Optical properties of the south pole ice at depths between 0.8 and 1 km

• Main Author: Askebjer, P
• Language: English
• Published: 1994
• Subjects: Astrophysics and Astronomy; South Pole; South pole
• Online Access: http://cds.cern.ch/record/303634

The optical properties of the ice at the geographical South Pole have been investigated at depths between 0.8 and 1 kilometers. The absorption and scattering lengths of visible light (\sim515 nm) have been measured {\it in situ } using the laser calibration setup of the AMANDA neutrino detector. The ice is intrinsically extremely transparent. The measured absorption length is 59 \pm 3 meters, comparable with the quality of the ultra-pure water used in the IMB and Kamiokande proton-decay and neutrino experiments and more than two times longer than the best value reported for laboratory ice. Due to a residual density of air bubbles at these depths, the trajectories of photons in the medium are randomized. Assuming bubbles are smooth and spherical, the average distance between collisions at 1 km depth is about 25 cm. The measured inverse scattering length on bubbles decreases linearly with increasing depth in the volume of ice investigated.