odr diagnostics for hadron colliders

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ODR Diagnostics for Hadron Colliders. Tanaji Sen FNAL/APC. Acknowledgements: A. Lumpkin, V. Scarpine, R. Thurman-Keup, M. Wendt. Diffraction Radiation. Radiation emitted when a charged particle passes in the vicinity of a conducting target. - PowerPoint PPT Presentation

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  • ODR Diagnostics for Hadron CollidersTanaji SenFNAL/APCAcknowledgements: A. Lumpkin, V. Scarpine, R. Thurman-Keup, M. Wendt

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersDiffraction RadiationRadiation emitted when a charged particle passes in the vicinity of a conducting target. Two cones (angle ~ 2/ ) of radiation in the forward and backward direction Key parameters: the impact parameter, beam energy and wavelength of radiation

    Similar (and different) to transition radiation where a particle passes through the conducting target.

    Main advantage: Non-invasive

    Initial theory developed: ~ 1960s First measurements reported: ~1995

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersPossible Beam DiagnosticsDiffraction Radiation ObservablesNear field (at or near target) intensityPolarizationFrequency spectrumFar field angular distributionInterference between radiation from 2 sources

    These can be combined to potentially measureBeam size Beam position Beam divergence Energy

    Recent measurements at KEK, APS, FLASH Interest at other labs: CEBAF, BNL

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersDiffraction Radiation - LayoutBDRCCD or PMTFilterPolarizerTargetProton beamb Impact parameterBeam2Far field imaging at KEKPhys. Rev Letters90, 104801 (2003)93, 244802 (2004)

    Near field image at APSPRSTAB:10,022802(2007)TargetEffective source sizeat target = ()/2

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersKEK results (slit target)

    Imax

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersKEK SummaryElectron beam energy=1.28 GeV, =2505Bunch intensity = 1.2 x 1010Beam size = 10 m, divergence= 3.8x10-3(1/)Impact parameter ~ 5yDetected wavelength = 0.56 mSynchrotron radiation background from dipole 8m upstream; used a maskODR intensity = 58% of OTR intensityMeasured sensitivity to beam size ~ 14 m

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersAPS 1010 10 16

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersAPS Summary Electron beam energy = 7GeV, = 13,699Bunch intensity ~ 1.9x1010 (3 nC). Tevatron proton intensity ~ 43 nCBeam sizes: x = 1375 m, y = 200 mTypical impact parameter ~ 6 y Wavelength ~ 0.83 mODR signals observed up to 16 y ODR signals (@ 6 y) about 10% of OTR signalSensitive to horizontal offsets of 50-100 mSensitive to beam size changes of 20-50 m

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersHadron colliders: key parameters

    Tevatron RHIC LHCEnergy [GeV]Bunch intensityTarget clearance [] Beam size [m]Wavelength[m]Beam div/opening angleFar-field distance [m] 9802.7x101112 839914.42.9x10-3

    2.5 250 2x101112 810121431.2x10-5

    1.6 70001.1x101112 88074.15.7x10-3

    36.1

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersDifferent target shapesStraight edge APS (near-field), KEK (far-field)

    Rectangular slit KEK (far-field)

    Round hole

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersRound holeIntensity distribution from a single particle (PSF) depends only on these parameters g, u, Otherwise it does not depend on the inner radius a/a< Scaled frequency u = / cN = (/)f u2 F(g, u) /

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersFar-field spectral distributions (round hole)For g =1.1,Number of photons emitted /bunch/turn N ~ 1.6 x 106

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersRectangular Slit Angular spectral distribution from a bunch depends onSlit widthRMS sizeBunch transverse offsetObservation angles x, y

    tx= x, ty = y

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersFar-field spectral distributions (slit)Wavelength dependenceLHCTEVBeam parameter dependence

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersFar-field spectral distribution(straight edge)Characteristic c = 2b/At b = 4.8mm, c = 28 m (TEV)Spectrum at > 0.2 c

    Photon yield/bunch/turn

    At = 2 c or =14 m, N = 4.4 x 106 photons/bunch/turn

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersInterferometryBeamInterference from multiple aperturesForward DR from 1st target interferes with backward DR from 2nd targetInterference pattern is sensitive to beam divergenceDistance between targets should be comparable to far field distance. Rules this out for the LHCMay be difficult for very small beam divergencesFDRBDR

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersODR location in the TevatronDrift space around C0 is 11m4 dipoles upstream, 2 dipoles downstream in the proton directionBeta functions are in the range 60-85mPreferable to image pbars closer to the 4 dipoles ?

    11 mprotonsOptics around C0

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersEmpty space in C0

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersLHC InsertionRegular arc dipoles are ~260m from IPWeak separation dipoles (~1.5T) at 60m from IPODR monitor would be stationed between the detector and 1st quadrupole left and right side of IR260m260m

    ODR for Hadron colliders

  • Measuring *, *Beam size, hence , is measured at +L, -L * = [(-L) (+L)]/4L* = ( [< >2 + 4(1+ *2)L2]1/2 - < >)/2) < > = [(-L) + (+L)]/2This measurement of *, * is independent of optics errors

    T. Sen; 10/18/2007ODR for Hadron collidersIP-LL

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersLayout in the LHCIP5: Horizontal Crossing AngleIP1 : Vertical Crossing Angle

    bbBDR ConeBDR ConeTarget at 45 to beam direction Beam 1Beam 2

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersDesign decisionsLocation of the target; both beams should not be present simultaneously, far enough from dipoles, Determine the synchrotron radiation background at the targetDetermine the optimal shape and material of the targetNear-field/Far-field imaging or bothDetermine the optimal wavelength rangeIf IR, deal with the challenges of IR detection (sensitivity, water vapor absorption, window material, )

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersChoice of windowQuartz has almost no transmission between 10 and 50 microns. Might work for RHIC (~140microns)Diamond would be the material of choice for IRCourtesy: FLASH

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersGoals for Tevatron measurementsInstall ODR monitor in 2008 shutdownMeasure two beam parameters with good reproducibility for a single beam Either beam size and beam position ORBeam size and beam divergenceMeasurements in both planes ?Measure parameters for several bunchesUpdate measurements every N turns

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersPros and Cons of ODR in the LHCPros. Non-invasiveBeam size measurement near the IP on both sides, hence beam size at the IP Measurement itself will not be influenced by optics errorsThis can be used to diagnose gradient errors in the IR.Relative beam position measurements can be compared against BPM measurements in the IR. A tomographic reconstruction of transverse phase space may be possible from measurements over several turns. ConsSlower than synchrotron light monitor. Signal will have to be integrated over several bunches.Errors associated with the measurement are not well known at the moment. Installing a device in the Tevatron would determine the limits of resolution with this device.The ODR monitor would be installed between the TAS and the 1st quad. Impact on the machine-detector interface needs to be better understood.

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersMajor LHC issuesWhat are the major benefits of imaging close to the IP?How do the errors associated with the ODR measurement compare to the errors from propagating the synchrotron light monitor measurement in the arcs to the IP?How fast can the ODR measurements be made?What is the level of synchrotron radiation background at the ODR target?

    ODR for Hadron colliders

  • T. Sen; 10/18/2007ODR for Hadron collidersNext StepsDesign ODR setup in the Tevatron E0 preferable. Develop a collaboration with US labs and CERNPresent proposal to the LARP collaboration for funding a LARP task (April 2008)Proceed with experiments Develop ODR facility for the LHCDetermine potential for future machines: muon collider, ILC,

    ODR for Hadron colliders