Direct decay-energy measurement as a route to the neutrino mass

A high-precision measurement of the $^{131}$Cs$
ightarrow ^{131}$Xe ground-to-ground-state electron-capture $Q_{ extrm{EC}}$-value was performed using the ISOLTRAP mass spectrometer at ISOLDE/CERN. The novel PI-ICR technique allowed to reach a relative mass precision $delta m/m$ of $1.4cdot10^{-9}$. A mass resolving power $m/Delta m$ exceeding $1cdot10^7$ was obtained in only $1,$s trapping time. Allowed electron-capture transitions with sub-keV or lower decay energies are of high interest for the direct determination of the $
u_e$ mass. The new measurement improves the uncertainty on the ground-to-ground-state $Q_{ extrm{EC}}$-value by a factor 25 precluding the $^{131}$Cs$
ightarrow ^{131}$Xe pair as a feasible candidate for the direct determination of the $
u_e$ mass.

Karthein, J., Atanasov, D., Blaum, K., Eliseev, S., Filianin, P., Lunney, D., ... Zuber, K.

Karthein, Jonas||Atanasov, Dinko||Blaum, Klaus||Eliseev, Sergey||Filianin, Pavel||Lunney, David||Manea, Vladimir||Mougeot, Maxime||Neidherr, Dennis||Novikov, Yuri||Schweikhard, Lutz||Welker, Andree||Wienholtz, Frank||Zuber, Kai

Direct decay-energy measurement as a route to the neutrino mass Institutional Repository Document