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What we may gain with the sorting at MEB
Presented by L. Bottura for the MEB
Session 4 - Magnetic Requirements for Commissioning
Divonnix, January 2006
Outline Our mission statement Sorting in practice: the MB’s
Macro-sorting Skimming/sifting the FQ Geometry classes
Examples SSS’s
Examples The other magnets (DS/MS/IR)
Examples Issues Conclusions and perspective
Mission statement If all magnets performed to (beam) specifications, we could install any
magnet anywhere In reality, we are faced with magnets performing worse, as, or better than
(production) specified, available as produced and requested as from installation schedule
Although a global sorting is out of the question, delays in the installation have provided an appropriate stock of magnets (e.g. in excess of 400 MB’s)
Mission: Find suitable slots for the available magnets that perform better than
specified, as specified or out-of-tolerance Preserve and (if possible) optimize the machine performance Include provisions to face day-to-day requirements (faults during
processing the magnets) Follow the planned installation schedule with a suitable flow of allocated
magnets
Slot allocation for MB’s 580 MB’s have been assigned
to a slot in the tunnel (nearly 1/2 of the LHC)
A stock of ≈ 250 magnets is available for macro- and local-sorting
Working mode was drastically modified at the end of 2004 to semi-automatic assignment by batches (see later) to match the demands of transport and installation teams
Semi-automatic assignment started as proposed by S. Fartoukh
Macro-sorting for MB’s Pre-select batches of 1 sector (154 MB’s + some 10…
20 spares) among the available stock(1) that have: The appropriate diode type (R/L) A 50/50 split between corrector packages (A/B) The same inner cable (01B and 01E show slight differences
in b1 at injection and initial ramp) Minimum b1 and b3 random (see next slides) An appropriate split among golden/silver/mid-cell geometry
(see next slides) Random mixing of
Manufacturer (Alstom/Ansaldo/BNN) Outer cable type (02B/02C/02D/02E/02G/02K)
NOTE: (1) CM and CR magnets. Magnets with delivery/completion date within few
weeks of allocation are also considered for pre-selection
Based on proposals from S. Fartoukh and E. Todesco
Xs1 Xs2 Xs3
Negative trend of b3 for Ansaldo magnetsand Alstom magnets with non-nominal shims
Initial production with non-nominal shims
Change of cross section
Skimming/sifting the FQ - 1/2 Production b3 1.9 units (vs. 1.4 units
target)
Courtesy of E. Todesco
Skimming/sifting the FQ - 2/2 Optimized choice can be used to select
batches with b3 1.0 … 1.6 units
Initial production with non-nominal shims and change of cross section
Mixing of cross-section 2 and 3
Inner cable 01E
mid-cellsilver silver
mid-cellsilver silver
Geometry classes - 1/3
In one sector: not more than 46 (23+23) MC at least 10 (5+5) G
Preferable (to allow sorting): At least 20 (10+10) G Not more than 20 (10+10) MC
Beam size
Based on a proposal from S. Fartoukh and J.B. Jeanneret
Geometry classes - 2/3
Geometry of as-built MB’s
More non-silver magnets than allowed A bit less golden magnets than desired
Distribution of classes in allocated sectors
Silver-right
Geometry classes - 3/3Silver-leftGolden-right
Golden-left
We can take advantage of the change of beam waist
in the cell !
OK !
Classes devised and defined by S. Fartoukh, J.B. Jeanneret and the WGA
Example: MB geometry The case of MB1148:
Assigned to DS slot (geometry-critical) LBBLQ.8L1 based on anticipated geometry
Unique type of interconnect (slot swapping not feasible)
Central foot blocked at cryostating (WP02), producing mid-cell geometry
Flanges out of tolerance (interconnect issue)
Foot at the limit of the adjustment range
Solution: installation shift x = 0.7 mm
r-parameter of MB1148 as built
r-parameter of MB1148 with installation shift
V1 V2
V1 V2
Courtesy of J.B. Jeanneret
Magnetic sorting Local sorting on TF, b3, a2 to:
Insure that the CO can be corrected with < 30 % of the corrector strength
Minimize the driving terms of 3rd order resonance Control the driving terms of of coupling resonance and vertical
dispersion Method:
No more than 3 MB’s with |b1| > 10 units in a raw
Form self-compensating sequences of MB’s to absorb |b1| > 15 units
Flip-flop pairing magnets with b3 above/below the <b3> Pairing at magnets with large or small b3 Flip-flop pairing at 2 magnets with a2 above/below the <a2>
Pairing at /2 magnets with a2 above/below the <a2>
Algorithm devised by S. Fartoukh, discussed at FQWG
Example: b1 local-sortingb1 distribution in sector 7-8 V1, MCBH strength at
7 TeV and residual CO error
Courtesy of S. Fartoukh
Gain: MCBH budget necessary for b1 correction limited to +/- 15 % of the available strength
XS2 and XS3 magnets XS1 BNN magnets
Example: b3 local-sorting
XS1 BNN magnetsXS3 magnets
-paired
flip-floppaired
b3 distribution in sector 7-8
Effect of flip-flop pairing
Effect of -pairing
Courtesy of S. Fartoukh
3rd order resonance driving terms
Gain: effective random b3 and driving terms reduced by a factor 3
SSS allocation SSS come in many different types, with reduced
sorting possibility Batch selection and qualification is performed in
advance to cold test Pairing at /2 magnets with b2 above/below the <b2> (or
pairing at 3/2, or flip-flop at , 2issue with D-beating)
110/362 SSS (nearly 1/3 of the main ring) allocated to date
Courtesy of M. Modena
SSS geometry
Specifications devised and defined by J.B. Jeanneret and WGA
The available aperture is tighter in the MQ’s, with no difference among cells
Specification based on D(H) quadrupoleg
r
SSS58
SSS58
The present situation requires care (see next slide) to avoid aperture loss at the level of 0.5 to 1 mm
Example: SSS geometry The case of SSS95:
Assigned to slot Q25R8 BPM support out-of-
tolerance by 0.25 mm (cannot be corrected)
Field angle 1.6 mrad (i.e.
a2 = 32 units) Solution
Installation shift and roll z=-0.1 mm, =-0.9 mrad Negligible aperture loss
(of the order of 50 m, not critical because the quadrupole is F)
V1 V2
V1 V2
r-parameter of SSS95 as built
r-parameter of SSS95 with installation shift and roll
Courtesy of E. Wildner, Y. Papaphilippou
Example: SSS b2 sorting
Courtesy of Y. Papaphilippou
b2 distribution in sector 7-8 as from warm measurements
Collars with permeability out of specification have
large apparent deviation from the production
average
Gain: total beta-beating kept well within (factor 2 to 3) the allocated budget
Total -beating (2 planes, 2 apertures)
The other magnets About 200 magnets:
DS/MS (Q4…Q11) and IR (Q1…Q3, D1…D4)
Correction dipoles for IP8,IP2 Discussed one-by-one, based on the
specific requirements of the proposed slot (e.g. SSS607 in Q5L8)
Allocated 6/114 DS/MS
quadrupoles (< 10 %) 4/4 cold D1 6/8 D2 (the remaining 2
are preallocated) 5/24 IR quadrupoles
(Q1/Q2 of IR8 R+L and Q3 or IR8 L)
3/6 warm compensation dipoles (IP8 spectrometer)
In addition MQW pre-sorted based
on b2 and geometry
Maximum operating Current: 3453 A
SSS607 training curve
Example: D1 geometry The case of D1 at right of
IP8 (D1L105) Pre-assignment based on field
quality and geometry inferred from measurements taken on the cold mass skin
Large deviations from straightness found in the cold bore
x=1.7 mm, z=2.7 mm Critical n1 = 5.7 at collision
vs. 7 target (with *=1 m) Solution:
Installation shift x=-0.6 mm Marginal n1 = 6.3 at
collision (with *=1 m, but this is an extreme case not used)
D1L105 horizontal geometry
D1L105 vertical geometry
Courtesy of M. Giovannozzi
Issues Replacement of magnets at
installation Risk: we may lose the
advantages of sorting MB batch selection, cold test
planning and fiducialisation Risk: reduced flexibility as the
production ends and the “sorting buffer” is depleted
SSS installation vs. production Work: meeting the installation
needs requires swift action (days)
Quads in the DS and MS Work: documentation,
automation, organization, as for MB’s and SSS’s
IR magnets, most critical elements in the machine at collision
Work: qualify cold D3/D4, Q1/Q2/Q3
Warm magnets Work: document, qualify,
sort and assign to slot
Assist the coordination work through anticipation
Cold test planning Pre-assignment of MQ’s in
the SSS Quench level in MQTL
correctors
Results and perspective - 1/2 So far we met our goals, and, when possible, we
did better… Maintaining the magnetic properties under control
(using sorting and compensation on field quality) Preserving the mechanical aperture (using sorting on
geometric classes and installation shifts/rolls) Negligible aperture loss in MQ’s, 0.1 mm (D) to 0.2 mm (F) MB’s in the shadow of MQ’s
Optimizing the installation sequence to gain margin (limiting the corrector strength, resonance driving terms)
Results and perspective - 2/2 … but we are only half way (at most)
IR, MS and DS are in front of us (and there is work to be done to specify aperture targets and qualify magnets)
Changes of transport/installation scenarios and needs result in pressure on magnet delivery, we are in the middle of this process. The situation will escalate during 2006
AcknowledgementsMembers Alternate Members
Luca Bottura (Chairman)
Massimo Giovannozzi (Scientific secretary, ABP – IR magnets (cold and warm), but low-beta quadrupoles)
Stephane Fartoukh (ABP - Magnet evaluation activity leader, ABP - MB) Massimo Giovannozzi
Yannis Papaphilippou (ABP - SSS) Jean Bernard Jeanneret
Frank Schmidt (ABP – Low-beta quadrupoles ) Stephane Fartoukh
Jean Bernard Jeanneret (Aperture)
Davide Tommasini (MB) Jose Carlo Pereira Lopes
Michele Modena (SSS) Theodor Tortschanoff
Nuria Catalan Lasheras (MS and DS SS) Ranko Ostojic
Ranko Ostojic (IR) Karl-Hubert Mess
Suitbert Ramberger (Resistive Magnets) Willi Kalbreier
Stephane Sanfilippo (Field Quality)
Elena Wildner (Geometry) Walter Scandale
Andrzej Siemko (Quench and Protection) Pierre Pugnat
Karl-Hubert Mess (Electrical Engineering) Ranko Ostojic
Dominique Missiaen (Survey) Patrick Winkes
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