Abstract

Turn-by-turn beam profile data measured at the Fermilab Booster are studied. Lattice models with experimental accelerator ramping parameters are used to obtain the lattice functions for data analysis. We studied the horizontal and vertical emittance growth behavior in different stages of a booster ramping cycle and its relation to the beam intensity. The transverse and longitudinal components in the horizontal beam width are separated by a fitting model which makes use of the different scaling rules of the beam momentum. We analyze the post-transition horizontal beam size oscillation based on a model where the longitudinal phase-space mismatch has resulted from rf voltage mismatch during the transition-energy crossing. We carried out systematic multiparticle simulation to show that the source of the vertical emittance growth is a combination of the random errors in skew-quadrupole and dipole fields, and the systematic Montague resonance. The effect of random quadrupole field is small for the Fermilab Booster because the betatron envelope tunes are reasonably far away from the half-integer stop band.

Highlights

  • Revolution x10003, 5, 7, etc., injection turns

  • Transition-energy loss is visible at the transition energy at about revolution

  • Since the horizontal beam width is a quadrature of contributions from the betatron motion and the rms offmomentum oscillation, we cannot directly calculate the normalized horizontal emittance unless we can isolate and remove the contributions of the off-momentum contribution

Read more

Summary

INTRODUCTION

The measured rms beam profiles and widths are used to deduce the emittances of the beam. We build a realistic lattice model to analyze measured IPM data and deduce the horizontal and vertical emittances and the rms off-momentum width [7,8,9]. The space-charge force of our model is based on the potential derived from a Gaussian beam distribution, where the horizontal and vertical rms beam radii are updated in each revolution. We employ this particle tracking model to evaluate the effects of random errors in dipole, quadrupole, skew-quadrupole fields on the beam emittances.

THE EMITTANCE MEASUREMENTS
The vertical emittance
Linear growth region
Horizontal emittance
Below transition energy
Across the transition energy
Microwave instability
Bunch mismatch oscillations in the synchrotron phase space
MODELING AND EMITTANCE DILUTION
Modeling algorithm
Energy gain in rf cavities
FODO cells and random linear errors
Space-charge effects
Betatron tunes and the rms beam-momentum spread
Results of numerical simulations
Effect of the half-integer stop band
Effects of the Montague resonance
Effect of the linear skew quadrupoles
Effect of dipole field errors
Effect of rf cavities in the dispersive region
Putting it all together
Other observations
Findings
CONCLUSION
Full Text
Paper version not known

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.