The neutron capture cross section and f i s s i o n cross section far 2 3 3 ~ have been measured simultaneously in the neutron energy range from 0.4 t o 1000 eV. The data a r e presented i n graphical, tabular, and i n t e g r a l farm. Cornpaxisons w i t h previously published data, using similar and different methods, are given, *Work sponsored by the U, 5. Atomic Energy Commission under contracts w i t h Oa& Ri'dge National Labosatoq ( W-"/o? -eng-26) and Rensselaer Polytechnic Ins.titute [.AT( 30-3) -328 1, *Dep&rtment of' Nuclear Engineering and Science, Rensselaer Polytechnic I n s t i k t e . +Presen.t address: Los AIwos S c i e n t i f i c Laboratory.NOTICE This rlnrtfimertt rmtoin(i infmnntim atid was p r p p d primarily far internal use ot Laboratory. Ir i s subjec? tc revision or corre not tqxesent a final report. preliminary noturn Oak Ridge lrlotionul end therefare does DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government.

No abstract

The neutron f i s s i o n and capture cross sections f o r 2 3 5~ have been measured simultaneously f o r incident neutron energies from 0.4 eV t o 3 keV. I n addition, t h e f i s s i o n cross section has been measured up t o a neutron energy of 20 keV.

This report was prepared as an account of work sponsored by the United States Government. ?jeither the United States nor the United States Atomic Energy Commission, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, oi-assumes any legal liability or responsibility for the accuracy, com-pietRness or usefulness of any information, apparatus, product or process disclosed, or represents that its use wouid not infringe privately owned rights.

A 20-cc lithium-drifted germanium detector has been used in conjunction with the R.P.I. Electron Linac Neutron Velocity Selector to examine the high-energy gamma-ray spectra arising from thermal and resonance neutron capture in mercury, and from resonance capture in tungsten. The effective gamma-ray energy resolution of 12-18 keV allowed 29 transitions to be examined in the energy range 4.67 to 8.02 MeV following capture of thermal neutrons and resonance neutrons of energy 34, 130, and 175 eV in 199 Hg (116 transitions in all). The spectra are interpreted in terms of levels in the compound nucleus 200 Hg. An analysis of the strengths of 88 El transitions indicates a Porter-Thomas distribution, the best fit being achieved-with a X 2 function with 0.96_o.i7 +0-24 degrees of freedom. The mean reduced partial radiation width for transitions to states in 200 Hg above the pairing energy gap is shown to be significantly higher than the corresponding mean width for transitions to collective states below the pairing energy. No such effect is obvious in the case of resonance capture in 183 W. A comparison between resonance capture in 198 Hg and 182 W, where no pairing energy gap exists, shows that the mean partial radiation width is a factor 4 larger for 198 Hg than for the highly distorted 182 W.