Direct Detection of Dark Matter
Natallia Karpenka
Experimental Techniques in Particle Astrophysics
October 27, 2010
Outline
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Question 1
Explain the how a WIMP interact can result in energy deposition in matter, e.g. ionisation, nuclear recoil. Use the Xenon ”two-phase TPC” to
illustrate this.
The XENON two-phase TPC
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Question 2
Discuss the structure of the CDMS experiment
(slide 21) with a focus on the shielding strategies.
Cryogenic detectors
Different layers of shielding around the icebox
Polyethylene shield
Polyethylene shield
Fast neutrons can be shielded in the most effective way by hydrogen. Fast neutrons are slowed down by collisions with hydrogen nuclei.
Thermal neutrons can be efficiently shielded using some additional elements in the shielding material e.g. boron, lithium, or cadmium.
The secondary gamma radiation comes from thermal neutron absorption in
hydrogen. This radiation can be minimized by using a shield containing
elements like boron or lithium.
Lead shield
Lead shield
α
γ
x-rays
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Question 3
How does a bubble chamber work? How can one
distinguish neutron and WIMP interactions?
How does a bubble chamber work?
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