Neutral Decay of the ω Meson
Abstract
The reaction π-+p-->ω+n at 1.2 BeVc was detected by counter techniques. Recoil neutrons were detected in a scintillation counter array at θn=20∘+/-2∘, and their velocity determined by a time-of-flight measurement. Measurement of the neutron direction and velocity determined the ω mass with resolution +/-15 MeV, and enabled separation of ω production from background. Scintillation counters surrounding the hydrogen target distinguished charged from neutral ω decays, yielding a branching ratio: ΓneutralΓcharged=0.124+/-0.021. Neutral ω decays were directly observed by conversion of the resulting γ rays in a leadplate spark-chamber array. Events with three observed γ's were fitted to the decay ω-->π0+γ-->3γ (a two-constraint fit). Twenty-six fits with χ2<5 were found, of which five are estimated to be background. If ω-->π0+γ is the only neutral mode, then we expect 29 observed π0γ decays, as calculated from the recoil-neutron measurements and spark-chamber efficiency. Thus our data give clear evidence that the mode ω-->π0+γ represents a substantial fraction (consistent with 100%) of the ω neutral decays.
- Publication:
-
Physical Review
- Pub Date:
- July 1967
- DOI:
- 10.1103/PhysRev.159.1219
- Bibcode:
- 1967PhRv..159.1219F