Collimators for the NSRL Beam Line
For some applications we make use of collimators to shape the radiation field. We have a variety of tungsten blocks that can be stacked to produce beam spots from as small as 1 square millimeter to 20 cm2 beam spots. These are useful for protecting the incubator from direct exposure to the beam.
In addition, we have pre-assembled collimators made out of layers of Lucite, Aluminum and Polyethylene. These collimators have precision holes that allow the beam to pass through in selected regions. The holes are typically 5mm to 1cm in diameter, and can be square or round. The make-up of the collimator is optimized to stop the beam without producing many penetrating fragments. The Lucite is the first stage, and is 85 mm thick. Aluminum is the second stage, and is 75 mm thick. The final stage is polyethylene, and it is 90 mm thick. See images of the collimators below.
When using these layered collimators, it is best to start with heavy ion beams of relatively lower energy, such as 600 MeV/n Fe beams. In this way the leakage dose, or dose in the regions covered by the collimator can be kept below about 3% of the dose in the holes. At higher beam energies the leakage will be greater.
Contact the liaison physicist for special collimation requirements.
Last Modified: October 15, 2010