Thu·Nov 14, 2019Thursday·November 14, 2019

1. 01*

   Swelling of doubly magic ${}^{48}$Ca core in Ca isotopes beyond $N=28$

   M. Tanaka🇯🇵 · M. Takechi🇩🇪 · A. Homma · M. Fukuda · D. Nishimura🇯🇵 · T. Suzuki🇯🇵 · Y. Tanaka🇯🇵 · T. Moriguchi · D.S. Ahn🇯🇵 · A. Aimaganbetov · M. Amano · H. Arakawa and 58 other authors

   Interaction cross sections for ${}^{42\text{-}51}$Ca on a carbon target at 280 MeV/nucleon have been measured for the first time. The neutron number dependence of derived root-mean-square matter radii shows a significant increase beyond the neutron magic number $N=28$. Furthermore, this enhancement of matter radii is much larger than that of the previously measured charge radii, indicating a novel growth in neutron skin thickness. A simple examination based on the Fermi-type distribution, and the Mean-Field calculations point out that this anomalous enhancement of the nuclear size beyond $N=28$ results from an enlargement of the core by a sudden increase in the surface diffuseness of the neutron density distribution, which implies the swelling of the bare ${}^{48}$Ca core in Ca isotopes beyond $N=28$.

   nucl-exPRL(2020)·69 citations
2. 02*

   Compression-mode resonances in the calcium isotopes and implications for the asymmetry term in nuclear incompressibility

   Kevin B. Howard🇺🇸 · Umesh Garg🇺🇸 · Masatoshi Itoh🇯🇵 · Hidetoshi Akimune🇯🇵 · Soumya Bagchi🇳🇱 · Takanobu Doi🇯🇵 · Yuki Fujikawa · Mamoru Fujiwara🇯🇵 · Tatsuya Furuno · Muhsin N. Harakeh🇳🇱 · Yuto Hijikata · Kento Inaba and 14 other authors

   Recent data on isoscalar giant monopole resonance (ISGMR) in the calcium isotopes ${}^{40,44,48}$Ca have suggested that $K_{\tau }$, the asymmetry term in the nuclear incompressibility, has a positive value. A value of $K_{\tau }>0$ is entirely incompatible with present theoretical frameworks and, if correct, would have far-reaching implications on our understanding of myriad nuclear and astrophysical phenomena. This paper presents results of an independent ISGMR measurement with the ${}^{40,42,44,48}$Ca($\alpha ,{\alpha }^{\prime }$) reaction at $E_{\alpha }=386$ MeV. These results conclusively discount the possibility of a positive value for $K_{\tau }$, and are consistent with the previously-obtained values for this quantity.

   nucl-exPLB(2020)·23 citations
3. 03*

   Shape analysis of HBT correlations at STAR

   Daniel Kincses (for the STAR Collaboration)🇭🇺

   To study the nature of the quark-hadron phase transition, it is important to investigate the space-time structure of the hadron-emitting source in heavy-ion collisions. Measurements of HBT correlations have proven to be a powerful tool to gain information about the source. In these proceedings, we report the current status of the analysis of source parameters obtained from Lévy fits to the measured one-dimensional two-pion correlation functions in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV.

   nucl-exPhys.Part.Nucl.(2020)·4 citations
4. 04*

   Data on neutron-neutron scattering length extracted in the n+2H-->n+n+p reaction at 60 MeV

   E.S. Konobeevski · A.A. Afonin🇷🇺 · S.V. Zuyev · A.A. Kasparov · V.V. Mitcuk · M.V. Mordovskoy · S.I. Potashev

   ${}^1{S}_0$ \textit{nn}-scattering length has been measured in the \textit{nd}-breakup reaction at 60 MeV. The experiment was performed in the final state interaction geometry with registration of all three secondary particles. The scattering length $a_{nn}=-16.3\pm 0.5$~fm was obtained from a comparison of the experimental dependence of the \textit{nd}-breakup yield on the relative energy of \textit{nn}-pair with the simulation results. An analysis of this value of scattering length together with the data obtained in other experiments on \textit{nd}- and \textit{dd}-breakup confirms the hypothesis about the influence of $3N$-forces on the values of \textit{nn}-interaction parameters extracted in these reactions.

   nucl-exPhys.Atom.Nucl.(2020)·1 citation
5. 05*

   Characterization of the ${}^{12}$C(p,p')${}^{12}$C Reaction (E${}_p$=19.5$-$30 MeV) for Active Interrogation

   J. Nattress🇺🇸 · F. Sutanto🇺🇸 · P.-W. Fang · Y.-Z. Chen🇨🇳 · A. Chen · K.-Y. Chu · T.S. Duh · H.-Y. Tsai · M.-W. Lin · I. Jovanovic🇺🇸

   Passive detection of special nuclear material (SNM) is challenging due to its inherently low rate of spontaneous emission of penetrating radiation, the relative ease of shielding, and the fluctuating and frequently overwhelming background. Active interrogation (AI), the use of external radiation to increase the emission rate of characteristic radiation from SNM, has long been considered to be a promising method to overcome those challenges. Current AI systems that incorporate radiography tend to use bremsstrahlung beams, which can deliver high radiation doses. Low-energy ion-driven nuclear reactions that produce multiple monoenergetic photons may be used as an alternative. The ${}^{12}$C(p,p')${}^{12}$C is one such reaction that could produce large gamma-ray yields of highly penetrating 4.4- and 15.1-MeV gamma rays. This reaction does not directly produce neutrons below the $\sim$19.7-MeV threshold, and the 15.1-MeV gamma-ray line is well matched to the photofission cross-section of ${}^{235}$U and ${}^{238}$U. We report the measurements of thick-target gamma-ray yields at 4.4 and 15.1 MeV from the ${}^{12}$C(p,p')${}^{12}$C at proton energies of 19.5, 25, and 30 MeV. Measurements were made with two 3'' EJ309 cylindrical liquid scintillation detectors and thermoluminescent dosimeters placed at 0 and 90 degrees. We estimate the highest yields of the 4.4- and 15.1-MeV gamma rays of 1.65$\times 10^{10}$ sr${}^{-1}\mu$ C${}^{-1}$ and 4.47$\times 10^8$ sr${}^{-1}\mu$ C${}^{-1}$ at a proton energy of 30 MeV, respectively. The yield of 4.4 and 15.1 MeV gamma rays in all experimental configurations is greater than a comparable deuteron-driven reaction that produces the same gamma-ray energies- ${}^{11}$B(d,n$\gamma$)${}^{12}$C. However, a two orders of magnitude increase of the neutron radiation dose is observed when the proton energy increases from 19.5 to 30 MeV.

   nucl-exphysics.ins-detPhys.Rev.Applied(2020)·2 citations
6. 06*

   Elastic electromagnetic form factors of vector mesons

   Yin-Zhen Xu🇨🇳 · Daniele Binosi🇮🇹 · Zhu-Fang Cui🇨🇳 · Bo-Lin Li🇨🇳 · Craig D Roberts🇨🇳 · Shu-Sheng Xu🇨🇳 · Hong-Shi Zong🇨🇳

   A symmetry-preserving approach to the two valence-body continuum bound-state problem is used to calculate the elastic electromagnetic form factors of the $\rho$-meson and subsequently to study the evolution of vector-meson form factors with current-quark mass. To facilitate a range of additional comparisons, $K^{\ast }$ form factors are also computed. The analysis reveals that: vector mesons are larger than pseudoscalar mesons; composite vector mesons are non-spherical, with magnetic and quadrupole moments that deviate $\sim 30$\% from point-particle values; in many ways, vector-meson properties are as much influenced by emergent mass as those of pseudoscalars; and vector meson electric form factors possess a zero at spacelike momentum transfer. Qualitative similarities between the electric form factors of the $\rho$ and the proton, $G_E^p$, are used to argue that the character of emergent mass in the Standard Model can force a zero in $G_E^p$. Morover, the existence of a zero in vector meson electric form factors entails that a single-pole vector meson dominance model can only be of limited use in estimating properties of off-shell vector mesons, providing poor guidance for systems in which the Higgs-mechanism of mass generation is dominant.

   ↳ nucl-thhep-exhep-lathep-ph+1PRD(2019)·63 citations
7. 07*

   Characterization of an electrically cooled BEGe detector till E${}_{\gamma }\sim 7$ MeV

   Sathi Sharma🇮🇳 · Arkabrata Gupta🇮🇳 · Balaram Dey🇮🇳 · M. Roy Chowdhury · A. Mandal🇮🇳 · A. Bisoi · V. Nanal🇮🇳 · L.C. Tribedi🇮🇳 · M. Saha Sarkar🇮🇳

   An electrically cooled Broad Energy Germanium (BEGe) detector has been characterized in the energy range E${}_{\gamma }$ $\sim$ 0.122 - 7 MeV by utilizing the $\gamma$- rays emitted by a short-lived resonance state in ${}^{15}$O populated through ${}^{14}$N(p,$\gamma$) reaction and standard radioactive source (${}^{152}$Eu). The experimental results have been reproduced through simulations with GEANT4 code, including vendor specified detector geometry along with the detailed construction of the target holder flange, to delineate the effects of the holder at various energies and detector position. Later the efficiency with a bare point source has been simulated. It has been found that the electrically cooled BEGe detector is suitable for usage in the $\gamma$-ray spectroscopy as well as for the study of resonance phenomena in nuclear astrophysics.

   ↳ physics.ins-detnucl-exnucl-thNucl.Instrum.Meth.A(2020)·4 citations
8. 08*

   $g$-matrix folding-model approach to reaction cross sections for scattering of Ca isotopes on a C target

   Shingo Tagami🇯🇵 · Masaomi Tanaka🇯🇵 · Maya Takechi🇩🇪 · Mitsunori Fukuda · Masanobu Yahiro🇯🇵

   We first predict the ground-state properties of Ca isotopes, using the Gogny-D1S Hartree-Fock-Bogoliubov (GHFB) with and without the angular momentum projection (AMP). We find that ${}^{64}$Ca is an even-dripline nucleus and ${}^{59}$Ca is an odd-dripline nucleus, using $A$ dependence of the one-neutron separation energy $S_1$ and the two-neutron separation energy, $S_2$. As for $S_1$, $S_2$ and the binding energies $E_{\mathrm{B}}$, our results agree with the experimental data in ${}^{40-58}$Ca. As other ground-state properties of ${}^{40-60,62,64}$Ca, we predict charge, proton, neutron, matter radii, neutron skin and deformation. As for charge radii, our results are consistent with the experimental data in ${}^{40-52}$Ca. For ${}^{48}$Ca, our results on proton, neutron, matter radii agree with the experimental data. Very lately, Tanaka et. al. measured interaction cross sections for ${}^{42-51}$Ca scattering on a ${}^{12}$C target at an incident energy per nucleon of $E_{\mathrm{lab}}=280$MeV. Secondly, we predict reaction cross sections ${\sigma }_{\mathrm{R}}$ for ${}^{40-60,62,64}$Ca, using a chiral $g$-matrix double-folding model (DFM). To show the reliability of the present DFM for ${\sigma }_{\mathrm{R}}$, we apply the DFM for the data on ${}^{12}$C scattering on ${}^9$Be, ${}^{12}$C, ${}^{27}$Al targets in $30<E_{\mathrm{lab}}<400$MeV, and show that the present DFM is good in $30<E_{\mathrm{lab}}<100$MeV and $250<E_{\mathrm{lab}}<400$MeV. For $110<E_{\mathrm{lab}}<240$MeV, our results have small errors. To improve the present DFM for ${\sigma }_{\mathrm{R}}$, we propose two prescriptions.

   ↳ nucl-thnucl-exPRC(2020)·25 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.