2023-03-08

Trying the FAB with no amplifer. 

We tried with Ishi-san's attenuator but this produced too mcuh noise.

Attenuator is not needed if we use a 1 Mohm termination at the scope.

With started by taking data in the 56 MeV case with the amplifier for the FAB still in place.  The 4th harmonic signal is as clear as before with 4ns step size (see figures above). The apparent absence of 4th harmonic noise in yesterday's data was down to the 40ns step size (this was confirmed by calculating the spectrum taking one in every 10 data points in the 4ns case).

Take data at 56 MeV and 35 MeV using the FAB without the Amplifier.  Second harmonic is dominant in both cases.

We see the RF noise even without the amplifier, 2 nd harmonic is still strong. So the it appears that the amplifier is not being saturated.

Even so we will move the FAB later today  to (hoperfully )reduce the noise on bunched beam data

After lunch, Schottky measurements are tried.

• Firstly without the amplifier, AWG script is used to accelerate to 35 MeV, adiabatically debunch, keep the beam without RF for about 350 ms, rebunch and accelerate up to 140 MeV.

Take a date for the whole cycle, ~ 400 ms (from -200 ms to 200 ms, #12-16 on, #17-21 off ), 20 ns/pt

Take  another data, zoom in the first 50 ms (from -180 ms to -130 ms, triggering at -155 ms, #24-28 off, #29-33 on), 2 ns/pt

• Secondly with the amplifierAWG script is used to accelerate to 35 MeV, adiabatically debunch, keep the beam without RF for about 350 ms, rebunch and accelerate up to 140 MeV.

Take a data for the whole cycle, ~ 400 ms (from -200 ms to 200 ms, #34-38 on, #39-43 off), 20 ns/pt

Take another data, zoom in the first 50 ms (from -180 ms to -130 ms, triggering at -155 ms, #44~48 off, #49-53 on) and the last 50 ms (from +110 ms to +160 ms, #54~58 on, #59-63 off), 2 ns/pt

• Finally, change the flattop energy to 56 MeV

Take a data for the whole cycle, ~ 400 ms (from -200 ms to 200 ms, #64-68 off, #69-73 on), 20 ns/pt

Take another data, zoom in the first 50 ms (from -180 ms to -130 ms, triggering at -155 ms, #74~78 on, #79-83 off) and the last 50 ms (from +110 ms to +160 ms, #84~88 on, #89~93 off), 2 ns/pt

E.Y: I have just plotted each data.

(1)  Take a date for the whole cycle, ~ 400 ms (from -200 ms to 200 ms, #12-16 on, #17-21 off ), 20 ns/pt

In these plot, it is hard to see a difference in between beam on/off (h=1).

In these plots, h=10. No spectrum can be seen. 

(2) Take  another data, zoom in the first 50 ms (from -180 ms to -130 ms, triggering at -155 ms, #24-28 off, #29-33 on), 2 ns/pt

(3)  Take a data for the whole cycle, ~ 400 ms (from -200 ms to 200 ms, #34-38 on, #39-43 off), 20 ns/pt (w/ NF amplifier)

Without RF reference waveform, it is hard to know where is the bunched beam. Is it around 180ms?

(4) Take another data, zoom in the first 50 ms (from -180 ms to -130 ms, triggering at -155 ms, #44~48 off, #49-53 on) 

(5) the last 50 ms (from +110 ms to +160 ms, #54~58 on, #59-63 off), 2 ns/pt

Take a data for the whole cycle, ~ 400 ms (from -200 ms to 200 ms, #64-68 off, #69-73 on), 20 ns/pt

(6)  

(7) zoom in the first 50 ms (from -180 ms to -130 ms, triggering at -155 ms, #74~78 on, #79-83 off) ,

Below figures caption: 50MS/s -> 500MS/s!

 (8) the last 50 ms (from +110 ms to +160 ms, #84~88 on, #89~93 off), 2 ns/pt

1. Better resolution with high freq samples (500Ms/s)

2. After 350(?)ms coasting, the signal is weak. Difficult to distinguish the peaks in beam on/off data.

3. Seems averaging data will also work for shcottky analysis?

4. The time constant of the NF amplifier with FAB would be about a few 100us (200-300us). Would this be affecting the data taking of a single particle delta function like signal?  

5. Time constant can be changed by additional shumt impedance before the amp. 

6. It might not change  situation drastically, would it be possible to set the scope next to the ring, with/without amplifier?