Waiting for the proton to decay: 1983 results from the new dedicated experiments

Three new dedicated experiments searching for proton decay came on the air during the last year or so. Orders of magnitude more neutrino events, as well as possible nucleon decay candidates, have been recorded. Significant new limitss have been placed on many modes of nucleon decay. Representative lower limits at 90% C.L. for the lifetime/branching ratio for p→e+π0 of 2.0×1032 years, p→e+K0 of 3.1×1031 years, p→μ+K0 of 2.6×1031 years, and n→ν̄K0 of 0.8×1031 years have been set by the IMB group. Many other limits have also been set by the HPW, IMB, Kamioka, Kolar, and Mont Blanc experiments. Contained interactions have been observed in four detectors at rates expected from atmospheric neutrino induction, within the 30‐50% errors on the calculations. The status1 of the operational experiments is discussed, and typical restrictive results are reviewed. Detectors under construction are also mentioned.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87916/2/21_1.pd

Design of an enhanced 1 GeV electron neutrino beam

An enhanced [nu]e beam would be useful for experiments that have been proposed to investigate the time evolution of a [nu]e beam or to test the universality of [nu]e and [nu][mu] interactions. We have performed detailed calculations to maximize the flux of electron neutrinos through a detector while minimizing the more copious muon neutrinos produced at 30 GeV proton accelerators. The [nu]e beam is formed from the semi-leptonic decay modes of the neutral kaon. Muon neutrinos generated by decays of charged pions and kaons are suppressed by a dipole sweeping magnet. The [nu]e/[nu][mu] ratio is enhanced from its usual value of ~ 1/1000 to a value of ~ 1/2, albeit at a low flux. We find with this design a typical flux of 1.5 x 107 [nu]e/m2 s. We find that a high magnetic field (>= 40 kG) is essential to achieve this [nu]e/[nu][mu] enhancement. Although the use of collimators and/or plugs inside the magnet reduces the [nu][mu] flux, the [nu]e flux is also diminished so that there is little beneficial effect on the [nu]e/[nu][mu] ratio. Magnetic focusing horns and quadrupole beams do not enhance the [nu]e/[nu][mu] ratio. The accuracy of the energy dependence of the calculation, as well as the absolute normalization of the fluxes, is determined by a subsidiary calculation of the [nu][mu] yield from the magnetic horn focused beam at Brookhaven National Laboratory. This calculation is the first to our knowledge to agree well with the [nu][mu] yield as measured in the BNL seven foot bubble chamber.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25662/1/0000214.pd

Limits on the production of neutral penetrating states in a beam dump

We present limits on the production of neutral penetrating states produced in 28 GeV proton nucleus collisions. We obtain limits for light, heavy and unstable neutral states. For light stable states our limit [sigma]I[sigma]P-69cm4/nucleon2 is more than a factor of 5.5 better than previous limits. Time of flight techniques are used to study heavy states. We have poor sensitivity to short-lived states.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24349/1/0000616.pd

Neutrino astrophysics with IMB: past, present, and future

A burst of eight neutrino interactions occurring over a six second interval had been observed with the IMB detector. The closeness in time of the burst to the optical discovery of Supernova 1987a suggests that the neutrinos originated from stellar collapse. The characteristics of the burst are reviewed together with a recently completed reevaluation of many aspects of the detector's response. Efforts underway to discover past and future supernovae are also briefly discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27392/1/0000423.pd

Search for Nucleon Decays induced by GUT Magnetic Monopoles with the MACRO Experiment

The interaction of a Grand Unification Magnetic Monopole with a nucleon can lead to a barion-number violating process in which the nucleon decays into a lepton and one or more mesons (catalysis of nucleon decay). In this paper we report an experimental study of the effects of a catalysis process in the MACRO detector. Using a dedicated analysis we obtain new magnetic monopole (MM) flux upper limits at the level of $\sim 3\cdot 10^{-16} cm^{-2} s^{-1} sr^{-1}$ for $1.1\cdot 10^{-4} \le |\beta| \le 5\cdot 10^{-3}$, based on the search for catalysis events in the MACRO data. We also analyze the dependence of the MM flux limit on the catalysis cross section.Comment: 12 pages, Latex, 10 figures and 2 Table

Search for massive rare particles with MACRO

Massive rare particles have been searched for in the penetrating cosmic radiation using the MACRO apparatus at the Gran Sasso National Laboratories. Liquid scintillators, streamer tubes and nuclear track detectors have been used to search for magnetic monopoles (MMs). Based on no observation of such signals, stringent flux limits are established for MMs as slow as a few 10^(-5)c. The methods based on the scintillator and on the nuclear track subdetectors were also applied to search for nuclearites. Preliminary results of the searches for charged Q-balls are also presented.Comment: 20 pages, 9 EPS figures included with epsfi

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)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87900/2/1_1.pd

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.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87399/2/321_1.pd