Next Generation TRD for CREAM Using Gas Straw Tubes and Foam Radiators

The Cosmic Ray Energetics And Mass (CREAM) experiment is designed to investigate the source, propagation and acceleration mechanism of high energy cosmic-ray nuclei, by directly meas- uring their energy and charge. Incorporating a transition radiation detector (TRD) provides an energy measurement complementary to the calorimeter, as well as additional track reconstruction capability. The next generation CREAM TRD is designed with 4 mm straw tubes to greatly improve tracking over the previous 20 mm tube design, thereby enhancing charge identification in the silicon charge detector (SCD). Plastic foam provides a weight-efficient radiator that doubles as a mechanical support for the straw layers. This design provides a compact, robust, reliable, low density detector to measure incident nucleus energy for 3 < Z < 30 nuclei in the Lorentz gamma factor range of 102 - 105. This paper discusses the new TRD design and the low power front end electronics used to achieve the large dynamic range required. Beam test results of a prototype TRD are also reported.