Fig.1. Correlation experiment with single electrons.

1. Electron source
2. Device of single electron registration
3. Amplifier
4. Scattering cristal
5. Matrix of detectors
6. Signal analyzator

In 1949 the Soviet physicists L.Biberman, N.Sushkin, V.Fabrikant have carried out the experiment [1] which have proved, that the wave properties are inherent not only in a beam of electrons, but in each single electron.

The electron beam with energy 72 Kev passed through diffracting object (crystals of the magnesium ocide, applied on a colloid film) and was registering by a sensitive photographic plate. Chaotic light marking of separate grains of photographic plate has merged (by enough time of exposure) in typical diffraction picture.                                           
Diffraction pictures have been received from the beams differing in intensity almost by on seven orders. They have appeared absolutely identical. Measurement of intensity of extremely weak beam has given the value 4,2х10(3) electrons per second. Each electron passed the way in the device in 8,5х10(-9) second whereas the average time between two electron passages was 2,4х10(-4) second, i.e. 30000 times more. Thus, the probability of a casual appearing in the device simultaneously two electrons did not exceed [3,54х10(-5)] (2) ≈ 10 (-9). Any interaction between electrons has been thus excluded, so the diffraction picture has been caused by properties of each separate electron.

This classic experiment could become still more substantial if not only an average picture was considered, but photo shoots would be made with time exposure considerably smaller, than average time between two consecutive electrons 2,4x10(-4) second. In that case each shot would show result of action of each separate electron on a photographic plate.

At such setting of experiment it would be possible to receive the answer to a question: whether electron exists as the localised corpuscle or there is only electronic field?
In the first case (as the corpuscle by definition is indivisible), each electron could cause marking only in one point (more precisely, within one grain of photolayer). Marking at once of two and more grains remote from each other  would not be observed in any picture. Anyway, the probability of occurrence of two marked grains would not exceed probability of casual imposing of two electrons during the time of shot exposure. This probability, evidently, is equal to a square of the relation of shot exposure time to an average time interval between electron passages.

In the second case (if a physical reality is the electronic wave field), one «electron» (actually – one electronic wave train) would mark photographic plate simultaneously in the several points located in limits of  diffraction spot.

Performance of such experiment was quite realizable in 1949 and the more so it does not any difficulties now. To avoid the tiresome visual scanning of shots (which most part remains not marked), the device of automatic scanning with computer data recording can be applied.

As variants the matrix of wave-guide photomultipliers or charge-coupled devises can be applied for electron registration. Separate PM or active (not connected with themselves) pixels CCD can be mutually commuted in the different ways. For example, the readouts of coincidence scheme could have place only in the case of simultaneous actions of two, three, … n pixels.

If electron as a corpuscle really exists, such coincidences should be impossible.
If a physical reality is the electronic field, such coincidences will be rather frequent and easily observed.

Measurement of amplitudes of signals on separate pixels (or PM) will allow to receive the information about distribution of intensity of a field within separate electronic train.

The basic scheme of experiment is presented on a Fig. 1.
Electrons from a low-current source (1) arrive on the device (2), which allows to register the individual electron. Passing through solenoid, electron causes an impulse which through the amplifier (3) switches on the shutter hindering the electron emission during the time Т. It is possible to judge from amplitude of an impulse, only one electron has passed through solenoid, but not two or more.

The individual electron, after passing through the solenoid, gets on a crystal (4) on which one is subjected to diffraction scattering.  The matrix of detectors (5) is put on the way of electronic wave which allows to register the fact of simultaneous occurrence of a signal on two or more detectors (or absence of such fact). Correlation of signals on detectors is analyzed by means of a processing device of signals (6).

If electron is corpuscle, with wave function determining probability of detection, the simultaneous occurrence of signals on different detectors is excluded: corpuscle cannot be in two places at once.

If such correlations would observed, it will mean, electron  does not exist as the localised particle, and  electronic wave field is a physical reality, not just the field of detection probabilities.

Certainly, in the second case new theoretical problems arise: first of all it will be necessary to explain the meaning of such values, as rest mass and electric charge for a wave field.
These questions do not arise in case of validity of corpuscular hypothesis.

However no preliminary theoretical arguments should be obstacles to realization of such experiment: its principle importance does not cause any doubts.

1. L.Biberman, N.Sushkin, V.Fabrikant
Успехи Физических Наук. 1949. Август. Т. XXXVIII, вып.4.

  Similar experiment can be carried out with protons, ions and thermal neutrons. As the corpuscular nature of these pacticles does not cause doubts, expected effect in this case – absence of correlations between signals of detectors.
It allows to simplify experimental scheme – the element 2 ceases to be necessary.