milano interneIstituto Nazionale di Fisica Nucleare
Sezione di Milano

STAR Project

STAR project at UniCal will start commissioning soon


The STAR Project, based on a collaboration among UniCal, CNISM, INFN and Sincrotrone Trieste, is in its advanced stage of installation and test at the University of Calabria (UniCal), one of the largest University Campus of southern Italy. Here, inside a dedicated building with a radio-protection bunker, a short linear accelerator for high brightness electron beams will drive a unique advanced X-ray Thomson source. This source will produce mono-chromatic, polarized and tunable X-ray beams, ranging from 30 keV up to 140 KeV. The specific contribution to the STAR Project by INFN Milano has been remarkable from the theoretical/design and technical point of view, resulting in the project and technical coordination leadership. Also a group from Physics Dept. at the University of Milano has contributed very significantly in the theoretical modelling and understanding of these advanced radiation sources. The Accelerator Division of LNF-INFN (Laboratori Nazionali di Frascati dell’INFN) contributed in a crucial way to the design, test of components and the installation of the machine at the STAR site: it is providing at the moment the main technical support and is sharing the technical responsibility of the machine installation and commissioning, and at the same time is actively pursuing the transfer of expertise to the resident STAR technical team.


This peculiar and tunable X-ray source will be devoted mainly to matter science experiments, cultural heritage and advanced radiological imagining with micro-tomography capabilities. An example of the machine capability is reported in the paper: Scientific Report 6, Article n.27227. Here researchers involved in the STAR source development, within an international research collaboration based at the European Synchrotron Radiation Facility (ESRF-Grenoble) , has showed outstanding results in the virtual unrolling and reading of carbonized Herculaneum papyrus by using X-ray phase-contrast tomography (at 80, 52 and 30 KeV): a very unique experiment with large impact on archeology and cultural heritage research that could be replicated at STAR.


The STAR machine layout is as follows:

One S-band RF Photo-injector running at 100 Hz (world-wide second in operation at such a rep rate, critical to achieve the X-ray flux requested by experiments) will produce electron bunches boosted up to 60 MeV by a 3m long S-band TW cavity. A dog-leg beam transport line will bring the beam on a parallel line, shielding the X-ray line from the background radiation caused by the Linac dark current. The peculiarity of such a machine is the ability to produce high quality electron beams, with low emittance and high stability, allowing to reach spot sizes around 10-15 microns at the interaction point, with a pointing jitter of the order of a few microns.


The collision laser is based on a Yb:Yag 100 Hz high quality laser system, synchronized to an external photo-cathode laser and to the RF system to better than 1 ps time jitter. We notice a quite strong sinergy with the ELI-NP-GBS in construction at ELI-NP in Romania, where INFN is main coordinator of the machine construction on behalf of a large European Collaboration named EuroGammaS: the ELI-NP-GBS design group is actually very much the same as for the STAR Project, mainly based on a well world-wide recognized expertise (see publication list at the bottom) in the theory, modelling and design of Compton/Thomson Sources based at INFN Milano and Phys. Dept. of University of Milan.


The first X-ray beams are expected by the summer of 2017. Update images (November 2016) of the STAR machine are shown below:




Media coverage:  (watch in particular the last 5 minutes of the video)

Scientific Reports:

Related Projects:


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