A set of compact ionization chamber-Si(IP)CsI(Tl) telescopes for multifragmentation studies are described. These ion chamber telescopes can be used either individually, or to augment the MSU Miniball 4π array. The characteristics of the large-area passivated, ion implanted Si detectors are investigated. Statistics on the overall planarity of these detectors as well as, the thickness of dead layers present at the surface of this type of detectors are examined.

The spatial-temporal extent of the emitting system for central collisions in Kr-84 + Au-197 at E/A = 35, 55, and 70 MeV is probed using fragment-fragment velocity correlation functions. Selection on fragment pairs of high velocity yields a stronger fragment-fragment Coulomb interaction than for inclusive fragment pairs. This result is consistent with fragment emission from a source of decreased spatial-temporal extent. The universality of this association and the effect of different selection criteria are explored. The sensitivity of the spatial-temporal extent deduced by the correlation function technique to measurement uncertainties, assumed source characteristics, and rotational effects is assessed.

Fragment emission patterns occurring in nuclear systems of modest excitation are studied. Exclusive measurement of fragment emission in 14N+197Au reactions at EA = 100, 130 and 156 MeV allows selection of central collisions where a single source dominates the decay. Low threshold measurement of IMF emission for these events allows investigation of the influence of detector threshold effects. The time scale of fragment emission is deduced using fragment-fragment velocity correlations. Comparisons are made to the predictions of a statistical decay model.

W. A. Friedman Department of Physics, University of Wisconsin, Madison, Wisconsin 53076 (Received 22 May 1996) Multifragment decays of central collisions in 84Kr 1 197Au at EyA ­ 70 MeV are studied. By utilizing a technique sensitive to the emission order of fragments, it is deduced that carbon fragments are emitted prior to beryllium fragments when these fragments have the same velocity. This observation is consistent with the cooling of a thermally decaying source. [S0031-9007(96)01726-7]

Fragment emission depends strongly on the angular momentum of the emitting system. To explore the systematic behavior of rotational effects in central collisions, we have studied several systems over a large range of bombarding energies. The systems investigated include {sup 14}N+ {sup 197}Au at E/A = 100-156 MeV, {sup 36}Ar+{sup 197}Au at E/A = 35-110 MeV, and {sup 84}Kr+{sup 197}Au at E/A = 35-70 MeV. To probe for evidence of rotation in central collisions (b/b{sub max}< 0.2), we have examined azimuthal correlation functions for fragments (4 < Z < 9). Predictions of a rotating source model are used to deduce the magnitude of rotational effects which persist for central collisions.

Multifragment decays of central collisions in {sup 36}Ar+{sup 197}Au at E/A = 35-35-110 MeV and{sup 84}Kr+{sup 197}Au at E/A = 35-70 MeV reactions are investigated. The spatial-temporal extent of the emitting system is probed using fragment-fragment velocity correlations. The dependence of the velocity correlation on the fragment energy is examined. The influence of rotation and radial expansion is investigated in the context of statistical models.

An experiment to synthesize element 110 by the 59Co+209Bi reaction has been performed at the SuperHILAC at the Lawrence Berkeley Laboratory. One event with many of the expected characteristics of a successful synthesis of 267110 was observed. This event corresponds to a production cross section of about one picobarn.

An experiment to synthesize element 110 by the Co-59+Bi-209 reaction has been performed at the SuperHILAC at the Lawrence Berkeley Laboratory. One event with many of the expected characteristics of a successful synthesis of (267)110 was observed. This event corresponds to a production cross section of about one picobarn.

Fragment emission in the reaction {sup 84}Kr+{sup 197}Au at E/A = 35, 55, and 70 MeV has been studied. Low threshold, high resolution detector telescopes together with the MSU Miniball 4{pi} detector array have been used in an exclusive experiment to measure intermediate mass fragments (IMF: 3{le}Z{le}20) emitted over a broad angular range. The dependence of the characteristics of the emitting source on the incident energy with impact parameter selection is examined using Galilei-invariant velocity distributions. Kinetic energy spectra, element distributions, and angular distributions associated with central collisions are utilized to characterize the source of the fragments.

Low threshhold, high resolution detector telescopes together with the MSU Miniball 4{pi} detector array have been used in an exclusive experiment to measure intermediate mass fragments (IMF: 3

Multifragment decays of central collisions in {sup 84}Kr +{sup 197}Au at E/A = 35, 55, and 70 MeV are studied. The dependence of the extracted emission time on the velocity of the fragment pair is investigated. More energetic pairs manifest a stronger Coulomb interaction indicating emission from a source of smaller spatial-temporal extent than less energetic pairs. This trend can be understood in the context of a statistical model which incorporates the de-excitation of the source as the fragments are emitted.