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Updated: May 20, 2025
Preparing an Isotopically Pure 229Th Ion Beam for Studies of 229mTh
Published on: May 3, 2019
Micromegas with GEM preamplification for enhanced energy threshold in low-background gaseous time projection chambers
Juan Francisco Castel Pablo1, Susana Cebrián Guajardo1, Theopisti Dafni1
1Center for Astroparticles and High Energy Physics (CAPA), University of Zaragoza, Zaragoza, Aragon, Spain.
Background:
We develop the concept of a Micromegas readout plane with an additional GEM preamplification stage placed a few millimetres above it to increase the maximum effective gain of the combined readout.
Methods:
We implement it and test it in realistic conditions for its application to low-background dark matter searches like the TREX-DM experiment. For this, we use a Micromegas of Microbulk type, built with radiopure materials.
Results:
We report on GEM effective extra gain factors of about 90, 50 and 20 in 1, 4 and 10 bar of Ar-1%iC 4H 10. These results are obtained in a small test chamber allowing for systematic scanning of voltages and pressures. In addition, a TREX-DM full-scale set-up has also been built and tested, featuring a replica of the fully-patterned TREX-DM Microbulk readout.
Conclusions:
The results here obtained show promise to lower the threshold of the experiment down to 50 eV , corresponding to substantially enhanced sensitivity to low-mass WIMPs.
