Tue·Jan 16, 2024Tuesday·January 16, 2024

1. 01*

   Extracting the speed of sound in quark-gluon plasma with ultrarelativistic lead-lead collisions at the LHC

   CMS Collaboration

   Ultrarelativistic nuclear collisions create a strongly interacting state of hot and dense quark-gluon matter that exhibits a remarkable collective flow behavior with minimal viscous dissipation. To gain deeper insights into its intrinsic nature and fundamental degrees of freedom, we determine the speed of sound in an extended volume of quark-gluon plasma using lead-lead (PbPb) collisions at a center-of-mass energy per nucleon pair of 5.02 TeV. The data were recorded by the CMS experiment at the CERN LHC and correspond to an integrated luminosity of 0.607 nb${}^{-1}$. The measurement is performed by studying the multiplicity dependence of the average transverse momentum of charged particles emitted in head-on PbPb collisions. Our findings reveal that the speed of sound in this matter is nearly half the speed of light, with a squared value of 0.241 $\pm$ 0.002 (stat) $\pm$ 0.016 (syst) in natural units. The effective medium temperature, estimated using the mean transverse momentum, is 219 $\pm$ 8 (syst) MeV. The measured squared speed of sound at this temperature aligns precisely with predictions from lattice quantum chromodynamic (QCD) calculations. This result provides a stringent constraint on the equation of state of the created medium and direct evidence for a deconfined QCD phase being attained in relativistic nuclear collisions.

   nucl-exhep-exRept.Prog.Phys.(2024)·54 citations
2. 02*

   Background study of the AMoRE-pilot experiment

   A. Agrawal · V.V. Alenkov · P. Aryal · J. Beyer🇩🇪 · B. Bhandari🇺🇸 · R.S. Boiko🇺🇦 · K. Boonin · O. Buzanov · C.R. Byeon · N. Chanthima · M.K. Cheoun🇰🇷 · J.S. Choe and 96 other authors

   We report a study on the background of the Advanced Molybdenum-Based Rare process Experiment (AMoRE), a search for neutrinoless double beta decay (\znbb) of ${}^{100}$Mo. The pilot stage of the experiment was conducted using $\sim$1.9 kg of \CAMOO~ crystals at the Yangyang Underground Laboratory, South Korea, from 2015 to 2018. We compared the measured $\beta /\gamma$ energy spectra in three experimental configurations with the results of Monte Carlo simulations and identified the background sources in each configuration. We replaced several detector components and enhanced the neutron shielding to lower the background level between configurations. A limit on the half-life of $0\nu \beta \beta$ decay of ${}^{100}$Mo was found at $T_{1/2}^{0\nu }\ge 3.0\times 10^{23}$ years at 90\% confidence level, based on the measured background and its modeling. Further reduction of the background rate in the AMoRE-I and AMoRE-II are discussed.

   nucl-exhep-exAstropart.Phys.(2024)·14 citations
3. 03*

   Study of ${}^{113}$In($\alpha ,\alpha$) elastic scattering to determine $\alpha$-optical potential relevant for astrophysical $\gamma$-process

   Dipali Basak🇮🇳 · Tanmoy Bar · Lalit Kumar Sahoo · Sukhendu Saha · T. K. Rana · S. Manna · C. Bhattacharya🇮🇳 · Samir Kundu · J. K. Sahoo · J. K. Meena · A. K. Saha · Ashok Kumar Mondal🇮🇳 · Chinmay Basu

   The $\alpha$-optical potential is one of the key input parameters used to measure the reaction rate of the ($\gamma ,\alpha$)-process using the Hauser-Feshbach(HF) statistical model and the principle of detailed balance. $\alpha$-elastic scattering experiment on ${}^{113}$In $p$-nucleus was carried out in the energy range E${}_{lab}$=26$-$32 MeV. The vacuum evaporation technique was used to prepare the ${}^{113}$In target~($\sim$86 $\mu$g/cm${}^2$). An energy-dependent local optical potential parameters set was obtained by analysing the experimental elastic scattering angular distribution data. The local potential parameters are extrapolated for lower energies and are used to measure the ${}^{113}$In($\alpha ,\gamma$) reaction cross-section.

   nucl-exastro-ph.SRJ.Phys.G(2024)·1 citation
4. 04*

   Fusion of ${}^7$Li with ${}^{205}$Tl at near barrier energies

   V. V. Parkar · Prasanna M. · Ruchi Rathod · V. Jha🇮🇳 · S. K. Pandit🇮🇳 · A. Shrivastava🇮🇳 · K. Mahata🇩🇪 · K. Ramachandran🇮🇳 · R. Palit🇩🇪 · Md. S. R. Laskar · B. J. Roy🇮🇳 · Bhushan Kanagalekar · B. G. Hegde

   The complete and incomplete fusion cross sections for the ${}^7$Li+${}^{205}$Tl reaction were measured at near barrier energies by online characteristic $\gamma$ ray detection technique. The complete fusion (CF) cross sections at energies above the Coulomb barrier were found to be suppressed by $\sim$ 26 \% compared to the coupled channel calculations. Reduced fusion cross sections for the present system at energies normalised to the Coulomb barrier were also found to be systematically lower than those with strongly bound projectiles forming a similar compound nucleus. The suppression observed in CF cross sections is found to be commensurate with the measured total incomplete fusion (ICF) cross sections. In the ICF cross sections, t capture is found to be dominant than $\alpha$ capture at all the measured energies. The systematic study of available CF, ICF and total fusion (TF) data with ${}^7$Li projectile is performed.

   nucl-exnucl-thPRC(2024)·11 citations
5. 05*

   Probing proton cross-shell excitations through the two-neutron removal from 38Ca

   T. Beck · A. Gade🇺🇸 · B. A. Brown🇺🇸 · J. A. Tostevin🇬🇧 · D. Weisshaar🇺🇸 · D. Bazin🇺🇸 · K. W. Brown🇺🇸 · R. J. Charity🇺🇸 · P. J. Farris · S. A. Gillespie🇨🇦 · A. M. Hill · J. Li🇨🇳 and 3 other authors

   Bound states of the neutron-deficient, near-dripline nucleus ${}^{36}$Ca were populated in two-neutron removal from the ground state of ${}^{38}$Ca, a direct reaction sensitive to the single-particle configurations and couplings of the removed neutrons in the projectile wave function. Final-state exclusive cross sections for the formation of ${}^{36}$Ca and the corresponding longitudinal momentum distributions, both determined through the combination of particle and $\gamma$-ray spectroscopy, are compared to predictions combining eikonal reaction theory and shell-model two-nucleon amplitudes from the USDB, USDC, and ZBM2 effective interactions. The final-state cross-section ratio $\sigma (2_1^{+})/\sigma (0^{+})$ shows particular sensitivity and is approximately reproduced only with the two-nucleon amplitudes from the ZBM2 effective interaction that includes proton cross-shell excitations into the $pf$ shell. Characterizing the proton $pf$-shell occupancy locally and schematically, an increase of the $sd$-$pf$ shell gap by $250$ keV yields an improved description of this cross-section ratio and simultaneously enables a reproduction of the $B(E2;0_1^{+}\to 2_1^{+})$ excitation strength of ${}^{36}$Ca. This highlights an important aspect if a new shell-model effective interaction for the region was to be developed on the quest to model the neutron-deficient Ca isotopes and surrounding nuclei whose structure is impacted by proton cross-shell excitations.

   nucl-exPRC(2023)·11 citations
6. 06*

   Searches for axion-like particles in proton-proton and ion-ion collisions at energies in the center of mass system of 5.02 TeV and 13 TeV

   T.V. Obikhod🇺🇦 · S.B. Chernyshenko🇺🇦

   As part of experimental measurements by the ATLAS collaboration during 2015 and 2018 years of light-on-light scattering in Pb+Pb collisions, at an integrated luminosity of 2.2 nb${}^{-1}$ and energy of 5.02 TeV, we modeled the cross sections of the axion-like particle (ALP) production, candidates for dark matter, with subsequent decay into gamma quanta. The obtained calculations showed the dependence of the cross section on the number of ALPs events, on the energy in the center of mass system in proton-proton and Pb-Pb collisions and on the mass region of the ALPs. Using four models with the parameters, which specify the Good-Walker eigenstates, we calculated the ALP production cross sections in proton-proton collisions for the single dissociation and diffractive dissociation components.

   ↳ hep-phnucl-exIOSR Journal of Applied Physics (IOSR-JAP…·0 citations
7. 07*

   Mini-jet Clustering Algorithm Using Transverse-momentum Seeds in High-energy Nuclear Collisions

   Hanpu Jiang🇺🇸 · Nanxi Yao🇺🇸 · Cheuk-Yin Wong🇺🇸 · Gang Wang🇺🇸 · Huan Zhong Huang🇺🇸

   We propose an algorithm to detect mini-jet clusters in high-energy nuclear collisions, by selecting a high-transverse-momentum ($p_T$) particle as a seed and assigning a clustering radius ($R$) in the pseudorapidity and azimuthal-angle space. Our PYTHIA simulations for $p$+$p$ collisions show that a scheme with a seeding $p_T$ of around 0.5 GeV/$c$ and $R$ of approximately 0.6 satisfactorily identifies mini-jet clusters. The correlation between clusters obtained in PYTHIA calculations using the algorithm exhibits the proper behavior of hard-scattering-like processes, suggesting its usefulness in isolating mini-jet-like clusters from non-hard-scattering soft processes when applied to actual nuclear-collision data, thereby allowing a closer examination of both the mini-jet and the soft mechanisms.

   ↳ physics.data-annucl-exnucl-thPRC(2024)·0 citations
8. 08*

   First Dark Matter Limits from the COUPP 4kg Bubble Chamber at a Deep Underground Site

   Drew Fustin🇺🇸

   The COUPP 4 kg bubble chamber employs 4.0 kg of CF${}_3$I as a WIMP scattering target for use as a dark matter direct detection search. This thesis reports the first experimental results from operating this bubble chamber at the deep underground site (6000 m.w.e.) of SNOLAB, near Sudbury, Ontario. Twenty dark matter candidate events were observed during an effective exposure of 553.0 kg-days, when operating the bubble chamber at three different bubble nucleation thresholds. These data are consistent with a neutron background internal to the detector. Characterization of this neutron background has led to the recommendation to replace two detector components to maximize dark matter signal sensitivity in a future run with this bubble chamber. A measurement of the gamma-ray flux has confirmed that this detector should not be sensitive to a gamma-induced background for more than three orders of magnitude below current sensitivity. The dark matter search data presented here set a new world-leading limit on the spin-dependent WIMP-proton scattering cross section and demonstrate significant sensitivity to spin-independent WIMP-nucleon scattering.

   ↳ astro-ph.COhep-exnucl-ex7 citations
9. 09*

   Weak magnetic effect in quark-gluon plasma and local spin polarization

   Jing-An Sun🇨🇳 · Li Yan🇨🇳

   We propose the weak magnetic effect, which emerges in quark-gluon plasma close to local thermal equilibrium as the dissipative correction to the quark phase space distribution function, as a novel contribution to the observed Lambda hyperon local spin polarization. With a finite field strength, which is consistent with previous estimate of the magnetic field in heavy-ion collisions, one is able to explain the experimentally observed Lambda local spin polarization through all centrality classes. Moreover, the weak magnetic effect plays an unambiguous role in the ordering between the second-order and the third-order modulations of the Lambda local spin polarization in experiments.

   ↳ nucl-thhep-phnucl-exCPC(2025)·10 citations
10. 10*

    Detector performance of the Gamma-ray Transient Monitor onboard DRO-A Satellite

    Pei-Yi Feng (1, 2) · Zheng-Hua An (1) · Da-Li Zhang (1)🇨🇳 · Chen-Wei Wang (1 and 2)🇨🇳 · Chao Zheng (1 and 2) · Sheng Yang (1) · Shao-Lin Xiong (1)🇨🇳 · Jia-Cong Liu (1 and 2) · Xin-Qiao Li (1) · Ke Gong (1)🇨🇳 · Xiao-Jing Liu (1) · Min Gao (1) and 6 other authors

    Gamma-ray Transient Monitor (GTM) is an all-sky monitor onboard the Distant Retrograde Orbit-A (DRO-A) satellite with the scientific objective of detecting gamma-ray transients ranging from 20 keV to 1 MeV. GTM is equipped with 5 Gamma-ray Transient Probe (GTP) detector modules, utilizing the NaI(Tl) scintillator coupled with a SiPM array. To reduce the SiPM noise, GTP makes use of a dedicated dual-channel coincident readout design. In this work, we firstly studied the impact of different coincidence times on detection efficiency and ultimately selected the 500 ns time coincidence window for offline data processing. To test the performance of GTPs and validate the Monte Carlo simulated energy response, we conducted comprehensive ground calibration tests using Hard X-ray Calibration Facility (HXCF) and radioactive sources, including energy response, detection efficiency, spatial response, bias-voltage response, and temperature dependence. We extensively presented the ground calibration results, and validated the design and mass model of GTP detector. These work paved the road for the in-flight observation and science data analysis.

    ↳ astro-ph.IMhep-exnucl-exphysics.ins-detSCPMA(2024)·12 citations
11. 11*

    Calculation of Fission Fragment Yields for thermal neutron reaction of ${}^{239}$Pu

    Futoshi Minato🇯🇵

    Fission fragment yield evaluation in the past has been done mainly by considering independent and cumulative fission yields. In addition to them, the fission fragment yields are related to various observables such as total kinetic energy, prompt fission neutron, decay heats, etc. Various improvements were carried out in the fission fragment yield evaluation of JENDL-5, however it did not consider correlations between such fission observables and fragment yields. A new evaluation including fission observables is thus required for next generation of evaluated data. We recently developed a new calculation system using CCONE code to calculate fission fragment yields. This calculation system enables us to compare various fission observables with the experimental data simultaneously. In this work, we calculated thermal-induced fission of 239Pu. We present the result of prompt fission neutrons, decay heats, and delayed neutrons

    ↳ nucl-thnucl-ex0 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.