The GECAM series of satellites utilizes LaBr_(3)(Ce),LaBr_(3)(Ce,Sr),and NaI(Tl)crystals as sensitive materials for gamma-ray detectors(GRDs).To investigate the nonlinearity in the detection of low-energy gamma rays a...The GECAM series of satellites utilizes LaBr_(3)(Ce),LaBr_(3)(Ce,Sr),and NaI(Tl)crystals as sensitive materials for gamma-ray detectors(GRDs).To investigate the nonlinearity 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 mono-energetic X-rays.The nonlinearity test results of the Compton electrons and X-rays demonstrated substantial differences,with all three crystals presenting a higher nonlinearity for X/-rays than for Compton electrons.Despite the LaBr_(3)(Ce)and LaBr_(3)(Ce,Sr)crystals having higher absolute light yields,they exhibited a noticeable nonlinear 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 nonlinearity in these crystals.This study not only elucidates the detector responses of GECAM,but also initiates a comprehensive investigation of the nonlinearity of domestically produced lanthanum bromide and sodium iodide crystals.展开更多
点源与探测器相对位置发生变化时,探测效率会发生很大变化,确定探测效率随探测距、角度变化的函数关系有利于快速得到点源在任意位置处的探测效率。利用蒙特卡罗软件MCNP5模拟计算了^(152)Eu、^(137)Cs、^(60)Co点源在特定位置处的探测...点源与探测器相对位置发生变化时,探测效率会发生很大变化,确定探测效率随探测距、角度变化的函数关系有利于快速得到点源在任意位置处的探测效率。利用蒙特卡罗软件MCNP5模拟计算了^(152)Eu、^(137)Cs、^(60)Co点源在特定位置处的探测效率,与实验结果相比,最大误差不超过6%。基于MCNP5对3.81 cm LaBr_(3)(Ce)探测器做效率刻度,并计算了点源在探测器正面2π空间范围内不同位置处的探测效率,拟合了探测效率与角度和距离的函数关系。结果表明:点源探测效率最大值出现在与探测器轴线夹角90°处,随着探测距离和能量的增大,角度对点源探测效率的影响逐渐减小;空间位置对探测效率的影响实际上是对点源相对于探测器的空间立体角效率。基于效率函数可计算出特定能量γ射线在空间任意位置处的探测效率,对LaBr_(3)(Ce)探测器效率矩阵的求解及效率刻度具有一定的参考价值和指导意义。展开更多
A scintillator detector consisting of a LaBr_(3)(Ce)(0.5%)scintillator,a photomultiplier tube(PMT),and an oscilloscope were used to study the neutron sensitivities of the LaBr_(3)(Ce)scintillator at the China Spallati...A scintillator detector consisting of a LaBr_(3)(Ce)(0.5%)scintillator,a photomultiplier tube(PMT),and an oscilloscope were used to study the neutron sensitivities of the LaBr_(3)(Ce)scintillator at the China Spallation Neutron Source(CSNS)Back-n white neutron source in the double-bunch and single-bunch operation modes,respectively.Under the two operational modes,the relative neutron sensitivity curves of the LaBr_(3)(Ce)scintillator in the energy regions of 1–20 MeV and 0.5–20 MeV were obtained for the first time.In the energy range of 1–20 MeV,the two curves were nearly identical.However the relative neutron sensitivity uncertainties of the double-bunch experiment were higher than those of the single-bunch experiment.The above results indicated that the single-bunch experiment's neutron sensitivity curve has a lower minimum measurable energy than the double-bunch experiment.Above the minimum measurable energy of the double-bunch experiment,there is little difference between the measured relative neutron sensitivity curves of the single-bunch and double-bunch experiments of the LaBr_(3)(Ce)scintillator and those of other scintillators with a similar neutron response signal intensity.展开更多
基金This work was supported by the National Key Research and Development Program(Nos.2022YFB3503600 and 2021YFA0718500)Strategic Priority Research Program of the Chinese Academy of Sciences(Nos.XDA15360102)National Natural Science Foundation of China(Nos.12273042 and 12075258).
文摘The GECAM series of satellites utilizes LaBr_(3)(Ce),LaBr_(3)(Ce,Sr),and NaI(Tl)crystals as sensitive materials for gamma-ray detectors(GRDs).To investigate the nonlinearity 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 mono-energetic X-rays.The nonlinearity test results of the Compton electrons and X-rays demonstrated substantial differences,with all three crystals presenting a higher nonlinearity for X/-rays than for Compton electrons.Despite the LaBr_(3)(Ce)and LaBr_(3)(Ce,Sr)crystals having higher absolute light yields,they exhibited a noticeable nonlinear 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 nonlinearity in these crystals.This study not only elucidates the detector responses of GECAM,but also initiates a comprehensive investigation of the nonlinearity of domestically produced lanthanum bromide and sodium iodide crystals.
文摘点源与探测器相对位置发生变化时,探测效率会发生很大变化,确定探测效率随探测距、角度变化的函数关系有利于快速得到点源在任意位置处的探测效率。利用蒙特卡罗软件MCNP5模拟计算了^(152)Eu、^(137)Cs、^(60)Co点源在特定位置处的探测效率,与实验结果相比,最大误差不超过6%。基于MCNP5对3.81 cm LaBr_(3)(Ce)探测器做效率刻度,并计算了点源在探测器正面2π空间范围内不同位置处的探测效率,拟合了探测效率与角度和距离的函数关系。结果表明:点源探测效率最大值出现在与探测器轴线夹角90°处,随着探测距离和能量的增大,角度对点源探测效率的影响逐渐减小;空间位置对探测效率的影响实际上是对点源相对于探测器的空间立体角效率。基于效率函数可计算出特定能量γ射线在空间任意位置处的探测效率,对LaBr_(3)(Ce)探测器效率矩阵的求解及效率刻度具有一定的参考价值和指导意义。
基金Project supported by the National Natural Science Foundation of China(Grant No.11905196)。
文摘A scintillator detector consisting of a LaBr_(3)(Ce)(0.5%)scintillator,a photomultiplier tube(PMT),and an oscilloscope were used to study the neutron sensitivities of the LaBr_(3)(Ce)scintillator at the China Spallation Neutron Source(CSNS)Back-n white neutron source in the double-bunch and single-bunch operation modes,respectively.Under the two operational modes,the relative neutron sensitivity curves of the LaBr_(3)(Ce)scintillator in the energy regions of 1–20 MeV and 0.5–20 MeV were obtained for the first time.In the energy range of 1–20 MeV,the two curves were nearly identical.However the relative neutron sensitivity uncertainties of the double-bunch experiment were higher than those of the single-bunch experiment.The above results indicated that the single-bunch experiment's neutron sensitivity curve has a lower minimum measurable energy than the double-bunch experiment.Above the minimum measurable energy of the double-bunch experiment,there is little difference between the measured relative neutron sensitivity curves of the single-bunch and double-bunch experiments of the LaBr_(3)(Ce)scintillator and those of other scintillators with a similar neutron response signal intensity.
