Thu·Jul 26, 2018Thursday·July 26, 2018

1. 01*

   Determination of the polarization observables $C_x$, $C_z$, and $P$ for the $\vec{\gamma }d\to K^0\Lambda (p)$ reaction

   Colin Gleason🇺🇸 · Yordanka Ilieva🇺🇸

   Many excited nucleon states ($N^{\ast }$s) predicted by quark models, but not observed in $\pi N$ channels, are expected to couple strongly to kaon--hyperon ($KY$) channels. While in the last decade data have been published for $KY$ photoproduction off the proton, data off the neutron are scarce. In this paper we present preliminary results for the polarization observables $P$, $C_x$, and $C_z$ for the reaction $\gamma d\to K^0\Lambda (p)$, where $(p)$ denotes the spectator proton. The observables cover photon energies, $E_{\gamma }$, between 0.9 GeV and 2.6 GeV and kaon center-of-mass angles, cos${\theta }_{K^0}^{CM}$, between $-0.9$ and 1. The data were collected in experiment E06-103 (g13) with the CLAS detector at the Thomas Jefferson National Accelerator Facility using a circularly-polarized photon beam and an unpolarized liquid deuterium target. We also discuss the effect of neutron binding on the observables. Our study is part of a broader effort by the g13 group to provide cross sections and polarization observables for meson photoproduction off the neutron and is expected to have a significant impact on the $N^{\ast }$ research.

   nucl-ex0 citations
2. 02*

   High-resolution hypernuclear spectroscopy at Jefferson Lab, Hall A

   Jefferson Lab Hall A Collaboration: F. Garibaldi🇮🇹 · A. Acha🇺🇸 · P. Ambrozewicz🇺🇸 · K.A. Aniol🇺🇸 · P. Beturin🇺🇸 · H. Benaoum🇺🇸 · J. Benesch🇺🇸 · P.Y. Bertin🇫🇷 · K.I. Blomqvist🇩🇪 · W.U. Boeglin🇺🇸 · H. Breuer🇺🇸 · P. Brindza🇺🇸 and 87 other authors

   The experiment E94-107 in Hall A at Jefferson Lab started a systematic study of high resolution hypernuclear spectroscopy in the 0p-shell region of nuclei such as the hypernuclei produced in electroproduction on 9Be, 12C and 16O targets. In order to increase counting rates and provide unambiguous kaon identification two superconducting septum magnets and a ring-imaging Cherenkov detector were added to the Hall A standard equipment. The high-quality beam, the good spectrometers and the new experimental devices allowed us to obtain very good results. For the first time, measurable strength with sub-MeV energy resolution was observed for the core-excited states of Lambda 12B. A high-quality Lambda 16N hypernuclear spectrum was likewise obtained. A first measurement of the Lambda binding energy for Lambda 16N, calibrated against the elementary reaction on hydrogen, was obtained with high precision, 13.76 +/- 0.16 MeV. Similarly, the first Lambda 9Li hypernuclear spectrum shows general agreement with theory (distorted-wave impulse approximation with the SLA and BS3 electroproduction models and shell-model wave functions). Some disagreement exists with respect to the relative strength of the states making up the first multiplet. A Lambda separation energy of 8.36 MeV was obtained, in agreement with previous results. It has been shown that the electroproduction of hypernuclei can provide information complementary to that obtained with hadronic probes and the gamma-ray spectroscopy technique.

   nucl-exnucl-thPRC(2019)·32 citations
3. 03*

   Measurements of the chiral magnetic effect in Pb--Pb collisions with ALICE

   Md. Rihan Haque (for the ALICE Collaboration)

   We present the measurement of the charge-dependent 3-particle azimuthal correlation for unidentified charged particles in Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV in ALICE. The results are compared with corresponding results from Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV. We observe no significant difference in the charge-sensitive 3-particle correlator (${\gamma }_{112}$) between the two collision energies. Charged-dependent mixed-harmonic correlator (${\gamma }_{132}$) is also presented and compared with the predictions from a blast-wave model incorporating local charge conservation.

   ↳ hep-exnucl-exNPA(2019)·11 citations
4. 04*

   Event-shape- and multiplicity-dependent identified particle production in pp collisions at 13 TeV with ALICE at the LHC

   Gyula Bencedi (for the ALICE Collaboration)🇭🇺

   Multiplicity-dependent measurements of identified particle production led to the discovery of collective-like behavior in pp collisions at the LHC. Better understanding of the effects attributed to well-understood physics, like multiple hard scatterings, is required to establish whether this behaviour is truly collective in origin. Experimentally, those effects can be controlled using event shapes, like transverse spherocity, which allows the classification of pp collisions either as jetty or isotropic events. The transverse momentum ($p_{\mathrm{T}}$) spectra of light-flavor hadrons in pp collisions measured over a broad range provide important input to study particle production mechanisms in the soft and hard scattering regimes of the QCD. In this work, they are used to perform a comprehensive study as a function of the event multiplicity, collision energy, and event shapes. The proton-to-pion and kaon-to-pion particle ratios as a function of $p_{\mathrm{T}}$ are also reported and the results compared to QCD-inspired models.

   ↳ hep-exnucl-exNPA(2019)·18 citations
5. 05*

   Cosmic Ray Muon Radiography Applications in Safeguards and Arms Control

   J. Matthew Durham🇺🇸

   Muons are the most penetrating radiographic probe that exists today. These elementary particles possess a unique combination of physical properties that allows them to pass through dense, heavily shielded objects that are opaque to typical photon/neutron probes, and emerge with useful radiographic information on the object'sinternal substructure. Interactions of cosmic rays in the Earth's upper atmosphere provide a constant, natural source of muons that can be used for passive interrogation, eliminating the need for artificial sources of radiation. These proceedings discuss specific applications of muon radiography in nuclear safeguards and arms control treaty verification.

   ↳ physics.soc-phnucl-exphysics.ins-det1 citation

* 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.