Measurement of the Beta-Neutrino Correlation of Sodium-21 using Shakeoff Electrons

Understand

The beta-neutrino correlation coefficient, $a_{\beta\nu}$, is measured in sodium-21 by detecting the time-of-flight of the recoil nucleus detected in coincidence with the atomic electrons shaken off in beta decay.

• The sample of sodium-21 is confined in a magneto-optic trap.
• High detection efficiency allows low trap density, which suppresses the photoassociation of molecular sodium, which can cause a large systematic error.
• Suppressing the fraction of trapped atoms in the excited state using a dark trap also reduces the photoassociation process, and data taken with this technique are consistent.