MEGA -- A search for {mu} {r_arrow} e{gamma}

Conference · Tue Dec 01 04:00:00 EST 1998

OSTI ID:677165

Mischke, R E

The MEGA experiment is a search for the decay {mu} {r_arrow} e{gamma}. Even though there is no fundamental reason to expect lepton number to be a conserved quantity, processes such as {mu} {r_arrow} e{gamma} have not been observed. (The present upper limit for the branching ratio for {mu} {r_arrow} e{gamma} is 4.9 x 10{sup {minus}11}.) The minimal standard model of electroweak interactions, which is enormously successful, builds in lepton number conservation. However, the decay {mu} {r_arrow} e{gamma} is expected in many extensions to the standard model, in particular in supersymmetry models. The experimental signature for {mu} {r_arrow} e{gamma} from decays at rest is the observation of a positron and photon, each of 52.8 MeV , that are back-to-back, in time coincidence, and originate from a common spatial point. The MEGA detector consists of two spectrometers designed to measure the kinematic characteristics of positrons and photons to search for events with this signature. The primary difficulty in the analysis of these data has been the development of reconstruction algorithms that balance efficiency and resolution. Also, many calibrations and corrections are needed to get optimum resolutions. Most surviving candidate events are accidentals. Results of analysis are given.

• Research Organization: Los Alamos National Lab., NM (United States)
• Sponsoring Organization: USDOE Office of Energy Research, Washington, DC (United States); National Science Foundation, Washington, DC (United States); Welch (Robert A.) Foundation, Houston, TX (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 677165
• Report Number(s): LA-UR--98-2113; CONF-980372--; ON: DE99000757
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
BRANCHING RATIO
COINCIDENCE METHODS
DATA ANALYSIS
MUONS
PARTICLE IDENTIFICATION
RADIATIVE DECAY