Electrical Properties of Carbon Fiber Support Systems

TL;DR

This paper examines the electrical properties of carbon fiber support structures in high energy physics detectors, highlighting their conductive behavior at high frequencies and proposing grounding solutions for optimal detector performance.

Contribution

It provides experimental data and analysis on the conductivity of carbon fiber at high frequencies and discusses effective grounding configurations for silicon detectors using carbon fiber supports.

Findings

Carbon fiber acts as a conductor at 10-100 MHz.

A copper-kapton mesh grounding scheme ensures robust detector performance.

Experimental measurements validate the proposed grounding approach.

Abstract

Carbon fiber support structures have become common elements of detector designs for high energy physics experiments. Carbon fiber has many mechanical advantages but it is also characterized by high conductivity, particularly at high frequency, with associated design issues. This paper discusses the elements required for sound electrical performance of silicon detectors employing carbon fiber support elements. Tests on carbon fiber structures are presented indicating that carbon fiber must be regarded as a conductor for the frequency region of 10 to 100 MHz. The general principles of grounding configurations involving carbon fiber structures will be discussed. To illustrate the design requirements, measurements performed with a silicon detector on a carbon fiber support structure at small radius are presented. A grounding scheme employing copper-kapton mesh circuits is described and shown to provide adequate and robust detector performance.