1. ATF nanoBPM system - nanoGrid ATF2 Movers TTF HOM – dipole / monopole
Test Facility Experimental Program ILC Division RD report June 12, 2006 Marc Ross
ATF2 cavity BPMs
ATF nanoBPM system - nanoGrid
ATF2 Movers
TTF HOM – dipole / monopole
ESA/LCLS bunch length
ILCTA
6/12/2006

2. ATF2 Cavity BPM
SLAC group will provide the full cavity system from the hybrid combiner to data server
70 + channels
Beam tests April 10 – 22.
Single ATF2 cavity between the two triplets (no mover)
First look is ‘good’
Data analysis started
Full system delivery delayed
(was to have been June 5) – delay is mid-August.
Following discussions with group at ATF2 meeting
Our first cavity BPM System
Test result documentation (acceptance)
Mechanical
Calibration algorithm
4/24/2006
Marc Ross - SLAC

3. ATF2 Cavity BPM Production electronics
6 GHz receiver board layout
Realistic system design including packaging and mounting hardware
Tested successfully at ATF April 2006
4/24/2006
Marc Ross - SLAC

4. System design
Local configuration
4/24/2006

5. Beam Tests of ATF2 electronics (Y. Honda)
4/24/2006
Marc Ross - SLAC

6. Beam Tests
4/24/2006
Marc Ross - SLAC

7. Beam Tests
4/24/2006
Marc Ross - SLAC

8. Schedule
4/24/2006
Marc Ross - SLAC

9. Do the Nanogrids Help? Data from 13 April 2006 at 22:56:
96 events at nominal position
64 events at +/-20 microns to calibrate
Resolution, no nanogrids
19.1 nm
Resolution, with nanogrids
15.6 nm
4/24/2006
Marc Ross - SLAC

10. ATF Laserwire extraction line near old Compton IP
requires special optics
need wire scanner to confirm
backup lens – real one delayed and lost in the mail (Oxford)
now testing fully corrected lens for operation in November
two graduate students to be posted at ATF all year
Miryam Qureishi (Oxford) and Lawrence Deacon (RHUL)
Guidance from Pavel Karataev (RHUL)
4/24/2006
Marc Ross - SLAC

11. ATF laser – wire scan (May 25)
First scans
Optics and laser aberrations
(factor 10 scale error)
σ = /- 0.4 µm
4/24/2006
Marc Ross - SLAC

12. ATF2 Mover System
4/24/2006
Marc Ross - SLAC

13. Mover shipping and requirements:
4/24/2006
Marc Ross - SLAC

14. TTF HOM studies – plan for August
Goals:
install and commission the HOM BPM DOOCs server
beam tests of HOM SVD algorithm
fast processor HOM board (FNAL)
HOM phase feedback
7 shifts; 2 weeks of beam time July 28 to August 13
A lot of time allocated
3 DESY, 5 Fermilab, 2 SLAC, 2 Saclay staff, ANL, JLab, Cockroft.
Steve Molloy (SLAC) and Nathan Eddy (Fermi) working on analysis
4/24/2006
Marc Ross - SLAC

15. Phase Measurement from Monopole modes
Phase of monopole modes determined by beam phase.
Use fast (5GS/s, 6GHz BW) scope directly measuring HOM signals
Compare HOM monopole phases with 1.3 GHz reference
Not completely straightforward since TTF trigger jitter > 1 cycle of 1.3GHz
Plot phase vs. machine cycle for TM011-7 and TM011-8, and phase difference between modes
Note: measurent uses “accidental” data, taken during other experiment, not optimized.
4/24/2006
Marc Ross - SLAC

16. Higher Order Monopole Modes
2300 – 2500 MHz
Both couplers for 1 cavity shown
0.1 degree (L-band) precision  0.2 ps
Note that different lines have different couplings to the 2 couplers
Monopole lines due to beam, and phase is related to beam time of arrival
Fundamental 1.3GHz line also couples out – provides precise RF to beam phase for control
4/24/2006
Marc Ross - SLAC

17. Beam Phase vs. RF Measurement During 5 Degree Phase Shift
2 cavities, same structure give 0.34 degree L-band RMS phase difference
Measure 5 degree phase shift commanded by control system
4/24/2006
Marc Ross - SLAC

18. What is System Resolution, Drift
Compare 2 couplers on same cavity, RMS difference 0.12 degrees L-band.
Electronics noise ~0.08 degrees
cavity to cavity difference (0.3 degrees may be due to microphonics)
Compare 2 cavities for long (7 hour) run. RMS difference 0.69 degrees L-band.
Combination of electronics drift and cavity to cavity phase shifts.
4/24/2006
Marc Ross - SLAC

19. Summary of Phase System Performance
System noise ~0.08 degrees L-band, 1 minute timescales.
Also measured ~0.1 degree for 10 minutes
Cavity to cavity difference ~0.3 degrees, possibly microphonics.
Drift <0.7 degrees over 7 hours – probably dominated by real cavity to cavity variations.
Cable length change of 10 degrees results in <0.25 degree (consistent with 0) change in measured phase
4/24/2006
Marc Ross - SLAC

20. ESA/LCLS bunch length monitor
This is a ‘single-pass’ device – intended as a ‘relative’ monitor to complement LOLA
Two devices to be built for LCLS BC1
Deadline November 2006
Testing until November 2007
‘CSR’ or focused wave (BL11) and gap monitor (BL12)
Both may use pyroelectric devices
Beam tests in ESA this month
Accurate mm-wave measurements are difficult
Full system relies on integration with LOLA (29-4)
No LOLA in ESA
4/24/2006
Marc Ross - SLAC

21. BL12 Bunch Length Monitor
Located just after the BL11 monitor
Uses gap and diode detectors
Only vacuum component is conventional ceramic gap
Initially instrument with 100GHz diodes
Add higher frequency diodes as needed
Diodes used in pairs to reduce effect of beam motion
20cm waveguide used to disperse pulse (~1ns), keep peak power reasonable on diodes.
20dB gain horns on diodes
4/24/2006
Marc Ross - SLAC

22. BL12
4/24/2006
Marc Ross - SLAC

23. BL12 Development Plan
Similar diodes operating at 100GHz have been tested in End Station B.
Additional test in end station B in April 2006, using same electronics as LCLS
Will use pair of diodes to check measurement noise.
Initial test in LCLS will be done with a pair of 100GHz detectors.
As shorter bunch length measurements are required, additional diodes and waveguide can be added
Use of optical breadboard makes installation of new diodes (on optical clamp mount) straightforward.
Will try using a pyroelectric detector mounted next to the gap.
Should be able to measure total mm-wave power, and compare with toroid current measurement to get bunch length signal
Very simple and inexpensive system if it works.
In principal extends to very short bunch lengths
Must be calibrated with LOLA
4/24/2006
Marc Ross - SLAC

24. ESA Bunch Length Monitor
simple ceramic gap and diode detector
diode and waveguide form crude bandpass filter
200 to 400 um bunch length sensitivity (ILC)
Two 100 GHz detectors track with RMS error of 1.5%
100GHz Diode,
WR10 waveguide
and horn
WR10 and WR90 waveguides
at ceramic gap
4/24/2006
Marc Ross - SLAC

25. Summary – ongoing work and developments since April 2006
ATF cavity BPM’s (UK, UCB, LLNL, KEK)
Near a spectrometer result with 2 triplets+1 (?)
Nanogrid tests – first results
ATF2 BPM cavities (Pohang, KEK, UCL)
1/3 copper cavities done
Electronics delayed 2 months  system issues
ATF extraction kicker (LLNL, KEK) delivered in June
To be used in September 2006
TTF HOM (DESY, KEK, Saclay, FNAL)
System implementation in August
Phase measurements excellent (April 21)
LCLS BLM
first results in May