Intrinsic time resolution of 3D-trench silicon pixels for charged particle detection

L Anderlini,R Mulargia,M Boscardin,E Robutti,A Loi,A Bizzeti,M Ferrero,R Mendicino,M Garau,M Ruspa,A Cardini,S Ronchin,A Lai,C Lucarelli ,Mauro Aresti ,G.-F Dalla Betta,G T Forcolin ,Andrea Lampis ,M M Obertino ,S Vecchi

doi:10.1088/1748-0221/15/09/p09029

Abstract

In the last years, high-resolution time tagging has emerged as a promising tool to tackle the problem of high-track density in the detectors of the next generation of experiments at particle colliders. Time resolutions below 50 ps and event average repetition rates of tens of MHz on sensor pixels having a pitch of 50 μm are typical minimum requirements. This poses an important scientific and technological challenge on the development of particle sensors and processing electronics. The TIMESPOT initiative (which stands for TIME and SPace real-time Operating Tracker) aims at the development of a full prototype detection system suitable for the particle trackers of the next-to-come particle physics experiments. This paper describes the results obtained on the first batch of TIMESPOT silicon sensors, based on a novel 3D MEMS (micro electro-mechanical systems) design. We demonstrate that following this approach, the performance of other ongoing silicon sensor developments can be matched and overcome. In addition, 3D technology has already been proved to be robust against radiation damage. A time resolution of the order of 20 ps has been measured at room temperature suggesting also possible improvements after further optimisations of the front-end electronics processing stage.

Highlights

IntroductionHigh signal-to-noise ratio, speed and spatial response uniformity are key ingredients to be considered when designing a high-resolution timing detector
We demonstrate that following this approach, the performance of other ongoing silicon sensor developments can be matched and overcome
A time resolution of the order of 20 ps has been measured at room temperature suggesting possible improvements after further optimisations of the front-end electronics processing stage

Summary

Introduction

High signal-to-noise ratio, speed and spatial response uniformity are key ingredients to be considered when designing a high-resolution timing detector To meet these requirements, thin silicon sensors with a gain layer have been recently introduced. Ultra Fast Silicon Detectors (UFSD), based on Low Gain Avalanche Diode (LGAD) technology, presently achieve 30 ps resolution up to fluences of 1−2×1015 neq/cm2 [8] Such devices are currently the baseline for the forward part of the ATLAS and CMS timing layers at HL-LHC [4, 5]. The sensors are characterised by cylindrical electrodes penetrating deep into the bulk material, perpendicularly to the surface This unique structure, which decouples the charge carrier drift distance from the sensor thickness, exhibits very good radiation hardness, probed up to fluence of 3 × 1016 neq/cm2 [12]. The fact that the charge carriers are collected perpendicularly to the sensor thickness minimises time uncertainties due to nonuniform ionisation density (delta rays) and charge carriers diffusion

Methods

Results

Conclusion