Wednesday 1st July 2015

Post date: Jul 1, 2015 7:21:50 AM

The final tune measurement, 23ms into the acceleration cycle, was taken this morning completing the set at 900A corrector current. We then spent some time trying out Shinji's rf script to adiabatically transition from acceleration to flat-top. Unfortunately no improvement of beam transmission into the flat-top was observed - in fact the beam loss look greater with a finite transition time (Ishi-san points out it may be debunching rather than actual loss). A kink in the rf waveform can be seen at the transition times and, at the same time, a horizontal line covering all frequencies is seen in the real time spectral analyser. However, both of these features are also seen with zero transition time. We tried various transition times from 1ms to 10ms and, at first glance, saw no improvement.

We have now gone back to taking a couple of more tune measurements at 900A in the region of 14 ms where the tune reaches a peak in the vertical plane.