R. E. Mischke

Improved Measurement of the π→eν Branching Ratio

A new measurement of the branching ratio,

Search for massive neutrinos in π+→e+νe decay

R_{e/\mu} =\Gamma (\pi^+ \rightarrow \mbox{e}^+ \nu + \pi^+ \rightarrow \mbox{e}^+ \nu \gamma)/ \Gamma (\pi^+ \rightarrow \mu^+ \nu + \pi^+ \rightarrow \mu^+ \nu \gamma)

Improved measurement of the

, resulted in

\pi \rightarrow \mbox{e} \nu

R_{e/\mu}^{exp} = (1.2344 \pm 0.0023 (stat) \pm 0.0019 (syst)) \times 10^{-4}

branching ratio

. This is in agreement with the standard model prediction and improves the test of electron-muon universality to the level of 0.1 %.

Search for massive neutrinos in π + → e + ν e

The PIENU experiment aims to measure the branching ratio of the charged pion decay with precision of < 0.1 %. This measurement is much sensitive to search for massive neutrinos coupled to electrons in \({\pi }^{+}{\rightarrow }e^{+}{\nu }_{e}\) decay. The initial analysis was completed and the upper limit on the neutrino mixing parameter |Uei|2 in the neutrino mass range of 0 to 55 MeV/c2 was improved by a factor of 1.5, and the sensitivity for the mass range of 68 to 129 MeV/c2 was improve by a factor of up to 4.

{\pi }^{+}{\rightarrow }e^{+}{\nu }_{e}

A new measurement of the branching ratio,

decay

R_{e/\mu} =\Gamma (\pi^+ \rightarrow \mbox{e}^+ \nu + \pi^+ \rightarrow \mbox{e}^+ \nu \gamma)/ \Gamma (\pi^+ \rightarrow \mu^+ \nu + \pi^+ \rightarrow \mu^+ \nu \gamma)

Status of the PIENU experiment at TRIUMF

, resulted in

Improved search for heavy neutrinos in the decay π→eν

R_{e/\mu}^{exp} = (1.2344 \pm 0.0023 (stat) \pm 0.0019 (syst)) \times 10^{-4}