So let’s say : we have an environment obviously contaminated with some Rn222 and Rn220. They decay with alpha emissions, and in the daughter products some also emit beta minus particles.
The alpha nucleii and beta minus particles destroy the experiment. They create a link, even if very weak, which is enough because of the ultra high stability of the environment thanks to the very cold temperatures. The high energy of the many alpha decays contributes, simply kinetically, especially strongly to the compaction of the atoms and formation of “condensats”. It’s also the simple explanation for the superfluidity of helium.
I wonder if Einstein really predicted this or, more simply, did the experiment and could not see why and elaborated the theory without the proof.
UPDATE (June 1st) : the above explanation is also demonstrated through another way : with magnons, condensats in an iron-yttrium-garnet thin film happen at room temperature (S. O. Demokritov; V. E. Demidov; O. Dzyapko; G. A. Melkov; A. A. Serga; B. Hillebrands & A. N. Slavin (2006). “Bose–Einstein condensation of quasi-equilibrium magnons at room temperature under pumping”. Nature. 443 (7110): 430–433.)
Of course : in a ferromagnetic environment the electronic link between alpha particles and beta minus particles works much better.