Experimental study on 3.7A GeV 16O interactions with emulsion nuclei is carried out. The shower
particle multiplicity characteristics are investigated. Data are presented in terms of the number of
emitted particles in both forward and backward angular zones. The dependence on the target size is
presented. For this purpose the statistical events are discriminated into groups according to the
interactions with H, CNO, Em, and AgBr target nuclei. The separation of events, into the mentioned
groups, is executed basing on Glauber's approach. Features suggestive of a decay mechanism seem to
be a characteristic of the backward emission. This emission may be during the de–excitation of the
excited target nucleus, in a behavior like that of compound–nucleus disintegration. Regarding the
limiting fragmentation hypothesis beyond 1A GeV, the target size is the main parameter affecting the
backward production. The incident energy is a main factor responsible for the forward emitted particle
production in a creation system. However, the target size is an effective parameter as well as the
projectile size considering the geometrical concept regarded in the nuclear fireball model. The data are
simulated in the framework of the Lund Monte Carlo simulation code, the so–called modified
FRITIOF model. The multisource thermal model can predict source numbers, may be responsible for
particle production.