High accuracy imaging of single photoelectrons by low-pressure Multistep Avalanche Chamber coupled to a solid photocathode

Abstract

A position sensitive Multistep Avalanche Chamber (MSC), operated with low pressure isobutane (5–20 Torr) was coupled to a solid photocathode. It is shown that gaseous amplification factors above 10 8 are obtained, thus enabling the efficient detection of single photoelectrons. Imaging of single photoelectrons was performed using the delay-line technique. Position resolution of the order of 200 μm (fwhm) is obtained with a photoelectron detection efficiency close to 100%. Further applications are discussed.