Slotted carbide anvils: improved X-ray access for synchrotron-based multi-anvil experiments

We present a new technique to allow enhanced X-ray access to synchrotron-based multi-anvil experiments with tungsten carbide anvils. Slots of 2 mm width and 1 mm depth are cut into the four anvils which are in the beam path along their ? 110? diagonals and these slots are filled with baked pyrophyllite to produce a region in the anvils which is X-ray transparent. We have tested this arrangement using a standard 10/5 cell assembly and the X-ray window remains open, allowing imaging of a 2.5 by 2 mm section of the cell to at least 20 GPa. There is no evidence that the slots reduce the life of the anvils and the recovered slotted anvils have been used in subsequent experiments.