kinematics $E_{lab}=80$ MeV, $\theta=16^\circ$ the uncertainty of the quasielastic contribution is reduced by a factor of 15 and the theory uncertainty starts being dominated by that due to the subtraction constant (estimated to be 40 $\mu$eV). It can be seen that already the next MAMI A1 runs at the lowest energy of 180 MeV and the most forward angle of 16$^\circ$ with a 2% precision have the potential to reduce the uncertainty of our dispersion calculation by at least factor of 4. The sensitivity to the value of the parameter $a_1$ is further enhanced at a lower energy as can be seen in the lower panel of Fig. \[sensitivity\]. Future measurements will allow to test other theoretical frameworks, such as potential models and EFT, as well.

   $E_{lab},\,\theta_{lab}$   Exp. precision   $\begin{array}{c} \delta(\Delta E_{2S-2P}^{\mu D}) \\ {\rm in}\;\mu {\rm eV} \end{array}$   $\begin{array}{c} \delta(\Delta E_{1S-2S}^{e D}) \\ {\rm in\;kHz} \end{array}$
  -------------------------- ---------------- ------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------
     180 MeV, 30$^\circ$            2%                                                    740                                                                                    12
                                    1%                                                    370                                                                                    6
     180 MeV, 22$^\circ$            2%                                                    390                                                                                   6.32
                                    1%                                                    195                                                                                   3.16
     180 MeV, 16$^\circ$            2%                                                    211                                                                                   3.36
                                    1%                                                    110                                                                                   1.68
      80 MeV, 16$^\circ$            2%                                                    67                                                                                    1.08
                                    1%                                                    48                                                                                    0.78

  : Impact of future measurements of the deuteron electrodesintegration at MAMI A1 and 