Ranjeet Dalal

Combined effect of bulk and surface damage on strip insulation properties of proton irradiated n+-p silicon strip sensors

Silicon sensors in next generation hadron colliders will face a tremendously harsh radiation environment. Requirement to study rarest reaction channels with statistical constraints has resulted in a huge increment in radiation flux, resulting in both surface damage and bulk damage. For sensors which are used in a charged hadron environment, both of these degrading processes take place simultaneously. Recently it has been observed in proton irradiated n+-p Si strip sensors that n+ strips had a good inter-strip insulation with low values of p-spray and p-stop doping densities which is contrary to the expected behaviour from the current understanding of radiation damage. In this work a simulation model has been devised incorporating radiation damage to understand and provide a possible explanation to the observed behaviour of irradiated sensors.

A method to simulate the observed surface properties of proton irradiated silicon strip sensors

During the scheduled high luminosity upgrade of LHC, the worlds largest particle physics accelerator at CERN, the position sensitive silicon detectors installed in the vertex and tracking part of the CMS experiment will face more intense radiation environment than the present system was designed for. To upgrade the tracker to required performance level, extensive measurements and simulations studies have already been carried out. A defect model of Synopsys Sentaurus TCAD simulation package for the bulk properties of proton irradiated devices has been producing simulations closely matching with measurements of silicon strip detectors. However, the model does not provide expected behavior due to the fluence increased surface damage. The solution requires an approach that does not affect the accurate bulk properties produced by the proton model, but only adds to it the required radiation induced properties close to the surface. These include the observed position dependency of the strip detectors charge collection efficiency (CCE). In this paper a procedure to find a defect model that reproduces the correct CCE loss, along with other surface properties of a strip detector up to a fluence

Simulations of Inter-Strip Capacitance and Resistance for the Design of the CMS Tracker Upgrade

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Study of Trapping Probability in Proton Irradiated Silicon Pad Detectors Using Transient Current Technique Simulations

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Dependence of charge multiplication on different design parameters of LGAD devices

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TCAD simulation of Low Gain Avalanche Detectors

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Design optimization of pixel sensors using device simulations for the phase-II CMS tracker upgrade

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Design, fabrication and characterization of multi-guard-ring furnished p+n−n+ silicon strip detectors for future HEP experiments

, will be presented. When applied with CCE loss measurements at different fluences, this method may provide means for the parametrization of the accumulation of oxide charge at the SiO2/Si interface as a function of dose.

Development of AC-coupled, poly-silicon biased, p-on-n silicon strip detectors in India for HEP experiments

An upgrade of the LHC accelerator, the high luminosity phase of the LHC (HL-LHC), is foreseen for 2023. The tracking system of the CMS experiment at the HL-LHC will face a more intense radiation environment than the present system was designed for. This requires an upgrade of the full tracker, which will be equipped with higher granularity as well as radiation harder sensors, which can withstand higher radiation levels and occupancies. In order to address the problems caused by the intense radiation environment, extensive measurements and simulation studies have been initiated for investigating these different design and material options for silicon micro-strip sensors. The simulation studies are based on commercial packages (Silvaco and Synopsys TCAD) and aim to investigate sensor characteristics before and after irradiation for fluences up to 1.5 ·1015 neq/cm. A defect model was developed to implement the radiation damage and tuned to fit experimental measurements. This paper covers the simulation of the inter-strip capacitance and resistance both before and after irradiation. Both properties are crucial for the design of future sensors, being responsible for strip noise and isolation, in turn affecting resolution. A detailed understanding of these parameters is required for an optimal sensor design for the future CMS tracker. Technology and Instrumentation in Particle Physics 2014, 2-6 June, 2014 Amsterdam, the Netherlands

Characterization of irradiated APDs for picosecond time measurements

As the rate of the incoming fluence increases, the density of the traps also increases in the silicon bulk. This leads to a decrease in the charge collected limiting the long term operation of the silicon detectors. In the work presented here, we have calculated the effective trapping probability in a proton irradiated silicon pad detector using transient current simulations and ROOT software.