Pontecorvo reactions in antiproton annihilation at rest in deuterium to<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi>n</mml:mi><mml:mo>,</mml:mo></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mrow><mml:msup><mml:mrow><mml:mi>Δ</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>η</mml:mi><mml:mi>n</mml:mi></mml:math>, and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>η</mml:mi><mml:mrow><mml:msup><mml:mrow><mml:mi>Δ</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>

Using modularized NaI(Tl) detectors, we carried out a high statistics measurement of inclusive \ensuremath{\gamma}-ray, ${\ensuremath{\pi}}^{0}$, and \ensuremath{\eta} spectra, and determined the branching ratios or upper limits of Pontecorvo reactions $\mathrm{p\ifmmode\bar\else\textasciimacron\fi{}}d\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}n$, ${\ensuremath{\pi}}^{0}{\ensuremath{\Delta}}^{0}$, $\ensuremath{\eta}n$, and $\ensuremath{\eta}{\ensuremath{\Delta}}^{0}$ from the corresponding monochromatic peaks in them. The obtained branching ratios are $B(\mathrm{p\ifmmode\bar\else\textasciimacron\fi{}}d\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}n)=(1.03\ifmmode\pm\else\textpm\fi{}0.41)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$, $B(\mathrm{p\ifmmode\bar\else\textasciimacron\fi{}}d\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\Delta}}^{0})=(4.67\ifmmode\pm\else\textpm\fi{}1.66)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$, $B(\mathrm{p\ifmmode\bar\else\textasciimacron\fi{}}d\ensuremath{\rightarrow}\ensuremath{\eta}n)&lt;8.94\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ (95% C.L.), and $B(\mathrm{p\ifmmode\bar\else\textasciimacron\fi{}}d\ensuremath{\rightarrow}\ensuremath{\eta}{\ensuremath{\Delta}}^{0})&lt;6.49\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ (95% C.L.).