Mon·Oct 5, 2020Monday·October 5, 2020

1. 01*

   High precision half-life measurement of ${}^{95}$Ru, ${}^{95}$Tc and ${}^{95m}$Tc with $\gamma$-spectroscopy

   T. N. Szegedi🇭🇺 · Á. Tóth · G. G. Kiss🇭🇺 · Gy. gyürky🇭🇺

   The precise knowledge of the half-life of the reaction product is of crucial importance for a nuclear reaction cross section measurement carried out with the activation technique. The cross section of the ${}^{92}$Mo($\alpha$,n)${}^{95}$Ru reaction was measured recently using this experimental approach. The preliminary results indicated that the literature half-life of ${}^{95}$Ru, derived about half a century ago, is overestimated. Therefore, the half-lives of ${}^{95}$Ru and its daughter isotope ${}^{95}$Tc and ${}^{95m}$Tc have been measured with high precision using $\gamma$-spectroscopy. The results are t${}_{1/2}$=1.6033 $\pm$ 0.0044 h for ${}^{95}$Ru, t${}_{1/2}$ = 19.258 $\pm$ 0.026 h for ${}^{95}$Tc and t${}_{1/2}$ = 61.96 $\pm$ 0.24 d for ${}^{95m}$Tc. The precision of the half-life values has been increased, consequently the recently measured ${}^{92}$Mo($\alpha$,n)${}^{95}$Ru activation cross section will become more precise.

   nucl-exEPJA(2020)·4 citations
2. 02*

   Ring-Based Electron Cooling System for the EIC

   V. Lebedev🇺🇸 · S. Nagaitsev🇺🇸 · A. Burov🇺🇸 · V. Yakovlev🇺🇸 · I. Gonin🇺🇸 · I. Terechkine🇺🇸 · A. Saini🇺🇸 · N. Solyak🇺🇸

   This report describes a concept of an EIC cooling system, based on a proven induction linac technology with a dc electron beam. The system would operate in a full energy range of proton beams (100 - 270 GeV) and would provide 50-100 A electron beams, circulating in a cooler ring for 5 ms. Every 5 ms a new electron pulse would be injected into the cooler ring to provide continuous cooling at collisions. Operations with a 10-ms cycle is possible but it will reduce the cooling rates by ~30$\%$. The system is capable of delivering the required performance in the entire EIC energy range with emittance cooling times of less than 1-2 hours.

   ↳ physics.acc-phnucl-exJINST(2021)·9 citations
3. 03*

   Controlling $T_c$ of Iridium Films Using the Proximity Effect

   R. Hennings-Yeomans🇺🇸 · C. L. Chang🇺🇸 · J. Ding🇺🇸 · A. Drobizhev🇺🇸 · B. K. Fujikawa🇺🇸 · S. Han🇺🇸 · G. Karapetrov🇺🇸 · Yu. G. Kolomensky🇺🇸 · V. Novosad🇺🇸 · T. O'Donnell🇺🇸 · J. L. Ouellet🇺🇸 · J. Pearson🇺🇸 and 10 other authors

   A superconducting Transition-Edge Sensor (TES) with low-$T_c$ is essential in a high resolution calorimetric detection. With a motivation of developing sensitive calorimeters for applications in cryogenic neutrinoless double beta decay searches, we have been investigating methods to reduce the $T_c$ of an Ir film down to 20 mK. Utilizing the proximity effect between a superconductor and a normal metal, we found two room temperature fabrication recipes of making Ir-based low-$T_c$ films. In the first approach, an Ir film sandwiched between two Au films, a Au/Ir/Au trilayer, has a tunable $T_c$ in the range of 20-100 mK depending on the relative thicknesses. In the second approach, a paramagnetic Pt thin film is used to create Ir/Pt bilayer with a tunable $T_c$ in the same range. We present detailed study of fabrication and characterization of Ir-based low-$T_c$ films, and compare the experimental results to theoretical models. We show that Ir-based films with predictable and reproducible critical temperature can be consistently fabricated for use in large scale detector applications.

   ↳ cond-mat.supr-conhep-exnucl-exphysics.ins-detJ.Appl.Phys.(2020)·8 citations
4. 04*

   Pulse Shape Discrimination of CsI(Tl) with a Photomultiplier Tube and MPPCs

   Nguyen V. H. Viet · M. Nomachi🇯🇵 · K. Takahisa🇯🇵 · T. Shima🇯🇵 · B. T. Khai🇯🇵 · R. Takaishi · K. Miyamoto

   In this study, we evaluate and compare the pulse shape discrimination (PSD) performance of multipixel photon counters (MPPCs, also known as silicon photomultiphers - SiPMs) with that of a typical photomultiplier tube (PMT) when testing using CsI(Tl) scintillators. We use the charge comparison method, whereby we discriminate different types of particles by the ratio of charges integrated within two time-gates (the delayed part and the entire digitized waveform). For a satisfactory PSD performance, a setup should generate many photoelectrons (p.e.) and collect their charges efficiently. The PMT setup generates more p.e. than the MPPC setup does. With the same digitizer and the same long time-gate (the entire digitized waveform), the PMT setup is also better in charge collection. Therefore, the PMT setup demonstrates better PSD performance. We subsequently test the MPPC setup using a new data acquisition (DAQ) system. Using this new DAQ, the long time-gate is extended by nearly four times the length when using the previous digitizer. With this longer time-gate, we collect more p.e. at the tail part of the pulse and almost all the charges of the total collected p.e. Thus, the PSD performance of the MPPC setup is improved significantly. This study also provides an estimation of the short time-gate (the delayed part of the digitized waveform) that can give a satisfactory PSD performance without an extensive analysis to optimize this gate.

   ↳ physics.ins-detnucl-exIEEE Trans.Nucl.Sci.(2020)·1 citation
5. 05*

   Semi-classical approaches to heavy-ion reactions: fusion, rainbow, and glory

   L.F. Canto · K. Hagino🇯🇵 · M. Ueda

   A semi-classical approximation has been a powerful tool in understanding the dynamics of low-energy heavy-ion reactions. Here we discuss two topics in this regard, for which Mahir Hussein was a world leading pioneer. The first topic is heavy-ion fusion reactions of neutron-rich nuclei, in which the breakup process of the projectile nucleus plays a crucial role. The second is rainbow and glory scattering, for which characteristic oscillatory patterns in differential cross sections can be well understood in terms of intereferences among several semi-classical trajectories.

   ↳ nucl-thnucl-exEPJA(2021)·7 citations
6. 06*

   Spin-polarized $\beta$-stable neutron star matter: the nuclear symmetry energy and GW170817 constraint

   Ngo Hai Tan🇻🇳 · Dao T. Khoa🇻🇳 · Doan Thi Loan🇻🇳

   Magnetic field of rotating pulsar might be so strong that the equation of state (EOS) of neutron star (NS) matter is significantly affected by the spin polarization of baryons. In the present work, the EOS of the spin-polarized nuclear matter is investigated in the nonrelativistic Hartree-Fock formalism, using a realistic density dependent nucleon-nucleon interaction with its spin and spin-isospin dependence accurately adjusted to the Brueckner-Hartree-Fock results for the spin-polarized nuclear matter. The nuclear symmetry energy and proton fraction are found to increase significantly with the increasing spin polarization of baryons, leading to a larger probability of the direct Urca process in the cooling of magnetar. The EOS of the $\beta$-stable np$e\mu$ matter obtained at different spin polarizations of baryons is used as the input for the Tolman-Oppenheimer-Volkov equations to determine the hydrostatic configuration of NS. Based on the GW170817 constraint on the radius $R_{1.4}$ of NS with $M\approx 1.4_{\odot }$, our mean-field results show that up to $60\%$ of baryons in the NS merger might be spin-polarized. This result supports the magnetar origin of the blue kilonova ejecta of GW170817 suggested by Metzger et al., and the spin polarization of baryons needs, therefore, to be properly treated in the many-body calculation of the EOS of NS matter before comparing the calculated NS mass and radius with those constrained by the multi-messenger GW170817 observation.

   ↳ nucl-thastro-ph.HEnucl-exPRC(2020)·6 citations
7. 07*

   Absolute X-ray energy measurement using a high-accuracy angle encoder

   Takahiko Masuda · Tsukasa Watanabe🇯🇵 · Kjeld Beeks🇦🇹 · Hiroyuki Fujimoto🇯🇵 · Takahiro Hiraki · Hiroyuki Kaino · Shinji Kitao · Yuki Miyamoto · Koichi Okai · Noboru Sasao🇯🇵 · Makoto Seto · Thorsten Schumm🇦🇹 and 7 other authors

   This paper presents an absolute X-ray photon energy measurement method that uses a Bond diffractometer. The proposed system enables the prompt and rapid in-situ measurement of photon energies in a wide energy range. The diffractometer uses a reference silicon single crystal plate and a highly accurate angle encoder called SelfA. We evaluate the performance of the system by repeatedly measuring the energy of the first excited state of the potassium-40 nuclide. The excitation energy is determined as 29829.39(6) eV. It is one order of magnitude more precise than the previous measurement. The estimated uncertainty of the photon energy measurement was 0.7 ppm as a standard deviation and the maximum observed deviation was 2 ppm.

   ↳ physics.ins-detnucl-exJ.Synchrotron Radiat.(2021)·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.