Log entry time 02:27:42 on April 22, 2012

Entry number 377284

We got beam this night from ~22:30. After MCC could send beam into the hall, Pengjia and I checked the slow raster size with empty target. We found that the maximal slow raster size we can use is 0.7V with out fast raster (or 0.62V with fast raster on). If we increase the slow raster voltage, spot_3 plot will start to show hot spots on both up and down side. So we decide to use an asymmetric slow raster: 0.62V on vertical direction and 0.8V on horizontal direction (with fast raster on). We will not crap anything at this raster shape.

After that, we moved the target to carbon hole to center the target. We found that we need to move the target 1mm down to center it. The new target offset is 162404. Halog 377238 shows more details.

Then we moved back to C12_40 target to check the raster again. Everything looks OK this time, so we moved the target to NH3 and start production at this setting.

The final slow raster shape is an ellipse with 0.62V(1.40cm) at vertical axis and 0.80V(1.94cm) at horizontal axis. Notice fast raster will extend the size by 2mm on both axis (1.60cm, 2.14cm).

We lost beam for about one hour form 12:30 to 1:30, after the beam back, we noticed the beam position is off by 0.5 mm on Y direction. We asked MCC to move beam position back. After doing this, we checked the raster pattern with carbon target and carbon hole target. The plots looks good to me.

We moved to NH3 target and start to polarize it at around 2:15.

Below I put several spot_3 plots for reference.

Spot_3 41471 slow raster size 0.75V no fast raster

Spot_3 41473 slow raster size 0.70V no fast raster

Spot_3 41488 slow raster size 0.80Vx0.62V fast raster on