5 replies to this topic

[Still Waters]

In a man-made cavern, deep beneath a mountain, scientists are hoping to shed light on one of the most mysterious substances in our Universe - dark matter.

The Gran Sasso National Laboratory seems more like a Bond villain's lair than a hub for world class physics.

It's buried under the highest peak of Italy's Gran Sasso mountain range; the entrance concealed behind a colossal steel door found halfway along a tunnel that cuts through the mountain.

http://www.bbc.co.uk...onment-21340274

[DieChecker]

I wonder how they intend to detect the WIMPS? Change in energy? Won't it appear as energy showing up out of nowhere?

Interesting. Will look forward to more articles.

[sepulchrave]

DieChecker, on 06 February 2013 - 09:02 PM, said:

I wonder how they intend to detect the WIMPS? Change in energy? Won't it appear as energy showing up out of nowhere?

I think so. They will detect a sudden emission of light and possibly some electron scatter.

They will then have to deduce the direction and energy of the particle that caused this disturbance, and see if it matches any understood sources (solar neutrinos, trace radioactivity, etc.) to see if it can be explained.

IF not, and IF a statistically significant collection of very similar and unexplainable events are detected, then they can attribute it to a new source.

[DieChecker]

sepulchrave, on 06 February 2013 - 09:22 PM, said:

I think so. They will detect a sudden emission of light and possibly some electron scatter.

They will then have to deduce the direction and energy of the particle that caused this disturbance, and see if it matches any understood sources (solar neutrinos, trace radioactivity, etc.) to see if it can be explained.

IF not, and IF a statistically significant collection of very similar and unexplainable events are detected, then they can attribute it to a new source.

Do you think that they have any kind of expected odds? Like one strike on average per day, or something like that? Unless they have some kind of expectation, how can they eliminate stuff like neutrinos?

[sepulchrave]

DieChecker, on 06 February 2013 - 11:53 PM, said:

Do you think that they have any kind of expected odds? Like one strike on average per day, or something like that? Unless they have some kind of expectation, how can they eliminate stuff like neutrinos?

I imagine they have an expectation of the odds, but I also am sure the odds are extremely slim... perhaps one strike per month.

I think the dark matter will be detected by deducing the momentum and energy of the collisions, and using those to estimate the rest mass and velocity of the mystery particle.

Solar neutrinos are always travelling extremely fast, but have extremely small masses. WIMPs, on the other hand, are probably travelling relatively slowly but should have significant masses.

Free neutrons (perhaps from random radioactivity) might also be slow, and definitely have a significant mass, but they have a well-known life-time and decay channel (a free neutron will decay into an electron and a proton in about 15 minutes), and the effects of trace amounts of radioactivity should not be dependent on the time of day or the time of the year.

I think neutrino detection depends slightly on which side of the Earth is facing the Sun (not sure about that, though), and in the OP's article the scientists mentioned they expect a seasonal variation in dark matter detection (since, presumably, there is a galactic current of dark matter flowing through the Solar system, and as the Earth orbits the Sun our alignment with this current will change with the seasons).

[DieChecker]

sepulchrave, on 07 February 2013 - 12:11 AM, said:

and in the OP's article the scientists mentioned they expect a seasonal variation in dark matter detection (since, presumably, there is a galactic current of dark matter flowing through the Solar system, and as the Earth orbits the Sun our alignment with this current will change with the seasons).

Cool!!