Use of tungsten anodes in microgap gas chambers

In a continuation of our earlier tests[1,2], tungsten has been used for anode strips in the fabrication of microgap gas chambers (MGCs) in an attempt to find a metallization suitable for gas avalanche microdetectors (MSGCs or MGCs) that will be both highly robust against sparking and yet have sufficiently low resistivity to permit use of detectors of relatively larger sizes. MGCs having about 5500 and 7500 Angstrom thick tungsten anodes were fabricated using a sputtering technique, and the sheet resistances for these layers were measured as 0.42 and 0.27 Ohm/square, respectively. The detectors were subjected to sparks having a range of energies, and the damage to the anode strips was assessed using optical and scanning electron microscope (SEM) photographs, and by measuring leakage current before and after sparking. In this paper, the spark damage test results of tungsten anodes in MGCs are reported, and an interpretation is made regarding the viability of use of this metal for larger sizes of detectors.