Wed·Nov 18, 2020Wednesday·November 18, 2020

1. 01*

   Combinative Isobaric Resonances CIRs by MSS and from previous precise data

   A. Gafarov

   The elastic scattering {12}^C(p,p{o}_) Excitation Function (EF) was measured in the energy range Ep =16 - 19.5 MeV with resolution about 10 keV by means of innovative approach - MSS - the Method of Spectra Superposition at the 14-angle Magnetic Spectrograph (Apelsin) at beam with an energy spread of about 200 keV from U-150 cyclotron of INP Ulugbek (Tashkent) of Science Academy of Uzbekistan [1-9]. The obtained EF has a reach structure of anomalies in precise agreement with thresholds and levels data [2,10-12]. Measurements were done on the {12}^C self-supporting target with thickness 13 mg/cm2 and an area of 1 cm2 in the center of Apelsin. The 20-step Energy Moderator controlled the proton energy, providing a 3.5 MeV wide Ep interval with no readjustment of cyclotron and all the ionic-optics on the 41-meter-long beam-pipe. Energy resolution of Apelsin for protons is better than 5 keV. The spectrograph magnetic field was stabilized to 3ppm by NMR-monitor system [1,9]. The EF of {12}^C (p,p{o}_) scattering has many resonances that precisely correspond to g.s. and levels of well-known product-nuclei. But 80% of anomalies were not decoded. A new concept of Combinative Isobaric Resonance (CIRs) proposed to identify these anomalies. The proposed CIRs concept worked very promising (Fig. 4). To prove CIRs validity, precise excitation function of {12}^C(p,p{o}_), {12}^C(d,d{o}_), and {7}^Li(p,p{o}_), were analyzed in search for the Combinative Isobaric Resonances. This study perfectly proves existence of CIRs.

   nucl-exastro-ph.SR0 citations
2. 02*

   Rotational bands beyond the Elliott model

   Ryan Zbikowski · Calvin W. Johnson🇺🇸 · Anna E. McCoy🇨🇦 · Mark A. Caprio🇺🇸 · Patrick J. Fasano🇺🇸

   Rotational bands are commonplace in the spectra of atomic nuclei. Inspired by early descriptions of these bands by quadrupole deformations of a liquid drop, Elliott constructed a discrete nucleon representations of $\mathrm{SU}(3)$ from fermionic creation and annihilation operators. Ever since, Elliott's model has been foundational to descriptions of rotation in nuclei. Later work, however, suggested the symplectic extension $\mathrm{Sp}(3,R)$ provides a more unified picture. We decompose no-core shell-model nuclear wave functions into symmetry-defined subspaces for several beryllium isotopes, as well as ${}^{20}$Ne, using the quadratic Casimirs of both Elliott's $\mathrm{SU}(3)$ and $\mathrm{Sp}(3,R)$. The band structure, delineated by strong $B(E2)$ values, has a more consistent description in $\mathrm{Sp}(3,R)$ rather than $\mathrm{SU}(3)$. {In particular, we confirm previous work finding in some nuclides strongly connected upper and lower bands with the same underlying symplectic structure.

   ↳ nucl-thnucl-exJ.Phys.G(2021)·7 citations
3. 03*

   A study of DC electrical breakdown in liquid helium through analysis of the empirical breakdown field distributions

   N. S. Phan🇺🇸 · W. Wei🇺🇸 · B. Beaumont🇺🇸 · N. Bouman🇺🇸 · S. M. Clayton🇺🇸 · S. A. Currie🇺🇸 · T. M. Ito🇺🇸 · J. C. Ramsey🇺🇸 · G. M. Seidel🇺🇸

   We report results from a study on electrical breakdown in liquid helium using near-uniform-field stainless steel electrodes with a stressed area of $\sim$0.725 cm${}^2$. The distribution of the breakdown field is obtained for temperatures between 1.7 K and 4.0 K, pressures between the saturated vapor pressure and 626 Torr, and with electrodes of different surface polishes. A data-based approach for determining the electrode-surface-area scaling of the breakdown field is presented. The dependence of the breakdown probability on the field strength as extracted from the breakdown field distribution data is used to show that breakdown is a surface phenomenon closely correlated with Fowler-Nordheim field emission from asperities on the cathode. We show that the results from this analysis provides an explanation for the supposed electrode gap-size effect and also allows for a determination of the breakdown-field distribution for arbitrary shaped electrodes. Most importantly, the analysis method presented in this work can be extended to other noble liquids to explore the dependencies for electrical breakdown in those media.

   ↳ physics.ins-dethep-exnucl-exphysics.app-ph+1J.Appl.Phys.(2021)·13 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.