View from my CERN office of the sunrise on the Jura mountains the morning of the 7 TeV collisions.  Good start to a good day.

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The CMS Collaboration has made public the preliminary plot that shows the di-photon resonance (pi0). Enjoy!!

Edgar Carrera (BU)

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I think the pictures says it all. This is the beginning of a new era of discovery for particle physics. Excellent job by all my fellow collaborators on ATLAS and the LHC! Hopefully much more data is soon to come. It makes me very excited about the future.

Here is where our public event displays are located.

7 TeV Collision Event

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CMS one of the 1st collision events at 7 TeV

After years of hard work by many people, after several weeks of intense work for preparation, and after several hours of holding our breaths, we finally got stable colliding beams at the record center-of-mass energy of 7 TeV.  Today, Tuesday 30th of March of 2010, CMS captured these beautiful collision candidate events!!!

You will see them appearing  here soon!!!

A new era of exciting physics (hopefully discoveries) has just started, a renaissance of science, which will most certainly change the way we perceive our universe and trigger an enhancement of our own humanism.

Cheers for particle physics and for humankind!!

Edgar Carrera (Boston University)

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These are plots of the horizontal and vertical positions at CMS where collisions will be expected to happen.  They were measured from “beam gas” events by experts from the CMS Collaboration.  There is a small offset of about 100 microns in one of the directions.  This information is being passed to the LHC operators.   The moment of truth approaches, stay tuned….

Edgar Carrera (BU)

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We will enjoy about one hour of stable non-colliding beams at 3.5 TeV.  When was the last time we saw all those indicators “true” and “green”?  It looks beautiful; congratulations LHC, and thanks!!….. we can’t wait for collisions!!

Edgar Carrera(BU)

lhc stable non-colliding beams at 3.5 TeV per beam

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We’ve been getting word that 7 TeV collisions are supposed to start happening tonight as early as 7 am at CERN (1 am Eastern standard time). As I’m writing the sign on the LHC Ops page is Beam Status: Ramp (the current energy is 480  GeV… no wait 500 GeV and rising ). I’ll be watching the ATLAS control room live tonight (got the coffee pot going already)… but for those of you who want to watch too here’s a couple of links:

From the LHC control room. The webcast will start at 8:30 am at CERN (2:30 am Eastern).

From the ATLAS control room.

This one is already live streaming. Be on the look-out for my former roommate Stephanie, she’s run coordinator for the Liquid Argon Calorimeter tonight… and I’m sure she’ll appreciate me mentioning her in the post. I’m so jealous she’s there on the front lines. I know we’re all really nervous and hope everything goes well.

So tune in to watch!!!

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The first proton collisions at 7 TeV are supposed to happen tomorrow morning Geneva time – maybe just in time for people to be watching the morning news in Europe!

By the way, let me mention about the word “buckets” on the LHC beam status page.

Basically, the proton beams aren’t continuous – they are kept in tiny bunches or “buckets.”  The bunches in both beams go around the LHC ring at the same frequency and only cross at specific points.  So for protons to collide they have to be in synchronized buckets, or else they won’t be at the crossing point at the same time.

So keep an eye out, because soon, the LHC will be smashing together the world’s highest energy “buckets o’ protons”!

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I thought it best to write a post now, as I won’t have a chance to during this Tuesday’s excitement — not because I’ll be so wrapped up in first 7 TeV collisions, but because it’s going to be the first day of Passover, which will take me partially offline. (Who exactly thought that this would be a good day for the big event? Well, it had to be on some day or another.) Just like last time, I plan on sleeping through the big event, as I thoroughly expect it to be uneventful.

For instance, don’t expect any radically new science to emerge from the first days of collisions. While it appears that the experiments are really in excellent shape, based on the work done with the December collisions, it will take a long time to accumulate and analyze enough data before we can definitively say that we have observed any new physics. The amount of data we expect to take in these next two years is enough to make the LHC experiments competitive in discovering new phenomena, or constraining what new phenomena might look like, but that’s still two years worth of data. So, as the old saying goes, this is a marathon, not a sprint, and we have to pace ourselves.

But on the other hand, everyone is motivated to get out some kind of result as soon as possible, to demonstrate that the experiments do work and that we’ve got what it takes to complete the marathon. The major milestone is the International Conference on High Energy Physics, which starts on July 22. By then, everyone is hoping to have a bunch of real physics results (even if they are merely confirmation of known phenomena rather than discoveries) that can set the baseline for the performance of the experiments. July 22 is sixteen weeks from this Thursday. To go from having no data at all to high-quality measurements in sixteen weeks is going to be quite a feat. Put on top of that the uncertainty of just how well the LHC will perform over this time — by ICHEP, we definitely expect to have a million times as much data as we recorded in December. But it could turn out to be be ten million times as much! Whether any particular measurement is feasible or not could depend on which end of that range we end up on, and there might be many course corrections to make as we go along as a result.

So even though the real LHC physics program is a marathon, on your marks, get set….

KB

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Update (3/26): I should probably clarify that this post focuses on theories for new physics beyond the Standard Model. We certainly do have well-established theories that are absolutely spot-on within their regime of applicability, e.g. the Standard Model, quantum electrodynamics, general relativity… these have all been tested experimentally over and over and over again.

One our goals here on the US/LHC blog is to clarify a few public misconceptions about  physics. One thing that the popular press seems to get consistently wrong is that people are married to their models—by which I mean “plausible, but speculative, frameworks for explaining natural phenomena.”  Journalists will often write about a physicist’s pet model by starting with “Professor So-and-So believes that…,” as if Professor So-and-So goes to bed at night thinking of ways to explain to the world why his/her model is right and everyone else is wrong.

That’s not how science is done, not even speculative science. Just because someone spends some time developing a new idea, that doesn’t mean that they are doing so because they think it must be true. This may sound silly: if they don’t think its true, then why devote so much time to it?

One answer is that it could be true. Thus we should figure out what falsifiable implications it would have if it were true so that future experiments can cross it out. However, there’s a deeper reason to pursue ideas that one isn’t necessarily “married to.”

The point is that good ideas have value  just because they’re good ideas, even if they are necessarily speculative. Certainly a “good” idea should be plausible, e.g. a model of “intelligent falling” would have a very hard time garnering serious interest. However, there are plenty of good ideas out there for open questions. Of course we really want to find the “right ideas,” but there’s no way to know which ideas, if any, will ultimately be reflected in nature. All we can know are which ideas fit present data and which have strong theoretical (somewhat subjective) motivation. Rigorously exploring these ideas, their implications, and their inter-relationships allow the field to move forward.

[An interesting side note: it's not even clear that there should be only one idea which is "right." Much of the modern progress in theoretical physics is based on the idea of "dualities," i.e. two totally different models describing the same physical phenomena in complementary ways.]

The value of “wrong” ideas is something that’s often under-appreciated in the popular press. In fact, theoretical physicists are usually interested in building up a tool-box of good ideas (independent of ‘correctness’ for a particular problem) that can be used as needed to solve open questions. One popular example is string theory.

1. Our front-running speculative “theory of everything” wasn’t born with such grand aspirations: rather it was originally constructed as a potential model to explain the weird particles that were showing up at the old-school colliders of the 1960s. Later experiments showed that correct explanation (quantum chromodynamics) was something rather unrelated, and string theory (then known as “dual resonance models”) fell to the backs of everyone’s minds…
2. … until some clever theorists realized that it could be used to give a quantum theory of gravity. This became a hip thing to study in the 80s and especially 90s, but since then has lost a bit of steam due in part to its lack of experimental predictions at accessible energies.
3. But that’s okay: while people were playing with string theory as a “good speculative idea,” they discovered some very unexpected dualities between higher dimensional gravity theories (which are relatively well-understood) and lower dimensional models of strong coupling (which are notoriously difficult to work with). These ideas are usually referred to as the “holographic principle,” and have shown promise as models of, among other things, the very same kinds of particles that originally motivated string theory in the 1960s! (In coming full circle several new and rather deep insights were developed.)

Stories like this can be found all over the place in the history of physics. The extra dimensional models which became very popular in 1998 and 1999 are based on the Kaluza-Klein models from the 1920s, but adapted to solve new problems. The idea of electroweak symmetry breaking and a Higgs boson was built upon progress in understanding superconductivity. Good ideas never really die, they just lay dormant until the next big problem comes along.

In this sense, the measure of a theoretical physicist isn’t necessarily how many “right ideas” s/he has generated. (Indeed, in the past 30 years there hasn’t been enough experimental sources to definitively say anything about many good ideas.) Instead, the community values creative new ideas. And for what my two cents are worth, fostering this creativity—in multiple disciplines (arts, humanities, sciences, mathematics)—should be one of the main goals of primary and secondary education.

For what it’s worth, the ‘good idea’ that I personally think is most theoretically appealing is supersymmetry. But as evidenced by Cornell’s recent loss in the NCAA basketball tournament to #1 seeded Kentucky, most of the things that I cheer for don’t seem to benefit from my support. (PS, Big Red: we’re proud of you!)

-Flip, US/LHC blog

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Hi there!

The LHC is about to start colliding protons at 7 TeV (3.5 TeV per beam) or with about three times more energy than has ever been achieved by man. This is really exciting stuff! We’ll have a big media day on Tuesday to make sure everyone has a front row seat to the event!

Last night I was asked an interesting question – interesting enough that I thought I’d share the answer.

Will we collide the beams at many energies, or only at 7 TeV?

The LHC is really a discovery machine. Imagine that you’re back in 1490, and we’ve built a new ship that is capable of going seven times further than any previous ship in history before it needs to land (to refresh its stores, etc). The first thing we want to do with this is take it as far as it will go to see what’s out there! It could be that we’ll find a whole mess of new particles – that would be wonderful! It could be that we find nothing at all. That really would be like Columbus sailing for the new world and coming to the edge of the earth! It seems impossible and would fly in the face of everything we know – for physicists, it would be almost as interesting as finding a load of new particles! And, of course, when you’re sailing that far, you might pass some interesting things along the way…

Once you’ve searched for new high energy physics, you might want to try collisions at a few different energies. That would be something like looking for islands in the Atlantic. They might not be as exciting as a new continent, but they’re worth searching for all the same. Technically, just like if we were to sail out, we have no choice but to pass all the energies in between. But we do so for only a moment, and don’t really pause there to do any significant search in the middle. Side note: the middle energies aren’t quite as exciting at the LHC as they would be at, say LEP, because protons are “composite”, rather than single objects (as one professor put it, it’s like colliding two garbage cans). You can get some sense of what’s going on at lower energies from the higher energy collisions.

So on Tuesday, you should expect to see the beams go up from 450 GeV each (when they go into the machine) to 3500 GeV each (when they are colliding) without stopping in the middle – unless they plan something I don’t know about, of course!

One fun (very) technical note. Computers have a clock that keeps them in time (your computer is probably 2 GHz, for example). The whole LHC acts like a giant set of computers, all of which are timed together. It’s as though the entire thing has a single heart beat, around 40 MHz. We actually keep the heartbeat going at just the right pace to always have collisions “on time.” But the protons are changing energy from when they are injected at 450 GeV to when they collide at 3.5 TeV!! That means the entire heartbeat of the machine speeds up just a little bit to keep up (because of relativity, it’s only a fraction of a percent, but it is noticeable!!). To make sure things are safe, ATLAS usually stops collecting data while the heartbeat is actually changing – it’s a delicate operation, and we don’t want to have to stop to fix something right before the data arrives! So we may or may not actually see any of the collisions at energies between 900 GeV and 7 TeV!

EXCITED!!

–Zach

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Phew… the past 3 days were our perspective student weekend. We put on our best foot forward to show accepted graduate students what life at SB is like. The current graduate students host the visitors – we show them around campus, take them to places in the area, to breakfast – the professors tell them about opportunities in the grad program… all-in-all a good time. Plus… lots of free food, my little office fridge is bursting with leftovers. (bagels and pizza… breakfast of champions).

It’s always nice to interact with incoming students because it reminds you what it was like to not be caught up in the little details of research. It lets you look at the broad picture and remember the science behind all the compiling code. Plus it’s exciting to talk about all the happenings at the LHC. There were quite a few people interested in particle physics… yay! Nothing like a couple of days of just talking about the physics of particle physics. I think I said “supersymmetry” in the past few days than I have in the past few months. Plus Sunday was so nice, we even went to the beach! — surely that’ll convince people to come here.

But now back to work… the work of particle physics. The vaca was nice while it lasted.

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….. is what we are hoping  to have next Tuesday   The LHC made it official, and so they will attempt to collide the two proton beams at 3.5 TeV each, on Tuesday March 30.

It’s 01:15am and I just got home after a quite long day of work (although shorter than I expected).  Everything needs to be ready before we get collisions, so the efforts have to double.  As part of the high level trigger team in CMS, my work this week consists in making sure that we are able to accept all the good collision events (data).  After a few days of intensive testing from different groups and people, we hope we will deploy the final version of the trigger “menu” tomorrow, or on Thursday the latest.  The high level trigger is a key component of being able to accept data.  It is basically a collection of code that runs online, live, to discriminate what information is put into tape and what is not.

It is very likely that  we will have lower energy collisions (900 GeV) during the weekend as a preamble for the historic 7 TeV smashings. We also need the trigger to catch beam gas events from 3.5 TeV circulating stable beams (no collisions), maybe on Sunday.

The adrenaline is starting to flow here at CERN.  It is somehow difficult to sleep, thinking about all this, for people like me who are on-call.  Most of the improvements, fixes, upgrades, etc, that we made after the learning experience of last year’s collisions are now in place, and ready for prime time.   We will do just fine.  I am sure.

Edgar F. Carrera (Boston University)

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Hi there!

This morning there’s been a press release from CERN announcing March 30th as the first attempt for collisions at 7 TeV! You can still follow CERN or ATLAS on Twitter for all the action…

A little reminder – these collisions will be 3.5 times higher energy than our competitors at the Tevatron, and 3 times higher than we reached at the end of last year (when the last record was set). Because of the higher energy, we should be able to quickly match the Tevatron’s sensitivity to “new physics” – what ever that might turn out to mean…

If all goes well, this will mark the start of a very exciting year in physics!!

Will things ever be the same again?? It’s the Final Countdown!!

–Zach

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Click for live beam status.

Early this morning in Geneva, for the first time ever, both proton beams were each ramped to 3.5 TeV.  This is higher than when the LHC set the record for highest energy collisions in December.

The image here is the current beam status.  Keep your eye out for more high energy beams later today!

–Mike

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