Saturday, November 17, 2007

Needles in haystacks are easy to find

Do you know what attracted me to particle physics in the first place? It was the challenge of detection. How to you design experiments to see those unbelievably small things? How do you make sense of the signals or images from a detector? How can you be sure that you see what you think you see, that it was not something else that you had not thought about?

That's what I'm interested in, and as you might imagine it's often not a simple task. The analysis of data from an experiment can take years.

I found this explanation of the ATLAS "spam filter" nice. (ATLAS is one of the experiments at the Large Hadron Collider (LHC) which will be turned on next year.) Here about 40 million reactions will occur per second (40 million events in the detector!) and of these only 200 will be stored for analysis. We know most of the physics already, and the people working with this are not interested in looking at a lot of the well-known old stuff. Already this trigger system is impressive!

I hope the world will turn out to be arranged in a way that is not too difficult to make sense of from the data we will get soon. Perhaps we will learn what the dark matter really is. As you might know, the most popular candidate for the dark matter particle is the lightest neutralino, a particle that arises from supersymmetric theory. Supersymmetry is one of the first things to look for at LHC, and if this is a correct description of the world it will probably be discovered soon.

And if not, we might still get clues to what the dark matter particles can be.