User name X. Zheng
Log entry time 23:08:31 on July 3,2001
Entry number 65615
Followups:
keyword=Target - EPR D2 signal testEPR D2 signal test:
After gradient test I did 3 FMSweeps to test D2 signal.
10:06pm: FM Sweep with Modulation source 0.025Vpp, attenuator 1:1 (FMS, short)
10:14pm: FM Sweep with Modulation source 0.7Vpp, attenuator 100:1 (AFP, 100:1)
10:18pm: FM Sweep with Modulation source 1.5Vpp, attenuator 100:1 (AFP, 100:1)
The first two FM sweeps are shown here. First one setting is usually used when we try to find D2 signal manually. The lineshape width is about 120 KHz (pk to pk) and ~80KHz for half resonance region.
The second setting was used for AFP sweep measurement. 0.7 Vpp was used based on EEL lab test data. Recently it has been found that the system lose lock-in during the down or up flips. From this plot we can see that the lineshape width is very narrow at this setting (~40KHz pk to pk, and 40KHz for half resonance region). It helps to explain why system cannot track D2 signal during flips: during flips the Rb resonance jumps by >50KHz, which will be out of resonance region.
The third FM sweep will be shown in the next entry.
Note:
Target position: pick-up coil
laser used: #6
parameters used in FM sweep:
starting frequency: 11.440 MHz
step size: 1000Hz
total number of steps: 250
delay between each sample: 500 ms
2 samples per step
RF: 16.0V
To obtain a nicer lineshape spectrum, more samples should be used for each step (more time-consuming)
FIGURE 1
FIGURE 2
