Search for tri-nucleon decays of Ge in GERDA

Area of Science:

• Nuclear Physics
• Particle Physics
• Astroparticle Physics

Background:

• Tri-nucleon decays are rare, exotic nuclear processes.
• Understanding these decays provides insights into fundamental nuclear forces.
• Previous experimental limits on these decays were less stringent.

Purpose of the Study:

• To search for tri-nucleon decays of Germanium-76.
• To set new limits on the decay widths and lifetimes of these processes.
• To improve upon existing experimental constraints.

Main Methods:

• Analysis of data from the GERmanium Detector Array (GERDA) experiment.
• Exclusion of decays populating excited states above particle emission threshold.
• Targeted search for specific decay channels (ppp-, ppn-, pnn-, nnn-) and the subsequent decay of Gallium-70.
• Statistical analysis to set limits on decay widths.

Main Results:

• No signal candidates for tri-nucleon decays of Germanium-76 were observed.
• A lower limit on the lifetime for inclusive tri-nucleon decays was set at 1.2 x 10^26 years (90% credible interval).
• This result significantly improves previous limits by one to three orders of magnitude.

Conclusions:

• The absence of signal places strong constraints on the probabilities of tri-nucleon decays.
• The findings push the boundaries of experimental sensitivity for rare nuclear events.
• This study contributes to a deeper understanding of nuclear structure and decay mechanisms.