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Academic literature on the topic 'High purity germanium detectors'
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Dissertations / Theses on the topic "High purity germanium detectors"
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Ginsz, Michaël. "Characterization of high-purity, multi-segmented germanium detectors." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAE047/document.
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L’apparition de la segmentation électrique des détecteurs au GeHP et de l’électronique numérique a ouvert la voie à des applications prometteuses, telles que le tracking γ, l’imagerie γ ou la mesure bas bruit de fond, pour lesquelles une connaissance fine de la réponse du détecteur est un atout. L’IPHC a développé une table de scan utilisant un faisceau collimaté, qui sonde la réponse d’un détecteur dans tout son volume en fonction de la localisation de l’interaction. Elle est conçue pour utiliser une technique innovante de scan 3D, le Pulse Shape Comparison Scan, qui a été d’abord simulée afin de démontrer son efficacité. Un détecteur AGATA a été scanné de manière approfondie. Des scan 2D classiques ont permis, entre autres, de mettre en évidence des effets locaux de modification de la collection des charges, liés à la segmentation. Pour la première fois, une base de données 3D, complète, de formes d’impulsions fonction de la position d’interaction a été établie. Elle permettra notamment d’améliorer les performances du spectromètre AGATA<br>Recent developments of electrical segmentation of HPGe detectors, coupled with digital electronics have led to promising applications such as γ-ray tracking, γ-ray imaging or low-background measurements which will benefit from a fine knowledge of the detector response. The IPHC has developed a new scanning table which uses a collimated γ-ray beam to investigate the detector response as a function of the location of the γ-ray interaction. It is designed to use the Pulse Shape Comparison Scan technique, which has been simulated in order to prove its efficiency. An AGATA detector has been thoroughly scanned. 2D classical scans brought out, for example, local charge collection modification effects such as charge sharing, due to the segmentation. For the first time, a 3D, complete pulse-shape database has been established. It will especially allow to improve the overall AGATA array performances
2
Colosimo, Samantha. "The characterisation of AGATA high purity germanium detectors for pulse shape analysis." Thesis, University of Liverpool, 2013. http://livrepository.liverpool.ac.uk/11077/.
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Gamma-ray spectroscopy is an essential tool in the study of nuclear phenomenon. The study of exotic nuclei and nuclear states have been used to expand the nuclear chart as well as understand the origin of the universe. Large volume high purity germanium arrays, very high beam intensities and more recently exotic beams have lead to new understanding of nuclear physics. The Advanced Gamma Tracking Array (AGATA) aims to utilise high purity germanium (HPGe) detectors in order to achieve a dramatic increase in efficiency over current spectrometers. The work detailed in this thesis shows a highly detailed characterisation of two AGATA asymmetric capsules of the same shape in order to test and compare performances. Detector A004 was acceptance tested and scanned at the University of Liverpool in February 2010. Detector A006 was scanned between April and September 2010. Resolution, efficiency and charge collection parameters have been studied, comparing these two detector. The results of the comparison show an excellent agreement between the performance of the two detectors. The depletion rate of the detectors has also been compared quantitatively indicating the dependence of depletion on impurity concentration of the capsules. An experimental pulse shape database was generated for detector A006. The sensitivity of the detector response was quantified indicating the regions of the detector of high variation in pulse shape response. The AGATA detector library, which used to simulate the detector response for pulse shape analysis, is compared with this database. The position resolution achieved between the two data sets has been calculated. The combination of the detailed comparison and characterisation of the detector with the study of the simulate database will provide the AGATA collaboration with useful information to improve detector simulations in the further for pulse shape analysis.
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Nelson, Justin Matthew 1981. "Total-to-peak ratios of high purity germanium gamma ray detector." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32746.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics; and, (S.B.)--Massachusetts Institute of Technology, Dept. of Mathematics, 2004.<br>MIT Institute Archives copy: leaves 2-22 bound in reverse order.<br>Includes bibliographical references (leaf 22).<br>This study is concerned with the percentage of [gamma]-rays of a certain energy having their energy correctly measured by a high purity Germanium [gamma]-ray detector. The ratio between the total counts and the counts within the energy peak (total-to-peak ratio) is determined for seven energies ranging from 89 keV to 1275 keV. A Monte Carlo based on the physical parameters of the detector was used to extrapolate between these points and after an energy independent scaling factor fit the data with a reduced [chi]² slightly below 1. The same experiment was repeated with a lead brick and then a β detector near the Ge detector and these objects were found to not have an effect on the total-to-peak ratios within the precision of the experiment.<br>by Justin Matthew Nelson.<br>S.B.
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Gamir, Luis Palafox. "A new method for the determination of the entry position of #gamma#-rays in high purity germanium detectors by current pulse analysis." Thesis, Cranfield University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387640.
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Palafox, Gamir Luis. "A new method for the determination of the entry position of y-rays [gamma rays] in high purity germanium detectors by current pulse analysis." Thesis, Cranfield University, 1997. http://hdl.handle.net/1826/850.
Full textAbstract:
A new method for determining the entry point of gamma-rays in closed ended HPGe
detectors has been developed. Exploiting the position dependence shown by the
current pulses generated when a gamma-ray interacts with the detector, it is possible
to electronically divide the crystal in the radial coordinate and thus increase the
effective granularity of the detector.
Position resolution is particularly important for correcting the Doppler peak
broadening observed in many in-beam gamma-spectroscopy experiments. Position resolution
within coaxial crystals is accomplished by combining the angular information
gained by segmenting the outer contact with the determination of the event
radius by current pulse shape analysis.
With increasing gamma-energy, more than one interaction is in general required
to completely stop a gamma-ray in a germanium detector. The concept of a main
interaction, defined as that depositing the largest fraction of the original gamma-energy,
is introduced and seen to be the dominant contribution to the event current pulses.
A Monte Carlo simulation for the positions and energies of the interactions in an
event has been performed in order to establish the physical limits for the position
resolution that can be measured in a segmented CLUSTER module. A varying
fraction of events, from 55% at a gamma-energy of 400 keV to 85% at 1800 keV, have
their main interaction within 5 mm from the entry point. The position of the
main interaction can therefore be successfully used to measure the entry position
of the gamma-ray in the detector.
In order to provide high quality charge/energy and current outputs from the
detector signal, a new preamplifier for large volume HPGe detectors has been
developed. The intrinsic equivalent noise contribution from the preamplifier was
measured at 0.65 keV + 35 eV /pF. The measured energy resolution when the
input FET is operated at cryogenic temperature is 2.30 keV at 1333 keV with
3 μs shaping time.
Using this preamplifier and the first prototype of a two-fold segmented
CLUSTER module, a radial resolution of ±4mm has been measured with the
new method both at 662 and 1333 keV. The method can be incorporated into
an analogue electronic circuit and is therefore directly applicable in in-beam gamma-
spectroscopy experiments.
6
Palafox, Gamir Luis. "A new method for the determination of the entry position of γ-rays [gamma rays] in high purity germanium detectors by current pulse analysis". Thesis, Cranfield University, 1997. http://dspace.lib.cranfield.ac.uk/handle/1826/850.
Full textAbstract:
A new method for determining the entry point of gamma-rays in closed ended HPGe detectors has been developed. Exploiting the position dependence shown by the current pulses generated when a gamma-ray interacts with the detector, it is possible to electronically divide the crystal in the radial coordinate and thus increase the effective granularity of the detector. Position resolution is particularly important for correcting the Doppler peak broadening observed in many in-beam gamma-spectroscopy experiments. Position resolution within coaxial crystals is accomplished by combining the angular information gained by segmenting the outer contact with the determination of the event radius by current pulse shape analysis. With increasing gamma-energy, more than one interaction is in general required to completely stop a gamma-ray in a germanium detector. The concept of a main interaction, defined as that depositing the largest fraction of the original gamma-energy, is introduced and seen to be the dominant contribution to the event current pulses. A Monte Carlo simulation for the positions and energies of the interactions in an event has been performed in order to establish the physical limits for the position resolution that can be measured in a segmented CLUSTER module. A varying fraction of events, from 55% at a gamma-energy of 400 keV to 85% at 1800 keV, have their main interaction within 5 mm from the entry point. The position of the main interaction can therefore be successfully used to measure the entry position of the gamma-ray in the detector. In order to provide high quality charge/energy and current outputs from the detector signal, a new preamplifier for large volume HPGe detectors has been developed. The intrinsic equivalent noise contribution from the preamplifier was measured at 0.65 keV + 35 eV /pF. The measured energy resolution when the input FET is operated at cryogenic temperature is 2.30 keV at 1333 keV with 3 μs shaping time. Using this preamplifier and the first prototype of a two-fold segmented CLUSTER module, a radial resolution of ±4mm has been measured with the new method both at 662 and 1333 keV. The method can be incorporated into an analogue electronic circuit and is therefore directly applicable in in-beam gamma-spectroscopy experiments.
7
Volynets, Oleksandr [Verfasser], Bela [Akademischer Betreuer] Majorovits, Peter [Akademischer Betreuer] Fierlinger, and Alejandro [Akademischer Betreuer] Ibarra. "Methods to improve and understand the sensitivity of high purity germanium detectors for searches of rare events / Oleksandr Volynets. Gutachter: Peter Fierlinger ; Alejandro Ibarra. Betreuer: Bela Majorovits." München : Universitätsbibliothek der TU München, 2012. http://d-nb.info/1025337832/34.
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Ljungvall, Joa. "Characterisation of the Neutron Wall and of Neutron Interactions in Germanium-Detector Systems." Doctoral thesis, Uppsala University, Department of Nuclear and Particle Physics, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5845.
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<p>A Monte Carlo simulation of the Neutron Wall detector system has been performed using Geant4, in order to define optimum conditions for the detection and identification of multiple neutrons. Emphasis was put on studying the scattering of neutrons between different detectors, which is the main source of the apparent increase of the number of detected neutrons. The simulation has been compared with experimental data. The quality of neutron gated γ-ray spectra was improved for both two- and three-neutron evaporation channels. The influence of small amounts of γ rays mis-interpreted as neutrons was investigated. It was found that such γ rays dramatically reduce the quality of neutron gated γ-ray spectra.</p><p>The interaction properties of fast neutrons in a closed-end coaxial and a planar high-purity germanium detector (HPGe) were studied. Digitised waveforms of HPGe preamplifier signals were recorded for time-of-flight separated neutrons and γ rays, emitted by a <sup>252</sup>Cf source. The experimental waveforms from the detectors were compared to simulated pulse shapes. In the analysis, special emphasis was given to the detection of elastically scattered neutrons, which may be an important effect to take into account in future spectrometers based on γ-ray tracking. No differences between neutron and γ-ray induced pulse shapes were found in this work.</p><p>A Monte Carlo simulation of the interactions of fast neutrons in the future 4π γ-ray spectrometer AGATA was also performed, in order to study the influence of neutrons on γ-ray tracking. It was shown that although there is a large probability of detecting neutrons in AGATA, the neutrons decrease the photo-peak efficiency of AGATA by only about 1% for each neutron emitted in coincidence with γ rays. The peak-to-background ratios in γ-ray spectra are, however, reduced to a much larger extent. The possibility of using AGATA as a neutron detector system was also investigated.</p>
9
Foerster, Nadine [Verfasser], and J. [Akademischer Betreuer] Blümer. "Detector optimization based on studies of charge migration in the high purity germanium crystals of the EDELWEISS dark matter experiment / Nadine Foerster ; Betreuer: J. Blümer." Karlsruhe : KIT-Bibliothek, 2017. http://d-nb.info/1129258793/34.
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De, Canditiis Bartolomeo. "3D characterization of multi-segmented HPGe detectors : simulation and validation of the PSCS technique and its application for different energies with a 152 Eu source." Thesis, Strasbourg, 2020. http://www.theses.fr/2020STRAE008.
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Les ensembles de détecteurs de rayon gamma de nouvelle génération, tel AGATA, utilisent des détecteurs multi-segmentés de germanium hyper-pur dans les expériences de physique nucléaire pour lesquelles une grande résolution et efficacité sont demandées. Ces caractéristiques sont obtenues par l’application des techniques d'analyse des formes d'impulsion et de tracking des rayons gamma. Ces dernières demandent une caractérisation volumétrique des détecteurs. À cet effet, l'IPHC a développé une table de scan qui utilise la technique Pulse Shape Comparison Scan (PSCS). Des simulations sont réalisées pour quantifier la précision de la technique PSCS et pour la valider. Elles sont appliquées sur un détecteur planaire pixelisé 3x3 et sur un détecteur symétrique d'AGATA de type S. La méthode est testée avec plusieurs énergies de rayons gamma et diverses statistiques d'entrée. Des scans réels sont aussi entrepris sur les deux détecteurs, qui sont totalement caractérisés. En particulier, un scan réalisé pour la première fois avec une source de rayons gamma de 152Eu, prouve la validité de certaines hypothèses sur lesquelles repose la technique de tracking<br>New generation gamma-ray detectors arrays, such as AGATA, employ multi-segmented high purity germanium detectors in experiments of nuclear physics that require high resolution and efficiency which are obtained thanks to the application of pulse-shape analysis and gamma-ray tracking. These techniques require full volume characterization of the position sensitive detectors. The IPHC developed a scanning table that uses the Pulse Shape Comparison Scan (PSCS) technique to perform this task. Simulations are performed to quantify the accuracy of the PSCS and to validate it.They are applied on a pixelated 3x3 planar detector and a symmetrical S-type AGATA detector. The method is tested with different gamma-ray energies and input statistics. Several real scans are performed as well on both detectors, which are fully characterized. In particular a scan with agamma-ray source of 152Eu, the first ever done, prove some assumptions on which the tracking technique is based