Particle Physics Masterclass 2012

The final lecture of the day was on dark matter. Unfortunately I don’t have many pictures from this as my camera needed recharging. The lecturer was Dr Pawel Majewski. For further information click here: http://en.wikipedia.org/wiki/Dark_matter

Dark matter is mass that cannot be seen that seems to affect matter.

Gravitational lensing  involve gravitational fields bending the trajectory of photons. Gravitational lensing by clusters of galaxies allows us to observe distant objects. It causes their images to be distorted.

A bullet cluster consists of two galaxies colliding. For more information click here: http://en.wikipedia.org/wiki/Bullet_Cluster

Gravitational lensing has been used to map dark matter using the Hubble telescope.

The universe is made up of 74% dark energy, 22% dark matter, 3.6% intergalactic gas and 0.4% stars etc.

Dr Majewski went on to explain how to build a dark matter detector. The detector must have low energy loss and be able to search for rare events without triggers. It is hard to combine both. The detector needs to be shielded against cosmic radiation (usually by locating it deep underground). It needs to be shielded against external gamma and neutron radiation.

Dark matter direct matter detection techniques include heat and ionisation, bolometers, CDMS and Edelweiss.

One such detector is found down Boulby mine near Whitby. Its depth is 1100m.

http://www.hep.shef.ac.uk/research/dm/boulby/boulby.php

Dr Majewski continued by describing the Zeplin project. More information can be found here: http://hep45.hep.colostate.edu/~wilson/DUSEL/TopicalWorkshops/Physics-WorkshopNov05/Presentations/Session2b/Wang_Xenon-Extrapolation.pdf

It has the capability of detecting a single electron.

Dark matter interacts with gravity and there is an assumption it interacts like neutrons. Missing energy techniques could find it.

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