| SPARX-FEL infrastructure |
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The SPARX source will produce X-rays with absolutely unprecedented characteristics, among which three are particularly important: the space coherence of the radiation; its peak brilliance, about 1032 (in conventional units, c. u., that is photons/s/mrad2/mm2, 0.1% band width); the duration of each pulse, about 100 femtoseconds. In the final project, possible experimental techniques to obtain even shorter pulses, i.e. few femtoseconds long, will be studied. Concerning the spectral range, SPARX will be realized in two phases: the first one foresees the emission of radiation with wavelength between 30.0nm and 4.0nm; the second phase foresees the emission down to 0.6nm The use of higher harmonics (third and fifth) will allow a wide tunability of the energy between 30.0nm and 0.12nm and between 1.5 nm and 0.3 nm, respectively. The parameters of the SPARX source, presented in detail in the next sections, are obviously susceptible of revisions in the advanced phase of the project in order to meet the requirements of new users and new disciplines (together with possible technological improvements). The use of the ultra-short and ultra-brilliant pulses, in the energy interval mentioned above, will find a huge variety of advanced applications in a wide range of scientific and technological disciplines. The Site The SPARX X-FEL accelerator will be built in the Tor Vergata campus site, a few km south of the city of Rome. It will be disposed along a linear geometry, approximately 0.5 km long. The ground in this area has volcanic origin. A geological analysis of the territory has been carried out and it has proved that the ground is made of very stable rock.
The SPARX facility is housed in a complex of civil buildings, part of which is underground. The surface buildings have been reduced at minimum in order to fulfil the town planning scheme of the Tor Vergata area, and they consist of a big building at the head of the facility and another one at the end of the LINAC, just above the undulator hall. The underground buildings consist of a service building at the beginning of the LINAC, and of two double tunnels and a main hall for a total length of a bit more than 400m. The first tunnel will house the injector and the linac, the second tunnel will house the undulators and the hall will house the experimental lines and devices.  Linac and undulator halls will be divided in two overlapping tunnels. The lower tunnel will house the accelerator components, while the upper ones will house all the backing equipment such as modulators, klystrons and power supplies. The tunnel above the Undulator Hall will house a magnetic measuring machine and a workshop containing some supporting devices, while the surface building will house the control room. Finally the experimental hall is an open space of 60x30 m2 in which the beam lines and stations will be installed. SPARX-FEL layoutThe Injector of the accelerator is a copy of SPARC photo injector. 
It is composed by an RF gun surrounded by a solenoid, three accelerating structures, the first two of which are embedded in a series of focusing solenoids, see dedicated section in chapter 5. After the gun a diagnostics section is foreseen to measure the characteristics at 6 MeV. Read more...
The 150 MeV beam is boosted by a first stage of three accelerating structures (LINAC1) before the first bunch compressor (BC1) and a second stage, named LINAC2 followed by BC2. 15 RF structures accelerate the beam up to 1.5 GeV where the electron beam is extracted and sent along the transfer line.
 Below the transfer line parallel to the main linac and the third bunch compressor (BC3) are shown; because of the small exit angle the magnetic elements are longitudinally shifted to avoid installation interference. In the following line the diagnostics devices to measure the electron bunches at 1.5 GeV are foreseen. LINAC4, composed by other 15 RF structures, accelerates the beam up to 2.4 GeV, before being sent into the undulators. The transfer line will send the beam from the linac to the different undulators. Because of the small deflecting angles, a special lattice is designed avoiding magnetic elements and lines conflict. Read more...
Three undulators are foreseen to cover the photon spectral range of the project (see parameter list).
 The undulator on the right end, following the beam, receives the electron bunch with energy up to 1.5 GeV, the left end one is dedicated to the high energy electron and the central is multi-stage undulators in which both low and high energy beam can be sent. At the very end of the undulators sections the bending magnets necessary to send the electron beam to the below dump. The SASE and Seeded FEL photons produced in the undulators propagate in proper beam lines with suitable optical components. The optical line configurations allows the simultaneous use of different experimental stations. Read more...
SPARX-FEL parameters
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