Observation of Low-Lying Isomeric States in 136Cs: A New Avenue for Dark Matter and Solar Neutrino Detection in Xenon Detectors

We report on new measurements establishing the existence of low-lying isomeric states in 136Cs using y rays produced in 136Xe(p; n)136Cs reactions. Two states with O(100) ns lifetimes are placed in the decay sequence of the 136Cs levels that are populated in charged-current interactions of solar neutrinos and fermionic dark matter with 136Xe. Xenon-based experiments can therefore exploit a delayed-coincidence tag of these interactions, greatly suppressing backgrounds to enable spectroscopic studies of solar neutrinos and dark matter.

Automated summary

We present measurements showing the existence of low-lying isomeric states in 136Cs using y rays generated from 136Xe(p; n)136Cs reactions. Two states with lifetimes of around O(100) ns are identified in the decay sequence of 136Cs levels, which are populated through charged-current interactions of solar neutrinos and fermionic dark matter with 136Xe. This discovery enables xenon-based experiments to effectively suppress backgrounds and conduct spectroscopic studies of solar neutrinos and dark matter.