A High Power Liquid Hydrogen Target for Parity Violation Experiments

Parity-violating electron scattering measurements on hydrogen and deuterium, such as those underway at the Bates and CEBAF laboratories, require luminosities exceeding 10{sup 38} cm{sup -2} s{sup -1}, resulting in large beam power deposition into cryogenic liquid. Such targets must be able to absorb 500 watts or more with minimal change in target density. A 40 cm long liquid hydrogen target, designed to absorb 500 watts of beam power without boiling, has been developed for the SAMPLE experiment at Bates. In recent tests with 40 {micro}A of incident beam, no evidence was seen for density fluctuations in the target, at a sensitivity level of better than 1%. A summary of the target design and operational experience will be presented.