Status of ATF2 linear collider focus prototype emphasizing France-China joint contributions Philip Bambade Laboratoire de l’Accélérateur Linéaire Université Paris 11, Orsay, France 5 th FCPPL Workshop, LAL&CEA-Saclay March 2012

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ATF & ATF2 R&D for linear colliders  efficiency P elec N e E cm  x  y  efficiency P elec  beamstrahlung E cm  y,normalised Luminosity ~  Parameters ATF2ILCCLIC Beam Energy [GeV] L* [m]  x/y [m.rad] 5E-6 / 3E-81E-5 / 4E-86.6E-7 / 2E-8 IP  x/y [mm] 4 / / / 0.07 IP  ’ [rad]  E [%] ~ 0.1 ~ 0.3 Chromaticity ~ 1E4 ~ 5E4 Number of bunches1-3 (goal 1)~ Number of bunches3-30 (goal 2)~ Bunch population1-2E102E103.7E9 IP  y [nm] linac RF + sources beam size control & stability cost & feasibility trade-off

ATF2 Goals  Small vertical beam size - achievement of  y ~ 37 nm (cf. 5 nm in ILC)  Stabilization of beam center - down to ~ 2nm - bunch-to-bunch feedback (~300 ns)  R&D on instrumentation to measure nanometer size beams  Training of young accelerator physicists and engineers on “real system”  open & unique facility

ATF2 operation & instrumentation R&D DR extraction setup, stability Match optics into FF buffer section for input errors 2 nd order telescope fine tuning of local errors

    FCPPL FJPPL FKPPL

Installation of quadrupoles contributed by IHEP (China) in January 2008

“Shintake” beam size monitor at IP Sensitivity ranges of crossing angles

Measurement of the vertical beam size at ATF2 Example: A beam size measured (2010/May/20) Modulation Depth = 8.0 deg. mode  y = (stat.) (syst.) nm A smaller beam size, 37 nm, is one of the target of Goal-1. The reached size was 300 nm before the Great East Japan earthquake. Recover 300nm again, then continue the tuning down to 37 nm.

Great Eastern Earthquake – March 11, 2011 Beams recovered in June !  but ~9 month delay in ATF2 program… Nobuhiro Terunuma (KEK)

Essential to reduce the optical demagnification gradually ! February 2012

Is 37 nm vertical size the limit at ATF2 ? Study explores to what extent can be varied the   * Originally motivated to start ATF2 with larger   * values –More comfortable situation, less sensitive to errors (non-linear optics…) Study shows that beam size down to ~17 nm might be achievable ! –Of large interest for CLIC machine, to demonstrate the its chromaticity regime is feasible –Such low   * values are also of interest for alternative (more economical) ILC setups with “pushed” IP parameters Sha Bai (IHEP & LAL, FCPPL & Eiffel grant)

Skew sextupole tolerance compared to the measurement for the quadrupoles Best quadrupoles: QM15FF, QD10X, QF11X, QF17X, QD18X Worst quadrupoles:QD4BFF, QD0FF, QF5AFF, QF9AFF, QF5BFF Dou Wang (IHEP & KEK) “Mitigating the effects of higher order multipole fields in the magnets of ATF2”, Sha Bai (IHEP) et al., accepted for publication in Chinese Phys. C

First beam waist measurements in the final focus beam line at the KEK Accelerator Test Facility, by Sha Bai et al.: PRSTAB 13, (2010) Method first described in:

 PhD thesis topic Shan Liu (Jilin U.) has applied under the FCPPL-CSC doctoral grant scheme

Selected publications and reports P. Bambade (LAL) et al., Present status and first results of the final focus beam line at the KEK Accelerator Test Facility, PRSTAB 13, (2010) S. Bai (IHEP) et al., First beam waist measurements in the final focus beam line at the KEK Accelerator Test Facility, PRSTAB 13, (2010) S. Bai (IHEP) et al., Simulation of beam size multiknobs correction at Accelerator Test Facility 2 at KEK, Chinese Phys. C 2011 Vol.35(4): S. Bai (IHEP) et al., Mitigating the effects of higher order multipole fields in the magnets of ATF2, Accepted for publication in Chinese Phys. C, 2011 Optical configurations with variable beta* at different IP locations in ATF2, by S. Bai, P. Bambade: ATF-08-05, LAL/RT Linear Collider Test Facility: Twiss Parameter Analysis at the IP/Post-IP location of the ATF2 beam line, by B. Bolzon et al.: THPD077.PDF, Presented at the 1st International Particle Accelerator Conference (IPAC 2010), Kyoto, Japan, May 2010 ATF2 ultra-low IP betas proposal, by R. Tomas et al.: LAL-RT-09-11, Presented at the 23rd Particle Accelerator Conference (PAC09), Vancouver, Canada, 4-8 May 2009 Linear Collider Test Facility: Twiss Parameter Analysis at the IP/Post-IP location of the ATF2 beam line, by B. Bolzon et al.: THPD077.PDF, Presented at the 1st International Particle Accelerator Conference (IPAC 2010), Kyoto, Japan, May 2010 Simulation of Multiknobs Correction at ATF2, by S. Bai et al.: THPD096.PDF, Presented at the 1st International Particle Accelerator Conference (IPAC 2010), Kyoto, Japan, May 2010

Concluding comment ATF2 is making good strong progress in 2012, after recovering form the earthquake The 30 degree mode of “Shintake” monitor is now validated Collaboration with China (IHEP,…) is continuing builing on the FCPPL initial support THANK YOU !