CLIC TransverseProfile MonitoringCLIC Transverse

Profile Monitoring

CTCCTC

- Critical issue identified for the CDR: ‘1um resolution Laser Wire Scanner’- Foreseen at the end of the Main Linac and in the BDS: Studied by RHUL

- Damping ring & RTML would need as well high precision measurements- DR’s and TA’s

- Based on Synchrotron Radiation (SR) techniques (X-ray, interferometry,..)- LWS could be used as well but more expensive

- Transfer lines:-Thermal limitations of OTR screen in the range of …..- Development of Degradable OTR screen

- Need for non-interceptive beam diagnostic in the Drive Beam Complex- 20-50um resolution but with very high charge beams- Strategy here in the used classical interceptive devices (OTR) up to the thermal limit for screen- Option for Optical Diffraction Radiation, Synchrotron Radiation, LWS:

- ODR could be used in straight section - Simple and cheap- Single shot measurements but no beam profile- Compatible 3-4 screens method instead of Quad scans

- SR and LWS would need in bending magnet and be based on quad scans (need a DUMP afterwards)

CLIC RequirementsCLIC Requirements

Beam energy (GeV)10-2 10-1 1 10 102 103

Beam size (mm)

10-310-

4

10-3

10-2

10-1

1

10

102

DB Injector complex

DB Injector complex

Drive Beam

DB

Decelerator

DB

Decelerator

Main Beam

MB Injector complex

MB Injector complex

RTMLMain Linac BDS

RTMLMain Linac BDS

PDR &

DR

PDR &

DR

CTCCTCCLIC Transverse Beam size CLIC Transverse Beam size

RequirementsRequirements

Beam energy (GeV)10-2 10-1 1 10 102 103

Beam size (mm)

10-310-

4

10-3

10-2

10-1

1

10

102

Zone Of Interest

DB

DeceleratorMB Injector complex

DB Injector complex

PDR

&

DRn Linac & BDS

CTCCTCCLIC Transverse Beam size CLIC Transverse Beam size

RequirementsRequirements

DB

DeceleratorMB Injector complex

DB Injector complex

PDR

&

DRn Linac & BDS

Optical Transition Radiation

Limited by charge density

Optical Transition Radiation

Limited by charge density

OTR

Beam energy (GeV)10-2 10-1 1 10 102 103

Beam size (mm)

10-310-

4

10-3

10-2

10-1

1

10

102

Synchrotron Radiation Techniques

Limit ?

Synchrotron Radiation Techniques

Limit ?

SR Techniques

LWS

Laser Wire Scanner

Ultimate resolution ?

Laser Wire Scanner

Ultimate resolution ?

ODR

Optical Diffraction Radiation

Limited by resolution ?

Optical Diffraction Radiation

Limited by resolution ?

CTCCTCAvailable Techniques & limitationsAvailable Techniques & limitations

Beam energy (GeV)10-2 10-1 1 10 102 103

Beam size (mm)

10-310-

4

10-3

10-2

10-1

1

10

102

Optical Transition RadiationOptical Transition Radiation

OTR

Synchrotron Radiation Techniques

Synchrotron Radiation Techniques

SR Techniques

LWS

Laser Wire Scanner

Laser Wire Scanner

ODR

Optical Diffraction Radiation

Optical Diffraction Radiation

CTCCTCPotential Test FacilitiesPotential Test Facilities

CTCCTC

- Main Beam: 321 bunches with 3.72x109 electrons- Assuming a reduced repetition rate ~1Hz during the measurement: For quad scans: beam should be dumped afterwards

- Limited for thermal resistant screen (~3000oC): Max ~ 250um2 size density

- For a single bunch ~ 10um2: Would work but close to the limit (DR & RTML)

Thermal limitations of OTR Thermal limitations of OTR screensscreens

1 104 1 10

3 0.01 0.1

1

10

100

1 103

1 104

1 105

1 106

1 107

Beam size (cm)

Tem

pera

ture

incr

ease

(de

gree

s)

TMB dMB ( )( )

- Drive Beam: 70128 bunches with 5x1010 electrons

-For the full beam, it only works if the beam density >10cm2 : Never the Case !

- at the limit with a single Drive Beam: (0.36mm2)

- Can be foreseen for the DB Decelerator because the beam envelope is becoming larger

CTCCTC

- Impact parameter to produce visible photons depending on the beam energy

Spatial resolution limitation of ODRSpatial resolution limitation of ODR

1 103 1 10

4 1 105 1 10

6 1 107

1 104

1 103

0.01

0.1

1

Relativistic Factor

Impa

ct P

aram

eter

(m

)

IPe e( )

e

- Principle of operation: Observe the interference pattern of diffraction radiation form two slits

‘Position of the peak ~ 1/’

- For DB Energy: a~600um

CTCCTC

- Several machine have already observed ODR- Spatial resolution limitations still to be understood !- Not an absolute measurement ! Method needs cross-calibration: Could be used to measure change in beam size - potentially a candidate for DB complex

Spatial resolution limitation of ODRSpatial resolution limitation of ODR

1.28GeVLow emittanceObserved size: 10-70um

7GeVObserved size: 200-1000um

Signal distortion in near field: if the observer is at a distance L <

CTCCTC

- Laser Wire Scanner:- Demonstrate the resolution: Followed up by RHUL in test facilities:

- ATF2 (1um resolution: Main Beam system)- PETRA (~ Drive Beam system)- CESR-TA ?

- Integrate the monitor in the different areas of the CLIC complex: ‘Simulation‘- Design of the detection system – including bends if necessary- First study in the CLIC main tunnel by Greg Penn in 2003- Estimate the level of background – Acceptable beam loss level

- Develop the technology: ‘Lab’- High power Optical fiber laser for simplicity and cost optimization (Studied by Oxford / JAI)- Optical system and distributed systems for cost optimization- Develop detector for very high energy scheme

- Synchrotron Radiation: to be followed through DR collaboration - Point spread function techniques: (done in PSI)- X-ray optics (done in several places: DESY / ALBA ?)- LWS (done in ATF2/KEK – CESRA-TA ?)

- Optical Transition Radiation:- Demonstrate a resolution of 1um: RHUL colleagues in ATF2-KEK- Develop degradable monitor

- Optical Diffraction Radiation: (ATF2 – CESR-TA)- Used for beam sizes in DB complex in Linear section: Cost saving compared to LWS- Used for non interceptive beam energy monitoring along the CLIC Main Beam linac

Next Step for R&DNext Step for R&D

Beam energy (GeV)

10-2 10-1 1 10 102 103

Beam size (mm)

10-310-

4

10-3

10-2

10-1

1

10

102

DB

DeceleratorMB Injector complex

DB Injector complex

PDR

&

DRn Linac & BDS

CTCCTCCLIC Transverse Beam size CLIC Transverse Beam size

RequirementsRequirements