China

Yuhao Qin

Qinglin Niu

Dong Guo

Sheng Xiao

Baiting Tian

Yijie Wang

Zhi Qin

Xinyue Diao

Fenhai Guan

Dawei Si

Boyuan Zhang

Yaopeng Zhang

Xianglun Wei

Herun Yang

Peng Ma

Haichuan Zou

Tianli Qiu

Xinjie Huang

Rongjiang Hu

Limin Duan

Hooi Jin Ong

Yanyun Yang

Shiwei Xu

Kang Wang

Zhen Bai

Junbing Ma

Fangfang Duan

Guo Yang

Qiang Hu

Hongwei Wang

Baohua Sun

Hungary

Ukraine

Sergei P. Maydanyuk

Chang Xu

Zhigang Xiao

Erratum to “Probing high-momentum component in nucleon momentum distribution by neutron-proton bremsstrahlung <italic>&#947;</italic>-rays in heavy ion reactions&#8221; [Phys. Lett. B 850 (2024) 138514]

The high momentum tail (HMT) of nucleons, as a signature of the short-range correlations in nuclei, has been investigated by the high-energy bremsstrahlung γ rays produced in $^{86}$Kr+$^{124}$Sn at 25 MeV/nucleon. The energetic photons are measured by a CsI(Tl) hodoscope mounted on the spectrometer CSHINE. The energy spectrum ≥35 MeV can be reproduced by the Isospin- and Momentum-Dependent Boltzmann-Uehling-Uhlenbeck model calculations incorporating the photon production channel from np process in which the HMTs of nucleons is considered. A non-zero HMT ratio of about 15% is favored by the data. The effect of the capture channel <math><mi>n</mi><mi>p</mi><mo>→</mo><mi>d</mi><mi>γ</mi></math> is demonstrated.

Probing high-momentum component in nucleon momentum distribution by neutron-proton bremsstrahlung -rays in Heavy ion Reactions

The charge exchange (CE) reaction is an effective probe to study the structure of atomic nuclei in the isospin dimension, which has been studied for decades. To expand the range of nuclei studied by CE reactions to a wider range and research the structure characteristics of unstable nuclei, including the isospin symmetry, spin-isospin excitation, and nuclear symmetry energy, a semi-cylindrical time projection chamber (scTPC) prototype was designed and constructed to probe ( $$^{\textrm{3}}$$  <math> <msup> <mrow></mrow> <mtext>3</mtext> </msup> </math>  He,t) CE reactions in inverse kinematics. The 266 nm UV laser was used to achieve electron-drift-velocity calibration. The scTPC has an energy resolution (FWHM) of 5.6% for  $$\alpha $$  <math> <mi>α</mi> </math>   particles emitted by  $$^{\textrm{241}}$$  <math> <msup> <mrow></mrow> <mtext>241</mtext> </msup> </math>  Am radioactive source. The position resolution of scTPC is described by the residual method. The spatial resolution on the pad plane is 409  $$\upmu $$  <math> <mi>μ</mi> </math>  m. And the position resolution in the drift direction is 326  $$\upmu $$  <math> <mi>μ</mi> </math>  m, equivalent to an angular resolution of 0.4 $$^\circ $$  <math> <msup> <mrow></mrow> <mo>∘</mo> </msup> </math>  . These performances suggest that the scTPC can measure  $$\Delta E $$  <math> <mrow> <mi>Δ</mi> <mi>E</mi> </mrow> </math>  and particle tracks precisely. The successful development of the scTPC prototype provides better conditions for the next step of experimental data analysis and processing.

Zhixuan He

Meng Li

Wenjuan Bu

Chaoyuan Xiao

Yuansheng Yang

Shanhaowei He

Chengui Lu

Bitao Hu

Yi Zhang

Development of a semi-cylindrical time projection chamber prototype for ( $$^{3}{\textrm{He}},t$$  <math> <mrow> <msup> <mrow></mrow> <mn>3</mn> </msup> <mtext>He</mtext> <mo>,</mo> <mi>t</mi> </mrow> </math>  ) charge exchange reaction experiment

A new trapezoid-shaped Frisch-grid ionization chamber (TFG-IC) has been built as a part of a  $$\varDelta {E}-E$$  <math> <mrow> <mi>Δ</mi> <mi>E</mi> <mo>-</mo> <mi>E</mi> </mrow> </math>   telescope system for the detection and identification of charged particles at energies down to a few MeV. To study the effect of the drift electric field uniformity, two types of sealed windows, namely a pair of SSA (split-strip aluminized mylar film) and a pair of DSA (double-sided aluminized mylar film) sealed windows have been investigated. The detector’s performances were studied using a standard  $$^{241}$$  <math> <msup> <mrow></mrow> <mn>241</mn> </msup> </math>  Am source at different gas pressures, and the total energy-deposit resolution achieved is about 1.1%(FWHM). The  $$\varDelta {E}-E$$  <math> <mrow> <mi>Δ</mi> <mi>E</mi> <mo>-</mo> <mi>E</mi> </mrow> </math>   telescope, which was composed of TFG-IC and a DSSSD (double-sided silicon strip detector), has been tested using a three-component  $$\alpha $$  <math> <mi>α</mi> </math>   source and the  $$^{241}$$  <math> <msup> <mrow></mrow> <mn>241</mn> </msup> </math>  Am source under laboratory conditions. The results show that the energy resolution with the SSA sealed windows which provide uniform drift electric field has a smaller fluctuation than that with the DSA ones; the fluctuations are about 1% and 4% for the former and the latter, respectively. Simulations using the COMSOL software also confirmed the electric-field distortion at the edge of the detector with the DSA windows. A correlation curve between energy resolution and energy deposit of charged particles at various gas pressures and for two gas species is derived for TFG-IC with the SSA sealed windows using the measurement with the  $$^{241}$$  <math> <msup> <mrow></mrow> <mn>241</mn> </msup> </math>  Am source. Incorporating the above results, we performed Monte Carlo simulations to evaluate the particle-identification capability of the telescope. The results show that the telescope can be extended to the identification of low-energy particles.

Xiaohua Yuan

Junwei Zhang

Yuxuan Yang

Zhoubo He

Xiaohao Yin

Zhijie Li

Japan

Hooi Ong

New trapezoid-shaped Frisch-grid ionization chamber for low-energy particle measurements

The intensity interferometry is applied as a chronometer of the particle emission of hydrogen isotopes from the intermediate velocity source formed in $^{40}$Ar+$^{197}$Au reactions at 30 MeV/u. The dynamic emission order of <math><msub><mrow><mi>τ</mi></mrow><mrow><mi>p</mi></mrow></msub><mo>&gt;</mo><msub><mrow><mi>τ</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>&gt;</mo><msub><mrow><mi>τ</mi></mrow><mrow><mi>t</mi></mrow></msub></math> is evidenced via the correlation functions of nonidentical particle pairs. Assuming the similar source size, the same emission order is inferred from the correlation functions of identical particle pairs, where <math><msub><mrow><mi>τ</mi></mrow><mrow><mi>p</mi></mrow></msub><mo>≈</mo><mn>100</mn><mspace width="0.25em"></mspace><mtext>fm</mtext><mo>/</mo><mtext>c</mtext></math> is extracted by the fit of Koonin-Pratt equation to p-p correlation function. Transport model simulations demonstrate that the dynamic emission order of light charged particles depends on the stiffness of the nuclear symmetry energy.

Qianghua Wu

Yan Huang

Liming Lyu

Zhihao Gao

Genming Jin

Shuya Jin

Jiansong Wang

Peng Wang

Yufeng Wang

Gongming Yu

Yuechao Yu

Yapeng Zhang

Qingwu Zhou

Yaofeng Zhang

Chunwang Ma

Xinrong Hu

Yunyi Cui

Junlong Tian

The emission order of hydrogen isotopes via correlation functions in 30 MeV/u Ar+Au reactions

A new Frisch-grid ionization chamber has been built to explore the appropriate choice of Frisch-grid. Detailed studies of the relationship between grid geometries and detector performance have been performed with an  $$^{241}$$  <math> <msup> <mrow></mrow> <mn>241</mn> </msup> </math>  Am source. This paper describes and compares the energy resolution of ionization chambers with parallel-wire and mesh grids of different grid parameters. Some specific recommendations for grid selection are provided based on the data currently available. To obtain optimal energy resolution, the operating voltage of the chamber must satisfy the condition of minimum electron collection on the grid with distinct geometries and parameters, respectively. Since there is no established theory applicable to both types of grids, we have devised a careful simulation procedure incorporating the COMSOL and Garfield++ codes to search for the conditions of the minimum electron collection on the grid. The simulation results fit the experimental data well, suggesting that this simulation method successfully predicts the suitable voltage setting when using a mesh grid or parallel wires grid as the shielding electrode.

Yongde Fang

Yikai Hou

Exploration of grid scheme for Frisch-grid ionization chamber

We consider right-handed neutrino dark matter N1 in local U(1)LÎ¼âLÏ -extended Ma model. With the light U(1)Î¼âÏ gauge boson ( mZâ²â¼O(100)Â MeV ) and small U(1)Î¼âÏ gauge coupling ( gZâ²â¼10â4â10â3 ) which can accommodate the muon (gâ2) anomaly and is still allowed by other experimental constraints, we show that we can get correct relic density of dark matter for wide range of dark matter mass ( M1â¼10â200Â GeV ), although the gauge coupling constant gZâ² is small. This is due to the fact that the annihilation cross section of dark matter pair is enhanced by M14/mZâ²4 in the processes N1N1âZâ²Zâ² or N1N1âZâ²H2 . We also consider the constraints from direct detection, collider searches.

South Korea

Seungwon Baek

Dark matter and muon ( g − 2) in local U(1)Lμ−Lτ -extended Ma model