This work was supported by the National Science Foundation Grant NSF PHY 78-22774 A02 & A03 and by Indiana Universit

Collins, J.C.

Foster, C.C.

Friesel, D.L.

Hall, J.R.

Jacobs, W.W.

Jones, W.P.

Kaitchuck, M.D.

Schwandt, P.

Stephenson, E.J.

English

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ANALYZING POWERS FOR DEUTERON-INDUCED 
REACTIONS LEADING TO CONTINUUM FINAL STATES 
E.J. Stephenson, J.C. Collins, C.C. Foster, D.L. Friesel, 
J.R. Hall, W.W. Jacobs, W.P. Jones, M.D. Kaitchuck and P. Schwandt 
Indiana University Cyclotron Facility, Bloomington, Indiana 47405 
In a recent article1), it was reported that the 
analyzing powers are large for protons that 
inelastically scatter to states in the continuum. 
Those analyzing powers rise with angle in a trend 
similar to the analyzing powers for elastic scattering. 
This suggests a connection between the spin-dependent 
distortions in the entrance channel and the trends of 
the analyzing powers regardless of the nature of the 
excited states. 
For intermediate-energy deuterons, the onset of 
rainbow scattering creates very large vector and tensor 
analyzing powers. The experiment described here was 
undertaken to see how far these trends persist for 
reactions to continuum states. The cross sections were 
already availableS2) along with a comparison to a 
calculation assuming that the projectile energy was 
dissipated in the formation of particle-hole states in 
the target. 
The experiment was carried out in the 64-inch 
scattering chamber using three-element telescopes. The 
elements of the telescopes were chosen from various 
thicknesses of silicon and high-purity germanium to 
provide information on the outgoing p, d, t, 3He and 
4 ~ e  fragments at energies between 20 and 100 MeV. In 
front of each telescope, the collimating slit was made 
of plastic scintillator (see Figure 1). Its signal was 
used to veto pulses in the telescope. This technique 
greatly reduces slit-edge scattering background. At 
angles where the elastic-scattering analyzing powers 
are large, this background could introduce some false 
false spin dependence into the continuum spectrum. 
ACTIVE COLLIMATOR 
HIGH- 
PURlf Y 
Ge SCINTILLATOR 
Figure 1. Layout of the active-collimator assembly 
showing two elements of the detector telescope. This 
collimator fits in front of the window of the 
germanium-detector cryostat. The solid collimator 
(hatched area) is beveled to eliminate scattering into 
the telescope system. 
The deuteron beam energy was 80 MeV. Both vector 
(Ay) and tensor (Ayy) analyzing powers were measured at 
angles between 30' and 105" in the laboratory. The 
target was chosen to be 5 8 ~ i  to maintain compatibility 
with the earlier studies of elastic scattering. 
A sample analysis of the vector and tensor 
analyzing powers for inelastic deuteron scattering is 
shown in Figure 2 as a function of excitation energy in 
the final nuclear system. Points analyzed in the 
continuum are indicated by a horizontal bar giving the 
excitation energy range over which they apply. The 
analyzing powers for the transitions to discrete final 
states are remarkably similar at large angles, 
powers in the continuum. This result reaffirms that 
the spin-orbit distortions in the entrance channel 
largely control which projections of the incoming beam 
can initiate reactions. It is this distortion, and not 
the structure of the excited nuclear system, that 
dominates the analyzing power for inelastic scattering 
and particle transfer reactions at large scattering 
angles. If structure information is to be obtained, it 
indicating an absence of diffraction pattern may well appear only in-relative changes in the tensor 
information on the configuration of the final nucleus. analyzing powers. 
These analyzing powers are all similar to that for 
elastic scattering. 
In the continuum, the vector analyzing power 
58 / 58 Ni (d,d ) Ni 80 MeV 60' 
remains large, even at very high excitation. This is 
' * O O  
true also for the (d,p) reaction channel, but not for I I 
(d,t), (d,3~e), or (d,a). In these latter cases, the 
analyzing power falls much more quickly to zero. 
The tensor analyzing power Ayy also falls quickly 0.5 
to zero with increasing excita ion energy. For elastic 
scattering, the large values of Ay and A,, mean that \ + 
the scattering is dominated by deuterons from the m-l-1 +++ 
substate in the primary beam. However, in the 
continuum, the analyzing powers are characterized 
rather by the absence of the m=-1 substate. This YY 
change suggests a sensitivity of the m=O projection to I I I I I I 
the structure of the final nucleus, an implication that 60 40 20 0 
will be pursued in future experiments on particular 
reactions. Fi ure 2. Vector (+) and tensor (Ayy) analyzing 
poters for deuterons inelastically scattered from 5 8 ~ i  
These conclusions are quite similar to the results as a function of the excitation energy. 
-- obtained at 56 MeV at ~saka.~) In addition, they 
measured + and found negative values for the discrete 
1) H. Sakai, K. Hosono, N. Matsuoka, S. Nagamachi, K. 
states, and tensor analyzing powers going rapidly to Okada, K. Naeda, and H. Shimizu, Phys. Rev. Lett. 
44, 1193 (1980). 
-
zero in the excitation region of the continuum. These 
2) J.R. Wu, C.C. Chang, and H.D. Holmgren, Phys. Rev. 
negative values for A,, agree with the trends given in C g ,  370 (1979). 
optical-model calculations for elastic scattering. 3) H. Sakai, N. Matsuoka, K. Hatamaka, K. Okada, and H. 
Shimizu, Annual Report of the Research Center for 
Like protons, deuterons show large vector analyzing Nuclear Physics, Osaka, 1979. 


Analyzing Powers for Deuteron-Induced Reactions Leading to Continuum Final States

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Analyzing Powers for Deuteron-Induced Reactions Leading to Continuum Final States

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