2023-03-07

We're operating at 1Hz this morning.  The aim is to store the bunched beam for longer than yesterday and see how long it survives. We first took some data at the same flattop energy as yesterday (~56 MeV) with a 400ms flattop. 

We then reduced the flattop energy to 25 MeV. This is to check whether its possible to avoid the onset of RF noise.

Some issues getting the machine to run 1 Hz but working now

Scope is difficult to trigger at 1Hz, use single trigger mode to solve the problem. In the save_lecroy_data function uncomment the line scope.trigger_mode = TriggerMode.single

Taking beam lifetime data at a range of energies. 

5 sets of data for beam off and beam on at each energy (56, 25, 28, 35, MeV)

Note, at ~25 MeV the beam is near the fouth order resonance so this data may not be reliable for beam lifetime measurements. 35 MeV is sufficiently far away from the resonance.

At the lower energy the second harmonic of the RF noise is the strongest ( in yesterday's data the 4th harmonic was the strongest)

David's analysis shows a higher beam current than yesterday. It could be higher today because there was an issue with the amplitude correction in the AWG script in yesterday's data.

note for residual gas losses calcuation - Vacuum level 1.1e-5 pascal for all data


To check whether the transverse tune is not at the resonances at lower energy, one of the figure in the previous publication helps (see below). To convert from time to energy,

5 ms, 23.374 MeV

6 ms, 26.437 MeV

7 ms, 29.656 MeV

8 ms, 33.028 MeV

9 ms, 36.549 MeV

10 ms, 40.216 MeV

11 ms, 44.025 MeV

12 ms, 47.973 MeV

13 ms, 52.056 MeV

14 ms, 56.273 MeV

We will use 35.183 MeV in the following measurements.

see FFT plots of file 41 and 42 from today, thats the high sample rate, zoomed in data to the end of the cycle in the 35 MeV case. Blue is beam on and orange is beam off. Nice clear side bands

Harmonics 1 through 6 below, and a plot zoomed into first harmonic which also shows the signal window I used. 


NOTE - "EXTRA SPECTRUM" = BEAM OFF,       "SPECTRUM" =  BEAM ON

The peaks either side of the side band appear in both the beam on and beam off data so that is probably noise.