Search found 7 matches

by mugwort
Tue Dec 08, 2009 8:32 am
Forum: The Accelerator
Topic: Beams have bunches in wrong bucket; abort gap??
Replies: 10
Views: 4194

Re: Beams have bunches in wrong bucket; abort gap??

They now have refilled for one bunch into bucket #1. It does seem to have been a Super Proton Synchrotron vs LHC timing issue, per operator's log: B1: CIRCULATE AND DUMP to check that now we inject bunch 1 in bucket 1. Philippe confirms that this is the case but that there is a phase problem between...
by mugwort
Tue Dec 08, 2009 6:36 am
Forum: The Accelerator
Topic: Beams have bunches in wrong bucket; abort gap??
Replies: 10
Views: 4194

Re: Beams have bunches in wrong bucket; abort gap??

Oops, I see I responded hastily to jmayes; at the four crossover points, both beams do share the same pipe, and protons collide head-on (low angle). As somebody stated in the crossover thread, collisions are turned on by shifting beam path rather than bunch timing. Daavery, thanks for the info! They...
by mugwort
Tue Dec 08, 2009 5:54 am
Forum: The Accelerator
Topic: Beams have bunches in wrong bucket; abort gap??
Replies: 10
Views: 4194

Re: Beams have bunches in wrong bucket; abort gap??

The two beams run through separate pipes except at the crossover points, and I've seen diagrams that show the beams being focused and entering the crossovers at a significant angle -- so the site of collisions shouldn't be very timing-dependent. It's also my understanding that the RF system keeps bu...
by mugwort
Tue Dec 08, 2009 4:46 am
Forum: The Accelerator
Topic: From the operator's log...
Replies: 1
Views: 1223

7 Dec Night: beam running, wrong buckets

From the 7-Dec Night shift: 23:22 Precycle ongoing in all sectors. All vac valve open 23:53 All circuits finished precycle 00:54 1x1 bunch injected. Lifetimes ~ 25 hr, Problems with BPMs: not all reading out ... restarting BPM processes on Fesa servers for the BPMs 01:09 We proceed with the injecti...
by mugwort
Tue Dec 08, 2009 4:38 am
Forum: The Accelerator
Topic: From the operator's log...
Replies: 1
Views: 1223

From the operator's log...

The LHC Operator's Logbook is a gold-mine of information, but a little awkward to keep tabs on. So I propose that we post entries of interest to this thread, where they'll be more widely available. Logbook entries are based on shift (starting date, day/evening/night) with timestamped entries, so an ...
by mugwort
Tue Dec 08, 2009 4:31 am
Forum: The Accelerator
Topic: Beams have bunches in wrong bucket; abort gap??
Replies: 10
Views: 4194

Beams have bunches in wrong bucket; abort gap??

As of 8-Dec 0329 (CERN time), the operator reports that the bunches in both beams are about 128 buckets behind where they should be; cause unknown. They're expressing concern because this puts the bunches only 83 slots ahead of the " abort gap ". Does anybody here know what role the abort gap plays,...
by mugwort
Mon Dec 07, 2009 8:15 am
Forum: Portal link and forum suggestions
Topic: Forum question: section/thread for LHC at-the-moment status?
Replies: 11
Views: 4534

Forum question: section/thread for LHC at-the-moment status?

Which forum board and thread is the appropriate place to chat about short-term LNC news -- for example, asking if anybody knows more about the current Sector 4 refrigerator shutdown? Each such event doesn't deserve its own thread, but I haven't spotted one yet with a suitable subject. Thanks much fo...