Preatmospheric size of the Barwell meteorite: Cosmic-ray track, fusion crust and thermoluminescence studies

Extensive measurements of cosmic-ray tracks have been made in three fragments of Barwell meteorite with a view to deduce the extent of atmospheric ablation of different crusted surfaces and in order to determine its approximate pre-atmospheric radius. Independent estimates of ablation made for several crusted surfaces from observations of fusion-crust mineralogy and thermoluminescence (TL) are in excellent accord. The observed agreement gives credence to the ablation theory and establishes usefulness of TL studies for determining atmospheric flight times. The preatmospheric ‘radius’ of Barwell is deduced to lie between 16 and 18 cm; the recovered mass amounts to 63 ± 11% of the pre-atmospheric mass. The low ablation indicates that the atmospheric and geocentric velocities of the meteorite must be less than 15 and 10 km s^-1, respectively.