Antiparticle-to-particle ratio for both investigated hypernuclei. The uncertainties are given by the quadratic sum of the statistical uncertainties and the systematic uncertainty on the absorption of the (anti)hypernuclei decay products (4.3% for the $^{4}_{\overline{\Lambda}}\overline{\rm He}$ / $^{4}_{\Lambda}{\rm He}$ , 4.5% for the $^{4}_{\overline{\Lambda}}\overline{\rm H}$ / $^{4}_{\Lambda}{\rm H}$ ) and the absorption of the (anti)hypernuclei themselves (5.5% for the $^{4}_{\overline{\Lambda}}\overline{\rm He}$ / $^{4}_{\Lambda}{\rm He}$, 6.3% for the $^{4}_{\overline{\Lambda}}\overline{\rm H}$ / $^{4}_{\Lambda}{\rm H}$).