Thu·Oct 27, 2022Thursday·October 27, 2022

1. 01*

   Neutral-current neutrino cross section and expected supernova signals for ${}^{40}$Ar from a three-fold increase in the magnetic dipole strength

   W. Tornow🇺🇸 · A. P. Tonchev🇺🇸 · S. W. Finch🇺🇸 · Krishichayan🇺🇸 · X. B. Wang🇨🇳 · A. C. Hayes🇺🇸 · H. G. D. Yeomans🇺🇸 · D. A. Newmark🇺🇸

   In view of the great interest in liquid argon neutrino detectors, the ${}^{40}$Ar($\gamma ,{\gamma }^{\prime }$)${}^{40}$Ar${}^{\ast }$ reaction was revisited to guide a calculation of the neutral current neutrino cross section at supernova energies. Using the nuclear resonance fluorescence technique with a monoenergetic, 99% linearly polarized photon beam, we report a three-fold increase in magnetic dipole strength at around 10 MeV in ${}^{40}$Ar. Based on shell-model calculations, and using the experimentally identified transitions, the neutral current neutrino cross sections for low-energy reactions on ${}^{40}$Ar are calculated.

   nucl-exhep-exPLB(2022)·16 citations
2. 02*

   Understanding the cosmic abundance of ${}^{22}$Na: lifetime measurements in ${}^{23}$Mg

   C. Fougères (GANIL, ANL) · F. de Oliveira Santos (GANIL) · N. A. Smirnova (LP2IB) · C. Michelagnoli (GANIL, ILL) · GANIL-E710/AGATA collaborations

   Simulations of explosive nucleosynthesis in novae predict the production of ${}^{22}$Na, a key astronomical observable to constrain nova models. Its gamma-ray line at 1.275 MeV has not yet been observed by the gamma-ray space telescopes. The ${}^{20}$Ne/${}^{22}$Ne ratio in presolar grains, a possible tool to identify nova grains, also depends on ${}^{22}$Na produced. Uncertainties on its yield in classical novae currently originate from the rate of the ${}^{22}$Na(p, $\gamma$)${}^{23}$Mg reaction. At peak novae temperatures, this reaction is dominated by a resonance at E${}_{\text{R}}$=0.204 MeV, corresponding to the $E_x$=7.785 MeV excited state in ${}^{23}$Mg. The resonance strengths measured so far disagree by one order of magnitude. An experiment has been performed at GANIL to measure the lifetime and the proton branching ratio of this key state, with a femtosecond resolution for the former. The reactions populating states in ${}^{23}$Mg have been studied with a high resolution detection set-up, i.e. the particle VAMOS, SPIDER and gamma tracking AGATA spectrometers, allowing the measurements of lifetimes and proton branchings. We present here a comparison between experimental results and shell-model calculations, that allowed us to assign the spin and parity of the key state. Rather small values obtained for reduced $M1$ matrix elements, $|M(M1)|\lesssim 0.5$ ${\mu }_N$, and proton spectroscopic factors, $C^2{S}_{\text{p}}$<10${}^{-2}$, seem to be beyond the accuracy of the shell model. With the reevaluated ${}^{22}$Na(p, $\gamma$)${}^{23}$Mg rate, the ${}^{22}$Na detectability limit and its observation frequency from novae are found promising for the future space telescopes.

   nucl-exastro-ph.HEastro-ph.SRnucl-thEPJ Web Conf.(2023)·1 citation
3. 03*

   Numerical study of the twist-3 asymmetry $A_{LT}$ in single-inclusive electron-nucleon and proton-proton collisions

   Brandon Bauer🇺🇸 · Daniel Pitonyak🇺🇸 · Cody Shay🇺🇸

   We provide the first rigorous numerical analysis of the longitudinal-transverse double-spin asymmetry $A_{LT}$ in electron-nucleon and proton-proton collisions for the case where only a single pion, jet, or photon is detected in the final state. Given recent extractions of certain, previously unknown, non-perturbative functions, we are able to compute contributions from all terms relevant for $A_{LT}$ and make realistic predictions for the observable at Jefferson Lab (JLab) 12 GeV, COMPASS, the future Electron-Ion Collider, and the Relativistic Heavy Ion Collider. We also compare our results to a JLab 6 GeV measurement, which are the only data available for this type of reaction. The twist-3 nature of $A_{LT}$ makes it a potentially fruitful avenue to probe quark-gluon-quark correlations in hadrons as well as provide insights into dynamical quark mass generation in QCD.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2023)·7 citations
4. 04*

   Bayesian Estimation of the $S$ Factor and Thermonuclear Reaction Rate for ${}^{16}$O(p,$\gamma$)${}^{17}$F

   Christian Iliadis🇺🇸 · Vimal Palanivelrajan · Rafael S. de Souza🇺🇸

   The ${}^{16}$O(p,$\gamma$)${}^{17}$F reaction is the slowest hydrogen-burning process in the CNO mass region. Its thermonuclear rate sensitively impacts predictions of oxygen isotopic ratios in a number of astrophysical sites, including AGB stars. The reaction has been measured several times at low bombarding energies using a variety of techniques. The most recent evaluated experimental rates have a reported uncertainty of about 7.5\% below $1$~GK. However, the previous rate estimate represents a best guess only and was not based on rigorous statistical methods. We apply a Bayesian model to fit all reliable ${}^{16}$O(p,$\gamma$)${}^{17}$F cross section data, and take into account independent contributions of statistical and systematic uncertainties. The nuclear reaction model employed is a single-particle potential model involving a Woods-Saxon potential for generating the radial bound state wave function. The model has three physical parameters, the radius and diffuseness of the Woods-Saxon potential, and the asymptotic normalization coefficients (ANCs) of the final bound state in ${}^{17}$F. We find that performing the Bayesian $S$ factor fit using ANCs as scaling parameters has a distinct advantage over adopting spectroscopic factors instead. Based on these results, we present the first statistically rigorous estimation of experimental ${}^{16}$O(p,$\gamma$)${}^{17}$F reaction rates, with uncertainties ($\pm 4.2$\%) of about half the previously reported values.

   ↳ nucl-thastro-ph.SRnucl-exPRC(2022)·10 citations
5. 05*

   Monte Carlo simulation method of polarization effects in Laser Compton Scattering on relativistic electrons

   Dan Filipescu (1) ((1) Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH))

   Quasi-monochromatic, high energy and highly polarized $\gamma$-ray beam sources based on Compton scattering of laser photons (LCS) on relativistic electrons have developed for the last few decades as established instruments for nuclear physics studies. Following an extensive photoneutron experimental campaign at the LCS $\gamma$-ray beam line of the NewSUBARU synchrotron radiation facility at SPring8, Japan, a dedicated simulation code was developed for characterizing the incident $\gamma$-ray beams. The eliLaBr code is implemented using Geant4 and is available on the GitHub repository, at https://github.com/dan-mihai-filipescu/eliLaBr . The present work describes step-by-step the Monte Carlo algorithm with focus on modeling the polarization properties of the scattered photon. The polarization is treated independently both in the Stokes parameters and in the polarization vector formalisms. An intervalidation between the two methods is given. Based on polarization state description requirements of different Geant4 physics classes, user recommendations are given on which of the two methods to be employed. The spatial and energy distributions for the LCS $\gamma$-ray beam and its Stokes parameters are obtained for head-on laser - relativistic electron collisions, where several incident laser polarization states were considered: linear, unpolarized, circular and mixed linear and circular polarization. The influence of variable incident angle between photon and electron beam was also investigated. We show that the degree of polarization transfer from the incident photon to the scattered photon increases with the collision angle. However, we show that, for $\gamma$-ray sources based on Compton scattering of laser photons on relativistic electrons, the polarization degree of the incident photon is almost completely transferred to the scattered photon for any incident angle.

   ↳ physics.ins-detnucl-exJINST(2022)·13 citations
6. 06*

   Deciphering the phases of QCD matter with fluctuations and correlations of conserved charges

   Anar Rustamov🇩🇪

   A review is given on recent experimental and theoretical/phenomenological developments regarding the phase structure of the strongly interacting matter. Specifically, evolution with the collision energy of net-proton number fluctuations as measured by several experiments are presented and their implications for the QCD phase diagram are outlined. In addition, theoretical calculations on correlations between conserved charges are presented and prospects for their experimental explorations are addressed.

   ↳ hep-phnucl-exEPJ Web Conf.(2023)·14 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.