New Type of Particle May Have Been Found 281
An anonymous reader writes "The LHC is out of commission, but the Tevatron collider at Fermilab is still chugging along, and may have just discovered a new type of particle that would signal new physics. New Scientist reports that the Tevatron's CDF detector has found muons that seem to have been created outside of the beam pipe that confines the protons and anti-protons being smashed together. The standard model can't explain the muons, and some speculate that 'an unknown particle with a lifetime of about 20 picoseconds was produced in the collision, traveled about 1 centimeter, through the side of the beam pipe, and then decayed into muons.' The hypothetical particle even seems to have the right mass to account for one theory of dark matter."
More data, less hype at arxiv (Score:5, Informative)
The New Scientist article points to a paper at arxiv:
http://arxiv.org/abs/0810.5357 [arxiv.org]
with the rather less sensational title:
Study of multi-muon events produced in p-pbar collisions at sqrt(s)=1.96 TeV
I'm amused to note that the author list stretches over three pages, which I gather is common for this sort of paper.
Probability? (Score:2, Informative)
The question here is about repeatability, and given how long it's taken to have an anomaly like this surface, the only other accelerator that might be capable of confirming this find (ie, doing it again) is probably the LHC.
Anyone know what the probability of doing this again might be?
CV (Score:5, Informative)
Re:please let it be the higgs boson (Score:4, Informative)
If the standard model is wrong, there are almost certainly more particles to be found at higher and higher energies (see any website that is pulled up by googling "beyond the standard model"). And the tevatron isn't likely to probe much higher energies...
Re:One theory of dark matter eh? (Score:5, Informative)
Not to ask the blatantly obvious, but if it's the right mass for one theory of dark matter, I can't help but wonder where they are all being produced. Given a life of 20 picoseconds, I can't imagine that there would be monstrous factories of these things all over the universe to account for the stupidly large amount of mass they are supposed to account for. How come we haven't found them before?
I thought the same thing at first, but the article states that they are theorizing that the particle produced is not a dark matter particle itself, but rather the particle that carries forces between dark matter particles. It is entirely possible that there are stable dark-matter particles, but for the force-carrying particles to be unstable when produced in isolation.
Re:coincidence? (Score:5, Informative)
The Tevatron is big money science. the LHC is bigger money science.
Re:please let it be the higgs boson (Score:1, Informative)
"The Higgs boson is frequently referred to as 'the god particle', a name adopted after Leon Lederman's book which enjoyed wide popularity. "
http://en.wikipedia.org/wiki/Higgs_boson
Nice job making yourself look like a complete tool.
Re:hardly news... (Score:1, Informative)
No, a capacitor blew, so they had to de-cool the entire facility to get in and inspect it. Because it's coming into European winter, and the facility takes months to cool, they've had to wait until next year (I'm not sure why it doesn't work in winter, but I'm from warmer climes, so there's probably something about extreme colds I'm not aware of). Also, the beercan sabotage thing was with an earlier facility, but you'd have to check on wikipedia to see which one.
Anonymous to mod on this thread :)
Re:hardly news... (Score:5, Informative)
That's because it takes a lot of electricity to cool the collider down. Europeans like to use a lot of electricity to keep their buildings warm in winter, which drives up the price of electricity. So they wait for summer when electricity is cheaper and the giant German solar panel farms are pumping out lots of jiggawatts.
Re:One theory of dark matter eh? (Score:5, Informative)
More than possible. Of the force carrying particles we know of, only the photon is stable. The graviton, if it exists, should be stable. But the W+/-, Z and all the various flavours of gluons are unstable.
Re:coincidence? (Score:5, Informative)
The real stuff has gotten pretty tough. I had the challenge once to rework a preproduction board to prove a design change. I was way out of my comfort zone.
Resistors these days are the size of a juvenile flea. If you drop one, let it go man... it's gone. ICs aren't much better. You have to use IPA and a lintfree cloth just to clean the soldering tweezers. It takes a 60x microscope and a steady hand. I was really regretting my caffeine habit. And the tiny static charges make everything sticky. The leadfree solder takes more heat so you have to be extra careful not so bake the components to death. And don't stab yourself with the tweezers. They look like pencil erasers in the scope but they'll penetrate your skin with no resistance, burning the whole way.
It worked. It wasn't pretty, but it worked. I am thrilled to have had the experience. I wish I knew a vendor for the surgical point soldering tweezers.
Respect to the asian ladies in the factory that do this all day for a pittance, with nothing more than a magnifying glass and grim determination.
Re:Uhh... (Score:1, Informative)
Re:One theory of dark matter eh? (Score:2, Informative)
Given a life of 20 picoseconds, I can't imagine that there would be monstrous factories of these things all over the universe to account for the stupidly large amount of mass they are supposed to account for.
The factory was only working for about 100 picoseconds and most of the product was consumed in short order. Like CueCats though the unused product remains, eating up storage costs throughout the universe as we know it. Buy yours today!
Seriously, though - a simpler explanation for the unexplained phenomena could be that the "gravitic constant" is not constant, as we know it to not be. If its inconstance is nonlinear that would explain a lot. A logarithmic depreciation of the gravitic constant from the big bang to now could well explain a lot of the presently supposed "dark matter" and "dark energy".
Re:coincidence? (Score:4, Informative)
They do for the most part. But almost inevitably somebody makes 200,000 circuit boards, only to discover that something doesn't work and it to be reworked. Three resistors, a capacitor and an IO connector have to be changed. It's boring work in a toxic environment under appalling conditions. But it's got to be done if you want that new BluRay player under your tree.
Re:1 cm in 20 pico secs..? not so fast..?! (Score:3, Informative)
The statement in the article is correct!
The (half) life-time of a particle is the time measured with a clock traveling with the particle, which slows down when approaching the light speed c. Hence the path it 'survives' becomes longer.
That's relativity.
Re:1 cm in 20 pico secs..? not so fast..?! (Score:5, Informative)
Your math is way off. Using google:
(20 picoseconds) * c = 0.599584916 centimeters
Given that
1) 20 picoseconds is a half-life
2) Time slows down for the muons.
It's not surprising that they travelled about 1cm.
Re:coincidence? (Score:2, Informative)
The number of unexpected particles is ~10**5. This is not a statistical phantom, although the physical significance remains to be seen.
Re:coincidence? (Score:3, Informative)
Hot air is your friend for soldering.
As a mere hobbyist, some of my designs use ICs with 0.4mm pitch pins (0.2 mm gap between the pads). I have made my own PCBs at home to mount these on. It takes care but it can be done and it doesn't require more than a magnifying glass. However, thanks to reasonably low cost PCB prototyping houses, I usually get the PCBs for that sort of thing made by one of those these days :-) I've even soldered 0.4mm pitch LQFP with a normal soldering iron with a pointy tip.
Hand soldering 0603 discrete components isn't hard and can be done with a normal soldering iron tip. Some hobbyists have used 0402 parts (and I bet some masochist has tried 0201), but I think 0603 for me is a good tradeoff between small size and my ability to handle them.
However, I've found solder paste and hot air really is the way to go. It's so much easier and neater. I have a little syringe of the stuff, it needs an incredibly small amount of it on each pad, and for ICs, just a bead of solder paste run along the pads. For hot air, I use an inexpensive hot air gun which on the low setting is the correct temperature for reflow. Surface tension is also your friend - slightly misaligned components will magically align themselves as the solder paste melts.
Others use electric skillets for reflow, or toaster ovens. Lots of hobbyists are doing fun things with tiny components now. Last night, I was soldering leadless packages on a home made PCB, using solder paste and hot air. Nearly all of my electronics projects now use fine pitch surface mount, and with hot air and paste I can mount resistors and capacitors etc. much faster than I can the equivalent through hole parts.
Hot air is also great for rework - use a nozzle to just heat the IC you want to get off, wait for it to all warm up, then remove it with tweezers.