Experimental investigations in particle physics at intermediate energies
Abstract
The major elements of this project continues to be on fundamental symmetries and parameters of the Standard Model. The projects in the current period have been BNL E791 (a search for the decay K(sub L)(sup 0) yields micro-e, which would violate the rule of separate lepton number conservation), test of an upgrade proposal (E871), and LSND, a neutrino experiment at LAMPF. For E791, data taking was completed in June 1990, and preliminary results are now available for the decays K(sub L)(sup 0) yields micro-e and K(sub L)(sup 0) yields (mu)(mu)from the entire data set. The data for decay K(sub L)(sup 0) yields ee are still being analyzed. These are an upper limit for the branching fraction for K(sub L)(sup 0) yields micro-e of 3.5 x 10(exp -11) (90 pct. C.L.). From the 1990 data alone, we have a new (preliminary) value of the branching fraction for K(sub L)(sup 0) yields (mu)(mu) of (6.96 + or - 0. 4 + or - 0.22) x 10(exp -9), with a sample of 349 events. Combining this with earlier data gives (6.96 + or - 0.34) x 10(exp 9), by far the most precise value. The limit on the decay K(sub L)(sup 0) yields micro-e places a lower limit on the mass of a new particle mediating such decays of 85 TeV. The LSND (Large Scintillator Neutrino Detector), a search for neutrino oscillations at LAMPF, has been approved, and is now underway. Other neutrino work at Los Alamos, E764, has resulted in a final publication. This includes the best measurement of (nu)-nuclear scattering, in (nu)(sub mu) C-12 inclusive cross sections. The measurement of the cross section for the exclusive reaction (nu)(sup mu)(C-12) yields (mu)(sup -12) N is unique. In a new development, Dr. Martoff has established a facility for fabrication of superconducting detectors of nuclear radiation; the equipment has been funded and is partly installed. Planned uses include scattering for 'Dark Matter.' In summary, the objectives for this year have been met.
- Publication:
-
Unknown
- Pub Date:
- September 1991
- Bibcode:
- 1991eipp.rept.....A
- Keywords:
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- Leptons;
- Neutrinos;
- Particle Energy;
- Particle Interactions;
- Radiation Detectors;
- Radioactive Decay;
- Carbon 12;
- Conservation Laws;
- Nuclear Reactions;
- Radiation Measurement;
- Atomic and Molecular Physics