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LHC is Turning on FAST September 19, 2008

Posted by gordonwatts in Fermilab, LHC.

During Frank’s talk he said that he was a bit "depressed that it took 25 years to build machine, but just a few weeks to commission" – implying it wasn’t enough of a challenge.

I am, frankly, amazed at how fast this thing has turned on. None of my previous experience had prepared me for how fast they have turned on. The engineering job is incredible. Here they turned on 10 September and they are talking about first collisions (at 900 GeV — really small compared to the planned 14 TeV final operation) this coming weekend!

Given the number of moving parts, electronics, etc., in this machine… well, this is a breath-taking to have gotten this far. As a long-time member of the US community I’m also feeling a bit embarrassed. Our last start up – Fermilab Run 2 – was not nearly as smooth. One key difference between the LHC and Fermilab’s startup, btw, is that all the bits are present in the accelerator from the get-go. Fermilab has continuously been adding bits to the accelerator to improve it (many bits were delayed due to the funding profile).

If we in the USA get a chance to build another accelerator we are going to have to make sure we step up and match (or come close to matching) CERN’s accelerator division!

UPDATE: Yeah Yeah. I know. 2 months of downtime now. ๐Ÿ™‚ What can I say? The accident was probably caused by me posting this. I donโ€™t know if you saw the CERN press release โ€“ but note how it said that in a non-super conducting machine this fix would take a few days? The 2 months is because they have to warm the machine up and then cool it down again. What is a magnet replacement at Fermilab? 8 days? I wonder what the difference is in the cryo systems?


Will it really take ATLAS 3 years to see 5 sigma Higgs? August 20, 2008

Posted by gordonwatts in ATLAS, CERN, D0, Fermilab.

Probably (for ATLAS new predictions on this should be released in a few months). But in the context of the Tevatron and the LHC Higgs search that isn’t really what is important.

The ATLAS prediction that it might take 3 years to reach the 5 sigma level for a low mass Higgs discovery got a lot of airplay. It got me to thinking. Lets say the two accelerators are in close competition for the Higgs. The Tevatron can really only speak to the 3 sigma level. It isn’t ever going to get to the 5 sigma level. Further, at the Tevatron the CDF and DZERO experiments will have to combine their results to even reach this 3 sigma level. So, I find it highly unlikely that the LHC will sit back and let the Tevatron get away with this. I certainly wouldn’t (and I’m on a LHC experiment). So what to do? Obvious – beat the Tevatron at its own game: combine results from CMS and ATLAS and the 3 sigma level will be obtained much more quickly. At that point the LHC has stolen the thunder from the Tevatron and CMS and ATLAS can now race each other to individual discoveries of the Higgs at the 5 sigma level.

I don’t expect the experiments to combine for the 5 sigma discovery (I could well be wrong, of course – I know of no plans to not do this or to do this!). There are many forces at play that are driving each experiment to make the first paper submission of a 5 sigma signal. This may, indeed, be what gives the Tevatron space to slip in with a 3 sigma evidence paper. And in the grand scheme of things – the Tevatron goes out with a 3 sigma evidence and the LHC with a 5 sigma discovery – that doesn’t seem like a bad “split”. But who has ever heard of the free market working like that!?

As a member of DZERO I want to push as hard as possible to nail a low mass Higgs. As a member of ATLAS, I want the experiment to scramble as fast as possible to get the Higgs – evidence and discovery. After all, that is one of the LHC’s main points.

Play it safe, or… August 17, 2008

Posted by gordonwatts in ATLAS, CERN, D0, Fermilab.
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There was an unspoken theme at the DZERO workshop this week. Stick with the Tevatron for a huge, but iffy, payoff. Or switch to the LHC now because it is a “sure” bet (as sure as anything gets in research).

This is all about the Standard Model Higgs search at the two accelerators. If such a Higgs does exist the LHC is bound to discover it. The LHC has some “difficulty” at low mass Higgs (below about 125 or so). Difficulty for the LHC means it could take up to 3 years for a single experiment to declare a 5 sigma discovery, the gold standard of “discovery”.

At the Tevatron the Higgs analysis is all about difficulty. Each new Higgs result you hear or read about is a tour-de-force of new techniques and new methods of extracting every last bit of signal out of the experiments. As a graduate student I never remember techniques this sophisticated. And the LHC pre-trial analyses are not as sophisticated either (on the other hand, they don’t need to be).

Global fits to the Standard Model currently predict the Higgs to be low mass – between 114 GeV and 120 or 125 GeV. The Tevatron is currently x2 away from being sensitive to this mass range. By doubling our dataset to 6 fb-1 of data and making a number of improvements to our analyses, we expect that we should be there. These improvements are not easy – it will require a lot of work and a lot of people. Nor are they assured. At best, if the Higgs is there, and we aren’t unlucky, we should be able to see it at the 3 sigma level. But never the 5 sigma discovery level. That will have to be left to the LHC in any case.

So is it worth sticking with the Tevatron? Well… the payoff would be huge to see something at the 3 sigma level. So it is like a lottery with high stakes. The chance of winning is not all that sure, but the jackpot is big!

Me? Well, I’m working on both the LHC and the Tevatron (as are many US physicists). I have a student working on the Higgs search at Fermilab, for example. I’m deeply involved in a number of topics at the LHC as well.

What will happen? Hard to tell. Things to watch? Well, that is easy. There are only two things that really matter here – the performance of the Tevatron and the performance of the LHC. Each physicist who is on both collaborations is performing some complex calculus to optimize their time on the two experiments depending on the chances of success.

I wish us all luck. ๐Ÿ™‚

How Hard Will The Hunt Be? August 6, 2008

Posted by gordonwatts in D0, Fermilab, Higgs, physics.

Yesterday I mentioned that the Tevatron experiments had finally started to rule out the Higgs. I thought I’d post another plot that shows exactly how hard it will be – and so gives you an idea of how much hope the Tevatron has of actually catching the Higgs. Click on the plot to get an enlarged version of the jpeg (here for details).

The most important lines in that plot are the black one (1-CLs Observed) and and the 95% CL thick blue line. The thick blue line is the point at which, in our best statistical estimate, we are 95% confident that we have not observed anything. While the blue line is the “goal”, the black line is where we are now – the current observation. A lot goes into that black line – many different physics analysis contribute (from both D0 and CDF), the physics of the Higgs decay, the physics of how the Higgs boson is supposedly made, and how good our detector is at seeing the Higgs. As you can see, we have just peaked above the 95% level near 170. And that is what allows us to say that we’ve excluded the Higgs around 170 GeV.

Now, the future. You’ll note that the curve is pretty flat near where it peaks above 170. That says to me that when we add more data and minor analysis improvements we will be able to quickly broaden the amount of the observed line is above the 95% CL line. Where the black line is steeply falling, however, it require a huge amount of work (even if it is possible at the Tevatron).

Finally, in yesterday’s post the plot started at 114 GeV. This one starts at 155. What about everything from 114 to 155? Yes — we are working on that. For example, at D0 we have individual results already (and if you look at this plot, given the discussion, you can see that how we are doing as far as getting towards ruling things out at low mass – though the plot is a very different type of plot – but you can guess what is going on if you are not familiar with it). I couldn’t find the recent update of the CDF combined results. But the low mass combination between the experiments was not completed in time for ICHEP. I’m hopeful that we will see it soon – but as they say, it ain’t out until it is ready to be out!

New Fermilab Photos July 3, 2008

Posted by gordonwatts in Fermilab, photography.
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I’m always on the watch for new photos relating to particle physics. It seems there is a fairly new group on Flickr — Fermi National Accelerator Laboratory. Check it out, and if you have pictures of Fermilab, do contribute them!

Fermilab Gets $5 Million Donation June 2, 2008

Posted by gordonwatts in Fermilab, science.
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An anonymous donor has given $5 million to the University of Chicago to make up some of the budget short-fall at Fermilab. While it won’t prevent the layoffs from proceeding, it does mean an end to the furlough program. This was a crazy program where

This is old news now. But I was thinking about it over the last several days. This has something in common with another donation that was recently made for the LSST. At the University of Washington I’m used to seeing donations for buildings. And the result is a name on a large room, or perhaps the whole building is named after the donor or someone important to them. At least a plaque.

But these donations are different. There is no building that will remain for 50 years with the donor’s name. No room (though perhaps a plaque somewhere). The donor is donating funding for science. As I have mentioned before, at some level stepping in where our government has failed to step up to the plate. I think it is fantastic that people look beyond just getting their name on a building for 50 years. Thanks to all the donors who have taken this approach.

I was trying to think of a way a donor could get the best of both worlds. While we need buildings and rooms to do our science, we also need the money to build the equipment and the people to come up with the ideas. You could argue that people are the most important ingredient, actually. So there is another form of donation – endowed positions or named chairs. These are often named (“Kenneth K. Young Memorial Professor of Physics“). That way a donor would contribute perhaps the most important resource – intellectual power – and would still have their name associated their donation for a long period of time, as with getting their name on the building. Heck for the cost of a building you could probably setup endowments for quite a few prestigious named chairs. For less money one could do the same for graduate students – the lifeblood of any high quality research program.

Since both of these are endowments, the students or professors are paid off the interest earned by the endowment – which means they last “forever.” From a science and university point of view this is a fantastic deal.

In the meantime I’ll keep gifting small amounts of cash to our department and a few others that I’ve been associated with (i.e. until I strike it rich… probably never!).

Core Dump May 12, 2008

Posted by gordonwatts in computers, Fermilab, life, SLAC.
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A little bit of fluff. I suspect about half the people who read this blog already know this. I keep forgetting it — though I use the words “core dump” almost everyday (hey – right now I’m working on ATLAS software!).

The term “core dump” relates to an old type of computer memory, in use before the advent of silicon chips, which used grids of tiny magnetized rings to store information. When a computer program in such a system crashed, a record was created about the state of the memory. “Core dump” has come variously to mean any fatal error in a program, as well as slang for getting the long version of a story from someone.

This is from the SLAC today web mailing. The Fermilab version is a bit depressing right now: any day now the layoffs will be announced – and that day is going to be depressing when it finally arrives.

Bye Fred (subtext: Fermilab is a little less human) May 6, 2008

Posted by gordonwatts in Fermilab, physics life.
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I noticed in a Fermilab Today issue (the May 3rd issue) that Fred Ullrich retired. He ran Visual Media Services forever (well, as long as I can remember). I’ve interacted with him on and off for years. Sometimes begging him to prepare a poster for a conference that I’d waited until the last minute to finish off. I wanted to send him a congrats email. But I can’t find his email address!

So, as usual, I’m going to take this one little anecdote and extrapolate it way beyond reasonable limits (this is a blog, after all). The normal place to look for this sort of thing is the Fermilab white pages – an online directory. But the problem is Fermilab has taken computer and employee security to the level that pretty much the day you leave Fermilab all trace of you ever existing is removed from their databases. I realize this is how all of corporate America (and perhaps the rest of the world) works, but the problem is Fermilab feels like a “home” to me – and so this seems like fairly harsh treatment. Not something you’d do to your friend – especially as they are leaving on good terms. Queue the refrain “Ah, it was better in the old days…”

Bummer. At any rate – Fred – thanks for all your help over the years, and have fun starting the second half of your life!

Visual Media Service has a great collection of pictures taken over the years at Fermilab (ha! the page still says to contact Fred — he isn’t gone yet!!). Well worth looking through!

Superstition in the D0 Control Room March 14, 2008

Posted by gordonwatts in D0, Fermilab.
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There are lots of old superstitions – some of them we still live our lives by. Running a large experiment like D0 is no different. For example, there are a set of ducks along the console – the rumor is if they aren’t there then the whole system will cease to operate. I don’t think anyone has been brave enough to remove them… ๐Ÿ˜‰

I pulled the following quote from a recent shift report:

Beam was nice for a while.  Then while talking to Bill Lee about losing the beam, we lost the beam, thereby illustrating Bill’s spooky powers in the control room.

Bill has long been making our control room run smoothly, and should know the lesson: don’t talk about loosing the beam! You’ll jinx it!! [Technical reason: apparently an important power supply went out of allowed operating range].

Fermilab has Fun with Safety March 10, 2008

Posted by gordonwatts in Fermilab.
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IMG_1104As anyone who as worked at a US national lab knows, safety is job #1. The constant reminders and cross checks and forms that have to be signed before work can be done can sometimes be a little overbearing. And a bit frustrating – but there is a reason they are there; they seem to work.

Still, I can’t help but cringe when I see one of those posters that shows those cartoon characters “Hey, safe work is happy work!” or some such blather.

Fermilab seems to have come up with a better approach. I think the way this happened was they asked the graduate student association for some safety quotes. These were then turned into posters and have been distributed around the site. They work because they are out of the ordinary, and, for the most part, clever. Heck, I want to read them. I took photos of the ones I saw on my last visit: