Fri·Jul 15, 2022Friday·July 15, 2022

1. 01*

   Measurement of sequential ${\rm Y}$ suppression in Au+Au collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}$ = 200 GeV with the STAR experiment

   STAR Collaboration: B. E. Aboona · J. Adam · L. Adamczyk · J. R. Adams · I. Aggarwal · M. M. Aggarwal · Z. Ahammed · D. M. Anderson · E. C. Aschenauer · J. Atchison · V. Bairathi · W. Baker and 361 other authors

   We report on measurements of sequential ${\rm Y}$ suppression in Au+Au collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}$ = 200 GeV with the STAR detector at the Relativistic Heavy Ion Collider (RHIC) through both the dielectron and dimuon decay channels. In the 0-60% centrality class, the nuclear modification factors ($R_{\mathrm{AA}}$), which quantify the level of yield suppression in heavy-ion collisions compared to $p$+$p$ collisions, for ${\rm Y}$(1S) and ${\rm Y}$(2S) are $0.40\pm 0.03\text{(stat.)}\pm 0.03\text{(sys.)}\pm 0.09\text{(norm.)}$ and $0.26\pm 0.08\text{(stat.)}\pm 0.02\text{(sys.)}\pm 0.06\text{(norm.)}$, respectively, while the upper limit of the ${\rm Y}$(3S) $R_{\mathrm{AA}}$ is 0.17 at a 95% confidence level. This provides experimental evidence that the ${\rm Y}$(3S) is significantly more suppressed than the ${\rm Y}$(1S) at RHIC. The level of suppression for ${\rm Y}$(1S) is comparable to that observed at the much higher collision energy at the Large Hadron Collider. These results point to the creation of a medium at RHIC whose temperature is sufficiently high to strongly suppress excited ${\rm Y}$ states.

   nucl-exnucl-thPRL(2023)·52 citations
2. 02*

   Observation of azimuth-dependent suppression of hadron pairs in electron scattering off nuclei

   S.J. Paul🇺🇸 · S. Moran🇺🇸 · M. Arratia🇺🇸 · A. El Alaoui🇨🇱 · H. Hakobyan🇨🇱 · W. Brooks🇨🇱 · M.J. Amaryan🇺🇸 · W.R. Armstrong🇺🇸 · H. Atac🇺🇸 · L. Baashen🇺🇸 · N.A. Baltzell🇺🇸 · L. Barion🇮🇹 and 133 other authors

   We present the first measurement of di-hadron angular correlations in electron-nucleus scattering. The data were taken with the CLAS detector and a 5.0 GeV electron beam incident on deuterium, carbon, iron, and lead targets. Relative to deuterium, the nuclear yields of charged-pion pairs show a strong suppression for azimuthally opposite pairs, no suppression for azimuthally nearby pairs, and an enhancement of pairs with large invariant mass. These effects grow with increased nuclear size. The data are qualitatively described by the GiBUU model, which suggests that hadrons form near the nuclear surface and undergo multiple-scattering in nuclei. These results show that angular correlation studies can open a new way to elucidate how hadrons form and interact inside nuclei

   nucl-exPRL(2022)·11 citations
3. 03*

   Isoscalar Giant Resonances: Experimental Studies

   Umesh Garg🇺🇸

   Giant resonances--highly collective, high-frequency oscillations of the atomic nucleus--are the focus of this chapter. We discuss the isoscalar excitations, where the protons and neutrons oscillate in phase, up to angular-momentum transfers $L$ = 3. The procedures of experiments and data analysis employed in extracting the strength distributions associated with these resonances are discussed. The experimentally extracted strength distributions are presented, along with information on the properties of these resonances available to date. The effect of deformation of the nuclear ground state on the resonance strength distributions is discussed. Furthermore, the exciting opportunities being opened with the current and future availability of rare isotope beams the world over are expounded.

   nucl-exnucl-th2 citations
4. 04*

   Particle Physics Readout Electronics and Novel Detector Technologies for Neutron Science

   Thomas Block · Markus Gruber🇩🇪 · Saime Gurbuz · Jochen Kaminski🇩🇪 · Michael Lupberger🇩🇪 · Divya Pal🇬🇷 · Laura Rodriguez Gomez · Patrick Schwaebig🇩🇪 · Klaus Desch🇩🇪

   Traditional thermal neutron detectors are based on Helium-3 as conversion and detection material due to its large neutron cross-section. In light of the upgrade and construction of several neutron scattering facilities such as the European Spallation Source (ESS) and a simultaneous shortage of Helium-3, new detection technologies have been introduced. The most prominent one is to use solid converts with a large thermal neutron cross-section such as Gadolinium and Boron. Those materials emit charged particles when hit by a neutron. The technique then relies on detection and/or tracking of the charged particle, as in detectors of particle physics. At the same time, this requires an increase of the readout channels by an order of magnitude with the advantage of also increasing the position resolution by the same amount compared to traditional neutron detectors. A prime example is the Gadolinium Gas Electron Multiplier (GdGEM) detector for the NMX instrument at ESS jointly developed by the CERN Gaseous Detector Group and the ESS Detector Group. In this contribution, some of our efforts to transfer particle physics detectors and readout electronics to neutron science will be presented. We employed the VMM3a chip, originally designed for the ATLAS New Small Wheel upgrade, to read out a GEM-based neutron detector. The Timepix3 chip is employed in a neutron Time Projection Chamber as well as to read out a neutron-sensitive Micro-Channel Plate detector. Those readout chips are integrated into the Scalable Readout System of the RD51 collaboration.

   ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2023)·1 citation
5. 05*

   Dynamical Pair Production at Sub-Barrier Energies for Light Nuclei

   T. Settlemyre🇺🇸 · H. Zheng🇨🇳 · A. Bonasera🇺🇸

   In the collision of two heavy ions, the strong repulsion coming from the Coulomb field is enough to produce $e^{+}{e}^{-}$ pair(s) from vacuum fluctuations. The energy is provided by the kinetic energy of the ions and the Coulomb interaction at the production point. If, for instance, the electron is located at the center of mass (C.M.) of the two ions moving along the \emph{z}-axis, and the positron is at a distance \emph{x} from the electron, the ions can be accelerated towards each other since the Coulomb barrier is lowered by the presence of the electron. This screening results in an increase in the kinetic energy of the colliding ions and may result in an increase in the fusion probability of light ions above the adiabatic limit.

   ↳ nucl-thnucl-exParticles(2022)·3 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.