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Beam Delivery

Beam Delivery. Toward the ILC: A Fermilab Community School on R&D Challenges and Opportunities July 25-27, 2007, Fermilab, Batavia, IL. BDS layout. Single IR push-pull BDS, upgradeable to 1TeV CM in the same layout, with additional bends. BDS beamline. Diagnostics. b -collimator.

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Beam Delivery

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  1. Beam Delivery Toward the ILC: A Fermilab Community School on R&D Challenges and Opportunities July 25-27, 2007, Fermilab, Batavia, IL

  2. BDS layout • Single IR push-pull BDS, upgradeable to 1TeV CM in the same layout, with additional bends

  3. BDS beamline Diagnostics b-collimator Sacrificial collimators E-collimator BSY FF 14mr IR Tune-up dump Main dump grid: 100m*1m Extraction

  4. betatron collimation septa MPS coll skew correction / emittance diagnostic polarimeter fast kickers fast sweepers tuneup dump beta match final transformer polarimeter energy collimation IP primary dump energy spectrometer fast sweepers energy spectrometer final doublet

  5. BDS optics for incoming beam FF BSY E-spectrometer Polarimeter E-collimator b-collim. Diagnostics

  6. “Type B” (×4) fast kickers septa polarimeter chicane QFSM1 moves ~0.5 m 500GeV => 1TeV CM upgrade example for BSY Magnets and kickers are added in energy upgrade M. Woodley et al

  7. Collimators & muon walls collimator 2.25m • Collimators: spoiler-absorber pairs • In Final Doublet & IP phase • Spoilers can survive direct hit of two bunches • Can collimate 0.1% of the beam • Muons are produced during collimation • Muon walls reduce muon background in the detectors Magnetized muon wall

  8. Collimators: wakefields & survivability Minimize wakefields: tapered Be ( with thin ~um Cu coating) and Copper in the middle. Recently also considered Beryllium-free design: To avoid damage by 1-2 bunches, beam size need to be large enough at spoilers. Beam tests to study the threshold of damage Field emission in e+ collimators – recent question 0.6 Xo of Ti alloy leading taper (gold), graphite (blue), 1 mm thick layer of Ti alloy Beam damage experiment at FFTB, 30GeV, 3-20x109 e-, 1mm length, s~45-200um2. Test sample is Cu, 1.4mm thick. Damage observed for densities > 7x1014e-/cm2. Picture is for 6x1015e-/cm2

  9. FF with local chromatic correction • Chromaticity is cancelled locally by two sextupoles interleaved with FD, a bend upstream generates dispersion across FD • Geometric aberrations of the FD sextupoles are cancelled by two more sextupoles placed in phase with them and upstream of the bend • If this scheme would be implemented as shown, there will be large second order dispersion left uncorrected. To cancel that: • The -matching section produces as much X chromaticity as the FD, so the X sextupoles run twice stronger and cancel the second order dispersion and chromaticity simultaneously • FF with local chromatic correction can be, for the same energy reach and L*, several times shorter than the traditionally designed FF

  10. IR coupling compensation When detector solenoid overlaps QD0, coupling between y & x’ and y & E causes large (30 – 190 times) increase of IP size (green=detector solenoid OFF, red=ON) without compensation sy/ sy(0)=32 Even though traditional use of skew quads could reduce the effect, the local compensation of the fringe field (with a little skew tuning) is the most efficient way to ensure correction over wide range of beam energies antisolenoid SD0 QD0 with compensation by antisolenoidsy/ sy(0)<1.01

  11. Detector Integrated Dipole • When beams cross solenoid field, vertical orbit arise • For e+e- the orbit is anti-symmetrical and beams still collide head-on • If the vertical angle is undesirable (to preserve spin orientation or the e-e- luminosity), it can be compensated locally with DID • Alternatively, negative polarity of DID may be useful to reduce angular spread of beam-beam pairs (anti-DID)

  12. Orbit in 5T SiD SiD IP angle zeroed w.DID Use of DID or anti-DID DID field shape and scheme DID case anti-DID case The present assumption is to use anti-DID polarity in ILC

  13. Optics for outgoing beam “nominal” Beam spectra E-spectrometer Polarimeter “low P” 250 GeV 100 GeV Extraction optics can handle the beam with ~60% energy spread, and provides energy and polarization diagnostics

  14. Beam dump • 17MW power (for 1TeV CM) • Rastering of the beam on 30cm double window • 6.5m water vessel; ~1m/s flow • 10atm pressure to prevent boiling • Three loop water system • Catalytic H2-O2 recombiner • Filters for 7Be • Shielding 0.5m Fe & 1.5m concrete Window prototype Damage study Remote replacement

  15. Shock wave generation in 18 MW water dumps • Pressure wave in water vessel 22 µs after a 20°C rise in temperature over 10µs beam pulse • Similar to ILC beam dump parameters at shower maximum with rastered beam • Maximum pressure = 120 bar Chris Densham, et al The beam is deliberately off-center in the vessel; waves are generated primarily in radial direction; 1/r reduction; the ILC dump is by a factor of four more difficult that SLC dump in terms of Joules/g – all these factors are helping to make the issue of shock waves not a problem. However detailed studies are needed.

  16. Crab cavity design FNAL 3.9GHz 9-cell cavity in Opega3p. K.Ko, et al old / newHOM coupler 3.9GHz cavity achieved 7.5 MV/m (FNAL) • Based on FNAL design of 3.9GHz CKM deflecting cavity • Initial design been optimized now to match ILC requirements on damping of parasitic modes, and to improve manufacturability • Design & prototypes been done by UK-FNAL-SLAC collaboration

  17. Crab cavity LLRF • LLRF phase and synchronization stability • Required: ~67fsec or 0.094o for <2% luminosity loss (7 cell 1.5GHz cavity at JLab achieved 37fsec) • Design features: digital phase detector, RF interferometer • Simulations predict that specs can be met

  18. Concept of single IR with two detectors detector B The concept is evolving and details being worked out may be accessible during run detector A accessible during run Platform for electronic and services. Shielded. Moves with detector. Isolate vibrations.

  19. Concept of detector systems connections detector service platform or mounted on detector detector low V DC for electronics high V AC 4K LHe for solenoids low V PS high I PS electronic racks 4K cryo-system 2K cryo-system gas system 2K LHe for FD high P room T He supply & return sub-detectors solenoid antisolenoid FD high I DC for solenoids chilled water for electronics high I DC for FD gas for TPC fiber data I/O electronics I/O fixed connections long flexible connections move together

  20. IR integration Final doublet magnets are grouped into two cryostats, with warm space in between, to provide break point for push-pull (old location)

  21. Actively shielded QD0 Shield ON Shield OFF BNL Intensity of color represents value of magnetic field. new force neutral antisolenoid to be prototyped during EDR • Interaction region uses compact self-shielding SC magnets • Independent adjustment of in- & out-going beamlines • Force-neutral anti-solenoid for local coupling correction

  22. IR magnets prototypes at BNL BNL prototype of self shielded quad cancellation of the external field with a shield coil has been successfully demonstrated at BNL prototype of sextupole-octupole magnet winding process Coil integrated quench heater

  23. BNL • Detailed engineering design of IR magnets and their integration has started Service cryostat & cryo connections

  24. IRENG07 Workshop http://www-conf.slac.stanford.edu/ireng07/

  25. Present concept of cryo connection • B.Parker, et al • Result of deliberations of IRENG07 preparatory meetings of WGs

  26. Detector assembly • CMS detector assembled on surface in parallel with underground work, lowered down with rented crane • Adopted this method for ILC, to save 2-2.5 years that allows to fit into 7 years of construction photos courtesy CERN colleagues

  27. Shielding the IR hall 250mSv/h Self-shielding of GLD Shielding the “4th“ with walls

  28. Pacman design Pac Man Open CMS shield opened Pac Man Closed Considered tentative versions Beam Line Support Here SLD pacman open John Amann

  29. Moving the detector 5000 ton Hilman roller module Air-pads at CMS – move 2000k pieces Is detector (compatible with on-surface assembly) rigid enough itself to avoid distortions during move? Concept of the platform to move ILC detector, A.Herve, H.Gerwig, at al

  30. IR alternatives, 0mrad • FD: NbTi @ 500GeV CM (250T/m, 7T/bore); Nb3Sn @ 1TeV CM (~370T/m, 10.5T/bore) • Separator: D=12mm at 55m from IP (to control parasitic crossing beam-beam instability) => 2.6MV/m (±130kV over 100mm gap) & *2 at 1TeV CM), split gap, overlapped with dipole field; low spark rate is essential • Challenges: intermediate ~1MW dump, possible back shine to detector; design of downstream diagnostics Overlapping bends separator

  31. IR alternatives, 2mrad • Focus of latest optics work: trying to design minimal system, shortest, most economical, without downstream diagnostics (added later if new ideas found) • FD reoptimized with new ILC parameters: SC QD0/SD0 &warm QF1/SF1 • FD is NbTi at 500GeV CM (225T/m, 6.3T/bore) and Nb3Sn at 1 TeV CM (350T/m, 8.8T/bore) • Beamline downstream of FD to be designed & studied. Study feasibility of downstream diagnostics, study beam & SR losses and evaluate backscattered background

  32. Test facilities: ESA & ATF2 ESA: machine-detector tests; energy spectrometer; collimator wake-fields, etc. ATF2: prototype FF, develop tuning, diagnostics, etc. ATF2

  33. BDS beam tests at ESA BPM energy spectrometer (T-474/491) Synch Stripe energy spectrometer (T-475) Collimator design, wakefields (T-480) IP BPMs/kickers—background studies (T-488) EMI (electro-magnetic interference) Bunch length diagnostics (T-487) Latest run: March 7-26, 2007~ 40 participants Runs: three 2-weeks runs in 2006 & 07; request two runs in 2008 more in talk of E.Torrence

  34. Collimator Wakefield study at ESA • Spoilers of different shape investigated at ESA (N.Watson et al) • Theory, 3d modeling and measurements are so far within a factor of ~2 agreement

  35. ATF and ATF2

  36. Final Focus Test Beam Achieved ~70nm vertical beam size

  37. Scaled down model of ILC final focus (local chromatic correction) ATF2 – model of ILC BDS ATF2 goals (A) Small beam sizeObtain sy ~ 35nmMaintain for long time (B) Stabilization of beam center Down to < 2nm by nano-BPM Bunch-to-bunch feedback of ILC-like train

  38. ATF collaboration & ATF2 facility • ATF2 will prototype FF, • help development tuning methods, instrumentation (laser wires, fast feedback, submicron resolution BPMs), • help to learn achieving small size & stability reliably, • potentially able to test stability of FD magnetic center. • ATF2 is one of central elements of BDS EDR work, as it will address a large fraction of BDS technical cost risk. • Constructed as ILC model, with in-kind contribution from partners and host country providing civil construction • ATF2 commissioning will start in Autumn of 2008

  39. ATF2 schedule

  40. Advanced beam instrumentation at ATF2 • BSM to confirm 35nm beam size • nano-BPM at IP to see the nm stability • Laser-wire to tune the beam • Cavity BPMs to measure the orbit • Movers, active stabilization, alignment system • Intratrain feedback, Kickers to produce ILC-like train IP Beam-size monitor (BSM) (Tokyo U./KEK, SLAC, UK) Laser-wire beam-size Monitor (UK group) Laser wire at ATF Cavity BPMs with 2nm resolution, for use at the IP (KEK) Cavity BPMs, for use with Q magnets with 100nm resolution (PAL, SLAC, KEK)

  41. BPM at ATF & ATF2 Nano-BPM work: use cavity BPMs of BINP and KEK design, put them in triplet in metrology frame, and find resolution. So far achieved ~15nm resolution Sean Walston (LLNL), et al ATF2 will use primarily the cavity BPMs (> 30). ATF2 will be (one of the) first large accelerator system that rely entirely on cavity BPMs. Issues of reliable signal processing, first pulse calibration, are crucial Y.Honda (KEK), et al

  42. ATF & ATF2 J.Nelson (at SLAC) and T.Smith (at KEK) during recent "remote participation" shift. Top monitors show ATF control system data. The shift focused on BBA, performed with new BPM electronics installed at ATF by Fermilab colleagues. T.Smith is commissioning the cavity BPM electronics and the magnet mover system at ATF beamline Improvement of soft & hardware for remote participation

  43. High Availability PS for ATF2 ILC-like High Availability (HA) power supplies developed for ATF2. HA is provided by redundancy (“four out of five” configuration). Stimulated failure and recovery in the redundant module configuration KEK colleagues at SLAC for PS review

  44. FD magnets & IR integration • The FD stability requirements are in the 100-200nm range • luminosity reduction is 1-2%, 5%, 15-20% for rms FD vibration of 100nm, 200nm and 500nm, correspondingly (with fast IP feedback) • Very rough estimation, comparing with existing cryo magnets of completely different design which show 0.3-1micron level vibration, tell that the needed improvement is about a factor of three to five BNL developing optical methods to measure vibration of cold mass. Recently started to develop methods to measure nm level motion of magnetic center of quads with use of stabilized long coils.

  45. Final doublet for ATF2 (SC at 2nd stage?) • The final doublet for the ATF is built with conventional quadrupoles and sextupoles, placed on movers. The FD is placed on a table with specially developed support. • Stability of the FD built with ILC-like technology could be tested at ATF2 at the second stage, once the primary goals are reached Mover

  46. SC FD for ATF2, tentative Brett Parker, BNL Nov.2005 version FD designed with the same approach as for ILC: QD0 and QF1 with skew and dipole correctors and combined sextupole-octupole packages with skew sextupoles. The coils would be wound on a single tube with 30mm radius of the aperture, and placed in a common cryostat. For ATF2, either the super-fluid He or normal He can be used. To match the design to low energy of ATF2, the coils would be wound with single wire (not with 7 strand cable), which would also decrease the needed current, make current leads easier, and would also allow to have six layers and allow to measure and correct the field harmonics during manufacturing.

  47. BDS Movers • Need 5dof, 50nm step movers. • FFTB movers achieved ~300nm step • Being developed by D.Warner, Colorado State University • Also need mover for FD (move QD0 cryostat as a whole) – that should be compact (fit in small space between FD and detector), radiation resistant, with small sub um step, and should not amplify vibration

  48. HTS quads for extraction line • Ramesh Gupta (BNL) made a fist look on the use of HTS quads for ILC extraction system • Based on HTS R&D quad built for RIA • HTS quads allow large loss on the coils and may in a long run prove economical

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