Thu·Oct 24, 2019Thursday·October 24, 2019

1. 01*

   New evidence supporting the existence of the hypothetic X17 particle

   A.J. Krasznahorkay🇭🇺 · M. Csatlos🇭🇺 · L. Csige🇭🇺 · J. Gulyas🇭🇺 · M. Koszta🇭🇺 · B. Szihalmi🇭🇺 · J. Timar🇭🇺 · D.S. Firak🇭🇺 · A. Nagy🇭🇺 · N.J. Sas🇭🇺 · A. Krasznahorkay

   We observed electron-positron pairs from the electro-magnetically forbidden M0 transition depopulating the 21.01 MeV 0${}^{-}$ state in ${}^4$He. A peak was observed in their $e^{+}{e}^{-}$ angular correlations at 115${}^{\circ }$ with 7.2$\sigma$ significance, and could be described by assuming the creation and subsequent decay of a light particle with mass of $m_{\mathrm{X}}{c}^2$=16.84$\pm 0.16(stat)\pm 0.20(syst)$ MeV and ${\Gamma }_{\mathrm{X}}$= $3.9\times 10^{-5}$ eV. According to the mass, it is likely the same X17 particle, which we recently suggested [Phys. Rev. Lett. 116, 052501 (2016)] for describing the anomaly observed in ${}^8$Be.

   nucl-ex130 citations
2. 02*

   Measurement of 3He analyzing power for p-3He scattering using the polarized 3He target

   A. Watanabe🇯🇵 · S. Nakai🇯🇵 · K. Sekiguchi🇯🇵 · T. Akieda🇯🇵 · D. Etoh🇯🇵 · M. Inoue🇯🇵 · Y. Inoue · K. Kawahara🇯🇵 · H. Kon🇯🇵 · K. Miki🇺🇸 · T. Mukai🇯🇵 · D. Sakai🇯🇵 and 25 other authors

   Proton-3He scattering is one of the good probes to study the T=3/2 channel of three--nucleon forces. We have measured 3He analyzing powers for p-3He elastic scattering with the polarized 3He target at 70 and 100 MeV. The data are compared with the theoretical predictions based on the modern nucleon--nucleon potentials. Large discrepancies are found between the data and the calculations at the angles where the 3He analyzing power takes the minimum and maximum values, which are not explained by taking into account Delta-isobar degrees of freedom.

   nucl-exSciPost Phys.Proc.(2020)·2 citations
3. 03*

   Proton-induced reactions on Fe, Cu, & Ti from threshold to 55 MeV

   Andrew S. Voyles🇺🇸 · Amanda M. Lewis · Jonathan T. Morrell🇺🇸 · M. Shamsuzzoha Basunia · Lee A. Bernstein · Jonathan W. Engle · Stephen A. Graves · Eric F. Matthews

   Theoretical models often differ significantly from measured data in their predictions of the magnitude of nuclear reactions that produce radionuclides for medical, research, and national security applications. In this paper, we compare a priori predictions from several state-of-the-art reaction modeling packages (CoH, EMPIRE, TALYS, and ALICE) to cross sections measured using the stacked-target activation method. The experiment was performed using the LBNL 88-Inch Cyclotron with beams of 25 and 55 MeV protons on a stack of iron, copper, and titanium foils. 34 excitation functions were measured for 4 < Ep < 55 MeV, including the first measurement of the independent cross sections for natFe(p,x) 49,51Cr, 51,52m,52g,56Mn, and 58m,58gCo. All of the models failed to reproduce the isomer-to-ground state ratio for reaction channels at compound and pre-compound energies, suggesting issues in modeling the deposition or distribution of angular momentum in these residual nuclei.

   nucl-exEPJA(2021)·8 citations
4. 04*

   The Onset of Jet Quenching Phenomenon

   M. T. AlFiky🇪🇬 · O. T. ElSherif🇪🇬 · A. M. Hamed🇪🇬

   The aim of this study is to set a baseline for the jet quenching measurements of the Quark Gluon Plasma (QGP) formed in the large system size Nucleus-Nucleus (A-A) at top central collisions, via studying simulated small system size, Nucleon-Nucleon (N-N) collisions. The proton-proton (p-p) collisions were simulated using PYTHIA, at center of mass energies $\sqrt{s_{{}_{NN}}}=200$ $GeV$ and $\sqrt{s_{{}_{NN}}}=13$ $TeV$ corresponding to the available energies at the current collider experiments; the Relativistic Heavy Ion Collider (RHIC), and the Large Hadron Collider (LHC). At both energies, the two-particle azimuthal correlation functions have been considered, and the yield associated with the high transverse momentum ($p_{{}_T}$) particles were extracted at its near-side ($\Delta \varphi \approx 0$) and away-side ($\Delta \varphi \approx \pi$) at mid pseudo rapidity ($|\eta |\le 2$). The ratio between the near-side yields in the high multiplicity events to these of the low multiplicity events ($I_{{}_{HL}}^{{}^N}$), as well as, the ratio of the away-side yields ($I_{{}_{HL}}^{{}^A}$) were calculated at both energies as a function of the hadron fractional energy $z_{{}_T}$ of the high-$p_{{}_T}$ particle. At both energies, the values of $I_{{}_{HL}}^{{}^N}$ and $I_{{}_{HL}}^{{}^A}$ were less than unity, and of trivial dependence on $z_{{}_T}$. The values of $I_{{}_{HL}}^{{}^A}$ are always less than these of $I_{{}_{HL}}^{{}^N}$ at the same multiplicity and energy, and both quantities show a pattern of systematic decreases with the multiplicity. Such multiplicity dependence cannot be used neither to exclude the jet quenching nor to prove it in the high multiplicity events in p-p collisions, as the suppressions have been found at both sides, near and away of the high-$p_{{}_T}$ particle.

   ↳ hep-exnucl-exJETP Lett.(2020)·2 citations
5. 05*

   Spinodal Instability at the Onset of Collective Expansion in Nuclear Collisions

   Pawel Danielewicz🇺🇸 · Hao Lin (Michigan State U)🇺🇸 · Jirina R. Stone (U Oxford/U Tennessee)🇬🇧 · Yoritaka Iwata (Kansai U)🇯🇵

   Using transport theory to model central Au + Au collisions in the energy region of 20 - 110 MeV/u, at impact parameters b <= 5 fm, we predict a measurable impact of spinoidal instability as the collective expansion sets in with energy. Two transport models are employed, the pBUU model, solving a Boltzmann-Uehling-Uhlenbeck equation, and the Brownian Motion (BM) model, solving a set of Langevin equations to describe the motion of individual nucleons in a noisy nuclear medium. We find without ambiguity, for the first time, that a combination of delayed equilibration, onset of collective expansion and the spinodal instability produces a pair of transient ring structures, made of the projectile and target remnants, with spectator nucleons predicted to end in the entities reminiscent of stones in jewelry, on the rings. The ring structures, calculated in the configuration space and mapped onto the velocity space, could be detected in experimental collective flow data.

   ↳ nucl-thnucl-exPLB(2020)·4 citations
6. 06*

   Ground state properties and potential energy surfaces of ${}^{270}$Hs from multidimensionally-constrained relativistic mean field model

   Xu Meng🇨🇳 · Bing-Nan Lu🇺🇸 · Shan-Gui Zhou🇨🇳

   We study the ground state properties, potential energy curves and potential energy surfaces of the superheavy nucleus ${}^{270}$Hs by using the multidimensionally-constrained relativistic mean-field model with the effective interaction PC-PK1. The binding energy, size and shape as well as single particle shell structure corresponding to the ground state of this nucleus are obtained. ${}^{270}$Hs is well deformed and exhibits deformed doubly magic feature in the single neutron and proton level schemes. One-dimensional potential energy curves and two-dimensional potential energy surfaces are calculated for ${}^{270}$Hs with various spatial symmetries imposed. We investigate in detail the effects of the reflection asymmetric and triaxial distortions on the fission barrier and fission path of ${}^{270}$Hs. When the axial symmetry is imposed, the reflection symmetric and reflection asymmetric fission barriers both show a double-hump structure and the former is higher. However, when triaxial shapes are allowed the reflection symmetric barrier is lowered very much and then the reflection symmetric fission path becomes favorable.

   ↳ nucl-thnucl-exSCPMA(2020)·34 citations
7. 07*

   Unified description of hadron yield ratios from dynamical core-corona initialization

   Yuuka Kanakubo🇯🇵 · Yasuki Tachibana🇺🇸 · Tetsufumi Hirano🇯🇵

   We develop the dynamical core-corona initialization framework as a phenomenological description of the formation of quark gluon plasma (QGP) fluids in high-energy nuclear collisions. Using this framework, we investigate the fraction of the fluidized energy to the total energy and strange hadron yield ratios as functions of multiplicity and scrutinize the multiplicity scaling of hadron yield ratios recently reported by the ALICE Collaboration. Our results strongly indicate that the QGP fluids are partly formed even at the averaged multiplicity for nonsingle diffractive p+p events.

   ↳ nucl-thhep-phnucl-exPRC(2020)·74 citations
8. 08*

   Sub Coulomb barrier d+${}^{208}$Pb scattering in the time-dependent basis function approach

   Peng Yin🇨🇳 · Weijie Du🇺🇸 · Wei Zuo🇨🇳 · Xingbo Zhao🇨🇳 · James P. Vary🇺🇸

   We employ the non-perturbative time-dependent basis function (tBF) approach to study the scattering of the deuteron on ${}^{208}$Pb below the Coulomb barrier. We obtain the bound and discretized scattering states of the projectile, which form the basis representation of the tBF approach, by diagonalizing a realistic Hamiltonian in a large harmonic oscillator basis. We find that the higher-order inelastic scattering effects are noticeable for sub barrier scatterings with the tBF method. We have successfully reproduced experimental sub Coulomb barrier elastic cross section ratios with the tBF approach by considering only the electric dipole ($E1$) component of the Coulomb interaction between the projectile and the target during scatterings. We find that the correction of the polarization potential to the Rutherford trajectory is dominant in reproducing the data at very low bombarding energies, whereas the role of internal transitions of the deuteron projectile induced by the $E1$ interaction during the scattering becomes increasingly significant at higher bombarding energies.

   ↳ nucl-thnucl-exJ.Phys.G(2022)·9 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.