Physics & Astronomy ETDs

Publication Date

Fall 12-2016


Dark matter is believed to comprise over 80% of the matter in the Universe. Its composition could be in the form of weakly interacting massive particles (WIMPs), which are predicted by extensions of the Standard Model, namely supersymmetric theories. Even though hints of its existence were detected in astronomical observations over eighty years ago, its detection through means other than the gravitational influence on observable luminous matter still eludes us.

Currently, there are many ongoing direct detection experiments, that aim to measure the signals left by the elastic scattering of WIMPs with nuclei in the detector target material. The detection and identification of dark matter is made difficult, however, by the small interaction cross-section with ordinary matter and the large parameter space that it could inhabit. As such large detectors are needed to probe this parameter space, but potential detections can appear ambiguous in origin due to the presence of backgrounds and a lack of a strong fingerprint in the energy spectrum of detected events. Fortunately, there are two signatures that could point to the Galactic origin of the signal. These are the annual modulation and directional signatures, but of the two, the latter can provide the strongest evidence.

This thesis discusses the many challenges of directional detection utilizing the low pressure time projection chamber (TPC) technology and describes the experimental efforts to overcome them. A study of low-energy recoils to explore the achievable discrimination threshold and directional sensitivity in a real detector is described. Next, I discuss progress towards a path for detector scale-up while retaining sensitivity by employing a newly identified electronegative TPC gas. The development of a novel readout technology for large detectors is discussed. Finally, the last chapter is devoted to a new idea on a method to detect directionality in a high pressure detector.

Degree Name


Level of Degree


Department Name

Physics & Astronomy

First Committee Member (Chair)

Dinesh Loomba

Second Committee Member

John Matthews

Third Committee Member

Michael Gold

Fourth Committee Member

James Battat




dark matter, directionality, time projection chamber, low energy recoils, CCD, electronegative gases

Document Type