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

Kim, Y.D.

Kwiatkowski, K.

Lynch, W.G.

Murakami, T.M.

Nayak, T.K.

Pelak, R.

Planeta, R.

Rose, S.

Tsang, M.B.

Viola, V.E.

Woo, L.W.

Xu, H.M.

Yennello, S.J.

Zhang, J.

Zhu, F.

English

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TWO-PARTICLE CORRELATION FUNCTIONS FOR 
THE 200-MeV 3He + Ag REACTION 
I?. Zhu, T.M. Murakami, T.K. Naya,k, W.G. Lynch, M.B. Tsang, Y.D. Kim, 
R. Pelak, H.M. Xu, 
Michigan State Univer~ity, East Lansing, Michigan 4 8824 
K. Kwiatkowski, L.W. Woo, S.J. Yennello, S. Rose, R. Planeta, J .  Zhang and V.E. Viola 
Indiana Univer~it y Cyclotron Facility, Bloomington, Indiana 4 7405 
Pa.rticle-particle correlations at small relative momenta have been frequently employed 
to investigate the temperature, source size and time evolution associated with the emission 
of complex fragments from highly excited nuclear mattter.ly2 In the present study we have 
atpplied the particle-particle correlation technique to the 200-MeV 3He + Ag system, where 
inclusive studies indicate that complex fragments emitted at forward angles arise from fast, 
non-equilibrium processes, whereas those emitted at backward angles appear to have their 
origin in the decay of an equilibrated conlpound n u ~ l e u s . ~  
Measurements were performed in the IUCF 152-cm scattering chamber with a 2 mm 
diameter, halo-free 3He bea%m incident on a high-pnrity Ag taxget of thickness TOO pg/cm2. 
Isotopically resolved hydrogen and helium ions, as well as 2-identified intermediate mass 
fragrnents were detected by a close-packed array of thirteen position-sensitive telescopes.* 
Two settings of the array were employed, one centered at 4Z0 in the laborastory and the 
other at a backward angle. Each telescope consisted of an x-y position-sensitive propor- 
tional counter, a planar silicon-surface-barrier detector and a 5-mm lithium drifted silicon 
detector. 
The two-particle coincidence yield, Y12 ($1 ,G2), for ejectile la,boratory momenta. and 
pi, contains contributions from the sequential decay of particle-unstable excited states as 
well as from the coincident ernissio~l of non-resonant particles. For particle pairs of relative 
momentum q, the correlation function, R(q), is defined in ternis of the coincidence yield 
and the single particle yields, Y1 (sl) and Y2 ($2): 
The normalization constant, C12 is determined by the requirement that R(q) = O for large 
relative moment a. 
Correlation functioris for 'Li decay with the array at 42" axe shown in Fig. 1. Strong 
correlations for decay of the ground state (p + a )  and the 16.66 MeV excited sta,te 
(d+3He) are evident. These correlations are among the strongest ever observed in 
intermediate-energy nuclear reactions, being up to a factor of two greater than those found 
in most heavy-ion-induced reactions. 
1. S. Koonin, Phys. Lett. 70B, 43 (1977). 
2. J. Pochodzalla., et al., Phys. Rev. C23, 1695 (1987). 
3. K. Kwiatkowski, et al., Phys. Lett. B171,  41 (1986). 
4. T. Mura.kami, et al., Nucl. Instr. Meth. Phys. Res. A275, 122 (1989). 
Figure 1. Particle-particle corre- 
lastion function, R(q), as a func- 
tion of relative laboratory momen- 
tum q of the pair for 5Li* decay 
from: (top) ground state to p + a 
channel, and (bottom) 1G.6 MeV 
excited state to D + 3He channel. 
ANALYZING POWERS FOR COMPLEX FRAGMENTS FORMED 
I N  THE 200 MeV jj + Ag REACTION 
E. Renshaw, S.J. Yennello, K. Kwiatkowski, L.W. Woo, and V.E. Viola 
Indiana University Cyclotron Facility, Bloomington, Indiana 47405 
Studies of proton-induced reactions at 161 MeV1 and 200-500 MeV2 itldica.te that 
intermediate mass fragments (IMF: 3 < Z < 15) formed in tliese reactions originate primarily 
from a fast non-equilibrium mechanism. Previous studies with polarized bea8ms3 have 
shown zero analyzi~ig powers for IMFs emitted at angles larger than 60 degrees, indica.tirig 
that direct processes cannot account for these fragments. To investigate the possibility that 


Two-Particle Correlation Functions for the 200-MeV 3-He + Ag Reaction

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Two-Particle Correlation Functions for the 200-MeV 3-He + Ag Reaction

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