On BL1B, the proton beam is converted into a neutron beam using a cylindrical lead converter, as shown in the schematic below. (The schematic is not to scale.)
The resulting neutron beam is cone-like. The diameter of the beam spot and the beam intensity change with the square of the distance R from the neutron converter. Note that R is not the same as P, the distance between the end of the beam pipe and the DUT that is measured in the test room. R is 96 cm longer than P.
If at position R₁, the maximum beam flux is φ₁ (in neutrons/cm²/s) and the beam spot diameter is D₁, then the beam characteristics at position R₂ can be calculated from those at R₁ using the following relationships:
The maximum beam flux φ corresponds to neutron flux that can be achieved using the maximum proton current on BL1B. It is always possible to lower the flux, but not to increase it past this safety limit.
Use the calculators below to plan your tests using the most up-to-date calibrations of the BL1B neutron beams.
I want a neutron beam with a diameter of at least cm.
I want to reach a flux of neutrons/cm²/s.
I want to setup cm from the end of the beam pipe.