15 February 2008

RHIC pp Set-Up:  APEX running from 5:00AM - 5:00PM yesterday.  First test ramp after APEX failed due to leftover chromaticity settings.  Dejan remembers this occurring "many times" in the past when recovering from APEX.  This is one of many instances of loss of configuration control.

Finally there was an overnight store with 0.8e11 in 109 bunches giving 2.7kHz at PHENIX. 

The tape did not remove the separation bumps.  Activating the ramp in the RampEditor did. 

Blue polarization is stable near 50% throughout the store.  Yellow polarization is lower, and drops throughout the store.  There is no understanding of why the Yellow polarization drops.

Wolfram emphasized the importance of performing an emittance measurement with the Polarimeter at the beginning of the store.

Blue beam decay is high (110% per hour) at beginning of the store.  The Blue emittance at beginning of store is also large (44pi), explaining the high losses and short lifetime.  Lowering the Blue horizontal tune by 0.001 seems to help somewhat.  Blue bunch length shrinks initially, then starts to grow after one hour.

Tunes are on opposite sides of the diagonal with Blue below and Yellow above.  Blue should be "happier" than Yellow, but it isn't.

Today we will change the ramp tunes to separate the two beams and prevent the emittance blow-up.

Run 109 bunches at 0.9e11 evening and owl shift. 

Perform Polarimeter Target Scan at beginning and end of each store, and measure polarization every two hours.  Call experiments before scans.

Measurements of Blue beam emittance at the end of the store today show values of ~60pi with Target #1 (thin) but only 21pi with Target #5 (thick).  This suggests that the large emittance observed in Blue is a reflection of target peculiarities.  Meanwhile, ZDC-based emittance points at higher values, 30-40pi.  In the process of exploring emittance measurements, it was discovered that all four of the Yellow Horizontal Targets has been lost.  We have no method of measuring the Yellow Vertical Polarization Profile any longer.

The JET lost an RF Cooling coil today and need a 20 minute access today before physics stores begin.  PP2PP also needs a 10 minute access that can fit behind the JET work.  Both of these tasks can probably fit behind a rotator ramp (~30 minutes),