Mon·Jun 12, 2023Monday·June 12, 2023

1. 01*

   Measurement of polarization transfer in the quasi-elastic ${}^{40}\mathrm{Ca}(\vec{e},e^{\prime }\vec{p})$ process

   T. Kolar🇮🇱 · P. Achenbach🇩🇪 · M. Christmann🇩🇪 · M. O. Distler🇩🇪 · L. Doria🇩🇪 · P. Eckert🇩🇪 · A. Esser🇩🇪 · C. Giusti🇮🇹 · J. Geimer🇩🇪 · P. Gülker🇩🇪 · M. Hoek🇩🇪 · P. Klag🇩🇪 and 23 other authors

   Polarization transfer to a bound proton in polarized electron knock-out reactions, $\mathrm{A}(\vec{e},e^{\prime }\vec{p})$, is a powerful tool to look for in-medium modification of the bound proton. It requires comparison to calculations which consider the many-body effects accompanying the quasi-free process. We report here measured components $P_x^{\prime }$, $P_z^{\prime }$, and their ratio $P_x^{\prime }/P_z^{\prime }$, of polarization transfer to protons bound in ${}^{40}\mathrm{Ca}$, which is described well by the shell model and for which reliable calculations are available. While the calculations capture the essence of the data, our statistical precision allows us to observe deviations which cannot be explained by simple scaling, including by varying the proton electromagnetic form factor ratio $G_E/G_M$. We further explore the deviations of the ratio of the polarization transfer components from that of a free proton, $(P_x^{\prime }/P_z^{\prime }{)}_{\mathrm{A}}/(P_x^{\prime }/P_z^{\prime }{)}_{\mathrm{H}}$, and its dependence on the bound-proton virtuality.

   nucl-exPLB(2023)·6 citations
2. 02*

   Characterization of a ${}^{220}$Rn source for low-energy electronic recoil calibration of the XENONnT detector

   Florian Jörg🇩🇪 · Shengchao Li🇺🇸 · Jochen Schreiner🇩🇪 · Hardy Simgen🇩🇪 · Rafael F. Lang🇺🇸

   Low-background liquid xenon detectors are utilized in the investigation of rare events, including dark matter and neutrinoless double beta decay. For their calibration, gaseous ${}^{220}$Rn can be used. After being introduced into the xenon, its progeny isotope ${}^{212}$Pb induces homogeneously distributed, low-energy ($<30$ keV) electronic recoil interactions. We report on the characterization of such a source for use in the XENONnT experiment. It consists of four commercially available ${}^{228}$Th sources with an activity of 55 kBq. These sources provide a high ${}^{220}$Rn emanation rate of about 8 kBq. We find no indication for the release of the long-lived ${}^{228}$Th above 1.7 mBq. Though an unexpected ${}^{222}$Rn emanation rate of about 3.6 mBq is observed, this source is still in line with the requirements for the XENONnT experiment.

   ↳ physics.ins-detastro-ph.IMnucl-exJINST(2023)·10 citations
3. 03*

   NuCLR: Nuclear Co-Learned Representations

   Ouail Kitouni🇺🇸 · Niklas Nolte · Sokratis Trifinopoulos🇺🇸 · Subhash Kantamneni · Mike Williams🇺🇸

   We introduce Nuclear Co-Learned Representations (NuCLR), a deep learning model that predicts various nuclear observables, including binding and decay energies, and nuclear charge radii. The model is trained using a multi-task approach with shared representations and obtains state-of-the-art performance, achieving levels of precision that are crucial for understanding fundamental phenomena in nuclear (astro)physics. We also report an intriguing finding that the learned representation of NuCLR exhibits the prominent emergence of crucial aspects of the nuclear shell model, namely the shell structure, including the well-known magic numbers, and the Pauli Exclusion Principle. This suggests that the model is capable of capturing the underlying physical principles and that our approach has the potential to offer valuable insights into nuclear theory.

   ↳ nucl-thcs.LGnucl-ex2 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.