Thu·Feb 28, 2019Thursday·February 28, 2019

1. 01*

   Exposing Novel Quark and Gluon Effects in Nuclei

   I. C. Cloët🇺🇸 · R. Dupré🇫🇷 · S. Riordan🇺🇸 · W. Armstrong🇺🇸 · J. Arrington🇺🇸 · W. Cosyn🇧🇪 · N. Fomin🇺🇸 · A. Freese🇺🇸 · S. Fucini🇮🇹 · D. Gaskell🇺🇸 · C. E. Keppel🇺🇸 · G. A. Miller🇺🇸 and 6 other authors

   The fundamental theory of the strong interaction -- quantum chromodynamics (QCD) -- provides the foundational framework with which to describe and understand the key properties of atomic nuclei. A deep understanding of the explicit role of quarks and gluons in nuclei remains elusive however, as these effects have thus far been well-disguised by confinement effects in QCD which are encapsulated by a successful description in terms of effective hadronic degrees of freedom. The observation of the EMC effect has provided an enduring indication for explicit QCD effects in nuclei, and points to the medium modification of the bound protons and neutrons in the nuclear medium. Understanding the EMC effect is a major challenge for modern nuclear physics, and several key questions remain, such as understanding its flavor, spin, and momentum dependence. This manuscript provides a contemporary snapshot of our understanding of the role of QCD in nuclei and outlines possible pathways in experiment and theory that will help deepen our understanding of nuclei in the context of QCD.

   nucl-exnucl-thJ.Phys.G(2019)·38 citations
2. 02*

   Measurement of the 235U(n,f) cross section relative to the 6Li(n,t) and 10B(n,alpha) standards from thermal to 170 keV neutron energy range at n_TOF

   S. Amaducci🇮🇹 · L. Cosentino🇮🇹 · M. Barbagallo🇮🇹 · N. Colonna🇮🇹 · A. Mengoni🇮🇹 · C. Massimi🇮🇹 · S. Lo Meo🇮🇹 · P. Finocchiaro🇮🇹 · O. Aberle🇨🇭 · J. Andrzejewski🇵🇱 · L. Audouin🇫🇷 · M. Bacak🇫🇷 and 109 other authors

   The 235U(n,f) cross section was measured in a wide energy range at n_TOF relative to 6Li(n,t) and 10B(n,alpha), with high resolution and in a wide energy range, with a setup based on a stack of six samples and six silicon detectors placed in the neutron beam. This allowed us to make a direct comparison of the reaction yields under the same experimental conditions, and taking into account the forward/backward emission asymmetry. A hint of an anomaly in the 10{\div}30 keV neutron energy range had been previously observed in other experiments, indicating a cross section systematically lower by several percent relative to major evaluations. The present results indicate that the evaluated cross section in the 9{\div}18 keV neutron energy range is indeed overestimated, both in the recent updates of ENDF/B-VIII.0 and of the IAEA reference data. Furthermore, these new high-resolution data confirm the existence of resonance-like structures in the keV neutron energy region. The new, high accuracy results here reported may lead to a reduction of the uncertainty in the 1{\div}100 keV neutron energy region. Finally, the present data provide additional confidence on the recently re-evaluated cross section integral between 7.8 and 11 eV.

   nucl-exhep-exEPJA(2019)·19 citations
3. 03*

   $\alpha$ and triton clustering in ${}^{35}$Cl

   Yasutaka Taniguchi🇯🇵

   Coupling of cluster and deformed structures are important for dynamics of nuclear structure. Threshold energy has been discussed to explain cluster structures coupling to deformed states but relation between threshold energy and excitation energy has open problems. Negative-parity superdeformed (SD) states were observed by a $\gamma$-spectroscopy experiment in ${}^{35}$Cl but its detailed structure is unclear. By analyzing coupling of cluster structures in deformed states and high-lying cluster states in ${}^{35}$Cl, cluster structures coupling to deformed states and excitation energy of high-lying cluster states are investigated. The antisymmetrized molecular dynamics (AMD) and the generator coordinate method (GCM) are used. An AMD wave function is a Slater determinant of Gaussian wave packets. By energy variational calculations with constraints on deformation and clustering, wave functions of deformed structures and $\alpha$- and $t$-cluster structures are obtained. Adopting those wave functions as GCM basis, wave functions of ground and excited states are calculated. Various deformed bands are obtained and predicted. A $K^{\pi }={\frac{1}{2}}^{-}$ deformed band, which corresponds to the observed SD band, dominates deformed structure and compact $\alpha$- and $t$-cluster structure components. Particle-hole configurations of the dominant components with deformed and cluster structures are similar. In high-lying states, almost pure $\alpha$- and $t$-cluster states are obtained in negative-parity states, and excitation energies of the $t$-cluster states are higher than those of $\alpha$-cluster states. In conclusions, particle-hole configurations of cluster structure with small intercluster distance are important for coupling to low-energy deformed states. Threshold energies reflect to excitation energies of high-lying almost pure cluster states.

   ↳ nucl-thnucl-exPRC(2019)·4 citations
4. 04*

   High luminosity fixed-target experiment at the LHC

   C. Hadjidakis🇫🇷 · S.J. Brodsky🇺🇸 · G. Cavoto🇮🇹 · C. Da Silva🇺🇸 · F. Donato🇮🇹 · M.G. Echevarria🇮🇹 · E.G. Ferreiro🇪🇸 · I. Hřivnáčová🇫🇷 · D. Kikola🇵🇱 · A. Klein🇺🇸 · A. Kurepin🇷🇺 · A. Kusina🇵🇱 and 21 other authors

   By extracting the beam with a bent crystal or by using an internal gas target, the multi-TeV proton and lead LHC beams allow one to perform the most energetic fixed-target experiments ever and to study $pp$, $p$d and $p$A collisions at $\sqrt{s_{NN}}=115$ GeV and Pb$p$ and PbA collisions at $\sqrt{s_{NN}}=72$ GeV with high precision and modern detection techniques. Such studies would address open questions in the domain of the nucleon and nucleus partonic structure at high-$x$, quark-gluon plasma and, by using longitudinally or transversally polarised targets, spin physics. In this paper, we will review the technical solutions to obtain a high-luminosity fixed-target experiment at the LHC and will discuss their possible implementations with the ALICE and LHCb detectors.

   ↳ hep-exnucl-exPoS(2019)·4 citations
5. 05*

   Ab initio calculations of 5H resonant states

   R. Lazauskas🇫🇷 · E. Hiyama🇯🇵 · J. Carbonell🇫🇷

   By solving the 5-body Faddeev-Yakubovsky equations in configuration space with realistic nuclear Hamiltonians we have studied the resonant states of ${}^5$H isotope. Two different methods, allowing to bypass the exponentially diverging boundary conditions, have been employed providing consistent results. The existence of ${}^5$H broad J${}^{\pi }$=1/2${}^{+}$,3/2${}^{+}$,5/2${}^{+}$ states as S-matrix poles has been confirmed and compared with the, also calculated, resonant states in ${}^4$H isotope. We have established that the positions of these resonances only mildly depend on the nuclear interaction model.

   ↳ nucl-thnucl-exphysics.comp-phPLB(2019)·25 citations
6. 06*

   Wide band spectroscopic response of monocrystallines to low dose neutron and gamma radiation

   Yossi Mosbacher🇮🇱 · Micha Weiss🇮🇱 · Hagar Landsman🇮🇱 · Nadav Priel🇮🇱 · Ilan Eliyahu🇮🇱 · Arik Kreisel🇮🇱 · Offir Ozeri🇮🇱 · David Hershkovich🇮🇱 · Ori Cheshnovsky🇮🇱 · Ranny Budnik🇮🇱

   We identify a number of crystalline structures with promising characteristics to serve as a detection medium for a novel Dark Matter (DM) detector with a low threshold energy. A detector of this kind can be specifically useful in application requiring the detection of nuclear recoils, such as in direct detection of low mass DM, coherent neutrino scattering and neutrons. We describe a broad band, high sensitivity optical setup designed and constructed for the purpose of this search and future investigations of specific crystals. We report on the fluorescent signals produced from exposure to low doses of neutrons and $\gamma$ rays and find potential targets in Quartz, Sapphire, LiF, CaF${}_2$ and BaF${}_2$. These crystals and specific signals will be the subject of further study to establish the various traits relevant for a full scale DM detector. In this paper we identify the most interesting signals that will be promoted to significantly more detailed studies, including their production mechanism.

   ↳ physics.ins-dethep-exnucl-ex4 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.