Subjects: Physics >> Nuclear Physics submitted time 2025-07-03
Abstract： The energy response of an imaging detector based on a monolithic crystal is highly dependent on the position of the gamma ray interaction, which leads to a spectral drift of the imaging detector, known as the spectral drift related to incident position. It deteriorates the energy resolution of the detector and affects the selection of the energy window for imaging, resulting in artefacts in the reconstructed image. Thus, a energy response correction method is proposed to improve the positional consistency of the detector energy response. In both simulation and physical experiments, the method improved the full-energy peak consistency of the monolithic crystal detector, which results in improved energy resolution of the detector, more accurate selection of the energy window, and imaging quality. Especially, in physical experiments, the method converges the peak sites of 365keV energy at each location, which reduced the half-height width of characteristic peak (@365 keV) from 53 to 38 channels, improved the energy resolution by 28.3%, transformed the incomplete mask projection into a complete mask projection, and the signal-to-noise ratio increased from 2.38 to 5.37.
Peer Review Status:
Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2025-05-15
Abstract： The energy response of an imaging detector based on a monolithic crystal is highly dependent on the position of the gamma ray interaction, which leads to a spectral drift of the imaging detector, known as the spectral drift related to incident position. It deteriorates the energy resolution of the detector and affects the selection of the energy window for imaging, resulting in artefacts in the reconstructed image. Thus, a energy response correction method is proposed to improve the positional consistency of the detector energy response. In both simulation and physical experiments, the method improved the full-energy peak consistency of the monolithic crystal detector, which results in improved energy resolution of the detector, more accurate selection of the energy window, and imaging quality. Especially, in physical experiments, the method converges the peak sites of 365keV energy at each location, which reduced the half-height width of characteristic peak (@365 keV) from 53 to 38 channels, improved the energy resolution by 28.3%, transformed the incomplete mask projection into a complete mask projection, and the signal-to-noise ratio increased from 2.38 to 5.37.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2025-01-24
Abstract： The energy response of an imaging detector based on a monolithic crystal is highly dependent on the position of the gamma ray interaction, which leads to a spectral drift of the imaging detector, known as the spectral drift related to incident position. It deteriorates the energy resolution of the detector and affects the selection of the energy window for imaging, resulting in artefacts in the reconstructed image. Thus, a energy response correction method is proposed to improve the positional consistency of the detector energy response. In both simulation and physical experiments, the method improved the full-energy peak consistency of the monolithic crystal detector, which results in improved energy resolution of the detector, more accurate selection of the energy window, and imaging quality. Especially, in physical experiments, the method converges the peak sites of 365keV energy at each location, which reduced the half-height width of characteristic peak (@365 keV) from 53 to 38 channels, improved the energy resolution by 28.3%, transformed the incomplete mask projection into a complete mask projection, and the signal-to-noise ratio increased from 2.38 to 5.37.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2023-08-11
Abstract： A new scintillating fiber detector inside magnetic shielding tube was designed and assembled for use in the next round of fusion experiments in the experimental advanced superconducting tokamak to provide D–T neutron yield with time resolution. In this study, Geant4 simulations were used to obtain the pulse-height spectra for ideal signals produced when detecting neutrons and gamma rays of multiple energies. One of the main sources of interference was found to be low-energy neutrons below 10-5 MeV, which can generate numerous secondary particles in the detector components, such as the magnetic shielding tube, leading to high-amplitude output signals. To address this issue, a compact thermal neutron shield containing a 1 mm Cd layer outside the magnetic shielding tube and a 5 mm inner Pb layer was specifically designed. Adverse effects on the measurement of fast neutrons and the shielding effect on gamma rays were considered. This can suppress the height of the signals caused by thermal neutrons to a level below the height corresponding to neutrons above 4 MeV because the yield of the latter is used for detector calibration. In addition, the detector has relatively flat sensitivity curves in the fast neutron region, with the intrinsic detection efficiencies (IDEs) of approximately 40 %. For gamma rays with energies that are not too high (< 8 MeV), the IDEs of the detector are only approximately 20 %, whereas for gamma rays below 1 MeV, the response curve cuts off earlier in the low-energy region, which is beneficial for avoiding counting saturation and signal accumulation.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics Subjects: Astronomy >> Astronomical Instruments and Techniques Subjects: Materials Science >> Materials Science (General) submitted time 2023-12-15
Pei-Yi Feng
Xi-Lei Sun
Zheng-Hua An
Yong Deng
Cheng-Er Wang
Huang Jiang
Jun-Jie Li
Da-Li Zhang
Xin-Qiao Li
Shao-Lin Xiong
Chao Zheng
Ke Gong
Sheng Yang
Xiao-Jing Liu
Min Gao
Xiang-Yang Wen
Ya-Qing liu
Yan-Bing Xu
Xiao-Yun Zhao
Jia-Cong Liu
Abstract： The GECAM series of satellites utilizes LaBr3(Ce), LaBr3(Ce,Sr), and NaI(Tl) crystals as sensitive materials for gamma-ray detectors (GRDs). To investigate the non-linearity in the detection of low-energy gamma rays and address the errors in the calibration of the E-C relationship, comprehensive tests and comparative studies of the three aforementioned crystals were conducted using Compton electrons, radioactive sources, and monoenergetic X-rays. The non-linearity test results of the Compton electrons and X-rays demonstrated substantial differences, with all three crystals presenting a higher non-linearity for X/γ-rays than for Compton electrons. Despite the LaBr3(Ce) and LaBr3(Ce,Sr) crystals having higher absolute light yields, they exhibited a noticeable non-linear decrease in the light yield, especially at energies below 400 keV. The NaI(Tl) crystal demonstrated an "excess" light output in the 6–200 keV range, reaching a maximum "excess" of 9.2% at 30 keV in the X-ray testing and up to 15.5% at 14 keV during Compton electron testing, indicating a significant advantage in the detection of low-energy gamma rays. Furthermore, we explored the underlying causes of the observed non-linearity in these crystals. This study not only elucidates the detector responses of GECAM, but also initiates a comprehensive investigation of the non-linearity of domestically produced lanthanum bromide and sodium iodide crystals.
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