Fabrication, Assembly and Testing of the Reflection Grating Arrays aboard XMM

The Reflection Grating Spectrometer (RGS) aboard XMM is a high throughput, dispersive soft X-Ray spectrometer designed to operate with a resolving power of a few hundred between 5 and 35 Angstroms in first order. Arrays of grating replicas (RGAs), assembled to work as single dispersive optics, intercept roughly 45% of the converging light behind the Mirror Module (MM) exit apertures on two of the three nested-shell X-Ray telescopes. Dispersed light is read out on the two, 300mm long, back-illuminated CCD arrays, housed in the RGS focal-plane cameras (RFCs). In short, XMM/RGS offers unrivaled soft X-Ray spectroscopic collection area. The two flight model RGAs were assembled at Columbia Astrophysics Lab and have already undergone end-to-end testing: both at MPE/Panter and at the XMM Vertical Facility (Centre Spatial de Liege). Results from these measurement campaigns will be presented, and they indicate the expected flight performance of the XMM/RGS spectrometer system.