The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
F. Dubecky - One of the best experts on this subject based on the ideXlab platform.
-
Performance of a Schottky surface barrier Radiation Detector based on bulk undoped semi-insulating GaAs at reduced temperature
IEEE Transactions on Nuclear Science, 2006Co-Authors: F. DubeckyAbstract:This work presents the performance of a Radiation Detector based on LEC semi-insulating GaAs with Au/Zn Schottky contact at variable temperature. The roles of the shaping time of a linear amplifier and operating voltage were studied. The performance of the Radiation Detector was calculated from pulse height spectra of 59.5 keV (/sup 241/Am) and 122.1 keV (/sup 57/Co). The optimal reverse bias voltage of the Radiation Detector, shaping time of the linear amplifier and temperature of Detector were investigated. The best charge collection efficiency of 98.2% at 303 K, relative energy resolution in FWHM 19.8% for 59.5 keV and 10.7% for 122.1 keV at 253 K were obtained.
-
Electrical and detection performance of Radiation Detector based on bulk semi-insulating InP:Fe: role of Detector volume
ASDAM 2000. Conference Proceedings. Third International EuroConference on Advanced Semiconductor Devices and Microsystems (Cat. No.00EX386), 2000Co-Authors: F. Dubecky, J. Darmo, M. Krempasky, V. Necas, M. Sekacova, P. Euthymiou, D. Korytar, O. Csabay, L. Harmatha, P.g. PelferAbstract:In this work study of bulk semi-insulating (SI) InP:Fe-based particle Detectors with emphasise to the role of Detector volume is presented. Detectors based on three various materials with active contact area between 0.3-5.5 mm/sup 2/ and various base length, 190, 400, and 1830 /spl mu/m were fabricated and tested. Obtained attenuation volume ranges between 0.12 and 5.7 mm/sup 3/. Detection performance of Detectors was tested at temperature 230 K. Charge collection efficiency and energy resolution tested using /spl gamma/-ray sources (/sup 241/Am, /sup 57/Co) are demonstrated. Problems of measurement at voltages >1 kV necessary for Detectors with long base (>500 /spl mu/m) and architecture of a "large volume" Radiation Detector based on bulk SI InP applicable in detection of solar neutrino are discussed.
-
Study of key physical parameters of bulk semi-insulating GaAs for Radiation Detector fabrication
Semiconducting and Insulating Materials 1998. Proceedings of the 10th Conference on Semiconducting and Insulating Materials (SIMC-X) (Cat. No.98CH3615, 1998Co-Authors: F. Dubecky, J. Darmo, M. Krempasky, V. Necas, P.g. Pelfer, P. Bohacek, M. SekacovaAbstract:Study of selected physical properties of bulk semi-insulating (SI) GaAs grown by LEC and VGF techniques, undoped and Cr-doped is presented. Conductivity, Hall, GDMS, I-V and C-V techniques were used for material and Radiation Detector characterisation. Detection performances of Detectors have been tested using /sup 57/Co source of 122 keV gamma rays. Correlation between the physical properties of base materials and performances of Detectors is presented. Physical parameters suitable for estimation of the Detector grade bulk SI GaAs are discussed.
Kanai S. Shah - One of the best experts on this subject based on the ideXlab platform.
-
Thallium Bromide Nuclear Radiation Detector Development
IEEE Transactions on Nuclear Science, 2009Co-Authors: Alexei V. Churilov, Guido Ciampi, Leonard J. Cirignano, William M. Higgins, Fred Olschner, Kanai S. ShahAbstract:Thallium bromide (TlBr) is a dense, high-Z, wide bandgap semiconductor that has potential as an efficient, compact, room temperature nuclear Radiation Detector. In this paper we report on our recent progress in TlBr nuclear Detector development. In particular, improvements in material purification have led to an order of magnitude increase in the mobility-lifetime product of electrons, (mutau)e, to as high as 5 times 10-3 cm2/V. This has enabled much thicker Detectors with good charge collection to be fabricated. We fabricated and tested small pixel TlBr arrays up to 10 mm thick. The energy resolution ~2% FWHM at 662 keV was recorded with 5-10 mm thick devices without 3-D spectral correction. We also investigated the long-term Detector stability and were able to constantly operate a thin (0.5 mm) Detector for five months at -18degC, under an electric field and with irRadiation.
-
Thallium bromide nuclear Radiation Detector development
2008 IEEE Nuclear Science Symposium Conference Record, 2008Co-Authors: Alexei V. Churilov, Guido Ciampi, Leonard J. Cirignano, William M. Higgins, Fred Olschner, Kanai S. ShahAbstract:Thallium bromide (TlBr) is a dense, high-Z, wide band gap semiconductor that has potential as an efficient, compact, room temperature nuclear Radiation Detector. In this paper we report on our recent progress in TlBr nuclear Detector development. In particular, improvements in material purification have led to an order of magnitude increase in the mobility-lifetime product of electrons, (μτ)e, to as high as 5×10−3 cm2/V. This has enabled much thicker Detectors with good charge collection to be fabricated. We fabricated and tested small pixel TlBr arrays up to 10 mm thick. The energy resolution ∼2% FWHM at 662 keV was recorded with 5–10 mm thick devices without 3D spectral correction. We also investigated the longterm Detector stability and were able to constantly operate a thin (0.5 mm) Detector for 5 months at −18 °C, under an electric field and with irRadiation.
M.m. Hamada - One of the best experts on this subject based on the ideXlab platform.
-
Influence of crystalline surface quality on TlBr Radiation Detector performance
IEEE Transactions on Nuclear Science, 2005Co-Authors: I.b. Oliveira, F.e. Costa, P.k. Kiyohara, M.m. HamadaAbstract:In this study, TlBr Detectors were fabricated from crystals purified by the multipass zone refining and grown by the Bridgman method. Detectors were prepared using TlBr 0.3-mm-thick wafers, with surface submitted to different mechanical and chemical treatments. Optical microscopy and scanning electron microscopy evaluated the TlBr wafers surface quality. To analyze the surface quality influence in the Detector response, systematic measurements of the pulse height spectra and energy resolution were carried out for each prepared Radiation Detector. The Radiation response for these Detectors was performed under /sup 241/Am gamma Radiation excitation at room temperature. The influence of the surface quality of the TlBr wafer on its performance as a Radiation Detector was observed.
-
Influence of crystalline surfaces on the TlBr Radiation Detector performance
IEEE Symposium Conference Record Nuclear Science 2004., 2004Co-Authors: I.b. Oliveira, F.e. Costa, P.k. Kiyohara, M.m. HamadaAbstract:Thallium bromide (TlBr) is an important material for room temperature Detectors. Due to its high photoelectric absorption efficiency and large band gap, thallium bromide is a good candidate for X- and gamma-ray spectrometry. In this study, TlBr Detectors were fabricated from the crystals purified by the multipass zone refining and grown by the Bridgman method. Detectors were prepared using TlBr wafers of about 0.3 mm thick, with surface submitted at different mechanical and chemical treatments. The results of surface quality of TlBr wafers, evaluated by scanning electron microscopy, are presented. Spectrometric performance of the TlBr Detector was assessed by excitation with 241Am gamma-ray source at room temperature. The dependence of the Radiation on the Detector was affected by the condition of the crystalline surface. This study has important implications for adequate processing of TlBr surfaces for Radiation Detector applications
Koan Sik Joo - One of the best experts on this subject based on the ideXlab platform.
-
Performance characteristics of a silicon photomultiplier based compact Radiation Detector for Homeland Security applications
Nuclear Instruments and Methods in Physics Research Section A: Accelerators Spectrometers Detectors and Associated Equipment, 2015Co-Authors: Hye Min Park, Koan Sik JooAbstract:A next-generation compact Radiation Detector was studied for more accurate measurement of Radiation and for improvement of Detector reliability for the purpose of developing Radiation protection technology and military applications. The previously used Radiation Detector had some limitations due to its bulky size, limited range and its environment for Radiation measurement. On the other hand, the compact Radiation Detector examined in this study utilizes a silicon photomultiplier which appears to be more suitable for this application because of its physical superiority characterized by its small size, high sensitivity, and durability. Accordingly, a SiPM based scintillation Detector has been developed as part of this basic study of military Radiation Detectors. The Detector has been tested for its ability to obtain the operating characteristics of a sensor and analyzed with variations of parameter values and for efficiency of detection in accordance with its ability to measure Radiation in the environment. Two SiPM based Scintillation Detectors with LYSO, BGO and CsI:Tl scintillators were developed and the Detectors were analyzed by a number of operating characteristics such as reverse bias, operating temperature and high magnetic field, that depend on environmental changes in Radiation measurement. The Photon count rate and spectra were compared for these three scintillators. We found that there were variations in the Radiation detection which were characterized by reverse bias, temperature and high magnetic field. It was also found that there was an 11.9% energy resolution for the LYSO, 15.5% for BGO and 13.5% for CsI:Tl using Array SiPM, and 18% for CsI:Tl energy resolution using single SiPM when we measured energy resolution of 511 keV for 22Na. These results demonstrate the potential widespread use of SiPM based compact Radiation Detectors for Homeland Security applications.
-
Design of a silicon photomultiplier based compact Radiation Detector for Homeland Security screening
2013 3rd International Conference on Advancements in Nuclear Instrumentation Measurement Methods and Their Applications ANIMMA 2013, 2013Co-Authors: Hye Min Park, Hong Kyu Lee, Sang June Jeon, Koan Sik JooAbstract:Next-generation compact Radiation Detector was studied for more accurate measurement of Radiation and improvement of reliability of the Detector with purpose of developing of Radiation protection technology and military application. The Radiation Detector which was used previously had some limitations due to the bulky size, limited range and the environment of Radiation measurement. On the other hand, the compact Radiation Detector under this study which has adopted the silicon photomultiplier seems to be suitable for the application because of its physical excellence which are characterized by its small size, high sensitivity and durabili0074y. Accordingly, a SiPM based Scintillation Detector has been made as a part of basic study of military Radiation Detector development. The Detector has been tested for obtaining the operating characteristics of a sensor and analyzed with variation of parameter values and the efficiency of detection in accordance with the factor of measurement environment of Radiation. The two SiPM based Scintillation Detectors with the LYSO, BGO and CsI:Tl scintillator were made and the Detectors were analyzed with the variation of operating characteristics as reverse bias, operating temperature and high magnetic field that are depend on environmental changes of Radiation measurement. The results of three scintillators for a photon count rate and spectra were compared with each other. It was found that there are variations of Radiation detection which are characterized by reverse bias, temperature and high magnetic field. Also, It was found that there were the 11.9 % for the LYSO, 15.5 % for BGO and 13.5 % for CsI:Tl energy resolution using array SiPM, and 18 % for CsI:Tl energy resolution using single SiPM, respectively when we measured energy resolution of 511keV for 22 Na. The results demonstrate the potential of SiPM based compact Radiation Detector to be used widely for Homeland Security applications. © 2013 IEEE.
Y. Hiratate - One of the best experts on this subject based on the ideXlab platform.
-
Temperature characteristics of the Radiation Detector using the TlBr crystals
IEEE Transactions on Nuclear Science, 1999Co-Authors: T. Shoji, K. Hitomi, O. Muroi, T. Suehiro, Y. HiratateAbstract:The Radiation Detector was fabricated from the TlBr crystals grown by the TMZ (travelling molten zone) method and the FWHM and transit time of electrons and holes were measured as a function of temperature. The TlBr Radiation Detector shows the best response characteristics at about 313 K (3.19 K/sup -1/) in cases where holes mainly contributed to the output pulses. However, for temperatures higher than 300 K (3.33 K/sup -1/), the FWHM for /sup 241/Am /spl alpha/-particles (5.48 MeV) becomes worse. An activation energy of about 0.90 eV has been deduced from the resistivity measurement.
-
Response characteristics of the TlBr Radiation Detector as a function of the Detector temperature
1998 IEEE Nuclear Science Symposium Conference Record. 1998 IEEE Nuclear Science Symposium and Medical Imaging Conference (Cat. No.98CH36255), 1998Co-Authors: T. Shoji, K. Hitomi, T. Suehiro, Y. HiratateAbstract:The Radiation Detectors were fabricated from the TlBr crystals grown by TMZ method and the FWHM and transit time of electrons and holes were measured as a function of the Detector temperature. The TlBr Radiation Detector shows the best response characteristics at about 320 K for holes. At the temperature of 330 K or above, the transit time and FWHM for the /sup 241/Am /spl alpha/-particle peak become worse. On the other hand, in the case of electron, the spectrum becomes worse with increasing the temperature form 150 K to 380 K. In the case, we can deduce an activation energy of about 0.20 eV for holes and about 0.10 for electron from the temperature dependence of the carrier transit time.
-
Fabrication of Radiation Detector using PbI/sub 2/ crystal
IEEE Transactions on Nuclear Science, 1995Co-Authors: T. Shoji, T. Suehiro, K. Ohba, Y. HiratateAbstract:Radiation Detectors have been fabricated from lead iodide (PbI/sub 2/) crystals grown by two methods: zone melting and Bridgman methods. In response characteristics of the Detector fabricated from crystals grown by the zone melting method, a photopeak for /spl gamma/-rays from an /sup 241/Am source (59.5 keV) has been clearly observed with applied Detector bias of 500 V at room temperature. The hole drift mobility is estimated to be about 5.5 cm/sup 2//Vs from measurement of pulse rise time for 5.48 MeV /spl alpha/-rays from /sup 241/Am. By comparing the Detector bias versus saturated peak position of the PbI/sub 2/ Detector with that of the CdTe Detector, the average energy for producing electron-hole pairs is estimated to be about 8.4 eV for the PbI/sub 2/ crystal. A Radiation Detector fabricated from PbI/sub 2/ crystals grown by the Bridgman method, however, exhibited no response for /spl gamma/-rays.
-
Properties of CdTe(Cl) crystal used for Radiation Detector
IEEE Conference on Nuclear Science Symposium and Medical Imaging, 1992Co-Authors: T. Shoji, T. Suehiro, K. Ohba, H. Onabe, Y. HiratateAbstract:A new method of growth of CdTe crystal doped with chlorine using radio-frequency THM which can provide excellent uniformity of Cl atoms for compensating the cadmium vacancies in CdTe crystal has been developed. Using the crystal grown by this method, a large number of Radiation Detectors which exhibit the same characteristics can be produced from one CdTe ingot. The authors discuss the relationship between the response characteristics of a gamma -ray Detector and crystal properties studied by photoluminescence and SIMS measurements. The response property of the Radiation Detector becomes worse as the intensity of the 1.554 eV emission line increases. This 1.554 eV emission line, which is mainly observed in the OR-THM crystals, is ascribed to the chlorine impurity.
