Search found 168 matches

by mfb
Mon Aug 28, 2017 11:16 pm
Forum: The Accelerator
Topic: 2017 Operation
Replies: 72
Views: 6280

Re: 2017 Operation

The machine operators made a table. It is ... not that nice. 2 fill attempts with 2556 bunches, both dumped during ramp due to 16L2. 7 fill attempts with 2220 bunches, 5 dumped during ramp due to 16L2, one dumped before SB for another reason, only one reached SB - only to get dumped by 16L2 later. 3...
by mfb
Mon Aug 28, 2017 12:12 pm
Forum: End Of The World
Topic: Creating "Sparks"
Replies: 163
Views: 69580

Re: Creating "Sparks"

There are only 2 facts what make such an scenario very unlikely: chriwi is missing the most obvious one: There is no possible reaction. What would the process be? Proton -> what? Every possible result has more energy than a proton. This is different for fission, where the fission products are light...
by mfb
Mon Aug 28, 2017 8:48 am
Forum: The Accelerator
Topic: 2017 Operation
Replies: 72
Views: 6280

Re: 2017 Operation

The pumps are running, of course. The gas is mainly frozen out at the walls. Heating the part up was the approach to get rid of the gas, but it can also release gas that was trapped elsewhere. We had a nice long run with 1550 bunches, 100% design luminosity. Just 60% of the previous peak performance...
by mfb
Sat Aug 26, 2017 12:56 pm
Forum: The Accelerator
Topic: 2017 Operation
Replies: 72
Views: 6280

Re: 2017 Operation

They reduced the meetings to Monday/Wednesday/Friday (with an additional meeting tomorrow). 16L2 is the problem, dumping most of the fills, typically during the ramp or quickly after. Some of the dumps are from beam 1, some from beam 2, which is quite strange. Actually, the dump signal does not come...
by mfb
Tue Aug 22, 2017 9:00 am
Forum: The Accelerator
Topic: 2017 Operation
Replies: 72
Views: 6280

Re: 2017 Operation

Data collection slowed down notably. We still get above 30/fb this year with the current speed, but it is certainly not optimal. Let's hope they solve that issue.
by mfb
Thu Aug 17, 2017 8:53 am
Forum: The Accelerator
Topic: 2017 Operation
Replies: 72
Views: 6280

Re: 2017 Operation

They tried 1940 bunches overnight, dumped again from losses. 1740 worked for a while but then got dumped due to losses as well. They switched to 96bpi with fill 6072, the night to Saturday, after the scrubbing. It should reduce the heat load, but you can't get 2556 bunches that way. They tried to fi...
by mfb
Tue Aug 15, 2017 2:44 pm
Forum: The Accelerator
Topic: 2017 Operation
Replies: 72
Views: 6280

Re: 2017 Operation

They still seem to have problems with beam losses, same point as before.

1.10E11 protons/bunch currently.

Edit Wednesday: Bunch number is oscillating a bit depending on dump reasons, but now we have a stable run with 1550 bunches.
by mfb
Thu Aug 10, 2017 1:38 am
Forum: The Accelerator
Topic: What are the current records for LHC fills?
Replies: 45
Views: 4851

Re: What are the current records for LHC fills?

3.08 and 3.16E14 protons in the beams this evening. 174% the design luminosity after optimization. The previous run started 6:46 and had 500/pb. This run had 200/pb already. If the beams don't get dumped, we get a new 24 hour record with a bit more than 0.8/fb. Edit: ~335/pb (ATLAS shows 331, CMS sh...
by mfb
Sun Aug 06, 2017 2:42 am
Forum: The Accelerator
Topic: What are the current records for LHC fills?
Replies: 45
Views: 4851

Re: What are the current records for LHC fills?

Collecting the records in a single post: Peak luminosity: A bit above 1.6E34/(cm^2*s), several runs in July/August. Highest beam energy: At 3E14 p/beam and 6.5 TeV, we had 310 MJ per beam in various runs. Luminosity in 24 hours: 0.7/fb in early 2017 according to this article , not sure if that is st...
by mfb
Sun Aug 06, 2017 2:21 am
Forum: The Accelerator
Topic: 2017 Operation
Replies: 72
Views: 6280

Re: 2017 Operation

14 hours into the current run, 520/pb.

15.5 weeks of data-taking remaining. If the LHC keeps running as in the last few days, we get 3.5/fb per week and 55/fb more, for a total of more than 60/fb. That is probably too optimistic, but 50/fb doesn't look unrealistic.
by mfb
Thu Aug 03, 2017 9:14 pm
Forum: Science
Topic: LIGO - Was It All Just Noise?
Replies: 26
Views: 863

Re: LIGO - Was It All Just Noise?

I plugged in numbers into the quadrupole formula. There is nothing published because a one-minute calculation shows it is tens of orders of magnitude too weak to be relevant. Virgo joined LIGO in the science run on Tuesday, this months they will measure together. Afterwards all three detectors will ...
by mfb
Thu Aug 03, 2017 9:12 pm
Forum: The Accelerator
Topic: 2017 Operation
Replies: 72
Views: 6280

Re: 2017 Operation

Based on the recent MD block, the machine operators are confident that they can go to beta* = 30 cm later (down from 40 cm).
by mfb
Mon Jul 31, 2017 8:24 am
Forum: The Accelerator
Topic: 2017 Operation
Replies: 72
Views: 6280

Re: 2017 Operation

10/fb for both ATLAS and CMS. Data-taking makes nice progress, more than 0.6/fb in the last 24 hours.
by mfb
Wed Jul 26, 2017 9:53 pm
Forum: The Accelerator
Topic: 2017 Operation
Replies: 72
Views: 6280

Re: 2017 Operation

Van-der-Meer scans. We get a better luminosity calibration now.
by mfb
Fri Jul 21, 2017 6:09 pm
Forum: The Accelerator
Topic: 2017 Operation
Replies: 72
Views: 6280

Re: 2017 Operation

More than 2.11 would be an absolute luminosity record, surpassing the KEKB record from 2009. As far as I know it would be the first time ever a proton-proton machine has the absolute luminosity record. It would be a stretch, but maybe they can make it possible. 2018 SuperKEKB will surpass this recor...