Tue·Mar 12, 2019Tuesday·March 12, 2019

1. 01*

   Multiparticle production and initial quasi-temperature from proton induced carbon collisions at $p_{Lab}=31$ GeV/$c$

   Pei-Pin Yang🇨🇳 · Mai-Ying Duan🇨🇳 · Fu-Hu Liu🇨🇳 · Raghunath Sahoo🇮🇳

   The momentum spectra of charged pions (${\pi }^{+}$ and ${\pi }^{-}$) and kaons ($K^{+}$ and $K^{-}$), as well as protons ($p$), produced in the beam protons induced collisions in a 90-cm-long graphite target [proton-carbon ($p$-C) collisions] at the beam momentum $p_{Lab}=31$ GeV/$c$ are studied in the framework of a multisource thermal model by using Boltzmann distribution and Monte Carlo method. The theoretical model results are approximately in agreement with the experimental data measured by the NA61/SHINE Collaboration. The related free parameters (effective temperature, rapidity shifts, and fraction of non-leading protons) and derived quantities (average transverse momentum and initial quasi-temperature) under given experimental conditions are obtained. It is shown that the considered free parameters and derived quantities to be strongly dependent on emission angle over a range from 0 to 380 mrad and weakly dependent on longitudinal position (graphite target thickness) over a range from 0 to 90 cm.

   ↳ hep-phhep-exnucl-exnucl-thAdv.High Energy Phys.(2020)·2 citations
2. 02*

   Cluster structure of light nuclei

   R. Bijker🇲🇽 · F. Iachello🇺🇸

   We review recent studies of the cluster structure of light nuclei within the framework of the algebraic cluster model (ACM) for nuclei composed of k alpha-particles and within the framework of the cluster shell model (CSM) for nuclei composed of k alpha-particles plus x additional nucleons. The calculations, based on symmetry considerations and thus for the most part given in analytic form, are compared with experiments in light cluster nuclei. The comparison shows evidence for Z_2, D_{3h} and T_d symmetry in the even-even nuclei 8Be (k=2), 12C (k=3) and 16O (k=4), respectively, and for the associated double groups Z'_2 and D'_{3h} in the odd nuclei 9Be, 9B (k=2, x=1) and 13C (k=3, x=1), respectively.

   ↳ nucl-thnucl-exPPNP(2020)·49 citations
3. 03*

   Cold dilute nuclear matter with $\alpha$-particle condensation in a generalized nonlinear relativistic mean-field model

   Zhao-Wen Zhang🇨🇳 · Lie-Wen Chen🇨🇳

   We explore the thermodynamic properties of homogeneous cold (zero-temperature) nuclear matter including nucleons and $\alpha$-particle condensation at low densities by using a generalized nonlinear relativistic mean-field (gNL-RMF) model. In the gNL-RMF model, the $\alpha$-particle is included as explicit degree of freedom and treated as point-like particle with its interaction described by meson exchanges and the in-medium effects on the $\alpha$ binding energy is described by density- and temperature-dependent energy shift with the parameters obtained by fitting the experimental Mott density. We find that below the dropping density $n_{\mathrm{drop}}$ ($\sim 3\times 10^{-3}$ fm${}^{-3}$), the zero-temperature symmetric nuclear matter is in the state of pure Bose-Einstein condensate (BEC) of $\alpha$ particles while the neutron-rich nuclear matter is composed of $\alpha$-BEC and neutrons. Above the $n_{\mathrm{drop}}$, the fraction of $\alpha$-BEC decreases with density and vanishes at the transition density $n_t$ ($\sim 8\times 10^{-3}$ fm${}^{-3}$). Above the $n_t$, the nuclear matter becomes pure nucleonic matter. Our results indicate that the empirical parabolic law for the isospin asymmetry dependence of nuclear matter equation of state is heavily violated by the $\alpha$-particle condensation in the zero-temperature dilute nuclear matter, making the conventional definition of the symmetry energy meaningless. We investigate the symmetry energy defined under parabolic approximation for the zero-temperature dilute nuclear matter with $\alpha$-particle condensation, and find it is significantly enhanced compared to the case without clusters and becomes saturated at about $7$ MeV at very low densities ($\lesssim 10^{-3}$ fm${}^{-3}$). The critical temperature for $\alpha$-condensation in homogeneous dilute nuclear matter is also discussed.

   ↳ nucl-thnucl-exPRC(2019)·11 citations
4. 04*

   Three-body problem with velocity-dependent optical potentials: a case of $(d,p)$ reactions

   N.K. Timofeyuk🇬🇧

   The change in mass of a nucleon, arising from its interactions with other nucleons inside the target, results in velocity-dependent terms in the Schrödinger equation that describes nucleon scattering. It has recently been suggested in a number of publications that introducing and fitting velocity-dependent terms improves the quality of the description of nucleon scattering data for various nuclei. The present paper discusses velocity-dependent optical potentials in a context of a three-body problem used to account for deuteron breakup in the entrance channel of $(d,p)$ reactions. Such potentials form a particular class of nonlocal optical potentials which are a popular object of modern studies. It is shown here that because of a particular structure of the velocity-dependent terms the three-body problem can be formulated in two different ways. Solving this problem within an adiabatic approximation results in a significant difference between the two approaches caused by contributions from the high $n$-$p$ momenta in deuteron in one of them. Solving the three-body problem beyond the adiabatic approximation may remove such contributions, which is indirectly confirmed by replacing the adiabatic approximation by the folding Watanabe model where such contributions are suppressed. Discussion of numerical results is carried out for the ${}^{40}$Ca($d,p{)}^{41}$Ca reaction where experimental data both on elastic scattering in entrance and exit channels and on nucleon transfer are available.

   ↳ nucl-thnucl-exJ.Phys.G(2019)·2 citations
5. 05*

   In-air ion beam analysis with high spatial resolution proton microbeam

   Milko Jakšić · Davit Chokheli · Stjepko Fazinić · Veljko Grilj · Natko Skukan · Ivan Sudić · Tonči Tadić · Tome Antičić🇭🇷

   One of the possible ways to maintain the micrometer spatial resolution while performing ion beam analysis in the air is to increase the energy of ions. In order to explore capabilities and limitations of this approach, we have tested a range of proton beam energies (2 - 6 MeV) using in-air STIM (Scanning Ion Transmission Microscopy) setup. Measurements of the spatial resolution dependence on proton energy have been compared with SRIM simulation and modelling of proton multiple scattering by different approaches. Results were used to select experimental conditions in which 1 micrometer spatial resolution could be obtained. High resolution in-air microbeam could be applied for IBIC (Ion Beam Induced Charge) tests of large detectors used in nuclear and high energy physics that otherwise can not be tested in relatively small microbeam vacuum chambers.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.B(2016)·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.