Design and commissioning of a 600 L Time Projection Chamber with Microbulk Micromegas

Abstract

We report the design, construction, and initial commissioning results of a large high pressure gaseous Time Projection Chamber (TPC) with Micromegas modules for charge readout. The detector vessel has an inner volume of about 600 L and an active volume of 270 L. At 10 bar operating pressure, the active volume contains about 20 kg of xenon gas and can image charged particle tracks. Drift electrons are collected by the charge readout plane, which accommodates a tessellation of seven Micromegas modules. Each of the Micromegas covers a square of 20 cm by 20 cm. A new type of Microbulk Micromegas is chosen for this application due to its good gain uniformity and low radioactive contamination. Initial commissioning results with 1 Micromegas module running with 1 bar argon and isobutane gas mixture and 5 bar xenon and trimethylamine (TMA) gas mixture are reported. We also recorded extended background tracks from cosmic ray events and highlighted the unique tracking feature of this gaseous TPC.

A Gaseous Time Projection Chamber with Micromegas Readout for Low Radioactive Material Screening

“…A 2 mm thick polished copper plate is attached to the bottom of the field cage as the cathode, which is supplied a high voltage while the TPC is operating. The overall assembly follow resembles that field cage design in [16]. On the top of the field cage, a faced-down 20×20 cm 2 Micromegas module serves as the readout plane.…”

“…A total of 128 strips are read out with 64 channels in the X and Y direction each. A strip is made of interconnected diamond shapes with a pitch distance of 3 mm, the same design as the Micromegas described in [16]. The Micromegas is fixed to an aluminum backplane and then screwed to the top of the aluminum vessel.…”

Current Status and Future Developments of Micromegas Detectors for Physics and Applications

“…The PandaX-III experiment [87][88][89] plans to study those events with large 1.5-m, 200 kg, gaseous 136 Xe TPC modules at 10 bar pressure (Figure 20). The electron trajectories in the TPC will be measured as well as the deposited energy using Microbulk Micromegas detectors.…”

Slow Control System for PandaX-III experiment

“…A prototype detector [28] with 7 Micromegas modules is built to study the performance of high-pressure xenon TPC, especially its track recording and energy response capability. A SCS demonstrator (P-SCS) is set up to monitor the status of the prototype detector, and to optimize the final design of the SCS.…”