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 will be equipped with silicon pad sensors, covering a total area of 620m2.
The sensors are processed on novel 8-inch p-type wafers with active thicknesses of 300μm, 200μm, and 120μm 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 (Jozef Stefan Institute, Ljubljana).
A previous annealing study has been performed on silicon diodes from neutron irradiation with fluences from 2e15neq/cm2 to 1.5e16neq/cm2. In a more realistic operational scenario, the detector experience a cumulative increase of fluence during its expected life-time of ten years, with technical stops in-between allowing the silicon sensors to anneal, to finally reach expected fluences up to 1.5e16neq/cm2 and doses up to 1.5 MGy.
In this new study, silicon diodes were irradiated with neutrons in a first round to fluences between 5e14neq/cm2 and 4e15neq/cm2, and subsequently annealed at three different temperatures, 20°C, 40°C, and 60°C, within the expected beneficial annealing window. In the second irradiation step, the same silicon diodes were further irradiated to end-of-lifetime fluences between 2e15neq/cm2 and 1.5e16neq/cm2, now consistent with the previous annealing studies. In this talk, the electrical characterisation and charge collection measurements from both irradiation rounds will be presented and compared with results from the full fluence annealing study.
| Type of presentation (in-person/online) | in-person presentation |
|---|---|
| Type of presentation (I. scientific results or II. project proposal) | I. Presentation on scientific results |
