This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Anderson, B.D.

Baldwin, A.R.

Eden, T.

Foster, C.C.

Madey, R.

Manley, D.M.

Steinfelds, E.

Watson, J.W.

Zhang, W.-M.

English

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5. Y. Wang, C.D. Goodman, W. Huang, G.C. Kiang, T.N. Taddeucci, R.C. Byrd, T.  
Carey, B. Sailor, L.J. Rybarcyk, C.A. Gaarde, D.J. Horen, J .  Rapaport, E. Sugarbaker, 
D. Marchlenski and J .  Wagner, IUCF Scientific and Technical Report, May 1988-April 
1989, p.48. 
6. J. Rapaport, C. Gaarde, J .  Larsen, C. Goulding, C.D. Goodman, C. Foster, D.J. 
Horen, T. Masterson, E. Sugarbaker, and T.N. Taddeucci, Nucl. Phys. A431, 301, 
(1984). 
P-A MEASUREMENTS IN THE 48Ca(p,n)48Sc REACTION AT 135 MeV 
B.D. Anderson, W.-M. Zhang, J.W. Watson_, A.R. Baldwin, 
T. Eden, D.M. Manley, R. Madey, and E. Steinfelds 
Kent  State U n i v e r ~ i t y ,  Ken t ,  Ohio 44242 
C.C. Foster 
Indiana U n i u e r ~ i t y  Cyclotron Facility, Bloomington, Indiana 4 7405 
We measured the polarization (P) and the analyzing-power (Ay)  for the 48 Ca(p,n)48 Sc 
reaction at 135 MeV with the beam-swinger facility at the Indiana University Cyclotron 
Facility (IUCF). The experiment was performed using the improved transmission from the 
polarized ion source. The beam intensity was 400-600 nA of protons with a polarization 
of about 72%. The KSU neutron polarimeterl was located along the 0" swinger line at a 
flight path of 37 m; the energy resolution was about 1 MeV. This polarimeter uses three 
BC-517L liquid scintilla.tor neutron analyzers together with six plastic scintillator "side" 
detectors and provides an analyzing power of about 0.35 for neutrons of about 120 MeV. 
These measurements extend our earlier cross ~ e c t i o n , ~  analyzing-power,3 and spin-transfer4 
measurements for this reaction. 
The target nucleus, 48Ca, is understood to be a relatively good closed-shell nucleus 
and the transitions induced by the (p,n) reaction are to predominantly one particle, one- 
hole ( l p lh )  states. The 1+ state at 2.52 MeV in 48Sc is believed to be predominantly 
(f,/, ,f$) and the I+ state at 16.8 MeV is believed to be predominately (fsI2 ,f$) The 
difference in the dominant l p l h  structures of these two 1+ excitations is expected to affect 
the difference P - Ay strongly. Love and Comfort5 shows that for transitions with a single 
shell, one of the nonvanishing form factors for P = A is specified by the matrix element 
of the operator < i L x  a'>. They show that this matrix element will vanish for j(initia1) = 
j(fina1); thus, P and Ay are expected to be the same for the low-lying 1+ excitation, but we 
expect a significant difference for the state at 16.8 MeV. "Standard" nonrelativistic DWIA 
calculations support these expectations, in fact, the signs of P and Ay are predicted to be 
opposite over the entire angular range for the high-lying 1'- excitation. 
Results for a, aP,  and aA for the 48Ca(p,n)48Sc reaction at 5" are shown in Fig. 1. 
These results are qualitatively in agreement with the arguments presented above. The low- 
I I I I I I I I I 
4B~a(p.n)4$c 
Ep=135 MeV 
2.52 o 
- 
I I I I 
0 10 20 30 40 
Excitation energy (MeV) 
Figure 1. Results for a, aP, and aA for the 48Ca(p,n)48S~ reaction at 135 MeV and 5.0". 
The ordinate scales are in arbitrary units. 
excitation part of the spectrum is dominated by (f712,fy,?2) I+ strength, which is expected 
to show little difference between P and Ay . Because the spectrum near the 16.8 MeV 
state is dominated by (fS12 ,f;b) 1+ strength, it is expected to show significant differences 
between P and Ay. At higher energies, the spectrum is dominated by quasi-free scattering, 
for which P and Ay are expected to be nearly identical. 
Figure 2 shows the extracted results for P, A,, and P-A for the transitions to the 
2.52 and 16.8 MeV states at 0' and 5".  The solid lines show the DWIA predictions. Both 
P and A are seen to be zero at 0 ° ,  as expected. At 5O, it is seen that Av has opposite 
signs for these two transitions. The DWIA calculations correctly predict the signs of both 
P and A in each case, but consistently underestimate the magnitudes. Analysis at larger 
angles is in progress. 
48Ca(p,n)48~c (I+, 2.52 MeV)  
135 MeV 
0.5 I I I I 
0.4 - - DWIA - 
4 8 ~ a ( p , n ) 4 8 ~ c  (I+,  16.8 M e V )  
135 MeV 
Figure 2. P, Ay and P-A angular distributions for the 48 Ca(p,n)48 sc reaction at 135 MeV 
to the I+ states at 2.52 and 16.8 MeV. 
0.5 
0.4 
0 3  
1. J.W. Watson e t  al., Nucl. Instrum. Meth. A272, 750 (1988). 
2. B.D. Anderson e t  al., Phys. Rev. C31, 1161 (1985). 
3.  B.D. Anderson e t  al., Phys. Rev. C34, 422 (1986). 
4. J.W. Watson e t  al., Phys. Lett. B181, 47 (1986). 
5. W.G. Love and J.R. Comfort, Phys. Rev. C27,  2135 (1984). 
I 1 I I 
- - DWLA - 
- - 
02 - 
0.1 - 
a 
-0.1 
-02 
-0.3 
-0.4 
-0.5 
- - 
- - 
- - 
- - 
I I 1 I 
0 2 4 8 1 0  


P-A Measurements in the 48-Ca(p,n)48-Sc Reaction at 135 MeV

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P-A Measurements in the 48-Ca(p,n)48-Sc Reaction at 135 MeV

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