CLIC Post-Collision Line

1. CLIC Post-Collision Line Edda Gschwendtner, CERN for the Post-Collision Working Group Rob Appleby (CERN & Cockcroft Institute) Armen Apyan (CERN) Konrad Elsener (CERN) Arnaud Ferrari (Uppsala University) Mike Salt (Cockcroft Institute) Jan Uythoven (CERN) Volker Ziemann (Uppsala University)

2. post-collision line dump dump 20mrad beam2 beam1 detector Post-Collision Line E. Gschwendtner, CERN

3. disrupted beam at interaction point Coherent pairs 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 • 170kW opposite charge • Incoherent e+e- pairs • 4.4E5 e+e- pairs/bunchX  78 W E. Gschwendtner, CERN

4. Baseline: vertical chicane with 2x4 dipoles Separation by dipole magnets of the disrupted beam, beamstrahlung photons and particles with opposite sign from coherent pairs, from low energy tails Short line to prevent the transverse beam size from growing too much Intermediate dumps and collimator systems Back-bending region with dipoles to direct the beam onto the final dump  Long line allowing non-colliding beam to grow to acceptable size ILC style water dump intermediate dump carbon based masks 1.5m side view C-shape magnets 6m 150m 4m 27.5m window-frame magnets 67m Conceptual Design R.B. Appleby, A. Ferrari, M.D. Salt and V. Ziemann, Phys. Rev. ST Accel. Beams 12 (2009) 021001. E. Gschwendtner, CERN

5. 4MW 10MW beamstrahlung photons 1.5 TeV Collided 1.5TeV Beam at 150m from IP disrupted beam + same sign coherent pairs 90 cm beamstrahlung 300 GeV Disrupted beam 30mm rms Right-sign coherent pairs Conceptual Design Side view Uncollided 1.5 TeV beam at 150m from IP: Spot size of 3mm2 A. Ferrari, R. Appleby, M.D. Salt, V. Ziemann, PRST-AB 12, 021001 (2009) E. Gschwendtner, CERN

6. Critical Issues • Background to IP  PhD student at Cockcroft Institute, UK • Luminosity measurements  Project associate  Fellow to come in summer • Beam dump design • Window • Energy deposition and pressure in tank • Magnet design • Beam blow-up at dump • Tilted magnets • Kickers E. Gschwendtner, CERN

7. Baseline Dump Design 1966: SLAC water based beam dump: 2.2MW 2008: ILC 18 MW water dump • Cylindrical vessel • Volume: 18m3 • Length: 10m • Diameter of 1.5m • Water pressure at 10bar (boils at 180C) • Cu-window, 1mm thick, 30cm diameter E. Gschwendtner, CERN

8. Energy Deposition in the Beam Dump Energy deposition (MeV/cm3) of an uncollided 1.5TeV electron beam. Work ongoing/setting up to calculate: • Energy deposition calculations in windows, water, etc… (FLUKA) • Stress, heating, etc… (ANSYS) • What is the impact on the beam-size? MeV/cm3 A. Apyan E. Gschwendtner, CERN

9. C-shape magnets Window-frame magnets 45cm 75cm 57.7cm < h < 153.1cm Magnet Status • Main issues • Design of magnets • Defocusing the beam • (tilting the poles of C-shape magnets, gradient of ~10T/m) • Sweeping magnets B=0.8T E. Gschwendtner, CERN

10. Summary Conceptual design exists. Detailed studies: are ongoing • Photon and neutron backgrounds at the IP • Beam dump studies of particle production and energy deposition or need to be setup • Beam dump design • magnets design • beam blowup E. Gschwendtner, CERN

11. Introduction E. Gschwendtner, CERN

12. Particle distributions in beam dump Undisrupted beam, 1.5 TeV beam Neutron Photon Primary electron showers in water, depositing energy and producing photons, neutrons (mainly photonuclear) (+ others). Work ongoing to extract the peak GeV/cc deposited to calculate delta-T per train A. Apyan E. Gschwendtner, CERN