1. MKD Waveform Measurements
C. Wiesner, W. Bartmann, C. Bracco, M. Fraser, C. Hessler, N. Magnin
MKD Generator Meeting
23/05/2017
MKD Generator Meeting

2. Measurement Setup
Measurements were performed on 14/05/2017 for both beams.
The procedure was: We recorded the horizontal beam position on the BTVSE in dependence of the bucket number. We did not use 'inject and dump', but injected and then used a manual operator dump.
23/05/2017
MKD Generator Meeting

3. Measurement Setup
Before, we had prepared an injection pattern for both beams. It worked quite efficiently. Both waveforms were measured with more than 30 shots for each beam in less than 3 hours (compared to the planned 2 to 5 hours for each beam).
New injection pattern for the MKD waveform measurements saved as ’B1B2_bunch_scan_LBDS‘. It can now be reused and modified for future measurements.
Before each scan, we checked the reproducibility of the beam position on the screen for three characteristic points on the waveforms (2 to 4 shots for buckets 1, 281, 681). Then we repeated bucket 1 after the end of the measurement. The shot-to-shot stability was remarkable. The position only changed once for one point by 0.2 mm (screen resolution is 0.2 mm/pixel). For all others it remained constant.
Since the AG keeper was enabled, no measurements of the rise time were performed. Instead we focused on measuring Overshoot 1.
23/05/2017
MKD Generator Meeting

4. Measurement Setup
No measurement of rising edge possible if AG keeper is active.
23/05/2017
MKD Generator Meeting

5. Errorbars: +/- 0.1 mm (0.5 pixel size) and +/- 10 ns (LBDS jitter)
MKD Waveform – Beam 1
Results Beam 1:
In general: MKD waveform measurement fits very well with the measurement done in April 2015 and with the simulations.
Shape and position did not change visibly since 2015 (~0.2mm or less).
MAD-X model based on the measured MKD waveforms, B(I) calibration factors, time delays (eddy currents & signal delays) and calculated time of flight.
Errorbars: +/- 0.1 mm (0.5 pixel size) and +/- 10 ns (LBDS jitter)
Offset corrected for simulated data.
23/05/2017
MKD Generator Meeting

6. MKD Waveform – Beam 1 Zoom on overshoot 1 Δt ≈ 112.5 ns ± 50 ns
Results Beam 1:
T_DELAY correspond to Bucket -45  Δt ≈ ns
Assuming worst-case errors of:
position +/- 0.1 mm
LBDS jitter of +/-10 ns
 Δb = 45 ± 20 buckets*
 Δt = ns ± 50 ns
T_DELAY varies with beam energy. The global delay times has to be chosen such that for the earliest case (assuming worst-case errors) Bucket 1 is placed not earlier than T_DELAY (stronger kick = safe side). How much margin is required?
* Approximation assuming symmetric error
Bucket 1 (2017)
Bucket 1 (2015)
Δx = 0.71 mm
I_REF100PCT
Δt ≈ ns ± 50 ns
T_DELAY
23/05/2017
MKD Generator Meeting

7. MKD Waveform – Delay Times
Earliest case (2-3 TeV): Bucket 1 is placed ~60 ns earlier
Preliminary result: Even considering a pessimistic waveform-measurement error and a possible LBDS jitter of 10 ns, Bucket 1 will not be shifted before T_DELAY.
23/05/2017
MKD Generator Meeting

8. MKD Waveform – Beam 2 Results Beam 2:
Simulation shifted by 0.55 mm
Results Beam 2:
Beam 2: The shape of the measured data fits very well with the simulations.
Compared to the measurement done in April 2015, the absolute value on the screen has shifted by ~0.6 mm.
BI: No change in BTVSE settings since 2015.
Change of beam orbit?
Offset corrected for simulated data.
23/05/2017
MKD Generator Meeting

9. MKD Waveform – Beam 2 Zoom on overshoot 1 Results Beam 2:
T_DELAY correspond to Bucket -48  Δt ≈ ns
Assuming worst-case errors of:
position +/- 0.1 mm
LBDS jitter of +/-10 ns
 Δb = 48 ± 20 buckets*
 Δt = ns ± 50 ns
Applying same logic as for Beam 1:  Even considering a pessimistic waveform-measurement error and an LBDS jitter of 10 ns, Bucket 1 will not be shifted before T_DELAY for the ‘earliest case’ of ~2TeV.
Bucket 1 (2017)
Δx = 0.75 mm
I_REF100PCT
Bucket 1 (2015)
Δt ≈ ns ± 50 ns
T_DELAY
23/05/2017
MKD Generator Meeting

10. Summary
-Beam 1: MKD waveform measurement fits very well with the measurement done in April 2015 and with the simulations. Shape and position did not change visibly. - Beam 2: The shape of the measured data fits very well with the simulations. Compared to the measurement done in April 2015, the absolute value on the screen has shifted by ~0.6 mm. -The shot-to-shot stability was remarkably good (close to the screen resolution of 0.2mm/pixel). - The position of Bunch 1 with respect to T_DELAY leaves enough margin for measurements errors, jitters and operation with all required beam energies.
23/05/2017
MKD Generator Meeting

11. Thank you for your attention!

12. Energy Scan Example: Estimated values for MKD.AB1*:
450 GeV: Bucket 1 is placed ns after T_DELAY (measurement)
800 GeV: Bucket 1 is placed 206 ns after T_DELAY
3 TeV: Bucket 1 is placed 89 ns after T_DELAY
6.5 TeV: Bucket 1 is placed 180 ns after T_DELAY
*quick estimate based on ‘Measurements MKD.UA63.IPOC2.AB1/Waveform from :21:00 to :06:00’. To be checked for all MKDs.
23/05/2017
MKD Generator Meeting