Interaction Region Issues and Beam Delivery R&D

• Issues & IR Design Status• R&D Plans

T. Markiewicz

Klaisner Review

4/15/1999

Interaction Region Issues

Final Quadrupole Support & IR Layout

Effect of 10 mrad crossing angle and Detector Solenoid

Stabilizing the final quads against jitter @ the 1-5 nm level

Detector Backgrounds

IP Backgrounds

Machine Backgrounds

Topic SubTopic Speaker

CollimationMuon Spoiler System Lew Keller

IR TransportOverview & Energy Expandibility Peter TenenbaumTolerances & Tuning Peter Tenenbaum

Interaction Region

Crossing Angle and Solenoid Effects Peter TenenbaumBackground Calculations Takashi MaruyamaDetector Model Knut SkarpaasREC as Final Doublet IR Magnets Andy Ringwall

Extraction LinesExtraction Line Optics Yuri NosochkovExtraction Line Diagnostics Mike Woods

CollimationWakefield Tests Peter TenenbaumNovel Collimator Designs Joe FrischMaterial Survival Tests Joe Frisch

Small Spot Size IssuesVibration Stability Mike WoodsOther ideas for FD stability Joe Frisch

Design Issues

R&D

MagnetsBeam Line Magnets Andy RingwallMovers & Supports Andy RingwallIR Magnets Andy RingwallPower Supplies Andy RingwallCables Andy Ringwall

VacuumVacuum System Leif Eriksson

CollimatorsCollimators & Stoppers Eric Doyle

Beam Dump Dieter Walz

InstrumentationBeam Line Instrumentation Eric Doyle

RFCrab Cavity RF System Joe Frisch

Facility RequirementsBeam lines Knut SkarpaasIR Halls Knut Skarpaas

Engineering Status & Costs Sessions

Detailed Talks Pre-Prepared for this Committee

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LCD Small Detector with L* =2m CD1 Optics

Plan View

M1

M2Q1 Q1-SC Q2

Q1-EXT

10 mrad

Support Tube

Lum

RF Shield-10 mrad

Tunnel Wall

Beam Pipe

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Bz versus z, NLC IR Solenoid 1

Bz,

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z, m

Bz, T

L*

Uniform Current Density Coil

Crossing Angle and Solenoid Field Issues

Crab Cavity (~6m from IP):– Relative phase stability 1/20 degree S-BAND required– Not a problem

Before the collision:– Beam deflected: 1.7 m , 34.4 rad – Dispersion: 3.1 m added to vertical spot size– Solutions:

• Clever optics:– Tune upstream FF and SCS skew-quad systems– Move Q1 2.6 m CCY sextupoles 1.4 m

• Flux excluder around Q1 NOT needed• ~800 G-m Dipole steering magnet between Q1 and the IP NOT needed

After the collision:– Steering: position (m) & angle (~rad) different from B=0 case– Solution:

• Only run with solenoid ON• Realign extraction line when necessary

Engineering

Final Doublet Magnet Technology Choice

Q1: Rare Earth Cobalt (REC: Sm2Co17 or Sm1Co5)•smaller mass works better with active vibration stabilization•no fluids•can it survive B|| (reduces max. pole tip field) and B (demagnetizes over time)?

•For small detector Bz(2m) < 3 T and Br(2m) < 500 G

Q1 SC for tune-ability: can we engineer this away?Q2A & Q2B iron (if it will fit)

Support details•Accommodation for

•piezo actuators•sensor systems

•lines of sight for interferometric sensors•space for inertial sensors

•fast feedback electrodes and kickers•beam monitoring and physics detectors

•Detector access•Vacuum flanges•Mask supports

Luminosity Monitor Detail

Background Simulation Status

“Engineered” LCD Small Detector in 6 Tesla w/ appropriate masks in GEANT3

Correct non-cylindrically symmetric geometry

Non-uniform magnetic field

Giant Dipole resonance and eN high energy neutron production

Extraction Line and Dump modeled as well

Machine Backgrounds

Synchrotron RadiationMuons ProductionDirect Beam Loss*

•Beam-Gas•Collimator edge re-scattering

Neutron back-shine from DumpExtraction Line Losses

IP Backgrounds

Disrupted primary beamBeamstrahlung photons

e+,e- pairs from beams. interactionsHadrons from beams. interactions

Radiative Bhabhas

Backgrounds

Machine Backgrounds

Synchrotron Radiation: 1996 results need updating

•Less serious than pair background

•Need to investigate SR from disrupted beam

Muons: 1996 result needs updating

•Four 9m long tunnel filling dipole steel dipole magnets per transport line

•100% beam can be dumped on a collimator and get < 1 muon in detector

Dump Neutrons: active effort; NOT dominant neutron source because of

•Concrete shielding around dump

•Concrete end-plug between detector door and pit wall

Beam Loss: need to begin this work

•1996 estimates showed zero re-scattered beam made it to Q1

>10 500 GeV hits on Q1 up-beam face needed before source became a detector problem

Extraction Line Beam Loss: active effort

•Recent redesign limits power lost to < 4 kW (x10 improvement)

•Need to add detectors

IP Backgrounds

Degraded e-,e+:

Energy acceptance of extraction line

Beamstrahlung photons: 1.5E10 per bunch @ <E>=30.3 GeV (0.83 Mw)

Use e+e- dump

Angular distribution set beam line length and minimum magnet apertures

e+e- pairs: 88000 per bunch @ <E>=10.5 GeV (1.7 W)

Dead cone and mask geometry

Direct hits in VXD: ~10% of secondary production

Secondary production of e+, e-, , neutrons:

VXD and tracking chamber backgrounds

VXD radiation damage lifetime

Hadrons with large pT (mini-jets)

Detector issue, will ignore here

e- e+

e- e+

e+

e-

Extraction Line Diagnostics

Standard Diagnostics: Facilitate transport to dump with minimal loss– BPMs, toroids, ion chambers

Detailed simulations needed to design Lum and Physics detectors

Luminosity Monitors:– Deflection scan BPMs

– Pair monitors

– Radiative Bhabha monitors

Physics Detectors: – Compton polarimeter

– Energy spectrometer

– Wire scanner (E)

– Colinearity detectors

– Small angle electron taggers

– Instrumented masks

– Beamstrahlung monitors

RF– Low and High power tests of crab cavity phase stability

Magnets – RECs

• Effects of external fields on various REC choice of materials• Prototypes, aging, thermal, and radiation effects

– SC Q1:• Design and testing

– Kickers and Septa: always a challengeVacuum: Cu is current choice (Al(out-gas rate) and Stainless(high R))

– Verify outgassing rates– Investigate transition materials and joining techniques for Cu and Al– Develop flanges– Prototype section of beamline

Beam Dumps:– Materials and cooling of window– Water flow patterns

Instrumentation:– Not enough thought here to begin to plan an R&D program

Engineering R&D

Collimator R&D•Accelerator Physics Design Investigations: to begin post - CD1

•Collimator wakefields experiments: work in progress

•Materials Damage

•Calculations

•Analytic: Preliminary calculations done

•ANSYS, EGS

•Beam Experiments

•Single Bunch @FFTB: Initial expt. done; beam size marginal; no damage observed on Cu

•Multi Bunch @ ESA: needs optics to make small spots

•Laser Experiments: understand single shot damage vs. many shot damage

•Collimator Design

•Rotating Solid design

•Cooling & Position accuracy in a high radiation UHV environment

•Bearings, motor, vacuum feedthroughs

•Rotating Solidifying Liquid Metal design

•Surface finish, Adherence, and Corrosion PLUS the above

Small Spot Size and Vibration Control

Achieve 1nm stability via• Site requirements: < 10 nm rms for > 1 Hz and < 200 m

• Compact detector ( to satisfy vibration req. passively)

• Allow for closed loop active feedback with piezo movers on quads (interferometer or inertial sensors)

• Fast intra-train feedback

Snowmass detector with optical anchor

• Interferometric Sensors: Optical anchor – 1 m interferometer + piezo system yields 1nm fringe stability– 10 m interferometer in place but unused– 100 kg quad simulator setup exists

• with piezo movers, capacitive displacement sensors and geophone sensors • Piezos position control with 1 nm resolution demonstrated• Stability measurements with feedback still to come

– Goal: IR mock-up once we know what to mock up

R&D Status on Small Spot Size and Vibration Control

•Inertial Sensors

•Initial discussions have re-opened

question of optimal strategy

•Conceptual designs for sensors presented

• Very fast IP feedback:– Use beam-beam deflection of head of bunch (or pilot bunch) to correct tail

• Goal: ~50 latency ns to correct following bunches of 263 ns long train– Currently only conceptual

• tools in hand to begin design• effort needed

• Tunnel support testing– Jitter requirements are also quite tight– Full prototype test required

R&D Status on Small Spot Size and Vibration Control