The design of the 2mrad extraction line Rob Appleby Daresbury Laboratory On behalf of the SLAC-BNL-UK-France task force ILC European Regional Meeting and ILC-BDIR Royal Holloway, 21st June 2005

The 2mrad extraction line design Extensive collaborative work since LCWS05 Study of downstream diagnostics layout Detailed design of doublet region "Short" doublet "Long" doublet Diagnostics2mrad IP Worked out for 500 GeV machine Diagnostics worked out for 500 GeV machine - can "graft" onto the doublet choice for 1 TeV machine At this meeting, fix doublet technology/parameters and develop 1 TeV extraction line for Snowmass Additionally for Snowmass, compare 2mrad/20mrad and benchmark extraction and diagnostics performance Design is a result of a long process of convergence

LHC NbTi IR quads Tolerable beam power losses in SC QD gradient for 0.5 TeV : 215 T/m, radius  35mm higher gradients are studied for LHC upgrades using NbTi(Ta), Nb 3 Sn Assumed ILC WG parameters at IP local & integral LHC spec: 0.4 mW/g & 5 W/m Need to ensure that gradients are achievable

Possible short doublet parameters for TeV l*=3.51m m 9m  optical transfer SC QD (r  35mm) T/m warm QF (r ~ 10mm) T/m 2 mrad ~ 6-7 mrad 1-1.9m to beam diagnostics (consistent with ILC parameters group parameter space) Comparative study: l*=3.51m crossing angle = 2mrad energy =1 TeV

Adjusting the gradient in different background fields from Brett Parker Background field, and safety, leads to gradient reduction QD aperture to 45mm, length to 4m -> "long" doublet For more magnet discussion, see Brett/Cherrill's talk

Cherrill Spencer's Panofsky Septum Quadrupole Slide from Brett Parker +SSQ

Beam envelope in short FD at 1 TeV -80% to -60% -60% to -40% -40% to -20% -20% to 0% QDSDSF Beam x envelope in doubletBeam y envelope in doublet

Beam envelope in long FD at 1 TeV -60% to -40% -40% to -20% -20% to 0% -80% to -60% QDSDSF Beam x envelope in doubletBeam y envelope in doublet

Disrupted beam tracking for short doublet Power loss over 50m sums to ~1kW Beam x envelope in doublet Beam x envelope in extraction line QDQFX1

Disrupted beam tracking for long doublet Power loss over 50m sums to ~1kW Beam x envelope in doublet Beam x envelope in extraction line QDQFX1

X-envelopes and beam sizes for short and long doublets Short doublet Long doublet Beam x envelope in doublet Beam x envelope in extraction line Beam x sizeBeam y size

Downstream diagnostics Slide from Ken Moffeit

2mrad extraction line with diagnostics chicane Plot from Yuri Nosochkov

Full line to dump for 500 GeV machine short doublet I Downstream diagnostics worked out for 500 GeV machine, for a variant of the short doublet. Turtle tracking studies show good beam transport

Full line to dump for 500 GeV machine short doublet I Beam losses: 3.3kW on first collimator at ~90m and 160kW on second collimator at ~500m These need further optimisation to reduce loads Performance of diagnostics chicanes under study

Integration with final focus optics Long doublet was combined with final focus magnets - complete FF deck developed. Bandwidth of system okay, but needs optimisation Short doublet will be okay - expect good bandwidth from Andrei Seryi

Collimation depths Compare 2mrad collimation depths for short and long doublets Use consistent parameters (E=1TeV WG1 nominal parameters, L*=3.51) Compute SR fan with linear optics Slide from Frank Jackson, DL. See his talk at this meeting Long doublet: N x =11  x and N y =88  y Short doublet: N x =17  x and N y =98  y Looser collimation constraints for short doublet than long doublet

Background Simulations for the 2mrad scheme using BDSIM Full Stahl Design with a solenoid field map extending into the Final Doublet region Investigating: Synchrotron from Halo reflecting on QF1 Incoherent pairs and Radiative Bhabhas Power loss into Final Doublet elements and beam cal Mask requirements Also looking to investigate Full background issues along the extraction line Collimation Requirements Rotated view of the Interaction Region Side view of a single electron from a pair event hitting the Inner wall of QD0 Total E [GeV] Slide from John Carter, RHUL. See his talk at this meeting

Conclusion The short and long doublet designs will be differentiated: Beam transport properties - very close behaviour Collimation depth - favours shorter doublet Magnet feasibility - this meeting and see Andrei's talk Short doublet Oide effect suggests longer doublet Choose final doublet technology in consultation with magnet designers ----> include downstream diagnostics and integrate into final focus optics for complete design Other constraints e.g. R22=+0.5 in extraction line Performance study and comparison of the 2mrad and 20mrad extraction lines will be done for Snowmass We need to write some document soon