Particle Physics And Nuclear Physics

Distribution of helium projectile fragments (HPFs) produced in 12C-emulsion interactions at 290 A MeV and correlation between HPFs and the size of target is discussed.The experimental results is compared with that obtained from different beam induced nuclear emulsion collision at different energies. It is found that 1). the partial production cross-sections of 0αand 1αis independent of the beam mass and energy, but the partial production cross-sections of Nα≥2 increase with the projectile mass; 2). the average multiplicity of HPFs depends on the mass of projectile but independent of incident energy; 3). the dispersion D of HPFs multiplicity distribution linearly depend on the average HPFs multiplicity , and the non-zero of the value of the second Muller moment f2 implies there are strong correlation between the production of HPFs; 4).The minimum percentage for the interactions of 12C and H target is at Nα=1,but for Nα>1 the percentage of HPFs production is gradually increased in collisions of 12C and H target. The emission of high multiplicity HPFs is more in collisions of 12C and H target,the emission of low multiplicity HPFs is more in collisions of 12C and C,N,O,AgBr target ; 5). average black track particles ,average grey track particles and average heavily ionizing track particles decrease with increase of the number of HPFs ; 6). the emission angle and transverse momentum distribution of HPFs can not be represented by a single Gaussian distribution, but can be well represented by superposition of two Gaussian distribution, which means that there are two different sources in the production of HPFs in 12C-emulsion collisions at 290 A MeV.