Pub Date : 2010-10-01DOI: 10.1109/NSSMIC.2010.5873811
M. Gierlik, J. Iwanowska, T. Kozłowski, M. Moszynski, L. Swiderski, T. Szczesniak
The quest for finding the suitable detector for application in neutron activation analysis triggered us to investigate the properties of three 3"× 3" cylindrical scintillation detectors. The emphasis was put on the detectors' properties in the multi-MeV energy region as well as their response to neutron radiation. In this work we compare energy resolution efficiency and timing properties of BGO, LaBr3 and NaI(Tl) scintillation detectors coupled to Photonis spectrometric photomultiplier tubes.
{"title":"The comparison of large scintillators for high energy gamma-rays detection","authors":"M. Gierlik, J. Iwanowska, T. Kozłowski, M. Moszynski, L. Swiderski, T. Szczesniak","doi":"10.1109/NSSMIC.2010.5873811","DOIUrl":"https://doi.org/10.1109/NSSMIC.2010.5873811","url":null,"abstract":"The quest for finding the suitable detector for application in neutron activation analysis triggered us to investigate the properties of three 3\"× 3\" cylindrical scintillation detectors. The emphasis was put on the detectors' properties in the multi-MeV energy region as well as their response to neutron radiation. In this work we compare energy resolution efficiency and timing properties of BGO, LaBr3 and NaI(Tl) scintillation detectors coupled to Photonis spectrometric photomultiplier tubes.","PeriodicalId":13048,"journal":{"name":"IEEE Nuclear Science Symposuim & Medical Imaging Conference","volume":"35 1","pages":"501-505"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88383663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-10-01DOI: 10.1109/NSSMIC.2010.5873894
S. Prasad, S. Clarke, E. Miller, S. Pozzi, E. Larsen
Liquid scintillator detectors are valuable for detection of special nuclear material since they are capable of detecting both neutrons and gamma rays. Furthermore, scintillators can also provide energy information which can help in identification and characterization of the source. In order to deign scintillation based measurement systems appropriate simulation tools are needed. MCNPX-PoliMi is capable of simulating scintillator detector response, however, simulations have traditionally been run in analog mode which leads to longer computation times. In this paper nonanalog MCNPX-PoliMi mode which uses variance reduction techniques is applied and tested. The nonanalog MCNPX-PoliMi simulation test case uses source biasing variance reduction technique to efficiently simulate pulse height distribution and then time-of-flight for a heavily shielded case with a 252Cf source. Neutron time-of-flight measurements are essential to nonproliferation and safeguards efforts to identify and characterize special nuclear material. The resulting simulation is marked by an improvement in the figure of merit (FOM) by a factor of 3.4.
{"title":"Time dependent neutron detector response simulation for 252Cf","authors":"S. Prasad, S. Clarke, E. Miller, S. Pozzi, E. Larsen","doi":"10.1109/NSSMIC.2010.5873894","DOIUrl":"https://doi.org/10.1109/NSSMIC.2010.5873894","url":null,"abstract":"Liquid scintillator detectors are valuable for detection of special nuclear material since they are capable of detecting both neutrons and gamma rays. Furthermore, scintillators can also provide energy information which can help in identification and characterization of the source. In order to deign scintillation based measurement systems appropriate simulation tools are needed. MCNPX-PoliMi is capable of simulating scintillator detector response, however, simulations have traditionally been run in analog mode which leads to longer computation times. In this paper nonanalog MCNPX-PoliMi mode which uses variance reduction techniques is applied and tested. The nonanalog MCNPX-PoliMi simulation test case uses source biasing variance reduction technique to efficiently simulate pulse height distribution and then time-of-flight for a heavily shielded case with a 252Cf source. Neutron time-of-flight measurements are essential to nonproliferation and safeguards efforts to identify and characterize special nuclear material. The resulting simulation is marked by an improvement in the figure of merit (FOM) by a factor of 3.4.","PeriodicalId":13048,"journal":{"name":"IEEE Nuclear Science Symposuim & Medical Imaging Conference","volume":"1 1","pages":"911-914"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88427361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-10-01DOI: 10.1109/NSSMIC.2010.5874434
N. Efthimiou, S. Maistros, X. Tripolitis, A. Samartzis, G. Loudos, G. Panayiotakis
This article presents the performance evaluation in planar and tomographic mode, of a low cost dedicated PET camera for small animal imaging. The system consists of two pixelated LSO crystals, two Hamamatsu H8500 PSPMTs, fast amplification electronics and a FPGA based read out system. The main parameters that have been studied are i) saturation as a function of acceptance angle ii) effect of projections number and total rotation degrees iii) spatial resolution and iv) system's sensitivity. Image reconstruction has been carried out with open source software previously developed by our group, the QSPECT. In addition Monte Carlo simulations of the system have been carried out, in order to investigate the system performance with the used of different scintillation crystals and geometries.
{"title":"Tomographie and planar evaluation of dual head small animal PET","authors":"N. Efthimiou, S. Maistros, X. Tripolitis, A. Samartzis, G. Loudos, G. Panayiotakis","doi":"10.1109/NSSMIC.2010.5874434","DOIUrl":"https://doi.org/10.1109/NSSMIC.2010.5874434","url":null,"abstract":"This article presents the performance evaluation in planar and tomographic mode, of a low cost dedicated PET camera for small animal imaging. The system consists of two pixelated LSO crystals, two Hamamatsu H8500 PSPMTs, fast amplification electronics and a FPGA based read out system. The main parameters that have been studied are i) saturation as a function of acceptance angle ii) effect of projections number and total rotation degrees iii) spatial resolution and iv) system's sensitivity. Image reconstruction has been carried out with open source software previously developed by our group, the QSPECT. In addition Monte Carlo simulations of the system have been carried out, in order to investigate the system performance with the used of different scintillation crystals and geometries.","PeriodicalId":13048,"journal":{"name":"IEEE Nuclear Science Symposuim & Medical Imaging Conference","volume":"04 1","pages":"3383-3388"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86110894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-10-01DOI: 10.1109/NSSMIC.2010.5874034
Grzegorz Deptuch, M. Trimpl, R. Yarema, D. Siddons, G. Carini, P. Grybos, R. Szczygiel, M. Kachel, P. Kmon, P. Maj
We report on the design of the VIPIC IC (Vertically Integrated Pixel Imaging Chip) designed for X-ray Photon Correlation Spectroscopy (XPCS) experiments by FNAL in collaboration with AGH-UST. The VIPIC chip is a prototype matrix with 64 × 64 pixels with 80 μm × 80 μm pixel size and consists of two layers: analog and digital. The single analog pixel cell consists of a charge sensitive amplifier, a shaper, a single current discriminator and trim DACs. The simulated gain is 52 μV/e−, the noise ENC < 150 e− rms (with Cdet= 100 fF) and the peaking time tp < 250 ns. The power consumption is 25 μW/pixel in the analog part. The digital layer of the VIPIC integrated circuit is divided into 16 readout groups of pixels read out in parallel via separate serial ports with nominal frequency of the 100 MHz clock using the LVDS standard. The readout within each group is zero-suppressed. The sparsification scheme (addresses of hit pixels only) allows a dead-time free readout.
{"title":"VIPIC IC — Design and test aspects of the 3D pixel chip","authors":"Grzegorz Deptuch, M. Trimpl, R. Yarema, D. Siddons, G. Carini, P. Grybos, R. Szczygiel, M. Kachel, P. Kmon, P. Maj","doi":"10.1109/NSSMIC.2010.5874034","DOIUrl":"https://doi.org/10.1109/NSSMIC.2010.5874034","url":null,"abstract":"We report on the design of the VIPIC IC (Vertically Integrated Pixel Imaging Chip) designed for X-ray Photon Correlation Spectroscopy (XPCS) experiments by FNAL in collaboration with AGH-UST. The VIPIC chip is a prototype matrix with 64 × 64 pixels with 80 μm × 80 μm pixel size and consists of two layers: analog and digital. The single analog pixel cell consists of a charge sensitive amplifier, a shaper, a single current discriminator and trim DACs. The simulated gain is 52 μV/e<sup>−</sup>, the noise ENC < 150 e<sup>−</sup> rms (with C<inf>det</inf>= 100 fF) and the peaking time t<inf>p</inf> < 250 ns. The power consumption is 25 μW/pixel in the analog part. The digital layer of the VIPIC integrated circuit is divided into 16 readout groups of pixels read out in parallel via separate serial ports with nominal frequency of the 100 MHz clock using the LVDS standard. The readout within each group is zero-suppressed. The sparsification scheme (addresses of hit pixels only) allows a dead-time free readout.","PeriodicalId":13048,"journal":{"name":"IEEE Nuclear Science Symposuim & Medical Imaging Conference","volume":"353 1","pages":"1540-1543"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82605925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-10-01DOI: 10.1109/NSSMIC.2010.5874480
Wenjia Bai, S. M. Brady
Positron emission tomography (PET) is a molecular imaging technique which provides important functional information about the human body. However, thoracic PET images are often substantially degraded by respiratory motion, which adversely impacts on subsequent diagnosis. In this paper, a motion correction and attenuation correction method is proposed to correct for motion in respiratory gated PET images and to yield an accurate distribution of the radioactivity concentration. Experimental results show that this method can effectively correct for motion and improve PET image quality.
{"title":"Motion correction and attenuation correction in thoracic PET imaging","authors":"Wenjia Bai, S. M. Brady","doi":"10.1109/NSSMIC.2010.5874480","DOIUrl":"https://doi.org/10.1109/NSSMIC.2010.5874480","url":null,"abstract":"Positron emission tomography (PET) is a molecular imaging technique which provides important functional information about the human body. However, thoracic PET images are often substantially degraded by respiratory motion, which adversely impacts on subsequent diagnosis. In this paper, a motion correction and attenuation correction method is proposed to correct for motion in respiratory gated PET images and to yield an accurate distribution of the radioactivity concentration. Experimental results show that this method can effectively correct for motion and improve PET image quality.","PeriodicalId":13048,"journal":{"name":"IEEE Nuclear Science Symposuim & Medical Imaging Conference","volume":"13 1","pages":"3593-3598"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86635003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-10-01DOI: 10.1109/NSSMIC.2010.5874537
K. Borozdin, C. Morris, A. Klimenko, R. Spaulding, J. Bacon
We present a novel concept of the SNM imaging system based on cosmic-ray muon tracking in coincidence with neutron/gamma detection. The cosmic-ray flux at sea level is about 1 muon/sq. cm/minute. It is composed of nearly equal numbers of μ+ and μ-. In previous work, we have demonstrated that these muons can be used to image nuclear threats in relatively short times by measuring their multiple scattering through objects. Here we propose to image nuclear objects by combining tracking of the muons into a scene with measurements of the secondary particles produced when the muons stop in dense potentially fissile materials. We use multiple drift tube planes to trace incoming cosmic rays. Plastic scintillator serves as a detector of outgoing neutrons and gamma-rays. Additionally, the same plastic scintillator is used to estimate the energy of incoming cosmic-rays. We use a coincidence of n/gamma detection with the initial cosmic-ray trigger to suppress the background. The fissions produced by the stopped μ-generate fission chains that die away after several (∼5) fissions. Each fission produces ∼10 energetic gamma rays and ∼2.5 neutrons. Although a self-shielding needs to be considered, it is likely that tens of neutrons and gamma rays will escape from the object of typical configuration. The efficiency of detecting at least one of the products within ∼100 ns could be close to 100% for a detector of reasonably large solid angle (∼2 ster). Ten minutes of data should produce 50 trajectories from μ-stopped in 20 kg of U. These numbers can be scaled for other size objects. Our approach has no active source, and therefore it is safe for humans and has no effect on the object under inspection. The detectors are scalable and portable. The drift tubes of the detectors are sealed and do not need the gas replenishment. Detection and localization of SNM is achieved with automatic reconstruction algorithm, which can be run at a standard computer.
{"title":"Passive imaging of SNM with cosmic-ray generated neutrons and gamma-rays","authors":"K. Borozdin, C. Morris, A. Klimenko, R. Spaulding, J. Bacon","doi":"10.1109/NSSMIC.2010.5874537","DOIUrl":"https://doi.org/10.1109/NSSMIC.2010.5874537","url":null,"abstract":"We present a novel concept of the SNM imaging system based on cosmic-ray muon tracking in coincidence with neutron/gamma detection. The cosmic-ray flux at sea level is about 1 muon/sq. cm/minute. It is composed of nearly equal numbers of μ+ and μ-. In previous work, we have demonstrated that these muons can be used to image nuclear threats in relatively short times by measuring their multiple scattering through objects. Here we propose to image nuclear objects by combining tracking of the muons into a scene with measurements of the secondary particles produced when the muons stop in dense potentially fissile materials. We use multiple drift tube planes to trace incoming cosmic rays. Plastic scintillator serves as a detector of outgoing neutrons and gamma-rays. Additionally, the same plastic scintillator is used to estimate the energy of incoming cosmic-rays. We use a coincidence of n/gamma detection with the initial cosmic-ray trigger to suppress the background. The fissions produced by the stopped μ-generate fission chains that die away after several (∼5) fissions. Each fission produces ∼10 energetic gamma rays and ∼2.5 neutrons. Although a self-shielding needs to be considered, it is likely that tens of neutrons and gamma rays will escape from the object of typical configuration. The efficiency of detecting at least one of the products within ∼100 ns could be close to 100% for a detector of reasonably large solid angle (∼2 ster). Ten minutes of data should produce 50 trajectories from μ-stopped in 20 kg of U. These numbers can be scaled for other size objects. Our approach has no active source, and therefore it is safe for humans and has no effect on the object under inspection. The detectors are scalable and portable. The drift tubes of the detectors are sealed and do not need the gas replenishment. Detection and localization of SNM is achieved with automatic reconstruction algorithm, which can be run at a standard computer.","PeriodicalId":13048,"journal":{"name":"IEEE Nuclear Science Symposuim & Medical Imaging Conference","volume":"1 1","pages":"3864-3867"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88889255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-10-01DOI: 10.1109/NSSMIC.2010.5873918
A. Medvid, A. Mychko, E. Dauksta, Y. Naseka, J. Crocco, E. Dieguez
The aim of this work is to study the possibility to increase the radiation hardness of Cd0.9Zn0.1 Te crystal using laser radiation. Pulsed Nd:YAG laser for this aim was used. Estimation of the crystalline lattice defects before and after irradiation by γ-ray using photoluminescence method in the experiments was applied. Experimental results showed the increase of the radiation hardness of CdZnTe crystal after irradiation by laser at intensity 1.20–1.80 MW/cm2.
{"title":"Increased radiation hardness of CdZnTe by laser radiation","authors":"A. Medvid, A. Mychko, E. Dauksta, Y. Naseka, J. Crocco, E. Dieguez","doi":"10.1109/NSSMIC.2010.5873918","DOIUrl":"https://doi.org/10.1109/NSSMIC.2010.5873918","url":null,"abstract":"The aim of this work is to study the possibility to increase the radiation hardness of Cd0.9Zn0.1 Te crystal using laser radiation. Pulsed Nd:YAG laser for this aim was used. Estimation of the crystalline lattice defects before and after irradiation by γ-ray using photoluminescence method in the experiments was applied. Experimental results showed the increase of the radiation hardness of CdZnTe crystal after irradiation by laser at intensity 1.20–1.80 MW/cm2.","PeriodicalId":13048,"journal":{"name":"IEEE Nuclear Science Symposuim & Medical Imaging Conference","volume":"6 1","pages":"1014-1016"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88967666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-10-01DOI: 10.1109/NSSMIC.2010.5873965
J. Adams, M. Mellor, M. Joyce
A phantom designed for the study of radiologically-contaminated land is described. The phantom comprises a bespoke, 1 m3 outer tank and an inner tube matrix for the deployment of γ-ray emitting radioactive sources. The phantom was filled to a depth of 900mm with dry sandy loam to mimic soils found in areas surrounding nuclear legacy facilities in the U.K. A series of non-intrusive spectral measurements were taken using an automated scanning rig and a cadmium telluride γ-ray detector. The detector was clamped at a constant height above the phantom, face-down and sequenced over a pre-defined grid above the phantom, using a scanning rig. A small caesium-137 source was positioned at a depth of 150mm in one of the tubes at random. Scans were then conducted at 30 minute intervals at twelve separate measurement points, to allow sufficient counting time to isolate the γ-ray caesium-137 662 keV photopeak from the background. A CAD model was then built of a simplified albeit geometrically correct representation of the phantom and the reading points. The combination of this model and the imported γ-ray spectra has enabled the inverse modelling technique N-Visage™ to be validated against the accurate surface location for the source without prior knowledge.
{"title":"A phantom for research studies of radiologically-contaminated land","authors":"J. Adams, M. Mellor, M. Joyce","doi":"10.1109/NSSMIC.2010.5873965","DOIUrl":"https://doi.org/10.1109/NSSMIC.2010.5873965","url":null,"abstract":"A phantom designed for the study of radiologically-contaminated land is described. The phantom comprises a bespoke, 1 m3 outer tank and an inner tube matrix for the deployment of γ-ray emitting radioactive sources. The phantom was filled to a depth of 900mm with dry sandy loam to mimic soils found in areas surrounding nuclear legacy facilities in the U.K. A series of non-intrusive spectral measurements were taken using an automated scanning rig and a cadmium telluride γ-ray detector. The detector was clamped at a constant height above the phantom, face-down and sequenced over a pre-defined grid above the phantom, using a scanning rig. A small caesium-137 source was positioned at a depth of 150mm in one of the tubes at random. Scans were then conducted at 30 minute intervals at twelve separate measurement points, to allow sufficient counting time to isolate the γ-ray caesium-137 662 keV photopeak from the background. A CAD model was then built of a simplified albeit geometrically correct representation of the phantom and the reading points. The combination of this model and the imported γ-ray spectra has enabled the inverse modelling technique N-Visage™ to be validated against the accurate surface location for the source without prior knowledge.","PeriodicalId":13048,"journal":{"name":"IEEE Nuclear Science Symposuim & Medical Imaging Conference","volume":"185 3","pages":"1239-1243"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91512784","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-10-01DOI: 10.1109/NSSMIC.2010.5873908
H. Harano, T. Matsumoto, J. Nishiyama, A. Masuda, A. Uritani, K. Kudo
Long counters are widely used as neutron fluence monitors by utilizing their flat-response feature. A bulky neutron moderator is required however to achieve the flat-response feature, which can be a disadvantage from the viewpoint of portability as well as an undesirable source of scattered neutrons. Just downsizing the moderator deteriorates the flat response especially for high-energy neutrons. We proposed a new method to downsize the moderator with keeping the flat-response feature and developed a compact flat-response neutron detector in the present study. The detector consists of two small spherical 3He proportional counters embedded in appropriate positions in a compact cylindrical polyethylene moderator. The sensitivity ratio between the two counters was adjusted to provide a flat response in the total outputs from the two counters. It was demonstrated by MCNPX calculations and response measurements for Cf and Am-Be neutrons and monoenergetic neutrons that the present detector had a good flat response in the wide energy range up to 20 MeV while being downsized by one fifth compared with long counters. The positions of the effective center were determined as a function of the neutron energy. We also proposed a method to evaluate the neutron energy using the detector, which will allow various new applications by taking advantage of measuring the neutron fluence and energy at the same time.
{"title":"Development of a compact flat response neutron detector","authors":"H. Harano, T. Matsumoto, J. Nishiyama, A. Masuda, A. Uritani, K. Kudo","doi":"10.1109/NSSMIC.2010.5873908","DOIUrl":"https://doi.org/10.1109/NSSMIC.2010.5873908","url":null,"abstract":"Long counters are widely used as neutron fluence monitors by utilizing their flat-response feature. A bulky neutron moderator is required however to achieve the flat-response feature, which can be a disadvantage from the viewpoint of portability as well as an undesirable source of scattered neutrons. Just downsizing the moderator deteriorates the flat response especially for high-energy neutrons. We proposed a new method to downsize the moderator with keeping the flat-response feature and developed a compact flat-response neutron detector in the present study. The detector consists of two small spherical 3He proportional counters embedded in appropriate positions in a compact cylindrical polyethylene moderator. The sensitivity ratio between the two counters was adjusted to provide a flat response in the total outputs from the two counters. It was demonstrated by MCNPX calculations and response measurements for Cf and Am-Be neutrons and monoenergetic neutrons that the present detector had a good flat response in the wide energy range up to 20 MeV while being downsized by one fifth compared with long counters. The positions of the effective center were determined as a function of the neutron energy. We also proposed a method to evaluate the neutron energy using the detector, which will allow various new applications by taking advantage of measuring the neutron fluence and energy at the same time.","PeriodicalId":13048,"journal":{"name":"IEEE Nuclear Science Symposuim & Medical Imaging Conference","volume":"45 1","pages":"974-978"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91524591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-10-01DOI: 10.1109/NSSMIC.2010.5874119
P. Lecoq, E. Auffray, S. Gundacker, H. Hillemanns, P. Jarron, A. Knapitsch, J. Leclercq, X. Letartre, T. Meyer, K. Pauwels, F. Powolny, C. Seassal
The renewal of interest for Time of Flight Positron Emission Tomography (TOF PET) has highlighted the need for increasing the light output of scintillating crystals and in particular for improving the light extraction from materials with a high index of refraction. One possible solution to overcome the problem of total internal reflection and light losses resulting from multiple bouncing within the crystal is to improve the light extraction efficiency at the crystal/photodetector interface by means of photonic crystals, i.e. media with a periodic modulation of the dielectric constant at the wavelength scale. After a short reminder of the underlying principles this contribution proposes to present the very encouraging results we have recently obtained on LYSO pixels and the perspectives on other crystals such as BGO, LuYAP and LuAG. These results confirm the impressive predictions from our previously published Monte Carlo simulations. A detailed description of the sample preparation procedure is given as well as the methodology and different characterization steps to control the process and evaluate the results. Pictures and quantitative results are shown, which confirm that significant light output gain factors (50% and more) can be obtained with this approach. Finally an interesting feature of photonic crystals to collimate light in some privileged directions is highlighted.
{"title":"Progress on photonic crystals","authors":"P. Lecoq, E. Auffray, S. Gundacker, H. Hillemanns, P. Jarron, A. Knapitsch, J. Leclercq, X. Letartre, T. Meyer, K. Pauwels, F. Powolny, C. Seassal","doi":"10.1109/NSSMIC.2010.5874119","DOIUrl":"https://doi.org/10.1109/NSSMIC.2010.5874119","url":null,"abstract":"The renewal of interest for Time of Flight Positron Emission Tomography (TOF PET) has highlighted the need for increasing the light output of scintillating crystals and in particular for improving the light extraction from materials with a high index of refraction. One possible solution to overcome the problem of total internal reflection and light losses resulting from multiple bouncing within the crystal is to improve the light extraction efficiency at the crystal/photodetector interface by means of photonic crystals, i.e. media with a periodic modulation of the dielectric constant at the wavelength scale. After a short reminder of the underlying principles this contribution proposes to present the very encouraging results we have recently obtained on LYSO pixels and the perspectives on other crystals such as BGO, LuYAP and LuAG. These results confirm the impressive predictions from our previously published Monte Carlo simulations. A detailed description of the sample preparation procedure is given as well as the methodology and different characterization steps to control the process and evaluate the results. Pictures and quantitative results are shown, which confirm that significant light output gain factors (50% and more) can be obtained with this approach. Finally an interesting feature of photonic crystals to collimate light in some privileged directions is highlighted.","PeriodicalId":13048,"journal":{"name":"IEEE Nuclear Science Symposuim & Medical Imaging Conference","volume":"1 1","pages":"1970-1975"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90174662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：