Thu·Jul 27, 2023Thursday·July 27, 2023

1. 01*

   Jet-hadron correlations with respect to the event plane in $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV Au+Au collisions in STAR

   STAR Collaboration: M. I. Abdulhamid · B. E. Aboona · J. Adam · L. Adamczyk · J. R. Adams · I. Aggarwal · M. M. Aggarwal · Z. Ahammed · E. C. Aschenauer · S. Aslam · J. Atchison · V. Bairathi and 352 other authors

   Angular distributions of charged particles relative to jet axes are studied in $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV Au+Au collisions as a function of the jet orientation with respect to the event plane. This differential study tests the expected path-length dependence of energy loss experienced by a hard-scattered parton as it traverses the hot and dense medium formed in heavy-ion collisions. A second-order event plane is used in the analysis as an experimental estimate of the reaction plane formed by the collision impact parameter and the beam direction. Charged-particle jets with $15<p_{\mathrm{T},\mathrm{jet}}<$ 20 and $20<p_{\mathrm{T},\mathrm{jet}}<$ 40 GeV/$c$ were reconstructed with the anti-$k_{\mathrm{T}}$ algorithm with radius parameter setting of (R=0.4) in the 20-50\% centrality bin to maximize the initial-state eccentricity of the interaction region. The reaction plane fit method is implemented to remove the flow-modulated background with better precision than prior methods. Yields and widths of jet-associated charged-hadron distributions are extracted in three angular bins between the jet axis and the event plane. The event-plane (EP) dependence is further quantified by ratios of the associated yields in different EP bins. No dependence on orientation of the jet axis with respect to the event plane is seen within the uncertainties in the kinematic regime studied. This finding is consistent with a similar experimental observation by ALICE in $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV Pb+Pb collision data.

   nucl-exhep-exPRC(2024)·3 citations
2. 02*

   Charged particle pseudorapidity distributions measured with the STAR EPD

   Mátyás Molnár (for the STAR Collaboration)🇭🇺

   In 2018, in preparation for the Beam Energy Scan II, the STAR detector was upgraded with the Event Plane Detector (EPD). The instrument enhanced STAR's capabilities in centrality determination for fluctuation measurements, event plane resolution for flow measurements and in triggering overall. Due to its fine radial granularity, it can also be utilized to measure pseudorapidity distributions of the produced charged primary particles, in EPD's pseudorapidity coverage of $2.15<|\eta |<5.09$. As such a measurement cannot be done directly, the response of the detector to the primary particles has to be understood well. The detector response matrix was determined via Monte Carlo simulations and corrected charged particle pseudorapidity distributions were obtained in Au+Au collisions at center of mass collision energies $\sqrt{s_{{}_{NN}}}$ = 19.6 and 27.0 GeV using an iterative unfolding procedure. Several systematic checks of the method were also done.

   nucl-exUniverse(2023)·2 citations
3. 03*

   Measurement of Non-prompt ${\mathrm{D}}^0$-meson Elliptic Flow in Pb-Pb Collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV

   ALICE Collaboration

   The elliptic flow ($v_2$) of ${\mathrm{D}}^0$ mesons from beauty-hadron decays (non-prompt ${\mathrm{D}}^0$) was measured in midcentral (30-50%) Pb-Pb collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV with the ALICE detector at the LHC. The ${\mathrm{D}}^0$ mesons were reconstructed at midrapidity ($|y|<0.8$) from their hadronic decay ${\mathrm{D}}^0\to {\mathrm{K}}^{-}{\pi }^{+}$, in the transverse momentum interval $2<p_{\mathrm{T}}<12$ GeV/$c$. The result indicates a positive $v_2$ for non-prompt ${\mathrm{D}}^0$ mesons with a significance of 2.7$\sigma$. The non-prompt ${\mathrm{D}}^0$-meson $v_2$ is lower than that of prompt non-strange D mesons with 3.2$\sigma$ significance in $2<p_{\mathrm{T}}<8$ GeV/$c$, and compatible with the $v_2$ of beauty-decay electrons. Theoretical calculations of beauty-quark transport in a hydrodynamically expanding medium describe the measurement within uncertainties.

   nucl-exhep-exEPJC(2023)·32 citations
4. 04*

   Measurement of the $2\nu \beta \beta$ decay rate and spectral shape of ${}^{100}$Mo from the CUPID-Mo experiment

   C. Augier🇫🇷 · A. S. Barabash🇷🇺 · F. Bellini🇮🇹 · G. Benato🇮🇹 · 6 M. Beretta🇺🇸 · L. Berge🇫🇷 · J. Billard🇫🇷 · Yu. A. Borovlev🇷🇺 · L. Cardani🇮🇹 · N. Casali🇮🇹 · A. Cazes🇫🇷 · E. Celi🇮🇹 and 72 other authors

   Neutrinoless double beta decay ($0\nu \beta \beta$) is a yet unobserved nuclear process which would demonstrate Lepton Number violation, a clear evidence of beyond Standard Model physics. The process two neutrino double beta decay ($2\nu \beta \beta )$ is allowed by the Standard Model and has been measured in numerous experiments. In this letter, we report a measurement of $2\nu \beta \beta$ decay half-life of ${}^{100}$Mo to the ground state of ${}^{100}$Ru of $(7.07\pm 0.02\text{(stat.)}\pm 0.11\text{(syst.)})\times 10^{18}$~yr by the CUPID-Mo experiment. With a relative precision of $\pm 1.6$ \% this is the most precise measurement to date of a $2\nu \beta \beta$ decay rate in ${}^{100}$Mo. In addition, we constrain higher-order corrections to the spectral shape which provides complementary nuclear structure information. We report a novel measurement of the shape factor ${\xi }_{3,1}=0.45\pm 0.03\text{(stat.)}\pm 0.05\text{(syst.)}$, which is compared to theoretical predictions for different nuclear models. We also extract the first value for the effective axial vector coupling constant obtained from a spectral shape study of $2\nu \beta \beta$ decay.

   nucl-exhep-exPRL(2023)·39 citations
5. 05*

   Modification of charged-particle jets in event-shape engineered Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

   ALICE Collaboration

   Charged-particle jet yields have been measured in semicentral Pb$-$Pb collisions at center-of-mass energy per nucleon-nucleon collision $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with the ALICE detector at the LHC. These yields are reported as a function of the jet transverse momentum, and further classified by their angle with respect to the event plane and the event shape, characterized by ellipticity, in an effort to study the path-length dependence of jet quenching. Jets were reconstructed at midrapidity from charged-particle tracks using the anti-$k_{\mathrm{T}}$ algorithm with resolution parameters $R=$ 0.2 and 0.4, with event-plane angle and event-shape values determined using information from forward scintillating detectors. The results presented in this letter show that, in semicentral Pb$-$Pb collisions, there is no significant difference between jet yields in predominantly isotropic and elliptical events. However, out-of-plane jets are observed to be more suppressed than in-plane jets. Further, this relative suppression is greater for low transverse momentum ($<$ 50 GeV/$c$) $R=$ 0.2 jets produced in elliptical events, with out-of-plane to in-plane jet-yield ratios varying up to 5.2$\sigma$ between different event-shape classes. These results agree with previous studies indicating that jets experience azimuthally anisotropic suppression when traversing the QGP medium, and can provide additional constraints on the path-length dependence of jet energy loss.

   nucl-exhep-exPLB(2024)·7 citations
6. 06*

   Local multiplicity fluctuations in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV with ALICE at the LHC

   Sheetal Sharma🇮🇳 · Ramni Gupta (for the ALICE Collaboration)🇮🇳

   Local multiplicity fluctuations are an useful tool to understand the dynamics of the particle production and the phase-space changes from quarks to hadrons in ultrarelativistic heavy-ion collisions. The study of scaling behavior of multiplicity fluctuations in geometrical configurations in multiparticle production can be performed using the factorial moments and recognized in terms of a phenomenon referred to as intermittency. In this contribution, the analysis of the factorial moment is presented for the multiplicity distributions of charged particles produced in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV, recorded with the ALICE detector at the LHC. The normalized factorial moments (NFM), $F_q$ of the spatial configurations of charged particles in two-dimensional angular ($\eta ,\phi$) phase space are calculated. For a system with dynamic fluctuations due to the characteristic critical behavior near the phase transition, $F_q$ exhibits power-law growth with increasing bin number or decreasing bin size which indicates self-similar fluctuations. Relating the $q^{\mathrm{th}}$ order NFM ($F_q$) to the second-order NFM ($F_2$), the value of the scaling exponent ($\nu$) is extracted, which indicates the order of the phase transition within the framework of Ginzburg-Landau theory. The dependence of scaling exponent on the $p_{\mathrm{T}}$ bin width will be presented. The measurements are also compared with the corresponding results from the AMPT model and a Toy Monte Carlo (MC) simulation.

   nucl-exhep-exSpringer Proc.Phys.(2024)·5 citations
7. 07*

   Dwarf (Twin) Neutron Stars I: Did GW170817 Involve One?

   Dake Zhou🇺🇸

   Dwarf neutron stars are stable twins of neutron stars but with a maximum mass less than that of neutron stars. Their existence brings into concordance the seemingly conflicting information on the size of neutron stars inferred from gravitational waves from GW170817, from the NICER mission, and from the PREX-II experiment. Their distinctive characteristics lead to rich and falsifiable predictions that are expected to be tested in the near future. If corroborated, the existence of dwarf neutron stars would substantially improve our understanding of the QCD phase diagram and offer valuable insights into the dark sector.

   ↳ astro-ph.HEgr-qchep-phnucl-ex+12 citations
8. 08*

   Networked Sensing for Radiation Detection, Localization, and Tracking

   R.J. Cooper · N. Abgrall🇨🇭 · G. Aversano · M.S. Bandstra · D. Hellfeld · T.H. Joshi · V. Negut · B.J. Quiter · E. Rofors🇸🇪 · M. Salathe🇺🇸 · K. Vetter · P. Beckman and 9 other authors

   The detection, identification, and localization of illicit radiological and nuclear material continue to be key components of nuclear non-proliferation and nuclear security efforts around the world. Networks of radiation detectors deployed at strategic locations in urban environments have the potential to provide continuous radiological/nuclear (R/N) surveillance and provide high probabilities of intercepting threat sources. The integration of contextual information from sensors such as video, Lidar, and meteorological sensors can provide significantly enhanced situational awareness, and improved detection and localization performance through the fusion of the radiological and contextual data. In this work, we present details of our work to establish a city-scale multi-sensor network testbed for intelligent, adaptive R/N detection in urban environments, and develop new techniques that enable city-scale source detection, localization, and tracking.

   ↳ physics.ins-detnucl-exphysics.app-phJ.Phys.Conf.Ser.(2023)·4 citations
9. 09*

   Skyrme-Hartree-Fock-Bogoliubov mass models on a 3D mesh: III. From atomic nuclei to neutron stars

   Guilherme Grams🇧🇪 · Wouter Ryssens🇧🇪 · Guillaume Scamps🇺🇸 · Stephane Goriely🇧🇪 · Nicolas Chamel🇧🇪

   We present BSkG3, the latest entry in the Brussels-Skyrme-on-a-grid series of large-scale models of nuclear structure based on an energy density functional. Compared to its predecessors, the new model offers a more realistic description of nucleonic matter at the extreme densities relevant to neutron stars. This achievement is made possible by incorporating a constraint on the infinite nuclear matter properties at high densities in the parameter adjustment, ensuring in this way that the predictions of BSkG3 for the nuclear Equation of State are compatible with the observational evidence for heavy pulsars with $M>2M_{\odot }$. Instead of the usual phenomenological pairing terms, we also employ a more microscopically founded treatment of nucleon pairing, resulting in extrapolations to high densities that are in line with the predictions of advanced many-body methods and are hence more suited to the study of superfluidity in neutron stars. By adopting an extended form of the Skyrme functional, we are able to reconcile the description of matter at high densities and at saturation density: the new model further refines the description of atomic nuclei offered by its predecessors. A qualitative improvement is our inclusion of ground state reflection asymmetry, in addition to the spontaneous breaking of rotational, axial, and time-reversal symmetry. Quantitatively, the model offers lowered root-mean-square deviations on 2457 masses (0.631 MeV), 810 charge radii (0.0237 fm) and an unmatched accuracy with respect to 45 primary fission barriers of actinide nuclei (0.33 MeV). Reconciling the complexity of neutron stars with those of atomic nuclei establishes BSkG3 as a tool of choice for applications to nuclear structure, the nuclear equation of state and nuclear astrophysics in general.

   ↳ nucl-thnucl-exEPJA(2023)·43 citations
10. 10*

    Event Shape Selection Method in Search of the Chiral Magnetic Effect in Heavy-ion Collisions

    Zhiwan Xu🇺🇸 · Brian Chan🇺🇸 · Gang Wang🇺🇸 · Aihong Tang🇺🇸 · Huan Zhong Huang🇺🇸

    The search for the chiral magnetic effect (CME) in heavy-ion collisions has been impeded by the significant background arising from the anisotropic particle emission pattern, particularly elliptic flow. To alleviate this background, the event shape selection (ESS) technique categorizes collision events according to their shapes and projects the CME observables to a class of events with minimal flow. In this study, we explore two event shape variables to classify events and two elliptic flow variables to regulate the background. Each type of variable can be calculated from either single particles or particle pairs, resulting in four combinations of event shape and elliptic flow variables. By employing a toy model and the realistic event generator, event-by-event anomalous-viscous fluid dynamics (EBE-AVFD), we discover that the elliptic flow of resonances exhibits correlations with both the background and the potential CME signal, making the resonance flow unsuitable for background control. Through the EBE-AVFD simulations of Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV with various input scenarios, we ascertain that the optimal ESS strategy for background control entails utilizing the single-particle elliptic flow in conjunction with the event shape variable based on particle pairs.

    ↳ nucl-thnucl-exphysics.ins-detPLB(2024)·21 citations
11. 11*

    Recent Upgrades of the Gas Handling System for the Cryogenic Stopping Cell of the FRS Ion Catcher

    A. Mollaebrahimi🇳🇱 · D. Amanbayev🇩🇪 · S. Ayet San Andrés🇩🇪 · S. Beck🇩🇪 · J. Bergmann🇩🇪 · T. Dickel🇩🇪 · H. Geissel🇩🇪 · C. Hornung🇩🇪 · N. Kalantar-Nayestanaki🇳🇱 · G. Kripko-Koncz🇩🇪 · I. Miskun🇩🇪 · D. Nichita🇷🇴 and 6 other authors

    In this paper, the major upgrades and technical improvements of the buffer gas handling system for the cryogenic stopping cell of the FRS Ion Catcher at GSI/FAIR (in Darmstadt, Germany) are described. The upgrades include implementation of new gas lines and gas purifiers to achieve a higher buffer gas cleanliness for a more efficient extraction of reactive ions as well as suppression of the molecular background ionized in the stopping cell. Furthermore, additional techniques have been implemented for improved monitoring and quantification of the purity of the helium buffer gas.

    ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2023)·3 citations
12. 12*

    An express monitoring procedure for low pressure MWPC efficiency value in heavy ion induced complete fusion nuclear reactions

    Yu.S.Tsyganov · D.Ibadullayev · A.N. Polyakov · V.B.Zlokazov

    A simple routine is proposed for monitoring the efficiency value of a low pressure pentane filled multi-wire proportional chamber (MWPC) in long term experiments. The proposed algorithm utilizes a two parameter approximation for the background function. It is based on a linear approximation of the background in the energy range of 4.8 to 10.0 MeV and an exponential approximation of the neutron induced tail in the 1.5 to 4.2 MeV region. This specific energy interval is used to measure the efficiency value. Prior to discussing the algorithm, a description of the DGFRS-2 setup detection module is provided. Additionally, an example of its application is presented for the complete fusion of a heavy ion induced 232Th+48Ca = Ds complete fusion nuclear reaction. Descriptions of two other two-parameter functional dependencies for background approximations are also provided. A feature of this algorithm is that there is no interruption of the main experiment for a calibration test (reaction). An alternative scenario is considered in brief too. In consist of a measurement of scattered target like ions in 30 to 45 MeV energy interval to estimate an efficiency value.

    ↳ physics.ins-detnucl-ex1 citation

* 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.