Fri·Dec 9, 2022Friday·December 9, 2022

1. 01*

   Search for the Chiral Magnetic Wave in Pb--Pb collisions using the ALICE detector

   Wenya Wu🇨🇳

   The interplay of the chiral anomaly and the strong magnetic field ($\sim$ 10${}^{15}$ T) created in heavy-ion collisions could give rise to a collective excitation in the quark--gluon plasma called the Chiral Magnetic Wave (CMW). This effect can be experimentally sought by the charge asymmetry ($A_{\mathrm{ch}}$) dependence of elliptic flow $v_2$. However, non-CMW mechanisms such as local charge conservation (LCC) coupled with collective flow can also lead to a similar dependence of $v_2$ on $A_{\mathrm{ch}}$. The triangular flow ($v_3$) measurement serves as a reference as it is not expected to be affected by the CMW. The $v_2$ and $v_3$ of charged hadrons as a function of $A_{\mathrm{ch}}$ measured in Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 and 5.02 TeV are presented. In addition, the event-shape engineering (ESE) technique is adopted for the first time to quantitatively disentangle the CMW signal and the LCC background. The results indicate that the background effects dominate the CMW measurements.

   nucl-exEPJ Web Conf.(2023)·1 citation
2. 02*

   $\alpha$-cluster decay from ${}^{24}$Mg resonances produced in ${}^{12}$C(${}^{16}$O,${}^{24}$Mg)$\alpha$ reaction

   Dong-Xi Wang · Yan-Lin Ye🇨🇳 · Cheng-Jian Lin · Jia-Hao Chen🇨🇳 · Kai Ma · Jia-Xing Han · Hui-Ming Jia🇨🇳 · Lei Yang · Li-Sheng Yang🇨🇳 · Zi-Yao Hu🇨🇳 · Ying Chen · Wei-Liang Pu and 12 other authors

   A transfer reaction and cluster-decay experiment, ${}^{12}$C(${}^{16}$O,${}^{24}$Mg$\to$$\alpha$+${}^{20}$Ne)$\alpha$, was performed at a beam energy of 96 MeV. Both recoil and decay $\alpha$ particles were detected in coincidence, allowing us to deduce the energy-momentum of a ${}^{20}$Ne fragment. A number of resonant states of ${}^{24}$Mg were reconstructed up to an excitation energy of approximately 30 MeV. Owing to the experimentally achieved excellent resolutions of the $Q$-value and excitation-energy spectra, the relative decay widths for each resonant state in ${}^{24}$Mg to various final states of ${}^{20}$Ne were extracted, alone with the total decay width. The obtained results provide good testing ground for theoretical descriptions of the multiple clustering configurations in ${}^{24}$Mg.

   nucl-exCPC(2023)·3 citations
3. 03*

   ${}^{54}$Fe($d$,$p$)${}^{55}$Fe and the evolution of single neutron energies in the $N=29$ isotones

   L. A. Riley🇺🇸 · I.C.S. Hay · L. T. Baby🇺🇸 · A. L. Conley · P. D. Cottle🇺🇸 · J. Esparza🇺🇸 · K. Hanselman🇺🇸 · B. Kelly · K. W. Kemper🇺🇸 · K. T. Macon🇺🇸 · G. W. McCann🇺🇸 · M. W. Quirin and 4 other authors

   A measurement of the ${}^{54}$Fe($d$,$p$)${}^{55}$Fe reaction at 16 MeV was performed using the Florida State University Super-Enge Split-Pole Spectrograph to determine single-neutron energies for the $2p_{3/2}$, $2p_{1/2}$, $1f_{5/2}$, $1g_{9/2}$ and $2d_{5/2}$ orbits. Two states were observed that had not been observed in previous (d, p) measurements. In addition, we made angular momentum transfer, \textit{L}, assignments to four states and changed \textit{L} assignments from previous ($d$, $p$) measurements for nine more states. The spin-orbit splitting between the $2p_{3/2}$ and $2p_{1/2}$ orbits is similar to that in the other $N=29$ isotones and not close to zero as a previous measurement suggested. While the $1f_{5/2}$ single neutron energy is significantly lower in ${}^{55}$Fe than in ${}^{51}$Ti, as predicted by a covariant density functional theory calculation, the single-neutron energy for this orbit in ${}^{55}$Fe is more than 1 MeV higher than the calculation suggests, although it is only 400 keV above the $2p_{1/2}$ orbit. The summed spectroscopic strength we observed for the $1g_{9/2}$ orbit up to the single-neutron separation energy of 9.3 MeV is only 0.3. This is surprising because the $1g_{9/2}$ orbit is predicted by Togashi \textit{et al.} to be located only 5.5 MeV above the $2p_{3/2}$ orbit.

   nucl-exPRC(2022)·8 citations
4. 04*

   Alpha decay of thermally excited nuclei

   J. E. Perez Velasquez · O. L. Caballero · N. G. Kelkar

   One of the prominent decay modes of heavy nuclei which are produced in astrophysical environments at temperatures of the order of $10^9$ K is the $\alpha$ (${}^4$He) decay. Thermally enhanced $\alpha$ decay rates are evaluated within the standard scheme of a tunneling decay where the $\alpha$ particle tunnels through the potential barrier formed by its interaction with the daughter nucleus. Following the observation that there exist several excited levels with the possibility of an $\alpha$ decay when the daughter nucleus is at a shell closure, we focus in particular on decays producing daughter nuclei with the neutron number, N = 126. Within a statistical approach we find that the half-lives, $t_{1/2}(T)$, for temperatures ranging from $T$ = 0 to 2.4 GK can decrease by 1 - 2 orders of magnitude with the exception of the decay of ${}^{212}$Po which decays to the doubly magic daughter ${}^{208}$Pb, where $t_{1/2}(T)$ decreases by 5 orders of magnitude. The effect of these thermally enhanced $\alpha$ decays on the $r$-process nucleosynthesis can be significant in view of the mass build up at the waiting point nuclei with closed neutron shells.

   ↳ nucl-thastro-ph.HEnucl-exJ.Phys.G(2023)·8 citations
5. 05*

   Nuclear chiral rotation induced by superfluidity

   Y. P. Wang · J. Meng🇨🇳

   The microscopic understanding on the influence of the pairing correlations or the superfluidity on the nuclear chiral rotation has been a longstanding and challenging problem. Based on the three-dimensional cranking covariant density functional theory, a shell-model-like approach with exact particle number conservation is implemented to take into account the pairing correlations and applied for the chiral doublet bands in Nd135. The data available are well reproduced. It is found that the superfluidity can reduce the critical frequency and make the chiral rotation easier. The mechanism is that the particle/hole alignments along the short/long axis are reduced by the pairing correlations, resulting in the enhanced preference of the collective rotation along the intermediate axis, and inducing the early appearance of the chiral rotation.

   ↳ nucl-thnucl-exPLB(2023)·23 citations
6. 06*

   Development of a large-mass, low-threshold detector system with simultaneous measurements of athermal phonons and scintillation light

   M. Chaudhuri🇮🇳 · G. Agnolet🇺🇸 · V. Iyer🇮🇳 · V. K. S. Kashyap🇮🇳 · M. Lee🇰🇷 · R. Mahapatra🇺🇸 · S. Maludze🇺🇸 · N. Mirabolfathi🇺🇸 · B. Mohanty🇮🇳 · M. Platt🇺🇸 · A. Upadhyay · S. Sahoo🇮🇳 · S. Verma

   We have combined two low-threshold detector technologies to develop a large-mass, low-threshold detector system that simultaneously measures the athermal phonons in a sapphire detector while an adjacent silicon high-voltage detector detects the scintillation light from the sapphire detector. This detector system could provide event-by-event discrimination between electron and nuclear events due to the difference in their scintillation light yield. While such systems with simultaneous phonon and light detection have been demonstrated earlier with smaller detectors, our system is designed to provide a large detector mass with high amplification for the limited scintillation light. Future work will focus on at least an order of magnitude improvement in the light collection efficiency by having a highly reflective detector housing and custom phonon mask design to maximize light collection by the silicon high-voltage detector.

   ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2023)·2 citations
7. 07*

   MFV approach to robust estimate of neutron lifetime

   Jiang Zhang · Sen Zhang · Zhen-Rong Zhang🇨🇳 · Pu Zhang🇨🇳 · Wen-Bin Li · Yan Hong

   Aiming at evaluating the lifetime of the neutron, we introduce a novel statistical method to analyse the updated compilation of precise measurements including the 2022 dataset of Particle Data Group (PDG). Based on the minimization for the information loss principle, unlike the median statistics method, we apply the most frequent value (MFV) procedure to estimate the neutron lifetime, irrespective of the Gaussian or non-Gaussian distributions. Providing a more robust way, the calculated result of the MFV is ${\tau }_n=881.16_{-2.35}^{+2.25}$ s with statistical bootstrap errors, while the result of median statistics is ${\tau }_n=881.5_{-3}^{+5.5}$ s according to the binomial distribution. Using the different central estimates, we also construct the error distributions of neutron lifetime measurements and find the non-Gaussianity, which is still meaningful.

   ↳ physics.data-anastro-ph.COnucl-exEPJC(2022)·13 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.