Fri·Oct 16, 2020Friday·October 16, 2020

1. 01*

   Effects of Magnetic Fields on HPGe Tracking Detectors

   I. Y. Lee🇺🇸 · A. O. Macchiavelli🇺🇸

   We present a study of magnetic fields effects on the position resolution and energy response of hyper-pure germanium detectors. Our results provide realistic estimates of the potential impact on the resolving power of tracking-arrays from (fringe) magnetic fields present when operating together with large spectrometers. By solving the equations of motion for the electron and holes in the presence of both electric and magnetic fields, we analyzed the drift trajectories of the charge carriers to determine the deviations in the positions at the end point of the trajectories, as well as changes in drift lengths affecting the energy resolution and peak shift due to trapping. Our results show that the major effect is in the deviation of the transverse (to the electric field direction) position and suggest that, if no corrective action is taken in the pulse-shape and tracking data analysis procedures, a field strength $\gtrsim$ 0.1 T will start to impact the intrinsic position resolution of 2 mm (RMS). At fields above $\sim$1 T, the degradation of the energy response becomes observable.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2021)·0 citations
2. 02*

   Homogeneity of neutron transmission imaging over a large sensitive area with a four-channel superconducting detector

   The Dang Vu🇯🇵 · Hiroaki Shishido🇯🇵 · Kenji M. Kojima🇨🇦 · Tomio Koyama🇯🇵 · Kenichi Oikawa🇯🇵 · Masahide Harada🇯🇵 · Shigeyuki Miyajima🇯🇵 · Takayuki Oku🇯🇵 · Kazuhiko Soyama🇯🇵 · Kazuya Aizawa🇯🇵 · Mutsuo Hidaka🇯🇵 · Soh Y. Suzuki🇯🇵 and 4 other authors

   We previously proposed a method to detect neutrons by using a current-biased kinetic inductance detector (CB-KID), where neutrons are converted into charged particles using a 10B conversion layer. The charged particles are detected based on local changes in kinetic inductance of X and Y superconducting meanderlines under a modest DC bias current. The system uses a delay-line method to locate the positions of neutron-10B reactions by acquiring the four arrival timestamps of signals that propagate from hot spots created by a passing charged particle to the end electrodes of the meanderlines. Unlike conventional multi-pixel imaging systems, the CB-KID system performs high spatial resolution imaging over a 15 mm x 15 mm sensitive area using only four channel readouts. Given the large sensitive area, it is important to check the spatial homogeneity and linearity of detected neutron positions when imaging with CB-KID. To this end we imaged a pattern of 10B dot absorbers with a precise dot pitch to investigate the spatial homogeneity of the detector. We confirmed the spatial homogeneity of detected dot positions based on the distribution of measured dot pitches across the sensitive area of the detector. We demonstrate potential applications of the system by taking a clear transmission image of tiny metallic screws and nuts and a ladybug. The image was useful for characterizing the ladybug noninvasively. Detection efficiencies were low when the detector was operated at 4 K, so we plan to explore raising the operating temperature towards the critical temperature of the detector as a means to improve counting rates.

   ↳ physics.ins-detnucl-exSupercond.Sci.Technol.(2021)·3 citations
3. 03*

   QCD and the Strange Baryon Spectrum

   Tetsuo Hyodo🇯🇵 · Masayuki Niiyama🇯🇵

   The strange quark plays a unique role in QCD, reflecting its intermediate mass between the light and heavy quarks. In recent years, remarkable progress has been made in the spectroscopy of baryons with strangeness. Many new features of the strange baryon spectrum have been revealed by accurate experimental data with novel techniques, as well as systematic developments of theoretical framework to describe hadron resonances. The basic properties of strange baryons, namely, the pole positions, spin and parity, and decay branching ratios, are being determined accurately. As a consequence, the Particle Data Group have added new entries in the particle listings, such as the $\Lambda (1380)$ and the $\Omega (2012)$. The developments of the spectroscopy stimulate intensive discussion on the exotic internal structure of strange baryons beyond the ordinary three-quark configuration. In this review, we introduce the basics of QCD, the scattering theory, and the exotic internal structure of hadrons, emphasizing the importance of the pole positions of the scattering amplitude for the characterization of hadron resonances. We then summarize the current status of selected strange baryon resonances; $\Lambda (1405)$, $\Lambda (1670)$, $\Xi (1620)$, $\Xi (1690)$, and $\Omega (2012)$, from theoretical and experimental viewpoints.

   ↳ hep-phhep-exnucl-exnucl-thPPNP(2021)·88 citations
4. 04*

   Sensitivity of transfer cross sections to the bound-state wave functions

   Shubhchintak🇧🇪 · P. Descouvemont🇧🇪

   We test the sensitivity of transfer reactions to the bound state wave functions within a distorted wave Born approximation formalism. Using supersymmetric transformations, we remove the Pauli-forbidden states from the two-body potentials and generate an equivalent supersymmetric partner. Wave functions from these potentials have the same asymptotics, but they differ in the nuclear interior. This allows us to study the influence of the nuclear interior on transfer cross sections. We apply the calculations to the ${}^{16}$O($d,p$)${}^{17}$O and ${}^{12}$C(${}^7$Li, $t$)${}^{16}$O reactions, which are typical examples of nucleon and $\alpha$ transfer, respectively. The spectroscopic factors for ${}^{17}$O are decreased by about 30\% when using supersymmetric potentials. For ${}^{16}$O, the differences are smaller. However, we show that ambiguities exist in the determination of the spectroscopic factors, due to the choice of the angular range where the fit is performed.

   ↳ nucl-thnucl-exPLB(2020)·9 citations
5. 05*

   Nuclear collective dynamics in transport model with the lattice Hamiltonian method

   Rui Wang · Zhen Zhang🇨🇳 · Lie-Wen Chen🇨🇳 · Yu-Gang Ma🇨🇳

   We review the recent progress on studying the nuclear collective dynamics by solving the Boltzmann-Uehling-Uhlenbeck (BUU) equation with the lattice Hamiltonian method treating the collision term by the full-ensemble stochastic collision approach. This lattice BUU (LBUU) method has recently been developed and implemented in a GPU parallel computing technique, and achieves a rather stable nuclear ground-state evolution and high accuracy in evaluating the nucleon-nucleon (NN) collision term. This new LBUU method has been applied to investigate the nuclear isoscalar giant monopole resonances and isovector giant dipole resonances. While the calculations with the LBUU method without the NN collision term (i.e., the lattice Hamiltonian Vlasov method) describe reasonably the excitation energies of nuclear giant resonances, the full LBUU calculations can well reproduce the width of the giant dipole resonance of ${}^{208}$Pb by including a collisional damping from NN scattering. The observed strong correlation between the width of nuclear giant dipole resonance and the NN elastic cross section suggests that the NN elastic scattering plays an important role in nuclear collective dynamics, and the width of nuclear giant dipole resonance provides a good probe of the in-medium NN elastic cross section.

   ↳ nucl-thastro-ph.HEnucl-exFront.in Phys.(2020)·15 citations
6. 06*

   Improving Calibration of the Large Low-Background Proportional Counter

   O.D.Petrenko · A.M.Gangapshev · Yu.M.Garilyuk · V.V.Kazalov · V.V.Kuzminov · S.I.Panasenko · S.S.Ratkevich · D.A.Tekueva

   The study of low-yield effects requires not only good quality of the original data but also puts high requirements for their processing procedures to increase the efficiency of the selection of useful events. The exploiting of the large cylindrical proportional counter's electrostatic topology allows improving the extrapolation of information about the primary ionization of a multipoint event. Long-term calibration measurements with an external ${}^{109}$Cd-source allowed the development of a new method for analyzing the pulse shape from a sizeable proportional counter. Optimized analysis of the current's pulse shape from the electron cloud of primary ionization in the counter improved the resolution and energy calibration. As a result, the efficiency of selecting useful events was increased by 25\%.

   ↳ physics.ins-detnucl-exJ.Phys.Conf.Ser.(2020)·0 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.