Simulation Project SANS-2: Pinhole collimation

Place one pinhole (circular slit), 8 mm diameter, right after the exit of the velocity selector, and place an identical one 6 m downstream. Simulate the divergence of the beam after the second slit. Compare to the calculated values.

Perform the same task for the case of \(L_c=3\) m (move the first slit 3 m further downstream). Does it make a difference to place a 3 m guide piece after the velocity selector? Why?

McStas hint

You may like to store the results of your two simulations by virtual_output to ease the simulations in the problems below. You will probably need \(1 \cdot 10^9\) rays or more to reach reasonable statistics. It might be a good idea to produce the virtual sources over the weekend.