Pub Date : 2026-06-01Epub Date: 2026-02-03DOI: 10.1016/j.nima.2026.171353
Rafael Ballabriga , Eric Buschmann , Michael Campbell , Raimon Casanova Mohr , Dominik Dannheim , Jona Dilg , Ana Dorda , Ono Feyens , Finn King , Philipp Gadow , Ingrid-Maria Gregor , Karsten Hansen , Yajun He , Lennart Huth , Iraklis Kremastiotis , Stephan Lachnit , Corentin Lemoine , Stefano Maffessanti , Larissa Mendes , Younes Otarid , Håkan Wennlöf
The H2M (Hybrid-to-Monolithic) is a monolithic pixel sensor manufactured in a modified 65 nm CMOS imaging process with a small collection electrode. Its design addresses the challenges of porting an existing hybrid pixel detector architecture into a monolithic chip, using a digital-on-top design methodology, and developing a compact digital cell library. Each square pixel integrates an analog front-end and digital pulse processing with an 8-bit counter within a 35 m pitch.
This contribution presents the performance of H2M based on laboratory and test beam measurements, including a comparison with analog front-end simulations in terms of gain and noise. A particular emphasis is placed on backside thinning in order to reduce material budget, down to a total chip thickness of 21 m for which no degradation in MIP detection performance is observed. For all investigated samples, a MIP detection efficiency above 99% is achieved below a threshold of approximately 205 electrons. At this threshold, the fake-hit rate corresponds to a matrix occupancy of fewer than one pixel per the 500 ns frame.
Measurements reveal a non-uniform in-pixel response, attributed to the formation of local potential wells in regions with low electric field. A simulation flow combining technology computer-aided design, Monte Carlo, and circuit simulations is used to investigate and describe this behavior, and is applied to develop mitigation strategies for future chip submissions with similar features.
{"title":"Characterization of the H2M monolithic CMOS sensor","authors":"Rafael Ballabriga , Eric Buschmann , Michael Campbell , Raimon Casanova Mohr , Dominik Dannheim , Jona Dilg , Ana Dorda , Ono Feyens , Finn King , Philipp Gadow , Ingrid-Maria Gregor , Karsten Hansen , Yajun He , Lennart Huth , Iraklis Kremastiotis , Stephan Lachnit , Corentin Lemoine , Stefano Maffessanti , Larissa Mendes , Younes Otarid , Håkan Wennlöf","doi":"10.1016/j.nima.2026.171353","DOIUrl":"10.1016/j.nima.2026.171353","url":null,"abstract":"<div><div>The H2M (Hybrid-to-Monolithic) is a monolithic pixel sensor manufactured in a modified 65 nm CMOS imaging process with a small collection electrode. Its design addresses the challenges of porting an existing hybrid pixel detector architecture into a monolithic chip, using a digital-on-top design methodology, and developing a compact digital cell library. Each square pixel integrates an analog front-end and digital pulse processing with an 8-bit counter within a 35 <span><math><mi>μ</mi></math></span>m pitch.</div><div>This contribution presents the performance of H2M based on laboratory and test beam measurements, including a comparison with analog front-end simulations in terms of gain and noise. A particular emphasis is placed on backside thinning in order to reduce material budget, down to a total chip thickness of 21 <span><math><mi>μ</mi></math></span>m for which no degradation in MIP detection performance is observed. For all investigated samples, a MIP detection efficiency above 99% is achieved below a threshold of approximately 205 electrons. At this threshold, the fake-hit rate corresponds to a matrix occupancy of fewer than one pixel per the 500 ns frame.</div><div>Measurements reveal a non-uniform in-pixel response, attributed to the formation of local potential wells in regions with low electric field. A simulation flow combining technology computer-aided design, Monte Carlo, and circuit simulations is used to investigate and describe this behavior, and is applied to develop mitigation strategies for future chip submissions with similar features.</div></div>","PeriodicalId":19359,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment","volume":"1086 ","pages":"Article 171353"},"PeriodicalIF":1.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146191075","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 : 2026-06-01Epub Date: 2026-02-03DOI: 10.1016/j.nima.2026.171362
Meng Li , Philip Bambade , Dou Wang , Naoko Iida , Yoshihiro Funakoshi , Hiroshi Kaji , Yukiyoshi Ohnishi , Taichiro Koga , Jie Gao , Urbschat Bela , Hiroyuki Nakayama , Andrii Natochii , Haruyo Koiso , Kazuhito Ohmi , Kenta Uno , Qingyuan Liu
At SuperKEKB, the maximum achievable beam currents and the luminosity are projected to be constrained by beam injection in the near future. Recent attempts to squeeze the vertical beta function at the IP or increase beam currents have not yielded the expected improvements in luminosity, with poor injection performance in both rings being a major factor. The injection efficiencies are lower than half of the required value and large background signals are observed in the Belle II detector and other beam loss monitors. To avoid a sudden increase in background caused by injection, the Belle II trigger system is vetoed for several tens of milliseconds just after beam injection, leading to significant dead time. These injection issues are expected to become even more severe as luminosity increases, making beam injection one of the major bottleneck to achieving the target luminosity. To investigate and address these issues, detailed injection simulations for the high-energy ring (HER) were performed and compared with dedicated experimental measurements, providing valuable insights into injection-related beam loss mechanisms and offering practical strategies to improve injection efficiency while mitigating injection-induced backgrounds. This paper presents these findings together with their experimental validation.
{"title":"Injection-related beam loss in the high-energy ring of SuperKEKB","authors":"Meng Li , Philip Bambade , Dou Wang , Naoko Iida , Yoshihiro Funakoshi , Hiroshi Kaji , Yukiyoshi Ohnishi , Taichiro Koga , Jie Gao , Urbschat Bela , Hiroyuki Nakayama , Andrii Natochii , Haruyo Koiso , Kazuhito Ohmi , Kenta Uno , Qingyuan Liu","doi":"10.1016/j.nima.2026.171362","DOIUrl":"10.1016/j.nima.2026.171362","url":null,"abstract":"<div><div>At SuperKEKB, the maximum achievable beam currents and the luminosity are projected to be constrained by beam injection in the near future. Recent attempts to squeeze the vertical beta function at the IP or increase beam currents have not yielded the expected improvements in luminosity, with poor injection performance in both rings being a major factor. The injection efficiencies are lower than half of the required value and large background signals are observed in the Belle II detector and other beam loss monitors. To avoid a sudden increase in background caused by injection, the Belle II trigger system is vetoed for several tens of milliseconds just after beam injection, leading to significant dead time. These injection issues are expected to become even more severe as luminosity increases, making beam injection one of the major bottleneck to achieving the target luminosity. To investigate and address these issues, detailed injection simulations for the high-energy ring (HER) were performed and compared with dedicated experimental measurements, providing valuable insights into injection-related beam loss mechanisms and offering practical strategies to improve injection efficiency while mitigating injection-induced backgrounds. This paper presents these findings together with their experimental validation.</div></div>","PeriodicalId":19359,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment","volume":"1086 ","pages":"Article 171362"},"PeriodicalIF":1.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190885","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 : 2026-06-01Epub Date: 2026-01-28DOI: 10.1016/j.nima.2026.171333
Junliang Zhang, Ding Ma, Quan Wu, Rongliang Zhang, Shenshen Hou, Wenhao Su, Jianxiong Shao, Ximeng Chen, Lin Chen, Yanling Guo
Accurate measurement of the activity of medical radioactive isotopes is crucial for ensuring the safety of diagnosis and treatment as well as patient therapeutic efficacy. A calorimeter is designed to measure the decay heat generated by medical radioisotopes in microwatt precision, based on the thermopile heat-flow sensors used for twin cylinder chambers. The simulation reveals that the equilibrium temperature distribution inside of the calorimeter can be precisely controlled by the water bath and the automatic thermostatic control components. The experimental results show that the temperature control accuracy can reach ±0.0005 °C under the proportional-integral-derivative regulation. The output thermoelectric potential shows a significant linear relationship with the input thermal power, achieving a sensitivity coefficient of 0.297 V/W during the electrical power calibration of the calorimeter. The lowest detectable thermal power is 1.6 μW in the steady-state equilibrium mode with the baseline correction. The minimum time to establish thermal equilibrium is about 15 min for microwatt power, and approximately 30 min for milliwatt power, respectively.
{"title":"A microwatt calorimeter for medical radioisotopes","authors":"Junliang Zhang, Ding Ma, Quan Wu, Rongliang Zhang, Shenshen Hou, Wenhao Su, Jianxiong Shao, Ximeng Chen, Lin Chen, Yanling Guo","doi":"10.1016/j.nima.2026.171333","DOIUrl":"10.1016/j.nima.2026.171333","url":null,"abstract":"<div><div>Accurate measurement of the activity of medical radioactive isotopes is crucial for ensuring the safety of diagnosis and treatment as well as patient therapeutic efficacy. A calorimeter is designed to measure the decay heat generated by medical radioisotopes in microwatt precision, based on the thermopile heat-flow sensors used for twin cylinder chambers. The simulation reveals that the equilibrium temperature distribution inside of the calorimeter can be precisely controlled by the water bath and the automatic thermostatic control components. The experimental results show that the temperature control accuracy can reach ±0.0005 °C under the proportional-integral-derivative regulation. The output thermoelectric potential shows a significant linear relationship with the input thermal power, achieving a sensitivity coefficient of 0.297 V/W during the electrical power calibration of the calorimeter. The lowest detectable thermal power is 1.6 μW in the steady-state equilibrium mode with the baseline correction. The minimum time to establish thermal equilibrium is about 15 min for microwatt power, and approximately 30 min for milliwatt power, respectively.</div></div>","PeriodicalId":19359,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment","volume":"1086 ","pages":"Article 171333"},"PeriodicalIF":1.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190979","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 : 2026-06-01Epub Date: 2026-02-11DOI: 10.1016/j.nima.2026.171377
S.B. Ma , Y. Xu , X.H. Zhang , B.M. Wu , T.J. Yang , S.J. Zheng , X.C. Kang , Z. Chai , P. Ma , B. Yang , X. Zhang , L.A. Jin , J. Hu , Z.G. Gan , Z.Y. Sun , H.S. Xu
A multi-purpose superconducting solenoid separator has been designed to investigate low-energy, low cross-section nuclear reactions and their products at the High Intensity heavy-ion Accelerator Facility (HIAF). The separator’s performance in collecting and purifying reaction products has been systematically evaluated. Simulation results show that the separator achieves a polar angle acceptance of , momentum acceptance exceeding , and maximum magnetic rigidity of , enabling effective collection of products from fusion-evaporation, multi-nucleon transfer, and one-nucleon transfer reactions. For purification, it exhibits excellent background suppression for fusion evaporation and one-nucleon transfer products. However, for near symmetric multi-nucleon transfer products, overlapping magnetic rigidity distributions with background particles and the separator’s relatively small dispersion results in ineffective background filtering. Thus, a particle identification detection system with triggering functionality is required for further background suppression. This research would provide technical support for low-energy nuclear physics research at the HIAF facility and contributes to advancements in cutting-edge fields such as the production and property studies of proton-rich and neutron-rich heavy nuclei, as well as nuclear astrophysics research.
{"title":"Design of a multi-purpose superconducting solenoid separator at HIAF","authors":"S.B. Ma , Y. Xu , X.H. Zhang , B.M. Wu , T.J. Yang , S.J. Zheng , X.C. Kang , Z. Chai , P. Ma , B. Yang , X. Zhang , L.A. Jin , J. Hu , Z.G. Gan , Z.Y. Sun , H.S. Xu","doi":"10.1016/j.nima.2026.171377","DOIUrl":"10.1016/j.nima.2026.171377","url":null,"abstract":"<div><div>A multi-purpose superconducting solenoid separator has been designed to investigate low-energy, low cross-section nuclear reactions and their products at the High Intensity heavy-ion Accelerator Facility (HIAF). The separator’s performance in collecting and purifying reaction products has been systematically evaluated. Simulation results show that the separator achieves a polar angle acceptance of <span><math><mrow><mo>±</mo><mn>11</mn><mo>.</mo><mn>5</mn><mo>°</mo></mrow></math></span>, momentum acceptance exceeding <span><math><mrow><mo>±</mo><mn>15</mn><mtext>%</mtext></mrow></math></span>, and maximum magnetic rigidity of <span><math><mrow><mn>2</mn><mo>.</mo><mn>2</mn><mspace></mspace><mi>Tm</mi></mrow></math></span>, enabling effective collection of products from fusion-evaporation, multi-nucleon transfer, and one-nucleon transfer reactions. For purification, it exhibits excellent background suppression for fusion evaporation and one-nucleon transfer products. However, for near symmetric multi-nucleon transfer products, overlapping magnetic rigidity distributions with background particles and the separator’s relatively small dispersion results in ineffective background filtering. Thus, a particle identification detection system with triggering functionality is required for further background suppression. This research would provide technical support for low-energy nuclear physics research at the HIAF facility and contributes to advancements in cutting-edge fields such as the production and property studies of proton-rich and neutron-rich heavy nuclei, as well as nuclear astrophysics research.</div></div>","PeriodicalId":19359,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment","volume":"1086 ","pages":"Article 171377"},"PeriodicalIF":1.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190978","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 : 2026-06-01Epub Date: 2026-01-28DOI: 10.1016/j.nima.2026.171335
Wangtao Yu , Peng Xu , Jie Bao , Man Zhou , Yuxin Lei , Yu Wang
The collimator is a critical component of fast neutron radiography system, as its performance directly influences both neutron beam quality and image resolution. In this paper, the simulation design and optimization of a multi-layer composite structure collimator is carried out for the D-T neutron generator. The optimal material, thickness for each functional layer, and the channel shape were determined using Geant4 simulations. Additionally, the designed collimator system was validated by simulating radiography of an iron slit sample and a tungsten block sample. Simulation results show that within a Ф30 mm field of view, the system exhibits a neutron fluence inhomogeneity of 2.78 %, a beam parallelism of 0.9955, an uncollided neutron fraction of 97.69 %, and a neutron-to-gamma fluence ratio of 40.81. The simulated imaging further confirms the system's good spatial resolution and its ability to provide a high-quality collimated neutron beam for high-performance fast neutron radiography. This study provides a reliable theoretical foundation and a systematic design methodology for collimators in D-T neutron generator-based fast neutron radiography systems.
{"title":"Simulation design of the collimator for fast neutron radiography system based on D-T neutron generator","authors":"Wangtao Yu , Peng Xu , Jie Bao , Man Zhou , Yuxin Lei , Yu Wang","doi":"10.1016/j.nima.2026.171335","DOIUrl":"10.1016/j.nima.2026.171335","url":null,"abstract":"<div><div>The collimator is a critical component of fast neutron radiography system, as its performance directly influences both neutron beam quality and image resolution. In this paper, the simulation design and optimization of a multi-layer composite structure collimator is carried out for the D-T neutron generator. The optimal material, thickness for each functional layer, and the channel shape were determined using Geant4 simulations. Additionally, the designed collimator system was validated by simulating radiography of an iron slit sample and a tungsten block sample. Simulation results show that within a Ф30 mm field of view, the system exhibits a neutron fluence inhomogeneity of 2.78 %, a beam parallelism of 0.9955, an uncollided neutron fraction of 97.69 %, and a neutron-to-gamma fluence ratio of 40.81. The simulated imaging further confirms the system's good spatial resolution and its ability to provide a high-quality collimated neutron beam for high-performance fast neutron radiography. This study provides a reliable theoretical foundation and a systematic design methodology for collimators in D-T neutron generator-based fast neutron radiography systems.</div></div>","PeriodicalId":19359,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment","volume":"1086 ","pages":"Article 171335"},"PeriodicalIF":1.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146070982","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 : 2026-05-01Epub Date: 2026-01-25DOI: 10.1016/j.nima.2026.171313
Hexin Wang , Huachang Liu , Zhencheng Mu , Hui Zhang , Linyan Rong , Zhexin Xie , Maliang Wan , Bo Wang , Bilawal Ali , Kai Guo , Xuanming Zhang , Shaozhe Wang , Yongming Li , Zhaoyun Duan , Yubin Gong
This paper reports the development and experimental validation of a compact metamaterial-loaded 324 MHz/3 MW klystron power system designed for the China Spallation Neutron Source (CSNS) proton linear accelerator. Conventional P-band klystrons deployed at CSNS, suffer from large physical dimensions and heavy weight, imposing constraints on system integration and cost. To address these limitations, a novel metamaterial-loaded klystron (M-klystron) incorporating complementary electric split-ring resonators (CeSRRs) and a second harmonic cavity is proposed, fabricated, and hot-tested. Particle-in-cell (PIC) simulations demonstrated that the M-klystron could achieve an output power of 2.97 MW at 324 MHz. The power system is driven by a self-developed long-pulse solid-state modulator, capable of delivering stable −110 kV, 51.5 A pulses at 25 Hz with a flat-top width of 950 μs, alongside a low-level RF (LLRF) control system ensuring precise amplitude and phase stabilization. Hot testing results confirmed a saturated output power of 3 MW with an efficiency of 53.1 % and a gain of 47.5 dB. Compared with the commercial klystron, the proposed M-klystron reduced cavities chain length from 3.5 m to 1.9 m, leading to volume reduction of nearly 50 %. These results highlight M-klystron's potential for compact, efficient RF sources in accelerator facilities as well as broader industrial and medical applications.
{"title":"Development and experiment of metamaterial loaded compact 324 MHz/3 MW klystron power system for CSNS proton linac","authors":"Hexin Wang , Huachang Liu , Zhencheng Mu , Hui Zhang , Linyan Rong , Zhexin Xie , Maliang Wan , Bo Wang , Bilawal Ali , Kai Guo , Xuanming Zhang , Shaozhe Wang , Yongming Li , Zhaoyun Duan , Yubin Gong","doi":"10.1016/j.nima.2026.171313","DOIUrl":"10.1016/j.nima.2026.171313","url":null,"abstract":"<div><div>This paper reports the development and experimental validation of a compact metamaterial-loaded 324 MHz/3 MW klystron power system designed for the China Spallation Neutron Source (CSNS) proton linear accelerator. Conventional P-band klystrons deployed at CSNS, suffer from large physical dimensions and heavy weight, imposing constraints on system integration and cost. To address these limitations, a novel metamaterial-loaded klystron (M-klystron) incorporating complementary electric split-ring resonators (CeSRRs) and a second harmonic cavity is proposed, fabricated, and hot-tested. Particle-in-cell (PIC) simulations demonstrated that the M-klystron could achieve an output power of 2.97 MW at 324 MHz. The power system is driven by a self-developed long-pulse solid-state modulator, capable of delivering stable −110 kV, 51.5 A pulses at 25 Hz with a flat-top width of 950 μs, alongside a low-level RF (LLRF) control system ensuring precise amplitude and phase stabilization. Hot testing results confirmed a saturated output power of 3 MW with an efficiency of 53.1 % and a gain of 47.5 dB. Compared with the commercial klystron, the proposed M-klystron reduced cavities chain length from 3.5 m to 1.9 m, leading to volume reduction of nearly 50 %. These results highlight M-klystron's potential for compact, efficient RF sources in accelerator facilities as well as broader industrial and medical applications.</div></div>","PeriodicalId":19359,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment","volume":"1085 ","pages":"Article 171313"},"PeriodicalIF":1.4,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146078181","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 : 2026-05-01Epub Date: 2026-01-22DOI: 10.1016/j.nima.2026.171299
F.G. Mo , Q. Tang , C. Guo , C.G. Yang , JUNO Collaboration
The Jiangmen Underground Neutrino Observatory (JUNO) is the state-of-the-art neutrino physics experiment located in South China. With 20 ktons of ultra-pure Liquid Scintillator, JUNO aims to achieve groundbreaking measurements, including the determination of the Neutrino Mass Ordering and a precise measurement of three neutrino oscillation parameters with sub-percent precision. The central detector is immersed in a Water Cherenkov Detector (WCD), which contains 40 ktons of ultrapure water and 2400 microchannel plate photomultipliers, serving dual purposes of radioactive background suppression from surrounding rock and cosmic muon tagging. The inner surface of the water pool’s wall is covered by 5 mm HDPE to prevent the rock emanating radon from diffusing into the water. Tyvek reflectors cover both the HDPE surface and the stainless lattice steel structure to enhance the light collection efficiency. A 100 t/h ultra-pure water system, which could reduce radon to mBq/m level and radium to Bq/m level, maintains high water quality and ensures optimal detector performance. A magnetic shielding system effectively mitigates geomagnetic field effects on PMT operation. The WCD demonstrates exceptional cosmic muon detection efficiency, exceeding 99% while suppressing muon-induced fast neutron backgrounds to 0.1 events per day. This paper will provide an overview of the design and current status of JUNO’s Water Cherenkov detector.
{"title":"JUNO’s Water Cherenkov Detector","authors":"F.G. Mo , Q. Tang , C. Guo , C.G. Yang , JUNO Collaboration","doi":"10.1016/j.nima.2026.171299","DOIUrl":"10.1016/j.nima.2026.171299","url":null,"abstract":"<div><div>The Jiangmen Underground Neutrino Observatory (JUNO) is the state-of-the-art neutrino physics experiment located in South China. With 20 ktons of ultra-pure Liquid Scintillator, JUNO aims to achieve groundbreaking measurements, including the determination of the Neutrino Mass Ordering and a precise measurement of three neutrino oscillation parameters with sub-percent precision. The central detector is immersed in a Water Cherenkov Detector (WCD), which contains 40 ktons of ultrapure water and 2400 microchannel plate photomultipliers, serving dual purposes of radioactive background suppression from surrounding rock and cosmic muon tagging. The inner surface of the water pool’s wall is covered by 5 mm HDPE to prevent the rock emanating radon from diffusing into the water. Tyvek reflectors cover both the HDPE surface and the stainless lattice steel structure to enhance the light collection efficiency. A 100 t/h ultra-pure water system, which could reduce radon to mBq/m<span><math><msup><mrow></mrow><mrow><mn>3</mn></mrow></msup></math></span> level and radium to <span><math><mi>μ</mi></math></span>Bq/m<span><math><msup><mrow></mrow><mrow><mn>3</mn></mrow></msup></math></span> level, maintains high water quality and ensures optimal detector performance. A magnetic shielding system effectively mitigates geomagnetic field effects on PMT operation. The WCD demonstrates exceptional cosmic muon detection efficiency, exceeding 99% while suppressing muon-induced fast neutron backgrounds to <span><math><mo>∼</mo></math></span>0.1 events per day. This paper will provide an overview of the design and current status of JUNO’s Water Cherenkov detector.</div></div>","PeriodicalId":19359,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment","volume":"1085 ","pages":"Article 171299"},"PeriodicalIF":1.4,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146078189","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 : 2026-05-01Epub Date: 2026-01-01DOI: 10.1016/j.nima.2025.171274
Xingcan Li , Hua Cai , Shubin Chen , Kun Ge , Zhehao Hua , Hao He , Jifeng Han , Peng Hu , Jinsheng Jia , Weichang Li , Sen Qian , Wang Qiao , Xusheng Qiao , Jing Ren , Xinyuan Sun , Zexuan Sui , Gao Tang , Jingping Tang , Dong Yang , Huiping Yuan , Jinlong Zhu
A novel Hadron Calorimeter (HCAL) design scheme utilizing glass scintillators to replace plastic scintillators in the analog read-out option has been proposed. To satisfy the performance indicators of Glass Scintillator Hadron Calorimeter (GSHCAL), batch testing and screening of the properties of glass scintillators are imperative. Large-size glass scintillators were batch-fabricated via the melt-quenching method, and their properties were rapidly tested and analyzed using a PMT-based test system. Over 50 % of the samples comply with the specified performance indicators. The light output (LO) of the glasses is effectively sustained above 1000 ph/MeV, while the decay time is controlled below 500 ns. This study provides an effective approach for the batch testing of large-size glass scintillators and contributes significantly to the development of GSHCAL.
{"title":"Batch testing results of GFO glass scintillators for GSHCAL","authors":"Xingcan Li , Hua Cai , Shubin Chen , Kun Ge , Zhehao Hua , Hao He , Jifeng Han , Peng Hu , Jinsheng Jia , Weichang Li , Sen Qian , Wang Qiao , Xusheng Qiao , Jing Ren , Xinyuan Sun , Zexuan Sui , Gao Tang , Jingping Tang , Dong Yang , Huiping Yuan , Jinlong Zhu","doi":"10.1016/j.nima.2025.171274","DOIUrl":"10.1016/j.nima.2025.171274","url":null,"abstract":"<div><div>A novel Hadron Calorimeter (HCAL) design scheme utilizing glass scintillators to replace plastic scintillators in the analog read-out option has been proposed. To satisfy the performance indicators of Glass Scintillator Hadron Calorimeter (GSHCAL), batch testing and screening of the properties of glass scintillators are imperative. Large-size glass scintillators were batch-fabricated via the melt-quenching method, and their properties were rapidly tested and analyzed using a PMT-based test system. Over 50 % of the samples comply with the specified performance indicators. The light output (LO) of the glasses is effectively sustained above 1000 ph/MeV, while the decay time is controlled below 500 ns. This study provides an effective approach for the batch testing of large-size glass scintillators and contributes significantly to the development of GSHCAL.</div></div>","PeriodicalId":19359,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment","volume":"1085 ","pages":"Article 171274"},"PeriodicalIF":1.4,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145929143","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}
Over the past several decades, external-beam radiotherapy has advanced significantly owing to sophisticated treatment-planning techniques and image-guided delivery. Nevertheless, the dose actually delivered to patients can deviate from that prescribed because of treatment-planning inaccuracies, delivery errors, and setup uncertainties. Consequently, in vivo dosimetry, a quality assurance technique that directly measures the dose delivered to patients, has been recommended internationally. In this study, we evaluated the response of a small spherical diode dosimeter (SSDD) to X-rays as a novel alternative to conventional in vivo dosimeters. The sensitive volume consists of a 1.2-mm-diameter spherical silicon junction, comprising a p-type core surrounded by an n-type layer on all sides except the bottom, forming a spherical p–n junction. Aluminum (n-side, top) and silver (p-side, bottom) electrodes are aligned along the central axis of the sphere. The SSDD (diameter = 1.7 mm) is sufficiently small for body insertion and enables real-time delivered dose measurements via the collected ionization charge. Radiation-induced response degradation was found to be linear and could be readily corrected through pre- and post-irradiation calibration. The percent depth dose (PDD) measured using the SSDD closely matched that obtained with a Farmer-type ionization chamber, reproducing the reference PDD within 2.5 % at all depths except at the nominal surface. Angular dependence evaluation revealed alternating regions of higher and lower sensitivity at steps of ∼90° for all dosimeters. Although an angular dependence was observed, its magnitude was small (≤3 %). These findings indicate that the SSDD is a suitable in vivo dosimeter for therapeutic X-ray beams.
{"title":"Fundamental X-ray characterization of a small spherical diode dosimeter for in-vivo dosimetry","authors":"Masaya Watanabe , Ren Abukawa , Shinnosuke Matsumoto","doi":"10.1016/j.nima.2025.171272","DOIUrl":"10.1016/j.nima.2025.171272","url":null,"abstract":"<div><div>Over the past several decades, external-beam radiotherapy has advanced significantly owing to sophisticated treatment-planning techniques and image-guided delivery. Nevertheless, the dose actually delivered to patients can deviate from that prescribed because of treatment-planning inaccuracies, delivery errors, and setup uncertainties. Consequently, in vivo dosimetry, a quality assurance technique that directly measures the dose delivered to patients, has been recommended internationally. In this study, we evaluated the response of a small spherical diode dosimeter (SSDD) to X-rays as a novel alternative to conventional in vivo dosimeters. The sensitive volume consists of a 1.2-mm-diameter spherical silicon junction, comprising a p-type core surrounded by an n-type layer on all sides except the bottom, forming a spherical p–n junction. Aluminum (n-side, top) and silver (p-side, bottom) electrodes are aligned along the central axis of the sphere. The SSDD (diameter = 1.7 mm) is sufficiently small for body insertion and enables real-time delivered dose measurements via the collected ionization charge. Radiation-induced response degradation was found to be linear and could be readily corrected through pre- and post-irradiation calibration. The percent depth dose (PDD) measured using the SSDD closely matched that obtained with a Farmer-type ionization chamber, reproducing the reference PDD within 2.5 % at all depths except at the nominal surface. Angular dependence evaluation revealed alternating regions of higher and lower sensitivity at steps of ∼90° for all dosimeters. Although an angular dependence was observed, its magnitude was small (≤3 %). These findings indicate that the SSDD is a suitable in vivo dosimeter for therapeutic X-ray beams.</div></div>","PeriodicalId":19359,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment","volume":"1085 ","pages":"Article 171272"},"PeriodicalIF":1.4,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145929144","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}
Measurements have been made of the decay heat generated within the new-style tantalum-clad ten-plate tungsten target for the First Target Station (TS-1) of the ISIS Spallation Neutron Source. The new-style target incorporates less tantalum than the old-style target, and the decay heat is correspondingly less. Measured values of decay heat agree well with values obtained from Monte Carlo calculations.
{"title":"Measurement of decay heat in ISIS new-style TS-1 target","authors":"D.J.S. Findlay, G.P. Škoro, J.P. Chapman, J.D. Moor, S.D. Gallimore","doi":"10.1016/j.nima.2025.171263","DOIUrl":"10.1016/j.nima.2025.171263","url":null,"abstract":"<div><div>Measurements have been made of the decay heat generated within the new-style tantalum-clad ten-plate tungsten target for the First Target Station (TS-1) of the ISIS Spallation Neutron Source. The new-style target incorporates less tantalum than the old-style target, and the decay heat is correspondingly less. Measured values of decay heat agree well with values obtained from Monte Carlo calculations.</div></div>","PeriodicalId":19359,"journal":{"name":"Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment","volume":"1085 ","pages":"Article 171263"},"PeriodicalIF":1.4,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145929218","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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