The Cryogenic Dark Matter Search (CDMS) project is announcing on Friday 18th December, the possible detection of two dark matter particles. However, the chances of a false positive here are estimated to be 23%, which is rather high compared to the threshold of 5% typically employed in measurement science, and extremely high compared to the threshold of 0.1% stipulated by the CDMS team.The CDMS detector resides in an abandoned iron mine in Minnesota, (to minimise the background neutron radiation from cosmic rays), and consists of germanium discs cryogenically cooled to an extremely low temperature. The discs are coated with phonon sensors, designed to detect the tiny vibrations in such a crystalline solid. When the crystals are cooled to a very low temperature, the vibrational background of the solid is virtually eliminated, and it is possible to detect the phonons created by incoming particles colliding with the atoms in the solid.
These phonons, however, can be created by background gamma radiation colliding with the electrons in the solid, or by hypothetical dark matter particles colliding with the nuclei of the atoms. The two different processes create different patterns of ionisation, hence the detection of dark matter particles requires the simultaneous detection of the phonons and the ionisation in the crystals. (See Dark Side of the Universe, Iain Nicolson, p84-85).
6 comments:
Is not this the same type of experiment that has been going on at Boulby Mine in the North East for a few years, I think run by Sheffield Uni (gowd bless em)?
Anyways who cares, as long as it gets us closer to unlimited cheap clean energy it sound like a winner to me.
It is the same type of experiment! I'm well impressed Sean.
Its amazing what a few days on the wagon can do :0)
So how come its not the plucky Brits measuring up for the tux for Stockholm? luck or is it to do with the depth of the mine?
assuming of course....
I don't know, but it could be some combination of lack of finance and lack of expertise, the latter of which is ultimately attributable to a lack of investment in nuclear research.
You would have thought the German experience of installing 70k windmills and not one traditional power station being closed might tell the politicos something?
But then again when we are closing/mothballing steel mills in the north east so Tata can claim 600 Million in carbon credits and move production to India you know you are in the deep shit.
Maybe if we link Politicos pay,perks and pensions to wind power production they might think more carefully about the problem?
Correction, that should be 60 million.
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