Preliminary Proton/Electron Mass Ratio using a Compensated Quadring Penning Trap

A new type of compensated Penning trap with the ring electrode split into equal quadrants allows intense unshifted ion cyclotron resonances to be synchronously detected with very small relative linewidths (< 2×${10}^{-9\mathrm{}}$). By measuring the cyclotron frequencies of both protons and electrons in the same magnetic field (5 T) and the same trapping volume (<${10}^{-7\mathrm{}}$ ${\mathrm{cm}}^3$), a preliminary value of the mass ratio $\frac{m_p}{m_e}=1836.153\mathrm{}00\left(25\right)\mathrm{}$ is obtained with an accuracy that is more than four times greater than any previous direct measurement.