Speaker
Description
To face the higher levels of radiation due to the 10-fold increase in integrated luminosity during the High Luminosity LHC, the CMS detector will replace the current endcap calorimeters (CE) with the new High Granularity Calorimeter (HGCAL). It will facilitate the use of particle flow calorimetry with its unprecedented transverse and longitudinal readout and trigger segmentation, with more than 6M readout channels. The electromagnetic section as well as the high-radiation regions of the hadronic section of the HGCAL (fluences above $10^{14} n_{eq}/cm^2$) will be equipped with silicon pad sensors, covering a total area of $620 m^2$). Fluences up to 1.5e16 $n_{eq}/cm^2$ and doses up to 1.5 MGy are expected.
The sensors are processed on novel 8-inch p-type wafers with active thicknesses of 300$~\mu$m, 200$~\mu$m and 120$~\mu$m and cut into hexagonal shapes for optimal use of the wafer area and tiling. With each main sensor several small sized test structures are hosted on the wafers, used for quality assurance and radiation hardness tests. In order to investigate the radiation-induced bulk damage, the diode test structures of these sensors have been irradiated with neutrons at JSI (Jožef Stefan Institute, Ljubljana) to fluences between 2e15 $n_{eq}/cm^2$ and 1.5e16 $n_{eq}/cm^2$ .
In this talk, the electrical characterisation and charge collection measurements of the irradiated silicon diodes will be presented. The study focuses on the isothermal annealing behaviour of the bulk material at temperatures of 6.5°C, 20°C, 30°C, 40°C and 60°C in order to extract the temperature dependent annealing time constants that allow scaling to temperatures such as the 0°C foreseen as shutdown temperature of the CE.
| Type of presentation (in-person/online) | in-person presentation |
|---|---|
| Type of presentation (I. scientific results or II. project proposal) | I. Presentation on scientific results |
