A new measurement of the intensities of heavy cosmic-ray nuclei around 1 TeV/nucleon.

摘要

This work describes a measurement of the intensities of heavy primary cosmic-ray nuclei (O, Ne, Mg, Si, Fe) with the Transition Radiation Array for Cosmic Energetic Radiation (TRACER) up to energies around a few TeV/nucleon. TRACER is a balloon-borne cosmic-ray telescope that implements new technologies, including an array of single-wire proportional tubes, to achieve a large geometric aperture of 4.42 m2sr. It uses a transition radiation detector (TRD) to determine particle energies in the range of 500–10,000 GeV/nucleon. Measurements of the ionization energy loss in a gas and of the Cerenkov light yield in plastic discriminate against low-energy particles.; TRACER is designed to fly around the northern polar circle for 10 to 20 days. This work describes the instrument and presents the results of an analysis of data from a one-day test flight, conducted in Ft. Sumner, NM in 1999. The TRD is able to determine particle energies as high as 10 14 eV, limited only by the duration of the test flight. Furthermore, the ionization energy loss in the proportional tube array provides sufficient energy resolution to measure the intensities of nuclei with Z ≥ 12 in the intermediate energy region of 15 to 500 GeV/nucleon. The results of TRACER are essentially consistent with previous observations in this energy range, for which few measurements of the intensities of heavy cosmic-ray nuclei with individual charge resolution have been reported.