Hi everyone,
The transport simulations have been extended to include the Al window and fixture and the PrePolarizingMagnet. The PPM field plots given to me by Andy the other day imply an effective axial length of 63.4 cm at 7 T. I have used this and the as-built geometries to calculate the UCN arriving at the position of gate valve 2 located just downstream of the PPM. These calculations also include the UCN exiting two 6.4 mm dia monitoring holes located in the bottom of the quartz guides: one just downstream from gate valve 1; and, the other just upstream of gate valve 2.
Mark tells me that the specularity of the DLC in the pump-out port and gate valve 1 should have been 90% rather than the 50% I assumed in the calculations reported to you on 1/27/04. I have therefore redone those calculations and revised results for UCN exiting gate valve 1 (upstream of the PPM and just outside the shielding) are included. This change made a substantial difference.
Bottom line is that 4.87+/-0.04 x 10^(-9) completely polarized UCN/p are expected to arrive at gate valve 2 following a single proton pulse (quoted uncertainties here are statistical only.) Entering the upstream monitoring hole 1 will be 3.1+/0.1 x 10^(-10) UCN/p and the downstream monitoring hole 2 will be 2.0+/-0.3 x 10^(-11) UCN/p. The latter is about 1/2 the average UCN/p/cm^2 arriving at gate valve 2 which is reasonable. In continuous operation at 4 microAmps, the average rate of polarized UCN arriving at gate valve 2 is about 131 kHz (3,900 UCN/cm^2/s.)
Regards,
Roger