1. ODR Diagnostics for Hadron Colliders Tanaji Sen APC

2. T. Sen; 9/12/2007 ODR for Hadron colliders Diffraction Radiation Radiation emitted when a charged particle passes in the vicinity of a conducting target. Two cones (angle ~ 2/γ ) of radiation in the forward and backward direction Two cones (angle ~ 2/γ ) of radiation in the forward and backward direction Key parameters: the impact parameter, beam energy and wavelength of radiation 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. Similar (and different) to transition radiation where a particle passes through the conducting target. Main advantage: Non-invasive Main advantage: Non-invasive Initial theory developed: ~ 1960s Initial theory developed: ~ 1960s First measurements reported: ~1995 First measurements reported: ~1995

3. T. Sen; 9/12/2007 ODR for Hadron colliders Possible Beam Diagnostics Diffraction Radiation Observables Near field (at or near target) intensity Near field (at or near target) intensity Polarization Polarization Frequency spectrum Frequency spectrum Far field angular distribution Far field angular distribution Interference between radiation from 2 sources Interference between radiation from 2 sources These can be combined to potentially measure These can be combined to potentially measure Beam size Beam size Beam position Beam position Beam divergence Beam divergence Energy Energy Recent measurements at KEK, APS, FLASH Recent measurements at KEK, APS, FLASH Interest at other labs: CEBAF, BNL Interest at other labs: CEBAF, BNL

4. T. Sen; 9/12/2007 ODR for Hadron colliders Diffraction Radiation - Layout BDR CCD or PMT Filter Polarizer Target Proton beam b Impact parameter Beam 2Φ2Φ Φ Far field imaging at KEK Phys. Rev Letters 90, 104801 (2003) 93, 244802 (2004) Near field image at APS PRSTAB:10,022802(2007) Target Effective source size at target = (γλ)/2π

5. T. Sen; 9/12/2007 ODR for Hadron colliders KEK results (slit target) Imax

6. T. Sen; 9/12/2007 ODR for Hadron colliders KEK Summary Electron beam energy=1.28 GeV, γ=2505 Electron beam energy=1.28 GeV, γ=2505 Bunch intensity = 1.2 x 10 10 Bunch intensity = 1.2 x 10 10 Beam size = 10 μm, Beam size = 10 μm, divergence= 3.8x10 -3 (1/γ) divergence= 3.8x10 -3 (1/γ) Impact parameter ~ 5σ y Impact parameter ~ 5σ y Detected wavelength λ = 0.56 μm Detected wavelength λ = 0.56 μm Synchrotron radiation background from dipole 8m upstream; used a mask Synchrotron radiation background from dipole 8m upstream; used a mask ODR intensity = 58% of OTR intensity ODR intensity = 58% of OTR intensity Measured sensitivity to beam size ~ 14 μm Measured sensitivity to beam size ~ 14 μm

7. T. Sen; 9/12/2007 ODR for Hadron collidersAPS 10σ 16σ

8. T. Sen; 9/12/2007 ODR for Hadron colliders APS Summary Electron beam energy = 7GeV, γ= 13,699 Electron beam energy = 7GeV, γ= 13,699 Bunch intensity ~ 1.9x10 10 (3 nC). Tevatron proton intensity ~ 43 nC Bunch intensity ~ 1.9x10 10 (3 nC). Tevatron proton intensity ~ 43 nC Beam sizes: σ x = 1375 μm, σ y = 200 μm Beam sizes: σ x = 1375 μm, σ y = 200 μm Typical impact parameter ~ 6 σ y Typical impact parameter ~ 6 σ y Wavelength λ ~ 0.83 μm Wavelength λ ~ 0.83 μm ODR signals observed up to 16 σ y ODR signals observed up to 16 σ y ODR signals (@ 6 σ y ) about 10% of OTR signal ODR signals (@ 6 σ y ) about 10% of OTR signal Sensitive to horizontal offsets of 50-100 μm Sensitive to horizontal offsets of 50-100 μm Sensitive to beam size changes of 20-50 μm Sensitive to beam size changes of 20-50 μm

9. T. Sen; 9/12/2007 ODR for Hadron colliders Hadron colliders: key parameters Tevatron RHIC RHIC LHC LHC Energy [GeV] Bunch intensity Target clearance [σ] Beam size [μm] Beam size [μm] Wavelength[μm] Beam div/opening angle Far-field distance [m] 980 980 2.7x10 11 1239914.4 2.9x10 -3 2.5 250 250 2x10 11 2x10 11121012143 1.2x10 -5 1.6 7000 7000 1.1x10 11 128074.1 5.7x10 -3 36.1

10. T. Sen; 9/12/2007 ODR for Hadron colliders Different target shapes Straight edge – APS (near-field), KEK (far-field) Straight edge – APS (near-field), KEK (far-field) Rectangular slit – KEK (far-field) Rectangular slit – KEK (far-field) Round hole Round hole

11. T. Sen; 9/12/2007 ODR for Hadron colliders Round hole Intensity distribution from a single particle (PSF) depends only on these parameters Intensity distribution from a single particle (PSF) depends only on these parameters g, u, γθ g, u, γθ Otherwise it does not depend on the inner radius a < Otherwise it does not depend on the inner radius a < Number of photons emitted (far-field) Number of photons emitted (far-field) Inner radius a Key parameters  Critical frequency ω c = γc/a <  Radii ratio g = a > /a <  Scaled frequency u = ω / ω c ΔN γ = (β/π)α f u 2 F(g, u) Δ ΔN γ = (β/π)α f u 2 F(g, u) Δω/ω

12. T. Sen; 9/12/2007 ODR for Hadron colliders Far-field spectral distributions (round hole) For g =1.1, Number of photons emitted /bunch/turn ΔN γ ~ 1.6 x 10 6

13. T. Sen; 9/12/2007 ODR for Hadron colliders Rectangular Slit Angular spectral distribution from a bunch depends on Angular spectral distribution from a bunch depends on Slit width Slit width RMS size RMS size Bunch transverse offset Bunch transverse offset Observation angles Observation angles θx, θy θx, θy tx= γθx, ty = γθy

14. T. Sen; 9/12/2007 ODR for Hadron colliders Far-field spectral distributions (slit) Wavelength dependence LHC TEV Beam parameter dependence

15. T. Sen; 9/12/2007 ODR for Hadron colliders Far-field spectral distribution (straight edge) Characteristic λ c = 2πb/γ Characteristic λ c = 2πb/γ At b = 4.8mm, λ c = 28 μm (TEV) At b = 4.8mm, λ c = 28 μm (TEV) Spectrum at ω > 0.2 ω c Spectrum at ω > 0.2 ω c Photon yield/bunch/turn Photon yield/bunch/turn At ω = 2 ω c or λ=14 μm, At ω = 2 ω c or λ=14 μm, ΔN = 4.4 x 10 6 ΔN = 4.4 x 10 6 photons/bunch/turn photons/bunch/turn

16. T. Sen; 9/12/2007 ODR for Hadron collidersInterferometry Beam Interference from multiple apertures  Forward DR from 1 st target interferes with backward DR from 2 nd target  Interference pattern is sensitive to beam divergence  Distance between targets should be comparable to far field distance. Rules this out for the LHC  May be difficult for very small beam divergences FDR BDR

17. T. Sen; 9/12/2007 ODR for Hadron colliders ODR location in the Tevatron Drift space around C0 is 11m Drift space around C0 is 11m 4 dipoles upstream, 2 dipoles downstream in the proton direction 4 dipoles upstream, 2 dipoles downstream in the proton direction Beta functions are in the range 60-85m Beta functions are in the range 60-85m Preferable to image pbars closer to the 4 dipoles ? Preferable to image pbars closer to the 4 dipoles ? 11 m protons Optics around C0

18. T. Sen; 9/12/2007 ODR for Hadron colliders Empty space in C0

19. T. Sen; 9/12/2007 ODR for Hadron colliders LHC Insertion Regular arc dipoles are ~260m from IP Regular arc dipoles are ~260m from IP Weak separation dipoles (~1.5T) at 60m from IP Weak separation dipoles (~1.5T) at 60m from IP ODR monitor would be stationed between the detector and 1 st quadrupole – left and right side of IR ODR monitor would be stationed between the detector and 1 st quadrupole – left and right side of IR 260m

20. T. Sen; 9/12/2007 ODR for Hadron colliders Layout in the LHC IP5: Horizontal Crossing Angle IP1 : Vertical Crossing Angle b b BDR Cone Target at 45 to beam direction Beam 1 Beam 2 Location - Both beams should not arrive at the same time

21. T. Sen; 9/12/2007 ODR for Hadron colliders Design decisions Location of the target; both beams should not be present simultaneously, far enough from dipoles, … Location of the target; both beams should not be present simultaneously, far enough from dipoles, … Determine the synchrotron radiation background at the target Determine the synchrotron radiation background at the target Determine the optimal shape and material of the target Determine the optimal shape and material of the target Near-field/Far-field imaging or both Near-field/Far-field imaging or both Determine the optimal wavelength range Determine the optimal wavelength range If IR, deal with the challenges of IR detection (sensitivity, water vapor absorption, window material, …) If IR, deal with the challenges of IR detection (sensitivity, water vapor absorption, window material, …)

22. T. Sen; 9/12/2007 ODR for Hadron colliders Choice of window Quartz has almost no transmission between 10 and 50 microns. Might work for RHIC (~140microns) Quartz has almost no transmission between 10 and 50 microns. Might work for RHIC (~140microns) Diamond would be the material of choice for IR Diamond would be the material of choice for IR Courtesy: FLASH

23. T. Sen; 9/12/2007 ODR for Hadron colliders Goals for Tevatron measurements Install ODR monitor in 2008 shutdown Install ODR monitor in 2008 shutdown Measure two beam parameters with good reproducibility for a single beam Measure two beam parameters with good reproducibility for a single beam Either beam size and beam position Either beam size and beam position OR OR Beam size and beam divergence Beam size and beam divergence Measurements in both planes (?) Measurements in both planes (?) Measure parameters for several bunches Measure parameters for several bunches Update measurements every N turns Update measurements every N turns

24. T. Sen; 9/12/2007 ODR for Hadron colliders LARP Criteria for ODR What diagnostics does it realistically provide? What diagnostics does it realistically provide? Estimates of the background (synchrotron radiation mainly) and mitigation Estimates of the background (synchrotron radiation mainly) and mitigation Precision and reliability of measurements (understand systematic and random errors) Precision and reliability of measurements (understand systematic and random errors) Advantages/disadvantages of ODR Advantages/disadvantages of ODR Impact on the machine and detector Impact on the machine and detector Does it advance the start of the art? Does it advance the start of the art?

25. T. Sen; 9/12/2007 ODR for Hadron colliders Next Steps Design ODR setup in the Tevatron. Invite collaboration with RHIC, APS ? Design ODR setup in the Tevatron. Invite collaboration with RHIC, APS ? Develop an informal collaboration with US labs and CERN Develop an informal collaboration with US labs and CERN Present proposal to the LARP collaboration for funding a LARP task (April 2008) Present proposal to the LARP collaboration for funding a LARP task (April 2008) Proceed with experiments Proceed with experiments Develop ODR facility for the LHC Develop ODR facility for the LHC Determine potential for future machines: muon collider, ILC,… Determine potential for future machines: muon collider, ILC,…