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Tests of finline-coupled TES bolometers for ClOVER

Audley, M. D., Glowacka, D. M., Goldie, D. J., Lasenby, A. N., Tsaneva, V. N., Withington, S., Grimes, P. K., North, Christopher E., Yassin, G., Piccirillo, L., Pisano, G., Ade, Peter A. R., Teleberg, Gustav, Irwin, K. D., Duncan, W. D., Reintsema, C. D., Halpern, M. and Battistelli, E. S. 2007. Tests of finline-coupled TES bolometers for ClOVER. Presented at: Joint 32nd International Conference on Infrared and Millimeter Waves, 2007 and the 2007 15th International Conference on Terahertz Electronics. IRMMW-THz., Cardiff, UK, 2-9 September 2007. Published in: Griffin, Matthew Joseph and Parker, T. eds. Joint 32nd International Conference on Infrared and Millimeter Waves, 2007 and the 2007 15th International Conference on Terahertz Electronics. IRMMW-THz. Los Alamitos, CA: IEEE, pp. 180-181.

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Abstract

CLOVER aims to detect the signature of gravitational waves from inflation by measuring the B-mode polarization of the cosmic microwave background. CLOVER consists of two polarimeters. One operates at 97 GHz, using finline-coupled Transition Edge Sensors (TES). The other has a combined 150/220-GHz focal plane populated by radial-probe coupled TES detectors. The 97-GHz instrument will have 100 feedhorns and 200 detectors while the combined 150 and 220-GHz instrument will have a total of 200 horns. To achieve the target NEP of 1.5×10−17 W Hz−1 the 97-GHz detectors will have a transition temperature of 190 mK and will operate with a base temperature of � 100 mK. CLOVER’s detectors are fabricated on 225-micron silicon substrates. In the 97-GHz instrument a finline transition feeds a microstrip which is terminated by a matched resistor on the silicon nitride island that carries the TES. Each detector is fabricated as a single chip to ensure a 100% operational focal plane. The detectors are mounted in linear modules made of copper which form split-block waveguides. Each detector module contains a time-division SQUID multiplexer to read out the detectors. The multiplexed signals are further amplified by SQUID series arrays. The first prototype detectors for CLOVER have a transition temperature of 350 mK and were fabricated to validate the detector design and the polarimeter technology. We have characterised these detectors in a dedicated test facility. The CLOVER testbed contains cryogenics similar to those in the final instrument: a pulse-tube cooler, He-7 sorption fridge, and a mini dilution fridge so that the detectors are tested in a realistic environment. The test bed has a cryogenic blackbody source with band-defining filters for optical testing. As well as the multi-channel electronics that will be used on the final instrument the test bed has an analogue SQUID readout which allows us to characterise the readout fully. We discuss the results of the detector tests and the design changes needed to achieve the required sensitivity.

Item Type: Conference or Workshop Item (Paper)
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Publisher: IEEE
ISBN: 9781424414383
Last Modified: 20 Oct 2017 09:05
URI: http://orca.cf.ac.uk/id/eprint/22410

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