Thu·Dec 12, 2019Thursday·December 12, 2019

1. 01*

   Energy of the ${}^{229}$Th Nuclear Clock Isomer Determined by Absolute $\gamma$-ray Energy Difference

   A. Yamaguchi · H. Muramatsu🇺🇸 · T. Hayashi🇺🇸 · N. Yuasa · K. Nakamura · M. Takimoto · H. Haba🇯🇵 · K. Konashi · M. Watanabe🇯🇵 · H. Kikunaga · K. Maehata · N. Y. Yamasaki🇯🇵 · K. Mitsuda🇯🇵

   The low-lying isomeric state of ${}^{229}$Th provides unique opportunities for high-resolution laser spectroscopy of the atomic nucleus. We determine the energy of this isomeric state by taking the absolute energy difference between the excitation energy required to populate the 29.2-keV state from the ground-state and the energy emitted in its decay to the isomeric excited state. A transition-edge sensor microcalorimeter was used to measure the absolute energy of the 29.2-keV $\gamma$-ray. Together with the cross-band transition energy (29.2 keV$\to$ground) and the branching ratio of the 29.2-keV state measured in a recent study, the isomer energy was determined to be 8.30$\pm$0.92 eV. Our result is in agreement with latest measurements based on different experimental techniques, which further confirms that the isomeric state of ${}^{229}$Th is in the laser-accessible vacuum ultraviolet range.

   nucl-exphysics.atom-phPRL(2019)·52 citations
2. 02*

   Ab initio nuclear thermodynamics

   Bing-Nan Lu🇺🇸 · Ning Li🇺🇸 · Serdar Elhatisari🇹🇷 · Dean Lee🇺🇸 · Joaquín E. Drut🇺🇸 · Timo A. Lähde🇩🇪 · Evgeny Epelbaum🇩🇪 · Ulf-G. Meißner🇩🇪

   We propose a new Monte Carlo method called the pinhole trace algorithm for {\it ab initio} calculations of the thermodynamics of nuclear systems. For typical simulations of interest, the computational speedup relative to conventional grand-canonical ensemble calculations can be as large as a factor of one thousand. Using a leading-order effective interaction that reproduces the properties of many atomic nuclei and neutron matter to a few percent accuracy, we determine the location of the critical point and the liquid-vapor coexistence line for symmetric nuclear matter with equal numbers of protons and neutrons. We also present the first {\it ab initio} study of the density and temperature dependence of nuclear clustering.

   ↳ nucl-thcond-mat.stat-mechhep-latnucl-exPRL(2020)·62 citations
3. 03*

   Nucleon-to-meson transition distribution amplitudes in impact parameter space

   Bernard Pire🇫🇷 · Kirill Semenov-Tian-Shansky🇷🇺 · Lech Szymanowski🇵🇱

   Recent analyses of backward meson electroproduction support the validity of a collinear QCD factorization framework for these hard exclusive reactions. This opens a way to the extraction of nucleon-to-meson transition distribution amplitudes (TDAs) from the experimental data. Similarly to the generalized parton distributions, TDAs - after the Fourier transform in the transverse plane - carry valuable information on the transverse location of hadron constituents. We address the properties of integrated nucleon-to-meson TDAs in the impact parameter representation. We argue that the emerging picture provides an intuitive interpretation for the hadron structural information contained in nucleon-to-meson TDAs and allows to study diquark-quark contents of fast moving hadrons in the transverse plane.

   ↳ hep-phhep-exnucl-exnucl-thPoS(2019)·6 citations
4. 04*

   The STAR Event Plane Detector

   Joseph Adams🇺🇸 · Annika Ewigleben🇺🇸 · Sierra Garrett🇺🇸 · Wanbing He🇨🇳 · Te-Chuan Huang🇹🇼 · Peter M. Jacobs🇺🇸 · Xinyue Ju🇨🇳 · Michael A. Lisa🇺🇸 · Michael Lomnitz🇺🇸 · Robert Pak🇺🇸 · Rosi Reed🇺🇸 · Alexander Schmah🇺🇸 and 6 other authors

   The Event Plane Detector (EPD) is an upgrade detector to the STAR experiment at RHIC, designed to measure the pattern of forward-going charged particles emitted in a high-energy collision between heavy nuclei. It consists of two highly-segmented disks of 1.2-cm-thick scintillator embedded with wavelength-shifting fiber, coupled to silicon photomultipliers and custom electronics. We describe the general design of the device, its construction, and performance on the bench and in the experiment.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2020)·87 citations
5. 05*

   Low-energy neutron scattering on light nuclei and ${}^{19}$B as a ${}^{17}$B-$n$-$n$ three-body system in the unitary limit

   Jaume Carbonell🇫🇷 · Emiko Hiyama🇯🇵 · Rimantas Lazauskas🇫🇷 · F. Miguel Marqués🇫🇷

   We consider the evolution of the neutron-nucleus scattering length for the lightest nuclei. We show that, when increasing the number of neutrons in the target nucleus, the strong Pauli repulsion is weakened and the balance with the attractive nucleon-nucleon interaction results into a resonant virtual state in ${}^{18}$B. We describe ${}^{19}$B in terms of a ${}^{17}$B-$n$-$n$ three-body system where the two-body subsystems ${}^{17}$B-$n$ and $n$-$n$ are unbound (virtual) states close to the unitary limit. The energy of ${}^{19}$B ground state is well reproduced and two low-lying resonances are predicted. Their eventual link with the Efimov physics is discussed. This model can be extended to describe the recently discovered resonant states in ${}^{20,21}$B.

   ↳ nucl-thnucl-exquant-phSciPost Phys.Proc.(2020)·2 citations
6. 06*

   Fission of relativistic nuclei with fragment excitation and reorientation

   C.A. Bertulani🇺🇸 · Y. Kucuk🇹🇷 · R. Lozeva🇫🇷

   Experimental studies of fission induced in relativistic nuclear collisions show a systematic enhancement of the excitation energy of the primary fragments by a factor of ~ 2, before their decay by fission and other secondary fragments. Although it is widely accepted that by doubling the energies of the single-particle states may yield a better agreement with fission data, it does not prove fully successful, since it is not able to explain yields for light and intermediate mass fragments. State-of-the-art calculations are successful to describe the overall shape of the mass distribution of fragments, but fail within a factor of 2-10 for a large number of individual yields. Here, we present a novel approach that provides an account of the additional excitation of primary fragments due to final state interaction with the target. Our method is applied to the 238U + 208Pb reaction at 1 GeV/nucleon (and is applicable to other energies), an archetype case of fission studies with relativistic heavy ions, where we find that the large probability of energy absorption through final state excitation of giant resonances in the fragments can substantially modify the isotopic distribution of final fragments in a better agreement with data. Finally, we demonstrate that large angular momentum transfers to the projectile and to the primary fragments via the same mechanism imply the need of more elaborate theoretical methods than the presently existing ones.

   ↳ nucl-thnucl-exPRL(2020)·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.