Ultra-Fast Silicon Detectors for 4D tracking applications in high energy physics and medical applications

Betreuer: Thomas Bergauer
Fachbereich: Detektorentwicklung
Projekt: CMS Tracker

Ultra-Fast Silicon Detectors based on LGAD (Low Gain Avalanche Detectors) are of high interest for tracking applications at future collider experiments in high energy particle physics.  This technology is based on silicon pixel detectors with internal amplification that allows to achieve time resolutions of better than 30 ps. This allows to record both the spatial and the timing of traversing particles, hence 4D.

Today, LGADs are used to build so-called timing layers and add a single, high precision timestamp to a track. For true 4D tracking, a timestamp at each tracking plane is required. In present designs, a roughly 100 µm wide dead area at the pixel periphery is limiting the minimum pixel size and thus the application for true 4D tracking.  The scope of the thesis will be to investigate new pixel structures to reduce the dead area. This will be achieved by means of experiment and simulation. On the simulation side, the interplay between finite element and Monte Carlo simulations will be a key element to get a faster turnaround on new ideas. 


  • Finite element simulations with Synopsys TCAD simulation framework to obtain detailed information on the electrical behavior of new pixel structures. 
  • Monte Carlo simulations with the Allpix Squared framework to obtain results on time resolution and radiation hardness of the same structures.
  • Characterization of silicon detectors by means of a wide range of electrical measurements in the clean room.
  • Characterization of prototype LGAD devices with radioactive sources, laser and particle beams at MedAustron. 
  • Comparison and verification of simulation results with experiment. 

Required skill set:

  • Interest in radiation detection, electronics and computing.
  • Some experience with Linux-based operating systems.
  • Some programming experience. Experience in C++ is welcome but not required. 
  • More important than a specific skill is a general willingness to learn new ones. The extend and focus of the work can be adapted to the student, with the focus on either hardware or software.

If you are interested or in case of further questions contact: 
Dr. Thomas Bergauer (Email:
Group leader for Detector Development