Welcome to the website dedicated to the scientific project AXIOMA.
The Axioma research project is aimed at the development of a completely new class of detectors based on Active Sensing for the detection of axions, neutrinos and neutrons, as to register very small excitation energy within the matter well below the present state of the art of energy thresholds and in the meantime open a new research line into the laser-nuclear interaction.
An outstanding result of modern cosmology is that a significant fraction of the universe is matter of unknown form, the so-called dark matter (DM), whose existence is claimed through its gravitational interaction with ordinary barionic matter. A favored DM candidate is the axion, a new particle that followed the introduction of a solution to the strong CP problem by Peccei and Quinn (R.D. Peccei, H.R. Quinn, Phys. Rev. Lett. 38, 1440 (1977)).
Axions have mass m
a inversely proportional to the Peccei-Quinn symmetry breaking scale f
a. For certain ranges of m
a (typically ranging from µeV to meV), large quantities of axions may have been produced in the early universe that could account for the galactic halo dark matter. An observer on Earth would then perceive an “axion wind”, because of the motion of the Solar System through the galactic halo.
The proposed research activity is aimed at detecting axionic dark matter in two different configurations. The first exploits the axion-electron coupling, the second the axion coupling to the photon. These two types of interactions will be investigated with the methods described in the two Working Packages (WP) of the project.
- Axion-electron coupling (WP1)
In order to observe the “invisible axion” through the axion-electron coupling approach, we devise a magnetized sample with a Zeeman transition tuned to the axion mass by an external polarizing static B field. The effect of the axion wind on such magnetized material can be described as an effective oscillating magnetic field with frequency determined by m
a, and strength related to f
a. The axion field will then drive the Zeeman transition from the ground to the excited state of the sample. The possibility to probe such excited state by means of a laser is envisaged when the laser wavelength is tuned to another transition to a higher fluorescent level. It is worth noticing that the magnetized sample must be cooled to ultra-cryogenic temperature to avoid thermal excitation. A new particle detection method is then introduced in the present project, which is based on an active probing process realized through laser systems tuned to well defined atomic or molecular transitions of the active media. The species that act as target can be hosted in molecular crystals such as the solid neon matrix or para-hydrogen crystals, recently developed media in which the embedded atoms retain the structure of free atoms.
- Axion-photon coupling (WP2)
The second configuration is based on an analogous laser-driven, fluorescence-emitting transitions detection scheme, but with a different type of material. Rare-earth doped optical crystals will be thoroughly investigated in this part of the project, in order to apply the infrared quantum counter (IRQC) scheme to particle detection. Unparalleled sensitivities can in principle be obtained, if the active material exhibits a metastable level close to the ground state and it is properly co-doped to optimize the mechanisms of energy transfers between the doping ions, among other properties that will be detailed in the present project. We also plan to realize optical amplification schemes and to use recycling techniques to improve the detector energy threshold. In this second detection approach the possibility to investigate several fundamental physics phenomena would disclose, if the target sensitivity is reached. In fact, a detector with both low energy threshold and appreciable active mass applies as well to neutrino searches.