Triple GEM Detectors for the Forward Tracker in STAR

TL;DR

This paper presents the development and testing of triple GEM detectors designed for the forward tracking upgrade of the STAR detector at RHIC, demonstrating high efficiency and spatial resolution suitable for future spin structure measurements.

Contribution

It introduces a cost-effective triple GEM detector design with Tech-Etch foils and laser-etched readout, showing promising beam test results for the STAR upgrade.

Findings

Detectors achieved around 70 μm spatial resolution.

Detectors demonstrated high operational stability and efficiency.

The impact of particle incidence angle on resolution was characterized.

Abstract

Future measurements of the flavor-separated spin structure of the proton via parity-violating W boson production at RHIC require an upgrade of the forward tracking system of the STAR detector. This upgrade will allow the reconstruction of the charge sign of electrons and positrons produced from decaying W bosons. A design based on six large area triple GEM disks using GEM foils produced by Tech-Etch Inc. has emerged as a cost-effective solution to provide the necessary tracking precision. We report first results from a beam test of three test detectors using Tech-Etch produced GEM foils and a laser etched two dimensional strip readout. The detectors show good operational stability, high efficiency and a spacial resolution of around 70 um or better, exceeding the requirements for the forward tracking upgrade. The influence of the angle of incidence of the particles on the spatial resolution of the detectors has also been studied in detail.