Fri·Aug 4, 2023Friday·August 4, 2023

1. 01*

   Long term experience with perfluorobutane in COMPASS RICH

   F.Bradamante🇮🇹 · A. Bressan🇮🇹 · A. Cicuttin🇮🇹 · M. L. Crespo🇮🇹 · C. Chatterjee🇮🇹 · P. Ciliberti🇮🇹 · S. Dalla Torre🇮🇹 · W. Florian🇮🇹 · L. Garcia Ordonez🇮🇹 · M. Gregori🇮🇹 · A. Kerbizi🇮🇹 · S. Levorato🇮🇹 and 7 other authors

   COMPASS RICH-1 has used high-purity perfluorobutane as radiator gas since 2001. The operation and control of the radiator gas has evolved over years with continuous improvements. We report on the experience gained in the 20 year-long operation of perfluorobutane as COMPASS RICH radiator. Very accurate values for the radiator gas refractive index are needed for high-performance particle identification. The procedure has evolved over years and the one presently in use, which provides refractive index estimate at the 1 ppm level, is discussed. Perfluorobutane procurement is becoming challenging, and the minimization of material waste is now a priority for the protection of the environment. Commercially available perfluorobutane needs dedicated filtering before usage and typical material losses in the filtering procedure were around 30%. Recent efforts allowed us to reduce them to about 5%. A potential alternative to fluorocarbon radiators in gaseous RICHes is also presented.

   ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2023)·1 citation
2. 02*

   Production and chemical separation of ${}^{229}$Pa toward observation of $\gamma$ rays of ${}^{229\mathrm{m}}$Th

   Yudai Shigekawa · Xiaojie Yin🇨🇳 · Akihiro Nambu · Yang Wang🇨🇳 · Hiromitsu Haba🇯🇵

   To observe the $\gamma$ rays emitted from the low-lying isomeric state of ${}^{229}$Th (${}^{229\mathrm{m}}$Th), we aim to dope fluoride crystals with its precursor ${}^{229}$Pa. In this study, we produced ${}^{229}$Pa by a 30-MeV proton bombardment on ${}^{232}$Th and developed a chemical separation method. The chemical yield of Pa was 93(4)%, and the physical production yield of ${}^{229}$Pa for the proton energy range of 29.0$-$30.1 MeV was measured to be 9.4(8) MBq/$\mu$Ah, which was more than 10 times higher than those of ${}^{232,230,228,233}$Pa. These high chemical and production yields will allow us to prepare fluoride crystals having a sufficient amount of ${}^{229}$Pa for the observation of the $\gamma$ rays of ${}^{229\mathrm{m}}$Th.

   ↳ physics.ins-detnucl-exJ.Radioanal.Nucl.Chem.(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.