Ground motion studies at ATF2 June 11, 2014 Orbit jitter source identification via ground motion studies at ATF2 (Results of the June run) Marcin Patecki, Jürgen Pfingstner and the ground motion team K. Artoos, St. Jannsens, A. Jeremie (LAPP), Y. Renier, D. Schulte and R. Tomas 30 th of May 2014 Many thanks for the support from the ATF team, especially T. Okugi and N. Terunuma

Ground motion studies at ATF2 June 11, 2014 Outline A.Review of the status B.Results of the first week C.Results of the second week D. Results of remote work from CERN E. Conclusions and future plan

Ground motion studies at ATF2 June 11, 2014 A. REVIEW OF THE STATUS

Ground motion studies at ATF2 June 11, 2014 A.1 Work on Synchronisation issues

Ground motion studies at ATF2 June 11, 2014 Problem: Signal used to synchronize GM and beam Signal is generated by increment of beam trigger signal. This is done in an motion controller (details have to be investigated). Large noise on signal, therefore low-pass filtering. Even whole pulses are sometimes lost.

Ground motion studies at ATF2 June 11, 2014 Jointly found solution At the workshop in Annecy in March, the issues was discussed and a solution was worked out. The KEK team will provide us with a signal that should solve all problems in the May run. Thank you! The signal is: Kicker trigger Charge signal > C_min & Bunch stretching ns NIM signal some ms signal

Ground motion studies at ATF2 June 11, 2014 A.2 Data analysis and results from corrected Data

Ground motion studies at ATF2 June 11, 2014 Evaluation of the correlation (r-value) R is the correlation coefficient. Also here the used machine model is very important. No correlation in horizontal direction. Predicted beam motion from measurements is much higher than compared to the model.

Ground motion studies at ATF2 June 11, 2014 Updated model of beam line The updated magnet strengths of the beam line were used to create an updated MADX model The MADX model was compared with the initial and updated FL models The comparison of β values in BPMs locations shows good agreement between updated MADX and FL models and disagreement with FL default model We should always use the updated magnet strengths to create a model (FL or MADX)

Ground motion studies at ATF2 June 11, 2014 Why do we see something without jitter subtraction? In the beginning of the beam line, much more high frequency ground motion than expected (sensor 1 and 2) Other sensors behave like model At this frequency, ground motion is basically uncorrelated Luckily for the experiment the ground motion seems to create much more beam jitter than expected by the model (factor 10). It seems to be beneficial to have more sensors in this region of interest.

Ground motion studies at ATF2 June 11, 2014 A.3 Plans for the experiment in May Synchronisation: Implement and test the new synchronisation hardware and software. Solve the synchronisation issue with the good sinchronization signal. The proper synchronisation should verify the correlation between GM predictions and BPMs readings. Ground motion source: Verify the high-frequent ground motion (20-30 Hz) in the beginning of the beam line by putting more sensors in this region. Check what is the possible source of this vibration. Check if this vibration is correlated with the beam motion.

Ground motion studies at ATF2 June 11, 2014 B. RESULTS OF THE FIRST WEEK

Ground motion studies at ATF2 June 11, 2014 B.1 Synchronisation improvements

Ground motion studies at ATF2 June 11, 2014 Synchronisation signal In the last run, we found a problem with the synchronisation Therefore, Terunuma-san kindly installed Wednesday a new synchronisation signal. The signal is: Trigger gate signal Charge signal (ICT) > & Bunch stretching ns NIM signal some ms signal Treshold Suppresses influence of kicker noise

Ground motion studies at ATF2 June 11, 2014 B.2 Correlation Results

Ground motion studies at ATF2 June 11, 2014 Correlation in from 22 nd of June (r -value) Highest values with the saved model: r x = 0.56 r y = 0.34 Model is not yet up to date. Next week the OTRs will be available to update the model.

Ground motion studies at ATF2 June 11, 2014 Correlation plots of measured and predicted BPM motion for the most favorable BPMs

Ground motion studies at ATF2 June 11, 2014 B.3 Ground motion Measurement

Ground motion studies at ATF2 June 11, 2014 Region with strong ground motion source Two noticable things: 1.Water pipes under girder (probably touching at one point) 2.Heavy objects one the girder (lead bricks, Dipole magnet). This could lower resonance frequency. Q1X Q2X Cooling water pipes

Ground motion studies at ATF2 June 11, 2014 Ground motion around Q1X (sorry for half finishes slides) Sensors beside each other show nearly the same result (no sensor problem) Sensor on ground shows not increased motion

Ground motion studies at ATF2 June 11, 2014 Ground motion further upstream Two Sensor 1.At kicker location on floor (no increase of ground motion) 1.On Q7RX slightly increase (especially at higher frequencies)

Ground motion studies at ATF2 June 11, 2014 Ground motion on the girder and table of Q1X and Q2X Sensor on girder shows different motion than sensor on table with Q1X

Ground motion studies at ATF2 June 11, 2014 C. RESULTS OF THE SECOND WEEK

Ground motion studies at ATF2 June 11, 2014 Sensors on top of quadrupoles Correlation Beam jitter Correlation much higher vertically than before: r y = Correlation horizontally is gone: sensor 3 and 4 have been moved! Beam jitter is about 20% vertically and 5% horizontally.

Ground motion studies at ATF2 June 11, 2014 Predicted vs. measured ground motion BPM in MQF19X In vertical direction A bit of propaganda, since this is the most favorable BPM.

Ground motion studies at ATF2 June 11, 2014 Remove hanging cooling water tube from girder Correlation Beam jitter Vertical correlation is reduced to maximal: r y = Horizontal correlation is gone: sensor 3 and 4 have been moved! Beam jitter is reduced vertically from 20% to 16%.

Ground motion studies at ATF2 June 11, 2014 Turn off the cooling water pipe for the vacuum system Correlation Beam jitter Vertical and horizontal correlation only slightly reduced. Vertical beam jitter is further reduced from 16% to 14%.

Ground motion studies at ATF2 June 11, 2014 D. RESULTS OF REMOTE WORK FROM CERN

Ground motion studies at ATF2 June 11, 2014 Work from the ATF team at the week-end Even though the water has been turned of in the touching pipe, there were mechanical connections to the other pipes. Also the ATF team found a similar situation (touching pipe) for one girder slightly further upstream. Both girders have been moved so that they do not touch the cooling water pipe anymore. Measurements were performed to observe the results on the beam jitter and the quadrupole motion.

Ground motion studies at ATF2 June 11, 2014 Vertical motion (PSD) Motion of Q1X and Q2X is significantly reduced. Only at Q2X there is still a spike at 24.5Hz

Ground motion studies at ATF2 June 11, 2014 Horizontal motion (PSD) Motion of Q1X and Q2X is reduced, but still very large. Could be interesting to measure the transfer function from ground to quadrupole. Sensor 4 is not working (cable is not the problem).

Ground motion studies at ATF2 June 11, 2014 Result after removing of all found cooling water excitations (Wednesday last week) Correlation Beam jitter Vertical and horizontal correlation significantly reduced (nearly gone). Vertical beam jitter is again at a level of about 20%???

Ground motion studies at ATF2 June 11, 2014 Dispersion measurement Sorry for the plots! Horizontal dispersion is normal. Vertical dispersion is far too big 0.6m at highest point. Likely to be an explanation for the increased beam jitter. Horizontal Vertical

Ground motion studies at ATF2 June 11, 2014 Result after removing of all found cooling water excitations and dispersion correction (Tuesday this week) Correlation Beam jitter Vertical and horizontal correlation significantly reduced (nearly gone). Vertical beam jitter is again at a level of about 19%???

Ground motion studies at ATF2 June 11, 2014 E. CONCLUSIONS AND FUTURE WORK

Ground motion studies at ATF2 June 11, 2014 Conclusions With the new synchronisation strategy, there is a significant correlation between the motion sensor data and the BPM measurements. This correlation is even increased, if the sensors are put on top of the quadrupoles: r y =0.75. There is a significant difference of the motion of the girder and the quadrupole, which was not expected (calculate transfer function). Also the girder moves much more then the quadrupole. Two excitations of the girder have been found: hanging cooling water tube and a touching cooling water pipe. After removing them, the beam jitter was reduced from 19% to about %. This factor sqrt(2) corresponds to half the power and therefore half the sources have been removed!

Ground motion studies at ATF2 June 11, 2014 Conclusions cont. The cooling water pipes have been removed from the girders. A second position further upstream was also found where the pipes touch the girder (has been removed as well). Surprisingly the jitter has been again about 20%! Possible guess to explain the observations: –By moving the pipes, a new source has been introduced (pipes touching somewhere else)? Possible future work Equip the two quadrupoles further upstream temporary with sensors (high radiation area) to observe is there is motion correlated with the beam jitter. We have now a way to create sufficient beam jitter to measure correlation (hanging tube). We could start correcting this correlation (Marcin’s PhD?).

Ground motion studies at ATF2 June 11, 2014 Thank you for your attention!