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SUMMARY:KDK: Measuring the unique third forbidden electron capture decay o
 f K-40 for backgrounds in rare-event searches
DTSTART;VALUE=DATE-TIME:20210831T154500Z
DTEND;VALUE=DATE-TIME:20210831T160000Z
DTSTAMP;VALUE=DATE-TIME:20260618T075940Z
UID:indico-contribution-15842@indico.ific.uv.es
DESCRIPTION:Speakers: Matthew Stukel (Queen's University)\nPotassium-40 (K
 -40) is a long-lived\, naturally occurring radioactive isotope. The decay 
 products are prominent backgrounds for many rare event searches\, especial
 ly those involving NaI-based scintillators (ex. DAMA\, ANAIS-112\, COSINE-
 100\, SABRE\, COSINUS etc.). The branching ratio of the electron capture d
 irectly to the ground state of Argon-40 has never been experimentally meas
 ured and presents an unknown background directly in the 2-6 keV energy reg
 ion. This is the same region where the DAMA/LIBRA experiment observes thei
 r unique annual modulation. Knowledge of this branching ratio can place co
 nstraints on the allowed modulation fraction observed by the DAMA experime
 nt. In addition\, this branching ratio has important implications for nucl
 ear physics and geochronology. KDK (Potassium (K) Decay (DK)) is an intern
 ational collaboration dedicated to the measurement of this branching ratio
 . The experiment is performed using a silicon drift detector with a therma
 lly deposited\, enriched K-40 source inside the Modular Total Absorption S
 pectrometer (MTAS\, Oak Ridge National Laboratory). MTAS is a large NaI de
 tector whose high gamma-ray efficiency enables the proper discrimination b
 etween ground and excited state electron capture events. This setup has be
 en characterized in terms of energy calibration and dead time\, and a tagg
 ing efficiency of 97.89(6) % has been demonstrated (arXiv:2012.15232 submi
 tted to NIM). We report on the analysis method and sensitivity for a 44-da
 y K-40 physics run.\n\nhttps://indico.ific.uv.es/event/6178/contributions/
 15842/
LOCATION:
URL:https://indico.ific.uv.es/event/6178/contributions/15842/
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