# VCI2019 - The 15th Vienna Conference on Instrumentation

18-22 February 2019
Vienna University of Technology
Europe/Vienna timezone

## Deep Diffused Avalanche Photodiodes for Charged Particle Timing

19 Feb 2019, 14:25
20m
EI7 ()

### EI7

Talk Semiconductor Detectors

### Speaker

Matteo Centis Vignali (CERN)

### Description

The upgrades ATLAS and CMS for the High Luminosity LHC (HL-LHC) highlighted physics objects timing as a tool to resolve primary interactions within a bunch crossing. Since the expected pile-up is around 200, with an rms time spread of 170ps, a time resolution of about 30ps is needed. The timing detectors will experience a 1-MeV neutron equivalent fluence of $\Phi_{eq}=10^{14}$ and $10^{15}$cm$^{-2}$ for the barrel and end-cap regions, respectively.
In this contribution, deep diffused Avalanche Photo Diodes (APDs) produced by Radiation Monitoring Devices are examined as candidate timing detectors for HL-LHC applications. To improve the detector's timing performance, the APDs are used to directly detect the traversing particles, without a radiator medium where light is produced.
Devices with an active area of $8\times8$mm$^2$ were characterized in beam tests. Two readout schemes were investigated: 1) a direct coupling to the APD with off-sensor capacitive coupling and 2) a capacitive coupling on the sensor realized by means of a metallic mesh isolated from the detector by a kapton layer. The timing performance and signal properties were measured as a function of position on the detector using a beam telescope and an MCP.
Devices with an active area of $2\times2$mm$^2$ were used to determine the effects of radiation damage on current, signal amplitude, noise, and timing using a ps pulsed laser. These detectors were irradiated with neutrons up to $\Phi_{eq}=10^{15}$cm$^{-2}$.

### Primary authors

Matteo Centis Vignali (CERN) Michele Gallinaro (LIP Lisbon) Mr Mickel McClish (Radiation Monitoring Devices Inc.) Kirk McDonald (Princeton University) Michael Moll (CERN) Mitchell Franck Newcomer (University of Pennsylvania (US)) Sofia Otero Ugobono (CERN/Universidade de Santiago de Compostela (ES)) Dr Sebastian White (University of Virginia (US))