A search for the Sunyaev-Zel'dovich effect at λ=3 millimeters

Using both drift scan and source tracking observations, we have searched for the Sunyaev-Zel'dovich effect in seven clusters of galaxies at a wavelength of 3 mm using the National Radio Astronomy Observatory 12 m (formerly 11 m) telescope on Kitt Peak and the ATandT Bell Laboratories 7 m telescope at Crawford Hill. This wavelength is advantageous because flux from sources in the clusters is negligible and the Sunyaev-Zel'dovich signal is near maximum amplitude. Our measurements set upper limits on the magnitude of the Sunyaev-Zel'dovich effect that are consistent with all previous, longer wavelength, searches. We introduce a method for comparison of observations that is independent of the details of the measurement and only weakly dependent on the intracluster gas model. The consistency of existing observations and the prospects for future measurements are discussed.