Pub Date : 2013-10-01DOI: 10.1109/NSSMIC.2013.6829523
H. Kanda, Y. Akazawa, Y. Fujii, R. Honda, M. Kaneta, Y. Kasai, J. Kusaka, K. Maeda, K. Miwa, S. Nagao, S. Nakamura, T. Nishizawa, K. Tsukada, F. Yamamoto
We developed scintillation counters with Multi-Pixel-Photon-Counters (MPPC's) for an electron detector of a photon tagging system. They were compact, tolerant to a magnetic field, rate tolerant up to 170 kHz and had a good time resolution. These properties were suitable for the electron detector which was placed in a limited space of a bending magnet of an electron synchrotron. The scintillation counters were used for the measurement of the timing of the passage of the post-bremsstrahlung electrons, and the definition of their orbits by the hit positions on the counters to measure their momenta. We prepared two kinds of scintillation counter, one is for finer granularity named as a TagF and the other for the timing measurement named as a TagB. We performed an experiment to measure the properties of the counter unit using an electron beam with the energy of 855 MeV. We obtained the timing resolution of the TagB to be less than 80 ps (σ) almost independent of the hit rate in the range of 25 kHz to 170 kHz. Its gain decrease at the rate of 170 kHz was ~ 5% of the gain at the rate of 25 kHz. These properties satisfied our requirements for the electron detector. The whole electron detector consisting of the counter units are currently being designed.
{"title":"MPPC based scintillation counters for the internal photon tagger","authors":"H. Kanda, Y. Akazawa, Y. Fujii, R. Honda, M. Kaneta, Y. Kasai, J. Kusaka, K. Maeda, K. Miwa, S. Nagao, S. Nakamura, T. Nishizawa, K. Tsukada, F. Yamamoto","doi":"10.1109/NSSMIC.2013.6829523","DOIUrl":"https://doi.org/10.1109/NSSMIC.2013.6829523","url":null,"abstract":"We developed scintillation counters with Multi-Pixel-Photon-Counters (MPPC's) for an electron detector of a photon tagging system. They were compact, tolerant to a magnetic field, rate tolerant up to 170 kHz and had a good time resolution. These properties were suitable for the electron detector which was placed in a limited space of a bending magnet of an electron synchrotron. The scintillation counters were used for the measurement of the timing of the passage of the post-bremsstrahlung electrons, and the definition of their orbits by the hit positions on the counters to measure their momenta. We prepared two kinds of scintillation counter, one is for finer granularity named as a TagF and the other for the timing measurement named as a TagB. We performed an experiment to measure the properties of the counter unit using an electron beam with the energy of 855 MeV. We obtained the timing resolution of the TagB to be less than 80 ps (σ) almost independent of the hit rate in the range of 25 kHz to 170 kHz. Its gain decrease at the rate of 170 kHz was ~ 5% of the gain at the rate of 25 kHz. These properties satisfied our requirements for the electron detector. The whole electron detector consisting of the counter units are currently being designed.","PeriodicalId":246351,"journal":{"name":"2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (2013 NSS/MIC)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116769109","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 : 2013-10-01DOI: 10.1109/NSSMIC.2013.6829626
H. Simões, S. Ghithan, M. Loureiro, P. Crespo
Measurements of the phosphorescence of cerium-doped gadolinium oxyorthosilicate (GSO:Ce) crystals in a high-radiation environment with dose rates higher than 5 Gy/h have revealed the presence of a strong component of phosphorescent light. Such component, at times reaching values as high as the irradiation itself, could disturb planned orthogonal ray imaging systems, where megavoltage linacs deliver target doses of the order of 2 Gy/min. In two previous studies of orthogonal ray imaging a crystal of cerium-doped lutetium yttrium oxyorthosilicate (LYSO:Ce) was utilized for obtaining first orthogonal ray images with a single-pixel collimated detector. Because an orthogonal ray imaging device must comprise a multi-pixel system, the possibility of utilizing GSO as a scintillator suiting that purpose is currently under investigation. In order to rule out the possibility that the aforementioned phosphorescence of GSO disturbs future orthogonal ray imaging systems, we have performed spectroscopic measurements of a finger-like GSO crystals before, during, and after irradiation with both a 22Na and 60Co radioactive source with activities of 1.6 and 7.0MBq, respectively. A dosimetric Geiger detector positioned adjacent to the 60Co source revealed a dose rate of 1 mGy/h, i.e. more than 3 orders of magnitude lower than the aforementioned study. This value, nevertheless, is still above the expected dose rate value to be experienced by an orthogonal ray imaging detector since such detector is to be positioned behind a multi-hole or a multi-slit collimator. Cunha et al. calculated that the radiation dispersed onto such detectors is diminished by a factor of at least 105, which renders the dose-rate values measured in this work pertinent. We found no evidence of GSO phosphorescence at these very-low dose rates. Pulse shape analysis revealed nevertheless the existence of a very small amount of intrinsic radioactivity due to the alpha decay of 152Gd. GSO is therefore a suitable scintillator for planned orthogonal ray imaging systems.
{"title":"Characterization of GSO:Ce phosphorescence after low-dose-rate gamma-ray irradiation","authors":"H. Simões, S. Ghithan, M. Loureiro, P. Crespo","doi":"10.1109/NSSMIC.2013.6829626","DOIUrl":"https://doi.org/10.1109/NSSMIC.2013.6829626","url":null,"abstract":"Measurements of the phosphorescence of cerium-doped gadolinium oxyorthosilicate (GSO:Ce) crystals in a high-radiation environment with dose rates higher than 5 Gy/h have revealed the presence of a strong component of phosphorescent light. Such component, at times reaching values as high as the irradiation itself, could disturb planned orthogonal ray imaging systems, where megavoltage linacs deliver target doses of the order of 2 Gy/min. In two previous studies of orthogonal ray imaging a crystal of cerium-doped lutetium yttrium oxyorthosilicate (LYSO:Ce) was utilized for obtaining first orthogonal ray images with a single-pixel collimated detector. Because an orthogonal ray imaging device must comprise a multi-pixel system, the possibility of utilizing GSO as a scintillator suiting that purpose is currently under investigation. In order to rule out the possibility that the aforementioned phosphorescence of GSO disturbs future orthogonal ray imaging systems, we have performed spectroscopic measurements of a finger-like GSO crystals before, during, and after irradiation with both a 22Na and 60Co radioactive source with activities of 1.6 and 7.0MBq, respectively. A dosimetric Geiger detector positioned adjacent to the 60Co source revealed a dose rate of 1 mGy/h, i.e. more than 3 orders of magnitude lower than the aforementioned study. This value, nevertheless, is still above the expected dose rate value to be experienced by an orthogonal ray imaging detector since such detector is to be positioned behind a multi-hole or a multi-slit collimator. Cunha et al. calculated that the radiation dispersed onto such detectors is diminished by a factor of at least 105, which renders the dose-rate values measured in this work pertinent. We found no evidence of GSO phosphorescence at these very-low dose rates. Pulse shape analysis revealed nevertheless the existence of a very small amount of intrinsic radioactivity due to the alpha decay of 152Gd. GSO is therefore a suitable scintillator for planned orthogonal ray imaging systems.","PeriodicalId":246351,"journal":{"name":"2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (2013 NSS/MIC)","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116808033","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 : 2013-10-01DOI: 10.1109/NSSMIC.2013.6829237
Yu Yunhan, Yan Xia, Wei Wang, Yaqiang Liu, K. Ying, Shi Wang, Tianyu Ma
System matrix works as an association between image and detected data. Accurate expression of the system matrix is a key component during PET image reconstruction. However, with numerous Line-of-Responses (LORs) detected in modern 3D PET scanner, the huge storage size of a full system matrix increases computational burden. To solve this essential issue, we designed a rotationally symmetric polygonal pixel grid with fan-shaped segments in the image domain to efficiently compress the matrix with geometrical symmetries. This idea mainly came from the polygonal geometry of detector rings in most PET system.
{"title":"Polygonal pixel grid based PET image reconstruction algorithm: Development, application and performance comparison","authors":"Yu Yunhan, Yan Xia, Wei Wang, Yaqiang Liu, K. Ying, Shi Wang, Tianyu Ma","doi":"10.1109/NSSMIC.2013.6829237","DOIUrl":"https://doi.org/10.1109/NSSMIC.2013.6829237","url":null,"abstract":"System matrix works as an association between image and detected data. Accurate expression of the system matrix is a key component during PET image reconstruction. However, with numerous Line-of-Responses (LORs) detected in modern 3D PET scanner, the huge storage size of a full system matrix increases computational burden. To solve this essential issue, we designed a rotationally symmetric polygonal pixel grid with fan-shaped segments in the image domain to efficiently compress the matrix with geometrical symmetries. This idea mainly came from the polygonal geometry of detector rings in most PET system.","PeriodicalId":246351,"journal":{"name":"2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (2013 NSS/MIC)","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123279609","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 : 2013-10-01DOI: 10.1109/nssmic.2013.6829169
Shigeharu Kobayashi, Tokonatsu Yamamoto, F. Kajino
A simple MC simulation using the Mathematica app. is presented for a square-shaped PEM device consisted of the notched scintillating crystal chips. For a previously studied material of a 30 mm length Pr:LuAG with the cross sectional area of either 2×2 mm2 or 4×4 mm2, the imaging spread and the detection efficiency of a point source are examined. Chosen the number of DOI notches as a parameter, an optimum solution to give the sub-millimeter space resolution is obtained. Some more results for the PEM construction also are presented.
{"title":"Simulation study of the DOI-PEM scanner","authors":"Shigeharu Kobayashi, Tokonatsu Yamamoto, F. Kajino","doi":"10.1109/nssmic.2013.6829169","DOIUrl":"https://doi.org/10.1109/nssmic.2013.6829169","url":null,"abstract":"A simple MC simulation using the Mathematica app. is presented for a square-shaped PEM device consisted of the notched scintillating crystal chips. For a previously studied material of a 30 mm length Pr:LuAG with the cross sectional area of either 2×2 mm2 or 4×4 mm2, the imaging spread and the detection efficiency of a point source are examined. Chosen the number of DOI notches as a parameter, an optimum solution to give the sub-millimeter space resolution is obtained. Some more results for the PEM construction also are presented.","PeriodicalId":246351,"journal":{"name":"2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (2013 NSS/MIC)","volume":"136 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123594456","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 : 2013-10-01DOI: 10.1109/NSSMIC.2013.6829168
A. Aichert, M. Manhart, Bharath K. Navalpakkam, R. Grimm, J. Hutter, A. Maier, J. Hornegger, A. Doerfler
CTP is an important imaging modality for diagnosis of ischemic stroke, which is computed from of a series of consecutive CT-scans during the injection of contrast agent. Contrast flow at any point in space can be tracked as minor changes in intensity over a period of about 40 seconds to one minute, represented as a time-attenuation curve (TAC) for every voxel. This work presents an isotropic, dense, physiologically realistic and dynamic brain phantom for CT perfusion. The phantom is based on MRI scans of a volunteer and is freely available for download.
{"title":"A realistic digital phantom for perfusion C-arm CT based on MRI data","authors":"A. Aichert, M. Manhart, Bharath K. Navalpakkam, R. Grimm, J. Hutter, A. Maier, J. Hornegger, A. Doerfler","doi":"10.1109/NSSMIC.2013.6829168","DOIUrl":"https://doi.org/10.1109/NSSMIC.2013.6829168","url":null,"abstract":"CTP is an important imaging modality for diagnosis of ischemic stroke, which is computed from of a series of consecutive CT-scans during the injection of contrast agent. Contrast flow at any point in space can be tracked as minor changes in intensity over a period of about 40 seconds to one minute, represented as a time-attenuation curve (TAC) for every voxel. This work presents an isotropic, dense, physiologically realistic and dynamic brain phantom for CT perfusion. The phantom is based on MRI scans of a volunteer and is freely available for download.","PeriodicalId":246351,"journal":{"name":"2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (2013 NSS/MIC)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123773427","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 : 2013-10-01DOI: 10.1109/NSSMIC.2013.6829535
Weibin Pan, G. Gong, Hongming Li, Jianmin Li
This paper presents a temperature compensation design for carry chain based Time-to-Digital Converter (TDC) in FPGA. The bin-by-bin calibrations under different temperatures are performed for both plain TDC and Wave Union TDC to characterize the influence of temperature variation on the delay time of carry chain which shows all TDC channels have the similar temperature-LUT coefficient. Accordingly, a simplified temperature compensation scheme by using a dedicated correction channel to measure the coefficient and correct fine time result for all TDC channels is implemented and tested. This method shows only few picosecond errors for both simulation and measurement. With this compensation approach, a 21ps RMS TDC resolution has been achieved in Cyclone II FPGA under a wide temperature range from 10°C to 75°C. Several design key points are also described in this paper.
提出了一种基于进位链的FPGA时间-数字转换器(TDC)的温度补偿设计。在不同温度条件下，对普通TDC和Wave Union TDC进行了逐箱校准，表征了温度变化对携带链延迟时间的影响，结果表明所有TDC通道具有相似的温度- lut系数。在此基础上，实现了一种简化的温度补偿方案，即利用专用的校正通道测量系数并对所有TDC通道的精细时间结果进行校正。该方法的仿真和测量误差均小于皮秒。通过这种补偿方法，Cyclone II FPGA在10°C至75°C的宽温度范围内实现了21ps RMS TDC分辨率。本文还介绍了几个设计要点。
{"title":"A 20-ps temperature compensated Time-to-Digital Converter (TDC) implemented in FPGA","authors":"Weibin Pan, G. Gong, Hongming Li, Jianmin Li","doi":"10.1109/NSSMIC.2013.6829535","DOIUrl":"https://doi.org/10.1109/NSSMIC.2013.6829535","url":null,"abstract":"This paper presents a temperature compensation design for carry chain based Time-to-Digital Converter (TDC) in FPGA. The bin-by-bin calibrations under different temperatures are performed for both plain TDC and Wave Union TDC to characterize the influence of temperature variation on the delay time of carry chain which shows all TDC channels have the similar temperature-LUT coefficient. Accordingly, a simplified temperature compensation scheme by using a dedicated correction channel to measure the coefficient and correct fine time result for all TDC channels is implemented and tested. This method shows only few picosecond errors for both simulation and measurement. With this compensation approach, a 21ps RMS TDC resolution has been achieved in Cyclone II FPGA under a wide temperature range from 10°C to 75°C. Several design key points are also described in this paper.","PeriodicalId":246351,"journal":{"name":"2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (2013 NSS/MIC)","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123799968","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 : 2013-10-01DOI: 10.1109/NSSMIC.2013.6829043
Yunlong Zan, R. Boutchko, Qiu Huang, G. Gullberg
123I-MIBG is an analogue of the norepinephrine uptake in the presynaptic portion of the sympathetic neurons that innervate the heart. The abnormal metabolism of 123I-MIBG is used to diagnose potential heart failure. This paper quantitatively compares the metabolism of 123I-MIBG in SHRs and Wistar-Kyoto normal rats. Dynamic projection data were acquired for 100 min in 1-sec time frames with an angular step of 2 degrees per frame on a dual-head GE Millennium VG Hawkeye SPECT/CT scanner equipped with custom pinhole collimators. The time activity curves of radiotracer in blood pool and myocardium were extracted from the projections through the spatiotemporal dimension reduction method developed previously for dynamic cardiac SPECT reconstruction. The kinetic parameters were estimated by fitting the estimate time activity curves to a compartmental model. The distribution volumes (DVs) of the radiotracer in the myocardium were calculated. The DV of SHRs was greater (p=2.4E-4) than that of WKY normal rats, indicating the development of cardiac hypertrophy in the SHRs.
{"title":"Evaluation of sympathetic nervous system function in normal and spontaneously hypertensive rat hearts with dynamic SPECT imaging","authors":"Yunlong Zan, R. Boutchko, Qiu Huang, G. Gullberg","doi":"10.1109/NSSMIC.2013.6829043","DOIUrl":"https://doi.org/10.1109/NSSMIC.2013.6829043","url":null,"abstract":"123I-MIBG is an analogue of the norepinephrine uptake in the presynaptic portion of the sympathetic neurons that innervate the heart. The abnormal metabolism of 123I-MIBG is used to diagnose potential heart failure. This paper quantitatively compares the metabolism of 123I-MIBG in SHRs and Wistar-Kyoto normal rats. Dynamic projection data were acquired for 100 min in 1-sec time frames with an angular step of 2 degrees per frame on a dual-head GE Millennium VG Hawkeye SPECT/CT scanner equipped with custom pinhole collimators. The time activity curves of radiotracer in blood pool and myocardium were extracted from the projections through the spatiotemporal dimension reduction method developed previously for dynamic cardiac SPECT reconstruction. The kinetic parameters were estimated by fitting the estimate time activity curves to a compartmental model. The distribution volumes (DVs) of the radiotracer in the myocardium were calculated. The DV of SHRs was greater (p=2.4E-4) than that of WKY normal rats, indicating the development of cardiac hypertrophy in the SHRs.","PeriodicalId":246351,"journal":{"name":"2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (2013 NSS/MIC)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125437125","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 : 2013-10-01DOI: 10.1109/NSSMIC.2013.6829212
Heejong Kim, Chin-Tu Chen, H.-T. Chen, A. Ronzhin, E. Ramberg, S. Los, P. Murat, S. Majewski, C. Kao
We are developing a human-brain imaging TOF PET detector with high sensitivity and lower radioactive dose to patients. The proposed detector design consists of 36 detector modules, and each module has 4×8 LYSO scintillators coupled to SiPMs individually. For signal readout for detector modules, the transmission-line readout with high speed waveform sampling is adopted to fully exploit the fast time response of SiPM with reduced electronics channels. A detector simulation has been developed using Geant4 package to check the performances of the proposed detector. Previously we demonstrated that our signal readout approach is feasible with SiPM. Based on the experience with the proto-type readout board, second generation readout board has been developed to implement the transmission-line signal readout for the proposed detector. In the paper, we present the initial results obtained from the simulation studies and experimental tests using the newly developed strip-line board.
{"title":"A TOF PET detector development using waveform sampling and strip-line based data acquisition","authors":"Heejong Kim, Chin-Tu Chen, H.-T. Chen, A. Ronzhin, E. Ramberg, S. Los, P. Murat, S. Majewski, C. Kao","doi":"10.1109/NSSMIC.2013.6829212","DOIUrl":"https://doi.org/10.1109/NSSMIC.2013.6829212","url":null,"abstract":"We are developing a human-brain imaging TOF PET detector with high sensitivity and lower radioactive dose to patients. The proposed detector design consists of 36 detector modules, and each module has 4×8 LYSO scintillators coupled to SiPMs individually. For signal readout for detector modules, the transmission-line readout with high speed waveform sampling is adopted to fully exploit the fast time response of SiPM with reduced electronics channels. A detector simulation has been developed using Geant4 package to check the performances of the proposed detector. Previously we demonstrated that our signal readout approach is feasible with SiPM. Based on the experience with the proto-type readout board, second generation readout board has been developed to implement the transmission-line signal readout for the proposed detector. In the paper, we present the initial results obtained from the simulation studies and experimental tests using the newly developed strip-line board.","PeriodicalId":246351,"journal":{"name":"2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (2013 NSS/MIC)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126876297","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 : 2013-10-01DOI: 10.1109/NSSMIC.2013.6829508
C. Chung
On May 19th 2011, the AMS-02 experiment was successfully deployed on board the Earth-orbiting International Space Station (ISS) and is constantly operating since then without interruption. AMS is a complex particle detector in space and conducts research in astroparticle physics by precisely measuring charged cosmic particles to study acceleration, propagation and contributions from new particle physics and astrophysical sources. This is made possible by the main features of the AMS detector, namely its large acceptance, the long duration mission about 20 years limited by the ISS lifespan and the unique high proton rejection power by combining the electromagnetic calorimeter and the transition radiation detector (TRD). The TRD is designed to separate positrons from the huge proton background with a high efficiency. A precision measurement of the positron fraction in the energy range from 0.5 to 350 GeV is presented. The accurate data show that the positron fraction is steadily increasing from 10 to 250 GeV with a decreasing slope by an order of magnitude between 20 and 250 GeV. The positron fraction spectrum shows no fine structure and no observable anisotropy. These observations show the existence of new physical phenomena whether from a particle physics or an astrophysical origin.
{"title":"The transition radiation detector of the alpha magnetic spectrometer(AMS-02) on the International Space Station and the precision measurement of the cosmic ray positron fraction","authors":"C. Chung","doi":"10.1109/NSSMIC.2013.6829508","DOIUrl":"https://doi.org/10.1109/NSSMIC.2013.6829508","url":null,"abstract":"On May 19th 2011, the AMS-02 experiment was successfully deployed on board the Earth-orbiting International Space Station (ISS) and is constantly operating since then without interruption. AMS is a complex particle detector in space and conducts research in astroparticle physics by precisely measuring charged cosmic particles to study acceleration, propagation and contributions from new particle physics and astrophysical sources. This is made possible by the main features of the AMS detector, namely its large acceptance, the long duration mission about 20 years limited by the ISS lifespan and the unique high proton rejection power by combining the electromagnetic calorimeter and the transition radiation detector (TRD). The TRD is designed to separate positrons from the huge proton background with a high efficiency. A precision measurement of the positron fraction in the energy range from 0.5 to 350 GeV is presented. The accurate data show that the positron fraction is steadily increasing from 10 to 250 GeV with a decreasing slope by an order of magnitude between 20 and 250 GeV. The positron fraction spectrum shows no fine structure and no observable anisotropy. These observations show the existence of new physical phenomena whether from a particle physics or an astrophysical origin.","PeriodicalId":246351,"journal":{"name":"2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (2013 NSS/MIC)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126966187","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 : 2013-10-01DOI: 10.1109/NSSMIC.2013.6829063
D. Xi, Chen Zeng, W. Liu, Xiang Liu, L. Wan, Heejong Kim, Luyao Wang, C. Kao, Q. Xie
Multi-voltage threshold (MVT) is an amplitude-based sampling method. It takes timing samples when the event pulse crosses the user-defined thresholds. Only a few comparators and TDCs are required when implementing such digitizer. Previously, we have demonstrated an FPGA-only MVT digitizer based on this method. The FPGA-only MVT digitizer employs the differential I/Os in an FPGA as the required comparators and FPGA based TDCs. The implementation of this digitizer is entirely based on the FPGA. We have demonstrated that it is possible to implement a significant number of MVT digitizers by using a single FPGA. It is also flexible, as it allows us to readily modify, or add functions to, the implementation without requiring costly hardware changes. Currently, we are developing a PET detector module using the FPGA-only MVT digitizer. In this paper we describe the design and implementation of the detector module and report its performance properties. The detector module has a total detection sensitive area of 50mm × 50mm, an overall energy resolution of 15.1% FWHM at 511keV, and a module-level coincidence timing resolution of 684ps FWHM. In addition, our preliminary imaging with such detector module successfully resolves 1.6mm-diameter rods separated by 3.2mm.
{"title":"A PET detector module using FPGA-only MVT digitizers","authors":"D. Xi, Chen Zeng, W. Liu, Xiang Liu, L. Wan, Heejong Kim, Luyao Wang, C. Kao, Q. Xie","doi":"10.1109/NSSMIC.2013.6829063","DOIUrl":"https://doi.org/10.1109/NSSMIC.2013.6829063","url":null,"abstract":"Multi-voltage threshold (MVT) is an amplitude-based sampling method. It takes timing samples when the event pulse crosses the user-defined thresholds. Only a few comparators and TDCs are required when implementing such digitizer. Previously, we have demonstrated an FPGA-only MVT digitizer based on this method. The FPGA-only MVT digitizer employs the differential I/Os in an FPGA as the required comparators and FPGA based TDCs. The implementation of this digitizer is entirely based on the FPGA. We have demonstrated that it is possible to implement a significant number of MVT digitizers by using a single FPGA. It is also flexible, as it allows us to readily modify, or add functions to, the implementation without requiring costly hardware changes. Currently, we are developing a PET detector module using the FPGA-only MVT digitizer. In this paper we describe the design and implementation of the detector module and report its performance properties. The detector module has a total detection sensitive area of 50mm × 50mm, an overall energy resolution of 15.1% FWHM at 511keV, and a module-level coincidence timing resolution of 684ps FWHM. In addition, our preliminary imaging with such detector module successfully resolves 1.6mm-diameter rods separated by 3.2mm.","PeriodicalId":246351,"journal":{"name":"2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (2013 NSS/MIC)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114955408","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}
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