Search for Majoron-emitting modes of $^{136}$Xe double beta decay with the complete EXO-200 dataset
Abstract
A search for Majoron-emitting modes of the neutrinoless double-beta decay of $^{136}$Xe is performed with the full EXO-200 dataset. This dataset consists of a total $^{136}$Xe exposure of 234.1 kg$\cdot$yr, and includes data with detector upgrades that have improved the energy threshold relative to previous searches. A lower limit of T${1/2}^{\rm{^{136}Xe}}>$4.3$\cdot$10$^{24}$ yr at 90% C.L. on the half-life of the spectral index $n=1$ Majoron decay was obtained, a factor of 3.6 more stringent than the previous limit from EXO-200, corresponding to a constraint on the Majoron-neutrino coupling constant of $|\langle g{ee}^{M}\rangle|$$<(0.4$-$0.9)\cdot10^{-5}$. The lower threshold and the additional data taken resulted in a factor 8.4 improvement for the $n=7$ mode compared to the previous EXO search. This search provides the most stringent limits to-date on the Majoron-emitting decays of $^{136}$Xe with spectral indices $n=1,2,3,$ and 7.
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Scholars@Duke
Phillip S. Barbeau
Professor Barbeau’s research interests are predominantly in the fields of neutrino and astroparticle physics. His efforts are focused on (but not limited to) three major areas of research: studying the physics of coherent neutrino-nucleus scattering; novel searches for the dark matter in our universe; and searches for zero neutrino double beta decay. The unifying aspect of the work is the common need for new and creative detector development in order to solve some of the “hard” problems in low-background rare-event detection.
Jens Dilling
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