BEATS has awarded a contract to the Danish company JJ X-ray for the production of the Front-End for the future tomography beamline at SESAME. Delivery is scheduled for May 2022.
The Front-End (FE) of the beamline is an assembly of elements that channel the photons generated by the X-ray source to the optics hutch of the beamline. The FE connects to the storage ring at a tangent and passes through the shielding wall of the accelerator tunnel to the first part of the beamline.
The most important function of the FE is to allow to safely switch on and off the inflow to the beamline of the X-rays generated by the source. This is especially important when accessing the optics and experimental hutches of the beamline. At BEATS, the source is a three-pole wiggler.
The FE assembly is composed of a series of components, as follows:
A photon shutter is a movable water-cooled copper blade designed to intercept and absorb the complete white beam when in the closed position. It protects down-stream components and allows safe access to the optics and experimental hutches.
A bremsstrahlung stopper is an uncooled collimating tungsten alloy block that absorbs off-axis bremsstrahlung radiation from the insertion device straight section.
A crotch absorber, situated at the exit of the insertion device vacuum chamber, collimates the beam and protects the downstream vacuum chambers and FE components from radiation.
A fixed mask defines the beamline aperture and reduces the heatload on the downstream FE elements.
Primary slits (horizontal and vertical) tailor the beam dimensions to the needs of the experiment.
An attenuator adapts the overall flux and shape of the beam to the needs of the users by means of absorbent foils of varying thickness.
The FE assembly also guarantees the proper separation of the storage ring from the beamline in terms of vacuum thanks to a diamond window and a fast vacuum shutter.
The Final Design Report for the Front-End was approved on 23rd September. The Front-End was designed by BEATS experts from ALBA, Elettra, ESRF and SESAME who will continue to follow-up production, installation and commissioning of the assembly.