Fri·Apr 21, 2023Friday·April 21, 2023

1. 01*

   The Jefferson Lab tritium program of nucleon and nuclear structure measurements

   John Arrington🇺🇸 · Reynier Cruz-Torres🇺🇸 · Tyler J. Hague🇺🇸 · Leiqaa Kurbany🇺🇸 · Shujie Li🇺🇸 · David Meekins🇺🇸 · Nathaly Santiesteban🇺🇸

   A series of experiments were performed in Hall A of Jefferson Lab in 2018 that used a novel tritium and helium-3 target system. These experiments took advantage of the isospin symmetry of these mirror nuclei to make precise measurements of isospin dependence in both nucleon and nuclear structure. We summarize here the design and properties of these cells, the physics measurements that have been published, and results currently under analysis from this program.

   nucl-exhep-exEPJA(2023)·10 citations
2. 02*

   Event-by-event correlations between $\Lambda$ ($\bar{\Lambda }$) hyperon global polarization and handedness with charged hadron azimuthal separation in Au+Au collisions at $\sqrt{s_{\text{NN}}}=27\text{ GeV}$ from STAR

   STAR Collaboration: M. I. Abdulhamid🇪🇬 · B. E. Aboona🇺🇸 · J. Adam🇨🇿 · J. R. Adams🇺🇸 · G. Agakishiev🇷🇺 · I. Aggarwal🇮🇳 · M. M. Aggarwal🇮🇳 · Z. Ahammed🇮🇳 · A. Aitbaev🇷🇺 · I. Alekseev🇷🇺 · D. M. Anderson🇺🇸 · A. Aparin🇷🇺 and 345 other authors

   Global polarizations ($P$) of $\Lambda$ ($\bar{\Lambda }$) hyperons have been observed in non-central heavy-ion collisions. The strong magnetic field primarily created by the spectator protons in such collisions would split the $\Lambda$ and $\bar{\Lambda }$ global polarizations ($\Delta P=P_{\Lambda }-P_{\bar{\Lambda }}<0$). Additionally, quantum chromodynamics (QCD) predicts topological charge fluctuations in vacuum, resulting in a chirality imbalance or parity violation in a local domain. This would give rise to an imbalance ($\Delta n=\frac{N_{\text{L}}-N_{\text{R}}}{⟨N_{\text{L}}+N_{\text{R}}⟩}\ne 0$) between left- and right-handed $\Lambda$ ($\bar{\Lambda }$) as well as a charge separation along the magnetic field, referred to as the chiral magnetic effect (CME). This charge separation can be characterized by the parity-even azimuthal correlator ($\Delta \gamma$) and parity-odd azimuthal harmonic observable ($\Delta a_1$). Measurements of $\Delta P$, $\Delta \gamma$, and $\Delta a_1$ have not led to definitive conclusions concerning the CME or the magnetic field, and $\Delta n$ has not been measured previously. Correlations among these observables may reveal new insights. This paper reports measurements of correlation between $\Delta n$ and $\Delta a_1$, which is sensitive to chirality fluctuations, and correlation between $\Delta P$ and $\Delta \gamma$ sensitive to magnetic field in Au+Au collisions at 27 GeV. For both measurements, no correlations have been observed beyond statistical fluctuations.

   nucl-exPRC(2023)·5 citations
3. 03*

   Direct Comparison of using a Z-Transformation instead of the traditional $Q^2$ for for Extraction of the Proton Radius from $e-p$ Scattering Data

   Tyler J. Hague (1 and 2)🇺🇸 · Douglas W. Higinbotham (3)🇺🇸 · Spencer Portuese (3 and 4) ((1) North Carolina A&T State University, (2) Lawrence Berkeley National Laboratory, (3) Thomas Jefferson National Accelerator Facility, (4) The Governor's School for Science and Technology)🇺🇸

   A discrepancy in the determination of the proton's charge radius, $r_p$, between muonic hydrogen spectroscopy versus classic atomic spectroscopy and electron scattering data has become known as the proton radius puzzle. Extractions of $r_p$ from electron scattering data require determination of the slope of the proton's charge form factor, $G_E^p$, in the limit of $Q^2\to 0$ through fitting and extrapolation. Some works have presented the $Z$-transformation fitting technique as the best choice for this type of extraction due to the true functional form of $G_E^p$ being mathematically guaranteed to exist within the parameter-space of the fit function. In this work, we test this claim by examining the mathematical bias and variances introduced by this technique as compared to the more traditional $Q^2$ fits using statistically sampled $G_E^p$ parameterizations with known input radii. Our tests conclude that the quality of the $Z$-transformation technique depends on the range of data used. In the case of new experiments, the fit function and technique should be selected in advance by generating realistic pseudodata and assessing the power of different techniques.

   nucl-exEPJA(2024)·8 citations
4. 04*

   Direct Determination of Fission-Barrier Heights Using Light-Ion Transfer in Inverse Kinematics

   S. A. Bennett🇬🇧 · K. Garett🇬🇧 · D. K. Sharp🇬🇧 · S. J. Freeman🇬🇧 · A. G. Smith🇬🇧 · T. J. Wright🇬🇧 · B. P. Kay🇺🇸 · T. L. Tang🇺🇸 · I. A. Tolstukhin🇺🇸 · Y. Ayyad🇪🇸 · J. Chen🇺🇸 · P. J. Davies🇬🇧 and 7 other authors

   We demonstrate a new technique for obtaining fission data for nuclei away from $\beta$-stability. These types of data are pertinent to the astrophysical \textit{r-}process, crucial to a complete understanding of the origin of the heavy elements, and for developing a predictive model of fission. These data are also important considerations for terrestrial applications related to power generation and safeguarding. Experimentally, such data are scarce due to the difficulties in producing the actinide targets of interest. The solenoidal-spectrometer technique, commonly used to study nucleon-transfer reactions in inverse kinematics, has been applied to the case of transfer-induced fission as a means to deduce the fission-barrier height, among other variables. The fission-barrier height of ${}^{239}$U has been determined via the ${}^{238}$U($d$,$pf$) reaction in inverse kinematics, the results of which are consistent with existing neutron-induced fission data indicating the validity of the technique.

   nucl-exPRL(2023)·8 citations
5. 05*

   Heavy Gas Cherenkov Construction for Hall C at Thomas Jefferson National Accelerator Facility

   W.B. Li🇨🇦

   The Thomas Jefferson National Accelerator Facility (JLab) has undertaken the 12 GeV Upgrade to double the accelerating energy of its electron beam. This attracts many interesting proposals to probe the quark-gluon nature of nuclear matter at higher energy, therefore a new set of equipment is required. Experimental Hall C of JLab has planned to construct a new Super High Momentum Spectrometer (SHMS) to replace the existing Short Orbit Spectrometer (SOS). The University of Regina is assigned to construct the Heavy Gas Čerenkov (HGC) Detector as part of the SHMS focal plane detectors. This detector will be used as critical component to provide reliable pion/Kaon separation between 3-11 GeV/c central momenta in the SHMS experimental program. In this thesis, we will report the design, quality control studies and simulated expected performances of the HGC detector.

   ↳ physics.ins-detnucl-ex2 citations
6. 06*

   Improving nuclear data evaluations with predictive reaction theory and indirect measurements

   Jutta Escher🇺🇸 · Kirana Bergstrom🇺🇸 · Emanuel Chimanski🇺🇸 · Oliver Gorton🇺🇸 · Eun Jin In🇺🇸 · Michael Kruse🇺🇸 · Sophie Péru🇫🇷 · Cole Pruitt🇺🇸 · Rida Rahman🇺🇸 · Emily Shinkle🇺🇸 · Aaina Thapa🇺🇸 · Walid Younes🇺🇸

   Nuclear reaction data required for astrophysics and applications is incomplete, as not all nuclear reactions can be measured or reliably predicted. Neutron-induced reactions involving unstable targets are particularly challenging, but often critical for simulations. In response to this need, indirect approaches, such as the surrogate reaction method, have been developed. Nuclear theory is key to extract reliable cross sections from such indirect measurements. We describe ongoing efforts to expand the theoretical capabilities that enable surrogate reaction measurements. We focus on microscopic predictions for charged-particle inelastic scattering, uncertainty-quantified optical nucleon-nucleus models, and neural-network enhanced parameter inference.

   ↳ nucl-thnucl-exEPJ Web Conf.(2023)·2 citations
7. 07*

   Probing the nucleon effective mass splitting with the light particle emission

   Fang-Yuan Wang · Jun-Ping Yang · Xiang Chen🇨🇳 · Ying Cui🇨🇳 · Yong-Jia Wang🇨🇳 · Zhi-Gang Xiao🇨🇳 · Zhu-Xia Li🇨🇳 · Ying-Xun Zhang🇨🇳

   In this work, we first analyze the correlations among different nuclear matter parameters which are obtained by the 119 effective Skyrme interaction sets. The values of the correlation coefficients illustrate that the magnitude of the effective mass splitting is crucial for the tight constraints of the symmetry energy via HICs. Thus, the main object of this work is to investigate the impacts of the effective mass splitting on the heavy ion collisions observables. The ${}^{86}$Kr+${}^{208}$Pb system at the beam energy ranging from 25A MeV to 200A MeV are simulated within the framework of the improved quantum molecular dynamics model (ImQMD-Sky) for this goal. Our calculations show that the slopes of the spectra of $\ln$[Y(n)/Y(p)] and $\ln$[Y(t)/Y(${}^3$He)], which are the logarithms of the neutron to proton yield ratios and triton to Helium-3 yield ratios, are directly related to the effective mass splitting and can be used to probe the effective mass splitting.

   ↳ nucl-thnucl-exNucl.Sci.Tech.(2023)·15 citations
8. 08*

   Study of S, Cl and Ar isotopes with $N\ge Z$ using microscopic effective $sd$-shell interactions

   Priyanka Choudhary🇮🇳 · Praveen C. Srivastava🇮🇳

   In the present work, newly developed microscopic effective $sd$-valence shell interactions such as chiral next-to-next-to-next-to-leading order (N3LO), $J$-matrix inverse scattering potential (JISP16), Daejeon16 (DJ16), and monopole-modified DJ16 (DJ16A) are employed to study the nuclear structural properties of sulphur, chlorine, and argon isotopes with $N\ge Z$. These interactions are derived using the \textit{ab initio} no-core shell-model and the OLS unitary transformation method. We calculate energy spectra and electromagnetic properties to test the predictive strength of the effective interactions for these heavier $sd$-shell nuclei. For a complete systematic study, we compare the microscopic results with the phenomenological USDB results and experimental data. By looking at the excitation energies of these nuclei, the DJ16A interaction is found to be {the} most suitable for these $sd$-shell nuclei among all microscopic interactions. The electric quadrupole transition strength and excitation energy of the first $2^{+}$ state data of even-even sulphur isotopes indicate the presence of the $N=20$ shell closure. Quadrupole moment predictions are also made using these interactions where experimental data are unknown. Magnetic moments are in excellent agreement with the experimental values. The root-mean-square deviations are also calculated to provide an idea of how accurate the interactions are.

   ↳ nucl-thnucl-exEPJA(2023)·6 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.