Observation of the 'head-tail' effect in nuclear recoils of low-energy neutrons

Understand

Directional detection of dark matter can provide unambiguous observation of dark matter interactions even in the presence of background.

• This article presents an experimental method to measure the direction tag ("head-tail") of the dark matter wind by detecting the scintillation light created by the elastic nuclear recoils in the scattering of dark matter particles with the detector material.
• The technique is demonstrated by tagging the direction of the nuclear recoils created in the scattering of low-energy neutrons with CF4 in a low-pressure time-projection chamber that is developed by the DMTPC collaboration.
• The measurement of the decreasing ionization rate along the recoil trajectory provides the direction tag of the incoming neutrons, and proves that the "head-tail" effect can be observed.