Studies of fresh and fossil tracks in meteoritic hypersthene

From measurements of the total recordable lengths of fossil tracks and freshly-produced Fe ion tracks in meteoritic hypersthene, the abundance of Fe relative to all VH ions (20 ≦ Z ≦ 28) in the time-averaged cosmic-ray flux is found to be ≈ 0.35. After allowance is made for the effects of fragmentation of nuclei at a depth of ≈ 11 cm within the meteorite, this value is found to be in broad agreement with presentday measurements.

These crystals have been irradiated with a number of heavy ions with a view to calibrating them for the identification of VVH cosmic rays by measurement of track-etch velocity, V_T, as a function of residual range. A good fit to the calibration data is obtained by using a value for the constant K in the primary-ionization equation of 10.5 (±0.5). The relationship between V_T and primary ionization J appears to be approximately linear.