  MOSARIX is a collaborative project between three research group in Sorbonne
University to build a x-ray spectrometer (2-5 keV) portable to large scale
facilities with high efficiency and good resolution. X-ray spectroscopy and
coincidences experiment are planned. A prototype with a single HADP crystal
with von Hamos geometry has been tested (resolution and efficiency). A fast
time and position detector has been realized (patent and publication).We plan
to build the spectrometer with 8 HADP (or 4) crystals under Helium atmosphere
using a TimePix3 or a CCD camera. MOSARIX is a project of an x-ray spectrometer
in the tender x-ray domain (2-5 keV) with high efficiency, allowing performing
x-ray emission and coincidences (or covariance mapping) experiments using
synchrotron radiation, XFEL, the future installation SPIRAL2/GANIL or
CRYRING/FAIR. It involves 2 groups at LCPMR (Francis PENENT and Marc SIMON) and
one group at INSP (Dominique VERNHET). The coincidences/covariance measurements
will be between x-ray photons and ions or electrons. It would be the first time
for such coincidences with energy-resolved photons. The spectrometer will be
portable and will be brought to the different large-scale facilities. MOSARIX
is a multi-crystal HAPG von Hamos spectrometer optimized for the 2-5 keV photon
energy range. Its resolving power E/DE will be 4000. It will be equipped with a
fast time and position sensitive detection system, allowing performing
coincidences, or with a CCD camera. I. Scientific case and some possible
experiments The accelerated development of x-ray sources, as 3 rd generation
synchrotrons (and recent upgrades) or free-electron lasers, has opened new
opportunities to investigate new phenomena by means of photoelectron and Auger
spectroscopy, electron-ion coincidence techniques and x-ray emission. However,
several processes of high scientific interests are still hard to measure; some
of them require the measurement of photons with high efficiency, high
resolution and even sometimes in coincidence mode. This is the purpose of
MOSARIX development. As an example, we propose to revisit Resonance-Enhanced
X-ray Multiple Ionization (REXMI) 1 with a significant amelioration of the
detection of photons, i.e. measuring the photons not only with high efficiency
and high resolution but also in coincidence with ions or electrons. This will
allow accessing the involved intermediate states and obtaining a clearer image
of the dynamic of the multiple ionization process. MOSARIX can also be used for
the investigation of very low cross-section phenomena such as attosecond
electron dynamics 2 and High-Energy Resolution Off-Resonant Spectroscopy
(HEROS) 3,4. X-ray spectroscopy has also proved to be a very powerful tool to
investigate quantum dynamics in heavy ions collisions with matter of whatever
nature, dilute or condensed 5-7. A
