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CLIC Post-Collision Line and Dump. Edda Gschwendtner, CERN. for the Post-Collision Team

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clic post collision line and dump

CLIC Post-Collision Line and Dump

Edda Gschwendtner, CERN

for the Post-Collision Team

Rob Appleby (CERN & Cockcroft Institute), Armen Apyan (CERN), Barbara Dalena (CERN), Konrad Elsener (CERN), Arnaud Ferrari (Uppsala University), Thibaut Lefevre (CERN), Cesare Maglioni (CERN), Alessio Mereghetti (CERN), Michele Modena (CERN), Mike Salt (Cockcroft Institute), Jan Uythoven (CERN), Ray Veness (CERN), Alexey Vorozhtsov (CERN)

outline
2

2

Outline
  • Introduction
  • Absorbers and Intermediate Dump
  • Magnet System
  • Background Calculations to the IP
  • Main Beam Dump
  • Luminosity Monitoring
  • 500GeV/18.6mrad Option
  • Summary

E. Gschwendtner, CERN

post collision line
Beam

dump

Beam

dump

post-collision line

20mrad

beam1

beam2

detector

Post-Collision Line

E. Gschwendtner, CERN

CLIC meeting, 5 Nov. 2010

some numbers
4

4

Some Numbers

50 Hz repetition rate 156ns bunch train length

3.7E9 e/bunch 312 bunches/pulse

14MW beam power

  • e+e- collision creates disrupted beam
    • Huge energy spread, large x,y div in outgoing beam

 total power of ~10MW

  • High power divergent beamstrahlung photons
    • 2.2 photons/incoming e+e-

 2.5 E12 photons/bunch train

 total power of~4MW

  • Coherent e+e- pairs
    • 5E8 e+e- pairs/bunchX
    • 170kWopposite charge
  • Incoherent e+e- pairs
    • 4.4E5 e+e- pairs/bunchX

 78 W

E. Gschwendtner, CERN

design considerations
5

5

Design Considerations
  • Transport particles of all energies and intensities from IP to dump
  • Diagnostics (luminosity monitoring)
  • Control beam losses in the magnets
  • Minimize background in the experiments
  • Stay clear of the incoming beam
  • Consequences
  •  Large acceptance
  • Collimation system
  • Main dump
  • Beam diagnostic system

E. Gschwendtner, CERN

baseline design
ILC style

water dump

intermediate dump

carbon based absorbers

1.5m

side view

C-shape magnets

6m

315m

4m

27.5m

window-frame magnets

67m

6

6

Baseline Design

A. Ferrari, R. Appleby, M.D. Salt, V. Ziemann, PRST-AB 12, 021001 (2009)

  • Vertical chicane
  • Separation of disrupted beam, beamstrahlung photons and right-sign charge particles from coherent pairs and particles from e+e- pairs with the opposite sign charge particles
    • Intermediate dumps and collimator systems
  • Back-bending region to direct the beam onto the final dump
    • Allowing non-colliding beam to grow to acceptable size

E. Gschwendtner, CERN

baseline design1
side view

ILC type

water dump

beamstrahlung photons

disrupted beam

+ right sign coherent pairs

1.5 TeV

90cm

300 GeV

210m

to IP: 105m

Baseline Design

Collided 1.5TeV Beam at water dump 315m from IP

Right sign coherent beam

Beamstrahlung photons

Disrupted beam

E. Gschwendtner, CERN

baseline design2
Baseline Design

Geometry fully implemented in SW tools

to

main dump

C-shaped

magnets

intermediate

dump

window-frame

magnets

to IP

absorbers

absorber baseline design
Absorber Baseline Design

10

10

Intermediate dump (CNGS style):

iron jacket, carbon based absorber,water cooled aluminum plates, 3.15m x 1.7m x 6m

 aperture: X=18cm, Y=86cm

Magnet protection:

Carbon absorbers:

Vertical apertures between 13cm and 100cm

E. Gschwendtner, CERN

absorber baseline design1
11

11

Absorber Baseline Design

Aperture dimensions tuned such that losses in magnets < 100W/m

170kW

Opposite sign charge particles

1.9kW

0.7 kW

131kW

3.1kW

Right sign charge particles

1kW

6.9kW

  • All opposite charge particles absorbed by upper part of dump
  • Right charge particles with energy >16% of nominal pass through

4kW

0.9kW

0kW

 Solutions for absorbers exist (see dumps in neutrino experiments: 4MW)

E. Gschwendtner, CERN

magnets
12

12

Magnets

E. Gschwendtner, CERN

post collision line magnets
Post-Collision Line Magnets

13

  • Designed considerations:
  • average current density in copper conductor < 5 A/mm2.
  • magnetic flux density in magnet core is < 1.5 T.
  • temperature rise of cooling water < 20° K.
  •  All magnets strength of 0.8 T
  •  In total 18 magnets of 5 different types
  • Total consumption is 3.3MW

M. Modena, A. Vorozhtsov, TE-MSC

E. Gschwendtner, CERN

magnets1
Magnets

Mag2

Mag3

Mag4

14

C-type

Mag1a (window frame type)

incoming beam

54.1cm

49 cm

40.8 cm

34.3cm

20.1cm

11.1cm

5.1cm

spent

beam

Inter-

mediate

dump

Mag1b

Mag1a

C-

type

38m

46m

27.5m

30.5m

54m

67m

75m

E. Gschwendtner, CERN

window frame type magnets mag1a1b
Window Frame Type Magnets Mag1a1b

10A/mm2

198kCHF

143kW

19.5cm distance to

incoming beam

4.6A/mm2

280kCHF

65kW

5.1cm distance to

incoming beam

M. Modena, A. Vorozhtsov, TE-MSC

E. Gschwendtner, CERN

vacuum system
Vacuum System

16

16

E. Gschwendtner, CERN

E. Gschwendtner, CERN

CLIC meeting, 5 Nov. 2010

vacuum system1
Vacuum System

Less demanding pressure requirement in the medium vacuum range (required pressure TBC),

allowing for a conventional un-baked system design.

Requires a high pumping speed due to the large surface area and beam-induced outgassing.

A combination of sputter-ion, turbo-molecular and mechanical pumps will be used.

stainless steel vacuum chambers in stepped or conical forms inside the magnetic and absorber elements.

Absorbers are outside the vacuum chambers

windows upstream of the intermediate dump absorbers

exit window separating the collider vacuum system from the main dump body

Large diameter (~1m).

17

17

elliptical vacuum tube

R. Veness, TE-VSC

E. Gschwendtner, CERN

E. Gschwendtner, CERN

CLIC meeting, 5 Nov. 2010

background calculations to ip
18

18

Background Calculations to IP

E. Gschwendtner, CERN

background calculations from post collision line to ip
19

19

Background Calculations from Post-Collision Line to IP
  • Entire Post-collision line geometry implemented
  • Using Geant4 on the GRID
    • Neutron and photon background from absorbers and intermediate dump
    • Neutron and photon background from main beam dump

 Ongoing: M. Salt, Cockcroft Institute

C-shaped

magnets

intermediate

dump

window-frame

magnets

absorbers

E. Gschwendtner, CERN

photon background from first absorber to ip
IP

10m

20

20

Photon Background from First Absorber to IP

From first absorber:

0.73 ± 0.05 photons/cm2/bunchX

Backscattered photons at the entrance to the first magnet (s = 27.5 m)

M. Salt, Cockcroft Institute

E. Gschwendtner, CERN

photon background from intermediate dump to ip
Photon Background from Intermediate Dump to IP

21

21

Backscattered photons at the entrance to the intermediate dump (s = 67 m)

From intermediate dump:

7.7 ± 2.6 photons/cm2/bunchX

(without absorbers: 530 ± 20 photons/cm2/bunchX)

  • Intermediate dump contributes significantly to IP background
  • But 98% attenuation thanks to aperture restriction in the chicane

M. Salt, Cockcroft Institute

E. Gschwendtner, CERN

slide22
Background Calculations to IP
  • Preliminary results show that background particles at ‘outer edge’ of the LCD is low.
  • The detector yoke and calorimeter will further shield the vertex and tracker against
  • hits from background photons.
  • Even if additional absorbers are needed, space is available in the forward region between the detector (6m) and the first post-collision line magnet (27m) .

Lumical

BPM

Spent beam

QD0

Kicker

Beamcal

N.Siegrist, H.Gerwig

main beam dump
23

23

Main Beam Dump

E. Gschwendtner, CERN

main dump
24

24

Main Dump
  • 1966: SLAC beam dump
    • 2.2 MW average beam power capacity
    • Power absorption medium is water
  • 2000: TESLA
    • 12 MW beam power capacity
    • Water dump

E. Gschwendtner, CERN

baseline main dump design
Baseline Main Dump Design

2008: ILC 18 MW water dump

Cylindrical vessel

Volume: 18m3, Length: 10m

Diameter of 1.8m

Water pressure at 10bar (boils at 180C)

Ti-window, 1mm thick, 30cm diameter

 baseline for CLIC 2010 main dump

15.0 mm thick Ti vessel

30.0 cm diameter window (Ti)

1.0 mm thick

ILC type

water dump

Diameter 1.5 m

Dump axis

Length 10.0 m

25

25

25

E. Gschwendtner, CERN

CLIC meeting, 5 Nov. 2010

clic main beam dump
26

26

CLIC Main Beam Dump
  • Uncollided beam:

sx = 1.56mm, sy =2.73mm  5.6mm2

  • Collided beam:

Photons

Disrupted beam

Coherent beam

Collided 1.5TeV Beam at water dump 315m from IP

Right sign coherent beam

Beamstrahlung photons

Disrupted beam

E. Gschwendtner, CERN

particle distribution at the beam dump entrance
Particle Distribution at the Beam Dump Entrance

27

27

Disrupted beam

Coherent beam

Photons

10-3

10-4

10-3

0mm

0mm

750mm

0mm

-750mm

-750mm

-750mm

27

Window

Dump

A. Mereghetti, EN-STI

E. Gschwendtner, CERN

energy deposition in main dump
Energy Deposition in Main Dump

28

28

max ≈ 270 J/cm3

uncollided beam

collided beam (x10)

max ≈ 10 J/cm3

uncollided beam

collided beam

[J cm-3 per bunch train]

[J cm-3 per bunch train]

A. Mereghetti, EN-STI

E. Gschwendtner, CERN

main dump issues
Main Dump Issues

29

  • Maximum energy deposition per bunch train: 270 J/cm3

 ILC: 240 J/cm3 for a 6 cm beam sweep

  • Remove heat deposited in the dump
    • Minimum water flow of 25-30 litre/s with v=1.5m/s
  • Guarantee dump structural integrity
    • Almost instantaneous heat deposition generate a dynamic pressure wave inside the bath!
    • Cause overstress on dump wall and window (to be added to 10bar hydrostatic pressure).

 dimensioning water tank, window, etc..

  • Radiolytical/radiological effects
    • Hydrogen/oxygen recombiners, handling of 7Be, 3H

 Calculations ongoing

E. Gschwendtner, CERN

slide30
Dump Hall - Tank - Geometry Version 2

ILC Beam Dump

Surround Dump Tank with 50 cm Iron + ~200 cm Borcrete (Concrete + 5% Boron).

Minimize volume of activated air.

Tail Catcher inside Dump Tank.

Small open area around windows for changer mechanism to be developed.

Space Distribution of Steady State Water Temperature

Beam spot, 6 cm sweep radius

This plan can work.

50 0C water inlet, 2.5 m/s

Max water temp

147 0C

Insertion Beam

Line

Temp K

Beam Line Magnets

Inlet

Outlet

Shd2 - Borcrete

Extraction Beam

Line

Shd1 - Borcrete

Shd0 - Iron

Sump

CLIC08, CERN, 16 Oct 2008

slide31
31

31

Energy Deposition in CLIC Beam Dump Window

  • Titanium window:
  • 1mm thick, 30cm diameter, cooling on internal surface by dump water at 180°C

 Total deposited Power: ~6.3W

max ≈ 4.3 J/cm3

uncollided beam

collided beam

max ≈ 0.13 J/cm3

uncollided beam

collided beam

A. Mereghetti, EN-STI

E. Gschwendtner, CERN

slide32
Temperature Rise in CLIC Beam Dump Window
  • Temperature rise per 1 pulse:
  • DT=0.44°C
  • Stable temperature after 3-4 sec with DT=24°C

C. Maglioni, EN-STI

E. Gschwendtner, CERN

ilc beam dump window
ILC Beam Dump Window

Titanium window:

hemispherical shape, 1mm thick, 30mm thick, single jet cooling

  • Maximal total power of 25 W with 21 J/cm3
  • Maximum temperature rises to 57°C
other main dump window issues
Other Main Dump Window Issues

34

  • Beam dump window needs stiffener, double/triple parallel window system, symmetric cooling, etc… to withstand
    • Hydrostatic pressure of 10bar
    • Dynamic pressure wave
    • Window deformation and stresses due to heat depositions

 Calculations ongoing

E. Gschwendtner, CERN

luminosity monitoring
Luminosity Monitoring

35

35

E. Gschwendtner, CERN

slide36
36

36

Luminosity Monitoring

e+e- pair production

Beamstrahlung through converter Produce charged particles Optical Transition Radiation in thin screen Observation with CCD or photomultiplier

m+m- pair production

V.Ziemann – Eurotev-2008-016

  • Main dump as converter muons  install detector behind dump
    • With a Cherenkov detector: 2 E5 Cherenkov photons/bunch

Converter (1mm thick C)

Small magnetic field (10-3 Tm)

OTR screen

(30mm diameter)

E. Gschwendtner, CERN

slide37
Muons/cm2/bunch

37

37

First Results

Muon distribution with E> 212MeV behind the beam dump and shielding

A. Apyan, EN-MEF

E. Gschwendtner, CERN

slide38
Muons/cm2/bunch

38

38

First Results

Muon distribution with E> 50 GeV behind the beam dump and shielding

A. Apyan, EN-MEF

Calculations ongoing:

 Include Cherenkov counters in simulations

 produce non-perfect collisions and track particles through post collision line to see variations in luminosity detectors

E. Gschwendtner, CERN

500 gev c m scenario
500 GeV c.m. Scenario

39

39

39

E. Gschwendtner, CERN

CLIC meeting, 5 Nov. 2010

slide40
Photons:

19cm horizontal shift, but reduced in size

250 GeV

1.5 TeV

19cm shift

x’max = ±0.6mrad

y’max= ±0.3mrad

40

40

500 GeV c.m. /18.6mrad Option versus 3000 GeV c.m. / 20mrad Option

Collided 1.5TeV Beam at water dump 315m from IP

80cm

Right sign coherent beam

Beamstrahlung photons

Disrupted beam

x’max = ±1.6mrad

y’max= ±1mrad

 Proof of principle

Impact of 500GeV c.m. scenario on post-IP design is minimal

E. Gschwendtner, CERN

E. Gschwendtner, CERN

CLIC meeting, 5 Nov. 2010

summary
41Summary
  • Many new results achieved since last year
  • Conceptual design of the CLIC post-collision line exists:
    • Magnets
    • Intermediate dumps
    • Background calculations to the IP
    • Luminosity monitoring: First promising results
    • Beam dump: first results, calculations ongoing
      • Improve design on beam dump
      • Collaboration with ILC: ILC-CLIC working group on dumps?

E. Gschwendtner, CERN

slide42
42

42

  • Additional Slides

E. Gschwendtner, CERN

slide43
Plus others ………..

IP Feedback

Beamcal+

Lumical

Anti-solenoid

Vacuum

QD0 quadrupoles

Support

tubes

+Stabilization + prealignment

slide45
Prompt Energy Deposition - J/cm3/hour - Geometry V2

Even the rocks get hot!

Plan View

Muon Spoiler Hall

Dump Hall

Air

Air

DT ~ 2 deg C/hour

Borcrete

Granite

Water

Iron

CLIC08, CERN, 16 Oct 2008

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