[en] Thin-walled drift tubes have been used in conjunction with a superconducting magnet for the rigidity spectrometer aboard two recent particle astrophysics experiments flown on high altitude balloons: PBAR (a low energy antiproton search) and SMILI (the superconducting magnet instrument for light isotopes). The HEAT (high energy antimatter telescope) experiment currently under construction will also employ this technology. This paper reviews the design, construction, and in-flight operation of the PBAR and SMILI systems, as well as the design of the HEAT system which will be used in conjunction with a new superconducting magnet aboard an upcoming series of balloon experiments to study high energy positrons and antiprotons in the cosmic radiation. In addition to a brief account of the scientific goals for these flights, the prospects for future application of this technology to long duration exposures aboard antarctic balloon flights and spacecraft are discussed. (orig.)

[en] We describe the PBAR balloon-borne magnet spectrometer flown on August 13-14, 1987 to measure the abundance of cosmic ray antiprotons in the energy interval 100-1580 MeV at the top of the atmosphere. The limits first reported have been improved to an overall limit of anti p/p<2.0x10^-5 (85% CL). We summarize the overall design and performance of the PBAR spectrometer, which had the unique ability to establish the mass of each singly charged cosmic ray, as well as to reject spurious antimatter candidates caused by hard scatterings within the instrument. (orig.)

[en] The HEAT (high-energy antimatter telescope) instrument has been developed for a series of observations in cosmic-ray astrophysics that require the use of a superconducting magnet spectrometer. This paper describes the first configuration of HEAT which is optimized for the detection of cosmic-ray electrons and positrons below 100 GeV. In addition to the spectrometer, a combination of time-of-flight scintillators, a transition radiation detector, and an electromagnetic shower counter, provides particle identification, energy measurement, and powerful discrimination against the large background of protons. The instrument was successfully flown aboard high-altitude balloons in 1994 and 1995. The design and construction of the spectrometer and of the detector systems are described, and the performance of the instrument is demonstrated with data obtained in flight. (orig.)

[en] We present a new measurement of atmospheric muons made during an ascent of the High Energy Antimatter Telescope balloon experiment. The muon charge ratio μ⁺/μ^- as a function of atmospheric depth in the momentum interval 0.3-0.9 GeV/c is presented. The differential μ^- intensities in the 0.3-50 GeV/c range and for atmospheric depths between 4-960 g/cm² are also presented. We compare these results with other measurements and model predictions. We find that our charge ratio is ∼1.1 for all atmospheric depths and is consistent, within errors, with other measurements and the model predictions. We find that our measured μ^- intensities are also consistent with other measurements, and with the model predictions, except at shallow atmospheric depths