Wed·Dec 20, 2023Wednesday·December 20, 2023

1. 01*

   Extracting the speed of sound in the strongly interacting matter created in relativistic nuclear collisions with the CMS experiment

   Cesar A. Bernardes🇧🇷

   A hot and dense matter exhibiting collective flow behavior with almost no viscous dissipation has been discovered in ultrarelativistic nuclear collisions. To constrain the fundamental degrees of freedom and equation of state of this matter, these proceedings present an extraction of its speed of sound using head-on lead-lead collision data collected by the CMS experiment at a center-of-mass energy per nucleon pair of 5.02 TeV. The measurement is based on an analysis of the observed charged multiplicity dependence of the average particle transverse momentum in ultra-central events (impact parameter of nearly zero), a variable which probes the system temperature as a function of entropy density at a fixed volume. Results are compared with hydrodynamic simulations and lattice quantum chromodynamics (QCD) predictions of the equation of state at high temperatures and small chemical potential. Implications to search for QCD phase transition and the critical point are discussed.

   nucl-exEPJ Web Conf.(2024)·4 citations
2. 02*

   A novel technique of extracting UCN lifetimes from storage bottle measurements dominated by scattering losses

   Prajwal Mohanmurthy🇺🇸 · Joseph Formaggio🇺🇸 · Daniel J. Salvat🇺🇸 · Jeff A. Winger🇺🇸

   Neutron lifetime is a critical parameter in the Standard Model. Its measurements using, particularly, the beamline and ultracold neutron storage techniques reveals serious tension. The status of the tension between various measurements have been presented, in light of the insights provided by the $\beta$-decay correlation measurements. When ultracold neutrons are stored in material bottles, they can be lost to various processes, such as $\beta$-decay and up-scattering on material walls. Here, we revisit the lifetime measurement in a material storage bottle, dominated by losses from scattering off the walls of the storage chamber. The neutron energy spectra and its associated uncertainties were, for the first time, well characterized. Such models have been used in the extraction of mean time between wall bounces, which is a key parameter for neutron storage disappearance experiments in search of neutron oscillation. A comparison between the loss model and the number of neutrons stored in a single chamber, used for the neutron electric dipole moment search, allowed us to extract a neutron lifetime of ${\tau }_n^{\ast }=879(+158/-78{)}_{\text{stat.}}(+230/-114{)}_{\text{sys.}}\text{s (68.3\% C.I.)}$. Though the uncertainty on this lifetime is not competent with currently available measurements, the highlight of this work is that, we precisely identify the systematic sources of uncertainty that contribute to the neutron lifetime measurements in material storage bottles, namely from the uncertainty in the energy spectra, as well as the storage chamber parameters of Fermi potential and loss per bounce parameter. In doing so, we finally highlight the underestimation of the uncertainties in the previous Monte Carlo simulations of experiments using ultracold neutron storage in material bottles.

   nucl-exSymmetry(2023)·1 citation
3. 03*

   Anti-deuteron beam study at J-PARC HEF K1.8 beam line

   M. Ukai (1 and 2)🇯🇵 · Y. Ishikawa (2)🇯🇵 · T. Takahashi (1)🇯🇵 · K. Tanida (3)🇯🇵 · T. O. Yamamoto (3) ((1) KEK IPNS, (2) Tohoku Univ., (3) JAEA ASRC)🇯🇵

   We performed a $\overline{d}$ beam study at the K1.8 beam line of J-PARC Hadron Experimental Facility. 1.8 GeV/$c$ $\overline{d}$ beam yield was measured to be 0.30 $\pm$ 0.04 counts/spill for 30 GeV 70 $\times 10^{12}$ protons/spill irradiated on a 66 mm thick of gold target with the vertical slit opening widths of 2.2 mm, 5 mm and 5 mm for intermediate focus (IFV), mass slit 1 (MS1) and 2 (MS2), respectively. Corresponding $\overline{p}$ beam yield is roughly estimated to be $\sim$ 0.3 Mcounts/spill for the same slit condition. Then, the $\overline{d}/\overline{p}$ production ratio at extraction angle of 6 degrees is estimated to be $\sim 10^{-6}$. This is the first time measurement of the $\overline{d}$ beam yield and $\overline{d}/\overline{p}$ production ratio at J-PARC. Further beam line tuning may increase the $\overline{d}$ beam yield.

   nucl-ex0 citations
4. 04*

   Measurements of azimuthal anisotropies in ${}^{16}$O+${}^{16}$O and $\gamma$+Au collisions from STAR

   Shengli Huang🇺🇸

   In this proceeding, we present the first measurements of azimuthal anisotropies, $v_2$ and $v_3$, in ${}^{16}$O+${}^{16}$O collisions at 200 GeV as a function of transverse momentum and multiplicity, by using two- and four-particle correlation methods. We compare our measurements with STAR measurements of $v_n$ in \dau and \heau collisions to provide insight into the impact of system symmetry on initial condition for small systems. We also investigate the ratio $v_2\{4\}/v_2\{2\}$ as a function of centrality, which is expected to be sensitive to nucleon-nucleon correlation in the ${}^{16}$O nucleus.

   nucl-exnucl-th29 citations
5. 05*

   First constraint on the dissipative tidal deformability of neutron stars

   Justin L. Ripley🇺🇸 · Abhishek Hegade K.R.🇺🇸 · Rohit S. Chandramouli🇺🇸 · Nicolas Yunes🇺🇸

   The gravitational waves (GWs) emitted by neutron star binaries probe the physics of matter at supra nuclear densities. During the late inspiral, tidal deformations raised on each star by the gravitational field of its companion depend crucially on the star's internal properties. The misalignment of a star's tidal bulge with its companion's gravitational field encodes the strength of internal dissipative processes, which imprint onto the phase of the gravitational waves emitted. We here analyze GW data from the GW170817 (binary neutron star) event detected by LIGO and Virgo and find the first constraint on the dissipative tidal deformability of a neutron star. From this constraint, \emph{assuming} a temperature profile for each star in the binary, we obtain an order of magnitude bound on the averaged bulk ($\zeta$) and shear ($\eta$) viscosity of each star during the inspiral.: $\zeta \lesssim 10^{31}\mathrm{g}{\mathrm{cm}}^{-1}{\mathrm{s}}^{-1}$ and $\eta \lesssim 10^{28}\mathrm{g}{\mathrm{cm}}^{-1}{\mathrm{s}}^{-1}$. We forecast that these bounds could be improved by two orders of magnitude with third-generation detectors, like Cosmic Explorer, using inspiral data. These constraints already inform nuclear physics models and motivate further theoretical work to better understand the interplay between viscosity and temperature in the late inspiral of neutron stars.

   ↳ gr-qcastro-ph.HEnucl-exnucl-thNature Astron.(2024)·52 citations
6. 06*

   Constraints on Phase Transitions in Neutron Star Matter

   Len Brandes🇩🇪 · Wolfram Weise🇩🇪

   Recent inference results of the sound velocity in the cores of neutron stars are summarized. Implications for the equation of state and the phase structure of highly compressed baryonic matter are discussed. In view of the strong constraints imposed by the heaviest known pulsars, the equation of state must be very stiff in order to ensure the stability of these extreme objects. This required stiffness limits the possible appearance of phase transitions in neutron star cores. For example, a Bayes factor analysis quantifies strong evidence for squared sound velocities $c_s^2>0.1$ in the cores of 2.1 solar-mass and lighter neutron stars. Only weak first-order phase transitions with a small phase coexistence density range $\Delta \rho /\rho <0.2$ (at the 68\% level) in a Maxwell construction still turn out to be possible within neutron stars. The central baryon densities in even the heaviest neutron stars do not exceed five times the density of normal nuclear matter. In view of these data-based constraints, much discussed issues such as the quest for a phase transition towards restored chiral symmetry, and the active degrees of freedom in cold and dense baryonic matter, are reexamined.

   ↳ nucl-thastro-ph.HEhep-phnucl-exSymmetry(2024)·40 citations
7. 07*

   Finite-size behavior of higher-order cumulant ratios near criticality in two-dimensional Potts models

   Rajiv V. Gavai🇮🇳 · Bedangadas Mohanty🇮🇳 · Jaydev Singh Rao🇮🇳 · Swati Saha🇮🇳

   Theoretical considerations predict a specific hierarchy among ratios of net-baryon number cumulants (${\chi }_n$, where $n$ is the order of cumulant) in the vicinity of the transition from the low-temperature hadronic phase to the high temperature quark-gluon plasma phase at small baryon chemical potential, ${\mu }_{\mathrm{B}}$, in the QCD phase diagram. This hierarchy, $\frac{{\chi }_6}{{\chi }_2}<\frac{{\chi }_5}{{\chi }_1}<\frac{{\chi }_4}{{\chi }_2}<\frac{{\chi }_3}{{\chi }_1}$, has been observed by the STAR experiment in net-proton number (a proxy of net-baryon number) cumulant ratios over a broad range of collision energies. Motivated by these findings, we investigate whether similar ordering emerges generically in finite statistical systems undergoing second-order phase transitions. We employ two different spin models: the two-state and three-state Potts models in two dimensions, both exhibiting a transition from an ordered phase to a disordered phase at their respective critical temperatures. Monte Carlo simulations are performed on square lattices of varying sizes using the Wolff cluster algorithm. Cumulants of the total magnetization are calculated up to sixth order in both of these models in a temperature range near their corresponding critical temperatures. Higher-order cumulants exhibit extrema (peaks/troughs) whose magnitudes grow with both cumulant order and lattice size, reflecting enhanced critical fluctuations. Except within a narrow temperature window above the critical temperature, neither the complete hierarchy nor its exact reverse is realized over the studied temperature range in either model.

   ↳ hep-latnucl-exnucl-thJ.Phys.G(2026)·1 citation
8. 08*

   Heavy Quark Momentum Broadening in a Non-Abelian Plasma away from Thermal Equilibrium

   Harshit Pandey🇮🇳 · Soeren Schlichting🇩🇪 · Sayantan Sharma🇮🇳

   We perform classical-statistical real-time lattice simulations to compute real-time spectral functions and momentum broadening of quarks in the presence of strongly populated non-Abelian gauge fields. Based on a novel methodology to extract the momentum broadening for relativistic quarks, we find that the momentum distribution of quarks exhibit interesting non-perturbative features as a function of time due to correlated momentum kicks it receives from the medium, eventually going over to a diffusive regime. We extract the momentum diffusion coefficient for a mass range describing charm and bottom quarks and find sizeable discrepancies from the heavy quark limit.

   ↳ hep-lathep-phnucl-exnucl-thPRL(2024)·28 citations
9. 09*

   Nuclear elastic scattering of protons below 250 MeV in FLUKA v4-4.0 and its role in single-event-upset production in electronics

   Alexandra-Gabriela Serban · Andrea Coronetti🇨🇭 · Ruben Garcia Alia🇨🇭 · Francesc Salvat Pujol🇨🇭

   FLUKA is among the general-purpose codes for the Monte Carlo simulation of radiation transport that are routinely employed to estimate the production of single-event-upsets (SEUs) in commercial static random access memories (SRAMs) exposed to radiation. Earlier studies concerning the production of SEUs in commercial SRAMs under proton irradiation revealed very good agreement between experimental measurements and FLUKA estimates of the SEU production cross section for proton energies above 20-30 MeV. However, at lower proton energies, where the cross section for SEU production in such low-critical-charge components increases drastically, a FLUKA underestimation of up to two orders of magnitude was observed. Preliminary analyses indicated that this underestimation was in great measure due to the lack of nuclear elastic scattering of protons below 10 MeV in FLUKA up to version 4-3.4. To overcome this limitation, a new model for the nuclear elastic scattering of protons has been developed, combining partial-wave analyses and experimental angular distributions. This newly developed model has been included in FLUKA v4-4.0, and leads to an order-of-magnitude improvement in the agreement between FLUKA and experimental cross sections for the production of SEUs in SRAMs under proton irradiation in the 1-10 MeV energy domain.

   ↳ physics.comp-phnucl-exphysics.acc-phComput.Phys.Commun.(2024)·3 citations
10. 10*

    Time Projection Chamber for GADGET II

    Ruchi Mahajan · T. Wheeler · E. Pollacco · C. Wrede · A. Adams · H. Alvarez-Pol · A. Andalib · A. Anthony · Y. Ayyad · D. Bazin · T. Budner · M. Cortesi and 8 other authors

    Background: The established GADGET detection system, designed for measuring weak, low-energy $\beta$-delayed proton decays, features a gaseous Proton Detector with MICROMEGAS readout for calorimetric particle detection, surrounded by a Segmented Germanium Array for high-resolution prompt $\gamma$-ray detection. Purpose: To upgrade GADGET's Proton Detector to operate as a compact Time Projection Chamber (TPC) for the detection, 3D imaging and identification of low-energy $\beta$-delayed single- and multi-particle emissions mainly of interest to astrophysical studies. Method: A new high granularity MM board with 1024 pads has been designed, fabricated, installed and tested. A high-density data acquisition system based on Generic Electronics for TPCs has been installed and optimized to record and process the gas avalanche signals collected on the readout pads. The TPC's performance has been tested using a ${}^{220}$Rn $\alpha$-particle source and cosmic-ray muons. In addition, decay events in the TPC have been simulated by adapting the ATTPCROOT data analysis framework. Further, a novel application of 2D convolutional neural networks for GADGET II event classification is introduced. Results: The GADGET II TPC is capable of detecting and identifying $\alpha$-particles, as well as measuring their track direction, range, and energy. It has also been demonstrated that the GADGET II TPC is capable of tracking cosmic-ray muons. In addition to being one of the first generation of micro pattern gaseous detectors to utilize a resistive anode applied to low-energy nuclear physics, the GADGET II TPC will also be the first TPC surrounded by a high-efficiency array of high-purity germanium $\gamma$-ray detectors. \textbf{Conclusions:} The TPC of GADGET II has been designed, fabricated, tested, and is ready for operation at the FRIB for radioactive beam-line experiments.

    ↳ physics.ins-detnucl-exPRC(2024)·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.