Beam test of a dual layer silicon charge detector (SCD) for the CREAM experiment

The Cosmic Ray Energetics and Mass (CREAM) balloon-borne experiment is designed for direct measurement of high-energy cosmic rays. The experimental goal is to measure single-element fluxes of all cosmic-ray nuclei from hydrogen to iron with energies up to the “knee”, or spectral index change near 1015eV, observed in the all-particle spectrum. The dual layer Silicon Charge Detector (SCD) was designed to provide precise charge measurements. Each SCD layer has an active area of 77.9cm×79.5cm and consists of 156 silicon sensors mounted on 24 ladders. Each sensor contains a 4 × 4 array of single-sided DC type silicon pixels with an active area of 2.1cm2. The detector was flown on the second CREAM flight (December 2005–January 2006) and recovered successfully. The SCD was refurbished for the third CREAM flight and tested with high-energy electron and hadron beams at CERN. This paper reports on the performance of the SCD during the beam test.