Speaker
Timo Hannu Tapani Peltola
(Helsinki Institute of Physics (FI))
Description
Position sensitive silicon detectors are largely employed in the tracking systems of High Energy
Physics experiments due to their outstanding performance. They are currently installed in the
vertex and tracking part of the ALICE, ATLAS, CMS and LHCb experiments at LHC, the world’s
largest particle physics accelerator at Centre for European Nuclear Research (CERN), Geneva.
An upgrade of LHC accelerator is already planned, namely the high luminosity (HL) phase of
the LHC (HL-LHC foreseen for 2023). This will enable the use of maximal physics potential of
the machine. At the high integrated luminosity of 3000 fb$^{-1}$ the tracking system at HL-LHC will
face more intense radiation environment than the present system was designed for. This requires
the upgrade of the all-silicon central trackers that will be equipped with higher granularity as well
as radiation hard sensors, which can withstand higher radiation levels and higher occupancies also
in the innermost layers closest to the interaction point. In order to address the problems caused
by intense radiation environment, extensive measurements and simulations studies requirements
have been initiated within the RD50 Collaboration, with an open cooperation across experimental
boundaries, for investigating different designs and materials options for silicon sensors with
sufficient radiation tolerance. Research topics include studies of sensors with n-electrode readout
(mainly sensors with p-bulk), which offer the advantage of collecting electrons instead of holes
resulting in an improvement of radiation tolerance. Also a further enhancement of performance is
investigated in thinned bulk sensors (reduced trapping probability) and in active edge technology
(maximized sensitive area). Another line of activity is the development of advanced sensor types
like 3D detectors and Low Gain Amplification Detectors (LGAD) designed for the extreme radiation
environment at the inner layers. TCAD simulations of silicon strip sensors have expanded to
cover both bulk and surface properties after irradiation at HL-LHC levels, producing results that
are converging with measurements.
Summary
Our results from both measurements and simulations of several detector technologies and silicon
materials at radiation levels expected for HL-LHC will be presented. Based on our results, latest
developments in finding the most suitable silicon detectors to be used for LHC detector upgrades
will be reported.
Author
Timo Hannu Tapani Peltola
(Helsinki Institute of Physics (FI))
