CLIC Transverse Profile Monitoring
Dec 30, 2015
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