Helium production from 84Kr-- and 197Au--emulsion interactions at high energies

The properties of the relativistic helium fragments produced in interactions of ⁸⁴Kr at 1.8 A GeV and ¹⁹⁷Au at 10.7 A GeV in emulsion are investigated. The experimental results are compared with those obtained from various projectiles with emulsion collisions at different energies. It is found that the multiplicity distribution of helium projectile fragments (HPFs) is well described by the Koba--Nielsen--Olesen (KNO) scaling presentation. The second Mueller moment f₂ of the HPF multiplicity distribution is independent of the projectile energy for the same projectile, but it is dependent on the projectile mass number. The value of f₂ increases with the increase of projectile mass number A_p. The negative value of f₂, when A_p<69, means that the emission of HPFs is anticorrelated, but positive value of f₂, when A_p>69, refers to that the emission of HPFs is correlated. The non-zero f₂ moment in this experiment implies the strong correlation existing between the HPFs.