Simbol-X Hard X-ray Focusing Mirrors: Results Obtained During the Phase A Study

Simbol-X will push grazing incidence imaging up to 80 keV, providing a strong improvement both in sensitivity and angular resolution compared to all instruments that have operated so far above 10 keV. The superb hard X-ray imaging capability will be guaranteed by a mirror module of 100 electroformed Nickel shells with a multilayer reflecting coating. Here we will describe the technogical development and solutions adopted for the fabrication of the mirror module, that must guarantee an Half Energy Width (HEW) better than 20 arcsec from 0.5 up to 30 keV and a goal of 40 arcsec at 60 keV. During the phase A, terminated at the end of 2008, we have developed three engineering models with two, two and three shells, respectively. The most critical aspects in the development of the Simbol-X mirrors are i) the production of the 100 mandrels with very good surface quality within the timeline of the mission; ii) the replication of shells that must be very thin (a factor of 2 thinner than those of XMM-Newton) and still have very good image quality up to 80 keV; iii) the development of an integration process that allows us to integrate these very thin mirrors maintaining their intrinsic good image quality. The Phase A study has shown that we can fabricate the mandrels with the needed quality and that we have developed a valid integration process. The shells that we have produced so far have a quite good image quality, e.g. HEW <~30 arcsec at 30 keV, and effective area. However, we still need to make some improvements to reach the requirements. We will briefly present these results and discuss the possible improvements that we will investigate during phase B.Comment: 6 pages, 3 figures, invited talk at the conference "2nd International Simbol-X Symposium", Paris, 2-5 december, 200

X-ray testing of the Einstein Probe follow-up x-ray telescope STM at MPE’s PANTER facility

The Einstein Probe mission, due to launch in late 2022, will study time-domain astrophysics and monitor variable objects. It aims to observe x-ray counterparts of gravitational wave sources and high-redshift gamma ray bursts. Developed and built by the Chinese Academy of Sciences, Einstein Probe will use two types of telescope: the WideField X-ray Telescope (WXT) and the Follow-Up X-ray Telescope (FXT). The FXT will perform follow-up observations of sources discovered by the WXT, and will observe in the energy range of 0.5 to 8 keV. The performance aim of the FXT – the point spread function half-energy width (PSF HEW) – is <20 arcseconds (on-axis at 1.49 keV). The Max-Planck Institute for Extraterrestrial Physics (MPE) is producing and integrating the x-ray straylight baffle for the FXT, as well as testing and calibrating the different models of the FXT x-ray optic. Production of the structural-thermal model (STM) for Einstein Probe FXT began in 2019. The STM mirror module, produced by Media Lario, has been tested at MPE’s PANTER x-ray test facility. Following this acceptance test, further x-ray tests have been performed at PANTER after each of the subsequent stages: the mounting of the x-ray baffle, the shock and vibration test, and the thermal cycling test. The x-ray performance of the FXT STM is documented at each stage and the results of each test are presented in this paper

Development of cold-slumping glass mirrors for imaging Cherenkov telescopes

The development of lightweight glass mirrors manufactured via cold-slumping technique for Imaging Atmospheric Cherenkov Telescope is presented. The mirror elements have a sandwich-like structure where the reflecting and backing facets are composed by glass sheets with an interposed honeycomb aluminum core. The reflecting coating is deposited in high vacuum by means of physical vapor deposition and consists of aluminum with an additional protective layer of SiO2. The mirror fabrication and environmental qualification by accelerated ageing, thermal cycling and coating adhesion are presented together with the optical performances measured as angular resolution and reflectivity obtained on spherical, 1 squared meter mirror prototypes