Mon·Mar 22, 2021Monday·March 22, 2021

1. 01*

   Production cross sections and angular distributions of neutron-rich rare isotopes from 15 MeV/nucleon Kr-induced collisions: toward the r-process path

   O. Fasoula🇬🇷 · G.A. Souliotis🇬🇷 · Y.K. Kwon🇰🇷 · K. Tshoo🇰🇷 · M. Veselsky🇨🇿 · S.J. Yennello🇺🇸 · A. Bonasera🇺🇸

   We present our recent study of cross sections and angular distributions of projectile fragments from heavy-ion reactions at beam energy of 15 MeV/nucleon. We studied the production cross sections and the angular distributions of neutron-rich nuclides from collisions of a 86 Kr (15 MeV/nucleon) beam with heavy targets ( 64 Ni, 124 Sn and 238 U). Experimental data from our previous work at Texas A & M were compared with model calculations. Our calculations were based on a two-step approach: the dynamical stage of the collision was described with, first, the phenomenological Deep-Inelastic Transfer model (DIT) and, alternatively, with the microscopic Constrained Molecular Dynamics model (CoMD). The de-excitation of the hot heavy projectile fragments was performed with the Statistical Multifragmentation Model (SMM). An overall good discription of the available data was obtained with the models employed. Furthermore, we performed calculations with a radioactive beam of 92 Kr (15 MeV/nucleon) interacting with a target of 238 U. We observed that the multinucleon transfer mechanism leads to extremely neutron-rich nuclides toward and beyond the astrophysical r-process path.

   nucl-exnucl-th4 citations
2. 02*

   Momentum Distributions of Projectile Fragments from Heavy-ion Peripheral Collisions at 15 MeV/nucleon with Emphasis on Trans-Projectile Isotopes

   S. Koulouris🇬🇷 · G.A. Souliotis🇬🇷 · I. Dimitropoulos🇬🇷 · O.Fasoula🇬🇷 · K. Palli🇬🇷 · M. Veselsky🇨🇿 · A. Bonasera🇺🇸

   This paper presents our recent efforts to study the momentum distributions as well as the production of neutron-rich rare isotopes with heavy-ion beams in the energy region of 15 MeV/nucleon. Experimental cross sections of neutron-rich nuclides from collisions of a 86 Kr (15 MeV/nucleon) beam with 64 Ni and 58 Ni targets are presented. Experimental data were obtained from the previous work of our group with the MARS mass spectrometer at the Cyclotron Institute of Texas A&M University. On that note, detailed calculations of yields and momentum distributions of neutron-rich projectile-like fragments are presented for the interaction of 86 Kr with 64 Ni and compared with the aforementioned experimental data. The calculations were based on a two-step general approach: the dynamical stage of the primary interaction was described with the phenomenological deep-inelastic transfer model (DIT) and the microscopic constrained molecular dynamics model (CoMD); the deexcitation stage of the excited projectile fragments was described with the statistical binary-decay model GEMINI. The experimental data show an enhancement in the production of neutron-rich isotopes close to the projectile, and interestingly of heavier than the projectile neutron-rich nuclei. The behaviour of the data is relative to the predictions of the CoMD/GEMINI calculation. The study of the momentum distributions offers a novel route to study the reaction mechanism that dominates the production of the fragments of interest in peripheral heavy-ion collisions at intermediate energies. In the future, we plan to analyze experimental data that were obtained from the MAGNEX spectometer at the INFN-LNS in Catania, Italy.

   nucl-exnucl-th0 citations
3. 03*

   Investigation of alpha particle induced reactions on natural silver in the 40-50 MeV energy range

   F. Ditrói🇭🇺 · S. Takács🇭🇺 · H. Haba🇯🇵 · Y. Komori🇯🇵 · M. Aikawa🇯🇵 · M. Saito🇯🇵 · T. Murata🇯🇵

   Natural silver targets have been irradiated by using a 50 MeV alpha-particle beam in order to measure the activation cross sections of radioisotopes in the 40-50 MeV energy range. Among the radio-products there are medically important isotopes such as ${}^{110m}$In and ${}^{111}$In. For optimizing the production of these radioisotopes and regarding their purity and specific activity the cross section data for every produced radioisotope are important. New data are measured in this energy range and the results of some previous measurements have been confirmed. Physical yield curves have been calculated by using the new cross section data completed with the results from the literature.

   nucl-exNucl.Instrum.Meth.B(2018)·1 citation
4. 04*

   Measurement of the neutron charge radius and the role of its constituents

   H. Atac🇺🇸 · M. Constantinou🇺🇸 · Z.-E. Meziani🇺🇸 · M. Paolone🇺🇸 · N. Sparveris🇺🇸

   The neutron is a cornerstone in our depiction of the visible universe. Despite the neutron zero-net electric charge, the asymmetric distribution of the positively- (up) and negatively-charged (down) quarks, a result of the complex quark-gluon dynamics, lead to a negative value for its squared charge radius, $⟨r_{\mathrm{n}}^2⟩$. The precise measurement of the neutron's charge radius thus emerges as an essential part of unraveling its structure. Here we report on a $⟨r_{\mathrm{n}}^2⟩$ measurement, based on the extraction of the neutron electric form factor, $G_{\mathrm{E}}^{\mathrm{n}}$, at low four-momentum transfer squared $(Q^2)$ by exploiting the long known connection between the $N\to \Delta$ quadrupole transitions and the neutron electric form factor. Our result, $⟨r_{\mathrm{n}}^2⟩=-0.110\pm 0.008({\mathrm{fm}}^2)$, addresses long standing unresolved discrepancies in the $⟨r_{\mathrm{n}}^2⟩$ determination. The dynamics of the strong nuclear force can be viewed through the precise picture of the neutron's constituent distributions that result into the non-zero $⟨r_{\mathrm{n}}^2⟩$ value.

   nucl-exnucl-thNature Commun.(2021)·51 citations
5. 05*

   Cluster dynamics studied with the phase-space Minimum Spanning Tree approach

   Viktar Kireyeu🇷🇺

   The origin of weakly bound objects like clusters and hypernuclei, observed in heavy-ion collisions, is of theoretical and experimental interest. It is in the focus of the experiments at RHIC and LHC since it is not evident how such weakly bound objects can survive in an environment whose hadronic decay products point to a temperature of the order of 150 MeV. It is as well one of the key research topics in the future facilities of FAIR and NICA which are under construction in Darmstadt (Germany) and Dubna (Russia), respectively. We present here first results on the cluster dynamics within the model-independent cluster recognition library "phase-space Minimum Spanning Tree" (psMST) applied to different transport approaches: PHQMD, PHSD, SMASH and UrQMD. The psMST is based on the "Minimum Spanning Tree" (MST) algorithm for the cluster recognition which exploits correlations in coordinate space, and it is extended to correlations of baryons in the clusters in momentum space. We show the sensitivity of the cluster formation on the microscopic realization of the n-body dynamics and on the potential interactions in heavy-ion collisions.

   ↳ nucl-thhep-exhep-thnucl-exPRC(2021)·14 citations
6. 06*

   Using local nuclear scaling of initial condition parameters to improve the system size dependence of transport model descriptions of nuclear collisions

   Chao Zhang🇨🇳 · Liang Zheng🇨🇳 · Shusu Shi🇨🇳 · Zi-Wei Lin🇺🇸

   We extensively study the system size dependence of nuclear collisions with a multi-phase transport model. Previously certain key parameters for the initial condition needed significantly different values for $pp$ and central $AA$ collisions for the model to reasonably describe the yields and transverse momentum spectra of the bulk matter in those collision systems. Here we scale two key parameters, the Lund string fragmentation parameter $b_L$ and the minijet transverse momentum cutoff $p_0$, with local nuclear thickness functions from the two colliding nuclei. This allows the model to use the parameter values for $pp$ collisions with the local nuclear scaling to describe the system size and centrality dependences of nuclear collisions self consistently. In addition to providing good descriptions of $pp$ collisions from 23.6 GeV to 13 TeV and reasonable descriptions of the centrality dependence of charged particle yields for Au+Au collisions from $7.7A$ GeV to $200A$ GeV and Pb+Pb collisions at LHC energies, the improved model can now well describe the centrality dependence of the mean transverse momentum of charged particles below $p_{\mathrm{T}}\lesssim 2$ GeV. It works similarly well for smaller systems including $p$Pb, Cu+Cu and Xe+Xe collisions.

   ↳ nucl-thnucl-exPRC(2021)·23 citations
7. 07*

   Re-investigation of heat capacity and paring phase transition in hot ${}^{93-98}$Mo nuclei

   Le Thi Quynh Huong · Tran Dong Xuan · Nguyen Ngoc Anh · Nguyen Quang Hung

   The empirical heat capacities of ${}^{93-98}$Mo nuclei are re-investigated by using the latest updated and recommended nuclear level density (NLD) data below the neutron binding energy $B_n$ combined with the back-shifted Fermi-gas (BSFG) model for the energy region above $B_n$. For the latter, the BSFG formula with energy-dependent level density parameter is used and the new parameterization has been carried out in order to obtain the best fit to the new NLD data in the whole data range. The results obtained show that the S-shaped heat capacity, a fingerprint of the pairing phase transition, is more pronounced in even ${}^{94,96,98}$Mo nuclei than that in odd ${}^{93,95,97}$Mo isotopes. This result is different with those obtained in two previous studies by R. Chankova et al., [Phys. Rev. C {\bf 73}, 034311 (2006)] and K. Kaneko et al., [Phys. Rev. C {\bf 74}, 024325 (2006)], in which the old NLD data and the BSFG model with energy-independent level density parameter were used. Moreover, the present work suggests that the very strong S-shape observed in the heat capacities of both even and odd Molybdenum isotopes by K. Kaneko et al., [Phys. Rev. C {\bf 74}, 024325 (2006)] should be re-investigated. The present work also suggests that obtain the correct heat capacity and associated pairing phase transition in excited nuclei, one should use the correct NLD data and the best fitted BSFG NLD in the entire region where the experimental data are available.

   ↳ nucl-thnucl-ex0 citations
8. 08*

   Coherent elastic neutrino-nucleus scattering with the $\nu$BDX-DRIFT directional detector at next generation neutrino facilities

   D. Aristizabal Sierra🇨🇱 · Bhaskar Dutta🇺🇸 · Doojin Kim🇺🇸 · Daniel Snowden-Ifft🇺🇸 · Louis E. Strigari🇺🇸

   We discuss various aspects of a neutrino physics program that can be carried out with the neutrino Beam-Dump eXperiment DRIFT ($\nu$BDX-DRIFT) detector using neutrino beams produced in next generation neutrino facilities. $\nu$BDX-DRIFT is a directional low-pressure TPC detector suitable for measurements of coherent elastic neutrino-nucleus scattering (CE$\nu$NS) using a variety of gaseous target materials which include carbon disulfide, carbon tetrafluoride and tetraethyllead, among others. The neutrino physics program includes standard model (SM) measurements and beyond the standard model (BSM) physics searches. Focusing on the Long Baseline Neutrino Facility (LBNF) beamline at Fermilab, we first discuss basic features of the detector and estimate backgrounds, including beam-induced neutron backgrounds. We then quantify the CE$\nu$NS signal in the different target materials and study the sensitivity of $\nu$BDX-DRIFT to measurements of the weak mixing angle and neutron density distributions. We consider as well prospects for new physics searches, in particular sensitivities to effective neutrino non-standard interactions.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2021)·23 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.