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E N A B L I N G T E C H N O L O G I E S

At the time of writing, the ESRF s new fourth- generation synchrotron, the Extremely Brilliant Source (EBS), has been in operation for over a year and is already operating close to its design parameters. The two major activities of the construction programme for the months to come are the new EBSL beamlines and the refurbishment of existing beamlines.

Among the various technical challenges facing the support divisions, the stability of the concrete experimental hall floor slabs is the one that should retain our attention, since the stability of the instruments depends on the characteristics and performance of the slabs. Thorough coordination between the teams of the Technical Infrastructure Division (TID) and the Instrumentation and Services Development Division (ISDD) is therefore essential.

The stability of the slabs and, more generally, slab performance has always been a concern at the ESRF, starting from the initial construction period when voids were spotted beneath the 18 cm-thick concrete slabs of the experimental hall. With the new EBS machine, the reduction of the beam emittance leads us to continue our efforts to guarantee the stability expected for the nanobeam lines.

The Belledonne and Chartreuse experimental hall constructions were consequently the opportunity to define new technical solutions with the support of an international advisory panel of experienced slab specialists (from ALBA, SOLEIL, DIAMOND, LASER MEGAJOULE and DESY synchrotrons). The challenge was to define solutions providing limited shrinkage and curling effects. It resulted in a monolithic mass created from a continuous pouring of concrete, strongly reinforced, and laid over a 600-mm, roller-compacted concrete base with a few millimetres of bituminous layer in between.