Preliminary results from a new microstructure for gaseous detectors

A new microstructure for the detection of gas ionizing radiations has been characterized. For every single detected ionizing radiation it gives a pair of “induced” charges of the same amount (pulses of the same amplitude), with opposite sign, the same collection time and, essentially, in time coincidence, that are proportional to the primary ionization collected. Gas multiplication more than 105 with more than 108 electrons in the primary avalanches, working in the proportional region, are possible. The complete lack of insulating materials in the active volume of this microstructure avoids problems of charging-up and makes its behaviour stable and repeatable. This microstructure, by the use of the charge pair generated, allows the development of a position-sensitive detector with a two-dimensional read-out. Using isobutane as the gas, an energy resolution of about 8% FWHM was recorded with α particles from an 241Am source in ΔE fashion. Always in isobutane gas, X-rays from a 55Fe source were also detected.