1. Sub-Bunch Beam Position Measurements James Miller-Marquez Mentor: Vic Scarpine 08-08-2007

2. What are we doing We are taking beam position data from Stripline Monitors and analyzing sub-bunch transverse motion This measurement is done with anti-proton bunches immediately after they have been transferred from the Accumulator to the Main Injector Beamline Tuner currently used are good at measuring the average position, but do not measure sub-bunch transverse motion

3. Beamline Layout

4. Kicker Magnets The kicker magnets have one job: to move beam from one beamline to another Need to be able to turn on and off very quickly If the beam hits the rising or falling edge of the magnet, the beam will ‘spread out’

5. What the Problem is. The bunches are extracted from the accumulator by a kicker magnet The front edge and/or the back tail of the set of bunches get “tickled” by the kicker’s rising or falling field, causing oscillations in the beam

6. Betatron Oscillations “Betatron Oscillations are the transverse oscillation of particle in a circular accelerator about the equilibrium orbit. “ “Focusing components in the magnetic field provides the restoring force for the oscillation that act to bend a particle off the equilibrium orbit back towards it. In synchrotron accelerators of modern design there are several cycles of betatron oscillation per revolution of beam particles.” Accelerator Glossary of Terms v3.1 : 4/17/06 Accessed 6/14/2007

7. What is a BPM/Stripline Non invasive beam measurement device Detects image charge AB A – B -------- ~= Beam Position A + B

8. What we get out of the stripline (“Raw” Signal)

9. Averaged over 8 points Data Manipulation (A8, A+B/A-B)

10. Position Output Sinusoidal shape Head-Tail motion seen Reflected nature of the sine wave

11. MATLAB Final Output

12. LabView Output

13. Side-by-Side Images

14. Comparison Methodology and Results LabView and MATLAB wrote the amplitude and phase data to file A separate program then took those files and analyzed them by taking the LabView results and subtracted the MATLAB results

15. Problems and Errors Phase angle comparison is not giving any useful results – Possible that two different methods are being used to determine the phase angle – Unable to examine the LabView code to determine method for fitting the phase angle Amplitudes are usually close, but not exact, and the offset is troubling – Possible that the two programs have two different ways of removing the offset that is inherent in the data sets – Some of the difference could be due to how the programs deal with the background A few artifacts remain from the original code that should be removed

16. Conclusion The different programs yield similar results The MATLAB code is more resilient then the LabView code Both programs work and get reasonable qualitative results

17. Acknowledgements Vic Scarpine Dave Slimmer Brian Fellenz Elvin Harms Carl Lundberg Everyone involved with SULI/IPM Very Special Thanks: Mike Hildreth

18. Bibliography Rookie Book: Accelerator Concepts v3.1: 11/16/2006. Accessed 6/14/2007 Rookie Book: Accelerator Glossary of Terms v3.1: 4/17/2006. Accessed 6/14/2007 Shafer, Robert E. Beam Position Monitoring. American Institute of Physics, 1990