MPGD with a 3D-printed Thick-GEM as sole gain element

TL;DR

This work addresses MPGD supply limitations by demonstrating a fully 3D-printed Thick-GEM that functions as the sole gain element. The authors design a 10 cm × 10 cm THGEM with three rim sizes and test its performance in Ar/CO$_2$ 70:30, finding that the 0.15 mm rim sector achieves gains above $10^4$, while other rims underperform, with a notable time-dependent gain rise and slow decay due to charging-up of the insulating 3D-printed material. The results establish a proof-of-principle for in-house fabrication of active MPGD gain elements and identify critical factors such as rim geometry, print quality, and conditioning time, outlining a path toward larger-area, fully 3D-printed detectors. This work potentially enables rapid, cost-effective production of MPGDs and may accelerate detector development by allowing end users to manufacture devices in-house via additive manufacturing.

Abstract

We present the first micropattern gaseous detector that employs a small 3D-printed Thick-GEM as its sole gain element. The detector can achieve sufficient gas gain for regular operation without the need for pre-amplification by additional gain elements. We describe the design, quality control, assembly, and test of this detector. The 10 cm $\times$ 10 cm active area of the Thick-GEM features three separate sectors with different sizes of the clearance rim annuli (0.1 mm, 0.15 mm, 0.2 mm) around the 0.7 mm diameter holes. The gas gain is found to depend strongly on the rim size. When operated in Ar/CO$_2$ 70:30 gas, the sector with 0.15 mm annulus rims reaches a gain above 10$^4$ while operating in a stable manner with an acceptably low discharge rate. The gain reach under stable operation is found to be considerably lower in the other two sectors. The gas gain shows a characteristic time-dependence as it rises quickly in the first hour of operation and then drops slowly over the next 24 hours and subsequently stabilizes.

Figures (14)

• Figure 1: View of the 10 cm $\times$ 10 cm THGEM design within Altium Designer. The front (back) electrodes are show in red (blue).
• Figure 2: Typical hole dimensions and pitches for standard THGEMs (reproduced from Alexeev:2015kda).
• Figure 3: Left: 3D-printed THGEM as delivered by printer company. Right: Light from a ring light shining through the THGEM.
• Figure 4: Close-up of three sectors with rim sizes of 0.1 mm, 0.15 mm, and 0.2 mm (left to right).
• Figure 5: Optical microscopy of THGEM holes. Top: Holes designed to have no rims, but with actual 0.1 mm rim annulus. Center: Holes designed to have 0.1 mm rim annulus, but with actual 0.15 mm rim annulus. Bottom: Holes designed to have 0.18 mm rim annulus, but with actual 0.2 mm annulus.