Beam Delivery System Summary Andrei Seryi LCWS 2010 / ILC 2010 March 30, 2010

ILC 2010, Mar/27/10 A. Seryi, BDS: 2 Plan of the program at ILC2010 Focus of efforts –Work on parameter set for a possible new baseline –Work on a prototype of the final focus at ATF2 –Work on design of key technical systems of BDS

ILC 2010, Mar/27/10 A. Seryi, BDS: 3 BDS & MDI presentations at ILC presentations –Including joint sessions with MDI, DR, CFS & GG and presentations during joint working sessions on SB2009 optimizations

ILC 2010, Mar/27/10 A. Seryi, BDS: 4 SB2009 BDS Updates Changes in the subsystem integration of the central region: As of the RDR, the BDS, the electron source and the damping rings are clustered in the central region of the ILC accelerator complex. The proposed changes in the baseline envisage relocation of the positron source system to the downstream end of the electron main linac, so that they also join this central region. This impacts the subsystem layout in ways that affect the implementation of electron side BDS. Changes in the baseline parameter set: Proposed adoption of the low power beam parameter set (same machine pulse repetition rate and the same bunch intensity, but a reduced number of bunches per pulse) leads to a desire to push the beam-beam parameter, so that the same luminosity as in RDR can be achieved. As a solution the so-called travelling focus scheme is being considered.

ILC 2010, Mar/27/10 A. Seryi, BDS: 5 The central integration includes the sources in the same tunnel as the BDS. Relocation of the positron production system to the downstream end of the electron linac means placing it just before the beginning of the electron BDS. These changes need suitable design modifications to the layout of this area. Figure above shows the proposed new layout of the electron BDS Homework: Polarimeter chicane is still to be inserted (shrink FF to keep the length) Deepa Angal-Kalinin et al

ILC 2010, Mar/27/10 A. Seryi, BDS: 6 B. FosterCo-Chair A. SeryiCo-Chair J. Clarke M. Harrison D. Schulte T. Tauchi 6 Effect of changes for running at lower energies following the Physics Questions Committee’s Status Report provided to the SB2009 Working Group of Detector colleagues Brian Foster, Jim Clarke, Andrei Seryi for the Physics Question Committee AAP Review Oxford, January 6-8, 2010

ILC 2010, Mar/27/10 A. Seryi, BDS: 7 Beam Parameters 7 Rate at IP = 2.5Hz, Rate in the linac = 5Hz (every other pulse is at 150GeV/beam, for e+ production) Low luminosity at this energy reduces the physics reach

ILC 2010, Mar/27/10 A. Seryi, BDS: 8 L,E34 E CM 1/E 0.5/E 0.25/E 0.5/E SB2009 Lumi Actual luminosity Rate at IP = 2.5Hz, Rate in the linac = 5Hz (every other pulse is at 150GeV/beam, for e+ production) Low luminosity at this energy reduces the physics reach

ILC 2010, Mar/27/10 A. Seryi, BDS: 9 Lumi(E) dependence in SB2009 Factor determine shape of L(E) in SB2009 –Lower rep ( /2) rate below ~125GeV/beam –Collimation effects: increased beam degradation at lower E due to collimation wakes and due to limit (in X) on collimation depth Understanding the above limitations, one can suggest mitigation solutions: –1) Consider doubling the rep rate at lower energy –2) Consider Final Doublet optimized for 250GeV CM

ILC 2010, Mar/27/10 A. Seryi, BDS: 10 Work on mitigations of L(E) with SB2009 during ILC2010 Have initiated discussion of double rep rate ~month before the ILC2010 Doubling the rep rate (below ~125GeV/beam) –BDS WG discussed implications with other Working Groups: DR => OK! (new conceptual DR design was presented!) Sources => OK! Linac, HLRF, Cryogenics => OK! FD optimized for ~250GeV CM –Shorter FD reduce beam size in FD and increase collimation depth, reducing collimation related beam degradation –Will consider exchanging FD for low E operation or a more universal FD that can be retuned

ILC 2010, Mar/27/10 A. Seryi, BDS: 11 Emittance damping t/  x 8 damping times are needed for the vertical emittance 5 Hz   x = 26 ms 10 Hz   x = 13 ms S. Guiducci (LNF)

ILC 2010, Mar/27/10 A. Seryi, BDS: 12 DR Parameters for 10 Hz Operation Energy = 5 GeV S. Guiducci (LNF) et al DR (3.2km) at 10Hz is feasible

ILC 2010, Mar/27/10 A. Seryi, BDS: 13 Double rep rate: Sources Electron Source: –doubling rep rate is not critical [Axel Brachmann, Tsunehiko Omori et al] Positron Source: –For SB b case there should be no issues For 250a, which is not a preferred solution, the most important consequence of the increased rep rate will be the increased average power on the positron target Even for this case there is a hope that it can be managed, but need more detailed studies [Jim Clarke, Wei Gai, et al]

ILC 2010, Mar/27/10 A. Seryi, BDS: 14 Linac and double rep rate At lower gradient, considering the cryo load (which should not be exceeded) and the efficiency of rf power sources (their efficiency decreases with power) concluded, that at 125 GeV/beam one can work at 10Hz rep rate in the linac At 150GeV/beam one can work at 8Hz in the linac –And this is possible only because the e+ source is at the end of the linac! => SB2009 OK for linac rep rate 10 Hz for 125 GeV/beam & 8 Hz for 150 GeV/beam Chris Adolphsen, et al

ILC 2010, Mar/27/10 A. Seryi, BDS: 15 Linac OK for double rep rate At lower gradient, it would be easy to increase the rep rate of the cavities to maintain a constant cryo load (the rep rate scales roughly as 1/gradient^2). However, one cannot readily increase the rep rate of the rf power sources as their efficiency decreases with power. In particular the klystron output power scales as V^3.5 where V = the modulator voltage while the power flow in the modulators and klystrons scales as V^2.5, and their rep rate scales as 1/(flow*pulse width) (limited mainly by the site power capacity and the modulator charging supply ratings). For example, at half the gradient, the klystron voltage could be lowered to.5^3.5 =.82 of its nominal value and rep rate could then be increased by a factor of 1/.82^2.5 = 1.64 times the pulse width factor of ~ 1.6/1.3 (due to the shorter filling time) for a net factor of 2.0 (up to 10 Hz). There would be some additional costs associated with designing the modulators to run at a variable rep rate. However, I believe the main problem would be in the damping rings as the beams need 200 ms to be fully damped (one would need to increase the damping rate with more undulators). And of course, at low beam energy, half the pulses have to run at 150 GeV or above to generate photons to produce positrons (although such pulses probably do not have to be fully damped, the modulators would probably need to run at a constant pulse spacing). Thus with damping times of 5/8 nominal, one could perhaps run 4 Hz at 150 GeV (for e+ production) interleaved with 4 Hz of luminosity production (vs 2.5 Hz in the report) at < 150 GeV per beam. Also, for beam energies of 250 GeV down to 150 GeV, all pulses would be for luminosity and the rep rate would increase from 5 Hz to 8 Hz (which is an advantage of putting the undulators at the end of the linacs) Chris Adolphsen: => SB2009 OK for linac rep rate of 10 Hz for 125 GeV/beam & 8 Hz for 150 GeV/beam

ILC 2010, Mar/27/10 A. Seryi, BDS: 16 Cryo load is OK #1#2 G=31.5 MV/mG=15.75 MV/m Nb=2625Nb=1312 Ne+=2E10 2K8.6 W5.5 W 4K8.2 W7.7 W 40K131 W106.8 W Total per cryomodule9.8 kW8.2 kW Notes: Qext(#1)=Qext(#2) Conversion: 2K=> 703 W/W 4K=> 197 W/W 40K=> W/W Ratio: Total (#2)/ (#1) = Cavity losses: #1: 5.98 W (out of 8.6) #2: 2.99 W (out of 5.5) Nikolay Solyak:

ILC 2010, Mar/27/10 A. Seryi, BDS: 17 One option would be to have a separate FD optimized for lower E, and then exchange it before going to nominal E Other option to be studied is to build a universal FD, that can be reconfigured for lower E configuration (may require splitting QD0 coil and placing sextupoles in the middle) FD optimized for lower energy will allow increasing the collimation depth by ~10% in Y and by ~30% in X (Very tentative!) FD for low E Nominal FD & SR trajectories FD for 1/2E & SR trajectories

ILC 2010, Mar/27/10 A. Seryi, BDS: 18 Beam Parameters & mitigation Tentative! At 250 GeV CM the mitigations may give –* 2 L due to double rep rate –* about 1.4 L due to FD optimized for low E 18

ILC 2010, Mar/27/10 A. Seryi, BDS: 19 SB2009 Lumi Linac rate 10Hz (IP rate 5Hz) and special FD Linac & IP rates are 8Hz

ILC 2010, Mar/27/10 A. Seryi, BDS: 20 SB2009 optimization There are ways to increase L at low E which look promising and can be studied further The joint work of several Working Groups on double rep rate case during ILC2010 is a very good example of workshop-style joint work! Thanks to all WGs for joint efforts

ILC 2010, Mar/27/10 A. Seryi, BDS: 21 ATF2

ILC 2010, Mar/27/10 A. Seryi, BDS: 22 ATF2 Scaled ILC final focus ATF2: model of ILC beam delivery goals: ~37nm beam size; nm level beam stability Dec 2008: first pilot run; Jan 2009: hardware commissioning Feb-Apr 2009: large  ; BSM laser wire mode; tuning tools commissioning Oct 2009-June 2010: commission interferometer mode of BSM, aim for ~100nm beam

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ILC 2010, Mar/27/10 A. Seryi, BDS: 24 Ongoing R&Ds at ATF/ATF2 ATF low emittance beam Tuning, XSR, SR, Laser wire,… 1pm emittance (DR BPM upgrade,…) Multi-bunch Instability (Fast Ion,…) Extraction by Fast Kicker Others Cavity Compton SR monitor at EXT ATF2 35 nm beam size Beam tuning (Optics modeling, Optics test, debugging soft&hard tools,…) Cavity BPM (C&S-band, IP-BPM) Beam-tilt monitor IP-BSM (Shintake monitor) Beam position stabilization (2nm) Intra-train feedback (FONT) feed-forward DR->ATF2 Others Pulsed 1um Laser Wire Cold BPM Liquid Pb target Permanent FD Q SC Final doublet Q/Sx

ILC 2010, Mar/27/10 A. Seryi, BDS: 25 Beam Size monitor team: Feb 2010 Working with large beta*. Preparing hardware & tuning software for tuning down to smaller size. Next runs: April & May

ILC 2010, Mar/27/10 A. Seryi, BDS: 26 SC FD and Cryogenics “Update on SC Magnets and Schedule,” Brett Parker, BNL-SMD 26 Face-to-face meeting at BNL was very productive; Will schedule a new meeting at KEK meeting at BNL (now the preferred option) (now the preferred option) ATF2 Option 2

ILC 2010, Mar/27/10 A. Seryi, BDS: 27 ATF2 Coil Winding Status “Update on ATF2 SC Magnets” Brett Parker, BNL-SMD Winding Schematic for ATF2 Quad All 3 coil sets now complete

ILC 2010, Mar/27/10 A. Seryi, BDS: 28 ILC QD0 R&D Prototype Long Coil Winding Challenges We did not adequately control the coil support tube position (even with orthogonal machine-controlled rolling supports). Our first R&D coils had substantial harmonic errors. We have therefore decided to go back to using a few fixed, rigid supports and have made modifications (shown here) to the ATF2 “ILC SC FD & ATF2 SC Magnet Upgrade – Update,” Brett Parker, BNL-SMD short coil winding machine. We extended the machine & carefully positioned fixed supports between the coils. The 2.2 m long QD0 R&D coil will be wound in two sections on a common tube.

ILC 2010, Mar/27/10 A. Seryi, BDS: 29 Beam Delivery & MDI items 14mr IR Final Focus E-spectrometer polarimeter Diagnostics Tune-up dump Beam Switch Yard Sacrificial collimators Extraction with downstream diagnostics grid: 100m*1m Main dump Muon wall Tune-up & emergency Extraction IR Integration Final Doublet 1TeV CM, single IR, two detectors, push-pull Collimation: , E Optimize IR ensuring the needed detector performance & efficient push-pull operation Agree on division of responsibilities for space, parameters and devices

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ILC 2010, Mar/27/10 A. Seryi, BDS: Ground motion through the feet From this…. …….to this Vibration studies for SiD Marco Oriunno, SLAC

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ILC 2010, Mar/27/10 A. Seryi, BDS: 41 MSL - SLAC41 Beam 1 hits tungsten mask at IP-3 m ~ 100 /event ~ 1800 mSv/h µSv/1_train 9 MW The spaces between the door plates are empty in the model, but in the real detector they will be partially filled Radiation Protection studies for SiD Mario Santana, SLAC / RP

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ILC 2010, Mar/27/10 A. Seryi, BDS: 45 ILC Project general view John Osborne – March 2010

ILC 2010, Mar/27/10 A. Seryi, BDS: 46 ILC RDR Baseline Layouts for Interaction Region

ILC 2010, Mar/27/10 A. Seryi, BDS: 47 Possible new cross section

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ILC 2010, Mar/27/10 A. Seryi, BDS: 49 Additional question: –What sample (example) site will be included in TDP report? –FNAL, CERN, Japan, Dubna?

ILC 2010, Mar/27/10 A. Seryi, BDS: 50 Path forward IP parameter optimization –Detailed work on SB2009 study –Evaluate double rep rate at low E BDS & MDI coherent plan –Enhance BDS-MDI work IR & Push-pull Stability Connection to CFS ATF2 work –Beam size –Stability –Upgrades 1) Is this the correct strategy to achieve the goal of ‘cost- constraint’ ? Especially with respect to your working group. 2) How should we improve communication within the GDE and with key stakeholders (e.g. Physics and Detector groups)? 3) What are the top concerns you have for achieving the goals outlined in the R D Plan for the TDP – through 2012? (see general program announcement).