Mon·Jun 27, 2022Monday·June 27, 2022

1. 01*

   First measurement of polarisation transfer $C_{x^{\prime }}^n$ in deuteron photodisintegration

   M. Bashkanov🇬🇧 · D.P. Watts🇬🇧 · S.J.D. Kay🇨🇦 · S. Abt🇨🇭 · P. Achenbach🇩🇪 · P. Adlarson🇩🇪 · F. Afzal🇩🇪 · Z. Ahmed🇨🇦 · C.S. Akondi🇺🇸 · J.R.M. Annand🇬🇧 · H.J. Arends🇩🇪 · R. Beck🇩🇪 and 57 other authors

   A first measurement of the polarisation transfer from a circularly-polarised photon to the final state neutron ($C_{x^{\prime }}^n$) in deuterium photodisintegration has been carried out. This quantity is determined over the photon energy range 370~--~700~MeV and for neutron centre-of-mass breakup angles $\sim 45-120^{\circ }$. The polarisation of the final state neutrons was determined by an ancillary large-acceptance nucleon polarimeter, surrounding a cryogenic liquid deuterium target within the Crystal Ball detector at MAMI. The polarimeter characterised $(n,p)$ charge exchange of the ejected neutrons to determine their polarisation. The new $C_{x^{\prime }}^n$ data are also compared to a theoretical model based on nucleonic and nucleon resonance degrees of freedom constrained by the current world-database of deuterium photodisintegration measurements. Structures in $C_{x^{\prime }}^n$ observed in the region of the $d^{\ast }(2380)$ could not be explained by conventional models of deuteron photodisintegration.

   nucl-exPLB(2023)·8 citations
2. 02*

   Analysis of one-neutron transfer reaction in ${}^{18}$O + ${}^{76}$Se collision at 275 MeV

   I. Ciraldo🇮🇹 · F. Cappuzzello🇮🇹 · M. Cavallaro🇮🇹 · D. Carbone🇮🇹 · S. Burrello🇩🇪 · A. Spatafora🇮🇹 · A. Gargano🇮🇹 · G. De Gregorio🇮🇹 · R. I. Magaña Vsevolodovna🇮🇹 · L. Acosta🇲🇽 · C. Agodi🇮🇹 · P. Amador-Valenzuela🇧🇷 and 36 other authors

   Purpose: We want to analyze transitions to low-lying excited states of the residual and ejectile nuclei in the 76Se(18O, 17O) 77Se one-neutron stripping reaction at 275-MeV incident energy and determine the role of single-particle and core excitation in the description of the measured cross sections. In addition, we explore the sensitivity of the calculated cross section to different nuclear structure models. Methods: The excitation energy spectrum and the differential cross-section angular distributions are measured using the MAGNEX large acceptance magnetic spectrometer for the detection of the ejectiles and the missing mass technique for the reconstruction of the reaction kinematics. The data are compared with calculations based on distorted-wave Born approximation, coupled-channels Born approximation, and coupled reaction channels adopting spectroscopic amplitudes for the projectile and target overlaps derived by large-scale shell-model calculations and interacting boson-fermion model. Results: Peaks in the energy spectra corresponding to groups of unresolved transitions to 77Se and 17O are identified. The experimental cross sections are extracted and compared to theoretical calculations. A remarkable agreement is found, without using any scaling factors, demonstrating that the adopted models for nuclear structure and reaction take into account the relevant aspects of the studied processes. The main transitions which contribute to the cross section of each peak are identified.

   nucl-exnucl-thPRC(2022)·34 citations
3. 03*

   Photoproduction of $J/\psi$ in d+Au ultraperipheral collisions at the BNL Relativistic Heavy Ion Collider

   V. Guzey (St. Petersburg, INP)🇷🇺 · E. Kryshen (St. Petersburg, INP)🇷🇺 · M. Strikman (Penn State U.)🇺🇸 · M. Zhalov (St. Petersburg, INP)🇷🇺

   We argue that the STAR data on $J/\psi$ photoproduction in $d+Au$ ultraperipheral collisions (UPCs) at the momentum transfer $t\ne 0$ primarily probes elastic and possibly nucleon-dissociative $J/\psi$ photoproduction on quasi-free nucleons, while being essentially insensitive to expectedly weak nuclear modifications of the gluon distribution in the deuteron. Analyzing the STAR detector capabilities for selection of UPC events, we explore the possibility that the contribution of nucleon-dissociative $J/\psi$ photoproduction is negligibly small and obtain a very good description of the $t$ dependence of the STAR total cross section.

   ↳ hep-phhep-exnucl-exPRC(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.