Fast timing silicon detectors for new scientific frontiers

Supervisor: Dr Dima Maneuski

School: Physics and Astronomy 


Silicon sensors are essential in a range of fields, from cutting-edge research (materials science, particle physics, chemistry) to industry (agriculture, manufacturing), and everyday devices (cameras, security). They are the eyes of our electronic world. As scientists developmore precise sensors, for example cameras with smaller pixels, the potential reach of these devices increases, allowing more processes to be investigated, and with more detail. Currently the resolution of such sensors is at the micrometre level. However, the time precision is relatively much worse, due to significant technological challenges in assigning times to the signals in the silicon. The best precision for small-pixel silicon sensors is at the nanosecond (ns) level. By comparison, light travels 300,000 micrometresper ns. Our ability to observe many processes is significantly hampered by limitations in time precision.

LGADis a new type of the Avalanche Silicon Detector concept with a gain in the region of 5-10. The lower gain increases signal to noise ratio in comparison with a planar silicon detector and have reduced noise compared to an avalanche photodiode. The LGADs can be highly segmented and assembled into hybrid pixel detectors.

This research project aims to characterise, for the first time small-pitch pad and pixelated silicon Low Gain Avalanche Detectors (LGAD) allowingsimultaneous precise measurements of particle position (within 15μm) and time (within 50ps). Such sensors will ultimately open-up new fields of research and have broad applications in fundamental research (electron microscopy), applied science & industry (functionalmaterials), and in the healthcaresector (proton therapy).

In this work it is proposed to characterise secondgeneration ofLGAD devices recently produced by our UK industrial partner, Micron Semiconductor Ltd. The work will concern pad and pixelated devices.Basic characterisation of these devices by means of current-voltage characteristics is essential. This gives basic understandingof samples’ quality and their suitability for in-depth studies.Existing Transient Current Technique (TCT) setup will be employed to study effective gain of the devices. It is essential to study these devices at various bias voltagesand temperatures as gain strongly depends onthese.And finally, our bespoke X-ray system will be used to study the response of the devices to x-rays in preparation for experiments at Diamond Light SourceSynchrotron. 

Essential criteria

Background in Particle or Nuclear Physics or Engineering

Basic knowledge of electronics

Basic lab skills

Basic presentation skills

Basic Python / c++ / git

Strong ability to work in a team