Search for the neutrinoless muon decay,. mu. /sup +/. -->. e/sup +/. gamma

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:5296958

Wilson, S L

Separate muon, electron, and tau numbers are conserved in the minimal standard model of electroweak interactions with massless neutrinos. However, in many extensions to the standard model, separate lepton numbers are not expected to be conserved quantities. A new search for muon number non-conserving processes has been undertaken at the Los Alamos Meson Physics Facility (LAMPF), specifically to look for three neutrinoless decay modes of the muon. A new detector facility, located in the LAMPF stopped muon channel, was developed for this experiment. This Crystal Box detector consists of a cylindrical drift chamber surrounded by a plastic scintillator hodoscope and a large solid angle, modularized, Nal(Tl) calorimeter. The apparatus measures the trajectories, relative timing, and energies of charged particles and photons from the decays of positive muons stopped in a central target. The assembly and calibration of the detector is described, and the procedure for taking data is discussed. The sample of 1.3 million candidate events, from the first data run of the Crystal Box, was analyzed using a maximum-likelihood method. The upper limit on the branching ratio, relative to normal muon decay for a muon decaying to an electron and a photon is found to be consistent with previous measurements. With 90% confidence, the branching ratio for this neutrinoless decay is observed to be less than 1 in 3.6 billion.

• Research Organization: Stanford Univ., CA (USA)
• OSTI ID: 5296958
• Country of Publication: United States
• Language: English

Related Subjects

645102* -- High Energy Physics-- Particle Interactions & Properties-Experimental-- Weak Interactions & Properties
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ACCELERATORS
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
BRANCHING RATIO
DATA
DRIFT CHAMBERS
ELEMENTARY PARTICLES
EXPERIMENTAL DATA
FERMIONS
INFORMATION
LAMPF LINAC
LEPTON NUMBER
LEPTONS
LINEAR ACCELERATORS
MASSLESS PARTICLES
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
MESON FACTORIES
MULTIWIRE PROPORTIONAL CHAMBERS
MUONS
MUONS PLUS
NUMERICAL DATA
PARTICLE MODELS
PHOTONS
POSITRONS
PROPORTIONAL COUNTERS
RADIATION DETECTORS
RADIATIVE DECAY
STANDARD MODEL
UNIFIED GAUGE MODELS