Radiation Hardness Studies in a CCD with High-Speed Column Parallel Readout

TL;DR

This paper investigates the radiation hardness and charge transfer inefficiency of high-speed column-parallel CCDs for particle physics, analyzing effects of radiation damage, temperature, and readout speed through simulations.

Contribution

It provides detailed simulation results on CTI in CPCCDs, including effects of radiation damage and optimal operating conditions for high-speed readout.

Findings

Optimal temperature for minimal charge trapping is about 230 K.

Radiation damage significantly affects CTI depending on trap levels.

Higher readout speeds influence charge transfer efficiency.

Abstract

Charge Coupled Devices (CCDs) have been successfully used in several high energy physics experiments over the past two decades. Their high spatial resolution and thin sensitive layers make them an excellent tool for studying short-lived particles. The Linear Collider Flavour Identification (LCFI) collaboration is developing Column-Parallel CCDs (CPCCDs) for the vertex detector of the International Linear Collider (ILC). The CPCCDs can be read out many times faster than standard CCDs, significantly increasing their operating speed. The results of detailed simulations of the charge transfer inefficiency (CTI) of a prototype CPCCD are reported and studies of the influence of gate voltage on the CTI described. The effects of bulk radiation damage on the CTI of a CPCCD are studied by simulating the effects of two electron trap levels, 0.17 and 0.44 eV, at different concentrations and operating temperatures. The dependence of the CTI on different occupancy levels (percentage of hit pixels) and readout frequencies is also studied. The optimal operating temperature for the CPCCD, where the effects of the charge trapping are at a minimum, is found to be about 230 K for the range of readout speeds proposed for the ILC. The results of the full simulation have been compared with a simple analytic model.