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

Breuer, H.

Gokmen, A.

Kwiatkowski, K.

Mathews, G.J.

Viola, V.E. Jr.

Ward, T.E.

Zhou, S.

English

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REACTIONS TO CONTINUUM FINAL STATES 
TOTAL MASS AND CHARGE DISTRIBUTIONS IN THE p + 27Al REACTION AT 180 MeV 
S. Zhou, K. Kwiatkowski, T.E. Ward and V.E. Viola, Jr. 
Indiana University Cyclotron Facility, Bloomington, Indiana 47405 
H. Breuer and A. Gokmen 
University of Maryland, College Park, Maryland 20742 
G.J. Mathews 
Lawrence Livermore Laboratory, Livermore, California 94550 
Total mass and charge distributions have been spectra were ~rovided by a conventional, three-element , 
measured for reaction products formed in the semiconductor detector telescope. 
interaction of 180-MeV protons with 27~l. The fragment An example of the mass yield curve for reaction 
mass distributions, d3a/dQd~dA, were measured with a products detected at 20° to the beam is shown in Fig. 
channel-plate, fast-timing semiconductor detector 1. Enhanced yields are observed for products with 
system which permitted discrete identification of all A=12, 16 and 20. This feature is characteristic of the 
nuclides with 0 6  and energies above 0.1 MeVjnucleon. observed spectra at all angles. This behavior 
Charge distributions, do3 /dQd~dz, were obtained with a presumably reflects the influence of ground-state 
gas-ionization, semiconductor detector telescope which Q-values during the evaporation stage of de-excitation. 
uniquely identified products with 2>3 for energies In Fig. 2 the angular distributions of selected 
above 0.25 MeVInucleon. Measurements of H and He 
4 6 8 10 12 14 16 18 20 22 24 26 28 
MASS NUMBER 
Fi ure 1. Mass spectrum at 20' resulting from the 
bo:bardment of 27Al by 180 MeV protons. 
Figure 2. Angular distributions for A=6, 12, 16, 20 
and 25 isobars produced by the reaction of 180 MeV 
protons with 27~1. 
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 


Total Mass and Charge Distributions in the p + 27-Al Reaction at 180 MeV

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Total Mass and Charge Distributions in the p + 27-Al Reaction at 180 MeV

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