The polarization of cosmic ray muons
Cosmic-rays muons of definite energy and direction of motion are expected to show a partial longitudinal polarization because of the falling energy spectrum of the parent pions. The general theory of muon polarization in pi deg C was con- mu decay in flight is worked out, and applied to cyclotron as well as cosmic-ray experiments. Cosmic-ray muons are predicted to have a partial longitudinal polarization of about 23%. The theory is aiso applied to the K deg C was con- mu decay. An experiment has been carried out to test the prediction for cosmic-ray muons. Decay electrons from muons stopped in an aluminum absorber are detected in identical scintillation counters placed symmetrically above and below the absorber. The delay and amplitude of each observed pulse have been measured, and used to sont out the mu /sup +/ deg C was con- e/sup +/ decays from the mu /sup - deg C was con- e/sup -/ and background contributions. The ratio of mu /sup +/ deg C was con- e/sup +/ events detected in the upper and lower scintillators is 1.14 plus or minus 0.07, as compared with a theoretical prediction of about 1.11. To test the symmetry of the apparatus the experiment has aiso been carried out with an absorber of salt, which is known to depolarize stopped muons aimost completely. The upper to lower ratio is in this case 1.03 plus or minus 0.06, to be compared with the theoretically expected vaiue of about 1.02. It is concluded that the various assumptions made in the theory of muon polarization in pi deg C was con- mu decay in flight are correct and that muons suffer negligible depolarization while losing 2 Bev energy in the atmosphere. (auth)
- Research Organization:
- Washington Univ., St. Louis
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-13-003158
- OSTI ID:
- 4273378
- Journal Information:
- Nuovo Cimento, Journal Name: Nuovo Cimento Journal Issue: S2 Vol. 8; ISSN 0029-6341
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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