Interaction Regions Working Group T1

1
Interaction Regions Working Group (T1)

• Final Report
• T.Markiewicz, F.Pilat

Snowmass 2001
Plenary Session Snowmass, July 19
2
Overview

• Introduction
• Hadron colliders
• Lepton-hadron
• ee- linear colliders
• gg collider
• ee- ring colliders
• m-m colliders
• Conclusions

3
Hadron Colliders

• Review Tevatron, RHIC operational experience, LHC
  design
• ? VLHC Stage 1 and Stage 2
• Hadron IR issues
• IR design layout, flexibility, upgrade
• IR components magnets, powering
• IR performance LR beam-beam, field quality,
  alignment
• IR corrections local, feedback, beam-beam
  compensation
• Energy deposition background, IR component
  protection
• Integration machine-experiment
• ? RD program

4
IR design VLHC Stage 1

• Triplet optics (antisymmetric)
• Triplets 300 T/m
• 4 matching quads 70 T/m
• Dm fixed
• b 6 ? 0.3 m
• Crossing angle /- 77 mrad
• 10 s at the first parasitic crossing

RD IR magnets (M.Lamm, S.Zlobin, T2) LHC
upgrade Nb3Sn 250 T/m 90mm bore VLHC-1
Nb3Sn 300 T/m 70mm bore Goal short model FY05-08
10M prototype FY08-10 20M

5
IR design VLHC Stage 2

• Doublet (flat) symmetric
• Doublet 400-600 T/m
• Dm fixed
• bv 7.12 ? 0.37 m
• bh 71.2 ? 3.7 m

Triplet solution exists, similar to Stage 1
optics

• Flat optics?separate, then focus
• Final doublet design challenging
• 2-in-1, high gradient, neutral debris
• RD (M.Lamm, R.Gupta, B.Parker, T2)
• double bore HTS IR quads 400-600T/m
• Separation dipoles 12-16 T
• Goal short model by FY12-16

6
Flat ? round optics
Flat beam pros LR horizontal tune shift 20x
smaller LR vertical tune shift 2Xsmaller Flat
beam cons doublet magnet design Neutrons from
IP hit the conductor Lack of (lower) energy
flexibility
flat
round
Snowmass result (J.Johnstone) Optical solution
with 4 FF IR quadrupoles exists that allows
continuous transition from flat (doublet) to
round (triplet) - very attractive! RD optimizat
ion of design development of FF quadrupoles
7
IR Correction Systems

• To relax tolerances ?cost effective design
• To improve operational performance

• RD
• Development of a collaborative beam
• experiment program at existing laboratories
• (Snowmass conclusion, M4-T1) in the next
• 3-6 years to address
• beam-beam (LR, coherent modes, etc.)
• test of compensation schemes
• IR correction and feedback
• IBS, diffusion, .
• Phase 1 MD activity
• Phase 2 formally approved experiments

LHC inner triplet and local correctors
8
Energy deposition

• LHC
• 900 W/IR side of collision debris
• generated at nominal E and L
• Machine background few if IP debris
• VLHC-1
• 3 KW/IR side of collision debris
• factor 3 extrapolation is OK
• VLHC-2
• Extrapolation not OK
• 24 KW/IR side of collision debris
• (initial PHYTHIA simulation)
• RD
• Modeling (MARS, PHYTHIA)
• Development of IR protection system
• (collimators, absorbers, etc.)

From Nikolai Mokhov LHC Heat Load
9
Lepton-hadron colliders

• HERA (HERA upgrade) ? eRHIC, EPIC, THERA
• IR Panel on e-hadron IRs (Keil, Peggs, Merminga,
  Willeke, Norem, Hasell, Krasny)
• Luminosity
• Collision frequency optimization among
  conflicting requirements
• Accelerator-experiment integration (components
  teams)
• background, collimation, vacuum, alignment,
  instrumentation
• Head-on vs crossing angle
• SR and backgrounds
• Energy range energy tunability essential to
  match the physics
• RD
• Optimization of collision frequency
• IR FF magnets extensive experience for HERA
  upgrade
• inside detector, large aperture, holes for
  other beam
• good field quality, local correction coils
• Electron cooling for proton beams

10
Basic LC IR Drivers
Bunch Structure Beam-beam effects Small
spot sizes
?Crossing Angle Feedback Design
?IP Backgrounds Pinch Enhancement
?Control position motion of final quads and/or
the beam
11
Backgrounds and IR Layouts

• Most important background is the incoherent
  production of ee- pairs.
• pairs scales with luminosity and is equal for
  both designs.
• Detector occupancies depend on machine bunch
  structure and relevant readout time
• GEANT and FLUKA based simulations indicated that
  in both cases occupancies are acceptable and the
  CCD-based vertex detector lifetime is some number
  of years.
• IR Designs Magnet Technologies
• Differ due to the crossing angle, magnet
  technology choice, and separate extraction line
  in the case of the NLC
• Similar in the use of tungsten shielding,
  instrumented masks, and low Z material to absorb
  low energy charged and neutral secondary
  backgrounds

12
e,e- pairs from beams. gg interactionsare the
most important background
scales w/ L 2.5-5x109/sec
BSOL, L, Masks
13
TESLA IR(Instr. W Masks, Pair-LumMon, Low Z)
14
NLC Detector MaskingPlan View w/ 20mrad X-angle
Large Det.- 3 T
Silicon Det.- 5 T
30 mrad
32 mrad
15
JLC IR8 mrad Design
Elevation View

• Iron magnet in a SC Compensating magnet
• 8 mrad crossing angle
• Extract beam through coil pocket
• Vibration suppression through support tube

16
Detector Occupancies are Acceptable fn(bunch
structure, integration time)
TESLA VXD Hits/BX vs. Radius
LCDL2 Hit Density/Train in VXD TPC vs. Radius
TESLA g/BX in TPC vs. z
17
TESLA SC Final Doublet QuadsMature LHC based
Design

• QD0
• L2.7m
• G250 T/m
• Aperture24mm
• QF1
• L1.0m

18
NLC Final Doublet Quads Compact, stiff,
connection free
Permanent Magnet Option
EXT
QD
Carbon fiber stiffener
nm-mover
FFTB style cam movers
Cantilevered support tube
T2 Compact SC (HERA-style)
19
Extraction and DiagnosticsHandling the Disrupted
Beam
NLC Post-IP Diagnostics Common g,e
dump TESLA Pre-IP Diagnostics Separate g e dumps
20
Colliding Small Beam Spots at the IP
Q1
Q1
Relative Motion of two final lenses
e
e-
sy 3-5 nm Dy sy/(4-10) 0.5-1 nm

• Control position motion of final quads and/or
  position of the beam to achieve/maintain
  collisions
• PASSIVE COMPLIANCE Get a seismically quiet site,
  dont screw it up (pumps, compressors, fluids),
  engineer the quad/detector interface
• FEEDBACK Between bunch trains Within bunch
  trains
• SENSE MOTION CORRECT MAGNETS or BEAMS

21
Intra-train Feedback based on beam-beam
deflection at TESLA
Dy25 ? 0.1s0.5nm sensitivity
In 90 bunches and DL lt 10, bunches are
controlled to 0.1sy
22
Very Fast Intra-train IP Feedback at NLC limits
jitter-induced DL
Concept
Design
Performance 5 s Initial Offset (13 nm)
YIP (nm)
40ns Latency
23
RD on Inertial Stabilization to Suppress Jitter
at NLC
Block with Accelerometers/ Geophones
Electrostatic Pushers
x10-100 Jitter Suppression in Frequency Range of
Interest
24
RD on Interferometers to Stabilize Quads w.r.to
Tunnel
Sub-nm resolution measuring fringes with
photodiodes ? drive piezos in closed loop
Measured Displacement over 100 seconds
rms 0.2nm
UBC Setup
25
gg Collider IR

• Laser Development
• Fusion program-funded Mercury laser project
  applicable to gg project is under construction
• Conceptual designs to take the output of the
  laser and to match it to the time structure
  required for either the NLC or TESLA are underway
• IR Optical designs
• to provide the ge collisions have been developed
  and will soon be tested.
• Optics and IP parameters
• improved performance for gg collisions

26
LLNL 10Hz -100J MERCURY Fusion Program Laser IS
Prototype for gg Collider
g-g laser system architecture CPA front
end seeds 12 Mercury power amplifiers
Mode-locked oscillator
Spectral shaper
Stretcher
OP-CPA preamp
0.5 J 3 ns 120 Hz
12- 100 J power amplifiers
Beam splitters
Optics Combiner, splitters
100 J macropulse 100X 2ps micropulses 120 Hz
Grating compressor
27
Diode pulsers
Front end
Gas-cooled amplifier head
Pump delivery
Injection multi-pass spatial filter
28
Matching Laser Output to Accelerator Bunch
StructureKnown Technology gg specific
development planned
8 May 1999
29
Large Diameter gg Annular Optics
Engineered Performance Tests Planned
Out of the way of input beam beam-beam debris
30
Circular ee- IRs

• HOM
• SR
• SR Masks
• Beam Tails
• Orbit Compensation

31
mm Collider IR
Final Focus design using local chromatic
correction scheme of NLC Shielding designs tuned
for 100 GeV, 500 GeV, and 4 TeV
32
Conclusions

• Many IR design issues are common across different
  types of machines
• VLHC IR design has advanced, with the promise of
  both round and flat beam solutions. RD for IR
  magnets and correction systems are priorities.
• The proposed designs for LC IRs look more similar
  than different, are fairly well advanced, and
  have active RD programs
• Viable solutions to gg Laser IR Optics now
  available and give program real credibility

33
NLC/TESLA Beam-Beam Comparison
Larger sz for TESLA More time for
disruption larger luminosity enhancement more
sensitivity to jitter Lower charge density lower
energy photons Real results come from beam-beam
sim. (Guinea-Pig/CAIN) and GEANT3/FLUKA