(Proposal for) IR7 Threshold
Changes for the 2016 p-Pb Run
(aka the art of extrapolating from one point)
A. Mereghetti, on behalf of the LHC Collimation Team
11 Oct 2016
2
Summary of Discussions So Far
•
p-Pb / Pb-p run at 6.5 Z TeV:
•
Adjust BLM thresholds based on ion collimation quench test of 2015
(@6.37 Z TeV):
•
•
•
•
IR7 DS, based on LM when quench took place;
IR7 collimators (actually, TCP TCSG? only), in order to dump on
collimators before dumping on cold BLMs (D.Wollmann);
Instead of using 2015 BLM thresholds as during ion run, get increase
factors wrt present BLM thresholds;
p-Pb run at 4 Z TeV:
•
Can we adjust the BLM thresholds in a way similar to the one for 6.5 Z
TeV?
Based on available info:
•
•
•
•
Use past qualification LMs at 4 Z TeV (2013);
Linear scaling of key quantities (e.g. quench level, endep profile in SC
coils, …);
Instead of using 2013 BLM thresholds as during ion run, get increase
factors wrt present BLM thresholds;
Updates wrt last week
11 Oct 2016
3
6.5 Z TeV
11 Oct 2016
4
Recap Of 2015 Ion Coll Quench
Test
•
•
Quench test performed inducing
controlled losses (ADT) on B2H;
 losses achieved with a relatively
slow ramp, in the effort of “reproducing”
steady state;
Managed to quench MBB.9L7.B2 with
~10s of excitation up to 15 kW;
 Representative of steady state?
~3s
~10s
Reports: 199th (2016-01-22) and 201st (2016-03-07)
Coll WG Meetings, CERN-ACC-NOTE-2016-0031
Time stamp
2015-12-13 22:08 (fill #4723)
PL [kW] (50Hz BCT data)
15
Losses
1.47 1010 charges/s (i.e. 3.3 1010 nucleons/s or 1.79 1010 ions/s - ~2.6 nominal bunches /s)
hmax (during test) []
2.25 10-2 @BLMEI.09L7.B2I30_MBB
PDS [W]
340
Result
MBB.9L7.B2 quenched
IR7 collimator settings
2015 operational, i.e.: 5.5s (TCP), 8s (TCSG), 14s (TCLA)
11 Oct 2016
5
Adjust BLM Thresholds in IR7 DS
RS09
Ratio of BLM signals just before the dump (noisesubtracted) and BLM thresholds used during
2016 proton operation (fill #5393, from 2016-1009 to 2016-10-10, physics):
• @6.5 TeV (instead of 6.37Z TeV);
• after YETS2015 corrections (BLM ECR0044);
RS09
MQTL.06R3
MQ.11L5
Cells 09L7 and 11L7
11 Oct 2016
6
Adjust BLM Thresholds in IR7 DS (II)
F
BLMs requiring
threshold change
Increase factor wrt
2016 BLM thresholds
BLM name
BLMEI_09L7_B2I21_MBB
BLMQI.11L7.B2I10_MQ
BLMEI_09L7_B2I22_MBA
BLMEI.09L7.B2I24_MBA
BLMEI.09L7.B2I23_MBA
BLMEI.09L7.B2I25_MBA
BLMEI_09L7_B2I21_MBA
BLMQI.11L5.B2E10_MQ
BLMBI_11L7_B0T10_MBB-MBA
BLM2I_11L7_B2I24_MBA_MBA
BLMEI.11L7.B2I30_MBB
BLMQI.09L7.B2I10_MQ
BLMBI_11L7_B0T20_MBA-LEIR
BLMQI.06R3.B2E10_MQTL
BLMEI.09L7.B2I30_MBB
BLMBI_09L7_B0T10_MBB-MBA
11 Oct 2016
RS08
0.31585
0.500848
0.351742
0.35724
0.367509
0.399902
0.412887
0.656563
0.818373
0.590397
0.592483
0.939858
1.26855
0.919643
1.12909
2.10223
RS09
0.537429
0.762449
0.597653
0.607201
0.624507
0.679698
0.702243
0.998189
1.24083
1.00679
1.01041
1.43184
1.93133
1.65268
1.92117
3.26085
RS10
1.07462
1.12278
1.191
1.20762
1.2439
1.3542
1.39983
1.47476
1.83978
1.99404
2.00095
2.10295
2.85161
3.78013
3.82517
5.40044
RS10: 20%
7
Adjust BLM Thresholds in IR7 DS (II)
F
BLMs requiring
threshold change
Increase factor wrt
2016 BLM thresholds
BLM name
BLMEI_09L7_B2I21_MBB
BLMQI.11L7.B2I10_MQ
BLMEI_09L7_B2I22_MBA
BLMEI.09L7.B2I24_MBA
BLMEI.09L7.B2I23_MBA
BLMEI.09L7.B2I25_MBA
BLMEI_09L7_B2I21_MBA
BLMQI.11L5.B2E10_MQ
BLMBI_11L7_B0T10_MBB-MBA
BLM2I_11L7_B2I24_MBA_MBA
BLMEI.11L7.B2I30_MBB
BLMQI.09L7.B2I10_MQ
BLMBI_11L7_B0T20_MBA-LEIR
BLMQI.06R3.B2E10_MQTL
BLMEI.09L7.B2I30_MBB
BLMBI_09L7_B0T10_MBB-MBA
RS08
0.31585
0.500848
0.351742
0.35724
0.367509
0.399902
0.412887
0.656563
0.818373
0.590397
0.592483
0.939858
1.26855
0.919643
1.12909
2.10223
RS09
0.537429
0.762449
0.597653
0.607201
0.624507
0.679698
0.702243
0.998189
1.24083
1.00679
1.01041
1.43184
1.93133
1.65268
1.92117
3.26085
RS10
1.07462
1.12278
1.191
1.20762
1.2439
1.3542
1.39983
1.47476
1.83978
1.99404
2.00095
2.10295
2.85161
3.78013
3.82517
5.40044
RS10: 20%
Remarks:
• RS10 (5.24s) in general requires the largest changes;
• Possible corrections: flattening out at RS10? Or is it better RS by RS? (from RS08 through
RS12);
• Slightly larger increase factors wrt 2015 ion BLM thresholds, but picture does not change
significantly:
• Slightly larger beam energy (6.5TeV instead of 6.37Z TeV);
• Updates to cold BLM thresholds during YETS2015 (BLM ECR0044);
11 Oct 2016
8
Adjust BLM Thresholds at IR7 Collimators
Let’s set BLM thresholds at selected IR7 collimators (TCPs? TCSGs?) such that we
dump on collimators instead of on cold BLMs in the IR7 DS:
1. Assume BLM signals at IR7 collimators from LM at quench (B2H, 6.37Z TeV) as
operational thresholds for 6.5Z TeV run;
2. From (calibrated) qualification LMs for 2016 proton run (FT, B1/2, H/V), get max
power loss allowed and corresponding MF;
NB: changes by MF (E.B.Holzer) save time and simplify the problem…
…hoping not to get trapped in dumps at injection!
MF [x10-3]
30kW
H H V
11 Oct 2016
V S S
9
Adjust BLM Thresholds at IR7 Collimators
Remarks:
1. Lowering MFs at selected IR7 collimators may look a feasible way to restore the
correct dump hierarchy;
1. We would not create new families;
2. Manual adjustments allow for more point-like corrections;
3. Can be applied to one beam at a time;
2. If applied to both beams at the same time, we would limit losses from the proton
beam at >30kW (at present: ~200kW);
MF [x10-3]
30kW
H H V
11 Oct 2016
V S S
10
4 Z TeV
11 Oct 2016
11
Adjust BLM Thresholds
• Idea: let’s use 2013 qualification loss maps to extrapolate BLM signals at quench;
• …but referring changes to 2016 BLM thresholds for proton operation;
• …but no quench due to ion collimation took place at 4 Z TeV:
• No measured beam power loss leading to quench;
• No clear target of beam power loss for scaling LMs;
• Let’s scale linearly (!!) what we know from 2015 quench test:
η6.5𝑍𝑇𝑒𝑉
Extrapolated beam power
𝑃𝐿𝑄,4𝑍𝑇𝑒𝑉 = 𝑃𝐿𝑄,6.5𝑍𝑇𝑒𝑉 × 𝐹𝑄𝐿 × 𝐹𝐸𝐷 ×
η4𝑍𝑇𝑒𝑉
loss at quench at 4 Z TeV:
11 Oct 2016
12
Adjust BLM Thresholds (II)
𝑃𝐿𝑄,4𝑍𝑇𝑒𝑉 = 𝑃𝐿𝑄,6.5𝑍𝑇𝑒𝑉 × 𝐹𝑄𝐿 × 𝐹𝐸𝐷 ×
η6.5𝑍𝑇𝑒𝑉
η4𝑍𝑇𝑒𝑉
FQL=1.5 from 6.5Z TeV to 4Z TeV (QP3
estimations as from BAuchmann – last
week: 1.63);
FED=1 (arbitrary, without strong indications
from simulations);
Case
h [x10-2]
PLM
[kW]
PLQ
[kW]
B1H
1.74
2.53
29.0
B1V
1.12
2.05
45.0
B2H
2.08
2.93
24.0
B2V
1.37
1.20
37.0
RS08
RS09
RS10
RS11
RS12
MQ.DOB MB.BFPP
1.993
2.221
1.867
2.144
1.652
1.761
1.475
1.506
1.475
1.492
MB.UFO
2.483
2.397
1.984
1.700
1.683
Take min values and stay conservative!
NB: PLM estimated with:
• calib: from RS12 and total intensity loss;
• PLM ~RS09/calib;
11 Oct 2016
13
Adjust BLM Thresholds (III)
The scaling at 4Z TeV shows that no threshold adjustment is actually required!
• Only two BLMs showed up:
• BLMQI.06R7.B1E10_MQTL (~22%);
• BLMQI.11R7.B1E10_MQ (~35%);
• Vaguely consistent with the fact that in 2013 no quench was induced…
(3.5Z TeV, 150kW in ~75ms…)  shall we then take care of IR7
collimators to restore dump hierarchy?
11 Oct 2016
14
Conclusions
• Presented first ideas on how to set BLM thresholds in IR7 for 2016 p-Pb run;
• 6.5 Z TeV:
• Let’s re-use the info available from ion collimation quench test (6.37 Z TeV);
• DS:
• Corrections for RS08 through RS12 estimated based on the B2H LM at
quench (the only one available);
• IR7 collimators:
• Let’s dump on collimators before dumping on cold BLMs in IR7 DS;
• Let’s modify MFs of (point-like modifications):
• H: TCLA.A7 to 0.09  limit to ~100kW proton losses;
• V: TCLA.C6 to 0.03  limit to ~30kW proton losses;
• 4 Z TeV:
• Let’s use the 2013 qualification loss maps;
• Let’s assume as max allowed power loss the 2015 quench power loss,
linearly scaled according to quench limit;
• No BLM requires corrections based on the extrapolations;
• It would be great to have a cross-check with qualification loss maps…
11 Oct 2016
15
Reserve Slides
11 Oct 2016
16
Collimator Settings
4Z TeV
6.5Z TeV
5.6
5.5
7.2
7.5
10.6
11
Rbruce, private
communication
Courtesy of PDHermes
11 Oct 2016
17