma Ray Astronomy with Spectroscopy and Positioning) detectors at working temperatures within an adequate range (85 + or - 15 K for the germanium and 283 + or - 20 K for CsI) is discussed. Thermal control based in cryogenic liquid tanks is not considered the most suitable solution because of mass and lifetime considerations. Instead of this conventional solution, a concept using a combination of passive and active cooling systems was chosen. It combines the features of a corrugated radiator panel, thermal shields, MLI blankets, and an extra cooling system based on the Stirling cycle engine.

  3. State-independent purity and fidelity of quantum operations

    Science.gov (United States)

    Kong, Fan-Zhen; Zong, Xiao-Lan; Yang, Ming; Cao, Zhuo-Liang

    2016-04-01

    The purity and fidelity of quantum operations are of great importance in characterizing the quality of quantum operations. The currently available definitions of the purity and fidelity of quantum operations are based on the average over all possible input pure quantum states, i.e. they are state-dependent (SD). In this paper, without resorting to quantum states, we define the state-independent (SI) purity and fidelity of a general quantum operation (evolution) in virtue of a new density matrix formalism for quantum operations, which is extended from the quantum state level to quantum operation level. The SI purity and fidelity gain more intrinsic physical properties of quantum operations than state-dependent ones, such as the purity of a one-qubit amplitude damping channel (with damping rate 1) is 1/2, which is in line with the fact that the channel is still a nonunitary operation described by two Kraus operators rather than a unitary one. But the state-dependent Haar average purity is 1 in this case. So the SI purity and fidelity proposed here can help the experimentalists to exactly quantify the implementation quality of an operation. As a byproduct, a new measure of the operator entanglement is proposed for a quantum evolution (unitary or nonunitary) in terms of the linear entropy of its density matrix on the orthonormal operator bases (OOBs) in Hilbert-Schmidt space.

  4. Euromet action 428: transfer of ge detectors efficiency calibration from point source geometry to other geometries; Action euromet 428: transfert de l'etalonnage en rendement de detecteurs au germanium pour une source ponctuelle vers d'autres geometries

    Energy Technology Data Exchange (ETDEWEB)

    Lepy, M.Ch

    2000-07-01

    The EUROMET project 428 examines efficiency transfer computation for Ge gamma-ray spectrometers when the efficiency is known for a reference point source geometry in the 60 keV to 2 MeV energy range. For this, different methods are used, such as Monte Carlo simulation or semi-empirical computation. The exercise compares the application of these methods to the same selected experimental cases to determine the usage limitations versus the requested accuracy. For carefully examining these results and trying to derive information for improving the computation codes, this study was limited to a few simple cases, from an experimental efficiency calibration for point source at 10-cm source-to-detector distance. The first part concerns the simplest case of geometry transfer, i.e., using point sources for 3 source-to-detector distances: 2,5 and 20 cm; the second part deals with transfer from point source geometry to cylindrical geometry with three different matrices. The general results show that the deviations between the computed results and the measured efficiencies are for the most part within 10%. The quality of the results is rather inhomogeneous and shows that these codes cannot be used directly for metrological purposes. However, most of them are operational for routine measurements when efficiency uncertainties of 5-10% can be sufficient. (author)

  5. Radiation detectors: needs and prospects

    Energy Technology Data Exchange (ETDEWEB)

    Armantrout, G.A.

    1981-01-01

    Important applications for x- and ..gamma..-ray spectroscopy are found in prospecting, materials characterization, environmental monitoring, the life sciences, and nuclear physics. The specific requirements vary for each application with varying degrees of emphasis on either spectrometer resolution, detection efficiency, or both. Since no one spectrometer is ideally suited to this wide range of needs, compromises are usually required. Gas and scintillation spectrometers have reached a level of maturity, and recent interest has concentrated on semiconductor spectrometers. Germanium detectors are showing continuing refinement and are the spectrometers of choice for high resolution applications. The new high-Z semiconductors, such as CdTe and HgI/sub 2/, have shown steady improvement but are limited in both resolution and size and will likely be used only in applications which require their unique properties.

  6. Novel approach for n-type doping of HVPE gallium nitride with germanium

    Science.gov (United States)

    Hofmann, Patrick; Krupinski, Martin; Habel, Frank; Leibiger, Gunnar; Weinert, Berndt; Eichler, Stefan; Mikolajick, Thomas

    2016-09-01

    We present a novel method for germanium doping of gallium nitride by in-situ chlorination of solid germanium during the hydride vapour phase epitaxy (HVPE) process. Solid germanium pieces were placed in the doping line with a hydrogen chloride flow directed over them. We deduce a chlorination reaction taking place at 800 ° C , which leads to germanium chloroform (GeHCl3) or germanium tetrachloride (GeCl4). The reactor shows a germanium rich residue after in-situ chlorination experiments, which can be removed by hydrogen chloride etching. All gallium nitride crystals exhibit n-type conductivity, which shows the validity of the in-situ chlorination of germanium for doping. A complex doping profile is found for each crystal, which was assigned to a combination of localised supply of the dopant and sample rotation during growth and switch-off effects of the HVPE reactor.

  7. Detector Unit

    CERN Multimedia

    1960-01-01

    Original detector unit of the Instituut voor Kernfysisch Onderzoek (IKO) BOL project. This detector unit shows that silicon detectors for nuclear physics particle detection were already developed and in use in the 1960's in Amsterdam. Also the idea of putting 'strips' onto the silicon for high spatial resolution of a particle's impact on the detector were implemented in the BOL project which used 64 of these detector units. The IKO BOL project with its silicon particle detectors was designed, built and operated from 1965 to roughly 1977. Detector Unit of the BOL project: These detectors, notably the ‘checkerboard detector’, were developed during the years 1964-1968 in Amsterdam, The Netherlands, by the Natuurkundig Laboratorium of the N.V. Philips Gloeilampen Fabrieken. This was done in close collaboration with the Instituut voor Kernfysisch Onderzoek (IKO) where the read-out electronics for their use in the BOL Project was developed and produced.

  8. Infrared detectors

    CERN Document Server

    Rogalski, Antonio

    2010-01-01

    This second edition is fully revised and reorganized, with new chapters concerning third generation and quantum dot detectors, THz detectors, cantilever and antenna coupled detectors, and information on radiometry and IR optics materials. Part IV concerning focal plane arrays is significantly expanded. This book, resembling an encyclopedia of IR detectors, is well illustrated and contains many original references … a really comprehensive book.-F. Sizov, Institute of Semiconductor Physics, National Academy of Sciences, Kiev, Ukraine

  9. Linear polarization sensitivity of SeGA detectors

    CERN Document Server

    Miller, D; Moeller, V; Starosta, K; Vaman, C; Weisshaar, D

    2006-01-01

    Parity is a key observable in nuclear spectroscopy. Linear polarization measurements of $\\gamma$-rays are a probe to access the parities of energy levels. Utilizing the segmentation of detectors in the Segmented Germanium Array (SeGA) at the NSCL and analyzing the positions of interaction therein allows the detectors to be used as Compton polarimeters. Unlike other segmented detectors, SeGA detectors are irradiated from the side to utilize the transversal segmentation for better Doppler corrections. Sensitivity in such an orientation has previously been untested. A linear polarization sensitivity $Q \\approx 0.14$ has been measured in the 350-keV energy range for SeGA detectors using $\\alpha$-$\\gamma$ correlations from a \

  10. Direct observations of the vacancy and its annealing in germanium

    DEFF Research Database (Denmark)

    Slotte, J.; Kilpeläinen, S.; Tuomisto, F.

    2011-01-01

    Weakly n-type doped germanium has been irradiated with protons up to a fluence of 3×1014 cm-2 at 35 K and 100 K in a unique experimental setup. Positron annihilation measurements show a defect lifetime component of 272±4 ps at 35 K in in situ positron lifetime measurements after irradiation at 100...

  11. Discovery of Gallium, Germanium, Lutetium, and Hafnium Isotopes

    CERN Document Server

    Gross, J L

    2011-01-01

    Currently, twenty-eight gallium, thirty-one germanium, thirty-five lutetium, and thirty-six hafnium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  12. Composite germanium monochromators - results for the TriCS

    Energy Technology Data Exchange (ETDEWEB)

    Schefer, J.; Fischer, S.; Boehm, M.; Keller, L.; Horisberger, M.; Medarde, M.; Fischer, P. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    Composite germanium monochromators are in the beginning of their application in neutron diffraction. We show here the importance of the permanent quality control with neutrons on the example of the 311 wafers which will be used on the single crystal diffractometer TriCS at SINQ. (author) 2 figs., 3 refs.

  13. Noise and oscillations in gold-doped germanium photodiodes

    NARCIS (Netherlands)

    Bolwijn, P.T.; Rijst, C. v. d.; Ast, W.G. van; Lam, T.

    1967-01-01

    Considerable noise effects in excess of shot noise and oscillations found in commercially available, gold-doped germanium photodiodes have been investigated. The noise and oscillation effects occur in the photocurrent of reversely biased diodes at temperatures below about 100°K. The dependence of th

  14. Differential Diode Laser Sensor for High-Purity Oxygen Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A compact portable sensor for determining the purity of oxygen concentrations near 100 percent is proposed based on differential absorption of two beams from a diode...

  15. Highly Accurate Sensor for High-Purity Oxygen Determination Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this STTR effort, Los Gatos Research (LGR) and the University of Wisconsin (UW) propose to develop a highly-accurate sensor for high-purity oxygen determination....

  16. Determination of Purity by Differential Scanning Calorimetry (DSC).

    Science.gov (United States)

    Brown, M. E.

    1979-01-01

    An exercise is presented which demonstrates the determination of sample purity by differential scanning calorimetry. Data and references are provided to enable the exercise to be carried out as a dry-lab experiment. (BB)

  17. Determination of Purity by Differential Scanning Calorimetry (DSC).

    Science.gov (United States)

    Brown, M. E.

    1979-01-01

    An exercise is presented which demonstrates the determination of sample purity by differential scanning calorimetry. Data and references are provided to enable the exercise to be carried out as a dry-lab experiment. (BB)

  18. Delta Doping High Purity CCDs and CMOS for LSST

    Science.gov (United States)

    Blacksberg, Jordana; Nikzad, Shouleh; Hoenk, Michael; Elliott, S. Tom; Bebek, Chris; Holland, Steve; Kolbe, Bill

    2006-01-01

    A viewgraph presentation describing delta doping high purity CCD's and CMOS for LSST is shown. The topics include: 1) Overview of JPL s versatile back-surface process for CCDs and CMOS; 2) Application to SNAP and ORION missions; 3) Delta doping as a back-surface electrode for fully depleted LBNL CCDs; 4) Delta doping high purity CCDs for SNAP and ORION; 5) JPL CMP thinning process development; and 6) Antireflection coating process development.

  19. Gaseous Detectors: Charged Particle Detectors - Particle Detectors and Detector Systems

    CERN Document Server

    Hilke, H J

    2011-01-01

    Gaseous Detectors in 'Charged Particle Detectors - Particle Detectors and Detector Systems', part of 'Landolt-Börnstein - Group I Elementary Particles, Nuclei and Atoms: Numerical Data and Functional Relationships in Science and Technology, Volume 21B1: Detectors for Particles and Radiation. Part 1: Principles and Methods'. This document is part of Part 1 'Principles and Methods' of Subvolume B 'Detectors for Particles and Radiation' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the Subsection '3.1.2 Gaseous Detectors' of Section '3.1 Charged Particle Detectors' of Chapter '3 Particle Detectors and Detector Systems' with the content: 3.1.2 Gaseous Detectors 3.1.2.1 Introduction 3.1.2.2 Basic Processes 3.1.2.2.1 Gas ionization by charged particles 3.1.2.2.1.1 Primary clusters 3.1.2.2.1.2 Cluster size distribution 3.1.2.2.1.3 Total number of ion pairs 3.1.2.2.1.4 Dependence of energy deposit on particle velocity 3.1.2.2.2 Transport of...

  20. Measurement of environmental radiation using medical scintillation detector in well counter system

    Energy Technology Data Exchange (ETDEWEB)

    Lyu, Kwang Yeul; Park, Yeon Joon; Kim, Min Jeong; Ham, Eun Hye; Yoon, Ji Yeol; Kim, Hyun in; Min, Jung Hwan; Park, Hoon Hee [Dept. of Radiological Technology, Shingu College, Sungnam (Korea, Republic of)

    2015-12-15

    After the Fukushima nuclear accident in 2011, concerns about radiation by people are increasing rapidly. If people could know how much they will be exposed by radiation, it may help them avoiding it and understand what exactly radiation is. By doing this, we were helping to reduce the anxiety of radiation contamination. In this study, we have researched figures of radioactivity with ‘Captus-3000 thyroid uptake measurement systems’ in well counter detector system. The materials were measured with Briquette, Shiitake, Pollock, Button type battery, Alkaline battery, Topsoil, Asphalt, Gasoline, Milk powder, Pine, Basalt stone, Pencil lead, Wasabi, Coarse salt, Tuna(can) Cigar, Beer, and then we categorized those samples into Land resources, Water resources, Foodstuff and Etc (Beer classified as a water resources has been categorized into Foodstuff). Also, we selected the standard radiation source linear 137Cs to measure the sensitivity of well counter detector. After that, we took cpm(counter per minute) for the well counter detector of thyroid uptake system’s sensitivity. Then we compared the results of each material’s cpm and converted those results to Bq/kg unit. There were a little limitation with the measurement equipment because it has less sensitivity than other professional equipment like ‘High purity germanium radiation detector’. Moreover, We didn’t have many choices to decide the materials. As a result, there are macroscopic differences among the rates of material’s spectrum. Therefore, it had meaningful results that showed how much each material had emitted radiation. To compare the material’s cpm with BKG, we’ve compounded their spectrums. By doing that, we were able to detect some differences among the spectrums at specific peak section. Lastly, Button type battery, Alkaline Battery, Briquette, Asphalt and Topsoil showed high value. There were classified emitting high radiation Group A and emitted lower radiation Group B. The Group A

  1. A TNFR2-Agonist Facilitates High Purity Expansion of Human Low Purity Treg Cells.

    Directory of Open Access Journals (Sweden)

    Xuehui He

    Full Text Available Regulatory T cells (Treg are important for immune homeostasis and are considered of great interest for immunotherapy. The paucity of Treg numbers requires the need for ex vivo expansion. Although therapeutic Treg flow-sorting is feasible, most centers aiming at Treg-based therapy focus on magnetic bead isolation of CD4+CD25+ Treg using a good manufacturing practice compliant closed system that achieves lower levels of cell purity. Polyclonal Treg expansion protocols commonly use anti-CD3 plus anti-CD28 monoclonal antibody (mAb stimulation in the presence of rhIL-2, with or without rapamycin. However, the resultant Treg population is often heterogeneous and pro-inflammatory cytokines like IFNγ and IL-17A can be produced. Hence, it is crucial to search for expansion protocols that not only maximize ex vivo Treg proliferative rates, but also maintain Treg stability and preserve their suppressive function. Here, we show that ex vivo expansion of low purity magnetic bead isolated Treg in the presence of a TNFR2 agonist mAb (TNFR2-agonist together with rapamycin, results in a homogenous stable suppressive Treg population that expresses FOXP3 and Helios, shows low expression of CD127 and hypo-methylation of the FOXP3 gene. These cells reveal a low IL-17A and IFNγ producing potential and hardly express the chemokine receptors CCR6, CCR7 and CXCR3. Restimulation of cells in a pro-inflammatory environment did not break the stability of this Treg population. In a preclinical humanized mouse model, the TNFR2-agonist plus rapamycin expanded Treg suppressed inflammation in vivo. Importantly, this Treg expansion protocol enables the use of less pure, but more easily obtainable cell fractions, as similar outcomes were observed using either FACS-sorted or MACS-isolated Treg. Therefore, this protocol is of great interest for the ex vivo expansion of Treg for clinical immunotherapy.

  2. A TNFR2-Agonist Facilitates High Purity Expansion of Human Low Purity Treg Cells.

    Science.gov (United States)

    He, Xuehui; Landman, Sija; Bauland, Stijn C G; van den Dolder, Juliette; Koenen, Hans J P M; Joosten, Irma

    2016-01-01

    Regulatory T cells (Treg) are important for immune homeostasis and are considered of great interest for immunotherapy. The paucity of Treg numbers requires the need for ex vivo expansion. Although therapeutic Treg flow-sorting is feasible, most centers aiming at Treg-based therapy focus on magnetic bead isolation of CD4+CD25+ Treg using a good manufacturing practice compliant closed system that achieves lower levels of cell purity. Polyclonal Treg expansion protocols commonly use anti-CD3 plus anti-CD28 monoclonal antibody (mAb) stimulation in the presence of rhIL-2, with or without rapamycin. However, the resultant Treg population is often heterogeneous and pro-inflammatory cytokines like IFNγ and IL-17A can be produced. Hence, it is crucial to search for expansion protocols that not only maximize ex vivo Treg proliferative rates, but also maintain Treg stability and preserve their suppressive function. Here, we show that ex vivo expansion of low purity magnetic bead isolated Treg in the presence of a TNFR2 agonist mAb (TNFR2-agonist) together with rapamycin, results in a homogenous stable suppressive Treg population that expresses FOXP3 and Helios, shows low expression of CD127 and hypo-methylation of the FOXP3 gene. These cells reveal a low IL-17A and IFNγ producing potential and hardly express the chemokine receptors CCR6, CCR7 and CXCR3. Restimulation of cells in a pro-inflammatory environment did not break the stability of this Treg population. In a preclinical humanized mouse model, the TNFR2-agonist plus rapamycin expanded Treg suppressed inflammation in vivo. Importantly, this Treg expansion protocol enables the use of less pure, but more easily obtainable cell fractions, as similar outcomes were observed using either FACS-sorted or MACS-isolated Treg. Therefore, this protocol is of great interest for the ex vivo expansion of Treg for clinical immunotherapy.

  3. Validation of Phonon Physics in the CDMS Detector Monte Carlo

    CERN Document Server

    McCarthy, K A; Anderson, A J; Brandt, D; Brink, P L; Cabrera, B; Cherry, M; Silva, E Do Couto E; Cushman, P; Doughty, T; Figueroa-Feliciano, E; Kim, P; Mirabolfathi, N; Novak, L; Partridge, R; Pyle, M; Reisetter, A; Resch, R; Sadoulet, B; Serfass, B; Sundqvist, K M; Tomada, A

    2011-01-01

    The SuperCDMS collaboration is a dark matter search effort aimed at detecting the scattering of WIMP dark matter from nuclei in cryogenic germanium targets. The CDMS Detector Monte Carlo (CDMS-DMC) is a simulation tool aimed at achieving a deeper understanding of the performance of the SuperCDMS detectors and aiding the dark matter search analysis. We present results from validation of the phonon physics described in the CDMS-DMC and outline work towards utilizing it in future WIMP search analyses.

  4. Ionizing radiation detector using multimode optical fibers

    Energy Technology Data Exchange (ETDEWEB)

    Suter, J.J. (Johns Hopkins Univ., Laurel, MD (United States). Applied Physics Lab.); Poret, J.C.; Rosen, M. (Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Materials Science and Engineering); Rifkind, J.M. (National Inst. of Health, Baltimore, MD (United States). Lab. of Cellular and Molecular Biology)

    1993-08-01

    An optical ionizing radiation detector, based on the attenuation of 850-nm light in 50/125-[mu]m multimode fibers, is described. The detector is especially well suited for application on spacecraft because of its small design. The detection element consists of a section of coiled fibers that has been designed to strip higher-order optical modes. Cylindrical radiation shields with atomic numbers ranging from Z = 13 (aluminum too) Z = 82 (lead) were placed around the ionizing radiation detector so that the effectiveness of the detector could be measured. By exposing the shields and the detector to 1.25-MeV cobalt 60 radiation, the mass attenuation coefficients of the shields were measured. The detector is based on the phenomenon that radiation creates optical color centers in glass fibers. Electron spin resonance spectroscopy performed on the 50/125-[mu]m fibers showed the presence of germanium oxide and phosphorus-based color centers. The intensity of these centers is directly related to the accumulated gamma radiation.

  5. Evaluation of purity with its uncertainty value in high purity lead stick by conventional and electro-gravimetric methods

    OpenAIRE

    Singh, Nahar; SINGH, Niranjan; Tripathy, S Swarupa; Soni, Daya; Singh, Khem; GUPTA Prabhat K

    2013-01-01

    Background A conventional gravimetry and electro-gravimetry study has been carried out for the precise and accurate purity determination of lead (Pb) in high purity lead stick and for preparation of reference standard. Reference materials are standards containing a known amount of an analyte and provide a reference value to determine unknown concentrations or to calibrate analytical instruments. A stock solution of approximate 2 kg has been prepared after dissolving approximate 2 g of Pb stic...

  6. In-Situ Cleaning, Passivation, Functionalization, and Atomic Layer Deposition on Germanium and Silicon-Germanium

    Science.gov (United States)

    Kaufman-Osborn, Tobin Adar

    In recent years, germanium (Ge) and silicon-germanium (SiGe) have drawn significant interest as replacements of conventional silicon in the search for alternative materials for use in complementary metal-oxide-semiconductor (CMOS) devices due to their high electron and hole mobilities. In order to effectively implement Ge or SiGe as a replacement for silicon, two major challenges must be overcome: non-disruptive cleaning and surface passivation/functionalization. As electrical devices are increasingly scaled, it becomes especially crucial to effectively clean each unit cell on the Ge/SiGe surface without causing major disruption or damage to the surface. If air-induced defects or contaminants persist on the surface after cleaning, these defect sites may be un-reactive for functionalization and thereby will hinder device performance and/or the ability to aggressively scale device size. If a cleaning method is too aggressive leaving a rough or disordered surface, this can lower the mobility at the interface which will worsen device performance. For these reasons, it is necessary to develop a non-disruptive cleaning process that cleans each unit cell leaving a flat, ordered, and reactive surface. Once the Ge or SiGe surface is cleaned, in order to achieve a good electrical quality interface and a high nucleation density on the surface, all surface atoms must be passivated and functionalized allowing for aggressive device scaling. The interface must remain electrically passive in order to not inhibit electrical performance of the device. This study uses scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), and x-ray photoelectron spectroscopy (XPS) to develop and analyze a completely in-situ non-disruptive cleaning method of the Ge surface using H2O2(g) and atomic hydrogen. After cleaning, the Ge or SiGe surface is passivated and functionalized using H2O2(g) as a method to improve upon the conventional H2O(g) passivation method by more than

  7. Reduction of material mass of optical component in cryogenic camera by using high-order Fresnel lens on a thin germanium substrate.

    Science.gov (United States)

    Grulois, Tatiana; Druart, Guillaume; Sauer, Hervé; Chambon, Mathieu; Guérineau, Nicolas; Magli, Serge; Lasfargues, Gillles; Chavel, Pierre

    2015-07-10

    We designed a compact infrared cryogenic camera using only one lens mounted inside the detector area. In the field of cooled infrared imaging systems, the maximal detector area is determined by the dewar. It is generally a sealed and cooled environment dedicated to the infrared quantum detector. By integrating an optical function inside it, we improve the compactness of the camera as well as its performances. The originality of our approach is to use a thin integrated optics which is a high quality Fresnel lens on a thin germanium substrate. The aim is to reduce the additional mass of the optical part integrated inside the dewar to obtain almost the same cool down time as a conventional dewar with no imaging function. A prototype has been made and its characterization has been carried out.

  8. CDEX实验中CsI(T1)晶体反符合探测器实验测试%Experimental Study on the CsI(T1) Crystal Anti-Compton Detector in CDEX

    Institute of Scientific and Technical Information of China (English)

    刘书魁; 岳骞; 唐昌建

    2012-01-01

    CDEX( China Dark matter EXperiment)合作组将在中国锦屏极深地下实验室(CJPL China Jin-Ping deep underground Laboratory)利用极低能阈高纯锗(ULE-HPGe)探测器进行暗物质的直接探测.在地下实验之前,对CsI(T1)晶体反符合探测器进行了地面的实验研究.主要包括光导的选择,光反射层的选择,CsI(T1)晶体的高度一致性测试,不同侧面非均匀性的测试,以及所有晶体的测试结果.通过地面实验的前期工作,我们对反符合探测器有了一定认识,为地下实验做了准备.%CDEX( China Dark matter Experiment) Collaboration will cany out direct search for dark matter with Ultra - Low Energy Threshold High Purity Germanium (ULE - HPGe) detector at CJPL( China Jinping deep underground Laboratory). Before underground research, some experiments of the CsI(Tl) crystal Anti - Compton detector have been done on the ground, including light guide choice, wrapping material choice, height uniformity of CsI(Tl) crystal, side uniformity of CsI(Tl) crystal and the test results of all the crystals. Through the preliminary work on the ground, we have got some knowledge of the anti - compton detector and prepared for the underground experiment.

  9. Improving Memory Characteristics of Hydrogenated Nanocrystalline Silicon Germanium Nonvolatile Memory Devices by Controlling Germanium Contents.

    Science.gov (United States)

    Kim, Jiwoong; Jang, Kyungsoo; Phu, Nguyen Thi Cam; Trinh, Thanh Thuy; Raja, Jayapal; Kim, Taeyong; Cho, Jaehyun; Kim, Sangho; Park, Jinjoo; Jung, Junhee; Lee, Youn-Jung; Yi, Junsin

    2016-05-01

    Nonvolatile memory (NVM) with silicon dioxide/silicon nitride/silicon oxynitride (ONO(n)) charge trap structure is a promising flash memory technology duo that will fulfill process compatibility for system-on-panel displays, down-scaling cell size and low operation voltage. In this research, charge trap flash devices were fabricated with ONO(n) stack gate insulators and an active layer using hydrogenated nanocrystalline silicon germanium (nc-SiGe:H) films at a low temperature. In this study, the effect of the interface trap density on the performance of devices, including memory window and retention, was investigated. The electrical characteristics of NVM devices were studied controlling Ge content from 0% to 28% in the nc-SiGe:H channel layer. The optimal Ge content in the channel layer was found to be around 16%. For nc-SiGe:H NVM with 16% Ge content, the memory window was 3.13 V and the retention data exceeded 77% after 10 years under the programming condition of 15 V for 1 msec. This showed that the memory window increased by 42% and the retention increased by 12% compared to the nc-Si:H NVM that does not contain Ge. However, when the Ge content was more than 16%, the memory window and retention property decreased. Finally, this research showed that the Ge content has an effect on the interface trap density and this enabled us to determine the optimal Ge content.

  10. Pixel Detectors

    OpenAIRE

    Wermes, Norbert

    2005-01-01

    Pixel detectors for precise particle tracking in high energy physics have been developed to a level of maturity during the past decade. Three of the LHC detectors will use vertex detectors close to the interaction point based on the hybrid pixel technology which can be considered the state of the art in this field of instrumentation. A development period of almost 10 years has resulted in pixel detector modules which can stand the extreme rate and timing requirements as well as the very harsh...

  11. Silicon and germanium mid-infrared photonics

    Science.gov (United States)

    Mashanovich, G. Z.; Reed, G. T.; Nedeljkovic, M.; Soler Penades, J.; Mitchell, C. J.; Khokhar, A. Z.; Littlejohns, C. J.; Stankovic, S.; Chen, X.; Shen, L.; Healy, N.; Peacock, A. C.; Alonso-Ramos, C.; Ortega-Monux, A.; Wanguemert-Perez, G.; Molina-Fernandez, I.; Cheben, P.; Ackert, J. J.; Knights, A. P.; Gardes, F. Y.; Thomson, D. J.

    2016-02-01

    We present three main material platforms: SOI, suspended Si and Ge on Si. We report low loss SOI waveguides (rib, strip, slot) with losses of ~1dB/cm. We also show efficient modulators and detectors realized in SOI, as well as filters and multiplexers. To extend transparency of SOI waveguides, bottom oxide cladding can be removed. We have fabricated low loss passive devices in a suspended platform that employ subwavelength gratings. Ge on Si material can have larger transparency range than suspended Si. We have designed passive devices in this platform, demonstrated all optical modulation and carried out two photon absorption measurements. We have also investigated theoretically free carrier optical modulation in Ge.

  12. An environmentally-friendly vacuum reduction metallurgical process to recover germanium from coal fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lingen; Xu, Zhenming, E-mail: zmxu@sjtu.edu.cn

    2016-07-15

    Highlights: • An environmental friendly vacuum reduction metallurgical process is proposed. • Rare and valuable metal germanium from coal fly ash is recycled. • Residues are not a hazardous material and can be further recycled. • A germanium recovery ratio of 94.64% is obtained in pilot scale experiments. - Abstract: The demand for germanium in the field of semiconductor, electronics, and optical devices is growing rapidly; however, the resources of germanium are scarce worldwide. As a secondary material, coal fly ash could be further recycled to retrieve germanium. Up to now, the conventional processes to recover germanium have two problems as follows: on the one hand, it is difficult to be satisfactory for its economic and environmental effect; on the other hand, the recovery ratio of germanium is not all that could be desired. In this paper, an environmentally-friendly vacuum reduction metallurgical process (VRMP) was proposed to recover germanium from coal fly ash. The results of the laboratory scale experiments indicated that the appropriate parameters were 1173 K and 10 Pa with 10 wt% coke addition for 40 min, and recovery ratio germanium was 93.96%. On the basis of above condition, the pilot scale experiments were utilized to assess the actual effect of VRMP for recovery of germanium with parameter of 1473 K, 1–10 Pa and heating time 40 min, the recovery ratio of germanium reached 94.64%. This process considerably enhances germanium recovery, meanwhile, eliminates much of the water usage and residue secondary pollution compared with other conventional processes.

  13. Synthesis and Gas Phase Thermochemistry of Germanium-Containing Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Classen, Nathan Robert [Iowa State Univ., Ames, IA (United States)

    2002-01-01

    The driving force behind much of the work in this dissertation was to gain further understanding of the unique olefin to carbene isomerization observed in the thermolysis of 1,1-dimethyl-2-methylenesilacyclobutane by finding new examples of it in other silicon and germanium compounds. This lead to the examination of a novel phenylmethylenesilacyclobut-2-ene, which did not undergo olefin to carbene rearrangement. A synthetic route to methylenegermacyclobutanes was developed, but the methylenegermacyclobutane system exhibited kinetic instability, making the study of the system difficult. In any case the germanium system decomposed through a complex mechanism which may not include olefin to carbene isomerization. However, this work lead to the study of the gas phase thermochemistry of a series of dialkylgermylene precursors in order to better understand the mechanism of the thermal decomposition of dialkylgermylenes. The resulting dialkylgermylenes were found to undergo a reversible intramolecular β C-H insertion mechanism.

  14. Synthesis and Gas Phase Thermochemistry of Germanium-Containing Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Nathan Robert Classen

    2002-12-31

    The driving force behind much of the work in this dissertation was to gain further understanding of the unique olefin to carbene isomerization observed in the thermolysis of 1,1-dimethyl-2-methylenesilacyclobutane by finding new examples of it in other silicon and germanium compounds. This lead to the examination of a novel phenylmethylenesilacyclobut-2-ene, which did not undergo olefin to carbene rearrangement. A synthetic route to methylenegermacyclobutanes was developed, but the methylenegermacyclobutane system exhibited kinetic instability, making the study of the system difficult. In any case the germanium system decomposed through a complex mechanism which may not include olefin to carbene isomerization. However, this work lead to the study of the gas phase thermochemistry of a series of dialkylgermylene precursors in order to better understand the mechanism of the thermal decomposition of dialkylgermylenes. The resulting dialkylgermylenes were found to undergo a reversible intramolecular {beta} C-H insertion mechanism.

  15. Diffusion of n-type dopants in germanium

    Energy Technology Data Exchange (ETDEWEB)

    Chroneos, A., E-mail: alexander.chroneos@imperial.ac.uk [Engineering and Innovation, The Open University, Milton Keynes MK7 6AA (United Kingdom); Department of Materials, Imperial College, London SW7 2AZ (United Kingdom); Bracht, H., E-mail: bracht@uni-muenster.de [Institute of Materials Physics, University of Münster, Wilhelm-Klemm-Strasse 10, D-48149 Münster (Germany)

    2014-03-15

    Germanium is being actively considered by the semiconductor community as a mainstream material for nanoelectronic applications. Germanium has advantageous materials properties; however, its dopant-defect interactions are less understood as compared to the mainstream material, silicon. The understanding of self- and dopant diffusion is essential to form well defined doped regions. Although p-type dopants such as boron exhibit limited diffusion, n-type dopants such as phosphorous, arsenic, and antimony diffuse quickly via vacancy-mediated diffusion mechanisms. In the present review, we mainly focus on the impact of intrinsic defects on the diffusion mechanisms of donor atoms and point defect engineering strategies to restrain donor atom diffusion and to enhance their electrical activation.

  16. Electronic Structure of Germanium Nanocrystal Films Probed with Synchrotron Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Bostedt, C

    2002-05-01

    The fundamental structure--property relationship of semiconductor quantum dots has been investigated. For deposited germanium nanocrystals strong quantum confinement effects have been determined with synchrotron radiation based x-ray absorption and photoemission techniques. The nanocrystals are condensed out of the gas phase with a narrow size distribution and subsequently deposited in situ onto various substrates. The particles are crystalline in the cubic phase with a structurally disordered surface shell and the resulting film morphology depends strongly on the substrate material and condition. The disordered surface region has an impact on the overall electronic structure of the particles. In a size-dependent study, the conduction and valence band edge of germanium nanocrystals have been measured for the first time and compared to the bulk crystal. The band edges move to higher energies as the particle size is decreased, consistent with quantum confinement theory. To obtain a more accurate analysis of confinement effects in the empty states, a novel analysis method utilizing an effective particle size for the x-ray absorption experiment, which allows a deconvolution of absorption edge broadening effects, has been introduced. Comparison of the present study to earlier studies on silicon reveals that germanium exhibits stronger quantum confinement effects than silicon. Below a critical particle size of 2.3 {+-} 0.7 nm, the band gap of germanium becomes larger than that of silicon--even if it is the opposite for bulk materials. This result agrees phenomenologically with effective mass and tight binding theories but contradicts the findings of recent pseudopotential calculations. The discrepancy between theory and experiments is attributed to the differences in the theoretical models and experimental systems. The experimentally observed structural disorder of the particle surface has to be included in the theoretical models.

  17. Diffusion of tin in germanium: A GGA+U approach

    KAUST Repository

    Tahini, H. A.

    2011-10-18

    Density functional theory calculations are used to investigate the formation and diffusion of tin-vacancy pairs (SnV) in germanium(Ge). Depending upon the Fermi energy, SnV pairs can form in neutral, singly negative, or doubly negative charged states. The activation energies of diffusion, also as function of the Fermi energy, are calculated to lie between 2.48-3.65 eV, in agreement with and providing an interpretation of available experimental work.

  18. Optical properties of silicon germanium waveguides at telecommunication wavelengths.

    Science.gov (United States)

    Hammani, Kamal; Ettabib, Mohamed A; Bogris, Adonis; Kapsalis, Alexandros; Syvridis, Dimitris; Brun, Mickael; Labeye, Pierre; Nicoletti, Sergio; Richardson, David J; Petropoulos, Periklis

    2013-07-15

    We present a systematic experimental study of the linear and nonlinear optical properties of silicon-germanium (SiGe) waveguides, conducted on samples of varying cross-sectional dimensions and Ge concentrations. The evolution of the various optical properties for waveguide widths in the range 0.3 to 2 µm and Ge concentrations varying between 10 and 30% is considered. Finally, we comment on the comparative performance of the waveguides, when they are considered for nonlinear applications at telecommunications wavelengths.

  19. Strain-induced changes to the electronic structure of germanium

    KAUST Repository

    Tahini, H. A.

    2012-04-17

    Density functional theory calculations (DFT) are used to investigate the strain-induced changes to the electronic structure of biaxially strained (parallel to the (001), (110) and (111) planes) and uniaxially strained (along the [001], [110] and [111] directions) germanium (Ge). It is calculated that a moderate uniaxial strain parallel to the [111] direction can efficiently transform Ge to a direct bandgap material with a bandgap energy useful for technological applications. © 2012 IOP Publishing Ltd.

  20. High purity tellurium production using dry refining processes

    Indian Academy of Sciences (India)

    N R Munirathnam; D S Prasad; J V Rao; T L Prakash

    2005-07-01

    Tellurium (99.95 at.% purity) is purified using dry processes such as selective vapourization and zone melting in a thoroughly etched and cleaned quartz boat, under continuous flow of hydrogen (H2) gas. The tellurium ingot was quadruple zone refined (QZR) under continuous flow of H2 gas. Thus, the purified tellurium of ultra high purity (UHP) grade is analysed for 60 impurity elements in the periodic table using glow discharge mass spectrometer (GDMS). The sum of all elemental impurities indicate that the purity of tellurium as 7N (99.99999 at.%). The total content of gas and gas forming impurities like O, N and C are found to be within acceptable limits for opto-electronic applications.

  1. Metal Detectors.

    Science.gov (United States)

    Harrington-Lueker, Donna

    1992-01-01

    Schools that count on metal detectors to stem the flow of weapons into the schools create a false sense of security. Recommendations include investing in personnel rather than hardware, cultivating the confidence of law-abiding students, and enforcing discipline. Metal detectors can be quite effective at afterschool events. (MLF)

  2. Optical Detectors

    Science.gov (United States)

    Tabbert, Bernd; Goushcha, Alexander

    Optical detectors are applied in all fields of human activities from basic research to commercial applications in communication, automotive, medical imaging, homeland security, and other fields. The processes of light interaction with matter described in other chapters of this handbook form the basis for understanding the optical detectors physics and device properties.

  3. Gamma tracking with the AGATA detector

    CERN Document Server

    Söderström, P -A; Nyberg, J; Recchia, F; Farnea, E; Gadea, A

    2008-01-01

    The next generation of radioactive ion beam facilities, which will give experimental access to many exotic nuclei, are presently being developed. At the same time the next generation of high resolution gamma-ray spectrometers, based on gamma-ray tracking, for studying the structure of these exotic nuclei are being developed. One of the main differences in tracking of $\\gamma$ rays versus charged particles is that the gamma rays do not deposit their energy "continuously" in the detector, but in a few discrete steps. Also, in the field of nuclear spectroscopy, the location of the source is mostly well known while the exact interaction position in the detector is the unknown quantity. This makes the challenges of gamma-ray tracking in germanium somewhat different compared to vertexing in silicon detectors. In these proceedings we present the methods for determining the 3D interaction positions in the detector and how these are used to reconstruct the gamma-ray tracks in the AGATA detector array. We also present ...

  4. Random Bures mixed states and the distribution of their purity

    Energy Technology Data Exchange (ETDEWEB)

    Al Osipov, V; Sommers, H-J [Fakultaet fuer Physik, Universitaet Duisburg-Essen, 47048 Duisburg (Germany); Zyczkowski, K, E-mail: Vladimir.Al.Osipov@gmail.co, E-mail: H.J.Sommers@uni-due.d, E-mail: karol@cft.edu.p [Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Krakow (Poland)

    2010-02-05

    Ensembles of random density matrices determined by various probability measures are analysed. A simple and efficient algorithm to generate at random density matrices distributed according to the Bures measure is proposed. This procedure may serve as an initial step in performing the Bayesian approach to quantum state estimation based on the Bures prior. We study the distribution of purity of random mixed states. The moments of the distribution of purity are determined for quantum states generated with respect to the Bures measure. This calculation serves as an exemplary application of the 'deform-and-study' approach in the theory of integrable systems leading to one of Painleves transcendents.

  5. Measures of quantum state purity and classical degree of polarization

    CERN Document Server

    Gamel, Omar

    2013-01-01

    There is a well-known mathematical similarity between two-dimensional classical polarization optics and two-level quantum systems, where the Poincare and Bloch spheres are identical mathematical structures. This analogy implies that the classical degree of polarization and quantum purity are in fact the same quantity. We make extensive use of this analogy to analyze various measures of polarization for higher dimensions proposed in the literature, in particular the N = 3 case, illustrating interesting relationships that emerge as well as the advantages of each measure. We also propose a different class of measures of entanglement based on the purity of subsystems.

  6. Development of Large Cryogenic Semiconductor Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Mandic, Vuk [Univ. of Minnesota, Minneapolis, MN (United States)

    2016-12-09

    This project aims at developing large cryogenic semiconductor detectors for applications in particle physics and more broadly. We have developed a 150 mm diameter, 43 mm thick, Si-based detector that measures ionization released in an interaction of a particle inside the silicon crystal of high purity, operated at 30 mK temperature. We demonstrated that such a detector can be used to measure recoil energies on the keV scale, and that its stable operation can be maintained indefinitely. Detectors of this type could therefore be used in the fields of direct dark matter searches, coherent neutrino scattering measurements, X-ray observations, as well as in broader applications such as homeland security.

  7. Search for an annual modulation of dark-matter signals with a germanium spectrometer at the Sierra Grande Laboratory

    CERN Document Server

    Abriola, D; Brodzinski, R L; Collar, J I; Gregorio, D E D; Farach, H A; García, E; Gattone, A O; Guérard, C K; Hasenbalg, F; Huck, H; Miley, H S; Morales, A; Morales, J; De Solorzano, A O; Puimedón, J; Reeves, J H; Salinas, A; Sarsa, M L; Villar, J A

    1999-01-01

    Data collected during three years with a germanium spectrometer at the Sierra Grande underground laboratory have been analyzed for distinctive features of annual modulation of the signal induced by WIMP dark matter candidates. The main motivation for this analysis was the recent suggestion by the DAMA/NaI Collaboration that a yearly modulation signal could not be rejected at the 90% confidence level when analyzing data obtained with a high-mass low-background scintillator detector. We performed two different analyses of the data: First, the statistical distribution of modulation-significance variables (expected from an experiment running under the conditions of Sierra Grande) was compared with the same variables obtained from the data. Second, the data were analyzed in energy bins as an independent check of the first result and to allow for the possibility of a crossover in the expected signal. In both cases no statistically significant deviation from the null result was found, which could support the hypothe...

  8. Functionalization of Mechanochemically Passivated Germanium Nanoparticles via "Click" Chemistry

    Science.gov (United States)

    Purkait, Tapas Kumar

    Germanium nanoparticles (Ge NPs) may be fascinating for their electronic and optoelectronic properties, as the band gap of Ge NPs can be tuned from the infrared into the visible range of solar spectru. Further functionalization of those nanoparticles may potentially lead to numerous applications ranging from surface attachment, bioimaging, drug delivery and nanoparticles based devices. Blue luminescent germanium nanoparticles were synthesized from a novel top-down mechanochemical process using high energy ball milling (HEBM) of bulk germanium. Various reactive organic molecules (such as, alkynes, nitriles, azides) were used in this process to react with fresh surface and passivate the surface through Ge-C or Ge-N bond. Various purification process, such as gel permeation chromatography (GPC), Soxhlet dailysis etc. were introduced to purify nanoparticles from molecular impurities. A size separation technique was developed using GPC. The size separated Ge NPs were characterize by TEM, small angle X-ray scattering (SAXS), UV-vis absorption and photoluminescence (PL) emission spectroscopy to investigate their size selective properties. Germanium nanoparticles with alkyne termini group were prepared by HEBM of germanium with a mixture of n-alkynes and alpha, o-diynes. Additional functionalization of those nanoparticles was achieved by copper(I) catalyzed azide-alkyne "click" reaction. A variety of organic and organometallic azides including biologically important glucals have been reacted in this manner resulting in nanopartilces adorned with ferrocenyl, trimethylsilyl, and glucal groups. Additional functionalization of those nanoparticles was achieved by reactions with various azides via a Cu(I) catalyzed azide-alkyne "click" reaction. Various azides, including PEG derivatives and cylcodextrin moiety, were grafted to the initially formed surface. Globular nanoparticle arrays were formed through interparticle linking via "click" chemistry or "host-guest" chemistry

  9. Strengthening Purity: Moral Purity as a Mediator of Direct and Extended Cross-Group Friendships on Sexual Prejudice.

    Science.gov (United States)

    Vezzali, Loris; Brambilla, Marco; Giovannini, Dino; Paolo Colucci, Francesco

    2017-01-01

    The present research investigated whether enhanced perceptions of moral purity drive the effects of intergroup cross-group friendships on the intentions to interact with homosexuals. High-school students (N = 639) reported their direct and extended cross-group friendships with homosexuals as well as their beliefs regarding the moral character of the sexual minority. Participants further reported their desire to interact with homosexuals in the future. Results showed that both face-to-face encounters and extended contact with homosexuals increased their perceived moral purity, which in turn fostered more positive behavioral intentions. Results further revealed the specific role of moral purity in this sense, as differential perceptions along other moral domains (autonomy and community) had no mediation effects on behavioral tendencies toward homosexuals. The importance of these findings for improving intergroup relations is discussed, together with the importance of integrating research on intergroup contact and morality.

  10. Comparison of optimised germanium gamma spectrometry and multicollector inductively coupled plasma mass spectrometry for the determination of 134Cs, 137Cs and 154Eu single ratios in highly burnt UO 2

    Science.gov (United States)

    Caruso, S.; Günther-Leopold, I.; Murphy, M. F.; Jatuff, F.; Chawla, R.

    2008-05-01

    Non-destructive and destructive methods have been compared to validate their corresponding assessed accuracies in the measurement of 134Cs/137Cs and 154Eu/137Cs isotopic concentration ratios in four spent UO2 fuel samples with very high (52 and 71 GWd/t) and ultra-high (91 and 126 GWd/t) burnup values, and about 10 (in the first three samples) and 4 years (in the latter sample) cooling time. The non-destructive technique tested was high-resolution gamma spectrometry using a high-purity germanium detector (HPGe) and a special tomographic station for the handling of highly radioactive 400 mm spent fuel segments that included a tungsten collimator, lead filter (to enhance the signal to Compton background ratio and reduce the dead time) and paraffin wax (to reduce neutron damage). The non-destructive determination of these isotopic concentration ratios has been particularly challenging for these segments because of the need to properly derive non-Gaussian gamma-peak areas and subtract the background from perturbing capture gammas produced by the intrinsic high-intensity neutron emissions from the spent fuel. Additionally, the activity distribution within each pin was determined tomographically to correct appropriately for self-attenuation and geometrical effects. The ratios obtained non-destructively showed a 1σ statistical error in the range 1.9-2.9%. The destructive technique used was a high-performance liquid chromatographic separation system, combined online to a multicollector inductively coupled plasma mass spectrometer (HPLC-MC-ICP-MS), for the analysis of dissolved fuel solutions. During the mass spectrometric analyses, special care was taken in the optimisation of the chromatographic separation for Eu and the interfering element Gd, as also in the mathematical correction of the 154Gd background from the 154Eu signal. The ratios obtained destructively are considerably more precise (1σ statistical error in the range 0.4-0.8% for most of the samples, but up to

  11. Low cost routes to high purity silicon and derivatives thereof

    Energy Technology Data Exchange (ETDEWEB)

    Laine, Richard M; Krug, David James; Marchal, Julien Claudius; Mccolm, Andrew Stewart

    2013-07-02

    The present invention is directed to a method for providing an agricultural waste product having amorphous silica, carbon, and impurities; extracting from the agricultural waste product an amount of the impurities; changing the ratio of carbon to silica; and reducing the silica to a high purity silicon (e.g., to photovoltaic silicon).

  12. Purity Evaluation of Bulk Single Wall Carbon Nanotube Materials

    Science.gov (United States)

    Dettlaff-Weglikowska, U.; Wang, J.; Liang, J.; Hornbostel, B.; Cech, J.; Roth, S.

    2005-09-01

    We report on our experience using a preliminary protocol for quality control of bulk single wall carbon nanotube (SWNT) materials produced by the electric arc-discharge and laser ablation method. The first step in the characterization of the bulk material is mechanical homogenization. Quantitative evaluation of purity has been performed using a previously reported procedure based on solution phase near-infrared spectroscopy. Our results confirm that this method is reliable in determining the nanotube content in the arc-discharge sample containing carbonaceous impurities (amorphous carbon and graphitic particles). However, the application of this method to laser ablation samples gives a relative purity value over 100 %. The possible reason for that might be different extinction coefficient meaning different oscillator strength of the laser ablation tubes. At the present time, a 100 % pure reference sample of laser ablation SWNT is not available, so we chose to adopt the sample showing the highest purity as a new reference sample for a quantitative purity evaluation of laser ablation materials. The graphitic part of the carbonaceous impurities has been estimated using X-ray diffraction of 1:1 mixture of nanotube material and C60 as an internal reference. To evaluate the metallic impurities in the as prepared and homogenized carbon nanotube soot inductive coupled plasma (ICP) has been used.

  13. Estimation of purity in terms of correlation functions

    Science.gov (United States)

    Prosen, Tomaž; Seligman, Thomas H.; Žnidarič, Marko

    2003-06-01

    We prove a rigorous inequality that estimates the purity of a reduced density matrix of a composite quantum system in terms of cross correlation of the same state and an arbitrary product state. Various immediate applications of our result are proposed, in particular, concerning Gaussian wave-packet propagation under classically regular dynamics.

  14. Analysis of the Purity of Cetrimide by Titrations

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Rasmussen, Claus/Dallerup; Nielsen, Hans/Boye

    2006-01-01

    The purity of cetrimide, trimethyl tetradecyl ammonium bromide (TTAB), that is an important preservative of many cosmetic and pharmaceutical products, was determined by three independent methods of titration. Traditionally, cetrimide was analysed by an assay method of the European Pharmacopoeia (Ph...

  15. Improved WIMP-search reach of the CDMS II germanium data

    CERN Document Server

    Agnese, R; Asai, M; Balakishiyeva, D; Barker, D; Thakur, R Basu; Bauer, D A; Billard, J; Borgland, A; Bowles, M A; Brandt, D; Brink, P L; Bunker, R; Cabrera, B; Caldwell, D O; Calkins, R; Cerdeño, D G; Chagani, H; Chen, Y; Cooley, J; Cornell, B; Crewdson, C H; Cushman, P; Daal, M; Di Stefano, P C F; Doughty, T; Esteban, L; Fallows, S; Figueroa-Feliciano, E; Godfrey, G L; Golwala, S R; Hall, J; Harris, H R; Hertel, S A; Hofer, T; Holmgren, D; Hsu, L; Huber, M E; Jardin, D; Jastram, A; Kamaev, O; Kara, B; Kelsey, M H; Kennedy, A; Kiveni, M; Koch, K; Leder, A; Loer, B; Asamar, E Lopez; Lukens, P; Mahapatra, R; Mandic, V; McCarthy, K A; Mirabolfathi, N; Moffatt, R A; Oser, S M; Page, K; Page, W A; Partridge, R; Pepin, M; Phipps, A; Prasad, K; Pyle, M; Qiu, H; Rau, W; Redl, P; Reisetter, A; Ricci, Y; Rogers, H E; Saab, T; Sadoulet, B; Sander, J; Schneck, K; Schnee, R W; Scorza, S; Serfass, B; Shank, B; Speller, D; Toback, D; Upadhyayula, S; Villano, A N; Welliver, B; Wilson, J S; Wright, D H; Yang, X; Yellin, S; Yen, J J; Young, B A; Zhang, J

    2015-01-01

    CDMS II data from the 5-tower runs at the Soudan Underground Laboratory were reprocessed with an improved charge-pulse fitting algorithm. Two new analysis techniques to reject surface-event backgrounds were applied to the 612 kg days germanium-detector WIMP-search exposure. An extended analysis was also completed by decreasing the 10 keV analysis threshold to $\\sim$5 keV, to increase sensitivity near a WIMP mass of 8 GeV/$c^2$. After unblinding, there were zero candidate events above a deposited energy of 10 keV and 6 events in the lower-threshold analysis. This yielded minimum WIMP-nucleon spin-independent scattering cross-section limits of $1.8 \\times 10^{-44}$ and $1.18 \\times 10 ^{-41}$ cm$^2$ at 90\\% confidence for 60 and 8.6 GeV/$c^2$ WIMPs, respectively. This improves the previous CDMS II result by a factor of 2.4 (2.7) for 60 (8.6) GeV/$c^2$ WIMPs.

  16. Improved WIMP-search reach of the CDMS II germanium data

    Energy Technology Data Exchange (ETDEWEB)

    Agnese, R.; Anderson, A. J.; Asai, M.; Balakishiyeva, D.; Barker, D.; Basu Thakur, R.; Bauer, D. A.; Billard, J.; Borgland, A.; Bowles, M. A.; Brandt, D.; Brink, P. L.; Bunker, R.; Cabrera, B.; Caldwell, D. O.; Calkins, R.; Cerdeno, D. G.; Chagani, H.; Chen, Y.; Cooley, J.; Cornell, B.; Crewdson, C. H.; Cushman, Priscilla B.; Daal, M.; Di Stefano, P. C.; Doughty, T.; Esteban, L.; Fallows, S.; Figueroa-Feliciano, E.; Godfrey, G. L.; Golwala, S. R.; Hall, Jeter C.; Harris, H. R.; Hertel, S. A.; Hofer, T.; Holmgren, D.; Hsu, L.; Huber, M. E.; Jardin, D. M.; Jastram, A.; Kamaev, O.; Kara, B.; Kelsey, M. H.; Kennedy, A.; Kiveni, M.; Koch, K.; Leder, A.; Loer, B.; Lopez Asamar, E.; Lukens, P.; Mahapatra, R.; Mandic, V.; McCarthy, K. A.; Mirabolfathi, N.; Moffatt, R. A.; Oser, S. M.; Page, K.; Page, W. A.; Partridge, R.; Pepin, M.; Phipps, A.; Prasad, K.; Pyle, M.; Qiu, H.; Rau, W.; Redl, P.; Reisetter, A.; Ricci, Y.; Rogers, H. E.; Saab, T.; Sadoulet, B.; Sander, J.; Schneck, K.; Schnee, R. W.; Scorza, S.; Serfass, B.; Shank, B.; Speller, D.; Toback, D.; Upadhyayula, S.; Villano, A. N.; Welliver, B.; Wilson, J. S.; Wright, D. H.; Yang, X.; Yellin, S.; Yen, J. J.; Young, B. A.; Zhang, J.

    2015-10-31

    CDMS II data from the five-tower runs at the Soudan Underground Laboratory were reprocessed with an improved charge-pulse fitting algorithm. Two new analysis techniques to reject surface-event backgrounds were applied to the 612 kg days germanium-detector weakly interacting massive particle (WIMP)-search exposure. An extended analysis was also completed by decreasing the 10 keV analysis threshold to ~5 keV, to increase sensitivity near a WIMP mass of 8 GeV/c2. After unblinding, there were zero candidate events above a deposited energy of 10 keV and six events in the lower-threshold analysis. This yielded minimum WIMP-nucleon spin-independent scattering cross-section limits of 1.8×10-44 and 1.18×10-41 at 90% confidence for 60 and 8.6 GeV/c2 WIMPs, respectively. This improves the previous CDMS II result by a factor of 2.4 (2.7) for 60 (8.6) GeV/c2 WIMPs.

  17. Measurements of thermal characteristics in silicon germanium un-cooled micro-bolometers

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, Mario; Torres, Alfonso; Kosarev, Andrey [National Institute for Astrophysics, Optics and Electronics, P.O. Box 51 and 216, Z.P. 7200 Puebla (Mexico); Ambrosio, Roberto; Mireles, Jose [Universidad Autonoma de Ciudad Juarez, Electrical Department, Av. Del Charro 450 N, Z.P. 32310, C. J., Chihuahua (Mexico); Garcia, Maria [Benemerita Universidad Autonoma de Puebla, Physics Department, Av. San Claudio S/N Z.P. 72570 Puebla (Mexico)

    2010-04-15

    We present a study of the thermal characteristics of an infrared detector (un-cooled micro-bolometer), based on an amorphous silicon germanium film (a-Si{sub x}Ge{sub y}:H), deposited by plasma at low temperature ({proportional_to} 300 C) and compatible with the standard CMOS technology. These films have been studied due to their high performance characteristics as high activation energy (E{sub a}{approx} 0.37 eV), high temperature coefficient of resistance (TCR{approx} -0.047 K{sup -1}) and moderate room temperature conductivity ({sigma}{sub RT}{approx} 2x10{sup -5}{omega} cm), which provides a moderate pixel resistance (R{sub cell}{approx}3.5x10{sup 8}{omega}). We have used two simple methods to calculate the thermal characteristics of the micro-bolometer. The thermal conductance (G{sub th}) has been obtained from the electrical I(U) characteristics in the range where self heating due to bias is not presented. The temperature dependence of the electrical resistance and as well the temperature dependence of the thermal resistance have been obtained by measuring the I(U) characteristics in the device at different temperature values. Finally the results of both methods have been compared. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. DUMAND detector

    CERN Multimedia

    This object is one of the 256 other detectors of the DUMAND (Deep Underwater Muon And Neutrino Detection) experiment. The goal of the experiment was the construction of the first deep ocean high energy neutrino detector, to be placed at 4800 m depth in the Pacific Ocean off Keahole Point on the Big Island of Hawaii. A few years ago, a European conference with Cosmic experiments was organized at CERN as they were projects like DUMAND in Hawaii. Along with the conference, a temporary exhibition was organised as well. It was a collaboration of institutions from Germany, Japan, Switzerland and the U.S.A. CERN had borrowed equipment and objects from different institutes around the world, including this detector of the DUMAND experiment. Most of the equipment were sent back to the institutes, however this detector sphere was offered to a CERN member of the personnel.

  19. Ion-beam induced structure modifications in amorphous germanium; Ionenstrahlinduzierte Strukturmodifikationen in amorphem Germanium

    Energy Technology Data Exchange (ETDEWEB)

    Steinbach, Tobias

    2012-05-03

    Object of the present thesis was the systematic study of ion-beam induced structure modifications in amorphous germanium (a-Ge) layers due to low- (LEI) and high-energetic (SHI) ion irradiation. The LEI irradiation of crystalline Ge (c-Ge) effects because the dominating nuclear scattering of the ions on the solid-state atoms the formation of a homogeneous a-Ge Layer. Directly on the surface for fluences of two orders of magnitude above the amorphization fluence the formation of stable cavities independently on the irradiation conditions was observed. For the first time for the ion-beam induced cavity formation respectively for the steady expansion of the porous layer forming with growing fluence a linear dependence on the energy {epsilon}{sub n} deposed in nuclear processes was detected. Furthermore the formation of buried cavities was observed, which shows a dependence on the type of ions. While in the c-Ge samples in the range of the high electronic energy deposition no radiation defects, cavities, or plastic deformations were observed, the high electronic energy transfer in the 3.1 {mu}m thick pre-amorphized a-Ge surface layers leads to the formation of randomly distributed cavities. Basing on the linear connection between cavity-induced vertical volume expansion and the fluence determined for different energy transfers for the first time a material-specific threshold value of {epsilon}{sub e}{sup HRF}=(10.5{+-}1.0) kev nm{sup -1} was determined, above which the ion-beam induced cavity formation in a-Ge sets on. The anisotropic plastic deformation of th a-Ge layer superposed at inclined SHI irradiation on the cavity formation was very well described by an equation derived from the viscoelastic Maxwell model, but modified under regardment of the experimental results. The positive deformation yields determined thereby exhibit above a threshold value for the ion-beam induced plastic deformation {epsilon}{sub e}{sup S{sub a}}=(12{+-}2) keV nm{sup -1} for the first

  20. Oriented bottom-up growth of armchair graphene nanoribbons on germanium

    Science.gov (United States)

    Arnold, Michael Scott; Jacobberger, Robert Michael

    2016-03-15

    Graphene nanoribbon arrays, methods of growing graphene nanoribbon arrays and electronic and photonic devices incorporating the graphene nanoribbon arrays are provided. The graphene nanoribbons in the arrays are formed using a scalable, bottom-up, chemical vapor deposition (CVD) technique in which the (001) facet of the germanium is used to orient the graphene nanoribbon crystals along the [110] directions of the germanium.

  1. A measurement method of a detector response function for monochromatic electrons based on the Compton scattering

    Science.gov (United States)

    Bakhlanov, S. V.; Bazlov, N. V.; Derbin, A. V.; Drachnev, I. S.; Kayunov, A. S.; Muratova, V. N.; Semenov, D. A.; Unzhakov, E. V.

    2016-06-01

    In this paper we present a method of scintillation detector energy calibration using the gamma-rays. The technique is based on the Compton scattering of gamma-rays in a scintillation detector and subsequent photoelectric absorption of the scattered photon in the Ge-detector. The novelty of this method is that the source of gamma rays, the germanium and scintillation detectors are immediately arranged adjacent to each other. The method presents an effective solution for the detectors consisting of a low atomic number materials, when the ratio between Compton effect and photoelectric absorption is large and the mean path of gamma-rays is comparable to the size of the detector. The technique can be used for the precision measurements of the scintillator light yield dependence on the electron energy.

  2. A measurement method of a detector response function for monochromatic electrons based on the Compton scattering

    CERN Document Server

    Bakhlanov, S V; Derbin, A V; Drachnev, I S; Kayunov, A S; Muratova, V N; Semenov, D A; Unzhakov, E V

    2016-01-01

    In this paper we present a method of scintillation detector energy calibration using the gamma-rays. The technique is based on the Compton scattering of gamma-rays in a scintillation detector and subsequent photoelectric absorption of the scattered photon in the Ge-detector. The novelty of this method is that the source of gamma rays, the germanium and scintillation detectors are immediately arranged adjacent to each other. The method presents an effective solution for the detectors consisting of a low atomic number materials, when the ratio between Compton effect and photoelectric absorption is large and the mean path of gamma-rays is comparable to the size of the detector. The technique can be used for the precision measurements of the scintillator light yield dependence on the electron energy.

  3. A measurement method of a detector response function for monochromatic electrons based on the Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Bakhlanov, S.V. [St.Petersburg Nuclear Physics Institute, National Research Center “Kurchatov Institute”, Gatchina 188300 (Russian Federation); Bazlov, N.V. [Saint-Petersburg State University, Universitetskaja nab. 7/9, Saint-Petersburg 199034 (Russian Federation); Derbin, A.V., E-mail: derbin@pnpi.spb.ru [St.Petersburg Nuclear Physics Institute, National Research Center “Kurchatov Institute”, Gatchina 188300 (Russian Federation); Drachnev, I.S. [St.Petersburg Nuclear Physics Institute, National Research Center “Kurchatov Institute”, Gatchina 188300 (Russian Federation); GranSasso Science Institute, INFN, L' Aquila (AQ) I-67100 (Italy); Kayunov, A.S.; Muratova, V.N.; Semenov, D.A.; Unzhakov, E.V. [St.Petersburg Nuclear Physics Institute, National Research Center “Kurchatov Institute”, Gatchina 188300 (Russian Federation)

    2016-06-11

    In this paper we present a method of scintillation detector energy calibration using the gamma-rays. The technique is based on the Compton scattering of gamma-rays in a scintillation detector and subsequent photoelectric absorption of the scattered photon in the Ge-detector. The novelty of this method is that the source of gamma rays, the germanium and scintillation detectors are immediately arranged adjacent to each other. The method presents an effective solution for the detectors consisting of a low atomic number materials, when the ratio between Compton effect and photoelectric absorption is large and the mean path of gamma-rays is comparable to the size of the detector. The technique can be used for the precision measurements of the scintillator light yield dependence on the electron energy.

  4. Femtosecond Laser Processing of Germanium: An Ab Initio Molecular Dynamics Study

    CERN Document Server

    Ji, Pengfei

    2016-01-01

    An ab initio molecular dynamics study of femtosecond laser processing of germanium is presented in this paper. The method based on the finite temperature density functional theory is adopted to probe the structural change, thermal motion of the atoms, dynamic property of the velocity autocorrelation, and the vibrational density of states. Starting from a cubic system at room temperature (300 K) containing 64 germanium atoms with an ordered arrangement of 1.132 nm in each dimension, the femtosecond laser processing is simulated by imposing the Nose Hoover thermostat to the electronic subsystem lasting for ~100 fs and continuing with microcanonical ensemble simulation of ~200 fs. The simulation results show solid, liquid and gas phases of germanium under adjusted intensities of the femtosecond laser irradiation. We find the irradiated germanium distinguishes from the usual germanium crystal by analyzing their melting and dynamic properties.

  5. Suspended germanium cross-shaped microstructures for enhancing biaxial tensile strain

    Science.gov (United States)

    Ishida, Satomi; Kako, Satoshi; Oda, Katsuya; Ido, Tatemi; Iwamoto, Satoshi; Arakawa, Yasuhiko

    2016-04-01

    We fabricate a suspended germanium cross-shaped microstructure to biaxially enhance residual tensile strain using a germanium epilayer directly grown on a silicon-on-insulator substrate. Such a suspended germanium system with enhanced biaxial tensile strain will be a promising platform for incorporating optical cavities toward the realization of germanium lasers. We demonstrate systematic control over biaxial tensile strain and photoluminescence peaks by changing structural geometry. The photoluminescence peaks corresponding to the direct recombination between the conduction Γ valley and two strain-induced separated valence bands have been clearly assigned. A maximum biaxial strain of 0.8% has been achieved, which is almost half of that required to transform germanium into a direct band-gap semiconductor.

  6. Neutron induced activity in natural and enriched {sup 70}Ge detectors

    Energy Technology Data Exchange (ETDEWEB)

    Naya, J.E. [Toulouse-3 Univ., 31 (France). Centre d`Etude Spatiale des Rayonnements]|[NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)]|[Universities Space Research Association, 7501 Forbes Blvd, 206, Seabrook, MD 20706-2253 (United States); Jean, P.; Albernhe, F.; Borrel, V.; Lavigne, J.M.; Vedrenne, G.; von Ballmoos, P. [Toulouse-3 Univ., 31 (France). Centre d`Etude Spatiale des Rayonnements; Barthelmy, S.D. [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)]|[Universities Space Research Association, 7501 Forbes Blvd, 206, Seabrook, MD 20706-2253 (United States); Bartlett, L.M.; Gehrels, N.; Parsons, A.; Tueller, J. [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Cordier, B. [Service d`Astrophysique du CEA, CEN de Saclay, 91191 Gif sur Yvette, Cedex (France); Leleux, P. [Institut de Physique Nucleaire, 2 chemin du Cyclotron, B-1348 Louvain-la-Neuve (Belgium); Teegarden, B.J. [Toulouse-3 Univ., 31 (France). Centre d`Etude Spatiale des Rayonnements]|[NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    1997-09-11

    The results of irradiations of isotopically enriched and natural Ge detectors with a neutron beam are presented. The analysis of the gamma-ray lines generated by decay of neutron induced unstable nuclei have provided us with a direct measurement of relevant interaction cross sections. Within a factor of 2, measurements and predictions are in good agreement. These results have important implications for the instrumental background in astrophysical gamma-ray spectrometers using germanium detectors. We confirm the reduction of the {beta}-background component, which dominates the continuum background in the 0.1-1 MeV energy range, using {sup 70}Ge enriched detectors. We clearly identify {beta}{sup +} decays inside the detector as a significant source of continuum background in the 1-4 MeV energy range. This component is about 2 times more intense in {sup 70}Ge enriched detectors than in natural ones. This is mainly due to the enhanced yield of {sup 69}Ge and {sup 68}Ga isotopes. The choice of either natural or {sup 70}Ge enriched as optimum detector material depends on the energies of astrophysical interest. Detectors made of enriched {sup 70}Ge are more appropriate for studies at energies below 1 MeV. For higher energies natural germanium is slightly better. The possibility of rejecting most of {beta}-background component by applying alternative analysis techniques makes natural Ge an appropriate material for future gamma-ray spectrometers. (orig.). 15 refs.

  7. Infrared absorption study of neutron-transmutation-doped germanium

    Science.gov (United States)

    Park, I. S.; Haller, E. E.

    1988-01-01

    Using high-resolution far-infrared Fourier transform absorption spectroscopy and Hall effect measurements, the evolution of the shallow acceptor and donor impurity levels in germanium during and after the neutron transmutation doping process was studied. The results show unambiguously that the gallium acceptor level concentration equals the concentration of transmutated Ge-70 atoms during the whole process indicating that neither recoil during transmutation nor gallium-defect complex formation play significant roles. The arsenic donor levels appear at full concentration only after annealing for 1 h at 450 C. It is shown that this is due to donor-radiation-defect complex formation. Again, recoil does not play a significant role.

  8. Homo and hetero epitaxy of Germanium using isobutylgermane

    Energy Technology Data Exchange (ETDEWEB)

    Attolini, G. [CNR-IMEM Institute, Parco Area delle Scienze 37/A, 43010 Fontanini, Parma (Italy); Bosi, M. [CNR-IMEM Institute, Parco Area delle Scienze 37/A, 43010 Fontanini, Parma (Italy)], E-mail: bosi@imem.cnr.it; Musayeva, N.; Pelosi, C.; Ferrari, C.; Arumainathan, S. [CNR-IMEM Institute, Parco Area delle Scienze 37/A, 43010 Fontanini, Parma (Italy); Timo, G. [CESI Ricerca S.P.A., Via Rubattino 54, 20134 Milano (Italy)], E-mail: Gianluca.Timo@cesiricerca.it

    2008-11-03

    Nominally undoped Ge epitaxial layers were deposited on Ge and GaAs substrates by means of Metal-Organic Vapor Phase (MOVPE) using a novel Germanium source, isobutylgermane (iBuGe), by Rohm and Haas Electronic Materials LLC (USA). High Resolution X-ray Diffraction, Atomic Force Microscopy and Raman spectroscopy were combined to characterize the layers. Ge layers were deposited using AsH{sub 3} as a surfactant and several growth procedures were tested. The use of arsine reduced the growth rate and also significantly improved the epitaxial quality and surface roughness.

  9. Point defect engineering strategies to retard phosphorous diffusion in germanium

    KAUST Repository

    Tahini, H. A.

    2013-01-01

    The diffusion of phosphorous in germanium is very fast, requiring point defect engineering strategies to retard it in support of technological application. Density functional theory corroborated with hybrid density functional calculations are used to investigate the influence of the isovalent codopants tin and hafnium in the migration of phosphorous via the vacancy-mediated diffusion process. The migration energy barriers for phosphorous are increased significantly in the presence of oversized isovalent codopants. Therefore, it is proposed that tin and in particular hafnium codoping are efficient point defect engineering strategies to retard phosphorous migration. © the Owner Societies 2013.

  10. Radiation-enhanced self- and boron diffusion in germanium

    DEFF Research Database (Denmark)

    Schneider, S.; Bracht, H.; Klug, J.N.

    2013-01-01

    We report experiments on proton radiation-enhanced self- and boron (B) diffusion in germanium (Ge) for temperatures between 515 ∘ C and 720 ∘ C. Modeling of the experimental diffusion profiles measured by means of secondary ion mass spectrometry is achieved on the basis of the Frenkel pair reaction...... to an enhanced self- and B diffusion in Ge. Analysis of the experimental profiles yields data for the diffusion of self-interstitials (I ) and the thermal equilibrium concentration of BI pairs in Ge. The temperature dependence of these quantities provides the migration enthalpy of I and formation enthalpy of BI...

  11. Properties Of Gallium-doped Hydrogenated Amorphous Germanium

    OpenAIRE

    1995-01-01

    The effects of adding small quantities of gallium atoms to hydrogenated amorphous germanium (a-Ge:H) on its dark-conductivity, band-gap, electronic density of states and the hydrogen bonding, were studied in detail by dark-conductivity, optical and infrared-transmission, and photothermal- deflection-spectroscopy measurements. Films of a-Ge:H having relative Ga atomic concentrations ranging between 3×10-5 and 1×10-2 were deposited by the cosputtering of solid Ge and Ga targets in a rf-plasma s...

  12. Effect of germanium dioxide on growth of Spirulina platensis

    Science.gov (United States)

    Cao, Ji-Xiang

    1996-12-01

    This study on the effect of different concentrations of germanium dioxide (GeO2) on the specific growth rate (SGR), pigment contents, protein content and amino acid composition of Spirulina platensis showed that Ge was not the essential element of this alga; that GeO2 could speed up growth and raise protein content of S. platensis, and could possibly influence the photosynthesis system. The concentration range of GeO2 beneficial to growth of S. platensis is from 5 100mg/l. GeO2 is proposed to be utilized to remove contamination by Chlorella spp. usually occurring in the cultivation of Spirulina.

  13. Cryostat for Ultra-low-energy Threshold Germanium Spectrometers

    CERN Document Server

    Aalseth, Craig E; Fast, James E; Hossbach, Todd W; Orrell, John L; Overman, Cory T; Vandevender, Brent A

    2012-01-01

    This paper presents progress on the development of a cryostat intended to improve upon the low-energy threshold (below 0.5 keV) of p-type point contact germanium gamma-ray spectrometers. Ultra-low energy thresholds are important in the detection of low-energy nuclear recoils, an event class relevant to both dark matter direct detection and measurement of coherent neutrino-nucleus scattering. The cryostat design, including a thermal and electrical-field model, is given. A prototype cryostat has been assembled and data acquired to evaluate its vacuum and thermal performance.

  14. Uniaxially stressed germanium with fundamental direct band gap

    OpenAIRE

    Geiger, R.; Zabel, T.; Marin, E; Gassenq, A.; Hartmann, J.-M.; Widiez, J.; Escalante, J.; Guilloy, K.; Pauc, N.; Rouchon, D.; Diaz, G. Osvaldo; Tardif, S; Rieutord, F.; Duchemin, I.; Niquet, Y. -M.

    2015-01-01

    We demonstrate the crossover from indirect- to direct band gap in tensile-strained germanium by temperature-dependent photoluminescence. The samples are strained microbridges that enhance a biaxial strain of 0.16% up to 3.6% uniaxial tensile strain. Cooling the bridges to 20 K increases the uniaxial strain up to a maximum of 5.4%. Temperature-dependent photoluminescence reveals the crossover to a fundamental direct band gap to occur between 4.0% and 4.5%. Our data are in good agreement with n...

  15. Band Anticrossing in Dilute Germanium Carbides Using Hybrid Functionals

    CERN Document Server

    Stephenson, Chad A; Qi, Meng; Penninger, Michael; Schneider, William; Wistey, Mark A

    2014-01-01

    Dilute germanium carbides (Ge1-xCx) offer a direct bandgap for compact silicon photonics, but widely varying results have been reported. This work uses ab initio simulations with HSE06 hybrid functionals and spin-orbit coupling to study the band structure behavior in the absence of defects. Contrary to Vegard's law, the conduction band minimum at k=0 is consistently found to decrease with increasing C content, while L and X valleys remain nearly unchanged. A vanishing bandgap was observed for all alloys with x>0.017. Conduction bands deviate from a constant-potential band anticrossing model except near the center of the Brillouin zone.

  16. Analysis of defect formation in semiconductor cryogenic bolometric detectors created by heavy dark matter

    CERN Document Server

    Lazanu, Ionel; Lazanu, Sorina

    2012-01-01

    The cryogenic detectors in the form of bolometers are presently used for different applications, in particular for very rare or hypothetical events associated with new forms of matter, specifically related to the existence of Dark Matter. In the detection of particles with a semiconductor as target and detector, usually two signals are measured: ionization and heat. The amplification of the thermal signal is obtained with the prescriptions from Luke-Neganov effect. The energy deposited in the semiconductor lattice as stable defects in the form of Frenkel pairs at cryogenic temperatures, following the interaction of a dark matter particle, is evaluated and consequences for measured quantities are discussed. This contribution is included in the energy balance of the Luke effect. Applying the present model to germanium and silicon, we found that for the same incident weakly interacting massive particle the energy deposited in defects in germanium is about twice the value for silicon.

  17. An assessment of radiation damage in space-based germanium detectors due to solar proton events

    NARCIS (Netherlands)

    Owens, Alan; Brandenburg, S.; Buis, E. -J.; Kliewiet, H.; Kraft, S.; Ostendorf, R. W.; Peacock, A.; Quarati, F.; Quirin, P.

    2007-01-01

    Radiation effects caused by solar proton events will be a common problem for many types of sensors on missions to the inner solar system because of the long cruise phases coupled with the inverse square scaling of solar particle events. As part of a study in support of the BepiColombo mission to Mer

  18. Differentiating hidden sector dark matter from light WIMPs with Germanium detectors

    CERN Document Server

    Foot, R

    2012-01-01

    Light WIMP dark matter and hidden sector dark matter have been proposed to explain the DAMA, CoGeNT and CRESST-II data. Both of these approaches feature spin independent elastic scattering of dark matter particles on nuclei. Light WIMP dark matter invokes a single particle species which interacts with ordinary matter via contact interactions. By contrast hidden sector dark matter is typically multi-component and is assumed to interact via the exchange of a massless mediator. Such hidden sector dark matter thereby predicts a sharply rising nuclear recoil spectrum, $dR/dE_R \\sim 1/E_R^2$ due to this dynamics, while WIMP dark matter predicts a spectrum which depends sensitively on the WIMP mass, $m_\\chi$. We compare and contrast these two very different possible origins of the CoGeNT low energy excess. In the relevant energy range, the recoil spectra predicted by these two theories approximately agree provided $m_\\chi \\simeq 8.5$ GeV - close to the value favoured from fits to the CoGeNT and CDMS low energy data....

  19. Recrystallization behavior of high purity aluminum at 300 ℃

    Institute of Scientific and Technical Information of China (English)

    DU Yu-xuan; ZHANG Xin-ming; YE Ling-ying; LUO Zhi-hui

    2006-01-01

    The recrystallization behavior of 98.5% cold rolled high purity aluminum foils annealed at 300 ℃ was investigated, and the evolution of the microstructures was followed by electron back scattered diffraction(EBSD). The results show that the recrystallization process of the high purity aluminum foils at 300 ℃ is a mixture of discontinuous- and continuous-recrystallization.The orientations of the recrystallization nuclei include not only the cube orientation, but also other orientations such as some near deformation texture components which are the results of strong recovery process. However, such continuously recrystallized grains are usually associated with relatively high free energy, so they would be consumed by the discontinuously-recrystallized grains (cube-oriented grains) in subsequent annealing. On the other hand, the pattern quality index of recrystallized grains shows dependence on the crystal orientation which might introduce some errors into evaluating volume fraction of recrystallization by integrating pattern quality index of EBSD.

  20. Effects of Completeness and Purity on Cluster Dark Energy Constraints

    CERN Document Server

    Aguena, Michel

    2016-01-01

    The statistical properties of galaxy clusters can only be used for cosmological purposes if observational effects related to cluster detection are accurately characterized. These effects include the selection function associated to cluster finder algorithms and survey strategy. The importance of the selection becomes apparent when different cluster finders are applied to the same galaxy catalog, producing different cluster samples. We consider parametrized functional forms for the observable-mass relation, its scatter as well as the completeness and purity of cluster samples, and study how prior knowledge on these function parameters affects dark energy constraints derived from cluster statistics. Under the assumption that completeness and purity reach 50 % at masses around 10^{13.5} Msun/h, we find that self-calibration of selection parameters in current and upcoming cluster surveys is possible, while still allowing for competitive dark energy constraints. We consider a fiducial survey with specifications si...

  1. Entanglement, Purity, and Information Entropies in Continuous Variable Systems

    CERN Document Server

    Adesso, G; Illuminati, F; Adesso, Gerardo; Serafini, Alessio; Illuminati, Fabrizio

    2005-01-01

    Quantum entanglement of pure states of a bipartite system is defined as the amount of local or marginal ({\\em i.e.}referring to the subsystems) entropy. For mixed states this identification vanishes, since the global loss of information about the state makes it impossible to distinguish between quantum and classical correlations. Here we show how the joint knowledge of the global and marginal degrees of information of a quantum state, quantified by the purities or in general by information entropies, provides an accurate characterization of its entanglement. In particular, for Gaussian states of continuous variable systems, we classify the entanglement of two--mode states according to their degree of total and partial mixedness, comparing the different roles played by the purity and the generalized $p-$entropies in quantifying the mixedness and bounding the entanglement. We prove the existence of strict upper and lower bounds on the entanglement and the existence of extremally (maximally and minimally) entang...

  2. Characterization of low-purity clays for geopolymer binder formulation

    Science.gov (United States)

    Mostafa, Nasser Y.; Mohsen, Q.; El-maghraby, A.

    2014-06-01

    The production of geopolymer binders from low-purity clays was investigated. Three low-purity clays were calcined at 750°C for 4 h. The calcined clays were chemically activated by the alkaline solutions of NaOH and Na2SiO3. The compressive strength was measured as a function of curing time at room temperature and 85°C. The results were compared with those of a pure kaolin sample. An amorphous aluminosilicate polymer was formed in all binders at both processing temperatures. The results show that, the mechanical properties depend on the type and amount of active aluminum silicates in the starting clay material, the impurities, and the processing temperature.

  3. Characterization of low-purity clays for geopolymer binder formulation

    Institute of Scientific and Technical Information of China (English)

    Nasser Y.Mostafa; Q.Mohsen; A.El-maghraby

    2014-01-01

    The production of geopolymer binders from low-purity clays was investigated. Three low-purity clays were calcined at 750°C for 4 h. The calcined clays were chemically activated by the alkaline solutions of NaOH and Na2SiO3. The compressive strength was measured as a function of curing time at room temperature and 85°C. The results were compared with those of a pure kaolin sample. An amorphous aluminosilicate polymer was formed in all binders at both processing temperatures. The results show that, the mechanical properties depend on the type and amount of active aluminum silicates in the starting clay material, the impurities, and the processing temperature.

  4. Electrophoresis for the analysis of heparin purity and quality.

    Science.gov (United States)

    Volpi, Nicola; Maccari, Francesca; Suwan, Jiraporn; Linhardt, Robert J

    2012-06-01

    The adulteration of raw heparin with oversulfated chondroitin sulfate (OSCS) in 2007-2008 produced a global crisis resulting in extensive revisions to the pharmacopeia monographs and prompting the FDA to recommend the development of additional methods for the analysis of heparin purity. As a consequence, a wide variety of innovative analytical approaches have been developed for the quality assurance and purity of unfractionated and low-molecular-weight heparins. This review discusses recent developments in electrophoresis techniques available for the sensitive separation, detection, and partial structural characterization of heparin contaminants. In particular, this review summarizes recent publications on heparin quality and related impurity analysis using electrophoretic separations such as capillary electrophoresis (CE) of intact polysaccharides and hexosamines derived from their acidic hydrolysis, and polyacrylamide gel electrophoresis (PAGE) for the separation of heparin samples without and in the presence of its relatively specific depolymerization process with nitrous acid treatment.

  5. Tainting the soul: purity concerns predict moral judgments of suicide.

    Science.gov (United States)

    Rottman, Joshua; Kelemen, Deborah; Young, Liane

    2014-02-01

    Moral violations are typically defined as actions that harm others. However, suicide is considered immoral even though the perpetrator is also the victim. To determine whether concerns about purity rather than harm predict moral condemnation of suicide, we presented American adults with obituaries describing suicide or homicide victims. While harm was the only variable predicting moral judgments of homicide, perceived harm (toward others, the self, or God) did not significantly account for variance in moral judgments of suicide. Instead, regardless of political and religious views and contrary to explicit beliefs about their own moral judgments, participants were more likely to morally condemn suicide if they (i) believed suicide tainted the victims' souls, (ii) reported greater concerns about purity in an independent questionnaire, (iii) experienced more disgust in response to the obituaries, or (iv) reported greater trait disgust. Thus, suicide is deemed immoral to the extent that it is considered impure.

  6. Calorimeter detectors

    CERN Document Server

    de Barbaro, P; The ATLAS collaboration

    2013-01-01

    Although the instantaneous and integrated luminosity in HL-LHC will be far higher than the LHC detectors were originally designed for, the Barrel calorimeters of the four experiments are expected to continue to perform well  throughout the Phase II program. The conditions for the End-Cap calorimeters are far more challenging and whilst some detectors will require relatively modest changes, others require far more substantial upgrades. We present the results of longevity and performance studies for the calorimeter systems of the four main LHC experiments and outline the upgrade options under consideration. We include a discussion of the R&D required to make the final technology choices for the upgraded detectors.

  7. Pixel detectors

    CERN Document Server

    Passmore, M S

    2001-01-01

    positions on the detector. The loss of secondary electrons follows the profile of the detector and increases with higher energy ions. studies of the spatial resolution predict a value of 5.3 lp/mm. The image noise in photon counting systems is investigated theoretically and experimentally and is shown to be given by Poisson statistics. The rate capability of the LAD1 was measured to be 250 kHz per pixel. Theoretical and experimental studies of the difference in contrast for ideal charge integrating and photon counting imaging systems were carried out. It is shown that the contrast differs and that for the conventional definition (contrast = (background - signal)/background) the photon counting device will, in some cases, always give a better contrast than the integrating system. Simulations in MEDICI are combined with analytical calculations to investigate charge collection efficiencies (CCE) in semiconductor detectors. Different pixel sizes and biasing conditions are considered. The results show charge shari...

  8. Inference of conversion and purity for ETBE reactive distillation

    Directory of Open Access Journals (Sweden)

    Tian Yu-Chu

    2000-12-01

    Full Text Available Reactive distillation (RD, an unconventional and attractive technique, has been applied in fuel ether production. A typical application of RD is the synthesis of the widely used methyl tert-butyl ether (MTBE. RD has also been found to have potential to produce high quality ethyl tert-butyl ether (ETBE, a potential alternative to MTBE. A RD process integrates conventional reaction and separation into a single unit, resulting in extra complexity and dual process objectives, i.e. maximization of reactant conversion and purity of products. The conversion and the purity are thus important variables to be controlled in RD of ETBE. Unfortunately, both of them are not economically and reliably available for closed-loop control. This study aims to develop an effective method to infer the conversion and the purity from multiple temperature measurements that are easily available on-line and in real time. Nonlinear inferential models are recommended for ETBE synthesis with a ten-stage pilot scale RD column. The models are two-variable third-order regressive models, in which the temperature measurements of the reboiler and the bottom reactive section are employed. Experimental design, model identification, and model testing are also investigated.

  9. Impact of precursor purity on optical properties and radiation detection of CsI:Tl scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Saengkaew, Phannee; Cheewajaroen, Kulthawat; Yenchai, Chadet; Thong-aram, Decho [Chulalongkorn University, Department of Nuclear Engineering, Faculty of Engineering, Bangkok (Thailand); Sanorpim, Sakuntam [Chulalongkorn University, Department of Physics, Faculty of Science, Bangkok (Thailand); Jitpukdee, Manit [Kasetsart University, Department of Applied Radiation and Isotope, Faculty of Science, Bangkok (Thailand); Yordsri, Visittapong; Thanachayanont, Chanchana [Ministry of Science and Technology, National Metal and Materials Technology Center, National Science and Technology Development Agency, Pathumthani (Thailand); Nuntawong, Noppadon [Ministry of Science and Technology, National Electronic and Computer Technology Center, National Science and Technology Development Agency, Pathumthani (Thailand)

    2016-08-15

    Cesium iodide doped with thallium (CsI:Tl) crystals was grown to develop the gamma-ray detectors by using low-cost raw materials. Effect of impurities on optical properties and radiation detection performance was investigated. By a modified homemade Bridgman-Stockbarger technique, CsI:Tl samples were grown in two levels of CsI and TlI reactant materials, i.e., having as a very high purity of 99.999 % and a high purity of 99.9 %. XRD measurements indicate CsI:Tl crystals having a good quality with a dominant (110) plane. Having a cubic structure, a lattice constant of CsI crystals of 0.4574 nm and a crystallite size of 43.539 nm were obtained. From the lower-purity raw materials, calcite was found in an orange crystal with a lattice constant of 0.4560 nm and a crystallite size of 43.089 nm. By PL measurements, the optical properties of the CsI:Tl crystals were analyzed. ∝540-nm-wavelength PL peak was observed from the colorless high-purity crystal, and ∝600-nm-wavelength PL peak was observed from the orange crystal. The brighter PL emission was obtained from the orange crystals suggesting impurities. CsI:Tl surface morphology by SEM exhibited a smooth surface with some parallel crystal facets. For electrical properties of high-quality CsI:Tl crystals, the electrical resistances were 230 ± 16 MΩ in cross-sectional direction and 714 ± 136 MΩ in vertical direction with respect to more homogeneous crystal quality in cross-sectional direction than that in vertical direction. TEM measurement was applied to evaluate the microstructure of colorless CsI:Tl crystal with different patterns of a cubic structure. Both CsI:Tl crystals show good efficiencies and good resolutions. Maintaining the same electronic conditions and amplifications, the colorless CsI:Tl scintillators represented a higher detection efficiency at 122 keV of Co-57 of 78.4 % and the energy resolution of 23.3 % compared to the detection efficiency of 75.9 % and the energy resolution of 34.6 % of the

  10. Germanium electroabsorption devices on silicon for optical interconnects

    Science.gov (United States)

    Kuo, Yu-Hsuan; Miller, David A. B.; Harris, James S.

    2006-02-01

    Monolithic integration of both electronic and optic components into a silicon-based platform will provide high-speed optical interconnects and solve the power-bandwidth limitations. However, the lack of strong optical effects in silicon has limited the progress in the transmitter-end applications. Recently our research had demonstrated strong quantum-confined Stark effect (QCSE) in germanium quantum-well modulators on silicon. This first strong physical mechanism for group-IV photonics has a comparable behavior to III-V material systems. With proper quantum well structure design, we also demonstrated QCSE in C-band for long distance communications with CMOS-operational temperatures. The device fabrication is also compatible with standard silicon chip processes. Since the QCSE, a type of electroabsorption effect, requires much shorter optical length, it is suitable for device miniaturizations and possible for use in both lateral and vertical modulator configurations. Moreover, silicon-germanium electroabsorption modulators are inherently photodetectors, this advantage will enable efficient transmitter/receiver applications for optical interconnects.

  11. Superconductivity and unexpected chemistry of germanium hydrides under pressure

    Science.gov (United States)

    Davari Esfahani, M. Mahdi; Oganov, Artem R.; Niu, Haiyang; Zhang, Jin

    2017-04-01

    Following the idea that hydrogen-rich compounds might be high-Tc superconductors at high pressures, and the very recent breakthrough in predicting and synthesizing hydrogen sulfide with record-high Tc=203 K , an ab initio evolutionary algorithm for crystal structure prediction was employed to find stable germanium hydrides. In addition to the earlier structure of germane with space group Ama2, we propose a C2/m structure, which is energetically more favorable at pressures above 278 GPa (with inclusion of zero-point energy). Our calculations indicate that the C2/m phase of germane is a superconductor with Tc=67 K at 280 GPa. Germane is found to become thermodynamically unstable to decomposition to hydrogen and the compound Ge3H11 at pressures above 300 GPa. Ge3H11 with space group I 4 ¯m 2 is found to become stable at above 285 GPa with Tc=43 K . We find that the pressure-induced phase stability of germanium hydrides is distinct from analogous isoelectronic systems, e.g., Si hydrides and Sn hydrides. Superconductivity stems from large electron-phonon coupling associated with the wagging, bending, and stretching intermediate-frequency modes derived mainly from hydrogen.

  12. Materials and Fabrication Issues for Large Machined Germanium Immersion Gratings

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmenko, P J; Davis, P J; Little, S L; Hale, L C

    2006-05-22

    LLNL has successfully fabricated small (1.5 cm{sup 2} area) germanium immersion gratings. We studied the feasibility of producing a large germanium immersion grating by means of single point diamond flycutting. Our baseline design is a 63.4o blaze echelle with a 6 cm beam diameter. Birefringence and refractive index inhomogeneity due to stresses produced by the crystal growth process are of concern. Careful selection of the grating blank and possibly additional annealing to relieve stress will be required. The Large Optics Diamond Turning Machine (LODTM) at LLNL is a good choice for the fabrication. It can handle parts up to 1.5 meter in diameter and 0.5 meter in length and is capable of a surface figure accuracy of better than 28 nm rms. We will describe the machine modifications and the machining process for a large grating. A next generation machine, the Precision Optical Grinder and Lathe (POGAL), currently under development has tighter specifications and could produce large gratings with higher precision.

  13. Reduction of phosphorus diffusion in germanium by fluorine implantation

    Science.gov (United States)

    El Mubarek, H. A. W.

    2013-12-01

    The control of phosphorus (P) diffusion in germanium (Ge) is essential for the realisation of ultrashallow n-type junctions in Ge. This work reports a detailed study of the effect of fluorine (F) co-implantation on P diffusion in Ge. P and F profiles were characterized by secondary ion mass spectroscopy. The ion implantation damage was investigated using cross sectional transmission electron microscopy. It is shown that F co-implantation reduces the implanted P profile width and reduces both intrinsic and extrinsic P diffusion in Ge. A defect mediated mechanism for the strong influence of F co-implantation on P diffusion in Ge is proposed and invokes the formation of FnVm clusters in the F-amorphized Ge layer. A fraction of these FnVm clusters decorate the interstitial type end-of-range defects in the re-grown Ge layer and the rest react during re-growth with interstitial germanium atoms diffusing back from the amorphous crystalline interface. The Ge vacancies are then annihilated and mobile interstitial F is released and out diffuses from the surface. This results in a re-grown Ge layer which has a low vacancy concentration and in which the P diffusion rate is reduced. These results open the way to the realization of enhanced Ge n-type devices.

  14. Reduction of phosphorus diffusion in germanium by fluorine implantation

    Energy Technology Data Exchange (ETDEWEB)

    El Mubarek, H. A. W. [School of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL (United Kingdom)

    2013-12-14

    The control of phosphorus (P) diffusion in germanium (Ge) is essential for the realisation of ultrashallow n-type junctions in Ge. This work reports a detailed study of the effect of fluorine (F) co-implantation on P diffusion in Ge. P and F profiles were characterized by secondary ion mass spectroscopy. The ion implantation damage was investigated using cross sectional transmission electron microscopy. It is shown that F co-implantation reduces the implanted P profile width and reduces both intrinsic and extrinsic P diffusion in Ge. A defect mediated mechanism for the strong influence of F co-implantation on P diffusion in Ge is proposed and invokes the formation of F{sub n}V{sub m} clusters in the F-amorphized Ge layer. A fraction of these F{sub n}V{sub m} clusters decorate the interstitial type end-of-range defects in the re-grown Ge layer and the rest react during re-growth with interstitial germanium atoms diffusing back from the amorphous crystalline interface. The Ge vacancies are then annihilated and mobile interstitial F is released and out diffuses from the surface. This results in a re-grown Ge layer which has a low vacancy concentration and in which the P diffusion rate is reduced. These results open the way to the realization of enhanced Ge n-type devices.

  15. Structural and electronic properties of hybrid silicon-germanium nanosheets

    Directory of Open Access Journals (Sweden)

    F. L. Pérez Sánchez

    2014-12-01

    Full Text Available Using first principles molecular calculations, based on the Density Functional Theory (DFT, structural and electronic properties of hybrid graphene—like silicon—germanium circular nanosheets of hexagonal symmetry are investigated. The exchange—correlation functional of Perdew—Wang (PW in the local spin density approximation (LSDA based on the pseudopotentials of Dolg—Bergnre is applied. The finite extension nanosheets are represented by the CnHm—like cluster model with mono—hydrogenated armchair edges. Changes of the physicochemical properties were analyzed to learn on the chemical composition. We have obtained that the corrugation of the hybrid nanosheets is maintained (with respect to the pristine nanosheets of Ge and Si and is more pronounced when there is a high percentage of germanium. Moreover, hybrid nanosheets have ionic bonds (polarity in the interval from 0.18 to 0.77 D and exhibit a semimetal behavior. Three types of chemical compositions are considered: 1 the one—one relationship, 2 formation of Ge dimers and 3 formation of Ge hexagons. In each case it is observed an increase in the chemical reactivity. Finally, analyzing the work function we conclude that in cases 1 and 2 the chemical compositions improve the efficiency of the field emission and thereby they could expand the scope of nanotechnology applications.

  16. Assessment of radiochemical purity of [{sup 18}F]fludeoxyglucose by high pressure liquid chromatography (HPLC)

    Energy Technology Data Exchange (ETDEWEB)

    Lacerda, Aline E.; Silva, Juliana B.; Silveira, Marina B.; Ferreira, Soraya Z., E-mail: radiofarmacoscdtn@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Unidade de Pesquisa e Producao de Radiofarmacos

    2011-07-01

    The quality control of [{sup 18}F]fludeoxyglucose ({sup 18}FDG) has received attention due to its increasing clinical use. Although the quality requirements of {sup 18}FDG are established in various pharmacopoeia, the suitability of all testing methods used should be verified under actual conditions of use and documented. The aim of this study was to develop a high pressure liquid chromatography (HPLC) method for radiochemical purity evaluation of {sup 18}FDG, based on pharmacopoeia references, and to verify its suitability for routine quality control in our centre. HPLC analysis was performed with an Agilent HPLC. {sup 18}FDG and impurities were separated on an anion-exchange column by isocratic elution with 0.1 M NaOH as the mobile phase. Detection was accomplished with refractive index and NaI (Tl) scintillation detectors. The flow rate of the mobile phase was set at 0.8 mL/min and the column temperature was kept at 35 deg C. Specificity, linearity, precision and robustness were assessed to verify if the method was adequate for its intended purpose. Retention time of {sup 18}FDG was not affected by the presence of other components of the formulation and a good peak resolution was achieved. The analytical curve of {sup 18}FDG was linear, with a correlation coefficient value of 0.9995. Intraday repeatable precision, reported as the relative standard deviation, was 0.11%. Analytical procedure remained unaffected by small variations in mobile phase flow rate. Results evidenced that HPLC is suitable for radiochemical purity evaluation of {sup 18}FDG, considering operational conditions of our laboratory. (author)

  17. HNIW纯度测定方法研究%Study on Determination Method of HNIW Purity

    Institute of Scientific and Technical Information of China (English)

    黄志萍; 曹庆玮; 郭兴玲

    2001-01-01

    对测定HNIW纯度的高效液相色谱法进行了研究。采用紫外分光光度检测器, YWG-C18硅胶键合相高效反相色谱柱,乙腈-水流动相,比较了校正曲线法、内标法和峰面积归一法等三种定量方法。结果表明,三种方法标准偏差均小于1%,但归一法准确度受条件限制; 内标法虽准确度较高而操作较为繁琐; 而校正曲线法不仅准确度较高且操作方便。建议采用校正曲线法测定HNIW纯度。%The high performance liquid chromatography (HPLC) to determine purity of hexanitrohexaazaisowurtzitane (HNIW) has been studied in this paper. The method is carried out with ultraviolet spectrophotometer as detector,YWG-C18 column,acetonitrile(CH3CN)-water mobile phase. The compared results of calibration curve method,internal standard method,normalization method show that the standard deviation of three methods is all below 1%,the accuracy of normalization method is restricted with condition, the internal standard method is difficult to be accomplished,though its accuracy is higher, the calibration curve method is easy to be operated and with higher accuracy. It is prefer to use calibration curve method to analyze purity of HNIW.

  18. Germanium ion implantation to Improve Crystallinity during Solid Phase Epitaxy and the effect of AMU Contamination

    Science.gov (United States)

    Lee, K. S.; Yoo, D. H.; Son, G. H.; Lee, C. H.; Noh, J. H.; Han, J. J.; Yu, Y. S.; Hyung, Y. W.; Yang, J. K.; Song, D. G.; Lim, T. J.; Kim, Y. K.; Lee, S. C.; Lee, H. D.; Moon, J. T.

    2006-11-01

    Germanium ion implantation was investigated for crystallinity enhancement during solid phase epitaxial regrowth (SPE) using high current implantation equipment. Electron back-scatter diffraction(EBSD) measurement showed numerical increase of 19 percent of signal, which might be due to pre-amorphization effect on silicon layer deposited by LPCVD process with germanium ion implantation. On the other hand, electrical property such as off-leakage current of NMOS transistor degraded in specific regions of wafers, which implied non-uniform distribution of donor-type impurities into channel area. It was confirmed that arsenic atoms were incorporated into silicon layer during germanium ion implantation. Since the equipment for germanium pre-amorphization implantation(PAI) was using several source gases such as BF3 and AsH3, atomic mass unit(AMU) contamination during PAI of germanium with AMU 74 caused the incorporation of arsenic with AMU 75 which resided in arc-chamber and other parts of the equipment. It was effective to use germanium isotope of AMU 72 to suppress AMU contamination, however it led serious reduction of productivity because of decrease in beam current by 30 percent as known to be difference in isotope abundance. It was effective to use enriched germanium source gas with AMU 72 in order to improve productivity. Spatial distribution of arsenic impurities in wafers was closely related to hardware configuration of ion implantation equipment.

  19. XMASS detector

    CERN Document Server

    Abe, K; Hiraide, K; Hirano, S; Kishimoto, Y; Kobayashi, K; Moriyama, S; Nakagawa, K; Nakahata, M; Nishiie, H; Ogawa, H; Oka, N; Sekiya, H; Shinozaki, A; Suzuki, Y; Takeda, A; Takachio, O; Ueshima, K; Umemoto, D; Yamashita, M; Yang, B S; Tasaka, S; Liu, J; Martens, K; Hosokawa, K; Miuchi, K; Murata, A; Onishi, Y; Otsuka, Y; Takeuchi, Y; Kim, Y H; Lee, K B; Lee, M K; Lee, J S; Fukuda, Y; Itow, Y; Nishitani, Y; Masuda, K; Takiya, H; Uchida, H; Kim, N Y; Kim, Y D; Kusaba, F; Motoki, D; Nishijima, K; Fujii, K; Murayama, I; Nakamura, S

    2013-01-01

    The XMASS project aims to detect dark matter, pp and $^{7}$Be solar neutrinos, and neutrinoless double beta decay using ultra pure liquid xenon. The first phase of the XMASS experiment searches for dark matter. In this paper, we describe the XMASS detector in detail, including its configuration, data acquisition equipment and calibration system.

  20. XMASS detector

    Energy Technology Data Exchange (ETDEWEB)

    Abe, K. [Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205 (Japan); Kavli Institute for the Physics and Mathematics of the Universe, the University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Hieda, K. [Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205 (Japan); Hiraide, K. [Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205 (Japan); Kavli Institute for the Physics and Mathematics of the Universe, the University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Hirano, S. [Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205 (Japan); Kishimoto, Y.; Kobayashi, K.; Moriyama, S. [Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205 (Japan); Kavli Institute for the Physics and Mathematics of the Universe, the University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Nakagawa, K. [Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205 (Japan); Nakahata, M. [Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205 (Japan); Kavli Institute for the Physics and Mathematics of the Universe, the University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Nishiie, H. [Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205 (Japan); Ogawa, H. [Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205 (Japan); Kavli Institute for the Physics and Mathematics of the Universe, the University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); and others

    2013-07-11

    The XMASS project aims to detect dark matter, pp and {sup 7}Be solar neutrinos, and neutrinoless double beta decay using ultra pure liquid xenon. The first phase of the XMASS experiment searches for dark matter. In this paper, we describe the XMASS detector in detail, including its configuration, data acquisition equipment and calibration system.

  1. Temperature dependence of continuum and time resolved photoluminescence of germanium nanostructures

    Directory of Open Access Journals (Sweden)

    M Ardyanian

    2011-12-01

    Full Text Available   Germanium nanostructures were generated in the post annealed germanium oxide thin films. Visible and near infrared photoluminescence bands were observed in the samples annealed at 350°C and 400°C, respectively. These different luminescence ranges are attributed to the presence of the defects in oxide matrix and quantum confinement effect in the germanium nanostructures, respectively. Decay time and temperature dependence of the luminescence for different bands were investigated, which confirmed our idea about the origin of the luminescence.

  2. Pulse Rise Time Characterization of a High Pressure Xenon Gamma Detector for use in Resolution Enhancement

    CERN Document Server

    Troyer, G L

    2000-01-01

    High pressure xenon ionization chamber detectors are possible alternatives to traditional thallium doped sodium iodide (NaI(Tl)) and hyperpure germanium as gamma spectrometers in certain applications. Xenon detectors incorporating a Frisch grid exhibit energy resolutions comparable to cadmium/zinc/telluride (CZT) (e.g. 2% (at) 662keV) but with far greater sensitive volumes. The Frisch grid reduces the position dependence of the anode pulse risetimes, but it also increases the detector vibration sensitivity, anode capacitance, voltage requirements and mechanical complexity. We have been investigating the possibility of eliminating the grid electrode in high-pressure xenon detectors and preserving the high energy resolution using electronic risetime compensation methods. A two-electrode cylindrical high pressure xenon gamma detector coupled to time-to-amplitude conversion electronics was used to characterize the pulse rise time of deposited gamma photons. Time discrimination was used to characterize the pulse r...

  3. Position resolution of the prototype AGATA triple-cluster detector from an in-beam experiment

    Energy Technology Data Exchange (ETDEWEB)

    Recchia, F. [Dipartimento di Fisica dell' Universita di Padova, Padova (Italy); INFN Sezione di Padova, Padova (Italy)], E-mail: francesco.recchia@pd.infn.it; Bazzacco, D.; Farnea, E. [INFN Sezione di Padova, Padova (Italy); Gadea, A. [INFN Laboratori Nazionali di Legnaro, Legnaro (Italy); IFIC, CSIC - University of Valencia, Valencia (Spain); Venturelli, R. [INFN Sezione di Padova, Padova (Italy); Beck, T. [Gesellschaft fuer Schwerionenforschung, Darmstadt (Germany); Bednarczyk, P. [IFJ PAN, PL-31-342 Krakow (Poland); Buerger, A. [CEA Saclay, DAPNIA/SPhN, F-91191 Gif-sur-Yvette Cedex (France); Dewald, A. [Institut fuer Kernphysik, Universitaet zu Koeln, Koeln (Germany); Dimmock, M. [Oliver Lodge Laboratory, University of Liverpool, Liverpool (United Kingdom); Duchene, G. [Laboratoire Pluridisciplinaire Hubert Curien, CNRS-IN2P3/ULP Strasbourg, Strasbourg (France); Eberth, J. [Institut fuer Kernphysik, Universitaet zu Koeln, Koeln (Germany); Faul, T. [Laboratoire Pluridisciplinaire Hubert Curien, CNRS-IN2P3/ULP Strasbourg, Strasbourg (France); Gerl, J. [Gesellschaft fuer Schwerionenforschung, Darmstadt (Germany); Gernhaeuser, R. [INFN Laboratori Nazionali di Legnaro, Legnaro (Italy); Hauschild, K. [CSNSM, IN2P3-CNRS, Orsay Campus (France); Holler, A. [Institut fuer Kernphysik, Universitaet zu Koeln, Koeln (Germany); Jones, P. [Department of Physics, University of Jyvaeskylae, Jyvaeskylae (Finland); Korten, W. [CEA Saclay, DAPNIA/SPhN, F-91191 Gif-sur-Yvette Cedex (France); Kroell, Th. [Technische Universitaet Muenchen, Garching (Germany)] (and others)

    2009-06-11

    AGATA belongs to a new generation of {gamma}-ray detector arrays for nuclear spectroscopy at present in its final stage of development. The detectors of these new arrays will be based on 36-fold electronically segmented coaxial germanium diodes operated in position sensitive mode. An in-beam test of the AGATA prototype triple cluster detector was carried out with the purpose of demonstrating the feasibility of such detectors and in order to measure the most sensitive parameters for their overall performance. An inverse kinematics reaction was performed, using a {sup 48}Ti beam at an energy of 100 MeV, impinging on a deuterated titanium target. The results from the analysis of the experimental data, compared with the predictions of Monte Carlo simulations, give an estimation of the position sensitivity of these detectors of about 5 mm FWHM, consistent with the specifications required.

  4. Reducing multiplexing artifacts in multi-pinhole SPECT with a stacked silicon-germanium system: a simulation study.

    Science.gov (United States)

    Johnson, Lindsay C; Shokouhi, Sepideh; Peterson, Todd E

    2014-12-01

    In pinhole single photon emission computed tomography (SPECT), multi-pinhole collimators can increase sensitivity but may lead to projection overlap, or multiplexing, which can cause image artifacts. In this work, we explore whether a stacked-detector configuration with a germanium and a silicon detector, used with 123I (27-32, 159 keV), where little multiplexing occurs in the Si projections, can reduce image artifacts caused by highly-multiplexed Ge projections. Simulations are first used to determine a reconstruction method that combines the Si and Ge projections to maximize image quality. Next, simulations of different pinhole configurations (varying projection multiplexing) in conjunction with digital phantoms are used to examine whether additional Si projections mitigate artifacts from the multiplexing in the Ge projections. Reconstructed images using both Si and Ge data are compared to those using Ge data alone. Normalized mean-square error and normalized standard deviation provide a quantitative evaluation of reconstructed images' error and noise, respectively, and are used to evaluate the impact of the additional nonmultiplexed data on image quality. For a qualitative comparison, the differential point response function is used to examine multiplexing artifacts. Results show that in cases of highly-multiplexed Ge projections, the addition of low-multiplexed Si projections helps to reduce image artifacts both quantitatively and qualitatively.

  5. Semiconductor Detectors; Detectores de Semiconductores

    Energy Technology Data Exchange (ETDEWEB)

    Cortina, E.

    2007-07-01

    Particle detectors based on semiconductor materials are among the few devices used for particle detection that are available to the public at large. In fact we are surrounded by them in our daily lives: they are used in photoelectric cells for opening doors, in digital photographic and video camera, and in bar code readers at supermarket cash registers. (Author)

  6. Constraining solar hidden photons using HPGe detector

    Energy Technology Data Exchange (ETDEWEB)

    Horvat, R.; Kekez, D., E-mail: Dalibor.Kekez@irb.hr; Krčmar, M.; Krečak, Z.; Ljubičić, A.

    2013-04-25

    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 χ>(2.2×10{sup −13}–3×10{sup −7}) in the mass region 0.2 eV≲m{sub γ{sup ′}}≲30 keV. Our constraints on the mixing parameter χ 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.

  7. Silicon carbide detector for laser-generated plasma radiation

    Science.gov (United States)

    Bertuccio, Giuseppe; Puglisi, Donatella; Torrisi, Lorenzo; Lanzieri, Claudio

    2013-05-01

    We present the performance of a Silicon Carbide (SiC) detector in the acquisition of the radiation emitted by laser generated plasmas. The detector has been employed in time of flight (TOF) configuration within an experiment performed at the Prague Asterix Laser System (PALS). The detector is a 5 mm2 area 100 nm thick circular Nisbnd SiC Schottky junction on a high purity 4Hsbnd SiC epitaxial layer 115 μm thick. Current signals from the detector with amplitudes up to 1.6 A have been measured, achieving voltage signals over 80 V on a 50 Ω load resistance with excellent signal to noise ratios. Resolution of few nanoseconds has been experimentally demonstrated in TOF measurements. The detector has operated at 250 V DC bias under extreme operating conditions with no observable performance degradation.

  8. Improved methods to determine radionuclidic purity of F-18 compounds

    DEFF Research Database (Denmark)

    Jørgensen, Thomas; Micheelsen, Mille Ankerstjerne; Jensen, Mikael

    2012-01-01

    Current revisions of monographs for F-18 pharmaceuticals in the European Pharmacopoeia (Ph. Eur.) (Ph. Eur., 2011) call for a radionuclidic purity (RNP) of or better than 99.9%. However, the current method is not sufficient nor effective for testing this required RNP level. We present a theoretical...... model leading to a practical procedure for a simple test of RNP for F-18 compounds that tells whether or not the sample is pure with a statistical confidence of 97.5% (P=0.975). (C) 2011 Elsevier Ltd. All rights reserved....

  9. Competitive growth of high purity aluminum grains in directional solidification

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jiao; SHU Da; WANG De-lin; SUN Bao-de; CHEN Gang

    2006-01-01

    A self-made directional solidification setup was used to prepare high purity aluminum ingots of 100mm in diameter. The morphology of the growth interface was detected by SEM and AFM, and the grain lattice orientation was detected by XRD. The results indicate that the grains suffer competitive growth under any conditions in experiments. The lattice orientation of the preferred grains is determined by the flow field above the solid-liquid interface. The horizontal lattice position does not change during the growth process. However, the lattice orientation in the growth direction varies with the growth velocity and approaches to [100]gradually during the growth process.

  10. Textures in high purity aluminum foils and AA3004 sheets

    Institute of Scientific and Technical Information of China (English)

    肖亚庆; 张新明; 唐建国; 邓运来; 陈志永

    2003-01-01

    The simulation of rolling texture with "minimum shear principle" and the strengthening of cube recrystallization texture by inhomogeneous rolling, low strain deformation and multistage annealing, of the formation and evolution of texture in high purity Al were presented. The plastic anisotropy of crystalline materials were also summarized, including determination of the co-yield surfaces and condition of slipping as well as mechanical twinning, prediction of plastic anisotropy of deep drawing with modified Tuckers method, evolution of earing behavior of Al alloy sheets for deep drawing with CMTP approach, and construction of texture balance design and some technologies to suppress plastic anisotropy in practical production.

  11. Young’s modulus of [111] germanium nanowires

    Directory of Open Access Journals (Sweden)

    M. Maksud

    2015-11-01

    Full Text Available This paper reports a diameter-independent Young’s modulus of 91.9 ± 8.2 GPa for [111] Germanium nanowires (Ge NWs. When the surface oxide layer is accounted for using a core-shell NW approximation, the YM of the Ge core approaches a near theoretical value of 147.6 ± 23.4 GPa. The ultimate strength of a NW device was measured at 10.9 GPa, which represents a very high experimental-to-theoretical strength ratio of ∼75%. With increasing interest in this material system as a high-capacity lithium-ion battery anode, the presented data provide inputs that are essential in predicting its lithiation-induced stress fields and fracture behavior.

  12. Young’s modulus of [111] germanium nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Maksud, M.; Palapati, N. K. R.; Subramanian, A., E-mail: asubramanian@vcu.edu [Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Yoo, J. [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Harris, C. T. [Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    2015-11-01

    This paper reports a diameter-independent Young’s modulus of 91.9 ± 8.2 GPa for [111] Germanium nanowires (Ge NWs). When the surface oxide layer is accounted for using a core-shell NW approximation, the YM of the Ge core approaches a near theoretical value of 147.6 ± 23.4 GPa. The ultimate strength of a NW device was measured at 10.9 GPa, which represents a very high experimental-to-theoretical strength ratio of ∼75%. With increasing interest in this material system as a high-capacity lithium-ion battery anode, the presented data provide inputs that are essential in predicting its lithiation-induced stress fields and fracture behavior.

  13. Specific features of phase transformations in germanium monotelluride

    Energy Technology Data Exchange (ETDEWEB)

    Bigvava, A.D.; Gabedava, A.A.; Kunchuliya, Eh.D.; Shvangiradze, R.R.

    1981-12-01

    Phase transformations in germanium monotelluride are studied using DRON-0.5 and DRON-1 plants with high-temperature chamber GPVT-1500 at Cu, Ksub(..cap alpha..) radiation. It is shown that in the whole homogeneity range ..cap alpha.. GeTe is a metastable phase which is formed under the conditions of fast cooling of alloy from temperatures >=Tsub(cub) (temperature of transition in cubic crystal system). An equilibrium ..gamma..-phase is obtained by annealing of dispersed powders and metal-ceramic specimens of alloys with 50.3; 50.6; 50.9 at % Te. Lattice parameters of rhombic ..gamma..-phase do not depend on tellurium content in initial ..cap alpha..- phase. ..cap alpha --> gamma.. transformation is observed at any temperature less than Tsub(cub) with the change of alloy composition, namely tellurium precipitation. ..gamma..-phase transforms into ..beta.. at higher temperatures than ..cap alpha..-phase.

  14. Experimental investigation on oxidation kinetics of germanium by ozone

    Science.gov (United States)

    Wang, Xiaolei; Zhao, Zhiqian; Xiang, Jinjuan; Wang, Wenwu; Zhang, Jing; Zhao, Chao; Ye, Tianchun

    2016-12-01

    Oxidation kinetics of germanium surface by ozone at low temperature (≤400 °C) is experimentally investigated. The growth process contains two regions: initial linear growth region and following parabolic growth region. The GeOx thickness vs. oxidation time plot obeys the well-known Deal-Grove or linear parabolic model. The linear growth region contains reaction of oxygen atoms with surface bond and back bonds of outmost Ge layer. And the activation energy is experimentally estimated to be 0.06 eV. Such small activation energy indicates that the linear growth region is nearly barrier-less. The parabolic growth region starts when the oxygen atoms diffuse into back bonds of second outmost Ge layers. And the activation energy for this process is found to be 0.54 eV. Furthermore, in the ozone oxidation it is not O3 molecules but O radicals that go through the GeOx film.

  15. Laser-initiated explosive electron emission from flat germanium crystals

    Science.gov (United States)

    Porshyn, V.; Mingels, S.; Lützenkirchen-Hecht, D.; Müller, G.

    2016-07-01

    Flat Sb-doped germanium (100) crystals were investigated in the triode configuration under pulsed tunable laser illumination (pulse duration tlaser = 3.5 ns and photon energy hν = 0.54-5.90 eV) and under DC voltages 1 MW/cm2 corresponding to a high quantum efficiency up to 3.3% and cathode currents up to 417 A. This laser-induced explosive electron emission (EEE) from Ge was characterized by its voltage-, laser power- and hν-sensitivity. The analysis of the macroscopic surface damage caused by the EEE is included as well. Moreover, we have carried out first direct measurements of electron energy distributions produced during the EEE from the Ge samples. The measured electron spectra hint for electron excitations to the vacuum level of the bulk and emission from the plasma plume with an average kinetic energy of ˜0.8 eV.

  16. The impact of polishing on germanium-on-insulator substrates

    Institute of Scientific and Technical Information of China (English)

    Lin Wang; Ruan Yujiao; Chen Songyan; Li Cheng; Lai Hongkai; Huang Wei

    2013-01-01

    We prepared germanium-on-insulator (GOI) substrates by using Smart-CutTM and wafer bonding technology.The fabricated GOI is appropriate for polishing due to a strong bonding strength (2.4 MPa) and a sufficient bonding quality.We investigated mechanical polishing and chemical-mechanical polishing (CMP) systematically,and an appropriate polishing method-mechanical polishing combined with CMP-is obtained.As shown by AFM measurement,the RMS of GOI after polishing decreased to 0.543 nm.And the Ge peak profile of the XRD curve became symmetric,and the FWHM is about 121.7 arcsec,demonstrating a good crystal quality.

  17. Exceptional transport property in a rolled-up germanium tube

    Science.gov (United States)

    Guo, Qinglei; Wang, Gang; Chen, Da; Li, Gongjin; Huang, Gaoshan; Zhang, Miao; Wang, Xi; Mei, Yongfeng; Di, Zengfeng

    2017-03-01

    Tubular germanium (Ge) resistors are demonstrated by rolling-up thin Ge nanomembranes (NMs, 50 nm in thickness) with electrical contacts. The strain distribution of rolled-up Ge microtubes along the radial direction is investigated and predicted by utilizing micro-Raman scattering spectroscopy with two different excitation lasers. Electrical properties are characterized for both unreleased GeNMs and released/rolled-up Ge microtubes. The conductivities of GeNMs significantly decrease after rolling-up into tubular structures, which can be attributed to surface charging states on the conductance, band bending, and piezo-resistance effect. When illuminated with a light source, facilitated by the suppressed dark current of rolled-up Ge tubes, the corresponding signal-to-noise ratio can be dramatically enhanced compared with that of planar GeNMs.

  18. Wide band polarizer with suspended germanium resonant grating

    Institute of Scientific and Technical Information of China (English)

    Wugang Cao; Jianyong Ma; Changhe Zhou

    2012-01-01

    An ultra broad band polarizer that operates in the telecommunication wavelength band is proposed.This device,which consists of a single suspended germanium resonant grating layer,is designed using the inverse mathematical method and the rigorous vector diffraction theory.Calculated results indicate that the ultra broad band polarizer exhibits extremely high reflection (R > 99%) for TE polarization light and high transmission (T > 99%) for TM polarization at the wavelength range greater than 300 nm,and it has an extinction ratio of approximately 1 000 at the 1 550-nm central wavelength.The results of the rigorous coupled wave analysis indicate that the extremely wide band property of the TE polarization is caused by the excitation of strong modulation guided modes in the design wavelength range.

  19. Phosphorus diffusion in germanium following implantation and excimer laser annealing

    Science.gov (United States)

    Wang, Chen; Li, Cheng; Huang, Shihao; Lu, Weifang; Yan, Guangming; Zhang, Maotian; Wu, Huanda; Lin, Guangyang; Wei, Jiangbin; Huang, Wei; Lai, Hongkai; Chen, Songyan

    2014-05-01

    We focus our study on phosphorus diffusion in ion-implanted germanium after excimer laser annealing (ELA). An analytical model of laser annealing process is developed to predict the temperature profile and the melted depth in Ge. Based on the heat calculation of ELA, a phosphorus diffusion model has been proposed to predict the dopant profiles in Ge after ELA and fit SIMS profiles perfectly. A comparison between the current-voltage characteristics of Ge n+/p junctions formed by ELA at 250 mJ/cm2 and rapid thermal annealing at 650 °C for 15 s has been made, suggesting that ELA is promising for high performance Ge n+/p junctions.

  20. Anomalous compression behavior of germanium during phase transformation

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Xiaozhi [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203 (China); Tan, Dayong [Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203 (China); Guangzhou Institute of Geochemistry, Chinese Academic of Sciences, Guangzhou 510640 (China); Ren, Xiangting [Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203 (China); Yang, Wenge, E-mail: yangwg@hpstar.ac.cn, E-mail: duanweihe@scu.edu.cn [Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203 (China); High Pressure Synergetic Consortium (HPSynC), Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439 (United States); He, Duanwei, E-mail: yangwg@hpstar.ac.cn, E-mail: duanweihe@scu.edu.cn [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Institute of Fluid Physics and National Key Laboratory of Shockwave and Detonation Physic, China Academy of Engineering Physics, Mianyang 621900 (China); Mao, Ho-Kwang [Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203 (China); High Pressure Synergetic Consortium (HPSynC), Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439 (United States); Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015 (United States)

    2015-04-27

    In this article, we present the abnormal compression and plastic behavior of germanium during the pressure-induced cubic diamond to β-tin structure transition. Between 8.6 GPa and 13.8 GPa, in which pressure range both phases are co-existing, first softening and followed by hardening for both phases were observed via synchrotron x-ray diffraction and Raman spectroscopy. These unusual behaviors can be interpreted as the volume misfit between different phases. Following Eshelby, the strain energy density reaches the maximum in the middle of the transition zone, where the switch happens from softening to hardening. Insight into these mechanical properties during phase transformation is relevant for the understanding of plasticity and compressibility of crystal materials when different phases coexist during a phase transition.