Imaging micro-well proportional counters fabricated with masked UV laser ablation

The micro-well detector is a gas-proportional counter similar to the CAT (Bartol et al., J. Phys. III 6 (1996) 337) and WELL detectors (Bellazzini et al., Nucl. Instr. and Meth. A 423 (1999) 125). The micro-well is a cylindrical hole formed in the polymer substrate of commercially fabricated copper-clad flexible printed circuit board by UV laser ablation. The micro-wells are drilled at GSFCʹs UV laser-ablation facility. The cathode is a metal annulus that surrounds the opening of the well. The anode is a metal pad that fills the bottom of the well. Advantages of this topology include intrinsic two-dimensional sensing, thick robust electrodes, and large localized image charge on the cathodes. e fabricated 5 cm×5 cm micro-well detectors with segmented anodes (1-d) and with both anodes and cathodes segmented (2-d), and have demonstrated: , proportional operation at gas gains in excess of 30,000 in Ar- and Xe-based gases; nergy resolution of 20% at 6 keV in P-10; inary 1-d spatial resolution of ⩽150 μm (rms) in P-10; and pability of MWDs to produce 2-dimensional images. port on the design, fabrication, and testing of 1-d, 2-d, and pixelized micro-well detectors.