학술논문
Rare $^{40}$K decay with implications for fundamental physics and geochronology
Document Type
Working Paper
Author
Stukel, M.; Hariasz, L.; Di Stefano, P. C. F.; Rasco, B. C.; Rykaczewski, K. P.; Brewer, N. T.; Stracener, D. W.; Liu, Y.; Gai, Z.; Rouleau, C.; Carter, J.; Kostensalo, J.; Suhonen, J.; Davis, H.; Lukosi, E. D.; Goetz, K. C.; Grzywacz, R. K.; Mancuso, M.; Petricca, F.; Fijałkowska, A.; Wolińska-Cichocka, M.; Ninkovic, J.; Lechner, P.; Ickert, R. B.; Morgan, L. E.; Renne, P. R.; Yavin, I.
Source
Physical Review Letters, 131-052503 (2023)
Subject
Language
Abstract
Potassium-40 is a widespread, naturally occurring isotope whose radioactivity impacts subatomic rare-event searches, nuclear structure theory, and estimated geological ages. A predicted electron-capture decay directly to the ground state of argon-40 has never been observed. The KDK (potassium decay) collaboration reports strong evidence of this rare decay mode. A blinded analysis reveals a non-zero ratio of intensities of ground-state electron-captures ($I_{\text{EC}^0}$) over excited-state ones ($I_\text{EC*}$) of $ I_{\text{EC}^0} / I_\text{EC*} = 0.0095 \stackrel{\text{stat}}{\pm} 0.0022 \stackrel{\text{sys}}{\pm} 0.0010 $ (68% C.L.), with the null hypothesis rejected at 4$\sigma$. In terms of branching ratio, this signal yields $I_{\text{EC}^0} = 0.098\% \stackrel{\text{stat}}{\pm} 0.023\% \stackrel{\text{sys}}{\pm} 0.010\% $, roughly half of the commonly used prediction, with consequences for various fields [L. Hariasz et al., companion paper, DOI: 10.1103/PhysRevC.108.014327].
Comment: This is a companion paper to Hariasz et al (KDK collaboration) "Evidence for ground-state electron capture of ${}^{40}$K" [arXiv:2211.10343; DOI: 10.1103/PhysRevC.108.014327]. As such, both texts share some figures and portions of text. This version includes the journal DOI
Comment: This is a companion paper to Hariasz et al (KDK collaboration) "Evidence for ground-state electron capture of ${}^{40}$K" [arXiv:2211.10343; DOI: 10.1103/PhysRevC.108.014327]. As such, both texts share some figures and portions of text. This version includes the journal DOI