Monte Carlo computation of pair correlations in excited nuclei

We present a novel quantum Monte Carlo method based on a path integral in Fock space, which allows one to compute finite-temperature properties of a many-body nuclear system with a monopole pairing interaction in the canonical ensemble. It enables an exact calculation of the thermodynamic variables such as the internal energy, the entropy, or the specific heat, from the measured moments of the number of hops in a path of nuclear configurations. Monte Carlo calculations for a single-shell ({ital h}{sub 11/2}){sup 6} model are consistent with an exact calculation from the many-body spectrum in the seniority model. {copyright} {ital 1996 The American Physical Society.}