Further Evidence for the Radiative Decay of a Light, Penetrating Particle

摘要

Photons and photon pairs from the 590 MeV proton beam dump at SIN, have been observed in a counter-triggered thin foil optical spark chamber, placed behind 7.5 m of iron-concrete, and 2 m of free space. A significant excess of events was found at small angles alpha towards the beam dump direction: thirteen 1 gamma -events, and twelve 2 gamma -events (with alpha <= 7 deg, and for 129 Coulombs), over a flat background of, respectively, 3.2 and 2.3 events per bin. The effect was unchanged by 20 cm of iron in front of the decay region, but vanished when this iron was moved to the end of that region. This suggests that these photons stem from a dacay. (ERA citation 10:047562)