New branching ratio measurement of the pion beta - decay. pi. /sup +/. -->. pi. /sup 0/ + e/sup +/ + nu/sub e/
A new measurement of the branching ratio R of the pion beta-decay mode ..pi../sup +/..--> pi../sup 0/ + e/sup +/ + nu/sub e/ was made at the High Energy Pion channel P/sup 3/ of the LAMPF accelerator at Los Alamos. The measurement used a completely new ''decay-in-flight technique'' which differs from all the previous experiments based on a ''decay-at-rest technique''. The two gamma rays from the decay of the neutral pion ..pi../sup 0/ were detected in coincidence using a modified version of the LAMPF ..pi../sup 0/ spectrometer. The number of analyzed pion beta-decay events (after background subtraction) was 1127.14 +/- 33.92. Great care was taken to make an accurate measurement of the absolute number of charged pions in the beam and yielded (2.1457 +/- 0.0223) X 10/sup 14/. A Monte Carlo program was then used to simulate the pion beta-decay process and the response of the apparatus to this decay. The resulting value of the pion beta-decay branching ratio R = GAMMA(..pi../sup +/..--> pi../sup 0/ + e/sup +/ + nu/sub e/)/GAMMA(..pi../sup +/..-->..all) is R/sub EXP/ = (1.021 +/- 0.039) X 10/sup -8/, whereas the current CVC theory predicts R/sub THE/ = (1.047 +/- 0.008) X 10/sup -8/. Within the uncertainties, the experimental and theoretical values agree. Thus, the newly measured value of R is consistent with the theory and CVC hypothesis.
- Research Organization:
- Temple Univ., Philadelphia, PA (USA)
- OSTI ID:
- 5006963
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PIONS PLUS
BETA-PLUS DECAY
BETA PARTICLES
BRANCHING RATIO
ELECTRON NEUTRINOS
EXPERIMENTAL DATA
LAMPF LINAC
MONTE CARLO METHOD
PIONS NEUTRAL
TIME-OF-FLIGHT METHOD
ACCELERATORS
BETA DECAY
BOSONS
CHARGED PARTICLES
DATA
DECAY
ELEMENTARY PARTICLES
FERMIONS
HADRONS
INFORMATION
LEPTONS
LINEAR ACCELERATORS
MASSLESS PARTICLES
MESON FACTORIES
MESONS
NEUTRINOS
NUMERICAL DATA
PIONS
PSEUDOSCALAR MESONS
645102* - High Energy Physics- Particle Interactions & Properties-Experimental- Weak Interactions & Properties