Anna Rita Altamura

Anna Rita Altamura

Ph.D XXXIV

Supervisor: Alberto Gola

altamura.annarita@spes.uniud.it

Research Project

The Silicon Photon Multiplier (SiPM) and the Low Gain Avalanche Detector (LGAD) are devices that exploit impact ionization in silicon to create an internal charge multiplication mechanism, which allows achieving excellent performance in terms of sensitivity and time resolution. Among other applications, such detectors are currently at the heart of several development for next-generation big science experiments.

In particular, SiPM are single-photon detectors, operated above breakdown and working in Geiger mode. They provide sensitivity down to the single photon and maximum single photon time resolution down to 20 ps. They are often employed for the readout of scintillation light, in several applications, such as medical imaging (e.g. Time of Flight PET). For what concerns the scientific experiments, they are currently being evaluated for the scintillator readout in the Barrel Timing Layer (BTL) of the CMS experiment, in the framework of the Phase-2 upgrade for the High-Luminosity LHC.

On the other hand, LGADs are operated in proportional multiplication regime, with a tunable gain value which is usually in the order of 5-20, depending on the specific detector technology and the operative conditions. The advantages of such approach are a faster timing response and a higher signal intensity. Among other applications, timing-optimized LGADs (usually referred to as Ultra-Fast Silicon Detectors, UFSD) are currently the detectors of choice for the Endcap Timing Layer of CMS, since they demonstrated the capability to achieve the required timing resolution (30 ps) and to withstand the radiation dose expected during the HL-LHC lifetime (> 1015 Neq).

FBK is currently at the forefront of developments of both SiPMs and LGAD detectors. Strong irradiation is expected for both detectors. Thus, significant R&D effort will be dedicated to their characterization and optimization in this regard.

Project goals

  • Characterization and optimization of the SiPM and LGAD technologies for radiation hardness, in collaboration with scientific partners in the relevant projects and using external irradiation facilities, which FBK has access to.
  • Development of a prototype of detecting modules for BTL.
  • Characterization of the timing performance of SiPMs in the readout of scintillation crystals as required for BTL detecting modules.
  • Characterization of the overall performance of new LGAD technologies developed by FBK to improve the sensor detection efficiency.