Characterisation of low gain avalanche detectors for large area precision timing at particle colliders

Mulvey, Jonathan ORCID: 0009-0004-5237-7990 (2025). Characterisation of low gain avalanche detectors for large area precision timing at particle colliders. University of Birmingham. Ph.D.

Preview

Mulvey2025PhD.pdf
Text - Accepted Version
Available under License Creative Commons Public Domain Dedication.
Download (21MB) | Preview

Abstract

Low Gain Avalanche Detectors (LGADs) are the chosen technology for the timing layers which are to be placed in the forward region of the inner trackers in the ATLAS and CMS experiments. Teledyne e2v (Te2v) is a silicon foundry known for producing large volume CCDs. This work aims to establish them as a future vendor of LGADs, particularly for High Energy Physics applications. Experimental set-ups and techniques have been successfully developed and refined in order to characterise the IV, CV, gain and timing properties of LGADs. Characterisation has been completed before and after irradiation with 27 MeV protons at the MC40 cyclotron in Birmingham. These results are reported here with key values compared to LGADs from alternative vendors. Te2v’s LGADs achieve sub-40 ps time resolution at a gain of ∼20 or above. The time resolution also behaves similarly as a function of gain compared to other vendors. After irradiation, they can still achieve this time resolution below a fluence of 5.7 × 1014 1 MeV neq/cm2. At this fluence and above, the timing performance is limited to 50 ps at a gain of ∼10. Gain non-uniformity across similar devices was observed in IV and gain measurements. The acceptor removal coefficient was measured to be (9.7 ± 0.5) × 10−16 cm2, 45 % larger than reported for Fondazione Bruno Kessler’s (FBK) UFSD2 production where it is 6.7 × 10−16 cm2. Overall, this work has demonstrated that Te2v is capable of manufacturing LGADs with comparable performance to existing vendors. With further refinement of the gain layer implant energy and dose, Te2v would be a highly competitive supplier with potential for meeting the large orders anticipated for many future particle physics facilities.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):