This work was supported by the National Science Foundation Grant NSF PHY 81-14339 and by Indiana Universit

Collins, S.F.

Devins, D.W.

Friesel, D.L.

Jones, W.P.

Officer, V.C.

Shute, G.G.

Spicer, B.M.

English

IUScholarWorks

ANALYZING POWER MEASUREMENTS FOR 3 ~ ( p , p  ') AT 120 MEV 
S.F. Co l l in s ,  B.M. Spicer ,  G.G. Shute, and V.C. Of f i ce r  
School of Physics,  Univers i ty  of Melbourne, P a r k v i l l e ,  V ic to r i a  3052, Aus t r a l i a  
D.W. Devins, D.L. F r i e s e l ,  and W.P. Jones 
Indiana Univers i ty  Cyclotron F a c i l i t y ,  Bloomington, Indiana 47405 
I n  a previous experiment l ,  d i f f e r e n t i a l  c ross  
s e c t i o n s  f o r  t he  e x c i t a t i o n  of 13c by i n e l a s t i c  proton 
s c a t t e r i n g  a t  135 MeV were obtained. Resu l t s  have been 
repor ted1 f o r  s t a t e s  up t o  an e x c i t a t i o n  energy of 
about 11 MeV, and f o r  the  3/2', T = 312 s t a t e  a t  15.11 
MeV. 
This  experiment was aimed mainly a t  e l u c i d a t i n g  
informat ion about exc i t ed  s t a t e s  above 11 MeV. An 
8.9 mg/cm3 13c t a r g e t  was placed i n  the  64" s c a t t e r i n g  
chamber, and s c a t t e r e d  protons were observed us ing 
i n t r i n s i c  Ge E-AE d e t e c t o r  te lescopes .  P a r t i c l e  
i d e n t i f i c a t i o n  was achieved us ing a hard-wired c i r c u i t .  
Spect ra  were measured a t  angles  between about 20' and 
50°, and covered a range from 0 MeV t o  g r e a t e r  than 30 
MeV exc i t a t ion .  The experimental  r e s o l u t i o n  was 
t y p i c a l l y  250 - 300 keV. Despi te  the  good s t a t i s t i c s ,  
t h e  l ack  of r e s o l u t i o n  has made the  e x t r a c t i o n  of peak 
a r e a s  d i f f i c u l t .  Consequently f o r  some of the weaker 
s t a t e s  the  u n c e r t a i n t i e s  a r e  q u i t e  large .  
Resu l t s  a r e  presented here  f o r  t h ree  of t he  bes t  
understood t r a n s i t i o n s  i n  13c, namely the  3/2' s t a t e  a t  
3.68 MeV, t he  512' s t a t e  a t  7.55 MeV and the  9/2+ s t a t e  
a t  9.50 MeV. The measured analyzing powers a r e  
compared t o  microscopic DWBA c a l c u l a t i o n s  f o r  these  
s t a t e s .  The parameters used i n  these  c a l c u l a t i o n s  a r e  
t h e  same a s  those  used i n  our previous work1, wi th  the  
except ion of the  nucleon-nucleon i n t e r a c t i o n .  Here we 
have used the  140 MeV complex t -ma t r ix  of Love and 
~ r a n e y , ~  which is s i m i l a r  t o  the  i n t e r a c t i o n 3  used i n  
our  previous work. Resu l t s  a r e  p l o t t e d  a s  a func t ion  
of qcm (ca lcu la t ed  r e l a t i v i s t i c a l l y ) ,  r a t h e r  than Ocm, 
because these  c a l c u l a t i o n s  were done f o r  a bombarding 
energy of 135 MeV. 
The spec t roscop ic  amplitudes used f o r  t he  312' and 
512' s t a t e s  were obtained from the  wavefunctions of 
Cohen and ~ u r a t h . ~  The angular  d i s t r i b u t i o n s  f o r  these  
s t a t e s  a r e  very s i m i l a r  t o  the  angular  d i s t r i b u t i o n  f o r  
t h e  2+, T = 0 s t a t e  of 12c  a t  4.44 MeV, cons i s t en t  with 
a weak coupling model of these  2 s t a t e s ,  wi th  the  
1 2 c ( 2 + , ~ = 0 )  coupled t o  a 1 ~ 1 1 2  neutron. The analyzing 
power measurements f o r  these  2 s t a t e s  a r e  shown i n  
Figs. 1 and 2, and a r e  a l s o  q u i t e  s i m i l a r  t o  the  
analyzing power measured f o r  t he  4.44 MeV s t a t e  of 12c 
i n  1 2 ~ ( ~ , ~ ' )  a t  120 ~ e v . 5  
In  Fig. 1 the  experimental  analyzing power f o r  
t he  312- s t a t e  is compared with the  DWBA ca lcu la t ion .  
Figure 1. Analyzing power measurements compared t o  
wi th  DWBA c a l c u l a t i o n s  f o r  t he  3/2' s t a t e  of 13c a t  
3.68 MeV. 
Resul ts  f o r  t he  512- s t a t e  a r e  presented i n  Fig. 2. 
I n  both in s t ances  the  magnitude of the  ca l cu la t ed  
analyzing powers is too large .  The c a l c u l a t i o n  f o r  t he  
4.44 MeV s t a t e  of 12c a t  a p r o j e c t i l e  energy of 120 
M ~ v , ~  (which used the  same i n t e r a c t i o n 2 ) ,  e x h i b i t s  a 
s i m i l a r  discrepancy. 
The r e s u l t s  f o r  t he  AJ=4, AL-3, AS=l t r a n s i t i o n  t o  
t h e  "s t re tched"  9/2+ s t a t e  a t  9.50 M e V  a r e  shown i n  
Fig. 3. The c a l c u l a t i o n  has the  r i g h t  magnitude but 
does not reproduce the  phase of t he  experimental  
analyzing powers. 
Data reduct ion is cont inuing f o r  t he  s t a t e s  a t  
h igher  e x c i t a t i o n  ene rg ie s  with the  o b j e c t i v e  of 
us ing the  combination of our d i f f e r e n t i a l  cross-sect ion 
measurements and these  new analyzing power measurements 
t o  a s s i s t  i n  the  determinat ion of sp ins  and p a r i t i e s  
of l e v e l s  where these  a r e  unknown. 
Figure  3. Analyzing power measurements compared wi th  
DWBA c a l c u l a t i o n s  f o r  t he  9/2+ s t a t e  of 13c a t  9.50 
MeV. 
1)  S.F. Co l l in s ,  G.G. Shute, B.M. Spicer ,  
v.C. Of f i ce r ,  I. Morrison, K.A. Amos, D.W. Devins, 
D.L. F r i e s e l  and W.P. Jones,  Nucl. Phys. A380, 445 
(1982). 
2) W.G. Love and M.A. Franey, Phys. Rev. C 24, 1073 
(1981). 
3) W.G. Love, i n  "Proc. Conf. on (p,n) Reactions and 
t h e  Nucleon-Nucleon Force", T e l l u r i d e ,  Colorado, 
1979, ed. C.D. Goodman, S.M. Austin,  S.T. Bloom, 
J.R. Rapaport, and G.R. Sa tch le r  (Plenum, New York, 
1980), p. 23. 
4) S. Cohen and D. Kurath, Nucl. Phys. 73, 1 (1965). 
5 )  J.R. Comfort, G.L. Moake, C.C. Fos te r ,  P. Schwandt, 
C.D. Goodman, J. Rapaport and W.G. Love, Phys. 
Rev. C 24, 1834 (1981). 
Figure 2. Analyzing power measurements compared wi th  
DWBA c a l c u l a t i o n  f o r  t he  5/2' s t a t e  of 13c  a t  7.55 MeV. 


Analyzing Power Measurements for 13-C(p,p') at 120 MeV

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Analyzing Power Measurements for 13-C(p,p') at 120 MeV

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