Interaction Regions Working Group (T1)

Final ReportT.Markiewicz, F.Pilat

Plenary SessionSnowmass, July 19

Overview

IntroductionHadron collidersLepton-hadron e+e- linear colliderse+e- ring colliders collidersConclusions

Basic LC IR Drivers

Bunch Structure:

Beam-beam effects

Small spot sizes:

TESLA-500 NLC-500

B 337 ns 2.8ns/1.4ns

NB 2820 95/190

f 5 Hz 120 Hz

C 0 mrad 20 mrad

x550 nm 245 nm

y5 nm 2.7 nm

N 2.0 x 1010 0.75 x 1010

z300 m 110 m

Crossing Angle & Feedback Design

IP Backgrounds & Pinch Enhancement

Control position & motion of final quads and/or the beam

Backgrounds and IR Layouts

Most important background is the incoherent production of e+e- 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

e+,e- pairs from beams. interactions

are the most important background

# scales w/ L

2.5-5x109/sec

BSOL, L*,& Masks

TESLA IR(Instr. W Masks, Pair-LumMon, Low

Z)

NLC Detector MaskingPlan View w/ 20mrad X-angle

32 mrad

30 mrad

Large Det.- 3 T Silicon Det.- 3 T

Elevation View•Iron magnet in a SC Compensating magnet

•8 mrad crossing angle

•Extract beam through coil pocket

•Vibration suppression through support tube

JLC IR8 mrad Design

Detector Occupancies are Acceptable fn(bunch structure, integration time)

LCD=L2 Hit Density/Train in VXD &TPC vs. Radius

TESLA VXD Hits/BX vs. Radius

TESLA #/BX in TPC vs. z

TESLA SC Final Doublet QuadsMature LHC=based Design

QD0:

•L=2.7m

•G=250 T/m

•Aperture=24mm

QF1:

•L=1.0m

NLC Final Doublet Quads Compact, stiff, connection free

Permanent Magnet Option

T2: Compact SC (HERA-style)

QD

Carbon fiber stiffener

Cantilevered support tube

FFTB style cam movers

nm-mover

EXT

Extraction and DiagnosticsHandling the Disrupted Beam

NLCPost-IP DiagnosticsCommon ,e dump

TESLAPre-IP DiagnosticsSeparate & e dumps

Colliding Small Beam Spots at the IP

Control position & motion of final quads and/or position of the beam to achieve/maintain collisions

•PASSIVE COMPLIANCE: Get a seismically quiet site, don’t screw it up (pumps, compressors, fluids), engineer the quad/detector interface

•FEEDBACK: Between bunch trains & Within bunch trains

•SENSE MOTION & CORRECT MAGNETS or BEAMS

y ~ 3-5 nm

y = y/(4-10) ~ 0.5-1 nm

Q1 Q1

e+e-

Relative Motion of two final lenses

Intra-train Feedback based on beam-beam deflection at TESLA

In 90 bunches and L < 10%, bunches are controlled to 0.1y

Dy~25 ~0.1~0.5nm sensitivity

Very Fast Intra-train IP Feedback at NLC limits jitter-

induced L

Amp

BPMProcessor

IP Round Trip Delay

+

Amp

Concept

Performance5 Initial Offset (13 nm)

Design

40ns Latency

YIP

(nm)

R&D on Inertial Stabilization to Suppress Jitter at NLC

Block with Accelerometers/

Geophones & Electrostatic Pushers

x10-100 Jitter Suppression in

Frequency Range of Interest

R&D on Interferometers to Stabilize Quads w.r.to Tunnel

UBC Setup

Measured Displacement over 100 seconds

rms = 0.2nm

Sub-nm resolution measuring fringes with

photodiodes drive piezos in closed loop

Collider IR

Laser Development Fusion program-funded “Mercury” laser project

applicable to 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 e collisions have been developed and

will soon be tested.

Optics and IP parameters improved performance for collisions

laser system architecture: CPA front endseeds 12 Mercury power amplifiers

Mode-lockedoscillator

Spectral shaper

Stretcher OP-CPApreamp

Mercury power ampMercury power amp

Mercury power amp

Beamsplitters

12- 100 J power amplifiersOptics:

Combiner, splitters

Grating compressor 100 J macropulse:100X 2ps micropulses120 Hz

0.5 J3 ns120 Hz

LLNL 10Hz -100J “MERCURY” Fusion Program Laser IS Prototype for Collider

Pump delivery

Front end

Injection multi-pass spatial filter

Diode pulsers

Gas-cooled amplifier head

8 May 1999

Matching Laser Output to Accelerator Bunch StructureKnown Technology – specific development planned

Large Diameter Annular Optics

EngineeredPerformance Tests Planned

Out of the way of input beam & beam-beam debris

Circular e+e- IRs

•HOM

•SR

•SR Masks

•Beam Tails

•Orbit Compensation

Collider IR Shielding

Designs tuned for 100 GeV, 500 GeV, and 4 TeV

Conclusions

Many IR design issues are common across different types of machines

The proposed designs for LC IRs look more similar than different, are fairly well advanced, and

have active R&D programs

Viable solutions to Laser & IR Optics now available and give program real credibility

NLC/TESLA Beam-Beam Comparison

)(

2

YXY

ZeeY

NrD

c

bunch

YXZ

ee

B

BNr

)(6

5 2

NLC500 TESLA500

Dy 14 25

0.11 0.06

n 1.17 1.6

b 4.6% 3.2%

HD 1.4 2.1

#pairs/ sec

2.5E9 4.7E9

Larger z 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

Magnet Technology Choices

Permanent Magnets (NLC)Compact, stiff, few external connections, no fringe field to affect extracted beamAdjustment more difficult

Superconducting (TESLA)Adjustable, big boreMassive, not stiff, not compact, external connections

Iron (JLC)Adjustable, familiarMassive, shielded from detector solenoid, extraction through coil pocket