P.N. Burrows GDE/MDI Vancouver 19/7/06 (T-488) Philip Burrows John Adams Institute Oxford University EM Background Tests of Feedback BPM

P.N. Burrows GDE/MDI Vancouver 19/7/06 Reminder of IP feedback system BPM measures deflection of outgoing bunches Kicker steers incoming bunches into collision Feedback system: BPM signal processor digital FB board drive amplifier x, y: intra-train (3MHz) + 5 Hz

P.N. Burrows GDE/MDI Vancouver 19/7/06 Intra-train y + y’ IP feedback simulations y position FB: restore collisions within 100 bunches 1 seed: post-BBA + GM + wakes y position scan: optimise signal in pair monitor y angle scan OPTIMAL LUMINOSITY

P.N. Burrows GDE/MDI Vancouver 19/7/06 Overview of fast beam feedback R&D UK LCABD: Oxford, Daresbury Lab. Collaborators: SLAC, KEK, DESY, CERN Prototype + test beam-based (intra-train) FB system Completed: ultra-fast analogue feedback prototypes FONT1 / NLCTA: 67 ns latency (2002) FONT2 / NLCTA: 54ns latency (2003/4) FONT3 / ATF: 23ns latency (2005) Ongoing: ILC digital feedback prototypes FONT4 / ATF: 1 st digital FB processor EM background impact on FB BPM

P.N. Burrows GDE/MDI Vancouver 19/7/06 UK group Faculty/PI: Philip Burrows RAs: Glen White Glenn Christian Tony Hartin Electronic engineers: Colin Perry Hamid Dabiri Khah Alexander Kalinin Students: Christine Clarke, Christina Swinson

P.N. Burrows GDE/MDI Vancouver 19/7/06 Nominal IP feedback hardware locations Engineering details TBD!

P.N. Burrows GDE/MDI Vancouver 19/7/06 Nominal IP feedback hardware locations Engineering details TBD!

P.N. Burrows GDE/MDI Vancouver 19/7/06 Nominal IP feedback hardware locations Engineering details TBD!

P.N. Burrows GDE/MDI Vancouver 19/7/06 Pair-induced EM backgrounds BPM e+e- pairs Low Z mask

P.N. Burrows GDE/MDI Vancouver 19/7/06 Beam Parameters SchemeNumber of Pair ParticlesAverage Energy (GeV)BPM hits Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme GeV 1 TeV Pair counts + hits at FB BPM

P.N. Burrows GDE/MDI Vancouver 19/7/06 Primary pair counts Beam Parameters SchemeNumber of Pair ParticlesAverage Energy (GeV)BPM hits Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme GeV 1 TeV

P.N. Burrows GDE/MDI Vancouver 19/7/06 Secondary hits at FB BPM Beam Parameters SchemeNumber of Pair ParticlesAverage Energy (GeV)BPM hits Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme Scheme GeV 1 TeV

P.N. Burrows GDE/MDI Vancouver 19/7/06 Effect of hits on BPM performance? Charge-asymmetry between strips at 10**6 level will cause micron-level degradation of resolution (S. Smith) Our estimates of # hits are X below this level BUT: No cause for complacency – backgrounds always worse Need to model stripline response explicitly (in progress) Noise and/or long-term radiation effects? Experimental tests desirable to add confidence

P.N. Burrows GDE/MDI Vancouver 19/7/06 Origin of BPM hit primaries outgoing beamline r=12mm Max. density of primary pairs / mm^2

P.N. Burrows GDE/MDI Vancouver 19/7/06 Test beam experiment request at ESA SLAC Test Beam Request Title: (FESA)Date: 24 May 2006 Address: John Adams Institute, Denys Wilkinson Building, Keble Rd., Oxford, OX1 3RH, UK. PIs: P.N. BurrowsTelephone: Approved + assigned T-488 Burrows, Christian, Clarke, Hartin, Swinson, White (Oxford University) Kalinin (Daresbury Laboratory) Arnold, Hast, Smith, Woods (SLAC)

P.N. Burrows GDE/MDI Vancouver 19/7/06 FONT Test Module for ESA

P.N. Burrows GDE/MDI Vancouver 19/7/06 FONT Test Module for ESA Material model of ILC outgoing beamline

P.N. Burrows GDE/MDI Vancouver 19/7/06 FONT Test Module for ESA low Z mask beamcal BPM QFEX1 Material model of ILC outgoing beamline

P.N. Burrows GDE/MDI Vancouver 19/7/06 FONT Test Module

P.N. Burrows GDE/MDI Vancouver 19/7/06 T-488 beam test location in ESA

P.N. Burrows GDE/MDI Vancouver 19/7/06 T-488 beamline

P.N. Burrows GDE/MDI Vancouver 19/7/06 Beam test outline Recreate ILC-like primary e- flux on front face of module 1) 30 GeV main beam: create diffuse beam with total charge 10**6 -> 10**10 by varying transmission at slits 2) ‘spray beam’: put main beam through Be radiator, select momentum bites + transport degraded beam to A-line Main problem is to measure flux at low intensity

P.N. Burrows GDE/MDI Vancouver 19/7/06 First beam tests (July ) 10**10 primary beam position scan for reference Blew up beam to 1mm**2, sequentially decreased charge: 10**8 10**7 10**6 Scanned beam across front face of FONT module; recorded BPM waveforms Have not produced spray beam yet

P.N. Burrows GDE/MDI Vancouver 19/7/06 Reference BPM waveforms 10**10 beam through middle of beampipe

P.N. Burrows GDE/MDI Vancouver 19/7/06 1mm sigma beam, 10**7 e-, viewed on screen 5mm fiducial box

P.N. Burrows GDE/MDI Vancouver 19/7/06 Projection of FONT test module at screen r=20mm 3C1 collim. r=12mm inner edge of low-Z mask

P.N. Burrows GDE/MDI Vancouver 19/7/06 Beam scan across module Preliminary (12 Jul 06) Noticeable degradation of signals 10**7 beam

P.N. Burrows GDE/MDI Vancouver 19/7/06 Comparison of beam charges 10**8 10**7 qualitatively similar

P.N. Burrows GDE/MDI Vancouver 19/7/06 Status Built test module of first few m of ILC extraction line Installed in ESA First beam run of T-488 completed July 18 Succeeded in producing and characterising wide primary e- beam with charge down to 10**6 Scanned beam across test module See definite effect on BPM waveforms when beam hits low- Z mask Need to analyse data + compare w. simulations Possible next run in January/February 2007