Performances of the leak microstructures

The capabilities of a new microstructure, anode point based, for the detection of gas ionizing radiations are stressed. For every single detected ionizing radiation it gives a pair of “induced” charges (anodic and cathodic) of the same amount (pulses of the same amplitudes), of opposite sign, with the same collection time and essentially in time coincidence, that are proportional to the primary ionization collected. The complete lack of insulating materials in the active volume of this microstructure avoids problems of charging-up and makes stable and repeatable its behaviour. Primary avalanches with a size of more than 2.5×107 electrons (4 pC) giving current pulses with a peak of more than 0.26 mA on 100 Ω and about 30 ns duration are possible with 5.9 keV X-rays of 55Fe working in proportional region and in isobutane gas. Single electrons emitted by a heated filament (Ec<1 eV) were detected in 760 Torr of isobutane; with an estimated gas gain of 1.2×106 a counting rate up to 800 k pulses/s per single microstructure was achieved. Three different types of position-sensitive two-dimensional read-out detectors, based on these microstructures, in development are presented.