Mon·May 29, 2023Monday·May 29, 2023

1. 01*

   Simultaneous $\gamma$-ray and electron spectroscopy of ${}^{182,184,186}$Hg isotopes

   M. Stryjczyk🇫🇮 · B. Andel🇸🇰 · J. G. Cubiss🇨🇭 · K. Rezynkina🇫🇷 · T. R. Rodríguez🇪🇸 · J. E. García-Ramos🇪🇸 · A. N. Andreyev🇬🇧 · J. Pakarinen🇫🇮 · P. Van Duppen🇧🇪 · S. Antalic🇸🇰 · T. Berry🇬🇧 · M. J. G. Borge🇪🇸 and 39 other authors

   Background: The mercury isotopes around $N=104$ are a well-known example of nuclei exhibiting shape coexistence. Mixing of configurations can be studied by measuring the monopole strength ${\rho }^2(E0)$, however, currently the experimental information is scarce and lacks precision, especially for the $I^{\pi }\to I^{\pi }$ ($I\ne 0$) transitions. Purpose: The goals of this study were to increase the precision of the known branching ratios and internal conversion coefficients, to increase the amount of available information regarding excited states in ${}^{182,184,186}$Hg and to interpret the results in the framework of shape coexistence using different models. Method: The low-energy structures in ${}^{182,184,186}$Hg were populated in the $\beta$ decay of ${}^{182,184,186}$Tl, produced at ISOLDE and purified by laser ionization and mass separation. The $\gamma$-ray and internal conversion electron events were detected by five germanium clover detectors and a segmented silicon detector, respectively, and correlated in time to build decay schemes. Results: In total, 193, 178 and 156 transitions, including 144, 140 and 108 observed for the first time in a $\beta$-decay experiment, were assigned to ${}^{182,184,186}$Hg, respectively. Internal conversion coefficients were determined for 23 transitions, out of which 12 had an $E0$ component. Extracted branching ratios allowed the sign of the interference term in ${}^{182}$Hg as well as ${\rho }^2(E0;0_2^{+}\to 0_1^{+})$ and $B(E2;0_2^{+}\to 2_1^{+})$ in ${}^{184}$Hg to be determined. By means of electron-electron coincidences, the $0_3^{+}$ state was identified in ${}^{184}$Hg. The experimental results were qualitatively reproduced by five theoretical approaches, the IBM with configuration mixing with two different parametrizations, the General Bohr Hamiltonian, the BMF model and the SCCM model. However, a quantitative description is lacking.

   nucl-exnucl-thPRC(2023)·0 citations
2. 02*

   Experimental Study of the ${}^{\text{38}}$S Excited Level Scheme

   C. R. Hoffman🇺🇸 · R. S. Lubna🇺🇸 · E. Rubino🇺🇸 · S. L. Tabor · K. Auranen🇫🇮 · P. C. Bender🇺🇸 · C. M. Campbell🇺🇸 · M. P. Carpenter🇺🇸 · J. Chen🇨🇳 · M. Gott · J. P. Greene · D. E. M. Hoff🇺🇸 and 11 other authors

   Information on the ${}^{38}$S level scheme was expanded through experimental work utilizing a fusion-evaporation reaction and in-beam $\gamma$-ray spectroscopy. Prompt $\gamma$-ray transitions were detected by the Gamma-Ray Energy Tracking Array (GRETINA) and recoiling ${}^{38}$S residues were selected by the Fragment Mass Analayzer (FMA). Tools based on machine-learning techniques were developed and deployed for the first time in order to enhance the unique selection of ${}^{38}$S residues and identify any associated $\gamma$-ray transitions. The new level information, including the extension of the even-spin yrast sequence through $J^{\pi }=8^{(+)}$, was interpreted in terms of a basic single-particle picture as well shell-model calculations which incorporated the empirically derived FSU interaction. A comparison between the properties of the yrast states in the even-$Z$ $N=22$ isotones from $Z=14$ to $20$, and for ${}^{36}$Si-${}^{38}$S in particular, was also presented with an emphasis on the role and influence of the neutron $1p_{3/2}$ orbital on the structure in the region.

   nucl-exPRC(2023)·1 citation
3. 03*

   First observation of electron emission from the DD threshold resonance

   K. Czerski · R. Dubey🇿🇦 · M. Kaczmarski · A. Kowalska · N. Targosz-Sleczka · G. Das Haridas · M. Valat

   Electron emission in the deuteron-deuteron reaction supporting existence of the single-particle threshold resonance in 4 He has been observed for the first time. The measured electron energy spectrum and the electron-proton branching ratio agree very well with the assumed electron-positron pair creation decay of the 0+ resonance state to the ground state and the detailed Monte Carlo simulations of the experimental energy spectrum.

   nucl-exPRC(2024)·7 citations
4. 04*

   Machine learning transforms the inference of the nuclear equation of state

   Yongjia Wang🇨🇳 · Qingfeng Li🇨🇳

   Our knowledge of the properties of dense nuclear matter is usually obtained indirectly via nuclear experiments, astrophysical observations, and nuclear theory calculations. Advancing our understanding of the nuclear equation of state (EOS, which is one of the most important properties and of central interest in nuclear physics) has relied on various data produced from experiments and calculations. We review how machine learning is revolutionizing the way we extract EOS from these data, and summarize the challenges and opportunities that come with the use of machine learning.

   ↳ nucl-thnucl-exFront.Phys.(Beijing)(2023)·21 citations
5. 05*

   Pulsar as a Weber detector of gravitational waves and a probe to its internal phase transitions

   Partha Bagchi🇮🇳 · Oindrila Ganguly🇮🇳 · Biswanath Layek🇮🇳 · Anjishnu Sarkar🇮🇳 · Ajit M. Srivastava🇮🇳

   It is believed that cores of neutron stars provide a natural laboratory where exotic high baryon density QCD phases may exist.The theoretically well established {\it neutron superfluid phase} is also believed to be found only inside neutron stars. Focus on neutron stars has intensified in recent years with the direct detection of gravitational waves (GWs) from binary neutron star (BNS) merger, which has allowed the possibility of directly probing the properties of the interior of a neutron star. A remarkable phenomenon manifested by rapidly rotating neutron stars is in their {\it avatar} as {\it Pulsars}. The accuracy of pulsar timing allowed the first indirect detection of GWs from a BNS system and opened up a few exciting possibilities. Any pulsar deformation, even if incredibly tiny, can leave imprints on the pulses by introducing tiny perturbations of the moment of inertia (MI) tensor components. While the diagonal MI components of the perturbed MI tensor affect the pulse timings, the off-diagonal components lead to the pulsar's wobbling and affecting the pulse profile. This opens up an opportunity to explore various phase transitions inside a pulsar core by induced density fluctuations through the observable effects on the pulse timing and profile. Such perturbations also naturally induce a rapidly changing quadrupole moment of the star, thereby providing a new source of GW emission. Another remarkable possibility arises when we consider the effect of an external GW on a neutron star. With the possibility of detecting any minute changes in its configuration through pulse observations, the neutron star has the potential to perform as a Weber detector of GWs. This brief review focuses on these specific aspects of a pulsar, specifically on the type of physics that can be probed by utilizing the effect of changes in the MI tensor on pulse properties.

   ↳ astro-ph.HEhep-phnucl-exnucl-thMod.Phys.Lett.A(2024)·5 citations
6. 06*

   Impact of initial fluctuations and nuclear deformations in isobar collisions

   Jian-fei Wang🇨🇳 · Hao-jie Xu🇨🇳 · Fuqiang Wang🇺🇸

   Relativistic isobar (${}_{44}^{96}$Ru+${}_{44}^{96}$Ru and ${}_{40}^{96}$Zr+${}_{40}^{96}$Zr) collisions have revealed intricate differences in their nuclear size and shape, inspiring unconventional studies of nuclear structure using relativistic heavy ion collisions. In this study, we investigate the relative differences in the mean multiplicity ($R_{⟨N_{\mathrm{ch}}⟩}$) and the second- ($R_{{ϵ}_2}$) and third-order eccentricity ($R_{{ϵ}_3}$) between isobar collisions using initial state models. It is found that initial fluctuations and nuclear deformations have negligible effects on $R_{⟨N_{\mathrm{ch}}⟩}$ in most central collisions, while both are important for the $R_{{ϵ}_2}$ and $R_{{ϵ}_3}$, the degree of which is sensitive to the underlying nucleonic or sub-nucleonic degree of freedom. These features, compared to real data, may probe the particle production mechanism and the physics underlying nuclear structure.

   ↳ nucl-thnucl-exNucl.Sci.Tech.(2024)·17 citations
7. 07*

   Novel Machine Learning and Differentiable Programming Techniques applied to the VIP-2 Underground Experiment

   F Napolitano🇮🇹 · M Bazzi🇮🇹 · M Bragadireanu🇷🇴 · M Cargnelli🇦🇹 · A Clozza🇮🇹 · L De Paolis🇮🇹 · R Del Grande🇮🇹 · C Fiorini🇮🇹 · C Guaraldo🇮🇹 · M Iliescu🇮🇹 · M Laubenstein🇮🇹 · S Manti🇮🇹 and 11 other authors

   In this work, we present novel Machine Learning and Differentiable Programming enhanced calibration techniques used to improve the energy resolution of the Silicon Drift Detectors (SDDs) of the VIP-2 underground experiment at the Gran Sasso National Laboratory (LNGS). We achieve for the first time a Full Width at Half Maximum (FWHM) in VIP-2 below 180 eV at 8 keV, improving around 10 eV on the previous state-of-the-art. SDDs energy resolution is a key parameter in the VIP-2 experiment, which is dedicated to searches for physics beyond the standard quantum theory, targeting Pauli Exclusion Principle (PEP) violating atomic transitions. Additionally, we show that this method can correct for potential miscalibrations, requiring less fine-tuning with respect to standard methods.

   ↳ physics.ins-detnucl-exMeasur.Sci.Tech.·3 citations
8. 08*

   Pulse shape discrimination based on the Tempotron: a powerful classifier on GPU

   Haoran Liu · Peng Li🇨🇳 · Ming-Zhe Liu · Kai-Ming Wang🇨🇳 · Zhuo Zuo · Bing-Qi Liu

   This study utilized the Tempotron, a robust classifier based on a third-generation neural network model, for pulse shape discrimination. By eliminating the need for manual feature extraction, the Tempotron model can process pulse signals directly, generating discrimination results based on prior knowledge. The study performed experiments using GPU acceleration, resulting in over 500 times faster compared to the CPU-based model, and investigated the impact of noise augmentation on the Tempotron performance. Experimental results substantiated that Tempotron serves as a formidable classifier, adept at accomplishing high discrimination accuracy on both AmBe and time-of-flight PuBe datasets. Furthermore, analyzing the neural activity of Tempotron during training shed light on its learning characteristics and aided in selecting its hyperparameters. Moreover, the study addressed the constraints and potential avenues for future development in utilizing the Tempotron for pulse shape discrimination. The dataset used in this study and the GPU-based Tempotron are publicly available on GitHub at https://github.com/HaoranLiu507/TempotronGPU.

   ↳ eess.SPcs.LGnucl-exIEEE Trans.Nucl.Sci.(2024)·1 citation

* 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.