Atomic and Nuclear Physics

Biography

Biography: S P Avdeyev

Abstract

The kinetic energy spectra of intermediate mass fragments, (which are heavier than α-particles but lighter than fission fragments) have been studied for 4.4 GeV d + Au collisions at the Dubna Nuclotron with the FAZA 4π detector array. Experimental kinetic energy spectra were compared to that obtained by the multibody Coulomb trajectory calculations with the various values of radial flow. Th e analysis has been done on an event by event basis. The multibody Coulomb trajectory calculations of all charged particles have been performed with the initial break-up conditions given by the combined model INC+SMM. It was found good agreement of measured and calculated kinetic energy spectra including additional energy, which is due to the radial expansion of the system. We used a uniform radial expansion, in which the flow velocity is a linear function of the distance of the particle from the center of mass. The velocity of a particle Z located on a radius RZ in freeze out moment was taken as follows: 0 flow v radial velocity on the surface of the system. The figure shows the dependence of the radial fl ow 0 flow v as a function of fragment charge Z. It is seen that the radial fl ow decreases with increasing fragment charge. This means that the density distribution is not homogeneous. In fact, if the fragments are formed due to density fl uctuations, the formation of heavy fragments is preferable in the denser inner part of the expanding nucleus. The research was supported by Grant No. 15-2-02745-a from Russian Foundation for Basic Research. Radial fl ow as a function of fragment charge