Transcript Document 7680485

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
Detailed Talks Pre-Prepared for this Committee
Design Issues
Topic
SubTopic
Engineering Status & Costs Sessions
Speaker
Collimation
Muon Spoiler System
Lew Keller
Magnets
IR Transport
Overview & Energy Expandibility
Tolerances & Tuning
Peter Tenenbaum
Peter Tenenbaum
Interaction Region
Beam Line Magnets
Movers & Supports
IR Magnets
Power Supplies
Cables
Andy Ringwall
Andy Ringwall
Andy Ringwall
Andy Ringwall
Andy Ringwall
Vacuum System
Leif Eriksson
Vacuum
Crossing Angle and Solenoid Effects
Background Calculations
Detector Model
REC as Final Doublet IR Magnets
Peter Tenenbaum
Takashi Maruyama
Knut Skarpaas
Andy Ringwall
Extraction Lines
Extraction Line Optics
Extraction Line Diagnostics
Yuri Nosochkov
Mike Woods
R&D
Collimation
Wakefield Tests
Novel Collimator Designs
Material Survival Tests
Peter Tenenbaum
Joe Frisch
Joe Frisch
Small Spot Size Issues
Vibration Stability
Other ideas for FD stability
Mike Woods
Joe Frisch
Collimators
Collimators & Stoppers
Beam Dump
Eric Doyle
Dieter Walz
Instrumentation
Beam Line Instrumentation
Eric Doyle
Crab Cavity RF System
Joe Frisch
RF
Facility Requirements
Beam lines
IR Halls
Knut Skarpaas
Knut Skarpaas
LCD Small Detector with L* =2m CD1 Optics
Plan View
0.4
Tunnel Wall
M2
0.3
Q1
M1
Beam Pipe
Q1-SC
Q2
0.2
0.1
10 mrad
0
0
Lum
2
4
6
8
-0.1
12
-10 mrad
RF Shield
-0.2
Q1-EXT
-0.3
Support Tube
-0.4
10
B versus z, NLC IR Solenoid 1
z
6
Uniform Current
Density Coil
5
L*
Bz, T
4
B,T
z
3
2
1
0
0
0.5
1
1.5
2
z, m
2.5
3
3.5
4
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 mm , 34.4 mrad
– Dispersion: 3.1 mm added to vertical spot size
– Solutions:
• Clever optics:
– Tune upstream FF and SCS skew-quad systems
– Move Q1 2.6 mm CCY sextupoles 1.4 mm
• Flux excluder around Q1 NOT needed
• ~800 G-m Dipole steering magnet between Q1 and the IP NOT needed
After the collision:
– Steering: position (mm) & angle (~mrad) 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
Backgrounds
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. gg interactions
Hadrons from beams. gg interactions
Radiative Bhabhas
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: 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
e+
Degraded e-,e+:
e-
e-
Energy acceptance of extraction line
e+e- pairs:
e+
88000 per bunch @ <E>=10.5 GeV (1.7 W)
Dead cone and mask geometry
e-
e+
Direct hits in VXD: ~10% of secondary production
Secondary production of e+, e-, g, neutrons:
Beamstrahlung photons: 1.5E10 per bunch @
VXD and tracking chamber backgrounds
<E>=30.3 GeV (0.83 Mw)
VXD radiation damage lifetime
Use e+e- dump
Angular distribution set beam line length and
minimum magnet apertures
Hadrons with large pT (mini-jets)
Detector issue, will ignore here
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 (DE)
Colinearity detectors
Small angle electron taggers
Instrumented masks
Beamstrahlung monitors
Engineering R&D
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
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 n > 1 Hz and l < 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
R&D Status on Small Spot Size and Vibration Control
• 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
•Inertial Sensors
•Initial discussions have re-opened
question of optimal strategy
•Conceptual designs for sensors
presented
R&D Status on Small Spot Size and Vibration Control
• 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