Device for characterizing an ionizing radiation

A device for characterizing an ionizing radiation used in an ambient medium having a first refraction index, the device comprising:

• a scintillator material delimited by a wall, the scintillator material generating photons under the effect of an ionizing radiation, the scintillator material having a second refraction index, and
• a guide layer in contact with at least part of the wall, the guide layer guiding toward a predetermined zone, the photons generated by the scintillator material and having an angle of incidence relative to the part of the wall greater than or equal to the arcsin of the ratio of the first refraction index to the second refraction index, the material of the guide layer having a third refraction index, the third refraction index being greater than the first and second refraction indices, the guide layer including at least one diffracting element suitable for orienting photons in a predetermined direction.