Thu·Jun 15, 2023Thursday·June 15, 2023

1. 01*

   Core States of Neutron Stars from Anatomizing their Scaled Structure Equations

   Bao-Jun Cai🇨🇳 · Bao-An Li🇺🇸 · Zhen Zhang🇨🇳

   Given an Equation of State (EOS) for neutron star (NS) matter, there is a unique mass-radius sequence characterized by a maximum mass $M_{\mathrm{NS}}^{\max }$ at radius $R_{\max }$. We first show analytically that the $M_{\mathrm{NS}}^{\max }$ and $R_{\max }$ scale linearly with two different combinations of NS central pressure $P_{\mathrm{c}}$ and energy density ${\epsilon }_{\mathrm{c}}$ by dissecting perturbatively the dimensionless Tolman-Oppenheimer-Volkoff (TOV) equations governing NS internal variables. The scaling relations are then verified via 87 widely used and rather diverse phenomenological as well as 17 microscopic NS EOSs with/without considering hadron-quark phase transitions and hyperons by solving numerically the original TOV equations. The EOS of densest NS matter allowed before it collapses into a black hole (BH) is then obtained. Using the universal $M_{\mathrm{NS}}^{\max }$ and $R_{\max }$ scalings and NICER (Neutron Star Interior Composition Explorer) and XMM-Newton mass-radius observational data for PSR J0740+6620, a very narrow constraining band on the NS central EOS is extracted directly from the data for the first time without using any specific input EOS model.

   ↳ nucl-thastro-ph.HEnucl-exApJ(2023)·24 citations
2. 02*

   Energy Calibration of Germanium Detectors for the MAJORANA DEMONSTRATOR

   I.J. Arnquist🇺🇸 · F.T. Avignone III🇺🇸 · A.S. Barabash🇷🇺 · C.J. Barton🇺🇸 · K.H. Bhimani🇺🇸 · E. Blalock🇺🇸 · B. Bos🇺🇸 · M. Busch🇺🇸 · M. Buuck🇺🇸 · T.S. Caldwell🇺🇸 · Y-D. Chan🇺🇸 · C.D. Christofferson🇺🇸 and 44 other authors

   The MAJORANA DEMONSTRATOR was a search for neutrinoless double-beta decay ($0\nu \beta \beta$) in the ${}^{76}$Ge isotope. It was staged at the 4850-foot level of the Sanford Underground Research Facility (SURF) in Lead, SD. The experiment consisted of 58 germanium detectors housed in a low background shield and was calibrated once per week by deploying a ${}^{228}$Th line source for 1 to 2 hours. The energy scale calibration determination for the detector array was automated using custom analysis tools. We describe the offline procedure for calibration of the Demonstrator germanium detectors, including the simultaneous fitting of multiple spectral peaks, estimation of energy scale uncertainties, and the automation of the calibration procedure.

   ↳ physics.ins-detnucl-exJINST(2023)·13 citations
3. 03*

   Neutronic Chain Reactions for Polonium-210 Production

   Solomon Lim🇰🇷

   The production of the industrially significant radionuclide polonium-210 from the neutron irradiation of bismuth metal and the subsequent beta decay of bismuth-210 is highly inefficient due to the small neutron capture cross section of bismuth-209. In this paper, we report a previously undescribed self-sustaining nuclear chain reaction involving self-propagating neutron multiplication in bismuth salts that allow for rapid and cost-effective production of polonium- 210. The reaction proceeds in a cycle of three alternating elementary steps - the capture of neutrons by bismuth-209 and the subsequent formation of polonium-210, the emission of high-energy alpha particles by polonium-210, and the production of more neutrons from (alpha,n) and (n,2n) reactions on light element and bismuth-209 nuclei respectively. The chain reaction was proven to have successfully occurred by irradiating a sample of the bismuth salt with a 80 microcurie neutron source and monitoring the activity levels of the reaction. It was found that the activity of the reaction increased exponentially after an initial stable period following a derived formula for polonium production trends for the reaction, thus validating the occurrence of the reaction. Furthermore, alpha spectroscopy confirmed that polonium-210 had been produced by characterising the 5.30 MeV alpha emission peak of the reaction in addition to using beta spectroscopy to identify the parent nuclide bismuth-210, further proving that the reaction was successful.

   ↳ physics.ins-detnucl-ex0 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.