Pub Date : 2025-12-03DOI: 10.1016/j.radmeas.2025.107583
Xinyu Yang , Jian Yang , Guoqiang Zeng , Haowen Deng , Chengshuai Tian , Chuanhao Hu
For radioactive source localization, traditional Compton cameras are limited by the imaging field-of-view (FOV) and low detection efficiency, resulting in slow response in complex environments. To address the limitations in the azimuthal sensitivity of conventional dual-layer scintillator detectors and the sensitive volume of semiconductor detectors, this study proposes an omnidirectional Compton camera based on four-sided scintillator detectors with a square ring-shaped structure. This imaging system features omnidirectional sensitivity with a continuous 360° azimuthal response, significantly enhancing detection efficiency by minimizing the escape of scattered photons. The smallest imaging unit utilizes an independent CsI(Tl) crystal coupled with a single SiPM, which reduces light propagation loss and improves light collection efficiency to enhance energy resolution. To simplify the electronic systems, a serial readout circuit is employed to reduce the readout channels. The experimental results demonstrate that the total energy resolution for the 137Cs source was 6.2 % (FWHM) after calibrating the position and energy. Using the maximum likelihood expectation maximization algorithm for image reconstruction, the imaging system achieves accurate localization of radioactive sources with an angular resolution of 12° and clearly distinguishes the position of two radioactive sources.
{"title":"Development of an omnidirectional Compton camera with enhanced energy resolution for radioactive source localization","authors":"Xinyu Yang , Jian Yang , Guoqiang Zeng , Haowen Deng , Chengshuai Tian , Chuanhao Hu","doi":"10.1016/j.radmeas.2025.107583","DOIUrl":"10.1016/j.radmeas.2025.107583","url":null,"abstract":"<div><div>For radioactive source localization, traditional Compton cameras are limited by the imaging field-of-view (FOV) and low detection efficiency, resulting in slow response in complex environments. To address the limitations in the azimuthal sensitivity of conventional dual-layer scintillator detectors and the sensitive volume of semiconductor detectors, this study proposes an omnidirectional Compton camera based on four-sided scintillator detectors with a square ring-shaped structure. This imaging system features omnidirectional sensitivity with a continuous 360° azimuthal response, significantly enhancing detection efficiency by minimizing the escape of scattered photons. The smallest imaging unit utilizes an independent CsI(Tl) crystal coupled with a single SiPM, which reduces light propagation loss and improves light collection efficiency to enhance energy resolution. To simplify the electronic systems, a serial readout circuit is employed to reduce the readout channels. The experimental results demonstrate that the total energy resolution for the <sup>137</sup>Cs source was 6.2 % (FWHM) after calibrating the position and energy. Using the maximum likelihood expectation maximization algorithm for image reconstruction, the imaging system achieves accurate localization of radioactive sources with an angular resolution of 12° and clearly distinguishes the position of two radioactive sources.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"191 ","pages":"Article 107583"},"PeriodicalIF":2.2,"publicationDate":"2025-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145683165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-02DOI: 10.1016/j.radmeas.2025.107582
Joseph Graham , Brian Durtschi , Ashish Avachat , Seth Kilby
Methods for measuring the thickness of lead shielding based on 60Co gamma-ray spectroscopy are presented. In applications where a shield’s thickness is multiple mean free paths and the shield has a complex shape (i.e. cannot be approximated as a simple solid such as a slab, sphere, semi-infinite medium, etc.), the necessary buildup factors are not available. Thus, determination of shield thickness by means of the Beer–Lambert law requires separating the counts from uncollided photons from the scattered photon contribution. It is demonstrated how the 1332 keV gamma ray of 60Co can be used to precisely quantify lead thicknesses up to at least 280 mm. Use of the ratio of 1173 keV to 1332 keV photopeak areas to determine thickness is also discussed.
{"title":"Use of gamma-ray spectroscopy in thickness gauging of a complex-shaped lead shield","authors":"Joseph Graham , Brian Durtschi , Ashish Avachat , Seth Kilby","doi":"10.1016/j.radmeas.2025.107582","DOIUrl":"10.1016/j.radmeas.2025.107582","url":null,"abstract":"<div><div>Methods for measuring the thickness of lead shielding based on <sup>60</sup>Co gamma-ray spectroscopy are presented. In applications where a shield’s thickness is multiple mean free paths and the shield has a complex shape (i.e. cannot be approximated as a simple solid such as a slab, sphere, semi-infinite medium, etc.), the necessary buildup factors are not available. Thus, determination of shield thickness by means of the Beer–Lambert law requires separating the counts from uncollided photons from the scattered photon contribution. It is demonstrated how the 1332 keV gamma ray of <sup>60</sup>Co can be used to precisely quantify lead thicknesses up to at least <span><math><mo>∼</mo></math></span>280 mm. Use of the ratio of 1173 keV to 1332 keV photopeak areas to determine thickness is also discussed.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"191 ","pages":"Article 107582"},"PeriodicalIF":2.2,"publicationDate":"2025-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145683066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-28DOI: 10.1016/j.radmeas.2025.107566
Jacob C. Warming, Peter Balling, Rosana M. Turtos
Long-lived defect states in large-band-gap materials can potentially store energy from ionising radiation allowing the materials to be used as dosimeters. The population in many of these dosimetric traps can be read out with optically stimulated luminescence (OSL). OSL is associated with a cross section for the excitation probability, and the wavelength dependence of the cross section provides insight into the physical characteristics of the traps and allows for an optimised readout of OSL-dosimeters.
This paper suggests a novel approach to measuring the optical cross section using a pulsed tunable laser. A model of the evolution of the trap population is used to analyse data taken pulse-by-pulse to determine the cross sections in YSiO5:Ce. The cross sections are compared to theoretical models in order to determine the trap depth and phonon contribution. The wavelength-dependent cross section increases monotonically as the wavelength decreases, varying by more than two orders of magnitude from at the longest wavelengths (800 nm) to more than m in the green and blue part of the spectrum. Depending on the theoretical model used, the main trap depth is within the range 2.1–2.6 eV with a characteristic value of 2.3 eV, aligning with published results. Additionally, a notable phonon contribution is found with a magnitude that is consistent with previously reported phonon energies.
{"title":"Wavelength-dependent cross section for optically stimulated luminescence in Y2SiO5:Ce","authors":"Jacob C. Warming, Peter Balling, Rosana M. Turtos","doi":"10.1016/j.radmeas.2025.107566","DOIUrl":"10.1016/j.radmeas.2025.107566","url":null,"abstract":"<div><div>Long-lived defect states in large-band-gap materials can potentially store energy from ionising radiation allowing the materials to be used as dosimeters. The population in many of these dosimetric traps can be read out with optically stimulated luminescence (OSL). OSL is associated with a cross section for the excitation probability, and the wavelength dependence of the cross section provides insight into the physical characteristics of the traps and allows for an optimised readout of OSL-dosimeters.</div><div>This paper suggests a novel approach to measuring the optical cross section using a pulsed tunable laser. A model of the evolution of the trap population is used to analyse data taken pulse-by-pulse to determine the cross sections in Y<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>SiO<sub>5</sub>:Ce. The cross sections are compared to theoretical models in order to determine the trap depth and phonon contribution. The wavelength-dependent cross section increases monotonically as the wavelength decreases, varying by more than two orders of magnitude from <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>24</mn></mrow></msup></mrow></math></span> at the longest wavelengths (800 nm) to more than <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>22</mn></mrow></msup></mrow></math></span> m<span><math><msup><mrow></mrow><mrow><mn>2</mn></mrow></msup></math></span> in the green and blue part of the spectrum. Depending on the theoretical model used, the main trap depth is within the range 2.1–2.6 eV with a characteristic value of 2.3 eV, aligning with published results. Additionally, a notable phonon contribution is found with a magnitude that is consistent with previously reported phonon energies.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"191 ","pages":"Article 107566"},"PeriodicalIF":2.2,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145683168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-28DOI: 10.1016/j.radmeas.2025.107570
T. Genetay , L. Tlustos , M. Campbell , F. Bochud , P. Carbonez , J. Damet
This work presents, to the best of the authors’ knowledge, the first attempt at reconstructing X-ray spectra with a hybrid pixel detector for radiation protection applications in the scattered field around fluoroscopy devices. The performance of the Timepix4 detector was evaluated under reference conditions using RQR beam qualities. A dedicated methodology was developed to correct for detection efficiency, explicitly accounting for contributions from Compton scattering and the photoelectric effect. Accuracy was assessed through Monte Carlo simulations and comparisons with published RQR reference spectra. In addition, particle fluence measurements obtained with Timepix4 were validated against values derived from kerma factors and ionisation chamber measurements performed in a calibration laboratory. The results show excellent agreement between reconstructed and reference spectra up to , with residuals below 1.7% and relative photon fluence shifts within 5%. At higher energies, discrepancies increase due to the low detection efficiency of the silicon sensor, requiring large correction factors and leading to greater statistical fluctuations. Nevertheless, the system demonstrated acceptable performance up to , with fluence shifts remaining below 16%. Linearity was confirmed across all beam qualities and intensities investigated, consistent with previous studies on earlier Timepix ASIC generations. Overall, these findings demonstrate that Timepix4 can provide reliable spectral and fluence measurements in reference X-ray beams, offering valuable information for radiation protection studies in scattered fields where conventional detectors are of limited use. Future improvements in readout bandwidth and spectral deconvolution methods are expected to extend its applicability to higher energies and clinical environments.
{"title":"RQR beam qualities measurement with the Timepix4 detector","authors":"T. Genetay , L. Tlustos , M. Campbell , F. Bochud , P. Carbonez , J. Damet","doi":"10.1016/j.radmeas.2025.107570","DOIUrl":"10.1016/j.radmeas.2025.107570","url":null,"abstract":"<div><div>This work presents, to the best of the authors’ knowledge, the first attempt at reconstructing X-ray spectra with a hybrid pixel detector for radiation protection applications in the scattered field around fluoroscopy devices. The performance of the Timepix4 detector was evaluated under reference conditions using RQR beam qualities. A dedicated methodology was developed to correct for detection efficiency, explicitly accounting for contributions from Compton scattering and the photoelectric effect. Accuracy was assessed through Monte Carlo simulations and comparisons with published RQR reference spectra. In addition, particle fluence measurements obtained with Timepix4 were validated against values derived from kerma factors and ionisation chamber measurements performed in a calibration laboratory. The results show excellent agreement between reconstructed and reference spectra up to <span><math><mrow><mn>70</mn><mspace></mspace><mtext>keV</mtext></mrow></math></span>, with residuals below 1.7% and relative photon fluence shifts within 5%. At higher energies, discrepancies increase due to the low detection efficiency of the silicon sensor, requiring large correction factors and leading to greater statistical fluctuations. Nevertheless, the system demonstrated acceptable performance up to <span><math><mrow><mn>120</mn><mspace></mspace><mtext>keV</mtext></mrow></math></span>, with fluence shifts remaining below 16%. Linearity was confirmed across all beam qualities and intensities investigated, consistent with previous studies on earlier Timepix ASIC generations. Overall, these findings demonstrate that Timepix4 can provide reliable spectral and fluence measurements in reference X-ray beams, offering valuable information for radiation protection studies in scattered fields where conventional detectors are of limited use. Future improvements in readout bandwidth and spectral deconvolution methods are expected to extend its applicability to higher energies and clinical environments.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"191 ","pages":"Article 107570"},"PeriodicalIF":2.2,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The well-known CR-39, or poly allyl diglycol carbonate (PADC), has been widely used for personal neutron dosimetry for over 40 years. For providers of individual monitoring service (IMS) of neutron dose, it is necessary to establish an automatic reading system for CR-39 detectors in two aspects: to quickly measure a large number of detectors returned from users, and to ensure precision and accuracy that meet the requirements of the ISO/IEC 17025 standard. In this study, a novel high-speed and precise system composed of three parts was developed: (I) image acquisition of etched tracks on CR-39 detectors using an optical microscope with an autofocusing module and a high-speed scanning stage, (II) image processing of the tracks using an integrated software for automatic pit-counting on CR-39 (ISAP-39), including dedicated image processing in two steps, judging exposure in screening mode and evaluating neutron dose in precise reading mode, and (III) data reviewing by dosimetry experts. In the performance evaluation of the system, the following results were confirmed: high-speed scanning with 30 s per detector, high image-processing performance with 0 % false positive detection rate for neutron-induced tracks in screening and over 83 % true positive rate in precise reading, capability to describe differences in track features due to different neutron sources, and capability for precise dose measurements, including coefficient of variation, linearity, and track counting uncertainties. Moreover, in the operational study, the system was confirmed to be valid in terms of the screening function, threshold setting, pass rate stability in screening, and validity of precise reading and data reviewing. Consequently, the CR-39 reading system was proven to have sufficient performance in terms of reading speed and measurement precision.
{"title":"Development of a high-speed and precise automatic reading system of CR-39 plastic nuclear track detector for neutron dose measurements","authors":"Takuya Hashizume, Ryuji Akino, Hiroshi Sekiguchi, Chizuru Ojima, Yumi Kanie, Masami Sonda, Hiroki Hakamata, Akifumi Suzuki, Mitsuo Tsubomatsu, So Kitazawa, Yuki Oda","doi":"10.1016/j.radmeas.2025.107572","DOIUrl":"10.1016/j.radmeas.2025.107572","url":null,"abstract":"<div><div>The well-known CR-39, or poly allyl diglycol carbonate (PADC), has been widely used for personal neutron dosimetry for over 40 years. For providers of individual monitoring service (IMS) of neutron dose, it is necessary to establish an automatic reading system for CR-39 detectors in two aspects: to quickly measure a large number of detectors returned from users, and to ensure precision and accuracy that meet the requirements of the ISO/IEC 17025 standard. In this study, a novel high-speed and precise system composed of three parts was developed: (I) image acquisition of etched tracks on CR-39 detectors using an optical microscope with an autofocusing module and a high-speed scanning stage, (II) image processing of the tracks using an integrated software for automatic pit-counting on CR-39 (ISAP-39), including dedicated image processing in two steps, judging exposure in screening mode and evaluating neutron dose in precise reading mode, and (III) data reviewing by dosimetry experts. In the performance evaluation of the system, the following results were confirmed: high-speed scanning with 30 s per detector, high image-processing performance with 0 % false positive detection rate for neutron-induced tracks in screening and over 83 % true positive rate in precise reading, capability to describe differences in track features due to different neutron sources, and capability for precise dose measurements, including coefficient of variation, linearity, and track counting uncertainties. Moreover, in the operational study, the system was confirmed to be valid in terms of the screening function, threshold setting, pass rate stability in screening, and validity of precise reading and data reviewing. Consequently, the CR-39 reading system was proven to have sufficient performance in terms of reading speed and measurement precision.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"191 ","pages":"Article 107572"},"PeriodicalIF":2.2,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145790454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-26DOI: 10.1016/j.radmeas.2025.107571
S. Panzuela , A.M. Bruque , J. Macías
This study investigates the correction of the lateral response artifact (LRA) in accelerated protocols for radiochromic film dosimetry that shorten the time between irradiation and read-out. In these protocols, the LRA is assessed by pixel profiles along the longest axis of radiochromic film strips that are scanned parallel to the axis of artifact. The interplay between the non-uniform response of flatbed scanners and unavoidable heterogeneities in the radiation fields of linear accelerators modifies these pixel profiles, deviating them from their real behavior. This phenomenon has a negative impact on radiochromic film dosimetry. To solve this issue, first-order variations in the homogeneity of the radiation fields were subtracted from the pixel profiles. We studied dose distributions of 30 × 30 cm2 square fields at different dose levels and realistic radiotherapy treatment plans, using 6 MV and 6 MV flattening filter free energies. The radiochromic film models utilized were EBT4 and EBT-XD. For evaluation, gamma analysis (2 %,2 mm) and relative root mean square error metrics were employed. Comparisons against reference measurements demonstrate this novel correction is highly effective in suppressing radiation field heterogeneities, leading to enhanced dosimetric accuracy. Moreover, this study presents a semi-analytical expression for the LRA correction, which contributes to reducing uncertainties.
{"title":"On the correction of lateral response artifact in accelerated radiochromic film dosimetry protocols","authors":"S. Panzuela , A.M. Bruque , J. Macías","doi":"10.1016/j.radmeas.2025.107571","DOIUrl":"10.1016/j.radmeas.2025.107571","url":null,"abstract":"<div><div>This study investigates the correction of the lateral response artifact (LRA) in accelerated protocols for radiochromic film dosimetry that shorten the time between irradiation and read-out. In these protocols, the LRA is assessed by pixel profiles along the longest axis of radiochromic film strips that are scanned parallel to the axis of artifact. The interplay between the non-uniform response of flatbed scanners and unavoidable heterogeneities in the radiation fields of linear accelerators modifies these pixel profiles, deviating them from their real behavior. This phenomenon has a negative impact on radiochromic film dosimetry. To solve this issue, first-order variations in the homogeneity of the radiation fields were subtracted from the pixel profiles. We studied dose distributions of 30 × 30 cm<sup>2</sup> square fields at different dose levels and realistic radiotherapy treatment plans, using 6 MV and 6 MV flattening filter free energies. The radiochromic film models utilized were EBT4 and EBT-XD. For evaluation, gamma analysis (2 %,2 mm) and relative root mean square error metrics were employed. Comparisons against reference measurements demonstrate this novel correction is highly effective in suppressing radiation field heterogeneities, leading to enhanced dosimetric accuracy. Moreover, this study presents a semi-analytical expression for the LRA correction, which contributes to reducing uncertainties.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"191 ","pages":"Article 107571"},"PeriodicalIF":2.2,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145683065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rn-222 in water is not only a potential threat to human health, but also an important tracer for studying groundwater flow and crustal fracture system. The physical model of the existing method for measuring Rn-222 in water by the spray technique has not been made public. In this paper, a mathematical model for measuring Rn-222 concentration in water by spray method is established. A small spray device is designed and combined with RAD7 radon monitor to form a field measurement system for Rn-222 concentration in water. Six groups of field experiments were carried out in different locations around Yixin Lake in Hengyang Normal University, Hunan Province to verify the effectiveness of the model. The results show that the determination coefficient (R2) of the model is higher than 0.87, and the conversion efficiency of Rn-222 from water phase to gas phase is higher than 77 %, and the conversion efficiency is within two standard deviations. At the same time, the influence of leakage on the measurement results is analyzed. When the leakage rate exceeds 1 10−4 s−1, the measured Rn-222 concentration in water will be underestimated by about 20 %. The sensitivity of this measurement system is 0.0012 CPM/(Bq/m3). At a water temperature of 34.1 °C, the detection concentration range is from 0.7 to 133,689 Bq/m3.This study provides theoretical basis and technical support for rapid and accurate in-situ measurement of Rn-222 in natural water.
{"title":"Physical model construction and experimental verification of measuring Rn-222 concentration in water by spray method","authors":"Shicheng Luo, Zhongkai Fan, Ruomei Xie, Xinyue Yang, Xianfa Mao, Chenxi Zu, Feng Xiao, Hongbo Xu, Yi Liu, Hao You, Haoyu You, Jia Liu, Cheng Luo, Hongzhi Yuan, Yanliang Tan","doi":"10.1016/j.radmeas.2025.107573","DOIUrl":"10.1016/j.radmeas.2025.107573","url":null,"abstract":"<div><div>Rn-222 in water is not only a potential threat to human health, but also an important tracer for studying groundwater flow and crustal fracture system. The physical model of the existing method for measuring Rn-222 in water by the spray technique has not been made public. In this paper, a mathematical model for measuring Rn-222 concentration in water by spray method is established. A small spray device is designed and combined with RAD7 radon monitor to form a field measurement system for Rn-222 concentration in water. Six groups of field experiments were carried out in different locations around Yixin Lake in Hengyang Normal University, Hunan Province to verify the effectiveness of the model. The results show that the determination coefficient (R<sup>2</sup>) of the model is higher than 0.87, and the conversion efficiency of Rn-222 from water phase to gas phase is higher than 77 %, and the conversion efficiency is within two standard deviations. At the same time, the influence of leakage on the measurement results is analyzed. When the leakage rate exceeds 1 <span><math><mrow><mo>×</mo></mrow></math></span> 10<sup>−4</sup> s<sup>−1</sup>, the measured Rn-222 concentration in water will be underestimated by about 20 %. The sensitivity of this measurement system is 0.0012 CPM/(Bq/m<sup>3</sup>). At a water temperature of 34.1 °C, the detection concentration range is from 0.7 to 133,689 Bq/m<sup>3</sup>.This study provides theoretical basis and technical support for rapid and accurate in-situ measurement of Rn-222 in natural water.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"191 ","pages":"Article 107573"},"PeriodicalIF":2.2,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-22DOI: 10.1016/j.radmeas.2025.107567
Owen M. Williams, Nigel A. Spooner
We critically examine the quartz defect pair model, within which physical explanations of quartz thermoluminescence and optically stimulated luminescence (OSL) were introduced. We address the apparent circularity of the model, in that it appears to lack an appropriate OSL terminal reaction. In particular, by appropriately analysing prior spectral OSL measurements, we demonstrate that the prominent primary peak centred at 365 nm is accompanied by a smaller secondary peak. With this insight, we proceed to extend the existing defect pair model by introducing a new OSL reaction pair which not only takes account of the secondary peak but also offsets the source of the circularity. We complete our study by introducing a configurational coordinate diagram that includes a new terminating antibonding state, the presence of which is consistent with both the measurement data and our defect pair model extension.
{"title":"Offsetting circularity within an extended quartz luminescence defect pair model","authors":"Owen M. Williams, Nigel A. Spooner","doi":"10.1016/j.radmeas.2025.107567","DOIUrl":"10.1016/j.radmeas.2025.107567","url":null,"abstract":"<div><div>We critically examine the quartz defect pair model, within which physical explanations of quartz thermoluminescence and optically stimulated luminescence (OSL) were introduced. We address the apparent circularity of the model, in that it appears to lack an appropriate OSL terminal reaction. In particular, by appropriately analysing prior spectral OSL measurements, we demonstrate that the prominent primary peak centred at 365 nm is accompanied by a smaller secondary peak. With this insight, we proceed to extend the existing defect pair model by introducing a new OSL reaction pair which not only takes account of the secondary peak but also offsets the source of the circularity. We complete our study by introducing a configurational coordinate diagram that includes a new terminating antibonding state, the presence of which is consistent with both the measurement data and our defect pair model extension.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"191 ","pages":"Article 107567"},"PeriodicalIF":2.2,"publicationDate":"2025-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145683167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ban Phot Historical Park in Phetchabun province is a new historical park in Thailand. However, the fossil remains in this historical park have been reported by taxonomic identification to be originating from the Carboniferous–Permian period. Confirming the age of these remains using electron spin resonance (ESR) spectroscopy coupled with neutron activation analysis is necessary. Sedimentary rocks from Ban Phot Historical Park were separated into fossil shells and soils. Taxonomic identification indicated that the overall morphologies corresponded to a brachiopod, specifically Orthotichia javanapheti and Marginifera banphotensis. The chemical composition and crystal structure of the fossil shells were examined by X-ray fluorescence spectroscopy and X-ray diffractometry, respectively, revealing high silicon content and a quartz phase. All fossil shells were applied irradiation doses ranging from 0 to 15 kGy. Free radicals were measured by ESR spectroscopy to quantify the accumulated dose (AD). The results demonstrated that the free radicals comprised CO2− species derived from carbonate. The AD varied from 9298.6 ± 186.0 Gy to 9516.1 ± 190.3 Gy. Neutron activation analysis determined the concentrations of 238U, 232Th, and 40K in shells and soils for annual dose-rate (D) estimation. Thereafter, AD from ESR dating was combined with a Monte Carlo simulation to estimate fossil age. The ages obtained by ESR agreed with those derived via the Monte Carlo simulation using the DATA program, aligning with the Carboniferous period. Moreover, this age appears credible and may fill a gap in geological studies of the new historical park at Ban Phot, Phetchabun province.
{"title":"Electron spin resonance spectroscopy and Monte Carlo simulation for fossils age determination from new historical park in Thailand","authors":"Sirikorn Pongtornkulpanich , Patcharin Naemchanthara , Weeranut Kaewwiset , Sumalee Ninlaphruk , Pichet Limsuwan , Kittisakchai Naemchanthara","doi":"10.1016/j.radmeas.2025.107569","DOIUrl":"10.1016/j.radmeas.2025.107569","url":null,"abstract":"<div><div>Ban Phot Historical Park in Phetchabun province is a new historical park in Thailand. However, the fossil remains in this historical park have been reported by taxonomic identification to be originating from the Carboniferous–Permian period. Confirming the age of these remains using electron spin resonance (ESR) spectroscopy coupled with neutron activation analysis is necessary. Sedimentary rocks from Ban Phot Historical Park were separated into fossil shells and soils. Taxonomic identification indicated that the overall morphologies corresponded to a brachiopod, specifically <em>Orthotichia javanapheti</em> and <em>Marginifera banphotensis</em>. The chemical composition and crystal structure of the fossil shells were examined by X-ray fluorescence spectroscopy and X-ray diffractometry, respectively, revealing high silicon content and a quartz phase. All fossil shells were applied irradiation doses ranging from 0 to 15 kGy. Free radicals were measured by ESR spectroscopy to quantify the accumulated dose (<em>AD</em>). The results demonstrated that the free radicals comprised CO<sub>2</sub><sup>−</sup> species derived from carbonate. The <em>AD</em> varied from 9298.6 ± 186.0 Gy to 9516.1 ± 190.3 Gy. Neutron activation analysis determined the concentrations of <sup>238</sup>U, <sup>232</sup>Th, and <sup>40</sup>K in shells and soils for annual dose-rate (<em>D</em>) estimation. Thereafter, <em>AD</em> from ESR dating was combined with a Monte Carlo simulation to estimate fossil age. The ages obtained by ESR agreed with those derived via the Monte Carlo simulation using the DATA program, aligning with the Carboniferous period. Moreover, this age appears credible and may fill a gap in geological studies of the new historical park at Ban Phot, Phetchabun province.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"190 ","pages":"Article 107569"},"PeriodicalIF":2.2,"publicationDate":"2025-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145615329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-20DOI: 10.1016/j.radmeas.2025.107568
Rachel K. Smedley , Mae Fletcher , Alex Honnold , Aldo Kane , Heidi Sevestre
Exposure ages and erosion rates determined using rock surface luminescence have the potential to revolutionalise Quaternary Science. However, accurately quantifying μ (the light attenuation coefficient) is a significant challenge. Our study shows how variable light attenuation properties (i.e. μ) can be for five samples taken from a small (423 m) elevation range of a near-vertical gneiss rock wall, which we would have expected to have had a shared μ value. The light attenuation properties varied on multiple scales: (i) between samples; (ii) between replicate cores; and (iii) between slices within a core. To avoid the between sample variability, we need to either measure μ directly from the rock cores used to derive the exposure age or erosion rate, or prove that these samples and the sample used to calibrate μ have identical light attenuation properties. To avoid variability between replicate cores observed in samples, it may be more accurate to derive exposure ages or erosion rates using a single core with identical light attenuation properties to the sample used to calibrate μ. Finally, where possible, we should avoid rocks that have hetergeneous mixes of minerals with different opacities (lighter and darker). However, if it is not possible, we should routinely measure red-green-blue (RGB) values to link the presence of any low datapoints in the luminescence depth profiles to overlying lighter-coloured minerals that could have caused light ‘piping’. Our findings further emphasise the detailed consideration required for deriving μ to determine accurate exposure ages and erosion rates.
{"title":"Highly variable light attenuation across a gneiss rock wall in eastern Greenland","authors":"Rachel K. Smedley , Mae Fletcher , Alex Honnold , Aldo Kane , Heidi Sevestre","doi":"10.1016/j.radmeas.2025.107568","DOIUrl":"10.1016/j.radmeas.2025.107568","url":null,"abstract":"<div><div>Exposure ages and erosion rates determined using rock surface luminescence have the potential to revolutionalise Quaternary Science. However, accurately quantifying μ (the light attenuation coefficient) is a significant challenge. Our study shows how variable light attenuation properties (i.e. μ) can be for five samples taken from a small (423 m) elevation range of a near-vertical gneiss rock wall, which we would have expected to have had a shared μ value. The light attenuation properties varied on multiple scales: (i) between samples; (ii) between replicate cores; and (iii) between slices within a core. To avoid the between sample variability, we need to either measure μ directly from the rock cores used to derive the exposure age or erosion rate, or prove that these samples and the sample used to calibrate μ have identical light attenuation properties. To avoid variability between replicate cores observed in samples, it may be more accurate to derive exposure ages or erosion rates using a single core with identical light attenuation properties to the sample used to calibrate μ. Finally, where possible, we should avoid rocks that have hetergeneous mixes of minerals with different opacities (lighter and darker). However, if it is not possible, we should routinely measure red-green-blue (RGB) values to link the presence of any low datapoints in the luminescence depth profiles to overlying lighter-coloured minerals that could have caused light ‘piping’. Our findings further emphasise the detailed consideration required for deriving μ to determine accurate exposure ages and erosion rates.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"190 ","pages":"Article 107568"},"PeriodicalIF":2.2,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145615321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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