Thursday 2nd July 2015 (evening)

Post date: Jul 2, 2015 9:32:30 AM

We measured very little change in fractional tune after increasing the acceleration rate. The synchronous phase was changed from 20 to 35 degrees. We decided to look at the maxima in vertical tunes which occur at 5ms and 14ms with the nominal acceleration rate. The acceleration time was reduced to 2.97ms and 8.93ms at the higher synchronous phase to go into flat-top at the same energies. The fractional tune, measured as usual with the real time spectrum analyser was found to shift by approximately 0.005 in both planes. This may be within the error bar of the measurement. Note - In this measurement the corrector current was maintained at 900A.

Next we decided to start measuring the tune with the corrector current at 700A and at the nominal acceleration rate. At 14ms we found that the fractional part of the horizontal tune increased by about 0.025 while the vertical tune barely changed. In fact the horizontal tune moved close to last year measurement at the corresponding time in the acceleration cycle. We speculate that this shift is caused by amplitude detuning with COD amplitude. We will continue this series of measurements tomorrow.