Tagger Hall
Shielding Basis for Hall D Complex (old note before shielding optimization)
Neutron background estimates in the hall
Radius of the exit electron beam pipe
Do we need a wider beam pipe transporting electrons into the dump? By Sept 2014 a 6 imch diameter pipe brought the beam to about 2m in front of the dump wall. It ends with a thick flange connected to a 1.5 inch pipe transporting the beam through the wall. There is a girder with a valve between the flange and the wall. The flange became a hot spot after the first beam tune in May 2014. Would it help to install a wider pipe from the flange through the wall?
- The deflection of the electron beam from the photon beam in this area is about L=400cm
- The electrons deflected not more than r cm from the trajectory of the non-radiated beam go into the beam dump. The others dump their energy into the hall.
- The full power of the photons is WB·R, where WB is the power of the electron beam and R is the radiator thickness in R.L.
The energy dumped by the radiator electrons into the hall is WB·R·(ln(L/r)-1+r/L)
| r, cm | W/(WB·R) |
|---|---|
| 1 | 5.0 |
| 2 | 4.3 |
| 3 | 3.9 |
| 4 | 3.6 |
| 5 | 3.4 |
| 6 | 3.2 |
| 10 | 2.7 |
The increase of the exit pipe radius from 2cm to 4cm would reduce the power dumped in the hall by the radiated electrons by about 15%.
