Log entry time 01:49:28 on June18,2004

Entry number 126142

We wanted to remeasure the PITA slopes because of the injector work done today.

Run 2229 - PITA scan, IHWP in, RHWP = 6500
PITA slope = 11.79 ppm/V = 707.4 ppm/DAC V
A_Q offset = 226.87

Run 2230 - IA scan, IHWP in, RHWP = 6500
IA slope = -154.53 ppm/DAC V

Run 2231 - PITA scan, IHWP out, RHWP = 2250
PITA slope = -3.69 ppm/V = -221.4 ppm/DAC V
A_Q offset = -662.28 ppm

Run 2232 - IA scan, IHWP out, RHWP = 2250
IA slope = -154.18

The IA slope didn't change too much, but I did update the panFFB.db file for IA feedback.

The new PC voltages for IHWP in are:

POS = 3.837, NEG = 6.752

There is a large offset in the IHWP out charge asymmetry.  This is quite a mystery since it was only a couple of days ago when we ran at this setpoint with a very small charge asymmetry.  I'm not sure what the reason is for the drift.  Certainly, it could be a result of the injector work done today.  I talked to Gordon about this for a bit, and it seems that it could be because of phase gradients of the linear polarization incident on the PC; therefore we have to work to get rid of our sensitivity to these gradients by changing the voltages on the PC significantly.  Because the slope didn't change very much, we believe that this change isn't due to the RHWP.

When we switch(ed) to the IHWP out setting, the PC voltages will be (are):

POS = 3.427, NEG = 8.366

If the IA begins to work very hard, and we run out of lever arm on our PITA feedback, we will have to do a local (perhaps full) RHWP scan to pick a different location to give us a larger PITA slope perhaps or a zero crossing in charge asymmetry while maintaining the criterion for small position differences.