The laser isotope separation (LIS) system is being developed for the study of neutrino-less double beta decay of 48Ca. A proof-of-principle experiment has been successfully conducted, and development ...of a mass production (∼1 mol/year) system is currently underway. For stable and efficient production, we are preparing an atomic beam system capable of producing a well-collimated beam with sufficient flux and a high-power semiconductor laser system with stable frequency over a long period of time.
JSNS
2
(J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) is an experiment that searches for sterile neutrinos via the observation of
ν
¯
μ
→
ν
¯
e
appearance oscillations using ...muon decay-at-rest neutrinos. The JSNS
2
experiment performed data taking from 2021. In this manuscript, a study of the accidental background is presented. The rate of the accidental background is (
9.29
±
0.39
)
×
10
-
8
/spill with 0.75 MW beam power and comparable to the expected number of signal events.
Search for the ultra-rare process, neutrino-less double beta decay, is a powerful tool to test the Majorana nature of neutrinos. Among the potential double beta decay nuclei, 48Ca has the largest ...Q-value, hence we can expect the measurement with least background. On the other hand, due to its low natural abundance, isotope enrichment is essential to achieve the sensitivity in the region of interest (inverted/normal mass hierarchy of neutrinos).We have been developing a laser isotope separation method using a tunable semiconductor laser that can excite only a specific isotope (48Ca). The laser is irradiated perpendicular to the collimated calcium vapor beam. Only 48Ca atoms are separated by deflecting them from the original atomic beam by momentum transfer due to multiple absorption and emission of laser photons. The isotope separation is confirmed by irradiating an ionization laser and time-of-flight measurement.Following the success of the proof-of-principle experiment, we are now developing the mass production system which include efficient generation of atomic beams, frequency-stabilized high-power laser, efficient laser irradiation method, and collection method of deflected isotope beams. In this paper, we report on the status and prospects of these developments.
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