They have looked only at the effects of collision on HD+; there are hardly any equations. They are not interested in quantum description of the whole process but only on what happened with the HD+ from which they read about used slit(s). But please respond, does the hellium go through the slits as a wave or as a particle? The Copenhagen interpretation discretizes experiments: during one, it must be either the former or the latter. If it is a particle, then it has a position or momentum during measurement (subject to uncertainty; they "arise" upon measurement, according to orthodox Copenhagen, and arise randomly). Then, there are also things such as momentum transfer etc. which are usual for particles. If it is a wave, however, then it can interfere, and also it can be in many places at a time during measurement. But in this experiment both momentum transfer and wave effects happen during one process of leaving a slit. So please admit that the experiment shows something that is against the orthodox Copenhagen interpretation. Already for this reason it is worth mentioning here(!), but there is one more point.
If you take the Bohm's interpretation (which spreads properties such as charge or mass in space, if the article is not mistaken) and then apply the guiding equation not to one selected point, but to all continuum of points within the orbital, then you can easily explain how can something that acts as a particle go through both slits at a time. The interference pattern will arise due to similar effects as in Huygens' principle; momentum transfers from points (integrated, of course, because normally they will have only something like density of mass and thus density of momentum) will also follow normally. This looks like a quite natural explanation of the phenomenon, especially that photons most likely encounter the same thing when they bounce from shutters between the slits, etc. A very natural explanation is, then, that the apparent "particle", subject to all QED equations etc., acts proportionally "with its whole body" (can be normalized to 99% like with orbitals, so that the body does not extend infinitely in space). Every point follows its own way, when confronted with potentials of external fields, for instance (as in QED), though they have a common wavefunction and this makes them one and the same "particle."
But this emergent interpretation, so natural and obvious, will never be compatible with the Copenhagen interpretation and the like, which assign certain probabilities to different outcomes of a measurement. This is why CI needs the distinction "acts as a wave"  "acts as a particle" in experiment; in case of a particle you will have 1 position or momentum, subject to Heisenberg's, and in case of a wave you don't take these into account, so no problem! But never, in CI, you have a continuum of measurements for a certain wave function; because, then, without any collapse in between, ALL POSSIBILITIES would have to occur, otherwise I don't know how do you understand the word "probability." You will not have an explanation why these other points are still "with" the wavepacket and have not flown elsewhere. For such an explanation, you would have to introduce a causal component which actually cancels all your probabilities and, thus, all the individual life of the points of an orbital. This causal component exists in the Bohm's interpretation (applied separately to the points), because the guiding equation will make the points go in such a way that the "centres of probability" are observed in choosing direction, and thus the points will keep close to the orbital, they will not escape.
Thanks for reading this and please restore the paragraph, maybe with some deletions, because it enriches the article and is even easy to understand and admit. Don't hide the facts. 83.9.142.208