New limit on the rate-density of evaporating black holes.

摘要

Data taken with the CYGNUS detector between 1989 and 1993 have been used to search for 1 second bursts of ultra-high energy (UHE) gamma rays from any point in the northern sky. There is no evidence for such bursts. Therefore the theory-dependent upper limit on the rate-density of evaporating black holes is 6.1 (times) 10(sup 5)pc(sup (minus)3)yr(sup (minus)1) at the 99% C.L.. After renormalizing previous direct searches to the same theory, this limit is the most restrictive by more than 2 orders of magnitude.