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Posts Tagged ‘startup’

It’s kind of mind-bending how fast things are ramping up, but no-one knows when “it” will happen, and how “it” will go — “it” being the initial collisions and the data analysis to follow. You get the same sense from everyone you talk to about the LHC, and especially from the younger people i know (students and postdocs) whose, well, *lives* depend on things getting going soon. I remember this feeling well, just as RHIC was starting — although things felt smaller in those days, or at least my 50-person experiment did.

This week is a Physics and Performance Workshop concerned with how ATLAS will deal with early data. I have a particular interest in this from the standpoint of a guy interested in heavy ions since this is precisely the data we will use to compare with lead-lead collisions when they eventually arrive. And yet, the last few months finishing up our proposal (more on that later, i’m serious) have shielded me from the outrageous amount of work going into so many different aspects of the detector and analysis. I’m scrambling to catch up long-distance, from my office, reading slides, and keeping up with emails, and we even have a heavy ion videoconference tomorrow (for which I’m assembling a talk now…). But there’s a lot to keep up with, and then I still have to get ready for the big ATLAS week in July! (and let’s not mention we have a short Alpine vacation to plan as well…)

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It’s very exciting to be lucky enough to be here at CERN as the LHC is finally set to turn on. People first started thinking about the LHC over 30 years ago (about when I was born), and magnet R&D began in 1988 (when I was in middle school). The CERN council approved it in 1994 (as I was graduating High School). I have seen presentations on the physics of the LHC since I entered the field 10 years ago as a graduate student. After the long build-up, a lot of people are starting to guess what will happen when the first protons finally collide. Everyone is eagerly expecting big discoveries, and many expect they will come fast.

I have seen talks in the past few years asking how many WEEKS it will take to discover supersymmetry. Here is a blog post from the APS meeting about a more conservative timeline of possible discoveries, some as early as 2009, some as late as 2019. My own experience on start-ups comes from being a member of the D0 Experiment during the start-up of Run II at the TeVatron at Fermilab. If that is any guide, the LHC won’t discover anything on Day One, and probably not after Week One, Month One, and maybe even Year One.
The official start-up of Run II at the TeVatron was on March 1, 2001. The first physics paper wasn’t submitted until March, 2003 by the CDF collaboration.

Here are the number of Run II publications per year from the CDF Experiment (link):
2001: 0
2002: 0
2003: 3
2004: 4
2005: 28

and from the D0 Experiment (link):
2001: 0
2002: 0
2003: 0
2004: 2
2005: 27

So it really took 4 years for the papers to start pouring out. To give you an idea of the kind of “discoveries” we were trying to make on D0 at first, here is an excerpt of an email to the collaboration from April 3, 2001:

Dear colleagues,
We are getting collisions, though not all the detectors
are timed in. We expect most the detectors get timed in
within the 1×8 stores. … we agreed to give out five
bottles of wine, one bottle each, for finding the following
objects:

First two jet event
First photon
First reconstructed track in the SMT+CFT system
First electron
First muon

Event displays of these objects are necessary…
This competition will go on till all the bottles
are exhausted…

So with a new detector, it is first necessary to re-discover what you already know should be there, and then one can move on to the real discoveries. In my opinion, the ATLAS detector is in better shape to collect data than D0 was at that time, and in fact I have been looking at some cosmic-ray data we collected recently and the detector is performing pretty well already. So things might go quicker here.

Another big difference is, with respect to discoveries, the LHC is a big leap in energy over previous accelerators, while the TeVatron in 2001 was only a slight upgrade in terms of energy over its previous run, so big discoveries were not expected quickly. A better analogy might be to the turn-on of the SPPS accelerator and the UA1 and UA2 detectors in 1981, which are often cited for making nobel-prize-worthy discoveries of the W and Z bosons, very quickly after turning on. How quickly? From here, I found an official CERN history:

In summer 1981 the first collision between protons and antiprotons was recorded. The first experiments began in November 1981. At the beginning of 1982 two accidents damaged the UA1 detector, so the experiment was stopped until summer 1982. UA1 and UA2 experiments started again in September 1982 until December 1982, when the accelerators were switched off for two months. During this time data were analyzed and physicists were convinced of having discovered the W boson. This was announced in a press conference held on 25 January 1983. The next step was the discovery of Z boson. The experiments on SPS began again on April 1983, and there were soon major results. On 1 June 1983 CERN formally announced the discovery of the Z boson.

So in this case, it still took almost 2 years from the first beam to the first discovery announcement. Although, really it only took 4 months from data taking to announcement of the W boson discovery after the UA1 detector was fixed, and then less than 6 months more until the Z boson discovery announcement.

So how quickly CERN makes headlines with a discovery depends on how smoothly the work of thousands of people comes together over the next months, as well as on what nature has in store for us. Since of course no one knows that, we will just have to wait and see. It should be fun.

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Beam Schedule

Wednesday, April 23rd, 2008

The beam schedule. It is a constant source of anxiety at CERN. If you are interested in the latest-minute fluctuation in the beam schedule, I am not the person to ask. As a principle I refuse to worry about it because there is absolutely nothing that I can do to change it. The beam schedule will be what the beam schedule is regardless of whether I worry or not.

Instead I prefer to lose sleep over preparing ATLAS for beam readiness. Because it would be quite embarrassing with all the hype about the beam schedule to then not have a working detector. And preparing ATLAS for beam is something that at least I can contribute directly to.

The other reason I don’t try to determine the beam schedule on a daily basis is because then I would have to interpret charts like this.

beam_schedule

But there are some major announcements worth noting. First the current schedule plans that the machine will be cold (to superconducting temperatures) by mid-June. And that we could expect single beam in July. The first physics run in 2008 will be at an energy of 10TeV. (The machine design is 14TeV and for comparison the Tevatron accelerator in Chicago is 1.96 TeV).

There is disappointment from some that the first run will not be at the full design power. But for me, any beam will do. We have been building and testing this detector for so long. We all want to take it for a test drive. Even a ‘little’ 10 TeV one.

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