L. Hariasz
P.C.F. Di Stefano
B.C. Rasco
K.P. Rykaczewski
N.T. Brewer
D.W. Stracener
Y. Liu
Z. Gai
C. Rouleau
J. B. Carter
J. Kostensalo
J. Suhonen
H. Davis
E.D. Lukosi
K.C. Goetz
R.K. Grzywacz
M. Mancuso
F. Petricca
A. Fijalkowska
M. Wolinska-Cichocka
J. Ninkovic
P. Lechner
R.B. Ickert
Leah E. Morgan
P.R. Renne
I. Yavin
M. Stukel
2023
<p><span>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 nonzero ratio of intensities of ground-state electron-captures (</span><span id="MathJax-Element-2-Frame" class="mjx-chtml MathJax_CHTML"><span id="MJXc-Node-9" class="mjx-math"><span id="MJXc-Node-10" class="mjx-mrow"><span id="MJXc-Node-11" class="mjx-mrow"><span id="MJXc-Node-12" class="mjx-msub"><span class="mjx-base"><span id="MJXc-Node-13" class="mjx-mrow"><span id="MJXc-Node-14" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">I</span></span></span></span><span class="mjx-sub"><span id="MJXc-Node-15" class="mjx-mrow"><span id="MJXc-Node-16" class="mjx-msup"><span class="mjx-base"><span id="MJXc-Node-17" class="mjx-mrow"><span id="MJXc-Node-18" class="mjx-mi"><span class="mjx-char MJXc-TeX-main-R">EC</span></span></span></span><span class="mjx-sup"><span id="MJXc-Node-19" class="mjx-mrow"><span id="MJXc-Node-20" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">0</span></span></span></span></span></span></span></span></span></span></span></span><span>) over excited-state ones (</span><span id="MathJax-Element-3-Frame" class="mjx-chtml MathJax_CHTML"><span id="MJXc-Node-21" class="mjx-math"><span id="MJXc-Node-22" class="mjx-mrow"><span id="MJXc-Node-23" class="mjx-mrow"><span id="MJXc-Node-24" class="mjx-msub"><span class="mjx-base"><span id="MJXc-Node-25" class="mjx-mrow"><span id="MJXc-Node-26" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">I</span></span></span></span><span class="mjx-sub"><span id="MJXc-Node-27" class="mjx-mrow"><span id="MJXc-Node-28" class="mjx-msup"><span class="mjx-base"><span id="MJXc-Node-29" class="mjx-mrow"><span id="MJXc-Node-30" class="mjx-mi"><span class="mjx-char MJXc-TeX-main-R">EC</span></span></span></span><span class="mjx-sup"><span id="MJXc-Node-31" class="mjx-mrow"><span id="MJXc-Node-32" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">∗</span></span></span></span></span></span></span></span></span></span></span></span><span>) of </span><span id="MathJax-Element-4-Frame" class="mjx-chtml MathJax_CHTML"><span id="MJXc-Node-33" class="mjx-math"><span id="MJXc-Node-34" class="mjx-mrow"><span id="MJXc-Node-35" class="mjx-mrow"><span id="MJXc-Node-36" class="mjx-msub"><span class="mjx-base"><span id="MJXc-Node-37" class="mjx-mrow"><span id="MJXc-Node-38" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">I</span></span></span></span><span class="mjx-sub"><span id="MJXc-Node-39" class="mjx-mrow"><span id="MJXc-Node-40" class="mjx-msup"><span class="mjx-base"><span id="MJXc-Node-41" class="mjx-mrow"><span id="MJXc-Node-42" class="mjx-mi"><span class="mjx-char MJXc-TeX-main-R">EC</span></span></span></span><span class="mjx-sup"><span id="MJXc-Node-43" class="mjx-mrow"><span id="MJXc-Node-44" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">0</span></span></span></span></span></span></span></span><span id="MJXc-Node-45" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">/</span></span><span id="MJXc-Node-46" class="mjx-msub"><span class="mjx-base"><span id="MJXc-Node-47" class="mjx-mrow"><span id="MJXc-Node-48" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">I</span></span></span></span><span class="mjx-sub"><span id="MJXc-Node-49" class="mjx-mrow"><span id="MJXc-Node-50" class="mjx-msup"><span class="mjx-base"><span id="MJXc-Node-51" class="mjx-mrow"><span id="MJXc-Node-52" class="mjx-mi"><span class="mjx-char MJXc-TeX-main-R">EC</span></span></span></span><span class="mjx-sup"><span id="MJXc-Node-53" class="mjx-mrow"><span id="MJXc-Node-54" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">∗</span></span></span></span></span></span></span></span><span id="MJXc-Node-55" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">=</span></span><span id="MJXc-Node-56" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">0.0095</span></span><span id="MJXc-Node-57" class="mjx-mover MJXc-space2"><span class="mjx-stack"><span class="mjx-over"><span id="MJXc-Node-60" class="mjx-mrow"><span id="MJXc-Node-61" class="mjx-mi"><span class="mjx-char MJXc-TeX-main-R">stat</span></span></span></span><span class="mjx-op"><span id="MJXc-Node-58" class="mjx-mrow"><span id="MJXc-Node-59" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">±</span></span></span></span></span></span><span id="MJXc-Node-62" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">0.0022</span></span><span id="MJXc-Node-63" class="mjx-mover MJXc-space2"><span class="mjx-stack"><span class="mjx-over"><span id="MJXc-Node-66" class="mjx-mrow"><span id="MJXc-Node-67" class="mjx-mi"><span class="mjx-char MJXc-TeX-main-R">sys</span></span></span></span><span class="mjx-op"><span id="MJXc-Node-64" class="mjx-mrow"><span id="MJXc-Node-65" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">±</span></span></span></span></span></span><span id="MJXc-Node-68" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">0.0010</span></span></span></span></span></span><span> (68% C.L.), with the null hypothesis rejected at </span><span id="MathJax-Element-5-Frame" class="mjx-chtml MathJax_CHTML"><span id="MJXc-Node-69" class="mjx-math"><span id="MJXc-Node-70" class="mjx-mrow"><span id="MJXc-Node-71" class="mjx-mrow"><span id="MJXc-Node-72" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">4</span></span><span id="MJXc-Node-73" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">σ</span></span></span></span></span></span><span>. In terms of branching ratio, this signal yields </span><span id="MathJax-Element-6-Frame" class="mjx-chtml MathJax_CHTML"><span id="MJXc-Node-74" class="mjx-math"><span id="MJXc-Node-75" class="mjx-mrow"><span id="MJXc-Node-76" class="mjx-mrow"><span id="MJXc-Node-77" class="mjx-msub"><span class="mjx-base"><span id="MJXc-Node-78" class="mjx-mrow"><span id="MJXc-Node-79" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">I</span></span></span></span><span class="mjx-sub"><span id="MJXc-Node-80" class="mjx-mrow"><span id="MJXc-Node-81" class="mjx-msup"><span class="mjx-base"><span id="MJXc-Node-82" class="mjx-mrow"><span id="MJXc-Node-83" class="mjx-mi"><span class="mjx-char MJXc-TeX-main-R">EC</span></span></span></span><span class="mjx-sup"><span id="MJXc-Node-84" class="mjx-mrow"><span id="MJXc-Node-85" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">0</span></span></span></span></span></span></span></span><span id="MJXc-Node-86" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">=</span></span><span id="MJXc-Node-87" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">0.098</span></span><span id="MJXc-Node-88" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">%</span></span><span id="MJXc-Node-89" class="mjx-mover MJXc-space2"><span class="mjx-stack"><span class="mjx-over"><span id="MJXc-Node-92" class="mjx-mrow"><span id="MJXc-Node-93" class="mjx-mi"><span class="mjx-char MJXc-TeX-main-R">stat</span></span></span></span><span class="mjx-op"><span id="MJXc-Node-90" class="mjx-mrow"><span id="MJXc-Node-91" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">±</span></span></span></span></span></span><span id="MJXc-Node-94" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">0.023</span></span><span id="MJXc-Node-95" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">%</span></span><span id="MJXc-Node-96" class="mjx-mover MJXc-space2"><span class="mjx-stack"><span class="mjx-over"><span id="MJXc-Node-99" class="mjx-mrow"><span id="MJXc-Node-100" class="mjx-mi"><span class="mjx-char MJXc-TeX-main-R">sys</span></span></span></span><span class="mjx-op"><span id="MJXc-Node-97" class="mjx-mrow"><span id="MJXc-Node-98" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">±</span></span></span></span></span></span><span id="MJXc-Node-101" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">0.010</span></span><span id="MJXc-Node-102" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">%</span></span></span></span></span></span><span>, roughly half of the commonly used prediction, with consequences for various fields [L. Hariasz </span><i>et al.</i><span>, companion paper, </span><a href="http://dx.doi.org/10.1103/PhysRevC.108.014327" data-mce-href="http://dx.doi.org/10.1103/PhysRevC.108.014327"><span>Phys. Rev. C</span><span> </span><strong>108</strong>, 014327 (2023)</a><span>].</span></p>
application/pdf
10.1103/PhysRevLett.131.052503
en
American Physical Society
Rare 40K decay with implications for fundamental physics and geochronology
article