No abstract

and I n d i a n a U n i v e r s i t y C y c l o t r o n F a c i l i t y S t u d i e s o f t h e s y s t e m a t i c behavior of t h e most p r o b a b l e t o t a l k i n e t i c energy r e l e a s e i n f i s s i o n , GK>, have shown t h a t t h e d a t a can be r a t h e r a c c u r a t e l y d e s c r i b e d by a s i m p l e model based on Coulomb r e p u l s i o n between p r o l a t e ~~h e r i 0 d s . l Such a model p r e d i c t s t h a t depends l i n e a r l y on t h e Coul13mb parameter, z 2 /~l 1 3 , of t h e f i s s i o n i n g nucleus.It i s expected t h a t t h i s r e l a t i o n s h i p should deslzribe l i q u i d drop f i s s i o n e n e r g e t i c s , i.e. f i s s i o n well-above t h e b a r r i e r . S i n c e t h e dependence of GK> on e x c i t a t i o n energy i s r a t h e r weak, such a f i t t i n g procedure s u c c e e d s r e l a t i v e l y w e l l f o r spontaneous f i s s i o n a l s o . S t i m u l a t e d by two r e c e n t r e p , o r t s of GK> d a t a a t t h e lower2 and upper3 extremes of z2/A113, a new e v a l u a t i o n of f i s s i o n energy s y s t e m a t i c s has beenperformed. A weighted l e a s t -s q u a r e s f i t t o t h e c u r r e n t d a t a base4 y i e l d s t h e f o l l o w i n g r e s u l t : = (0.1189 + 0.0011) z2/A113 + 7.3

Using symmetric 112Sn+112Sn, 124Sn+124Sn collisions as references, we probe isospin diffusion in peripheral asymmetric 112Sn+124Sn, 124Sn+112Sn systems at an incident energy of E/A=50 MeV. Isoscaling analyses imply that the quasiprojectile and quasitarget in these collisions do not achieve isospin equilibrium, permitting an assessment of isospin transport rates. We find that comparisons between isospin sensitive experimental and theoretical observables, using suitably chosen scaled ratios, permit investigation of the density dependence of the asymmetry term of the nuclear equation of state.

Isotope, isotone and isobar yield ratios are utilized to obtain an estimate of the isotopic composition of the gas phase, i.e., the relative abundance of free neutrons and protons at breakup. Within the context of equilibrium calculations, these analyses indicate that the gas phase is enriched in neutrons relative to the liquid phase represented by bound nuclei.

The thermal component of the 8 GeV/c pi+ Au data of the ISiS Collaboration is shown to follow the scaling predicted by Fisher's model when Coulomb energy is taken into account. Critical exponents tau and sigma, the critical point (p(c),rho(c),T(c)), surface energy coefficient c(0), enthalpy of evaporation DeltaH, and critical compressibility factor C(F)(c) are determined. For the first time, the experimental phase diagrams, (p,T) and (T,rho), describing the liquid vapor coexistence of finite neutral nuclear matter have been constructed.