Old Breaking news 11/30-12/2/09

[Xymox]

The LHC has achieved a new world record of 1.18TeV very easily with no important problems encountered.

Collisions at this level or even greater can't be far away.

Congratulations to everyone for this world record setting achievement !



http://lhc-commissioning.web.cern.ch/lh ... t-news.htm

http://cms.web.cern.ch/cms/News/e-comme ... tary09.htm


Why is it that at the moment of a important event I am not close to a computer
Again I was away from my computer when they achieved this milestone.

[Xymox]

I think its possible that they might do 1.1 collisions like any minute...

Maybe...

Just a guess..

They have ALICE and ATLAS ON

[DCWhitworth]

They've had ALICE and ATLAS powered up most of the afternoon, but I've not seen any signs of them ramping up the beam power at all.

I've got two screens on my PC at work. The secondary one is normally dedicated to server monitoring, it's currently dedicated to LHC monitoring !

[sfxmadness]

Hi All,

I have been following the events of the last few days from the back seat and this last one is very great news indeed.

I also find it very exciting that this level of information along with much detail is available to the grand public.

I wish I could free more time to get better informed about all that is going on at the LHC and to actually contribute to the community that is also sharing similar interest.

Thank you for this site.

[LHC_Insider]

Collisions at this level or even greater can't be far away.

For a given definition of 'far away'... There are many things to bear in mind. Firstly, we currently only have one bunch per beam, and that bunch is pretty puny (the 'Inject probe' you see mentioned). To get meaningful collision data, we need more bunches (at design specs we will have close to 4000 per beam), and high intensity (i.e. more protons) per bunch.

We also need to understand the tunes. The LHC, like all coupled oscillating whatevers, is a resonant system. As such, as the energy increases, the 'tune' of the machine (think of it like keeping a string in tune - the protons are not describing an exact circle; they are actually following a helical path in the machine) needs to be calculated. If you look at the beam plots, there were losses in the beam during the acceleration due to these oscillations.

We also need to finish the commissioning of the quench protection, collimation, beam dump systems etc etc.

On top of that, we need to understand the optics of the machine (so we can 'aim' and focus the beams at the collision sites). We are apparently a few shifts away from understanding the optics at 450 GeV / beam, so we need to be able to get stable beams at 1.18 TeV before beginning to probe the optics at that energy.

The point is, the acceleration is a huge step, but there is much, much more to do before we can collide.

With regards to experiments being 'on', they are basically all on all the time, taking data, working on their commissioning (I'm actually an experiment person as opposed to an accelerator person). The LHC Page 1 display may say 'standby', but an experiment can be in a local DAQ mode taking data without the various communications to the LHC control. I think the bit about 'turning on' today was that we as of yet have not circulated beams with the experiments' magnets on. Today, these were turned on one by one so that the machine people can understand the couplings between these magnets and those in the LHC itself. These effects are another thing that needs to be understood and corrected for.

Right... Back to looking at the available collision data!

[Xymox]

Wow !.... I stand very happily corrected !

OK that's it, I am elevating you to LHCPortal Guru status, hehehehe....

Now you just gotta share some insight into that "candidate" collision data

I just know your using all sorts of amazing 3D visualization tool like iguana. Man I am SOOoOoo jealous. Such a cool job... For a pro, these new tools for looking at the data must be quite a advancement in state of the art tools for analysis ? That is a whole untold story I am sure. The way all the science collaborators will work on the data is going to be very interesting and cutting edge as well. The science tools are quite amazing.

So far all the attention has been toward the machine. Soon the focus will shift to the amazing science that will come from the machine. This is going to be fun.

Now remember... We need Warp Drive.. We need to get to other stars.. SO you must have a fundamental discovery that will lead to the science that eventually leads to Warp Drive. I wont take no for a answer.

Yea ok... My guess for higher energy collisions is before the 14th. More like the 10th at the latest. So your saying you not only want energy, you want good luminosity. So the plan might be to get collisions,, that might even, with lots of luck, result in some interesting event data... OoOoOoo that would be a nice Christmas present for CERN..

Nice to have you here. Thanks for taking time to post. This is awesome outreach.

[LHC_Insider]

Now you just gotta share some insight into that "candidate" collision data

Now I'm afraid that I can't do - anything made public has to be approved by the whole collaboration (within each experiment, that is - CMS don't approve ATLAS results, for example). However, this morning, the first paper was released by ALICE:

http://arxiv.org/abs/0911.5430

I just know your using all sorts of amazing 3D visualization tool like iguana. Man I am SOOoOoo jealous. Such a cool job... For a pro, these new tools for looking at the data must be quite a advancement in state of the art tools for analysis ?

Well, the visualisation tools are useful (most of us on CMS use a thing called Fireworks actually; it's more lightweight than Iguana), but not how we actually do analysis. That is done by running analysis software we write (in C++) to extract useful quantites from the events. It's all statistics; when we're at full-tilt we will have billions upon billions of events to analyse.

That is a whole untold story I am sure. The way all the science collaborators will work on the data is going to be very interesting and cutting edge as well. The science tools are quite amazing.

I think the community has got complacent, to be honest. Sure, we have access to hundreds of thousands of CPUs worldwide, and many petabytes of data storage, but this isn't that unusual now. It was when we started planning 15 years ago though. At the end of the day, we just run C++ applications on a shedload of data...

And yes, we really hope to get interesting new Physics soon.

Nice to have you here. Thanks for taking time to post. This is awesome outreach.

No problem. As you can imagine, it's a little busy at the moment, but I will try my best!

[chriwi]

Hello LHC_insider,

I am also glad to have you here.

At the moment I have one important question abut my understanding of what is going on there:
Is my understanding correct when I think of the solenoids of the experiments as a track switch which deflects the beam wether on a track to bypass the experiment or to pass through the experiment, the default of this track switch is bypass and only when it is turned on the the beam will pass throug the detector of a certain experimnt (f.e. the CMS)?

[LHC_Insider]

Hi Chriwi,

The beams are always passing through the experiments, there are no by-passes. The experimental solenoids are an integral part of the measuring capabilities of the detectors. For each type of particle we can observe, we care about a few main variables:

1. Its charge (+1, 0, or -1)
2. Its momentum
3. Its energy as deposited in the electromagnetic calorimeter
4. Its energy as deposited in the hadronic calorimeter

The ratio of 3 to 4 gives you a handle on how much a particle is 'electron / photon - like' or how much it is 'quark-like'. Electrons / photons give up their energy before quarks do. Note that we don't say 'that's an electron', we say 'this looks really like an electron', but we can never be quite sure - they don't come with labels on them

In any case, the question is how do we measure momentum and charge? Charged particles bend in a magnetic field (think CRT monitors), so by having a tracking system inside a solenoidal magentic field, we can record the paths of charged tracks as they move through the detector. If they bend one way, they are charge +1, if they bend the other way, they are charge -1. The degree of bending tells us the momentum.

[chriwi]

Thanks LHC_insider,

so that means that the experiment-solenoids are parts of gigiant massspectrometers.

bye

chriwi

[Danny252]

Thanks for the info, LHC_Insider - certainly given me a better understanding of some parts of the machine.

Currently the machine is set to 7.864 TeV - I don't know if the plan is to ramp a beam up to this energy today?

[LHC_Insider]

chriwi: Yes, you can think of them that way. However, a point of clarity: The solenoids and tracking systems are momentum spectrometers, not mass spectrometers. The combination of energy and momentum measurements allow us to determine a particle's mass.

Danny252: There must be machine software tests of some description going on. We will never ramp a beam above 7 TeV. In any case, we would not take the beam higher than about 1 TeV at the moment as the magents have not been commissioned above that. The aim is to get a 3.5 TeV / beam Physics run sometime next year, after further commissioning. 7 TeV / beam will wait until 2011.

[heladepela]

I believe I know what Danny252 is referring too and I have been curious about it as well. In the LHC_Operation view at the top it states Energy: 7.864 TeV (as in screenshot below), what does that refer to ?

[Tim Bergel]

Thanks also from me for the info, LHC_Insider - its really useful & interesting to hear from someone who understands such a complex system. It sounds like you are all having a great time getting the machine up to speed!

[daavery]

Page1 format has also changed: the beamTV images are not showing now and the whole mid-page area is different ( blank for now). I also noticed the "Page 1" and "LHC Operations" " Beam Current"(I) values were very different since yesterday. The "LHC Operations" I values seemed to match the Intensity plots while the "Page 1" values were moving around and dropping to 0.