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

Foster, C.C.

Rapaport, J.

Walker, G.E.

Ward, T.E.

English

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nucleus. 
In conclusion, we observed strong excitation of a 
0 h w  stretched state in the 48~a(p,n)48~c reaction 
at 160 MeV, namely, the 7+ state at 1.096 MeV, with a 
,vf-l ) major con£ iguration; however, we found ("712 712 
no evidence for 1 h w  stretched states based on 
,vf'l )8' or (nf ,vd'l )6' configurations. The 
(1g9/2 712 712 512 
excitation of stretched states of the 0 %w type should 
prove to be a useful tool for studying the isovector- 
tensor term of the effective nucleon-nucleon inter- 
action. 
1) W.G. Love in The (p,n) Reaction and the Nucleon- 
Nucleon Force, ed. by C.D. Goodman et al. (Plenum, 
New York, 1980), p. 23. 
2) R.A. Lindgren, W.J. Gerace, A.D. Bacher, W.G. Love, 
and F. Petrovich, Phys. Rev. Lett. 42, 1524 (1979). 
3) R.S. Henderson, B.M. Spicer, I.D. Svalbe, V.C. 
Officer, G.G. Shute, D.W. Devins, D.L. Friesel, 
W.P. Jones, and A.C. Attard, Aust. J. Phys. 32, 411 
(1979). 
4) G.S. Adams, A.D. Bacher, G.T. Emery, W.P. Jones, 
R.T. Kouzes, D.W. Miller, A. Picklesimer, and G.E. 
Walker, Phys. Rev. Lett. 2, 1387 (1977). 
5 )  A.D. Bacher, G.T. Emery, W.P. Jones, D.W. Miller, 
G.S. Adams, F. Petrovich, and W.G. Love, Bull. Am. 
Phys. Soc. 32, 945 (1978); and to be published. 
6) B.D. Anderson, M. Ahmad, A.R. Baldwin, A. Fazely, 
R. Madey, J.W.-Watson, and C. C. Foster, Bull. Am. 
Phys. Soc. 2, 729 (1980). 
7) P.J. Moffa and G.E. Walker, Nucl. Phys. A=, 140 
(1974). 
8) T.W. Donnelly and G.Ei Walker, Ann. Phys. (N.Y.) 
60, 217 (1970). 
- 
9) C. Gaarde, J.S. Larsen, M.N. Harakeh, S.Y. van der 
Werf, M. Igarashi, and A. Muller-Arnke, Nucl. Phys. 
A334, 248 (1980). 
10) J. Raynal and R. Schaeffer, Computer code DWBA70. 
11) P. Schwandt, A. Nadasen, P.P. Singh, M.D. 
Kaitchuck, W.W. Jacobs, J. Meek, A.D. Bacher, and 
P.T. Debevec, IUCF Technical and Scientific Report 
for Feb. 1, 1977 to Jan. 31, 1978, p. 79. 
MEASUREMENT OF THE 1 / ~  DEPENDENCE OF THE 7~i(p,n)7~e 
TOTAL REACTION CROSS SECTION 
T.E. Ward, C.C. Foster, and G.E. Walker 
Indiana University Cyclotron Facility, Bloomington, Indiana 47405 
J. Rapaport 
Ohio University, Athens, Ohio 43701 
The excitation function, a(E) , of the 7~i(p,n)7~e 
reaction was measured in the intermediate energy range 
of 60-199 MeV using activation techniques and y-ray 
spectroscopy. This method has been used to measure the 
total cross section at energies of 25-44 MeV by Shery 
et a1.l) and at 120 MeV by Goulding et a ~ . ~ )  to
calibrate large volume neutron detectors. Details of 
the experimental procedure can be found in the IUCF 
1979 annual report.3) A summary of the results is given 
in Table 1. The total errors estimated for these 
measurements range from 8 to 14%. 
The measured1s4) excitation function, a(E), of 
the 7~i(p,n)7~e total reaction cross ssection is 
observed to vary inversely with the incident proton 
energy, E, from 25 to 200 MeV. A theoretical analysis, 
assuming the PWIA with an energy-independent, 
very-short-range interaction, using harmonic oscillator 
wave functions and neglecting exchange effects, yields 
a 1 1 ~  dependence for the summed inelastic scattering 
differential cross section to a particular state. This 
result implies that a(E) = 725.3 (11E) - 0.295 with a 
in millibarns, E in MeV and a determinant coefficient 
of 0.998. 
Further, it implies that the interaction strength 
Table 1. Measured total cross-sections for the 
-~e (g.8. + 0.429 MeV) reaction. 
PROTON MEASURED PROTON MEASURED 
ENERGY CROSS SECTION ENERGY CROSS SECTION 
Ep(Mea) cm2) Ep(MeV) ( 10-27 ~~2 ) 
2 2 function (V, + 2.36 y,, ) is independent of incident 
proton energy. Using recently reported 
determinations5) of V, and V, at 24.8, 35 and 45 MeV, 
2 2 
(V, + 2.36 V, ) = 537 M ~ V ~  is obtained. Figure 1 is 
a plot of I V, I and I v, I versus E. The solid curves 
were calculated using this relation and experimental 
 value^^,^) of (V,,/V,)~ at 24.8, 35, 45, 80 and 120 
MeV. The dashed curves are based on a reasonable 
extrapolation of the observed energy dependence6) of 
(v,, /v, )2 
A manuscript of this work is presently in 
preparation and will be submitted for publication. 
2L I 40 I 60 I 80 100 I ~ I ~ I ~ I ~ I ~ I  120 140 I60 180 200 
E (MeV) 
Figure 1. Plot of 1 V, I and I v, / vs . E for the 
7~i(p,n)7~e reaction. 
1) S.D. Schery et al., Nucl. Instr. Methods 147, 399 
(1977). 
2) C.A. Goulding et.al., Nucl. Phys. A331, 29 (1979). 
3) IUCF Scient. and Techn. Report 1979, p. 28. 
4) C.C. Foster et al., Bull. Am. Phys. Soc. 24, 828 
(1979). 
5) S.A. Austin et al., preprint (1980). 
6) J. Rapaport et al., Bull. Am. Phys. Soc. 830 
(1979). 


Measurement of the 1/E Dependence of the 7-Li(p,n)7-Be Total Reaction Cross Section

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Measurement of the 1/E Dependence of the 7-Li(p,n)7-Be Total Reaction Cross Section

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