D. Kielczewska

A waveshifter light collector for a water Cherenkov detector

Abstract A device has been developed which is capable of doubling the light collection capability of a 5 inch hemispherical photomultiplier tube. Known as a “waveshifter plate”, its geometry is adaptable to various applications. Its marginal cost is small with respect to that of a phototube, it is readily removable, and it has minimum effect upon dark noise and timing resolution.

Calibration of the IMB detector

The IMB detector (named after its founding institutions: University of California, Irvine, the University of Michigan and Brookhaven National Laboratory) collected data on a wide range of phenomena for over eight years. It was the first and the largest of the ring imaging water Cherenkov detectors. The detector consisted of 8000 metric tons of ultra-pure water instrumented with 2048 photomultiplier tubes (PMTs). The PMTs were placed on the roof, floor, and walls of the detector in a lattice of approximately 1 m spacing. It made measurements of contained events that ranged in energy from 15 MeV up to 1.5 GeV. This paper describes the calibration of the IMB detector. This procedure was accurate and stable over a wide range of physical variables. It was used with little change throughout the entire eight-year lifetime of the experiment. The IMB calibration is a model for future large-scale detectors that employ the water Cherenkov technique.

A search for neutrino and gamma ray burst temporal correlations with the IMB detector

If Gamma Ray Bursts (GRBs) are associated with a stellar collapse‐like phenomenon then it is resonable to expect neutrino production to occur at the source. We have performed a temporal correlation analysis with GRBs using the IMB low‐energy neutrino dataset during 809 days of livetime between 1986 and 1990. No correlations were observed placing a 90%. C.L. limit of 0.046 ν interactions per GRB. The dependence of the GRB distances to neutrino yield using volume and shell distribution models is discussed. Lower limits are derived which exclude galactic stellar collapse‐like models.

A Search for Proton Decay into e+π° Irvine-Michigan-Brookhaven Collaboration

Observations were made 1570 mwe underground with an 8000 metric ton water Cherenkov detector. During a live-time of 80 days no events consistent with the decay p → e+π° were found in a fiducial mass of 3300 metric tons. We conclude that the limit on the lifetime for bound plus free protons divided by the e+π° branching ratio is τ/B > 1.9 × 1031 yr. (90% confidence). Observed cosmic ray muons and neutrinos are compatible with expectations.

Results from the IMB Detector the Irvine-Michigan-Brookhaven Collaboration

Results are presented from the first 80 days of the IMB detector, with 69 observed interactions in a 3300 metric ton fiducial volume. The 69 events are consistent with atmospheric neutrinos. Limits are set at the 90% CL for the lifetime/branching ratio τ/B for p → e+π° at 6.5 × 1031 years and p → μ+K° at 1.4 × 1031 years. For n → n, in oxygen, the lifetime is τ > 7 × 1030 years. Limits on monopole catalysis of nucleon decay up to a flux of 10−14/cm2 sec sr are described.