engleski

Pion absorption in flight on 4He

We have measured double and triple coincidences following π+ and π− absorption on 4He at various pion energies. Differential and integrated cross sections are determined for all possible absorption channels. We study and compare the two-nucleon absorption on nucleon pairs with isospin I = 0 and I = 1. In the dNN final-state two absorption mechanisms are identified, one with only one spectator nucleon and one with phase-space behavior. The existence of a three-nucleon absorption component with a spectator nucleon is established and a four nucleon phase-space-like contribution is also identified and found to be small. The total absorption cross section is directly determined by adding the integrated cross sections of all measured reaction channels.

pion absorption in flight ; nuclear reactions

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