2014/09/23 by R.J. de Meijer, de Meijer, R. J., Steph Steyn +1
Physics and Astronomy · #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Instrumentation and Detectors (physics.ins-det) #Neutrino Physics Research #Nuclear Experiment (nucl-ex) #Radioactive Decay and Measurement Techniques #Scientific Research and Discoveries
paper · pdf · doi:10.48550/arxiv.1409.6969
openalex publication_date 2014/09/23 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
In this paper we present results of a long-term observation of the decay of 22Na in the presence of a nuclear fission reactor. The measurements were made outside the containment wall of and underneath the Koeberg nuclear power plant near Cape Town, South Africa. Antineutrino fluxes ranged from ~5*1011 to 1.6*1013 cm-2 s-1 during this period. We show that the coincidence summing technique provides a sensitive tool to measure a change in the total decay constant as well as the branching ratio between EC and beta+ decay of 22Na to the first excited state in 22Ne. We observe a relative change in count rate between reactor-ON and reactor-OFF equal to (-0.51+/-0.11)*10-4. After evaluating possible systematic uncertainties we conclude that the effect is either due to a hidden instrumental cause or due to an interaction between antineutrinos and the 22Na nucleus. An upper limit of ~0.03 barn has been deduced for observing any change in the decay rate of 22Na due to antineutrino interactions.