M. Staib, M. Abercrombie, B. Benson, K. Gnanvo, M. Hohlmann Department of Physics and Space Sciences Florida Institute of Technology

Outline GEM Design GEM Stretching IR GEM Stretching Characterization Future Work Presentation Outline GEM detector design for ft 3 MT station GEM stretching and framing by IR thermal method Gain uniformity measurements of detectors fabricated using this new method Future work regarding implementation of these detectors into our ft 3 muon tomography station

Outline GEM Design GEM Stretching IR GEM Stretching Characterization Future Work Gas Electron Multiplier (GEM) Detector V μ-μ- e-e- GEM foil under electron microscope (F. Sauli) ~400 V

30 cm x 30 cm triple-GEM detectors for muon tomography based on design used for the COMPASS experiment at CERN and are operated in Ar/CO 2 70:30 mixture X-Y Cartesian readout strips 1568 strips per detector 400 μm pitch Triple-GEM Detector for MT station COMPASS Design Outline GEM Design GEM Stretching IR GEM Stretching Characterization Future Work Assembled GEM Detector Drift Cathode GEM foil FR4 Spacer Frame X-Y Readout Nucl. Inst. and Meth. A 490 (2002) 177–203

Traditional GEM Foil Stretching Mechanical (INFN)Thermal (CERN/FIT) Outline GEM Design GEM Stretching IR GEM Stretching Characterization Future Work GEM foils lack mechanical rigidity and must be stretched and framed before being assembled into a detector. Traditional methods of tensioning the foils are expensive to implement. Stretching must take place under clean room conditions. Framed GEM Foil

Outline GEM Design GEM Stretching IR GEM Stretching Characterization Future Work Low-Cost GEM Stretching Using IR Heating

Outline GEM Design GEM Stretching IR GEM Stretching Characterization Future Work Low-Cost GEM Stretching Using IR Heating Two 30 cm x 30 cm detectors were assembled at FIT using GEM foils tensioned by IR heating Framed GEM Foil 30 x 30 cm 2 Active Area HV Divider Board 128 Strip Readout Connectors Gas In Gas Out

Outline GEM Design GEM Stretching IR GEM Stretching Characterization Future Work CMS Upgrade Using GEM Detectors Framed GEM Foil Gas In Potential muon upgrade at CMS using GEMs for triggering & tracking ~1 m (A. Sharma, S. Colafranceschi)

Outline GEM Design GEM Stretching IR GEM Stretching Characterization Future Work Scaled-up IR Array for Large Area GEM We have scaled up our design in order to stretch foils as large as 1 m x 0.5 m Wedge shaped drift foil for proposed CMS endcap upgrade using GEMs in the high-η region

Outline GEM Design GEM Stretching IR GEM Stretching Characterization Future Work Temperature profile of Plexiglas stretching frame Scaled-up IR Array for Large Area GEM

Outline GEM Design GEM Stretching IR GEM Stretching Characterization Future Work Gain Uniformity Measurement The gain uniformity was measured using spectra obtained from a Cd-109 gamma source.

Outline GEM Design GEM Stretching IR GEM Stretching Characterization Future Work Why use 109 Cd for Uniformity Measurements? Copper K-line Emission 55 Fe Spectrum (16 Hours) 109 Cd Spectrum (1 Hour) 5.9 keV 2.9 keV Only about 5% of the x-rays produced by 55 Fe pass through the honeycomb cover into the drift region where they can be detected. 55 Fe measurement is very slow, impractical for a large study. We can observe copper K-line fluorescence from within the detector using a 109 Cd source.

Outline GEM Design GEM Stretching IR GEM Stretching Characterization Future Work Gain Uniformity Measurement Top Strip Uniformity GEM Detector 9

Outline GEM Design GEM Stretching IR GEM Stretching Characterization Future Work Gain Uniformity Measurement Bottom Strip Uniformity GEM 9 No-peak Measurement

Outline GEM Design GEM Stretching IR GEM Stretching Characterization Future Work Gain Uniformity Measurement GEM 10 Uniformity Top Strip UniformityBottom Strip Uniformity Some problems in one corner visible on both readout axes

Outline GEM Design GEM Stretching IR GEM Stretching Characterization Future Work The GEMs assembled at Florida Tech are currently en route to CERN for use in our ft 3 muon tomography station. We are implementing full readout of all 10 detectors (~16k channels!) and will continue characterization using complete readout electronics. We are working with the CMS collaboration to scale up our IR stretching method for a proposed upgrade to the muon system using large area GEM detectors.