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Sample records for germanium ge detectors

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

    NASA Astrophysics Data System (ADS)

    Maggioni, G.; Carturan, S.; Fiorese, L.; Pinto, N.; Caproli, F.; Napoli, D. R.; Giarola, M.; Mariotto, G.

    2017-01-01

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

  2. LArGe: Background suppression using liquid argon (LAr) scintillation for 0 νββ decay search with enriched germanium (Ge) detectors

    NASA Astrophysics Data System (ADS)

    Di Marco, M.; Peiffer, P.; Schönert, S.

    2007-10-01

    Measurements with a bare p-type high purity germanium diode (HPGe) submerged in a 19 kg liquid argon (LAr) scintillation detector at MPIK-Heidelberg are reported. The liquid argon-germanium system (LArGe) is operated as a 4 π anti-Compton spectrometer to suppress backgrounds in the HPGe. This R&D is carried out in the framework of the Gerda experiment which searches for 0 νββ decays with HPGe detectors enriched in 76Ge. The goal of this work is to develop a novel method to discriminate backgrounds in 0 νββ search which would ultimately allow to investigate the effective neutrino mass free of background events down to the inverse mass hierarchy scale. Other applications in low-background counting are expected.

  3. MAJORANA Collaboration's experience with germanium detectors

    DOE PAGES

    Mertens, S.; Abgrall, N.; Avignone, F. T.; ...

    2015-05-01

    The goal of the Majorana Demonstrator project is to search for 0νββ decay in 76Ge. Of all candidate isotopes for 0νββ, 76Ge has some of the most favorable characteristics. Germanium detectors are a well established technology, and in searches for 0νββ, 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®®. The process from production, to characterization and integration in MAJORANAmore » mounting structure will be described. A summary of the performance of all enriched germanium detectors will be given.« less

  4. MAJORANA Collaboration's experience with germanium detectors

    SciTech Connect

    Mertens, S.; Abgrall, N.; Avignone, F. T.; Barabash, A. S.; Bertrand, F. E.; Brudanin, V.; Busch, M.; Buuck, M.; Byram, D.; Caldwell, A. S.; Chan, Y. -D.; Christofferson, C. D.; Cuesta, C.; Detwiler, J. A.; Efremenko, Yu; Ejiri, H.; Elliott, S. R.; Galindo-Uribarri, A.; Giovanetti, G. K.; Goett, J.; Green, M. P.; Gruszko, J.; Guinn, I.; 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.; Meijer, S. J.; Orrell, J. L.; O'Shaughnessy, C.; Overman, N. R.; Poon, A. W. P.; Radford, D. C.; Rager, J.; Rielage, K.; Robertson, R. G. H.; Romero-Romero, E.; Ronquest, M. C.; Shanks, B.; Shirchenko, M.; Snyder, N.; 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.

    2015-05-01

    The goal of the Majorana Demonstrator project is to search for 0νββ decay in 76Ge. Of all candidate isotopes for 0νββ, 76Ge has some of the most favorable characteristics. Germanium detectors are a well established technology, and in searches for 0νββ, 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®®. 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.

  5. MAJORANA Collaboration's Experience with Germanium Detectors

    SciTech Connect

    Mertens, S.; Abgrall, N.; Avignone, III, F. T.; Bertrand, F. E.; Efremenko, Yuri; Galindo-Uribarri, A; Radford, D. C.; Romero-Romero, E.; White, B. R.; Wilkerson, J. F.; Majorana,

    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.

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

    SciTech Connect

    Aalseth, Craig E.; Barbeau, P. S.; Colaresi, J.; Collar, J. I.; Diaz Leon, J.; Fast, James E.; Fields, N.; Hossbach, Todd W.; Knecht, Andrea; Kos, Marek S.; Marino, Michael G.; Miley, Harry S.; Miller, M. L.; Orrell, John L.; Yocum, Michael

    2013-07-08

    CoGeNT employs p-type point-contact (PPC) germanium detectors to search for Weakly In- teracting 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 (m* * 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, instru- mental 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.

  7. Large Cryogenic Germanium Detector. Final Report

    SciTech Connect

    Mandic, Vuk

    2013-02-13

    The goal of this project was to investigate possible ways of increasing the size of cryogenic Ge detectors. This project identified two possible approaches to increasing the individual cryogenic Ge detector size. The first approach relies on using the existing technology for growing detector-grade (high-purity) germanium crystals of dislocation density 100-7000 cm{sup -2}. The second approach is to consider dislocation-free Ge crystals.

  8. Germanium detector vacuum encapsulation

    NASA Technical Reports Server (NTRS)

    Madden, N. W.; Malone, D. F.; Pehl, R. H.; Cork, C. P.; Luke, P. N.; Landis, D. A.; Pollard, M. J.

    1991-01-01

    This paper describes an encapsulation technology that should significantly improve the viability of germanium gamma-ray detectors for a number of important applications. A specialized vacuum chamber has been constructed in which the detector and the encapsulating module are processed in high vacuum. Very high vacuum conductance is achieved within the valveless encapsulating module. The detector module is then sealed without breaking the chamber vacuum. The details of the vacuum chamber, valveless module, processing, and sealing method are presented.

  9. Germanium detector vacuum encapsulation

    NASA Technical Reports Server (NTRS)

    Madden, N. W.; Malone, D. F.; Pehl, R. H.; Cork, C. P.; Luke, P. N.; Landis, D. A.; Pollard, M. J.

    1991-01-01

    This paper describes an encapsulation technology that should significantly improve the viability of germanium gamma-ray detectors for a number of important applications. A specialized vacuum chamber has been constructed in which the detector and the encapsulating module are processed in high vacuum. Very high vacuum conductance is achieved within the valveless encapsulating module. The detector module is then sealed without breaking the chamber vacuum. The details of the vacuum chamber, valveless module, processing, and sealing method are presented.

  10. WIMP Searches at Canfranc with Germanium Detectors

    NASA Astrophysics Data System (ADS)

    Morales, Angel

    2001-04-01

    An overview of the searches for Weak Interacting Massive Particles (WIMPs) through their scattering off Germanium nuclei carried out in the Canfranc Tunnel Astroparticle Laboratory (at 2450 metres of water equivalent (m.w.e.)) in a collaboration between the Universities of South Carolina and Zaragoza is given. The main experimental results are sketched both for natural abundance (COSME) and 76Ge enriched (IGEX) Germanium detector experiments are summarized and a briefing on the GEDEON project is also presented.

  11. Extrinsic germanium Blocked Impurity Bank (BIB) detectors

    NASA Technical Reports Server (NTRS)

    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.

  12. Germanium detector passivated with hydrogenated amorphous germanium

    DOEpatents

    Hansen, William L.; Haller, Eugene E.

    1986-01-01

    Passivation of predominantly crystalline semiconductor devices (12) is provided for by a surface coating (21) of sputtered hydrogenated amorphous semiconductor material. Passivation of a radiation detector germanium diode, for example, is realized by sputtering a coating (21) of amorphous germanium onto the etched and quenched diode surface (11) in a low pressure atmosphere of hydrogen and argon. Unlike prior germanium diode semiconductor devices (12), which must be maintained in vacuum at cryogenic temperatures to avoid deterioration, a diode processed in the described manner may be stored in air at room temperature or otherwise exposed to a variety of environmental conditions. The coating (21) compensates for pre-existing undesirable surface states as well as protecting the semiconductor device (12) against future impregnation with impurities.

  13. Cryogenic readout techniques for germanium detectors

    SciTech Connect

    Benato, G.; Cattadori, C.; Di Vacri, A.; Ferri, E.

    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)

  14. The 100 micron detector development program. [gallium doped germanium photoconductors

    NASA Technical Reports Server (NTRS)

    Moore, W. J.

    1976-01-01

    An effort to optimize gallium-doped germanium photoconductors (Ge:Ga) for use in space for sensitive detection of far infrared radiation in the 100 micron region is described as well as the development of cryogenic apparatus capable of calibrating detectors under low background conditions.

  15. Electronic considerations for externally segmented germanium detectors

    NASA Technical Reports Server (NTRS)

    Madden, N. W.; Landis, D. A.; Goulding, F. S.; Pehl, R. H.; Cork, C. P.; Luke, P. N.; Malone, D. F.; Pollard, M. J.

    1991-01-01

    The dominant background source for germanium gamma ray detector spectrometers used for some astrophysics observations is internal beta decay. Externally segmented germanium gamma ray coaxial detectors can identify beta decay by localizing the event. Energetic gamma rays interact in the germanium detector by multiple Compton interactions while beta decay is a local process. In order to recognize the difference between gamma rays and beta decay events, the external electrode (outside of detector) is electrically partitioned. The instrumentation of these external segments and the consequence with respect to the spectrometer energy signal is examined.

  16. Electronic considerations for externally segmented germanium detectors

    NASA Technical Reports Server (NTRS)

    Madden, N. W.; Landis, D. A.; Goulding, F. S.; Pehl, R. H.; Cork, C. P.; Luke, P. N.; Malone, D. F.; Pollard, M. J.

    1991-01-01

    The dominant background source for germanium gamma ray detector spectrometers used for some astrophysics observations is internal beta decay. Externally segmented germanium gamma ray coaxial detectors can identify beta decay by localizing the event. Energetic gamma rays interact in the germanium detector by multiple Compton interactions while beta decay is a local process. In order to recognize the difference between gamma rays and beta decay events, the external electrode (outside of detector) is electrically partitioned. The instrumentation of these external segments and the consequence with respect to the spectrometer energy signal is examined.

  17. Front End Spectroscopy ASIC for Germanium Detectors

    NASA Astrophysics Data System (ADS)

    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

  18. Gamma-ray imaging with germanium detectors

    NASA Astrophysics Data System (ADS)

    Mahoney, W. A.; Callas, J. L.; Ling, J. C.; Radocinski, R. G.; Skelton, R. T.; Varnell, L. S.; Wheaton, W. A.

    1993-01-01

    Externally segmented germanium detectors promise a breakthrough in gamma-ray imaging capabilities while retaining the superb energy resolution of germanium spectrometers. By combining existing position-sensitive detectors with an appropriate code aperture, two-dimensional imaging with 0.2-deg angular resolution becomes practical for a typical balloon experiment. Much finer resolutions are possible with larger separations between detectors and the coded aperture as would be applicable for space-based or lunar-based observatories. Two coaxial germanium detectors divided into five external segments have been fabricated and have undergone extensive performance evaluation and imaging testing in our laboratory. These tests together with detailed Monte Carlo modeling calculations have demonstrated the great promise of this sensor technology for future gamma-ray missions.

  19. Gamma-ray imaging with germanium detectors

    NASA Technical Reports Server (NTRS)

    Mahoney, W. A.; Callas, J. L.; Ling, J. C.; Radocinski, R. G.; Skelton, R. T.; Varnell, L. S.; Wheaton, W. A.

    1993-01-01

    Externally segmented germanium detectors promise a breakthrough in gamma-ray imaging capabilities while retaining the superb energy resolution of germanium spectrometers. By combining existing position-sensitive detectors with an appropriate code aperture, two-dimensional imaging with 0.2-deg angular resolution becomes practical for a typical balloon experiment. Much finer resolutions are possible with larger separations between detectors and the coded aperture as would be applicable for space-based or lunar-based observatories. Two coaxial germanium detectors divided into five external segments have been fabricated and have undergone extensive performance evaluation and imaging testing in our laboratory. These tests together with detailed Monte Carlo modeling calculations have demonstrated the great promise of this sensor technology for future gamma-ray missions.

  20. Performance of a 60 gram cryogenic germanium detector

    SciTech Connect

    Cummings, A.; Wang, N.; Shutt, T.; Barnes, P.; Lange, A.; Sadoulet, B.; Stubbs, C. . Dept. of Physics); Emes, J.; Ross, R.; Smith, G. ); Giraud-Heraud ); Haller, E.E. . Dept. of Materials Science and Mineral Engineering); Rich, J. )

    1991-04-01

    The authors have developed a 60 g particle detector which utilizes both the ionization and the photons produced by a particle interaction. Six NTD Ge thermistors are attached to a pure germanium crystal which has implanted contacts for drifting charge. The authors have operated our detector at 30 mK, and the authors have studied its response to irradiation by 18 and 60 keV photons from an 241 Am source. This paper presents an analysis of the resolution of our detector, considering the noise of the front end electronics, and signals from extraneous sources such as microphonics.

  1. Germanium Blocked Impurity Band (BIB) detectors

    NASA Technical Reports Server (NTRS)

    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.

  2. Detector materials: germanium and silicon

    SciTech Connect

    Haller, E.E.

    1981-11-01

    This article is a summary of a short course lecture given in conjunction with the 1981 Nuclear Science Symposium. The basic physical properties of elemental semiconductors are reviewed. The interaction of energetic radiation with matter is discussed in order to develop a feeling for the appropriate semiconductor detector dimensions. The extremely low net dopant concentrations which are required are derived directly from the detector dimensions. A survey of the more recent techniques which have been developed for the analysis of detector grade semiconductor single crystals is presented.

  3. Isotopically enriched germanium detectors for astrophysical gamma-ray spectroscopy

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    1990-01-01

    A study is presented of the instrumental background in astrophysical gamma-ray spectrometers using isotopically enriched germanium detectors. Calculations show that the beta-decay background, which is the largest component between approximately 0.1 and 1.0 MeV in balloonborne and satellite spectrometers, is dominated by the activation of Ge-74. This component can be reduced by an order of magnitude using detectors enriched to more than 80 percent in (Ge-70). The predicted reduction in the total background for current balloonborne instruments is more than a factor of 1.7 between 0.2 and 1.0 MeV. For future satellite instruments, the reduction in this energy range is by more than a factor of 5.

  4. Germanium: From Its Discovery to SiGe Devices

    SciTech Connect

    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.

  5. Electromechanically cooled germanium radiation detector system

    NASA Astrophysics Data System (ADS)

    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.

  6. Electromechanically-cooled germanium radiation detector system

    SciTech Connect

    Lavietes, A. D., LLNL.

    1998-05-01

    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 organizations 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.

  7. Proton-induced radiation damage in germanium detectors

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  8. Proton-induced radiation damage in germanium detectors

    SciTech Connect

    Bruckner, J.; Korfer, M.; Wanke, H. , Mainz ); Schroeder, A.N.F. ); Figes, D.; Dragovitsch, P. ); Englert, P.A.J. ); Starr, R.; Trombka, J.I. . Goddard Space Flight Center); Taylor, I. ); Drake, D.M.; Shunk, E.R. )

    1991-04-01

    High-purity germanium (HPGe) detectors will be used in future space missions for gamma-ray measurements and will be subject to interactions with energetic particles. To simulate this process several large-volume n-type HPGe detectors were incrementally exposed to a particle fluence of up to 10{sub 8} protons cm{sup {minus}2} (proton energy: 1.5 GeV) at different operating temperatures (90 to 120 K) to induce radiation damage. Basic scientific as well as engineering data on detector performance were collected. During the incremental irradiation, the peak shape produced by the detectors showed a significant change from a Gaussian shape to a broad complex structure. After the irradiation all detectors were thoroughly characterized by measuring many parameters. To remove the accumulated radiation damage the detectors were stepwise annealed at temperatures T {le} 110{degrees}C while staying specially designed cryostats. This paper shows that n-type HPGe detectors can be used in charged particles environments as high-energy resolution devices until a certain level of radiation damage is accumulated and that the damage can be removed at moderate annealing temperatures and the detector returned to operating condition.

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

    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.

  11. Silicon-Germanium Alloys for Infrared Detectors.

    DTIC Science & Technology

    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

  12. Germanium Detectors in Homeland Security at PNNL

    SciTech Connect

    Stave, Sean C.

    2015-05-01

    Neutron and gamma-ray detection is used for non-proliferation and national security applications. While lower energy resolution detectors such as NaI(Tl) have their place, high purity germanium (HPGe) also has a role to play. A detection with HPGe is often a characterization due to the very high energy resolution. However, HPGe crystals remain small and expensive leaving arrays of smaller crystals as an excellent solution. PNNL has developed two similar HPGe arrays for two very different applications. One array, the Multisensor Aerial Radiation Survey (MARS) detector is a fieldable array that has been tested on trucks, boats, and helicopters. The CASCADES HPGe array is an array designed to assay samples in a low background environment. The history of HPGe arrays at PNNL and the development of MARS and CASCADES will be detailed in this paper along with some of the other applications of HPGe at PNNL.

  13. Germanium detectors in homeland security at PNNL

    DOE PAGES

    Stave, S.

    2015-05-01

    Neutron and gamma-ray detection is used for non-proliferation and national security applications. While lower energy resolution detectors such as NaI(Tl) have their place, high purity germanium (HPGe) also has a role to play. A detection with HPGe is often a characterization due to the very high energy resolution. However, HPGe crystals remain small and expensive leaving arrays of smaller crystals as an excellent solution. PNNL has developed two similar HPGe arrays for two very different applications. One array, the Multisensor Aerial Radiation Survey (MARS) detector is a fieldable array that has been tested on trucks, boats, and helicopters. The CASCADESmore » HPGe array is an array designed to assay samples in a low background environment. The history of HPGe arrays at PNNL and the development of MARS and CASCADES will be detailed in this paper along with some of the other applications of HPGe at PNNL.« less

  14. Germanium detectors in homeland security at PNNL

    SciTech Connect

    Stave, S.

    2015-05-01

    Neutron and gamma-ray detection is used for non-proliferation and national security applications. While lower energy resolution detectors such as NaI(Tl) have their place, high purity germanium (HPGe) also has a role to play. A detection with HPGe is often a characterization due to the very high energy resolution. However, HPGe crystals remain small and expensive leaving arrays of smaller crystals as an excellent solution. PNNL has developed two similar HPGe arrays for two very different applications. One array, the Multisensor Aerial Radiation Survey (MARS) detector is a fieldable array that has been tested on trucks, boats, and helicopters. The CASCADES HPGe array is an array designed to assay samples in a low background environment. The history of HPGe arrays at PNNL and the development of MARS and CASCADES will be detailed in this paper along with some of the other applications of HPGe at PNNL.

  15. Production and test of isotopically modified Ge detectors for GERDA

    SciTech Connect

    Budjas, D.

    2011-07-01

    The viability of producing BEGe-type detectors from isotopically modified germanium for the GERDA experiment is demonstrated by a complete test of the supply chain. GERDA is built to search for neutrinoless double beta (0v{beta}{beta}) decay of Ge using high-purity germanium detectors made of material enriched in {sup 76}Ge. To reach a sensitivity for 0v{beta}{beta} decay of <1.4 x 10{sup 26} years, new active background suppression techniques are necessary. BEGe detectors enable a capability to efficiently identify and reject background events, while keeping large acceptance of 0v{beta}{beta} decay signal, by using novel pulse shape discrimination (PSD) techniques. The PSD as well as spectroscopic performance of prototype BEGe detectors from isotopically modified Ge was verified by comprehensive testing. (authors)

  16. Background suppression techniques in germanium detectors

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil; Cheung, Cynthia

    1992-01-01

    A new generation of astrophysical gamma ray spectrometers employing germanium solid state detectors for precise energy measurement are currently being planned for spaceflight in the late 1990's and the early 21st century. Because the observations of weak celestial sources are carried out in an intense radiation environment, the key objective of instrument design is to find ways to reduce the background. The current state of the knowledge in this field is reviewed and the new hardware techniques under design and test are discussed. Many of these techniques have already been flight tested on balloon platforms. Recent results from some of these tests are presented. By carefully applying these techniques it should be possible to achieve sensitivities that are factors of 3 to 10 better than would be obtained for a conventional instrument of similar weight.

  17. Germanium Detector Crystal Axis Orientation for the MAJORANA Demonstrator

    NASA Astrophysics Data System (ADS)

    Letourneau, Hannah

    2013-10-01

    The MAJORANA Demonstrator, currently being constructed at Sanford Underground Research Facility in Lead, South Dakota, is an array of germanium detectors which will be used to search for neutrinoless double beta decay, which would demonstrate that neutrinos have a Majorana mass term and lepton number is not conserved. An important characteristic of semiconductor detectors is the crystal axis orientation, because the propagation of electromagnetic signals is attenuated by the location of the interaction relative to the axis of the crystal. Conventionally, a goniometer is used to position a collimated low energy gamma source in many small increments around the detector to measure the rise time at each position. However, due to physical constraints from the casing of the Demonstrator, a different method must be developed. At the University of Washington this summer, I worked with a 76 Ge point-contact detector. I found the crystal axis orientation first with Americium 241, a lower energy gamma source. Then, I used a higher energy source, Thorium 232, in conjunction with the only a few angular reference points to also calculate rise time. Also, I wrote code to process the data. The success of this method will be evaluated and discussed. NSF

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Germanium-tin interdiffusion in strained Ge/GeSn multiple-quantum-well structure

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Dong, Yuan; Zhou, Qian; Tok, Eng Soon; Yeo, Yee-Chia

    2016-06-01

    The thermal stability and germanium-tin (Ge-Sn) interdiffusion properties were studied in epitaxial Ge/GeSn multiple-quantum-well (MQW) structure. No obvious interdiffusion was observed for annealing temperatures of 300 °C or below, while observable interdiffusion occurred for annealing temperatures of 380 °C and above. High-resolution x-ray diffraction was used to obtain the interdiffusion coefficient by analyzing the decrease rate of Ge/GeSn periodic satellite peaks. The interdiffusion coefficient is much higher, and the activation enthalpy of 1.21 eV is substantially lower in Ge/GeSn MQW structure than that previously reported in silicon-germanium (Si-Ge) systems. When the annealing temperature is increased to above 500 °C, Ge-Sn interdiffusion becomes severe. Some small pits appear on the surface, which should be related to Sn out-diffusion to the Ge cap layer, followed by Sn desorption from the top surface. This work provides insights into the Ge-Sn interdiffusion and Sn segregation behaviors in Ge/GeSn MQW structure, and the thermal budget that may be used for fabrication of devices comprising Ge/GeSn heterostructures.

  20. Germanium orthogonal strip detector system for gamma-ray imaging

    NASA Astrophysics Data System (ADS)

    Hull, Ethan L.; Burks, Morgan; Cork, Chris P.; Craig, William W.; Eckels, Del; Fabris, Lorenzo; Lavietes, Anthony D.; Luke, Paul N.; Madden, Norman W.; Pehl, Richard H.; Ziock, Klaus

    2001-12-01

    A germanium-detector based, gamma-ray imaging system has been designed, fabricated, and tested. The detector, cryostat, electronics, readout, and imaging software are discussed. An 11 millimeter thick, 2 millimeter pitch 19x19 orthogonal strip planar germanium detector is used in front of a coaxial detector to provide broad energy coverage. The planar detector was fabricated using amorphous germanium contacts. Each channel is read out with a compact, low noise external FET preamplifier specially designed for this detector. A bank of shaping amplifiers, fast amplifiers, and fast leading edge discriminators were designed and fabricated to process the signals from preamplifiers. The readout system coordinates time coincident x-y strip addresses with an x-strip spectroscopy signal and a spectroscopy signal from the coaxial detector. This information is sent to a computer where an image is formed. Preliminary shadow and pinhole images demonstrate the viability of a germanium based imaging system. The excellent energy resolution of the germanium detector system provides isotopic imaging.

  1. MSM-Metal Semiconductor Metal Photo-detector Using Black Silicon Germanium (SiGe) for Extended Wavelength Near Infrared Detection

    DTIC Science & Technology

    2012-09-01

    for Si1–xGex/Si MSM photodiodes. (a) 15% Ge with and without 5 mW light(red) and (b) 30% Ge MSM device with 5 (green) and 10 mW lights ( Lavender ...device with 5 (green) and 10 mW lights ( Lavender ). The clear dependence of the response on the optical power of the illumination source is evident

  2. Ge:Ga and Ge:Be photoconductive detectors for far infrared astronomy from a space platform

    NASA Technical Reports Server (NTRS)

    Bratt, P. R.; Lewis, N. N.; Nielsen, R. L.

    1978-01-01

    The paper describes some of the development work on gallium-doped germanium (Ge:Ga) and beryllium-doped germanium (Ge:Be) photoconductive detectors for use in far-infrared astronomical observations from a space platform such as IRAS. The paper is concerned primarily with detector performance and is divided into two major parts. The first presents the operating principles of this type of detector, while the second presents measured performance data under low-background flux conditions. It is shown that high sensitivity can be obtained from Ge:Ga and Ge:Be detectors under low-background and low-temperature conditions of operation. These detectors are useful for astronomical observations in the far-infrared over the wavelength range 30-120 microns. Major conclusions of the research work done so far are mentioned, including that detectors cut from the same crystal show reasonably good reproducibility of operating characteristics.

  3. Measurement and simulation of the segmented Germanium-Detector's Efficiency

    NASA Astrophysics Data System (ADS)

    Salem, Shadi

    This paper presents the methods to determine the detection efficiency of the segmented germanium detector. Two methods are given for the investigating the detection efficiency of the semiconductor segmented-germanium detector. Experimental measurements using radioactive sources are reported. The radioactive sources, which were involved, can give us the opportunity to cover the photon energy ranging up to hundreds of keV. A useful compilation is included of the latest values of the emission rates per decay for the following radioactive sources: 241Am and 133Ba. The second method, the simulation of the efficiency is involved for comparison purposes. A good agreement between the measurements and the simulation is obtained.

  4. SiGe-on-insulator fabricated via germanium condensation following high-fluence Ge+ ion implantation

    NASA Astrophysics Data System (ADS)

    Anthony, R.; Haddara, Y. M.; Crowe, I. F.; Knights, A. P.

    2017-08-01

    Germanium condensation is demonstrated using a two-step wet oxidation of germanium implanted Silicon-On-Insulator (SOI). Samples of 220 nm thick SOI are implanted with a nominal fluence of 5 × 1016 cm-2 Ge+ at an energy of 33 keV. Primary post-implantation wet oxidation is performed initially at 870 °C for 70 min, with the aim of capping the sample without causing significant dose loss via Ge evaporation through the sample surface. This is followed by a secondary higher temperature wet oxidation at either 900 °C, 1000 °C, or 1080 °C. The germanium retained dose and concentration profile, and the oxide thickness is examined after primary oxidation, and various secondary oxidation times, using Rutherford backscattering analysis. A mixed SiGe oxide is observed to form during the primary oxidation followed by a pure silicon oxide after higher temperature secondary oxidation. The peak germanium concentration, which varies with secondary oxidation condition, is found to range from 43 at. % to 95 at. %, while the FWHM of the Ge profile varies from 13 to 5 nm, respectively. It is also observed that both the diffusion of germanium and the rate of oxidation are enhanced at 870 and 900 °C compared to equilibrium expectations. Transmission electron microscopy of a representative sample with secondary oxidation at 1080 °C for 20 min shows that the SiGe layer is crystalline in nature and seeded from the underlying silicon. Raman spectroscopy is used to determine residual strain in the SiGe region following secondary oxidation. The strain is compressive in nature and increases with Ge concentration to a maximum of approximately 1% in the samples probed. In order to elucidate the physical mechanisms, which govern the implantation-condensation process, we fit the experimental profiles of the samples with a model that uses a modified segregation boundary condition; a modified linear rate constant for the oxidation; and an enhanced diffusion coefficient of germanium where the

  5. Bulk and surface effects in segmented high purity germanium detectors

    NASA Astrophysics Data System (ADS)

    Abt, I.; Caldwell, A.; Dönmez, B.; Irlbeck, S.; Majorovits, B.; Volynets, O.

    2013-08-01

    Segmented high-purity germanium detectors have been developed for a variety of experiments. The segmentation is used to augment the excellent energy resolution of such a device with spatial information to disentangle event topologies. Several performance aspects of true-coaxial segmented detectors are presented, especially the effects due to the crystallographic axes and the problem of events close to the surfaces of the detector. A test stand and Monte Carlo tools developed to study such effects are introduced. The simulation tools can also be used to design novel detectors, such as segmented point-contact detectors. A particular design is presented and discussed.

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

    DOEpatents

    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.

  7. GeMini: The Next Generation Mechanically-Cooled Germanium Spectrometer

    SciTech Connect

    Burks, M

    2008-06-13

    The next-generation mechanically-cooled germanium spectrometer has been developed. GeMini (GErmanium MINIature spectrometer) has been designed to bring high-resolution gamma-ray spectroscopy to a range of demanding field environments. Intended applications include short-notice and surprise inspections where positive nuclide identification of radioactive materials is required. GeMini weighs 2.75 kg (6 lbs) total including the detector, cryostat, cryocooler, batteries, electronics and readout. It is very low power allowing it to operate for 10 hours on a single set of rechargeable batteries. This instrument employs technology adapted from the gamma-ray spectrometer currently flying on NASA's Mercury MESSENGER spacecraft. Specifically, infrared shielding techniques allow for a vast reduction of thermal load. This in turn allows for a smaller, lighter-weight design, well-suited for a hand-held instrument. Two working prototypes have been built and tested in the lab. The target energy resolution is 3 keV fwhm or better for 1332 keV gamma-rays. The detectors currently achieve around 4.5 keV resolution, which is slightly higher than our goal due to microphonic noise. Our present work focuses on improving the resolution through mechanical and electronic means of reducing the microphonic noise. This paper will focus on the performance of the instrument and its applicability for inspectors in the field.

  8. Improving Germanium Detector Resolution and Reliability

    DTIC Science & Technology

    2008-09-01

    layer and fast states in the oxide/germanium interfacial layer have been investigated by Bardeen et al. (1956). Because electrons are attracted to the...figure art work. REFERENCES Bardeen , J., R. E. Coovert, S. R. Morrison, J. R. Schrieffer, R. Sun (1956). Surface conductance and the field effect...Chapman, B. (1980). Glow Discharge Processes: Sputtering and Plasma Etching, John Wiley & Sons, Inc.. Dinger, R. J. (1975). Dead layers at the surface of

  9. Variable-Temperature Cryostat For Radiation-Damage Testing Of Germanium Detectors

    NASA Technical Reports Server (NTRS)

    Floyd, Samuel R.; Puc, Bernard P.

    1992-01-01

    Variable-temperature cryostats developed to study radiation damage to, and annealing of, germanium gamma-ray detectors. Two styles: one accommodates large single detector and one accommodates two medium-sized detectors. New cryostats allow complete testing of large-volume germanium gamma-ray detectors without breaking cryostat vacuum and removing detectors for annealing.

  10. Ultra-low noise mechanically cooled germanium detector

    NASA Astrophysics Data System (ADS)

    Barton, P.; Amman, M.; Martin, R.; Vetter, K.

    2016-03-01

    Low capacitance, large volume, high purity germanium (HPGe) radiation detectors have been successfully employed in low-background physics experiments. However, some physical processes may not be detectable with existing detectors whose energy thresholds are limited by electronic noise. In this paper, methods are presented which can lower the electronic noise of these detectors. Through ultra-low vibration mechanical cooling and wire bonding of a CMOS charge sensitive preamplifier to a sub-pF p-type point contact HPGe detector, we demonstrate electronic noise levels below 40 eV-FWHM.

  11. Recent Results from the Canfranc Dark Matter Search with Germanium Detectors

    NASA Astrophysics Data System (ADS)

    Irastorza, I. G.; Morales, A.; Aalseth, C. E.; Avignone, F. T., III; Brodzinski, R. L.; Cebrián, S.; Garciá, E.; González, D.; Hensley, W. K.; Miley, H. S.; Morales, J.; Ortiz de Solórzano, A.; Piumedón, J.; Reeves, J. H.; Sarsa, M. L.; Scopel, S.; Villar, J. A.

    Two germanium detectors are currently operating in the Canfranc Underground Laboratory at 2450 m.w.e looking for WIMP dark matter. One is a 2 kg 76Ge IGEX detectors (RG-2) which has an energy threshold of 4 keV and a low-energy background rate of about 0.3 c/keV/kg/day. The other is a small (234 g) natural abundance Ge detector (COSME), of low energy threshold (2.5 keV) and an energy resolution of 0.4 keV at 10 keV which is looking for WIMPs and for solar axions. The analysis of 73 kg-days of data taken by COSME in a search for solar axions via their photon Primakoff conversion and Bragg scattering in the Ge crystal yields a 95% C.L. limit for the axion-photon coupling gaγγ < 2.8 × 10-9 GeV-1. These data, analyzed for WIMP searches provide an exclusion plot for WIMP-nucleon spin-independent interaction which improves previous plots in the low mass region. On the other hand, the σ(m) exclusion plot derived from the 60 kg-days of data from the RG-2 IGEX detector improves the exclusion limits derived from other ionization (non thermal) germanium detector experiments in the region of WIMP masses from 30 to 100 GeV recently singled out by the reported DAMA annual modulation effect.

  12. Comparison of Germanium Telluride (GeTe) Crystals

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Comparison of Germanium Telluride (GeTe) Crystals grown on Earth (left) and in space (right) during the Skylab SL-3 mission. These crystals were grown using a vapor transport crystal growth method in the Multipurpose Electric Furnace System (MEFS). Crystals grown on earth are needles and platelettes with distorted surfaces and hollow growth habits. The length of the ground-based needle is approximately 2 mm and the average lenth of the platelets is 1 mm. The dull appearance of the Skylab crystals resulted from condensation of the transport agent during the long cooling period dictated by the Skylab furnace. In a dedicated process, this would be prevented by removing the ampoule from the furnace and quenching the vapor source.

  13. Comparison of Germanium Telluride (GeTe) Crystals

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Comparison of Germanium Telluride (GeTe) Crystals grown on Earth (left) and in space (right) during the Skylab SL-3 mission. These crystals were grown using a vapor transport crystal growth method in the Multipurpose Electric Furnace System (MEFS). Crystals grown on earth are needles and platelettes with distorted surfaces and hollow growth habits. The length of the ground-based needle is approximately 2 mm and the average lenth of the platelets is 1 mm. The dull appearance of the Skylab crystals resulted from condensation of the transport agent during the long cooling period dictated by the Skylab furnace. In a dedicated process, this would be prevented by removing the ampoule from the furnace and quenching the vapor source.

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

    SciTech Connect

    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.

  15. Characterisation of the SmartPET planar Germanium detectors

    NASA Astrophysics Data System (ADS)

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

    2007-08-01

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

  16. Germanium ``hexa'' detector: production and testing

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    Here we present new result on the testing of a Germanium sensor for X-ray radiation. The system is made of 3 × 2 Medipix3RX chips, bump-bonded to a monolithic sensor, and is called ``hexa''. Its dimensions are 45 × 30 mm2 and the sensor thickness was 1.5 mm. The total number of the pixels is 393216 in the matrix 768 × 512 with pixel pitch 55 μ m. Medipix3RX read-out chip provides photon counting read-out with single photon sensitivity. The sensor is cooled to ‑126°C and noise levels together with flat field response are measured. For ‑200 V polarization bias, leakage current was 4.4 mA (3.2 μ A/mm2). Due to higher leakage around 2.5% of all pixels stay non-responsive. More than 99% of all pixels are bump bonded correctly. In this paper we present the experimental set-up, threshold equalization procedure, image acquisition and the technique for bump bond quality estimate.

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

    SciTech Connect

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

    2012-06-04

    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.

  18. Evaluation of neutron background in cryogenic Germanium target for WIMP direct detection when using reactor neutrino detector as neutron veto

    NASA Astrophysics Data System (ADS)

    Xu, Ye; Lan, Jieqin; Bai, Ying; Gao, Weiwei

    2016-09-01

    A direct WIMP (Weakly Interacting Massive Particle) detector with a neutron veto system is designed to better reject neutrons. An experimental configuration is studied in the present paper: 984 Ge modules are placed inside a reactor neutrino detector. In order to discriminate between nuclear and electron recoil, both ionization and heat signatures are measured using cryogenic germanium detectors in this detection. The neutrino detector is used as a neutron veto device. The neutron background for the experimental design has been estimated using the Geant4 simulation. The results show that the neutron background can decrease to O(0.01) events per year per tonne of high purity Germanium. We calculate the sensitivity to spin-independent WIMP-nucleon elastic scattering. An exposure of one tonne × year could reach a cross-section of about 2×10-11 pb.

  19. Ge photocapacitive MIS infrared detectors

    NASA Technical Reports Server (NTRS)

    Binari, S. C.; Miller, W. E.; Tsuo, Y. H.; Miller, W. E.

    1979-01-01

    An undoped Ge photocapacitive detector is reported which has peak normalized detectivities at wavelengh 1.4 microns and chopping frequencies 13-1000 Hz of 9 x 10 to the 12th, 4 x 10 to the 9th cm Hz to the 1/2th/W operating respectively at temperatures 77, 195, and 295 K. The observed temperature, spectral, and frequency response of the signal and noise are explained in terms of the measured space charge and interface state properties of the device.

  20. Neutrino Physics and Dark Matter Physics with Ultra-Low-Energy Germanium Detector

    SciTech Connect

    Shin-Ted, Lin

    2008-10-10

    The status and plans of the TEXONO Collaboration 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, an energy threshold of 220{+-}10 eV at an efficiency of 50% were achieved with a four-channel prototype detectors each of an active mass of 5 g. New limits were set for WIMPs with mass between 3-6 GeV. The prospects of the realization of full-scale experiments are discussed. This detector technique makes the unexplored sub-keV energy window accessible for new neutrino and dark matter experiments.

  1. Assembly and design of the germanium detectors for the Majorana Demonstrator

    NASA Astrophysics Data System (ADS)

    Jasinski, Ben; Majorana Collaboration

    2014-09-01

    The Majorana Demonstrator is a neutrino-less double-beta decay experiment being carried out at the Sanford Underground Research Facility, in South Dakota. The Demonstrator will consist of 30 kg of germanium detectors enriched in 76 Ge. Each P-type Point Contact detector is arranged in a string configuration, utilizing novel front-end electronics, cables, connectors, and mounts, fabricated from radio-pure materials. The assembly of the strings is carried out 4850 feet underground to reduce cosmologically induced backgrounds. To further reduce backgrounds, strings are assembled in a nitrogen-filled glovebox. This talk will give an overview of the design and the assembly of the detector strings for the Majorana Demonstrator.

  2. Portable electro-mechanically cooled high-resolution germanium detector

    SciTech Connect

    Neufeld, K.W.; Ruhter, W.D.

    1995-05-01

    We have integrated a small, highly-reliable, electro-mechanical cryo-cooler with a high-resolution germanium detector for portable/field applications. The system weighs 6.8 kg and requires 40 watts of power to operate once the detector is cooled to its operating temperature. the detector is a 500 mm{sup 2} by 20-mm thick low-energy configuration that gives a full-width at half maximum (FWHM) energy resolution of 523 eV at 122 keV, when cooled with liquid nitrogen. The energy resolution of the detector, when cooled with the electro-mechanical cooler, is 570 eV at 122 keV. We have field tested this system in measurements of plutonium and uranium for isotopic and enrichment information using the MGA and MGAU analysis programs without any noticeable effects on the results.

  3. Germanium blocked impurity band far infrared detectors

    SciTech Connect

    Rossington, C.S.

    1988-04-01

    The infrared portion of the electromagnetic spectrum has been of interest to scientist since the eighteenth century when Sir William Herschel discovered the infrared as he measured temperatures in the sun's spectrum and found that there was energy beyond the red. In the late nineteenth century, Thomas Edison established himself as the first infrared astronomer to look beyond the solar system when he observed the star Arcturus in the infrared. Significant advances in infrared technology and physics, long since Edison's time, have resulted in many scientific developments, such as the Infrared Astronomy Satellite (IRAS) which was launched in 1983, semiconductor infrared detectors for materials characterization, military equipment such as night-vision goggles and infrared surveillance equipment. It is now planned that cooled semiconductor infrared detectors will play a major role in the ''Star Wars'' nuclear defense scheme proposed by the Reagan administration.

  4. Germanium blocked impurity band far infrared detectors

    NASA Astrophysics Data System (ADS)

    Rossington, Carolyn Sally

    1988-04-01

    The infrared portion of the electromagnetic spectrum has been of interest to scientist since the eighteenth century when Sir William Herschel discovered the infrared as he measured temperatures in the sun's spectrum and found that there was energy beyond the red. In the late nineteenth century, Thomas Edison established himself as the first infrared astronomer to look beyond the solar system when he observed the star Arcturus in the infrared. Significant advances in infrared technology and physics, long since Edison's time, have resulted in many scientific developments, such as the Infrared Astronomy Satellite (IRAS) which was launched in 1983, semiconductor infrared detectors for materials characterization, military equipment such as night-vision goggles and infrared surveillance equipment. It is now planned that cooled semiconductor infrared detectors will play a major role in the Star Wars nuclear defense scheme proposed by the Reagan administration.

  5. The Role of the Silicon Germanium (SiGe) Heterojunction Bipolar Transistor (HBT) in Mobile Technology Platforms

    DTIC Science & Technology

    2011-09-01

    The Role of the Silicon Germanium (SiGe) Heterojunction Bipolar Transistor (HBT) in Mobile Technology Platforms by Gregory A. Mitchell...Germanium (SiGe) Heterojunction Bipolar Transistor (HBT) in Mobile Technology Platforms 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...MD 20783-1197 ARL-TN-0459 September 2011 The Role of the Silicon Germanium (SiGe) Heterojunction Bipolar Transistor (HBT) in Mobile

  6. An aeronomical application of a germanium near infrared (NIR) detector

    SciTech Connect

    Noto, J.; Kerr, R.B.; Rudy, R.J.; Williams, R.; Hecht, J.H.

    1994-12-31

    A collaboration between Boston University and the Aerospace corporation has resulted in a germanium based detector used in conjunction with an infrared optimized Fabry-Perot spectrometer. Gold plated mirrors were installed and the appropriate transmissive optics are used in the Fabry-Perot to optimize the NIR transmission. The detector is a germanium PIN diode coated with a layer of silicon-nitride. Current produced by the detector is measured by using a Capacitive Trans-Impedance Amplifier (CITA). An A/D converter samples the amplified capacitor voltage and outputs a 12 bit word that is then passed on to the controlling computer system. The detector, amplifier, and associated electronics are mounted inside a standard IR dewar and operated at 77 K. The authors have operated this detector and spectrometer system at Millstone Hill for about 6 months. Acceptable noise characteristics, a NEP of 10{sup {minus}17} watts, and a QE of 90% at 1.2 {micro}m, have been achieved with an amplifier gain of 200. The system is currently configured for observations of thermospheric helium, and has made the first measurement of the He 10,830 {angstrom} nightglow emission isolated from OH contamination. In an effort to both increase the sensitivity of the Fabry-Perot in the visible and to adapt it for planetary astronomy the authors have entered into a collaboration with CIDTEC. A Charge Injection Detector or CID has some unique capabilities that distinguish it from a CCD and the authors are evaluating it as a detector for the Hadinger fringe pattern produced by a Fabry-Perot. The CID allows non-destructive readout and random access of individual pixels with in the entire frame, this allows for both ``electronic masking`` of bright objects and allows each fringe to be observed without having to readout a large number of dark pixels.

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

    NASA Astrophysics Data System (ADS)

    Looker, Quinn

    minimizing charge injection leakage current, increasing the long-term stability of the contacts, and achieving good charge collection properties in segmented detectors. A systematic study of contact characteristics is presented where amorphous germanium (a-Ge) and amorphous silicon (a-Si) contacts are sputtered with varying sputter gas hydrogen content, sputter gas pressure, and amorphous film thickness. A set of about 45 detectors fabricated from 11 different crystal samples were analyzed for electron barrier height and effective Richardson constant. Most of these detectors were subjected to as many as 10 temperature cycles over a period of up to several months in order to assess their long-term stability. Additionally, 6 double-sided strip detectors were fabricated with a-Ge and a-Si contacts in order to study their inter-electrode charge collection properties. An attempt is made to relate fabrication process parameters such as hydrogen content, sputter pressure, and film thickness to changes observed in detector performance and assess the level of reproducibility using the current methods. Several important results and conclusions were found that enable more reliable and highly performing detectors with amorphous semiconductor contacts. Utilizing the new information should enable consistent production of finely segmented detectors with excellent energy resolution that can be operated reliably for a long period of time. The passivation process could impact planar detectors as well as other designs, such as the p-type point contact detector. It is demonstrated that the long-term stability of amorphous semiconductor contacts is primarily dependent on the time the detector is at room temperature rather than the number of temperature cycles. For a-Ge contacts, higher sputter pressure yields a more stable process that changes little with time, giving a reliable hole-blocking contact. The a-Si contacts form a good electron-blocking contact with decreasing leakage current over

  8. Characteristics of GRIFFIN high-purity germanium clover detectors

    NASA Astrophysics Data System (ADS)

    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.

  9. Evaluating a new segmented germanium detector contact technology

    NASA Astrophysics Data System (ADS)

    Jackson, E. G.; Lister, C. J.; Chowdhury, P.; Hull, E.; Pehl, R.

    2012-10-01

    New technologies for making gamma ray detectors position sensitive have many applications in space science, medical imaging, homeland security, and in nuclear structure research. One promising approach uses high-purity germanium wafers with the planar surfaces segmented into orthogonal strip patterns forming a Double-Sided Strip Detector (DSSD). The combination of data from adjoining strips, or pixels, is physics-rich for Compton image formation and polarization studies. However, sensitivity to charge loss and various kinds of cross-talk [1] have limited the usefulness of first generation devices. We are investigating new contact technologies, developed by PhDs Co [2], based on amorphous-germanium and yttrium contacts RF sputter deposited to a thickness of ˜ 1000 å. New techniques allow both physical and photolithographic segmentation of the contacts with inter-strip gap widths of 0.25 mm. These modifications should improve all aspects of charge collection. The new detector technology employs the same material and fabrication technique for both the n- and p- contacts, thus removing artificial asymmetry in the data. Results from tests of cross-talk, charge collection, and scattering asymmetry will be presented and compared with older technologies. This mechanically cooled counter, NP-7, seems to represent a breakthrough.[4pt] [1] S. Gros et al., Nucl. Inst. Meth. A 602, 467 (2009).[0pt] [2] E. Hull et al Nucl Inst Meth A 626, 39 (2011)

  10. Intrinsic germanium detector used in borehole sonde for uranium exploration

    USGS Publications Warehouse

    Senftle, F.E.; Moxham, R.M.; Tanner, A.B.; Boynton, G.R.; Philbin, P.W.; Baicker, J.A.

    1976-01-01

    A borehole sonde (~1.7 m long; 7.3 cm diameter) using a 200 mm2 planar intrinsic germanium detector, mounted in a cryostat cooled by removable canisters of frozen propane, has been constructed and tested. The sonde is especially useful in measuring X- and low-energy gamma-ray spectra (40–400 keV). Laboratory tests in an artificial borehole facility indicate its potential for in-situ uranium analyses in boreholes irrespective of the state of equilibrium in the uranium series. Both natural gamma-ray and neutron-activation gamma-ray spectra have been measured with the sonde. Although the neutron-activation technique yields greater sensitivity, improvements being made in the resolution and efficiency of intrinsic germanium detectors suggest that it will soon be possible to use a similar sonde in the passive mode for measurement of uranium in a borehole down to about 0.1% with acceptable accuracy. Using a similar detector and neutron activation, the sonde can be used to measure uranium down to 0.01%.

  11. Germanium

    SciTech Connect

    Major-Sosias, M.A.

    1996-01-01

    Germanium is an important semiconductor material, or metalloid which, by definition, is a material whose electrical properties are halfway between those of metallic conductors and electrical insulators. This paper describes the properties, sources, and market for germanium.

  12. SU-C-201-02: Quantitative Small-Animal SPECT Without Scatter Correction Using High-Purity Germanium Detectors

    SciTech Connect

    Gearhart, A; Peterson, T; Johnson, L

    2015-06-15

    Purpose: To evaluate the impact of the exceptional energy resolution of germanium detectors for preclinical SPECT in comparison to conventional detectors. Methods: A cylindrical water phantom was created in GATE with a spherical Tc-99m source in the center. Sixty-four projections over 360 degrees using a pinhole collimator were simulated. The same phantom was simulated using air instead of water to establish the true reconstructed voxel intensity without attenuation. Attenuation correction based on the Chang method was performed on MLEM reconstructed images from the water phantom to determine a quantitative measure of the effectiveness of the attenuation correction. Similarly, a NEMA phantom was simulated, and the effectiveness of the attenuation correction was evaluated. Both simulations were carried out using both NaI detectors with an energy resolution of 10% FWHM and Ge detectors with an energy resolution of 1%. Results: Analysis shows that attenuation correction without scatter correction using germanium detectors can reconstruct a small spherical source to within 3.5%. Scatter analysis showed that for standard sized objects in a preclinical scanner, a NaI detector has a scatter-to-primary ratio between 7% and 12.5% compared to between 0.8% and 1.5% for a Ge detector. Preliminary results from line profiles through the NEMA phantom suggest that applying attenuation correction without scatter correction provides acceptable results for the Ge detectors but overestimates the phantom activity using NaI detectors. Due to the decreased scatter, we believe that the spillover ratio for the air and water cylinders in the NEMA phantom will be lower using germanium detectors compared to NaI detectors. Conclusion: This work indicates that the superior energy resolution of germanium detectors allows for less scattered photons to be included within the energy window compared to traditional SPECT detectors. This may allow for quantitative SPECT without implementing scatter

  13. (Data acquisition for Ge detector arrays)

    SciTech Connect

    Hensley, D.C.

    1989-10-09

    The traveler presented three invited lectures entitled An Overview of Data Acquisition for Ge Detector Arrays,'' Specialized Data Acquisition for Ge Detector Arrays,'' and Gamma-Ray Angular Correlations from Heavy-Ion Inelastic Scattering Measured in the Spin Spectrometer'' and acted as a Study Group Coordinator at the Nuclear Structure in the Era of New Spectroscopy Workshop in Copenhagen, Denmark.

  14. Ge Detector Data Classification with Neural Networks

    NASA Astrophysics Data System (ADS)

    Wilson, Carly; Martin, Ryan; Majorana Collaboration

    2014-09-01

    The Majorana Demonstrator experiment is searching for neutrinoless double beta-decay using p-type point contact PPC germanium detectors at the Sanford Underground Research Facility, in South Dakota. Pulse shape discrimination can be used in PPC detectors to distinguish signal-like events from backgrounds. This research program explored the possibility of building a self-organizing map that takes data collected from germanium detectors and classifies the events as either signal or background. Self organizing maps are a type of neural network that are self-learning and less susceptible to being biased from imperfect training data. We acknowledge support from the Office of Nuclear Physics in the DOE Office of Science, the Particle and Nuclear Astrophysics Program of the National Science Foundation and the Russian Foundation for Basic Research.

  15. Automation of the Characterization of High Purity Germanium Detectors

    NASA Astrophysics Data System (ADS)

    Dugger, Charles ``Chip''

    2014-09-01

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

  16. Induced Radioactivity Measured in a Germanium Detector After a Long Duration Balloon Flight

    NASA Technical Reports Server (NTRS)

    Starr, R.; Evans, L. G.; Floyed, S. R.; Drake, D. M.; Feldman, W. C.; Squyres, S. W.; Rester, A. C.

    1997-01-01

    A 13-day long duration balloon flight carrying a germanium detector was flown from Williams Field, Antartica in December 1992. After recovery of the payload the activity induced in the detector was measured.

  17. Mitigation of Beta-Gamma Summing in a Planar Germanium Double-Sided Strip Detector

    NASA Astrophysics Data System (ADS)

    Larson, Nicole; Liddick, Sean; Prokop, Christopher; Suchyta, Scott; Tompkins, Jeromy

    2013-10-01

    Beta-decay spectroscopy experiments at fragmentation facilities are typically performed using a position-sensitive solid-state detector as a stopping medium for radioactive ion implantation. Subsequent beta decays are detected and correlated to the previously implanted ions based on position and time information. The results from these beta-decay spectroscopy experiments are pertinent to nuclear structure and astrophysics applications. To maximize the beta-decay detection efficiency a novel planar germanium double-sided strip detector (GeDSSD) has been implemented at the National Superconducting Cyclotron Laboratory. While the GeDSSD offers a beta-decay detection efficiency that will be close to 90%, the detector also has a very high efficiency for low-energy gamma rays (15.7% at 250 keV, for example). This leads to a large percentage of events in which the simultaneous energy deposition from the beta decay and gamma ray sum together in the GeDSSD. In order to mitigate the beta-gamma summing effects and recover the high gamma-ray detection efficiency, an algorithm has been developed in an attempt to separate the energy deposition of beta-decay electrons from gamma-rays. Results of the algorithm in both GEANT4 simulation and experimental data will be presented.

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

    SciTech Connect

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

    2006-09-21

    Compact maintenance free mechanical cooling systems are being developed to operate large volume (~570 cm3, ~3 kg, 140% or larger) germanium detectors for field applications. We are using a new generation of Stirling-cycle mechanical coolers for operating the very largest volume germanium detectors with absolutely no maintenance or liquid nitrogen requirements. The user will be able to leave these systems unplugged on the shelf until needed. The flip of a switch will bring a system to life in ~1 hour for measurements. The maintenance-free operating lifetime of these detector systems will exceed five years. These features are necessary for remote long-duration liquid-nitrogen free deployment of large-volume germanium gamma-ray detector systems for Nuclear Explosion Monitoring (NEM). The Radionuclide Aerosol Sampler/Analyzer (RASA) will greatly benefit from the availability of such detectors by eliminating the need for liquid nitrogen at RASA sites while still allowing the very largest available germanium detectors to be utilized. These mechanically cooled germanium detector systems being developed here will provide the largest, most sensitive detectors possible for use with the RASA. To provide such systems, the appropriate technical fundamentals are being researched. Mechanical cooling of germanium detectors has historically been a difficult endeavor. The success or failure of mechanically cooled germanium detectors stems from three main technical issues: temperature, vacuum, and vibration. These factors affect one another. There is a particularly crucial relationship between vacuum and temperature. These factors will be experimentally studied both separately and together to insure a solid understanding of the physical limitations each factor places on a practical mechanically cooled germanium detector system for field use. Using this knowledge, a series of mechanically cooled germanium detector prototype systems are being designed and fabricated. Our collaborators

  19. Pulse shape discrimination techniques for correcting the effects of radiation damage on germanium detectors

    SciTech Connect

    Ho, W.; Boggs, S.E.; Lin, R.P.

    1996-12-31

    For germanium detectors (GeDs), which provide the highest energy resolution for studying gamma ray line features from astrophysical sources, exposure to energetic particles in space leads to radiation damage. Trapping centers created in the GeDs, preferentially hole traps, reduce the efficiency of the transport of charge carriers and thereby degrade the energy resolution and line efficiency. In addition, the trapping may affect the performance of Pulse Shape Discrimination (PSD) techniques used in background reduction. We present here computer simulations of photon interactions and charge transport in a reverse-electrode, closed-end coaxial GeD. These simulations show that radiation damage does not significantly alter the shape of the current pulses, rendering the effect on PSD performance negligible. Furthermore, the simulations show that with PSD, significant improvements in the energy resolution of radiation damaged detectors can be obtained by applying a hole trapping correction to the energy measured by the detector. PSD provides the sizes and locations of the two largest energy depositions for photons that stop within the GeDs. For moderately damaged detectors (mean hole trapping length {lambda}{sub h} = 200 cm, which is equivalent to cosmic ray irradiation of {approximately}2 years), correcting for the trapping suffered by these two depositions provides almost complete recovery of the line shape and sensitivity: undamaged resolution and relative sensitivity (1.58 keV FWEM, 1.0), damaged (2.10 keV, 0.69), corrected (1.75 keV, 0.93). Even for severely damaged detectors ({lambda}{sub h} = 50 cm), a marked improvement is obtained. These improvements translate directly into an increase in sensitivity for the detection of weak fines.

  20. Aeronomical application of a germanium near infrared (NIR) detector

    NASA Astrophysics Data System (ADS)

    Noto, John; Kerr, Robert B.; Rudy, R. J.; Williams, R.; Hecht, James H.

    1994-09-01

    The wavelength region surrounding 1.0 micrometers has traditionally been a difficult one to observe. GaAs and silicon both have very low quantum efficiency in the NIR, while some improvements can be made by pre-flashing and oxygen soaking a silicon CCD. Greater improvement can be realized by using a material other then silicon as a substrate. Recently, detector technology has improved to the point where NIR observations can be made almost routinely. Scientifically, the NIR region is ideal for the study of molecular line and band emission, as well as low energy atomic transitions. A collaboration between Boston University and the Aerospace Corporation has resulted in a germanium based detector used in conjunction with an infrared optimized Fabry-Perot spectrometer. Gold plated mirrors were installed and the appropriate transmissive optics are used in the Fabry-Perot to optimize the NIR transmission. The detector is a germanium PIN diode coated with a layer of silicon-nitride. Current produced by the detector is measured by using a capacitive trans-impedance amplifier (CITA). An A/D converter samples the amplified capacitor voltage and outputs a 12 bit word that is then passed on to the controlling computer system. The detector, amplifier, and associated electronics are mounted inside a standard IR dewar and operated at 77 degree(s)K. We have operated this detector and spectrometer system at Millstone Hill for about 6 months. Acceptable noise characteristics, a NEP of 10(superscript -17) watts, and a QE of 90% at 1.2 micrometers , have been achieved with an amplifier gain of 200. The system is currently configured for observations of thermospheric helium, and has made the first measurement of the He 10,830 angstrom nightglow emission isolated from OH contamination. In an effort to both increase the sensitivity of our Fabry-Perot in the visible and to adapt it for planetary astronomy we have entered into a collaboration with CIDTEC. A charge injection detector or CID

  1. A repair station for HpGe detectors

    NASA Astrophysics Data System (ADS)

    Shearman, Robert; Lister, Christopher; Mitchell, A. J.; Copp, Patrick; Jepeal, Steven; Chowdhury, Partha

    2013-10-01

    Hyper-pure Germanium detectors (HpGe) offer the highest energy resolution for gamma-ray nuclear spectroscopy (about 1.5 keV @ 1 MeV), and are used in all the world's leading detector arrays such as GammaSphere, AGATA and GRETINA. The detector crystals are operated in cryostats at 100 K to reduce thermal noise. To maintain low leakage current and low operating temperatures, cryostat hygiene is very important. Detectors must be regularly maintained by using a high-vacuum, oil-free annealing station. At elevated temperatures above 373 K the process of pumping and baking can also anneal away neutron damage to the detector crystals. This poster will show the design and building of a new HpGe repair station at U. Mass Lowell, and make comparisons of results obtained from this new station to the Gammasphere annealing factory at Argonne. This research is funded by the DOE National Nuclear Safety Administration and the Office of Science.

  2. Liquid phase epitaxial growth and characterization of germanium far infrared blocked impurity band detectors

    SciTech Connect

    Bandaru, Jordana

    2001-01-01

    Germanium Blocked Impurity Band (BIB) detectors require a high purity blocking layer (< 1013 cm-3) approximately 1 mm thick grown on a heavily doped active layer (~ 1016cm-3) approximately 20 mm thick. Epilayers were grown using liquid phase epitaxy (LPE) of germanium out of lead solution. The effects of the crystallographic orientation of the germanium substrate on LPE growth modes were explored. Growth was studied on substrates oriented by Laue x-ray diffraction between 0.02° and 10° from the {111} toward the {100}. Terrace growth was observed, with increasing terrace height for larger misorientation angles. It was found that the purity of the blocking layer was limited by the presence of phosphorus in the lead solvent. Unintentionally doped Ge layers contained ~1015 cm-3 phosphorus as determined by Hall effect measurements and Photothermal Ionization Spectroscopy (PTIS). Lead purification by vacuum distillation and dilution reduced the phosphorus concentration in the layers to ~ 1014 cm-3 but further reduction was not observed with successive distillation runs. The graphite distillation and growth components as an additional phosphorus source cannot be ruled out. Antimony (~1016 cm-3) was used as a dopant for the active BIB layer. A reduction in the donor binding energy due to impurity banding was observed by variable temperature Hall effect measurements. A BIB detector fabricated from an Sb-doped Ge layer grown on a pure substrate showed a low energy photoconductive onset (~6 meV). Spreading resistance measurements on doped layers revealed a nonuniform dopant distribution with Sb pile-up at the layer surface, which must be removed by chemomechanical polishing. Sb diffusion into the pure substrate was observed by Secondary Ion Mass Spectroscopy (SIMS) for epilayers grown at 650 C. The Sb concentration at the interface dropped by an order of magnitude

  3. Mechanically Cooled Large-Volume Germanium Detector Systems for Nuclear Explosion Monitoring DOENA27323-1

    SciTech Connect

    Hull, E.L.

    2006-07-28

    Compact maintenance free mechanical cooling systems are being developed to operate large volume germanium detectors for field applications. To accomplish this we are utilizing a newly available generation of Stirling-cycle mechanical coolers to operate the very largest volume germanium detectors with no maintenance. The user will be able to leave these systems unplugged on the shelf until needed. The flip of a switch will bring a system to life in ~ 1 hour for measurements. The maintenance-free operating lifetime of these detector systems will exceed 5 years. These features are necessary for remote long-duration liquid-nitrogen free deployment of large-volume germanium gamma-ray detector systems for Nuclear Explosion Monitoring. The Radionuclide Aerosol Sampler/Analyzer (RASA) will greatly benefit from the availability of such detectors by eliminating the need for liquid nitrogen at RASA sites while still allowing the very largest available germanium detectors to be reliably utilized.

  4. Mechanically Cooled Large-Volume Germanium Detector Systems for Neclear Explosion Monitoring DOENA27323-2

    SciTech Connect

    Hull, E.L.

    2006-10-30

    Compact maintenance free mechanical cooling systems are being developed to operate large volume high-resolution gamma-ray detectors for field applications. To accomplish this we are utilizing a newly available generation of Stirling-cycle mechanical coolers to operate the very largest volume germanium detectors with no maintenance. The user will be able to leave these systems unplugged on the shelf until needed. The maintenance-free operating lifetime of these detector systems will exceed 5 years. Three important factors affect the operation of mechanically cooled germanium detectors: temperature, vacuum, and vibration. These factors will be studied in the laboratory at the most fundamental levels to insure a solid understanding of the physical limitations each factor places on a practical mechanically cooled germanium detector system. Using this knowledge, mechanically cooled germanium detector prototype systems will be designed and fabricated.

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

    NASA Astrophysics Data System (ADS)

    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. HEROICA: A fast screening facility for the characterization of germanium detectors

    SciTech Connect

    Andreotti, Erica; Collaboration: GERDA Collaboration

    2013-08-08

    In the course of 2012, a facility for the fast screening of germanium detectors called HEROICA (Hades Experimental Research Of Intrinsic Crystal Appliances) has been installed at the HADES underground laboratory in the premises of the Belgian Nuclear Research Centre SCK•CEN, in Mol (Belgium). The facility allows performing a complete characterization of the critical germanium detectors' operational parameters with a rate of about two detectors per week.

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

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  9. High-energy proton radiation damage of high-purity germanium detectors

    NASA Technical Reports Server (NTRS)

    Pehl, R. H.; Varnell, L. S.; Metzger, A. E.

    1978-01-01

    Quantitative studies of radiation damage in high-purity germanium gamma-ray detectors due to high-energy charged particles have been carried out; two 1.0 cm thick planar detectors were irradiated by 6 GeV/c protons. Under proton bombardment, degradation in the energy resolution was found to begin below 7 x 10 to the 7th protons/sq cm and increased proportionately in both detectors until the experiment was terminated at a total flux of 5.7 x 10 to the 8th protons/sq cm, equivalent to about a six year exposure to cosmic-ray protons in space. At the end of the irradiation, the FWHM resolution measured at 1332 keV stood at 8.5 and 13.6 keV, with both detectors of only marginal utility as a spectrometer due to the severe tailing caused by charge trapping. Annealing these detectors after proton damage was found to be much easier than after neutron damage.

  10. High-energy proton radiation damage of high-purity germanium detectors

    NASA Technical Reports Server (NTRS)

    Pehl, R. H.; Varnell, L. S.; Metzger, A. E.

    1978-01-01

    Quantitative studies of radiation damage in high-purity germanium gamma-ray detectors due to high-energy charged particles have been carried out; two 1.0 cm thick planar detectors were irradiated by 6 GeV/c protons. Under proton bombardment, degradation in the energy resolution was found to begin below 7 x 10 to the 7th protons/sq cm and increased proportionately in both detectors until the experiment was terminated at a total flux of 5.7 x 10 to the 8th protons/sq cm, equivalent to about a six year exposure to cosmic-ray protons in space. At the end of the irradiation, the FWHM resolution measured at 1332 keV stood at 8.5 and 13.6 keV, with both detectors of only marginal utility as a spectrometer due to the severe tailing caused by charge trapping. Annealing these detectors after proton damage was found to be much easier than after neutron damage.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. Chemical Bonding, Interfaces and Defects in Hafnium Oxide/Germanium Oxynitride Gate Stacks on Ge (100)

    SciTech Connect

    Oshima, Yasuhiro; Sun, Yun; Kuzum, Duygu; Sugawara, Takuya; Saraswat, Krishna C.; Pianetta, Piero; McIntyre, Paul C.; /Stanford U., Materials Sci. Dept.

    2008-10-31

    Correlations among interface properties and chemical bonding characteristics in HfO{sub 2}/GeO{sub x}N{sub y}/Ge MIS stacks were investigated using in-situ remote nitridation of the Ge (100) surface prior to HfO{sub 2} atomic layer deposition (ALD). Ultra thin ({approx}1.1 nm), thermally stable and aqueous etch-resistant GeO{sub x}N{sub y} interfaces layers that exhibited Ge core level photoelectron spectra (PES) similar to stoichiometric Ge{sub 3}N{sub 4} were synthesized. To evaluate GeO{sub x}N{sub y}/Ge interface defects, the density of interface states (D{sub it}) was extracted by the conductance method across the band gap. Forming gas annealed (FGA) samples exhibited substantially lower D{sub it} ({approx} 1 x 10{sup 12} cm{sup -2} eV{sup -1}) than did high vacuum annealed (HVA) and inert gas anneal (IGA) samples ({approx} 1x 10{sup 13} cm{sup -2} eV{sup -1}). Germanium core level photoelectron spectra from similar FGA-treated samples detected out-diffusion of germanium oxide to the HfO{sub 2} film surface and apparent modification of chemical bonding at the GeO{sub x}N{sub y}/Ge interface, which is related to the reduced D{sub it}.

  13. Germanium oxide removal by citric acid and thiol passivation from citric acid-terminated Ge(100).

    PubMed

    Collins, Gillian; Aureau, Damien; Holmes, Justin D; Etcheberry, Arnaud; O'Dwyer, Colm

    2014-12-02

    Many applications of germanium (Ge) are underpinned by effective oxide removal and surface passivation. This important surface treatment step often requires H-X (X = Cl, Br, I) or HF etchants. Here, we show that aqueous citric acid solutions are effective in the removal of GeOx. The stability of citric acid-treated Ge(100) is compared to HF and HCl treated surfaces and analyzed by X-ray photoelectron spectroscopy. Further Ge surface passivation was investigated by thiolation using alkane monothiols and dithiols. The organic passivation layers show good stability with no oxide regrowth observed after 3 days of ambient exposure.

  14. Comparison of CDMS [100] and [111] Oriented Germanium Detectors

    SciTech Connect

    Leman, S.W.; Hertel, S.A.; Kim, P.; Cabrera, B.; Do Couto E.Silva, E.; Figueroa-Feliciano, E.; McCarthy, K.A.; Resch, R.; Sadoulet, B.; Sundqvist, K.M.; /UC, Berkeley

    2012-09-14

    The Cryogenic Dark Matter Search (CDMS) utilizes large mass, 3-inch diameter x 1-inch thick target masses as particle detectors. The target is instrumented with both phonon and ionization sensors and comparison of energy in each channel provides event-by-event classification of electron and nuclear recoils. Fiducial volume is determined by the ability to obtain good phonon and ionization signal at a particular location. Due to electronic band structure in germanium, electron mass is described by an anisotropic tensor with heavy mass aligned along the symmetry axis defined by the [111] Miller index (L valley), resulting in large lateral component to the transport. The spatial distribution of electrons varies significantly for detectors which have their longitudinal axis orientations described by either the [100] or [111] Miller indices. Electric fields with large fringing component at high detector radius also affect the spatial distribution of electrons and holes. Both effects are studied in a 3 dimensional Monte Carlo and the impact on fiducial volume is discussed.

  15. Polarization insensitive Ge-rich silicon germanium waveguides for optical interconnects on silicon

    NASA Astrophysics Data System (ADS)

    Vakarin, V.; Chaisakul, Papichaya; Frigerio, Jacopo; Ballabio, Andrea; Ramírez, Joan Manel; Le Roux, Xavier; Coudevylle, Jean-René; Vivien, Laurent; Isella, Giovanni; Marris-Morini, Delphine

    2017-05-01

    We propose germanium-rich silicon germanium waveguides as a basic building block for polarization insensitive circuitry on silicon. In this work a detailed study of SiGe waveguides geometries is performed to find optimal parameters to simultaneously obtain low polarization sensitivity and single mode operation at λ=1.55μm. The polarization dependence of the effective index, group index and dispersion coefficient is investigated. Optimized geometries are tolerant to fabrication errors and can be realized with the current state of the art CMOS technology. As a next step polarization insensitive multimode interference structures have been designed.

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

    SciTech Connect

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

    2006-09-21

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

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

    SciTech Connect

    Napoli, D. R.; Maggioni, G. Carturan, S.; Gelain, M.; Eberth, J.; Grimaldi, M. G.; Tatí, S.; Riccetto, S.; Mea, G. Della

    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.

  18. Overview of multi-element monolithic germanium detectors for XAFS experiments at diamond light source

    SciTech Connect

    Chatterji, S.; Dennis, G. J.; Dent, A.; Diaz-Moreno, S.; Cibin, G.; Tartoni, N.; Helsby, W. I.

    2016-07-27

    An overview of multi-element monolithic germanium detectors being used at the X-ray absorption spectroscopy (XAS) beam lines at Diamond Light Source (DLS) is being reported. The hardware details and a summary of the performance of these detectors have also been provided. Recent updates about various ongoing projects being worked on to improve the performance of these detectors are summarized.

  19. Titanium germanium anti­monide, TiGeSb

    PubMed Central

    Lam, Robert; Mar, Arthur

    2009-01-01

    TiGeSb adopts the PbFCl- or ZrSiS-type structure, with Ti atoms (4mm symmetry) centred within monocapped square anti­prisms generated by the stacking of denser square nets of Ge atoms ( m2 symmetry) alternating with less dense square nets of Sb atoms (4mm symmetry). PMID:21577387

  20. GeGI (Germanium Gamma Imager) Performance: Maritime Interdiction Operation

    SciTech Connect

    Dreyer, Jonathan G.; Burks, Morgan T.; Trombino, Dave

    2014-09-23

    The Gamma Ray Imager (GeGI) was demonstrated during the Maritime Interdiction Operation at Point Alameda, the site of the former Naval Air Station, in Alameda, CA. During this exercise GeGI was used to localize sources within an abandoned building and a cargo ship, the Admiral Callaghan.

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

    NASA Astrophysics Data System (ADS)

    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.

  2. Conceptual design of a hybrid Ge:Ga detector array

    NASA Technical Reports Server (NTRS)

    Parry, C. M.

    1984-01-01

    For potential applications in space infrared astronomy missions such as the Space Infrared Telescope Facility and the Large Deployable Reflector, integrated arrays of long-wavelength detectors are desired. The results of a feasibility study which developed a design for applying integrated array techniques to a long-wavelength (gallium-doped germanium) material to achieve spectral coverage between 30 and 200 microns are presented. An approach which builds up a two-dimensional array by stacking linear detector modules is presented. The spectral response of the Ge:Ga detectors is extended to 200 microns by application of uniaxial stress to the stack of modules. The detectors are assembled with 1 mm spacing between the elements. Multiplexed readout of each module is accomplished with integration sampling of a metal-oxide-semiconductor (MOS) switch chip. Aspects of the overall design, including the anticipated level of particle effects on the array in the space environment, a transparent electrode design for 200 microns response, estimates of optical crosstalk, and mechanical stress design calculations are included.

  3. Design of monocrystalline Si/SiGe multi-quantum well microbolometer detector for infrared imaging systems

    NASA Astrophysics Data System (ADS)

    Shafique, Atia; Durmaz, Emre C.; Cetindogan, Barbaros; Yazici, Melik; Kaynak, Mehmet; Kaynak, Canan B.; Gurbuz, Yasar

    2016-05-01

    This paper presents the design, modelling and simulation results of silicon/silicon-germanium (Si/SiGe) multi-quantum well based bolometer detector for uncooled infrared imaging system. The microbolometer is designed to detect light in the long wave length infrared (LWIR) range from 8 to 14 μm with pixel size of 25 x 25 μm. The design optimization strategy leads to achieve the temperature coefficient of resistance (TCR) 4.5%/K with maximum germanium (Ge) concentration of 50%. The design of microbolometer entirely relies on standard CMOS and MEMS processes which makes it suitable candidate for commercial infrared imaging systems.

  4. Neutron energy determination with a high-purity germanium detector

    NASA Technical Reports Server (NTRS)

    Beck, Gene A.

    1992-01-01

    Two areas that are related to planetary gamma-ray spectrometry are investigated. The first task was the investigation of gamma rays produced by high-energy charged particles and their secondaries in planetary surfaces by means of thick target bombardments. The second task was the investigation of the effects of high-energy neutrons on gamma-ray spectral features obtained with high-purity Ge-detectors. For both tasks, as a function of the funding level, the experimental work was predominantly tied to that of other researchers, whenever there was an opportunity to participate in bombardment experiments at large or small accelerators for charged particles.

  5. Improvement in Ge Detector Cooling

    DTIC Science & Technology

    2008-09-01

    lifetime and integrity, improve performance, and resolve the need to procure and handle liquid nitrogen (LN2). Both cryocoolers offer advantages over...place, the 22-liter reservoir of LN2 provides up to 7 days of cooling to the detector with no risk of a partial thermal cycle or warm -up. The detector... warmed for repairs. Moreover, the interchangeability of dipsticks and Cryo-Cycle™ coolers allows independent replacement of either of the two most

  6. Germanium segregation in CVD grown SiGe layers

    NASA Astrophysics Data System (ADS)

    Novikau, Andrei; Gaiduk, Peter

    2010-02-01

    A 2D layer of spherical, crystalline Ge nanodots embedded in a SiO2 layer was formed by low pressure chemical vapour deposition combined with furnace oxidation and rapid thermal annealing. The samples were characterized structurally by using transmission electron microscopy and Rutherford back scattering spectrometry, as well as electrically by measuring C-V and I-V characteristics. It was found that formation of a high density Ge dots took place due to oxidation induced Ge segregation. The dots were situated in the SiO2 at the average distance 5-6 nm from the substrate. Strong evidence of charge storage effect in the crystalline Ge-nanodot layer was demonstrated by the hysteresis behavior of the high-frequency C-V curves.

  7. MaGe-a Geant4-Based Monte Carlo Application Framework for Low-Background Germanium Experiments

    SciTech Connect

    Boswell, Melissa; Chan, Yuen-Dat; Detwiler, Jason A.; Finnerty, Padraic; Henning, Reyco; Gehman, Victor M.; Johnson, Rob A.; Jordan, David V.; Kazkaz, Kareem; Knapp, Markus; Kroninger, 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

    2011-06-01

    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 MAJ ORANA and GE RDA neutrinoless double-beta decay experiments. MAJ ORANA and GERDA use high-purity germanium technology to search for the neutrinoless double-beta decay of the 76 Ge isotope, and MAGE is jointly developed between these two collaborations. The MAGE framework contains simulated geometries of common objects, prototypes, test stands, and the actual experiments. It also implements customized event generators, GE ANT 4 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 and experiment, and simplifies the addition of new detectors to be simulated. This paper focuses on the software framework, custom event generators, and physics list.

  8. Neutron damage tests of a highly segmented Germanium detector

    NASA Astrophysics Data System (ADS)

    Ross, T. J.; Beausang, C. W.; Lee, I. Y.; Macchiavelli, A. O.; Gros, S.; Cromaz, M.; Clark, R. M.; Fallon, P.; Jeppesen, Henrik; Allmond, J. M.

    2008-10-01

    Gamma ray energy tracking arrays such as GRETINA/GRETA and AGATA are the latest evolution in gamma ray detection. By locating the interaction points, in 3-dimensions, of individual gamma ray interactions such arrays allow the energies of gamma rays to be reconstructed. This leads to excellent energy resolution, superior peak-to-total ratio and photo peak efficiency and resolving powers up to a thousand times superior to the best current generation array. The position information is extracted from the detailed pulse shapes recorded in each segment. It is anticipated that these tracking-detectors will experience significant neutron fluxes during in beam experiments. Thus it is important to test the response of highly-segmented Ge detectors when subjected to high-energy neutrons. In a one week test carried out at the 88-Inch Cyclotron at LBNL the P3 prototype detector for the GRETINA array was exposed to a neutron flux equivalent to at least one and a half years normal use. The detector was then successfully annealed. Preliminary results for the energy and position resolution, prior to and after neutron damage, and after annealing will be presented.

  9. Black Silicon Germanium (SiGe) for Extended Wavelength Near Infrared Electro-optical Applications

    DTIC Science & Technology

    2010-05-01

    BLISS ATTN RDRL SE E T BOWER ATTN RDRL SED E M LITZ ATTN RDRL SED P A LELIS ATTN RDRL SED P B MORGAN ATTN RDRL SED P K JONES...Meissner, and Priyalal Wijewarnasuriya ARL -TR-5202 May 2010 Approved for public release...Research Laboratory Adelphi, MD 20783-1197 ARL -TR-5202 May 2010 Black Silicon Germanium (SiGe) for Extended Wavelength Near Infrared

  10. Ge(14)[Ge(SiMe(3))(3)](5)Li(3)(THF)(6): the largest metalloid cluster compound of germanium: on the way to fullerene-like compounds?

    PubMed

    Schenk, Christian; Schnepf, Andreas

    2008-10-14

    The reaction of GeBr with LiGe(SiMe(3))(3) yields the largest metalloid cluster compound of germanium Ge(14)[Ge(SiMe(3))(3)](5)Li(3)(THF)(6), in which 14 germanium atoms are arranged as a hollow sphere in the cluster core, showing that in the case of germanium also fullerene-like compounds might be present in the borderland between the molecular and solid states.

  11. Signal modeling of high-purity Ge detectors with a small read-out electrode and application to neutrinoless double beta decay search in Ge-76

    NASA Astrophysics Data System (ADS)

    Agostini, M.; Ur, C. A.; Budjáš, D.; Bellotti, E.; Brugnera, R.; Cattadori, C. M.; di Vacri, A.; Garfagnini, A.; Pandola, L.; Schönert, S.

    2011-03-01

    The GERDA experiment searches for the neutrinoless double beta decay of 76Ge using high-purity germanium detectors enriched in 76Ge. The analysis of the signal time structure provides a powerful tool to identify neutrinoless double beta decay events and to discriminate them from gamma-ray induced backgrounds. Enhanced pulse shape discrimination capabilities of Broad Energy Germanium detectors with a small read-out electrode have been recently reported. This paper describes the full simulation of the response of such a detector, including the Monte Carlo modeling of radiation interaction and subsequent signal shape calculation. A pulse shape discrimination method based on the ratio between the maximum current signal amplitude and the event energy applied to the simulated data shows quantitative agreement with the experimental data acquired with calibration sources. The simulation has been used to study the survival probabilities of the decays which occur inside the detector volume and are difficult to assess experimentally. Such internal decay events are produced by the cosmogenic radio-isotopes 68Ge and 60Co and the neutrinoless double beta decay of 76Ge. Fixing the experimental acceptance of the double escape peak of the 2.614 MeV photon to 90%, the estimated survival probabilities at Qββ = 2.039 MeV are (86+/-3)% for 76Ge neutrinoless double beta decays, (4.5+/-0.3)% for the 68Ge daughter 68Ga, and (0.9+0.4-0.2)% for 60Co decays.

  12. Monolayer germanium monochalcogenides (GeS/GeSe) as cathode catalysts in nonaqueous Li-O2 batteries.

    PubMed

    Ji, Yujin; Dong, Huilong; Yang, Mingye; Hou, Tingjun; Li, Youyong

    2017-08-09

    The development of novel cathode catalysts is of great importance to the practical applications of nonaqueous lithium oxygen (Li-O2) batteries. Here by using first-principles calculations, we revealed the catalytic mechanism and evaluated the catalytic activity of monolayer germanium monochalcogenides (2D-GeXs, X = S/Se) as cathode catalytic materials. For 2D-GeXs, Li4O4 with a ring-like structure is the final discharge product. The free energy diagram demonstrates that 2D-GeSe is more energetically favorable than 2D-GeS due to its considerably lower oxygen reduction reaction (ORR) overpotential (0.94 V) and oxygen evolution reaction (OER) overpotential (1.30 V), which originate from its weaker binding with LiO2 and stronger binding with the inserted Li atom. The analyses on electronic properties elucidate that the final product of Li4O4 on 2D-GeSe induces the semiconductor to semi-metal transition. Our results reflect that 2D-GeSe is an excellent candidate as a cathode material in nonaqueous Li-O2 batteries, while 2D-GeS is not appropriate.

  13. Recommendations for a Static Cosmic Ray Shield for Enriched Germanium Detectors

    SciTech Connect

    Aguayo Navarrete, Estanislao; Orrell, John L.; Ankney, Austin S.; Berguson, Timothy J.

    2011-09-21

    This document provides a detailed study of cost and materials that could be used to shield the detector material of the international Tonne-scale germanium neutrinoless double-beta decay experiment from hadronic particles from cosmic ray showers at the Earth's surface. This work was motivated by the need for a shield that minimizes activation of the enriched germanium during storage; in particular, when the detector material is being worked on at the detector manufacturer's facility. This work considers two options for shielding the detector material from cosmic ray particles. One option is to use a pre-existing structure already located near the detector manufacturer, such as Canberra Industries in Meriden, Connecticut. The other option is to build a shield onsite at a detector manufacturer's site. This paper presents a cost and efficiency analysis of such construction.

  14. Structural and optical properties of 200 mm germanium-on-insulator (GeOI) substrates for silicon photonics applications

    NASA Astrophysics Data System (ADS)

    Reboud, Vincent; Widiez, Julie; Hartmann, Jean Michel; Osvaldo Dias, Guilherme; Fowler, Daivid; Chelnokov, Alexei; Gassenq, Alban; Guilloy, Kevin; Pauc, Nicolas; Calvo, Vincent; Geiger, Richard; Zabel, T.; Faist, Jérôme; Sigg, Hans

    2015-02-01

    Integrated laser sources compatible with microelectronics represent currently one of the main challenges for silicon photonics. Using the Smart CutTM technology, we have fabricated for the first time 200 mm optical Germanium-On-Insulator (GeOI) substrates which consist of a thick layer of germanium (typically greater than 500 nm) on top of a thick buried oxide layer (around 1 µm). From this, we fabricated suspended microbridges with efficient Bragg mirror cavities. The high crystalline quality of the Ge layer should help to avoid mechanical failure when fabricating suspended membranes with amounts of tensile strain high enough to transform Ge into a direct bandgap material. Optical GeOI process feasibility has successfully been demonstrated, opening the way to waferscale fabrication of new light emitting devices based on highly-tensely strained (thanks to suspended membranes) and/or doped germanium.

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  16. Plasma Time in Discriminating Nuclear Recoils in Germanium Detector for Dark Matter Searches

    NASA Astrophysics Data System (ADS)

    Mei, Dongming; Barker, D'ann

    2012-10-01

    In the detection of WIMP-induced nuclear recoils with high-purity germanium detectors, CDMS-type bolometers are often used in measuring the ionization yield. For this technology, the detector is operated in the milli-Kelvin temperature range, which requires high priced detectors. Alternative electron/nuclear recoil discrimination using pulse shape has been widely utilized in the energy range of MeV in neutrinoless double-beta decay experiments with germanium detectors. However, the nuclear recoils induced by WIMPs are in the energy range of keV, and their pulse shape difference with electronic recoils in the same energy range has not proven to be visible in a commercially available germanium detector. This paper presents a new idea of using plasma time difference in pulse shape to discriminate nuclear recoils from electronic recoils. We show the plasma time difference as a function of nuclear recoil energy. The technique using plasma time will be discussed with a generic germanium detector.

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

    SciTech Connect

    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.

  18. Search of low-mass WIMPs with a p -type point contact germanium detector in the CDEX-1 experiment

    NASA Astrophysics Data System (ADS)

    Zhao, W.; Yue, Q.; 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.; 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.; 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.; CDEX Collaboration

    2016-05-01

    The CDEX-1 experiment conducted a search of low-mass (<10 GeV /c2 ) weakly interacting massive particles 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 setup, detector characterization, data acquisition, and analysis procedures of this experiment. No excess of unidentified events is observed after the subtraction of the known background. Using 335.6 kg-days of data, exclusion constraints on the weakly interacting massive particle-nucleon spin-independent and spin-dependent couplings are derived.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Point contact germanium detectors at 500 eVee threshold for light dark matter searches

    NASA Astrophysics Data System (ADS)

    Soma, Arun Kumar; Li, Hau-Bin; Lin, Shin-Ted; Wong, Henry Tsz-King; TEXONO Collaboration

    2016-04-01

    Germanium detectors with sub-keV sensitivities can probe low-mass WIMP Dark Matter. This experimental approach is pursued at Kuo-Sheng Neutrino Laboratory (KSNL) in Taiwan and at China Jinping Underground Laboratory (CJPL) in China via TEXONO and CDEX programs, respectively. The highlights of R&D efforts on point contact germanium detectors and in particular the differentiation of surface and bulk events by pulse shape analysis are described. The latest results on WIMP-nucleon scattering cross-sections are also presented. Some of the allowed parameter space implied by other experiments are probed and excluded.

  1. A variable temperature cryostat that produces in situ clean-up germanium detector surfaces

    SciTech Connect

    Pehl, R.H.; Madden, N.W.; Malone, D.F.; Cork, C.P.; Landis, D.A.; Xing, J.S.; Friesel, D.L.

    1988-11-01

    Variable temperature cryostats that can maintain germanium detectors at temperatures from 82 K to about 400 K while the thermal shield surrounding the detectors remains much colder when the detectors are warmed have been developed. Cryostats such as these offer the possibility of cryopumping material from the surface of detectors to the colder thermal shield. The diode characteristics of several detectors have shown very significant improvement following thermal cycles up to about 150 K in these cryostats. Important applications for cryostats having this attribute are many. 4 figs.

  2. Structural and thermodynamic consideration of metal oxide doped GeO{sub 2} for gate stack formation on germanium

    SciTech Connect

    Lu, Cimang Lee, Choong Hyun; Zhang, Wenfeng; Nishimura, Tomonori; Nagashio, Kosuke; Toriumi, Akira

    2014-11-07

    A systematic investigation was carried out on the material and electrical properties of metal oxide doped germanium dioxide (M-GeO{sub 2}) on Ge. We propose two criteria on the selection of desirable M-GeO{sub 2} for gate stack formation on Ge. First, metal oxides with larger cation radii show stronger ability in modifying GeO{sub 2} network, benefiting the thermal stability and water resistance in M-GeO{sub 2}/Ge stacks. Second, metal oxides with a positive Gibbs free energy for germanidation are required for good interface properties of M-GeO{sub 2}/Ge stacks in terms of preventing the Ge-M metallic bond formation. Aggressive equivalent oxide thickness scaling to 0.5 nm is also demonstrated based on these understandings.

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

    NASA Astrophysics Data System (ADS)

    Gehman, Victor

    2010-02-01

    The Majo-ra-na collaboration will search for neutrinoless double-beta decay (0νββ) by fielding an array of high-purity germanium (HPGe) detectors in ultra-clean electroformed-copper cryostats deep underground. Recent advances in HPGe detector technology, in particular P-type Point-Contact (PPC) detectors, present exciting new techniques for identifying and reducing backgrounds to the 0νββ signal. This should result in greatly improved sensitivity over previous generation experiments. The very low energy threshold attainable with PPC detectors also provides for a broader physics program including searches for dark matter and axions. The Majo-ra-na De-mon-strat-or is an R&D program that will field three ˜20 kg modules of PPC detectors at Sanford Underground Laboratory. Half of the detectors will be enriched to 86% in ^76Ge. Here, we will cover the motivation, design, recent progress and current status of this effort, with special attention to its physics reach. )

  4. Solution Synthesis of Germanium Nanowires Using a Ge+2 Alkoxide Precursor

    PubMed Central

    Gerung, Henry; Boyle, Timothy J.; Tribby, Louis J.; Bunge, Scott D.; Brinker, C. Jeffrey; Han, Sang M.

    2008-01-01

    A simple solution synthesis of germanium (Ge0) nanowires under mild conditions (<400 °C and 1 atm) was demonstrated using germanium 2,6 dibutylphenoxide Ge(DBP)2 (1) as the precursor where DBP = OC6H3(C(CH3)3)2–2,6. Compound 1, synthesized from Ge(NR2)2 where R = SiMe3 and two equivalents of DBP-H, was characterized as a mononuclear species by single crystal X-ray diffraction. Dissolution of 1 in oleylamine, followed by rapid injection into a 1-octadecene solution heated to 300 °C under an atmosphere of Ar, led to the formation of Ge0 nanowires. The Ge0 nanowires were characterized by transmission electron microscopy (TEM), X-ray diffraction analysis, and Fourier transform infrared spectroscopy. These characterizations revealed that the nanowires are single crystalline in the cubic phase and coated with oleylamine surfactant. We also observed that the nanowire length (0.1 to 10 µm) increases with increasing temperature (285 to 315 °C) and time (5 to 60 min). Two growth mechanisms are proposed based on the TEM images intermittently taken during the growth process as a function of time: (1) self-seeding mechanism where one of two overlapping nanowires serves as a seed, while the other continues to grow as a wire and (2) self-assembly mechanism where an aggregate of small rods (< 50 nm in diameter) recrystallize on the tip of a longer wire, extending its length. PMID:16608360

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

    DTIC Science & Technology

    2007-09-01

    needed for low -level counting facilities. The applications of such user facilities include characterization of low -level radioactive samples. In...decay. Germanium coaxial detectors having segmented outer contacts can provide sensitivity improvement in low - background measurements. The...needed for low -level counting facilities. The practical applications of such user facilities include characterization of low -level radioactive samples

  6. Dark Matter Search with SUB-keV Germanium Detectors at the China Jinping Underground Laboratory

    NASA Astrophysics Data System (ADS)

    Yue, Qian; Wong, Henry T.

    2013-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Yue, Qian; Wong, Henry T.; Cdex-Texono Collaboration

    2012-07-01

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  9. Study on the increase of inactive germanium layer in a high-purity germanium detector after a long time operation applying MCNP code

    NASA Astrophysics Data System (ADS)

    Huy, N. Q.; Binh, D. Q.; An, V. X.

    2007-04-01

    This study aims at finding an explanation for the decrease in the efficiency of an HPGe detector and evaluating a change in the detector inactive germanium layer during its operation. Monte Carlo calculations using the MCNP4C2 code were performed to evaluate the detector efficiency for different values of the inactive germanium layer. Comparison of the experimental and calculated data shows that the inactive germanium layer of the detector changed its thickness from 0.35 to 1.16 mm after an operating time of 9 years. Measurements for determining the reduction of the detector efficiency were carried out two times, one after 3 years and another after 9 years of operation. Experimental result shows that the detector efficiency was reduced about 8% in this period. The increase of inactive germanium layer can be considered as the main reason for explaining the reduction of detector efficiency of about 13% at the γ energies from 200 to 1800 keV during 9 years of detector operation, in which 5% for the 3 first years and 8% for the 6 last years.

  10. GeMini: The Next-Generation Mechanically-Cooled Germanium Spectrometer

    SciTech Connect

    Burks, M

    2008-11-12

    The next-generation mechanically-cooled germanium spectrometer has been developed. GeMini (MINIature GErmanium spectrometer) has been designed to bring high-resolution gamma-ray spectroscopy to a range of demanding field environments. Intended applications include short-notice inspections, border patrol, port monitoring and emergency response, where positive nuclide identification of radioactive materials is required but power and liquid cryogen are not easily available. GeMini weighs 2.75 kg for the basic instrument and 4.5 kg for the full instrument including user interface and ruggedized hermetic packaging. It is very low power allowing it to operate for 10 hours on a single set of rechargeable batteries. This instrument employs technology adapted from the gamma-ray spectrometer currently flying on NASA's Mercury MESSENGER spacecraft. Specifically, infrared shielding techniques allow for a vast reduction of thermal load. This in turn allows for a smaller, lighter-weight design, well-suited for a hand-held instrument. Three working prototypes have been built and tested in the lab. The measured energy resolution is 3 keV fwhm at 662 keV gamma-rays. This paper will focus on the design and performance of the instrument.

  11. 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

    NASA Astrophysics Data System (ADS)

    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.

  12. Extension of long wavelength response by modulation doping in extrinsic germanium infrared detectors

    NASA Technical Reports Server (NTRS)

    Hadek, V.; Farhoomand, J.; Beichman, C. A.; Watson, D. M.; Jack, M. D.

    1985-01-01

    A new concept for infrared detectors based on multilayer epitaxy and modulation doping has been investigated. This permits a high doping concentration and lower excitation energy in the photodetecting layer as is necessary for longer wavelength response, without incurring the detrimental effects of increased dark current and noise as would be the case with conventional detector designs. Germanium photodetectors using conventional materials and designs have a long wavelength cutoff in the infrared at 138 microns, which can only be extended through the inconvenient application of mechanical stress or magnetic fields. As a result of this approach which was arrived at from theoretical considerations and subsequently demonstrated experimentally, the long wavelength cutoff for germanium extrinsic detectors was extended beyond 200 microns, as determined by direct infrared optical measurements.

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

    NASA Astrophysics Data System (ADS)

    Alloatti, L.; Ram, R. J.

    2016-02-01

    A photodiode with 0.55 ± 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 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Measurement of the temperature dependence of pulse lengths in an n-type germanium detector

    NASA Astrophysics Data System (ADS)

    Abt, I.; Caldwell, A.; Liu, J.; Majorovits, B.; Volynets, O.

    2011-10-01

    The temperature dependence of the pulse length was measured for an 18-fold segmented n-type germanium detector in the temperature range of 77-120 K. The interactions of 122 keV photons originating from a 152Eu source were selected and pulses as observed on the core and segment electrodes were studied. In both cases, the temperature dependence can be well described by a Boltzmann-like ansatz.

  17. Search for global-minimum geometries of medium-sized germanium clusters. II. Motif-based low-lying clusters Ge21-Ge29

    NASA Astrophysics Data System (ADS)

    Yoo, S.; Zeng, X. C.

    2006-05-01

    We performed a constrained search for the geometries of low-lying neutral germanium clusters GeN in the size range of 21⩽N⩽29. The basin-hopping global optimization method is employed for the search. The potential-energy surface is computed based on the plane-wave pseudopotential density functional theory. A new series of low-lying clusters is found on the basis of several generic structural motifs identified previously for silicon clusters [S. Yoo and X. C. Zeng, J. Chem. Phys. 124, 054304 (2006)] as well as for smaller-sized germanium clusters [S. Bulusu et al., J. Chem. Phys. 122, 164305 (2005)]. Among the generic motifs examined, we found that two motifs stand out in producing most low-lying clusters, namely, the six/nine motif, a puckered-hexagonal-ring Ge6 unit attached to a tricapped trigonal prism Ge9, and the six/ten motif, a puckered-hexagonal-ring Ge6 unit attached to a bicapped antiprism Ge10. The low-lying clusters obtained are all prolate in shape and their energies are appreciably lower than the near-spherical low-energy clusters. This result is consistent with the ion-mobility measurement in that medium-sized germanium clusters detected are all prolate in shape until the size N ˜65.

  18. Neutrino and dark matter physics with sub-KeV Germanium detectors

    NASA Astrophysics Data System (ADS)

    Li, Hau Bin; (TEXONO Collaboration

    2016-05-01

    Germanium detectors with sub-keV sensitivities [1, 2, 3] offer a unique opportunity to study neutrino interactions and properties [4] as well as to search for light WIMP Dark Matter [5, 6]. The TEXONO and CDEX Collaborations have been pursuing this research program at the Kuo-Sheng Neutrino Laboratory in Taiwan and in the China Jinping Underground Laboratory in China. We will present highlights of the detector R&D program which allow us to experimental probe this new energy window. The results, status and plans of our neutrino physics program will be discussed, with focus on the quest on neutrino-nucleus coherent scattering.

  19. How Processing Atmosphere Influences the Evolution of GeO[subscript 2]-Embedded Germanium Nanocrystals Obtained from the Thermolysis of Phenyl Trichlorogermane-Derived Polymers

    SciTech Connect

    Henderson, Eric J.; Hessel, Colin M.; Cavell, Ronald G.; Veinot, Jonathan G.C.

    2010-06-22

    We report the influence of processing atmosphere on the evolution of oxide-embedded germanium nanocrystals (Ge-NCs) formed by the thermal processing of (C{sub 6}H{sub 5}GeO{sub 1.5}){sub n} sol-gel polymers. In an inert processing atmosphere (100% Ar), the generation of elemental Ge from thermally induced disproportionation of the germanium rich oxide (GRO) leads to GeO{sub 2}-embedded Ge-NCs whose size is independent of peak processing temperature and time. Processing in a slightly reducing atmosphere (5% H{sub 2}/95% Ar) activates a second Ge-NC formation and growth pathway, involving the reduction of Ge oxide species. Here, we report that the processing atmosphere governs the distribution of Ge species. By modifying the contributions from redistribution and reduction reactions within the GRO, diffusion of Ge atoms throughout the oxide matrix and formation and growth of Ge-NCs are impacted.

  20. Some gamma-ray shielding measurements made at altitudes greater than 115000 feet using large Ge(Li) detectors

    NASA Technical Reports Server (NTRS)

    Chapman, G. T.; Cumby, R. P.; Gibbons, J. H.; Macklin, R. L.; Parker, H. W.

    1972-01-01

    A series of balloon-flight experiments at altitudes greater than 115,000 feet were conducted to gain information relative to the use of composite shields (passive and/or active) for shielding large-volume, lithium-drifted, germanium (Ge(Li)) detectors used in gamma-ray spectrometers. Data showing the pulse-height spectra of the environmental gamma radiation as measured at 5.3 and 3.8 gms sq cm residual atmosphere with an unshielded diode detector are also presented.

  1. Chest wall thickness measurements of the LLNL and JAERI torso phantoms for germanium detector counting

    SciTech Connect

    Kramer, G.H.; Hauck, B.M.

    1997-11-01

    The Lawrence Livermore National Laboratory and Japanese Atomic Energy Research Institute torso phantoms were developed to calibrate lung counting systems that are used to estimate plutonium and other radionuclides deposited in the lung. Originally, low energy photon counting systems consisted of phoswich detectors. The average chest wall thicknesses and individual measurement points of the Lawrence Livermore National Laboratory phantom and its overlay plates in the regions covered by these detectors were provided by the manufacturer. Germanium detectors are of a different size and are placed in different locations on the phantom so that the manufacturer`s data are no longer applicable for the locations of the germanium detectors on the phantom. The Human Monitoring Laboratory has re-evaluated the chest wall thickness of both the Lawrence Livermore National Laboratory and Japanese Atomic Energy Research Institute phantoms and their overlay plates for its germanium lung counting system. The measurements were made in the upper right, lower right, upper left, and lower left positions on the phantom`s torso plate above the lungs. The effective chest wall thicknesses (17 keV) for the Lawrence Livermore National Laboratory torso plate are 1.46 cm, 1.43 cm, 1.66 cm, 1.48 cm, respectively. The manufacturer`s quoted average effective chest wall thickness for a pair of phoswich detectors is 1.63 cm. The measured effective chest wall thicknesses (17 keV) for the JAERI`s torso plate are 1.76 cm, 2.15 cm, 1.79 cm, 2.15 cm, respectively. The manufacturer`s quoted average chest wall thickness for an unspecified region of the chest is 1.50 cm. This paper presents effective chest wall thickness data for the phantoms with and without their overlay plates at 17 keV, 60 keV, 200 keV and 1,500 keV. 13 refs., 2 figs., 4 tabs.

  2. Characterizing germanium detectors fabricated from self-grown crystals at USD

    NASA Astrophysics Data System (ADS)

    Wagner, Mitchell; Liu, Jing; Mei, Dongming

    2017-01-01

    Several cryostats were established to characterize Ge detectors fabricated from self-grown crystals at the University of South Dakota (USD). The cryostats include: 1. an ultra-high vacuum (UHV) chamber that can be dipped into liquid nitrogen for quick cooling, 2. a portable liquid nitrogen cooled cryostat that can be operated in an arbitrary orientation, and 3. a surface scanning station that can be used to study detector surface properties in detail. We have successfully operated a planar Ge detector with amorphous semiconductor surfaces, made at LBNL from USD grown crystal, in the UHV chamber. Together with the existing crystal growth and detector fabrication facility, this marks the completion of the entire Ge detector development chain at USD.

  3. Influence of the deposition and annealing temperatures on the luminescence of germanium nanocrystals formed in GeO x films and multilayer Ge/SiO2 structures

    NASA Astrophysics Data System (ADS)

    Grachev, D. A.; Ershov, A. V.; Karabanova, I. A.; Pirogov, A. V.; Nezhdanov, A. V.; Mashin, A. I.; Pavlov, D. A.

    2017-05-01

    The GeO x films and multilayer nanoperiodic Ge/SiO2 structures containing germanium nanocrystals were prepared by physical vapor deposition in vacuum. The properties of the films and multilayer structures were controlled by varying the deposition temperature in the range of 35-590°C and the annealing temperature in the range of 400-1000°C. A comparative study of the optical and structural characteristics of the nanosystems was performed using the methods of Raman scattering spectroscopy, IR spectroscopy, photoluminescence, and electron microscopy, which demonstrated a qualitative similarity of the nanosystems. It was found that annealing at temperatures in the range of 600-800°C leads to the formation of germanium nanocrystals with a high density ( 1012 cm-2), whereas in the materials not subjected to annealing, their density did not exceed 1010 cm-2. The average size of the nanocrystals was found to be 5 ± 2 nm. For both nanosystems, three luminescence bands were observed at 1.2, 1.5-1.7, and 1.7-2.0 eV. It was assumed that the origin of these bands is associated with germanium nanocrystals, oxygen-deficient centers in GeOx, and defects at the Ge/dielectric interface, respectively.

  4. Characterization of a high-purity germanium detector for small-animal SPECT.

    PubMed

    Johnson, Lindsay C; Campbell, Desmond L; Hull, Ethan L; Peterson, Todd E

    2011-09-21

    We present an initial evaluation of a mechanically cooled, high-purity germanium double-sided strip detector as a potential gamma camera for small-animal SPECT. It is 90 mm in diameter and 10 mm thick with two sets of 16 orthogonal strips that have a 4.5 mm width with a 5 mm pitch. We found an energy resolution of 0.96% at 140 keV, an intrinsic efficiency of 43.3% at 122 keV and a FWHM spatial resolution of approximately 1.5 mm. We demonstrated depth-of-interaction estimation capability through comparison of pinhole acquisitions with a point source on and off axes. Finally, a flood-corrected flood image exhibited a strip-level uniformity of less than 1%. This high-purity germanium offers many desirable properties for small-animal SPECT.

  5. Characterization of a high-purity germanium detector for small-animal SPECT

    PubMed Central

    Johnson, Lindsay C; Campbell, Desmond L; Hull, Ethan L; Peterson, Todd E

    2011-01-01

    We present an initial evaluation of a mechanically-cooled, high-purity germanium double-sided strip detector as a potential gamma camera for small-animal SPECT. It is 90 mm in diameter and 10 mm thick with two sets of 16 orthogonal strips that have a 4.5 mm width with a 5 mm pitch. We found an energy resolution of 0.96% at 140 keV, an intrinsic efficiency of 43.3% at 122 keV and a FWHM spatial resolution of approximately 1.5 mm. We demonstrated depth-of-interaction estimation capability through comparison of pinhole acquisitions with a point source on and off axis. Finally, a flood-corrected-flood image exhibited a strip-level uniformity of less than 1%. This high-purity germanium offers many desirable properties for small-animal SPECT. PMID:21852723

  6. Synthesis and Structure of Two New Strontium Germanium Nitrides: Sr(3)Ge(2)N(2) and Sr(2)GeN(2).

    PubMed

    Clarke, S. J.; Kowach, G. R.; DiSalvo, F. J.

    1996-11-20

    We report the structures of two new strontium germanium nitrides synthesized as crystals from the elements in sealed Nb tubes at 750 degrees C using liquid Na as a growth medium. Sr(3)Ge(2)N(2) is isostructural with the previously reported Ba analogue. It crystallizes in P2(1)/m (No. 11), with a = 9.032(2) Å, b = 3.883(1) Å, c = 9.648(2) Å and beta = 112.42(3) degrees, and has two formula units per unit cell. It contains GeN(2)(4)(-) units and additionally |Ge(2)(-) zigzag chains. Sr(2)GeN(2) crystallizes in P4(2)/mbc (No. 135) with a= b = 11.773(2) Å and c= 5.409(1) Å and has Z = 8. It also contains GeN(2)(4)(-) units which have 18 valence electrons and, consequently are bent, like the isoelectronic molecule SO(2).

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

    NASA Astrophysics Data System (ADS)

    Jackson, Emily G.

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

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

    SciTech Connect

    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

    Here, a search for Pauli-exclusion-principle-violating Kα 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 × 1030 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 × 1030 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 76Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation.

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

    DOE PAGES

    Abgrall, N.; Arnquist, I. J.; Avignone, F. T.; ...

    2016-11-11

    Here, a search for Pauli-exclusion-principle-violating Kα 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 × 1030 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 × 1030 s at 90% C.L. It is estimated thatmore » the Majorana Demonstrator, a 44 kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of 76Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation.« less

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

    DOE PAGES

    Abgrall, N.; Arnquist, I. J.; Avignone, F. T.; ...

    2016-11-11

    Here, a search for Pauli-exclusion-principle-violating Kα 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 × 1030 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 × 1030 s at 90% C.L. It is estimated thatmore » the Majorana Demonstrator, a 44 kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of 76Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation.« less

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

    SciTech Connect

    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

    Here, a search for Pauli-exclusion-principle-violating Kα 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 × 1030 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 × 1030 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 76Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation.

  12. Germanium as a Critical Zone proxy: δ74Ge and Ge/Si in waters from the Peruvian Andes and Amazon

    NASA Astrophysics Data System (ADS)

    Baronas, J. J.; Hammond, D. E.; Torres, M. A.; West, A. J.; McManus, J.; Siebert, C.

    2014-12-01

    Germanium (Ge) is an element with a chemical behavior very similar to that of silicon (Si), albeit with some important differences. As a result, Ge/Si ratios in the environment can be used to investigate the Si cycle. For example, glacial-interglacial variations of the global marine Ge/Si ratio1 could be reflecting either changes in terrestrial weathering (river water Ge/Si has been proposed as a proxy for silicate weathering intensity1) or the degree of decoupling between Ge and Si during marine sediment diagenesis and burial2. The investigation of Ge stable isotopes (δ74Ge) may help to better constrain the dynamics of the Ge cycle and aid in the interpretation of Ge/Si paleorecords. It also has the potential to provide useful information on the weathering environment, complementing other isotopic critical zone proxies, such as δ7Li, δ30Si, 87Sr/86Sr, etc.. We present the first δ74Ge measurements of river waters. We analyzed δ74Ge as well as Ge/Si ratios and several other major and trace element concentrations across a mountain-to-floodplain gradient reaching from the Peruvian Andes to the Amazon. In contrast with other areas and the global trend1, there is no correlation between Ge/Si and Si concentration among different tributaries, indicating either the heterogeneity of Ge sources or the dominance of different secondary weathering reactions within different tributary catchments. We are currently investigating if Ge/Si varies with seasonal changes in runoff, which may help constrain the factors controlling Ge/Si. River water δ74Ge ranges from +3.4 to +6.5‰ among the different tributaries and is heavy relative to Bulk Silicate Earth (δ74Ge = +0.6‰3). Significant negative correlation of δ74Ge and Ge/Si suggests that both ratios may be fractionated during Ge uptake with secondary mineral precipitation. Similar (but weaker) correlation is observed for an extended dataset, including multiple U.S. rivers draining various lithologies. Overall, our data show

  13. Germanium-76 Sample Analysis

    SciTech Connect

    Kouzes, Richard T.; Engelhard, Mark H.; Zhu, Zihua

    2011-04-01

    The MAJORANA DEMONSTRATOR is a large array of ultra-low background high-purity germanium detectors, enriched in 76Ge, designed to search for zero-neutrino double-beta decay (0νββ). The DEMONSTRATOR will utilize 76Ge from Russia, and the first one gram sample was received from the supplier for analysis on April 24, 2011. The Environmental Molecular Sciences facility, a DOE user facility at PNNL, was used to make the required isotopic and chemical purity measurements that are essential to the quality assurance for the MAJORANA DEMONSTRATOR. The results of this first analysis are reported here.

  14. Towards a life-time-limited 8-octave-infrared photoconductive germanium detector

    NASA Astrophysics Data System (ADS)

    Pavlov, S. G.; Deßmann, N.; Pohl, A.; Abrosimov, N. V.; Mittendorff, M.; Winnerl, S.; Zhukavin, R. Kh; Tsyplenkov, V. V.; Shengurov, D. V.; Shastin, V. N.; Hübers, H.-W.

    2015-10-01

    Ultrafast, ultra-broad-band photoconductive detector based on heavily doped and highly compensated germanium has been demonstrated. Such a material demonstrates optical sensitivity in the more than 8 octaves, in the infrared, from about 2 mm to about 8 μm. The spectral sensitivity peaks up between 2 THz and 2.5 THz and is slowly reduced towards lower and higher frequencies. The life times of free electrons/holes measured by a pump-probe technique approach a few tenths of picoseconds and remain almost independent on the optical input intensity and on the temperature of a detector in the operation range. During operation, a detector is cooled down to liquid helium temperature but has been approved to detect, with a reduced sensitivity, up to liquid nitrogen temperature. The response time is shorter than 200 ps that is significantly faster than previously reported times.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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)

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

    SciTech Connect

    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.

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

    SciTech Connect

    Jastram, Andrew

    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.

  19. Selective Etching of Silicon in Preference to Germanium and Si0.5Ge0.5.

    PubMed

    Ahles, Christopher F; Choi, Jong Youn; Wolf, Steven; Kummel, Andrew C

    2017-06-21

    The selective etching characteristics of silicon, germanium, and Si0.5Ge0.5 subjected to a downstream H2/CF4/Ar plasma have been studied using a pair of in situ quartz crystal microbalances (QCMs) and X-ray photoelectron spectroscopy (XPS). At 50 °C and 760 mTorr, Si can be etched in preference to Ge and Si0.5Ge0.5, with an essentially infinite Si/Ge etch-rate ratio (ERR), whereas for Si/Si0.5Ge0.5, the ERR is infinite at 22 °C and 760 mTorr. XPS data showed that the selectivity is due to the differential suppression of etching by a ∼2 ML thick CxHyFz layer formed by the H2/CF4/Ar plasma on Si, Ge, and Si0.5Ge0.5. The data are consistent with the less exothermic reaction of fluorine radicals with Ge or Si0.5Ge0.5 being strongly suppressed by the CxHyFz layer, whereas, on Si, the CxHyFz layer is not sufficient to completely suppress etching. Replacing H2 with D2 in the feed gas resulted in an inverse kinetic isotope effect (IKIE) where the Si and Si0.5Ge0.5 etch rates were increased by ∼30 times with retention of significant etch selectivity. The use of D2/CF4/Ar instead of H2/CF4/Ar resulted in less total carbon deposition on Si and Si0.5Ge0.5 and gave less Ge enrichment of Si0.5Ge0.5. These results are consistent with the selectivity being due to the differential suppression of etching by an angstrom-scale carbon layer.

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

    NASA Technical Reports Server (NTRS)

    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.

  1. Gamma background studies for the XENON experiment using a High Purity Germanium Detector

    NASA Astrophysics Data System (ADS)

    Angle, Jesse Isaac

    The XENON Dark Matter Experiment, deployed at the Gran Sasso National Laboratory in Italy on March 2006, is a liquid noble gas detector designed to directly detect dark matter. The detector uses a dual-phase (gas/liquid) Xenon target to search for nuclear recoils associated with nucleus-WIMP interactions. Due to the high sensitivity needed in such an experiment, it is vital to not only reduce the background but to also understand the remaining background so as to aid in the understanding of the data as well as to facilitate upgrades beyond the early Research and Development phases. Many of the components of the XENON10 detector have been screened using a High Purity Germanium Detector known as the GATOR detector. Full analysis of the screening data requires Monte Carlo simulations of the GATOR detector and the sample. Results from this screening will be presented. Using the information obtained from the screening operation, Monte Carlo simulations of the XENON10 electron recoil background will be examined and compared to the actual detector data. The success of this simulation to data comparison indicates that we have a good understanding of the XENON10 gamma background and will be able to make more informed decisions regarding the next stage of detector development. This type of analysis has aided in the selection and design of many of the materials and components being incorporated into the new XENON100 detector, the next generation detector which will be capable of improving the limit set by XENON10 by at least an order of magnitude. (Full text of this dissertation may be available via the University of Florida Libraries web site. Please check http:/ /www.uflib.ufl.edu/etd.html)

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Development of a unit cell for a Ge:Ga detector array

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Two modules of gallium-doped germanium (Ge:Ga) infrared detectors with integrated multiplexing readouts and supporting drive electronics were designed and tested. This development investigated the feasibility of producing two-dimensional Ge:Ga arrays by stacking linear modules in a housing capable of providing uniaxial stress for enhanced long-wavelength response. Each module includes 8 detectors (1x1x2 mm) mounted to a sapphire board. The element spacing is 12 microns. The back faces of the detector elements are beveled with an 18 deg angle, which was proved to significantly enhance optical absorption. Each module includes a different silicon metal-oxide semiconductor field effect transistor (MOSFET) readout. The first circuit was built from discrete MOSFET components; the second incorporated devices taken from low-temperature integrated circuit multiplexers. The latter circuit exhibited much lower stray capacitance and improved stability. Using these switched-FET circuits, it was demonstrated that burst readout, with multiplexer active only during the readout period, could successfully be implemented at approximately 3.5 K.

  4. Validation of Pulse Shape Simulation for Ge detectors in the MAJORANA DEMONSTRATOR

    NASA Astrophysics Data System (ADS)

    Shanks, Benjamin; Majorana Collaboration

    2015-04-01

    The MAJORANA DEMONSTRATOR expects to begin searching for neutrinoless double beta decay using 76 Ge-enriched detectors in 2015. The DEMONSTRATOR high purity germanium (HPGe) detectors are built in the p-type point contact (PPC) geometry. The electrode of a PPC detector is small and shallow, resulting in low intrinsic capacitance and bulk field strengths compared to the traditional coaxial HPGe configuration. These characteristics allow for discrimination of signal event candidates from background using pulse shape analysis (PSA). In order to fully understand the systematics and efficiencies of PSA cuts, the MAJORANA collaboration has developed a software package to simulate signal generation in PPC detectors. This code has been validated by comparing simulated pulses to the pulse shapes generated for given detectors using an external source. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, the Particle Astrophysics Program of the National Science Foundation, and the Sanford Underground Research Facility.

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

    SciTech Connect

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

    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.

  6. Pulse shape discrimination for background rejection in germanium gamma-ray detectors

    NASA Technical Reports Server (NTRS)

    Feffer, P. T.; Smith, D. M.; Campbell, R. D.; Primbsch, J. H.; Lin, R. P.

    1989-01-01

    A pulse-shape discrimination (PSD) technique is developed to reject the beta-decay background resulting from activation of Ge gamma-ray detectors by cosmic-ray secondaries. These beta decays are a major source of background at 0.2-2 MeV energies in well shielded Ge detector systems. The technique exploits the difference between the detected current pulse shapes of single- and multiple-site energy depositions within the detector: beta decays are primarily single-site events, while photons at these energies typically Compton scatter before being photoelectrically absorbed to produce multiple-site events. Depending upon the amount of background due to sources other than beta decay, PSD can more than double the detector sensitivity.

  7. Pulse shape discrimination for background rejection in germanium gamma-ray detectors

    NASA Technical Reports Server (NTRS)

    Feffer, P. T.; Smith, D. M.; Campbell, R. D.; Primbsch, J. H.; Lin, R. P.

    1989-01-01

    A pulse-shape discrimination (PSD) technique is developed to reject the beta-decay background resulting from activation of Ge gamma-ray detectors by cosmic-ray secondaries. These beta decays are a major source of background at 0.2-2 MeV energies in well shielded Ge detector systems. The technique exploits the difference between the detected current pulse shapes of single- and multiple-site energy depositions within the detector: beta decays are primarily single-site events, while photons at these energies typically Compton scatter before being photoelectrically absorbed to produce multiple-site events. Depending upon the amount of background due to sources other than beta decay, PSD can more than double the detector sensitivity.

  8. Canister cryogenic system for cooling germanium semiconductor detectors in borehole and marine probes

    USGS Publications Warehouse

    Boynton, G.R.

    1975-01-01

    High resolution intrinsic and lithium-drifted germanium gamma-ray detectors operate at about 77-90 K. A cryostat for borehole and marine applications has been designed that makes use of prefrozen propane canisters. Uses of such canisters simplifies cryostat construction, and the rapid exchange of canisters greatly reduces the time required to restore the detector to full holding-time capability and enhances the safety of a field operation where high-intensity 252Cf or other isotopic sources are used. A holding time of 6 h at 86 K was achieved in the laboratory in a simulated borehole probe in which a canister 3.7 cm diameter by 57 cm long was used. Longer holding times can be achieved by larger volume canisters in marine probes. ?? 1975.

  9. Germanium blocked-impurity-band detector arrays - Unpassivated devices with bulk substrates

    NASA Technical Reports Server (NTRS)

    Watson, Dan M.; Guptill, Matthew T.; Huffman, James E.; Krabach, Timothy N.; Raines, S. N.; Satyapal, Shobita

    1993-01-01

    We have fabricated and characterized six-element monolithic arrays of Ge:Ga blocked-impurity-band detectors, with threshold wavelength 220 microns, peak quantum efficiency 14 percent, detective quantum efficiency 9 percent, dark current 300 e(-)/s, and response uniformity better than 4 percent. The devices are described very well by the standard model of blocked-impurity-band detectors and appear to satisfy many of the requirements of low-background astronomical instruments.

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

    NASA Astrophysics Data System (ADS)

    Detwiler, Jason

    2009-10-01

    The Majorana collaboration aims to perform a search for neutrinoless double-beta decay (0νββ) by fielding arrays of HPGe detectors mounted in ultra-clean electroformed-copper cryostats located deep underground. Recent advances in HPGe detector technology, in particular P-type Point-Contact (PPC) detectors, show great promise for identifying and reducing backgrounds to the 0νββ signal, which should result in improved sensitivity over previous generation experiments. The ultra-low energy threshold possible in PPC detectors also enables a broader physics program including sensitive searches for dark matter and axions. The Majorana Demonstrator R&D program will field three ˜20 kg modules of PPC detectors at Sanford Underground Laboratory. Half of the detector mass will be enriched to 86% in ^76Ge. I will present the motivation, design, recent progress and current status of this R&D effort, and discuss its physics reach.

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

    NASA Technical Reports Server (NTRS)

    Olsen, C. S.

    1998-01-01

    This research has shown that epilayers with residual impurity concentrations of 5 x 10(sup 13) cm(exp -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 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(exp -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.

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

    SciTech Connect

    Olsen, Christopher Sean

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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 efficiencies for a high purity germanium detector. The optimization procedure indicated that the increase in dead layer thickness is largely responsible for a detector efficiency decrease in time. The optimized detector model allows Monte Carlo efficiency calibration for all other samples of which the geometry and bulk composition is known. The presented method is a competitive and economic alternative to more elaborate detector scanning methods and results in a comparable accuracy.

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

    PubMed

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

    2014-06-01

    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 efficiencies for a high purity germanium detector. The optimization procedure indicated that the increase in dead layer thickness is largely responsible for a detector efficiency decrease in time. The optimized detector model allows Monte Carlo efficiency calibration for all other samples of which the geometry and bulk composition is known. The presented method is a competitive and economic alternative to more elaborate detector scanning methods and results in a comparable accuracy.

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

    SciTech Connect

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

    2014-06-15

    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 efficiencies for a high purity germanium detector. The optimization procedure indicated that the increase in dead layer thickness is largely responsible for a detector efficiency decrease in time. The optimized detector model allows Monte Carlo efficiency calibration for all other samples of which the geometry and bulk composition is known. The presented method is a competitive and economic alternative to more elaborate detector scanning methods and results in a comparable accuracy.

  16. Inelasticity and precipitation of germanium from a solid solution in Al-Ge binary alloys

    NASA Astrophysics Data System (ADS)

    Kardashev, B. K.; Korchunov, B. N.; Nikanorov, S. P.; Osipov, V. N.

    2015-08-01

    The influence of precipitation of germanium atoms in a solid solution on the dependence of the inelasticity characteristics on the germanium content in aluminum-germanium alloys prepared by directional crystallization has been studied. It has been shown that the Young's modulus defect, the amplitude-dependent decrement, and the microplastic flow stress at a specified cyclic strain amplitude have extreme values at the eutectic germanium content in the alloy. The eutectic composition of the alloy undergoes a ductilebrittle transition. It has been found that there is a correlation between the dependences of the Young's modulus defect, amplitude-dependent decrement, microplastic flow stress, and specific entropy of the exothermal process of germanium precipitation on the germanium content in the hypoeutectic alloy. The concentration dependences of the inelasticity characteristics and their changes after annealing have been explained by the change in the resistance to the motion of intragrain dislocations due to different structures of the Guinier-Preston zones formed during the precipitation of germanium atoms.

  17. The Largest Metalloid Group 14 Cluster, Ge18[Si(SiMe3)3]6 : An Intermediate on the Way to Elemental Germanium.

    PubMed

    Kysliak, Oleksandr; Schrenk, Claudio; Schnepf, Andreas

    2016-02-24

    The oxidation of [Ge9(Hyp)3](-) (Hyp=Si(SiMe3 )3) with an Fe(II) salt leads to Ge18 (Hyp)6 (1), the largest Group 14 metalloid cluster that has been structurally characterized to date. The arrangement of the 18 germanium atoms in 1 shows similarities to that found in the solid-state structure Ge(cF136). Furthermore, 1 can be described as a macropolyhedral cluster of two Ge9 units. Quantum-chemical calculations further hint at a strained arrangement so that 1 can be considered as a first trapped intermediate on the way from Ge9 units to elemental germanium with the clathrate-II structure (Ge(cF136)). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. High efficiency beta-decay spectroscopy using a planar germanium double-sided strip detector

    NASA Astrophysics Data System (ADS)

    Larson, N.; Liddick, S. N.; Bennett, M.; Bowe, A.; Chemey, A.; Prokop, C.; Simon, A.; Spyrou, A.; Suchyta, S.; Quinn, S. J.; Tabor, S. L.; Tai, P. L.; Tripathi, Vandana; VonMoss, J. M.

    2013-11-01

    Beta-decay spectroscopy experiments are limited by the detection efficiency of ions and electrons in the experimental setup. While there is a variety of different experimental setups in use for beta-decay spectroscopy, one popular choice is silicon double-sided strip detectors (DSSD). The higher Z of Ge and greater availability of thicker detectors as compared to Si potentially offer dramatic increases in the detection efficiency for beta-decay electrons. In this work, a planar GeDSSD has been commissioned for use in beta-decay spectroscopy experiments at the National Superconducting Cyclotron Laboratory (NSCL). The implantation response of the detector and its beta-decay detection efficiency is discussed.

  19. Average Energy Expended Per Electron-Hole Pair in Germanium Detector for Dark Matter Searches

    NASA Astrophysics Data System (ADS)

    Wei, Wenzhao; Wang, Lu; Mei, Dongming; Cubed Collaboration

    2016-03-01

    The value of ɛ, the average energy expended per electron-hole pair, plays a critical role in determining the energy threshold of a bolometer detector with germanium in dark matter searches. We propose an independent method to estimate the value of ɛ down to milli-Kelvin range, which is the operating temperature for a SuperCDMS-like detector. A theoretical model and experimental analysis algorithm are developed in this work to estimate the value of ɛ based on the relationship between ɛ, detector energy resolution (Fano factor) and the primary phonon energy. We also investigated the energy threshold for a SuperCDMS-like detector with the value of ɛ calculated from our model. In this work, we present our theoretical calculation and show how to use experimental data to evaluate the value of ɛ. Subsequently, we report the temperature dependence of ɛ and its value at 50 milli-Kelvin. This work is supported by NSF in part by the NSF OIA 1434142, DOE Grant DE-FG02-10ER46709, and the State of South Dakota.

  20. Testing the Ge detectors for the MAJORANA DEMONSTRATOR

    SciTech Connect

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

    2015-03-24

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

  1. Testing the Ge detectors for the MAJORANA DEMONSTRATOR

    DOE PAGES

    Xu, W.; Abgrall, N.; Aguayo, E.; ...

    2015-03-24

    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 performances of the HPGe crystals. A variety of crystal properties are being investigated, including both 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 distribution. In this talk, we will present our measurements that characterize the HPGe crystals. In addition, we will discussmore » the experiment’s simulation package for the detector characterization setup, where additional information is learned from data simulation comparisons.« less

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

    SciTech Connect

    Agnese, R.; Balakishiyeva, D.; Saab, T.; Welliver, B.; Anderson, A. J.; Figueroa-Feliciano, E.; Hertel, S. A.; McCarthy, K. A.; Basu Thakur, R.; Bauer, D. A.; Holmgren, D.; Hsu, L.; Loer, B.; Schmitt, R.; Borgland, A.; Brandt, D.; Brink, P. L.; Do Couto E Silva, E.; Godfrey, G. L.; Hasi, J. [SLAC National Accelerator Laboratory 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.

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

    SciTech Connect

    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.

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

    SciTech Connect

    Esch, Ernst I; Jason, Andrew; Miyadera, Haruo; Hoteling, Nathan J; Heffner, Robert H; Adelmann, Andreas; Stocki, Trevor; Mitchell, Lee

    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.

  5. Theoretical and experimental investigation of cosmogenic radioisotope production in germanium

    NASA Astrophysics Data System (ADS)

    Avignone, F. T.; Brodzinski, R. L.; Collar, J. I.; Miley, H. S.; Garcia, E.; Morales, A.; Morales, J.; Nuñez-Lagos, R.; Reeves, J. H.; Saenz, C.; Villar, J. A.

    1992-07-01

    Rates were calculated for the cosmic-ray-induced production of 3H, 54Mn, 57Ni, 57,58Co, 65,67Ga, 65Zn, and 68Ge in natural germanium using two experimental neutron spectra from the literature. Reaction excitation functions were computed with a nuclear spallation code. Experimental production rates of 54Mn, 57,58Co, 65Zn, 67Ga and 68Ge were derived from background spectra of natural isotopic abundance germanium detectors. The rate for 57Co was also derived from data taken with a detector fabricated from germanium isotopically enriched to 86% 76Ge and ˜14% 74Ge. The calculated and experimental data are in agreement within a factor of two and in many cases within 30%.

  6. Evaluation of a new contact technology for a planar high-purity germanium double-sided strip detector

    NASA Astrophysics Data System (ADS)

    Jackson, Emily

    This thesis is an evaluation of a new electrode technology for segmented germanium gamma-ray detectors. The detector assessed herein is a planar high-purity germanium wafer (a LEPS or low-energy photon spectrometer) with 16 photolithographic-deposited, amorphous-germanium contacts on either side. This new contact material is shown to be an improvement over the current standard, lithium and boron electrodes, in both ease-of-manufacture and in performance. The symmetry gained with the use of one material for all the contacts is shown to greatly reduce the difference in energy collected by strips on either side. The stability of the amorphous germanium allows for finer electrode segmentation, reducing the gap between each strip. This smaller gap leads to a more uniform electric field in the active volume and ultimately less charge loss between strips. These improvements are quantified with the analysis of the energy difference and distribution of one- and two-hit interactions in the crystal by mono-energetic gamma rays from a 137Cs source. The detector is shown to be a major step forward in the development of contact technologies necessary for the application of position-sensitive gamma-detection outside of fundamental research, such as in nuclear medicine, astrophysics, and homeland security.

  7. Performance of Ge:Ga far infrared detectors

    NASA Technical Reports Server (NTRS)

    Hueschen, M. R.; Richards, P. L.

    1983-01-01

    A systematic study was carried out of the properties of Ge:Ga photoconductive infrared detectors for wavelengths approx. 100 micron. The detectors studied were made from Ge:Ga with acceptor concentration N sub A approx. 2 x 10 exp 14/cu cm with both low compensation (10 exp -2) and ultralow compensation (10 exp -4). Noise measurements have been made as a function of background photon rate, bias voltage, and chopping frequency. Detective quantum efficiencies approaching unity have been observed over a side range of experimental parameters. Photocurrent has been measured as a function of voltage and temperature. Hall mobility and lifetime have been measured to determine their effect on detector properties. A small potential drop has been observed in nominally ohmic contacts produced by implantation of B ions.

  8. New quaternary thallium indium germanium selenide TlInGe2Se6: Crystal and electronic structure

    NASA Astrophysics Data System (ADS)

    Khyzhun, O. Y.; Parasyuk, O. V.; Tsisar, O. V.; Piskach, L. V.; Myronchuk, G. L.; Levytskyy, V. O.; Babizhetskyy, V. S.

    2017-10-01

    Crystal structure of a novel quaternary thallium indium germanium selenide TlInGe2Se6 was investigated by means of powder X-ray diffraction method. It was determined that the compound crystallizes in the trigonal space group R3 with the unit cell parameters a = 10.1798(2) Å, c = 9.2872(3) Å. The relationship with similar structures was discussed. The as-synthesized TlInGe2Se6 ingot was tested with X-ray photoelectron spectroscopy (XPS) and X-ray emission spectroscopy (XES). In particular, the XPS valence-band and core-level spectra were recorded for initial and Ar+ ion-bombarded surfaces of the sample under consideration. The XPS data allow for statement that the TlInGe2Se6 surface is rigid with respect to Ar+ ion-bombardment. Particularly, Ar+ ion-bombardment (3.0 keV, 5 min duration, ion current density fixed at 14 μA/cm2) did not cause substantial modifications of stoichiometry in topmost surface layers. Furthermore, comparison on a common energy scale of the XES Se Kβ2 and Ge Kβ2 bands and the XPS valence-band spectrum reveals that the principal contributions of the Se 4p and Ge 4p states occur in the upper and central portions of the valence band of TlInGe2Se6, respectively, with also their substantial contributions in other portions of the band. The bandgap energy of TlInGe2Se6 at the level of αg=103 cm-1 is equal to 2.38 eV at room temperature.

  9. Simulation results of Pulse Shape Discrimination (PSD) for background reduction in INTEGRAL Spectrometer (SPI) germanium detectors

    NASA Technical Reports Server (NTRS)

    Slassi-Sennou, S. A.; Boggs, S. E.; Feffer, P. T.; Lin, R. P.

    1997-01-01

    Pulse Shape Discrimination (PSD) for background reduction will be used in the INTErnational Gamma Ray Astrophysics Laboratory (INTEGRAL) imaging spectrometer (SPI) to improve the sensitivity from 200 keV to 2 MeV. The observation of significant astrophysical gamma ray lines in this energy range is expected, where the dominant component of the background is the beta(sup -) decay in the Ge detectors due to the activation of Ge nuclei by cosmic rays. The sensitivity of the SPI will be improved by rejecting beta(sup -) decay events while retaining photon events. The PSD technique will distinguish between single and multiple site events. Simulation results of PSD for INTEGRAL-type Ge detectors using a numerical model for pulse shape generation are presented. The model was shown to agree with the experimental results for a narrow inner bore closed end cylindrical detector. Using PSD, a sensitivity improvement factor of the order of 2.4 at 0.8 MeV is expected.

  10. Simulation results of Pulse Shape Discrimination (PSD) for background reduction in INTEGRAL Spectrometer (SPI) germanium detectors

    NASA Technical Reports Server (NTRS)

    Slassi-Sennou, S. A.; Boggs, S. E.; Feffer, P. T.; Lin, R. P.

    1997-01-01

    Pulse Shape Discrimination (PSD) for background reduction will be used in the INTErnational Gamma Ray Astrophysics Laboratory (INTEGRAL) imaging spectrometer (SPI) to improve the sensitivity from 200 keV to 2 MeV. The observation of significant astrophysical gamma ray lines in this energy range is expected, where the dominant component of the background is the beta(sup -) decay in the Ge detectors due to the activation of Ge nuclei by cosmic rays. The sensitivity of the SPI will be improved by rejecting beta(sup -) decay events while retaining photon events. The PSD technique will distinguish between single and multiple site events. Simulation results of PSD for INTEGRAL-type Ge detectors using a numerical model for pulse shape generation are presented. The model was shown to agree with the experimental results for a narrow inner bore closed end cylindrical detector. Using PSD, a sensitivity improvement factor of the order of 2.4 at 0.8 MeV is expected.

  11. Synthesis and characterization of a cadmium germanium phosphate CdGe(OH){sub 3}PO{sub 4} with an open framework

    SciTech Connect

    Liu Yan; Yang Xiaoli; Wang Guili; Zhang Jun; Li Yizhi; Du Hongbin You Xiaozeng

    2008-09-15

    A new three-dimensional (3D) framework cadmium germanium phosphate, CdGe(OH){sub 3}PO{sub 4} was synthesized by solvothermal methods. The crystal structure of CdGe(OH){sub 3}PO{sub 4} was established by single-crystal X-ray diffraction: CdGeH{sub 3}O{sub 7}P, Orthorhombic, Cmca, a=7.1415(7) A, b=10.9034(1) A, c=13.1098(1) A, Z=8, R{sub 1}=0.0365 (F{sup 2}>2{sigma}(F{sup 2}) and wR{sub 2}=0.0985 (all data). The framework of CdGe(OH){sub 3}PO{sub 4} is built by a mixed network of GeO{sub 6}, CdO{sub 6} octahedra and PO{sub 4} tetrahedra, which are linked to form a 3-membered ring (3-MR). The GeO{sub 6} and CdO{sub 6} octahedra share common vertexes and edges, respectively, to form one-dimensional (1D) Ge-O-Ge and Cd-O-Cd chains, which are further connected forming corrugated Ge-O-Cd layers. The layers are linked by PO{sub 4} tetrahedra, leading to a 3D open-framework structure with 3- and 6-MR channels. - Graphical abstract: A new three-dimensional framework cadmium germanium phosphate, CdGe(OH){sub 3}PO{sub 4} was synthesized by solvothermal methods. The framework of CdGe(OH){sub 3}PO{sub 4} is built by a mixed network of GeO{sub 6} octahedra, CdO{sub 6} octahedra and PO{sub 4} tetrahedra and contains a network of one-dimensional 3 and 6-membered ring channels. It belongs to a class of metal germanium phosphates with an open framework.

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Structural properties of relaxed thin film germanium layers grown by low temperature RF-PECVD epitaxy on Si and Ge (100) substrates

    SciTech Connect

    Cariou, R.; Ruggeri, R.; Tan, X.; Nassar, J.; Roca i Cabarrocas, P.; Mannino, Giovanni

    2014-07-15

    We report on unusual low temperature (175 °C) heteroepitaxial growth of germanium thin films using a standard radio-frequency plasma process. Spectroscopic ellipsometry and transmission electron microscopy (TEM) reveal a perfect crystalline quality of epitaxial germanium layers on (100) c-Ge wafers. In addition direct germanium crystal growth is achieved on (100) c-Si, despite 4.2% lattice mismatch. Defects rising from Ge/Si interface are mostly located within the first tens of nanometers, and threading dislocation density (TDD) values as low as 10{sup 6} cm{sup −2} are obtained. Misfit stress is released fast: residual strain of −0.4% is calculated from Moiré pattern analysis. Moreover we demonstrate a striking feature of low temperature plasma epitaxy, namely the fact that crystalline quality improves with thickness without epitaxy breakdown, as shown by TEM and depth profiling of surface TDD.

  15. 12 GeV detector technology at Jefferson Lab

    SciTech Connect

    Leckey, John P.; Collaboration: GlueX Collaboration

    2013-04-19

    The Thomas Jefferson National Accelerator Facility (JLab) is presently in the middle of an upgrade to increase the energy of its CW electron beam from 6 GeV to 12 GeV along with the addition of a fourth experimental hall. Driven both by necessity and availability, novel detectors and electronics modules have been used in the upgrade. One such sensor is the Silicon Photomultiplier (SiPM), specifically a Multi-Pixel Photon Counter (MPPC), which is an array of avalanche photodiode pixels operating in Geiger mode that are used to sense photons. The SiPMs replace conventional photomultiplier tubes and have several distinct advantages including the safe operation in a magnetic field and the lack of need for high voltage. Another key to 12 GeV success is advanced fast electronics. Jlab will use custom 250 MHz and 125 MHz 12-bit analog to digital converters (ADCs) and time to digital converters (TDCs) all of which take advantage of VME Switched Serial (VXS) bus with its GB/s high bandwidth readout capability. These new technologies will be used to readout drift chambers, calorimeters, spectrometers and other particle detectors at Jlab once the 12 GeV upgrade is complete. The largest experiment at Jlab utilizing these components is GlueX - an experiment in the newly constructed Hall D that will study the photoproduction of light mesons in the search for hybrid mesons. The performance of these components and their respective detectors will be presented.

  16. 12 GeV detector technology at Jefferson Lab

    SciTech Connect

    Leckey, John P.

    2013-04-01

    The Thomas Jefferson National Accelerator Facility (JLab) is presently in the middle of an upgrade to increase the energy of its CW electron beam from 6 GeV to 12 GeV along with the addition of a fourth experimental hall. Driven both by necessity and availability, novel detectors and electronics modules have been used in the upgrade. One such sensor is the Silicon Photomultiplier (SiPM), specifically a Multi-Pixel Photon Counter (MPPC), which is an array of avalanche photodiode pixels operating in Geiger mode that are used to sense photons. The SiPMs replace conventional photomultiplier tubes and have several distinct advantages including the safe operation in a magnetic field and the lack of need for high voltage. Another key to 12 GeV success is advanced fast electronics. Jlab will use custom 250 MHz and 125 MHz 12-bit analog to digital converters (ADCs) and time to digital converters (TDCs) all of which take advantage of VME Switched Serial (VXS) bus with its GB/s high bandwidth readout capability. These new technologies will be used to readout drift chambers, calorimeters, spectrometers and other particle detectors at Jlab once the 12 GeV upgrade is complete. The largest experiment at Jlab utilizing these components is GlueX - an experiment in the newly constructed Hall D that will study the photoproduction of light mesons in the search for hybrid mesons. The performance of these components and their respective detectors will be presented.

  17. 12 GeV detector technology at Jefferson Lab

    NASA Astrophysics Data System (ADS)

    Leckey, John P.; GlueX Collaboration

    2013-04-01

    The Thomas Jefferson National Accelerator Facility (JLab) is presently in the middle of an upgrade to increase the energy of its CW electron beam from 6 GeV to 12 GeV along with the addition of a fourth experimental hall. Driven both by necessity and availability, novel detectors and electronics modules have been used in the upgrade. One such sensor is the Silicon Photomultiplier (SiPM), specifically a Multi-Pixel Photon Counter (MPPC), which is an array of avalanche photodiode pixels operating in Geiger mode that are used to sense photons. The SiPMs replace conventional photomultiplier tubes and have several distinct advantages including the safe operation in a magnetic field and the lack of need for high voltage. Another key to 12 GeV success is advanced fast electronics. Jlab will use custom 250 MHz and 125 MHz 12-bit analog to digital converters (ADCs) and time to digital converters (TDCs) all of which take advantage of VME Switched Serial (VXS) bus with its GB/s high bandwidth readout capability. These new technologies will be used to readout drift chambers, calorimeters, spectrometers and other particle detectors at Jlab once the 12 GeV upgrade is complete. The largest experiment at Jlab utilizing these components is GlueX - an experiment in the newly constructed Hall D that will study the photoproduction of light mesons in the search for hybrid mesons. The performance of these components and their respective detectors will be presented.

  18. Identification of single-site events in germanium detectors by digital pulse shape analysis

    NASA Astrophysics Data System (ADS)

    Hellmig, J.; Klapdor-Kleingrothaus, H. V.

    2000-12-01

    A method that discriminates between single- and multiple-site interactions in germanium detectors was developed. For this purpose the output of customary charge-sensitive preamplifiers was differentiated with 10-20 ns sampled with 250 MHz and analyzed off-line. Multiple-site interactions were measured in the 1621 keV photo peak and single-site events in the 1592 keV double escape line of 208Tl. One single parameter describing the broadness of the charge pulse maximum is sufficient to achieve 80% detection efficiencies for both the interaction types, over a wide energy range. As examples, employment of the method in the Heidelberg-Moscow experiment resulted in the consistent half-life of two neutrino double beta decay and the reduction of the background by a factor of three in searches for the neutrinoless double beta decay. Identification of single Compton scattered events improved the minimal detectable activity of a 25% efficiency detector by a factor of two.

  19. Covariance analysis and fitting of germanium gamma-ray detector efficiency calibration data

    NASA Astrophysics Data System (ADS)

    Geraldo, L. P.; Smith, D. L.

    1990-05-01

    The measurement of neutron-induced reaction cross sections often requires detection of either prompt gamma rays or gamma rays emitted during the decay of radio nuclides. This paper describes the analytical procedures we use to generate calibrations for germanium gamma-ray detector full-energy-peak efficiency ɛ versus photon energy E, and to predict the associated uncertainties. Our method, which involves fitting a parameterized regression formula to measured data by the principle of least squares, is widely applicable beyond the specific problem considered here. It differs from most commonly used methods in that comprehensive use is made of available information on all known sources of random and systematic (correlated) error associated with the calibration process. This is accomplished through the formation and application of a calibration-data covariance matrix. Objective prediction of the errors in subsequently derived quantities (e.g., detector efficiencies at energies not directly represented in the calibration data) is then achieved through error propagation. Specifically, this paper discusses our experiences in fitting the particular empirical formula In ɛ = Σk-1 mpk(In E) k-1 to measured calibration data at gamma-ray energies from just above 200 keV to several MeV. A numerical example is provided to demonstrate the utility of this approach.

  20. New techniques and results in {sup 76}Ge double-beta decay

    SciTech Connect

    Miley, H.S.; Brodzinski, R.L.; Hensley, W.K.; Reeves, J.H.; Avignone, F.T.

    1991-09-01

    Several methods of lowering the background in germanium double-beta decay experiments are discusses. A technique for increasing confidence in double-beta decay measurements by variation of detector enrichment is demonstrated in the case of two-neutrino decay mode of {sup 76}Ge. The impact of cosmic ray spallation in low-background isotopically enriched germanium detectors is examined.

  1. New techniques and results in sup 76 Ge double-beta decay

    SciTech Connect

    Miley, H.S.; Brodzinski, R.L.; Hensley, W.K.; Reeves, J.H. ); Avignone, F.T. . Dept. of Physics)

    1991-09-01

    Several methods of lowering the background in germanium double-beta decay experiments are discusses. A technique for increasing confidence in double-beta decay measurements by variation of detector enrichment is demonstrated in the case of two-neutrino decay mode of {sup 76}Ge. The impact of cosmic ray spallation in low-background isotopically enriched germanium detectors is examined.

  2. Advanced Ge detectors for gamma-ray astronomy

    NASA Technical Reports Server (NTRS)

    Varnell, Larry S.

    1991-01-01

    Externally segmented coaxial detectors are fabricated for high efficiency in detecting gamma rays from cosmic sources with good sensitivities. The external background is reduced by enclosing the Ge detector array inside a thick active shield. The outer electrode of the coaxial detectors is subdivided into five segments, and internal beta activity is rejected by operating the segmented detector in a multisegment mode. The multisegment mode requires that events be detected in two or more segments before they are recorded. The full-energy-peak (FEP) efficiency of the unit is tested as a function of the incident gamma-ray energy and of the discriminator threshold of the segments. Measurements of beta-rejection and FEP efficiency are compared with Monte Carlo calculations, and good agreement is noted.

  3. Surfactant-mediated epitaxy of thin germanium films on SiGe(001) virtual substrates

    NASA Astrophysics Data System (ADS)

    Schmidt, J.; Tetzlaff, D.; Bugiel, E.; Wietler, T. F.

    2017-01-01

    We report on the impact of a surfactant on the growth mode and strain relaxation of thin Ge films on Si0.21Ge0.79 virtual substrates grown by surfactant mediated epitaxy on Si(001) wafers. Ge epitaxy without surfactant results in island formation after deposition of only 5 nm Ge. A certain part of the strain in the Ge islands is relaxed via interfacial misfit dislocations, which are located within the core part of the islands. We discuss the possibilities for the occurrence of three-dimensional growth at low Ge layer thickness. The use of Sb as a surfactant suppresses three-dimensional islanding and enables the growth of smooth pseudomorphically strained Ge films on Si0.21Ge0.79(001) virtual substrates up to a thickness of 10 nm. At thicknesses higher than 20 nm, the films relax via the formation of a misfit dislocation network at the Ge/ Si1-xGex interface. The surface roughness of up to 30 nm thick layers is below 1.6 nm. Our experimental results corroborate the calculated thickness for plastic relaxation of Ge on Si1-xGex. The effect of the surfactant on the growth of the virtual substrate and on the subsequent growth of Ge on Si0.21Ge0.79 is discussed.

  4. Insights into thermal diffusion of germanium and oxygen atoms in HfO{sub 2}/GeO{sub 2}/Ge gate stacks and their suppressed reaction with atomically thin AlO{sub x} interlayers

    SciTech Connect

    Ogawa, Shingo; Asahara, Ryohei; Minoura, Yuya; Hosoi, Takuji Shimura, Takayoshi; Watanabe, Heiji; Sako, Hideki; Kawasaki, Naohiko; Yamada, Ichiko; Miyamoto, Takashi

    2015-12-21

    The thermal diffusion of germanium and oxygen atoms in HfO{sub 2}/GeO{sub 2}/Ge gate stacks was comprehensively evaluated by x-ray photoelectron spectroscopy and secondary ion mass spectrometry combined with an isotopic labeling technique. It was found that {sup 18}O-tracers composing the GeO{sub 2} underlayers diffuse within the HfO{sub 2} overlayers based on Fick's law with the low activation energy of about 0.5 eV. Although out-diffusion of the germanium atoms through HfO{sub 2} also proceeded at the low temperatures of around 200 °C, the diffusing germanium atoms preferentially segregated on the HfO{sub 2} surfaces, and the reaction was further enhanced at high temperatures with the assistance of GeO desorption. A technique to insert atomically thin AlO{sub x} interlayers between the HfO{sub 2} and GeO{sub 2} layers was proven to effectively suppress both of these independent germanium and oxygen intermixing reactions in the gate stacks.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. The development of a segmented N-type germanium detector, and its application to astronomical gamma-ray spectroscopy

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    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. Previously announced in STAR as N84-13039

  7. The development of a segmented N-type germanium detector, and its application to astronomical gamma-ray spectroscopy

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    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. Previously announced in STAR as N84-13039

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

    SciTech Connect

    Howard, Chris; Daigle, Stephen; Buckner, Matt; Erikson, Luke E.; Runkle, Robert C.; Stave, Sean C.; Champagne, Art; Cooper, Andrew; Downen, Lori; Glasgow, Brian D.; Kelly, Keegan; Sallaska, Anne

    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.

  9. Germanium Isotope Measurements Using Double-Spike HG MC-ICP-MS: Results From Geothermal Fluids and Implications for the use of Ge/Si as a Paleoproxy

    NASA Astrophysics Data System (ADS)

    Siebert, C.; McManus, J.; Hammond, D.

    2005-12-01

    Numerous reports have documented the close coupling between dissolved germanic and silicic acids throughout the global ocean. Despite the apparent similarity in their oceanic behaviors, Ge and Si exhibit marked differences in their oceanic sources and sinks. Rivers supply most of the silica to the modern ocean whereas opaline marine sediments are the primary sink. In contrast to silica, germanium has two primary sources: rivers and hydrothermal inputs, and two sink terms: opaline sediments and reducing continental margin sediments. The differences in the relative importance of the source terms for Ge and Si, combined with the fact that siliceous microfossils may record water column Ge/Si, led to the proposal that the Ge:Si ratio recorded in diatoms could serve as a monitor for the relative importance of these two sources through time. However, an additional large non-opal sink for Ge complicates the interpretation of variations in the oceanic Ge:Si ratio. Distinctive Ge isotope signatures could provide additional constraints for the Ge cycle that would permit the relative rates of weathering and hydrothermal inputs to be deduced provided that Ge isotopes consistently fractionate during at least one of these processes. For our work on Ge isotopes, we use a hydride generation double spike (HG-DS) technique to determine the natural mass dependent isotope fractionation of germanium. The HG-DS technique has multiple advantages, which include correction of analytical mass bias and high sensitivity. We measured high-T geothermal fluids from a number of locations in the Oregon Cascades for their Ge isotope composition and Ge:Si ratios. All samples show light Ge isotope compositions ranging from -1 to -2 permil relative to a JMC laboratory standard. Corresponding Ge:Si ratios range from 6 to 74 micromol/mol. These ratios are higher than those from typical low-temperature weathered fluids (ca. 1) and those of bedrock (3 or lower), and are more elevated than Ge:Si ratios from

  10. Enhanced germanium precipitation and nanocrystal growth in the Ge+ ion-implanted SiO2 films during high-pressure annealing

    NASA Astrophysics Data System (ADS)

    Tyschenko, Ida E.; Volodin, Vladimir A.; Cherkov, Alexander G.

    2016-12-01

    The effect of pressure employed during subsequent annealing of the Ge+-ion implanted SiO2 layers on the Ge nanocrystal formation was studied. Ge+ ions implanted in the thin SiO2 layers formed Gauss-like profiles with a Ge peak concentration varied from 1 to 12 at%. Subsequent annealing was carried out at temperature 600-1130 °C under pressures 1-1.2×104 bar. Strong effect of the pressure on the Ge atom distribution was obtained. High-temperature annealing under pressure within the range of 1-103 bar resulted in the out-diffusion of germanium from the SiO2 layer to the Si substrate. As the pressure reached 1.2×104 bar, Ge migration to the Si/SiO2 interface was prevented. At that, the Ge nanocrystal growth within the ion-implanted region of the SiO2 film took place. The nanocrystal size was investigated as a function both of the Ge atom concentration and the annealing temperature. The obtained results show a diffusion-controlled nanocrystal growth mechanism. The high-pressure (1.2×104 bar) diffusion coefficient of germanium in silicon dioxide was estimated as a function of the temperature and expressed by D=1.1×10-10 exp(-1.43 eV/kT) cm2/s.

  11. Features of the stress-strain state of Si/SiO{sub 2}/Ge heterostructures with germanium nanoislands of a limited density

    SciTech Connect

    Kuryliuk, V. V. Korotchenkov, O. A.

    2013-08-15

    Within the elastic continuum model, with the use of the finite-element method, the stress-strain state of silicon-germanium heterostructures with semispherical germanium islands grown on an oxidized silicon surface is calculated. It is shown that as the density of islands is increased to limiting values, in the SiGe structure with open quantum dots the value and spatial distribution of the elastic-strain fields significantly change. The results of theoretical calculation allow the heterostructure portions with the maximum variation in the stress-strain state to be determined. The position of such a portions can be controlled by changing the density of islands.

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

    PubMed Central

    Campbell, DL; Peterson, TE

    2014-01-01

    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. PMID:25360792

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

    PubMed

    Campbell, D L; Peterson, T E

    2014-11-21

    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.

  14. Energy dependent chest wall thickness equations for male lung monitoring with germanium detectors.

    PubMed

    Broggio, D; Lechaftois, X; Abline, O; Fleury, B; Vial, A; Corrèze, P; Franck, D; Merzoug, V

    2014-03-01

    The thickness and fat fraction of the chest wall are important parameters for in vivo lung monitoring. They have been measured from ultrasonic images on 374 male workers of the French nuclear industry using four measurement locations, as dictated by the size and position of the germanium detectors used for monitoring. The plastic muscle equivalent chest wall thickness (PMECWT) and the plastic 50% muscle-50% adipose equivalent chest wall thickness (X5050) have been calculated for each worker at 17, 59.5, and 185.7 keV, respectively. Multi-linear regression models have been tested to predict PMECWT and X5050 as a function of anthropometric measurements. Finally, it was considered whether the average chest wall thickness could be used instead of the material equivalent chest wall thickness. It was found that the mean chest wall thickness was (27 ± 5) mm and the mean fat fraction was (25 ± 8)%. The best and more convenient model for material equivalent chest wall thickness is a linear function of the body mass index. Depending on the energy, the standard errors of estimate for this model range between 3.2-3.4 mm for PMECWT and between 3.2-3.7 mm for X5050. At 59.5 and 185.7 keV, it was determined, to an excellent approximation, that the fat fraction and consideration of an equivalent material are unnecessary, contrary to the case at 17 keV.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Room Temperature Ferromagnetic, Anisotropic, Germanium Rich FeGe(001) Alloys.

    PubMed

    Lungu, George A; Apostol, Nicoleta G; Stoflea, Laura E; Costescu, Ruxandra M; Popescu, Dana G; Teodorescu, Cristian M

    2013-02-21

    Ferromagnetic FexGe1-x with x = 2%-9% are obtained by Fe deposition onto Ge(001) at high temperatures (500 °C). Low energy electron diffraction (LEED) investigation evidenced the preservation of the (1 × 1) surface structure of Ge(001) with Fe deposition. X-ray photoelectron spectroscopy (XPS) at Ge 3d and Fe 2p core levels evidenced strong Fe diffusion into the Ge substrate and formation of Ge-rich compounds, from FeGe₃ to approximately FeGe₂, depending on the amount of Fe deposited. Room temperature magneto-optical Kerr effect (MOKE) evidenced ferromagnetic ordering at room temperature, with about 0.1 Bohr magnetons per Fe atom, and also a clear uniaxial magnetic anisotropy with the in-plane easy magnetization axis. This compound is a good candidate for promising applications in the field of semiconductor spintronics.

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

    SciTech Connect

    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

  18. Efficiency as a function of MEQ-CWT for large area germanium detectors using LLNL phantom.

    PubMed

    Rajaram, S; Brindha, J Thulasi; Sreedevi, K R; Hegde, A G

    2012-01-01

    The lung counting system at Kalpakkam, India, used for the estimation of transuranics deposited in the lungs of occupational workers, consists of an array of three large area germanium detectors fixed in a single assembly. The efficiency calibration for low energy photons was carried out using ²⁴¹Am and ²³²Th lung sets of Lawrence Livermore National Laboratory phantom. The muscle equivalent chest wall thickness (MEQ-CWT) was derived for the three energies 59.5, 75.95 (average energy of ²³²Th) and 238.9 keV for the series of overlay plates made of different adipose mass ratios. Efficiency as a function of MEQ-CWT was calculated for individual detectors for the three energies. Variation of MEQ-CWT from 16 to 40 mm resulted in an efficiency variation of around 40 % for all the three energies. The array efficiency for different MEQ-CWT ranged from 1.4×10⁻³ to 3.2×10⁻³, 1.5×10⁻³ to 3.3×10⁻³ and 1.1×10⁻³ to 2.3×10⁻³ for 59.5, 75.95 and 238.9 keV, respectively. In the energy response, efficiency was observed to be maximum for 75.95 keV compared with 59.5 and 238.9 keV.

  19. Sacrificial Silver Nanoparticles: Reducing GeI2 To Form Hollow Germanium Nanoparticles by Electroless Deposition.

    PubMed

    Nolan, Bradley M; Chan, Eric K; Zhang, Xinming; Muthuswamy, Elayaraja; van Benthem, Klaus; Kauzlarich, Susan M

    2016-05-24

    Herein we report the electroless deposition of Ge onto sacrificial Ag nanoparticle (NP) templates to form hollow Ge NPs. The formation of AgI is a necessary component for this reaction. Through a systematic study of surface passivating ligands, we determined that tri-n-octylphosphine is necessary to facilitate the formation of hollow Ge NPs by acting as a transport agent for GeI2 and the oxidized Ag(+) cation (i.e., AgI product). Annular dark-field (ADF) scanning transmission electron microscopy (STEM) imaging of incomplete reactions revealed Ag/Ge core/shell NPs; in contrast, completed reactions displayed hollow Ge NPs with pinholes which is consistent with the known method for dissolution of the nanotemplate. Characterization of the hollow Ge NPs was performed by transmission electron microscopy, ADF-STEM, energy-dispersive X-ray spectroscopy, UV-vis spectrophotometry, and Raman spectroscopy. The galvanic replacement reaction of Ag with GeI2 offers a versatile method for controlling the structure of Ge nanomaterials.

  20. Detector development for Jefferson Lab's 12GeV Upgrade

    SciTech Connect

    Qiang, Yi

    2015-05-01

    Jefferson Lab will soon finish its highly anticipated 12 GeV Upgrade. With doubled maximum energy, Jefferson Lab’s Continuous Electron Beam Accelerator Facility (CEBAF) will enable a new experimental program with substantial discovery potential, addressing important topics in nuclear, hadronic and electroweak physics. In order to take full advantage of the high energy, high luminosity beam, new detectors are being developed, designed and constructed to fit the needs of different physics topics. The paper will give an overview of various new detector technologies to be used for 12 GeV experiments. It will then focus on the development of two solenoid-based spectrometers, the GlueX and SoLID spectrometers. The GlueX experiment in Hall D will study the complex properties of gluons through exotic hybrid meson spectroscopy. The GlueX spectrometer, a hermetic detector package designed for spectroscopy and the associated partial wave analysis, is currently in the final stage of construction. Hall A, on the other hand, is developing the SoLID spectrometer to capture the 3D image of the nucleon from semi-inclusive processes and to study the intrinsic properties of quarks through mirror symmetry breaking. Such a spectrometer will have the capability to handle very high event rates while still maintaining a large acceptance in the forward region.

  1. Detector development for Jefferson Lab's 12GeV Upgrade

    DOE PAGES

    Qiang, Yi

    2015-05-01

    Jefferson Lab will soon finish its highly anticipated 12 GeV Upgrade. With doubled maximum energy, Jefferson Lab’s Continuous Electron Beam Accelerator Facility (CEBAF) will enable a new experimental program with substantial discovery potential, addressing important topics in nuclear, hadronic and electroweak physics. In order to take full advantage of the high energy, high luminosity beam, new detectors are being developed, designed and constructed to fit the needs of different physics topics. The paper will give an overview of various new detector technologies to be used for 12 GeV experiments. It will then focus on the development of two solenoid-based spectrometers,more » the GlueX and SoLID spectrometers. The GlueX experiment in Hall D will study the complex properties of gluons through exotic hybrid meson spectroscopy. The GlueX spectrometer, a hermetic detector package designed for spectroscopy and the associated partial wave analysis, is currently in the final stage of construction. Hall A, on the other hand, is developing the SoLID spectrometer to capture the 3D image of the nucleon from semi-inclusive processes and to study the intrinsic properties of quarks through mirror symmetry breaking. Such a spectrometer will have the capability to handle very high event rates while still maintaining a large acceptance in the forward region.« less

  2. High-Temperature Crystal Structure and Chemical Bonding in Thermoelectric Germanium Selenide (GeSe).

    PubMed

    Sist, Mattia; Gatti, Carlo; Nørby, Peter; Cenedese, Simone; Kasai, Hidetaka; Kato, Kenichi; Iversen, Bo B

    2017-05-17

    The discovery of the ultra-high thermoelectric figure of merit of 2.6 in SnSe has drawn attention to other lead-free IV-VI orthorhombic semiconductors. GeSe has been predicted to possess thermoelectric performances comparable to SnSe. Here, a complete structural study is reported of GeSe with temperature by means of high-resolution synchrotron powder X-ray diffraction. In the orthorhombic phase, the evolution of the bond distances with temperature is shown to deviate significantly with respect to SnSe. Analysis of the chemical bonding within the Quantum Theory of Atoms in Molecules shows that GeSe is ionic with van der Waals interlayer interactions. The signature of the N shell lone pair of Ge is also evident from both the electron density Laplacian and the ELF topologies. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Germanium subcells for multijunction GaInP/GaInAs/Ge solar cells

    SciTech Connect

    Kalyuzhnyy, N. A.; Gudovskikh, A. S.; Evstropov, V. V.; Lantratov, V. M.; Mintairov, S. A.; Timoshina, N. Kh.; Shvarts, M. Z.; Andreev, V. M.

    2010-11-15

    Photovoltaic converters based on n-GaInP/n-p-Ge heterostructures grown by the OMVPE under different conditions of formation of the p-n junction are studied. The heterostructures are intended for use as narrow-gap subcells of the GaInP/GaInAs/Ge three-junction solar cells. It is shown that, in Ge p-tn junctions, along with the diffusion mechanism, the tunneling mechanism of the current flow exists; therefore, the two-diode electrical equivalent circuit of the Ge p-n junction is used. The diode parameters are determined for both mechanisms from the analysis of both dark and 'light' current-voltage dependences. It is shown that the elimination of the component of the tunneling current allows one to increase the efficiency of the Ge subcell by {approx}1% with conversion of nonconcentrated solar radiation. The influence of the tunneling current on the efficiency of the Ge-based devices can be in practice reduced to zero at photogenerated current density of {approx}1.5 A/cm{sup 2} due to the use of the concentrated solar radiation.

  4. Mechanisms of Si and Ge diffusion on surfactant terminated (111) silicon and germanium surfaces

    NASA Astrophysics Data System (ADS)

    Zhachuk, R.; Coutinho, J.

    2016-05-01

    Surfactant mediated growth of Ge layers and formation of small Ge clusters on Si(111) are promising assemblage processes with envisioned applications in areas such as nanoelectronics or photovoltaics. They critically depend on migration of Si and Ge adatoms on surfactant terminated Si(111) and Ge(111) surfaces. We address Si and Ge adsorption and migration on surfactant (Bi, Sb) terminated (111) surfaces of Si and strained Ge by comprehensively mapping potential energy surfaces using density functional calculations. The main migration paths are identified and corresponding energy barriers are reported. It is shown that the energy barrier for adatom migration through Bi or Sb surfactant trimers (by actually breaking the trimers) is virtually degenerate to the mechanism involving traveling of the adatom around the same surfactant structures. We also find a low-energy anchoring site that is suggested to act as a nucleation structure and to trigger the clustering process. These results suggest a fundamentally new picture for the whole Si(111)sbnd Bi(Sb) epitaxial process.

  5. Barrelane-like germanium clusters in Eu 3Ge 5: Crystal structure, chemical bonding and physical properties

    NASA Astrophysics Data System (ADS)

    Budnyk, Sergij; Weitzer, Franz; Kubata, Christof; Prots, Yurii; Akselrud, Lev G.; Schnelle, Walter; Hiebl, Kurt; Nesper, Reinhard; Wagner, Frank R.; Grin, Yuri

    2006-08-01

    Formation and crystal structure of the binary germanide Eu 3Ge 5 were investigated in detail. The compound forms peritectically at 1008 °C and does not undergo any phase transition down to room temperature. The crystal structure was determined first from X-ray powder diffraction data and was later confirmed by single-crystal X-ray diffraction: structure type Pu 3Pd 5, space group Cmcm (no. 63), a=9.7675(4) Å, b=7.9681(3) Å, c=9.8562(3) Å. The main building blocks are Ge 56- cluster anions surrounded by Eu 2+ cations. The nearly tetragonal-pyramidal shape is suggested by the interatomic distances. Contrary to that, the bonding analysis with the electron localization function (ELF) reveals only two- and three-bonded germanium atoms forming a strongly distorted [1.1.1]-barrelane-like cluster. Despite the formal electron deficiency, compared to the barrelane C 5H 8, the electron counting in the cluster anion and its conformation cannot be interpreted applying the Wade's rules. In accordance with the calculated electronic density of states, Eu 3Ge 5 shows a metal-like temperature dependence of the electrical resistivity with a sharp change of ρ(T) slope at the Néel point. Above the Néel point the inverse magnetic susceptibility reveals Curie-Weiss behavior with an effective moment of 8.11 μB (Eu 2+, 4 f7 configuration) in agreement with the analysis of the chemical bonding. The 4 f7 electronic configuration of europium is confirmed by Eu- LIII X-ray absorption spectroscopy.

  6. Probing Sub-GeV Dark Matter with Conventional Detectors.

    PubMed

    Kouvaris, Chris; Pradler, Josef

    2017-01-20

    The direct detection of dark matter particles with mass below the GeV scale is hampered by soft nuclear recoil energies and finite detector thresholds. For a given maximum relative velocity, the kinematics of elastic dark matter nucleus scattering sets a principal limit on detectability. Here, we propose to bypass the kinematic limitations by considering the inelastic channel of photon emission from bremsstrahlung in the nuclear recoil. Our proposed method allows us to set the first limits on dark matter below 500 MeV in the plane of dark matter mass and cross section with nucleons. In situations where a dark-matter-electron coupling is suppressed, bremsstrahlung may constitute the only path to probe low-mass dark matter awaiting new detector technologies with lowered recoil energy thresholds.

  7. Probing Sub-GeV Dark Matter with Conventional Detectors

    NASA Astrophysics Data System (ADS)

    Kouvaris, Chris; Pradler, Josef

    2017-01-01

    The direct detection of dark matter particles with mass below the GeV scale is hampered by soft nuclear recoil energies and finite detector thresholds. For a given maximum relative velocity, the kinematics of elastic dark matter nucleus scattering sets a principal limit on detectability. Here, we propose to bypass the kinematic limitations by considering the inelastic channel of photon emission from bremsstrahlung in the nuclear recoil. Our proposed method allows us to set the first limits on dark matter below 500 MeV in the plane of dark matter mass and cross section with nucleons. In situations where a dark-matter-electron coupling is suppressed, bremsstrahlung may constitute the only path to probe low-mass dark matter awaiting new detector technologies with lowered recoil energy thresholds.

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

    SciTech Connect

    Reuben Walter Ogburn, IV

    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 analyzed all data from the two runs together in a single

  9. Particle dark matter and solar axion searches with a small germanium detector at the Canfranc Underground Laboratory

    NASA Astrophysics Data System (ADS)

    Morales, A.; Avignone, F. T., III; Brodzinski, R. L.; Cebrián, S.; García, E.; González, D.; Irastorza, I. G.; Miley, H. S.; Morales, J.; de Solórzano, A. Ortiz; Puimedón, J.; Reeves, J. H.; Sarsa, M. L.; Scopel, S.; Villar, J. A.

    2002-01-01

    A small, natural abundance, germanium detector (COSME) has been operating recently at the Canfranc Underground Laboratory (Spanish Pyrenees) in improved conditions of shielding and overburden with respect to a previous operation of the same detector (Nucl. Instrum. Meth. A 321 (1992) 410; Phys. Rev. D 51 (1995) 1458). An exposure of 72.7 kg day in these conditions has at present a background improvement of about one order of magnitude compared to the former operation of the detector. These new data have been applied to a direct search for weakly interacting massive particles (WIMPs) and solar axions. New WIMP exclusion plots improving the current bounds for low masses are reported. The paper also presents a limit on the axion-photon coupling obtained from the analysis of the data looking for a Primakoff axion-to-photon conversion and Bragg scattering inside the crystal.

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

    SciTech Connect

    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.

  11. Synthesis and the crystal and molecular structure of the germanium(IV) complex with propylene-1,3-diaminetetraacetic acid [Ge(Pdta)

    SciTech Connect

    Sergienko, V. S.; Martsinko, E. E.; Seifullina, I. I.; Churakov, A. V.; Chebanenko, E. A.

    2015-09-15

    The germanium(IV) complex with propylene-1,3-diaminetetraacetic acid (H{sub 4}Pdta) is studied by elemental analysis, X-ray diffraction, thermogravimetry, and IR spectroscopy. The X-ray diffraction study reveals two crystallographically independent [Ge(Pdta)] molecules of similar structure. Both Ge atoms are octahedrally coordinated by four O atoms and two N atoms (at the cis positions) of the hexadentate pentachelate Pdta{sup 4–} ligand. An extended system of weak C—H···O hydrogen bonds connects complex molecules into a supramolecular 3D framework.

  12. Synthesis and the crystal and molecular structure of the germanium(IV) complex with propylene-1,3-diaminetetraacetic acid [Ge( Pdta)

    NASA Astrophysics Data System (ADS)

    Sergienko, V. S.; Martsinko, E. E.; Seifullina, I. I.; Churakov, A. V.; Chebanenko, E. A.

    2015-09-01

    The germanium(IV) complex with propylene-1,3-diaminetetraacetic acid (H4 Pdta) is studied by elemental analysis, X-ray diffraction, thermogravimetry, and IR spectroscopy. The X-ray diffraction study reveals two crystallographically independent [Ge( Pdta)] molecules of similar structure. Both Ge atoms are octahedrally coordinated by four O atoms and two N atoms (at the cis positions) of the hexadentate pentachelate Pdta 4- ligand. An extended system of weak С—Н···О hydrogen bonds connects complex molecules into a supramolecular 3D framework.

  13. Local structure of germanium-sulfur, germanium-selenium, and germanium-tellurium vitreous alloys

    SciTech Connect

    Bordovsky, G. A.; Terukov, E. I.; Anisimova, N. I.; Marchenko, A. V.; Seregin, P. P.

    2009-09-15

    {sup 119}Sn and {sup 129}Te ({sup 129}I) Moessbauer spectroscopy showed that chalcogen-enriched Ge{sub 100-y}X{sub y} (X = S, Se, Te) glasses are constructed of structural units including two-coordinated chalcogen atoms in chains such as Ge-X-Ge- and Ge-X-X-Ge-. Germanium in these glasses is only tetravalent and four-coordinated, and only chalcogen atoms are in the local environment of germanium atoms. Chalcogen-depleted glasses are constructed of structural units including two-coordinated (in Ge-X-Ge- chains) and three-coordinated chalcogen atoms (in -Ge-X-Ge- chains). Germanium in these glasses stabilizes in both the tetravalent four-coordinated and divalent three-coordinated states, and only chalcogen atoms are in the local environment of germanium atoms.

  14. {Ge9[Si(SiMe3)2(SiPh3)]3}(-): Ligand Modification in Metalloid Germanium Cluster Chemistry.

    PubMed

    Kysliak, Oleksandr; Schrenk, Claudio; Schnepf, Andreas

    2015-07-20

    The influence of the stabilizing ligand on the physical and chemical properties of a metalloid cluster compound is important for nanotechnology as metalloid clusters are ideal model compounds for metal nanoparticles. Here we present the synthesis of a differently substituted metalloid {Ge9R3}(-) cluster: {Ge9[Si(SiMe3)2(SiPh3)]3}(-) 1, which is obtained in good yield by the reaction of K4Ge9 with ClSi(SiMe3)2(SiPh3). 1 is characterized via NMR and mass spectrometry, but crystallization is hindered. However, the reaction with HgCl2 gives the neutral compound HgGe18[Si(SiMe3)2(SiPh3)]6 2, which can be crystallized and structurally characterized. The presented results are a first step for the investigation of the ligand's influence on the properties of a metalloid germanium cluster compound.

  15. Syntheses, structures, and optical properties of the indium/germanium selenides Cs{sub 4}In{sub 8}GeSe{sub 16}, CsInSe{sub 2}, and CsInGeSe{sub 4}

    SciTech Connect

    Ward, Matthew D.; Pozzi, Eric A.; Van Duyne, Richard P.; Ibers, James A.

    2014-04-01

    The three solid-state indium/germanium selenides Cs{sub 4}In{sub 8}GeSe{sub 16}, CsInSe{sub 2}, and CsInGeSe{sub 4} have been synthesized at 1173 K. The structure of Cs{sub 4}In{sub 8}GeSe{sub 16} is a three-dimensional framework whereas those of CsInSe{sub 2} and CsInGeSe{sub 4} comprise sheets separated by Cs cations. Both Cs{sub 4}In{sub 8}GeSe{sub 16} and CsInGeSe{sub 4} display In/Ge disorder. From optical absorption measurements these compounds have band gaps of 2.20 and 2.32 eV, respectively. All three compounds are charge balanced. - Graphical abstract: Structure of Cs{sub 4}In{sub 8}GeSe{sub 16}. - Highlights: • The solid-state In/Ge selenides Cs{sub 4}In{sub 8}GeSe{sub 16}, CsInSe{sub 2}, and CsInGeSe{sub 4} have been synthesized. • Both Cs{sub 4}In{sub 8}GeSe{sub 16} and CsInGeSe{sub 4} display In/Ge disorder. • Cs{sub 4}In{sub 8}GeSe{sub 16} and CsInGeSe{sub 4} have band gaps of 2.20 eV and 2.32 eV, respectively.

  16. Photoluminescence Spectroscopy of Zinc Germanium Diphosphide (ZnGeP2)

    DTIC Science & Technology

    1993-09-13

    ZnGeP 2. Successful crystal growth has been accomplished using liquid metal solutions, Bridgman methods, metal-organic chemical vapor deposition...1974:685) The Bridgman , or gradient freeze, method creates crystals of the material of interest by forming a molten quantity of the material or its...off, making it a .0exagonal prism. Sample 24d was grown by the Bridgman method, and its c- axis was known to be normal to the hexagonal faces. Its

  17. Nanostructure and optoelectronic phenomena in germanium-transparent conductive oxide (Ge:TCO) composites

    NASA Astrophysics Data System (ADS)

    Shih, Grace Hwei-Pyng

    Nanostructured composites are attracting intense interest for electronic and optoelectronic device applications, specifically as active elements in thin film photovoltaic (PV) device architectures. These systems implement fundamentally different concepts of enhancing energy conversion efficiencies compared to those seen in current commercial devices. This is possible through considerable flexibility in the manipulation of device-relevant properties through control of the interplay between the nanostructure and the optoelectronic response. In the present work, inorganic nanocomposites of semiconductor Ge embedded in transparent conductive indium tin oxide (ITO) as well as Ge in zinc oxide (ZnO) were produced by a single step RF-magnetron sputter deposition process. It is shown that, by controlling the design of the nanocomposites as well as heat treatment conditions, decreases in the physical dimensions of Ge nanophase size provided an effective tuning of the optical absorption and charge transport properties. This effect of changes in the optical properties of nanophase semiconductors with respect to size is known as the quantum confinement effect. Variation in the embedding matrix material between ITO and ZnO with corresponding characterization of optoelectronic properties exhibit notable differences in the presence and evolution of an interfacial oxide within these composites. Further studies of interfacial structures were performed using depth-profiling XPS and Raman spectroscopy, while study of the corresponding electronic effects were performed using room temperature and temperature-dependent Hall Effect. Optical absorption was noted to shift to higher onset energies upon heat treatment with a decrease in the observed Ge domain size, indicating quantum confinement effects within these systems. This contrasts to previous investigations that have involved the introduction of nanoscale Ge into insulating, amorphous oxides. Comparison of these different matrix

  18. Experimental study of the complexation of silicon and germanium with aqueous organic species: Implications for germanium and silicon transport and Ge/Si ratio in natural waters

    SciTech Connect

    Pokrovski, G.S.; Schott, J.

    1998-11-01

    The stability of aqueous complexes formed by Si and Ge with carboxylic acids (acetic, salicyclic, oxalic, citric, tartaric) and phenols (phenol and catechol) has been investigated from 25 to 90 C via solubility and potentiometric measurements. Results show that Ge forms stable complexes with the di- and tricarboxylic acids and catechol, but that Si forms much weaker complexes with these ligands. Analysis of results and of available literature data on Ge complexes formed with other types of aqueous organic species demonstrates that Ge forms complexes of chelate type with the following functional groups: (1) carboxylic in acid solutions (1 {le} pH {le} 6), (2) di-phenolic hydroxyls in neutral and basic solutions (pH {ge} 6), and (3) alcoholic hydroxyls in very basic solutions (pH {ge} 10). Conversely, Si forms very weak complexes with these compounds. Stability constants generated in this study for Ge- and Si-organic species have been used to approximate Ge and Si complexing with humic acids which possess the same organic functional groups as those used in this study. Calculations show that Si-humic acid complexes are negligible in most natural waters. In contrast, the presence of humic acids can considerably affect Ge speciation in aqueous solution. For example, at pH {ge} 6 in a solution containing 0.1 {micro}g/L of Ge and 20 mg/L of dissolved organic carbon (DOC), Ge-humic acid complexes account for more than 95% of total aqueous Ge. These results can explain the increase of the Ge/Si ratio in organic-rich surficial waters Ge-organic matter complexation should be thus taken into account when using Ge/Si ratios measured in surface waters and biogenic opals to estimate chemical-weathering intensity and Ge and Si global fluxes.

  19. Germanium monochloride (GeCl). Spectroscopic constants and potential energy curves

    NASA Astrophysics Data System (ADS)

    Liao, Dai-Wei; Balasubramanian, K.

    1993-10-01

    The electronic states, potential energy curves and spectroscopic properties of the GeCl radical were calculated by means of the relativistic ab initio complete active space multiconfiguration self-consistent field (CASSCF) followed by first- and second-order configuration interaction (FOCI, SOCI) methods which included up to a million configurations. Our computed spectroscopic constants are in good agreement with the experiment for the observed states. Spectroscopic constants and potential energy curves of several other electronic states are computed which are yet to be observed. We also show that a previous rotational analysis of the B—X system is incorrect.

  20. Continued development of doped-germanium photoconductors for astronomical observations at wavelengths from 30 to 120 micrometers

    NASA Technical Reports Server (NTRS)

    Bratt, P. R.; Lewis, N. N.; Long, L. E.

    1978-01-01

    The development of doped-germanium detectors which have optimized performance in the 30- to 120-mu m wavelength range and are capable of achieving the objectives of the infrared astronomical satellite (IRAS) space mission is discussed. Topics covered include the growth and evaluation of Ge:Ga and Ge:Be crystals, procedures for the fabrication and testing of detectors, irradiance calculations, detector responsivity, and resistance measurements through MOSFET. Test data are presented in graphs and charts.

  1. Vapor pressure of germanium precursors

    NASA Astrophysics Data System (ADS)

    Pangrác, J.; Fulem, M.; Hulicius, E.; Melichar, K.; Šimeček, T.; Růžička, K.; Morávek, P.; Růžička, V.; Rushworth, S. A.

    2008-11-01

    The vapor pressure of two germanium precursors tetrakis(methoxy)germanium (Ge(OCH 3) 4, CASRN 992-91-6) and tetrakis(ethoxy)germanium (Ge(OC 2H 5) 4, CASRN 14165-55-0) was determined using a static method in the temperature range 259-303 K. The experimental vapor pressure data were fit with the Antoine equation. The mass spectra before and after degassing by vacuum distillation at low temperature are also reported and discussed.

  2. Characteristics of signals originating near the lithium-diffused N+ contact of high purity germanium p-type point contact detectors

    DOE PAGES

    Aguayo, E.; Amman, M.; Avignone, F. T.; ...

    2012-11-09

    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. Furthermore, experiments that operate germanium detectors with a verymore » low energy threshold may benefit from the methods presented herein.« less

  3. Characteristics of signals originating near the lithium-diffused N+ contact of high purity germanium p-type point contact detectors

    SciTech Connect

    Aguayo, E.; Amman, M.; 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.

    2012-11-09

    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. Furthermore, experiments that operate germanium detectors with a very low energy threshold may benefit from the methods presented herein.

  4. Mitigation of Charge Sharing and Cross-Talk in a Planar Germanium Double-Sided Strip Detector

    NASA Astrophysics Data System (ADS)

    Larson, N.; Liddick, S. N.; Crider, B. P.; Kondev, F. G.; Kumar, S.; Paulauskas, S. V.; Prokop, C. J.; Suchyta, S.

    2014-09-01

    Fragmentation facilities provide access to a wide range of beta-decaying nuclei for experimental study. However, the higher the atomic number of species of interest the greater the chance that the ion will not be fully stripped of its atomic electrons. The delivery of multiple charge states, predominately fully stripped and H-like, to the experimental system typically leads to overlaps in standard DE-TOF identification plots. A standard method for resolving multiple charge states is a measurement of the ion's total kinetic energy. A recently commissioned planar Ge double-sided strip detector (GeDSSD) is being used at the NSCL for beta-decay spectroscopy studies. The capability of the GeDSSD to measure total kinetic energies and resolve charge state contamination in a cocktail of radioactive ions is being investigated which requires addressing the dual problems of charge sharing between neighboring strips within the detector and electronic cross talk. Preliminary results will be presented.

  5. Progress report on the search for cold dark matter using ultralow-background germanium detectors at homestake

    NASA Astrophysics Data System (ADS)

    Drukier, A. K.; Avignone, F. T.; Brodzinski, R. L.; Collar, J. I.; Gelmini, G.; Miley, H. S.; Morales, A.; Reeves, J. H.; Spergel, D.

    1992-07-01

    Counting rates from the two 1-kg PNL/USC ultralow-background germanium detectors are ≤0.3 counts keV -1 kg -1 d -1 between 6 and 9 keV and ˜ 2 counts keV -1 kg -1 d -1 between 4 and 6 keV. These data show a significant short-time rate dependence due to blasting and other mining operations in the Homestake good mine. The mean shift in the centroid of the gallium x-ray peak was about 50 eV over a total period of about 500 days, indicating adequate stability for a search for annual modulation of Cold Dark Matter (CDM) particles.

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

    PubMed

    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.

  7. Study of inactive layer uniformity and charge collection efficiency of a p-type point-contact germanium detector.

    PubMed

    Ma, J L; Yue, Q; Wang, Q; Li, J; Wong, H T; Lin, S T; Liu, S K; Wang, L; Jiang, H; Yang, L T; Jia, L P; Chen, J H; Zhao, W

    2017-09-01

    The characteristics of the surface inactive layer of a 1-kg-mass p-type point-contact germanium detector were studied. The thickness of the inactive layer and its uniformity on the top and lateral surfaces were measured. A charge collection efficiency function was developed according to the Monte Carlo simulation to describe the charge collection capacity along the depth within this inactive layer. In the energy range below 18keV, the surface, bulk, and total spectra of (57)Co, (133)Ba, (137)Cs, and (60)Co from simulations based on the charge collection efficiency function were well consistent with those from experiments. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. The use of a high-purity germanium detector for routine measurements of {sup 125}I in radiation workers

    SciTech Connect

    Kopp, P.; Bergmann, H.; Havlik, E.; Aiginger, H.; Unfried, E.; Riedlmayer, L.

    1994-12-01

    A high-purity germanium detector was calibrated for the assessment of {sup 125}I uptake in the thyroid gland of radiation workers. A cylindrical water phantom (perspex walls) with high flexibility for position and size of the thyroid was constructed. Within a massive shielding chamber built for a whole-body counter, an activity of 2.2 Bq was detectable (MDA). This is well below the very restrictive limiting value of 20 Bq for inhalation specified by Austrian law. An activity of 128 Bq was measured with a statistical uncertainty of 5% in a counting period of 10 min. Various parameters influencing the result are investigated as well as the performance of two other measurement geometries outside the shielding chamber. 13 refs., 4 figs., 2 tabs.

  9. Compact Two-Dimensional Array of Stressed GE:GA Detectors

    NASA Astrophysics Data System (ADS)

    Doi, Y.; Makiuti, S.; Okuda, H.; Nakagawa, T.; Shibai, H.; Kawada, M.; Hiromoto, N.; Fujiwara, M.; Okumura, K.

    2000-08-01

    We have developed a 4 × 8 array of stressed Ge:Ga detectors. This array detector has a high density format of entrance pupils so that we can minimize the size of the camera optics. The cutoff wavelength of the detector is about 170 μm, and the detector's NEP is better than 10^16 W Hz^-1/2. We are going apply this array detector to balloon-borne astronomical observations. Furthermore, we are developing this detector into a 5 × 15 array detector that will be placed onboard the IRIS satellite to be launched in 2003.

  10. An automatic liquid-nitrogen filling system for multiple Ge detectors

    SciTech Connect

    Koizumi, Mitsuo; Oshima, Masumi; Toh, Yosuke; Kimura, Atsushi; Kin, Tadahiro; Furutaka, Kazuyoshi; Murakami, Yukihiro; Osa, Akihiko; Ando, Shingo

    2009-01-15

    In order to reduce the time and effort of the daily task of refilling Dewar vessels of Ge detectors with liquid nitrogen (LN{sub 2}), we have developed an automatic LN{sub 2} filling system equipped with a LN{sub 2} plant. With this system, we were freed from the work of LN{sub 2} filling. Such an LN{sub 2} filling system is useful for moderate-scale Ge detector arrays consisting of fewer than 20 Ge detectors.

  11. Measurement of the cross sections for the production of the isotopes 74As, 68Ge, 65Zn, and 60Co from natural and enriched germanium irradiated with 100-MeV protons

    NASA Astrophysics Data System (ADS)

    Barabanov, I. R.; Bezrukov, L. B.; Gurentsov, V. I.; Zhuykov, B. L.; Kianovsky, S. V.; Kornoukhov, V. N.; Kohanuk, V. M.; Yanovich, E. A.

    2010-07-01

    The cross sections for the production of the radioactive isotopes 74As, 68Ge, 65Zn, and 60Co in metallic germanium irradiated with 100-MeV protons were measured, the experiments being performed both with germanium of natural isotopic composition and germanium enriched in the isotope 76Ge. The targets were irradiated with a proton beam at the facility for the production of radionuclides at the accelerator of the Institute for Nuclear Research (INR, Moscow). The data obtained will further be used to calculate the background of radioactive isotopes formed by nuclear cascades of cosmic-ray muons in new-generation experiments devoted to searches for the neutrinoless double-beta decay of 76Ge at underground laboratories.

  12. Measurement of the cross sections for the production of the isotopes {sup 74}As, {sup 68}Ge, {sup 65}Zn, and {sup 60}Co from natural and enriched germanium irradiated with 100-MeV protons

    SciTech Connect

    Barabanov, I. R.; Bezrukov, L. B.; Gurentsov, V. I.; Zhuykov, B. L.; Kianovsky, S. V.; Kornoukhov, V. N.; Kohanuk, V. M.; Yanovich, E. A.

    2010-07-15

    The cross sections for the production of the radioactive isotopes {sup 74}As, {sup 68}Ge, {sup 65}Zn, and {sup 60}Co in metallic germanium irradiated with 100-MeV protons were measured, the experiments being performed both with germanium of natural isotopic composition and germanium enriched in the isotope {sup 76}Ge. The targets were irradiated with a proton beam at the facility for the production of radionuclides at the accelerator of the Institute for Nuclear Research (INR, Moscow). The data obtained will further be used to calculate the background of radioactive isotopes formed by nuclear cascades of cosmic-ray muons in new-generation experiments devoted to searches for the neutrinoless double-beta decay of {sup 76}Ge at underground laboratories.

  13. Dermal absorption of inorganic germanium in rats.

    PubMed

    Yokoi, Katsuhiko; Kawaai, Takae; Konomi, Aki; Uchida, Yuka

    2008-11-01

    So-called germanium 'health' products including dietary supplements, cosmetics, accessories, and warm bath service containing germanium compounds and metalloid are popular in Japan. Subchronic and chronic oral exposure of germanium dioxide (GeO(2)), popular chemical form of inorganic germanium causes severe germanium toxicosis including death and kidney dysfunction in humans and experimental animals. Intestinal absorption of neutralized GeO(2) or germanate is almost complete in humans and animals. However, it is not known whether germanium is cutaneously absorbed. We tested dermal absorption of neutralized GeO(2) or germanate using male F344/N rats. Three groups of rats were treated with a 3-h topical application of hydrophilic ointment containing graded level of neutralized GeO(2) (pH 7.4): 0, 0.21 and 0.42 mg GeO(2)/g. Germanium concentration in blood and tissues sampled from rats after topical application of inorganic germanium was measured by inductively coupled plasma-mass spectrometry. Animals topically applied 0.42 mg GeO(2)/g ointment had significantly higher germanium concentrations in plasma, liver, and kidney than those of rats that received no topical germanium. The results indicate that skin is permeable to inorganic germanium ion or germanate and recurrent exposure of germanium compounds may pose a potential health hazard.

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

    NASA Astrophysics Data System (ADS)

    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.

  15. Pulse-height defect due to electron interaction in dead layers of Ge/Li/ gamma-ray detectors

    NASA Technical Reports Server (NTRS)

    Larsen, R. N.; Strauss, M. G.

    1969-01-01

    Study shows the pulse-height degradation of gamma ray spectra in germanium/lithium detectors to be due to electron interaction in the dead layers that exist in all semiconductor detectors. A pulse shape discrimination technique identifies and eliminates these defective pulses.

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

    DTIC Science & Technology

    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

  17. P-Type Point Contact Germanium Detectors for Low-Level Counting

    DTIC Science & Technology

    2008-09-01

    same detector arrays can perform important fundamental physics measurements, including the search for rare-events like neutrino -less double-beta...same detector arrays can also perform important fundamental physics measurements, including the search for rare events like neutrino -less double...fabrication of other detectors having different aspect ratios compare co Barbeau nd ations in neutrino and astroparticle physics. Journal of

  18. The effects of exogenous antioxidant germanium (Ge) on seed germination and growth of Lycium ruthenicum Murr subjected to NaCl stress.

    PubMed

    Liu, Yan; Hou, Long-yu; Li, Qing-mei; Jiang, Ze-ping; Liu, Duo; Zhu, Yan

    2016-01-01

    In this paper, we present the results of a study on the effects of exogenous antioxidant germanium (Ge) on seed germination and seedling growth, and its role as a radical scavenger that regulates related enzymes, including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), under salt stress. Seeds were incubated in 0, 50, 100, 150, 200, 250 and 300 mM NaCl to determine the salt tolerance of the Lycium ruthenicum Murr seedlings and from the results, the critical and ultimate salt concentrations were chosen for the next experiment. Subsequently, two treatments (seeds soaked in Ge and Ge added to salt) with four concentrations of GeO2 (0, 5, 10 and 20 μM) were used with the critical (150 mM) and ultimate salt concentrations (250 mM). The results demonstrated that salt alone inhibited seed germination significantly (≥150 mM) and reduced seedling growth (≥200 mM). The addition of exogenous Ge to the salt solution, as well as soaking the seeds in Ge, attenuated the salt stress effects in a manner dependent on the dose of Ge, as indicated by the increased percentage of seeds that germinated and improved seedling growth. The addition of Ge also showed a significant reversal of salt stress on the activities of antioxidant enzymes, with a decrease in SOD and POD activity, but an increase in CAT activity with 150 mM NaCl, and enhancement of SOD, POD and CAT with 250 mM NaCl. Correspondingly, the level of malondialdehyde was decreased significantly by each Ge treatment under salt stress. Further, for L. ruthenicum, adding 10 Ge and seeds soaked in 5 Ge were the most effective treatments. To our knowledge, this is the first report to show the protective effects of exogenous Ge against salt-induced oxidative damage in L. ruthenicum seed germination and seedling growth. Thus, L. ruthenicum can be used in areas with salty soil and Ge can promote the plants' salt tolerance.

  19. The Reactivity of Germanium Phosphanides with Chalcogens.

    PubMed

    Harris, Lisa M; Tam, Eric C Y; Cummins, Struan J W; Coles, Martyn P; Fulton, J Robin

    2017-03-06

    The reactivity of germanium phosphanido complexes with elemental chalcogens is reported. Addition of sulfur to [(BDI)GePCy2] (BDI = CH{(CH3)CN-2,6-iPr2C6H3}2) results in oxidation at germanium to form germanium(IV) sulfide [(BDI)Ge(S)PCy2] and oxidation at both germanium and phosphorus to form germanium(IV) sulfide dicylohexylphosphinodithioate complex [(BDI)Ge(S)SP(S)Cy2], whereas addition of tellurium to [(BDI)GePCy2] only gives the chalcogen inserted product, [(BDI)GeTePCy2]. This reactivity is different from that observed between [(BDI)GePCy2] and selenium. Addition of selenium to the diphenylphosphanido germanium complex, [(BDI)GePPh2], results in insertion of selenium into the Ge-P bond to form [(BDI)GeSePCy2] as well as the oxidation at phosphorus to give [(BDI)GeSeP(Se)Ph2]. In contrast, addition of selenium to the bis(trimethylsilyl)phosphanido germanium complex, [(BDI)GeP(SiMe3)2], yields the germanium(IV) selenide [(BDI)Ge(Se)P(SiMe3)2].

  20. [Effects of Germanium Concentrations on Germanium Accumulation and Biotransformation of Polysaccarified Germanium in Cordyceps militaris].

    PubMed

    Wang, Ju-feng; Li, Hu-ming; Yang, Dao-de

    2015-11-01

    To study the effects of Germanium (Ge) concentration on Ge accumulation and biotransformation of polysaccarified Ge (PG) in Cordyceps militaris. Solid and liquid culture were used in this study. In the solid culture conditions, when the Ge concentration of medium was 200 mg/L, the sporophore biomass of Cordyceps militaris was the maximum; and when Ge concentration was 300 mg/L,the amount of biotransformation of PG in sporophore was the highest; and when the Ge concentration is 250 mg/L, conversion rate of organic germanium (OG) in sporophore reached the highest value. In the liquid culture conditions, when the Ge concentration was 250 mg/L, the mycelium biomass of Cordyceps militaris was the maximum; and when Ge concentration was 150 mg/L, the amount of organic conversion of PG in mycelium was the most; and conversion rate of OG in mycelium was the highest in media with the Ge concentration of 200 mg/L. This study showed the germanium concentrations in 150 - 300 mg/L was more suitable for Ge accumulation and biotransformation of PG in Cordyceps militaris. In general, the biotransformation capacity to germanium of sporophore was stronger than that of mycelium of Cordyceps militaris. Germanium can significantly affect Ge accumulation and biotransformation of PG in Cordyceps militaris (P < 0.05) at different concentration. This result has practical value for Ge enriched cultivation of fruiting body in Cordyceps militaris.

  1. STARS/LiBerACE: Segmented silicon and high-purity germanium detector arrays for low-energy nuclear reaction and structure studies

    NASA Astrophysics Data System (ADS)

    Lesher, S. R.; Phair, L.; Bernstein, L. A.; Bleuel, D. L.; Burke, J. T.; Church, J. A.; Fallon, P.; Gibelin, J.; Scielzo, N. D.; Wiedeking, M.

    2010-09-01

    The Silicon Telescope Array for Reaction Studies (STARS) consists of large-area annular double-sided silicon detectors for charged-particle identification. The Livermore Berkeley Array for Collaborative Experiments (LiBerACE) is an array of six Compton-suppressed high-purity germanium Clover detectors for efficient detection of γ-rays. These detector arrays are versatile tools for studies of neutron-induced reaction cross-sections, fission, light neutron-rich nuclei, and other low-energy nuclear physics topics through transfer, fusion, incomplete-fusion, and inelastic-scattering reactions. The STARS and LiBerACE arrays and typical experimental configurations are described in detail.

  2. Segmented Ge detectors and mechanical coolers for future gamma-ray astronomy instruments

    NASA Technical Reports Server (NTRS)

    Varnell, Larry S.

    1990-01-01

    The effectiveness of a segmented Ge detector in rejecting background events due to the beta decay of internal radioactivity is demonstrated by a laboratory experiment in which radioactivity was produced in the detector by neutron irradiation. A Cf-252 source of neutrons was used to produce, by neutron capture on Ge-74 in the detector itself, Ge-75, which decays by beta emission with a maximum energy of 1188 keV. Simultaneous spectra are taken of the activity in the detector under two conditions: a free spectrum in which all events in the detector are accumulated, and a gated spectrum in which events are accumulated only if they deposit energy in two or more segments. A comparison of the spectra shows that over 85 percent of the beta events are rejected, which is in good agreement with predictions.

  3. Germanium-76 Sample Analysis: Revision 3

    SciTech Connect

    Kouzes, Richard T.; Zhu, Zihua; Engelhard, Mark H.

    2011-09-19

    The MAJORANA DEMONSTRATOR is a large array of ultra-low background high-purity germanium detectors, enriched in 76Ge, designed to search for zero-neutrino double-beta decay (0{nu}{beta}{beta}). The DEMONSTRATOR will utilize 76Ge from Russia. The first one-gram sample was received from the supplier for analysis on April 24, 2011. The second one-gram sample was received from the supplier for analysis on July 12, 2011. The third sample, which came from the first large shipment of germanium from the vendor, was received from Oak Ridge National Laboratory (ORNL) on September 13, 2011. The Environmental Molecular Sciences facility, a DOE user facility at PNNL, was used to make the required isotopic and chemical purity measurements that are essential to the quality assurance for the MAJORANA DEMONSTRATOR. The results of these analyses are reported here. The isotopic composition of a sample of natural germanium was also measured twice. Differences in the result between these two measurements led to a re-measurement of the second 76Ge sample.

  4. Mineral commodity profiles: Germanium

    USGS Publications Warehouse

    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.

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

    DTIC Science & Technology

    2005-06-01

    gamma emitting source. By replacing the converging hole collimator with a second detector array (as in a Compton camera ) to improve detector...88 Input Logic Module Performance ..............................................................................89 Digital Gamma Finder...efficiency of the system. This problem should be overcome by the addition of an input logic module that will maintain consistent timing information

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

    SciTech Connect

    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.

  7. Simulation of CdTe:Ge crystal properties for nuclear radiation detectors

    NASA Astrophysics Data System (ADS)

    Sochinskii, N. V.; Lozano, M.; Pellegrini, G.; Ullan, M.

    2006-11-01

    We report on the simulation results of the electrical properties of a coplanar detector made from Ge-doped CdTe crystals. The simulations have been performed using the commercial modeling package MEDICI. The detailed models of material behavior have been created by varying the concentration of three standard traps associated with CdTe:Ge crystals. These traps are the A-center related to Cd vacancy-residual impurity complex, the Te vacancy defect and the Ge impurity. Their energetic positions were measured by photoluminescence technique. The simulation has revealed the effects of the traps on several important detector characteristics such as leakage current and electric field distribution.

  8. Application of response functions to make efficient Monte Carlo simulations of germanium detectors.

    PubMed

    Sima, Octavian

    2010-01-01

    A new Monte Carlo procedure to compute the efficiency and the coincidence summing corrections for closed end HPGe detectors was developed. In this procedure detector specific response functions that give the probability of getting a signal in the peak or in the total spectrum for photons incident on the end cap of the detector are used. The procedure is time efficient in the case of large scale computations because part of the simulation is circumvented by the use of pre-computed response functions. Copyright 2010 Elsevier Ltd. All rights reserved.

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

    SciTech Connect

    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.

  10. Improving axion detection sensitivity in high purity germanium detector based experiments

    NASA Astrophysics Data System (ADS)

    Xu, Wenqin; Elliott, Steven

    2015-04-01

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

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

    SciTech Connect

    Alnour, I. A. E-mail: ibrahim.elnour@yahoo.com; Wagiran, H.; Ibrahim, N.; Hamzah, S.; Elias, M. S.; Siong, W. B.

    2016-01-22

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

  12. Measurement of an upper limit of fission energy release in HOLOG using a germanium gamma ray detector

    SciTech Connect

    Wang, T.F.

    1998-01-01

    An upper limit of less than 4 mg TNT equivalent fission energy release from the HOLOG experiment was determined using a germanium {gamma}-ray detector to measure the ratio of selected fission-product and plutonium {gamma} rays. Only three hours of {gamma}-ray data collected immediately after the zero-time were analyzed to calculate the above limit. We found no peaks corresponding to the {sup 97} Zr - {sup 97} Nb fission product pair at the gamma-ray energies of E{sub {gamma}} = 743 keV and E{sub {gamma}} = 658 keV, respectively. No information on the plutonium isotopic ratios is revealed because {gamma}-ray peaks in the energy region below 100 keV are not observed due to the high absorption in the containment barrier. The measurement is relatively easy to perform and is not subject to false-positive results because specific fission product and plutonium {gamma} ray energies need to be detected.

  13. Cosmogenically-produced isotopes in natural and enriched high-purity germanium detectors for the MAJORANA DEMONSTRATOR

    NASA Astrophysics Data System (ADS)

    Gilliss, Thomas; MAJORANA DEMONSTRATOR Collaboration

    2017-01-01

    The MAJORANA DEMONSTRATOR advances toward measurements of the neutrinoless double-beta decay of 76Ge. Detectors employed in the DEMONSTRATOR are subject to cosmogenic spallation during production and processing, resulting in activation of certain long-lived radioisotopes. Activation of these cosmogenic isotopes is mitigated by shielded storage of detectors and through underground operation of the DEMONSTRATOR at the 4850 ft level of the Sanford Underground Research Facility. In this work, we explore the appearance and reduction of cosmogenic contributions to the DEMONSTRATOR background spectrum. This work is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, the Particle Astrophysics and Nuclear Physics Programs of the National Science Foundation, and the Sanford Underground Research Facility.

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

    SciTech Connect

    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.

  15. {Ge9[Si(SiMe3)3]2}(2-): a starting point for mixed substituted metalloid germanium clusters.

    PubMed

    Kysliak, O; Schnepf, A

    2016-02-14

    Deeper investigations on the silylation reaction of the Ge9(4-) Zintl anion are provided. The reaction of K4Ge9 with two equivalents of ClHyp (Hyp = Si(SiMe3)3) gives the metalloid cluster compound [Ge9(Hyp)2](2-). Subsequent reactions with this compound give access to the first mixed trisubstituted metalloid cluster [Ge9(Hyp)2(Hyp(Ph3))](-) (Hyp(Ph3) = Si(SiMe3)2(SiPh3)), opening a way to a variety of mixed substituted Ge9 clusters for future investigations.

  16. Early diagenesis of germanium in sediments of the Antarctic South Atlantic: In search of the missing Ge sink

    SciTech Connect

    King, S.L.; Froelich, P.N.; Jahnke, R.A.

    2000-04-01

    Pore water and solid-phase geochemistry profiles were obtained from several cores between 41{degree}S and 53{degree}S in the Atlantic sector of the Southern Ocean. Pore water nitrate, manganese, and iron profiles delineate standard redox zones in these sediments, and help characterize those with classic vs. burn-down behaviors. Pore water Si and Ge profiles demonstrate that Ge released during opal dissolution is removed pervasively throughout the uppermost interval of silicate release, and also downwards into the suboxic zone by as yet unidentified precipitation mechanisms. These results indicate that early diagenesis of Ge is uncoupled from that of opal. Solid-phase extractions (Fe, Mn, U, Mo, Ge, Cu, Ni, Co, V, and Cd) in a few cores suggest that anthigenic Ge removal in the suboxic zone is not associated with peaks in authigenic Mn cycling (MnO{sub 2} and related metals) but rather with processes deeper in the sediments, perhaps Fe or U diagenesis. Below the interval of Ge removal, pre water Ge increases linearly with depth by over two orders of magnitude, indicating a deep (below recovery) source of large magnitude. The fraction of opal-derived Ge precipitated authigenically in these sediments ranges from {approximately}1 to 96% and correlates strongly with the detrital fraction as well as the detrital to opal ratio, both of which generally decrease from north to south. The Ge sink observed in these sediments would need to be globally representative to account for the entire missing Ge sink in today's oceanic Ge balance, which seems unlikely. Benthic fluxes of Ge and Si estimated from these pore water profiles and from measurements in three benthic flux chamber experiments at high carbon-rain continental margin sites demonstrate that the Ge/Si rate released from the seafloor in locations with high benthic silicate and carbon fluxes is congruent with Holocene opal dissolution (Ge/Si {approximately} 0.7 x 10{sup {minus}6}). In contrast, Ge/Si flux ratios in areas

  17. Germanium isotope fractionation during Ge adsorption on goethite and its coprecipitation with Fe oxy(hydr)oxides

    NASA Astrophysics Data System (ADS)

    Pokrovsky, Oleg S.; Galy, Albert; Schott, Jacques; Pokrovski, Gleb S.; Mantoura, Samia

    2014-04-01

    Isotopic fractionation of Ge was studied during Ge adsorption on goethite and its coprecipitation with amorphous Fe oxy(hydr)oxides. Regardless of the pH, surface concentration of adsorbed Ge or exposure time, the solution-solid enrichment factor for adsorption (Δ74/70Gesolution-solid) was 1.7 ± 0.1‰. The value of the Δ74Gesolution-solid in Fe-Ge coprecipitates having molar ratio 0.1 < (Ge/Fe)solid < 0.5 remained constant at 2.0 ± 0.4‰. For (Ge/Fe)solid ratio < 0.1, the Δ74Gesolution-solid increased with the decrease of Ge concentration in the solid phase, with the value as high as 4.4 ± 0.2‰ at (Ge/Fe)solid < 0.001, corresponding to the majority of natural settings. These results can be interpreted based on available structural data for adsorbed and coprecipitated Ge. It follows that Ge(OH)4° adsorption occurring as bidentate binuclear complexes at the goethite surface is characterised by an enrichment factor of ∼1.7‰, likely related to the distortion of the GeO4 tetrahedron and the formation of Ge-O-Fe bonds at the goethite surface as compared to aqueous solution. In contrast, coprecipitation yields more distorted edge-sharing GeO4 tetrahedra and, in the case of the most diluted samples, part of the Ge is found in coordination 6, replacing Fe(III) in octahedral positions. This produces a greater enrichment of the solid phase in lighter isotopes, mostly due to the increase in Ge-O bond distances and coordination number compared to aqueous solution, which is in line with the basic principles of isotope fractionation. Discharge of hydrothermal fluids, leading to massive Fe(OH)3 precipitation in the vicinity of the springs should, therefore, represent an isotopically-heavy source of dissolved Ge to the ocean. Similarly, groundwater discharge and Fe(OH)3 precipitation at the Earth’s surface, Fe oxy(hydr)oxide formation in soils and riverine organo-ferric colloids coagulation, leading to iron hydroxide precipitation in estuaries, should produce an

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

    DTIC Science & Technology

    2007-09-01

    produced Stirling -cycle mechanical coolers provide the basis for this evolution. When properly instrumented, these systems can cool the very largest...as 50 K. The system is free of microphonic noise with the cooler operating at full power. The lower detector operating temperature, coupled with...570 cm3, ~ 3 kg, ~ 140 %, or larger) for field use in rugged conditions. A new generation of Stirling -cycle mechanical cooler is being used to reliably

  19. Advanced far infrared detector and double donor studies in Ge

    SciTech Connect

    Olsen, Christopher Sean

    1994-12-01

    This has application to astronomy and astrophysics. Selenium in Ge has been studied with a doping technique which limits complex formation. Only one ionization level has been found to correspond to selenium, which presumably occupies a substitutional site. This level is extremely unstable and its concentration decreases after annealing at 400C. Future work is planned to anneal the fast neutron damage before much selenium has formed in the {sup 74/76}Ge samples. It is expected that the observed selenium level can be better characterized and the missing selenium level is more likely to be discovered if other defects are removed before {sup 77}Se formation.

  20. Voltage-Assisted Calorimetric Detection of Gamma Interactions in a Prototype Cryogenic Ge Detector of the EDELWEISS Collaboration for Dark Matter Search

    NASA Astrophysics Data System (ADS)

    Broniatowski, A.; Piro, M.-C.; Marnieros, S.; Bergé, L.; Dumoulin, L.; Chapellier, M.

    2016-07-01

    As a part of an R&D program to improve the sensitivity of its detectors to low-mass (<10 GeV) weakly interacting massive particles, the Edelweiss dark matter collaboration is developing cryogenic ionization-and-heat coplanar grid germanium detectors, operated in a high-bias mode where advantage is taken of the voltage-assisted amplification of the ionization signals for enhanced sensitivity to low-energy (detector, capable of sustaining collection voltages up to 180 V with a corresponding gain of 60 in the heat measurement channel for electron recoil interactions. Event populations are analyzed based on ionization and heat data and on computer modeling of the detector signals, and a tentative interpretation of the results for the heat resolution is presented, involving athermal ballistic phonon losses in the device with consequent fluctuations in the thermometer response to the energy deposit of a particle.

  1. Epitaxial Deposition Of Germanium Doped With Gallium

    NASA Technical Reports Server (NTRS)

    Huffman, James E.

    1994-01-01

    Epitaxial layers of germanium doped with gallium made by chemical vapor deposition. Method involves combination of techniques and materials used in chemical vapor deposition with GeH4 or GeCl4 as source of germanium and GaCl3 as source of gallium. Resulting epitaxial layers of germanium doped with gallium expected to be highly pure, with high crystalline quality. High-quality material useful in infrared sensors.

  2. Epitaxial Deposition Of Germanium Doped With Gallium

    NASA Technical Reports Server (NTRS)

    Huffman, James E.

    1994-01-01

    Epitaxial layers of germanium doped with gallium made by chemical vapor deposition. Method involves combination of techniques and materials used in chemical vapor deposition with GeH4 or GeCl4 as source of germanium and GaCl3 as source of gallium. Resulting epitaxial layers of germanium doped with gallium expected to be highly pure, with high crystalline quality. High-quality material useful in infrared sensors.

  3. Radiation Effects on Stressed Ge:Ga Array Detector of Far-Infrared Surveyor on AKARI

    NASA Astrophysics Data System (ADS)

    Suzuki, Toyoaki; Kaneda, Hidehiro; Matsuura, Shuji; Shirahata, Mai; Nakagawa, Takao; Doi, Yasuo; Onaka, Takashi; Hibi, Yasunori; Shibai Mitsunobu Kawada, Hiroshi

    2008-08-01

    AKARI, the Japanese infrared astronomical satellite, was launched on 2006 February 21 (UT) and put into a sun-synchronous polar orbit at an altitude of 700 km. Cosmic radiations, particularly protons in the South Atlantic Anomaly (SAA), were expected to affect the performance of the stressed Ge:Ga array far-infrared detector on board AKARI. One of the influences is the radioactivation of the detector housing; γ -rays from the radioactivated detector housing interact with Ge:Ga elements, producing spikes (so-called glitches) in the electric outputs of the detector. Prior to the launch, we performed a 100 MeV proton-beam irradiation test for an engineering model of the stressed Ge:Ga array, which simulated the SAA passage. In the test, we observed glitches in the detector output that were due to the radioactivation of the detector housing. By investigating the test data, we have computed the glitch rate of the flight array detector expected in the AKARI orbit, including its change with time from the launch to the end of the AKARI mission. After the launch of AKARI, we have compared the performance observed in the orbit to that predicted by the proton-beam test. The glitch rate really changed with time after the launch; we have found that the in-orbit behavior is consistent with the prediction.

  4. Germanium surface passivation and atomic layer deposition of high-k dielectrics—a tutorial review on Ge-based MOS capacitors

    NASA Astrophysics Data System (ADS)

    Xie, Qi; Deng, Shaoren; Schaekers, Marc; Lin, Dennis; Caymax, Matty; Delabie, Annelies; Qu, Xin-Ping; Jiang, Yu-Long; Deduytsche, Davy; Detavernier, Christophe

    2012-07-01

    Due to its high intrinsic mobility, germanium (Ge) is a promising candidate as a channel material (offering a mobility gain of approximately ×2 for electrons and ×4 for holes when compared to conventional Si channels). However, many issues still need to be addressed before Ge can be implemented in high-performance field-effect-transistor (FET) devices. One of the key issues is to provide a high-quality interfacial layer, which does not lead to substantial drive current degradation in both low equivalent oxide thickness and short channel regime. In recent years, a wide range of materials and processes have been investigated to obtain proper interfacial properties, including different methods for Ge surface passivation, various high-k dielectrics and metal gate materials and deposition methods, and different post-deposition annealing treatments. It is observed that each process step can significantly affect the overall metal-oxide-semiconductor (MOS)-FET device performance. In this review, we describe and compare combinations of the most commonly used Ge surface passivation methods (e.g. epi-Si passivation, surface oxidation and/or nitridation, and S-passivation) with various high-k dielectrics. In particular, plasma-based processes for surface passivation in combination with plasma-enhanced atomic layer deposition for high-k depositions are shown to result in high-quality MOS structures. To further improve properties, the gate stack can be annealed after deposition. The effects of annealing temperature and ambient on the electrical properties of the MOS structure are also discussed.

  5. Effect of SiO2 coating in bolometric Ge light detectors for rare event searches

    NASA Astrophysics Data System (ADS)

    Beeman, J. W.; Gentils, A.; Giuliani, A.; Mancuso, M.; Pessina, G.; Plantevin, O.; Rusconi, C.

    2013-05-01

    In germanium-based light detectors for scintillating bolometers, a SiO2 anti-reflective coating is often applied on the side of the germanium wafer exposed to light with the aim to improve its light collection efficiency. In this paper, we report about a measurement, performed in the temperature range 25-35 mK, of the light-collection increase obtained thanks to this method, which resulted to be of the order of 20%. The procedure followed has been carefully selected in order to minimize systematic effects. The employed light sources have the same spectral features (peaking at ˜630 nm wavelength) that will characterize future neutrinoless double beta decay experiments on the isotope 82Se and based on ZnSe crystals, such as LUCIFER. The coupling between source and light detector reproduces the configuration used in scintillating bolometers. The present measurement clarifies the role of SiO2 coating and describes a method and a set-up that can be extended to the study of other types of coatings and luminescent materials.

  6. Pulse-Shape Analysis of Ionization Signals in Cryogenic Ge Detectors for Dark Matter

    NASA Astrophysics Data System (ADS)

    Foerster, N.; Broniatowski, A.; Eitel, K.; Marnieros, S.; Paul, B.; Piro, M.-C.; Siebenborn, B.

    2016-08-01

    The detectors of the direct dark matter search experiment EDELWEISS consist of high-purity germanium crystals operated at cryogenic temperatures (mathrm {{<}20 mK}) and low electric fields (mathrm {{<}1 V/cm}). The surface discrimination is based on the simultaneous measurement of the charge amplitudes on different sets of electrodes. As the rise time of a charge signal strongly depends on the location of an interaction in the crystal, a time-resolved measurement can also be used to identify surface interactions. This contribution presents the results of a study of the discrimination power of the rise time parameter from a hot carrier transport simulation in combination with time-resolved measurements using an EDELWEISS-type detector in a test cryostat at ground level. We show the setup for the time-resolved ionization signal read-out in the EDELWEISS-III experiment and first results from data taking in the underground laboratory of Modane.

  7. The MAJORANA DEMONSTRATOR: A search for neutrinoless double-beta decay of germanium-76

    NASA Astrophysics Data System (ADS)

    Schubert, Alexis; Majorana Collaboration

    2011-04-01

    Observation of neutrinoless double-beta decay (0 νββ) could determine whether the neutrino is a Majorana particle and may provide information on neutrino mass. The MAJORANA Collaboration will search for 0 νββ of 76Ge in an array of germanium detectors enriched to 86% in 76Ge. Germanium detectors are a well-understood technology and have the benefits of excellent energy resolution, a high Q-value, and the ability to act as source and detector. The p-type point contact germanium detectors chosen by the MAJORANA Collaboration provide low noise, low energy threshold, and some ability to distinguish between the signal and background events. MAJORANA is constructing the DEMONSTRATOR, which will be used to conduct research and development toward a tonne-scale Ge experiment. The DEMONSTRATOR will be installed deep underground and will contain 40 kg of Ge deployed in an ultra-low-background shielded environment. Research supported by DOE under contracts DE-AC05-00OR22725 and DE-FG02-97ER41020.

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

    SciTech Connect

    Aalseth, C. E.; Ely, J.; Fast, J. E.; Fuller, E.; Hoppe, E. W.; Keillor, M.; Kouzes, R. T.; Miley, H. S.; Orrell, J. L.; Thompson, R.; Warner, R.; Amman, M.; Bergevin, M.; Chan, Y.-D.; Detwiler, J. A.; Fujikawa, B.; Loach, J. C.; Luke, P. N.; Poon, A. W. P; Prior, G.

    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 {sup 76}Ge. The DEMONSTRATOR can also perform a competitive direct dark matter search for light WIMPs in the 1-10 GeV/c{sup 2} 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.

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

    SciTech Connect

    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.

  10. Further studies on the evidence for a 17-keV neutrino in a {sup 14}C-doped germanium detector

    SciTech Connect

    Wietfeldt, F.E.; Norman, E.B.; Chan, Y.D.; da Cruz, M.T.F.; Garcia, A.; Haller, E.E.; Hansen, W.L.; Hindi, M.M.; Larimer, R.; Lesko, K.T.; Luke, P.N.; Stokstad, R.G.; Sur, B.; Zlimen, I. ||||||

    1995-08-01

    We have studied the beta spectrum of {sup 14}C using a unique {sup 14}C-doped germanium detector. In 1991 an initial report was made of a distortion in the spectrum that could be explained by the emission of a 17-keV neutrino in approximately 1% of the decays. Further tests have shown that the observed distortion was most likely caused by systematic effects related to the detector`s active guard ring. A new measurement with a smaller data sample shows no sign of this distortion. In addition, we find the {ital Q} value of {sup 14}C decay to be 155.95{plus_minus}0.07(stat.){plus_minus}0.21(sys.) keV, in disagreement with a previous precision measurement.

  11. Comparison of experimental pulse-height distributions in germanium detectors with integrated-tiger-series-code predictions

    SciTech Connect

    Beutler, D.E.; Halbleib, J.A. ); Knott, D.P. )

    1989-12-01

    This paper reports pulse-height distributions in two different types of Ge detectors measured for a variety of medium-energy x-ray bremsstrahlung spectra. These measurements have been compared to predictions using the integrated tiger series (ITS) Monte Carlo electron/photon transport code. In general, the authors find excellent agreement between experiments and predictions using no free parameters. These results demonstrate that the ITS codes can predict the combined bremsstrahlung production and energy deposition with good precision (within measurement uncertainties). The one region of disagreement observed occurs for low-energy (<50 keV) photons using low-energy bremsstrahlung spectra. In this case the ITS codes appear to underestimate the produced and/or absorbed radiation by almost an order of magnitude.

  12. Novel Si(1-x)Ge(x)/Si heterojunction internal photoemission long wavelength infrared detectors

    NASA Technical Reports Server (NTRS)

    Lin, T. L.; Maserjian, Joseph; Ksendzov, A.; Huberman, Mark L.; Terhune, R.; Krabach, T. N.

    1990-01-01

    There is a major need for long-wavelength-infrared (LWIR) detector arrays in the range of 8 to 16 microns which operate with close-cycle cryocoolers above 65 K. In addition, it would be very attractive to have Si-based infrared (IR) detectors that can be easily integrated with Si readout circuitry and have good pixel-to-pixel uniformity, which is critical for focal plane array (FPA) applications. Here, researchers report a novel Si(1-x)Ge(x)/Si heterojunction internal photoemission (HIP) detector approach with a tailorable long wavelength infrared cutoff wavelength, based on internal photoemission over the Si(1-x)Ge(x)/Si heterojunction. The HIP detectors were grown by molecular beam epitaxy (MBE), which allows one to optimize the device structure with precise control of doping profiles, layer thickness and composition. The feasibility of a novel Si(1-x)Ge(x)/Si HIP detector has been demonstrated with tailorable cutoff wavelength in the LWIR region. Photoresponse at wavelengths 2 to 10 microns are obtained with quantum efficiency (QE) above approx. 1 percent in these non-optimized device structures. It should be possible to significantly improve the QE of the HIP detectors by optimizing the thickness, composition, and doping concentration of the Si(1-x)Ge(x) layers and by configuring the detector for maximum absorption such as the use of a cavity structure. With optimization of the QE and by matching the barrier energy to the desired wavelength cutoff to minimize the thermionic current, researchers predict near background limited performance in the LWIR region with operating temperatures above 65K. Finally, with mature Si processing, the relatively simple device structure offers potential for low-cost producible arrays with excellent uniformity.

  13. Novel Si(1-x)Ge(x)/Si heterojunction internal photoemission long wavelength infrared detectors

    NASA Astrophysics Data System (ADS)

    Lin, T. L.; Maserjian, Joseph; Ksendzov, A.; Huberman, Mark L.; Terhune, R.; Krabach, T. N.

    1990-07-01

    There is a major need for long-wavelength-infrared (LWIR) detector arrays in the range of 8 to 16 microns which operate with close-cycle cryocoolers above 65 K. In addition, it would be very attractive to have Si-based infrared (IR) detectors that can be easily integrated with Si readout circuitry and have good pixel-to-pixel uniformity, which is critical for focal plane array (FPA) applications. Here, researchers report a novel Si(1-x)Ge(x)/Si heterojunction internal photoemission (HIP) detector approach with a tailorable long wavelength infrared cutoff wavelength, based on internal photoemission over the Si(1-x)Ge(x)/Si heterojunction. The HIP detectors were grown by molecular beam epitaxy (MBE), which allows one to optimize the device structure with precise control of doping profiles, layer thickness and composition. The feasibility of a novel Si(1-x)Ge(x)/Si HIP detector has been demonstrated with tailorable cutoff wavelength in the LWIR region. Photoresponse at wavelengths 2 to 10 microns are obtained with quantum efficiency (QE) above approx. 1 percent in these non-optimized device structures. It should be possible to significantly improve the QE of the HIP detectors by optimizing the thickness, composition, and doping concentration of the Si(1-x)Ge(x) layers and by configuring the detector for maximum absorption such as the use of a cavity structure. With optimization of the QE and by matching the barrier energy to the desired wavelength cutoff to minimize the thermionic current, researchers predict near background limited performance in the LWIR region with operating temperatures above 65K. Finally, with mature Si processing, the relatively simple device structure offers potential for low-cost producible arrays with excellent uniformity.

  14. Stressed and unstressed Ge:Ga detector arrays for airborne astronomy

    NASA Technical Reports Server (NTRS)

    Stacey, G. J.; Beeman, J. W.; Haller, E. E.; Geis, N.; Poglitsch, A.; Rumitz, M.

    1992-01-01

    The construction and operation of 2D arrays of both unstressed and stressed Ge:Ga photoconductive detectors for far-IR astronomy from the Kuiper Airborne Observatory is presented. The 25 element (5 x 5) arrays are designed for a new cryogenically cooled spectrometer. The 2D spatial array described has the advantage of absolute registry between pixels in a map.

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

    NASA Astrophysics Data System (ADS)

    Jackman, Kevin Richard

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

  16. Non-equilibrium induction of tin in germanium: towards direct bandgap Ge(1-x)Sn(x) nanowires.

    PubMed

    Biswas, Subhajit; Doherty, Jessica; Saladukha, Dzianis; Ramasse, Quentin; Majumdar, Dipanwita; Upmanyu, Moneesh; Singha, Achintya; Ochalski, Tomasz; Morris, Michael A; Holmes, Justin D

    2016-04-20

    The development of non-equilibrium group IV nanoscale alloys is critical to achieving new functionalities, such as the formation of a direct bandgap in a conventional indirect bandgap elemental semiconductor. Here, we describe the fabrication of uniform diameter, direct bandgap Ge(1-x)Sn(x) alloy nanowires, with a Sn incorporation up to 9.2 at.%, far in excess of the equilibrium solubility of Sn in bulk Ge, through a conventional catalytic bottom-up growth paradigm using noble metal and metal alloy catalysts. Metal alloy catalysts permitted a greater inclusion of Sn in Ge nanowires compared with conventional Au catalysts, when used during vapour-liquid-solid growth. The addition of an annealing step close to the Ge-Sn eutectic temperature (230 °C) during cool-down, further facilitated the excessive dissolution of Sn in the nanowires. Sn was distributed throughout the Ge nanowire lattice with no metallic Sn segregation or precipitation at the surface or within the bulk of the nanowires. The non-equilibrium incorporation of Sn into the Ge nanowires can be understood in terms of a kinetic trapping model for impurity incorporation at the triple-phase boundary during growth.

  17. Non-equilibrium induction of tin in germanium: towards direct bandgap Ge1-xSnx nanowires

    NASA Astrophysics Data System (ADS)

    Biswas, Subhajit; Doherty, Jessica; Saladukha, Dzianis; Ramasse, Quentin; Majumdar, Dipanwita; Upmanyu, Moneesh; Singha, Achintya; Ochalski, Tomasz; Morris, Michael A.; Holmes, Justin D.

    2016-04-01

    The development of non-equilibrium group IV nanoscale alloys is critical to achieving new functionalities, such as the formation of a direct bandgap in a conventional indirect bandgap elemental semiconductor. Here, we describe the fabrication of uniform diameter, direct bandgap Ge1-xSnx alloy nanowires, with a Sn incorporation up to 9.2 at.%, far in excess of the equilibrium solubility of Sn in bulk Ge, through a conventional catalytic bottom-up growth paradigm using noble metal and metal alloy catalysts. Metal alloy catalysts permitted a greater inclusion of Sn in Ge nanowires compared with conventional Au catalysts, when used during vapour-liquid-solid growth. The addition of an annealing step close to the Ge-Sn eutectic temperature (230 °C) during cool-down, further facilitated the excessive dissolution of Sn in the nanowires. Sn was distributed throughout the Ge nanowire lattice with no metallic Sn segregation or precipitation at the surface or within the bulk of the nanowires. The non-equilibrium incorporation of Sn into the Ge nanowires can be understood in terms of a kinetic trapping model for impurity incorporation at the triple-phase boundary during growth.

  18. Non-equilibrium induction of tin in germanium: towards direct bandgap Ge1−xSnx nanowires

    PubMed Central

    Biswas, Subhajit; Doherty, Jessica; Saladukha, Dzianis; Ramasse, Quentin; Majumdar, Dipanwita; Upmanyu, Moneesh; Singha, Achintya; Ochalski, Tomasz; Morris, Michael A.; Holmes, Justin D.

    2016-01-01

    The development of non-equilibrium group IV nanoscale alloys is critical to achieving new functionalities, such as the formation of a direct bandgap in a conventional indirect bandgap elemental semiconductor. Here, we describe the fabrication of uniform diameter, direct bandgap Ge1−xSnx alloy nanowires, with a Sn incorporation up to 9.2 at.%, far in excess of the equilibrium solubility of Sn in bulk Ge, through a conventional catalytic bottom-up growth paradigm using noble metal and metal alloy catalysts. Metal alloy catalysts permitted a greater inclusion of Sn in Ge nanowires compared with conventional Au catalysts, when used during vapour–liquid–solid growth. The addition of an annealing step close to the Ge-Sn eutectic temperature (230 °C) during cool-down, further facilitated the excessive dissolution of Sn in the nanowires. Sn was distributed throughout the Ge nanowire lattice with no metallic Sn segregation or precipitation at the surface or within the bulk of the nanowires. The non-equilibrium incorporation of Sn into the Ge nanowires can be understood in terms of a kinetic trapping model for impurity incorporation at the triple-phase boundary during growth. PMID:27095012

  19. Low energy x-ray response of Ge detectors with amorphous Ge entrance contacts

    SciTech Connect

    Luke, P.N.; Rossington, C.S.; Wesela, M.F.

    1993-10-01

    The low energy x-ray response of GI detectors with amorphous GI entrance contacts has been evaluated. The spectral background due to near contact incomplete charge collection was found to consist of two components: a low level component which is insensitive to applied voltage and a high level step-like component which is voltage dependent. At high operating voltages, the high level component can be completely suppressed, resulting in background levels which are much lower than those previously observed using GI detectors with Pd surface barrier or B ion implanted contacts, and which also compare favorably to those obtained with Si(Li) x-ray detectors. The response of these detectors to {sup 55}Fe and 1.77 keV x-rays is shown. A qualitative explanation of the origins of the observed background components is presented.

  20. Radiotherapy dosimetry and the thermoluminescence characteristics of Ge-doped fibres of differing germanium dopant concentration and outer diameter

    NASA Astrophysics Data System (ADS)

    Noor, N. Mohd; Fadzil, M. S. Ahmad; Ung, N. M.; Maah, M. J.; Mahdiraji, G. A.; Abdul-Rashid, H. A.; Bradley, D. A.

    2016-09-01

    We examine the influence of elevated dopant concentration on the thermoluminescence characteristics of novel Ge-doped silica fibres. Basic dosimetric characteristics of the TL media were obtained, including linearity, reproducibility, energy dependence, fading, minimum detectable dose and glow curve analysis, use being made of a 60Co gamma irradiation facility (mean energy 1.25 MeV) and an electron linear accelerator producing photons at an accelerating potential of 6 and 10 MV. The 6 mol% Ge-doped fibres were found to provide TL response superior to that of 8- and 10 mol% Ge-doped fibres, both for fibres with outer diameter of 241 μm and 604 μm. Concerning reproducibility, obtained under three different test conditions, at <10% the 6 mol% Ge dopant concentration was observed to provide the superior coefficient of variation (CV). In regard to energy dependence, the 10 mol% Ge doped cylindrical fibres produced the largest gradient values at 0.364 and 0.327 for the 241 μm and 604 μm diameter cylindrical fibres respectively and thus the greatest energy dependency. Measured 33 days post irradiation; the 6 mol% Ge doped cylindrical fibres showed the least TL signal loss, at 21% for the 241 μm cylindrical fibre and <40% for the 604 μm cylindrical fibres. The results also revealed that the 6 mol% optical fibres provided the lowest minimum detectable dose, at 0.027 Gy for 6 MV photon beams. Evaluations of these characteristics are supporting development of novel Ge-doped optical fibres for dosimetry in radiotherapy.

  1. Neutrons in the low-background Ge-detector vicinity estimated from different activation reactions.

    PubMed

    Jovančević, N; Krmar, M

    2011-03-01

    Neutrons produced by cosmic-ray muons in a detector shield and other surrounding materials can be captured or scattered by different nuclei in subsequent reactions. The gamma photons emitted after nuclear capture or scattering from produced Ge isotopes are used to estimate the neutron flux. If a bulk sample measured in some low background gamma spectroscopy system contains hydrogen, a high energy photon (of energy 2223keV) emitted in the process of deuterium production can be used to estimate the flux of thermal neutrons. Results obtained from the interaction of neutrons with H as well as with some Ge isotopes are computed and compared in this paper. The passive lead shield in a detector system is a source of a significant fraction of the gamma radiation induced by capture and inelastic scattering of neutrons. We also used gamma lines emitted by several Pb isotopes to estimate the neutron flux near a detector.

  2. Germanium Multiphase Equation of State

    NASA Astrophysics Data System (ADS)

    Crockett, Scott; Kress, Joel; Rudin, Sven; de Lorenzi-Venneri, Giulia

    2013-06-01

    A new SESAME multiphase Germanium equation of state (EOS) has been developed utilizing the best experimental data and theoretical calculations. The equilibrium EOS includes the GeI (diamond), GeII (beta-Sn) and liquid phases. We will also explore the meta-stable GeIII (tetragonal) phase of germanium. The theoretical calculations used in constraining the EOS are based on quantum molecular dynamics and density functional theory phonon calculations. We propose some physics rich experiments to better understand the dynamics of this element.

  3. Surface Passivation of Germanium Nanowires

    SciTech Connect

    Adhikari, Hemant; Sun, Shiyu; Pianetta, Piero; Chidsey, Chirstopher E.D.; McIntyre, Paul C.; /SLAC, SSRL

    2005-05-13

    The surface of single crystal, cold-wall CVD-grown germanium nanowires was studied by synchrotron radiation photoemission spectroscopy (SR-PES) and also by conventional XPS. The as-grown germanium nanowires seem to be hydrogen terminated. Exposure to laboratory atmosphere leads to germanium oxide growth with oxidation states of Ge{sup 1+}, Ge{sup 2+}, Ge{sup 3+}, while exposure to UV light leads to a predominance of the Ge{sup 4+} oxidation state. Most of the surface oxide could be removed readily by aqueous HF treatment which putatively leaves the nanowire surface hydrogen terminated with limited stability in air. Alternatively, chlorine termination could be achieved by aq. HCl treatment of the native oxide-coated nanowires. Chlorine termination was found to be relatively more stable than the HF-last hydrogen termination.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Indium (In)- and tin (Sn)-based metal induced crystallization (MIC) on amorphous germanium (α-Ge)

    SciTech Connect

    Kang, Dong-Ho; Park, Jin-Hong

    2014-12-15

    Highlights: • In- and Sn-based MIC phenomenon on amorphous (α)-Ge is newly reported. • The In- and Sn-MIC phenomenon respectively started at 250 °C and 400 °C. • The Sn-MIC process presents higher sheet resistance and bigger crystal grains. - Abstract: In this paper, metal-induced crystallization (MIC) phenomenon on α-Ge by indium (In) and tin (Sn) are thoroughly investigated. In- and Sn-MIC process respectively started at 250 °C and 400 °C. Compared to the previously reported MIC samples including In-MIC, Sn-MIC process presented higher sheet resistance (similar to that of SPC) and bigger crystal grains above 50 nm (slightly smaller than that of SPC). According to SIMS analysis, Sn atoms diffused more slowly into Ge than In at 400 °C, providing lower density of heterogeneous nuclei induced by metals and consequently larger crystal grains.

  6. IGEX 76Ge neutrinoless double-beta decay experiment: Prospects for next generation experiments

    NASA Astrophysics Data System (ADS)

    Aalseth, C. E.; Avignone, F. T.; Brodzinski, R. L.; Cebrian, S.; Garcia, E.; Gonzalez, D.; Hensley, W. K.; Irastorza, I. G.; Kirpichnikov, I. V.; Klimenko, A. A.; Miley, H. S.; Morales, A.; Morales, J.; de Solorzano, A. Ortiz; Osetrov, S. B.; Pogosov, V. S.; Puimedon, J.; Reeves, J. H.; Sarsa, M. L.; Smolnikov, A. A.; Starostin, A. S.; Tamanyan, A. G.; Vasenko, A. A.; Vasiliev, S. I.; Villar, J. A.

    2002-05-01

    The International Germanium Experiment (IGEX) has analyzed 117 mol yr of 76Ge data from its isotopically enriched (86% 76Ge) germanium detectors. Applying pulse-shape discrimination to the more recent data, the lower bound on the half-life for neutrinoless double-beta decay of 76Ge is T1/2(0ν)>1.57×1025 yr (90% C.L.). This corresponds to an upper bound in the Majorana neutrino mass parameter, , between 0.33 and 1.35 eV, depending on the choice of theoretical nuclear matrix elements used in the analysis.

  7. Physical characteristics of GE Senographe Essential and DS digital mammography detectors

    SciTech Connect

    Ghetti, Caterina; Borrini, Adriano; Ortenzia, Ornella; Rossi, Raffaella; Ordonez, Pedro L.

    2008-02-15

    The purpose of this study was to investigate physical characteristics of two full field digital mammography (FFDM) systems (GE Senographe Essential and DS). Both are indirect conversion (x ray to light) a-Si flat panels coupled with a CsI(Tl) scintillator. The examined systems have the same pixel size (100 {mu}m) but a different field of view: a conventional size 23x19.2 cm{sup 2} and a large field 24x30.7 cm{sup 2}, specifically designed to image large breasts. In the GE Senographe Essential model relevant improvements in flat panel design were implemented and new deposition tools for metal, a-Si, and CsI(Tl) were introduced by GE. These changes in detector design are expected to be beneficial for advanced applications such as breast tomosynthesis. The presampling modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) were measured for a wide range of exposure (25-240 {mu}Gy) with a RQA-M2 technique (28 kVp with a Mo/Mo target/filter combination and 2 mm of additional aluminum filtration). At 1, 2, and at 4 lp/mm MTF is equal to 0.9, 0.76, and 0.46 for the conventional field detector and to 0.85, 0.59, and 0.24 for the large field detector. The latter detector exhibits an improved NNPS due to a lower electronic noise and a better DQE that reaches 60%. In addition a contrast-detail analysis was performed with CDMAM 3.4 phantom and CDCOM software: GE Senographe DS showed statistically significant poorer detection ability in comparison with the GE Senographe Essential. These results could have been expected, at least qualitatively, considering the relative DQE of the two systems.

  8. SiGe/Si heterojunction internal photoemission long-wavelength infrared detectors fabricated by molecular beam epitaxy

    NASA Technical Reports Server (NTRS)

    Lin, True-Lon; Ksendzov, A.; Dejewski, Suzan M.; Jones, Eric W.; Fathauer, Robert W.; Krabach, Timothy N.; Maserjian, Joseph

    1991-01-01

    A new SiGe/Si heterojunction internal photoemission (HIP) long-wavelength infrared (LWIR) detector has been fabricated by molecular beam epitaxy (MBE). The detection mechanism of the SiGe/Si HIP detector is infrared absorption in the degenerately doped p+-SiGe layer followed by internal photoemission of photoexcited holes over a heterojunction barrier. By adjusting the Ge concentration in the SiGe layer, and, consequently, the valence band offset between SiGe and Si, the cutoff wavelength of SiGe HIP detectors can be extended into the LWIR (8-17-micron) regime. Detectors were fabricated by growing p+-SiGe layers using MBE on patterned p-type Si substrates. The SiGe layers were boron-doped, with concentrations ranging from 10 to the 19th/cu cm to 4 x 10 to the 20th/cu cm. Infrared absorption of 5-25 percent in a 30-nm-thick p+-SiGe layer was measured in the 3-20-micron range using a Fourier transform infrared spectrometer. Quantum efficiencies of 3-5 percent have been obtained from test devices in the 8-12-micron range.

  9. An experimental study of antireflective coatings in Ge light detectors for scintillating bolometers

    NASA Astrophysics Data System (ADS)

    Mancuso, M.; Beeman, J. W.; Giuliani, A.; Dumoulin, L.; Olivieri, E.; Pessina, G.; Plantevin, O.; Rusconi, C.; Tenconi, M.

    2014-01-01

    Luminescent bolometers are double-readout devices able to measure simultaneously the phonon and the light yields after a particle interaction in the detector. This operation allows in some cases to tag the type of the interacting quantum, crucial issue for background control in rare event experiments such as the search for neutrinoless double beta decay and for interactions of particle dark matter candidates. The light detectors used in the LUCIFER and LUMINEU searches (projects aiming at the study of the double beta interesting candidates 82Se and 100Mo using ZnSe and ZnMoO4 scintillating bolometers) consist of hyper-pure Ge thin slabs equipped with NTD thermistors. A substantial sensitivity improvement of the Ge light detectors can be obtained applying a proper anti-reflective coatings on the Ge side exposed to the luminescent bolometer. The present paper deals with the investigation of this aspect, proving and quantifying the positive effect of a SiO2 and a SiO coating and setting the experimental bases for future tests of other coating materials. The results confirm that an appropriate coating procedure helps in improving the sensitivity of bolometric light detectors by an important factor (in the range 20% - 35%) and needs to be included in the recipe for the development of an optimized radio-pure scintillating bolometer.

  10. O2/ K/ Ge(100) 2 × 1 and O2/ Cs/ Ge(100) 2 × 1: puzzling behavior of K and Cs in the oxidation of germanium

    NASA Astrophysics Data System (ADS)

    Schirm, K. M.; Soukiassian, P.; Borensztein, Y.; Nishigaki, S.; Dong, G. S.; Bonnet, J. E.; Hricovini, K.

    1993-07-01

    The effect of alkali-metal overlayers (K, Cs) on the room-temperature oxidation of the Ge(100)2 × 1 surface in the presence of molecular oxygen was investigated by core-level and valence-band photoemission spectroscopy using synchrotron radiation. In strong contrast to the behavior observed for many other elemental or compound semiconductor surfaces, the presence of a K or Cs layer does not enhance the oxidation rate as expected but rather poisoned it since the K (Cs) covered Ge(100)2 × 1 surface exhibits significantly smaller amount of oxides for the same oxygen exposures. This behavior indicates that K does not act as a catalyst as observed in the cases of many other semiconductor surfaces, but as an oxygen acceptor, in agreement with a classical model of electron affinity.

  11. Hafnium germanium telluride

    PubMed Central

    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

  12. Photoresponse Model for Si_(1-x)Ge_x/Si Heterojunction Internal Photoemission Infrared Detector

    NASA Technical Reports Server (NTRS)

    Lin, T.; Park, J. S.; Gunapala, S. D.; Jones, E. W.; Castillo, H. M. Del

    1993-01-01

    A photoresponse model has been developed for the Si_(1-x)Ge_x/Si heterojunction internalphotoemission (HIP) infrared detector at wavelengths corresponding to photon energies less than theFermi energy. A Si_(0.7)Ge_(0.3)/Si HIP detector with a cutoff wavelength of 23 micrometers andan emission coefficient of 0.4 eV^(-1) has been demonstrated. The model agrees with the measureddetector response at lambda greater than 8 micrometers. The potential barrier determined by themodel is in close agreement (difference similar to 4 meV) with the potential barrier determined by theRichardson plot, compared to the discrepancies of 20-50 meV usually observed for PtSi Schottkydetectors.

  13. Interactive Analysis of Gamm-ray Spectra from GE Semiconductor Detectors

    SciTech Connect

    Egger, Ann

    1997-09-25

    GAUSS IX is a tool to interactively analyze gamma-ray spectra from Ge Semicondutor detectors. The user has full control over the view of the spectrum being analyzed and the location of the peaks and peak regions. Analysis is performed at user request to the requested peak regions. The fit of a peak region can be previewed before archival or deletion. An iterative procedure is available for calibrating the energy and width equations.

  14. GAUSS IX. Interactive Analysis of Gamm-ray Spectra from GE Semiconductor Detectors

    SciTech Connect

    Egger, A.E.

    1997-01-01

    GAUSS IX is a tool to interactively analyze gamma-ray spectra from Ge Semicondutor detectors. The user has full control over the view of the spectrum being analyzed and the location of the peaks and peak regions. Analysis is performed at user request to the requested peak regions. The fit of a peak region can be previewed before archival or deletion. An iterative procedure is available for calibrating the energy and width equations.

  15. Performances Of Arrays Of Ge:Ga Far-Infrared Detectors

    NASA Technical Reports Server (NTRS)

    Mccreight, C.; Farhoomand, J.

    1992-01-01

    Report presents evaluation of performances of two electronic modules containing few-element linear focal-plane arrays of Ge:Ga photodetectors and associated multiplexing readout circuitry. Tested to demonstrate feasibility of many-element, two-dimensional focal-plane arrays of far-infrared detectors and associated circuitry for use in astronomical and other low-background scientific observations. Revealed deficiencies that must be overcome in future designs.

  16. Development of low dark current SiGe-detector arrays for visible-NIR imaging sensor

    NASA Astrophysics Data System (ADS)

    Sood, Ashok K.; Richwine, Robert A.; Puri, Yash R.; DiLello, Nicole; Hoyt, Judy L.; Akinwande, Tayo I.; Horn, Stuart; Balcerak, Ray S.; Bulman, Gary; Venkatasubramanian, Rama; D'Souza, Arvind I.; Bramhall, Thomas G.

    2009-05-01

    SiGe based Focal Plane Arrays offer a low cost alternative for developing visible- NIR focal plane arrays that will cover the spectral band from 0.4 to 1.6 microns. The attractive features of SiGe based IRFPA's will take advantage of Silicon based technology, that promises small feature size, low dark current and compatibility with the low power silicon CMOS circuits for signal processing. This paper discusses performance comparison for the SiGe based VIS-NIR Sensor with performance characteristics of InGaAs, InSb, and HgCdTe based IRFPA's. Various approaches including device designs are discussed for reducing the dark current in SiGe detector arrays; these include Superlattice, Quantum dot and Buried junction designs that have the potential of reducing the dark current by several orders of magnitude. The paper also discusses approaches to reduce the leakage current for small detector size and fabrication techniques. In addition several innovative approaches that have the potential of increasing the spectral response to 1.8 microns and beyond.

  17. Indirect absorption in germanium quantum wells

    NASA Astrophysics Data System (ADS)

    Schaevitz, R. K.; Ly-Gagnon, D. S.; Roth, J. E.; Edwards, E. H.; Miller, D. A. B.

    2011-09-01

    Germanium has become a promising material for creating CMOS-compatible optoelectronic devices, such as modulators and detectors employing the Franz-Keldysh effect (FKE) or the quantum-confined Stark effect (QCSE), which meet strict energy and density requirements for future interconnects. To improve Ge-based modulator design, it is important to understand the contributions to the insertion loss (IL). With indirect absorption being the primary component of IL, we have experimentally determined the strength of this loss and compared it with theoretical models. For the first time, we have used the more sensitive photocurrent measurements for determining the effective absorption coefficient in our Ge/SiGe quantum well material employing QCSE. This measurement technique enables measurement of the absorption coefficient over four orders of magnitude. We find good agreement between our thin Ge quantum wells and the bulk material parameters and theoretical models. Similar to bulk Ge, we find that the 27.7 meV LA phonon is dominant in these quantum confined structures and that the electroabsorption profile can be predicted using the model presented by Frova, Phys. Rev., 145 (1966).

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

    PubMed

    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.

  19. Improvements to the Leake neutron detector II: Extension to 10 GeV energy

    NASA Astrophysics Data System (ADS)

    Leake, J. W.; Lowe, T.; Mason, R. S.

    2009-01-01

    We report on an improved design of neutron ambient dose equivalent (DE) detector, SNS-LINUS, consisting of a spherical polyethylene detector with internal shields of boron and lead based on the LINUS model thus extending the response to the GeV region. The computed Monte Carlo neutron ambient DE energy response is within a factor ±2.4 from 0.1 keV to 10 GeV with a detector weight of 7.8 kg that is significantly lower than other LINUS designs. The ambient DE response in the 50 keV-10 MeV range is within a factor ±1.36 (i.e. ±30%). The main applications are likely to be around particle accelerators, in aircraft or in spacecraft. The improved response in the 20 MeV energy region should make it attractive for use with fission sources. The computed responses of the SNS NGREM and LINUS detectors to pulsed neutrons and limits for their prudent use in portable monitors in such fields are given. The effect of large gamma bursts on the measurement of pulsed neutrons is discussed with recommendations made to enable operation up to 10 μGy of gamma radiation per burst. We propose a method of extending the dynamic range for pulsed neutron detection in which the neutron decay within the moderator is used to make measurements at a time at which the count rate losses are acceptable.

  20. Precision Electron-Beam Polarimetry at 1 GeV Using Diamond Microstrip Detectors

    NASA Astrophysics Data System (ADS)

    Narayan, A.; Jones, D.; Cornejo, J. C.; Dalton, M. M.; Deconinck, W.; Dutta, D.; Gaskell, D.; Martin, J. W.; Paschke, K. D.; Tvaskis, V.; Asaturyan, A.; Benesch, J.; Cates, G.; Cavness, B. S.; Dillon-Townes, L. A.; Hays, G.; Ihloff, E.; Jones, R.; King, P. M.; Kowalski, S.; Kurchaninov, L.; Lee, L.; McCreary, A.; McDonald, M.; Micherdzinska, A.; Mkrtchyan, A.; Mkrtchyan, H.; Nelyubin, V.; Page, S.; Ramsay, W. D.; Solvignon, P.; Storey, D.; Tobias, A.; Urban, E.; Vidal, C.; Waidyawansa, B.; Wang, P.; Zhamkotchyan, S.

    2016-01-01

    We report on the highest precision yet achieved in the measurement of the polarization of a low-energy, O (1 GeV ) , continuous-wave (CW) electron beam, accomplished using a new polarimeter based on electron-photon scattering, in Hall C at Jefferson Lab. A number of technical innovations were necessary, including a novel method for precise control of the laser polarization in a cavity and a novel diamond microstrip detector that was able to capture most of the spectrum of scattered electrons. The data analysis technique exploited track finding, the high granularity of the detector, and its large acceptance. The polarization of the 180 -μ A , 1.16-GeV electron beam was measured with a statistical precision of <1 % per hour and a systematic uncertainty of 0.59%. This exceeds the level of precision required by the Qweak experiment, a measurement of the weak vector charge of the proton. Proposed future low-energy experiments require polarization uncertainty <0.4 %, and this result represents an important demonstration of that possibility. This measurement is the first use of diamond detectors for particle tracking in an experiment. It demonstrates the stable operation of a diamond-based tracking detector in a high radiation environment, for two years.

  1. Precision electron-beam polarimetry at 1 GeV using diamond microstrip detectors

    DOE PAGES

    Narayan, A.; Jones, D.; Cornejo, J. C.; ...

    2016-02-16

    We report on the highest precision yet achieved in the measurement of the polarization of a low-energy, O(1 GeV), continuous-wave (CW) electron beam, accomplished using a new polarimeter based on electron-photon scattering, in Hall C at Jefferson Lab. A number of technical innovations were necessary, including a novel method for precise control of the laser polarization in a cavity and a novel diamond microstrip detector that was able to capture most of the spectrum of scattered electrons. The data analysis technique exploited track finding, the high granularity of the detector, and its large acceptance. The polarization of the 180–μA, 1.16-GeVmore » electron beam was measured with a statistical precision of <1% per hour and a systematic uncertainty of 0.59%. This exceeds the level of precision required by the Qweak experiment, a measurement of the weak vector charge of the proton. Proposed future low-energy experiments require polarization uncertainty < 0.4%, and this result represents an important demonstration of that possibility. This measurement is the first use of diamond detectors for particle tracking in an experiment. As a result, it demonstrates the stable operation of a diamond-based tracking detector in a high radiation environment, for two years.« less

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

    NASA Astrophysics Data System (ADS)

    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. Gamma-ray pulse height spectrum analysis on systems with multiple Ge detectors using spectrum summing

    SciTech Connect

    Killian, E.W.

    1997-11-01

    A technique has been developed at the Idaho National Engineering Laboratory to sum high resolution gamma-ray pulse spectra from systems with multiple Ge detectors. Lockheed Martin Idaho Technologies Company operates a multi-detector spectrometer configuration at the Stored Waste Examination Pilot Plant facility which is used to characterize the radionuclide contents in waste drums destined for shipment to Waste Isolation Pilot Plant. This summing technique was developed to increase the sensitivity of the system, reduce the count times required to properly quantify the radio-nuclides and provide a more consistent methodology for combining data collected from multiple detectors. In spectrometer systems with multiple detectors looking at non homogeneous waste forms it is often difficult to combine individual spectrum analysis results from each detector to obtain a meaningful result for the total waste container. This is particularly true when the counting statistics in each individual spectrum are poor. The spectrum summing technique adds the spectra collected by each detector into a single spectrum which has better counting statistics than each individual spectrum. A normal spectral analysis program can then be used to analyze the sum spectrum to obtain radio-nuclide values which have smaller errors and do not have to be further manipulated to obtain results for the total waste container. 2 refs., 2 figs.

  4. Germanium geochemistry and mineralogy

    USGS Publications Warehouse

    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

  5. Intersubband absorption in Si(1-x)Ge(x/Si superlattices for long wavelength infrared detectors

    NASA Technical Reports Server (NTRS)

    Rajakarunanayake, Yasantha; Mcgill, Tom C.

    1990-01-01

    Researchers calculated the absorption strengths for intersubband transitions in n-type Si(1-x)Ge(x)/Si superlattices. These transitions can be used for the detection of long-wavelength infrared radiation. A significant advantage in Si(1-x)Ge(x)/Si supperlattice detectors is the ability to detect normally incident light; in Ga(1-x)Al(x)As/GaAs superlattices, intersubband absorption is possible only if the incident light contains a polarization component in the growth direction of the superlattice. Researchers present detailed calculation of absorption coefficients, and peak absorption wavelengths for (100), (111) and (110) Si(1-x)Ge(x)/Si superlattices. Peak absorption strengths of about 2000 to 6000 cm(exp -1) were obtained for typical sheet doping concentrations (approx. equals 10(exp 12)cm(exp -2)). Absorption comparable to that in Ga(1-x)Al(x)As/GaAs superlattice detectors, compatibility with existing Si technology, and the ability to detect normally incident light make these devices promising for future applications.

  6. The Oral Intake of Organic Germanium, Ge-132, Elevates α-Tocopherol Levels in the Plas-ma and Modulates Hepatic Gene Expression Profiles to Promote Immune Activation in Mice.

    PubMed

    Nakamura, Takashi; Takeda, Tomoya; Tokuji, Yoshihiko

    2014-01-01

    The common water-soluble organic germanium compound poly-trans-[(2-carboxyethyl) germasesquioxane] (Ge-132) exhibits activities related to immune responses and antioxidant induction. In this study, we evaluated the antioxidative effect of dietary Ge-132 in the plasma of mice. Male ICR mice (seven mice per group) received an AIN-76 diet with 0.05% Ge-132; three groups received the Ge-132-containing diet for 0, 1 or 4 days. The plasma alpha-tocopherol (α-tocopherol) concentration increased from 6.85 to 9.60 μg/ml after 4 days of Ge-132 intake (p<0.05). We evaluated the changes in hepatic gene expression related to antioxidative activity as well as in the entire expression profile after one day of Ge-132 intake, using DNA microarray technology. We identified 1,220 genes with altered expression levels greater than 1.5-fold (increased or decreased) as a result of Ge-132 intake, and α-tocopherol transfer protein (Ttpa) gene expression was increased 1.62-fold. Immune activation was identified as the category with the most changes (containing 60 Gene Ontology (GO) term biological processes (BPs), 41 genes) via functional clustering analysis of altered gene expression. Ge-132 affected genes in clusters related to ATP production (22 GO term BPs, 21 genes), lipid metabolism (4 GO term BPs, 38 genes) and apoptosis (5 GO term BPs). Many GO term BPs containing these categories were significantly affected by the Ge-132 intake. Oral Ge-132 intake may therefore have increased plasma α-tocopherol levels by up-regulating α-tocopherol transfer protein (Ttpa) gene expression.

  7. Calculations of the interference of annihilation radiations with positron spectra in a Ge detector

    NASA Astrophysics Data System (ADS)

    Avignone, F. T.; Noma, H.; Moltz, D. M.; Toth, K. S.

    1981-10-01

    The distortion of the Kurie plots of allowed positron spectra due to annihilation radiations was calculated by a simple Monte-Carlo technique for a small intrinsic Ge detector. The experimentally observed non-linearity near the end point is accurately reproduced by the calculations. Corrections were calculated for 15 theoretical allowed spectra with end-point energies ranging from 2.5 to 10 MeV for one small detector 1.6 cm in diameter and 0.7 cm thick and one larger detector 4.0 cm in diameter and 1.0 cm thick. The major effect of this interference is to shift the end-point up in energy from 182 keV at 2.5 MeV and to 204 keV at 9 MeV in the small detector and from 279 keV at 2.5 MeV and to 321 keV at 9 MeV in the larger detector. The method was used to correct the end-point energies of the two positron branches in the decay of 82Sr. The corrected data give values of (3.19 ± 0.02) and (2.42 ± 0.02) MeV. The resulting Q-value is (4.21 ± 0.02) MeV.

  8. Examining Signal Decomposition in Ge Tracking Detectors through Source-Based Coincidence Measurements

    NASA Astrophysics Data System (ADS)

    Cromaz, M.; Campbell, C. M.; Clark, R. M.; Crawford, H. L.; Fallon, P.; Lee, I. Y.; Macchiavelli, A. O.; Wiens, A.; Riley, L.; Taniuchi, R.

    2016-03-01

    The performance of a gamma-ray tracking detector, such as those used in the GRETINA spectrometer, is dependent on its ability to accurately locate multiple interaction points in the Ge crystal. Interactions are located by observing both net and induced charge as a function of time on the detector's segmented contact. As multiple interactions are likely, linear combinations of basis signals, a set of simulated signals with unit charge deposited on a grid that spans the detector volume, are fit against the observed signal yielding the interaction positions. While the location of the primary interaction point was found to be good (σpos <= 2 mm) the location of secondary, lower energy interactions appear less reliable. To investigate this issue, we carried out a series of source-based coincidence measurements. These employed a collimated source and a secondary detector by which we could select single interaction events. Given these events originate from known positions, we can take them in combination to directly test the efficacy of the signal decomposition procedure. We will present a description of the method and preliminary results with a GRETINA quad detector. This work is supported by the U.S. Department of Energy under Contract No. DE-AC02-05CHI1231.

  9. A review on germanium nanowires.

    PubMed

    Pei, Li Z; Cai, Zheng Y

    2012-01-01

    Ge nanowires exhibit wide application potential in the fields of nanoscale devices due to their excellently optical and electrical properties. This article reviews the recent progress and patents of Ge nanowires. The recent progress and patents for the synthesis of Ge nanowires using chemical vapor deposition, laser ablation, thermal evaporation, template method and supercritical fluid-liquid-solid method are demonstrated. Amorphous germanium oxide layer and defects existing in Ge nanowires result in poor Ohmic contact between Ge nanowires and electrodes. Therefore, Ge nanowires should be passivated in order to deposit connecting electrodes before applied in nanoelectronic devices. The experimental progress and patents on the application of Ge nanowires as field effect transistors, lithium batteries, photoresistors, memory cell and fluid sensors are discussed. Finally, the future development of Ge nanowires for the synthesis and practical application is also discussed.

  10. Solution synthesis of germanium nanocrystals

    DOEpatents

    Gerung, Henry [Albuquerque, NM; Boyle, Timothy J [Kensington, MD; Bunge, Scott D [Cuyahoga Falls, OH

    2009-09-22

    A method for providing a route for the synthesis of a Ge(0) nanometer-sized material from. A Ge(II) precursor is dissolved in a ligand heated to a temperature, generally between approximately 100.degree. C. and 400.degree. C., sufficient to thermally reduce the Ge(II) to Ge(0), where the ligand is a compound that can bond to the surface of the germanium nanomaterials to subsequently prevent agglomeration of the nanomaterials. The ligand encapsulates the surface of the Ge(0) material to prevent agglomeration. The resulting solution is cooled for handling, with the cooling characteristics useful in controlling the size and size distribution of the Ge(0) materials. The characteristics of the Ge(II) precursor determine whether the Ge(0) materials that result will be nanocrystals or nanowires.

  11. Mesostructured Metal Germanium Sulfide and Selenide Materials Based on the Tetrahedral [Ge 4S 10] 4- and [Ge 4Se 10] 4- Units: Surfactant Templated Three-Dimensional Disordered Frameworks Perforated with Worm Holes

    NASA Astrophysics Data System (ADS)

    Wachhold, Michael; Kasthuri Rangan, K.; Lei, Ming; Thorpe, M. F.; Billinge, Simon J. L.; Petkov, Valeri; Heising, Joy; Kanatzidis, Mercouri G.

    2000-06-01

    The polymerization of [Ge4S10]4- and [Ge4Se10]4- unit clusters with the divalent metal ions Zn2+, Cd2+, Hg2+, Ni2+, and Co2+ in the presence of various surfactant cations leads to novel mesostructured phases. The surfactants are the quaternary ammonium salts C12H25NMe3Br, C14H29NMe3Br, C16H33NMe3Br, and C18H37NMe3Br, which play the role of templates, helping to assemble a three-dimensional mesostructured metal-germanium chalcogenide framework. These materials are stoichiometric in nature and have the formula of (R-NMe3)2[MGe4Q10] (Q=S, Se). The local atomic structure was probed by X-ray diffuse scattering and pair distribution function analysis methods and indicates that the adamantane clusters stay intact while the linking metal atoms possess a tetrahedral coordination environment. A model can be derived, from the comparison of measured and simulated X-ray powder diffraction patterns, describing the structure as an amorphous three-dimensional framework consisting of adamantane [Ge4Q10]4- units that are bridged by tetrahedral coordinated M2+ cations. The network structures used in the simulations were derived from corresponding disordered structures developed for amorphous silicon. The frameworks in (R-NMe3)2[MGe4Q10] are perforated with worm hole-like tunnels, occupied by the surfactant cations, which show no long-range order. This motif is supported by transmission electron microscopy images of these materials. The pore sizes of these channels were estimated to lie in the range of 20-30 Å, depending on the appointed surfactant cation length. The framework wall thickness of ca. 10 Å is thereby independent from the surfactant molecules used. Up to 80% of the surfactant molecules can be removed by thermal degradation under vacuum without loss of mesostructural integrity. Physical, chemical, and spectroscopic properties of these materials are discussed.

  12. Binding of germanium of Pseudomonas putida cells

    SciTech Connect

    Klapcinska, B.; Chmielowski, J.

    1986-05-01

    The binding of germanium to Pseudomonas putida ATCC 33015 was investigated by using whole intact cells grown in a medium supplemented with GeO/sub 2/ and catechol or acetate. Electron-microscopic examination of the control and metal-loaded samples revealed that germanium was bound within the cell envelope. A certain number of small electron-dense deposits of the bound element were found in the cytoplasm when the cells were grown in the presence of GeO/sub 2/ and catechol. The study of germanium distribution in cellular fractions revealed that catechol facilitated the intracellular accumulation of this element.

  13. Evaluation of a far infrared Ge:Ga multiplexed detector array

    NASA Technical Reports Server (NTRS)

    Farhoomand, Jam; Mccreight, Craig

    1990-01-01

    The performance of a multielement Ge:Ga linear array under low-background conditions is investigated. On-focal plane switching is accomplished by MOSFET switches and the integrated charge is made available through MOSFET source followers. The tests were conducted at 106 microns and the radiation on the detectors was confined to a spectral window 1.25 microns wide using a stack of cold filters. At 4.2 K, the responsivity was measured to be nominally 584 A/W, and the NEP was 1.0 x 10 exp -16 W/sq rt Hz. A detailed description of the test setup and the procedure is presented.

  14. A Search for GeV-TeV Emission from GRBs Using the Milagro Detector

    SciTech Connect

    Aune, Taylor

    2009-05-25

    The Milagro detector surveyed the sky almost continuously in the very high energy regime from January 2000 through March 2008. During that time, over 130 GRBs have been detected and well localized by satellites within its 2 sr field of view. We have used Milagro data to search for >1 GeV emission from these bursts. Milagro is a water Cerenkov detector designed primarily for observations in the 0.1-100 TeV energy range. Milagro was operated simultaneously in both standard mode and 'scaler' mode. In the standard analysis, the direction and energy of an incoming particle is determined by reconstructing the air shower produced when the particle interacts in the Earth's atmosphere. In 'scaler' mode, the rates of the PMTs are monitored and fluctuations temporally coincident with GRBs are searched for. No significant emission was discovered using either method and the upper limit on the emission for each burst with known redshift is reported.

  15. Studies of Nuclear Structure using Radioactive Decay and a Large Array of Compton Suppressed Ge Detectors

    NASA Astrophysics Data System (ADS)

    Wood, John L.

    2000-11-01

    Radioactive decay has long played a role in contributing to the elucidation of nuclear structure. However compared to in-beam gamma-ray spectroscopy, which has been combined with the extraordinary power of multi-detector arrays, radioactive decay scheme studies have been carried out usually with rather modest detector set-ups (two detectors, no Compton suppression). An extensive program to rectify this situation has been initiated using the "8-PI spectrometer"[1]. This is an array of 20 Compton-suppressed Ge detectors with exceptional stability and peak-to-total ratio. Experiments performed[2] recently at Lawrence Berkeley Laboratory, to better characterize nuclear deformation properties and the onset of deformation in nuclei, will be described. Future plans for the study of nuclei far from beta stability at the TRIUMF/ISAC Facility using the 8-PI spectrometer will also be outlined. [1] J.P.Martin et al., Nucl.Instr.Meth. A 257, 301 (1987). [2] See, e.g., W.D.Kulp et al. Bull.Am.Phys.Soc. 44, 63 (1999); W.D.Kulp et al., ibid., Williamsburg Meeting, Oct 4-7 (2000).

  16. A multi-channel monolithic Ge detector system for fluorescence x-ray absorption spectroscopy

    SciTech Connect

    Bucher, J.J.; Allen, P.G.; Edelstein, N.M.; Shuh, D.K.; Madden, N.W.; Cork, C.; Luke, P.; Pehl, D.; Malone, D.

    1995-03-01

    Construction and performance of a monolithic quad-pixel Ge detector for fluorescence x-ray absorption spectroscopy (XAS) at synchrotron radiation sources are described. The detector semiconductor element has an active surface area of 4.0 cm{sup 2} which is electrically separated into four 1.0 cm{sup 2} pixels, with little interfacial dead volume. Spatial response of the array shows that cross-talk between adjacent pixels is < 10% for 5.9 keV photons that fall within 0.5 mm of the pixel boundaries. The detector electronics system uses pre-amplifiers built at LBNL with commercial Tennelec Model TC 244 amplifiers. Using an {sup 55}Fe test source (MnK{sub {alpha}}, 5.9 keV), energy resolution of better than 200 eV is achieved with a 4 {mu}sec peaking time. At 0.5 {mu}sec peaking time, pulse pileup results in a 75% throughput efficiency for an incoming count rate of 100 kHz. Initial XAS fluoresncece measurements at the beamline 4 wiggler end stations at SSRL show that the detector system has several advantages over commercial x-ray spectrometers for low-concentration counting.

  17. First look at Gamma-ray background lines in the SPI Ge detector spectra

    NASA Astrophysics Data System (ADS)

    Wunderer, C. B.; Weidenspointner, G.; Cordier, B.; Diehl, R.; Jean, P.; v. Kienlin, A.; Knoedlseder, J.; Leleux, P.; Lichti, G.; Roques, J.-P.; Schanne, S.; Schoenfelder, V.; Shrader, C.; Skinner, G.; Strong, A.; Sturner, S.; Teegarden, B.; Vedrenne, G.

    2003-03-01

    ESA's INTEGRAL observatory has been launched successfully on October 17, 2002. Since November 2002, the 19 Ge detectors comprising the camera of one of its main instruments, the Spectrometer SPI, have been recording data. They cover the energy range from ˜ 20 keV to ˜ 8 MeV. The spectrometer is particularly suited to the observations of gamma-ray line emission from astrophysical objects of interest. However, since many astrophysically interesting lines have energies very close to energies of some instrumental background lines, and since some astrophysically interesting radioactive isotopes are also produced within spacecraft and instrument materials by cosmic-ray activation, a detailed study of the gamma-ray background lines seen with the SPI Ge detectors is necessary. We present the first steps taken towards understanding the line components of the gamma-ray background observed with SPI. This includes both isotope identification and preliminary studies of temporal variations. Emphasis is placed on the energy regions of particular interest to astrophysics, especially around the 60Fe and 26Al lines. Preliminary sensitivity estimates for some astrophysically interesting lines will also be presented. This work has been supported by the DLR.

  18. Simulation of Cosmogenic and Radioactive Backgrounds for the CoGeNT Dark Matter Detector

    NASA Astrophysics Data System (ADS)

    Kos, Mark

    2012-03-01

    We have completed a comprehensive list of simulations of the cosmogenic and radioactive backgrounds for the CoGeNT detector. For the cosmogenic backgrounds we include muon-induced neutrons produced in the shielding material and muon-induced neutrons from the surrounding cavern rock. We also include electrons, positrons, and gammas produced by the through-going muons. For the radioactive backgrounds we include (alpha,n) neutrons from the cavern, (alpha,n) and fission neutrons from the HDPE shielding, fission neutrons from the lead shielding, and uranium and thorium chain backgrounds in materials near the detector. The energy distributions derived from the simulations are normalized to the expected flux for the cosmogenic backgrounds, and to the measured uranium and thorium contamination for the radioactive backgrounds. We then compared the background distributions to the data and the results of these comparisons are presented. We also present results from simulations of the same background sources for the next generation of CoGeNT, C4.

  19. Elemental boron-doped p(+)-SiGe layers grown by molecular beam epitaxy for infrared detector applications

    NASA Astrophysics Data System (ADS)

    Lin, T. L.; George, T.; Jones, E. W.; Ksendzov, A.; Huberman, M. L.

    1992-01-01

    SiGe/Si heterojunction internal photoemission (HIP) detectors have been fabricated utilizing molecular beam epitaxy of p(+)-SiGe layers on p(-)-Si substrates. Elemental boron from a high-temperature effusion cell was used as the dopant source during MBE growth, and high doping concentrations have been achieved. Strong infrared absorption, mainly by free-carrier absorption, was observed for the degenerately doped SiGe layers. The use of elemental boron as the dopant source allows a low MBE growth temperature, resulting in improved crystalline quality and smooth surface morphology of the Si(0.7)Ge(0.3) layers. Nearly ideal thermionic emission dark current characteristics have been obtained. Photoresponse of the HIP detectors in the long-wavelength infrared regime has been demonstrated.

  20. Elemental boron-doped p(+)-SiGe layers grown by molecular beam epitaxy for infrared detector applications

    NASA Technical Reports Server (NTRS)

    Lin, T. L.; George, T.; Jones, E. W.; Ksendzov, A.; Huberman, M. L.

    1992-01-01

    SiGe/Si heterojunction internal photoemission (HIP) detectors have been fabricated utilizing molecular beam epitaxy of p(+)-SiGe layers on p(-)-Si substrates. Elemental boron from a high-temperature effusion cell was used as the dopant source during MBE growth, and high doping concentrations have been achieved. Strong infrared absorption, mainly by free-carrier absorption, was observed for the degenerately doped SiGe layers. The use of elemental boron as the dopant source allows a low MBE growth temperature, resulting in improved crystalline quality and smooth surface morphology of the Si(0.7)Ge(0.3) layers. Nearly ideal thermionic emission dark current characteristics have been obtained. Photoresponse of the HIP detectors in the long-wavelength infrared regime has been demonstrated.

  1. All-fiber power sensor based on silicon-germanium core fiber F-P cavity

    NASA Astrophysics Data System (ADS)

    Wang, Tengjiao; Chen, Na; Zhao, Ziwen; Pang, Fufei; Chen, Zhenyi; Wang, Tingyun

    2017-06-01

    An all-optical power sensor based on silicon-germanium (SiGe) core fiber Fabry-Perot (F-P) cavity is proposed. The F-P sensor was formed by fusion splicing SiGe core fiber with conventional single-mode fiber (SMF). The 980 nm laser can be absorbed efficiently by the silicon-germanium material, resulting in the temperature increase inside the cavity, which induces the drifts of the reflection spectrum. The injected power has a very good linear relationship with the drifts experimentally, and the power sensitivity is up to 1.7 nm/mW, which may have great potential for all-fiber power detector.

  2. Measurements with a Ge detector and Monte Carlo computations of dose rate yields due to cosmic muons.

    PubMed

    Clouvas, A; Xanthos, S; Antonopoulos-Domis, M; Silva, J

    2003-02-01

    The present work shows how portable Ge detectors can be useful for measurements of the dose rate due to ionizing cosmic radiation. The methodology proposed converts the cosmic radiation induced background in a Ge crystal (energy range above 3 MeV) to the absorbed dose rate due to muons, which are responsible for 75% of the cosmic radiation dose rate at sea level. The key point is to observe in the high energy range (above 20 MeV) the broad muon peak resulting from the most probable energy loss of muons in the Ge detector. An energy shift of the muon peak was observed, as expected, for increasing dimensions of three Ge crystals (10%, 20%, and 70% efficiency). Taking into account the dimensions of the three detectors the location of the three muon peaks was reproduced by Monte Carlo computations using the GEANT code. The absorbed dose rate due to muons has been measured in 50 indoor and outdoor locations at Thessaloniki, the second largest town of Greece, with a portable Ge detector and converted to the absorbed dose rate due to muons in an ICRU sphere representing the human body by using a factor derived from Monte Carlo computations. The outdoor and indoor mean muon dose rate was 25 nGy h(-1) and 17.8 nGy h(-1), respectively. The shielding factor for the 40 indoor measurements ranges from 0.5 to 0.9 with a most probable value between 0.7-0.8.

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

    PubMed

    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.

  4. Electrodeposited germanium nanowires.

    PubMed

    Mahenderkar, Naveen K; Liu, Ying-Chau; Koza, Jakub A; Switzer, Jay A

    2014-09-23

    Germanium (Ge) is a group IV semiconductor with superior electronic properties compared with silicon, such as larger carrier mobilities and smaller effective masses. It is also a candidate anode material for lithium-ion batteries. Here, a simple, one-step method is introduced to electrodeposit dense arrays of Ge nanowires onto indium tin oxide (ITO) substrates from aqueous solution. The electrochemical reduction of ITO produces In nanoparticles that act as a reduction site for aqueous Ge(IV) species, and as a solvent for the crystallization of Ge nanowires. Nanowires deposited at 95 °C have an average diameter of 100 nm, whereas those deposited at room temperature have an average diameter of 35 nm. Both optical absorption and Raman spectroscopy suggest that the electrodeposited Ge is degenerate. The material has an indirect bandgap of 0.90-0.92 eV, compared with a value of 0.67 eV for bulk, intrinsic Ge. The blue shift is attributed to the Moss-Burstein effect, because the material is a p-type degenerate semiconductor. On the basis of the magnitude of the blue shift, the hole concentration is estimated to be 8 × 10(19) cm(-3). This corresponds to an In impurity concentration of about 0.2 atom %. The resistivity of the wires is estimated to be 4 × 10(-5) Ω·cm. The high conductivity of the wires should make them ideal for lithium-ion battery applications.

  5. Background rejection capabilities of a Compton imaging telescope setup with a DSSD Ge planar detector and AGATA

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

    In this work, we show the first Monte Carlo results about the performance of the Ge array which we propose for the DESPEC experiment at FAIR, when the background algorithm developed for AGATA is applied. The main objective of our study is to characterize the capabilities of the γ-spectroscopy system, made up of AGATA detectors in a semi-spherical distribution covering a 1π solid angle and a set of planar Ge detectors in a daisy configuration, to discriminate between γ sources placed at different locations.

  6. Silicon germanium (SiGe) radioisotope thermoelectric generator (RTG) program for space missions. Nineteenth technical progress report, December 1980-January 1981

    SciTech Connect

    Whitmore, C. W.; Silverman, G.

    1981-01-01

    Work accomplished during the reporting period on the DOE Silicon Germanium RTG Program, Contract DE-AC01-79ET-32043 is described. This program consists of the following three tasks: multi-hundred watt RTG for the Galileo probe mission; reestablishment of silicon germanium unicouple capability; and general purpose heat source RTG for the international solar polar and Galileo orbiter missions. Details of program progress for each task, including a milestone schedule and a discussion of current problem areas (if any) are presented.

  7. New approach for calibration the efficiency of HpGe detectors

    SciTech Connect

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

    2014-02-12

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

  8. Use of LGD-256 hodoscopic shower detector for registration of neutral mesons with energies to 10 GeV

    SciTech Connect

    Akimenko, S.A.; Belousov, V.I.; Blik, A.M.; Glinka, V.; Kolosov, V.N.; Korolev, V.M.; Kut'in, V.M.; Pavlinov, A.I.; Romanovskii, V.I.; Sergeev, S.V.; Solov'ev, A.S.

    1988-07-01

    A hodoscopic shower detector is described that contains 256 elements of TF-1 lead glass with dimensions of 85 x 85 x 350 mm and is a part of the Giperon unit. The characteristics and possibilities of the detector are studied using the quasibinary charge-transfer reaction ..pi../sup +/ ..-->.. ..pi../sup 0/ (eta, omega, f) by nuclei at an energy of 10 GeV.

  9. Germanium JFET for Cryogenic Readout Electronics

    NASA Technical Reports Server (NTRS)

    Das, N. C.; Monroy, C.; Jhabvala, M.; Shu, P.

    1999-01-01

    The n-channel Germanium junction field effect transistor (Ge-JFET) was designed and fabricated for cryogenic applications. The Ge-JFET exhibits superior noise performance at liquid nitrogen temperature (77 K). From the device current voltage characteristics of n-channel JFETs, it is seen that transconductance increases monotonically with the lowering of temperature to 4.2 K (liquid helium temperature).

  10. PHASE EQUILIBRIUM STUDIES OF GERMANIUM AND SILICON AT HIGH PRESSURES.

    DTIC Science & Technology

    phase Ge-IV with the body centered cubic structure . The triple point between Ge-I (diamond structure), Ge-III (body centered tetragonal) and Ge-IV (body...Another new phase with the simple cubic structure has been detected for the first time although its relations to the other polymorphs of germanium has

  11. Smooth germanium nanowires prepared by a hydrothermal deposition process

    SciTech Connect

    Pei, L.Z.; Zhao, H.S.; Tan, W.; Yu, H.Y.; Chen, Y.W.; Fan, C.G.; Zhang, Qian-Feng

    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.

  12. Dreams and Reality of Using Naked Ge Detectors in Liquid Nitrogen Status (Long-Term Stability) of GENIUS-TF

    NASA Astrophysics Data System (ADS)

    Krivosheina, Irina V.; Klapdor-Kleingrothaus, Hans V.

    2008-04-01

    GENIUS-TF-II is a setup of six naked high purity Ge detectors (15 kg) in liquid nitrogen in Gran Sasso. It has been installed in October, 2004 - after the first four naked Ge detectors had been installed on May 5, 2003 (GENIUS-TF-I). The GENIUS-Test-Facility (GENIUS-TF) is the first and up to now only setup ever testing the novel technique aiming at extreme background reduction in search for rare decays in particular underground. The goal of GENIUS-TF was to test some key operational parameters of the full GENIUS project in 1997.1-6 Simultaneous physical goal was to search for the annual modulation of the Dark Matter signal.12,25 After operation of GENIUS-TF over three years with finally six naked Ge detectors (15 kg) in liquid nitrogen in Gran Sasso we realize serious problems for realization of a full-size GENIUS-like experiment: 1. Background from 222Rn diffusing into the setup, on a level far beyond the expectation. 2. Limited long-term stability of naked detectors in liquid nitrogen as result of increasing leakage current. None of the six detectors is running after three years with the nominal leakage current. Three of the six detectors do not work any more at all. The results of our three years of investigation of the long-term stability casts serious doubt on the possibility to perform a full GENIUS project - or its copies GERDA or CAMEO/GEM.

  13. Silicon Germanium (SiGe) Radioisotope Thermoelectric Generator (RTG) Program for space missions. Fifteenth technical progress report, August 1-31, 1980

    SciTech Connect

    Whitmore, C. W.; Silverman, G.

    1980-01-01

    This program consists of the following three tasks: Multi-Hundred Watt RTG for the Galileo Probe Mission; Reestablishment of Silicon Germanium Unicouple Capability; and General Purpose Heat Source RTG for the International Solar Polar and Galileo Orbiter Missions. Details of program progress for each task, including a milestone schedule and a discussion of current problem areas (if any) are presented.

  14. Reducing 68Ge Background in Dark Matter Experiments

    SciTech Connect

    Kouzes, Richard T.; Orrell, John L.

    2011-03-01

    Experimental searches for dark matter include experiments with sub-0.5 keV-energy threshold high purity germanium detectors. Experimental efforts, in partnership with the CoGeNT Collaboration operating at the Soudan Underground Laboratory, are focusing on energy threshold reduction via noise abatement, reduction of backgrounds from cosmic ray generated isotopes, and ubiquitous environmental radioactive sources. The most significant cosmic ray produced radionuclide is 68Ge. This paper evaluates reducing this background by freshly mining and processing germanium ore. The most probable outcome is a reduction of the background by a factor of two, and at most a factor of four. A very cost effective alternative is to obtain processed Ge as soon as possible and store it underground for 18 months.

  15. Rhenium-germanium triple bonds: syntheses and reactions of the germylidyne complexes mer-[X2(PMe3)3Re≡Ge-R] (X=Cl, I, H; R=m-terphenyl).

    PubMed

    Filippou, Alexander C; Chakraborty, Uttam; Schnakenburg, Gregor

    2013-04-26

    A general approach to the first compounds that contain rhenium-germanium triple and double bonds is reported. Heating [ReCl(PMe3)5] (1) with the arylgermanium(II) chloride GeCl(C6H3-2,6-Trip2) (2; Trip=2,4,6-triisopropylphenyl) results in the germylidyne complex mer-[Cl2 (PMe3)3Re≡Ge-C6H3-2,6-Trip2] (4) upon PMe3 elimination. An equilibrium that is dependent on the PMe3 concentration exists between complexes 1 and 4. Removal of the volatile PMe3 shifts the equilibrium towards complex 4, whereas treatment of 4 with an excess of PMe3 gives a 1:1 mixture of 1 and the PMe3 adduct of 2, GeCl(C6H3-2,6-Trip2)(PMe3) (2-PMe3). Adduct 2-PMe3 can be selectively obtained by addition of PMe3 to chlorogermylidene 2. The NMR spectroscopic data for 2-PMe3 indicate an equilibrium between 2-PMe3 and its dissociation products, 2 and PMe3 , which is shifted far towards the adduct site at ambient temperature. NMR spectroscopic monitoring of the reaction of complex 1 with 2 and the reaction of complex 4 with PMe3 revealed the formation of two key intermediates, which were identified to be the chlorogermylidene complexes cis/trans-[Cl(PMe3)4 Re=Ge(Cl)C6H3-2,6-Trip2] (cis/trans-3) by using NMR spectroscopy. Labile chlorogermylidene complexes cis/trans-3 can be also generated from trans-[Cl(PMe3)4 Re≡Ge-C6H3-2,6-Trip2]BPh4 (9) and (nBu4N)Cl at low temperature, and decompose at ambient temperature to give a mixture of complexes 1 and 4. Complex 4 reacts with LiI to give the diiodido derivative mer-[I2(PMe3)3Re≡Ge-C6H3-2,6-Trip2] (5), which undergoes a metathetical iodide/hydride exchange with Na(BEt3H) to give the dihydrido germylidyne complex mer-[H2(PMe3)3Re≡Ge-C6H3-2,6-Trip2] (6). Carbonylation of 4 induces a chloride migration from rhenium to the germanium atom to afford the chlorogermylidene complex mer-[Cl(CO)(PMe3)3Re=Ge(Cl)C6H3-2,6-Trip2] (7). Similarly, MeNC converts complex 4 into the methylisocyanide analogue mer-[Cl(MeNC)(PMe3)3Re=Ge(Cl)C6H3-2,6-Trip2] (8). Chloride

  16. Radiation detectors based on laser sintered Bi 4Ge 3O 12 ceramics

    NASA Astrophysics Data System (ADS)

    Macedo, Zélia Soares; da Silva, Ronaldo Santos; Valerio, Mário Ernesto Giroldo; Hernandes, Antonio Carlos

    2004-06-01

    Laser sintered bismuth germanate (Bi 4Ge 3O 12) ceramics were investigated from the point of view of its potential use in radiation detector devices. The light output, density of trap centers and radiation damage were comparatively discussed for laser sintered ceramic, conventional ceramic and single crystal. The scintillator efficiency of the laser sintered ceramics was 13% higher than that observed for furnace sintered ceramics and the radiation damage levels were the same for both samples up to a dose of 3200 Gy of β radiation. The thermoluminescence results of the samples irradiated with UV and β-rays provided strong indicatives that the inter-grain defects have the same nature of the bulk defects and do not contribute with new traps in the temperature range studied. Furthermore, the density of trapping centers in the laser sintered material was 50% lower than in the conventionally sintered ceramics.

  17. Performance of multiplexed Ge:Ga detector arrays in the far infrared

    NASA Technical Reports Server (NTRS)

    Farhoomand, Jam; Mccreight, Craig

    1990-01-01

    The performance of two multi-element, multiplexed Ge:Ga linear arrays under low-background conditions was investigated. The on-focal switching is accomplished by MOSFET switches, and the integrated charge is made available through MOSFET source followers. The tests were conducted at 106 microns, and the radiation on the detectors was confined to a spectral window 1.25 microns wide using a stack of cold filters. At 4.2 K, the highest responsivity was 584 A/W, the noise equivalent power was 1.0 x 10(exp -16) W/square root of Hz, and the read noise was 6100 electrons/sample. A detailed description of the test setup and procedure is presented.

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

    PubMed

    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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Precision half-life measurement of 140La with Ge-detector

    NASA Astrophysics Data System (ADS)

    Adam, J.; Belov, A. G.; Brandt, R.; Chaloun, P.; Honusek, M.; Kalinnikov, V. G.; Krivopustov, M. I.; Kulakov, B. A.; Langrock, E.-J.; Pronskikh, V. S.; Sosnin, A. N.; Stegailov, V. I.; Tsoupko-Sitnikov, V. M.; Wan, J.-S.; Westmeier, W.

    2002-03-01

    Half-life is one of the fundamental properties of radioactive nuclei, and the precision required for its numerous applications in modern physics sometimes approaches the level of 10 -4-10 -5. Most part of the T1/2 measurements performed up to now was made with proportional chambers, and the results were sometimes hardly reproducible within the error limits. Using Ge-detectors for that purpose brought some significant advantages but electronic unit related effects and spectra analysis procedures still remain the sources of the errors influencing the accuracy of the T1/2 attained. In this work, 140La samples were obtained in the 139La( n, γ) 140La reaction, employing a microtron as a neutron source and the half-life measurements were performed with a HPGe-detector. Influencing factors such as photopeak and background shape, electronic circuitry dead time and deadtime variations during the measurements, as well as pulse pileup are studied altogether. Values of the 140La T1/2=1.6808(18) d, λ=0.47749(20)×10 -5, agreeing within the uncertainities with the most accurate evaluated ones ( T1/2=1.6781(3) d, λ=0.47807(9)×10 -5) [2] were obtained in two series of measurements.

  20. Mathematical calibration of Ge detectors, and the instruments that use them

    SciTech Connect

    Bronson, F.L.; Young, B.

    1997-11-01

    Efficiency calibrations for Ge detectors are typically done with the use of multiple energy calibrations sources which are added to a bulk matrix intended to simulate the measurement sample, and then deposited in the sample container. This is rather easy for common laboratory samples. Bu, even there, for many environmental samples, waste assay samples, and operational health physics samples, accurate calibrations are difficult. For these situations, various mathematical corrections or direct calibration techniques are used at Canberra. EML has pioneered the use of mathematical calibrations following source-based detector characterization measurements for in situ measurements of environmental fallout. Canberra has expanded this by the use of MCNP for the source measurements required in EML. For other calibration situations, MCNP was used directly, as the primary calibration method. This is demonstrated to be at least as accurate as source based measurements, and probably better. Recently, a new method [ISOCS] has been developed and is nearing completion. This promises to be an easy to use calibration software that can be used by the customer for in situ gamma spectroscopy to accurately measure many large sized samples, such as boxes, drums, pipes, or to calibrate small laboratory-type samples. 8 refs., 8 figs., 5 tabs.

  1. Developing robust fabrication of silicon/silicon-germanium quantum dots with integrated RF-SET charge detectors

    NASA Astrophysics Data System (ADS)

    Gilheart, Timothy John

    Solid-state approaches to quantum computing include quantum dot qubit implementations based on the Loss-DiVincenzo proposal. Prior work in GaAs two-dimensional electron gas (2DEG) materials serves as a proving ground for device designs that can be ported to Si/SiGe 2DEG systems, where the coherence time of quantum information is longer due to a combination of physical effects unique to strained Si quantum wells. In spite of the promise of Si/SiGe quantum dot qubits, several materials issues can reduce successful device yield. This work presents results from the exploration of two of these issues: the reliability of ohmic contacts to the 2DEG and the leakage current from the metallic Schottky gates used to form the quantum dots. For the ohmic contacts, growth recipes with yields approaching 100% based on two different metallizations, Au/Sb and Ag/Sb, are presented in the context of a known model for diffusion and alloying in Si. Addressing the issue of leakage currents, experiments on devices fabricated at Dartmouth strongly suggest that the major source of current leakage arises from the region near the etched mesa sidewall, where the photolithographically created metallic Schottky gate leads cover the edge of the device mesa. The solution presented here involves the deposition of SiO2 as a barrier oxide between the gate metallization and the underlying etched region to block whatever current paths might exist between the edge of the mesa and the 2DEG. Two variations on this theme are discussed: the deposition of oxide beneath the large gate leads only and the deposition of oxide immediately after etching to partially backfill the etched region with insulator. Results suggest that the latter method holds the most promise and may work even better with more robust insulators. Finally, the results of several successful devices are presented, including an radio-frequency single-electron transistor on Si/SiGe 2DEG material and a quantum dot formed in a Si/SiGe 2DEG

  2. Possibilities for LWIR detectors using MBE-grown Si(/Si(1-x)Ge(x) structures

    NASA Technical Reports Server (NTRS)

    Hauenstein, Robert J.; Miles, Richard H.; Young, Mary H.

    1990-01-01

    Traditionally, long wavelength infrared (LWIR) detection in Si-based structures has involved either extrinsic Si or Si/metal Schottky barrier devices. Molecular beam epitaxially (MBE) grown Si and Si/Si(1-x)Ge(x) heterostructures offer new possibilities for LWIR detection, including sensors based on intersubband transitions as well as improved conventional devices. The improvement in doping profile control of MBE in comparison with conventional chemical vapor deposited (CVD) Si films has resulted in the successful growth of extrinsic Si:Ga, blocked impurity-band conduction detectors. These structures exhibit a highly abrupt step change in dopant profile between detecting and blocking layers which is extremely difficult or impossible to achieve through conventional epitaxial growth techniques. Through alloying Si with Ge, Schottky barrier infrared detectors are possible, with barrier height values between those involving pure Si or Ge semiconducting materials alone. For both n-type and p-type structures, strain effects can split the band edges, thereby splitting the Schottky threshold and altering the spectral response. Measurements of photoresponse of n-type Au/Si(1-x)Ge(x) Schottky barriers demonstrate this effect. For intersubband multiquntum well (MQW) LWIR detection, Si(1-x)Ge(x)/Si detectors grown on Si substrates promise comparable absorption coefficients to that of the Ga(Al)As system while in addition offering the fundamental advantage of response to normally incident light as well as the practical advantage of Si-compatibility. Researchers grew Si(1-x)Ge(x)/Si MQW structures aimed at sensitivity to IR in the 8 to 12 micron region and longer, guided by recent theoretical work. Preliminary measurements of n- and p-type Si(1-x)Ge(x)/Si MQW structures are given.

  3. Self-organized growth of germanium nanocolumns

    NASA Astrophysics Data System (ADS)

    Mussabek, G. K.; Yermukhamed, D.; Dikhanbayev, K. K.; Schleusener, A.; Mathur, S.; Sivakov, V.

    2017-03-01

    The crystalline germanium nanostructures were obtained on a silicon surface by the chemical vapor deposition technique using a germanium (IV) iso-propoxide ([Ge(OiPr)4]) metalorganic precursor as a germanium source. As was observed, the one-dimensional (1D) germanium nanostructures on the silicon surface form without using a metal catalyst, meaning that the formation of 1D nanostructures is based not on a vapor-liquid-solid (VLS) growth mechanism, but on self-organization processes which take place on the silicon surfaces during the CVD process of germanium iso-propoxide pyrolysis. Our observation suggests that the non-catalytic growth of germanium nanocolumns is strongly dependent on the CVD process temperature. The germanium phase composition and morphology have been investigated by x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS), and high resolution scanning electron microscopy (HRSEM), respectively. Our results provide a new way to grow 1D germanium nanostructures without contamination by a catalyst, which the vapor-liquid-solid growth mechanism is known to cause, allowing for the application of such materials in micro- and optoelectronics.

  4. Results from a Search for Light-Mass Dark Matter with a P-type Point Contact Germanium Detector

    SciTech Connect

    Aalseth, Craig E.; Barbeau, Phil; Bowden, N. S.; Cabrera-Palmer, B.; Colaresi, J.; Collar, J. I.; Dazeley, S.; de Lurgio, P.; Fast, James E.; Fields, N.; Greenberg, C.; Hossbach, Todd W.; Keillor, Martin E.; Kephart, Jeremy D.; Marino, Michael G.; Miley, Harry S.; Miller, M. L.; Orrell, John L.; Radford, D. C.; Reyna, D.; Tench, O.; Van Wechel, T. D.; Wilkerson, J.; Yocum, K. M.

    2011-03-01

    We report on several features present in the energy spectrum from an ultra low-noise geranium detector operated at 2,100 m.w.e. By implementing a new technique able to reject surface events, a number of cosmogenic peaks can be observed for the first time. We discuss several possible causes for an irreducible excess of bulk-like events below 3 keVee, including a dark matter candidate common to the DAMA/LIBRA annual modulation effect, the hint of a signal in CDMS, and phenomenological predictions. Improved constraints are placed on a cosmological origin for the DAMA/LIBRA effect.

  5. Germananes: Germanium Graphane Analogues

    NASA Astrophysics Data System (ADS)

    Goldberger, Joshua

    2014-03-01

    Graphene's success has shown that it is not only possible to create stable, single-atom thick sheets from a crystalline solid, but that these materials have fundamentally different properties than the parent material. Our interest focuses on the synthesis and properties of Group IV graphane analogues. We have synthesized for the first time, mm-scale crystals of a hydrogen-terminated germanium multilayered graphane analogue (germanane, GeH) from the topochemical deintercalation of CaGe2. This layered van der Waals solid is analogous to multilayered graphane. The surface layer of GeH only slowly oxidizes in air over the span of five months, while the underlying layers are resilient to oxidation. We demonstrate that it is possible to covalently terminate the external surface with organic substituents to tune the electronic structure, and enhance the stability. These materials represent a new class of covalently terminated graphane analogues having great potential for a wide range of optoelectronic and sensing applications, especially since theory predicts a direct band gap of 1.53 eV and an electron mobility of 18,000 cm2/Vs which is five times higher than that of bulk Ge.

  6. Silicon germanium semiconductive alloy and method of fabricating same

    NASA Technical Reports Server (NTRS)

    Park, Yeonjoon (Inventor); Choi, Sang H. (Inventor); King, Glen C. (Inventor)

    2008-01-01

    A silicon germanium (SiGe) semiconductive alloy is grown on a substrate of single crystalline Al.sub.2O.sub.3. A {111} crystal plane of a cubic diamond structure SiGe is grown on the substrate's {0001} C-plane such that a <110> orientation of the cubic diamond structure SiGe is aligned with a <1,0,-1,0> orientation of the {0001} C-plane. A lattice match between the substrate and the SiGe is achieved by using a SiGe composition that is 0.7223 atomic percent silicon and 0.2777 atomic percent germanium.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  8. Germanium multiphase equation of state

    SciTech Connect

    Crockett, Scott D.; Lorenzi-Venneri, Giulia De; Kress, Joel D.; Rudin, Sven P.

    2014-05-07

    A new SESAME multiphase germanium equation of state (EOS) has been developed using 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

  9. Germanium multiphase equation of state

    DOE PAGES

    Crockett, Scott D.; Lorenzi-Venneri, Giulia De; Kress, Joel D.; ...

    2014-05-07

    A new SESAME multiphase germanium equation of state (EOS) has been developed using 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

  10. Germanium multiphase equation of state

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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.

  12. Measurement and simulation of boron diffusion in strained Si 1- xGe x epitaxial layers with a linearly graded germanium profile

    NASA Astrophysics Data System (ADS)

    Rajendran, K.; Schoenmaker, W.

    2001-11-01

    The diffusion of boron in compressively strained Si 1- xGe x epitaxial layers with graded Ge profiles grown by rapid pressure chemical vapor deposition during furnace and rapid thermal annealing has been studied. Comparison of the Si 1- xGe x samples to Si samples after furnace annealing (FA) and rapid thermal annealing (RTA) revealed a retarded B diffusion inside the strained Si 1- xGe x layer. FA after RTA has only a marginal effect on B diffusion. The extracted B diffusivity from the present studies is very well comparable with available experimental and simulation results. A simple empirical expression for B diffusion is presented and incorporated into a diffusion model for dopants in heterostructures. Good agreement between the measured and simulated diffusivity is observed. It is argued that B diffusion in strained Si 1- xGe x layers requires the inclusion of both trapping effect and strain in the formulation of the diffusion mechanism.

  13. SuperTIGER scintillator detector calibration with 30 GeV/nucleon Pb and its fragments

    NASA Astrophysics Data System (ADS)

    Sasaki, Makoto

    2016-07-01

    The SuperTIGER (Super Trans-Iron Galactic Element Recorder) long-duration balloon instrument has measured the abundances of galactic cosmic-ray elements to provide sensitive tests and clarification of the OB-association model of Galactic cosmic-ray origins. More than 600 nuclei with atomic number Z > 30 were observed on its first flight and the abundances of nuclei have been determined with clear individual element resolution and high statistical precision for 30 <= Z <= 40. From November 25 to December 01, 2015, a beamtest was carried out at CERN with fixed energy 30 GeV/nucleon Pb and its fragments to measure the saturation response of the scintillator detectors, which are essential to determine the abundances of nuclei with atomic number Z > 40. The beamtest results have been used to optimize the Geant4 simulation to represent the flight data, and will be used to interpret the flight data to extend the abundance determination to about _{60}Nd. SuperTIGER was developed by Washington University in St. Louis, NASA Goddard Flight Center, the California Institute of Technology, Jet Propulsion Laboratory, and the University of Minnesota.

  14. Modeling the detection efficiency of an HP-Ge detector for use in boron neutron capture therapy.

    PubMed

    Nakamura, Satoshi; Wakita, Akihisa; Ito, Masashi; Okamoto, Hiroyuki; Nishioka, Shie; Iijima, Kotaro; Kobayashi, Kazuma; Nishio, Teiji; Igaki, Hiroshi; Itami, Jun

    2017-07-01

    The multi-foil method is commonly used to determine upon an energy spectrum of neutrons in boron neutron capture therapy. The method requires to measure the radioactivation of the foils. This study develops a simple modeling procedure of a high-purity Ge detector, which is used to measure the radioactivation, in order to calculate the detection efficiency with GEANT4. By changing four parameters from their manufacturing specifications of the detector, the simulated detection efficiency is able to reproduce the actual detection efficiency. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Strangeness in Au+Au collisions at √sNN = 130 GeV observed with the STAR detector

    NASA Astrophysics Data System (ADS)

    Barnby, Lee S.; STAR Collaboration; Adler, C.; Ahammed, Z.; Allgower, C.; Amonett, J.; Anderson, B. D.; Anderson, M.; Averichev, G. S.; Balewski, J.; Barannikova, O.; Barnby, L. S.; Baudot, J.; Bekele, S.; Belaga, V. V.; Bellwied, R.; Berger, J.; Bichsel, H.; Bland, L. C.; Blyth, C. O.; Bonner, B. E.; Boucham, A.; Brandin, A.; Cadman, R. V.; Caines, H.; Calderón de la Barca Sánchez, M.; Cardenas, A.; Carroll, J.; Castillo, J.; Castro, M.; Cebra, D.; Chattopadhyay, S.; Chen, M. L.; Chen, Y.; Chernenko, S. P.; Cherney, M.; Chikanian, A.; Choi, B.; Christie, W.; Coffin, J. P.; Cormier, T. M.; Cramer, J. G.; Crawford, H. J.; Deng, W. S.; Derevschikov, A. A.; Didenko, L.; Draper, J. E.; Dunin, V. B.; Dunlop, J. C.; Eckardt, V.; Efimov, L. G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Fachini, P.; Faine, V.; Filimonov, K.; Finch, E.; Fisyak, Y.; Flierl, D.; Foley, K. J.; Fu, J.; Gagliardi, C. A.; Gagunashvili, N.; Gans, J.; Gaudichet, L.; Germain, M.; Geurts, F.; Ghazikhanian, V.; Grabski, J.; Grachov, O.; Grigoriev, V.; Guedon, M.; Gushin, E.; Hallman, T. J.; Hardtke, D.; Harris, J. W.; Heffner, M.; Heppelmann, S.; Herston, T.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G. W.; Horsley, M.; Huang, H. Z.; Humanic, T. J.; Hümmler, H.; Igo, G.; Ishihara, A.; Ivanshin, Yu. I.; Jacobs, P.; Jacobs, W. W.; Janik, M.; Johnson, I.; Jones, P. G.; Judd, E. G.; Kaneta, M.; Kaplan, M.; Keane, D.; Kiryluk, J.; Kisiel, A.; Klay, J.; Klein, S. R.; Klyachko, A.; Konstantinov, A. S.; Kotchenda, L.; Kovalenko, A. D.; Kramer, M.; Kravtsov, P.; Krueger, K.; Kuhn, C.; Kulikov, A. I.; Kunde, G. J.; Kunz, C. L.; Kutuev, R. Kh.; Kuznetsov, A. A.; Lakehal-Ayat, L.; Lamont, M. A. C.; Landgraf, J. M.; Lange, S.; Lansdell, C. P.; Lasiuk, B.; Laue, F.; Lebedev, A.; Lednický, R.; Leontiev, V. M.; LeVine, M. J.; Li, Q.; Lindenbaum, S. J.; Lisa, M. A.; Liu, F.; Liu, L.; Liu, Z.; Liu, Q. J.; Ljubicic, T.; Llope, W. J.; Curto, G. Lo; Long, H.; Longacre, R. S.; Lopez-Noriega, M.; Love, W. A.; Lynn, D.; Majka, R.; Margetis, S.; Markert, C.; Martin, L.; Marx, J.; Matis, H. S.; Matulenko, Yu. A.; McShane, T. S.; Meissner, F.; Melnick, Yu.; Meschanin, A.; Messer, M.; Miller, M. L.; Milosevich, Z.; Minaev, N. G.; Mitchell, J.; Moiseenko, V. A.; Moore, C. F.; Morozov, V.; de Moura, M. M.; Munhoz, M. G.; Nelson, J. M.; Nevski, P.; Nikitin, V. A.; Nogach, L. V.; Norman, B.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Okorokov, V.; Oldenburg, M.; Olson, D.; Paic, G.; Pandey, S. U.; Panebratsev, Y.; Panitkin, S. Y.; Pavlinov, A. I.; Pawlak, T.; Perevoztchikov, V.; Peryt, W.; Petrov, V. A.; Pluta, J.; Porile, N.; Porter, J.; Poskanzer, A. M.; Potrebenikova, E.; Prindle, D.; Pruneau, C.; Radomski, S.; Rai, G.; Ravel, O.; Ray, R. L.; Razin, S. V.; Reichhold, D.; Reid, J. G.; Retiere, F.; Ridiger, A.; Ritter, H. G.; Roberts, J. B.; Rogachevski, O. V.; Romero, J. L.; Roy, C.; Rykov, V.; Sakrejda, I.; Sandweiss, J.; Saulys, A. C.; Savin, I.; Schambach, J.; Scharenberg, R. P.; Schmitz, N.; Schroeder, L. S.; Schüttauf, A.; Schweda, K.; Seger, J.; Seliverstov, D.; Seyboth, P.; Shahaliev, E.; Shestermanov, K. E.; Shimanskii, S. S.; Shvetcov, V. S.; Skoro, G.; Smirnov, N.; Snellings, R.; Sorensen, P.; Sowinski, J.; Spinka, H. M.; Srivastava, B.; Stephenson, E. J.; Stock, R.; Stolpovsky, A.; Strikhanov, M.; Stringfellow, B.; Struck, C.; Suaide, A. A. P.; Sugarbaker, E.; Suire, C.; umbera, M.; Symons, T. J. M.; Szanto de Toledo, A.; Szarwas, P.; Tai, A.; Takahashi, J.; Tang, A. H.; Thomas, J. H.; Thompson, M.; Tikhomirov, V.; Tokarev, M.; Tonjes, M. B.; Trainor, T. A.; Trentalange, S.; Tribble, R. E.; Trofimov, V.; Tsai, O.; Turner, K.; Ullrich, T.; Underwood, D. G.; Van Buren, G.; Vander Molen, A. M.; Vasilevski, I. M.; Vasiliev, A. N.; Vigdor, S. E.; Voloshin, S. A.; Wang, F.; Ward, H.; Watson, J. W.; Wells, R.; Wenaus, T.; Westfall, G. D.; Whitten, C., Jr.; Wieman, H.; Willson, R.; Wissink, S. W.; Witt, R.; Wood, J.; Xu, N.; Xu, Z.; Yakutin, A. E.; Yamamoto, E.; Yang, J.; Yepes, P.; Yurevich, V. I.; Zanevski, Y. V.; Zborovský, I.; Zhang, H.; Zhang, W. M.; Zoulkarneev, R.; Zubarev, A. N.

    2002-07-01

    The STAR detector has made a variety of measurements of strange and other hadronic species in Au+Au collisions at √sNN = 130 GeV. A comparison of kaon and pion production enables an examination of the systematics of strangeness production with energy by comparing them to lower energy collisions. Anti-baryon to baryon ratios indicate a much reduced net-baryon density and transverse momentum spectra show that a picture of transverse expansion seems appropriate.

  16. Measurement of R between 1.84 and 3.05 GeV at the KEDR detector

    NASA Astrophysics Data System (ADS)

    Anashin, V. V.; Aulchenko, V. M.; Baldin, E. M.; Barladyan, A. K.; Barnyakov, A. Yu.; Barnyakov, M. Yu.; Baru, S. E.; Basok, I. Yu.; Batrakov, A. M.; Blinov, A. E.; Blinov, V. E.; Bobrov, A. V.; Bobrovnikov, V. S.; Bogomyagkov, A. V.; Bondar, A. E.; Buzykaev, A. R.; Eidelman, S. I.; Grigoriev, D. N.; Glukhovchenko, Yu. M.; Karnaev, S. E.; Karpov, G. V.; Karpov, S. V.; Kasyanenko, P. V.; Kharlamova, T. A.; Kiselev, V. A.; Kolmogorov, V. V.; Kononov, S. A.; Kotov, K. Yu.; Kravchenko, E. A.; Kudryavtsev, V. N.; Kulikov, V. F.; Kurkin, G. Ya.; Kuyanov, I. A.; Kuper, E. A.; Levichev, E. B.; Maksimov, D. A.; Malyshev, V. M.; Maslennikov, A. L.; Meshkov, O. I.; Mishnev, S. I.; Morozov, I. I.; Muchnoi, N. Yu.; Neufeld, V. V.; Nikitin, S. A.; Nikolaev, I. B.; Okunev, I. N.; Onuchin, A. P.; Oreshkin, S. B.; Osipov, A. A.; Ovtin, I. V.; Peleganchuk, S. V.; Pivovarov, S. G.; Piminov, P. A.; Petrov, V. V.; Prisekin, V. G.; Rezanova, O. L.; Ruban, A. A.; Sandyrev, V. K.; Savinov, G. A.; Shamov, A. G.; Shatilov, D. N.; Shwartz, B. A.; Simonov, E. A.; Sinyatkin, S. V.; Skrinsky, A. N.; Sokolov, A. V.; Sukharev, A. M.; Starostina, E. V.; Talyshev, A. A.; Tayursky, V. A.; Telnov, V. I.; Tikhonov, Yu. A.; Todyshev, K. Yu.; Tumaikin, G. M.; Usov, Yu. V.; Vorobiov, A. I.; Zhilich, V. N.; Zhulanov, V. V.; Zhuravlev, A. N.

    2017-07-01

    Using the KEDR detector at the VEPP-4M e+e- collider, we have determined the values of R at thirteen points of the center-of-mass energy between 1.84 and 3.05 GeV. The achieved accuracy is about or better than 3.9% at most of the energy points with a systematic uncertainty less than 2.4%.

  17. Large-volume ultralow background germanium-germanium coincidence/anticoincidence gamma-ray spectrometer

    SciTech Connect

    Brodzinski, R.L.; Brown, D.P.; Evans, J.C. Jr.; Hensley, W.K.; Reeves, J.H.; Wogman, N.A.; Avignone, F.T. III; Miley, H.S.; Moore, R.S.

    1984-03-01

    A large volume (approx. 1440 cm/sup 3/), multicrystal, high resolution intrinsic germanium gamma-ray spectrometer has been designed based on 3 generations of experiments. The background from construction materials used in standard commercial configurations has been reduced by at least two orders of magnitude. Data taken with a 132 cm/sup 3/ prototype detector, installed in the Homestake Gold Mine, are presented. The first application of the full scale detector will be an ultrasensitive search for neutrinoless and two-neutrino double beta decay of /sup 76/Ge. The size and geometrical configuration of the crystals is chosen to optimize detection of double decay to the first excited state of /sup 76/Se with subsequent emission of a 559 keV gamma ray. The detector will be sufficiently sensitive for measuring the neutrinoless double beta decay to the ground state to establish a minimum half life of 1.4.10/sup 24/ y. Application of the large spectrometer system to the analysis of low level environmental and biological samples is discussed.

  18. Multilayers Diamond-Like Carbon Film with Germanium Buffer Layers by Pulsed Laser Deposition

    NASA Astrophysics Data System (ADS)

    Cheng, Y.; Lu, Y. M.; Guo, Y. L.; Huang, G. J.; Wang, S. Y.; Tian, F. T.

    Multilayer diamond-like carbon film with germanium buffer layers, which was composed of several thick DLC layers and thin germanium island “layers” and named as Ge-DLC film, was prepared on the germanium substrate by ultraviolet laser. The Ge-DLC film had almost same surface roughness as the pure DLC film. Hardness of the Ge-DLC film was above 48.1GPa, which was almost the same as that of pure DLC film. Meanwhile, compared to the pure DLC film, the critical load of Ge-DLC film on the germanium substrate increased from 81.6mN to 143.8mN. Moreover, Ge-DLC film on germanium substrates had no change after fastness tests. The results showed that Ge-DLC film not only kept high hardness but also had higher critical load than that of pure DLC film. Therefore, it could be used as practical protective films.

  19. Monolayer graphene/germanium Schottky junction as high-performance self-driven infrared light photodetector.

    PubMed

    Zeng, Long-Hui; Wang, Ming-Zheng; Hu, Han; Nie, Biao; Yu, Yong-Qiang; Wu, Chun-Yan; Wang, Li; Hu, Ji-Gang; Xie, Chao; Liang, Feng-Xia; Luo, Lin-Bao

    2013-10-09

    We report on the simple fabrication of monolayer graphene (MLG)/germanium (Ge) heterojunction for infrared (IR) light sensing. It is found that the as-fabricated Schottky junction detector exhibits obvious photovoltaic characteristics, and is sensitive to IR light with high Ilight/Idark ratio of 2 × 10(4) at zero bias voltage. The responsivity and detectivity are as high as 51.8 mA W(-1) and 1.38 × 10(10) cm Hz(1/2) W(-1), respectively. Further photoresponse study reveals that the photovoltaic IR detector displays excellent spectral selectivity with peak sensitivity at 1400 nm, and a fast light response speed of microsecond rise/fall time with good reproducibility and long-term stability. The generality of the above results suggests that the present MLG/Ge IR photodetector would have great potential for future optoelectronic device applications.

  20. Near-infrared emission from mesoporous crystalline germanium

    SciTech Connect

    Boucherif, Abderraouf; Aimez, Vincent; Arès, Richard; Korinek, Andreas

    2014-10-15

    Mesoporous crystalline germanium was fabricated by bipolar electrochemical etching of Ge wafer in HF-based electrolyte. It yields uniform mesoporous germanium layers composed of high density of crystallites with an average size 5-7 nm. Subsequent extended chemical etching allows tuning of crystallites size while preserving the same chemical composition. This highly controllable nanostructure exhibits photoluminescence emission above the bulk Ge bandgap, in the near-infrared range (1095-1360nm) with strong evidence of quantum confinement within the crystallites.

  1. Near-infrared emission from mesoporous crystalline germanium

    NASA Astrophysics Data System (ADS)

    Boucherif, Abderraouf; Korinek, Andreas; Aimez, Vincent; Arès, Richard

    2014-10-01

    Mesoporous crystalline germanium was fabricated by bipolar electrochemical etching of Ge wafer in HF-based electrolyte. It yields uniform mesoporous germanium layers composed of high density of crystallites with an average size 5-7 nm. Subsequent extended chemical etching allows tuning of crystallites size while preserving the same chemical composition. This highly controllable nanostructure exhibits photoluminescence emission above the bulk Ge bandgap, in the near-infrared range (1095-1360nm) with strong evidence of quantum confinement within the crystallites.

  2. The Constellation-X Focal Plane Microcalorimeter Array: An NTD-Germanium Solution

    NASA Technical Reports Server (NTRS)

    Beeman, J.; Silver, E.; Bandler, S.; Schnopper, H.; Murray, S.; Madden, N.; Landis, D.; Haller, E. E.; Barbera, M.

    2001-01-01

    The hallmarks of Neutron Transmutation Doped (NTD) germanium cryogenic thermistors include high reliability, reproducibility, and long term stability of bulk carrier transport properties. Using micro-machined NTD Ge thermistors with integral 'flying' leads, we can now fabricate two-dimensional arrays that are built up from a series of stacked linear arrays. We believe that this modular approach of building, assembling, and perhaps replacing individual modules of detectors is essential to the successful fabrication and testing of large multi-element instruments. Details of construction are presented.

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

    SciTech Connect

    Ahmed, Z.; Akerib, D.S.; Arrenberg, S.; Bailey, C.N.; Balakishiyeva, D.; Baudis, L.; Bauer, D.A.; Brink, P.L.; Bruch, T.; Bunker, R.; Cabrera, B.; /Stanford U., Phys. Dept. /UC, Santa Barbara

    2010-11-01

    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 {approx}10 GeV/c{sup 2}. This analysis provides stronger constraints than previous CDMS II results for WIMP masses below 9 GeV/c{sup 2} and excludes parameter space associated with possible low-mass WIMP signals from the DAMA/LIBRA and CoGeNT experiments.

  4. Results from a low-energy analysis of the CDMS II germanium data.

    PubMed

    Ahmed, Z; Akerib, D S; 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; do Couto e Silva, E; Cushman, P; Daal, M; DeJongh, F; Di Stefano, P; Dragowsky, M R; Duong, L; Fallows, S; Figueroa-Feliciano, E; Filippini, J; Fox, 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; Liu, S; 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; Resch, R; 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

    2011-04-01

    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.

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

    SciTech Connect

    Ahmed, Z.; Filippini, J.; Golwala, S. R.; Moore, D.; Akerib, D. S.; Bailey, C. N.; Dragowsky, M. R.; Hennings-Yeomans, R.; Arrenberg, S.; Baudis, L.; Bruch, T.; Tarka, M.; Balakishiyeva, D.; Saab, T.; Bauer, D. A.; DeJongh, F.; Hall, J.; Holmgren, D.; Hsu, L.; Ramberg, E.

    2011-04-01

    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 {approx}10 GeV/c{sup 2}. This analysis provides stronger constraints than previous CDMS II results for WIMP masses below 9 GeV/c{sup 2} and excludes parameter space associated with possible low-mass WIMP signals from the DAMA/LIBRA and CoGeNT experiments.

  6. Germanium Nanocrystal Solar Cells

    NASA Astrophysics Data System (ADS)

    Holman, Zachary Charles

    Greenhouse gas concentrations in the atmosphere are approaching historically unprecedented levels from burning fossil fuels to meet the ever-increasing world energy demand. A rapid transition to clean energy sources is necessary to avoid the potentially catastrophic consequences of global warming. The sun provides more than enough energy to power the world, and solar cells that convert sunlight to electricity are commercially available. However, the high cost and low efficiency of current solar cells prevent their widespread implementation, and grid parity is not anticipated to be reached for at least 15 years without breakthrough technologies. Semiconductor nanocrystals (NCs) show promise for cheap multi-junction photovoltaic devices. To compete with photovoltaic materials that are currently commercially available, NCs need to be inexpensively cast into dense thin films with bulk-like electrical mobilities and absorption spectra that can be tuned by altering the NC size. The Group II-VI and IV-VI NC communities have had some success in achieving this goal by drying and then chemically treating colloidal particles, but the more abundant and less toxic Group IV NCs have proven more challenging. This thesis reports thin films of plasma-synthesized Ge NCs deposited using three different techniques, and preliminary solar cells based on these films. Germanium tetrachloride is dissociated in the presence of hydrogen in a nonthermal plasma to nucleate Ge NCs. Transmission electron microscopy and X-ray diffraction indicate that the particles are nearly monodisperse (standard deviations of 10-15% the mean particle diameter) and the mean diameter can be tuned from 4-15 nm by changing the residence time of the Ge NCs in the plasma. In the first deposition scheme, a Ge NC colloid is formed by reacting nanocrystalline powder with 1-dodecene and dispersing the functionalized NCs in a solvent. Films are then formed on substrates by drop-casting the colloid and allowing it to dry

  7. Development of doped-germanium photoconductors for astronomical observations at wavelengths from 30 to 120 micrometers

    NASA Technical Reports Server (NTRS)

    Bratt, P. R.; Lewis, N. N.

    1976-01-01

    Technology was developed for production of doped-germanium detectors which have optimized performance in the 30- to 120-micrometer wavelength range and are capable of achieving the objectives of the Infrared Astronomy Satellite space mission. The work of this phase was divided into the following major tasks: (1) growth of Ge:Ga crystals from high-purity starting material with Ga concentrations different from that previously produced, and development of a zone leveling method to produce a uniform Ga doping concentration; (2) growth of uncompensated Ge:Be crystals from high-purity starting material with a range of Be concentrations between 10 to the 14th power and 10 to the 16th power atoms/cubic cm; (3) evaluation of crystals by means of Hall effect and resistance measurements as a function of temperature; (4) fabrication and test of detectors made from both Ge:Be and Ge:Ga crystals to determine the relative performance between different crystals. Correlation of detector test data with material evaluation data and analysis of how to further optimize detector performance.

  8. Lattice dynamics and thermoelectric properties of nanocrystalline silicon-germanium alloys: Lattice dynamics and thermoelectric properties of nc Si-Ge alloys

    SciTech Connect

    Claudio, Tania; Stein, Niklas; Petermann, Nils; Stroppa, Daniel G.; Koza, Michael Marek; Wiggers, Hartmut; Klobes, Benedikt; Schierning, Gabi; Hermann, Raphaël P.

    2015-10-26

    The lattice dynamics and thermoelectric properties of sintered phosphorus-doped nanostructured silicon–germanium alloys obtained by gas-phase synthesis were studied. Measurements of the density of phonon states by inelastic neutron scattering were combined with measurements of the elastic constants and the low-temperature heat capacity. A strong influence of nanostructuring and alloying on the lattice dynamics was observed. The thermoelectric transport properties of samples with different doping as well as samples sintered at different temperature were characterized between room temperature and 1000°C. A peak figure of merit zT=0.88 at 900°C is observed and is comparatively insensitive to the aforementioned parameter variations.

  9. Verification tests of the GALLEX solar neutrino detector, with 71Ge produced in-situ from the beta-decay of 71As

    NASA Astrophysics Data System (ADS)

    GALLEX Collaboration; Hampel, W.; Handt, J.; Heusser, G.; Kaether, D.; Kiko, J.; Kirsten, T.; Laubenstein, M.; Neder, E.; Pernicka, E.; Rau, W.; Richter, H.; Rönn, U.; Schwan, U.; Wojcik, M.; Zakharov, Y.; Ammon, R. V.; Ebert, K. H.; Fritsch, T.; Heidt, D.; Henrich, E.; Stieglitz, L.; Weirich, F.; Balata, M.; Hartmann, F. X.; Bellotti, E.; Cattadori, C.; Cremonesi, O.; Ferrari, N.; Fiorini, E.; Zanotti, L.; Altmann, M.; Feilitzsch, F. V.; Mößbauer, R.; Berthomieu, G.; Schatzman, E.; Carmi, I.; Dostrovsky, I.; Bacci, C.; Belli, P.; Bernabei, R.; D'Angelo, S.; Paoluzi, L.; Cribier, M.; Rich, J.; Spiro, M.; Tao, C.; Vignaud, D.; Boger, J.; Hahn, R. L.; Rowley, J. K.; Stoenner, R. W.; Weneser, J.

    1998-09-01

    Previously, it was demonstrated that the GALLEX solar neutrino detector responds properly to low energy neutrinos, by exposing it to two intense 51Cr-neutrino sources; the recovery yield of the product 71Ge was reported to be 93%+/-8%. New experiments, in which known amounts of radioactive 71As have decayed to 71Ge in the full-scale gallium detector, strongly support this evidence. In several experiments, the gallium detector has been spiked with ~105 71As atoms, under varying conditions of how the 71As was added (either carrier free, or with Ge carrier), how the gallium solution was mixed, and how long the 71Ge remained in the gallium. 71As decays by electron capture and positron emission to 71Ge, with a half life of 2.72 d. Hot atoms are produced by these decay modes with kinematics that mimic solar neutrino capture, although the 51Cr neutrino source provided a more perfect match. This relative disadvantage is offset by the much better statistics obtainable with the 71As. In all 71As experiments, the recovery of 71Ge from the gallium was 100%, with uncertainties of only +/-1%. The combined results from the 51Cr sources and the 71As spikes rule out any loss mechanisms for 71Ge, including hot-atom chemical effects. Chemical processes in the aqueous gallium trichloride - hydrochloric acid solution guarantee that the 71Ge atoms formed in the GALLEX target will be quickly converted to extractable, volatile GeCl4.

  10. REACTIVITY OF THE GERMANIUM SURFACE: Chemical Passivation and Functionalization

    NASA Astrophysics Data System (ADS)

    Loscutoff, Paul W.; Bent, Stacey F.

    2006-05-01

    With the rapidly changing materials needs of modern microelectronics, germanium provides an opportunity for future-generation devices. Controlling germanium interfaces will be essential for this purpose. We review germanium surface reactivity, beginning with a description of the most commonly used surfaces, Ge(100) and Ge(111). An analysis of oxide formation shows why the poor oxide properties have hindered practical use of germanium to date. This is followed by an examination of alternate means of surface passivation, with particular attention given to sulfide, chloride, and hydride termination. Specific tailoring of the interface properties is possible through organic functionalization. The few solution functionalization methods that have been studied are reviewed. Vacuum functionalization has been studied to a much greater extent, with dative bonding and cycloaddition reactions emerging as principle reaction mechanisms. These are reviewed through molecular reaction studies that demonstrate the versatility of the germanium surface.

  11. Gamma-ray pulse height spectrum analysis on systems with multiple Ge detectors using a spectrum summing

    SciTech Connect

    Killian, E.W.

    1997-05-01

    A technique has been developed at the Idaho National Engineering Laboratory to sum high resolution gamma-ray pulse spectra from systems with multiple Ge detectors. Lockheed Martin Idaho Technologies Company operates a multi-detector spectrometer configuration at the Stored Waste Examination Pilot Plant facility which is used to characterize the radio nuclide contents in waste drums destined for shipment to Waste Isolation Pilot Plant. This summing technique was developed to increase the sensitivity of the system, reduce the count times required to properly quantify the radionuclides and provide a more consistent methodology for combining data collected from multiple detectors. In spectrometer systems with multiple detectors looking at non homogenous waste forms it is often difficult to combine individual spectrum analysis results from each detector to obtain a meaningful result for the total waste container. This is particularly true when the counting statistics in each individual spectrum are poor. The spectrum summing technique adds the spectra collected by each detector into a single spectrum which has better counting statistics than each individual spectrum. A normal spectral analysis program can then be used to analyze the sum spectrum to obtain radio nuclide values which have smaller errors and do not have to be further manipulated to obtain results for the total waste container.

  12. Spin-Charge Conversion Phenomena in Germanium

    NASA Astrophysics Data System (ADS)

    Oyarzún, Simón; Rortais, Fabien; Rojas-Sánchez, Juan-Carlos; Bottegoni, Federico; Laczkowski, Piotr; Vergnaud, Céline; Pouget, Stéphanie; Okuno, Hanako; Vila, Laurent; Attané, Jean-Philippe; Beigné, Cyrille; Marty, Alain; Gambarelli, Serge; Ducruet, Clarisse; Widiez, Julie; George, Jean-Marie; Jaffrès, Henri; Jamet, Matthieu

    2017-01-01

    The spin-orbit coupling relating the electron spin and momentum allows for spin generation, detection and manipulation. It thus fulfils the three basic functions of the spin field-effect-transistor made of semiconductors. In this paper, we review our recent results on spin-charge conversion in bulk germanium and at the Ge(111) surface. We used the spin pumping technique to generate pure spin currents to be injected into bulk germanium and at the Fe/Ge(111) interface. The mechanism for spin-charge conversion in bulk germanium is the spin Hall effect and we could experimentally determine the spin Hall angle θSHE, i.e., the spin-charge conversion efficiency, in heavily doped n-type and p-type germanium. We found very small values at room temperature: θSHE ≈ (1-2) × 10-3 in n-Ge and θSHE ≈ (6-7) × 10-4 in p-Ge. Moreover, we pointed out the essential role of spin dependent scattering on ionized impurities in the spin Hall effect mechanism. We concluded that the spin Hall effect in bulk germanium is too weak to produce large spin currents, whereas a large Rashba effect (>100 meV) at Ge(111) surfaces covered with heavy metals could generate spin polarized currents. We could indeed demonstrate a giant spin-to-charge conversion in metallic states at the Fe/Ge(111) interface due to the Rashba coupling. We generated very large charge currents by direct spin pumping into the interface states from 20 K to room temperature. By this, we raise a new paradigm: the possibility to use the spin-orbit coupling for the development of the spin-field-effect-transistor.

  13. Al{sub 2}O{sub 3}/GeO{sub x} gate stack on germanium substrate fabricated by in situ cycling ozone oxidation method

    SciTech Connect

    Yang, Xu; Zeng, Zhen-Hua; Wang, Sheng-Kai E-mail: xzhang62@aliyun.com Sun, Bing; Zhao, Wei; Chang, Hu-Dong; Liu, Honggang E-mail: xzhang62@aliyun.com; Zhang, Xiong E-mail: xzhang62@aliyun.com

    2014-09-01

    Al{sub 2}O{sub 3}/GeO{sub x}/Ge gate stack fabricated by an in situ cycling ozone oxidation (COO) method in the atomic layer deposition (ALD) system at low temperature is systematically investigated. Excellent electrical characteristics such as minimum interface trap density as low as 1.9 × 10{sup 11 }cm{sup −2 }eV{sup −1} have been obtained by COO treatment. The impact of COO treatment against the band alignment of Al{sub 2}O{sub 3} with respect to Ge is studied by x-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry (SE). Based on both XPS and SE studies, the origin of gate leakage in the ALD-Al{sub 2}O{sub 3} is attributed to the sub-gap states, which may be correlated to the OH-related groups in Al{sub 2}O{sub 3} network. It is demonstrated that the COO method is effective in repairing the OH-related defects in high-k dielectrics as well as forming superior high-k/Ge interface for high performance Ge MOS devices.

  14. Ultra High-Rate Germanium (UHRGe) Modeling Status Report

    SciTech Connect

    Warren, Glen A.; Rodriguez, Douglas C.

    2012-06-07

    The Ultra-High Rate Germanium (UHRGe) project at Pacific Northwest National Laboratory (PNNL) is conducting research to develop a high-purity germanium (HPGe) detector that can provide both the high resolution typical of germanium and high signal throughput. Such detectors may be beneficial for a variety of potential applications ranging from safeguards measurements of used fuel to material detection and verification using active interrogation techniques. This report describes some of the initial radiation transport modeling efforts that have been conducted to help guide the design of the detector as well as a description of the process used to generate the source spectrum for the used fuel application evaluation.

  15. Sr2(Mg1-xGax)Ge2O7+0.5x: Melilite-type oxygen ionic conductor associated with fivefold coordinated germanium and gallium

    NASA Astrophysics Data System (ADS)

    Park, Hee Jung; Kim, Tae-Gon; Kwak, Chan; Jung, Doh Won; Lee, Sangmock; Lee, Kyu Hyoung

    2015-02-01

    We demonstrate a new type of oxygen ionic conductor, Sr2(Mg1-xGax)Ge2O7+0.5x with a melilite-type structure. The oxygen-ion conductivity of Sr2Mg0.8Ga0.2Ge2O7.1 is measured as 10-4 S/cm at 800 °C using both 2-probe ac impedance and 4-probe dc measurements, and hardly depends on Po2 indicating that the main charge carriers are interstitial oxygen ions. Based on total energy calculations, it is suggested that a Ge4+ ion as well as Ga3+ contributes to the ionic conduction of interstitial oxygen through the coordination changes from fourfold to fivefold.

  16. Germanium films by polymer-assisted deposition

    DOEpatents

    Jia, Quanxi; Burrell, Anthony K.; Bauer, Eve; Ronning, Filip; McCleskey, Thomas Mark; Zou, Guifu

    2013-01-15

    Highly ordered Ge films are prepared directly on single crystal Si substrates by applying an aqueous coating solution having Ge-bound polymer onto the substrate and then heating in a hydrogen-containing atmosphere. A coating solution was prepared by mixing water, a germanium compound, ethylenediaminetetraacetic acid, and polyethyleneimine to form a first aqueous solution and then subjecting the first aqueous solution to ultrafiltration.

  17. Improving CMOS-compatible Germanium photodetectors.

    PubMed

    Li, Guoliang; Luo, Ying; Zheng, Xuezhe; Masini, Gianlorenzo; Mekis, Attila; Sahni, Subal; Thacker, Hiren; Yao, Jin; Shubin, Ivan; Raj, Kannan; Cunningham, John E; Krishnamoorthy, Ashok V

    2012-11-19

    We report design improvements for evanescently coupled Germanium photodetectors grown at low temperature. The resulting photodetectors with 10 μm Ge length manufactured in a commercial CMOS process achieve >0.8 A/W responsivity over the entire C-band, with a device capacitance of <7 fF based on measured data.

  18. The role of oxidized germanium in the growth of germanium nanoparticles on hafnia

    NASA Astrophysics Data System (ADS)

    Winkenwerder, Wyatt A.; Ekerdt, John G.

    2008-08-01

    The role oxidized germanium (GeO x) plays in germanium (Ge) nanoparticle growth on hafnia is reported. Oxide islands, in the form of hafnium germinate, form on hafnia during the initial stages of growth. The Ge adatoms are oxidized by background oxidants, such as water, only when they are in contact with the hafnia surface. Once a sufficient amount of hafnium germinate has formed, Ge nanoparticles nucleate such that nanoparticle growth proceeds by Ge growth on GeO x. Nanoparticles are not deposited on the hafnia but only on the interfacial oxide islands formed early in the growth process. Annealing hafnia in a silane ambient after Ge nanoparticle growth reduces the amount of GeO x and appears to transform it into a hafnium silicate. Furthermore, the electronic and/or chemical interaction between the Ge nanoparticles and the hafnia substrate is changed by the silane annealing step as reflected in the binding energy shift in the Ge 2p signal and the increased retention time of metal-oxide-semiconductor capacitors made from Ge nanoparticles and hafnia. Pretreating hafnia in silane leads to hafnium silicate islands and subsequent Ge nanoparticle growth proceeds on the silicate islands.

  19. Synthesis of mixed tin-ruthenium and tin-germanium-ruthenium carbonyl clusters from [Ru3(CO)12] and diaminometalenes (M = Sn, Ge).

    PubMed

    Cabeza, Javier A; García-Álvarez, Pablo; Polo, Diego

    2012-02-20

    Diaminostannylenes react with [Ru(3)(CO)(12)] without cluster fragmentation to give carbonyl substitution products regardless of the steric demand of the diaminostannylene reagent. Thus, the Sn(3)Ru(3) clusters [Ru(3){μ-Sn(NCH(2)(t)Bu)(2)C(6)H(4)}(3)(CO)(9)] (4) and [Ru(3){μ-Sn(HMDS)(2)}(3)(CO)(9)] (6) [HMDS = N(SiMe(3))(2)] have been prepared in good yields by treating [Ru(3)(CO)(12)] with an excess of the cyclic 1,3-bis(neo-pentyl)-2-stannabenzimidazol-2-ylidene and the acyclic and bulkier Sn(HMDS)(2), respectively, in toluene at 110 °C. The use of smaller amounts of Sn(HMDS)(2) (Sn/Ru(3) ratio = 2.5) in toluene at 80 °C afforded the Sn(2)Ru(3) derivative [Ru(3){μ-Sn(HMDS)(2)}(2)(μ-CO)(CO)(9)] (5). Compounds 5 and 6 represent the first structurally characterized diaminostannylene-ruthenium complexes. While a further treatment of 5 with Ge(HMDS)(2) led to a mixture of uncharacterized compounds, a similar treatment with the sterically alleviated diaminogermylene Ge(NCH(2)(t)Bu)(2)C(6)H(4) provided [Ru(3){μ-Sn(HMDS)(2)}(2){μ-Ge(NCH(2)(t)Bu)(2)C(6)H(4)}(CO)(9)] (7), which is a unique example of Sn(2)GeRu(3) cluster. All these reactions, coupled to a previous observation that [Ru(3)(CO)(12)] reacts with excess of Ge(HMDS)(2) to give the mononuclear complex [Ru{Ge(HMDS)(2)}(2)(CO)(3)] but triruthenium products with less bulky diaminogermylenes, indicate that, for reactions of [Ru(3)(CO)(12)] with diaminometalenes, both the volume of the diaminometalene and the size of its donor atom (Ge or Sn) are of key importance in determining the nuclearity of the final products.

  20. Novel approach for n-type doping of HVPE gallium nitride with germanium

    NASA Astrophysics Data System (ADS)

    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.

  1. A new reaction mode of germanium-silicon bond formation: insertion reactions of H₂GeLiF with SiH₃X (X = F, Cl, Br).

    PubMed

    Yan, Bingfei; Li, Wenzuo; Xiao, Cuiping; Li, Qingzhong; Cheng, Jianbo

    2013-10-01

    A combined density functional and ab initio quantum chemical study of the insertion reactions of the germylenoid H2GeLiF with SiH3X (X = F, Cl, Br) was carried out. The geometries of all the stationary points of the reactions were optimized using the DFT B3LYP method and then the QCISD method was used to calculate the single-point energies. The theoretical calculations indicated that along the potential energy surface, there were one precursor complex (Q), one transition state (TS), and one intermediate (IM) which connected the reactants and the products. The calculated barrier heights relative to the respective precursors are 102.26 (X = F), 95.28 (X = Cl), and 84.42 (X = Br) kJ mol(-1) for the three different insertion reactions, respectively, indicating the insertion reactions should occur easily according to the following order: SiH3-Br > SiH3-Cl > SiH3-F under the same situation. The solvent effects on the insertion reactions were also calculated and it was found that the larger the dielectric constant, the easier the insertion reactions. The elucidations of the mechanism of these insertion reactions provided a new reaction model of germanium-silicon bond formation.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  3. The Germanium GAlactic Plane Patrol mission

    NASA Technical Reports Server (NTRS)

    Tueller, Jack; Gehrels, Neil; Leventhal, Marvin

    1992-01-01

    The goal of the Germanium GAlactic Plane Patrol mission (GGAPP) is to provide a continuous monitor of the Galactic Plane (GP) for variable sources of gamma-ray lines. Potentially interesting sources include black hole candidates, X-ray binary systems, pulsars, gamma-ray bursts, and solar flares. The GGAPP instrument is an array of Ge detectors cooled by a mechanical refrigerator to achieve a spectral resolution of 2 keV at 1 MeV (1/500). A bismuth germanate (BGO) shield will restrict the field-of-view (FOV) to within 20 deg of the GP, and a modulation collimator system will locate strong sources to less than 0.3 deg in galactic longitude, provide a direct means of subtracting background, and mapping the diffuse emission from the GP. The spacecraft will be rotationally stabilized with the spin axis perpendicular to the GP such that the modulator scans in galactic longitude. A HEO or L1 orbit will keep GGAPP far away from the strong background produced by the Earth. GGAPP will provide a natural bridge between GRO and future missions such as INTEGRAL/NAE.

  4. Verification tests of the GALLEX solar neutrino detector, with 71Ge produced in-situ from the beta-decay of 71As.

    NASA Astrophysics Data System (ADS)

    Hampel, W.; Handt, J.; Heusser, G.; Kaether, D.; Kiko, J.; Kirsten, T.; Laubenstein, M.; Neder, E.; Pernicka, E.; Rau, W.; Richter, H.; Ronn, U.; Schwan, U.; Wojcik, M.; Zakharov, Y.; von Ammon, R.; Ebert, K. H.; Fritsch, T.; Heidt, D.; Henrich, E.; Stieglitz, L.; Weirich, F.; Balata, M.; Hartmann, F. X.; Bellotti, E.; Cattadori, C.; Cremonesi, O.; Ferrari, N.; Fiorini, E.; Zanotti, L.; Altmann, M.; von Feilitzsch, F.; Mossbauer, R.; Berthomieu, G.; Schatzman, E.; Carmi, I.; Dostrovsky, I.; Bacci, C.; Belli, P.; Bernabei, R.; D'Angelo, S.; Paoluzi, L.; Cribier, M.; Rich, J.; Spiro, M.; Tao, C.; Vignaud, D.; Boger, J.; Hahn, R. L.; Rowley, J. K.; Stoenner, R. W.; Weneser, J.

    1998-09-01

    Previously, it was demonstrated that the GALLEX solar neutrino detector responds properly to low energy neutrinos, by exposing it to two intense 51Cr-neutrino sources; the recovery yield of the product 71Ge was reported to be 93%±8%. New experiments, in which known amounts of radioactive 71As have decayed to 71Ge in the full-scale gallium detector, strongly support this evidence. In several experiments, the gallium detector has been spiked with ≡105 71As atoms, under varying conditions of how the 71As was added (either carrier free, or with Ge carrier), how the gallium solution was mixed, and how long the 71Ge remained in the gallium. 71As decays by electron capture and positron emission to 71Ge, with a half life of 2.72 d. Hot atoms are produced by these decay modes with kinematics that mimic solar neutrino capture, although the 51Cr neutrino source provided a more perfect match. This relative disadvantage is offset by the much better statistics obtainable with the 71As. In all 71As experiments, the recovery of 71Ge from the gallium was 100%, with uncertainties of only ±1%. The combined results from the 51Cr sources and the 71As spikes rule out any loss mechanisms for 71Ge, including hot-atom chemical effects.

  5. Uncooled Infrared Microbolometers and Silicon Germanium Oxide (SixGe1-xOy) Infrared Sensitive Material for Long Wavelength Detection

    DTIC Science & Technology

    2014-10-10

    120 Micro IR camera: operational performance," Proc. SPIE, vol. 4393, pp. 89-98, 2001. [12] C. Li, C. J. Han, G. D. Skidmore, and C. Hess , "DRS...1996. [49] S. Sedky, P. Fiorini, K. Baert, L. Hermans , and R. Mertens, "Characterization and optimization of infrared poly SiGe bolometers," IEEE...Transaction on Electron Devices, vol. 46(4), pp. 675-682, 1999. [50] S. Sedky, P. Fiorini, M. Caymax, C. Baert, L. Hermans , and R. Mertens

  6. A search for GeV-TeV emission from Gamma-ray Bursts using the Milagro detector

    SciTech Connect

    Saz Parkinson, P. M.

    2009-04-08

    The Milagro detector surveyed the sky continuously in the Very High Energy regime from January 2000 through March 2008. During that time, over 130 GRBs were detected and well localized by satellites within its 2 sr field of view. We have used Milagro data to search for >1 GeV emission from these bursts. Milagro is a water Cerenkov detector designed primarily for observations in the 0.1-100 TeV energy range. In the standard mode of operation, Milagro data is used to reconstruct the direction of an incoming high energy particle by analyzing the timing information of a large number of photomultiplier tubes that are triggered in coincidence by the air shower generated when such a particle interacts with the Earth's atmosphere. Milagro data, however, can also be analyzed in 'scaler mode', where the rates of individual photomultiplier tubes can be used to detect emission above 1 GeV (albeit with no directional information). Here we present results from both techniques for all known GRBs detected by BATSE, BeppoSax, HETE-2, INTEGRAL, Swift, and the IPN, within the field of view of Milagro in its 8 years of operation.

  7. Fabrication and characteristics of porous germanium films

    PubMed Central

    Jing, Chengbin; Zhang, Chuanjian; Zang, Xiaodan; Zhou, Wenzheng; Bai, Wei; Lin, Tie; Chu, Junhao

    2009-01-01

    Porous germanium films with good adhesion to the substrate were produced by annealing GeO2 ceramic films in H2 atmosphere. The reduction of GeO2 started at the top of a film and resulted in a Ge layer with a highly porous surface. TEM and Raman measurements reveal small Ge crystallites at the top layer and a higher degree of crystallinity at the bottom part of the Ge film; visible photoluminescence was detected from the small crystallites. Porous Ge films exhibit high density of holes (1020 cm−3) and a maximum of Hall mobility at ∼225 K. Their p-type conductivity is dominated by the defect scattering mechanism. PMID:27877311

  8. New constraints and discovery potential of sub-GeV dark matter with xenon detectors

    NASA Astrophysics Data System (ADS)

    McCabe, Christopher

    2017-08-01

    Existing xenon dark matter (DM) direct detection experiments can probe the DM-nucleon interaction of DM with a sub-GeV mass through a search for photon emission from the recoiling xenon atom. We show that LUX's constraints on sub-GeV DM, which utilize the scintillation (S1) and ionization (S2) signals, are approximately 3 orders of magnitude more stringent than previous xenon constraints in this mass range, derived from the XENON10 and XENON100 S2-only searches. The new LUX constraints provide the most stringent direct detection constraints for DM particles with a mass below 0.5 GeV. In addition, the photon emission signal in LUX and its successor LZ maintain the discrimination between background and signal events so that an unambiguous discovery of sub-GeV DM is possible. We show that LZ has the potential to reconstruct the DM mass with ≃20 % accuracy for particles lighter than 0.5 GeV.

  9. Strongly Enhanced THz Emission caused by Localized Surface Charges in Semiconducting Germanium Nanowires

    PubMed Central

    Lee, Woo-Jung; Ma, Jin Won; Bae, Jung Min; Jeong, Kwang-Sik; Cho, Mann-Ho; Kang, Chul; Wi, Jung-Sub

    2013-01-01

    A principal cause of THz emission in semiconductor nanostructures is deeply involved with geometry, which stimulates the utilization of indirect bandgap semiconductors for THz applications. To date, applications for optoelectronic devices, such as emitters and detectors, using THz radiation have focused only on direct bandgap materials. This paper reports the first observation of strongly enhanced THz emission from Germanium nanowires (Ge NWs). The origin of THz generation from Ge NWs can be interpreted using two terms: high photoexcited electron-hole carriers (Δn) and strong built-in electric field (Eb) at the wire surface based on the relation . The first is related to the extensive surface area needed to trigger an irradiated photon due to high aspect ratio. The second corresponds to the variation of Fermi-level determined by confined surface charges. Moreover, the carrier dynamics of optically excited electrons and holes give rise to phonon emission according to the THz region. PMID:23760467

  10. Optimal process parameters for phosphorus spin-on-doping of germanium

    NASA Astrophysics Data System (ADS)

    Boldrini, Virginia; Carturan, Sara Maria; Maggioni, Gianluigi; Napolitani, Enrico; Napoli, Daniel Ricardo; Camattari, Riccardo; De Salvador, Davide

    2017-01-01

    The fabrication of homogeneously doped germanium layers characterized by total electrical activation is currently a hot topic in many fields, such as microelectronics, photovoltaics, optics and radiation detectors. Phosphorus spin-on-doping technique has been implemented on Ge wafers, by developing a protocol for the curing process and subsequent diffusion annealing for optimal doping. Parameters such as relative humidity and curing time turned out to affect the surface morphology, the degree of reticulation reached by the dopant source and the amount of dopant available for diffusion. After spike annealing in a conventional furnace, diffusion profiles and electrical properties have been measured. Ge loss from the surface during high-temperature annealing, due to diffusion into the source film, has been observed and quantified.

  11. Germanium Metal - Insulator - Semiconductor Field Effect Transistors Utilizing a Germanium Nitride Gate Insulator.

    NASA Astrophysics Data System (ADS)

    Rosenberg, James Jordan

    The work presented in this thesis provides new information on three distinct but related topics. Firstly, it describes a technique for growing thin films of germanium nitride on germanium--a previously unexplored semiconductor -insulator system. Secondly, it describes electrical measurements made on metal-Ge(,3)N(,4)-Ge capacitors which demonstrate that this metal-insulator-semiconductor (MIS) system is of high quality. Thirdly, it describes a process by which n-channel germanium metal-insulator-semiconductor field effect transistors (MISFETs) have been fabricated. The motivations for exploring this new MIS system (e.g. basic physics of germanium inversion layers, higher performance MISFETs, etc.) are also described. The growth technique described here and the films produced by it possess several distinct advantages over previous methods of obtaining insulating films on germanium. The growth technique itself is simple. It involves no elaborate or expensive equipment, and is essentially identical in its execution (although not in its chemical process) to conventional techniques for obtaining an insulator on silicon (i.e. thermal oxidation of silicon). The film growth technique yields very reproducible results (in terms of film thickness and refractive index) from wafer to wafer. The physical properties of the film itself are also attractive. It is far more chemically stable than germanium oxide, and is quite process compatible. It is resistant to many chemicals encountered in typical processing cycles, but also can be readily patterned in hot phosphoric acid, which does not appreciably attack germanium. Electrical measurements on MIS capacitors indicate that the density of fast states at the germanium-germanium nitride interface is quite low. The interface state density is less than or equal to 1 x 10('11)/cm('2)-eV from midgap to within 0.15 eV of the conduction band edge, as determined by variable frequency capacitance measurements. The MISFETs fabricated for this

  12. Si/SiGe MMIC's

    NASA Astrophysics Data System (ADS)

    Luy, Johann-Friedrich; Strohm, Karl M.; Sasse, Hans-Eckard; Schueppen, Andreas; Buechler, Josef; Wollitzer, Michael; Gruhle, Andreas; Schaeffler, Friedrich; Guettich, Ulrich; Klaassen, Andreas

    1995-04-01

    Silicon-based millimeter-wave integrated circuits (SIMMWIC's) can provide new solutions for near range sensor and communication applications in the frequency range above 50 GHz. This paper gives a survey on the state-of-the-art performance of this technology and on first applications. The key devices are IMPATT diodes for mm-wave power generation and detection in the self-oscillating mixer mode, p-i-n diodes for use in switches and phase shifters, and Schottky diodes in detector and mixer circuits. The silicon/silicon germanium heterobipolar transistor (SiGe HBT) with f(sub max) values of more than 90 GHz is now used for low-noise oscillators at Ka-band frequencies. First system applications are discussed.

  13. Heterojunction Internal Photoemission SiO.7GeO.3/Si Infrared Detector

    NASA Technical Reports Server (NTRS)

    Lin, True Lon

    1994-01-01

    Silicon-compatible detectors are amoung the most promising infrared sensors for large focal plane array applications due to their advantages of uniformity, reliability, and easy integration with low-noise Si readout circuitry.

  14. Zirconia-germanium interface photoemission spectroscopy using synchrotron radiation

    SciTech Connect

    Chui, Chi On

    2005-04-05

    An ultrathin zirconia gate dielectric had been successfully incorporated into germanium metal-oxide-semiconductor (MOS) devices demonstrating very high permittivity gate stacks with no apparent interfacial layer. In this study, synchrotron radiation photoemission spectroscopy has been applied on the same gate stack to identify and quantify the presence of any interfacial germanium sub-oxide layer. By taking progressive core- level spectra during the layer-by-layer removal of the zirconia film, an oxidized germanium layer with sub-monolayer thickness was found possibly arising from an interfacial Zr-O-Ge bonding configuration. In addition, the offsets in the valence band spectra were also monitored and the energy band diagram of the zirconia-germanium heterostructure was constructed. Compared to high-{kappa} gate stacks on Si, the thinner interfacial layer and larger conduction band offset in high-{kappa} gate stacks on Ge suggest better scalability towards an ultimately higher MOS gate capacitance.

  15. Efficiency transfer in the calibration of a coaxial p-type HpGe detector using the Monte Carlo method.

    PubMed

    Vargas, M Jurado; Díaz, N Cornejo; Sánchez, D Pérez

    2003-06-01

    Monte Carlo simulation was applied to the efficiency transfer exercise described in the EUROMET428 project (Appl. Radiat. Isot. 55 (2001) 493), evaluating the peak efficiencies in the energy range 60-2000 keV for a typical coaxial p-type HpGe detector and several types of source configuration: point sources located at various distances from the detector and a cylindrical box containing three matrices. The efficiency values were derived in two ways: (a) by direct calculation taking into account the physical dimensions of the detector provided by the supplier, and (b) by means of relative computation (efficiency transfer) taking also into consideration the known efficiency values for a reference point source. As expected, some significant discrepancies between the calculated and experimental values were found when a direct computation was made using the data provided by the supplier. On the contrary, the results for the peak efficiency derived by relative calculation by means of an efficiency transfer were in good agreement with the experimental values. The deviations found with this last procedure were generally below 5% for all the geometries considered, which is entirely satisfactory for the purposes of routine measurements.

  16. Reducing Multiplexing Artifacts in Multi-Pinhole SPECT with a Stacked Silicon-Germanium System: a Simulation Study

    PubMed Central

    Johnson, Lindsay C.; Shokouhi, Sepideh; Peterson, Todd E

    2015-01-01

    In pinhole 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 non-multiplexed 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. PMID:25055382

  17. Reducing multiplexing artifacts in multi-pinhole SPECT with a stacked silicon-germanium system: a simulation study.

    PubMed

    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.

  18. Theoretical investigation of tensile strained GeSn waveguide with Si₃N₄ liner stressor for mid-infrared detector and modulator applications.

    PubMed

    Zhang, Qingfang; Liu, Yan; Yan, Jing; Zhang, Chunfu; Hao, Yue; Han, Genquan

    2015-03-23

    We theoretically investigate a tensile strained GeSn waveguide integrated with Si₃N₄ liner stressor for the applications in mid-infrared (MIR) detector and modulator. A substantial tensile strain is induced in a 1 × 1 μm² GeSn waveguide by the expansion of 500 nm Si₃N₄ liner stressor and the contour plots of strain are simulated by the finite element simulation. Under the tensile strain, the direct bandgap E(G,Γ) of GeSn is significantly reduced by lowering the Γ conduction valley in energy and lifting of degeneracy of valence bands. Absorption coefficients of tensile strained GeSn waveguides with different Sn compositions are calculated. As the Si₃N₄ liner stressor expands by 1%, the cut-off wavelengths of tensile strained Ge(0.97)Sn(0.03), Ge(0.95)Sn(0.05), and Ge(0.90)Sn(0.10) waveguide photodetectors are extended to 2.32, 2.69, and 4.06 μm, respectively. Tensile strained Ge(0.90)Sn(0.10) waveguide electro-absorption modulator based on Franz-Keldysh (FK) effect is demonstrated in theory. External electric field dependence of cut-off wavelength and propagation loss of tensile strained Ge(0.90)Sn(0.10) waveguide is observed, due to the FK effect.

  19. A maximum likelihood analysis of the CoGeNT public dataset

    NASA Astrophysics Data System (ADS)

    Kelso, Chris

    2016-06-01

    The CoGeNT detector, located in the Soudan Underground Laboratory in Northern Minnesota, consists of a 475 grams (fiducial mass of 330 grams) target mass of p-type point contact germanium detector that measures the ionization charge created by nuclear recoils. This detector has searched for recoils created by dark matter since December of 2009. We analyze the public dataset from the CoGeNT experiment to search for evidence of dark matter interactions with the detector. We perform an unbinned maximum likelihood fit to the data and compare the significance of different WIMP hypotheses relative to each other and the null hypothesis of no WIMP interactions. This work presents the current status of the analysis.

  20. A maximum likelihood analysis of the CoGeNT public dataset

    SciTech Connect

    Kelso, Chris

    2016-06-21

    The CoGeNT detector, located in the Soudan Underground Laboratory in Northern Minnesota, consists of a 475 grams (fiducial mass of 330 grams) target mass of p-type point contact germanium detector that measures the ionization charge created by nuclear recoils. This detector has searched for recoils created by dark matter since December of 2009. We analyze the public dataset from the CoGeNT experiment to search for evidence of dark matter interactions with the detector. We perform an unbinned maximum likelihood fit to the data and compare the significance of different WIMP hypotheses relative to each other and the null hypothesis of no WIMP interactions. This work presents the current status of the analysis.

  1. Solution-processable white-light-emitting germanium nanocrystals

    SciTech Connect

    Shirahata, Naoto

    2014-06-01

    This paper describes an efficient chemical route for the synthesis of visible light emitting nanocrystals of germanium (ncGe). The synthesis started by heating Ge(II) iodide at 300 °C in argon atmosphere. Spectroscopic characterizations confirmed the formation of diamond cubic lattice structures of ncGe. By grafting hydrophobic chains on the ncGe surface, the dispersions in nonpolar solvents of the ncGe became very stable. The as-synthesized ncGe showed the bluish white photoluminescence (PL) feature, but it was found that the PL spectrum is composed of many different emission spectra. Therefore, the color-tuning of white light emission is demonstrated through the witting removal of extra ncGe with unfavorable emission feature by making full use of column chromatographic techniques. - Highlights: • Visible light emitting nanocrystals of germanium was synthesized by chemical reduction of germanium iodide. • White light emission was achieved by control over size distribution of germanium nanocrystals. • Tuning the color of white light was achieved by separation of nanocrystals by emission.

  2. Crystallization of Electrodeposited Germanium Thin Film on Silicon (100)

    PubMed Central

    Abidin, Mastura Shafinaz Zainal; Matsumura, Ryo; Anisuzzaman, Mohammad; Park, Jong-Hyeok; Muta, Shunpei; Mahmood, Mohamad Rusop; Sadoh, Taizoh; Hashim, Abdul Manaf

    2013-01-01

    We report the crystallization of electrodeposited germanium (Ge) thin films on n-silicon (Si) (100) by rapid melting process. The electrodeposition was carried out in germanium (IV) chloride: propylene glycol (GeCl4:C3H8O2) electrolyte with constant current of 50 mA for 30 min. The measured Raman spectra and electron backscattering diffraction (EBSD) images show that the as-deposited Ge thin film was amorphous. The crystallization of deposited Ge was achieved by rapid thermal annealing (RTA) at 980 °C for 1 s. The EBSD images confirm that the orientations of the annealed Ge are similar to that of the Si substrate. The highly intense peak of Raman spectra at 300 cm−1 corresponding to Ge-Ge vibration mode was observed, indicating good crystal quality of Ge. An additional sub peak near to 390 cm−1 corresponding to the Si-Ge vibration mode was also observed, indicating the Ge-Si mixing at Ge/Si interface. Auger electron spectroscopy (AES) reveals that the intermixing depth was around 60 nm. The calculated Si fraction from Raman spectra was found to be in good agreement with the value estimated from Ge-Si equilibrium phase diagram. The proposed technique is expected to be an effective way to crystallize Ge films for various device applications as well as to create strain at the Ge-Si interface for enhancement of mobility. PMID:28788375

  3. Electrodeposition of germanium from supercritical fluids.

    PubMed

    Ke, Jie; Bartlett, Philip N; Cook, David; Easun, Timothy L; George, Michael W; Levason, William; Reid, Gillian; Smith, David; Su, Wenta; Zhang, Wenjian

    2012-01-28

    Several Ge(II) and Ge(IV) compounds were investigated as possible reagents for the electrodeposition of Ge from liquid CH(3)CN and CH(2)F(2) and supercritical CO(2) containing as a co-solvent CH(3)CN (scCO(2)) and supercritical CH(2)F(2) (scCH(2)F(2)). For Ge(II) reagents the most promising results were obtained using [NBu(n)(4)][GeCl(3)]. However the reproducibility was poor and the reduction currents were significantly less than the estimated mass transport limited values. Deposition of Ge containing films was possible at high cathodic potential from [NBu(n)(4)][GeCl(3)] in liquid CH(3)CN and supercritical CO(2) containing CH(3)CN but in all cases they were heavily contaminated by C, O, F and Cl. Much more promising results were obtained using GeCl(4) in liquid CH(2)F(2) and supercritical CH(2)F(2). In this case the reduction currents were consistent with mass transport limited reduction and bulk electrodeposition produced amorphous films of Ge. Characterisation by XPS showed the presence of low levels of O, F and C, XPS confirmed the presence of Ge together with germanium oxides, and Raman spectroscopy showed that the as deposited amorphous Ge could be crystallised by the laser used in obtaining the Raman measurements.

  4. Heat capacity of high-purity isotope-enriched germanium-76 in the temperature range of 2-15 K

    NASA Astrophysics Data System (ADS)

    Gusev, A. V.; Gibin, A. M.; Andryushchenko, I. A.; Gavva, V. A.; Kozyrev, E. A.

    2015-09-01

    The heat capacity of high-purity isotopically-enriched germanium Ge-76 has been measured in the range of 2.5-15 K. In this range, the heat capacity of Ge-76 is 6-15% higher than the heat capacity of germanium of the natural isotopic composition, which is determined by a change in the average mass.

  5. TRIFLUOROMETHYL COMPOUNDS OF GERMANIUM

    DTIC Science & Technology

    FLUORIDES, *GERMANIUM COMPOUNDS, *HALIDES, *ORGANOMETALLIC COMPOUNDS, ALKYL RADICALS, ARSENIC COMPOUNDS, CHEMICAL BONDS, CHEMICAL REACTIONS ...CHLORIDES, CHLORINE COMPOUNDS, HYDROLYSIS, IODIDES, METHYL RADICALS, POTASSIUM COMPOUNDS, PYROLYSIS, STABILITY, SYNTHESIS, TIN COMPOUNDS.

  6. Ion Implanted Ge:B Far Infrard Blocked Impurity BandDetectors

    SciTech Connect

    Beeman, J.W.; Goyal, S.; Reichertz, L.A.; Haller, E.E.

    2006-06-12

    Ge Blocked Impurity Band (BIB) photoconductors have the potential to replace stressed Ge:Ga photoconductors for far-infrared astronomical observations. A novel planar BIB device has been fabricated in which ion-implanted boron is used to form the blocking and absorbing layers of necessary purity and compensation. The effect of doping in the infrared active layer on the far-infrared photoconductive response has been studied, and the optimum doping concentration is found to be {approx} 4 x 10{sup 16} cm{sup -3}. Devices doped near this concentration show good blocking characteristics with low dark currents. The spectral response extends to {approx} 45 cm{sup -1}, clearly showing the formation of an impurity band. Under low background testing conditions these devices attain a responsivity of 0.12 A/W and NEP of 5.23 x 10{sup -15} W/Hz{sup -1/2}.

  7. Silicon Based Mid Infrared SiGeSn Heterostructure Emitters and Detectors

    DTIC Science & Technology

    2016-05-16

    more improvement. 15. SUBJECT TERMS electronic materials, heterostructure semiconductors, light emitting devices 16. SECURITY CLASSIFICATION OF: 17...J. Margetis, Y. Zhou, A. Mosleh, A. Nazzal, G. Sun, R. A. Soref, J. Tolle, B. Li, H. A. Naseem, “Si based GeSn light emitter: mid-infrared device in...Temperature- dependent characterization of G0.94Sn0.06 light -emitting diode grown on Si via CVD,” Proceeding of the Conference on Lasers and

  8. Long wavelength photoconductive detectors for airborne and orbital infrared astronomy

    NASA Technical Reports Server (NTRS)

    Houck, J. R.

    1983-01-01

    Seven gallium doped germanium (Ge:Ga) photoconductive infrared detectors were fabricated and mounted in integrating cavities. In addition, a cold preamplifier package consisting of J230 junction field effect transistors (JFETs) was produced. Tests of the system under low photon background conditions indicated that sensitivity was limited by the Johnson noise of the load resistor. The detectors were mounted in the Ames cooled grating spectrometer, and flown on the Kuiper Airborne Observatory. Good quality astronomical data were obtained during the flight of 7 July 1983.

  9. Optical properties of silicon germanium waveguides at telecommunication wavelengths.

    PubMed

    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.

  10. Na-doped optical Germanium bulk crystals

    NASA Astrophysics Data System (ADS)

    Pekar, G. S.; Singaevsky, A. F.

    2012-09-01

    In an effort to develop a material for infrared (IR) optics with improved parameters, bulk crystals of optical germanium doped with Na have been first grown and studied. Single-crystalline and coarse-crystalline Ge:Na boules of different shapes and dimensions, up to 10 kg by weight, have been grown. Sodium was incorporated into the Ge crystal during the crystal growing from the melt. Despite the fact that Na contamination in the source material was not strictly controlled, the density of Na in the grown crystals determined by the neutron activation analysis as well as by the glow discharge mass spectrometry did not exceed 1015 cm-3. Just this value may be supposed to be close to the solubility limit of Na incorporated in Ge in the course of bulk crystal growth. A first demonstration of donor behavior of Na in bulk Ge crystals is made by means of a thermoelectric type of testing. An interstitial location of Na impurity has been verified by experiments on donor drift in the dc electric field. The crystals are grown with free electron density in the range from 5ṡ1013 to 4ṡ1014 cm-3 which is optimal for using Ge crystals as an optical material for fabricating passive elements of the IR technique. A comparison between the properties of Ge:Na crystals and Ge crystals doped with Sb, a conventional impurity in optical germanium, grown under the same technological conditions and from the same intrinsic Ge as a source material, revealed a number of advantages of Ge:Na crystals; among them, the higher transparency in the IR region, smaller radiation scattering and higher regular optical transmission, lower dislocation density, more uniform distribution of electrical and optical characteristics over the crystal volume, the identity of optical parameters in the single-crystalline, and coarse-crystalline boules. No degradation of optical elements fabricated from Ge:Na crystals was detected in the course of their commercial application, starting from 1998.

  11. Beta-Decay Spectroscopy of Neutron-Rich Isotopes Utilizing a Planar Ge Double-Sided Strip Detector

    NASA Astrophysics Data System (ADS)

    Larson, N.; Liddick, S. N.; Prokop, C. J.; Kondev, F. G.; Kumar, S.; Crider, B. P.; Paulauskas, S. V.; Suchyta, S.

    2015-10-01

    In nuclear science, rapid changes in the structure of the atomic nucleus have been inferred with small changes in the neutron and proton numbers. These changes are manifested in variations of the low-energy level schemes of exotic isotopes. One region of the nuclear chart where rapid changes in deformation have been suggested based on the behavior of the first excited 2 + states is in neutron-rich nuclei near A = 110. Beta-decay spectroscopy is a sensitive and selective technique that can be used to investigate the low-energy level schemes exotic nuclei at low production rates. At the National Superconducting Cyclotron Laboratory (NSCL), a recently commissioned planar Ge double-sided strip detector (GeDSSD) is used in a novel application for these studies. Preliminary results from the decay of Tc isotopes in an experiment aimed at nuclei near A = 110 will be presented. This work was supported by the DOE NNSA DE-NA0000979 and the NSF Grant PHY1102511.

  12. Resonant germanium nanoantenna photodetectors.

    PubMed

    Cao, Linyou; Park, Joon-Shik; Fan, Pengyu; Clemens, Bruce; Brongersma, Mark L

    2010-04-14

    On-chip optical interconnection is considered as a substitute for conventional electrical interconnects as microelectronic circuitry continues to shrink in size. Central to this effort is the development of ultracompact, silicon-compatible, and functional optoelectronic devices. Photodetectors play a key role as interfaces between photonics and electronics but are plagued by a fundamental efficiency-speed trade-off. Moreover, engineering of desired wavelength and polarization sensitivities typically requires construction of space-consuming components. Here, we demonstrate how to overcome these limitations in a nanoscale metal-semiconductor-metal germanium photodetector for the optical communications band. The detector capitalizes on antenna effects to dramatically enhance the photoresponse (>25-fold) and to enable wavelength and polarization selectivity. The electrical design featuring asymmetric metallic contacts also enables ultralow dark currents (approximately 20 pA), low power consumption, and high-speed operation (>100 GHz). The presented high-performance photodetection scheme represents a significant step toward realizing integrated on-chip communication and manifests a new paradigm for developing miniaturized optoelectronics components.

  13. A tracking detector to study O(1 GeV) νμ CC interactions

    NASA Astrophysics Data System (ADS)

    Bernardini, P.; Cecchini, S.; Cindolo, F.; D'Antone, I.; Degli Esposti, L.; Lax, I.; Mandrioli, G.; Marsella, G.; Mauri, N.; Pasqualini, L.; Patrizii, L.; Pozzato, M.; Sirri, G.; Surdo, A.; Tenti, M.

    2017-03-01

    A tracking system composed of planes of triangular shape scintillator bars coupled to Silicon PhotoMultipliers in analog mode read-out has been developed for applications in neutrino experiments. A spatial resolution of O(1 mm) is required for the determination of momentum and charge of muons produced in νμ CC interactions at few GeV energy scale. The performance of the system has been studied by exposing it to charged particle beams at the CERN-PS. Preliminary results are discussed.

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

    SciTech Connect

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

    2007-02-05

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

  15. Effect of germanium dioxide on growth of Spirulina platensis

    NASA Astrophysics Data System (ADS)

    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.

  16. Well GeHP detector calibration for environmental measurements using reference materials

    NASA Astrophysics Data System (ADS)

    Tedjani, A.; Mavon, C.; Belafrites, A.; Degrelle, D.; Boumala, D.; Rius, D.; Groetz, J.-E.

    2016-12-01

    A well-type detector installed in the Modane underground Laboratory (LSM) can combine both low background and high detection efficiency and it is well suited for the analysis of small amounts of environmental samples. Reference materials such as IAEA-447 (moss-soil), IAEA-RG-Th1 and IAEA-RG-U1 were used for the detector calibration, owing to a chemical composition close to those of the environmental samples. Nevertheless, the matrix effects and the true coincidence summing effects must be corrected from the full energy peak efficiency (FEPE). The FEPE was performed for a wide range of energy by a semi-empirical method using Monte Carlo simulation (MCNP6), intended for environmental measurements such as lake sediments dating. In the well geometry, the true coincidence summing effects could be very important and correction factors have been computed in three different ways.

  17. GERDA phase II detectors: Behind the production and characterisation at low background conditions

    SciTech Connect

    Maneschg, Werner; Collaboration: GERDA Collaboration; and others

    2013-08-08

    The low background GERmanium Detector Array (GERDA) at Laboratori Nazionali del Gran Sasso (LNGS) is designed to search for the rare neutrinoless double beta decay (0νββ) in {sup 76}Ge. Bare germanium diodes are operated in liquid argon which is used as coolant, as passive and soon active as well shield against external radiation. Currently, Phase I of the experiment is running using ∼15 kg of co-axial High Purity Germanium diodes. In order to increase the sensitivity of the experiment 30 Broad Energy Germanium (BEGe) diodes will be added within 2013. This presentation reviews the production chain of the new BEGe detectors from isotopic enrichment to diode production and testing. As demonstrated all steps were carefully planned in order to minimize the exposure of the enriched germanium to cosmic radiation. Following this premise, acceptance and characterisation measurement of the newly produced diodes have been performed within the HEROICA project in the Belgian underground laboratory HADES close to the diode manufacturer. The test program and the results from a subset of the recently terminated GERDA Phase II BEGe survey will be presented.

  18. GERDA phase II detectors: Behind the production and characterisation at low background conditions

    NASA Astrophysics Data System (ADS)

    Maneschg, Werner; Gerda Collaboration

    2013-08-01

    The low background GERmanium Detector Array (GERDA) at Laboratori Nazionali del Gran Sasso (LNGS) is designed to search for the rare neutrinoless double beta decay (0νββ) in 76Ge. Bare germanium diodes are operated in liquid argon which is used as coolant, as passive and soon active as well shield against external radiation. Currently, Phase I of the experiment is running using ˜15 kg of co-axial High Purity Germanium diodes. In order to increase the sensitivity of the experiment 30 Broad Energy Germanium (BEGe) diodes will be added within 2013. This presentation reviews the production chain of the new BEGe detectors from isotopic enrichment to diode production and testing. As demonstrated all steps were carefully planned in order to minimize the exposure of the enriched germanium to cosmic radiation. Following this premise, acceptance and characterisation measurement of the newly produced diodes have been performed within the HEROICA project in the Belgian underground laboratory HADES close to the diode manufacturer. The test program and the results from a subset of the recently terminated GERDA Phase II BEGe survey will be presented.

  19. Nucleon-gold collisions at 200A GeV using tagged d + Au interactions in the PHOBOS detector

    DOE PAGES

    Back, B. B.; Nouicer, R.; Baker, M. D.; ...

    2015-09-23

    Forward calorimetry in the PHOBOS detector has been used to study charged hadron production in d+Au, p+Au, and n+Au collisions at √sNN =200GeV. The forward proton calorimeter detectors are described and a procedure for determining collision centrality with these detectors is detailed. The deposition of energy by deuteron spectator nucleons in the forward calorimeters is used to identify p+Au and n+Au collisions in the data. A weighted combination of the yield of p+Au and n+Au is constructed to build a reference for Au+Au collisions that better matches the isospin composition of the gold nucleus. The pT and centrality dependence ofmore » the yield of this improved reference system is found to match that of d+Au. The shape of the charged-particle transverse momentum distribution is observed to extrapolate smoothly from p+p¯ to central d+Au as a function of the charged-particle pseudorapidity density. The asymmetry of positively and negatively charged hadron production in p+Au is compared to that of n+Au. No significant asymmetry is observed at midrapidity. In conclusion, these studies augment recent results from experiments at the CERN Large Hadron Collider and BNL Relativistic Heavy Ion Collider facilities to give a more complete description of particle production in p+A and d+A collisions, essential for the understanding the medium produced in high-energy nucleus-nucleus collisions.« less

  20. Nucleon-gold collisions at 200A GeV using tagged d + Au interactions in the PHOBOS detector

    SciTech Connect

    Back, B. B.; Nouicer, R.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Becker, B.; Betts, R. R.; Bickley, A. A; Stienberg, P.; Ioradnova, A.; Pak, R.; Sukhanov, A.

    2015-09-23

    Forward calorimetry in the PHOBOS detector has been used to study charged hadron production in d+Au, p+Au, and n+Au collisions at √sNN =200GeV. The forward proton calorimeter detectors are described and a procedure for determining collision centrality with these detectors is detailed. The deposition of energy by deuteron spectator nucleons in the forward calorimeters is used to identify p+Au and n+Au collisions in the data. A weighted combination of the yield of p+Au and n+Au is constructed to build a reference for Au+Au collisions that better matches the isospin composition of the gold nucleus. The pT and centrality dependence of the yield of this improved reference system is found to match that of d+Au. The shape of the charged-particle transverse momentum distribution is observed to extrapolate smoothly from p+p¯ to central d+Au as a function of the charged-particle pseudorapidity density. The asymmetry of positively and negatively charged hadron production in p+Au is compared to that of n+Au. No significant asymmetry is observed at midrapidity. In conclusion, these studies augment recent results from experiments at the CERN Large Hadron Collider and BNL Relativistic Heavy Ion Collider facilities to give a more complete description of particle production in p+A and d+A collisions, essential for the understanding the medium produced in high-energy nucleus-nucleus collisions.

  1. Application of epithermal neutron activation in multielement analysis of silicate rocks employing both coaxial Ge(Li) and low energy photon detector systems

    USGS Publications Warehouse

    Baedecker, P.A.; Rowe, J.J.; Steinnes, E.

    1977-01-01

    The instrumental activation analysis of silicate rocks using epithermal neutrons has been studied using both high resolution coaxial Ge(Li) detectors and low energy photon detectors, and applied to the determination of 23 elements in eight new U.S.G.S. standard rocks. The analytical use X-ray peaks associated with electron capture or internal conversion processes has been evaluated. Of 28 elements which can be considered to be determinable by instrumental means, the epithermal activation approach is capable of giving improved sensitivity and precision in 16 cases, over the normal INAA procedure. In eleven cases the use of the low energy photon detector is thought to show advantages over convertional coaxial Ge(Li) spectroscopy. ?? 1977 Akade??miai Kiado??.

  2. Tensile strain mapping in flat germanium membranes

    SciTech Connect

    Rhead, S. D. Halpin, J. E.; Myronov, M.; Patchett, D. H.; Allred, P. S.; Wilson, N. R.; Leadley, D. R.; Shah, V. A.; Kachkanov, V.; Dolbnya, I. P.; Reparaz, J. S.; Sotomayor Torres, C. M.

    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. Investigation of adatom adsorption on single layer buckled germanium selenide

    NASA Astrophysics Data System (ADS)

    Arkın, H.; Aktürk, E.

    2016-12-01

    A recent study of Hu et al. [1] predicted that 2D single layer of asymmetric washboard germanium selenide is found to be stable and display semiconducting properties. Motivating from this study, we have shown that another phase, which is 2D buckled honeycomb germanium selenide, is also stable. This phase exhibits semiconducting behavior with a band gap of 2.29 eV. Furthermore, on the basis of the first principles, spin-polarized density functional calculations, we investigate the effect of selected adatoms adsorption on the b-GeSe single layer. The adatoms Se, Ge, S, Si, C, Br and P are chemisorbed with significant binding energy where this effects modify the electronic structure of the single layer buckled GeSe locally by tuning the band gap. Net integer magnetic moment can be achieved and b-GeSe attains half metallicity through the adsorption of Si, Ge, P and Br.

  4. Solution-Processed Germanium Nanowire-Positioned Schottky Solar Cells

    DTIC Science & Technology

    2011-04-01

    available soon. Solution-processed germanium nanowire-positioned Schottky solar cells Nanoscale Research Letters 2011, 6:287 doi:10.1186/1556-276X-6-287 Ju...DATES COVERED 00-00-2011 to 00-00-2011 4. TITLE AND SUBTITLE Solution-processed germanium nanowire-positioned Schottky solar cells 5a. CONTRACT...nanowire (GeNW)-positioned Schottky solar cell was fabricated by a solution process. A GeNW-containing solution was spread out onto asymmetric metal

  5. Ge profile from the growth of SiGe buried layers by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Godbey, D. J.; Ancona, M. G.

    1992-11-01

    X-ray photoelectron spectroscopy measurements were obtained and interpreted by a kinetic simulation to determine the germanium concentration profile of thin Si/SiGe heterostructures grown at 500 °C using elemental source molecular beam epitaxy. The primary finding is that there are significant segregation effects in these commonly grown structures which affect both the ``leading'' and ``trailing'' interfaces. Upon opening of the germanium shutter, the surface monolayer must be built up to a germanium composition of greater than 96% before the composition of the deposited alloy layer is equal to the flux composition for a Ge ratio of 0.3. This buildup causes the germanium depletion at the leading interface. Upon termination of the germanium flux, the incorporation of the germanium rich monolayer into the growing silicon cap layer causes a corresponding degradation of the trailing interface.

  6. Development of a Germanium Small-Animal SPECT System

    PubMed Central

    Johnson, Lindsay C.; Ovchinnikov, Oleg; Shokouhi, Sepideh; Peterson, Todd E.

    2015-01-01

    Advances in fabrication techniques, electronics, and mechanical cooling systems have given rise to germanium detectors suitable for biomedical imaging. We are developing a small-animal SPECT system that uses a double-sided Ge strip detector. The detector’s excellent energy resolution may help to reduce scatter and simplify processing of multi-isotope imaging, while its ability to measure depth of interaction has the potential to mitigate parallax error in pinhole imaging. The detector’s energy resolution is <1% FWHM at 140 keV and its spatial resolution is approximately 1.5 mm FWHM. The prototype system described has a single-pinhole collimator with a 1-mm diameter and a 70-degree opening angle with a focal length variable between 4.5 and 9 cm. Phantom images from the gantry-mounted system are presented, including the NEMA NU-2008 phantom and a hot-rod phantom. Additionally, the benefit of energy resolution is demonstrated by imaging a dual-isotope phantom with 99mTc and 123I without cross-talk correction. PMID:26755832

  7. Complementary metal-oxide semiconductor-compatible detector materials with enhanced 1550 nm responsivity via Sn-doping of Ge/Si(100)

    NASA Astrophysics Data System (ADS)

    Roucka, Radek; Beeler, Richard; Mathews, Jay; Ryu, Mee-Yi; Kee Yeo, Yung; Menéndez, José; Kouvetakis, John

    2011-05-01

    Previously developed methods used to grow Ge1-ySny alloys on Si are extended to Sn concentrations in the 1019-1020 cm-3 range. These concentrations are shown to be sufficient to engineer large increases in the responsivity of detectors operating at 1550 nm. The dopant levels of Sn are incorporated at temperatures in the 370-390 °C range, yielding atomically smooth layers devoid of threading defects at high growth rates of 15-30 nm/min. These conditions are far more compatible with complementary metal-oxide semiconductor processing than the high growth and processing temperatures required to achieve the same responsivity via tensile strain in pure Ge on Si. A detailed study of a detector based on a Sn-doped Ge layer with 0.25% (1.1 × 1020 cm-3) Sn range demonstrates the responsivity enhancement and shows much better I-V characteristics than previously fabricated detectors based on Ge1-ySny alloys with y = 0.02.

  8. Chalcogenide and germanium hybrid optics

    NASA Astrophysics Data System (ADS)

    Cogburn, Gabriel

    2011-11-01

    When choosing a material to design infrared optics, an optical designer has to decide which material properties are most important to what they are trying to achieve. Factors include; cost, optical performance, index of material, sensor format, manufacturability, mechanical mounting and others. This paper will present an optical design that is made for a 640×480, 17μm sensor and is athermalized by using the material properties of chalcogenide glass and Germanium (Ge). The optical design will be a 3-element, f1.0 optic with an EFL of 20mm at 10μm. It consists of two Ge spherical lenses and a middle chalcogenide aspheric element. By using Ge and chalcogenide, this design utilizes the high index of Ge and combines it with the lower dn/dt of chalcogenide glass to provide an athermalized design without the use of additional electro-optical compensation inside the assembly. This study will start from the optical design process and explain the mechanical and optical properties of the design, then show the manufacturing process of molding an aspheric chalcogenide element. After the three elements are manufactured, they will be assembled and tested throughout the temperature range of -40 to 85°C to compare optical performance to design expectations. Ultimately, this paper will show that a high performance, athermalized optical assembly is possible to manufacture at a lower cost with the use of combining different infrared materials that allow for spherical Ge lenses and only one aspherical chalcogenide element which can be produced in higher volumes at lower costs through glass molding technology.

  9. Low background IR detector and detector array evaluations

    NASA Technical Reports Server (NTRS)

    Goebel, J. H.; Jared, D. A.; Lee, J. H.; Mccreight, C. R.; Mckelvey, M. E.; Stafford, P. S.

    1983-01-01

    A technology program has been underway at Ames since 1978 to develop and evaluate detectors and integrated detector arrays for low-background astronomical applications. The approach is to evaluate existing (less than 24 micron) array technology under low-background conditions, with the aim of adapting and optimizing existing devices. For longer wavelengths, where the technology is much less mature, development is sponsored and devices are evaluated, in both discrete and array formats, for eventual applications. The status of this program has been reported previously. We rely on industrial and university sources for the detectors. Typically, after a brief functionality check in the supplier's laboratory, we work with the device at Ames to characterize its low-background performance. In the case of promising arrays or detectors, we conduct ground-based telescope testing to face the problems associated with real applications. A list of devices tested at Ames is given. In the array category, accumulation-mode charge-injection-devices (AMCIDs) appear repeatedly; this reflects our recent experience with the 2 x 64 and 16 x 16 arrays. Results from the 1 x 16 CID and InSb CCD have been reported. The status of our tests of the discrete Ge:x detectors from Lawrence Berkeley Laboratory are described below. Tests of a 1 x 2 switched sample photoconductor array are just beginning. A 32-channel CMOS multiplexer has been tested at 10 K. Low-temperature silicon MOSFETs and germanium JFETs have also been tested, primarily at Ball Aerospace. This paper describes results to date on three elements of this program: AMCID array, discrete Ge:Ga detectors, and Ge JFET preamplifiers.

  10. Novel metastable metallic and semiconducting germaniums.

    PubMed

    Selli, Daniele; Baburin, Igor A; Martoňák, Roman; Leoni, Stefano

    2013-01-01

    Group-IVa elements silicon and germanium are known for their semiconducting properties at room temperature, which are technologically critical. Metallicity and superconductivity are found at higher pressures only, Ge β-tin (tI4) being the first high-pressure metallic phase in the phase diagram. However, recent experiments suggest that metallicity in germanium is compatible with room conditions, calling for a rethinking of our understanding of its phase diagram. Missing structures can efficiently be identified based on structure prediction methods. By means of ab initio metadynamics runs we explored the lower-pressure region of the phase diagram of germanium. A monoclinic germanium phase (mC16) with four-membered rings, less dense than diamond and compressible into β-tin phase (tI4) was found. Tetragonal bct-5 appeared between diamond and tI4. mC16 is a narrow-gap semiconductor, while bct-5 is metallic and potentially still superconducting in the very low pressure range. This finding may help resolving outstanding experimental issues.

  11. Novel metastable metallic and semiconducting germaniums

    PubMed Central

    Selli, Daniele; Baburin, Igor A.; Martoňák, Roman; Leoni, Stefano

    2013-01-01

    Group-IVa elements silicon and germanium are known for their semiconducting properties at room temperature, which are technologically critical. Metallicity and superconductivity are found at higher pressures only, Ge β-tin (tI4) being the first high-pressure metallic phase in the phase diagram. However, recent experiments suggest that metallicity in germanium is compatible with room conditions, calling for a rethinking of our understanding of its phase diagram. Missing structures can efficiently be identified based on structure prediction methods. By means of ab initio metadynamics runs we explored the lower-pressure region of the phase diagram of germanium. A monoclinic germanium phase (mC16) with four-membered rings, less dense than diamond and compressible into β-tin phase (tI4) was found. Tetragonal bct-5 appeared between diamond and tI4. mC16 is a narrow-gap semiconductor, while bct-5 is metallic and potentially still superconducting in the very low pressure range. This finding may help resolving outstanding experimental issues. PMID:23492980

  12. Research progress of Si-based germanium materials and devices

    NASA Astrophysics Data System (ADS)

    Buwen, Cheng; Cheng, Li; Zhi, Liu; Chunlai, Xue

    2016-08-01

    Si-based germanium is considered to be a promising platform for the integration of electronic and photonic devices due to its high carrier mobility, good optical properties, and compatibility with Si CMOS technology. However, some great challenges have to be confronted, such as: (1) the nature of indirect band gap of Ge; (2) the epitaxy of dislocation-free Ge layers on Si substrate; and (3) the immature technology for Ge devices. The aim of this paper is to give a review of the recent progress made in the field of epitaxy and optical properties of Ge heterostructures on Si substrate, as well as some key technologies on Ge devices. High crystal quality Ge epilayers, as well as Ge/SiGe multiple quantum wells with high Ge content, were successfully grown on Si substrate with a low-temperature Ge buffer layer. A local Ge condensation technique was proposed to prepare germanium-on-insulator (GOI) materials with high tensile strain for enhanced Ge direct band photoluminescence. The advances in formation of Ge n+p shallow junctions and the modulation of Schottky barrier height of metal/Ge contacts were a significant progress in Ge technology. Finally, the progress of Si-based Ge light emitters, photodetectors, and MOSFETs was briefly introduced. These results show that Si-based Ge heterostructure materials are promising for use in the next-generation of integrated circuits and optoelectronic circuits. Project supported in part by the National Natural Science Foundation (Nos. 61036003, 61435013) and the Major State Basic Research Development Program of China (No. 2013CB632103).

  13. Germanium-doped crystalline silicon: Effects of germanium doping on boron-related defects

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaodong; Yu, Xuegong; Yang, Deren

    2014-09-01

    Recently it has been recognized that germanium (Ge) doping can be used for microelectronics and photovoltaic devices. This article reviews the recent results about the effects of Ge doping on boron-related defects in crystalline silicon. Behavior of Ge interacting with the acceptor dopants is also discussed therein. In addition, the article provides a comprehensive review on the effect of Ge doping to the formation of iron-boron pairs and boron-oxygen defects that is responsible for the light induced degradation (LID) of the carrier lifetime. The improvement silicon-based solar cells application from Ge doping is discussed as well, including the increment of cell efficiency and the power output of corresponding modules under sunlight illumination.

  14. Tunnel current across linear homocatenated germanium chains

    SciTech Connect

    Matsuura, Yukihito

    2014-01-28

    The electronic transport properties of germanium oligomers catenating into linear chains (linear Ge chains) have been theoretically studied using first principle methods. The conduction mechanism of a Ge chain sandwiched between gold electrodes was analyzed based on the density of states and the eigenstates of the molecule in a two-probe environment. Like that of silicon chains (Si chains), the highest occupied molecular orbital of Ge chains contains the extended σ-conjugation of Ge 4p orbitals at energy levels close to the Fermi level; this is in contrast to the electronic properties of linear carbon chains. Furthermore, the conductance of a Ge chain is expected to decrease exponentially with molecular length L. The decay constant β, which is defined as e{sup −βL}, of a Ge chain is similar to that of a Si chain, whereas the conductance of the Ge chains is higher than that of Si chains even though the Ge–Ge bond length is longer than the Si–Si bond length.

  15. Lithium drifted germanium system

    NASA Technical Reports Server (NTRS)

    Fjarlie, E. J.

    1969-01-01

    General characteristics of the lithium-drifted germanium photodiode-Dewar-preamplifier system and particular operating instructions for the device are given. Information is included on solving operational problems.

  16. Exceptional transport property in a rolled-up germanium tube

    NASA Astrophysics Data System (ADS)

    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.

  17. A dual-PIXE tomography setup for reconstruction of Germanium in ICF target

    NASA Astrophysics Data System (ADS)

    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.

  18. Influence of the Sb dopant distribution on far infrared photoconductivity in Ge:Sb blocked impurity band detectors

    SciTech Connect

    Bandaru, Jordana; Beeman, Jeffrey W.; Haller, Eugene E.; Samperi, Stacy; Haegel, Nancy M.

    2002-02-06

    Extended long wavelength response to {approx}200 {micro}m (50 cm{sup -1}) has been observed in Ge:Sb Blocked Impurity Band (BIB) detectors with N{sub D} {approx} 1 x 10{sup 16} cm{sup -3}. The cut-off wavelength increases from 150 {micro}m (65 cm{sup -1}) to 200 {micro}m (50 cm{sup -1}) with increasing bias. The responsivity at long wavelengths was lower than expected. This can be explained by considering the observed Sb diffusion profile in a transition region between the blocking layer and active layer. BIB modeling is presented which indicates that this Sb concentration profile increases the electric field in the transition region and reduces the field in the blocking layer. The depletion region consists partially of the transition region between the active and blocking layer, which could contribute to the reduced long wavelength response. The field spike at the interface is the likely cause of breakdown at a lower bias than expected.

  19. Next Generation Device Grade Silicon-Germanium on Insulator

    PubMed Central

    Littlejohns, Callum G.; Nedeljkovic, Milos; Mallinson, Christopher F.; Watts, John F.; Mashanovich, Goran Z.; Reed, Graham T.; Gardes, Frederic Y.

    2015-01-01

    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. PMID:25656076

  20. Using Fiber Optics to Measure Carrier Drift Velocity of Germanium at 40mK

    NASA Astrophysics Data System (ADS)

    Lam, Albert

    2010-11-01

    The Cryogenic Dark Matter Search (CDMS) uses ultrapure germanium detectors at milliKelvin temperatures to attempt to directly detect weakly interacting massive particles (WIMPs), a candidate for dark matter. When some particle interacts with the crystal structure, ionization and phonon signals are produced. Each particle interaction gives off a unique ratio of ionization signal to phonon signal. In this way, background noise can be separated from events that may involve WIMPs. Current germanium detectors are about the size of a hockey puck. If detectors can be made larger, there would be a greater probability of having a WIMP interaction. To make larger detectors, we need to better understand carrier transport processes in the germanium detectors. So, we measured the carrier drift velocity at 40milliKelvin, the temperature at which detectors operate. The carrier drift velocity gives us insight into how much impurity is present in the germanium detectors. We made this measurement using a fiber optics line. The fiber optics line allowed us to carry light from a 780nm laser diode at room temperature, into our dilution refrigerator and onto a germanium detector at 40milliKelvin. A laser diode allowed us to create electron-hole pairs on the surface of a germanium detector in a much more precise way than a radiation source.

  1. Direct band gap electroluminescence from bulk germanium at room temperature using an asymmetric fin type metal/germanium/metal structure

    SciTech Connect

    Wang, Dong Maekura, Takayuki; Kamezawa, Sho; Yamamoto, Keisuke; Nakashima, Hiroshi

    2015-02-16

    We demonstrated direct band gap (DBG) electroluminescence (EL) at room temperature from n-type bulk germanium (Ge) using a fin type asymmetric lateral metal/Ge/metal structure with TiN/Ge and HfGe/Ge contacts, which was fabricated using a low temperature (<400 °C) process. Small electron and hole barrier heights were obtained for TiN/Ge and HfGe/Ge contacts, respectively. DBG EL spectrum peaked at 1.55 μm was clearly observed even at a small current density of 2.2 μA/μm. Superlinear increase in EL intensity was also observed with increasing current density, due to superlinear increase in population of elections in direct conduction band. The efficiency of hole injection was also clarified.

  2. Reduction of phosphorus diffusion in germanium by fluorine implantation

    SciTech Connect

    El Mubarek, H. A. W.

    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.

  3. Integration of germanium waveguide photodetectors for intrachip optical interconnects

    NASA Astrophysics Data System (ADS)

    Rouviere, Mathieu; Halbwax, Mathieu; Cercus, Jean-Luc; Cassan, Eric; Vivien, Laurent; Pascal, Daniel; Heitzmann, Michel; Hartmann, Jean-Michel; Laval, Suzanne

    2005-07-01

    The main characteristics of germanium photodetectors integrated in silicon-on-insulator optical waveguides for intrachip optical interconnects are presented. The epitaxial Ge layers are grown on Si(001) by reduced-pressure chemical vapor deposition. The optical absorption of Ge layers is recorded from 1.2 to 1.7 µm and linked to the layer strain. The responsivity of an interdigitated metal-semiconductor-metal Ge photodetector has been measured. Light coupling from a slightly etched submicron rib silicon-on-insulator waveguide to a Ge photodetector is studied for two configurations: butt coupling and vertical coupling.

  4. Enhancement in device performance of hepta-layer coupled InGaAs quantum dot infrared detector by AuGe surface plasmons

    NASA Astrophysics Data System (ADS)

    Pandey, Sushil Kumar; Tyagi, Lavi; Ghadi, Hemant; Rawool, Harshal; Chakrabarti, Subhananda

    2016-09-01

    In this work, we have studied the effect of AuGe alloy nanoparticles deposition on properties of molecular beam epitaxy grown heptalayer coupled InGaAs 5.25 mono-layer quantum-dots (QDs) samples. AuGe 12 nm film was deposited using electron beam evaporator on these samples which were later annealed at 300 °C to create AuGe nanoparticles. SEM measurement confirms formation of AuGe nanoparticles which support surface Plasmon modes. The PL spectra at 20K confirms maximum enhancement of 53% in intensity of peak at ̴̴ 1123 nm for 300 °C annealed sample in comparison to as-grown (without nanoparticle) sample. Single pixel detectors were fabricated from asgrown and 300°C annealed nanoparticle sample using two level lithography and wet etching process. We have observed two-order and one-order augmentation in responsivity and detectivity from device having nanoparticles compared to the as-grown respectively at 80K. Peak detectivity of 4.2×107cm.Hz 1/2/W at 80K was observed for device having nanoparticles. Around 30% increment in spectral response having peak around 5μm at -1V bias for device having AuGe nanoparticles compared to the as-grown device was observed. The observed enhancement is due to increase light trapping or light scattering into the device by nanoparticles. Demonstration of this plasmonic-based detector will move forward the development of high-performance infrared QDs detectors.

  5. Study of the process e+e-→ω η π0 in the energy range √{s }<2 GeV with the SND detector

    NASA Astrophysics Data System (ADS)

    Achasov, M. N.; Aulchenko, V. M.; Barnyakov, A. Yu.; Beloborodov, K. I.; Berdyugin, A. V.; Berkaev, D. E.; Bogdanchikov, A. G.; Botov, A. A.; Dimova, T. V.; Druzhinin, V. P.; Golubev, V. B.; Kardapoltsev, L. V.; Kharlamov, A. G.; Koop, I. A.; Korol, A. A.; Kovrizhin, D. P.; Koshuba, S. V.; Kupich, A. S.; Lysenko, A. P.; Melnikova, N. A.; Martin, K. A.; Pakhtusova, E. V.; Obrazovsky, A. E.; Perevedentsev, E. A.; Rogovsky, Yu. A.; Serednyakov, S. I.; Silagadze, Z. K.; Shatunov, Yu. M.; Shatunov, P. Yu.; Shtol, D. A.; Skrinsky, A. N.; Surin, I. K.; Tikhonov, Yu. A.; Usov, Yu. V.; Vasiljev, A. V.; Zemlyansky, I. M.

    2016-08-01

    The process e+e-→ω η π0 is studied in the energy range 1.45-2.00 GeV using data with an integrated luminosity of 33 pb-1 accumulated by the SND detector at the e+e- collider VEPP-2000. The e+e-→ω η π0 cross section is measured for the first time. The cross section has a threshold near 1.75 GeV. Its value is about 2 nb in the energy range 1.8-2.0 GeV. The dominant intermediate state for the process e+e-→ω η π0 is found to be ω a0(980 ).

  6. Study of the solar anisotropy of cosmic ray primaries of about 200 GeV energy with the L3+C muon detector

    NASA Astrophysics Data System (ADS)

    L3 Collaboration; Achard, P.; Adriani, O.; Aguilar-Benitez, M.; van den Akker, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M. G.; Anderhub, H.; Andreev, V. P.; Anselmo, F.; Arefiev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay, L.; Bähr, J.; Baldew, S. V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.; Barillère, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco, R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B. L.; Biasini, M.; Biglietti, M.; Biland, A.; Blaising, J. J.; Blyth, S. C.; Bobbink, G. J.; Böhm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov, D.; Bourquin, M.; Braccini, S.; Branson, J. G.; Brochu, F.; Burger, J. D.; Burger, W. J.; Cai, X. D.; Capell, M.; Cara Romeo, G.; Carlino, G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Chamizo, M.; Chang, Y. H.; Chemarin, M.; Chen, A.; Chen, G.; Chen, G. M.; Chen, H. F.; Chen, H. S.; Chiarusi, T.; Chiefari, G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.; Colino, N.; Costantini, S.; de la Cruz, B.; Cucciarelli, S.; de Asmundis, R.; Déglon, P.; Debreczeni, J.; Degré, A.; Dehmelt, K.; Deiters, K.; della Volpe, D.; Delmeire, E.; Denes, P.; DeNotaristefani, F.; De Salvo, A.; Diemoz, M.; Dierckxsens, M.; Ding, L. K.; Dionisi, C.; Dittmar, M.; Doria, A.; Dova, M. T.; Duchesneau, D.; Duda, M.; Duran, I.; Echenard, B.; Eline, A.; El Mamouni, H.; Engler, A.; Eppling, F. J.; Extermann, P.; Faber, G.; Falagan, M. A.; Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson, T.; Fiandrini, E.; Field, J. H.; Filthaut, F.; Fisher, W.; Forconi, G.; Freudenreich, K.; Furetta, C.; Galaktionov, Yu.; Ganguli, S. N.; Garcia-Abia, P.; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z. F.; Grabosch, H. J.; Grenier, G.; Grimm, O.; Groenstege, H.; Gruenewald, M. W.; Guo, Y. N.; Gupta, S.; Gupta, V. K.; Gurtu, A.; Gutay, L. J.; Haas, D.; Haller, Ch.; Hatzifotiadou, D.; Hayashi, Y.; He, Z. X.; Hebbeker, T.; Hervé, A.; Hirschfelder, J.; Hofer, H.; Hoferjun, H.; Hohlmann, M.; Holzner, G.; Hou, S. R.; Huo, A. X.; Ito, N.; Jin, B. N.; Jindal, P.; Jing, C. L.; Jones, L. W.; de Jong, P.; Josa-Mutuberría, I.; Kantserov, V.; Kaur, M.; Kawakami, S.; Kienzle-Focacci, M. N.; Kim, J. K.; Kirkby, J.; Kittel, W.; Klimentov, A.; König, A. C.; Kok, E.; Korn, A.; Kopal, M.; Koutsenko, V.; Kräber, M.; Kuang, H. H.; Kraemer, R. W.; Krüger, A.; Kuijpers, J.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Le Goff, J. M.; Lei, Y.; Leich, H.; Leiste, R.; Levtchenko, M.; Levtchenko, P.; Li, C.; Li, L.; Li, Z. C.; Likhoded, S.; Lin, C. H.; Lin, W. T.; Linde, F. L.; Lista, L.; Liu, Z. A.; Lohmann, W.; Longo, E.; Lu, Y. S.; Luci, C.; Luminari, L.; Lustermann, W.; Ma, W. G.; Ma, X. H.; Ma, Y. Q.; Malgeri, L.; Malinin, A.; Maña, C.; Mans, J.; Martin, J. P.; Marzano, F.; Mazumdar, K.; McNeil, R. R.; Mele, S.; Meng, X. W.; Merola, L.; Meschini, M.; Metzger, W. J.; Mihul, A.; van Mil, A.; Milcent, H.; Mirabelli, G.; Mohanty, G. B.; Monteleoni, B.; Muanza, G. S.; Muijs, A. J. M.; Musy, M.; Nagy, S.; Nahnhauer, R.; Naumov, V. A.; Natale, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Nisati, A.; Novak, T.; Nowak, H.; Ofierzynski, R.; Organtini, G.; Pal, I.; Palomares, C.; Paolucci, P.; Paramatti, R.; Parriaud, J.-F.; Passaleva, G.; Patricelli, S.; Paul, T.; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix, D.; Petersen, B.; Piccolo, D.; Pierella, F.; Pieri, M.; Pioppi, M.; Piroué, P. A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofiev, D.; Qing, C. R.; Rahal-Callot, G.; Rahaman, M. A.; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P. G.; Ranieri, R.; Raspereza, A.; Ravindran, K. C.; Razis, P.; Rembeczki, S.; Ren, D.; Rescigno, M.; Reucroft, S.; Rewiersma, P.; Riemann, S.; Riles, K.; Roe, B. P.; Rojkov, A.; Romero, L.; Rosca, A.; Rosier-Lees, S.; Roth, S.; Rubio, J. A.; Ruggiero, G.; Rykaczewski, H.; Saidi, R.; Sakharov, A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Schäfer, C.; Schegelsky, V.; Schmitt, V.; Schoeneich, B.; Schopper, H.; Schotanus, D. J.; Sciacca, C.; Servoli, L.; Shen, C. Q.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shumilov, E.; Shvorob, A.; Son, D.; Souga, C.; Spillantini, P.; Steuer, M.; Stickland, D. P.; Stoyanov, B.; Straessner, A.; Sudhakar, K.; Sulanke, H.; Sultanov, G.; Sun, L. Z.; Suter, H.; Swain, J. D.; Szillasi, Z.; Tang, X. W.; Tarjan, P.; Tauscher, L.; Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, C.; Ting, Samuel C. C.; Ting, S. M.; Tonwar, S. C.; Tóth, J.; Trowitzsch, G.; Tully, C.; Tung, K. L.; Ulbricht, J.; Unger, M.; Valente, E.; Verkooijen, H.; Van de Walle, R. T.; Vasquez, R.; Vesztergombi, G.; Vetlitsky, I.; Viertel, G.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobiev, I.; Vorobyov, A. A.; Wadhwa, M.; Wang, R. G.; Wang, Q.; Wang, X. L.; Wang, X. W.; Wang, Z. M.; Weber, M.; van Wijk, R.; Wijnen, T. A. M.; Wilkens, H.; Wynhoff, S.; Xia, L.; Xu, Y. P.; Xu, J. S.; Xu, Z. Z.; Yamamoto, J.; Yang, B. Z.; Yang, C. G.; Yang, H. J.; Yang, M.; Yang, X. F.; Yao, Z. G.; Yeh, S. C.; Yu, Z. Q.; Zalite, An.; Zalite, Yu.; Zhang, C.; Zhang, F.; Zhang, J.; Zhang, S.; Zhang, Z. P.; Zhao, J.; Zhou, S. J.; Zhu, G. Y.; Zhu, R. Y.; Zhu, Q. Q.; Zhuang, H. L.; Zichichi, A.; Zimmermann, B.; Zöller, M.; Zwart, A. N. M.

    2008-09-01

    Context: Primary cosmic rays experience multiple deflections in the non-uniform galactic and heliospheric magnetic fields which may generate anisotropies. Aims: A study of anisotropies in the energy range between 100 and 500 GeV is performed. This energy range is not yet well explored. Methods: The L3 detector at the CERN electron-positron collider, LEP, is used for a study of the angular distribution of atmospheric muons with energies above 20 GeV. This distribution is used to investigate the isotropy of the time-dependent intensity of the primary cosmic-ray flux with a Fourier analysis. Results: A small deviation from isotropy at energies around 200 GeV is observed for the second harmonics at the solar frequency. No sidereal anisotropy is found at a level above 10-4. The measurements were performed in the years 1999 and 2000.

  7. A measurement method of a detector response function for monochromatic electrons based on the Compton scattering

    NASA Astrophysics Data System (ADS)

    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.

  8. Functionalization of Mechanochemically Passivated Germanium Nanoparticles via "Click" Chemistry

    NASA Astrophysics Data System (ADS)

    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. Detectors

    DOEpatents

    Orr, Christopher Henry; Luff, Craig Janson; Dockray, Thomas; Macarthur, Duncan Whittemore; Bounds, John Alan; Allander, Krag

    2002-01-01

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

  10. Interface-controlled layer exchange in metal-induced crystallization of germanium thin films

    NASA Astrophysics Data System (ADS)

    Hu, Shu; Marshall, Ann F.; McIntyre, Paul C.

    2010-08-01

    Low-temperature synthesis of polycrystalline germanium (poly-Ge) thin films is of great interest in thin-film photovoltaic and electronics applications. We demonstrate metal (Al)-induced crystallization to form poly-Ge thin films on both glass and polymer substrates at temperatures as low as 200 °C. An interfacial diffusion control layer, intentionally interposed between the Al and the underlying amorphous Ge (a-Ge) layer, is found to achieve layer exchange while suppressing uncontrolled Ge crystallization within the bilayer samples. Germanium thin films with micron-size grains and (111)-preferred orientation are prepared by controlled Ge nucleation and Ge lateral overgrowth of Al during a-Ge crystallization.

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

    NASA Astrophysics Data System (ADS)

    GERDA Collaboration; Agostini, M.; Allardt, 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.; Janicskó Csáthy, J.; 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.

    2017-05-01

    Internal contaminations of 238U, 235U and 232Th in the bulk of high purity germanium detectors are potential backgrounds for experiments searching for neutrinoless double beta decay of 76Ge. 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 226Ra, 227Ac and 228Th, the long-lived daughter nuclides of 238U, 235U and 232Th, respectively, have been derived. With these upper limits a background index in the energy region of interest from 226Ra and 228Th contamination is estimated which satisfies the prerequisites of a future ton scale germanium double beta decay experiment.

  12. A probe for neutron activation analysis in a drill hole using 252Cf, and a Ge(Li) detector cooled by a melting cryogen

    USGS Publications Warehouse

    Tanner, A.B.; Moxham, R.M.; Senftle, F.E.; Baicker, J.A.

    1972-01-01

    A sonde has been built for high-resolution measurement of natural or neutron-induced gamma rays in boreholes. The sonde is 7.3 cm in diameter and about 2.2 m in length and weighs about 16 kg. The lithium-compensated germanium semiconductor detector is stabilized at -185 to -188??C for as much as ten hours by a cryostatic reservoir containing melting propane. During periods when the sonde is not in use the propane is kept frozen by a gravity-fed trickle of liquid nitrogen from a reservoir temporarily attached to the cryostat section. A 252Cf source, shielded from the detector, may be placed in the bottom section of the sonde for anlysis by measurement of neutron-activation or neutron-capture gamma rays. Stability of the cryostat with changing hydrostatic pressure, absence of vibration, lack of need for power to the cryostat during operation, and freedom of orientation make the method desirable for borehole, undersea, space, and some laboratory applications. ?? 1972.

  13. Determination of Barium and selected rare-earth elements in geological materials employing a HpGe detector by radioisotope excited x-ray fluorescence

    SciTech Connect

    LaBrecque, J.J.; Preiss, I.L.

    1984-01-01

    The laterite material (geological) from Cerro Impacto was first studied by air radiometric techniques in the 1970's and was found to have an abnormally high radioactive background. Further studies showed this deposit to be rich in thorium, columbium, barium and rare-earth elements (mostly La, Ce, Pr and Nd). A similar work has been reported for the analysis of Brazil's lateritic material from Morro do Ferro to determine elemental compositions (including barium and rare-earth elements) and its relationship to the mobilization of thorium from the deposit using a Co-57 radioisotope source. The objective of this work was to develop an analytical method to determine barium and rare-earth element present in Venezuelan lateritic material from Cerro Impacto. We have employed a method before, employing a Si(Li) detector, but due to the low detection efficiencies in the rare-earth K-lines region (about 30 KeV - 40 KeV), we have decided to study the improvement in sensitivities and detection limits using an hyperpure germanium detector.

  14. Effects of a lactobacilli, oligosaccharide and organic germanium intake on the immune responses of mice.

    PubMed

    Nakamura, Takashi; Saito, Miki; Aso, Hisashi

    2012-01-01

    The organic germanium compound, Ge-132, has immune-modulating effects. We evaluated the symbiotic effects of Ge-132 with lactobacilli and oligosaccharide (LB/OS) on the immune responses of mice. The highest fecal IgA levels were observed in the mice receiving a low concentration of Ge-132 with LB/OS for 8 weeks. Our data suggest that LB/OS with a low concentration of Ge-132 stimulated the intestinal immunity.

  15. Response of silicon multistrip detectors and a cesium iodide scintillator to a calcium ion beam of 0.5 GeV/u

    NASA Astrophysics Data System (ADS)

    Codino, A.; Miozza, M.; Brunetti, M. T.; Checcucci, B.; Federico, C.; Grimani, C.; Lanfranchi, M.; Macchiaiolo, T.; Menichelli, M.; Maffei, P.; Plouin, F.; Vocca, H.

    1997-02-01

    We have constructed and operated charge preamplifiers for silicon strip detectors with a dynamic range extending from fractions of minimum ionising particle (MIP) up to 16 124 MIPs. These silicon detectors combined with time-of-flight counters and cesium iodide scintillator form a segment of the VENUS detector that has been exposed to a calcium beam of 0.5 GeV/u at the GSI accelerator. The aim of the instrument is the identification of all nuclides of the periodic table of the elements. Measurements of electronic noise, cross-talk among channels and energy deposit resolutions in various experimental conditions for silicon detectors are given. The measured light output of the CsI(Tl) crystal induced by calcium is compared with that extrapolated from lower-energy data of various nuclide species determined in other experiments. The charge resolution for calcium ions, determined by the {dE }/{dχ } detectors and TOF counters of time resolution of 55 ± 7 ps, amounts to 0.42 charge units (rms). Improvements in ion discrimination with respect to the present detector configuration are considered.

  16. Discovery of Photospheric Germanium in Hot DA White Dwarfs

    NASA Astrophysics Data System (ADS)

    Vennes, Stéphane; Chayer, Pierre; Dupuis, Jean

    2005-04-01

    We report the identification of Ge IV resonance lines in ultraviolet spectra of the hot DA white dwarfs Feige 24, G191-B2B, and GD 246. The lines originate in the stellar photosphere, and we measure low Ge/H abundance ratios ranging between -8.0 and -8.7. We also tentatively identify a resonance line of Sn IV blended with an Fe V line in the spectrum of G191-B2B. The presence of germanium extends our knowledge of the abundance pattern in hot white dwarfs beyond the iron group. The abundance ratio appears nearly solar, which implies either that the germanium abundance mixture in these stars has remained unaltered since leaving the main sequence or that diffusion processes (e.g., selective radiation pressure) are coincidentally reproducing a solar Ge/H ratio.

  17. Fabrication of core-shell nanostructures via silicon on insulator dewetting and germanium condensation: towards a strain tuning method for SiGe-based heterostructures in a three-dimensional geometry.

    PubMed

    Naffouti, Meher; David, Thomas; Benkouider, Abdelmalek; Favre, Luc; Cabie, Martiane; Ronda, Antoine; Berbezier, Isabelle; Abbarchi, Marco

    2016-07-29

    We report on a novel method for the implementation of core-shell SiGe-based nanocrystals combining silicon on insulator dewetting in a molecular beam epitaxy reactor with an ex situ Ge condensation process. With an in situ two-step process (annealing and Ge deposition) we produce two families of islands on the same sample: Si-rich, formed during the first step and, all around them, Ge-rich formed after Ge deposition. By increasing the amount of Ge deposited on the annealed samples from 0 to 18 monolayers, the islands' shape in the Si-rich zones can be tuned from elongated and flat to more symmetric and with a larger vertical aspect ratio. At the same time, the spatial extension of the Ge-rich zones is progressively increased as well as the Ge content in the islands. Further processing by ex situ rapid thermal oxidation results in the formation of a core-shell composition profile in both Si and Ge-rich zones with atomically sharp heterointerfaces. The Ge condensation induces a Ge enrichment of the islands' shell of up to 50% while keeping a pure Si core in the Si-rich zones and a ∼25% SiGe alloy in the Ge-rich ones. The large lattice mismatch between core and shell, the absence of dislocations and the islands' monocrystalline nature render this novel class of nanostructures a promising device platform for strain-based band-gap engineering. Finally, this method can be used for the implementation of ultralarge scale meta-surfaces with dielectric Mie resonators for light manipulation at the nanoscale.

  18. Fabrication of core-shell nanostructures via silicon on insulator dewetting and germanium condensation: towards a strain tuning method for SiGe-based heterostructures in a three-dimensional geometry

    NASA Astrophysics Data System (ADS)

    Naffouti, Meher; David, Thomas; Benkouider, Abdelmalek; Favre, Luc; Cabie, Martiane; Ronda, Antoine; Berbezier, Isabelle; Abbarchi, Marco

    2016-07-01

    We report on a novel method for the implementation of core-shell SiGe-based nanocrystals combining silicon on insulator dewetting in a molecular beam epitaxy reactor with an ex situ Ge condensation process. With an in situ two-step process (annealing and Ge deposition) we produce two families of islands on the same sample: Si-rich, formed during the first step and, all around them, Ge-rich formed after Ge deposition. By increasing the amount of Ge deposited on the annealed samples from 0 to 18 monolayers, the islands’ shape in the Si-rich zones can be tuned from elongated and flat to more symmetric and with a larger vertical aspect ratio. At the same time, the spatial extension of the Ge-rich zones is progressively increased as well as the Ge content in the islands. Further processing by ex situ rapid thermal oxidation results in the formation of a core-shell composition profile in both Si and Ge-rich zones with atomically sharp heterointerfaces. The Ge condensation induces a Ge enrichment of the islands’ shell of up to 50% while keeping a pure Si core in the Si-rich zones and a ˜25% SiGe alloy in the Ge-rich ones. The large lattice mismatch between core and shell, the absence of dislocations and the islands’ monocrystalline nature render this novel class of nanostructures a promising device platform for strain-based band-gap engineering. Finally, this method can be used for the implementation of ultralarge scale meta-surfaces with dielectric Mie resonators for light manipulation at the nanoscale.

  19. Germanium terminated (1 0 0) diamond.

    PubMed

    Sear, Michael J; Schenk, Alex K; Tadich, Anton; Spencer, Benjamin J; Wright, Christopher A; Stacey, Alastair; Pakes, Chris I

    2017-04-12

    An ordered germanium terminated (1 0 0) diamond surface has been formed and characterised using a combination of low energy electron diffraction and synchrotron-based core level photoemission spectroscopy. A number of preparation methods are explored, in each case inducing a two domain [Formula: see text] surface reconstruction. The surface becomes saturated with bonded germanium such that each [Formula: see text] unit cell hosts 1.26 Ge atoms on average, and possesses a negative electron affinity of  -0.71 eV.

  20. Comparative infrared study of silicon and germanium nitrides

    NASA Astrophysics Data System (ADS)

    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. Germanium terminated (1 0 0) diamond

    NASA Astrophysics Data System (ADS)

    Sear, Michael J.; Schenk, Alex K.; Tadich, Anton; Spencer, Benjamin J.; Wright, Christopher A.; Stacey, Alastair; Pakes, Chris I.

    2017-04-01

    An ordered germanium terminated (1 0 0) diamond surface has been formed and characterised using a combination of low energy electron diffraction and synchrotron-based core level photoemission spectroscopy. A number of preparation methods are explored, in each case inducing a two domain ≤ft(3× 1\\right) surface reconstruction. The surface becomes saturated with bonded germanium such that each ≤ft(3× 1\\right) unit cell hosts 1.26 Ge atoms on average, and possesses a negative electron affinity of  ‑0.71 eV.

  2. The Majorana Demonstrator: A search for neutrinoless double-beta decay of germanium-76

    SciTech Connect

    Elliott, S. R.; Boswell, M.; Goett, J.; Rielage, K.; Ronquest, M. C.; Xu, W.; Abgrall, N.; Chan, Y-D.; Hegai, A.; Martin, R. D.; Mertens, S.; Poon, A. W. P.; Aguayo, E.; Fast, J. E.; Hoppe, E. W.; Kouzes, R. T.; LaFerriere, B. D.; Orrell, J. L.; Overman, N. R.; Soin, A.; and others

    2013-12-30

    The MAJORANA collaboration is searching for neutrinoless double beta decay using {sup 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 ∼1 count/t-y or lower in the region of the signal. The MAJORANA collaboration, with funding support from DOE Office of Nuclear Physics and NSF Particle Astrophysics, is constructing the DEMONSTRATOR, an array consisting of 40 kg of p-type point-contact high-purity germanium (HPGe) detectors, of which ∼30 kg will be enriched to 87% in {sup 76}Ge. The DEMONSTRATOR is being constructed in a clean room laboratory facility at the 4850' level (4300 m.w.e.) of the Sanford Underground Research Facility (SURF) in Lead, SD. It utilizes a compact graded shield approach with the inner portion consisting of ultra-clean Cu that is being electroformed and machined underground. The primary aim of the DEMONSTRATOR is to show the feasibility of a future tonne-scale measurement in terms of backgrounds and scalability.

  3. 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.

    PubMed

    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).

  4. Improved WIMP-search reach of the CDMS II germanium data

    SciTech Connect

    Agnese, R.

    2015-10-12

    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. Furthermore, this improves the previous CDMS II result by a factor of 2.4 (2.7) for 60 (8.6) GeV/c2 WIMPs.

  5. Improved WIMP-search reach of the CDMS II germanium data

    DOE PAGES

    Agnese, R.

    2015-10-12

    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 andmore » 1.18×10–41 at 90% confidence for 60 and 8.6 GeV/c2 WIMPs, respectively. Furthermore, this improves the previous CDMS II result by a factor of 2.4 (2.7) for 60 (8.6) GeV/c2 WIMPs.« less

  6. Investigations of segregation phenomena in highly strained Mn-doped Ge wetting layers and Ge quantum dots embedded in silicon

    SciTech Connect

    Prestat, E. Porret, C.; Favre-Nicolin, V.; Tainoff, D.; Boukhari, M.; Bayle-Guillemaud, P.; Jamet, M.; Barski, A.

    2014-03-10

    In this Letter, we investigate manganese diffusion and the formation of Mn precipitates in highly strained, few monolayer thick, Mn-doped Ge wetting layers and nanometric size Ge quantum dot heterostructures embedded in silicon. We show that in this Ge(Mn)/Si system manganese always precipitates and that the size and the position of Mn clusters (precipitates) depend on the growth temperature. At high growth temperature, manganese strongly diffuses from germanium to silicon, whereas decreasing the growth temperature reduces the manganese diffusion. In the germanium quantum dots layers, Mn precipitates are detected, not only in partially relaxed quantum dots but also in fully strained germanium wetting layers between the dots.

  7. Measurement of K+ production cross section by 8 GeV protons using high energy neutrino interactions in the SciBooNE detector

    DOE PAGES

    Cheng, G.

    2011-07-28

    The SciBooNE Collaboration reports K+ production cross section and rate measurements using high energy daughter muon neutrino scattering data off the SciBar polystyrene (C8H8) target in the SciBooNE detector. The K+ mesons are produced by 8 GeV protons striking a beryllium target in Fermilab Booster Neutrino Beam line (BNB). Using observed neutrino and antineutrino events in SciBooNE, we measure d2σ/dpdΩ = (5.34 ±0.76) mb/(GeV/c x sr) for p + Be =K+ + X at mean K+ energy of 3.9 GeV and angle (with respect to the proton beam direction) of 3.7 degrees, corresponding to the selected K+ sample. Compared tomore » Monte Carlo predictions using previous higher energy K+ production measurements, this measurement, which uses the NUANCE neutrino interaction generator, is consistent with a normalization factor of 0.85 ± 0.12. This agreement is evidence that the extrapolation of the higher energy K+ measurements to an 8 GeV beam energy using Feynman scaling is valid. This measurement reduces the error on the K+ production cross section from 40% to 14%.« less

  8. Measurement of K+ production cross section by 8 GeV protons using high energy neutrino interactions in the SciBooNE detector

    SciTech Connect

    Cheng, G.

    2011-07-28

    The SciBooNE Collaboration reports K+ production cross section and rate measurements using high energy daughter muon neutrino scattering data off the SciBar polystyrene (C8H8) target in the SciBooNE detector. The K+ mesons are produced by 8 GeV protons striking a beryllium target in Fermilab Booster Neutrino Beam line (BNB). Using observed neutrino and antineutrino events in SciBooNE, we measure d2σ/dpdΩ = (5.34 ±0.76) mb/(GeV/c x sr) for p + Be =K+ + X at mean K+ energy of 3.9 GeV and angle (with respect to the proton beam direction) of 3.7 degrees, corresponding to the selected K+ sample. Compared to Monte Carlo predictions using previous higher energy K+ production measurements, this measurement, which uses the NUANCE neutrino interaction generator, is consistent with a normalization factor of 0.85 ± 0.12. This agreement is evidence that the extrapolation of the higher energy K+ measurements to an 8 GeV beam energy using Feynman scaling is valid. This measurement reduces the error on the K+ production cross section from 40% to 14%.

  9. Measurement of K+ production cross section by 8 GeV protons using high-energy neutrino interactions in the SciBooNE detector

    NASA Astrophysics Data System (ADS)

    Cheng, G.; Mariani, C.; Alcaraz-Aunion, J. L.; Brice, S. J.; Bugel, L.; Catala-Perez, J.; Conrad, J. M.; Djurcic, Z.; Dore, U.; Finley, D. A.; Franke, A. J.; Giganti, C.; Gomez-Cadenas, J. J.; Guzowski, P.; Hanson, A.; Hayato, Y.; Hiraide, K.; Jover-Manas, G.; Karagiorgi, G.; Katori, T.; Kobayashi, Y. K.; Kobilarcik, T.; Kubo, H.; Kurimoto, Y.; Louis, W. C.; Loverre, P. F.; Ludovici, L.; Mahn, K. B. M.; Masuike, S.; Matsuoka, K.; McGary, V. T.; Metcalf, W.; Mills, G. B.; Mitsuka, G.; Miyachi, Y.; Mizugashira, S.; Moore, C. D.; Nakajima, Y.; Nakaya, T.; Napora, R.; Nienaber, P.; Orme, D.; Otani, M.; Russell, A. D.; Sanchez, F.; Shaevitz, M. H.; Shibata, T.-A.; Sorel, M.; Stefanski, R. J.; Takei, H.; Tanaka, H.-K.; Tanaka, M.; Tayloe, R.; Taylor, I. J.; Tesarek, R. J.; Uchida, Y.; van de Water, R.; Walding, J. J.; Wascko, M. O.; White, H. B.; Yokoyama, M.; Zeller, G. P.; Zimmerman, E. D.

    2011-07-01

    The SciBooNE Collaboration reports K+ production cross section and rate measurements using high-energy daughter muon neutrino scattering data off the SciBar polystyrene (C8H8) target in the SciBooNE detector. The K+ mesons are produced by 8 GeV protons striking a beryllium target in Fermilab Booster Neutrino Beam line (BNB). Using observed neutrino and antineutrino events in SciBooNE, we measure (d2σ)/(dpdΩ)=(5.34±0.76)mb/(GeV/c×sr) for p+Be→K++X at mean K+ energy of 3.9 GeV and angle (with respect to the proton beam direction) of 3.7 degrees, corresponding to the selected K+ sample. Compared to Monte Carlo predictions using previous higher energy K+ production measurements, this measurement, which uses the NUANCE neutrino interaction generator, is consistent with a normalization factor of 0.85±0.12. This agreement is evidence that the extrapolation of the higher energy K+ measurements to an 8 GeV beam energy using Feynman scaling is valid. This measurement reduces the error on the K+ production cross section from 40% to 14%.

  10. Bridgman Growth of Germanium

    NASA Technical Reports Server (NTRS)

    Szofran, F. R.; Volz, M. P.; Cobb, S. D.; Motakef, S.

    1997-01-01

    The high-magnetic-field crystal growth facility at the Marshall Space Flight Center will be briefly described. This facility has been used to grow bulk germanium by the Bridgman technique in magnetic fields up to 5 Tesla. The results of investigations of ampoule material on the interface shape and thermal field applied to the melt on stability against convection will be discussed.

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

    PubMed

    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.

  12. Germanium Based Field-Effect Transistors: Challenges and Opportunities

    PubMed Central

    Goley, Patrick S.; Hudait, Mantu K.

    2014-01-01

    The performance of strained silicon (Si) as the channel material for today’s metal-oxide-semiconductor field-effect transistors may be reaching a plateau. New channel materials with high carrier mobility are being investigated as alternatives and have the potential to unlock an era of ultra-low-power and high-speed microelectronic devices. Chief among these new materials is germanium (Ge). This work reviews the two major remaining challenges that Ge based devices must overcome if they are to replace Si as the channel material, namely, heterogeneous integration of Ge on Si substrates, and developing a suitable gate stack. Next, Ge is compared to compound III-V materials in terms of p-channel device performance to review how it became the first choice for PMOS devices. Different Ge device architectures, including surface channel and quantum well configurations, are reviewed. Finally, state-of-the-art Ge device results and future prospects are also discussed. PMID:28788569

  13. Chemical synthesis of germanium nanoparticles with uniform size as anode materials for lithium ion batteries.

    PubMed

    Wang, Liangbiao; Bao, Keyan; Lou, Zhengsong; Liang, Guobing; Zhou, Quanfa

    2016-02-21

    A simple Mg-thermal reduction reaction is reported to synthesize germanium (Ge) nanoparticles with a uniform size at a low temperature of 400 °C in an autoclave. The as-prepared Ge nanoparticles exhibit promising anode applications in lithium ion batteries with high capacity and excellent cycling stability.

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

    PubMed

    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.

  15. Measurement of non-photonic electrons in p+p collisions at sNN = 200 GeV with reduced detector material in STAR

    SciTech Connect

    Jin,F.; Hallman,T.; et al.

    2009-05-13

    In this paper, we present our analysis of mid rapidity non-photonic electron (NPE) production at pT > 0.2 GeV/c in p+p collisions at √sNN = 200 GeV. The data set is ∼78 M TOF-triggered events taken from RHIC year 2008runs. Through the measurement of the e/π ratio, we find that the photonic background electrons from γ conversions are reduced by about a factor of 10 compared with those in STAR previous runs due to the absence of inner tracking detectors and the supporting materials. The dramatic increase of the signal-to-background ratio will allow us to improve the precision on extracting the charm cross section via its semi-leptonic decays to electrons.

  16. Present growth technology of silicon germanium alloys and possible advantages of microgravity growth

    NASA Technical Reports Server (NTRS)

    Stafsudd, O. M.

    1981-01-01

    The growth technology of Silicon-germanium (Si-Ge) alloys and the possible advantages of growth in microgravity is reviewed. The Si-Ge alloys have a continuous variation of bandgap energy from the germanium bandgap to the silicon bandgap. The unusual two slope behavior of Eg versus composition is due to the differences in the conduction band structure between Si and Ge. Below 17% (atomic), the germanium band structure dominates; and above it, the bands are "silicon like". It is found that the growth of Si-Ge alloys in microgravity is very attractive. In particular, the float zone method, in which a liquid zone of controlled starting composition, used to grow a large amount of useful alloy crystal. Large temperature gradients and relatively flat growth interfaces are necessary to obtain homogeneous crystal growth.

  17. Search for GeV gamma-ray bursts with the ARGO-YBJ detector: summary of eight years of observations

    SciTech Connect

    Bartoli, B.; Catalanotti, S.; Piazzoli, B. D'Ettorre; Di Girolamo, T.; Bernardini, P.; D'Amone, A.; De Mitri, I.; Bi, X. J.; Cao, Z.; Chen, S. Z.; Branchini, P.; Budano, A.; Camarri, P.; Cardarelli, R.; Sciascio, G. Di; Chen, T. L.; Danzengluobu; Creti, P.; Cui, S. W.; Dai, B. Z. E-mail: Piero.Vallania@to.infn.it; Collaboration: ARGO-YBJ Collaboration; and others

    2014-10-10

    The search for gamma-ray burst (GRB) emission in the energy range of 1-100 GeV in coincidence with the satellite detection has been carried out using the Astrophysical Radiation with Ground-based Observatory at YangBaJing (ARGO-YBJ) experiment. The high-altitude location (4300 m a.s.l.), the large active surface (∼6700 m{sup 2} of Resistive Plate Chambers), the wide field of view (∼2 sr, limited only by the atmospheric absorption), and the high duty cycle (>86%) make the ARGO-YBJ experiment particularly suitable to detect short and unexpected events like GRBs. With the scaler mode technique, i.e., counting all the particles hitting the detector with no measurement of the primary energy and arrival direction, the minimum threshold of ∼1 GeV can be reached, overlapping the direct measurements carried out by satellites. During the experiment lifetime from 2004 December 17 to 2013 February 7, a total of 206 GRBs occurring within the ARGO-YBJ field of view (zenith angle θ ≤ 45°) have been analyzed. This is the largest sample of GRBs investigated with a ground-based detector. Two light curve models have been assumed and since in both cases no significant excess has been found, the corresponding fluence upper limits in the 1-100 GeV energy region have been derived, with values as low as 10{sup –5} erg cm{sup –2}. The analysis of a subset of 24 GRBs with known redshift has been used to constrain the fluence extrapolation to the GeV region together with possible cutoffs under different assumptions on the spectrum.

  18. Germanium accumulation-mode charge-injection-device process

    NASA Technical Reports Server (NTRS)

    Moore, T. G.

    1981-01-01

    Gallium doped germanium is suitable for applications in the detection of far infrared radiation. Measurements were made on experimental photoconductors (PCs), accumulation mode charge injection devices (AMCIDs), and the SSPC (a switched, sampled PC alternative to the AMCID). The results indicate that the SSPC, which had a responsivity near 1.5 amp/watt, is desirable for use in two dimensional detector arrays.

  19. Crucible-free pulling of germanium crystals

    NASA Astrophysics Data System (ADS)

    Wünscher, Michael; Lüdge, Anke; Riemann, Helge

    2011-03-01

    Commonly, germanium crystals are grown after the Czochralski (CZ) method. The crucible-free pedestal and floating zone (FZ) methods, which are widely used for silicon growth, are hardly known to be investigated for germanium. The germanium melt is more than twice as dense as liquid silicon, which could destabilize a floating zone. Additionally, the lower melting point and the related lower radiative heat loss is shown to reduce the stability especially of the FZ process with the consequence of a screw-like crystal growth. We found that the lower heat radiation of Ge can be compensated by the increased convective cooling of a helium atmosphere instead of the argon ambient. Under these conditions, the screw-like growth could be avoided. Unfortunately, the helium cooling deteriorates the melting behavior of the feed rod. Spikes appear along the open melt front, which touch on the induction coil. In order to improve the melting behavior, we used a lamp as a second energy source as well as a mixture of Ar and He. With this, we found a final solution for growing stable crystals from germanium by using both gases in different parts of the furnace. The experimental work is accompanied by the simulation of the stationary temperature field. The commercially available software FEMAG-FZ is used for axisymmetric calculations. Another tool for process development is the lateral photo-voltage scanning (LPS), which can determine the shape of the solid-liquid phase boundary by analyzing the growth striations in a lateral cut of a grown crystal. In addition to improvements of the process, these measurements can be compared with the calculated results and, hence, conduce to validate the calculation.

  20. Nanoindentation-induced phase transformation and structural deformation of monocrystalline germanium: a molecular dynamics simulation investigation

    PubMed Central

    2013-01-01

    Molecular dynamics simulations were conducted to study the nanoindentation of monocrystalline germanium. The path of phase transformation and distribution of transformed region on different crystallographic orientations were investigated. The results indicate the anisotropic behavior of monocrystalline germanium. The nanoindentation-induced phase transformation from diamond cubic structure to β-tin-Ge was found in the subsurface region beneath the tool when indented on the (010) plane, while direct amorphization was observed in the region right under the indenter when the germanium was loaded along the [101] and [111] directions. The transformed phases extend along the < 110 > slip direction of germanium. The depth and shape of the deformed layers after unloading are quite different according to the crystal orientation of the indentation plane. The study results suggest that phase transformation is the dominant mechanism of deformation of monocrystalline germanium film in nanoindentation. PMID:23947487