Speaker
Description
The Micro Vertex Detector (MVD) is the first downstream detector of the fixed-target CBM experiment at the future Facility for Antiproton and Ion Research (FAIR). It extends the high-precision tracking towards low momenta in direct proximity of the target with the first station being placed 8cm downstream the interaction point. The four planar stations operate in the target vacuum and are equipped with $\sim$300 MIMOSIS CMOS Monolithic Active Pixel Sensors (MAPS) which have been developed in a joint R&D effort by IPHC Strasbourg, Goethe University Frankfurt and GSI Darmstadt. MIMOSIS is produced in the TJ-180nm process and features a $1024\times504$ pixel matrix with a global shutter ($5\mu$s frame time). A large variety of different designs have been tested, e.g. standard and modified pixel variants, two epitaxial options (25/50$\mu$m), and AC and DC-coupled front-ends. The performance has been validated both for radiation tolerance (5Mrad and 1$\times$10$^{14}n_{\text{eq}}$/cm$^2$), and for its full-system compatibility (e.g. realistic powering and data transport). Its free-streaming DAQ compatibility has been validated in the mCBM@SIS-18 test setup with a first system-level prototype (mMVD).
In the MVD, the sensors will be wire-bonded to thin flex cables and glued onto Thermal Pyrolytic Graphite (TPG; 380$\mu$m) carriers, which provide stiff, low-$X_0$ support with a high in-plane thermal conduction ($\sim$1500 W/m.K) in the acceptance. Actively cooled heat sinks outside the acceptance extract the heat. Sensors are integrated double-sided, achieving a 100% fill factor.
With the final MIMOSIS expected end of 2026 and module pre-production ongoing with prototype sensors, we are preparing the full-system integration. In this contribution, we present the detector concept, results from the prototype MIMOSIS sensors and its integration into the Micro Vertex Detector. A focal point will be the challenges associated with the stringent material budget constraints (0.3-0.5%$X_0$) and vacuum operation as we progress toward CBM commissioning end of 2028.