The general layout of FERMI is reported below. There are two 1 m-separated undulators (FEL1 and FEL2) delivering the radiation into the photon transport system. The radiation is collected by PADReS (Photon Analysis Delivery and REduction System), and then directed to the selected endstation in the experimental hall. So, any experiment (except MagneDYN) can have access to the full energy spectrum of the two FELs.; MagneDYN, n the contrary, can access only FEL2. It is then necessary to characterize the photon radiation emitted by both the undulator chains. For this reason two identical systems are installed. They consist of a shutter, a beam defining aperture, a beam position monitor, an intensity monitor, a differential pumping system, and a gas adsorption cell. After the gas adsorption cell the system is symmetrically repeated, therefore the light meets a second differential pumping system, a second intensity monitor, a second beam position monitor and, after that, the first mirror. Inside the safety hutch a system of 4 mirrors, two for FEL 1 and two for FEL 2, delivers the radiation to the online photon energy spectrometers that have to analyze, shot by shot, the energy spectrum of the emitted radiation. After that, for the main part of PADReS, an insertable switching mirror gives the possibility of directing the photon beam to the EIS-TIMER endstation. On the central path, on the other way, a beam splitting and delaying section is inserted before the 3-ways switching chamber. Starting from this point 3 branchlines, leading to three endstations (EIS-TIMEX, DiProI and LDM), start and host the refocusing sections. MagneDYN, on the other side, receives the radiation after its energy spectrometer and has only one possible path to the endstation.

Main targets

The main target of PADReS is to analyze the photon beam in terms of absolute intesity, position and spectral distribution of each pulse, working online shot-to-shot. Besides this, there is also the possibility to measure invasively the transversal coherence (on the first part of the EIS-TIMER branchline). Another important section of PADReS is devoted to split the photon beam and to introduce a controllable delay between the two generated semi-beams. Each endstation, at the end, has a dedicated refocusing section made by grazing incidence x-ray mirrors.

PADReS Layout

The PADReS includes the entire photon beam transport and diagnostics system at FERMI, going from the front-end shutters to the valves before the endstations. Part of it is located in the undulator hall (left of the main wall - see figure), part in the so-called safety hutch (between the two walls - see figure), and part in the main experimental hall. The five light-ports provide the photon beam to the respective experiments, and each of them benefit from the analysis and the manipulation performed on the beam itself.

Last Updated on Friday, 15 November 2019 12:07