Beam Delivery Toward the ILC: A Fermilab Community School on R&D Challenges and Opportunities July...
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Transcript of Beam Delivery Toward the ILC: A Fermilab Community School on R&D Challenges and Opportunities July...
Beam DeliveryBeam Delivery
Toward the ILC:A Fermilab Community School on R&D
Challenges and OpportunitiesJuly 25-27, 2007, Fermilab, Batavia, IL
Toward the ILC:A Fermilab Community School on R&D
Challenges and OpportunitiesJuly 25-27, 2007, Fermilab, Batavia, IL
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BDS layout
• Single IR push-pull BDS, upgradeable to 1TeV CM in the same layout, with additional bends
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BDS beamline
14mr IR
FF
E-collimator
-collimator
Diagnostics
Tune-up dump
BSY
Sacrificial collimators
Extractiongrid: 100m*1m Main dump
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polarimeterskew correction /emittance diagnostic
MPScoll
betatroncollimation
fastsweepers
tuneupdump
septa
fastkickers
energycollimation
betamatch
energyspectrometer
finaltransformer
finaldoublet
IP
energyspectrometer
polarimeter
fastsweepers
primarydump
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BDS optics for incoming beam
FF
E-c
ollim
ator
-collim.Diagnostics
BSY
Pol
arim
eter
E-s
pect
rom
eter
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QFSM1moves~0.5 m
polarimeterchicane
septafastkickers
“Type B” (×4)
500GeV => 1TeV CM upgrade example for BSY
M. Woodley et al
Magnets and kickers are added in energy upgrade
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• 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
2.25m
collimator
Collimators & muon walls
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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
Collimators: wakefields & survivability
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
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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
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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)
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
without compensation y/ y(0)=32
with compensation by antisolenoid
y/ y(0)<1.01
QD0
antisolenoid
SD0
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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)
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Use of DID or
anti-DID
Orbit in 5T SiD
SiD IP angle zeroed w.DID
DID field shape and scheme DID case
anti-DID case
The present assumption is to use anti-DID polarity in ILC
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Optics for outgoing beam
Extraction optics can handle the beam with ~60% energy spread, and provides energy and polarization diagnostics
100GeV
250GeV
“low P”
“nominal”
Beam spectra
Pol
arim
eter
E-s
pect
rom
eter
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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 prototypeDamage studyRemote replacement
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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.
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old / newHOM coupler
Crab cavity design
FNAL 3.9GHz 9-cell cavity in Opega3p. K.Ko, et al
• 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
3.9GHz cavity achieved 7.5 MV/m (FNAL)
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• 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
Crab cavity LLRF
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detectorB
may be accessible during run
accessible during run Platform for electronic
and services. Shielded. Moves with detector. Isolate vibrations.
Concept of single IR with two detectors
The concept is evolving and details being worked out
detectorA
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Concept of detector systems connections
fixed connections
long flexible connections
detectordetector service platform or mounted on detector
high V AC
high P room T Hesupply & return
chilled water for electronics
low V DC forelectronics
4K LHe for solenoids
2K LHe for FD
high I DC forsolenoids
high I DC for FD
gas for TPCfiber data I/O
electronics I/O
low V PShigh I PSelectronic racks4K cryo-system2K cryo-systemgas system
sub-detectorssolenoidantisolenoidFD
move together
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IR integration
(old location)
Final doublet magnets are grouped into two cryostats, with warm space in between, to provide break point for push-pull
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• Interaction region uses compact self-shielding SC magnets• Independent adjustment of in- & out-going beamlines• Force-neutral anti-solenoid for local coupling correction
Shield ONShield ON Shield OFFShield OFFIntensity of color represents value of magnetic field.
to be prototypedduring EDR
new force neutral antisolenoid
Actively shielded QD0
BNL
23
cancellation of the external field with a shield coil has been successfully demonstrated at BNL
BNL prototype of self shielded quad
prototype of sextupole-octupole magnet
Coil integrated quench heater
IR magnets prototypes
at BNL
winding process
24
• Detailed engineering design of IR magnets and their integration has started
Service cryostat & cryo connections
BNL
25
IRENG07 Workshop
http://www-conf.slac.stanford.edu/ireng07/
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Present concept of cryo connection
• B.Parker, et al• Result of deliberations of IRENG07 preparatory meetings of WGs
27
photos courtesy CERN colleagues
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
28250mSv/h
Shielding the IR hall
Self-shielding of GLD Shielding the “4th“ with walls
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Pacman design
John Amann
Pac Man Open
Pac Man Closed
Beam Line Support Here
CMS shield opened
Considered tentative versions
SLD pacman open
30
Moving the detector
Air-pads at CMS – move 2000k pieces
5000 ton Hilman roller module
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
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IR alternatives, 0mrad
• FD: NbTi @ 500GeV CM (250T/m, 7T/bore); Nb3Sn @ 1TeV CM (~370T/m, 10.5T/bore)
• Separator: =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
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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
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ATF2
Test facilities: ESA & ATF2
ESA: machine-detector tests; energy spectrometer; collimator wake-fields, etc.ATF2: prototype FF, develop tuning, diagnostics, etc.
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BDS beam tests at ESA
Runs: three 2-weeks runs in 2006 & 07;request two runs in 2008
Latest run: March 7-26, 2007~ 40 participants
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)
more in talk of E.Torrence
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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
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ATF and ATF2
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Final Focus Test Beam
Achieved ~70nm vertical beam size
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ATF2 goals(A) Small beam size
Obtain y ~ 35nmMaintain for long time
(B) Stabilization of beam center Down to < 2nm by nano-BPM Bunch-to-bunch feedback of ILC-like
train
ATF2 – model of ILC BDS
Scaled down model of ILC final focus (local chromatic correction)
39
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
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ATF2 schedule
41
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)
Cavity BPMs, for use with Q magnets with 100nm resolution (PAL, SLAC, KEK)
Cavity BPMs with 2nm resolution, for use at the IP (KEK)
Laser wire at ATF
42
BPM at ATF & ATF2
Sean Walston (LLNL), et al
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
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
43
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.
ATF & ATF2
T.Smith is commissioning the cavity BPM electronics and the magnet mover system at ATF beamlineImprovement of soft & hardware for remote
participation
44
High Availability PS for ATF2
KEK colleagues at SLAC for PS review
Stimulated failure and recovery in the redundant module configuration
ILC-like High Availability (HA) power supplies developed for ATF2. HA is provided by redundancy (“four out of five” configuration).
45
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.
46
47
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
48
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.
SC FD for
ATF2, tentative
Brett Parker, BNL
Nov.2005 version
49
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
50
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
51
Stability
PMD/eentecliquid sensor
2hrs puzzle disappeared
Effect of water well pump on ground motion at MI8 (BINP-FNAL study)
52
Instrumentation and other needs
• Alignment system• Deflecting y-t cavity• OTR monitors• PMT & ion chamber loss monitors• Polarimeters *• X synch light profile monitor • BDS BPMs * • BPM based energy spectrometer * • Feedbacks *• SR based energy spectrometer *• Interferometer to measure FD position *• * means that some groups are working on that
53
…Instrumentation and other needs
• Crystal collimation* and halo monitor• MPS system including checking status of fields before next
train• Seismic sensor that works near-FD (magnetic field, radiation,
tight space), such as PMD liquid sensor• Stable supports with movers• Active vibration decoupling of vibration coming via cryo lines
or water cooling pipes, reduction of turbulence produced vibration
• Beam size monitor ideas (such as Y.Honda’s nano-pattern BSM)
• Near IR vacuum system including reliable valves with RF shield
• Real time monitoring of doses (e.g. of beam dump window)• …
54
Thanks to
J.Amann, R.Arnold, F.Asiri, K.Bane, P.Bellomo, E.Doyle, A.Fasso, K.Jonghoon, L.Keller,K.Ko, Z.Li, T.Markiewicz, T.Maruyama, K.Moffeit, S.Molloy, Y.Nosochkov, N.Phinney,
T.Raubenheimer, S.Seletskiy, S.Smith, C.Spencer, P.Tenenbaum, D.Walz, G.White, M.Woodley,M.Woods, L.Xiao (SLAC),M.Anerella, A.Jain, A.Marone, B.Parker (BNL),O.Delferriere, O.Napoly,
J.Payet, D.Uriot (CEA), N.Watson (Birmingham Univ.), I.Agapov, J-L.Baldy, D.Schulte (CERN),G.Burt, A.Dexter (Lancaster Univ.), K.Buesser, W.Lohmann (DESY), L.Bellantoni, A.Drozhdin,V.Kashikhin, V.Kuchler, T.Lackowski, N.Mokhov, N.Nakao, T.Peterson, M.Ross, S.Striganov,
J.Tompkins, M.Wendt, X.Yang (FNAL), A.Enomoto, S.Kuroda, T.Okugi, T.Sanami, Y.Suetsugu,T.Tauchi (KEK), M.del Carmen Alabau, P.Bambade, J.Brossard, O.Dadoun (LAL), P.Burrows,G.Christian, C.Clarke, B.Constance, H.Dabiri Khah, A.Hartin, C.Perry, C.Swinson (Oxford),A.Ferrari (Uppsala Univ.), G.Blair, S.Boogert, J.Carter (RHUL), D. Angal-Kalinin, C.Beard,
C.Densham, L.Fernandez-Hernando, J.Greenhalgh, P.Goudket, F.Jackson, J.Jones, A.Kalinin, L. Ma,P. McIntosh (STFC), H.Yamamoto (Tohoku Univ.), T.Mattison (UBC, Vancouver), J.Carwardine,
C.Saunders (ANL), R.Appleby (Manchester Univ.), E.Torrence (Univ. Oregon), J.Gronberg (LLNL),T.Sanuki (Univ. Tokyo), Y.Iwashita (Kyoto Univ.), V.Telnov (BINP), D.Warner (Univ. Colorado)
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END