Further Study of the Anomalous Behavior of Secondary Particles Emitted from Heavy Primary Interactions

Abstract

Interaction lengths of singly charged relativistic secondary particles emitted from interactions of very heavy cosmic ray nuclei in emulsions were measured by systematic following of their tracks through the stack. The primary energies were determined by the "knock on" electron method. The results show that particles from interactions with primary energies between 1 and 5 GeV/nucleon emitted in the angular interval [Formula: see text] (θev is the expected RMS angle for evaporation protons) have significantly shorter mean free paths. The variation of the observed mean free paths with distance from the primary interactions shows a transition from short to normal interaction lengths at about 3 cm which indicates the presence of some anomalous component interacting with a very short mean free path of a few cm and relative intensity of order of 10%. This result cannot be accounted for by any known particle or interaction. Considerations of emission angles and types of stars produced by the secondary particles lead to a tentative conclusion that particles exhibiting the anomalously short interaction lengths are scattered fragments of the incident nuclei.