18 December 2007

RHIC Startup:  Ran stores last night, but lost the Blue clock causing PHENIX to be unable to take data.  Also lost the ability to dump the beam cleanly.  So when the beam was dumped, there was a real quench as well as a BLAM 90% alarm (90% of hourly radiation limit reached, shutting us off for an hour).  It appears the blue cogging was lost when the RF clock synch stopped. 

There was an attempt to scrub the vacuum yesterday afternoon by repeatedly filling at highest intensity at injection energy.  Monitoring vacuum levels at STAR showed that scrubbing did not succeed in raising the vacuum pressure even as much as standard colliding beam.  Further "scrubbing" will be accomplished by production stores.

PHENIX lost a Low Voltage Power Supply when they lost the beam synch.  They needed to make an access to replace that PS.  STAR also took advantage of the BLAM down time to take a short access.

STAR is still concerned about the background rates.  Their minimum bias trigger is only about 40% efficienct (60% of these triggers are accidental). 

As soon as the morning meeting ends, dump the current store, then Don Bruno will load the new lattice.  While digesting the results of that work, there will be a new store put up with the reduced beta* in Yellow.  Then there will physics stores until the APEX starts at about 8:00PM tonight (or later.  All of the work Don does this morning will be subtracted from the front end of the APEX schedule).