Detecting Dark Matter: How Scientists Differentiate Between WIMPs and Neutrinos

[kashiark]

According to an article that I read, an article came out today announcing that scientists had detected dark matter or at least a WIMP. How did they detect these particles? Did they do it the same way they detect neutrinos? If so, how do they know what they detected wasn't a neutrino?

 

[sylas]

According to an article that I read, an article came out today announcing that scientists had detected dark matter or at least a WIMP. How did they detect these particles? Did they do it the same way they detect neutrinos? If so, how do they know what they detected wasn't a neutrino?

I checked this out... Apparently there has been a rumour going around that a dark matter particle was detected by the http://cdms.berkeley.edu/; but there are also denials of the rumour. See The dark-matter rumour mill at physicsworld.com, which presents the skeptical view.

As for how it is detected; the CDMS page has some background that may help.

Cheers -- sylas

 

[nicksauce]

As far as I know, there was a rumor, which was denied, that they detected dark matter and will announce on December 18th. So I am going to hold off speculation until then...

 

[humanino]

You may start a poll to guess whether the results will be positive...

 

[Vanadium 50]

If you don't say what article you read, it will be difficult to discuss it in any detail.

 

[hamster143]

The December 18th announcement date is inaccurate. Two talks at Fermilab and SLAC are scheduled for December 17th (2 P.M. Pacific / 4 P.M. Central) and the manuscript is expected to appear on arXiv earlier than that.

 

[kashiark]

I read that they were supposed to publish an article about it on the 12th in nature, so I googled it yesterday, and I found an article that said they had actually discovered it; however, I can't find it now... I'm not sure if I read it incorrectly or if it was just B.S. Either way, sorry for the incorrect information.

 

[bcrowell]

Here is a blog with a link to a 2-page statement by the Minnesota group: http://physicsworld.com/blog/

Here is a UMN university news article: http://www1.umn.edu/news/features/2009/UR_CONTENT_164628.html

They saw two particles, with an expected background of 0.5 particles. They don't claim to have detected WIMPs, but they do claim to have improved the constraints on masses and strength of interaction. They plan to improve the setup by adding more detectors in order to increase efficiency.

 

[eep]

Basically, the two events aren't statistically significant enough to claim a WIMP signal with the expected background, but they can't be ruled out either. All that they can really say is that there's a 23% chance the two events were due to background. So perhaps it is the beginning of a signal. They linked to the archive paper and gave a statement on their site at cdms.berkeley.edu

 

[Vanadium 50]

The intent of the experimenters was to make a "box" with an expected background of 0.5 particles, study everything they could without opening the box, and when satisfied that everything was understood, open it and see how many events they had. As you know, they saw 2.

However, after all this study, they managed to conclude that the expected number of background events in the box was a shade above 0.8. That's why the 2 events is much less convincing than you might think at first.

 

[Haelfix]

It was a little dissappointing. One of the hits is very shady, and outside of their band.

Most of us were hoping for 3 or 4 hits.

 

[eep]

Both hits are inside their bands...