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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