Development of very-thick transparent GEMs with wavelength-shifting capability for noble element TPCs

Abstract

A new concept for the simultaneous detection of primary and secondary scintillation in time projection chambers is proposed. Its core element is a type of very-thick GEM structure supplied with transparent electrodes and machined from a polyethylene naphthalate plate, a natural wavelength shifter. Such a device has good prospects for scalability and, by virtue of its genuine optical properties, it can improve on the light collection efficiency, energy threshold and resolution of conventional micropattern gas detectors. This, together with the intrinsic radiopurity of its constituting elements, offers advantages for noble gas and liquid based time projection chambers, used for dark matter searches and neutrino experiments. Production, optical and electrical characterization, and first measurements performed with the new device are reported.

Cryogenic setup for the characterization of wavelength-shifting materials for noble element radiation detectors

“…The WLS FAT-GEM [9] presents several advantages when compared with state-of-the-art solutions. A schematic the polymeric (i.e.…”

“…Collection efficiency for S2 is increased due to the WLS effect of the holes' walls. Such structures further optimized for low optical losses can match or exceed the performance of state-of-the-art mesh solutions [9,19].…”

“…To this end, there have been exciting developments both in identifying new WLS compounds and solutions, as well as innovative applications of known WLS [7]. An example, scalable to very large surface areas, are the polyethylene naphthalate (PEN) wavelength shifter or the FAT-GEM concept (field-assisted transparent gaseous electroluminescence multiplier) [8], combined with reflecting and WLS coatings [9] to maximize S2 light collection.…”

Novel electron and photon recording concepts in noble-liquid detectors

“…It should be mentioned that another recent concept proposes very-thick GEM structures made on wavelength-shifting transparent polymers (e.g. polyethylene naphthalate (PEN)) for primary-and EL-photon optical recording in dual-phase TPCs [56].…”

“…Another possibility would be to manufacture the MSP patterns on a transparent WLS polymer (e.g. polyethylene naphthalate (PEN)) discussed in [56]; the stability of this or other WLS-polymers in noble liquids requires detailed studies.…”