Compound-nuclear tests of time reversal invariance in the nucleon-nucleon interaction

The theory for the effects of time-reversal noninvariance (TRNI) in complex systems is reviewed. Applied to the compound-nuclear data for energy-level, width and cross-section fluctuations (the latter for detailed-balance pairs of reactions proceeding through the compound nucleus) this gives bounds on multiparticle TRNI Hamiltonian matrix elements. Using a fluctuation-free form of statistical spectroscopy the results are reduced to bounds on α, the relative magnitude of the TRNI nucleon-nucleon interaction. The level and width analyses for heavy nuclei gave α ≤ 2 x 10-3 at high (∼99%) statistical confidence; preliminary calculations for detailed balance with 24Mg(α,p)27Al and its inverse gives α ≤ 4 x 10-3 at the same high confidence, but ≤0.2 x 10-3 at 80% confidence. Suggestions are made about experiments which should yield sharper bounds. 28 refs., 1 tab