Background^(131)I is a critical radionuclide in nuclear medicine,particularly for thyroid disorder therapies.Chinese national standards mandate reducing^(131)I concentrations in radioactive waste liquid to below 10 Bq...Background^(131)I is a critical radionuclide in nuclear medicine,particularly for thyroid disorder therapies.Chinese national standards mandate reducing^(131)I concentrations in radioactive waste liquid to below 10 Bq/L.To address this requirement,rapid and precise quantification of^(131)I activity is essential for compliance monitoring and clinical safety.Methods A detection system integrating a NaI(Tl)crystal and a silicon photomultiplier array was developed to measure the^(131)I concentrations via its 364.5 keV characteristic\(\gamma\)-ray emissions.The setup incorporates 5 cm oxygen-free copper and 5 cm lead shielding to mitigate external\(\gamma\)-ray interference.Sample analysis utilizes a 50 mL aliquot,with system sensitivity evaluated under varying measurement durations.Results Under optimized shielding conditions,the system achieved a minimum detectable activity of 8.0 Bq/L for^(131)I within a 3-hour measurement period.Extending the acquisition time to 24 hours enhanced sensitivity to 2.8 Bq/L,surpassing the regulatory threshold requirement of 10 Bq/L.Conclusions The developed system demonstrates sufficient sensitivity and accuracy for monitoring^(131)I in radioactive waste liquids,aligning with national emission standards.The time-dependent sensitivity improvement highlights its adaptability for both rapid screening and low-concentration quantification,thus validating its applicability in nuclear medicine waste management.展开更多
Background Liquid Argon(LAr)is used as a target material in several current and planned experiments related to dark matter direct searching and neutrino detection.Argon provides excellent pulse shape discrimination(PS...Background Liquid Argon(LAr)is used as a target material in several current and planned experiments related to dark matter direct searching and neutrino detection.Argon provides excellent pulse shape discrimination(PSD)capability,which could separate the electron recoil backgrounds from the expected nuclear recoil signals.As the next-generation photosensors,silicon photon multiplier(SiPM)is expected to replace traditional photon multiplier tubes.Purpose The purpose of this paper is to compare the PSD capability of a LAr detector between using SiPMs as photosensors and using PMTs as photosensors.Methods The PSD capability of a LAr detector is determined through the prompt fraction method,which relies on the analysis of output pulses.These pulses are generated using Monte Carlo simulation,incorporating real single photoelectron pulses obtained from a PMT or a SiPM.Results Three kinds of SiPMs and one kind of PMT have been used to compare the PSD capability of a LAr detector.The use of J-60035 SiPM results in a better PSD capability compared to the use of PMT as a photosensor,while using the other two kinds of SiPM deteriorates the PSD capability.Conclusion SiPM is a promising photosensor candidate for a LAr detector.The better energy resolution could help to improve its PSD capability,while the higher probabilities of cross-talk and after-pulse degrade its PSD capability.Notably,after-pulse has a more significant impact compared to cross-talk because after-pulse influences the energy distribution within the time window,while cross-talk primarily affects the energy resolution of the detector.展开更多
基金the National Institute of Metrology of China for providing the standard^(131)I solutionsupported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2023015).
文摘Background^(131)I is a critical radionuclide in nuclear medicine,particularly for thyroid disorder therapies.Chinese national standards mandate reducing^(131)I concentrations in radioactive waste liquid to below 10 Bq/L.To address this requirement,rapid and precise quantification of^(131)I activity is essential for compliance monitoring and clinical safety.Methods A detection system integrating a NaI(Tl)crystal and a silicon photomultiplier array was developed to measure the^(131)I concentrations via its 364.5 keV characteristic\(\gamma\)-ray emissions.The setup incorporates 5 cm oxygen-free copper and 5 cm lead shielding to mitigate external\(\gamma\)-ray interference.Sample analysis utilizes a 50 mL aliquot,with system sensitivity evaluated under varying measurement durations.Results Under optimized shielding conditions,the system achieved a minimum detectable activity of 8.0 Bq/L for^(131)I within a 3-hour measurement period.Extending the acquisition time to 24 hours enhanced sensitivity to 2.8 Bq/L,surpassing the regulatory threshold requirement of 10 Bq/L.Conclusions The developed system demonstrates sufficient sensitivity and accuracy for monitoring^(131)I in radioactive waste liquids,aligning with national emission standards.The time-dependent sensitivity improvement highlights its adaptability for both rapid screening and low-concentration quantification,thus validating its applicability in nuclear medicine waste management.
基金supported by the National Natural Science Foundation of China(Grant Nos.12275289,11975257,and 12175247)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2023015)the National Key R&D Program of China(Grant No.2016YFA0400304).
文摘Background Liquid Argon(LAr)is used as a target material in several current and planned experiments related to dark matter direct searching and neutrino detection.Argon provides excellent pulse shape discrimination(PSD)capability,which could separate the electron recoil backgrounds from the expected nuclear recoil signals.As the next-generation photosensors,silicon photon multiplier(SiPM)is expected to replace traditional photon multiplier tubes.Purpose The purpose of this paper is to compare the PSD capability of a LAr detector between using SiPMs as photosensors and using PMTs as photosensors.Methods The PSD capability of a LAr detector is determined through the prompt fraction method,which relies on the analysis of output pulses.These pulses are generated using Monte Carlo simulation,incorporating real single photoelectron pulses obtained from a PMT or a SiPM.Results Three kinds of SiPMs and one kind of PMT have been used to compare the PSD capability of a LAr detector.The use of J-60035 SiPM results in a better PSD capability compared to the use of PMT as a photosensor,while using the other two kinds of SiPM deteriorates the PSD capability.Conclusion SiPM is a promising photosensor candidate for a LAr detector.The better energy resolution could help to improve its PSD capability,while the higher probabilities of cross-talk and after-pulse degrade its PSD capability.Notably,after-pulse has a more significant impact compared to cross-talk because after-pulse influences the energy distribution within the time window,while cross-talk primarily affects the energy resolution of the detector.
