M.E. Potter

Limits on the neutrino magnetic moment from a measurement of neutrino-electron elastic scattering☆

Abstract Upper bounds on the magnetic moments of muon neutrinos and electron neutrinos are inferred from a measurement of neutrino-electron elastic scattering. The limits obained are: μ ν e −10 μ Bohr (90%CL) and μ ν ¬ −10 μ Bohr (90% CL).

Monte Carlo simulation of neutrino production by medium-energy protons in a beam stop

Abstract We describe a Monte Carlo program that generates the distribution of stopped pions produced by medium-energy protons in a beam stop. This distribution can be used to predict the absolute neutrino flux from this source to 7.3%. The same Monte Carlo program also calculates neutrino fluxes from the in-flight decay of pions and muons in the beam stop environment.

A search of the northern sky for ultra-high-energy point sources

A search has been made for steady emission or ultra-high-energy radiation from individual point sources over most or the northern sky. Over 2×10 8 air showers induced by primary particles or energy greater than about 10 TeV were recorded from 1986 April until 1991 May by the CYGNUS air shower array. No statistically significant excess above the background from the isotropic flux or cosmic rays was found for any direction in the sky from 0° to 80° declination. In addition, 49 specific potential sources were examined, and none showed a statistically significant excess or events

The CYGNUS extensive air-shower experiment

Abstract The CYGNUS extensive air-shower experiment is described. The design criteria, construction and operation details, and performance characteristics are presented. A discussion of the data analysis techniques is given. Finally, several enhancements and improvements in the apparatus are described.

Daily search for emission of ultra-high-energy radiation from point sources

A daily search for emission of ultra-high-energy radiation from astrophysical point sources using the CYGNUS extensive air shower array is described. The data set spans the period from 1986 April 4 to 1992 June 22. Fifty-one astrophysical objects have been examined, including Cyg X-3, Her X-1, the Crab, a number of gamma-ray and X-ray sources from the COS B and the fourth Uhuru catalogs, and several cataclysmic variables, nearby galaxies, and radio pulsars. The observed daily number of events from the source directions are consistent with expected statistical fluctuations of the number of events from backgrounds cosmic rays

Search for UHE emission from 4U0115+63

We report here the preliminary results of our observations of the sporadic X‐binary system 4U0115+63. The CYGNUS air shower array has been collecting data since April 1986. No significant excess is seen from the direction of this source, nor any correlation with its 24‐day orbital period. A 90% confidence‐level upper limit on the flux from 4U0115+63 is 2.8×10−13 cm−2 s−1 above 50 TeV. This flux limit is considerably lower than those reported by other UHE experiments. Search for periodicity at the neutron star frequency is in progress.

Recent data from the CYGNUS experiment

Data from the CYGNUS extensive air shower experiment at Los Alamos, NM has been analyzed to study the angular resolution of the array, and to search for point sources in the galaxy. Results on searches for steady emission from Cyg X‐3, Her X‐1 and the Crab nebula are presented.

Measurement of W‐Z interference from neutrino‐electron scattering

Neutrino‐electron elastic scattering was observed at LAMPF with a 15‐ton fine‐grained tracking calorimeter exposed to electron‐neutrinos from muon decay at rest. The measured νee−→νee− elastic scattering cross section, 10.0±1.5(stat)±0.09(syst)×10−45 cm−2×(Eν(MeV)), gives a model independent measurement of the strength of the destructive interference between the charged and neutral currents, I=−1.07±0.21, that agrees well with the standard model (SM) prediction I=−1.08. The agreement between the measured electroweak parameters and SM expectations is used to place limits on neutrino properties, such as neutrino flavor‐changing neutral currents and neutrino electromagnetic moments, and on the masses of hypothetical new bosons that would interact with leptons.

The status of the CYGNUS experiment: Past, present, and future

Abstract The CYGNUS experiment, located in Los Alamos, NM, has been continuously operating since April 2, 1986. The experiment consists of an air shower array and an associated 44 m2 muon detector; its large size, good angular resolution, muon detection, and low energy threshold make it a unique experiment among those currently operating. The experiment has undergone continuous expansion in several stages since it began operation. The experiment, its expansion, and further plans for the future will be described.