Princeton Student Finds Bug In LHC Experiment

An anonymous reader writes "A Princeton senior has found a bug in the hardware design for the Compact Muon Solenoid (CMS) experiment of the Large Hadron Collider (LHC). In the hardware used to record and capture events in the LHC, she discovered errors that were leading to the appearances of double images because of particle streams known as jets. 'Xiaohang Quan '09 was working on her senior thesis when she found a miscalculation in the hardware of the world's largest particle accelerator. Quan, a physics concentrator, traveled to Geneva, Switzerland, last week with physics professors Christopher Tully GS '98, Jim Olsen and Daniel Marlow for the annual meeting of the European Organization for Nuclear Research (CERN). This year, however, they also came to discuss Quan's discovery with the designers of the hardware for the Compact Muon Solenoid (CMS) experiment, which, as part of the Large Hadron Collider, has the potential to revolutionize particle physics.'"

wha?

[Lord Ender (156273)]

Her last name is "09" and she is a "concentrator?" Who wrote this?

Re:wha?

[scheme (19778)]

Her last name is "09" and she is a "concentrator?" Who wrote this?

It's from a student newspaper. Hence the 09 which refers to her graduation year. Also the concentrator part means that she's concentrating on physics. Some universities call it concentrating on a subject rather than majoring.

A concentrator!

[hellfire (86129)]

Some universities call it concentrating on a subject rather than majoring.

That's because years ago, teachers found out most students don't concentrate on anything.

But this girl is definitely the exception, she's obviously concentrating very hard.

Re:

[Rakshasa Taisab (244699)]

I've found thousands of bugs... Why aren't anyone writing stories about me? ;(

Re:A concentrator!

[icebraining (1313345)]

Have you found thousands of bugs on billion dollar projects announced by the media as world-sucking black-hole producing machine?

Re:A concentrator!

[Walkingshark (711886)]

Have you found thousands of bugs on billion dollar projects announced by the media as world-sucking black-hole producing machine?

I found some bugs in Tim Geitner's bailout plan, which seems to match the second part of your criteria...

Re:A concentrator!

[sortius_nod (1080919)]

...the computer side of it is written a lot by grad students and others without any formal CS training. Bugs pop up.

I really don't think that's a valid statement. Bugs pop up in anything, CS trained or not. In fact, some of the best coders I've come across have been untrained.

Arrogance like that is a reason why there are bugs in programs...

Re:A concentrator!

[Man On Pink Corner (1089867)]

Is there a way for experienced coders to volunteer to help?

Re:A concentrator!

[Xest (935314)]

I agree that Physics is probably the hardest of the Sciences (unless you class Math as a science rather than as it's own area of study). I also agree physicists are almost certainly intelligent enough to learn to be great programmers.

The problem is that a lot of physicists I've met don't want to be programmers or don't have time to learn to be good programmers on top of everything else. They want to use computers to help them solve problems but they don't want the hassle of dealing with memory allocation and all that.

Just as many great physicists have required the assistance of great mathematicians through the years, I think the dawn of computing does bring a place for computer scientists to work alongside physicists.

It's also worth pointing out it's not just about writing effective code, it's about writing zero/low defect code, efficient code, possibly even maintainable and reusable code. A physicist may be able to learn what's needed to solve his problem, but if his problem is one that with his solution may take weeks on the university computing cluster then it makes much more sense for him to work with a computer scientist who may be able to tweak/re-write his program to solve it in days or even hours instead.

Computer scientists are important to science not because they can necessarily contribute directly to science itself, but because they have invested the time, likely years and years into learning how to use computers in the best way possible, sure a physicist can learn to use and manipulate them, but there's no way on top of their own discipline they can learn the ins and outs a computer scientist does.

Mathematicians, Computer Scientists, Physicists, all have their place and all augment each other well, none are as effective alone as they could be with others. Even Steven Hawking, arguably our finest living physicist has always had (even before he became so severely disabled) to work with the great mathematicians are Cambridge and computer scientists.

Re:wha?

[Red Flayer (890720)]

Also the concentrator part means that she's concentrating on physics. Some universities call it concentrating on a subject rather than majoring.

What a load of horsecrap. Do you even go to Princeton?

At Princeton, students are labeled by their preferred method of problem-solving.

Some students are "blackboardists" (though this label is being phased out for a more color-neutral label, since some students use whiteboards. Also something about racism. "Vertical writing surfacist" is just unwieldy, I think they'll settle on "writist".) Some students are modelers -- but these tend to be chemists.

This student is a concentrator, a la Feinman.

When asked how Feinman would solve a specific theoretical physics problem, a famous physicist (I can't recall who it was), said, "He'd close his eyes for a minute or two, then write the solution on the blackboard."

At any rate, I'm very surprised a concentrator was able to find a hardware problem. Ususally concentrators don't bother with hardware, since the solution comes directly from their wetware.

Just to note, that there are other types of problem-solvers at Princeton as well, but they are not as common in the Physics department. In the Fine Arts, one finds "Lysergicists", in Liberal Arts one finds "Inhalors". Most dropouts are "Procrastinists", and if one is very luck, you can spot an "Osmosisist" on the green -- you can tell them from others by the fact that they always carry their books on their head.

Re:

[dgatwood (11270)]

...in Liberal Arts one finds "Inhalors".

Where I come from, they're called potheads.

Re:

[Red Flayer (890720)]

I think the label is meant to be inclusive. We wouldn't want to leave out the painthuffers and methsmokers, would we?

Re:wha?

[by Anonymous Coward]

That's her model number. She's actually a Japanese Robot.

Re:wha?

[Quothz (683368)]

Her last name is "09" and she is a "concentrator?"

That threw me, too. The '09 appears to be standard form for the Princetonian, representing her (expected) graduation year.

Who wrote this?

Tasnim Shamma

Personal Info

* Degree: A.B. in English, IPS in Journalism

* Hometown: Jamaica, NY

* Contact Email: [e-mail]

Personal Bio

Princeton '11, Brooklyn Technical High School '07, Daily Princetonian news/blog/multimedia staff, Orange Key tour guide, Daily Princetonian Class of 2001 Summer Journalism Program Alum'06/ Program Staff Associate '08 (www.princeton.edu/sjp), Aspiring Reporter (if there are jobs left when I graduate) ;)

Off topic: Miss Quan is cute.

Re:wha?

[by Anonymous Coward]

Off topic: Miss Quan is cute.

Funny how the site got slashdotted right after your comment appeared.

Re:She is hot!!

[Hork_Monkey (580728)]

She'd also find all those bugs crawling around.

Re:

[edittard (805475)]

Pity the "anonymous reader" didn't go the extra nine yards and become an invisible writer. Then we'd never have known what a waste of oxygen he was.

Great story.

[palegray.net (1195047)]

She just made her career, and rightfully so.

Re:Great story.

[Gromius (677157)]

Its not actually amazingly impressive, its made to sound a lot more impressive than it actually is. One the meeting in question was "CMS week", one of several weeks a year we get all our collaborators together at CERN not CERNs annual meeting. She's basically improved our jet algorithm (as far as I can tell, the article is woefully lacking in details), a decent job for an undergraduate and will certainly help her walk into a PhD place as a shes clearly good enough but she's certainly not the only undergradute to have made a contribution such as this.

Re:

[Walkingshark (711886)]

but she's certainly not the only undergradute to have made a contribution such as this.

Woah woah woah there. Didn't anyone tell you undergraduates aren't good for anything and undergraduate degrees are only useful to show you can "complete something?" Get with the latest talking points there please.

Re:Great story.

[Gromius (677157)]

These undergradutes are members of the collaboration working under supervision of experienced physicists so they have full access to everything. Anyway consulting the technical design reports [cms.cern.ch] will give you some hardware info on CMS but its not really presented in a way accessable to a non physicist.

If it smells, it's chemistry,

[MadMidnightBomber (894759)]

if it moves, it's biology. If it doesn't work, it's physics.

Re:If it smells, it's chemistry,

[Tubal-Cain (1289912)]

if it moves, it's biology.

Or gravity.

Behind her back..

[kop (122772)]

They are calling her "Gordon" and are scheming to get her to be the guinea pig in the resonance cascade scenario test.

Re:Behind her back..

[ijakings (982830)]

He is already there

http://www.gotogrado.com/sistema/data/upimages/Gordon_Freeman_Spotted_At_CERN.jpg [gotogrado.com]

Re:Behind her back..

[Man On Pink Corner (1089867)]

Someone actually did [google.com] send him a crowbar.

Job prospects

[bigredradio (631970)]

I would have to say that this student will not have a problem finding a job after graduation.

CERN: Now Xiaohang, Sherry is going to show you around the place. She can answer any questions you might have about fringe benefits or dress codes or anything and I'll see you back upstairs when you're done, okay? Sherry, take good care of this young lady. She's one of the ten finest minds kin the country.

XIAOHANG: Someday I hope to be two of them.

Not a hardware bug

[rminsk (831757)]

A Princeton senior has found a bug in the hardware design for the Compact Muon Solenoid (CMS) experiment of the Large Hadron Collider (LHC).

The bug was in the algorithm analyzing at the data from the CMS and not the hardware.

Re:Not a hardware bug

[by Anonymous Coward]

Actually, not a bug at all. It's a design choice.

The CMS Global Calorimeter Trigger hardware uses a 3*3 sliding window algorithm to find local maxima (jets) in the calorimeter regions. These 3*3 windows can partially overlap, meaning some energy is double-counted. Having a small amount of double-counted energy has no real consequence on the validity of the triggering, but does greatly simplify the firmware.

Eliminate bugs BEFORE the experiment: +1, Helpful

[by Anonymous Coward]

via hardware verification with ACL2 [utexas.edu].

I hope this helps the LHC Experiment so it doesn't cause
a black hole to destroy THE UNIVERSE.

Yours In Physics,
Kilgore Trout

This is awesome

[adpe (805723)]

This story makes me fall in love with science even more. Smart people think of ways to understand the world better, other smart people review it, find errors and discuss their finding with other scientists.
They have a discussion like adults, they look at the math, one side is correct and they correct their experiment and thank them for the contribution.
This is what the world is supposed to be like. Not like these fucking religois nutjobs, screaming at each other, arguning who has the cooler imaginary friend, without having even a halfway decent argument. They're just like "You're stupid!". "No, you are!". "No you!"
Science for the fucking win!

Re:This is awesome

[rhizome (115711)]

Smart people think of ways to understand the world better, other smart people review it, find errors and discuss their finding with other scientists.

Absolutely. I'd be curious to know whether anything like this has ever happened in the world of Intelligent Design or any other theological science disciplines. "Regent University Senior find new method by which God created the universe!"

Re:This is awesome

[Gotenosente (1496667)]

Absolutely. I'd be curious to know whether anything like this has ever happened in the world of Intelligent Design or any other theological science disciplines. "Regent University Senior find new method by which God created the universe!"

Actually ancient Indian spiritual literature is filled with accounts of various spiritual leaders debating each other. Often times, if one lost the debate they'd have to study under their victor. It was during this era that one of the world's great international universities, Nalanda [wikipedia.org], was created. Later it was burned to the ground by invading Muslims.

Re:This is awesome

[Mr. McGibby (41471)]

Yup. Scientists never argue or deride the work of their colleagues without merit. Never.

In case you missed it, I'm being facetious. Irrational disagreements and other immature behavior are a human problem. The scientific community is no less guilty of this than anyone else.

Re:This is awesome

[Godji (957148)]

Yes, but in said community counterarguments like "Here's the math and it works out, while your doesn't due to this counterexample!" work. Try that with the religious nutjobs.

Re:This is awesome

[Ohio Calvinist (895750)]

I think the statement needs a little intellectual honesty. I do agree that the scientific method when used properly is wonderful thing and this case is an example as such. However to limit "close mindedness" to "relgious" people sounds good on /. and gets you some cred with the groupthink crowd, but is pretty weak.

It takes a high degree of personal humility to be open-minded. Particularly when you have a vested interest in a particular outcome, (beit relgious, scientific, political, etc...) many people to greater or lessor extents need to actively pursue impartiality. There are many spheres of life such as politics, sports, business, science, etc. where you find members of those communities not engaging in meaninful dialogue, because they have a vested interest in a particular ideology or theory or methodology.

I have been in lectures where Ph.D.'s would not intellegently debate and discuss a particular set of data or therom contradictory of their own research/worldview. In some scientific fields there are positions you can take that will effectively kill your chances at a tenure-track faculty position; even if you are taken to those positions by the data against your will.

On the other hand I've been in discussions of a religious or political nature where those in discussion where members were looking for insight from other members; including those who were diametrically opposed, because they recognized that they didn't have it all figured out and they'd either be convinced of an alternate or affirmed in their existing position. This isn't to say that religious, poltical, business communities are better or more open minded, or anything to that effect, just that your generalization simply isn't accurate.

Science is great when it is really science. Science is truly lamentable when the theory trumps the data because the theorizer has far too much to lose if the theory is disproven or radically challenged; and broken theories are taught as immutable truth.

Cool.

[Colourspace (563895)]

Just delays us nearer to 2012?

Implications for discovery of new particle.

[gillbates (106458)]

Research has led to the discovery of the heaviest element yet known to science. The new element, Governmentium (Gv), has one neutron, 25 assistant neutrons, 88 deputy neutrons, and 198 assistant deputy neutrons, giving it an atomic mass of 312. These 312 particles are held together by forces called morons, which are surrounded by vast quantities of lepton-like particles called peons. Since Governmentium has no electrons, it is inert; however, it can be detected, because it impedes every reaction with which it comes into contact. A tiny amount of Governmentium can cause a reaction normally taking less than a second, to take from four days to four years to complete. Governmentium has a normal half-life of 2-6 years. It does not decay, but undergoes a reorganization in which a portion of the assistant neutrons and deputy neutrons exchange places. In fact, Governmentium's mass will actually increase over time, since each reorganization will cause more morons to become neutrons, forming isodopes, not to mention multiple oxymorons. This characteristic of moron promotion leads some scientists to believe that Governmentium is formed whenever morons reach a critical concentration. That hypothetical quantity might normally be called 'critical mass' but, in this unique case it is known as 'critical mess'. When catalyzed with money, Governmentium becomes Administratium (Am), another just-discovered element that radiates just as much energy as Governmentium since it has half as many peons but twice as many morons.

Bush also found an error in Fermilab calculations

[noidentity (188756)]

It's little-known that Bush also found some critical errors in Fermilab calculations [theonion.com].

young physicists

[Goldsmith (561202)]

"If you haven't done anything in physics by the time you're 21, you never will."

I've been told this quote comes from Heisenberg, and at the time I heard it, I thought it was a load of crap. However, the idea is correct. If you want to be a physicist, you have to be able and willing to jump into research right at the beginning (as an undergraduate), or you'll probably never do real research. Of course, most undergraduates don't end up finding bugs in code which has been checked by dozens of postdocs and grad students.

Re:Public Spin

[JoeBuck (7947)]

Once again: if there were any chance that LHC could produce earth-swallowing black holes, we'd be dead long ago, because Earth is regularly hit by much more powerful events than anything the LHC will be able to produce.

Re:

[Meumeu (848638)]

Once again: my buddy got shot by one of those high velocity armour piercing rounds; it went straight through him, hardly any damage at all. So there's no chance at all anyone'd be hurt by one of those namby-pamby pistol rounds. They'd probably bounce right off or something.

Did he also get shot at billions of times per second for 4.5 billion years?

Re:

[Tumbleweed (3706)]

Sorry, I meant to say 'NOT representative', the mistake in doing that is, of course, representative, therefore, I was correct either way. Ha! Next, I shall go on to prove black is white.

Re:they should not turn it on

[Tubal-Cain (1289912)]

until enough people / scientists are SURE nothing bad will happen.

The only way to know that is if they know exactly what will happen. And if you know exactly what will happen, what's the point?

Re:they should not turn it on

[JoeBuck (7947)]

You are ignorant; the universe is already conducting high-energy physics experiments. They are called cosmic rays, and some of them are billions of times more powerful than the LHC. Yet the earth is still here. And your notion that we delay until we completely understand the laws of physics is comical. What do you think the LHC is for? It's to help us understand the laws of physics! You don't discover laws of physics by just thinking deeply. You discover them by experimentation.

Re:

[JWSmythe (446288)]

It all depends on where you work.

I've seen businesses make decisions on thousands of lines of code in meetings after meetings, where they don't actually bring a computer, nor a line of code in. They theorize. They ponder. They wonder. They question. Then they come out of the meeting, and tell the developer how he screwed up. The theory and the reality very rarely coincide.

I like to throw them, by giving them a dozen different yet plausible theories as quick

Re:they should not turn it on

[amRadioHed (463061)]

Yeah, no more research until we understand everything. Good idea.

Re:they should not turn it on

[Gromius (677157)]

its not really a design flaw. Basically its a minor bug in the algorithms (if I'm reading it right, the article is very confused to say the least) which allow physicists to reconstruct the energies of hadronised partons. Now we can do it a bit better and make slightly better measurements. This software we know isnt optimal, it requires a great deal of knowledge to write and to be honest a major part of the effort in the earily days of an experiment is improving the reconstruction software with fixes such as this. And there will be many more such improvements. Bugs here do not pose any danger because the software is run *after* the event has occured so it cant effect the event, just our understand of what actually happened.

Also just to make clear that the LHC and CMS are very different things. The LHC is the accelerator and its what makes the particles go very fast. CMS is a detector, it just sits there and records what happens in the collision. CMS is built and designed by a completely different set of people to the LHC. CMS doesnt need the LHC to function and the LHC doesnt need CMS to function but they are a bit pointless without the other.

Re:God made women to debug

[hobbit (5915)]

I've seen this happen too much professionally to think of it as a trend.

I've seen this sort of anecdotal nonsense too much on Slashdot to think of it as statistically significant.

Re:Har har...

[xouumalperxe (815707)]

No, no. you got it all wrong. Black holes suck. Now geology, that rocks.