Log entry time 06:25:47 on June16,2004

Entry number 125943

Here's a summary of the runs I took while trying to set up our source configuration for IHWP in:

Run 2179: PITA scan, IHWP in, RHWP = 125 deg
Run 2180: PITA scan, IHWP in, RHWP = 130 deg
Run 2181: PITA scan, IHWP in, RHWP = 135 deg
Run 2182: PITA scan, IHWP in, RHWP = 35 deg
Run 2183: PITA scan, IHWP in, RHWP = 40 deg
Run 2184: Standard run to look at A_Q and position differences with new PC voltages, RHWP = 130 deg
Run 2185: IA scan, RHWP = 130 deg, IHWP in

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I took a series of PITA scans in order to find an angle with a reasonably sized PITA slope, small A_q, and small position differences. Note: Original PC voltages (delta HV = 0) are:
POS = 3.931, NEG = 6.658.

Run 2179: PITA scan at RHWP = 125 deg.  The PITA slope was measured to be 17.06 ppm/V with an offset charge asymmetry of 562.01 ppm.

Run 2180: PITA scan at RHWP = 130 deg.  The PITA slope was measured to be 12.68 ppm/V with an offset charge asymmetry of 626.93 ppm.

Run 2181: PITA scan at RHWP = 135 deg.  The PITA slope was measured to be 6.85 ppm/V with an offset charge asymmetry of 742.98 ppm.

Run 2182: PITA scan at RHWP = 35 deg.  The PITA slope was measured to be 12.06 ppm/V with an offset charge asymmetry of 1035.17 ppm.

Run 2183: PITA scan at RHWP = 40 deg.  The PITA slope was measured to be 8.69 ppm/V with an offset charge asymmetry of 955.79 ppm.

After studying plots of the position differences vs. delta HV along with looking at the PITA slopes and offsets, I chose to run at RHWP = 130 deg.  This angle has a reasonable PITA slope which gives us a nice dynamic range for controlling the charge asymmetry while also giving fairly reasonable position differences.  

I set new Pockels cell voltages in order to zero the charge asymmetry at this waveplate angle.

POS = 3.107
NEG = 7.482

Run 2184 was used to look at the charge asymmetry and position differences at this new setpoint.  During the run I changed the PC voltages to:

POS = 3.044
NEG = 7.545

Run 2185 was an IA scan.  The measured IA slope (from bcm3) was -147.61.  The feedback database was updated appropriately.

Note:  Because we are running with a larger PITA slope than with the IHWP out (x2.85), the outer peak separation is larger, so the bcm asymmetry widths will also be slightly larger (as pointed out by the owl shift crew).

Run 2186 was the first production after my setup.  Here are some preliminary results (IA feedback was on):

A_Q = -1.176 +/- 2.757 ppm
delta_x = 42.27 +/- 22.67 nm
delta_y = 6.806 +/- 17.75 nm