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Beam Delivery System and Interaction Region of a Linear Collider Nikolai Mokhov, Mauro Pivi, Andrei Seryi The US Particle Accelerator School January 15-26, 2007 in Houston, Texas Lecture RECENT DESIGN DEVELOPMENTS Evolution of ILC BDS design in 2006 Vancouver baseline Diagnostics BSY

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beam delivery system and interaction region of a linear collider

Beam Delivery System and Interaction Region of a Linear Collider

Nikolai Mokhov, Mauro Pivi, Andrei Seryi

The US Particle Accelerator School

January 15-26, 2007 in Houston, Texas

evolution of ilc bds design in 2006
Evolution of ILC BDS design in 2006

Vancouver baseline

Diagnostics

BSY

tune-up dump

2mr IR

b-collim.

E-collim.

20mr IR

Two collider halls separated longitudinally by 138m

FF

Valencia baseline

14mr IR

14mr IR

One collider hall

slide4

14(20)mrad IR

BNL, B.Parker, et al

fd14 design
FD14 design

Interface region being optimized with forward detector region

Sizes optimized for detector opening

BNL

Feedback kicker area

Focus on 14mr design to push technologySize and interface of shared cryostat being optimized with detectorFeedback area being designed

slide7

2mrad IR

Shared Large Aperture Magnets

Disrupted beam & Sync radiations

Q,S,QEXF1

SF1

QF1

SD0

QD0

60 m

Beamstrahlung

Incoming beam

pocket coil quad

Rutherford cable SC quad and sextupole

losses in extraction line
Losses in extraction line

100W/m hands-on limit

20mrad

20mr: losses < 100W/m at 500GeV CM and 1TeV CM2mr: losses are at 100W/m level for 500GeV CM and exceed this level at 1TeVRadiation conditions and shielding to be studied

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

2mrad

250GeV Nominal, 0nm offset

100W/m

45.8kW integr. loss

Losses are due to SR and beam loss

J. Carter, I. Agapov, G.A. Blair, L. Deacon (JAI/RHUL), A.I. Drozhdin, N.V. Mokhov (Fermilab), Y.M. Nosochkov, A.A. Seryi (SLAC)

benchmarks for evaluation of ilc detectors
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

Physics Benchmarks for the ILC Detectors, hep-ex/0603010,

M. Battaglia, T. Barklow, M. E. Peskin, Y. Okada, S. Yamashita, P. Zerwas

study of susy reach
Study of SUSY reach
  • SUSY reach is challenged for the large crossing angle when Dm (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 Dm=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
backscattering of sr
Backscattering of SR

Photon flux within 2 cm BeamCal aperture:

Flux is 3-6 times larger than from pairs.

More studies & optimization needed

SR from 250 GeV disrupted beam, GEANT

FD produce SR and part will

hit BYCHICMB surface

Total Power = 2.5 kW

<Eg>=11MeV (for 250GeV/beam)

From BYCHICB

Takashi Maruyama

downstream diagnostics evaluation 1
Downstream diagnostics evaluation (1)

Compton IP

(cm)

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

GEANT tracking in extraction lines

Compton Detector Plane

20mrad 2mrad

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

downstream diagnostics evaluation 2
Downstream diagnostics evaluation (2)

comparable with the goal for E precision measurements

brainstorm to design magnets in 2mrad extraction
Brainstorm to design magnets in 2mrad extraction

Some magnet sizes on this drawing are tentative

brainstorm for 2mrad magnets
Brainstorm for 2mrad magnets

BHEX1

Recent suggestions

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

QEX5

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

should have 6-60GS field!

B1

> 2m

beamstrahlung

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

QEX3

magnets
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
magnet current amp turn per coil and total power
Magnet current (Amp*turn) per coil and total power

Bend

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

P(W)=2*I(A)*j(A/m2)*r(W*m)*l(m)

Quad

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

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

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

Sextupole

P(W)=6*I(A)*j(A/m2)*r(W*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 r~2*10-8W*m.

For water cooled magnets the conductor area chosen so that current density j is in the range 4 to 10 A/mm2

slide18

Drivers of the cost and Dcost

Total 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

Additional costs for IR20 and IR2

from mdi panel statement
from MDI panel statement
  • The physics mode most affected by crossing angle is the slepton pair production where the slepton-LSP Dm is small. The main background is 2-g 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.
valencia 14 14 baseline conceptual cfs layout
Valencia 14/14 baseline. Conceptual CFS layout

muon wall tunnel widening

polarimeter laser borehole

9m shaft for BDS access

IP2

10m

IP1

beam dump service hall

alcoves

1km

slide21

CFS designs for two IRs

Vancouver

Valencia

beam delivery system tunnels
Beam Delivery System tunnels

9m shaft for BDS access & service hall

muon wall tunnel widening

alcoves

beam dump service hall

beam dump and its shield

slide23

On-surface assembly : CMS approach

  • 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
bds with single ir
BDS with single IR

BSY

Sacrificial

collimators

b-collim.

E-collimator

Diagnostics

FF

14mr IR

Tune-up dump

Extraction

slide26

betatron

collimation

septa

MPS

coll

skew correction /

emittance diagnostic

polarimeter

fast

kickers

fast

sweepers

tuneup

dump

beta

match

final

transformer

polarimeter

energy

collimation

IP

primary

dump

energy

spectrometer

fast

sweepers

energy

spectrometer

final

doublet

slide27

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

“Type B” (×4)

fast

kickers

septa

polarimeter

chicane

QFSM1

moves

~0.5 m

Magnets and kickers are added in energy upgrade

M. Woodley et al

single ir bds optics 2006e
Single IR BDS optics (2006e)

BSY

FF

Polarimeter

E-spectrometer

E-collimator

b-collim.

Diagnostics

concept of single ir final doublet
Concept of single IR Final Doublet

vacuum connection & feedback kicker

common stationary

cryostat

Detector

QD0

QF1

warm

IP

Original FD and redesigned for push-pull (BNL)

Redesigned FD

ir magnets
IR magnets

BNL prototype of sextupole-octupole magnet

BNL prototype of self shielded quad

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

new optics for extraction fd push pull compatible
New optics for extraction FD : push pull compatible
  • 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).

Nominal scheme

Push-pull scheme

B.Parker, Y.Nosochkov et al.

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

extraction lines shortened by 100m
Extraction Lines : shortened by 100m

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

high L parameters

(500 GeV CM)

Total loss before and at collimators for High L parameters is within acceptable levels.

Losses for the nominal case are negligible.

concept of single ir with two detectors
Concept of single IR with two detectors

detector

B

The concept is evolving and details being worked out

may be accessible during run

detector

A

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.

detector systems connections
Detector systems connections

detector service platform or mounted on detector

detector

low V DC for

electronics

high V AC

4K LHe for solenoids

low V PS

high I PS

electronic racks

4K cryo-system

2K cryo-system

gas system

2K LHe for FD

high P room T He

supply & return

sub-detectors

solenoid

antisolenoid

FD

high I DC for

solenoids

chilled water

for electronics

high I DC for FD

gas for TPC

fiber data I/O

electronics I/O

fixed connections

long flexible connections

move together

push pull cryo configuration
Push-pull cryo configuration

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

QD0 part

QF1 part

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

door

central part

slide36

Wall

25 rem/hr

IR & rad. safety

18MW loss on Cu target 9r.l \at s=-8m.

No Pacman, no detector. Concrete wall at 10m.

Dose rate in mrem/hr.

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

10m

slide37

Self-shielding detector

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 on Cu target 9r.l at s=-8m

Pacman 1.2m iron and 2.5m concrete

18MW lost at s=-8m.

Packman has Fe: 1.2m, Concrete: 2.5m

dose at pacman external wall dose at r=7m

0.65rem/hr (r=4.7m) 0.23rem/hr

shielding the ir hall
Shielding the IR hall

250mSv/h

Self-shielding of GLD

Shielding the “4th“ with walls

working progress on ir design
Working progress on IR design…

Mobile Shield Wall

Illustration of ongoing work… Designs are tentative & evolving

Structural Rib

3m Thickness

Overlapping

Rib

Mobile Platform

20m x 30m

Electronics/Cryo Shack

1m Shielded

25m Height

9m Base

John Amann

slide40

Working progress on IR design…

Pac Man Open

Illustration of ongoing work… Designs are tentative & evolving

Recessed Niche

Pac Man Closed

Beam Line Support Here

John Amann

slide41

Working progress on IR design…

CMS shield opened

Looking into experience of existing machines…

pacman opened

SLD pacman closed

pacman open

door tunnel

pacman closed

slide43

Air-pads at CMS

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.]

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

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

slide44

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

Matlab model, half-space

ANSYS model

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

slide45

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
crab crossing
Crab crossing

x

factor 10 reduction in L!

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

x

RF kick

crab cavity requirements
Crab cavity requirements

Crab Cavity

IP

~0.12m/cell

~15m

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

Slide from G. Burt & P. Goudket

slide50

View from top

Electric Field

in red

Beam

Magnetic field

in green

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

TM110 Dipole mode cavity

crab cavities
Crab cavities
  • 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.
  • 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

beam dump for 18mw beam
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.
ir coupling compensation
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)

without compensation sy/ sy(0)=32

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

antisolenoid

SD0

QD0

with compensation by antisolenoidsy/ sy(0)<1.01

slide54

Antisolenoids

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

BNL, P.Parker et al.

slide55

70mm cryostat1.7m long

316mm

456mm

Preliminary Design of Anti-solenoid for SiD

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

15T Force

detector integrated dipole
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)
slide57

Orbit in 5T SiD

SiD IP angle zeroed

w.DID

Use of DID or anti-DID

DID field shape and scheme

DID case

anti-DID case

slide59

ATF2

ATF2 goals

(A) Small beam sizeObtain sy ~ 35nmMaintain for long time

(B) Stabilization of beam center

Down to < 2nm by nano-BPM

Bunch-to-bunch feedback of ILC-like train

slide61

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)

Laser wire at ATF

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

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