Tue·Mar 14, 2023Tuesday·March 14, 2023

1. 01*

   Measurement of electrons from open heavy-flavor hadron decays in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV with the STAR detector

   STAR Collaboration: M. I. Abdulhamid · B. E. Aboona · J. Adam · L. Adamczyk · J. R. Adams · I. Aggarwal · M. M. Aggarwal · Z. Ahammed · D. M. Anderson · E. C. Aschenauer · S. Aslam · J. Atchison and 362 other authors

   We report a new measurement of the production of electrons from open heavy-flavor hadron decays (HFEs) at mid-rapidity ($|y|<$ 0.7) in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV. Invariant yields of HFEs are measured for the transverse momentum range of $3.5<p_{\mathrm{T}}<9$ GeV/$c$ in various configurations of the collision geometry. The HFE yields in head-on Au+Au collisions are suppressed by approximately a factor of 2 compared to that in $p$+$p$ collisions scaled by the average number of binary collisions, indicating strong interactions between heavy quarks and the hot and dense medium created in heavy-ion collisions. Comparison of these results with models provides additional tests of theoretical calculations of heavy quark energy loss in the quark-gluon plasma.

   nucl-exJHEP(2023)·8 citations
2. 02*

   A Complete Approach to Determine the ${}^3$He neutron incoherent scattering length $b_i$

   H. Lu🇺🇸 · O. Holderer🇩🇪 · A. Ioffe🇩🇪 · S. Pasini🇩🇪 · P. Pistel🇩🇪 · Z. Salhi🇩🇪 · B. M. Goodson🇺🇸 · W. M. Snow🇺🇸 · E. Babcock🇩🇪

   We report the first results from a new approach for measuring the ${}^3$He neutron incoherent scattering length $b_i$. $b_i$ is directly proportional to the difference $\Delta b=b_{+}-b_{-}$ in the two low-energy s-wave neutron-nucleus scattering amplitudes $b_{+}$ and $b_{-}$, corresponding to the singlet $J=0$ and triplet $J=1$ states of the neutron-${}^3$He interaction, respectively. An accurate measurement of $b_i$ can help distinguish among different models of three-nucleon interactions by comparison to {\it ab initio} nuclear theory calculations. The neutron birefringence caused by $\Delta b$ results in neutron spin rotation around the nuclear polarization. We measured $\Delta b$ using polarized neutron spin rotation and the transmission of neutrons through a ${}^3$He gas target polarized in situ by spin-exchange optical pumping. This brief test measurement, conducted at the FZ-Jülich neutron spin echo spectrometer at the Heinz Maier Leibnitz Zentrum (MLZ), yielded $\Delta b=[-5.27\pm 0.05$ (stat.) $-0.05$ (syst.)] fm. We argue that this method can be improved in precision to resolve the discrepancies between two prior measurements of $b_i$ which are dependent on the polarized absorption cross section ${\sigma }_p$. Further with absolute ${}^3$He polarization via NMR (in a properly-shaped cell) concurrent with accurate neutron transmission measurements, ${\sigma }_p$ can be measured to obtain independent values of $b_{+}$ and $b_{-}$.

   nucl-exphysics.atom-phPRC(2023)·1 citation
3. 03*

   Constraining the Astrophysical p Process: Cross Section Measurement of the 84Kr(p,g)85Rb Reaction in Inverse Kinematics

   Alicia Palmisano-Kyle · Artemis Spyrou · Paul DeYoung · Panagiotis Gastis · Orlando Olivas-Gomez · Caley Harris · Sean Liddick · Stephanie Lyons · Jorge Pereira · Andrea Richard · Anna Simon · Mallory Smith · Artemis Tsantiri · Remco Zegers

   One of the biggest questions in nuclear astrophysics is understanding where the elements come from and how they are made. This work focuses on the p process, a nucleosynthesis process that consists of a series of photodisintegration reactions responsible for producing stable isotopes on the proton-rich side of stability. These nuclei, known as the p nuclei, cannot be made through the well-known neutron-capture processes. Currently p-process models rely heavily on theory to provide the relevant reaction rates to predict the final p-nuclei abundances and more experimental data is needed. The present work reports on an experiment performed with the SuN detector at the National Superconducting Cyclotron Laboratory, NSCL, at Michigan State University using the ReA facility to measure the ${}^{84}$Kr(p,$\gamma$)${}^{85}$Rb reaction cross section in inverse kinematics. The reverse ${}^{85}$Rb($\gamma$,p)${}^{84}$Kr reaction is a branching point in the p-process reaction network that was highlighted as an important reaction in sensitivity studies in the production of the ${}^{78}$Kr p nucleus. A new hydrogen gas target was designed and fabricated and a new analysis technique for background subtraction and efficiency calculations of the detector were developed. The experimental cross section is compared to standard statistical model calculations using the NON-SMOKER and TALYS codes.

   nucl-exPRC(2022)·11 citations
4. 04*

   High energy nuclear physics meets Machine Learning

   Wan-Bing He🇨🇳 · Yu-Gang Ma🇨🇳 · Long-Gang Pang🇨🇳 · Huichao Song🇨🇳 · Kai Zhou🇩🇪

   Though being seemingly disparate and with relatively new intersection, high energy nuclear physics and machine learning have already begun to merge and yield interesting results during the last few years. It's worthy to raise the profile of utilizing this novel mindset from machine learning in high energy nuclear physics, to help more interested readers see the breadth of activities around this intersection. The aim of this mini-review is to introduce to the community the current status and report an overview of applying machine learning for high energy nuclear physics, to present from different aspects and examples how scientific questions involved in high energy nuclear physics can be tackled using machine learning.

   ↳ hep-phhep-exnucl-exnucl-thNucl.Sci.Tech.(2023)·105 citations
5. 05*

   Improvement of Geant4 Neutron-HP package: Doppler broadening of the neutron elastic scattering kernel and cross sections

   M. Zmeškal🇨🇿 · L. Thulliez🇫🇷 · E. Dumonteil🇫🇷

   Whether it is for shielding applications or for safety criticality studies, numerically solving the neutron transport equation with a good accuracy requires to precisely estimate the Doppler broadened elastic scattering kernel in the thermal and epithermal energy range of neutrons travelling in a free gas. In Geant4, low energy neutrons are transported using evaluated data libraries handled by the Neutron High-Precision (Neutron-HP) package. Version 11.00.p03 of the code features in particular the Doppler broadened elastic scattering kernel, provided by the so-called 'Sampling of the Velocity of the Target' (SVT) method. However this latter fails for resonant heavy nuclei such as 238U and can severely impact the solving of the Boltzmann equation in fissile media. To overcome this shortcoming, the Doppler Broadened Rejection Correction (DBRC) method has been implemented in Geant4 and successfully validated with the reference Monte Carlo neutron transport code Tripoli4 (version 11). This development will be taken into account in the next release of the code. The cross section Doppler broadening process, which is performed on-the-fly, is also carefully investigated and ways to improve it on a simulation-by-simulation basis are presented. All the validations have been performed with an automated benchmark tool which has been designed to support the quality assurance of the Geant4 Neutron-HP package. This tool is currently available on an ad hoc Gitlab repository and will be included in Geant4.

   ↳ physics.comp-phnucl-ex2 citations
6. 06*

   Active target TPC for study of photonuclear reactions at astrophysical energies

   M. Kuich🇵🇱 · M. Ćwiok · W. Dominik🇵🇱 · A. Fijałkowska🇵🇱 · M. Fila🇵🇱 · A. Giska🇵🇱 · Z. Janas🇵🇱 · A. Kalinowski🇵🇱 · K. Kierzkowski · C. Mazzocchi🇷🇴 · W. Okliński · M. Zaremba and 17 other authors

   A setup designed to study photonuclear reactions at astrophysical energies - an active target Time Projection Chamber was developed and constructed at the Faculty of Physics, University of Warsaw. The device was successfully employed in two experiments at the Institute of Nuclear Physics Polish Academy of Sciences in Cracow, in which {\gamma}- and neutron-induced reactions with CO2 gas target were measured. The reaction products were detected and their momenta reconstructed. Preliminary results are shown.

   ↳ physics.ins-detnucl-exActa Phys.Polon.Supp.(2023)·0 citations
7. 07*

   Development of a thorium coating on an aluminium substrate by using electrodeposition method and alpha spectroscopy

   Dal-Ho Moon · Vivek Chavan · Vasant Bhoraskar · Yeong Hoon Jeong · Jung Ho Park · Su-Jeong Suh · Seung-Woo Hong🇺🇸

   A thin coating of thorium on aluminium substrates with the areal density of 110 to 130 $\mu g/c{m}^2$ is developed over a circular area of 22 mm diameter by using the electrodeposition method. An electrodeposition system is fabricated to consist of three components; an anode made of a platinum mesh, a cylindrical-shape vessel to contain the thorium solution, and a cathode in the form of a circular aluminium plate. The aluminium plate is mounted horizontally, and the platinum mesh is connected to an axial rod of an electric motor, mounted vertically and normal to the plane of the aluminium. The electrolyte solution is prepared by dissolving a known-weight thorium nitrate powder in 0.8 M HNO3 and isopropanol. The system is operated either in constant voltage (CV) or constant current (CC) mode. Under the electric field between the anode and cathode, thorium ions were deposited on the aluminium substrate mounted on the cathode. In the CV mode at 320, 360, and 400 V and in the CC mode at 15 mA, thorium films were formed over a circular area of the aluminium substrate. The areal density of thorium coating was measured by detecting emitted alpha particles. The areal density of thorium varied from 80 to 130 $\mu g/c{m}^2$ by changing the deposition time from 10 to 60 min. The results from the CV mode and CC mode are compared, and the radial dependence in the measured areal density is discussed for different modes of the electric field. The developed thorium coatings are to be used in the in-house development of particle detectors, fast neutron converters, targets for thorium fission experiments, and other purposes.

   ↳ physics.ins-detnucl-exJ.Korean Phys.Soc.(2023)·0 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.