B. G. Cortez

IMB-3: a large water Cherenkov detector for nucleon decay and neutrino interactions

Abstract The IMB experiment, a large water Cherenkov detector which began data collection in September 1982, has undergone several upgrades to improve light collection, on-line processing power, data throughput and buffering, calibration, and operating efficiency. The current device, known as IMB-3, enjoys a factor of four light collection advantage over its precursor. Since May 1986, it has been used to search for such diverse phenomena as nucleon decay, dark matter, neutrino oscillation, and magnetic monopoles, and to study stellar collapse and cosmic rays. Due to its large size and long exposure time IMB presents unique challenges. The design and operation of the IMB-3 detector are described in detail.

The IMB photomultiplier test facility

Abstract An automatic system for testing up to 32 photomultiplier tubes (PMs) simultaneously under single photon counting conditions has been used to measure characteristics of more than 2500 PMs for use in the Irvine-Michigan-Brookhaven (IMB) proton decay experiment, 2048 tubes (64 EMI 9834B 8″ diameter, and 1984 EMI 9870B 5″ diameter) were selected for use in the 8000 m3 IMB water Cherenkov detector, now in operation for over a year. The PM test system is described and results of testing are presented along with PM performance in the IMB detector over the last year. In general, we find that the tube characteristics have smaller fluctuations than expected and that the tubes have proven to be reliable under rugged handling and operating conditions. On the basis of our experience, we make suggestions as to new industry standards for PMs to be used in particle counting.

Investigation of Matter Enhanced Neutrino Oscillations Relevant to the Solar Neutrino Problem

Abstract We study the effect of matter enhanced neutrino oscillations on atmospheric neutrinos. A recently proposed solution to the solar neutrino problem with Δm 2 = 1.1×10 −4 eV 2 suggests enhanced effects in the range 200 MeV-500MeV. We find no evidence of this effect for v μ ↔ v e mixing. Limits are set on the magnitude of the mixing angle. Our limit is sin θ v

The search for proton decay

Following a very brief description of the theoretical developments which motivated the search for proton decay, I shall describe one of these experiments (the IMB experiment) in some detail. Then I shall compare recent results from that experiment with those from other detectors.

Experimental limits on nucleon decay and ΔB=2 processes

Results from the IMB collabration to detect possible proton decay in a salt mine near Cleveland, Ohio are presented. Detection apparatus is described.(AIP)