Cryodetector readout for direct dark matter searches

Thesis

The next generation of cryodetector arrays for direct WIMP searches will aim to achieve large increases in WIMP-nucleon scattering target mass, an order of magnitude or more greater than existing detector arrays. The implementation of high-resolution measurements and background suppression by event discrimination will remain of paramount importance. Hardware development must be undertaken to increase the availability and density of readout channels while maintaining low-noise, low-heatload, high-radiopurity cryodetector performance. This thesis describes the development of scalable cryogenic cabling using etched metal foil fabrication techniques and the development of low-temperature high-voltage power supply for scintillation light readout using photomultiplier tubes.

Etched metal foil cables were developed for cryodetector readout. Fabrication techniques for low-heatload, low-cost cabling were developed and commissioning tests were carried out to verify low-noise performance in both low-impedance and high-impedance cryodetector readout schemes. SQUID readout cabling with a heatload cost 24 times lower than existing cabling was installed and mean SQUID noise of 5.5 pAHz^-1/2 was measured with low-impedance input.

Photomultiplier tubes can be used for cryogenic scintillation light measurement, a key technique in cryodetector event discrimination. A low-heatload, low-noise photomultiplier tube power supply circuit was developed. Measurements of cryogenic scintillation light from a CaWO4 crystal were carried out using a CWG/PMT module cooled to 0.95 mK.

Authors: Ingleby, S

• Publication date: 2012
• DOI: 10.5287/ora-x59862znm
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: cryogenic detector; particle physics; dark matter; SQUID sensor; cryogenic pmt; particle physics experiment; particle physics hardware
• Subjects: Particle physics