We report a search for time variations of the solar 8 B neutrino flux using 5,804 live days of Super-Kamiokande data collected between May 31, 1996, and May 30, 2018. Super-Kamiokande measured the precise time of each solar neutrino interaction over 22 calendar years to search for solar neutrino flux modulations with unprecedented precision. Periodic modulations are searched for in a data set comprised of five-day interval solar neutrino flux measurements with a maximum likelihood method. We also applied the Lomb-Scargle method to this data set to compare it with previous reports. The only significant modulation found is due to the elliptic orbit of the Earth around the Sun. The observed modulation is consistent with astronomical data: we measured an eccentricity of (1.53±0.35) %, and a perihelion shift is (−1.5±13.5) days.
We have searched for proton decay via p → νK + using Super-Kamiokande data from April 1996 to February 2013, 260 kiloton·year exposure in total. No evidence for this proton decay mode is found. A lower limit of the proton lifetime is set to τ/B(p → νK + ) > 5.9 × 10 33 years at 90% confidence level.
We have searched for proton decay via p → µ + K 0 using data from a 91.7 kiloton·year exposure of SuperKamiokande-I, a 49.2 kiloton·year exposure of Super-Kamiokande-II, and a 31.9 kiloton·year exposure of Super-Kamiokande-III. The number of candidate events in the data was consistent with the atmospheric neutrino background expectation and no evidence for proton decay in this mode was found. We set a partial lifetime lower limit of 1.6×10 33 years at the 90% confidence level.
[1] The Research Group for Semi-controlled Earthquakegeneration Experiments in South African deep gold mines (SeeSA) has continuously monitored strain changes with a resolution of 24 bit 25 Hz at the Bambanani mine near Welkom. An Ishii borehole strainmeter was installed at a depth of 2.4 km near the potential M $ 3 earthquake source area. Instantaneous strain steps of $10 À4 strains associated with two M2 events were observed within a length of seismic fault. These steps were followed by significant postseismic creep-like drift, but not preceded by forerunners. Analysis of the continuous 25 Hz data reveals many smaller steps with much longer durations (100 ms $ 100 s) than seen in normal earthquakes (À1 < M < 2) with source durations of 1 ms$50 ms. Some of the especially slow steps were preceded by accelerations in strain, the maximum being as large as one-third of the step.
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