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GEMs by the Mile (2003)

GEMs by the Mile (2003)

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Detector Layout In the context of development of low-background gaseous detectors by the group, a first batch of approximately 2,000 Gas Electron Multipliers (GEMs) has been produced in collaboration with 3M's Microinterconnect Systems Division, using their automated flexible circuit production line (Figure 1). This is the first instance of industrial mass production of Micropatterned Gaseous Devices (MPGDs), recent technologies that are revolutionizing the field of gaseous radiation detectors. To put things in perspective, this single first test batch represents roughly twice the total production of GEMs at CERN since their inception there by F. Sauli in 1997. GEM features are as small as 55 µm, repeated over the entire surface of the elements, with exacting tolerances. The process developed allows low-cost, reproducible fabrication of an unlimited number of GEMs of dimensions up to 30x30 cm2. First tests indicate that the resulting GEMs have excellent properties as radiation detectors. This now demonstrated industrial capability should help establish the growing prominence of MPGDs in particle physics, medical imaging and photodetection (inexpensive photocathode-coated GEMs are increasingly perceived as the alternative to costly photomultiplier tubes). This technological breakthrough remedies the problem of an ever growing demand for MPGDs by international research groups and as such has attracted a large attention, first among the HEP community: large GEM-based time projection chambers are the choice tracking system in Next Linear Collider proposals and in hadron-blind detectors for heavy-ion physics programs.


Figure 1. Figure 1.
Left: A single continuous roll containing a production of ~1,000 subtractive GEM elements.
Right: 3M's roll to roll flexible circuit manufacture in clean room conditions. The maximum GEM area permitted at present in 3M's production line is 30x30 cm2 already comparable to the largest MPGDs produced for high-energy physics experiments.

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