Beam Delivery System and Interaction Region of

a Linear Collider

Beam Delivery System and Interaction Region of

a Linear ColliderNikolai Mokhov, Mauro Pivi, Andrei SeryiNikolai Mokhov, Mauro Pivi, Andrei Seryi

The US Particle Accelerator SchoolJanuary 15-26, 2007 in Houston, Texas

2

LectureRECENT DESIGN

DEVELOPMENTS

3

Evolution of ILC BDS design in 2006

20mr IR

2mr IR

FF

E-collim.-collim.

DiagnosticsBSYtune-up dump

Two collider halls separated longitudinally by 138m

14mr IR

14mr IR

One collider hall

Vancouver baseline

Valencia baseline

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14(20)mrad IR

BNL, B.Parker, et al

5BNL, B.Parker, et al

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FD14 design

Sizes optimized for detector opening

Feedback kicker area

Interface region being optimized with forward detector region

BNL

Focus on 14mr design to push technology

Size and interface of shared cryostat being optimized with detector

Feedback area being designed

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QD0SD0 QF1

SF1 Q,S,QEXF1

Disrupted beam & Sync radiations

BeamstrahlungIncoming beam

60 m

Shared Large Aperture Magnets

Rutherford cable SC quad and sextupole

pocket coil quad

2mrad IR

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100W/m hands-on limit

Losses are mostly due to SR. Beam loss is very small

100W/m

Losses are due to SR and beam lossJ. Carter, I. Agapov, G.A. Blair, L. Deacon (JAI/RHUL), A.I. Drozhdin, N.V. Mokhov (Fermilab), Y.M. Nosochkov, A.A. Seryi (SLAC)

20mrad

2mrad

Losses in extraction

line20mr: losses < 100W/m at 500GeV CM and 1TeV CM

2mr: losses are at 100W/m level for 500GeV CM and exceed this level at 1TeV

Radiation conditions and shielding to be studied

250GeV Nominal, 0nm offset

45.8kW integr. loss

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Physics Benchmarks for the ILC Detectors, hep-ex/0603010, M. Battaglia, T. Barklow, M. E. Peskin, Y. Okada, S. Yamashita, P. Zerwas

Benchmarks for evaluation of ILC detectors

Reaction which cares most about crossing angle is

Detection is challenged by copious

which require low angle tagging.

Tagging is challenged by background from pairs and presence of exit hole

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Study of SUSY reach

• SUSY reach is challenged for the large crossing angle when m (slepton-neutralino) is small

• Studies presented at Bangalore (V.Drugakov) show that for 20mrad+DID (effectively ~40mrad for outgoing pairs), due to larger pairs background, one cannot detect SUSY dark matter if m=5GeV

• The cases of 20 or 14mrad with anti-DID have same pairs background as 2mrad. Presence of exit hole affects detection efficiency slightly. The SUSY discovery reach may be very similar in these configurations

• Several groups are studying the SUSY reach, results may be available after Vancouver

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Backscattering of SR

FD produce SR and part will hit BYCHICMB surfaceTotal Power = 2.5 kW<E>=11MeV (for 250GeV/beam)

Takashi MaruyamaFrom BYCHICB

Rate #s at IP/BX

#s in SiTracker from pairs

250 GeV 1.1x10-8 2200 700

500 GeV 2.9x10-8 11700 1900

Photon flux within 2 cm BeamCal aperture:

SR from 250 GeV disrupted beam,

GEANT

Flux is 3-6 times larger than from pairs. More studies & optimization needed

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Ken Moffeit, Takashi Maruyama, Yuri Nosochkov, Andrei Seryi, Mike Woods (SLAC), William P. Oliver (Tufts University), Eric Torrence (Univ. of Oregon)

GEANT tracking in extraction lines

Study achievable precision of polarization and energy measurements, background & signal/noise, requirements for laser, etc.

Compton Detector Plane20mrad 2mrad

Downstream diagnostics evaluation (1)

Compton IP

(cm)

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Downstream diagnostics evaluation (2)

Comparisons for 250GeV/beam 20mr 2mr

Beam overlap with 100mm laser spot at Compton IP

48% 15%

Polarization projection at Compton IP 99.85% 99.85%

Beam loss form IP to Compton IP <1E-7 >2.6E-4

Beam SR energy loss from IP to middle of energy chicane

119MeV 854MeV

Variation of SR energy loss due to 200nm X offset at IP

< 5MeV( < 20 ppm)

25.7MeV(~100 ppm)

The need for SR collimator at the Cherenkov detector

yes No

comparable with the goal for E precision measurements

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Brainstorm to design magnets in 2mrad extraction

Some magnet sizes on this drawing are tentative

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Recent suggestions

Brainstorm for 2mrad magnets

B1

beamstrahlung

> 2

m

Vladimir Kashikhin , Brett Parker, John Tompkins, Cherrill Spencer, Masayuki Kumada, Koji Takano, Yoshihisa Iwashita, Eduard Bondarchuk, Ryuhei Sugahara

BHEX1

Power @ 1TeV CM is 635-952 KW/magnet. Pulsed may be feasible?

Power @ 1TeV CM is 1MW/magnet. Temperature rise is very high. Use of HTS? Pulsed? Further feasibility study and design optimization are needed

QEX3

QEX5

should have 6-60GS field!

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Magnets

• Things to care: – needed aperture, L– strength, field quality,

stability– losses of beam or SR in the area

• E.g., extraction line => need aperture r~0.2m and have beam losses => need warm magnets which may consume many MW => may cause to look to new hybrid solutions, such as high T SC magnets

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Magnet current (Amp*turn) per coil

and total powerI(A)=B(Gs)*h(cm)*10/(4) P(W)=2*I(A)*j(A/m2)*(*m)*l(m)

I(A)=1/2*B(Gs)*h(cm)*10/(4)

P(W)=4*I(A)*j(A/m2)*(*m)*l(m)

I(A)=1/3*B(Gs)*h(cm)*10/(4)

P(W)=6*I(A)*j(A/m2)*(*m)*l(m)

For dipole h is half gap. For quad and sextupole h is aperture radius, and B is pole tip field. Typical bends may have B up to 18kGs, quads up to 10kGs. Length of turn l is approximately twice the magnet length. For copper ~2*10-8 *m.For water cooled magnets the conductor area chosen so that current density j is in the range 4 to 10 A/mm2

Bend

Quad

Sextupole

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Drivers of the cost and cost

• Cost drivers– CF&S– Magnet system– Vacuum system– Installation– Dumps & Colls.

• Drivers of splits between 20/2:– CF&S– Magnet system– Vacuum system– Dumps &

collimators– Installation; Controls

Total Cost

Additional costs for IR20 and IR2

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from MDI panel statement

• The physics mode most affected by crossing angle is the slepton pair production where the slepton-LSP m is small. The main background is 2- processes and an efficient low-angle electron tag by BEAMCAL is needed to veto them.

• Difference in expected background (is due to) different levels of veto efficiency. Signal to noise will be ~4 to 1 with 2mrad crossing angle.

• For a large crossing angle (14 or 20mrad), anti-DID is needed to collimate the pair background along the outgoing beam. For 14mrad crossing with anti-DID, the … background is expected to be comparable to the 2mrad case while the signal efficiency reduces by about 30% to 40%. This is mainly due to the 2nd hole of BEAMCAL that is needed for the large crossing angle which will force additional cuts to remove the 2-photon and other backgrounds.

• for 20mrad crossing with anti-DID was found to be essentially the same as the 2mrad case.

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Valencia 14/14 baseline. Conceptual CFS layout

IP2

IP1

10m

1km

beam dump service hallalcoves

9m shaft for BDS access

polarimeter laser borehole

muon wall tunnel widening

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CFS designs for two IRs

Valencia

Vancouver

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beam dump service hall

alcoves

9m shaft for BDS access & service hall

beam dump and its shield

muon wall tunnel widening

Beam Delivery System tunnels

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CMS assembly approach• Assembled on the surface in parallel with underground work• Allows pre-commissioning before lowering• Lowering using dedicated heavy lifting equipment• Potential for big time saving• Reduces size of required underground hall

On-surface assembly : CMS approach

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BDS with single IR

14mr IR

FF

E-collimator

-collim.

Diagnostics

Tune-up dump

BSY

Sacrificial collimators

Extraction

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polarimeterskew correction /emittance diagnostic

MPScoll

betatroncollimation

fastsweepers

tuneupdump

septa

fastkickers

energycollimation

betamatch

energyspectrometer

finaltransformer

finaldoublet

IP

energyspectrometer

polarimeter

fastsweepers

primarydump

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QFSM1moves~0.5 m

polarimeterchicane

septafastkickers

“Type B” (×4)

500GeV => 1TeV CM upgrade in BSY of 2006e

M. Woodley et al

Magnets and kickers are added in energy upgrade

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Single IR BDS optics (2006e)

FF

E-c

ollim

ator

-collim.Diagnostics

BSY

Pol

arim

eter

E-s

pect

rom

eter

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warm

Detector

IP

common stationary cryostat

QD0QF1

vacuum connection & feedback kicker

Concept of single IR Final Doublet

Redesigned FDOriginal FD and redesigned for push-pull (BNL)

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cancellation of the external field with a shield coil has been successfully demonstrated at BNL

BNL prototype of self shielded quad

IR magnets

BNL prototype of sextupole-octupole magnet

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• Rearranged extraction quads are shown. Optics performance is very similar.

• Both the incoming FD and extraction quads are optimized for 500GeV CM.

• In 1TeV upgrade would replace (as was always planned) the entire FD with in- and outgoing magnets. In this upgrade, the location of break-point may slightly move out. (The considered hall width is sufficient to accommodate this).

http://ilcagenda.cern.ch/conferenceDisplay.py?confId=1187

Nominal scheme

Push-pull scheme

New optics for extraction FD : push pull compatible

B.Parker, Y.Nosochkov et al.

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Extraction Lines : shortened by 100m

high L parameters(500 GeV CM)

For undisrupted beam reliance on beam sweeping on beam dump window using kickers.

Total loss before and at collimators for High L parameters is within acceptable levels. Losses for the nominal case are negligible.

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detectorB

may be accessible during run

accessible during run Platform for electronic and

services (~10*8*8m). Shielded (~0.5m of concrete) from five sides. Moves with detector. Also provide vibration isolation.

Concept of single IR with two detectors

The concept is evolving and details being worked out

detectorA

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Detector systems connections

fixed connections

long flexible connections

detectordetector service platform or mounted on detector

high V AC

high P room T Hesupply & return

chilled water for electronics

low V DC forelectronics

4K LHe for solenoids

2K LHe for FD

high I DC forsolenoids

high I DC for FD

gas for TPCfiber data I/O

electronics I/O

low V PShigh I PSelectronic racks4K cryo-system2K cryo-systemgas system

sub-detectorssolenoidantisolenoidFD

move together

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QD0 part QF1 part

doorcentral part

Optimized for fast switch of detectors in push-pull and fast opening on beamline

This scheme require lengthening L* to 4.5m and increase of the inner FD drift

Opening of detectors on the beamline (for quick fixes) may need to be limited to a smaller opening than what could be done in off-beamline position

Push-pull cryo configuration

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IR & rad. safety

• For 36MW MCI, the concrete wall at 10m from beamline should be ~3.1m

18MW loss on Cu target 9r.l \at s=-8m. No Pacman, no detector. Concrete wall at 10m.Dose rate in mrem/hr.

Wall

25 rem/hr10m

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Self-shielding detector

18MW on Cu target 9r.l at s=-8mPacman 1.2m iron and 2.5m concrete

dose at pacman external wall dose at r=7m 0.65rem/hr (r=4.7m) 0.23rem/hr

Detector itself is well shielded except for incoming beamlines

A proper “pacman” can shield the incoming beamlines and remove the need for shielding wall

18MW lost at s=-8m. Packman has Fe: 1.2m, Concrete: 2.5m

38250mSv/h

Shielding the IR hall

Self-shielding of GLD Shielding the “4th“ with walls

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Working progress on IR design…

John Amann

3m Thickness

9m Base25m Height

Structural Rib

Overlapping Rib

Illustration of ongoing work… Designs are tentative & evolving

Mobile Shield Wall

Mobile Platform20m x 30m

Electronics/Cryo Shack1m Shielded

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Working progress on IR design…

Illustration of ongoing work… Designs are tentative & evolving

John Amann

Recessed Niche

Pac Man Open

Pac Man Closed

Beam Line Support Here

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Working progress on IR design…

Looking into experience of existing machines…

CMS shield opened

pacman closed

pacman openSLD pacman closed door tunnel pacman opened

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UA2, CERN

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Air-pads at CMS

Photo from the talk by Y.Sugimoto, http://ilcphys.kek.jp/meeting/lcdds/archives/2006-10-03/

Single air-pad capacity ~385tons (for the first end-cap disk which weighs 1400 tons). Each of air-pads equipped with hydraulic jack for fine adjustment in height, also allowing exchange of air pad if needed. Lift is ~8mm for 385t units. Cracks in the floor should be avoided, to prevent damage of the floor by compressed air (up to 50bars) – use steel plates (4cm thick). Inclination of ~1% of LHC hall floor is not a problem. Last 10cm of motion in CMS is performed on grease pads to avoid any vertical movements. [Alain Herve, et al.]

14kton ILC detector would require ~36 such air-pads

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Displacement, modeling

Starting from idealized case: -- elastic half-space (Matlab model) -- simplified ANSYS model (size of modeled slab limited by memory)

Short range deformation (~0.1mm) is very similar in both models. Long range (1/r) deformation (~0.3mm) is not seen in ANSYS because too thin slab in the model

More details (3d shape of the hall, steel plates on the floor, etc.) to be included.

Long term settlement, inelastic motion, etc., are to be considered. Parameters: M=14000 ton; R=0.75m (radius of air-pad); E=3e9 kg/m^2, n=0.15 (as for concrete); Number of air-pads=36

J.Amann, http://ilcagenda.cern.ch/conferenceDisplay.py?confId=1225

Matlab model, half-space

ANSYS model

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Schedule for the design goal time (a.u.)

• The hardware can be designed to be compatible with a ~one day move, and this can be a design goal– Need to study cost and reliability versus the move duration – Need to study regulations in each regions

• Recalibration (at Z) may or may not be needed, and may be independent on push-pull – to be studied

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CFS layout for single IR & central DR

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CFS layout for single IR

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x

x

RF kick

Crab crossing

2 2 2,

20mr 100μm 2μm

x projected x c z

c z

factor 10 reduction in L!

use transverse (crab) RF cavity to ‘tilt’ the bunch at IP

49

Crab cavity requirements

IP

~0.12m/cell ~15m

Crab Cavity

Slide from G. Burt & P. Goudket

Use a particular horizontal dipole mode which gives a phase-dependant transverse momentum kick to the beam

Actually, need one or two multi-cell cavity

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TM110 Dipole mode cavity

View from top

Beam

Magnetic fieldin green

Electric Fieldin red

For a crab cavity the bunch centre is at the cell centre when E is maximum and B is zero

51

Crab cavities

• Top: earlier prototype of 3.9GHz deflecting (crab) cavity designed and build by Fermilab. This cavity did not have all the needed high and low order mode couplers. • Bottom: Cavity modeled in Omega3P, to optimize design of the LOM, HOM and input couplers.FNAL T. Khabibouline et al., SLAC K.Ko et al.Design is being continued by UK-US team

3.9GHz cavity achieved 7.5 MV/m

• BDS has two SC 9-cell cavities located ~13 m upstream of the IP operated at 5MV/m peak deflection. • Based on a Fermilab design for a 3.9GHz TM110 mode 13-cell cavity. • The uncorrelated phase jitter between the positron and electron crab cavities must be controlled to 61 fsec to maintain optimized collisions. • A proof-of-principle test of a 7 cell 1.5GHz cavity at the JLab ERL facility has achieved a 37 fsec level of control. • Other key issues to be addressed are LLRF control and higher-order mode damping.

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Beam dump for 18MW beam

• Water vortex• Window, 1mm thin, ~30cm

diameter hemisphere• Raster beam with dipole

coils to avoid water boiling• Deal with H, O, catalytic

recombination• etc.

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IR coupling compensation

When detector solenoid overlaps QD0, coupling between y & x’ and y & E causes large (30 – 190 times) increase of IP size (green=detector solenoid OFF, red=ON)

Even though traditional use of skew quads could reduce the effect, the local compensation of the fringe field (with a little skew tuning) is the most efficient way to ensure correction over wide range of beam energies

without compensation y/ y(0)=32

with compensation by antisolenoid

y/ y(0)<1.01

QD0

antisolenoid

SD0

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Antisolenoids

Antisolenoids (needed for both IRs to compensate solenoid coupling locally) with High Temperature Superconductor coils

BNL, P.Parker et al.

55

Preliminary Design of Anti-solenoid for SiD

456mm

316mm

70mm cryostat

1.7m long

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0 2 4 6 8 10

15T Force

Four 24cm individual powered 6mm coils, 1.22m total length, rmin=19cm

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Detector Integrated Dipole

• With a crossing angle, when beams cross solenoid field, vertical orbit arise

• For e+e- the orbit is anti-symmetrical and beams still collide head-on

• If the vertical angle is undesirable (to preserve spin orientation or the e-e- luminosity), it can be compensated locally with DID

• Alternatively, negative polarity of DID may be useful to reduce angular spread of beam-beam pairs (anti-DID)

57

Use of DID or

anti-DID

Orbit in 5T SiD

SiD IP angle zeroed w.DID

DID field shape and scheme DID case

anti-DID case

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ATF and ATF2

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ATF2 goals(A) Small beam size

Obtain y ~ 35nmMaintain for long time

(B) Stabilization of beam center Down to < 2nm by nano-BPM Bunch-to-bunch feedback of ILC-like

train

ATF2

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ATF2 optics

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Advanced beam instrumentation at ATF2

• BSM to confirm 35nm beam size• nano-BPM at IP to see the nm stability• Laser-wire to tune the beam• Cavity BPMs to measure the orbit• Movers, active stabilization, alignment system• Intratrain feedback, Kickers to produce ILC-like

train

IP Beam-size monitor (BSM)(Tokyo U./KEK, SLAC, UK)

Laser-wire beam-size Monitor (UK group)

Cavity BPMs, for use with Q magnets with 100nm resolution (PAL, SLAC, KEK)

Cavity BPMs with 2nm resolution, for use at the IP (KEK)

Laser wire at ATF

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ATF2 schedule

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ATF ring

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ATF hall