Investigation of a thick Si diode ionization detector at low temperatures for dark matter searches

The sensitivity and charge collection characteristics of a 1-mm-thick commercial Si diode ionization detector for use in a hybrid dark matter detector are described. Particle counting with /sup 57/Co and /sup 241/Am X-ray sources was used to study the variation in sensitive volume and charge collection as a function of temperature and bias. Operating temperatures down to 30 mK were investigated. At this temperature, full volume sensitivity and a near 100% charge collection was observed at 30 mK, with applied biases at low as 5 V.<
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