Per la prima volta in Italia é stato realizzato e messo in funzione un laser ad elettroni liberi (FEL) a piccole lunghezze d'onda basato su un acceleratore lineare.

The FEL emits extremely intense and ultra-short radiation, which can be used to photograph molecules, proteins, and viruses during their activity and to observe ultrarapid biochemical phenomena, which previously had not been possible.

This is the second laser of this type in Europe, the first being FLASH in Germany. 

This prototype (which is approximately 35 meters long) was developed at the laboratories of Italy’s National Institute of Nuclear Physics (INFN) in the town of Frascati by a group of researchers from INFN, ENEA, CNR and Italian universitites, funded by the Ministry of University Education and Research (MIUR) and the European Union.

The FEL, which is known as “SPARC” (Sorgente Pulsata Autoamplificata di Radiazione Coerente – Autoamplified Pulsed Source of Coherent Radiation), constitutes the first real step towards the realisation of “SPARX”, which will extend the radiation emited by X-rays and is currently in an advanced stage of development.

This supermicroscope of the future will contribute to rapid developments in scientific and technological research in many sectors in Italy, including nanotechnology and biomedical sciences; it will be constructed at the “Tor Vergata” University and funded by MIUR and the Lazio Region.

Technically, the FEL is a source of shortwave monochromatic electromagnetic radiation; the wavelength is as short as fractions of one billionth of a meter, which is typical of X rays.

These mechanisms basically consist of numerous small magnets, approximately 1 cm in length, with alternate polarity, which form an inverter in which an electron beam of high charge density is injected by interacting with the magnetic structure, the electrons oscillate and become organised, emitting radiation with a typical wavelength, known as “resonance”, which depends on the intensity of the magnetic field and on the energy of the electron beam.

By changing the energy of the electrons, the colour of the emitted radiation can be varied.  The SPARC research group has obtained green radiation (which corresponds to a wavelength of 500 nanometers) by injecting into the inverter (which is approximately 14 meters long and consists of more than 1,800 magnets) a beam of electrons which are accelerated by a difference of radiofrequency potential equal to 150 million Volts produced by a linear accelerator approximately 12 meters in length.

The future SPARX project will involve the use of more powerful linear accelerators, capable of bringing electrons to an energy of around 2.5 billion electron-Volts and inverters as long as 50 meters.