Tue·Jan 4, 2022Tuesday·January 4, 2022

1. 01*

   Reconstruction of Fission Events in Heavy Ion Reactions with CSHINE

   Xinyue Diao🇨🇳 · Fenhai Guan🇨🇳 · Yijie Wang🇨🇳 · Yuhao Qin🇨🇳 · Zhi Qin🇨🇳 · Dong Guo · Qianghua Wu · Dawei Si🇨🇳 · Xuan Zhao · Sheng Xiao · Yaopeng Zhang🇺🇸 · Xianglun Wei🇨🇳 and 8 other authors

   We report the reconstruction method of the fast fission events in 25 MeV/u ${}^{86}$Kr +${}^{208}$Pb reactions at the Compact Spectrometer for Heavy IoN Experiment (CSHINE). The fission fragments are measured by three large-area parallel plate avalanche counters, which can deliver the position and the arrival timing information of the fragments. The start timing information is given by the radio frequency of the cyclotron. Using the velocities of the two fission fragments, the fission events are reconstructed. The broadening of both the velocity distribution and the azimuthal difference of the fission fragments decrease with the folding angle, in accordance with the picture that fast fission occurs. The anisotropic angular distribution of the fission axis also reveals consistently the dynamic feature the fission events.

   nucl-ex0 citations
2. 02*

   Isospin Mixing and the Cubic Isobaric Multiplet Mass Equation in the Lowest T = 2, A = 32 Quintet

   M. Kamil🇿🇦 · S. Triambak🇿🇦 · A. Magilligan🇺🇸 · A. García🇺🇸 · B. A. Brown🇺🇸 · P. Adsley🇿🇦 · V. Bildstein · C. Burbadge🇨🇦 · A. Diaz Varela🇨🇦 · T. Faestermann🇩🇪 · P. E. Garrett🇨🇦 · R. Hertenberger🇩🇪 and 15 other authors

   The isobaric multiplet mass equation (IMME) is known to break down in the first T = 2, A = 32 isospin quintet. In this work we combine high-resolution experimental data with state-of-the-art shell-model calculations to investigate isospin mixing as a possible cause for this violation. The experimental data are used to validate isospin-mixing matrix elements calculated with newly developed shell-model Hamiltonians. Our analysis shows that isospin mixing with nonanalog T = 1 states contributes to the IMME breakdown, making the requirement of an anomalous cubic term inevitable for the multiplet.

   nucl-exPRC(2021)·7 citations
3. 03*

   Possible early universe signals in proton collisions at the Large Hadron Collider

   Raghunath Sahoo🇮🇳 · Tapan Kumar Nayak🇨🇭

   Our universe was born about 13.8 billion years ago from an extremely hot and dense singular point, in a process known as the Big Bang. The hot and dense matter which dominated the system within a few microseconds of its birth was in the form of a soup of elementary quarks and gluons, known as the quark-gluon plasma (QGP). Signatures compatible with the formation of the QGP matter have experimentally been observed in heavy-ion (such as Au or Pb) collisions at ultra-relativistic energies. Recently, experimental data of proton-proton (pp) collisions at the CERN Large Hadron Collider (LHC) have also shown signals resembling those of the QGP formation, which made these studies quite stimulating as to how the collision of small systems features in producing the early universe signals. In this article, we report on some of the compelling experimental results and give an account of the present understanding. We review the pp physics program at the LHC and discuss future prospects in the context of exploring the nature of the primordial matter in the early universe.

   ↳ hep-phhep-exhep-thnucl-ex+1Curr.Sci.(2021)·22 citations
4. 04*

   Fieldable muon spectrometer using multi-layer pressurized gas Cherenkov radiators and its applications

   Junghyun Bae🇺🇸 · Stylianos Chatzidakis🇺🇸

   Cosmic ray muons have been considered as a non-conventional radiation probe in various applications. To utilize cosmic ray muons in engineering applications, two important quantities, trajectory and momentum, must be known. The muon trajectories are easily reconstructed using two-fold detector arrays with a high spatial resolution. However, precise measurement of muon momentum is difficult to be achieved without deploying large and expensive spectrometers such as solenoid magnets. Here, we propose a new method to estimate muon momentum using multi-layer pressurized gas Cherenkov radiators. This is accurate, portable, compact (< 1m3), and easily coupled with existing muon detectors without the need of neither bulky magnetic nor time-of-flight spectrometers. The results show that not only our new muon spectrometer can measure muon momentum with a resolution of +-0.5 GeV/c in a momentum range of 0.1 to 10.0 GeV/c, but also we can reconstruct cosmic muon spectrum with high accuracy (~90%).

   ↳ physics.ins-detastro-ph.IMhep-exnucl-exSci.Rep.(2022)·7 citations
5. 05*

   Chiral Dynamics: Theory and Experiment -- A Tribute to Aron Bernstein

   Ulf-G. Meißner🇩🇪

   I review and discuss the contributions of Aron Bernstein to the field of chiral dynamics.

   ↳ hep-phhep-exhep-latnucl-ex+1PoS(2024)·2 citations
6. 06*

   Direct Nuclear Reactions

   Carlos A. Bertulani🇺🇸 · Angela Bonaccorso🇮🇹

   In this brief review we discuss the basic theoretical concepts used in the experimental studies of the most common cases of direct reactions such as (a) elastic scattering, (b) inelastic scattering, (c) Coulomb excitation, (d) transfer reactions and (e) breakup reactions.

   ↳ nucl-thnucl-ex0 citations
7. 07*

   First operation of undoped CsI directly coupled with SiPMs at 77 Kelvin

   Keyu Ding🇺🇸 · Jing Liu🇺🇸 · Yongjin Yang🇺🇸 · Dmitry Chernyak🇺🇸

   The light yield of a small undoped cesium iodide (CsI) crystal directly coupled with two silicon photomultipliers (SiPMs) at about 77~Kelvin was measured to be $43.0\pm 1.1$~photoelectrons (PE) per keV electron-equivalent (keV${}_{\text{ee}}$) using $X$ and $\gamma$-ray peaks from an ${}^{241}$Am radioactive source from 18 to 60 keV. The high light yield together with some other technical advantages illustrate the great potential of this novel combination for neutrino and low-mass dark matter detection, particularly at accelerator-based neutrino sources, where random background can be highly suppressed by requiring coincident triggers between SiPMs and beam pulse timing signals. Some potential drawbacks of using cryogenic SiPMs instead of photomultiplier tubes (PMTs) were identified, such as worse energy resolution and optical cross-talks between SiPMs. Their influence to rare-event detection was discussed and possible solutions were provided.

   ↳ physics.ins-dethep-exnucl-exEPJC(2022)·15 citations
8. 08*

   An accelerator experiment for junior and senior high school students to improve students' involvement in fundamental physics

   K.S. Tanaka🇨🇭 · K. Harada🇯🇵 · T. Hayamizu🇨🇦 · R. Kita · R. Kono · K. Maruta · H. Nagahama · N. Ozawa · Y. Sakemi · R. Sugimori

   In Japan, research activities by junior and senior high school students show an upward trend. However, there are limited examples of research activities in the field of elementary particles and atoms. This is due to the difficulty associated with procuring research tools such as accelerators or particle detectors. Therefore, we hosted the "Accel Kitchen" in 2018 and 2019 at Cyclotron and Radioisotope Center (CYRIC) in Tohoku University where junior and senior high school students could participate in ongoing research of particle and atomic physics. At each workshop, 12 junior and senior high school students participated in the beam experiment, including the production of francium atoms (Fr) by the fusion reaction of oxygen and gold, optimizing the transport of the ion beam and identifying the alpha decay nuclei, and laser trapping of Fr for two days. Each group that was involved in the experiment was supported by researchers and university students who acted as mentors. This was the first opportunity for junior and senior high school students to know about the particle beam experiment in Japan.

   ↳ physics.ed-phnucl-exphysics.acc-phphysics.atom-phPhys.Educ.(2022)·0 citations
9. 09*

   Nuclear masses learned from a probabilistic neural network

   A.E. Lovell🇺🇸 · A.T. Mohan · T.M. Sprouse🇺🇸 · M.R. Mumpower🇺🇸

   Machine learning methods and uncertainty quantification have been gaining interest throughout the last several years in low-energy nuclear physics. In particular, Gaussian processes and Bayesian Neural Networks have increasingly been applied to improve mass model predictions while providing well-quantified uncertainties. In this work, we use the probabilistic Mixture Density Network (MDN) to directly predict the mass excess of the 2016 Atomic Mass Evaluation within the range of measured data, and we extrapolate the inferred models beyond available experimental data. The MDN not only provides mean values but also full posterior distributions both within the training set and extrapolated testing set. We show that the addition of physical information to the feature space increases the accuracy of the match to the training data as well as provides for more physically meaningful extrapolations beyond the the limits of experimental data.

   ↳ nucl-thnucl-exPRC(2022)·60 citations
10. 10*

    Symmetry breaking of Gamow-Teller and magnetic-dipole transitions and its restoration in calcium isotopes

    Tomohiro Oishi🇭🇷 · Ante Ravlic🇭🇷 · Nils Paar🇭🇷

    Nuclear magnetic-dipole (M1) and Gamow-Teller (GT) transitions provide insight into the spin-isospin properties of atomic nuclei. By considering them as unified spin-isospin transitions, the M1/GT transition strengths and excitation energies are subject to isospin symmetry. The excitation properties associated to the M1/GT symmetry need to be clarified within consistent theoretical approach. In this work, the relationship between the M1 and GT transitions in Ca isotopes is investigated in a unified framework based on the relativistic energy-density functional (REDF) with point-coupling interactions, using the relativistic quasi-particle random-phase approximation (RQRPA). It is shown that the isovector-pseudovector (IV-PV) residual interaction affects both transitions, and the symmetry of M1 and giant-GT transitions is disrupted by this interaction in closed-shell nuclei. In open-shell Ca isotopes, the proton-neutron pairing in the residual RQRPA interaction also plays a role in GT transitions. Due to the interplay between these interactions, the M1/GT symmetry can be restored especially in the ${}^{42}$Ca nucleus, i.e., the giant-GT strength can become comparable to that of the M1 mode in terms of the unified spin-isospin transitions by adjusting the PN-pairing strength to reproduce the experimental low-lying GT-excitation energies. The mirror symmetry of both M1 and GT transitions is also demonstrated for open-shell mirror partners, ${}^{42}$Ca and ${}^{42}$Ti. Further improvements are required to achieve simultaneous reproduction of M1 and GT-transition energies in the REDF framework.

    ↳ nucl-thnucl-exPRC(2022)·4 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.