Thursday, March 22, 2007

140)The "Axion", a possible particle of dark matter, which makes up 25% of our known universe.

In post 116 I linked to 3 articles but links to the 2nd and 3rd articles do not work so I am posting the entire 2nd article relating to a possible new particle discovery that constitutes the invisible dark matter which makes up about 25% of our known universe:

Fundamental physics

Axion stations

Dec 19th 2006
From The Economist print edition

A possible particle of dark matter

WHEN Frank Wilczek, a Nobel laureate, proposed the existence of a new type of elementary particle in 1977 he named it an “axion”, after a type of detergent, because it cleaned up a profound physical problem.

This problem is that the amount of visible stuff in the universe is far smaller than is needed to account for the apparent effects of gravity. In particular, galaxies behave as though they are much heavier than they actually look.

One way of solving this conundrum is to invoke a type of matter that has a gravitational field, but cannot interact with light or other forms of electromagnetic radiation, and is therefore invisible. In other words, dark matter. Axions are the most popular proposal for what this dark matter might actually be.

Unfortunately, they have since created a mess of their own. Many experiments have looked for axions. Most have not found them. Indeed, they have proved so hard to detect that many physicists question whether they exist.

Earlier this year, though, an Italian experiment did see something that suggested their existence. Now a paper by Piyare Jain and Gurmukh Singh of the State University of New York, Buffalo, also offers some evidence that axions really do exist. It is published in the January edition of the Journal of Physics G: Nuclear and Particle Physics.

The pair had another look at some photographic plates from an experiment conducted a decade ago at CERN, the European particle physics laboratory near Geneva. Though that experiment had not been intended to make axions, the two researchers wondered if it had created such particles as a by-product. After re-analysing the plates, Dr Jain and Dr Singh concluded that they may have found axions that exist so fleetingly that they are not noticed by the modern electronic methods of particle detection that have replaced the use of photographic plates.

If their interpretation is correct, that would be exciting, as it would establish the existence of a new class of matter. Unfortunately, it would not solve the dark-matter problem, since what the two researchers think they have found would be too short-lived to form the “missing” matter. But other particles in the class might plug the gap. An experiment under way at DESY, a laboratory in Hamburg, Germany, is seeking to make and detect axions that would fall into this longer-lived category. Should it succeed, scientists will have come closer to cleaning up the mystery.


Islam, eminently logical, placing the greatest emphasis on knowledge, purports to understand God's creation:Aga Khan 4.
The God of the Quran is the One whose Ayats(Signs) are the Universe in which we live, move and have our being:Aga Khan 3