A. Dabrowski, 22 January 2008 Bunch length monitoring at CTF3 Anne Dabrowski (CERN) On behalf of all involved CTF3 Technical Meeting 22 January 2008

A. Dabrowski, 22 January /20 Bunch length monitoring Outline  Bunch length manipulation at the CTF3  Diagnostics to monitor bunch length at the CTF3  BPR with WR-28 waveguide port  RFdeflector and Streak Camera  “RF-pickup”  Highlights of Bunch length (and longitudinal dynamics) measurements at CTF3 (2005 – 2007)  New bunch length monitoring required for 2008  and foreseen improvements to the setup of 2007  RF pickup  Combiner ring measurements  Measurements in CLEX CTF3 Technical meeting

A. Dabrowski, 22 January /20 Bunch length monitoring Bunch CTF3 Drive Beam Injector Drive Beam Accelerator PETS Line 30 GHz source Stretcher Delay Loop TL1 (2006) CR (2007) TL2 (2007/2008) CLEX (2008) 30 GHz tests RF photo- injector test Compressor LINAC ≈ 1- 6 ps Delay Loop and Combiner Ring > 8 ps CLEX ≈ 1- 2 ps r.m.s.and Califes < 1 ps r.m.s  monitoring system to be developed CERN & CEA/Saclay CTF3 Technical meeting

Bunch length manipulation using INFN Chicane Klystron V(t) t Accelerating 15 4 Bends INFN- Frascati Chicane BPR & RF pick-up Delay Loop Changing the phase of Klystron 15 to insert a time to energy correlation within the bunch Convert energy correlation into path length modification and time correlation Measure the Bunch frequency spectrum On-crest Acceleration – the bunch length is conserved through the chicane Negative Off-crest Acceleration – the bunch gets longer Positive Off-crest Acceleration – the bunch gets shorter Nominal energy Higher energy Lower energy Measure bunch shape & length using RF deflector and OTR screen MTV A. Dabrowski, 22 January /20 Bunch length monitoringCTF3 Technical meeting

A. Dabrowski, 22 January /20 Bunch length monitoring Diagnostics –  BPR with WR-28 waveguide port power measurement at 30 GHz (see talks Lars Soby, CTF3 collaboration meeting 2003 For given beam current & position, maximise the signal  minimise bunch length ) BPR’s installed in the CTF3:  after injector  After chicane (girder 4)  After INFN/Frascati Chicane end of the Linac. Waveguide port shared with the “RF-pickup”  Combiner ring  TL2 before entrance to CLEX / TBL CTF3 Technical meeting

Focusing element A. Dabrowski, 22 January /20 Bunch length monitoring Diagnostics – Streak CTF3 Max sweep 10ps/mm  2 Optical lines installed in 2006 in and after Delay Loop  2 Optical lines installed in 2007 in Combiner Ring  2008  Optical lines foreseen for CLEX Synchrotron or OTR light from the beam CTF3 Technical meeting

Streak CTF3 Long optical lines to the streak camera Laboratory 2 Optical lines in 2006 Synchrotron Radiation in the Delay Loop OTR in the linac in TL1 Delay Loop  = 8.9ps (2.7 mm) “Nominal” chicane - R56 = 0.45 linac  = 4.5ps (1.4 mm) Sweep speed of 10ps/mm time

Phase coding in the sub-harmonic bunching system Bunch frequency multiplication in delay loop Sweep speed 250ps/mm SR light in the Delay Loop OTR light after recombination Streak CTF

Streak camera sweep speed 500ps/mm Phase Switch ~ 5-6 ns ; 8 % satellite Phase coding in the sub-harmonic bunching system Streak CTF

CR.MTV0451 CR.MTV0496 Optical Chicane New SC lab Streak CTF3 2 new optical lines installed in 2007 on the Combiner ring 2007

A. Dabrowski, 22 January 2008 “RF-Pickup” CTF3 was installed & first data taking in Nov 2006  Non-intercepting device, easy to implement in machine, sub-ps resolution, self calibrating if bunch length scan is performed  RF deflector and/or a streak provide an excellent cross calibration of device PAC07 proceedings: 10/20 Power Spectrum [a.u.] Freq [GHz] Theory (30 – 39) ; (45-69) ; (78-90) & ( ) GHz CTF3 Technical meeting Filters to separate signal into 4 frequency bands 2 down-mixing stages in each band Stage 1 = synthesizer 2-14 GHz Stage 2 = fixed 26.5; 56.5;75 and 157 GHz power spectrum Measure the power spectrum of the beam at each frequency band:

Bunch Length measurement using “RF CTF A. Dabrowski, 22 January /20 Bunch length monitoring Data analysed using a self calibration procedure  Chi square minimization. 16 measurements (corresponding to 16 different phase settings of MKS15) Fit done with lowest 3 mixing stages (< 100 GHz). 19 free parameters fit  3 response amplitudes and 16 bunch lengths CTF3 Technical meeting 0 ps 4 ps Phase MKS 15 (degrees) Goal 2007:  Optimise highest frequency measurement > 143 GHz  Cross calibrate device with RF deflector measurements

RF CTF A. Dabrowski, 22 January /20 Bunch length monitoring Improvements to setup in 2007:  RF Diamond window (0.500 ± mm thick) prototype installed previously ~ 3 mm thick Al 2 O 3  Parabolic 143 GHz (measure beam frequencies (157 ± 14 ) GHz) & re- focus better reflecting signal In 2006 Filter 157 GHz Hardware inc. D-band Waveguide Components, RF Window and fast ADC’s provided by Northwestern Univ CTF3 Technical meeting

Calibration of device – RF Deflector Chicane optics & bunch length measurements Magnetic chicane (4 dipoles) RF Deflector Screen Betatron phase advance (cavity-profile monitor) Beta function at cavity and profile monitor Beam energy RF deflector phase RF deflector wavelength Deflecting Voltage Bunch length  y0 yy Deflecting mode TM 11 RF deflector offRF deflector on 13/25A. Dabrowski, 17 October 2007 CTF3 Technical meetingBunch length monitoring

RF CTF3 - Bunch Length Measurement with the 1.5GHz RF Deflector of the Delay Loop - Maximum power of 20MW = 9.25ps OTR screen  noRF = 0.35mm  0Xing = 2.9mm (6.7ps) RF deflector off RF deflector on : 0 Xing

Measurement RF deflector 2007 Measurement method (“scan” method) Slide H. Shaker Change the 1.5 GHz RF deflector phase and measure the average intensity of a thin band on the middle of screen per each phase. The phase of RFD related to bunch length by c/f factor. (c is speed of light and f=1.5 GHz)  Matlab code written for automisation of the scan Standard deviation * c/f = 2.84 ± 0.35 mm Phase of RFD (degree) Average Intensity

Measurement RF deflector “Single Image” method: 1) Measure the bunch length in monitor in pixel units for a single image 2) Calibrate the monitor by finding the equivalence between pixel unit and length unit (mm) by measuring the relationship between the center of the image position per RF deflector phase Advantage Advantage “Scan” method vs. “Single Image” method:  Avoid non-linearity effects from the screen  Image can be bigger than the screen (improved resolution) Disadvantage Disadvantage “Scan” method vs. “Single Image” method:  Need to assume bunch shape remains constant during the scan Slide H. Shaker Example of Calibration curve for “Single Image” method ref. D.Alesini et al CTFF INFN Used in bunch length measurement from CTF data

Measurement RF deflector 2007 May 2007 Bunch length = 2.45 ± 0.28 mm Phase of MKS constant for 7 measurements, “Scan” method used Bunch Length (mm) Slide H. Shaker December 2007 Wanted to calibrate “RF-pickup” with RF deflector measurements Procedure established, but beam not stable enough for reliable calibration (beam shape not constant, large current contribution in satalites) To be completed in 2008 Bunch Length (mm) Klystron 13 Phase (degree)

Make absolute calibration of the “RF pickup” already installed after delay loop & understand resolution (use RF deflector and compare) Learn from “RF pickup” already installed to design most cost effective solution & sensitive design for bunch length monitoring in CLEX  Selection of down mixing frequency stages  Length of waveguide vs. down mixing closer to machine?  Requirements on ADC’s  Need for 2 stage down mixing?? Save on cost of synthesizer?  Optimal RF window Development of RF pick-up / RF deflector for TL2 and Califes (collaboration with CEA/Saclay)  characterise the longitudinal dynamics of the beam Prepare a new Streak Camera laboratory for CLEX Invest in New Streak Camera ( ± 180 K euro) for CLEX For 2008 A. Dabrowski, 22 January /20 Bunch length monitoringCTF3 Technical meeting

Conclusion A. Dabrowski, 22 January /20 Bunch length monitoringCTF3 Technical meeting  Optical lines to Streak Camera in & after DL successfully measured: ** bunch length, ** 180 degree phase switching & ** Bunch frequency multiplication  Two new optical lines have been installed in CR, to the New CR Streak Camera Laboratory 2007  Bunch length measurements with RF deflector performed using 2 methods  “RF pickup” with improvements in 2007 commissioned to measure bunch length at end of LINAC (or after delay loop)  Absolute calibration of “RF pickup” with RF deflector started  finish focus  Fully characterising the “RF pickup”  Designing a monitoring system for TBL & Califes (collaboration with CEA/Saclay)  characterise the longitudinal dynamics of the beam  Prepare a new Streak Camera laboratory for CLEX  Would need to Invest in New Streak Camera (± 180 K euro) for CLEX

Thank you’s RF-pickup installation acknowledgements and thank you ’ s must be made to: Hans Braun and Thibaut Lefevre for advising and collaboration in the design of the system Alberto Rodriguez for collaborative advice in the Labview Acquisition and DAQ for pickup Roberto Corsini, Peter Urschütz, Frank Tecker, Piotr Skowronski and Steffen Döbert for general collaboration, and in particular for the machine setup of the bunch compression scan to do the first measurement. Stephane Deghaye for Aquiris card installation Jonathan Sladen and Alexandra Andersson general consultation Erminio Rugo and Frank Perret for mechanics Romain Ruffieux and Christian Dutriat for electronics (BLMs & pickup) Mayda Velasco, Northwestern University and DOE Support from the BI groups at CERN All Collaborators on bunch length measurements inc Andrea Ghigo & the Frascati team CTF3 Technical meeting

Extra slides

A. Dabrowski, 22 January /24 Bunch length monitoring TL2 line, bunch length monitoring CTF3 Technical meeting CM.BHL 0100 CCS.MTV 0980 CC.VVS 0900 CC.QFL 0910CC.QDL 0920 CC.BPR 0915CC.BPM 0930 CC.WCM 0960 CC.MTV 0970 CC.VPI 0950 CC.DHD/DVD 0940 CB.VVS 0100 CB.QFM 0110 TL2 line Use this BPR waveguide port as a pickup for bunch length measurements  Design of “RF pickup” still under discussion to optimize resolution and cost (collaboration CEA/Saclay) OTR light from CC.MTV0970 sent to NEW CLEX Streak Camera Laboratory

TBL in 2008 TL2’ line Prototype Module CM.BHL 0100 CCS.DUM 0995 CCS.VPI 0990 CCS.MTV 0980 CC.VVS 0900 CC.QFL 0910CC.QDL 0920 CC.BPR 0915CC.BPM 0930 CC.WCM 0960 CC.MTV 0970 CC.VPI 0950 CC.DHD/DVD 0940 CB.DHD/DVD 0140CB.DHD/DVD 0130 CB.VVS 0100 CB.QFM 0110CB.QDM 0120 CB.BPM 0150 CB.PET 0220 CB.BPS 0210CB.QDR 0200 CB.MOV 0205 CB.VPI 0215 CB.VPI 0135 TL2 line TL2 spectrometer 17 th December 2007 CB.WCM 0132

TL2 Magnet Layout 1 st October 2007 BHH 0200 BHG 0500 BHH 0600 BHH 0700 BHG 0800 BVA 0300 BVB 0400 SHC 0120SHD 0110 QFG 0140QDG 0160 QFH 0210 QFH 0180 QFL 0270 QDL 0280 QDH 0220QFH 0230 QDH 0330 QFH 0350 QDH 0370 QDL 0430 QFL 0450 QDL 0470 QFL 0530 QDL 0550 QFL 0570 QFL 0620 QDL 0650 QFL 0680 QFL 0730 QDL 0750 QFL 0770 QDD 0820 QFD 0840 DHD/DVD 0175 DHD/DVD 0125 DHD/DVD 0225 DHD/DVD 0265 DHD/DVD 0345 DHD/DVD 0435 DHD/DVD 0525 DHD/DVD 0615 DHD/DVD 0655 DHD/DVD 0765 DHD/DVD 0855 KHC 0250 XLC 0580 XLC 0720 XLA 0630 XLA 0670 All names with prefix CC. Dipoles (Horizontal) 5 Dipoles (Vertical) 2 Quadrupoles 25 Sextupoles 4 Correctors 11 CLEX QFL 0910QDL 0920 e-e- VVS 0900 VPI 0950 BPM 0930 BPR 0915 WCM 0960MTV 0970 DHD/DVD 0940 Bldg 2003 Bldg 2010 SLH 0255

CT and CTS lines CT.BPM 0515 CT. WCM 0525 CT. BPR 0532 CT.VVS 0508 CT.BHD 0510 CT.VPI 0518 CT.QFD 0520 CT.QDD 0530 CT.BHE 0540 CTS.BHB 0800 CTS.PHM 0545 CTS.MTV 0550 CTS.VPI 0842 CTS.MTV 0840 VPG D L T L1 CTS Dump CT.QFH 0610 CT.QFH 0620 CT.XLC 0615 CT.BPI 0608 CT.BPI 0622 CT.DHF 0612 CT.VPI 0600

A. Dabrowski, 22 January /24 Bunch length monitoring Bunch length monitoring requirements for CLIC Location in CLIC MachineBunch Length mmps Drive beam Main Beam at injection Beam Delivery System (IP) Main Beam in damping ring before extraction Combiner Rings Bunch length need to be monitored throughout the machine dynamic range 0.1 ps  10 ps