12. July 2002Visit of Jonathan Dorfan to RAL 1

Linear Collider Alignment and Survey

“LiCAS”

12. July 2002Visit of Jonathan Dorfan to RAL 2

Overview

Why and how Oxford wants contribute to a linear collider

LiCAS Phase I (build survey) The survey problem Our solution Our Experience (ATLAS & ZEUS) Our Resources

LiCAS Phase II (online alignment) The alignment problem Steps towards a solution

12. July 2002Visit of Jonathan Dorfan to RAL 3

Why and how Oxford wants to contribute to a

LC ?

Why: Physics ! Our technologies and expertise are applicable to

collider survey and alignment Beam instrumentation work already exists in UK

How: Will be releasing large technological capabilities

from ATLAS construction phase (next two years) This gives ability to take up similar sized project Open mind about other tasks

12. July 2002Visit of Jonathan Dorfan to RAL 4

LiCAS Phase I(TESLA survey, build and repair)

Collider Survey Collider alignment at

build time 200 m (vertical) over 600m

Today’s open air survey technology fails both in speed and accuracy

We want to build survey instrument that matches requirement

Apply our technologies (FSI, straightness monitors) to new problem

12. July 2002Visit of Jonathan Dorfan to RAL 5

Survey & Alignment are difficult

This is the mainbeam line

12. July 2002Visit of Jonathan Dorfan to RAL 6

Special boundary conditions in TESLA

Many beam lines Very tight space (1m wide) Space also serves as

emergency escape route Automated process (induced

radiation environment, re-align without re-opening collider)

Horizontally and vertically curved sections, (Rmin>500m)

Some sections geometrically straight, others following geoid

Some sections with significant slopes

Electronically noisy environment

No long-term stable reference monuments

12. July 2002Visit of Jonathan Dorfan to RAL 7

LiCAS Phase I Automatic survey train measures

reference markers in tunnel wall Later (not too late!!) measure

collider against reference markers

Instrument internal lines in vacuum

Use scalable laser technology (EDFA & telecom style lasers)

Prototype @ DESY during FEL installation

Want same scheme for TESLA & NLC

FSI-distance measurements

straightness monitors

straightness monitor beam

reference markerstunnel wall

single car with sensors

12. July 2002Visit of Jonathan Dorfan to RAL 8

LiCAS Phase I (Our experience with alignment so far)

FSI for ATLAS Large scale O(800 lines) on-line survey system for the

ATLAS inner detector. Optimised for minimum mass Self-calibration to silicon detector’s co-ordinate system

using X-Ray scanning system In large scale production now

Straightness monitors Transparent silicon detector system for ZEUS vertex

detector Similar transparent Si from ATLAS muon system tested on

TESLA undulators for FEL test beam line CCD based system for ATLAS x-ray scanner

12. July 2002Visit of Jonathan Dorfan to RAL 9

LiCAS Phase I & II (FSI extrapolation)

Today: = 117 nm @

L=0.4m L/L = 0.29 ppm

Phase I: =1 m @ L=5m L/L = 0.5 ppm

Phase II: =1 m @ L=10m L/L = 0.1 ppm

7th digit changes

L=4*108nm

=117nm

12. July 2002Visit of Jonathan Dorfan to RAL 10

ATLAS FSI components

Retro Reflectors Quills

12. July 2002Visit of Jonathan Dorfan to RAL 11

Alternative Solutions Alternative scheme:

stretched wire over 25m for vertical position hydrostatic levelling system for horizontal position same train layout but different measurement modules

Drawbacks not suitable for geometric straight or sloping sections

(very important for NLC style collider !) not suitable for “strongly” curved sections many measurement steps to get to a single position slow (many mechanical moves and measurements) lower resolution (limits use as diagnostic tool after

initial survey)

LiCAS

Cast

NikhilKundu

GrzegorzGrzelak

academic

electronic

mechanic

+1 student

Name 01/02 02/03 03/04 04/05 05/06Faculty:

Armin Reichold 30 40 30 30 30Roman Walcak 20 20 30 30

RA:

Ankush Mitra 100

Paul Coe 30 30 60

Grzegorz Grzelak 10 40 50 50 50Electronics:

David Howell 20 50 80 80

Mark Jones 10 50 50 50 50Nikhil Kundu 20 50 50 50 50

Colin Perry 10 10 20 20 20Pete Shield 10 40

Roy Wastie 30 50 50

Mike Dawson 20 40 50 50

Richard Makin 10 40 40 40

Mechanics:

Wing Lau 10 20 30 30 30Brian Ottewell 10 100 100 100 100

Students:

John Green 50 (>Oct.) 50 100 50 + 50 next 100 nextJohn Nixon 100 (>Sept.) 100 (<March)

Edward Botcherby 100(Aug.&Sept.)

Total: ~260 ~520 670 680 680

12. July 2002Visit of Jonathan Dorfan to RAL 14

Project Constraints Timescales:

short term: 1st year, compatible with DESY installation of TTF3 medium term: 2nd-3rd year, compatible with DESY operation of

FEL in TTF3 and similar test-beams else where. long term: 4th- infinity, general development of LC alignment

scheme for both TESLA and NLC Funding:

short term: Oxford PP internal, guaranteed 15K£ Paul Instrument fund, possibly O(60K£),

medium term: PPAP project, Basic Technology fund long term: funding together with LC project on UK scale

Lots of good peopleMany good ideas

Small capital funds

12. July 2002Visit of Jonathan Dorfan to RAL 15

LiCAS Phase II(online alignment)

12. July 2002Visit of Jonathan Dorfan to RAL 16

LCs move… (time scales of ground motion)

70nm

Powerspektrum of ground motion in

various HEP tunnels

LEP: 60 to 180 m/Jahr

12. July 2002Visit of Jonathan Dorfan to RAL 17

…the beam moves even more

(length scales of ground motion)

wavenumber : 1/ [m -1]1/25m

rela

tive

beam

m

otio

n Relative beam motion vs. wavenumber of ground motion But wavelength > 25m do not matter all that much

12. July 2002Visit of Jonathan Dorfan to RAL 18

Magnet Sensitivities (position

dependence)

Sensitivity S of magnets in FF of NLC

Drift < 5Hz < Jitter Drift assumed to be

corrected for by beam

S(Drift): 25nm - 8m S(Jitter): 0.5nm - 2.5

m

<1nm

25nm

<8m

8m

closer to interaction point

12. July 2002Visit of Jonathan Dorfan to RAL 19

Effect on Luminosity (time scale)

TESLA Luminosity versus log(time/sec) assume: ideal beam corrections, ATL groundmotion (HERA)

2s 20s1week

must movemagnets now

12. July 2002Visit of Jonathan Dorfan to RAL 20

LiCAS Phase II(online alignment)

Address “slow” alignment with f<O(Hz) Fixed alignment Grid on most sensitive components (BDS,

final focus) Total length O(1km) Total number of SM stations O(500)

develop cheap camera and readout system Total number of FSI lines O(5000)

Profit from scalability and cheap telecom fibres/amplifiers Add fixed frequency laser to FSI system and use as Michelson

interferometer: FSI gives O(m) absolute alignment Michelson Mode gives O(nm) stabilisation (optical anchor)

Prototype @ DESY in FEL operation ESPI “afterburner” for straightness monitors ??