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 the 1-5 nm level Detector Backgrounds IP Backgrounds Machine Backgrounds

Detailed Talks Pre-Prepared for this Committee

LCD Small Detector with L* =2m CD1 Optics Plan View M1 M2 Q1Q1-SCQ2 Q1-EXT 10 mrad Support Tube Lum RF Shield -10 mrad Tunnel Wall Beam Pipe

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: Sm 2 Co 17 or Sm 1 Co 5 ) 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 B z (2m) < 3 T and B r (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 Radiation Muons Production Direct Beam Loss* Beam-Gas Collimator edge re-scattering Neutron back-shine from Dump Extraction Line Losses IP Backgrounds Disrupted primary beam Beamstrahlung photons e+,e- pairs from beams.  interactions Hadrons 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 > 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 =30.3 GeV (0.83 Mw) Use e+e- dump Angular distribution set beam line length and minimum magnet apertures e+e- pairs: per =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 p T (mini-jets) Detector issue, will ignore here 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 challenge Vacuum: 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 Initial expt. done; beam size marginal; no damage observed on Cu Multi 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: 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