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EDMS NO. REV. VALIDITY
0000000 0.1 DRAFT
REFERENCE
LHC-BPW-EC-0001
Date: 2018-07-26
Note: When approved, an Engineering Change Request becomes an Engineering Change Order.
This document is uncontrolled when printed. Check the EDMS to verify that this is the correct version before use.
CERN CH-1211 Geneva 23 Switzerland
LHC
ENGINEERING CHANGE REQUEST
Replacement of BQKs in IP4 by High
Bandwidth BPMs in IP4 for HL-LHC, and
Installation of a Prototype during LS2 BRIEF DESCRIPTION OF THE PROPOSED CHANGE(S):
New high bandwidth Beam Position Monitors will be required in IP4 for beam crabbing
observation post LS3. According to optics simulations, possible locations, i.e. with an
adequate phase advance to observe beam crabbing from IP1/5, have been identified
respectively close to Q5 and Q6 where the BQKs sit today. It is then proposed to replace
these long pick-ups (BQKs) by new high bandwidth monitors.
The installation of a prototype monitor is also foreseen during LS2 and will replace the
existing BQKH.L4.B1.
DOCUMENT PREPARED BY: DOCUMENT TO BE CHECKED BY: DOCUMENT TO BE APPROVED BY:
T. Levens (BE-BI)
T. Lefevre (BE-BI)
C. Adorisio, M. Barberan,
I. Bejar Alonso, M. Bernardini,
J. Blanc, G. Bregliozzi,
S. Bustamante, R. Calaga,
JP. Corso, S. Costa Machado,
R. De Maria, P. Fessia, R. Folch,
JF. Fuchs, C. Gaignant,
M. Giovannozzi, B. Holzer,
E. Jensen, R. Jones, M. Lamont,
Y. Muttoni, T. Otto, E. Page,
S. Redaelli, D. Ricci, G. Riddone,
R. Steerenberg, M. Tavlet,
R. Veness, J Wenninger,
M. Zerlauth
P. Collier
(on behalf of LMC)
L. Rossi
(on behalf of the HL-LHC project)
DOCUMENT SENT FOR INFORMATION TO:
ATS group leaders
SUMMARY OF THE ACTIONS TO BE UNDERTAKEN:
Space reservation for new pick-ups for crab cavity observation (installation foreseen during LS3)
Installation of new beam position monitor between Q5 on the left side of IP4 during LS2.
Pulling additional optical fibres will be required.
REFERENCE EDMS NO. REV. VALIDITY
LHC-BPW-EC-0001 0000000 0.1 DRAFT
Page 2 of 10
1. EXISTING SITUATION AND INTRODUCTION
The use of crab cavities in the HL-LHC era would require high-bandwidth beam position
monitors to measure the beam crabbing. Those monitors must have a fast time response
in the 20-50 ps range to be able to measure the intra-bunch beam position. They would
also need to be located at a position with a phase advance as close as possible to 90
degrees with respect to the position of the crab cavities in IP1/5 (or 0 degree with
respect to IPs). In order to observe beam crabbing from both beams in H and V, we
would need 4 new pick-ups to be installed in LSS4 during LS3.
A prototype of such a pick-up is proposed to be installed during LS2, replacing the
BQKH.L4.B1.
Identifier 11599 (re-opened after the closure of the initial request 10627) in the PLAN
tool references this activity.
2. REASON FOR THE CHANGE
The current head-tail monitors, installed on BPLH.6R4.B2 and BPLV.6R4.B1 beside Q5R
and BPLH.7R4.B1 and BPLV.7R4.B2 beside Q6R, can already reach a time resolution
close to what is required for crab cavity monitoring. However, they are not installed at
a location with an optimised phase advance. Based on beam optic simulation for HL-
LHC, a total of 4 monitors will be needed to be able to measure beam crabbing from
IP1/5 in both the horizontal and vertical planes. We propose for HL-LHC to replace the
existing BQKs, which are located at those positions today and have never been used
operationally, by new pick-ups capable of providing the best possible time resolution for
crab cavity diagnostics. A prototype is proposed to be installed during LS2 as a
replacement of the BQKH.L4.B1.
3. DETAILED DESCRIPTION
The phase advances in Q5 and Q6 at IP4 with respect to IP1/5 have been simulated for
the case of HL-LHC and are shown in Figure 1.
Figure 1 — Optics simulation showing the phase advance in H and V with respect to IP1/5 for both
beams in the case of Hl-LHC baseline optic scenario.+
REFERENCE EDMS NO. REV. VALIDITY
LHC-BPW-EC-0001 0000000 0.1 DRAFT
Page 3 of 10
As an indication extracted from Figure 1, we present in Table 1, a figure of merit of the
sensitivity of a pick-up located at the close vicinity of Q5 and Q6 to beam crabbing in
IP1/5 in both the horizontal and vertical planes. ‘Green’ means a phase advance close
to 0 degree, thus capable to measure beam crabbing with a good sensitivity. ‘Orange’
represents phase advances of 25-50 degrees, which are not fully optimized to measure
beam crabbing. And ‘Red’ is corresponding to phase advances close to 90 degrees which
are unsensitive to beam crabbing.
Table 1 — Phase advance for IP1/5 in the Horizontal and Vertical planes
Q5 Q6
IP1Y B1 BQKV.L4 – B1 BQKH.L4 – B1
IP1Y B2 BQKH.R4 – B2 BQKV.R4 – B2
IP5X B1 BQKV.L4 – B1 BQKH.L4 – B1
IP5X B2 BQKH.R4 – B2 BQKV.R4 – B2
IP1X B1 BQKV.L4 – B1 BQKH.L4 – B1
IP1X B2 BQKH.R4 – B2 BQKV.R4 – B2
IP5Y B1 BQKV.L4 – B1 BQKH.L4 – B1
IP5Y B2 BQKH.R4 – B2 BQKV.R4 – B2
In Table 1, we also indicate the name of existing stripline pick-ups, named BQKs,
installed close to Q5 and Q6 respectively on the left and on the right sides of IP4. These
pick-ups can be found in
Figure 2 andFigure 3 in the current machine layout on the left and the right side of IP4
respectively.
REFERENCE EDMS NO. REV. VALIDITY
LHC-BPW-EC-0001 0000000 0.1 DRAFT
Page 4 of 10
Figure 2 — Current LHC layout in IP4 left.
Figure 3 — Current LHC layout in IP4 right.
REFERENCE EDMS NO. REV. VALIDITY
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Page 5 of 10
One should note that all existing BKQs have cables, 2x 7/8” coaxial cables and 1x 26-
pin control cable, that will be reuse for signal acquisition and control. They are currently
coming from the pick-up to the racks BY06=UA47 and BY11-UA43 respectively on the
right and left side of IP4.
For HL-LHC, we propose to replace those BQKs with dual plane high-bandwidth pick-ups
for crab-cavity diagnostics. The new layouts in IP4 for HL-LHC, where the BQKs have
been replaced by space reservation zones, are shown on Figure 4 and Figure 5 for the
left of right sides of IP4 respectively.
Figure 4 — HL-LHC layout in IP4 left.
REFERENCE EDMS NO. REV. VALIDITY
LHC-BPW-EC-0001 0000000 0.1 DRAFT
Page 6 of 10
Figure 5 — HL-LHC layout in IP4 right.
During LS2, we propose to replace the BQKH.L4.B1 by a high bandwidth BPM prototype.
The design of this pick-up is under study at the moment such that we cannot provide
more detail on its integration. However, the installation will be made such that the
BQKH.L4.B1 will be replaced one to one by the new monitor and its mechanical support
will reuse the existing support of the current stripline.
This new pick-up is based on the use of fibre laser and would require the pulling of new
fibres (4 polarisation maintaining fibres and 4 single mode fibres). The existing cables
will be reused for signal acquisition and control. The laser system and the optical
detection system will be rack-mounted in BY11=UA43.
4. IMPACT ON OTHER ITEMS
4.1 IMPACT ON ITEMS/SYSTEMS
BQKH.L4.B1 New pick-up with a modified support
4.2 IMPACT ON UTILITIES AND SERVICES
Raw water: no
Demineralized water: no
REFERENCE EDMS NO. REV. VALIDITY
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Page 7 of 10
Compressed air: no
Electricity, cable pulling (power, signal, optical fibres…):
Special Optical fibres (polarisation maintaining fibre) to be pulled
DEC/DIC: DIF to be done
Racks (name and location):
BY11=UA43
Vacuum (bake outs, sectorisation…):
Bake-out
Special transport/ handling:
no
Temporary storage of conventional/radioactive components:
no
Alignment and positioning:
Pick-up to be aligned using classical survey target
Scaffolding: no
Controls: no
GSM/WIFI networks: no
Cryogenics: no
Contractor(s): no
Surface building(s): no
Others: no
5. IMPACT ON COST, SCHEDULE AND PERFORMANCE
5.1 IMPACT ON COST
Detailed breakdown of the change cost:
Fiber (40kCHF) Pick-up (10kCHF) Optic(20kCHF)
Budget code: 64065
5.2 IMPACT ON SCHEDULE
Proposed installation schedule:
LS2 (Q2/Q3 2020)
Proposed test schedule (if applicable):
no
REFERENCE EDMS NO. REV. VALIDITY
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Page 8 of 10
Estimated duration: 3 weeks
Urgency: no
Flexibility of scheduling: yes
5.3 IMPACT ON PERFORMANCE
Mechanical aperture: Same as today
Impedance: Should be better as we removed a long stripline replacing by a short button pick-up
Optics/MADX no
Electron cloud (NEG coating, solenoid…)
no
Insulation (enamelled flange, grounding…)
no
Vacuum performance: no
Others: no
6. IMPACT ON OPERATIONAL SAFETY
6.1 ÉLÉMENT(S) IMPORTANT(S) DE SECURITÉ
Requirement Yes No Comments
EIS-Access no
EIS-Beam no
EIS-Machine no
6.2 OTHER OPERATIONAL SAFETY ASPECTS
Have new hazards been created or changed?
Yes, using fibre laser – Safety file to be done when the system is fully designed
Could the change affect existing risk control measures?
Yes, using fibre laser – Safety file to be done when the system is fully designed
What risk controls have to be put in place?
Laser protection and signs to be put in place around the pick-up and in the rack in the gallery
Safety documentation to
update after the modification
yes
REFERENCE EDMS NO. REV. VALIDITY
LHC-BPW-EC-0001 0000000 0.1 DRAFT
Page 9 of 10
Define the need for training or information after the change
no
7. WORKSITE SAFETY
7.1 ORGANISATION
Requirement Yes No Comments
IMPACT – VIC: x To be done
Operational radiation protection (surveys, DIMR…):
x
Radioactive storage of material:
x The BQKH.L4.B1 will be removed from the machine and stored
Radioactive waste: x
Non-radioactive waste: x
Fire risk/permit (IS41) (welding, grinding…):
x
Alarms
deactivation/activation (IS37):
x
Others: x
7.2 REGULATORY TESTS
Requirement Yes No Responsible Group
Comments
Pressure/leak tests: x TE-VSC
Electrical tests: x BE-BI
Others: x
7.3 PARTICULAR RISKS
Requirement Yes No Comments
Hazardous substances (chemicals, gas, asbestos…):
x
Work at height: x
Confined space working: x
REFERENCE EDMS NO. REV. VALIDITY
LHC-BPW-EC-0001 0000000 0.1 DRAFT
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Noise: x
Cryogenic risks: x
Industrial X-ray (tirs radio):
x
Ionizing radiation risks (radioactive components):
x [Traceability by TREC.]
Others: x Fibre laser
8. FOLLOW-UP OF ACTIONS BY THE TECHNICAL COORDINATION
Action Done Date Comments
Carry out site activities:
Carry out tests:
Update layout drawings:
Update equipment drawings:
Update layout database:
Update naming database:
Update optics (MADX)
Update procedures for maintenance and operations
Update Safety File according to
EDMS document 1177755: