LHC portal

Latest 131st LHCC meeting has 45\fb as year end target :
https://indico.cern.ch/event/658856/con ... pt2017.pdf

JMc

https://home.cern/cern-people/updates/2017/08/lhc-report-something-nothing "On the basis of current statistics, there appears to be no direct correlation between the number of bunches and the number of beam dumps, so the task force is now planning tests with beams of up to 2200 bunches (last year’s ...

So running with the current 1550b yields 0.3\fb/day = 2\fb/week at 55% efficiency giving 35 - 40\fb for 2017 which looks fine to me, bearing in mind that the hope was to accumulate > 100\fb for run 2. I don't see the point in changing the planned running parameters of the LHC significantly, just for...

Interesting... so am I right in saying that the beam can heat the pipe via inductive heating, thus releasing any frozen gas, and temporary failing of the cryogenics then adds to the problem as the frozen gas is heated? This makes sense because the problem seemed to go away for a while as they gradua...

They've moved from 144bpi to 96bpi which looks interesting... perhaps the lower bpi are more efficient in scrubbing the injectors and minimizing loses?

JMc

Does anyone know why, for the past week, they're having to slowly ramp up the intensity again?

Jmc

They were trying for increased bunch intensity, but lost the beam several times upon ramping; so I guess the scrubbing is to "clean" the beam path in the hope this will improve things.

JMc

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

JMc

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

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

jmc2000

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...

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...

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

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

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