Karlik and Bernert were unsuccessful in reproducing his experiments, and subsequently attributed Minder's results to contamination of his radon stream (radon-222 is the parent isotope of polonium-218). Berta Karlik et Traude Bernert ne parviennent pas à reproduire son expérience et attribuent ses résultats à une contamination du flux de radon (le radon 222 est l'isotope parent du polonium 218).
