Search found 153 matches

by jmc2000
Sun Aug 06, 2017 1:05 am
Forum: The Accelerator
Topic: 2017 Operation
Replies: 72
Views: 57203

Re: 2017 Operation

Atlas currently recording o.5\fb every 13 hours giving >3.5\fb per week for 55% beam time

JMc
by jmc2000
Thu Jul 20, 2017 8:53 pm
Forum: The Accelerator
Topic: 2017 Operation
Replies: 72
Views: 57203

Re: 2017 Operation

At one point they managed a new instantaneous luminosity record of 1.65\nb/s, but dumped an hour later because of losses. 1.7\nb/s is the aim this year for beta = 40cm, 1.9\nb/s for beta = 33cm.

JMc
by jmc2000
Tue Jul 04, 2017 1:05 am
Forum: The Accelerator
Topic: 2017 Operation
Replies: 72
Views: 57203

Re: 2017 Operation

Does anyone know how the MDs went, and if a lower beta is a possibility?

jmc2000
by jmc2000
Tue Jun 27, 2017 6:19 pm
Forum: The Accelerator
Topic: 2017 Operation
Replies: 72
Views: 57203

Re: 2017 Operation

No, it looks clearly like BCMS.Emi is around 2.3 like BCMS Lumi is up to 1.55, which could not be achieved with 2460 bunches, if not BCMS. I guess the difference to calculation is due higher crossing angle at start, calculation is for 150µrad, but they start now at 240µrad to lower pile up and decr...
by jmc2000
Mon Jun 26, 2017 11:44 pm
Forum: The Accelerator
Topic: 2017 Operation
Replies: 72
Views: 57203

Re: 2017 Operation

https://indico.cern.ch/event/632309/contributions/2556444/attachments/1456855/2250118/LHCC-LHC_machine_status_report_11052017_MSolfaroli.pdf Page 19 gave a few possible 2017 scenarios with 2448b + BCMS giving higher luminosities compared to standard 2736b. We're at a luminosity of around 1.4/nb/s s...
by jmc2000
Thu Mar 09, 2017 11:05 pm
Forum: The Accelerator
Topic: 2017 Operation
Replies: 72
Views: 57203

Re: 2017 Operation

Summary Session of the LHC Performance Workshop 2017, March 1st:
https://indico.cern.ch/event/614870/

Aim is to record 45\fb, but going by previous years they'll probably go far further: 60\fb? ;)

jmc2000
by jmc2000
Thu Dec 01, 2016 10:46 pm
Forum: The Accelerator
Topic: 2017 Operation
Replies: 72
Views: 57203

2017 Operation

From the recent 128th LHCC Meeting:https://indico.cern.ch/event/580364/, page 27 from LHC Machine Status Report:
Naively applying 2016’s overall Hübner factor gives between 45 and 60 fb-1
Final configuration following discussion at Evian and Chamonix
jmc2000
by jmc2000
Thu Nov 03, 2016 8:38 pm
Forum: The Accelerator
Topic: LHC smashes targets for 2016 run
Replies: 0
Views: 15630

LHC smashes targets for 2016 run

There's a nice article concluding the 2016 proton-proton run: https://home.cern/about/opinion/2016/11/lhc-smashes-targets-2016-run-0 This success is underscored by the most amazing statistic of the year: in 2016, the LHC spent 60% of its operational time delivering stable beams to the experiments. JMc
by jmc2000
Mon Oct 17, 2016 12:15 am
Forum: The Accelerator
Topic: 2016 operation
Replies: 52
Views: 35903

Re: 2016 operation

mfb wrote:They made a high pileup test yesterday. Bunch trains with ~50 collisions per interaction, and a few individual bunches with 90-95 collisions. That is about 4 times the design value, and not far away from the HL-LHC conditions (140, maybe up to 200).
Has anything been published about this?

JMc
by jmc2000
Mon Sep 26, 2016 4:14 pm
Forum: The Accelerator
Topic: 2016 operation
Replies: 52
Views: 35903

Re: 2016 operation

Record luminosities for Atlas: 13.75 Hz/nb, CMS: 14.5 Hz/nb !! The latest LHCC meeting makes for interesting reading: https://indico.cern.ch/event/563488/ page 14: https://indico.cern.ch/event/563488/contributions/2277292/attachments/1340292/2019570/20160921_LHCC.pdf "~40-45 fb-1/year in 2017 and 20...
by jmc2000
Sat Sep 03, 2016 9:06 pm
Forum: The Accelerator
Topic: 2016 operation
Replies: 52
Views: 35903

Re: 2016 operation

New record for instantaneous luminosity for CMS at ~13.5 hz/nb ! and it's back to averaging 2.5\fb/week as in early August. But it's difficult to know how much out of calibration CMS is, and whether the record is real. Fingers crossed, >35\fb for 2016 is looking realistic which is x3 the data presen...
by jmc2000
Wed Aug 10, 2016 5:59 pm
Forum: The Accelerator
Topic: 2016 operation
Replies: 52
Views: 35903

Re: 2016 operation

It is an electric problem - the beam drilling a hole through the magnet would look differently. A short on the winding of a dipole magnet will mean it being warmed up to room temperature, replaced, then recooled as with a drilled example - 30 days repair with most of the days needed for the warming...
by jmc2000
Wed Aug 10, 2016 4:07 pm
Forum: The Accelerator
Topic: 2016 operation
Replies: 52
Views: 35903

Re: 2016 operation

Suspected short on dipole 31L2 which could be bad news in taking 30 days to replace: http://www.symmetrymagazine.org/article/december-2007/protecting-the-lhc-from-itself “In a bad accident, the beam could go off course and drill a hole through one or two magnets,” says Schmidt. While this would not ...
by jmc2000
Mon Aug 08, 2016 1:07 am
Forum: The Accelerator
Topic: 2016 operation
Replies: 52
Views: 35903

Re: 2016 operation

Recorded integrated luminosity/week ~1.6fb compared to ~2.5fb before the MDs which still looks pretty good, considering that there was even talk of replacing magnet D that would have taken 8 days, plus a few hundred hours of intensity ramp up. I wonder how much of the recent MD will be used over the...
by jmc2000
Sat Aug 06, 2016 11:12 pm
Forum: The Accelerator
Topic: CMS and ATLAS luminosity: are they jealous?
Replies: 6
Views: 8526

Re: CMS and ATLAS luminosity: are they jealous?

Does anyone know why the CMS luminosity is 10% larger than ATLAS, despite being the same before the MDs?

JMc