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Energy and Luminosity Spectrum

Eric Torrence University of Oregon Input from S. Boogert and M. Hildreth

Eric Torrence

1/13

August 2005


Outline

З MDI Questions З Upstream RF-BPM Spectrometer З Downstream SR Spectrometer З Additional Machine Diagnostics З Physics Reference Reactions З Putting it all Together З Work Plan

Focus on CDR issues and critical work for detector concept groups

Apologies for the text-heavy nature of this talk...

Eric Torrence

2/13

August 2005


Brief Introduction
0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 490 492 494 496 498 500 502 504 Root(s) (GeV)

( -, - ), ( +, + ), ... dL -----dE L

0

s Fundamental Goal Spin-dependent absolute collision energy spectrum Typical Components З З З З З Beam Energy Beam Energy Width Beam Polarization Absolute Luminosity Differential Luminosity Spectrum

All are intrinsically related in fundamental goal
Eric Torrence 3/13 August 2005


MDI Questions 14. Do you anticipate a need for both upstream and downstream polarimetry and spectrometry? What should be their precision, and what will the effect of 2 or 20 mr crossing angle be upon their performance.

SiD Reply: Both Long reply (M. Woods) stressing redundancy and complimentary systematics for both. GLD Reply: Both Short reply, similar sentiment. Also highlighted difficulty of downstream measurements. LDC Reply: Should be answered in common amongst all concepts. The ball is in our court here. Pressure will be to reduce costs. Far too early to give up on both upstream and downstream. Need to assess performance in 2 mRad and 20 mRad
Eric Torrence 4/13 August 2005


Upstream Spectrometer 100 ЕRad

RF BPMs ~10 meters З З З З

1 mm

Bends ~ 100 ЕRad, lengths 10 m, 1 mm bump Need 100 nm (or better) resolution and accuracy Move BPMs to the beam (keep same relative position) Calibrate alignment by ramping chicane (bipolar best)

Concept, Layout, and Design Many details to be refined, but basic concept is probably good enough for CDR Operational Strategy З What is the operational strategy? What kind of ramps and how often? З What limits luminosity during ramps? Can machine auto-correct? З Ramp strategy must be consistent with precision field maps! Real thought needed here Needs to be decided for CDR (in my opinion) Need space for extra correctors? Optics problems?
Eric Torrence 5/13 August 2005


Upstream Spectrometer Issues Inspired by M. Hildreth email BPM Issues З nBPM gives 20-30 nm, but aperture too small З Mechanical stability over length limits to ~100 nm? З Need dedicated spectrometer BPM design (one plane only? rectangular designs?) З Is 1000:1 range:precision rule of thumb absolute? З Is this really just an electronics issue? Work has already started, but more spectrometer-specific BPM efforts necessary.

Magnet Issues З Magnet technology (warm steel vs. SC) З Field mapping and in-situ instrumentation З End-fields dominate B dl uncertainty Not necessarily CDR issues, but need serious work

Eric Torrence

6/13

August 2005


Downstream Spectrometry
Polarimeter Chicane Energy Chicane
BHEX3A z=190.06 m x=-- cm BHEX3B z=192.36 m x=-- cm BYCHIC z=~198 m x=-- cm BYCHICM z~208 m x=-- cm

Ken Moffeit - June
2 mrad extraction line

Focus z~214 m
2rd

BYCHICM z~218 m x=----- cm

BYCHIC z~228 m x=----- cm

2 mRad Extraction Line
Plan View
10 cm 10 m
BHEX2 z=129.060 m x=71.25 cm SEXF2 z=116.66 m x=63.98 cm QEXF5 z=123.060 m x=67.73 cm

BHEX3C z=194.66 m x=-- cm

Stripe Detector
Beam Stay Clear +- 10 cm

Synchrotron

Angle 10.563 mrad

20 x 50 cm
BYCHIE z~ 131.0 m x= cm BYCHIE z~151.0 m x= cm BYCHIE z=154.4 m x=----- cm

BYCHIC z=174.4 m x=----- cm Angle 3.621 mrad Angle 5.242 mrad

Angle 2.0 mrad

Angle 8.850 mrad Angle 7.138 mrad Angle 5.425 mrad Angle 3.712 mrad

Compton IP

BHEX4C z=m x= cm

BYCHIC z=106.46 m x=58.00 cm

QEXF4 z=112.460 m x=61.52 cm

QEXF4B z=118.860 m x=65.27 cm

Angle 6.863 mrad

SR Detectors

BHEX4B z= m x= cm BHEX4A z=~232 m x= cm

BHEX4D z= m x= cm BHEX4E z= m x= cm

BYCHICM z=82.360 m x=43.87 cm BYCHIC z=60.364 m x=30.973 cm

BYCHICM z=84.460 m x=45.10 cm

SEXF1 z=28.861 m x=12.51 cm QEXF1 z=26.161 m x=10.92 cm QEXF1B z=31.061 m x=13.79 cm Beam Stay Clear +- 10 cm

Angle 5.863 mrad

20 cm
Photon Beamstrahlung Cone +- 1 mrad

1 mRad Cone Wigglers
8 meters

Angle 2.0 mrad at IR

Y

Sextupole Quad Quad Quad

Stripe Detector

Synchrotron

2nd Focus 214 meters
Cerenkov Detector
17.8 cm 35 GeV
1 .3 2 cm

10 cm 5 cm 0 -5 cm -10 cm Dispersion = 66 cm 250 GeV

Beam Stay Clear 10cm

Side View

Compton IP
Angle -3 mrad Angle 3 mrad Angle 2 mrad

25.1 GeV

Angle -3 mrad

Angle 3 mrad

Dispersion = 20 mm 250 GeV

C Detector
Vacuum Chamber

Beam Stay Clear 10cm

Dispersion = 66mm 250 GeV

25 GeV

Wiggler Low Field
25 GeV

Energy Slit
Eric Torrence

3 mRad
25 GeV

2 mRad SR Detectors

Stripe Detector

Synchrotron

K Moffeit 20 Apr 05

7/13

August 2005


Downstream Spectrometer Design What is done З Basic concept and detector strategy З Sketch of 2 mRad and 20 mRad extraction geometry to accommodate spectrometer and polarimeter What is not done З Feasibility of components - large apertures, shielding e.g.: wiggler is not at all "standard" or "trivial" З Simulation of beam transport including realistic tracking, stray doublet fields, solenoid, DID, etc. Key Work З Get IP to dump simulation working with BDSIM, gradually include more realistic features. З Specify/design realistic elements, esp. wiggler З Assess 2 mRad and 20 mRad performance including background estimates, shielding, stayclear tolerances, etc. Interested parties welcome here...
Eric Torrence 8/13 August 2005


Machine Diagnostics Need to have specifications in CDR for additional machine instrumentation useful for energy and lumi-spectrum measurements

З Energy spread at end of linac Continuous relative monitor of core energy width. Conventional wisdom is "wire scanner" at chicane. Where does the fit in the instrumentation section? What is the expected performance?

З Energy vs. z bunch profile This would be tremendously useful for monitoring linac wakefield effects, key part of collision biases. Does this really work at the ILC, where does it fit, can it be used as more than an MD diagnostic?

Input from machine instrumentation people needed...
Eric Torrence 9/13 August 2005


Physics Reference Channels Bhabha acolinearity З Best input for lumi spectrum shape З Strong requirements on performance of forward tracking and calorimetry? 200 mRad З Reasonably well studied analysis Е + Е - "Radiative Returns" З Potentially best measure of s correct for any collision bias З Only possibility for WW threshold? З Actually used at LEPII serious detector systematics
cos 1 0.9 0.8 0.7 0.6 0.5 200 300 400 500 600 800 1000 Collision Energy (GeV)

e+e- Еe+e-

e+e- Е ЕЕ

1 2

Need precise tracking to ~100 mRad 0. 1 % per event ( Z limit) 1 =
2

Absolute angle known to 10-4 Not a CDR issue for machine, but directly impacts detector concepts

Eric Torrence

10/13

August 2005


Other Reference Channels ZZ qqll З Useful as cross check of s З Lower statistics, but less detector systematics than Z З Only briefly considered (that I am aware of) З Ultimate resolution/accuraccy unknown... e+e- Е

Bhabha/Mu-pairs direct energy/momentum З Could potentially cross-check drifts in s З Limited by detector calibration and resolution З Already envisioned for detector calibration? 1 2 e+e- Еe+e-

Also related: t-channel WW for polarization Need more detector effort on forward tracking, esp. systematics. Forward tracking needs as much care as lumi monitor... Possibility to design specific calorimeter rings to improve performance? Physics benchmarks do include Bhabhas and ЕЕ need to raise awareness of importance in some detector groups
Eric Torrence 11/13 August 2005


Putting it all Together Need to demonstrate that lumi spectrum can be extracted from available inputs and fed back into physics analysis Generation Layer Simulation Layer Analysis Layer Machine Parameters GuineaPig Physics Generator beam params output beams four-vectors

dL/dE Extraction

Physics

Partly technical check of parameterization and technique, partly demonstration that there aren't loopholes in logic. Exploit G. White's work on IP feedback simulations Integrate into ILC generators for easy use by physics groups. S. Boogert - working on extracting machine parameters from Glen's files into convenient format for generators...

Eric Torrence

12/13

August 2005


Possible Snowmass Work BPM performance and operational strategy D. Miller, M. Hildreth, M. Ross?

IP -> Dump Simulations E. Torrence w/ help from BDSIM experts (i.e.: Carter)

Statement on Machine Diagnostics M. Ross, G. Blair?

Highlight Reference Physics Reactions to Concepts T. Barklow, others? Worth preparing a short talk on this for concepts?

Full Lumi Spectrum extraction and application S. Boogert
Eric Torrence 13/13 August 2005