Non-Accelerator Physics with The Super-Kamiokande Detector

University Of California-Irvine, Irvine CA

Investigators

Abstract

This award will provide support for the group’s non-accelerator physics program at the Kamioka Laboratory in Japan with the Super-Kamiokande (Super-K) detector. Super-K has been a prime example of an astrophysics detector searching to help understand the properties of neutrinos and the search for proton decay since 1996. With the current upgrade, it is now preparing to precisely determine neutrino oscillation parameters with atmospheric neutrinos. Atmospheric neutrinos also provide an opportunity to understand the relative masses of the various neutrino flavors and are sensitive to the so-called Charge-Parity (CP)-violation phase, which could help identify why there is so much more matter than anti-matter in the Universe. This award will also support the possibility of observing other types of neutrino interactions that will extend the indirect search for dark matter to medium/low Dark Matter masses. The Kamioka Laboratory has an extensive program for involving the public, undergraduate students, and K-12 students in the excitement of this research. The graduate student working on the new system will be integrated into these activities and lecture on the physics that comes from looking at astroparticle physics in Super-K. Each summer, the group selects undergraduate students from UCI and high school students to work at UCI or in Japan. The State of California COSMOS program provides a residential academic experience for high school students with a mission to motivate the most creative minds of the new generation of prospective scientists, engineers, and mathematicians. UCI faculty create course “clusters” in topics from astrophysics to mathematical modeling to marine ecosystems just for COSMOS. Here, they propose to originate a cluster in experimental particle physics emphasizing detection techniques. A previous NSF grant supported the design, construction and installation of a new trigger system, the Wideband Intelligent Trigger (WIT) system, which completely processes all of the data in the un-triggered, raw stream and extracts electrons with high efficiency down 2.49 MeV, the limit of stable and reliable event reconstruction at Super-K. The UCI group will capitalize on the investment of the previous award and take the lead in WIT data analysis. Super-K is currently in the process of being upgraded with the addition of gadolinium in order to enhance its neutron detection capabilities. At present, neutrons are observed by the 2.2 MeV photon emitted from capture on Hydrogen after about 200 micro-sec. On average there are only seven detected photons and the detection efficiency is quite low. After dissolving 0.2% Gd2(SO4)3, 90% of the neutrons will capture on Gd which makes an 8 MeV gamma cascade and produces about 22 detected photons per capture after about 35 micro-sec. High efficiency neutron detection will benefit many physics topics in Super-K-Gd. This project advances the goals of the NSF Windows on the Universe Big Idea. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.