USE OF TUNGSTEN ANODES IN MICROGAP GAS-CHAMBERS

In a continuation of our earlier tests[1,2], tungsten has been used fo r anode strips in the fabrication of microgap gas chambers (MGCs) in a n attempt to find a metallization suitable for gas avalanche microdete ctors (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 t hick 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 havi ng a range of energies, and the damage to the anode strips was assesse d using optical and scanning electron microscope (SEM) photographs, an d by measuring leakage current before and after sparking. In this pape r, the spark damage test results of tungsten anodes in MGCs are report ed, and an interpretation is made regarding the viability of use of th is metal for larger sizes of detectors.