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TCC8 bridge radiation discussion
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865/2-C19 (CERN)
TCC8 bridge radiation discussion
Zoom Meeting ID
62670986114
Host
Aleksandr Gorn
Passcode
77218288
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WP2: TCC8 bridge radiation discussion
Participants:
Aleksandr Gorn (AG)
Camille Vendeuvre (CV)
Claudia Ahdida (CA)
Francesco Velotti (FV)
Giuseppe Mazzola (GM)
Johannes Bernhard (JB)
Laurence Nevay (LN)
Luke Aidan Dyks (LD)
Matthew Fraser (MF)
RP studies at TCC8 bridge - update (Guiseppe)
Presents FLUKA model of the TT85 beam line including the river, the bridge and the air layer between them.
Radiation source term is created with the beam tilted by 1.5 mrad in the vertical direction hitting the aperture of QNL.792 and QNL.795 vacuum system.
According to simulations, current position of the magnets in this configuration cause the dose at top of the road that is above the acceptable level.
Multiple solutions and their combinations are considered in order to reduce the dose:
1. QNL792 moved of 1.5 m on the side
2. QNLs moved 5 m downstream
3. Additional 1 m of concrete under the bridge and QNL
The reduction of the dose is presented for all the cases (Claudia: reduction by a factor of ~80 is already acceptable). Shifting of the magnets in the most effective way to reduce the dose at the top of the bridge.
Discussion
MF: It would be smart to learn something before the next year. Let us first remove the quad, then measure the dose and finally put shielding.
We should work on shielding design either. (Action: CA).
LD: Moving QNL.792 1.5 m on the side looks unrealistic.
CA: This actually means removing the magnet. It will be just kept net to the beam line for transportation reasons.
JB: I will check if we can put quads on rails. (Action: JB)
JB: 5 m shift is a lot.
MF: We will have to rematch the optics.
Shifting Q20 magnets (Luke)
- QNL.X0450792 and QNL.X0450795 shifted 5 m downstream
- Simple optimisation performed varying quads
- Target: sigX, sigY, sigPX, sigPY, same at T10 (matched with >99.9% precision)
- Q16, 18, 19, 20, 21 strengths changed within 10-20%
- New current is still below the maximum of what power converters can provide.
- Completed with latest P42 model.
- Vertical beam size at Q20 is very sensitive to initial conditions.
Discussion
F: So, if I summarise, it is possible to move the quads, right?
LD: Yes, in terms of the optics. From the background point of view it still requires studies.
JB: There are many experiments upstream, so we can use their instrumentation to reconstruct the beam parameters.
MF: Next steps - a test during commissioning.
LD: We have too many things to do during this time, so one should prioritise the list of tasks.
MF: Please, make a plan, and then we will prioritise it. (Action: LD)
MF: I would like to make this changes until the end of the year.
MF: I can produce an optimiser.
LN: We need an optics knob to adjust the beam size.
MF: We can do the quad scan to roughly learn the beam size.
LN: We can check the background there.
M: Also we should check that the beam is still centered when we change the optics.
Actions:
CA - Follow up with shielding design.
JB - Check the cost estimation for the quad transportation.
LD - Make a plan of things to do during the commissioning.
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