Tue·Nov 29, 2022Tuesday·November 29, 2022

1. 01*

   Elastic scattering of 3He+4He with SONIK

   S. N. Paneru🇺🇸 · C. R. Brune🇺🇸 · D. Connolly · D. Odell🇺🇸 · M. Poudel · D. R. Phillips🇺🇸 · J. Karpesky🇺🇸 · B. Davids🇨🇦 · C. Ruiz🇨🇦 · A. Lennarz🇨🇦 · U. Greife🇺🇸 · M. Alcorta🇨🇦 and 13 other authors

   Measurements of the elastic scattering cross section of 3He and 4He are important in order to improve constraints on theoretical models of 4He(3He,g)7Be, a key reaction in Big Bang nucleosynthesis and solar neutrino production. The astrophysical S-factor for this reaction is a significant source of uncertainty in the standard solar-model prediction of the 7Be and 8B solar neutrino fluxes. The elastic scattering measurements reported in the literature do not extend to low energies and lack proper uncertainty quantification. A new measurement of the 4He(3He,3He)4He reaction has been made at center-of-mass energies Ec.m. = 0.38-3.13 MeV using the Scattering of Nuclei in Inverse Kinematics (SONIK) scattering chamber: a windowless, extended gas target surrounded by an array of 30 collimated silicon charged particle detectors situated at TRIUMF. This is the first elastic scattering measurement of 3He+4He made below 500 keV and it has greater angular range and better precision than previous measurements. The elastic scattering data were analyzed using both R-matrix and Halo Effective Field Theory (Halo EFT) frameworks, and values of the s-wave scattering length and effective range were extracted. The resulting improvement in knowledge of the s-wave effective-range function at low energies will reduce the overall uncertainty in S34 at solar energies.

   nucl-exnucl-thPRC(2024)·12 citations
2. 02*

   Accelerated electron thermometer: observation of 1D Planck radiation

   Morgan H. Lynch🇮🇱 · Evgenii Ievlev · Michael R. R. Good🇰🇿

   We report on the observation of thermal photons from an accelerated electron via examination of radiative beta decay of free neutrons measured by the RDK II collaboration. The emitted photon spectrum is shown to corroborate a thermal distribution consistent with the dynamical Casimir effect. Supported by a robust chi-squared statistic, we find the photons reside in a one-dimensional Planck spectrum with a temperature predicted by the moving mirror model.

   nucl-exgr-qcPTEP(2024)·17 citations
3. 03*

   Event-by-event fluctuations of mean transverse momentum in Pb-Pb and Xe-Xe collisions with ALICE

   Tulika Tripathy (for the ALICE collaboration)🇮🇳

   Event-by-event fluctuations of the mean transverse momentum of charged particles produced in Pb-Pb and Xe-Xe collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV and $\sqrt{s_{\mathrm{NN}}}$ = 5.44 TeV, respectively, are studied as a function of the charged-particle multiplicity using the ALICE detector at the LHC. Dynamical fluctuations are observed in both collision systems which indicate correlated particle emission. The central Pb-Pb and Xe-Xe collisions show a significant reduction of the fluctuation in comparison to peripheral collisions and are in qualitative agreement with previous measurements in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV. The results are compared with the HIJING model. A clear deviation from simple superposition of independent nucleon-nucleon collisions scenario, where the final state particles are produced from superposition of particle emitting sources, is observed.

   nucl-exhep-exJ.Phys.Conf.Ser.(2023)·4 citations
4. 04*

   Evidence of a new shell closed nucleus governing slow quasi-fission

   A. Pal🇮🇳 · S. Santra🇮🇳 · A. Kundu · D. Chattopadhyay🇮🇳 · P.C. Rout · Ramandeep Gandhi · P. N. Patil · R. Tripathi · B. J. Roy🇮🇳 · Y. Sawant · T.N. Nag · Abhijit Baishya and 3 other authors

   Mass distributions of fission fragments arising from the slow quasi-fission process have been derived by comparing the measured distributions with the theoretical distributions based on compound nuclear fission model for several reactions. The mass-distributions corresponding to quasi-fission events for all the systems show the following common features: (1) they are double peaked with fixed peak-centroids and nearly same width at different incident energies, (2) the yield of quasi-fission events decreases with the increasing projectile energy, and (3) peak corresponding to lighter fragment is observed at A $\sim$ 96 for all the systems, whereas the peak of heavier fragment increases linearly with the mass of the di-nuclear system. All the above observations are quite similar to the ones observed in well known asymmetric fission of actinides, thus providing clear evidences of shell effect in slow quasi-fission where the lighter fragment is possibly nuclei around ${}^{96}$Zr, a new doubly magic nucleus. This finding has great implications in the study of nuclear reactions, structure and particularly in super-heavy element synthesis where quasi-fission is synonymous.

   nucl-ex0 citations
5. 05*

   Investigation of K${}^{+}$K${}^{-}$ interactions via femtoscopy in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV at the LHC

   ALICE Collaboration

   Femtoscopic correlations of non-identical charged kaons (${\mathrm{K}}^{+}{\mathrm{K}}^{-}$) are studied in Pb$-$Pb collisions at a center-of-mass energy per nucleon$-$nucleon collision $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV by ALICE at the LHC. One-dimensional ${\mathrm{K}}^{+}{\mathrm{K}}^{-}$ correlation functions are analyzed in three centrality classes and eight intervals of particle-pair transverse momentum. The Lednický and Luboshitz interaction model used in the ${\mathrm{K}}^{+}{\mathrm{K}}^{-}$ analysis includes the final-state Coulomb interactions between kaons and the final-state interaction through $a_0$(980) and $f_0$(980) resonances. The mass of $f_0$(980) and coupling were extracted from the fit to ${\mathrm{K}}^{+}{\mathrm{K}}^{-}$ correlation functions using the femtoscopic technique. The measured mass and width of the $f_0$(980) resonance are consistent with other published measurements. The height of the $\varphi$(1020) meson peak present in the ${\mathrm{K}}^{+}{\mathrm{K}}^{-}$ correlation function rapidly decreases with increasing source radius, qualitatively in agreement with an inverse volume dependence. A phenomenological fit to this trend suggests that the $\varphi$(1020) meson yield is dominated by particles produced directly from the hadronization of the system. The small fraction subsequently produced by final-state interactions could not be precisely quantified with data presented in this paper and will be assessed in future work.

   nucl-exhep-exPRC(2023)·12 citations
6. 06*

   Search for Electron Capture in ${}^{176}$Lu with LYSO scintillator

   Luigi Ernesto Ghezzer · Francesco Nozzoli🇮🇹 · Riccardo Nicolaidis · Cristian De Santis · Roberto Iuppa · Paolo Zuccon

   The nuclide ${}^{176}$Lu is one of the few naturally occurring isotopes that are potentially unstable with respect to electron capture (EC). Although experimental evidence for ${}^{176}$Lu EC decay is still missing, this isotope is instead well known to ${\beta }^{-}$ decay into ${}^{176}$Hf with an half-life of about 38 Gyr. The precise investigation of all ${}^{176}$Lu possible decay modes is interesting because the Lu/Hf ratio is adopted as an isotopic clock. Previous searches for the ${}^{176}$Lu EC decay were performed by using a passive Lutetium source coupled with an HP-Ge spectrometer. Our approach uses a LYSO crystal both as Lutetium source and as an active detector. Scintillation light from the LYSO crystal is acquired in coincidence with the signals from the HP-Ge detector, this allows a powerful suppression of the background sourcing from the well known ${\beta }^{-}$ decay branch. This coincidence approach led to an improvement on the ${}^{176}$Lu EC branching ratio limits by a factor 3 to 30, depending on the considered EC channel.

   nucl-exhep-exPRC(2023)·3 citations
7. 07*

   Enhanced deuteron coalescence probability in jets

   ALICE Collaboration

   The transverse-momentum ($p_{\mathrm{T}}$) spectra and coalescence parameters $B_2$ of (anti)deuterons are measured in pp collisions at $\sqrt{s}=13$ TeV for the first time in and out of jets. In this measurement, the direction of the leading particle with the highest $p_{\mathrm{T}}$ in the event ($p_{\mathrm{T}}^{\mathrm{lead}}>5$ GeV/$c$) is used as an approximation for the jet axis. The event is consequently divided into three azimuthal regions and the jet signal is obtained as the difference between the Toward region, that contains jet fragmentation products in addition to the underlying event (UE), and the Transverse region, which is dominated by the UE. The coalescence parameter in the jet is found to be approximately a factor of 10 larger than that in the underlying event. This experimental observation is consistent with the coalescence picture and can be attributed to the smaller average phase-space distance between nucleons inside the jet cone as compared to the underlying event. The results presented in this Letter are compared to predictions from a simple nucleon coalescence model, where the phase space distributions of nucleons are generated using PYTHIA 8 with the Monash 2013 tuning, and to predictions from a deuteron production model based on ordinary nuclear reactions with parametrized energy-dependent cross sections tuned on data. The latter model is implemented in PYTHIA 8.3. Both models reproduce the observed large difference between in-jet and out-of-jet coalescence parameters, although the almost flat trend of the $B_2^{\mathrm{Jet}}$ is not reproduced by the models, which instead give a decreasing trend.

   nucl-exhep-exPRL(2023)·28 citations
8. 08*

   Multiplicity dependence of charged-particle production in pp, p-Pb, Xe-Xe and Pb-Pb collisions at the LHC

   ALICE Collaboration

   Multiplicity ($N_{\mathrm{ch}}$) distributions and transverse momentum ($p_{\mathrm{T}}$) spectra of inclusive primary charged particles in the kinematic range of $|\eta |<0.8$ and 0.15 GeV/$c$ $<p_T<$ 10 GeV/$c$ are reported for pp, p-Pb, Xe-Xe and Pb-Pb collisions at centre-of-mass energies per nucleon pair ranging from $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV up to $13$ TeV. A sequential two-dimensional unfolding procedure is used to extract the correlation between the transverse momentum of primary charged particles and the charged-particle multiplicity of the corresponding collision. This correlation sharply characterises important features of the final state of a collision and, therefore, can be used as a stringent test of theoretical models. The multiplicity distributions as well as the mean and standard deviation derived from the $p_{\mathrm{T}}$ spectra are compared to state-of-the-art model predictions. Providing these fundamental observables of bulk particle production consistently across a wide range of collision energies and system sizes can serve as an important input for tuning Monte Carlo event generators.

   nucl-exhep-exPLB(2023)·58 citations
9. 09*

   Pseudorapidity densities of charged particles with transverse momentum thresholds in pp collisions at $\sqrt{s}=5.02$ and $13$ TeV

   ALICE Collaboration

   The pseudorapidity density of charged particles with minimum transverse momentum ($p_{\mathrm{T}}$) thresholds of 0.15, 0.5, 1, and 2 GeV$/c$ is measured in pp collisions at the centre of mass energies of $\sqrt{s}=$ 5.02 and 13 TeV with the ALICE detector. The study is carried out for inelastic collisions with at least one primary charged particle having a pseudorapidity ($\eta$) within $\pm 0.8$ and $p_{\mathrm{T}}$ larger than the corresponding threshold. In addition, measurements without $p_{\mathrm{T}}$-thresholds are performed for inelastic and non-single-diffractive events as well as for inelastic events with at least one charged particle having $|\eta |<1$ in pp collisions at $\sqrt{s}=$ 5.02 TeV for the first time at the LHC. These measurements are compared to the PYTHIA 6, PYTHIA 8, and EPOS-LHC models. In general, the models describe the $\eta$ dependence of particle production well. However, discrepancies are observed for the highest transverse momentum threshold ($p_{\mathrm{T}}>2\mathrm{GeV}/c$), highlighting the importance of such measurements for tuning event generators. The new measurements agree within uncertainties with results from the ATLAS and CMS experiments obtained at $\sqrt{s}=13$ TeV.

   nucl-exhep-exPRD(2023)·22 citations
10. 10*

    Spectral distribution and flux of $\gamma$-ray beams produced through Compton scattering of unsynchronized laser and electron beams

    Dan Filipescu · Ioana Gheorghe · Konstantin Stopani · Sergey Belyshev · Satoshi Hashimoto · Shuji Miyamoto · Hiroaki Utsunomiya

    Intense, quasi-monochromatic, polarized $\gamma$-ray beams produced by Compton scattering of laser photons against relativistic electrons are used for fundamental studies and applications. Following a series of photoneutron cross section measurements in the Giant Dipole Resonance energy region performed at the NewSUBARU synchrotron radiation facility, we have developed the eliLaBr Monte Carlo simulation code for characterization of the scattered $\gamma$-ray photon beams. The code is implemented using Geant4 and is available on the GitHub repository (https://github.com/dan-mihai-filipescu/eliLaBr). Here we report the validation of the eliLaBr code on NewSUBARU LCS $\gamma$-ray beam flux and spectral distribution data and two applications performed with it for asymmetric transverse emittance profiles electron beams, characteristic for synchrotrons. The first application is based on a systematic investigation of transverse collimator offsets relative to the laser and electron beam axis. We show that the maximum energy of the LCS $\gamma$-ray beam is altered by vertical collimator offsets, where the edge shifts towards lower energies with the increase in the offset. Secondly, using the eliLaBr code, we investigate the effect of the laser polarization plane orientation on the properties of the LCS $\gamma$-ray beams produced with asymmetric emittance electron beams. We show that: 1. The use of vertically polarized lasers contributes to the preservation of the LCS $\gamma$-ray beam maximum energy edge by increasing the precision in the vertical collimator alignment. 2. Under identical conditions for the electron and laser beams phase-space distributions, the energy spectrum of the scattered LCS $\gamma$-ray beam changes with the laser beam polarization plane orientation: the use of vertically polarized laser beams slightly deteriorates the LCS $\gamma$-ray beam energy resolution.

    ↳ physics.ins-detnucl-exphysics.acc-phNucl.Instrum.Meth.A(2023)·13 citations
11. 11*

    A model-free procedure to correct for volume fluctuations in E-by-E analyses of particle multiplicities

    Anar Rustamov🇩🇪 · Joachim Stroth🇩🇪 · Romain Holzmann🇩🇪

    We develop an innovative and unbiased procedure, based on event mixing, to account for unavoidable contributions from volume (or system size) fluctuations to experimentally measured moments of particle multiplicity distributions produced in relativistic nuclear collisions. Within the wounded-nucleon model they are characterized by fluctuations of the number of wounded nucleons, the latter usually referred to as participants. For the first time we extract participant fluctuations directly from the data used for the fluctuation analysis, i.e., without involving model calculations. To achieve this we constructed a dedicated event-mixing algorithm that eliminates all possible correlations between produced particles while preserving the volume fluctuations. The procedure provides direct access to the cumulants of wounded-nucleon distributions, which can be used to account for non-critical contributions to the experimentally measured cumulants of multiplicity distributions.

    ↳ nucl-thhep-phnucl-exNPA(2023)·17 citations
12. 12*

    Background measurements and detector response studies for ISMRAN experiment

    R. Dey🇮🇳 · P. K. Netrakanti🇮🇳 · D. K. Mishra🇮🇳 · S. P. Behera🇮🇳 · R. Sehgal🇮🇳 · V. Jha🇮🇳 · L. M. Pant🇮🇳

    We report the measurement of the non-reactor environmental backgrounds and the detector response with the Indian Scintillator Matrix for Reactor Anti-Neutrinos (ISMRAN), which is $\sim$1 ton detector setup by volume, consisting of 10$\times$9 (10 rows and 9 columns) Plastic Scintillator Bars (PSBs) array at BARC, Mumbai, India. ISMRAN is an above-ground anti-neutrino (${\overline{\nu }}_{\mathrm{e}}$) experiment at very short baseline located at Dhruva research reactor facility. It is enclosed by a shielding made of 10 cm thick lead and 10 cm thick borated polyethylene to minimize the backgrounds and is mounted on a movable base structure, situated at $\sim$ 13 m away from the reactor core. These measurements are useful in the context of the ISMRAN detector setup that will be used to detect the reactor ${\overline{\nu }}_{\mathrm{e}}$ and measure its energy spectrum through the inverse beta decay (IBD) process. In this paper, we present the energy resolution model and energy non-linearity model of PSB and the cosmogenic muon-induced background, based on the sum of their energy depositions and number of hit bars. Reconstructed sum energy spectrum and number of hit bars distribution for ${}^{22}\mathrm{Na}$ radioactive source has been compared with Geant4 based Monte Carlo simulations. These experimentally measured results will be useful for discriminating the correlated and uncorrelated background events from the true IBD events in reactor ON and OFF conditions inside the reactor hall.

    ↳ physics.ins-dethep-exnucl-exPoS·0 citations
13. 13*

    Nature of $X(3872)$ in $B^0\to K^{0}X(3872)$ and $B^{+}\to K^{+}X(3872)$ decays

    Hao-Nan Wang🇨🇳 · Li-Sheng Geng🇨🇳 · Qian Wang🇨🇳 · Ju-Jun Xie🇨🇳

    We investigate the decays of $B^0\to K^{0}X(3872)$ and $B^{+}\to K^{+}X(3872)$ based on the picture where the $X(3872)$ resonance is strongly coupled to the $D{\bar{D}}^{\ast }+c.c.$ channel. In addition to the decay mechanism where the $X(3872)$ resonance is formed from the $c\bar{c}$ pair hadronization with the short-distance interaction, we have also considered the $D{\bar{D}}^{\ast }$ rescattering diagrams in the long-distance scale, where $D$ and ${\bar{D}}^{\ast }$ are formed from $c$ and $\bar{c}$ separately. Because of the difference of the mass thresholds of charged and neutral $D{\bar{D}}^{\ast }$ channels, and the rather narrow width of the $X(3872)$ resonance, at the $X(3872)$ mass, the loop functions of $D^0{\bar{D}}^{\ast 0}$ and $D^{+}{\bar{D}}^{\ast -}$ are much different. Taking this difference into account, the ratio of $\mathcal{B}[B^0\to K^{0}X(3872)]/\mathcal{B}[B^{+}\to K^{+}X(3872)]\simeq 0.5$ can be naturally obtained. Based on this result, we also evaluate the decay widths of $B_s^0\to \eta ({\eta }^{\prime })X(3872)$. It is expected that future experimental measurements of these decays can be used to elucidate the nature of the $X(3872)$ resonance.

    ↳ hep-phhep-exnucl-exnucl-thChin.Phys.Lett.(2023)·14 citations
14. 14*

    Charged-hadron production in $pp$, $p$+Pb, Pb+Pb, and Xe+Xe collisions at $\sqrt{s_{{}_{\text{NN}}}}=5$ TeV with the ATLAS detector at the LHC

    ATLAS Collaboration

    This paper presents measurements of charged-hadron spectra obtained in $pp$, $p$+Pb, and Pb+Pb collisions at $\sqrt{s}$ or $\sqrt{s_{{}_{\text{NN}}}}=5.02$ TeV, and in Xe+Xe collisions at $\sqrt{s_{{}_{\text{NN}}}}=5.44$ TeV. The data recorded by the ATLAS detector at the LHC have total integrated luminosities of 25 pb${}^{-1}$, 28 nb${}^{-1}$, 0.50 nb${}^{-1}$, and 3 $\mu$b${}^{-1}$, respectively. The nuclear modification factors $R_{p\text{Pb}}$ and $R_{\text{AA}}$ are obtained by comparing the spectra in heavy-ion and $pp$ collisions in a wide range of charged-particle transverse momenta and pseudorapidity. The nuclear modification factor $R_{p\text{Pb}}$ shows a moderate enhancement above unity with a maximum at $p_{\mathrm{T}}\approx 3$ GeV; the enhancement is stronger in the Pb-going direction. The nuclear modification factors in both Pb+Pb and Xe+Xe collisions feature a significant, centrality-dependent suppression. They show a similar distinct $p_{\mathrm{T}}$-dependence with a local maximum at $p_{\mathrm{T}}\approx 2$ GeV and a local minimum at $p_{\mathrm{T}}\approx 7$ GeV. This dependence is more distinguishable in more central collisions. No significant $|\eta |$-dependence is found. A comprehensive comparison with several theoretical predictions is also provided. They typically describe $R_{\text{AA}}$ better in central collisions and in the $p_{\mathrm{T}}$ range from about 10 to 100 GeV.

    ↳ hep-exnucl-exJHEP(2023)·61 citations
15. 15*

    Global constraint on the magnitude of anomalous chiral effects in heavy-ion collisions

    Wen-Ya Wu🇨🇳 · Qi-Ye Shou🇨🇳 · Panos Christakoglou🇳🇱 · Prottay Das🇮🇳 · Md. Rihan Haque🇵🇱 · Guo-Liang Ma🇨🇳 · Yu-Gang Ma🇨🇳 · Bedangadas Mohanty🇮🇳 · Chun-Zheng Wang🇨🇳 · Song Zhang🇨🇳 · Jie Zhao🇨🇳

    When searching for anomalous chiral effects in heavy-ion collisions, one of the most crucial points is the relationship between the signal and the background. In this letter, we present a simulation in a modified blast wave model at LHC energy, which can simultaneously characterize the majority of measurable quantities, in particular, the chiral magnetic effect (CME) and the chiral magnetic wave (CMW) observables. Such a universal description, for the first time, naturally and quantitatively unifies the CME and the CMW studies and brings to light the connection with the local charge conservation (LCC) background. Moreover, a simple phenomenological approach is performed to introduce the signals, aiming at quantifying the maximum allowable strength of the signals within experimental precision. Such a constraint provides a novel perspective to understand the experimental data and sheds new light on the study of anomalous chiral effects as well as charge dependent correlations.

    ↳ nucl-thnucl-exPRC(2023)·22 citations
16. 16*

    Quenching jets increases their flavor

    Chathuranga Sirimanna🇺🇸 · Ismail Soudi🇺🇸 · Gojko Vujanovic🇺🇸 · Wen-Jing Xing🇨🇳 · Shanshan Cao🇨🇳 · Abhijit Majumder🇺🇸

    The widespread notion that jets quenched in a Quark-Gluon-Plasma (QGP) are similar in their parton flavor composition to jets in vacuum is critically examined. We demonstrate that while the soft to semi-hard [low to intermediate transverse momentum ($p_T$)] sector of vacuum jets are predominantly bosonic i.e., composed of gluons, \emph{sufficiently} quenched jets can have an intermediate momentum sector that is predominantly fermionic, dominated by quarks and antiquarks. We demonstrate, using leading order perturbative QCD processes, that the rate of flavor conversion from a gluon traversing the QGP as part of a jet, to a quark or antiquark, versus the reverse process, grows steadily with falling $p_T$. Simple diagrammatic estimates are followed by a variety of realistic simulations in static media. The relation of this increase in flavor to the observed baryon enhancement at intermediate $p_T$ is studied in a fully realistic simulation.

    ↳ hep-phnucl-exnucl-thPRC(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.