Tue·Oct 4, 2022Tuesday·October 4, 2022

1. 01*

   Flow and transverse momentum correlation in Pb+Pb and Xe+Xe collisions with ATLAS: assessing the initial condition of the QGP

   Somadutta Bhatta (on behalf of the ATLAS Collaboration)🇺🇸

   One important challenge in our field is to understand the initial condition of the QGP and constrain it using sensitive experimental observables. Recent studies show that the Pearson Correlation Coefficient between ${\mathbf{V}}_n$ and event-wise mean transverse momentum $[p_{\mathrm{T}}]$, ${\rho }_n({\mathbf{V}}_n,[p_{\mathrm{T}}])$ can probe number and size of sources, nuclear deformation, volume fluctuation, and initial momentum anisotropy in initial state of heavy-ion collisions. This proceeding presents new, precision measurements of ${\mathbf{V}}_n-[p_{\mathrm{T}}]$ correlation in ${}^{129}\mathrm{Xe}{+}^{129}\mathrm{Xe}$ and ${}^{208}\mathrm{Pb}{+}^{208}\mathrm{Pb}$ collisions for harmonics $n=2$, 3, and 4 using the ATLAS detector at the LHC. The values of ${\rho }_n$ shows rich and non-monotonic dependence on centrality, $p_T$ and $\eta$, reflecting that different ingredients of the initial state impact different regions of the phase space. The ratio of ${\rho }_2$ between the two systems in the ultra-central region suggests that ${}^{129}\mathrm{Xe}$ has large quadrupole deformation and with a significant triaxiality. All current models fail to describe many of the observed trends in the data.

   nucl-exhep-exActa Phys.Polon.Supp.(2023)·0 citations
2. 02*

   Fissile isotopes antineutrino spectra: summation method and direct experiment

   P. Naumov🇷🇺 · S. Silaeva🇷🇺 · V. Sinev🇷🇺 · A. Vlasenko🇷🇺

   New antineutrino spectra of fissile isotopes (${}^{235}$U, ${}^{238}$U, ${}^{239}$Pu and ${}^{241}$Pu) which are containing in a nuclear reactor fuel have been obtained. A combined technique was used: calculation of antineutrino spectra and their fitting to those obtained in the experiment at the Rovno NPP in the 80s of the last century. The cross sections of fissile isotopes calculated with these spectra describe well the cross section obtained experimentally in the Double Chooz experiment. The calculated cross section for the same reactor core composition is ${\sigma }_f=(5.82\pm 0.12)\times 10^{-43}$ cm${}^2$/fission. It is the closest result between all predicted. The obtained spectra have the same "bump" as experimental ones in 5 MeV observed energy region.

   nucl-exhep-ph0 citations
3. 03*

   Exploiting dissipative reactions to perform in-beam $\gamma$-ray spectroscopy of the neutron-deficient isotopes \nuc{38,39}{Ca}

   A. Gade🇺🇸 · D. Weisshaar🇺🇸 · B. A. Brown🇺🇸 · D. Bazin🇺🇸 · K. W. Brown🇺🇸 · R. J. Charity🇺🇸 · P. Farris · A. M. Hill · J. Li🇨🇳 · B. Longfellow🇺🇸 · D. Rhodes🇨🇦 · W. Reviol🇺🇸 · J. A. Tostevin🇬🇧

   The neutron-deficient Ca isotopes continue to attract attention due to their importance for testing isospin symmetry and their relevance in capture reactions of interest for nova nucleosynthesis and the shape of light curves in Type I X-ray bursts. To date, spectroscopic information on 38,39 Ca is largely limited to data on lower-spin excited states. Here, we report in-beam {\gamma}-ray spectroscopy of complementary higher-spin, complex-structure states in 39 Ca populated in fast-beam-induced, momentum-dissipative processes leading to neutron pickup onto excited configurations of the projectile, 9 Be(38 Ca , 39 Ca + {\gamma})X. Such a dissipative reaction was recently characterized for the case of inelastic scattering of 38 Ca off 9 Be, 9 Be(38 Ca, 38 Ca + {\gamma})X. Additional data and discussion on the nuclear structure of 38 Ca is also presented. An explanation for the more-complex-structure states, populated with small cross sections in one-nucleon knockout reactions, and observed in the tails of their longitudinal momentum distributions, is also offered.

   nucl-exPRC(2022)·9 citations
4. 04*

   Deconstructing experimental decay energy spectra: the ${}^{26}$O case

   Pierre Nzabahimana · Thomas Redpath🇺🇸 · Thomas Baumann · Pawel Danielewicz🇺🇸 · Pablo Giuliani🇺🇸 · Paul Guèye🇺🇸

   In nuclear reaction experiments, the measured decay energy spectra can give insights into the shell structure of decaying systems. However, extracting the underlying physics from the measurements is challenging due to detector resolution and acceptance effects. The Richardson-Lucy (RL) algorithm, a deblurring method that is commonly used in optics and has proven to be a successful technique for restoring images, was applied to our experimental nuclear physics data. The only inputs to the method are the observed energy spectrum and the detector's response matrix also known as the transfer matrix. We demonstrate that the technique can help access information about the shell structure of particle-unbound systems from the measured decay energy spectrum that isn't immediately accessible via traditional approaches such as chi-square fitting. For a similar purpose, we developed a machine learning model that uses a deep neural network (DNN) classifier to identify resonance states from the measured decay energy spectrum. We tested the performance of both methods on simulated data and experimental measurements. Then, we applied both algorithms to the decay energy spectrum of ${}^{26}\mathrm{O}{\to }^{24}\mathrm{O}$ + n + n measured via invariant mass spectroscopy. The resonance states restored using the RL algorithm to deblur the measured decay energy spectrum agree with those found by the DNN classifier. Both deblurring and DNN approaches suggest that the raw decay energy spectrum of ${}^{26}\mathrm{O}$ exhibits three peaks at approximately 0.15~MeV, 1.50~MeV, and 5.00~MeV, with half-widths of 0.29~MeV, 0.80~MeV, and 1.85~MeV, respectively.

   ↳ nucl-thnucl-exPRC(2023)·14 citations
5. 05*

   Analysis of radiation damage in silicon charge-coupled devices used for dark matter searches

   Steven J. Lee (on behalf of DAMIC-M)🇨🇭

   Nuclear recoils in crystal detectors generate radiation damage in the form of crystal defects that can be measured in scientific-grade CCDs as local hot spots of leakage current stimulated by temperature increases in the devices. In this proceeding, we use a neutron source to generate defects in DAMIC-M CCDs, and using increases in leakage current at different temperatures, we demonstrate a procedure for identifying crystal defects in the CCDs of the DAMIC-M experiment. This is the first time that individual defects generated from nuclear recoils have been studied. This technique could be used to distinguish nuclear recoils from electron recoils in some energy ranges, which would improve the ability of CCD detectors to search for weakly interacting dark matter.

   ↳ physics.ins-detcond-mat.mtrl-scihep-exnucl-exSciPost Phys.Proc.(2023)·3 citations
6. 06*

   From lattice to observables: Real and virtual experiments for exploring hot and dense QCD

   Masakiyo Kitazawa🇯🇵

   Relativistic heavy-ion collisions and the lattice QCD Monte-Carlo simulations are important ``experimental'' tools for investigating the properties of the medium described by QCD under extreme conditions. After briefly examining their characteristics, I pick up the study of the critical points in QCD as an example of the research subjects that these two tools play complementary roles and discuss recent topics that have been achieved with the use of each tool.

   ↳ nucl-thhep-latnucl-exEPJ Web Conf.(2023)·0 citations
7. 07*

   Preformation Probability and Kinematics of Clusters Emission yielding Pb-daughters

   Joshua T. Majekodunmi · M. Bhuyan🇲🇾 · K. Anwar · N. Abdullah · Raj Kumar🇮🇳

   In the present study, the newly established preformation formula is applied for the first time to study the kinematics of the cluster emission from various radioactive nuclei, especially those decaying to the double-shell closure ${}^{208}$Pb nucleus and its neighbours as daughters. The recently proposed universal cluster preformation formula has been established based on the concepts that underscore the influence of the mass and charge asymmetry (${\eta }_A$ and ${\eta }_Z$), cluster mass $A_c$ and the Q-value, paving the way to quantify the energy contribution during the preformation as well as the tunnelling process separately. The cluster-daughter interaction potential is obtained by folding the relativistic mean-field (RMF) densities with the recently developed microscopic R3Y using the NL$3^{\ast }$ and the phenomenological M3Y NN potentials to compare their adaptability. The penetration probabilities are calculated from the WKB approximation. With the inclusion of the new preformation probability $P_0$, the predicted half-lives from the R3Y and M3Y interactions are in good agreement with the experimental data. Furthermore, a careful inspection reflects slight differences in the decay half-lives, which arise from their respective barrier properties. The $P_0$ for the systems with the double magic shell closure ${}^{208}$Pb daughter are found to be relatively higher with an order of $\approx 10^2$ than those with neighbouring Pb-daughter nuclei. By exploring the contributions of the decay energy, the recoil effect of the daughter nucleus is appraised, unlike several other conjectures. Thus, the centrality of the Q-value in the decay process is demonstrated and re-defined within the preformed cluster-decay model. Besides, we have introduced a simple and intuitive set of criteria that governs the estimation of recoil energy in the cluster radioactivity.

   ↳ nucl-thnucl-exCPC(2023)·6 citations
8. 08*

   The Nuclear g9/2 Shell -Comparison of our work with an old B.H. Flowers Paper

   Larry Zamick

   In an old paper [ 1] B.H. Flowers discussed calculations for odd A nuclei in the g9/2 shell. He finds when he varies the parameters of a certain interaction that the lowest energy state is always a seniority v=1 state with angular momentum J=9/2+. However experiments show about half the states have J=9/2+ lower and the other ones have J=7/2+ lower. More recently we considered selected nuclei between Z=40 and Z=50. For lower odd N Zr isotopes we find J=7/2+ comes below J=9/2+ while for odd Z isotones near Z=50 the opposite is true i.e. J=9/2+ comes below J= 7/2+.We justify using different interactions in the 2 regions by considering nuclear deformation near the Z=40 region. A plea to find missing energy levels is made.

   ↳ nucl-thnucl-ex2 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.