Two Source Emission Behavior of Helium Projectile Fragments in ⁸⁴Kr Interactions at Around 1 GeV per nucleon

Problem statement: The emission of helium projectile fragments has been studied in ⁸⁴Kr interactions with nuclei of the nuclear emulsion detector at relativistic energies below 2 GeV per nucleon. Approach: The angular distribution of helium projectile fragments in terms of transverse momentum could not be explained by a straight and clean-cut collision geometry hypothesis of Participant-Spectator (PS) Model. Results: Therefore, it has been assumed that helium projectile fragments were produced from two separate sources that belong to the projectile spectator region differing drastically in their temperatures. It has also been clearly observed that the emissions of helium projectile fragments were from two different sources. The contribution of helium projectile fragments from contact layer or hot source was few percent of the total emission of helium projectile fragments. Conclusion: Most of the helium projectile fragments were emitted from the cold source.