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Developments Towards a Scaled-Up One-Dimensional Directional Dark Matter Detector

Scarff, Andrew (2017) Developments Towards a Scaled-Up One-Dimensional Directional Dark Matter Detector. PhD thesis, University of Sheffield.

Available under License Creative Commons Attribution-Noncommercial-No Derivative Works 2.0 UK: England & Wales.

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There are many forms of evidence that point towards an unknown form of matter, known as dark matter, making up ∼85% of the mass in the universe. Many dark matter candidates have been proposed with the Weakly Interacting Massive Particle (WIMP) being among the most favoured. There are many groups around the world actively looking for WIMPs with direct, indirect and collider searches with specific interest here in annual modulation and directional searches. The DRIFT-IId detector is the world’s largest directional dark matter detector and is operational in Boulby Mine in the UK. Members of the directional community have come together to form the CYGNUS collaboration, looking towards larger detectors with better directional sensitivity. This thesis looks towards the future scale up to larger directional detectors, specifically low-pressure gas detectors. Improvements have been made to a system used to measure the radon emanation of materials, with emanation tests taken of potential components for CYGNUS detectors. Measurements have also been taken with a small scale THGEM TPC in both CF4 and SF6 gas. The results from CF4 showed the high gas gains achievable from the THGEM detector and allowed a direct measurement of the Townsend coefficients of the gas. Gains of up to 8600 ± 150 have been achieved in low pressure SF6 with a resolution of 19%, both of these figures are the highest achieved to date. The directional sensitivity of 1D readouts has been tested with initial signals of head-tail shown in a THGEM TPC in SF6. A head-tail signature is also seen in a simplified 1D DRIFT-IId readout mode. Exclusion limits from both the full and simplified DRIFT readouts have been produced from over 100 days of background data. The result of 0.16 pb from the full analysis is the lowest limit produced by any directional detector. These results show that a one-dimensional readout may be feasible for directional WIMP detection removing the need for many hundreds or thousands of read out channels required for 3D reconstruction.

Item Type: Thesis (PhD)
Academic Units: The University of Sheffield > Faculty of Science (Sheffield) > Physics and Astronomy (Sheffield)
Identification Number/EthosID: uk.bl.ethos.729484
Depositing User: Andrew Scarff
Date Deposited: 08 Jan 2018 11:30
Last Modified: 12 Oct 2018 09:49
URI: http://etheses.whiterose.ac.uk/id/eprint/18863

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