Cosmic Ray Deuterium from 0.2 to 3.0 GeV/nucleon

The abundances of cosmic ray protons and deuterium between 0.2 and 3.0 GeV/nucleon were measured by the IMAX balloon--borne magnet spectrometer during a flight in July, 1992. These isotope measurements extend to significantly higher energies than have previously been achieved. A high--resolution time--of--flight system and two silica aerogel Cherenkov counters were used in conjunction with a drift--chamber/MWPC--tracking system to determine mass by means of the velocity vs. magnetic rigidity technique.

We present here the abundances of ^1H, ^2H and ^4He corrected to the top of the atmosphere, and the resulting ^2H/^1H and ^2H/^4He isotope ratios. The IMAX experiment was supported by NASA: RTOP 353--87--02 (GSFC); grants NAGW--1919 (Caltech) and NAGW--1418 (NMSU), and in Germany by the DFG and the BMFT.