Study of the single cluster response of a helium-isobutane drift chamber prototype using 8 keV X-rays

The identification of single clusters in the electronic signals produced by ionizingparticles within a drift chamber is expected to significantly improve the performances of this kindof detectors in terms of particle identification capabilities and space resolution. In order to developrefined cluster recognition algorithms, it is essential to measure the response of the chamber and itselectronics to single ionization clusters. This can be done by irradiating the chamber with X-rays.We report here on the studies performed on a drift chamber prototype for the MEG-II experimentat the X-ray facility of the INFN Frascati’s National Laboratories “XLab Frascati”. The prototypeis operated with a helium-isobutane mixture and instrumented with high bandwidth custom pre-amplifiers. The results of this study have been used to develop an innovative method for clusterrecognition, based on the Wiener filter technique, which has been tested on data collected at theFrascati’s Beam Test Facility. As a side measurement, we also performed a study of the gas gain ina configuration which is similar to that of the MEG-II experiment.