were to set B f z 0 . 8 3 ~ ~ ~ ~ ~ and af/a,=l.OO, as suggested f i n Ref. 8, but using our more sophisticated level density treatment, the calculated afiss would substantially exceed the measured values at all bombarding energies for all three systems, and the fission-fragment anisotropies measured for 6~i + Ig7~u would be overpredicted by -25%. We conclude that the differing claims in Refs. 6 and 8 concerning high-spin fission barrier heights for A-200 can be largely attributed to differences in the underlying assumptions and philosophy of the statistical model analyses, although certainly differences in experimental technique and in contributions from competing reaction mechanisms may further cloud the comparison. Our calculations adequately explain the measurements for three widely differing entrance channels to A1200 CN, reinforcing our earlier conclusion6 that there is no evidence, at the present level of sophistication of the statistical treatment for an inadequacy of the RLDM-NIFG structure predictions at high spin and excitation in this mass range. 1) A . Gavron, Phys. Rev. C 21, 230 (1980). 2) A. Zebelman e t al., Phys. Rev. C 2, 200 (1974). 3) F. Plasil et al., Phys. Rev. Lett. 45, 333 (1980). 4) M. Beckerman and M. Blann, Phys. Rev. C 17, 1615 (1978). 5) M. Blann and T. Komoto, Phys. Rev. C 24, 426 ( 1981). 6) S.E. Vigdor et al., Phys. Rev. C 26, 1035 (1982). 7) M.G. Mustafa et al., Phys. Rev. C 25, 2574 (1982). 8) D.J. Hinde et al., Nucl. Phys. A385, 109 (1982). 9) S.E. Vigdor and H.J. Karwowski, Phys. Rev. C 26, 1068 (1982). 190 MeV PROTON-INDUCED SYMMETRIC AND ASYMMETRIC FISSION* F. D. Becchetti, J. Janecke and P. Lister University of Michigan, Ann Arbor, MI 48109 K. Kwiatkowski, H.J. Karwowski, and S. Zhou Indiana University Cyclotron University, Bloomington, Indiana 47405 A. Nadasen University of Michigan-Dearborn, Dearborn, MI 48128 K. Hicks University of Colorado, Boulder, CO 80309 Proton-induced fission (Ep = 190 MeV) has been Energy signals, and timing signals relative to the studied for uranium and several selected nuclei with A cyclotron r.f. and between detectors were used for between 140 and 210. Fission fragments were detected fragment identification, with energy and relative mass in the 163 cm diameter scattering chamber using spectra calibrated using a thin 252~f fission source. solid-state detectors. Typically a single 300 mm2 Si The time-of-flight resolution of 0.7 to 1.5 ns (FWHM) detector (<loop) was placed on one detector arm was sufficient to separate fission fragments from most (8=90°) about 15 cm from the target. A three-detector of the energetic light ions emitted and provide an array (600 mm2 Si; <lo0 pm) was located about 30 cm approximate mass identification (510 mu) (see Fig. 1). away on an opposing detector arm (8 < -90°), with the The targets consisted of self -supporting rolled target set a t 45' with respect to the incident beam. metal foils, about 500 pg/cm2, or in the case of U, Eu, 155