Prototype Development and Simulation of the Cosmic-Ray Electron Synchrotron Telescope (CREST).

Abstract

The Cosmic Ray Electron Synchrotron Telescope (CREST) instrument is a balloon payload designed to measure the flux of primary cosmic ray electrons at energies greater than 2 TeV. As electrons at these energies lose energy very rapidly during propagation through the insterstellar medium, their detection would indicate the existance of sources which are nearby on a galactic scale. In order to obtain the needed large exposure time and apperture of the detector, we use an apporach that depends on the detection of synchrotron photons emitted whne the electrons travel through the earth’s magnetic field. Such photons have energies in the x-ray and gamma ray region, hence CREST incorporates an array of inorganic scintillators. The primary electrons do not need to pass through the detector, allowing for an effective detection area that is much larger than the actual detector array size. This work focuses on three subjects: prototype detector development, prototype CREST flight (CREST-I), and insturment detection simulation. To accomplish σ = 1 ns or less timing resolution for identification of the interaction time with the detector, initial development of the BaF2 crystal and photomultiplier tube assembly was performed. The measured result shows that the timing resolution is approximately 0.7 ns. In 2005, the CREST-I flight successfully measured the diffusive and atmospheric x/γ-rays to estimate the background for real events. The flight also verified our method of photon detection and proved the performance of the electronics. GEANT 4 simulation optimized the dead time of the front-end electronics, and it shows the instrument performance of measuring synchrotron photons form high energy electrons.