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Zachary Marshall | USLHC | USA

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LHC Physics News

By special request, here is an update on how the physics and machine are doing. Hope it helps!

Any results or new physics hints?

We don’t yet have enough data to see much new physics. Unless it’s something really strange, we expect only one “interesting” event for every thousand million collisions we see. We’ve seen hundreds of millions of collisions now, but it’s unlikely that we’ll say anything definitive until we’ve seen quite a bit. You can see my previous posts about being careful and errors for some of the reasons why.

As for the results we have seen, we’re progressing well. I liked the way one of my collaborators put it: a march through the history of physics. We’ve gone through the ’50’s, ’60’s, and some of the 70’s. We’ve gotten some of the ’80’s done as well. We probably need ten or one hundred times more data to get through the ’90’s. After that, the sky is the limit…

Why is the machine going so slow?

Truth is, the LHC is doing great. It feels as though every week we collect as much data as we had collected up to that point. Of course, the exponential growth won’t go on forever. But there are quite a few things that we can still do to get a lot more data out of the machine. In numbers: we are around one half of one thousandth of one percent of the “maximum” collision rate in the LHC. We know very well how to get thousands of times more collisions per second – but we want to go slowly. This machine has to be around for 20 years – it won’t do to get hasty and have an accident at this point! We can’t just go buy another one!!!

If you watch the LHC Page 1 obsessively, then you’ll see a lot of down time. It turns out that, if you’re in Europe particularly, it’s self-selecting. That is, when the experts are there during the day, we’ll spend a lot of time doing tests. At night, they often have stable runs (by “night” I mean midnight to 8am). But it’s those tests (during which we don’t have “stable beam,” and sometimes we don’t even have beam) that give us the confidence to raise the collision rate by quite a bit. Tonight, more tests – so that we can get a higher collision rate!

So when will we know more??

The collision rate will continue to increase, and I hope we hit the “magic number” – 100 inverse picobarns of data – around the end of the year. I say “magic number” because that’s around the time when we’ll start to really beat previous machines like the Tevatron in Chicago. To some, that’s when the fun starts – when we start looking for new physics, and we have reach well beyond any other machine in history.

We release a lot of results at conferences. The summer has several key conferences, so I fully expect several results from each experiment at every conference. They probably won’t be “discovery” results, but they will be the first key physics results. They’re exciting to some physicists, but, frankly, many will consider most of these “ho-hum” results (unless one of us does find something new!). Everyone recognizes how important it is to get some results, and what attitude is being expressed. We’re releasing physics results less than six months after the machine started! There are experiments that have taken years with their data before releasing any results!!

And as the exciting results roll in, we’ll keep you up-to-date here, as much as we can!