Large Hardon Collider

[Tristam]

So in case anyone has been following or cares, Science published their "Breakthrough of the Year" issue the other day and they gave it to Ardi (remember the "missing link" thread). I was honestly a bit surprised given the LCROSS results, but maybe the whole water on moon thing just hasn't been given enough time to truly appreciate it?

Other notable runners up were the advances made in gene therapy (easily the most important medical breakthrough). And also progress in materials science through the use of graphene. Woozie, being the nanotubes guy, probably knows more about carbon than anyone here, but I stand in awe of graphene simply for the demonstration that if you coat a grid with a graphene monolayer and place it in an electron microscope chamber, by taking loooooong exposures you can actually see individual hydrogen and oxygen atoms (vacuum impurities) adsorbed to the graphene sheet (which is electron transparent, which I don't fully understand). Anyways, because of all the cool properties of graphene, it's becoming more useful in a variety of fields. The hubble also got a nod for recent pics that are being analyzed to discover more about the birth of stars.

Every year, I am amazed at how quickly we progress in all fields, and it's important to take note of all our accomplishments as a species. I always wonder what next year will bring. It's tough to predict major breakthroughs, who would have predicted water on the moon? Who would have thought we could see hydrogen atoms? Even the AFM work showing C-C bond densities got overlooked among all the other cool shit out there.

Where do you guys see science going in the next year?

edit: totally forgot, but relevant to the thread, Nature has published "news" that a group has detected two events that have a 75% probability of being WIMPs hitting a detector. It's all unpublished, and I'm the last person to be discussing particle physics, but apparrently based on the properties of whatever was detected, it can be predicted that the LHC should be able to see these "WIMPS" within 1-2 years. Thougts on whether the identification of dark matter will be a breakthrough? Or am I talking out of my ass?

[Woozie]

edit: totally forgot, but relevant to the thread, Nature has published "news" that a group has detected two events that have a 75% probability of being WIMPs hitting a detector. It's all unpublished, and I'm the last person to be discussing particle physics, but apparrently based on the properties of whatever was detected, it can be predicted that the LHC should be able to see these "WIMPS" within 1-2 years. Thougts on whether the identification of dark matter will be a breakthrough? Or am I talking out of my ass?

It would be a HUGE breakthrough. I'd like to see exactly what happened here when they published what they found. Afaik, WIMPS only interact graviationally. So I'm wondering what they mean by "hitting" a detector (and what kind of detector it is), and how they determined that what was 'hitting' it was dark matter.

Edit:

http://news.nationalgeographic.com/n...minnesota.html

Dark Matter Detected for First Time?
Ker Than
for National Geographic News
December 18, 2009

Dark matter may have been "felt" for the first time deep in a Minnesota mine, physicists say.

Detectors in the mine, part of the Cryogenic Dark Matter Search experiment, were tripped recently by what might be weakly interacting massive particles, or WIMPs.

WIMPs are among the most popular candidates for dark matter, the invisible material that scientists think makes up more than 80 percent of the mass in the universe.

Recently detectors in the mine recorded two hits with "characteristics consistent with those expected from WIMPs," according to a statement posted on the Cryogenic Dark Matter Search Web site.

There is a one-in-four chance, however, that the particles detected are not dark matter but ordinary subatomic particles such as neutrons, the team cautions. (Related: "Dark Matter Proof Found Over Antarctica?")

Mike Shull, an astrophysicist at the University of Colorado at Boulder, also urged restraint in interpreting the results.

"I regard this as interesting but very much an interim 'progress report' on a promising technique," said Shull, who did not participate in the research.

"I hope they've detected [WIMPs]," he added, "It's exciting if it's true."

WIMPS: Best Dark Matter Candidate?

Scientists have predicted that WIMPs can interact with normal atoms but only weakly and very rarely—hence the name.

When such an interaction happens, a WIMP careens like a billiard ball off an atom, the theory goes. But the collision leaves behind a unique signature in the form of a small amount of heat, which can be detected.

The smashup also creates charged atoms, or ions, that are detectable.

The Cryogenic Dark Matter Search experiment uses 30 detectors made of germanium and silicon crystals.

The detectors were placed a half-mile (0.8 kilometer) underground at the Soudan mine, a defunct iron mine in northern Minnesota. The deep location helps block "background noise" from other particles, such as solar and cosmic rays.

Aside from the online statement, details on the new detections have yet to be published, and members of the Cryogenic Dark Matter Search team are declining comment.

But University of Chicago theorist Craig Hogan said that while the new detections are exciting, "it's not time for the champagne bottles yet."

The real significance of the apparent find would be that it could be used to help shape future dark matter detectors, which will be more sensitive and can better rule out false hits, Hogan said.

"It's not a discovery yet, but if these detections are real, we can turn it into a discovery."

Dark Matter Origins

If WIMP detections are confirmed by other experiments, then scientists will likely want to know where the particles are coming from, the University of Colorado's Shull added.

That's because the origins of dark matter particles passing Earth could help solve other cosmic mysteries.

Some theories of galaxy formation, for instance, say that our Milky Way and other "adult" galaxies are enveloped by halos of dark matter that are densest in the galactic centers.

If this is correct, Shull said, then dark matter particles would be expected to originate from the center of the Milky Way more often than from other regions of space.

[Woozie]

My bad, I was wrong. According to wiki, dark matter interacts through Weak Nuclear force as well as gravity. It's ridiculously hard to detect something that is uncharged, doesn't interact electromagnetically, and doesn't interact through strong nuclear force (like neutrinos, for example. As a matter of fact, their detection method reminds me of the neutrino detectors).

I don't know the specifics behind WIMPS, so I have no clue how they would find it in in the LHC. I'm surprised to hear that it's even a possibility. One of my Quantum Field Theory textbooks briefly mentions dark matter, but doesn't really go into the math behind them. We probably didn't even know it's properties when the book was written. Heck, I don't think we know their properties now, which is why I'm a little confused as to how we're able to know if we're detecting one.

Edit: I just noticed there's a wiki page for detecting wimps. But I'm going to need to see it in a textbook or something before I can really understand it.

http://en.wikipedia.org/wiki/Weakly_...ntal_detection

[Eliseos]

. As a matter of fact, their detection method reminds me of the neutrino detectors).

That's what I thought also, is that the same mine they used to detect neutrinos too? I thought I remember it being somewhere in MN.

[Woozie]

Hmm, I don't know, but it would make sense to use the same mine since there's already a lab down there lol.

[Eliseos]

Yeah lol, I can't imagine too many mines being laboratory ready. Speaking of neutrinos, one of the presentations in my class was about the strong, weak, and electromagnetic forces. One of the detectors is hoping to observe proton decay by way of neutrino emission. The Super-K experiment in Japan just basically has a large pool of water, and hopes that with all of the protons, one will decay and emit a neutrino and hit the detectors. Pretty interesting stuff, and it essentially just goes to a basic and simple setup. Here's a picture showing the relative size of everything, you can see a small boat that they use to fix the detectors.

Spoiler: show

http://upload.wikimedia.org/wikipedi...62/Super-k.jpg

[Tristam]

Breaking my rule and posting direct from Nature:

An experiment buried deep beneath the forests of Minnesota has seen two events that could be the first direct detection of dark matter.

The finding is tentative — it's still possible that conventional particles might be causing the signal — but, if confirmed, it will mark the end of a decades-long search for the mysterious particles. The data from the Cryogenic Dark Matter Search II (CDMSII) experiment also suggests that dark matter should show up in collisions at the Large Hadron Collider (LHC) — the world's most powerful particle accelerator, based at CERN, Europe's particle-physics laboratory near Geneva, Switzerland.

Observations by Swiss astronomer Fritz Zwicky in the 1930s gave the first hints of the existence of dark matter. Since then, studies of the Universe's structure, and of the way galaxies rotate, have confirmed that there must be an unseen form of matter shaping the cosmos. This dark matter is believed to make up as much as 85% of all the material in the Universe, although its identity is unknown.

The two events, seen by CDMSII in 2007, are the signatures of the most likely form of dark matter, known as weakly interacting massive particles (WIMPs). Each particle could be as massive as an entire atom, yet reveal itself only rarely by interacting with conventional matter.

The possible WIMPs were caught in the experiment's crystals of germanium and silicon, which are chilled to nearly absolute zero (–273.15 ºC). When a WIMP strikes one of the crystals, it should trigger vibrations that raise the temperature of the detector very slightly; it should also create a small charge on the crystal's surface. Comparing the size and timing of the two signals can help to determine whether or not they were caused by WIMPs.
"An interesting hint"

CDMSII scientists are remaining tight-lipped about the results until they are peer-reviewed. But in a series of talks delivered over the next few days in the US and Europe, they are expected to announce that their WIMP candidates have a mass of 30–60 gigaelectronvolts — roughly 30–60 times that of a single proton. From their analysis, they believe that there is a 75% chance that both events are WIMPs, and a 25% chance that they might both be false-positives caused by stray radiation.

A three out of four chance is not good enough to claim a definitive detection of the elusive WIMPs, says Timothy Sumner, a physicist at Imperial College London, who leads a rival WIMP experiment known as Zeplin-III. "Statistically, it's not compelling," he says. The big question will be whether the experiment has adequately accounted for background radiation.

Despite being shrouded by lead bricks and located three-quarters of a kilometre underground in the disused Soudan Mine, there's still a chance that a few neutrons might find their way into the crystals and mimic WIMP signals. Stray electrons or gamma rays striking the detector's surface could also create false positives. Understanding and accounting for these backgrounds is extremely difficult and is crucial for confirming any detection, Sumner says.

Seeing two events is a tantalizing and frustrating outcome for CDMSII. Had the detector detected five WIMPs, physicists could have confidently claimed a discovery, while seeing no events at all would have further narrowed down the possible mass of the particles. "The best we could call it is a hint," says John Ellis, a theoretical physicist at CERN. "An interesting hint."
The hunt is on

The possible detection at CDMSII is the latest in a series of possible dark-matter sightings. In August 2008, an Italian-led satellite-based experiment known as PAMELA saw an excess of antielectrons (positrons) that could stem from the annihilation of dark-matter particles (see 'Physicists await dark-matter confirmation'). And in October, a NASA satellite known as the Fermi Gamma-ray Space Telescope saw a haze of high-energy light in the centre of our Galaxy that could also be a dark-matter signature (see 'Bright light hints at a dark centre to the Galaxy'). An Italian experiment known as DAMA has claimed to see dark matter before, but many physicists are sceptical of the group's findings (see 'Dark-matter test faces obstacles'). The new results are consistent with the observations from PAMELA and Fermi but make the DAMA results less likely to be valid.


The CDMSII result will now spur physicists at the LHC to verify the sighting. "The LHC would see this very easily and relatively quickly," Ellis says, adding that the collider could potentially generate a detectable WIMP signal by the end of next year. Confirmation of WIMPs at the energies suggested by CDMSII would also provide support to supersymmetry, a popular theory that would simultaneously explain dark matter and unify several fundamental forces.

But scientists may not have to wait even that long to learn whether CDMSII is right. Experiments such as Zeplin-III are now taking data and might shore up the CDMSII observation within a matter of months. "A possible confirmation could happen very quickly," Sumner says.

[Woozie]

Wow, physics is about to get really awesome(er) if dark matter is confirmed.

[Woozie]

Despite being shrouded by lead bricks and located three-quarters of a kilometre underground in the disused Soudan Mine

Yeah, it is the same mine as the neutrino detector.

Edit: Also, I've read about those proton decay experiments before, but I don't understand them. If protons decay, their half life is 10^42 years (or at the very least about 10^33 years). It seems like you'd need a ridiculous amount of protons or a ridiculous amount of time in order to observe a decay.

[Mizango]

Wow, physics is about to get really awesome(er) if dark matter is confirmed.

No doubt.

[Eliseos]

Edit: Also, I've read about those proton decay experiments before, but I don't understand them. If protons decay, their half life is 10^42 years (or at the very least about 10^33 years). It seems like you'd need a ridiculous amount of protons or a ridiculous amount of time in order to observe a decay.

Yeah, that's why they are using so much water, since half-life is only an average, they should eventually see a proton decay (or see evidence that one did).

[Chun Liroy]

I don't quite understand dark matter. If it indeed reacts with normal matter with explosive results, wouldn't we see explosions all along the dark matter-normal matter border a lot? Or am I thinking of anti-matter? (If they are even different)

[Eliseos]

That's anti-matter you're thinking about. Dark Matter, according to theory, doesn't interact with regular matter at all (save particles like GIMPs etc).

EDIT: And it also interacts with gravity, which would explain the missing mass from the universe of just normal matter.

[Mizango]

Yes that's anti-matter you're thinking of.

[Kryssan]

Antimatter being its own interesting discussion.






However, as I promised, here you go:


Reflections on Russian Accident on August 17th, 2009


Sorry for the black and white and the graininess, but it was the best I could do. There are some pictures from the security cameras, including one where you see the turbine lifting up in the air. I wish I could show you the video of it happening though. There are no words to describe it.

[Eliseos]

Oh wow, those pictures are incredible. Wish the video of the accident was available, I can't even imagine what that looked like.

[Max™]

http://www.newscientist.com/article/dn15115

• 18:55 03 November 2008 by Anil Ananthaswamy

While engineers at the Large Hadron Collider (LHC) race to fix its teething problems and start looking for new particles, its ageing predecessor is refusing go silently into the night.
Last week, physicists announced that the Tevatron particle accelerator at Fermilab in Batavia, Illinois, has produced particles that they are unable to explain. Could it be a sign of new physics?
The Collider Detector at Fermilab (CDF) monitors the particles that spew from collisions between protons and anti-protons, which are accelerated and smashed head-on by the Tevatron. The collision occurs inside the 1.5-centimetre-wide "beam pipe" that confines the protons and anti-protons, and the particles created are tracked by surrounding layers of electronics.
In this instance, the CDF was looking at bottom quarks and bottom anti-quarks that decay into, among other things, at least two charged particles called muons.




The team was in for a big surprise. First, they saw far more muons coming from the collisions than expected. But crucially, some of these muons seemed to have been created outside of the beam pipe: they had left no trace in the innermost layer of the detector.
The CDF team says it is unable to explain such muons using the standard model of particle physics, or from what they know of their detector.
Unknown particle

However, "we haven't ruled out a mundane explanation for this, and I want to make that very clear", says CDF spokesperson Jacobo Konigsberg, who adds that it is important that other experiments verify the effect.
While the CDF team is circumspect, theoreticians are more willing to speculate. If the signal is not spurious, this means that some unknown particle with a lifetime of about 20 picoseconds was produced in the collision, travelled about 1 centimetre, through the side of the beam pipe, and then decayed into muons.
"A centimetre is a long way for most kinds of particles to make it before decaying," says Dan Hooper of Fermilab. "It's too early to say much about this. That being said, if it turns out that a new 'long-lived' particle exists, it would be a very big deal."
Dark matter?

Neal Weiner of New York University agrees. "If this is right, it is just incredibly exciting," he says. "It would be an indication of physics perhaps even more interesting than we have been guessing beforehand."
So what could it be? As it happens, Weiner and Nima Arkani-Hamed of the Institute for Advanced Study in Princeton, New Jersey, and colleagues have developed a theory of dark matter - the enigmatic stuff thought to make up a large proportion of the universe - to explain recent observations of radiation and anti-particles from the Milky Way.
Their model posits dark matter particles that interact among themselves by exchanging "force-carrying" particles with a mass of about 1 gigaelectronvolts.
The CDF muons appear to have come from the decay of a particle with a mass of about 1 GeV. So could they be a signature of dark matter? "We are trying to figure that out," says Weiner. "But I would be excited by the CDF data regardless."

Posted this last year, after I predicted (Sept 08 actually) they would find a 1.25~ GeV stable tetraquark configuration and dark matter candidate that behaved bosonically, electrically neutral, spin 0, etc, etc, etc.

Waiting for the LHC to find more.

[Mizango]

Antimatter being its own interesting discussion.






However, as I promised, here you go:


Reflections on Russian Accident on August 17th, 2009


Sorry for the black and white and the graininess, but it was the best I could do. There are some pictures from the security cameras, including one where you see the turbine lifting up in the air. I wish I could show you the video of it happening though. There are no words to describe it.

Awesome, thank you! Sorry for the late reply, was out of town this past weekend. Much appreciated sir.

[Lhyet]

Peaches Geldof on the Large Hadron Collider:
"They've made this thing like... called the Large Hadron Collider that's like... in Texas or something... where they're trying to create a black hole in space..."

Peaches Geldof on her interests in Quantum Mechanics:
"Well... I've always been interested in Quantum Physics... about theories of, you know, how we came to be and why... like... um... which is I guess like how I got into spirituality and stuff and that way the religious path I choose."

She then goes on to claim she's a Scientologist.

Who wants to beat her over the head first?

[Woozie]

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