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Joint BLM Threshold and LHC Collimation Working Group
meeting
2014 August 25
Francesco Cerutti, Anton Lechner, Eleftherios
Skordis
for the team
COLLIMATOR LOADAND BLM RESPONSE
proton interaction distribution in the collimators
by Roderik Bruce et al. (collimation team)
2014 August 25 F. Cerutti CWG#179 2
DIFFERENT SENSITIVITY [I]
PRIMARY COLLIMATORS (IR7, B1) 3.5 TeV
halo plane
BLMresponse
protoncatcher
BLM_TCP.D BLM_TCP.C BLM_TCP.B
horizontal TCP.C 0.01 1 2.53
vertical TCP.D 0.58 1.80 2.13
normalized to 4.58 10-12 Gy/p i.e. the BLM_TCP.C response to a 3.5 TeV proton caught in the
TCP.C6.5 TeV
BLM_TCP.C
1.38
dependence on jaw orientation
dominant cross talk
energy dependence
2014 August 25 F. Cerutti CWG#179 3
DIFFERENT SENSITIVITY [II]
TERTIARY COLLIMATORS (IR5, B1) 3.5 TeV
halo plane
BLMresponse
protoncatcher
BLM_TCTH BLM_TCTV
horizontal TCTH 6.27 1.21
horizontal TCTV 0.43 3.23
normalized to 4.58 10-12 Gy/p i.e. the BLM_TCP.C response to a 3.5 TeV proton caught in the
TCP.C7 TeV
BLM_TCTH BLM_TCTV
18.1 4.68
0.71 13.9
dependence on jaw material
dependence on jaw orientation
cross talk, even backwards
energy dependence
2014 August 25 F. Cerutti CWG#179 4
REFERENCE AND BENCHMARKING
E. Skordis’ presentation at the CWG #160 on May
6, 2013
2014 August 25 F. Cerutti CWG#179 5
LOSS DEPTH IN THE TCTs
TCT
V
TCT
H
TCTH
TCT
V
shifted by
5mm
3.5 TeV2011
7 TeVHL-LHC
shifted by 7.5mm
2014 August 25 F. Cerutti CWG#179 6
VARIATION OF THE TCT BLM RESPONSE [I]
TERTIARY COLLIMATORS (IR5, B1) 3.5 TeV
halo plane
BLMresponse
protoncatcher
BLM_TCTH BLM_TCTV
vertical TCTH 6.73 1.47
vertical TCTV 0.53 3.08
normalized to 4.58 10-12 Gy/p i.e. the BLM_TCP.C response to a 3.5 TeV proton caught in the
TCP.C7 TeV
BLM_TCTH BLM_TCTV
19.1 6.10
0.60 15.3
2014 August 25 F. Cerutti CWG#179 7
TERTIARY COLLIMATORS (IR1, B1) 3.5 TeV
halo plane
BLMresponse
protoncatcher
BLM_TCTH BLM_TCTV
vertical TCTH 7.21 1.14
vertical TCTV 0.40 3.25
normalized to 4.58 10-12 Gy/p i.e. the BLM_TCP.C response to a 3.5 TeV proton caught in the
TCP.C
VARIATION OF THE TCT BLM RESPONSE [II]
2014 August 25 F. Cerutti CWG#179 8
TERTIARY COLLIMATORS (IR1, B1) 3.5 TeV
halo plane
BLMresponse
protoncatcher
BLM_TCTH BLM_TCTV
horizontal TCTH 6.90 1.07
horizontal TCTV 0.41 3.31
normalized to 4.58 10-12 Gy/p i.e. the BLM_TCP.C response to a 3.5 TeV proton caught in the
TCP.C
VARIATION OF THE TCT BLM RESPONSE [III]
2014 August 25 F. Cerutti CWG#179 9
LOAD ON THE TCT JAWS
TCTH: 2.14 + 2.58 10-7 J per caught
protonTCTV: 3.22 + 1.82 10-7 J per caught
proton
7 TeVHL-LHC
2014 August 25 F. Cerutti CWG#179 10
LOAD ON THE TCP JAWS3.5 TeV
TCPC: 1.05 10-8 J (in the whole collimator) per caught proton
TCPB: 3.9 10-8 J (in the whole collimator) per proton caught in
the TCPC
[F. Cerutti’s presentation at the CWG #108 on Nov 9,
2009]
here (multiple) ionizing passages of halo
protons before interaction not considered
2014 August 25 F. Cerutti CWG#179 11
THE GLOBAL VIEW: IR7 LSSTCP
TCSG
TCLA
1MW @ 4 TeV
2014 August 25 F. Cerutti CWG#179 12
CONCLUSIONS
Number of protons lost in a collimator and signal of the respective BLM are not
connected by an universal constant. Strong dependence on jaw material, orientation
and relative BLM position as well as very important cross talk.
Response matrices (per lost proton) were calculated for primary and tertiary
collimators, considering different beam energies and machine configurations. Looking
at TCTs, the various spatial distributions of losses in the collimator jaws, varying from
one collimator to another and as a function of the halo plane and of optics and
collimator settings, with averages values of the order of mm, do not affect significantly
the BLM response. Collimator settings may significantly change the number of losses
on a collimator and consequently scale up the respective BLM signal, without changing
the response matrix. Before writing numbers in stone, a systematic revision is
advisable (e.g. to uniform assumptions on jaw density).
Assessment of collimator load limits can be improved based on joint simulations
including the thermomechanical stage.
Physics debris collimator thresholds are a special case, not touched here.
2014 August 25 F. Cerutti CWG#179 13