Reaction plane determination for 36Ar+197Au collisions at E/A=35 MeV.

Abstract

Collisions between $^{36}\mathrm{Ar}$ projectile and $^{197}\mathrm{Au}$ target nuclei at E/A=35 MeV have been studied with a 4\ensuremath{\pi} phoswich array with a low detection threshold. Azimuthal distributions of light-charged particles and intermediate-mass fragments are extracted with respect to reaction planes determined from fission fragments or from the emission patterns of coincident light particles and intermediate-mass fragments. The internal consistency and sensitivity to particle detection thresholds are explored for the various techniques of reaction plane determination. For the present reaction, the reaction plane can be determined with comparable accuracy from the distribution of fission fragments as from the orientation of the major axis of the transverse momentum tensor constructed from the emitted light particles and intermediate-mass fragments. Monte Carlo calculations are performed illustrating the sensitivity of the transverse momentum tensor method to the azimuthal anisotropy of the single-particle distributions and the convergence of this method as a function of particle multiplicity. The extraction of experimental uncertainties in the determination of the reaction plane is discussed.