There is a mystery around the quantity of matter that composes the entire universe. Scientists know that approximately 80% of the matter that exists in the universe is not the ordinary matter that is visible, but of entirely a different characteristic. Scientists call this type of matter dark matter (D M). Although the dark matter is not visible, scientists infer its existence by the gravitational effect on visible matter in the universe, such as stars and galaxies.

Dark photon; mediator between dark and visible matter

Scientists know that dark matter is not able to interact with electromagnetic radiation; therefore, it cannot be detected with imaging technology; however, it´s believed that this type of substance could interact with visible material through a different type of medium called dark photon.

A n obscure photon is thought to be interacting between visible and obscure substance, just as a photon does with the electromagnetic force.

The NA64 experiment

This experiment utilizes a beam of CERN´s SPS (Super Proton Synchrotron) to search for a new particle that could be acting as a mediator between ordinary substance and the so called dark or invisible matter. Through a physics concept known as the conservation of energy, a beam of electrons with precisely known energy is directed at a detector; the interactions between the electrons and the detector´s atomic nuclei generate observable photons; the energy of these photons should equal that of the electrons.

The evidence of dark photons is confirmed if the detector is not able to match the original energy, indicating that some fraction of that energy was lost, thus providing evidence of the presence of obscure photons.

Theories about the existence of invisible substance

D M is hypothesized to stem from a yet undiscovered subatomic particle, such as WIMPS which do not absorb or emit light nor interact with other particles. When WIMPS encounter each other, they annihilate, emitting gamma rays. The discovery of this mysterious particle (the dark photon) if confirmed could open a new perspective in the understanding D M and Cosmology.