Tue·Aug 16, 2022Tuesday·August 16, 2022

1. 01*

   A new study of the $N=32$ and $N=34$ shell gap for Ti and V by the first high-precision MRTOF mass measurements at BigRIPS-SLOWRI

   S. Iimura · M. Rosenbusch🇩🇪 · A. Takamine · Y. Tsunoda🇯🇵 · M. Wada🇵🇱 · S. Chen🇨🇳 · D. S. Hou · W. Xian · H. Ishiyama · S. Yan · P. Schury🇯🇵 · H. Crawford🇺🇸 and 25 other authors

   The atomic masses of ${}^{55}$Sc, ${}^{56,58}$Ti, and ${}^{56-59}$V have been determined using the high-precision multi-reflection time-of-flight technique. The radioisotopes have been produced at RIKEN's RIBF facility and delivered to the novel designed gas cell and multi-reflection system (ZD MRTOF), which has been recently commissioned downstream of the ZeroDegree spectrometer following the BigRIPS separator. For ${}^{56,58}$Ti and ${}^{56-59}$V the mass uncertainties have been reduced down to the order of $10\mathrm{keV}$, shedding new light on the $N=34$ shell effect in Ti and V isotopes by the first high-precision mass measurements of the critical species ${}^{58}$Ti and ${}^{59}$V. With the new precision achieved, we reveal the non-existence of the $N=34$ empirical two-neutron shell gaps for Ti and V, and the enhanced energy gap above the occupied $\nu p_{3/2}$ orbit is identified as a feature unique to Ca. We perform new Monte Carlo shell model calculations including the $\nu d_{5/2}$ and $\nu g_{9/2}$ orbits and compare the results with conventional shell model calculations, which exclude the $\nu g_{9/2}$ and the $\nu d_{5/2}$ orbits. The comparison indicates that the shell gap reduction in Ti is related to a partial occupation of the higher orbitals for the outer two valence neutrons at $N=34$.

   nucl-exPRL(2023)·27 citations
2. 02*

   Fast- and thermal-neutron detection with common NaI(Tl) detectors

   Guntram Pausch · Achim Kreuels · Falko Scherwinski · Yong Kong🇨🇳 · Mathias Kuester · Ralf Lentering · Andreas Wolf🇩🇪 · Juergen Stein

   Radionuclide Identification Devices (RIDs) or Backpack Radiation Detection Systems (BRDs) are often equipped with NaI(Tl) detectors. We demonstrate that such instruments could be provided with reasonable thermal- and fast-neutron sensitivity by means of an improved and sophisticated processing of the digitized detector signals: Fast neutrons produce nuclear recoils in the scintillation crystal. Corresponding signals are detectible and can be distinguished from that of electronic interactions by pulse-shape discrimination (PSD) techniques as used in experiments searching for weakly interacting massive particles (WIMPs). Thermal neutrons are often captured in iodine nuclei of the scintillator. The gamma-ray cascades following such captures comprise a sum energy of almost 7 MeV, and some of them involve isomeric states leading to delayed gamma emissions. Both features can be used to distinguish corresponding detector signals from responses to ambient gamma radiation. The experimental proof was adduced by offline analyses of pulse records taken with a commercial RID. An implementation of such techniques in commercial RIDs is feasible.

   ↳ physics.ins-detnucl-exphysics.app-phphysics.geo-ph+10 citations
3. 03*

   There and Sharp Again: The Circle Journey of Nucleons and Energy Deposition

   Giuliano Giacalone🇩🇪

   A central question in high-energy nuclear phenomenology is how the geometry of the quark-gluon plasma (QGP) formed in relativistic nuclear collisions is precisely shaped. In our understanding of such processes, two features are especially crucial for the determination of the QGP geometry, respectively, the nucleon size and the energy deposition scheme. This contribution reports on the (circular) evolution of such features in state-of-the-art model incarnations of heavy-ion collisions over the past seven years. Ideas for future directions of investigation are pointed out.

   ↳ nucl-thhep-exhep-phnucl-ex14 citations
4. 04*

   Testing the collectivity in large and small colliding systems with test particles

   Han-Sheng Wang🇨🇳 · Guo-Liang Ma🇨🇳

   We propose a test-particle method to probe the transport dynamics of the establishment and development of collective flow in large and small systems of heavy-ion collisions. We place test particles as passengers into the partonic medium created by Au$+$Au midcentral collisions at $\sqrt{s_{NN}}$ = 200 GeV and $p$ $+$ Pb central collisions at $\sqrt{s_{NN}}$ = 5.02 TeV, using a multiphase transport model. With the help of test particles in two extreme test cases, we demonstrate that parton collisions play an important role in establishing and developing collectivity in large and small colliding systems. The collectivity established by final state parton collisions is much stronger in large colliding systems compared to small colliding systems. The collectivity from the initial state can persist or survive more easily in small colliding systems than in large colliding systems due to fewer parton collisions. Our study provides a new method to understand the origin of collectivity in large and small colliding systems at the BNL Relativistic Heavy Ion Collider and the CERN Large Hadron Collider.

   ↳ nucl-thhep-phnucl-exPRC(2022)·4 citations
5. 05*

   Unified description of high-energy nuclear collisions based on dynamical core--corona picture

   Yuuka Kanakubo🇯🇵

   I establish the dynamical core--corona initialization framework (DCCI2) as a state-of-the-art dynamical framework that is capable of describing small and large colliding systems at the LHC energies. Under the core--corona picture, contributions from both equilibrated (core) and non-equilibrated (corona) components are implemented. I describe the dynamical separation of the system into the core and corona at the initial stage by incorporating the core--corona picture into the novel dynamical initialization framework. With DCCI2, I simulate $p$+$p$ collisions at $\sqrt{s}=7,13$ TeV and $Pb$+$Pb$ collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV. Especially, I extract the fractions of core and corona components in final hadron yields in $p$+$p$ and $Pb$+$Pb$ collisions as functions of multiplicity, and reveal that the core components become dominant at $⟨d{N}_{\mathrm{ch}}/d\eta {⟩}_{|\eta |<0.5}\approx 20$. I also find that the corona contribution at very low $p_T$ (below $p_T\approx 1$ GeV) is non-negligible even in $Pb$+$Pb$ collisions and show that such contributions significantly affect $p_T$-integrated flow coefficients. These results strongly suggest the importance of considering non-equilibrated components to extract transport coefficients of quark-gluon plasma from model-to-data comparisons quantitatively.

   ↳ nucl-thhep-phnucl-ex2 citations
6. 06*

   Stochastic modeling of a neutron imaging center at the Brazilian Multipurpose Reactor

   Luiz P. de Oliveira🇧🇷 · Alexandre P.S. Souza🇧🇷 · Frederico A. Genezini🇧🇷 · Adimir dos Santos

   Neutron imaging is a non-destructive technique for analyzing a wide class of samples, such as archaeological or industrial material structures. In recent decades, technological advances have had a great impact on the neutron imaging technique, which has meant an evolution from simple radiographs using films (2D) to modern tomography systems with digital processing (3D). The 5 MW research nuclear reactor IEA-R1, which is located at the Instituto de Pesquisas Energéticas e Nucleares (IPEN) in Brazil, possesses a neutron imaging instrument with $1.0\times 10^6$ $n/c{m}^{2}s$ in the sample position. IEA-R1 is over 60 years old and the future of neutron science in Brazil, including imaging, will be expanded to a new facility called the Brazilian Multipurpose Reactor (RMB, Portuguese acronym), which will be built soon. The new reactor will house a suite of instruments at the Neutron National Laboratory, including the neutron imaging facility, viz., Neinei. Inspired by recent author's works, we model the Neinei instrument through stochastic Monte Carlo simulations. We investigate the sensitivity of the neutron imaging technique parameter ($L/D$ ratio) with the neutron flux, and the results are compared to data from the Neutra (PSI), Antares (FRM II), BT2 (NIST) and DINGO (OPAL) instruments. The results are promising and provide avenues for future improvements.

   ↳ physics.ins-detnucl-exquant-phNucl.Eng.Des.(2024)·4 citations
7. 07*

   Fluctuations of conserved charges in strong magnetic fields from lattice QCD

   Heng-Tong Ding🇨🇳 · Sheng-Tai Li🇨🇳 · Jun-Hong Liu🇨🇳 · Xiao-Dan Wang🇨🇳

   We present the first lattice QCD results of the second order fluctuations of and correlations among net baryon number, electric charge and strangeness in (2+1)-flavor lattice QCD in the presence of a background magnetic field with physical pion mass $m_{\pi }=135$ MeV. To mimic the magnetic field strength produced in the early stage of heavy-ion collision experiments we use 6 different values of the magnetic field strength up to $\sim$10$m_{\pi }^2$. We find that the correlations between baryon number and electric charge along the transition line are substantially affected by magnetic fields in the current $eB$ window, which could be useful for probing the existence of a magnetic field in heavy-ion collision experiments.

   ↳ hep-lathep-phnucl-exnucl-thActa Phys.Polon.Supp.(2023)·16 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.