Introduction

Small Array

Large Array

The Arcminute Microkelvin Imager (AMI) is a twin-array radio telescope (spanning 13.5–18 GHz) operated by the Astrophysics group at the Cavendish Laboratory. AMI is designed to find and image very faint cm-wave structures on scales 30''–10'; its sensitivity (3 mJy s^-1/2 Large Array, 30 mJy s^-1/2 Small Array) and field-of-view give it a very fast surveying speed. AMI is sited at the Mullard Radio Astronomy Observatory near Cambridge, UK.

The principal aims behind AMI are:

• to carry out a blind survey for clusters of galaxies using the Sunyaev-Zel'dovich (SZ) effect, with the key advantages of the SZ's independence of cluster redshift and its independence of cluster gas distribution;
• to image these clusters in detail;
• to search for topological defects and for the first ionized structures;
• and to follow up, at higher angular resolution, non-primordial features found by the Planck satellite.

The AMI design is interferometric, partly for the now well-proven advantages of low systematics and of reaching design sensitivity. AMI consists of two arrays, both operating over the frequency range 13.5–18 GHz.

• The Small Array (SA) consists of ten 3.7-m paraboloidal antennas situated inside a 30-m x 40-m, 4.5-m high metal enclosure; the antennas have rimmed primaries and shaped secondaries to minimize crosstalk and groundspill, and both the HEMT amplifiers and their entire feedhorns are cryogenically cooled.
• The Large Array (LA) consists of the eight existing 13-m diameter antennas of the Ryle Telescope in a new 2-dimensional array with baselines up to 100 m, with their receivers upgraded.

This dual array design gives AMI very good temperature sensitivity over a large range of angular scales, as well as the high flux sensitivity needed to identify and remove the effect of radio sources from the data.

Find out more about AMI using the links to the left.