This work was supported by the National Science Foundation Grants NSF PHY 78-22774 A03, NSF PHY 81-14339, and by Indiana Universit

Boyd, R.N.

Chang, C.C.

Chant, N.S.

Ciangaru, G.

Donoghue, T.R.

Hall, J.R.

Maher, J.

Nadasen, A.

Roos, P.G.

Saber, M.

Segel, R.

Singh, P.P.

Stephenson, E.J.

Wesick, J.

Zupranski, P.

English

IUScholarWorks

fragments are plotted. The lighter fragments exhibit These data will be used to examine existing 
forward-peaked angular distributions; but, as the cascade-evaporation codes1 and total reaction cross 
fragment mass increases, there is a systematic section predictions.2 In addition they are of interest 
enhancement of the yields at backward angles near the to problems related to galactic cosmic ray transport 
target elastic recoil axis. Both the angular through the interstellar medium arid to microcircuit 
distributions and the associated energy spectra are upsets in semiconductor devices aboard space 
consistent with a picture in which the light fragments satellites. 
originate largely from high deposition-energy events, 
1) K. Chen, Z. Frankel, G. Friedlander, J.R. Grover, 
whereas the heavier fragments are associated with J.M. Miller, and Y. Shimamoto, Phys. Rev. 166, 949 
(1968); G.J. Mathews, Phys. Rev., to be published. 
simple cascade processes followed by statiscal decay 
2) J.C. Peng, R.M. DeVries, N.J. DiGiacomo, Phys. Lett. 
involving smaller amounts of excitation energy. - 98B, 244 (1981). 
ANALYZING POWER OF THE PROTON CONTINUUEl FOR 150 AND 200 MeV POLARIZED PROTONS ON 12c AND 58,62~i 
C.C. Chang, N.S. Chant, G. Ciangaru, A. Nadasen, P.G. Roos, and J. Wesick 
University of Maryland, College Park, Maryland 20742 
J.R. Hall, M. Saber, P.P. Singh, and E.J. Stephenson 
Indiana University Cyclotron Facility, Bloonington, Indiana 47405 
R.N. Boyd and T.R. Donoghue 
Ohio State University, Columbus, Ohio 43210 
R. Seyel and P. Zupranski 
Northwestern University, Evanston, Illinois 60201 
J. Maher 
University of Pittsburgh, Pittsburgh, Pennsylvania 15260 
The inclusive neutron and charged-particle cases, only suggestive. 
continuum spectra induced by the bombardment of many One experiment which can shed some light on the 
target nuclei by medium energy protons have been well importance of the QFNN scattering mechanism is to 
+ 
studied.ls2 One common feature of the energy spectra measure the (p,p') analyzing power, A(E,8), of the 
is that the yields to the continuum are large and very continuum as a function of the detection angle. It is 
forward peaked. Efforts in the past few years have expected that if the QFNN scattering mechanism is 
concentrated on attempting to understand the major indeed an important mechanism, the measured A(E,B) for 
nuclear reaction mechanisms by which the incident the (p,p') continuum should be predictable from the 
proton dissipates its energy to the target nucleus, free p-p and p-n analyzing powers, appropriately folded 
resulting in the continuum part of the energy spectra. with the momentum distribution of the struck nucleons 
Two major competitive mechanisms have been in the target nucleus and corrected for the mean field 
proposed; (1) the quasifree nucleon-nucleon (QFNN) effects. 
scattering mechanism and (2) the collective multipole, Initial measurements of the analyzing powers of 
excitation mechanism. The evidences in support of outgoing protons, deuterons and tritons for 150 and 200 
these two mechanisms, although numerous, are in some MeV polarized proton beams on 12c and 58s62~i targets 
have been made. At 150 MeV, the outgoing particles 
were detected with two identical telescopes, located 
symmetrically on both sides of the beam. Each 
telescope consisted of a 100 pm (or 60 pm) and a 1 mm 
silicon surface barrier AE-detector followed by a 2"x3" 
NaI(TR) E-detector. Such a symmetric geometry, 
combined with a fast spin-flip of the beam 
polarization, eliminates many systematic errors to 
first order. At 200 MeV, only one telescope, 
consisting of a 100 pm and a 1 mm silicon AE-detector 
followed by a 5" deep NaI(TR) E-detector, was used. 
Therefore, only spin-up and spin-down measurements were 
made and were used in the calculation of analyzing 
powers. 
Figures 1-5 show the preliminary results for 
12c(;,pt) at Ep = 150 and 200 MeV. Similar data were 
obtained for 58,62~i targets at both energies (Fig. 6). 
Fi ure 1. Cross sections and analyzing powers for the 
refction 12~(p,ptx) at eL=300 and Ep = 150 MeV. 
Figure 2. Cross sections and analyzing powers for the 
reaction 12~(p,p'x) at eL=400 and Ep = 150 MeV. 
Figure 3. Cross sections and analyzing powers for the 
reaction 12~(p,ptx) at eL=500 and Ep = 150 MeV. 
Ep=*OO MeV Cross Section 
0 75 150 
E (MeV) 
16 C Ep=200 Mev cross Section 1 
(Arb. Units) I 
+ 0.5 Analyzing Power 
0 
- 0 .5  
I 
0 75 150 
E (MeV) 
Figure 4. 
reaction 
(The gap 
, Cross sections and 
12C(p,p'x) at eL=200 
at -20 MeV is due to 
analyzing powers for the Fi ure 5. Cross sections and analyzing powers for the 
lab. and Ep = 200 MeV. regction 12C(p,p'x) at eL=400 lab and Bp - 200 MeV. 
the dead layer on the NaI 
detector. An energy dependent correction that 
increases with energy remains to be made to the cross 
section.) 
For all targets, the analyzing powers are positive for If the QFNN scattering mechanism is indeed a 
eL<400, near zero for eL=400, and become negative and dominant mechanism for energy dissipation of the 
+ 
smaller for 81)40°. At the high energy (or low incident proton, the measured (p,pt) analyzing powers 
excitation energy) end of the spectra, erratic of the continuum should be positive for eL<4S0 (loosely 
analyzing powers were observed because of the speaking, this corresponds to nucleon-nucleon 
contributions of different excited states and multipole center-of-mass scattering angles less than go0), near 
excitation. zero for eL=450, and negative for eL)45O. The observed 
Analyzing Power 1 
Ep=200 MeV 
- 
8= 20' 
n 
picture, although the collective excitation mechanism 
cannot be ruled out completely, especially for the 
spectra near the high energy end. 
The analyzing powers at backward angles measured 
in this experiment are vastly different from those 
obtained at Ep = 65 MeV. At Ep = 65 MeV, the analyzing 
powers at large angles are large, especially at low 
excitation. These large analyzing powers at low 
/ excitation regions might be due to collective 
excitations. 
Calculations are now being carried out in which 
the plane wave impulse 'approximation (PWIA) expression 
for quasifree nucleon knockout is integrated over the 
/ 
direction of the undetected outgoing nucleon. In the 
near future, distorted-wave impulse approximation 
calculations of the quasifree mechanism as well as 
collective excitation will also be performed. 
1) J.R. Wu, C.C. Chang, and H.D. Holmgren, Phys. Rev. C 
19, 698 (1979). 
-
0 75 150 
E (MeV) 
2) B.A. Anderson et al., Phys. Rev. Lett. 46, 226 
(1981). 
Fi ure 6 Analyzing powers for the reaction 
at eLu200 , 40' and 50' and Ep = 200 MeV. 
THE ROLE OF NUCLEON-NUCLEON INTERACTIONS IN PROTON-INDUCED REACTIONS ON 5 8 ~ i  AT 200 MEV 
C.C. Chang, G. Ciangaru, H.D. Holmgren, A. Nadasen, and P.G. Koos 
University of Maryland, College Park, Maryland 20742 
A.A. Cowley and S. Mills 
Council for Scientific and Industrial Research, South Africa 
J.R. Hall, M.K. Saber, and P.P. Singh 
Indiana University Cyclotron Facility, Bloomington, Indiana 47405 
As part of an effort to study the importance of component of the charged-particle coincidence yield is 
the quasifree nucleon-nucleon (QFNN) scattering as a associated with the emission of at least two fast 
dominant process in dissipating the incident proton protons. Furthermore, it was observed that the 
energy, a series of particle-particle coincidence secondary proton energy spectra at various angles, 
studies were previously carried out at Maryland using detected in coincidence with primary protons emitted at 
100 MeV protons on 58~l.1 It was found that the major 15' with energies between 30 and 50 MeV, have the same 


Analyzing Power of the Proton Continuum for 150 and 200 MeV Polarized Protons on 12-C and 58,62-Ni

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Analyzing Power of the Proton Continuum for 150 and 200 MeV Polarized Protons on 12-C and 58,62-Ni

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