Inverse-kinematics charge-exchange experiments with radioactive ion beams require compact detector systems with good particle identification capability and high energy resolution for recoil charged particles emitted at large angles. In a recently developed TPC-CsI(Tl) Delta E-E telescope for the inverse-kinematics (He-3, t) reaction, the performance of long CsI(Tl) scintillator bars is limited by light collection non-uniformity (LCNU) caused by scintillation-photon attenuation. In this work, a dual-end readout scheme for CsI(Tl) bars is proposed and investigated. Geant4-based Monte Carlo simulations are performed to study photon transport and collection in single-end and dual-end readout configurations, showing that the LCNU is reduced from 18.19% to 4.30% with improved light-collection efficiency. Experimental tests using cosmic ray muons further confirm the effectiveness of the dual-end readout, achieving LCNU below 6% for most crystals. These results demonstrate that dual-end readout provides a practical and effective solution to mitigate intrinsic non-uniformity in long CsI(Tl) bars and significantly improve the energy resolution and overall performance of CsI(Tl)-based detector systems.

PURPOSE:The aim of this work was to develop an online dose monitoring device that can be applied to both conventional radiation therapy (RT) and ultrahigh dose rate RT. METHODS AND MATERIALS:Thick Gas Electron Multiplier (THGEM) technology, with its uniform microstructure characteristics, emerges as an ideal solution to these challenges. This study introduces an innovative approach by covering both THGEM electrodes with Mylar conductive films, creating independent microionization chambers in each microhole that effectively reduce charge density issues in high dose rate environments. RESULTS:Experimental results demonstrate that the developed THGEM-based air ionization chamber (THGEM-ADIC) exhibits nearly identical linear response to the standard PTW Farmer 30013 ionization chamber over a dose range of 1-100 Gy in conventional RT settings, with dose deviations within ±3% and a stable operational plateau of approximately 400 V. Accuracy at clinical single-field doses typical of intensity modulated RT or fractionated treatments remains to be investigated. More importantly, benefiting from its unique microstructure design, THGEM-ADIC has rapid signal response, enabling direct measurement of FLASH radiation therapy accelerator macro-pulse structures. In ultrahigh dose rate (UHDR) working environments, the detector maintains an operational plateau of about 200 V and demonstrates a dose response with linearity exceeding 99% compared with EBT3 film dosimetry measurements, even at extreme dose rates up to 250 Gy/s. However, a dose rate dependence was observed between 50 and 250 Gy/s under UHDR conditions, which should be taken into account for accurate dosimetry at UHDRs. CONCLUSIONS:Collectively, these results indicate that THGEM-ADIC, with its microstructure design and rapid response capabilities, not only provides measurement accuracy consistent with traditional ionization chambers in conventional RT but also enables precise dose monitoring under UHDR FLASH radiation therapy conditions, offering an important dosimetric tool for the clinical translation of FLASH-RT technology.

Short-range correlation (SRC) in nuclei refers to nucleons forming temporally correlated pairs in close proximity, giving rise to the high momentum of the nucleons beyond the Fermi surface. It has been reported that bremsstrahlung gamma production from the neutron-proton process in heavy-ion reactions provides a potential probe to the SRC abundance in nuclei. In this paper, we present in detail the precision measurement of bremsstrahlung gamma rays in 124Sn + 124Sn reactions at 25 MeV/nucleon using the Compact Spectrometer for Heavy IoN Experiment (CSHINE). A comprehensive experimental and analysis framework is established to ensure the reliability and robustness of the extracted results. Background contributions are evaluated and subtracted using independent methods, and the consistency of the analysis is systematically validated. By comparing the experimental gamma spectrum with isospin-dependent Boltzmann-Uehling-Uhlenbeck simulations, the high momentum tail (HMT) fraction of RHMT = (20 +/- 3)% is derived in 124Sn nuclei. This work provides a detailed and validated experimental framework for extracting SRC information from bremsstrahlung gamma-ray emission and demonstrates the feasibility of studying nucleon SRCs with high precision in low-energy heavy-ion collisions.

The High-Rigidity Radioactive Ion Beam Line (HIRIBL) is a projectile fragmentation-type secondary beam facility that works at relativistic energies. As an important part of the High-Intensity Heavy-Ion Accelerator Facility (HIAF), it is known for its high beam intensity, high energy, and ability to produce complex particles. The beamline uses a TOF-rho-Delta E method to identify secondary beam particles. This process presents major challenges for the dynamic range, counting rate, and long-term stability of the particle identification detectors. To solve these problems, a new Micro-Pin Array Detector (MIPA) has been developed. This detector works over a large dynamic range, from the ionization region to the proportional region. In a gas mixture of Ar and CH4 (10%, known as P10), the MIPA achieved a gain of 4 & times; 104 and operated stably for fifteen days. When set up as a parallel-plate ionization chamber, the MIPA showed energy resolutions of 4.19% for 239Pu, 3.57% for 241Am, and 3.07% for Cm-244, using a triple-alpha source. These results prove that the MIPA Detector has a large dynamic range and very good stability, making it suitable for advanced nuclear detection applications.

Purpose Cosmic ray muons, characterized by their high energy and penetrative capabilities, provide significant advantages for non-destructive imaging applications, including security inspection, geological exploration, and archaeology. As the muon tomography continues to advance, there is growing demand for precise and efficient muon imaging algorithms. This study aims to enhance muon track reconstruction accuracy, improve the quality of muon scattering imaging, and increase track utilization quality. Methods This paper proposes a neural network-based method utilizing Multi-Wire Drift Chambers (MWDCs), to improve muon track reconstruction performance. Additionally, to address the limitations of the conventional Point-of-Closest Approach (PoCA) algorithm in imaging accuracy and track utilization efficiency, an improved PoCA-based imaging method is proposed and its imaging performance is evaluated. Results The proposed neural network-based track reconstruction method achieved a spatial resolution 351 μ m . Furthermore, the improved PoCA algorithm significantly improved imaging resolution and reconstruction performance, while enhancing muon track utilization efficiency. Conslusions The MWDC-based neural network track reconstruction method improves muon track reconstruction performance, while the improved PoCA algorithm enhances imaging quality and track utilization efficiency. The combination of these methods provides an effective solution for muon scattering tomography

A new multi-detector array named HALIMA (Hybrid Array for LIfetime MeAsurement) has been developed at Lanzhou for nuclear structure studies in fission. The array comprises eight BGO-shielded High-Purity Germanium detectors and twenty fast Ce-doped Lanthanum Bromide [LaBr _3 (Ce)] detectors shielded with CsI(Tl). HALIMA is further complemented by two ancillary detector systems: fission fragment (FF) detectors and β detectors. This configuration enables precise sub-nanosecond lifetime measurements using the fourfold FF/ β -Ge-LaBr _3 (Ce)-LaBr _3 (Ce) coincidence technique. The performance and specifications of the detectors, associated electronics, and the data acquisition system are presented in detail. The advantage of FF selectivity is emphasized, which significantly enhances sensitivity to specific fission channels. Using this approach, the lifetimes of the nuclear excited states populated in the spontaneous fission of ^252 Cf were measured, showing good agreement with the established literature values.

Chirality lies at the heart of low-energy QCD, governing the symmetry structure that shapes hadron masses and strong interaction dynamics. Among the most compelling open questions tied to chiral dynamics and spontaneous chiral symmetry breaking is the longstanding Λ polarization puzzle, in which Λ hyperons produced in unpolarized hadronic collisions exhibit a surprisingly large transverse polarization that remains theoretically unexplained. This whitepaper presents the proposal for the Hyperon-Nucleon Spectrometer (H-NS) at the High-Intensity heavy-ion Accelerator Facility (HIAF). Leveraging the high energy and high intensity of HIAF's proton and heavy-ion beams, the H-NS experiment will perform systematic studies of hyperon polarization phenomena and their underlying mechanisms in proton-proton (pp), proton-nucleus (pA), and nucleus-nucleus (AA) collisions in the fixed target mode. A wide-range beam energy scan, including proton beams from 3 GeV up to 9.3 GeV (HIAF) and up to 32 GeV (upgraded HIAF), will be conducted to examine the dependence of polarization on collision energy. The spectrometer is designed with specialized detectors capable of high-precision reconstruction of final-state baryon polarizations. Among its many interesting and important measurements, H-NS will simultaneously measure hyperon and proton spin observables to explore the polarization mechanism in hadronic interactions and the spin structure of baryons. Furthermore, the use of pA and AA collisions will enable detailed investigations of cold and hot nuclear matter effects on spin polarization. Its physics program and detector development will significantly benefit the future Electron-ion Collider in China.

This study presents a comprehensive application and validation of a multi-software coupling workflow for the research and development of gaseous detector systems. The integrated workflow includes particle interaction (Geant4/Garfield++), electrostatic field computation (COMSOL), electronic response (LTspice), and digital signal processing (ROOT). Applied to a Frisch-grid ionization chamber (FGIC) developed for the High-Intensity heavy-ion Accelerator Facility (HIAF), the integrated system simulates the entire response chain, including geometric structure modeling, particle source definition and interactions, electric field distribution calculations, electron-ion transport, electronic circuit response, and digital shaping algorithms. The key advantage of this systematically integrated approach lies in its ability to perform waveform-level simulation and validation. As demonstrated by the FGIC case study, the simulated waveforms show a correlation coefficient of 0.9 with measurements, and the energy spectra exhibit a peak position deviation of < 0.5%, confirming the high-fidelity physical simulation of gaseous detectors. This methodology provides a tool for optimizing the design of the FGIC and interpreting its experimental data, with general applicability to other gaseous detector development efforts.

Abstract This study reports on the design, simulation, construction, and testing of a full-size prototype of the multi-wire drift chamber for the CSR external-target experiment. The multi-wire drift chamber array incorporates drift cells of three different sizes: 8 $$\times $$ × 8 mm $$^{\textrm{2}}$$ 2 , 10 $$\times $$ × 10 mm $$^{\textrm{2}}$$ 2 , and 15 $$\times $$ × 15 mm $$^{\textrm{2}}$$ 2 . Simulation studies were carried out to compare their electron drift time spectra, R-T relations, and position resolution. The prototype was constructed based on the design of the multi-wire drift chamber closest to the target. Since the beam passes through the center region of the multi-wire drift chamber, the prototype features a special beam avoidance design. The design ensures that the detector is sensitive to reaction products while remaining unresponsive to heavy ion beams. The size of the prototype is 930 $$\times $$ × 1660 mm $$^{\textrm{2}}$$ 2 , comprising 960 drift cells. Testing was conducted with dedicated electronics. An energy resolution of 22% was achieved for the $$^{\textrm{55}}$$ 55 Fe source; the track residuals were approximately 300 $$\upmu $$ μ m for the cosmic rays; the detection efficiency of each layer exceeds 96% for the cosmic rays.

For heavy ion radiotherapy of tumors, a persistent worldwide challenge is the inability to accurately measure the actual depth of ion beams and to assess the precision of irradiation during treatment. Positron-emitters radionuclides such as [Formula: see text]C, [Formula: see text]C and [Formula: see text]O, generated during the treatment process, are deposited along the beam trajectory, enabling Positron Emission Tomography (PET) imaging and the monitoring of the dose distribution primary beam. Although the distribution of positron-emitters activity can be reconstructed by a PET system, establishing a correlation between this activity and the dose is a prerequisite for employing the system to assess carbon ion beam dose distribution. In this study, a dual flat-panel In-beam PET scanner was developed to investigate the relationship between the spatial activity distribution of positron products and the spatial dose distribution of carbon ions. Experiments revealed that along the Y-axis perpendicular to the beam direction, the positron activity peak shows a itional deviation of less than 0.5[Formula: see text]mm, allowing direct beam positioning. In the beam direction, however, while the two are correlated, they do not directly coincide under the same beam energy; a millimeter-level discrepancy exists between the positron activity peak and the dose peak, and this deviation increases with higher beam energy. Based on these findings, the study proposes that a dose monitoring model using positron activity distribution as input and incorporating machine learning methods can be established, paving a new pathway for in vivo range verification and precise dose control in carbon ion therapy.

Heavy-ion collisions(HICs)is a unique experimental tool for investigating the properties of nuclear matter under extreme conditions in the laboratory.At HIRFL-CSR energies,HICs can create nuclear matter with 2-3 times the saturation density(ρ0).The HIRFL-CSR external-target experiment(CEE)is a large-acceptance spectrometer designed to explore frontier top-ics in high-energy nuclear physics,such as the QCD phase structure and nuclear matter equation of states.In this letter,we introduce simulation and analysis software for the CEE experiment(CeeROOT).Based on the CEE conceptual design and CeeROOT software,the configurations of its subdetectors were optimized by considering foreseeable physical constraints.The final detector layout of the CEE spectrometer and its acceptances were validated through simulations of U+U collisions at 500 MeV/u and pp collisions at 2.8 GeV,which demonstrated that the CEE experiment will serve as a detector with wide acceptance and multi-particle identification capabilities for studying high-energy nuclear physics topics at HIRFL-CSR energies with pp,pA,and AA collisions.

The cross section for the J(pi) (T) = 3( +)(0) state was measured to be enhanced in an isolated "Li nucleus compared to the same reduced state in a "Li cluster. This difference demonstrates a nuclear medium modification of the tensor force, which is sensitively probed by the T = 0 channel. In contrast, the J(pi) (T) = 0 (+) (1) state (T=1) was found to have approximately equal excitation strength in both Li-6 systems. We interpret this tensor force modification as a consequence of density saturation within a many-body interaction framework.

Experimental and theoretical investigation of the fragmentation reaction in the Fermi-energy domain is currently of particular importance for not only nuclear physics but also some interdisciplinary fields.In the present study,neutron-rich 14C and 16C ion beams at 27.5 MeV/nucleon were used to bombard carbon and polyethylene(CD2)n targets.Energy and angular distributions of the produced fragments were measured.Background events ori-ginating from the carbon content in(CD2)n target were efficiently excluded using an extended E-P plot method.Ex-perimental results are systematically analyzed using the HIPSE-SIMON dynamic model.The comparison reveals that,for the carbon target,the HIPSE-SIMON calculation overestimates the yields of the beam-velocity component for fragments near the projectile and also the energy phase space for fragments far away from the projectile,suggest-ing that fine tuning of the overall interaction profile adopted in the model is required.In contrast,for reactions with the deuteron target,the model calculation can reasonably reproduce the experimental data.The implication of the fragmentation mechanism on the validity of the invariant mass method,as frequently used to reconstruct the cluster-ing resonant structures in light nuclei,is also discussed.

The semicylindrical time projection chamber (scTPC) is designed to measure the angular distribution of the cross section for intermediate-energy (3He,t) charge-exchange reactions in inverse kinematics. The scTPC prototype comprises a cathode, field cage, drift region, amplification structure based on a multilayer thick gas electron multiplier (THGEM), and a readout plane with 886 zigzag-shaped pads. The gain uniformity of the THGEM and the drift velocity of electrons were calibrated. Track recognition based on the Hough transform was then developed to reconstruct cosmic ray tracks and determine their position resolution. The position resolution of secondary particle tracks resulting from collisions between the heavy-ion beam and the 3He target was measured, yielding an x-resolution of 0.71 mm and a z-resolution of 0.73 mm. The scTPC demonstrates sufficient energy and spatial resolution to support charge-exchange reaction experiments in inverse kinematics.

The neutron-neutron (nn) correlation function has been measured in 25  MeV/u ^{124}Sn+^{124}Sn reactions. Using the Lednický-Lyuboshitz approach, the nn scattering length and effective range (f_{0}^{nn}, d_{0}^{nn}), as well as the reduced space-time size R^{(0)} of the neutron emission source are simultaneously extracted as (18.9_{-1.2}^{+1.3}  fm, 1.9_{-1.0}^{+1.3}  fm) and 4.12±0.12  fm, respectively. The measured nn scattering length is consistent with the results obtained in the low-energy scattering ^{2}H(π^{-},γ)2n, indicating heavy-ion collisions can serve as an effective approach for measuring nn interactions and further investigating the charge symmetry breaking of nuclear force. The space-time size extracted from momentum-gated correlation functions exhibits clear dependence on the pair momentum, with R^{(0)}=2.8±0.1  fm and 4.9±0.2  fm being determined for the high and low momentum neutrons, respectively.

The Time Projection Chamber (TPC) serves as the central detector of the Cooling Storage Ring External-target Experiment (CEE) spectrometer, designed to precisely measure dE/dx, momentum information, and charged particle trajectories of large-angle reaction products in nuclear experiments conducted at the Heavy Ion Research Facility in Lanzhou (HIRFL). To achieve accurate tracking of charged particles in the large-angle region and enable particle identification in conjunction with other detectors, real-time monitoring and control of the detector system are essential. For this purpose, a Slow Control System (SCS) was developed and implemented using the Experimental Physics and Industrial Control System (EPICS) software toolkit. This system monitors and controls the TPC's operational parameters, including gas flow, laser system performance, front-end electronics, and environmental conditions, while also overseeing auxiliary devices in real time. Such comprehensive monitoring ensures high-precision position and time measurements with the detector. This paper presents the design, components, commissioning, operation, and performance evaluation of the TPC SCS.

A half-size prototype of the multi wire drift chamber for the cooling storage ring external-target experiment (CEE) was assembled and tested in the 350 MeV/u Kr + Fe reactions at the heavy-ion research facility in Lanzhou. The prototype consists of six sense layers, where the sense wires are stretched in three directions X, U, and V; meeting 0^∘ , 30^∘ , and -30^∘ , respectively, with respect to the vertical axis. The sensitive area of the prototype is 76 cm× 76 cm . The amplified and shaped signals from the anode wires were digitized in a serial capacity array. When operating at a high voltage of 1500 V on the anode wires, the efficiency for each layer is greater than 95 301 ± 2 μm . This performance satisfies the requirements of CEE.

The emission of neutrons from heavy ion reactions is an important observable for studying the asymmetric nuclear equation of state and the reaction dynamics. A 20-unit neutron array has been developed and mounted on the compact spectrometer for heavy ion experiments (CSHINE) to measure the neutron spectra, neutron- neutron and neutron-proton correlation functions. Each unit consists of a 15 x 15 x 15 cm3 plastic scintillator coupled to a cent = 52 mm photomultiplier. The Geant4 simulation with optical process is performed to investigate the time resolution and the neutron detection efficiency. The inherent time resolution of 212 ps is obtained by cosmic ray coincidence test. The n-y discrimination and time-of-flight performance are given by 252 Cf radioactive source test and beam test. The neutron energy spectra have been obtained in the angular range 30 degrees <= B lab <= 51 degrees in the beam experiment of 124 Sn + 124 Sn at 25 MeV/u with CSHINE.

The prompt fission neutron spectrum(PFNS)is a key nuclear data quantity that is of particular interest and plays a crucial role in understanding and modeling fission processes.An array comprising 48 liquid scintillation detectors and a parallel-plate avalanche counter(PPAC)was developed at the China Institute of Atomic Energy(CIAE)to measure the PFNS of actinide nuclei.Efficiency and energy calibrations were performed for all the liquid scintillators,and their efficiencies were consistently found to be better than 5％.The time resolutions of the PPAC and liquid scintillators were measured to be 1.08 ns and 1.16 ns using 252Cf and 207Bi sources,respectively.The pulse shape discrimination of the liquid scintillator was utilized to identify neutron and γ signals on an event-by-event basis,and the figure of merit was deduced as 1.12 at a 200 keVee threshold.The contribution to the PFNS from multiple scattered neutrons was evaluated via Geant4 simulations,and those originating from the environment were found to be comparable to the crosstalk between the detectors.The neutron efficiency of the entire detection array was calibrated using a 252Cf spontaneous fission source and was demonstrated to be consistent with the Geant4 simulation results,which verified the reliability of the detection array.