Münster 2017 – scientific programme

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T: Fachverband Teilchenphysik

T 117: Myondetektoren 2

T 117.5: Talk

Thursday, March 30, 2017, 17:50–18:05, VSH 06

Characterization tests of Micromegas with elongated pillars — •Ourania Sidiropoulou — CERN and University of Wuerzburg

Micromegas are micro-pattern gaseous detectors which are more and more widely used in physics experiments. Micromegas are parallel-plate chambers where the amplification region is separated from the conversion region by a thin metallic micro-mesh. The width of the amplification region is defined by regularly spaced insulating pillars.

The pillars are made by photo-lithography from a uniform layer of photoimageable coverlay; its thickness defines the amplification gap. Since pillars produce a dead area and a perturbation of the electric field in the region nearby, the design of the pillar pattern is an important parameter. Moreover it has been observed that the attachment of small pillars to the anode plane of the detector is a critical factor for industrially produced large-size anode boards.

In this talk, a resistive micromegas detector built with a new pillar pattern with elongated shapes with length between few mm up to 10 cm will be presented. The detector features readout strips with a width of 250 μm and a pitch of 400 μm. The pillars extend in the direction orthogonal to the readout strips and are 200 μm wide. The larger surface of the pillars allows for a better adhesion to the readout structure and a more uniform amplification gap.

After the motivation of the new proposed structure, the presentation focuses on the characterization of the detector. Results on gain measurements, electron mesh transparency, ion back-flow, efficiency, spatial resolution and tracking performance are presented.