Western Kentucky University
Department of Physics and Astronomy


Dr. Mary Kidd

Department of Pysics
Tennessee Technological University

"First Limit on Neutrinoless Quadruple Beta Decay of 150Nd to the 0+1 state of 150Gd and Why We Care…."

April 01, 2019 @ 4:00 pm in EST 260


Lepton-number violating processes can lead to leptogenesis and the matter-anti-matter asymmetry, and can explain why we exist today. Observation of lepton number violation via detection of neutrinoless double beta decay requires that the neutrino be a Majorana particle. If the neutrino is a Dirac particle, a potential lepton-number violating process is neutrinoless quadruple beta decay. Only a few nuclei can undergo neutrinoless quadruple beta decay; one of these nuclei is 150Nd. This study yields the first half-life limit of the neutrinoless quadruple beta decay to the excited 0+1 state of 150Gd. We searched for neutrinoless quadruple beta decay events to excited final states of 150Gd by detecting the de-excitation gamma rays of the daughter nucleus in coincidence. These gamma rays have energies of 569.031 keV and 638.050 keV, and are emitted in coincidence through a 0+1 →2+1 →0+gs transition. The enriched Nd2O3 sample consisted of 40.33 ± 0.02 g 150Nd and was observed for 642.8 days at the Kimballton Underground Research Facility. A half-life limit for the decay to the 0+1 state of 150Gd was found to be T1/2 > 1.76 × 10^20 years (90% CL). We report the first search for this decay to excited final states. Though the predicted half life of this decay is many orders of magnitudes larger, constraining this value experimentally is vital to check for potential enhancements to the decay rate.