Charge transfer properties through graphene layers in gas detectors

Abstract

Graphene is a single layer of carbon atoms arranged in a honeycomb lattice with remarkable mechanical, electrical and optical properties. For the first time graphene layers suspended on copper meshes were installed into a gas detector equipped with a gaseous electron multiplier. Measurements of low energy electron and ion transfer through graphene were conducted. In this paper we describe the sample preparation for suspended graphene layers, the testing procedures and we discuss the preliminary results followed by a prospect of further applications.

Charge transfer properties through graphene for applications in gaseous detectors

“…The structure can be either a 5 µm-thick copper mesh with holes, or a GEM. Tests of the former structures are reported in [8]. Here we report on preliminary tests of a graphene-coated GEM.…”

“…The quality of the graphene is evaluated with Raman spectroscopy, and the coverage of the graphene is assessed using scanning electron microscopy (SEM). The coverage of single layer is found to be 90±5% and of triple layer is 99±0.5% [8]. The advantage of this technique is that the graphene can be transferred onto any metal substrate, for instance one of the faces of a GEM.…”

“…The ion transparency is defined as the ratio between the current at the cathode and the sum of the currents at the cathode and at the electrodes of the graphene-coated GEM. A detailed description of the methods to extract the electron and ion transmissions can be found in [8].…”

“…Compared to vacuum, charge transfer properties through graphene in gas are not well known. The first studies [8] showed that defects in the graphene layer play an important role in the electron and ion transmission measurements. Nevertheless, an almost defect-free triple layer graphene can be successfully transferred onto metal meshes.…”

Nanostructured materials for particle detector

“…Subsequently up to three graphene monolayers have been transferred to a copper mesh. The copper mesh-graphene stacks were inserted into a GEM detector to measure their charge transparency [21]. A strong asymmetry in transmission between low energy electrons and ions is observed in this graphene triple layer, opening the possibility to reduce the ion feedback and space charge distorsion in high rate Time Projection Chambers.…”