The photoneutron cross sections of ^175 Lu were measured in the energy range of 7.90−13.89 MeV using a quasi-monochromatic, energy-tunable gamma-ray beam produced by the Shanghai Laser Electron Gamma Source (SLEGS) at the Shanghai Synchrotron Radiation Facility (SSRF). Neutron counts were detected by a newly developed neutron flat-efficiency detector (FED) array, and the γ -ray spectrum distribution from the SLEGS was precisely determined using a BGO detector with a 100 ^175 Lu( γ , n) data were obtained with an uncertainty of less than 5 γ SF) values of ^175 Lu above the neutron threshold were extracted using the experimentally measured ^175 Lu( γ , n) data. Furthermore, an innovative Bayesian optimization framework was introduced to constrain the γ SF model parameters in the TALYS code, and the optimized γ SF model was then applied calculate the neutron capture cross section and Maxwell-averaged cross section of ^174 Lu.

The photodisintegration cross sections of the deuteron have been systematically measured over the photon energy range of 2.33-19.65 MeV at the Shanghai Laser Electron Gamma Source. By applying the well-established Baldin sum rule to the newly obtained data, the sum of the electric and magnetic dipole polarizabilities of the deuteron is extracted for the first time based solely on a dense and continuous experimental dataset, yielding α_{E}+β_{M}=0.719±0.009_{stat}±0.014_{algo}±0.023_{syst}  fm^{3}. With theoretical values of the magnetic polarizability β_{M} calculated from the pionless effective field theory, a new value of the electric polarizability is obtained as α_{E}=0.637±0.009_{stat}±0.014_{algo}±0.023_{syst}±0.004_{theo}  fm^{3}, which is in excellent agreement with current theoretical predictions. This result resolves the previous discrepancy between experimental measurements from elastic scattering and theory, providing a high-precision benchmark for nuclear interaction models.

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 photoneutron cross sections for the $^{209}$Bi$(\gamma,n)^{208}$Bi reaction have been measured using quasi-monoenergetic $\gamma$-ray beams from 7.5 to 25.0 MeV at the Shanghai Laser Electron Gamma Source (SLEGS). As a heavy magic nucleus with $N=126$, $^{209}$Bi serves as a critical benchmark for the collective excitation modes of spherical nuclei. Our measurement aims to provide a definitive resolution to the long-standing 20\% discrepancy between the experimental results from the Lawrence Livermore National Laboratory (LLNL) and Saclay. A high-efficiency flat-efficiency neutron detector (FED) was employed to minimize systematic uncertainties related to neutron energy dependence. The extracted giant dipole resonance (GDR) parameters were analyzed within the framework of the TALYS statistical model code. The results demonstrate that our data are consistent with the Saclay trend and IAEA evaluations, suggesting an underestimation in the earlier LLNL data. These findings provide essential constraints for the $\gamma$-ray strength functions ($\gamma$SF) and contribute to a more accurate understanding of the $p$-process nucleosynthesis and lead-bismuth eutectic coolant systems in nuclear reactors.

Gamma activation analysis (GAA) is a powerful elemental analysis technique, particularly suitable for light elements and those insensitive to thermal neutron activation. The establishment of the Shanghai Laser Electron Gamma Source (SLEGS) beamline has provided a unique platform in China for conducting advanced gamma activation studies using quasi-monochromatic gamma beams and obtaining high-precision nuclear data. In this paper, the gamma activation data measurement method and experimental setup developed at the SLEGS beamline are systematically presented, while demonstrating its specific applications and significant achievements in beam diagnostics and nuclear astrophysics research. This study is conducted at the SLEGS beamline. The SLEGS generates tunable quasi-monochromatic gamma beams in an energy range of 0.66-21.7 MeV through the inverse Compton scattering mode of a 3.5 GeV electron beam and a 10.64 mu m CO2 laser. The experimental procedure begins with the online irradiation of target samples such as natural abundance Au, Zn and Ru/Ga, thereby generating radioactive nuclei through photonuclear reactions. During irradiation, beam monitoring is conducted using LaBr3(Ce) or BGO detectors in conjunction with spectral unfolding. Subsequently, offline gamma-ray spectroscopy is performed on the activated samples using shielded HPGe detectors. Based on these measurements, the reaction cross-sections are ultimately determined by analyzing characteristic gamma peaks, beam parameters, and detector efficiency data. Absolute calibration of SLEGS gamma beam intensity is successfully achieved using Au-197(gamma, n)Au-196 and Zn-64(gamma, n)Zn-63 reactions. The measured results agree with online monitor data and Geant4 simulations within an uncertainty of 10%, thereby validating activation as a reliable beam diagnostic tool. Key photonuclear reaction cross-sections relevant to p-process nucleosynthesis are measured. Using natural abundance Ru targets, preliminary quasi-monoenergetic cross-section data are obtained for Ru-96(gamma, n)Ru-95, Ru-96(gamma, p)Tc-95 and Ru-98(gamma, n)Ru-97 reactions. Systematic measurements of the Ga-69(gamma, n)Ga-68 monoenergetic reaction cross-section are performed. The experimental data constrain parameters in the TALYS nuclear reaction model, enabling the calculation of Ga-69(gamma, n), (gamma, p), and (gamma, alpha) reaction rates over 1.5-10 GK temperature range. REACLIB-format parameters are derived for astrophysical network calculations. These experimental results provide crucial constraints for understanding the origin of p-nuclei. his study successfully establishes a comprehensive and reliable gamma activation data acquisition and analysis platform at the SLEGS beamline of Shanghai Synchrotron Radiation Facility. Experimental results show that this platform can not only accurately calibrate gamma beam parameters, but also conduct cutting-edge basic research in nuclear astrophysics, especially in measuring the critical yet challenging photonuclear reaction cross-sections of the p-process. The obtained datasets are crucial for nuclear databases and astrophysical models. Looking ahead, the SLEGS gamma activation platform will broaden its applications to a wider range of fields including characteristic nuclide identification, archaeometry, materials science, and medical isotope production. Low-background gamma data and partial gamma activation data are provided, which can be accessed in the dataset at https://doi.org/10.57760/sciencedb.j00213.00194. Gamma activation analysis (GAA) is a powerful elemental analysis technique, particularly suitable for light elements and those insensitive to thermal neutron activation. The establishment of the Shanghai Laser Electron Gamma Source (SLEGS) beamline has provided a unique platform in China for conducting advanced gamma activation studies using quasi-monochromatic gamma beams and obtaining high-precision nuclear data. In this paper, the gamma activation data measurement method and experimental setup developed at the SLEGS beamline are systematically presented, while demonstrating its specific applications and significant achievements in beam diagnostics and nuclear astrophysics research. This study is conducted at the SLEGS beamline. The SLEGS generates tunable quasi-monochromatic gamma beams in an energy range of 0.66-21.7 MeV through the inverse Compton scattering mode of a 3.5 GeV electron beam and a 10.64 mu m CO2 laser. The experimental procedure begins with the online irradiation of target samples such as natural abundance Au, Zn and Ru/Ga, thereby generating radioactive nuclei through photonuclear reactions. During irradiation, beam monitoring is conducted using LaBr3(Ce) or BGO detectors in conjunction with spectral unfolding. Subsequently, offline gamma-ray spectroscopy is performed on the activated samples using shielded HPGe detectors. Based on these measurements, the reaction cross-sections are ultimately determined by analyzing characteristic gamma peaks, beam parameters, and detector efficiency data. Absolute calibration of SLEGS gamma beam intensity is successfully achieved using Au-197(gamma, n)Au-196 and Zn-64(gamma, n)Zn-63 reactions. The measured results agree with online monitor data and Geant4 simulations within an uncertainty of 10%, thereby validating activation as a reliable beam diagnostic tool. Key photonuclear reaction cross-sections relevant to p-process nucleosynthesis are measured. Using natural abundance Ru targets, preliminary quasi-monoenergetic cross-section data are obtained for Ru-96(gamma, n)Ru-95, Ru-96(gamma, p)Tc-95 and Ru-98(gamma, n)Ru-97 reactions. Systematic measurements of the Ga-69(gamma, n)Ga-68 monoenergetic reaction cross-section are performed. The experimental data constrain parameters in the TALYS nuclear reaction model, enabling the calculation of Ga-69(gamma, n), (gamma, p), and (gamma, alpha) reaction rates over 1.5-10 GK temperature range. REACLIB-format parameters are derived for astrophysical network calculations. These experimental results provide crucial constraints for understanding the origin of p-nuclei. his study successfully establishes a comprehensive and reliable gamma activation data acquisition and analysis platform at the SLEGS beamline of Shanghai Synchrotron Radiation Facility. Experimental results show that this platform can not only accurately calibrate gamma beam parameters, but also conduct cutting-edge basic research in nuclear astrophysics, especially in measuring the critical yet challenging photonuclear reaction cross-sections of the p-process. The obtained datasets are crucial for nuclear databases and astrophysical models. Looking ahead, the SLEGS gamma activation platform will broaden its applications to a wider range of fields including characteristic nuclide identification, archaeometry, materials science, and medical isotope production. Low-background gamma data and partial gamma activation data are provided, which can be accessed in the dataset at https://doi.org/10.57760/sciencedb.j00213.00194.

A 3-inch x 4-inch LaBr3 detector was employed to characterize the energy distributions of quasi-monoenergetic gamma-rays generated at the Shanghai Laser Electron Gamma Source (SLEGS), part of the Shanghai Synchrotron Radiation Facility. Systematic calibration of the detector's response was conducted at the China Institute of Atomic Energy using monoenergetic gamma-rays from (p, gamma) nuclear reactions on LiF, Al-27 and C-13 targets. Energy spectrum unfolding was performed through an iterative matrix inversion algorithm, employing the detector's monoenergetic response functions as kernel elements in the linear equation system. This approach facilitated direct reconstruction of gamma-ray energy spectra from raw detector signals. Validation experiments comparing LaBr3 and BGO spectral reconstructions under identical conditions demonstrate strong agreement between both detection systems for gamma-ray spectra with FWHM > 6 %. The methodology successfully characterized gamma-ray beam energy profiles resulting from slant-scattering processes at SLEGS, demonstrating robust performance in complex analysis.

The Giant Dipole Resonance (GDR) in 51V has been a long-term conflicting interpretation, with existing photoneutron cross section data suggesting either a single peak or a pronounced splitting, leading to opposite conclusions on nuclear deformation. A new measurement of the 51V(γ,1n) cross section, performed at the Shanghai Laser Electron Gamma Source (SLEGS) facility, employs a refined monochromatic cross section extraction method. By integrating Polynomial Regression and Support Vector Regression (SVR) for robust interpolation and extrapolation, the new extracted monoenergetic cross sections exhibit a single, broad peak with no evidence of GDR splitting. Re-analysis of the reported splitting shows that any deformation extracted from such a structure would be relatively weaker than those of neighboring nuclei, providing a support for a spherical or near-spherical shape of 51V. Furthermore, we found that deliberately overfitting the data using an SVR model reproduces multi-peak structures similar to those reported in historical datasets, implying that the previously claimed splitting might originated from analysis artifacts rather than physical phenomena.

Above the neutron separation energy, photon absorption is dominated by the Giant Dipole Resonance (GDR), which is the dominant mechanism for incident y-rays energies typically exceeding 10 MeV. This absorption leads to highly excited compound nuclei that decay predominantly through neutron emission, resulting in the formation of daughter nuclei. Subsequent de-excitation of these daughters via y-rays cascades to lowlying states offers valuable insights into nuclear structure. The SLEGS Time-Of-Flight (TOF) spectrometer which consists of twenty neutron liquid Scintillators (EJ301), covering a total solid angle of 0.1126 sr-approximately 0.9% of the full 4t sphere and eight LaBr3(Ce) y-rays detectors, covering a total solid angle of 0.4054 sr-approximately 3.2% of the full 4t sphere, has been constructed and tested in both offline and online experiments. The experimental result shows that the total absolute y-rays detection efficiency is 1.15%@1332 keV with an efficiency stability 5.8%, the total absolute neutron detection efficiency is 0.31%@2.13MeV with an efficiency stability 1.3%. The energy resolution for neutrons is approximately 8.5%@4 MeV. To evaluate the performance of the setup and validate the data analysis procedures, an online coincidence measurement of the reaction 181Ta(y, y ' n)180Ta was performed using approximately 13 MeV quasi-monochromatic y rays from the SLEGS beamline. The measurement revealed features consistent with a high level density and the presence of multiple rotational bands in 180Ta, while also verifying the stable operation of the spectrometer.

Ag-109 is located on the pathway of the slow neutron capture process, and 79% of Ag-109 is generated through a rapid neutron capture process. Meanwhile, the mass fraction of Ag-109 in Ag-In-Cd control rods is 38.56%. Therefore, the neutron capture cross-section of Ag-109 is crucial for both nuclear energy and nuclear astrophysics applications. In this work, a neutron capture cross-section is measured using a Ag-109 isotope target at the Back1-500 eV energy region are obtained by combining the time-of-flight method and the pulse-height weighting technique. The Ag-109 resonance energy, neutron resonance width, and gamma resonance width parameters are extracted from this study at 139.4 eV are in agreement with the values evaluated in the JENDL-4.0, while the parameters at 169.9 eV and 328.1 eV are in agreement with the values evaluated in the JEFF-4.0. Additionally, the result at 259.3 eV is consistent with the value evaluated in the CENDL-3.2. The datasets presented in this paper are openly available at https://www.doi.org/10.57760/sciencedb.j00213.00197.

Polarized high-energy photon gamma rays are excellent probes for nuclear and particle physics research. Recently, a unique method for generating MeV energy-tunable gamma rays, the Laser Compton Slant Scattering (LCSS) mode, was implemented at the Shanghai Laser Electron Gamma Source (SLEGS). A study of the polarization properties of the LCSS gamma beam at SLEGS combined theoretical simulations with experimental measurements. The intensity of spatial distributions and Stokes parameters were systematically simulated for LCSS of linearly/circularly polarized laser photons and unpolarized relativistic electrons. The measured scattered gamma spatial distributions at three typical slant incidence angles were in agreement with the simulation for the linearly polarized laser. The results imply that the polarization degree of the incident photon is almost completely transferred to the scattered gamma rays for any incident angle, while the direction of polarization of the scattered gamma ray changes with the incident and scattering angles.

We report a new measurement of the photoneutron cross section for 89Y(gamma, n) 88Y in the energy range of 11.85-18.70 MeV at the Shanghai Laser Electron Gamma Source (SLEGS) using a neutron Flat-Efficiency Detector (FED) array. An iterative unfolding algorithm was combined to extract monoenergetic cross sections with a typical total uncertainty similar to 3.5%. Then the new experimental results are systematically compared with the data from Saclay, Livermore and IAEA/PD-2019, which implies the reliability of our results. Based on the new experimental results, the gamma-ray strength function (gamma SF) was deduced and used as input for Hauser-Feshbach calculations of the inverse reaction 88Y(n, gamma) 89Y using the TALYS code. Theoretical predictions were based on the Kopecky-Uhl generalized Lorentzian model for E1 transitions and the spin-flip scissors model for M1 transitions and optimized using a normalization factor Gnorm = 1.31. The calculated 88Y(n, gamma) 89Y cross sections are in good agreement with JEFF-3.3, but show deviations from other evaluated nuclear data libraries, including JENDL-5, TENDL-2023, and ROSFOND-2010.

The interaction of photons with relativistic electrons constitutes a fundamental electromagnetic process whose polarization-transfer mechanics remain incompletely characterized. We report the first systematic measurement of the spatial polarization distribution for [Formula: see text] rays generated via [Formula: see text] slant inverse Compton scattering (ICS) between linearly polarized [Formula: see text] photons and [Formula: see text] electrons, performing full two-dimensional mapping of the intensity, angle of polarization (AOP) and degree of polarization (DOP). The measurements reveal an asymmetric beam profile along the laser polarization direction that resembles observations from [Formula: see text] backward ICS. The central beam region exhibits DOP near 1.0, with the AOP rigidly aligned at [Formula: see text], while peripheral regions display complex, non-uniform polarization distributions. These findings confirm quantum electrodynamics predictions of near-complete polarization transfer along the beam axis in slant geometries, thereby establishing slant scattering as a viable alternative to head-on configurations for generating high-DOP [Formula: see text] rays.

High-flux, high-energy 𝛾-ray measurements are constrained by pulse pile-up and detector saturation.To address this issue, a well-type BGO scintillation detector based on a controlled low-efficiency sam-pling strategy is proposed, enabling online measurement of high-flux 𝛾-ray beams. The design reducesthe probability of full-energy absorption while maintaining a stable detector response, allowing reliableoperation at elevated flux levels. The detector performance was systematically evaluated through MonteCarlo simulations, energy calibration using (p,𝛾) reactions, and on-beam tests at SLEGS. The results showthat the detector operates stably over an energy range of 5.5–21.7 MeV at fluxes of approximately 10⁵ s⁻¹,without performance degradation. The experimental results agree well with the simulated one over theenergy range, validating the reliability of both the model and the measured data. The detector provides aneffective and scalable solution for real-time monitoring of high-flux 𝛾-ray beams.

Resolving inconsistencies among historical photonuclear cross-section measurements is essential for reliable nuclear data evaluation. Significant discrepancies exist between the Livermore and Saclay datasets for the 127I(γ, n) reaction, leading to long-standing uncertainties in evaluated databases. In this work, a Bayesian neural network (BNN) framework is applied to assess the systematic consistency of existing experimental data. The evaluation predicts that Bergère et al. (1969) measurements are mutually consistent within uncertainty, whereas both Livermore Bramblett et al. (1966) and Berman et al. (1987) measurements exhibit a systematic underestimation of the cross section, while available (γ, 2n) data remain consistent across laboratories. To independently test this prediction, new high-precision measurements of the 127I(γ, n) cross section were performed at the SLEGS beamline using quasi-monochromatic γ rays produced via inverse Compton scattering. The new data, with total uncertainties below 4

The fragment yields in photon-induced fission reactions of thorium (Th) isotopes are important for modern nuclear energy applications and for understanding the evolution of the nuclear structures of their isotopic chains. Bayesian neural network (BNN) models were constructed to describe the fragment yields in photonuclear fission reactions of thorium isotopes, ranging from ^216 Th to ^232 Th, especially those of ^232 Th, at various incident photon energies. The predicted results of the optimized BNN models were in good agreement with the measured data for these reactions. The double-layer BNN models successfully illustrated the systematic transition from asymmetric to symmetric fission in thorium isotopes, including the associated odd-even effects, energy dependence, and leftward shift in mass yield distributions. The developed BNN models provide a new tool for predicting the fragment yields in thorium photonuclear fission reactions.

High-flux, high-energy y-ray measurements are constrained by pulse pile-up and detector saturation. To address this issue, a well-type BGO scintillation detector based on a controlled low-efficiency sampling strategy is proposed, enabling online measurement of high-flux y-ray beams. The design reduces the probability of full-energy absorption while maintaining a stable detector response, allowing reliable operation at elevated flux levels. The detector performance was systematically evaluated through Monte Carlo simulations, energy calibration using (p, y) reactions, and on-beam tests at SLEGS. The results show that the detector operates stably over an energy range of 5.5-21.7 MeV at fluxes of approximately 105 s-1, without performance degradation. The experimental results agree well with the simulated one over the energy range, validating the reliability of both the model and the measured data. The detector provides an effective and scalable solution for real-time monitoring of high-flux y-ray beams.

使用激光康普顿散射产生的准单色γ射线在上海激光电子伽马源（SLEGS）测量了γ-Tm（γ，n）反应的光中子截面。使用迭代展开方法获得了8.27至14.61 MeV能量范围内的单能截面。将测量的激发函数与IAEA-2019评估、NewSUBARU数据以及TENDL-2019和TENDL-2021库进行了比较。虽然再现了横截面的总体趋势，但在共振区域仍存在明显差异。根据实验结果，提取了$^{169}$Tm的$\gamma$射线强度函数，并将其与TALYS计算结果进行了比较。使用实验约束的强度函数，进一步得到了逆$^{168}$Tm（$n，\gamma$）$^{169}$Tm反应截面计算，为核反应模型和评估的核数据库提供有用的约束。

The cross sections of 103Rh(n,γ) and 103Rh(γ,n) reactions play a crucial role in the stellar nucleosynthesis, rhodium-based self-powered neutron detectors, and nuclear medicine. The cross sections of 103Rh(n,γ) reaction was measured by the time-of-flight (TOF) method from 1 eV to 1000 keV at the Back-n facility of the Chinese Spallation Neutron Source. In the resolved resonance region, the data reported multiple new resonance structures for the first time. Several discrepancies, especially some previously spurious structures were clarified, offering valuable insights into the differences between the evaluated libraries. Maxwellian-averaged cross sections (MACSs) were calculated within the temperature range of the s process nucleosynthesis model, based on the averaged cross sections in the unresolved resonance region. Meanwhile the cross sections of 103Rh(γ,n) reaction within the range of p process nucleosynthesis were measured using laser Compton scattering (LCS) γ rays and a new neutron flat efficiency detector (FED) array at the Shanghai Laser Electron Gamma Source (SLEGS), Shanghai Synchrotron Radiation Facility (SSRF). Using an unfolding iteration method, 103Rh(γ,n) reaction data were obtained with uncertainty less than 5%, and the inconsistencies between the available experimental data and the evaluated libraries were discussed. This study provides a reliable benchmark for nuclear data evaluation and model optimization, and lays a solid foundation for Rh medical isotope applications and astrophysical research.

We report on a high-precision measurement of the D(γ,n)p photodisintegration reaction at the newly commissioned Shanghai Laser Electron Gamma Source, employing a quasimonochromatic γ-ray beam from Laser Compton Scattering. The cross sections were determined over E_{γ}=2.327-7.089  MeV, achieving up to a factor of 2.2 improvement in precision near the neutron separation threshold. Combined with previous data in a global Markov chain Monte Carlo analysis using dibaryon effective field theory, we obtained the unprecedentedly precise p(n,γ)D cross sections and thermonuclear rate, with a precision up to ≈4 times higher than previous evaluations. Implemented in a standard Big Bang nucleosynthesis framework, this new rate decreases uncertainty of the key cosmological parameter of baryon density Ω_{b}h^{2} by up to ≈16% relative to the Laboratory for Underground Nuclear Astrophysics (LUNA) result. A residual ≈1.2σ tension between Ω_{b}h^{2} constrained from primordial D/H observations and cosmic microwave background measurements persists, highlighting the need for improved dd reaction rates and offering potential hints of new physics beyond the standard model of cosmology.

A new measurement of the Cu-65(gamma, n)Cu-64 photoneutron cross section is performed using quasi-monoenergetic, tunable gamma-ray beams produced at the Shanghai Laser Electron Gamma Source (SLEGS). The energy spectrum of the SLEGS gamma-ray beams incident on the isotopically enriched Cu-65 target is monitored using a BGO detector, while the photoneutron yields are determined with a moderated He-3 detection array with high and flat efficiency. Within the energy range of MeV, the measured data have an uncertainty of %, and a pronounced giant-dipole peak is observed at MeV with a maximal cross section of mb. These photoneutron data are compared with previous experimental results and are employed to extract the gamma-ray strength function of Cu-65 above the neutron threshold. Furthermore, we calculate the radiative neutron capture cross sections and astrophysical reaction rates for Cu-64, which is a short-lived intermediate nucleus whose reaction rate controls the local abundance distribution in the weak s-process. It is found that the calculated Cu-64(n,gamma)Cu-65 data have an overall agreement with ENDF/B-VIII.0, JEFF-3.3, and TENDL-2023 evaluations, and the corresponding astrophysical reaction rates are consistent with those reported in the JINA REACLIB database.