Oxford Experimental Radio/mm Cosmology

GUBBINS - 200-GHz Ultra-BroadBand INterferometer for SZ

GUBBINS is a novel heterodyne interferometer currently under construction in Oxford that will both measure the spectrum of Sunyaev-Zel'dovich effect in the brightest galaxy clusters and provide a test-bed for future developments from our new-technology program.

The instrument employs new techniques in heterodyne interferometry, with the aim of achieving high brightness sensitivity in the millimetre band. It is a single baseline tracking interferometer operating in the frequency range 185-275 GHz. It has two 0.4m offset parabolic antennas separated by a 0.5m baseline. Each antenna feeds an SIS mixer with 2-20GHz IF band, driven by a phase-switched LO source. The IF signals from the mixers are processed by a 2-20GHz analogue complex correlator.

The primary science goal of GUBBINS is to measure the spectrum of the SZ effect in galaxy clusters. In particular we intend to measure the frequency of the SZ null near 217GHz which allows the temperature of the cluster to be determined. However, the technology developed for this instrument will also have applications in other areas of astronomy, particularly in the design of very wide bandwidth SIS receiver arrays, and in high dynamic range interferometry.

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