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Yoji Totsuka (戸塚 洋二, Totsuka Yōji, March 6, 1942 – July 10, 2008) was a Japanese physicist and Special University Professor, emeritus, University of Tokyo.A leader in the study of solar and atmospheric neutrinos, he was a scientist and director at Kamioka Observatory, Super-Kamiokande and the High Energy Physics Laboratory in Japan.
In particle physics, proton decay is a hypothetical form of particle decay in which the proton decays into lighter subatomic particles, such as a neutral pion and a positron. [1] The proton decay hypothesis was first formulated by Andrei Sakharov in 1967. Despite significant experimental effort, proton decay has never been observed.
It was a 30-ton tracking calorimeter whose primary purpose was to search for proton decay. [1] It set a lower limit on the lifetime of the proton of 1.6×10 30 years as well as upper limits on the density of magnetic monopoles. [2] It also served as a prototype for the following Soudan 2 and MINOS experiments.
Soudan 2 was the successor to the Soudan 1, a similar 30 ton detector also intended to search for proton decay. [2] The excavation for Soudan 2 was done in 1984–1985. Installation was started in 1986 and was completed in 1993. The experiment was run from April 1989 to June 2001, beginning with a partial detector of 275 tons. [3]
A simulated particle collision in the LHC. The safety of high energy particle collisions was a topic of widespread discussion and topical interest during the time when the Relativistic Heavy Ion Collider (RHIC) and later the Large Hadron Collider (LHC)—currently the world's largest and most powerful particle accelerator—were being constructed and commissioned.
IMB detected fast-moving particles such as those produced by proton decay or neutrino interactions by picking up the Cherenkov radiation generated when such a particle moves faster than light's speed in water. Since directional information was available from the phototubes, IMB was able to estimate the initial direction of neutrinos.
During 1984, Naba Kumar Mondal, TIFR, and Prof. Ito, Osaka City University, Japan, performed experimental studies on proton decay and indirectly observed the scatter of muons. Murali and Balasubramaniam briefly assisted Mondal and Ito as research assistants.
[10]: §IIIE If protons are not stable, white dwarfs will also be kept warm by energy released from proton decay. For a hypothetical proton lifetime of 10 37 years, Adams and Laughlin calculate that proton decay will raise the effective surface temperature of an old one- solar-mass white dwarf to approximately 0.06 K (−273.09 °C; −459.56 °F).