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

Bacher, A.D.

Baghaei, H.

Betker, A.C.

Carr, J.A.

Franklin, W.A.

Lindgren, R.A.

Petrovich, F.

Prout, D.L.

Stephenson, E.J.

Wissink, S.W.

Yu, C.

English

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Scattering Angle (c.m.) 
Figure 2. The cross section, Dx and D, angular distributions for the isoscalar transitions 
in 1°B (5, jY)I0B. The curves represent the effective interaction of Seifert, e t  al. 
MEASUREMENT OF THE REMAINING IN-PLANE POLARIZATION TRANSFER 
COEFFICIENTS FOR THE 1°B(p', jY)loB REACTION AT 200 MeV 
A.C. Betker, A.D. Bacher, W.A. Franklin, D.L. Prout, 
E.J. Stephenson, S.W. Wissink, and C. Yu 
Indiana Universi ty  Cyclotron Facility, Bloomington,  Indiana,  4 74 0 8  
H. Baghaei and R.A. Lindgren 
Universi ty  of Virginia, Charlottesville,  Virginia 22901 
J.A. Carr and F. Petrovich 
Florida S ta t e  Universi ty ,  Tallahassee, Florida 32206 
In order to understand the modification of the nucleon-nucleon force within the nuclear 
medium, we have undertaken the measurement of several "stretched states'' that have 
well understood structure. In the case of 1°B the state of interest is the the 0+ state 
at 1.74 MeV. This transition has a single-particle, single-hole configuration with a well 
determined magnetic form-factor from electron scattering studies,' is an isospin AT= 1 
transition, and because of its low excitation energy, is cleanly accessible to large momentum 
transfer. Previous experiments2j3 have measured cross-section daldfl, analyzing power A, 
induced polarization P, normal component spin transfer DNN and two combinations of the 
four in-plane spin transfer coefficients, denoted as D, and Dx. These experiments have 
been performed with the K600 spectrometer and have utilized its high resolution properties 
to separate the state of interest from other nearby states. 
Parity conservation permits polarimeters to measure only the in-plane projection of the 
scattered proton polarization that is sideways at the polarimeter's carbon analyzer target. 
Precession in the K600 spectrometer's magnetic field yields two linear combinations, D, 
and Dx, of the four in-plane polarization transfer coefficients as the observables associated 
with sideways and longitudinal beam polarization. They are given by 
D, = Dsa cos a + DSL1 sin a, and 
DX = DLSl cos a + DLL1 sin a 
where a is the spin precession angle through the K600. For the previous data set a = 235'. 
This experiment utilized the new "super-low" dispersion mode of the K600, described 
elsewhere in this report,4 to repeat the in-plane spin transfer measurements with a E 300'. 
Once these data are analyzed, this will allow us to extract all four of the standard in-plane 
spin transfer coefficients. 
These new measurements were performed at Olaa=200, 31°, 40°, 48", and 60°, the 
same angles at which the other in-plane data were taken. The best resolution achieved 
was 40 keV FWHM, although most of the data was taken with thick targets to maximize 
data rate. Resolution was most critical at 31' and 48", where the state of interest is close 
to contaminant states from "B and l2 C in the target. A resolution of 150-200 keV, which 
was typical, was sufficient for this purpose. 
The data were taken with three different settings of the spin precession solenoids in 
the high energy beam lines. While two settings are sufficient to obtain longitudinal and 
sideways measurements, using three settings, spaced about 60' apart, gave a simultaneous 
systematic evaluation of the system. At all five scattering angles, the measured asymmetry 
was well reproduced by a sinusoidal function of the in-plane spin direction. 
The previous data are shown in Fig. 1. The curves are from DW81 calculations5 with 
different t-matrices to describe the interaction. The t-matrix was parameterized with three 
terms: 
t ( p )  =  FREE + A ~ M O D  p + A~PAULI(P)  
where p is the local nuclear density. This was motivated by QCD sum rule calcula- 
tions which suggest that the density-dependence that arises from nucleon and meson sub- 
structure varies linearly with density over the range sampled by our experiment .6 Since we 
wish to characterize this piece of the density-dependence using our data, a phenomenolog- 
ical term, AtMoD p, has been included. The  FREE term is similar to the Franey-Love 
t - m a t r i ~ , ~  but is derived directly from the SM93 nucleon-nucleon phase shift solution at 
200 MeV by Arndt,8 and as such is better constrained because it is based on significantly 
more, higher precision data. The AtPAuLI(p) term is the change in the t-matrix due to 
l%(P,P')l% 3+ + O+ Observables 
Figure 1. Previously measured lo B 3+ + 0+ observables, along with DWB A calculations. 
The dashed lines represent a t-matrix composed of C FREE + AtPAULI(p). The solid curves 
include an additional phenomenological term, AtMoD - p. 
binding energy and Pauli blocking in the medium as calculated by Nakayama and Love.g 
In Fig. 1, the dashed curve includes the SM93 t-matrix and the Pauli term, while the solid 
curve includes all three terms. The phenomenological term, parameterized as density- 
dependent changes to the J< 2 nucleon-nucleon phase-shifts of SM93, was adjusted to 
best reproduce the data in Fig. 1. 
As a test of the quality of the phenomenological adjustment, predictions, shown in 
Fig. 2, were made for the new measurements. On-line data points from an experiment 
completed in March, 1995 are included. After a complete analysis, st atistical precision is 
expected to improve slightly, and any systematic effects will be included. 
It appears that the phenomenological modification that was appropriate for the pre- 
vious data is worse that no modification for the new data. Thus the new measurements 
contain constraints that were not present in the old analysis, and they will clearly be useful 
in specifying the character of the in-medium interaction. A full set of polarization-transfer 
coefficients will now allow the separation of the data into pieces that are sensitive to indi- 
vidual KMT amplitudes and the individual transverse and spin-longitudinal responses of 
the nucle~s. '~ Future studies of the in-medium effects will be pursued along these lines. 
Figure 2. Predictions for D, and Dx at or = 305O, along with the new data points. The 
curves are described in Fig. 1. 
1. R.S. Hicks, e t  aL, Phys. Rev. Lett. 60, 905 (1988). 
2. H. Baghaei, e t  aL, Phys. Rev. C 69, 2054 (1992). 
3. S. Chang, e t  al., IUCF Sci. and Tech. Rep., May 1992 - April 1993, p. 16. 
4. A.D. Bacher, e t  al., this report. 
5. R. Schaeffer and J. Raynal, program DW81, private communication. 
6. For example, T. Hatsuda and S. Huong Lee, Phys. Rev. C 43,213 (1991); M. Asakawa 
and C.M. KO, Phys. Rev. C 48, R526 (1993). 
7. M.A. Franey and W.G. Love, Phys. Rev. C 31,488 (1985). 
8. R. Arndt, private communication. 
9. K. Nakayama and W.G. Love, Phys. Rev. C 38, 51 (1988). 
10. E. Bleszynski, M. Bleszynski, and C.A. Whitten, Jr., Phys. Rev. C 26, 2063 (1982); 
J.M. Moss, Phys. Rev. C 26, 727 (1982). 


Measurement of the Remaining In-Plane Polarization Transfer Coefficients for the 10-B(p,p') 10-B Reaction at 200 MeV

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Measurement of the Remaining In-Plane Polarization Transfer Coefficients for the 10-B(p,p') 10-B Reaction at 200 MeV

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