Daily Schedules and Hiccups

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Danny252
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Re: Daily Schedules and Hiccups

Post by Danny252 » Thu Dec 10, 2009 4:45 pm

Thursday:

--
Comments: Supposedly some collisions. Doing dump studies at 17:45 CERN time, Collimator Studies + Higher Intensity beams still on for later.
--
Morning:

- Test transverse IP adjustments in IP5
- Quick optics verification at end of fill
- Bring ALICE solenoid back up ("-" polarity)
- Continue studies for higher intensities

Afternoon/evening:

- Collimator setup verification with higher intensities
- Stable beam collisions at 450 GeV with higher bunch
intensities 4x4, 2e10 p/bch

NB: new 4x4 filling scheme with no bunch bezond RF bucket 27000
has been prepared. See below or https://cern.ch/lpc
scheme 4x4_b .

Danny252
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Re: Daily Schedules and Hiccups

Post by Danny252 » Fri Dec 11, 2009 3:32 pm

Friday:

--
Comments: Looks like some of it may have been cut off for some reason?
--

Morning:

- Transverse scan IP8
- Transverse scan IP1
- Transverse scan IP5
- RF adjustements, no stable beams, ramp up ALICE dipole to "-"
- Transverse scan IP2

Afternoon, evening, night:
- As soon as CMS solenoid and ATLAS toroids at nominal fields,
start long stable beam period, till tomorrow morning,
then review.
For this period, we will use the scheme 4x4_c
*** with no overinjection, i.e. pilot and +1000 shift ***

Stephen
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Re: Daily Schedules and Hiccups

Post by Stephen » Sat Dec 12, 2009 1:10 am

Do they still have cyro problems? Any idea what causes them?

Shadowdraxx
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Re: Daily Schedules and Hiccups

Post by Shadowdraxx » Sat Dec 12, 2009 10:17 am

is this the reason for a month of no beams? to sort cyro out? seems to have annoyed the beam dept alot since turn on

Danny252
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Re: Daily Schedules and Hiccups

Post by Danny252 » Sat Dec 12, 2009 5:59 pm

Saturday's Timetable

--
Comments: Collisions and analying why B2 keeps falling is that?
--

- Continue stable beam collisions at 450 GeV, 2e10 p/bch,
4x4_c+shifted (no overinjection), review tomorrow morning.
- Try understanding beam life times.
- If possible, further transverse IP adjustments.
Last edited by Danny252 on Sat Dec 12, 2009 6:53 pm, edited 1 time in total.

RonnyV
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Re: Daily Schedules and Hiccups

Post by RonnyV » Sat Dec 12, 2009 6:53 pm

Shadowdraxx wrote:is this the reason for a month of no beams? to sort cyro out? seems to have annoyed the beam dept alot since turn on
There are several reasons for the shutdown, like maintenance actions that have to be done but also the LHC consumes a tremendous amount of energy in the form of electricity and the city of Geneva needs more electricity in the coldest months of the year for heating and lighting ...

What amazes me the most is not the fact that there are regular hiccups but the speed with which they manage to resolve them ! The complete LHC-team, from the machine operators in the CCC to the technicians "in the field" and anyone in between is working like a very well oiled machine, being an engineer myself I fully understand this is not evident at all.

Always keep in mind the sizes and scales of the LHC + Experiments and how they are defining new boundaries in many engineering area's. Just try to take a virtual walk in your mind along the LHC: if you' re afast walker, it 'll take you 3 hours, at 6 km/hr it will be almost 5 hours. The core of this machine is cooled down to 1.9K (-271°C), the coldest place in the entire universe (unless some others in a distant galaxy are also experimenting ...).

I could go on, but it's more fun to find out yourself: use the portal and forum and follow the links, hours of fun and information guaranteed. Just one more thing: here a photo of some guys working on the CMS detector to show you the scale of this (PS CMS stands for Compact Muon Solenoid, imagine how big ATLAS must be)

Image

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Allan
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Re: Daily Schedules and Hiccups

Post by Allan » Sat Dec 12, 2009 10:02 pm

Hi Everyone;posting.php?mode=reply&f=4&t=102#

Looks like beam down for 12 hours.

LHC: Cold compressor off in S12, present estimate: no beam for 12hrs

Allan :mrgreen:

Danny252
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Re: Daily Schedules and Hiccups

Post by Danny252 » Tue Dec 15, 2009 3:05 pm

Tuesday's

--
Comments: TOTEM/Roman Pots tests completed by time of posting. (1600 CERN Time). Ramp + Squeeze - 16x16? We'll have to watch!
--

Morning:

- Prepare 4x4
- Set up TOTEM Roman Pots, then take data, ~2h
- Study abort gap cleaner

Afternoon/evening:

- Orbit feedback
- Ramp, squeeze and machine measurements at 1.18 TeV squeezed

Harbles
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Re: Daily Schedules and Hiccups

Post by Harbles » Tue Dec 15, 2009 10:29 pm

They were running nice this afternoon with a 4 bunch at 1.18 TeV beam and another power converter tripped. This seems to be happening a lot. One log mentioned that they had already switched to the second card on that pc. I would love to hear the technical 'discussions' going on about pc reliability and what it means for long (10 months) runs.

josch222
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Re: Daily Schedules and Hiccups

Post by josch222 » Tue Dec 15, 2009 11:33 pm

Harbles wrote:They were running nice this afternoon with a 4 bunch at 1.18 TeV beam and another power converter tripped. This seems to be happening a lot. One log mentioned that they had already switched to the second card on that pc. I would love to hear the technical 'discussions' going on about pc reliability and what it means for long (10 months) runs.
Yes, I think too there will be discussions, but from the POV of decison-making for better reliability,
it is nice when you have multiple failures of the same subsystem ;-)
It is very frustrating to have different failures every day.
Most evil: Sporadic errors, you can spend weeks to catch the cause and sometimes it is
better to implement a workaround.

But given the huge amount of parts (and connections!) in the whole LHC I'm sure there will
be some more issues with reliability.
I know that there are calculations for the reliability of the beam-dump system, it would
be interesting if there is a MTBF for the whole LCH. On the other hand, such a value alone
would have not much meaning.

Joerg.

Harbles
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Re: Daily Schedules and Hiccups

Post by Harbles » Fri Dec 18, 2009 10:31 pm

Re: the PC trips of Tuesday I found an interesting entry in the AB-OP Elog LHC PO HC page at tues 15 Dec 23:02 abut the trip being caused by an unexpected large value short duration input from the real time feedback system. So it sounds like it's some thing they will sort out and not defective hardware failing as I was assuming (fearing) above.

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DCWhitworth
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Re: Daily Schedules and Hiccups

Post by DCWhitworth » Fri Dec 18, 2009 10:53 pm

Harbles wrote:Re: the PC trips of Tuesday I found an interesting entry in the AB-OP Elog LHC PO HC page at tues 15 Dec 23:02 abut the trip being caused by an unexpected large value short duration input from the real time feedback system. So it sounds like it's some thing they will sort out and not defective hardware failing as I was assuming (fearing) above.
I expect trips during pre-cycles is something they will be looking at very closely durin gthe shutdown, it seemed to be a major irritant.
DC

The LHC - One ring to rule them all !

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