Evidence of deep water penetration in silica during stress corrosion fracture

We measure the thickness of the heavy water layer trapped under the stress corrosion fracture surface of silica using neutron reflectivity experiments. We show that the penetration depth is 65-85 \aa ngstr\"{o}ms, suggesting the presence of a damaged zone of $\approx$ 100 \aa ngstr\"{o}ms extending ahead of the crack tip during its propagation. This estimate of the size of the damaged zone is compatible with other recent results.