Mon·May 13, 2024Monday·May 13, 2024

1. 01*

   A practical approach of measuring ${}^{238}$U and ${}^{232}$Th in liquid scintillator to sub-ppq level using ICP-MS

   Yuanxia Li🇨🇳 · Jie Zhao🇨🇳 · Yayun Ding🇨🇳 · Tao Hu🇨🇳 · Jiaxuan Ye🇨🇳 · Jian Fang🇨🇳 · Liangjian Wen🇨🇳

   Liquid scintillator (LS) is commonly utilized in experiments seeking rare events due to its high light yield, transparency, and radiopurity. The concentration of ${}^{238}$U and ${}^{232}$Th in LS consistently remains below 1 ppq (10${}^{-15}$ g/g), and the current screening result is based on a minimum 20-ton detector. Inductively coupled plasma mass (ICP-MS) spectroscopy is well-regarded for its high sensitivity to trace ${}^{238}$U and ${}^{232}$Th. This study outlines a method for detecting ${}^{238}$U and ${}^{232}$Th in LS at the sub-ppq level using ICP-MS, involving the enrichment of ${}^{238}$U/${}^{232}$Th from the LS through acid extraction. With meticulous cleanliness control, ${}^{238}$U/${}^{232}$Th in approximately 2 kg of LS is concentrated by acid extraction with 0.4 (0.3) pg ${}^{238}$U (${}^{232}$Th) contamination. Three standard adding methods are employed to assess recovery efficiency, including radon daughter, 2,5-diphenyloxazole (PPO), and natural non-existent ${}^{233}$U/${}^{229}$Th. The method detection limit at a 99% confidence level of this approach can reach approximately 0.2-0.3 ppq for ${}^{238}$U/${}^{232}$Th with nearly 100% recovery efficiency.

   ↳ physics.ins-detnucl-exRadiat.Phys.Chem.(2025)·5 citations
2. 02*

   Nuclear rainbow of the symmetric nucleus-nucleus system: Interchange of the nearside and farside scattering

   Nguyen Tri Toan Phuc🇻🇳 · Nguyen Hoang Phuc · Dao T. Khoa

   Extensive elastic scattering data measured at energies around 10 to 20 MeV/nucleon for some identical systems, like 12C+12C and 16O+16O, exhibit the nuclear rainbow pattern of broad Airy oscillations of the cross section at medium and large angles. Due to the identity of the scattered projectile and recoiled target, the rainbow pattern at angles around and beyond ${\theta }_{c.m.}\approx 90^{\circ }$ is strongly deteriorated by the boson exchange. The nuclear rainbow features in the identical-particles elastic scattering discussed so far are based on the nearside-farside (NF) decomposition of the scattering amplitude given by an optical model calculation neglecting the projectile-target exchange symmetry. Moreover, the NF decomposition method was developed in the 70s by Fuller for nonidentical systems only, and the details of how the exchange symmetry of an identical system affects the evolution of nuclear rainbow remain unexplored. Therefore, the Fuller method is generalized in this work for the elastic scattering of two identical (spin-zero) nuclei, with the projectile-target exchange symmetry taken explicitly into account. The results obtained for elastic 12C+12C and 16O+16O scattering at low energies show the exchange symmetry results in a symmetric interchange of the nearside and farside patterns at angles passing ${\theta }_{c.m.}=90^{\circ }$, which requires a more subtle interpretation of nuclear rainbow. We also found that a similar NF interchange occurs in a nonidentical nucleus-nucleus system with the core-core symmetry, where the elastic cross section at backward angles is due mainly to the elastic transfer of cluster or nucleon between two identical cores. This interesting effect is illustrated in the elastic 16O+12C scattering at low energies where the elastic $\alpha$ transfer between two 12C cores has been proven to enhance the elastic cross section at backward angles.

   ↳ nucl-thnucl-exPRC(2024)·3 citations
3. 03*

   Solar fusion III: New data and theory for hydrogen-burning stars

   B. Acharya🇺🇸 · M. Aliotta🇬🇧 · A. B. Balantekin🇺🇸 · D. Bemmerer🇩🇪 · C. A. Bertulani🇺🇸 · A. Best🇮🇹 · C. R. Brune🇲🇽 · R. Buompane🇮🇹 · F. Cavanna🇮🇹 · J. W. Chen🇹🇼 · J. Colgan🇺🇸 · A. Czarnecki🇨🇦 and 38 other authors

   In stars that lie on the main sequence in the Hertzsprung-Russel diagram, like our sun, hydrogen is fused to helium in a number of nuclear reaction chains and series, such as the proton-proton chain and the carbon-nitrogen-oxygen cycles. Precisely determined thermonuclear rates of these reactions lie at the foundation of the standard solar model. This review, the third decadal evaluation of the nuclear physics of hydrogen-burning stars, is motivated by the great advances made in recent years by solar neutrino observatories, putting experimental knowledge of the proton-proton chain neutrino fluxes in the few-percent precision range. The basis of the review is a one-week community meeting held in July 2022 in Berkeley, California, and many subsequent digital meetings and exchanges. The relevant reactions of solar and stellar hydrogen burning are reviewed here, from both theoretical and experimental perspectives. Recommendations for the state of the art of the astrophysical S-factor and its uncertainty are formulated for each of them. Several other topics of paramount importance for the solar model are reviewed, as well: recent and future neutrino experiments, electron screening, radiative opacities, and current and upcoming experimental facilities. In addition to reaction-specific recommendations, also general recommendations are formed.

   ↳ astro-ph.SRastro-ph.HEnucl-exnucl-thRMP(2025)·47 citations
4. 04*

   Data Reduction for Low Energy Nuclear Physics Experiments Using Data Frames

   Caleb Marshall🇺🇸

   Low energy nuclear physics experiments are transitioning towards fully digital data acquisition systems. Realizing the gains in flexibility afforded by these systems relies on equally flexible data reduction techniques. In this paper, methods utilizing data frames and in-memory techniques to work with data, including data from self-triggering, digital data acquisition systems, are discussed within the context of a Python package, \texttt{sauce}. It is shown that data frame operations can encompass common analysis needs and allow interactive data analysis. Two event building techniques, dubbed referenced and referenceless event building, are shown to provide a means to transform raw list mode data into correlated multi-detector events. These techniques are demonstrated in the analysis of two example data sets.

   ↳ physics.data-annucl-exphysics.ins-detSciPost Phys.Codeb.(2024)·1 citation

* 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.