Search for. mu. /sup +/. -->. e/sup +/. gamma

Journal Article · Mon May 31 20:00:00 EDT 1982 · Phys. Rev. D; (United States)

DOI:https://doi.org/10.1103/PhysRevD.25.2846· OSTI ID:5286168

Kinnison, W W; Anderson, H L; Matis, H S; Wright, S C; Carrington, R L; Eichler, R A; Hofstadter, R; Hughes, E B; McPharlin, T P; Bowman, J D; Cooper, M D; Hamm, M E; Hoffman, C M; Mischke, R E; Nagle, D E; Sarracino, J S; Thompson, P A

This paper describes a kinematically complete search for the muon decay ..mu../sup +/..-->..e/sup +/..gamma... The experiment used a magnetic spectrometer outfitted with proportional chambers to measure the positron momentum vector and a large segmented NaI(Tl) array to determine the ..gamma..-ray energy and impact point. The positrons were mostly from normal muon decay while the ..gamma.. rays were mostly from internal and external bremsstrahlung. Approximately 3 x 10/sup 12/ muons were stopped in a 50-mg/cm/sup 2/ polyethylene target. The relative timing between the positron and the ..gamma.. ray was measured with a resolution of 1.9 ns full width at half maximum (FWHM) by the use of a plastic-scintillator hodoscope for the positron and by NaI(Tl) constant-fraction timing for the ..gamma.. ray. The positron energy resolution averaged over all data was 8.8% FWHM, and the ..gamma..-ray energy resolution was 8% FWHM, both at 52.8 MeV. When the ..gamma.. ray is assumed to originate at the same place in the target as the positron, the rms error in the measurement of the angle between the positron and ..gamma..-ray momentum vectors was 37 mrad. The acceptance of the apparatus for ..mu../sup +/..-->..e/sup +/..gamma.. events was (1.75 +- 0.04)%. A maximum-likelihood analysis established a 90%-confidence upper limit for the branching ratio GAMMA(..mu../sup +/..-->..e/sup +/..gamma..)/GAMMA(..mu../sup +/..-->..e..nu nu..) of 1.7 x 10/sup -10/.

• Research Organization: Enrico Fermi Institute, The University of Chicago, 5630 South Ellis Avenue, Chicago, Illinois 60637
• OSTI ID: 5286168
• Journal Information: Phys. Rev. D; (United States), Journal Name: Phys. Rev. D; (United States) Vol. 25:11; ISSN PRVDA
• Country of Publication: United States
• Language: English

Related Subjects

645101* -- High Energy Physics-- Particle Interactions & Properties-Experimental-- Electromagnetic Interactions & Properties
645102 -- High Energy Physics-- Particle Interactions & Properties-Experimental-- Weak Interactions & Properties
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
BRANCHING RATIO
BREMSSTRAHLUNG
DECAY
ELECTROMAGNETIC PARTICLE DECAY
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
FERMIONS
GAMMA RADIATION
IONIZING RADIATIONS
LEPTONS
MUONS
MUONS PLUS
PARTICLE DECAY
PHOSPHORS
PLASTIC SCINTILLATORS
POSITRONS
RADIATIONS
RADIATIVE DECAY
WEAK PARTICLE DECAY