c/o Stefano
In prep for the sector 23 test:
- The Tungsten collimators (TCLA's) are interlocked and should
never be moved.
- I left only one Carbon collimator closed: The TCSG.5L3.B1
I showed to Alick and Eric how to open it if you want to
do the optics down to Q4. In case of long set-up time, it
is better to leave the TCSG closed and not to send too much
beam onto the Tungsten TCLA's.
Good luck!
Stefano
Propose to follow the same baseline:
- Interlock in closed position the first two Tungsten TCLA's (H+V) with no mechanical blockage of the jaws.
- Keep closed, but operational, the Carbon collimators upstream
(three primary and six secondary collimators)
- Powering of warm dipoles and quadrupoles as of the nominal optics
In IP7 the first two TCLA's (TCLA.A6L7.B2 and TCLA.B6L7.B2) are downstream of the Q5-R7, i.e. closer than in IP3 to the end of
sector. RP is informed and will give his feedback about that.
The requirements for the other collimators that will see beam are:
- TDI in IP8 movable in in/out positions
- Injection protection devices (TCDI's in TI8 and TCLIB in IP8) in fully open position, not to be moved during the test;
- Tertiary collimator upstream of LHCb fully open, not to be moved.
Layout name s [m] bx[m] by[m] L[m] Mat
TCP.D6R7.B2 6459.44 160.42 77.53 0.6 C
TCP.C6R7.B2 6461.44 152.03 82.01 0.6 C
TCP.B6R7.B2 6463.44 143.92 86.72 0.6 C
TCSG.A6R7.B2 6502.73 40.61 225.11 1.0 C
TCSG.A5R7.B2 6565.96 182.14 149.03 1.0 C
TCSG.B4R7.B2 6653.22 152.69 120.07 1.0 C
TCSG.A4R7.B2 6657.22 140.86 129.62 1.0 C
TCSG.A4L7.B2 6673.22 100.49 174.04 1.0 C
TCSG.6L7.B2 6811.08 339.26 47.19 1.0 C
TCLA.A6L7.B2 6818.14 300.27 47.89 1.0 W
TCLA.B6L7.B2 6849.02 161.51 75.78 1.0 W
TCLA.C6L7.B2 6882.29 69.50 151.08 1.0 W
TCLA.D6L7.B2 6884.29 65.87 157.10 1.0 W
TCLA.A7L7.B2 6901.92 65.66 144.18 1.0 W
the following proposal for the IP3 collimator operational scenario to stop the beam during the sector test.
After various iterations, we propose that:
- The first two TCLA's (TCLA.A5R3.B1 and TCLA.B5R3.B1) should be kept
in close position and used as beam stoppers.
- The 5 Carbon (TCP and TCSG) upstream of the TCLA's will be moveable from the CCC and in fact will be opened to commission the warm insertion Q4-R3 (limited number of shots).
- The beam will mainly be stopped by the first TCSG, downstream of D3
The main motivation not to dump all the beam on the TCLA is that the activation of Tungsten is significantly larger than for Carbon, as presented by Helmut in a recent injection test meeting. Typical figures can be found in his slides.
A new ingredient that came up recently during discussions with the DSO is that it does not seem to be mandatory to lock mechanically the collimators used to stop the beam. The consignation of the circuits of sector 3-4 will ensure that the beam will not make it through the arc. The risk of loosing a few shots in the first arc cells (e.g. in case loss of jaw auto-rectraction) is considered acceptable.
I think that this is a good solution for us because we do not need to disable the motors, we do not have to send people in an activated
area to unblock the collimators and we do not have keep the collimators disabled during the cooling period of some weeks.
However, we have to make sure that we can safely keep the collimators in the required position to stop the beam.
For this purpose, I propose to rely on the collimator hardware interlock based on discrete limit values for the jaw positions.
This would be the NOMINAL LHc configuration for the system!
Yesterday I started preliminary tests to verify the required functionality from the CCC. I would like to leave for the weekend the IR3 collimators in their operational positions for the sector test.
We can review the behaviour of the system early next week. We still have the possibility to lock the very last TCLA (that should see no
beam -> no problem to work on it) if the proposed interlocking strategy is not considered adequate.
P.S.: List of B1 collimators in IP3 for reference:
"TCP.6L3.B1" 6487.9713
"TCSG.5L3.B1" 6521.4928
"TCSG.4R3.B1" 6708.0758
"TCSG.A5R3.B1" 6719.4208
"TCSG.B5R3.B1" 6725.2408
"TCLA.A5R3.B1" 6755.7208
"TCLA.B5R3.B1" 6757.7208
"TCLA.6R3.B1" 6844.2703
"TCLA.7R3.B1" 6915.6758
Please keep in mind the two TCS without tank cooling:
TCSG.4R3.B1
TCSG.A5R3.B1
and monitor the jaw temperature (not more than 70deg C).
Ramses