  Operating conditions and challenging demands of present and future
accelerator experiments result in new requirements on detector systems. There
are many ongoing activities aimed to develop new technologies and to improve
the properties of detectors based on existing technologies. Our work is
dedicated to development of Transition Radiation Detectors (TRD) suitable for
different applications. In this paper results obtained in beam tests at SPS
accelerator at CERN with the TRD prototype based on straw technology are
presented. TRD performance was studied as a function of thickness of the
transition radiation radiator and working gas mixture pressure.
