Mon·Aug 5, 2019Monday·August 5, 2019

1. 01*

   Neutron DVCS Measurements with BONuS12 in CLAS12

   M. Hattawy🇺🇸 · M. Amaryan🇺🇸 · S. Bültmann🇺🇸 · G. Dodge🇺🇸 · N. Dzbenski🇺🇸 · C. Hyde🇺🇸 · S. Kuhn🇨🇭 · D. Payette🇺🇸 · J. Poudel🇺🇸 · L. Weinstein🇺🇸 · R. Dupré🇫🇷 · M. Guidal🇫🇷 and 18 other authors

   The three-dimensional picture of quarks and gluons in the nucleon is set to be revealed through deeply virtual Compton scattering (DVCS). With the absence of a free neutron target, the deuterium target represents the simplest nucleus to be used to probe the internal 3D partonic structure of the neutron. We propose here to measure the beam spin asymmetry (BSA) in incoherent neutron DVCS together with the approved E12-06-113 experiment (BONuS12) within the run group F, using the same beam time, simply with addition of beam polarization. The DVCS BSA on the quasi-free neutron will be measured in a wide range of kinematics by tagging the scattered electron and the real photon final state with the spectator proton. We will also measure BSA with all final state particles detected including the struck neutron. The proposed measurements is complementary to the approved CLAS12 experiment E12-11-003, which will also measure the quasi-free neutron DVCS by detecting the scattered neutron, but not the spectator proton. Indeed, besides providing more data for neutron DVCS, this experiment will allow a comparison of the measurement of the BSA of neutron DVCS from the approved E12-11-003 with the measurements using the two methods proposed herein. This comparison will help to understand the impact of nuclear effects, such as the final state interactions (FSI) and Fermi motion on the measurement of the neutron DVCS.

   nucl-ex3 citations
2. 02*

   Toward a reliable description of $(p,pN)$ reactions in the distorted-wave impulse approximation

   Nguyen Tri Toan Phuc🇻🇳 · Kazuki Yoshida🇯🇵 · Kazuyuki Ogata🇯🇵

   Background: Proton-induced nucleon knockout $(p,pN)$ reactions have been successfully used to study the single-particle nature of stable nuclei in normal kinematics with the distorted-wave impulse approximation (DWIA) framework. Recently, these reactions have been applied to rare-isotope beams at intermediate energies in inverse kinematics to study the quenching of spectroscopic factors. Purpose: Our goal is to investigate the effects of various corrections and uncertainties within the standard DWIA formalism on the $(p,pN)$ cross sections. The consistency of the extracted reduction factors between DWIA and other methods is also evaluated. Method: We analyze the $(p,2p)$ and $(p,pn)$ reactions data measured at the R${}^3$B/LAND setup at GSI for carbon, nitrogen, and oxygen isotopes in the incident energy range of 300--450 MeV/u. Cross sections and reduction factors are calculated by using the DWIA method. The transverse momentum distribution of the ${}^{12}$C($p$,$2p$)${}^{11}$B reaction is also investigated. Results: We have found that including the nonlocality corrections and the Møller factor affects the cross sections considerably. The proton-neutron asymmetry dependence of reduction factors extracted by the DWIA calculation is very weak and consistent with those given by other reaction methods and \textit{ab initio} structure calculations. Conclusions: The results found in this work provide a detailed investigation of the DWIA method for $(p,pN)$ reactions at intermediate energies. They also suggest that some higher-order effects, which is essential for an accurate cross-section description at large recoil momentum, is missing in the current DWIA and other reaction models.

   ↳ nucl-thnucl-exPRC(2019)·19 citations
3. 03*

   Jet overlap in heavy ion collisions at LHC energies and its consequences on jet shape

   Iurii Karpenko🇫🇷 · Joerg Aichelin🇫🇷 · Pol Gossiaux🇫🇷 · Martin Rohrmoser🇵🇱 · Klaus Werner🇫🇷

   Central lead-lead collisions at the LHC energies may pose a particular challenge for jet identification as multiple jets are produced per each collision event. We simulate the jet evolution in central Pb-Pb events at $\sqrt{s_{\mathrm{NN}}}=2.76$ GeV collision energy with EPOS3 initial state, which typically contains multiple hard scatterings in each event. Therefore the partons from different jets have a significant chance to overlap in momentum space. We find that 30% of the jets with $p_{\perp }>50$ GeV, identified by the standard anti-$k_{\perp }$ jet finding algorithm with jet cone size R=0.3, contain `intruder' particles from overlapping generator-level jets. This fraction increases with increasing beam energy and increasing R. The reconstructed momentum of the jet differs from that of the modelled jet by the loss due to jet partons which are outside of the jet cone and by the gain due to intruder partons. The sum of both may be positive or negative. These intruder partons particularly affect the radial jet momentum distribution because they contribute mostly at large angles $\Delta r$ with respect to the jet centre. The study stresses the importance of the jet overlap effect emerging in central lead-lead collisions at the LHC energies, while being negligible in peripheral PbPb or $p$Pb/$pp$ collisions.

   ↳ nucl-thhep-phnucl-exPRC(2020)·0 citations
4. 04*

   An Associated Particle Imaging System for Soil-Carbon Measurements

   Mauricio Ayllon Unzueta · Eoin Brodie · Craig Brown · Cristina Castanha · Charles Gary · Caitlin Hicks Pries · William Larsen · Bernhard Ludewigt🇺🇸 · Andrew Rosenstrom · Arun Persaud🇺🇸

   We present first results from experimental data showing the capabilities of an Associated Particle Imaging system to measure carbon in soil and other elements. Specifically, we present results from a pre-mixed soil sample containing pure sand (SiO${}_2$) and 4% carbon by weight. Because the main isotopes of all those three elements emit characteristic high-energy gamma rays following inelastic neutron scattering, it is possible to measure their distribution with our instrument. A 3D resolution of several centimeters in all dimensions has been demonstrated.

   ↳ physics.ins-detnucl-exphysics.app-phProc.SPIE Int.Soc.Opt.Eng.(2019)·0 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.