A search for the neutrinoless quadruple beta decay of 136Xe was conducted with the liquid-xenon detector XMASS-I using 327 kg ×800.0 days of the exposure. The pulse shape discrimination based on the scintillation decay time constant which distinguishes γ-rays including the signal and β-rays was used to enhance the search sensitivity. No significant signal excess was observed from the energy spectrum fitting with precise background evaluation, and we set a lower limit of the half life of 3.7 × 1024 years at 90% confidence level. This is the first experimental constraint of the neutrinoless quadruple beta decay of 136Xe.
|Journal||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|Publication status||Published - 2022 Oct 10|
- Liquid xenon
- Low background
- Neutrinoless-quadruple beta decay
ASJC Scopus subject areas
- Nuclear and High Energy Physics