The s e l e c t i v i t y and t h e s u r p r i s i n g s i m p l i c i t y of response function f o r spin-isospin t r a n s i t i o n s with t h e (p,n) r e a c t i o n a t intermediate energies has been AL=O t r a n s f e r s f o r 5 4 9 5 6~e t a r g e t s . I n t h e case of used t o study the spin-isospin c o r r e l a t i o n s i n n u c l e i t h e N i i s o t o p e s , a comparison may be made with t h e M1 (see Ref. 1 and o t h e r references within). The zero s p e c t r a obtained from e l e c t r o -e x c i t a t i o n . 3 9 degree s p e c t r a have been used t o o b t a i n t h e AL = 0 The experimental r e s u l t s and a n a l y s i s f o r the response function of n u c l e i while t h e measured2 energy 5 8~i ( p , n ) 5 8~u r e a c t i o n have been published3; t h e dependence of the e f f e c t i v e n u c l e o n n u c l e u s i n t e r a c t i o n a n a l y s i s f o r t h e o t h e r i s o t o p e s is i n progress.r e s u l t i n g from the spin-isospin terms i n the The double d i f f e r e n t i a l c r o s s s e c t i o n of L = 0 nucleonnucleon f o r c e has been employed t o i d e n t i f y t h e s t r e n g t h observed a t ( 3~ = 0' f o r t h e 5 8~i ( p , n ) 5 8~u spin-isospin o r Gamow-Teller strength. Other r e a c t i o n is presented i n Fig. l b and i s compared i n multipoles observed a t higher e x c i t a t i o n energies Fig. l c with the B(M1)C s t r e n g t h reported4 f o r t h e i n d i c a t e a maximum d i f f e r e n t i a l c r o s s s e c t i o n a t 5 8~i ( e , e ' ) reaction. The l o c a t i o n s of known 1+ e x c i t e ds l i g h t l y higher angles and have been i n t e r p r e t e d a s s t a t e s i n A = 58 n u c l e i a r e shown i n Fig. la. (AL = 1, AS = 1) and (AL = 2, AS = 1) e x c i t a t i 0 n s . l *permanent address: C e n t r a l Research I n s t i t u t e f o r W e have obtained 160 MeV (p,n) d a t a on 5 4 * 5 6~e and Physics, Budapest, Hungary.5 8 * 6 0~i and 120 MeV d a t a f o r t h e 5 8~i ( p , n ) 5 8~u r e a c t i o n 1) C. Gaarde e t a l . , Nucl. Phys. A369, 258 (1981).i n order t o study t h e response function of 5 8 * 6 0~i 2) T.N. Taddeucci e t a l . , Phys. Rev. C 25, 1094 (1981).t a r g e t s t o spin-isospin t r a n s i t i o n s characterized with 3) J. Rapaport e t al., Phys. Lett. 119B, 61 (1982). AL = 0, AL = 1 and AL = 2 t r a n s f e r s and t o study t h e 4) R.A. Lindgren e t a l . , Phys. Rev. C 3, 1789 (1976).

At intermediate energies, the differential cross quantity R(Ep) thus represents very nearly the ratio of sections at 8=0° for hJJE=l+ and O+ (p,n) transitions interaction strengths I Ja,/J, 1. In Fig. 1 we plot are proportional to the reduced transition probabilities B(GT) and B(F) for the analogous Gamow-Teller (GT) and Fermi (F) beta decays, respectively. This proportionality may be exploited to gain information about the isovector effective i n t e r a c t i o n s t r e n g t h s . For even-A t a r g e t s wed e f i n e the empirical quantity [R(E~)]* = [C~~~(O")/B(GT)][B(F)/C~(~~)] where B(GT) and B(F) are obtainable from measured beta-decay ft values according to1 B(F)+(~ .~5)~~(~~)=(6163.4 sec)/ft . A

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