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Signs of Dark Matter From Minnesota Mine
thomst writes "Juan Collar, team leader of COGENT, an experimental effort to detect WIMPs (Weakly Interacting Massive Particles), recently presented a paper detailing 15 months of data collected via a pure germanium detector located deep in a Minnesota mine which seems to confirm similar results reported by a European effort called DAMA/LIBRA. The results are particularly intriguing, because they appear to show a seasonal variation in the density of WIMPs that accords with models which predict Earth should encounter more WIMPs in Summer (when its path around the Sun moves in the same direction as the Milky Way revolves) than in Winter (when it goes the opposite direction). The most interesting thing about the COGENT experiment is that the mass of the WIMP candidates it records is significantly less than most particle physicists had predicted, according to popular models. (Ron Cowen wrote an earlier article about COGENT last year that goes into a lot more detail about how COGENT works, what its team expects it to find, and why.)"
some of us live in the southern hemisphere, you insensitive clods!
"If still these truths be held to be
Self evident."
-Edna St. Vincent Millay
Nice to see that we are still supporting science for the sake of science, not just science that turns into profits for some private corporation.
Ummm -- Minnesota is not a COAL mining mecca; the Sudan mine is located in what is known as the Iron Range.
Why are the nerds trying to detect the wimps?
toughen up or move north.
Hence the old WCCO running joke of "The Iron Ranger", with his trusty horse Taconite... I miss those days. :)
And the experiment should be duplicated there.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
My geraniums are just blooming too.
Science keeps amazing me!
It is being duplicated there: DM-Ice
The mine is iron ore.
Pretty good iron ore actually. 60%+ iron. Stuff that a magnet will stick to.
But it was too deep to mine economically.
You can tour the mine if you want, it's in Tower/Soudan, up by Ely and close to the Boundary Waters Canoe Area (a few hours drive from Duluth, MN). There's a mine tour and a physics lab tour.
i would be angry at the sleight as well, except for the fact that, as an antipodean, you would instead feel pleasure at being overlooked
and my apologies for not writing this upside down and backwards and inside out in meaning, as is antipodean custom
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
http://en.wikipedia.org/wiki/Milky_Way
"The Sun orbits around the center of the galaxy in a galactic year—once every 225-250 million Earth years."
has there ever been any research into odd or bad events in our geological record that occur with 237 million year frequency?
because right now, at this moment, we are plowing through space we haven't plowed through in 237 million years. what the hell are we hitting? everything from asteroids to comets to various kinds of background radiation to fundamental particles could potentially vary periodically, according to this 237 million year loop
yes, i take solace that most stuff around us is orbiting right along with us
but not all of it
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
Signs of Dark Matter From Minnesota Mine
Coal?
Instead, why not have the summary give the *month* when Earth's path around the Sun moves in the same/opposite direction as the Milky Way revolves?
For those of you that live in the southern hemisphere and don't have such seasons, winter is when it is cold. In Minnesota it can cool down to below 240K
(Yes I am aware that Antarctica has winter, but nobody lives there apart from penguins)
The lab is located in a lower (the lowest?) level of the Soudan Mine. This mine is also a state park and you can tour the mine.
The tour (when I took it, about 9 years ago) took you down to the same level as the lab, which I think is the lowest level of the mine or within a level or two of the lowest level.
You ride a mine cart to a room where extraction of iron ore took place, hear some details about early mining, including a lights-out experience where they show you what it was like with nothing more than old-fashioned arc lamps on the miner's helmets.
Before you leave this level, you get to go into the lab area and get a look around. I don't think you go much past the entry way, but it's neat anyway.
The mine had a fire recently and I don't know if the tours are back in operation, but I believe they have every intention of continuing with them once they fix whatever happened.
If the experiment is based in the Northern Hemisphere the reference can be assumed to be spring or Summer in the Northern Hemisphere.
Giant Interacting Massive P ..... er, nevermind.
Dark matter is more of a medium charcoal color.
some of us live in the southern hemisphere, you insensitive clods!
Yes, but statistically speaking, not very many of us do, and since Slashdot is a USA-based site, and even the summary mentions that the researchers were in the Northern hemisphere (Minnesota and Europe) it's pretty easy to figure out what they mean, even for someone who lives in a topsy-turvy land where up is down and presumably left is right and you have to wear magnetic boots to avoid falling off the Earth.
Typo -- you forgot the O -- Soudan.
The month appears to be irrelevant. The season is what is relevant. If the guy means to do a summer-time study in Minnesota to show that summer is when something happens, nobody is going to care what season it is in NSW. Lose the ego.
Someone flopped a steamer in the gene pool.
Whodathunk ?? This is 2011 already !!
How do you think we get stuff? Magic? Recycling yields less that 100%, so as the population grows, we need to get more stuff out of the ground.
Putting moderation advice in your
> Yes, but statistically speaking, not very many of us do, and since Slashdot is a USA-based site, and...
Yes, but statistically speaking, WHOOOOSH!
When I first saw the title of the thread, my initial reaction was "How the hell is there dark matter in Minnesota? Did they find Nibbler's litter box or something?"
I did my physics undergrad at the University of Minnesota Duluth, and they graciously let me play around in the mine on occasion. I don't do much particle physics anymore so I'm not particularily equipped to judge their results, but I can say that all kinds of seasonal errors can be introduced in these experiments. Cosmic rays have a seasonal variation for example. Another that happens at Soudan for sure and possibly in Italy is seasonal variation in background radiation. The air circulation at Soudan is largely passive, and there is lots of radon gas seeping from the rocks. In the cold winter the exchange is excellent, but in the summer the circulation is terrible and you get anywhere from 5 to 10 times the radon background in the cave (air in the cave is warmer than outside in the winter and cooler in the summer, you can do the math).
I'm not saying either of those are the cause of this, but there is good reason to squint hard at anything claiming "seasonal evidence" when the claim is extrordainary (in the sense that it is way off from any model). Scientists should be skeptical of this, especially since they are claiming a result before theory suggests a result should even be possible.
australia is known for arnold schwarzenegger, amadeus mozart, sigmund freud, franz ferdinand, the house of hapsburg, and "the sound of music"
please get a geography education
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
---
Dark Matter Feed @ Feed Distiller
Well, if it is a coal mine, wouldn't you expect it to be full of dark matter? ;)
I'm also glad to see that /. is working on the fortune generator. Too bad it blurts all fortunes in ROT-13. Hint for the curious:
< uglymess.txt tr '[A-Za-z]' '[N-ZA-Mn-za-m]' | sed 's/%/\n\n/g' > clean.txt
This post contains no rudeness or derision of any kind. All arguments are friendly. Terms and exclusions may apply.
my supposition is also absurd because the milky way itself is "moving" (orbitting?), in relation to other galaxies. there is no fixed point we are moving against
however, it is a slightly intriguing possibility, no? that say, some fundamental constant we take for granted as constant actually might vary slightly across a 250 million year period... for some reason. wouldn't that be interesting? yes, this is wild conjecture, but you could certainly sit around and construct a few "what ifs" that would suggest such a possibility. even though we aren't remotely able to ask serious science questions about such a hypothetical periodicity to... something, right now in our scientific maturity
at least the thought is the basis for some perhaps compelling speculative science fiction, if not real science
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
Actually 230K. But hey, what's another 10 degrees Kelvin when we're already at more than 40 below zero.
The month appears to be irrelevant. The season is what is relevant. If the guy means to do a summer-time study in Minnesota to show that summer is when something happens, nobody is going to care what season it is in NSW. Lose the ego.
Actually quite the opposite. It is based on where the planet is in its orbit, which is based on the month, not the notional season. Unless I entirely misunderstand TFS, if the experiment had been in NSW, it would've had to be held in winter.
Everyone knows the southern hemisphere orbits the sun in the opposite direction of the northern hemisphere. So, people in the southern hemisphere will still experience more dark matter in their summer.
...and the troll wins!
The experiment was not in NSW.
This is especially interesting to me because another experiment failed to detect any evidence of dark matter, which seemed to contradict the (not quite statistically significant) hints that CDMS may have detected dark matter last year.
I'm also confused about which experiment this is. It says it is in the Soudan mine in Minnesota, but it isn't mentioned on either of the websites for the mine. Is it part of MINOS or CDMS, or is it something separate?
Regardless, I have been really excited about these detectors for the last couple years (even more so than the LHC), and it is great to start seeing data.
Whoosh.
Looks like we've lost another one to magnetic boot failure.
The month appears to be irrelevant. The season is what is relevant. If the guy means to do a summer-time study in Minnesota to show that summer is when something happens, nobody is going to care what season it is in NSW. Lose the ego.
God, you're a fucking moron. I guess you probably represent most of the demographic on this site now. What arkenian wrote mirrors my sentiment, but he's much nicer about it and isn't 100% confident in his response (probably to be nice to you). Lose the ego.
really just becoming Emo Matter?
Southern hemisphere still has us beat.
It snowed CO2 at Scott Amundsen base once IIRC.
-nB
whois gawk date unzip strip find touch finger mount join nice man top fsck grep eject more yes exit umount sleep dump
Coldest I've seen living in Wisconsin is -62c/-80f/211k including wind-chill. Local news said exposed skin could develop frostbite in 10-15 seconds. WI is right next to MN, so similar temps, although MN tends to take the brunt of the weather that the Rockys sends our way.
http://wattsupwiththat.com/2009/06/13/results-lab-experiment-regarding-co2-snow-in-antarctica-at-113%C2%B0f-80-5%C2%B0c-not-possible/
I googled a bit.
-- perl -e'print pack"H*","6e656d6f406d38792e6f7267"'
"There are known knowns; there are things we know we know.
We also know there are known unknowns; that is to say we know there are some things we do not know.
But there are also unknown unknowns – the ones we don't know we don't know."
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
There's a huge controversy right now in the field. The DAMA/Libra experiment has been claiming an 8-sigma excess for years which they say is consistent with dark matter, but they keep getting excluded by other experiments, most notably CDMS and Xenon. Every time their favored region is excluded, they come up with a new way to reanalyze their data to make it consistent again. But they have not ever released any of their data to the community (and hold patents on the type of crystal they use for their detector) so it's impossible to directly verify.
CoGeNT first released hints of a low-energy excess which could be consistent with DAMA-type dark matter about a year ago. I was at the APS conference earlier this week where Collar released the seasonal modulation results which make it seem even more likely that they see the same thing as DAMA. However, just the next day, CDMS presented an analysis of their low energy data which is below their normal dark matter threshold (because the rate of background events in that region is quite high and poorly understood). They showed that, even if they didn't account for the known sources of background, the rate in their detector is inconsistent with CoGeNT's. As many people rightly point out, CoGeNT is seeing an exponential signal near threshold, which is what you'd expect to see in just about any detector with or without dark matter present.
The whole situation is muddled even further by politics and personalities. Collar is respected as a scientist, but is also generally agreed to be an asshole. When he announced the annular modulation result, he spent 25 minutes of his talk attacking xenon on mostly pointless grounds, then had only a single slide showing the important result of the modulation. He finds tiny holes in other's analyses, but doesn't often present a very convincing picture of his own.
tl;dr: The community is far from agreeing that what he and DAMA have seen are in fact WIMPs. CDMS and Xenon tend to have better established analysis programs and pay more attention to their systematics, and they still rule out both DAMA and CoGeNT. However, I think everyone at this point agrees they are seeing something interesting, just likely not WIMPs.
Is excreted by three eyed alien monkeys and is used to power space ships.
You can find out more about this in "Through the Wormhole with Morgan Freeman", this particular subject is in episode 8 (the last one)
Of course the matter is dark, it's at the bottom of a mine shaft!
there should be no "degrees" before "kelvin"
On April 27, I posted this comment on another story about an entirely different topic. Eventually, it got modded to +3 Insightful. Then, this morning, I discovered it had been modded all the way down to -1 Overrated.
There's only one reason why a single moderator would spend that many mod points on down-modding a single post: to put it below the browsing threshold of virtually all /. readers. The question is, "Why?" And I suspect the only credible answer to that question is, "Because he is so consumed by dedication either to communism or to libertarianism (the two political philosophies whose fundamental assumptions I criticized in the post), that he feels compelled to suppress any criticism of it for which he is unable to muster an argument in response.
Now, because communists are so thin on the ground around here, I have my strong suspicions which philosophy my censor espouses - but it doesn't matter either way, because, in either case, this is clearly a case of someone systematically attempting to suppress dissenting speech. The act of suppression itself is one of craven philosophical cowardice, and it does nothing whatsoever to enhance the credibility of the political philosophy it purports to defend. To the contrary, it merely establishes that the moderator, at least, can muster no useful counter-argument. Instead, he substitutes moderation abuse for intelligent discourse.
In the interest of fairness, I urge you to read my comment. Whether or not the down-mod is undone, it deserves at least that much consideration.
Check out my novel.
Hi Don Rumsfeld. How are you?
http://en.wikipedia.org/wiki/There_are_known_knowns
"If still these truths be held to be
Self evident."
-Edna St. Vincent Millay
Wind chill doesn't count when reporting temperatures. Stick to air temp and worry about the wind chill only if you're bothering to go outside.
They still mine, yes. But today most of it is data mining.
The Tao of math: The numbers you can count are not the real numbers.
Actually no. The low concentration of C02 in the atmosphere means that dry ice sublimates faster than it freezes at the temperatures that were recorded in Antarctica. So flakes of dry ice would never get a chance to form.
Yeah... well the joke doesn't really fit the reality of it being an iron mine.
This experiment is outside my field of expertise, but I know several people who worked on this experiment and have met Juan Collar several times. It seems like an excellent experiment, but there is a funny side to their results:- Juan Collar has been talking for a long time about how he has been very close to showing the DAMA claim of dark matter detection is incorrect, and now he has confirmed it. I often got the feeling that the COGENT team didn't really believe dark matter existed.
Simon's Rock College
Still have summer and winter don'tcha?
Wanna buy a shirt?
https://www.redbubble.com/people/stealthfinger/shop?asc=u
Nope. Iron.
I'm on to you! Real Americans(TM) on the radio warned me about your plot to confiscate all our Bibles and guns! Yer obviously onna them people whut believes Obama was barn in Amurka! [/silly]
Nope. Iron.
Well, it is still dark and it is still matter!
These particles have mass, right? (hence the "M" in the acronym)
So wouldn't they be rotating WITH the galaxy?
Doesn't that imply a higher collision rate when moving AGAINST the rotation of the Milky Way?
And what seasons do you have there.
Most of the populated area just has summer year around.
Or if you are at the south pole you have a full year of winter.
For the rest of us who live in the correct Hemisphere (North) we have areas with seasons. Where when we say winter we mean it. and not just a cool summer day.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
Dag Nabbit I had to wash the Boes-Eisenstein condensate off my car again.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
The reason dark matter has been the "missing mass" for so long is that Minnesotans have been hording it for ourselves. Sorry...
"Convictions are more dangerous enemies of truth than lies."
If this is as true as Juan Collar's talk's claiming to be the best, when there are others that have better limits. Such people will one day discover how pity they are. so sad
It doesn't say who's summer. There is a summer in the northern hemisphere, and a summer in the southern hemisphere, and we are all screwed if they both happen at once. The article doesn't say exactly where its published, although Europe is predominantly in the Northern Hemisphere, so that would mean that we Northerners (that includes you people in Georgia, Tennessee, Florida and Texas) are going with the celestial current, and those southern cross types (go ahead, call me an insensitive clod), are going against the intergalactic celestial current. You always though there was-- you know --something... and now you know.
I thought it was impossible for WIMPS to exist inside galaxies,because they would be streaming into stars due to gravitational attraction. Since WIMPS dont interact with the electromagnetic field effects of baryonic matter (thus weakly interacting) these WIMPS would exclusively be attracted by the gravity of stars, but not repulsed by the explosive effects of fusion reactions. This would lead to every star's equilibrium between inward acting gravity and outward acting fusion reaction being unbalanced, wiht the WMPS slowly increasing the mass of the star and hence the violence of fusion. Causing all stars to grow smaller and hotter until they nova'd. The only fix for this which has been suggested is to have all WIMPS safely quarantined in the outer galactic halo by their own angular momentum, thus they would never interact with anything on Earth.
Congrats on feeding the troll. Well done.
if the summer increases the threshold of observation, by way of moving with the galaxy, so then should we see more at night too, (when our hemisphere is moving the same direction too)
No?