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The CBM-RICH detector is designed to identify electrons with momenta up to 8 GeV/c and high purity as this is essential for the CBM physics program. The detector consist of a CO2-gaseous radiator, a spherical mirror system, and Multi-Anode PhotoMultiplier Tubes (MAPMT) of type H12700 from Hamamatsu as photon detectors. The detector concept was verified through R&D studies and a laterally scaled prototype. The results were summarized in a TDR, in which open issues were defined concerning the readout electronics, the shielding of the magnetic stray field in the MAPMT region, the radiation hardness of the MAPMT sensors, and the mechanical holding structure of the mirror system. In this article an overview is given on the CBM RICH development with focus on those open issues.

The Compressed Baryonic Matter (CBM) experiment at the future FAIR facility will investigate the QCD phase diagram at high net baryon densities and moderate temperatures in A+A collisions from 2 to 11 AGeV (SIS100). Electron identification in CBM will be performed by a Ring Imaging Cherenkov (RICH) detector and Transition Radiation Detectors (TRD). A real size prototype of the RICH detector was tested together with other CBM groups at the CERN PS/T9 beam line in 2014. For the first time the data format used the FLESnet protocol from CBM delivering free streaming data. The analysis was fully performed within the CBMROOT framework. In this contribution the data analysis and the event reconstruction methods which were used for obtained data are discussed. Rings were reconstructed using an algorithm based on the Hough Transform method and their parameters were derived with high accuracy by circle and ellipse fitting procedures. We present results of the application of the presented algorithms. In particular we compare results with and without Wavelength shifting (WLS) coating.

The Compressed Baryonic Matter (CBM) experiment at the future Facility for Anti-proton and Ion Research (FAIR) will investigate the phase diagram of strongly interacting matter at high net-baryon density and moderate temperature in A+A collisions. One of the key detectors of CBM to explore this physics program is a Ring Imaging CHerenkov (RICH) detector for electron identification. For a high performance of the RICH detector precise mirror alignment is essential. A three-step correction cycle has been developed, which will be discussed: First a qualitative, fast check of the mirror positions, second a quantitative determination of possible misalignments and third a software correction routine, allowing a proper functioning of the RICH under misalignment conditions.

A real size prototype of the CBM RICH detector was tested in beam at CERN in November 2014 with new readout electronics. A detailed analysis of the timing characteristics of the readout chain will be presented in this article. Results of the time precision measurements for several subsets of all channels and the stability of the fine time calibration will be discussed. The obtained sub-nanosecond time precision allows also to investigate the effect on timing when using additional wavelength-shifting films on top of the MAPMT windows.

In 2015 1100 Multi-Anode Photo-Multipliers (MAPMTs) of type HAMAMATSU H12700 were ordered to equip the photon detection plane of the CBM-RICH and HADES-RICH detectors. Both experiments aim to study the properties of dense matter produced in heavy ion collisions. To measure the characteristics of all ordered MAPMTs and give feedback to the manufacturer, a test bench was built at the University of Wuppertal. This paper describes the working principle of the test bench and compiles the measurements of the first 400 H12700 MAPMTs delivered. The average characteristics of the H12700 gathered from these measurements are discussed and compared to measurements of the HAMAMATSU H8500.

Wavelength-shifting (WLS) films of p-terphenyl have been applied by means of dip-coating on the entrance window of the H12700 multi anode photomultiplier (MAPMT) in order to enhance the UV sensitivity. Using coated and uncoated MAPMTs in a CBM RICH testbox in a proton testbeam at the COSY accelerator, an enhancement of the number of hits per ring of 15%–20% depending on cuts has been observed. Due to new fast readout electronics of the RICH detector for the CBM/ HADES experiments, the time response of p-terphenyl has been measured to show a decay constant of 2.35 ns. This compares well with time-resolved fluorescence measurements of the films.

The upgraded HADES RICH detector, as well as the future CBM RICH detector, will both use the same Hamamatsu H12700 Multianode PMTs read out by the newly developed DiRICH FPGA-TDC readout chain for MAPMTs and MCPs. The upgrade of the HADES RICH photon detector has meanwhile been completed, and we are now looking forward to the upcoming physics run in spring 2019. A brief overview on the status of both detector projects is given and supplemented with the recent test-beam results which confirmed the functionality of the DiRICH development before the start of the mass-production of all DiRICH components needed for the HADES RICH upgrade.

The Compressed Baryonic Matter (CBM) experiment at the future Facility for Anti-proton and Ion Research (FAIR) complex will explore the phase diagram of strongly interacting matter at high baryon density and moderate temperatures in A+A collisions. The energy spectrum will start at 2 AGeV/c and extend up to 11 AGeV/c for the heaviest nuclei at the SIS 100 accelerator set-up. To explore the physics program of CBM, a RICH detector will be employed for electron identification and pion suppression in a momentum range up to 8 GeV/c. Mirror alignment is a key issue for a proper detector operation. The final conceptual design for a monitoring system of the alignment of the mirrors of the CBM RICH detector will be introduced. It consists of a fast qualitative check of the alignment as well as two different methods to derive quantitative numbers for misalignments. A software correction cycle had been developed which, once applied allows to get back to physics performances as in an ideally aligned case.