Progress Report on CBM As of June 2015 (FAIR RRB)

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Progress Report on CBM as of June 2015 (FAIR RRB)

In the following, the progress made in the realization of the CBM experiment since January 2015 is briefly reviewed.

Organization

Two institutions have joined the CBM Collaboration: The China Three Gorges University (CTGU), and the Zuse-Institut Berlin (ZIB). The group from CTGU has a long experience in high-energy heavy-ion experiments (STAR, ALICE), whereas the colleagues from ZIB are experts in High-Performance Computing.

Publication

The CBM Progress Report 2014 has been published with 130 contributions on172 pages (ISBN 978-3-9815227-2-3). See also

Superconducting Dipole Magnet

The detailed specifications have been completed. The collaboration contractbetween FAIR and JINR Dubna is in preparation. Discussions with companies have started.

Silicon Tracking System

For the Silicon Tracking System (STS), final prototype double-sided silicon micro-strip sensors are under production. They comprise three physical geometries with unified layout and are compatible with 4” wafer technology. A fourth prototype sensor is to test the 6” wafer capability of one of the two vendors involved. The second prototype ASIC STS-XYTER has been designed. It is planned to be produced in the second half of 2015. The data transmission part of the ASIC is now compatible with the CERN GBT protocol. The data aggregating electronics is being produced in cooperation with CERN where joint orders for the GBTx chipset have been placed. The assembly of sensors, read-out cables and ASICs into detector modules has been further detailed and tested on prototype components. This includes ultra-thin read-out cables based on aluminum signal lines. Two pilot batches were produced on which quality assurance and yields were studied. An alternative cable technology based on copper technology was started as back-up. The mechanical layout of the STS detector has been advanced and a consolidated CAD model was achieved. It is the starting point for a real-size mechanical mock-up to test various integration and cooling aspects of the STS detector system.

Ring Imaging Cherenkov Detector

Within the RICH project major advances were made in radiation hardness tests: Detailed tests of the H12700 MAPMTs, the integrated voltage divider and the WLS coatings used in order to enhance the UV sensitivity of the MAPMTS were performed with thermal neutrons from the TRIGA reactor in Ljubljana and gammas from a Co60 source at University Giessen. Detailed experience on radiation hardness and possible activation of these components was obtained and as a result no radiation-related damage is expected at CBM radiation levels. These results are also of importance for other projects such as the LHCb RICH upgrade. With these tests the R&D phase of the photon sensors was finalized and 1100 pieces of H12700 MAPMTs were ordered from Hamamatsu for both, the CBM RICH and the HADES RICH upgrade which will take place prior to the start of the CBM operation. Furthermore, progress was made in the development of a common readout scheme for the HADES and CBM RICH MAPMTs based on the analysis of test data obtained in the 2014 test-beam operation of the CBM RICH prototype at CERN and in detailed lab measurements. In detailed simulation studies a large step forward was made in establishing a RICH geometry with tilted mirrors which is currently optimized.

Projectile Spectator Detector

The TDR of the Projectile Spectator Detector (PSD) has been approved by FAIR in February 2015.The collaboration contract between the FAIR GmbH and INR Moscow including all necessary Annexes for the prototyping, production and delivery of the PSD has been prepared.The simulation of the PSD response and the PSD optimization at SIS100 energies is in progress.

Time-of-flight Detector

The TDR of the CBM-TOF has been approved by FAIR in January 2015. The key characteristics of the CBM-TOF are an excellent time resolution (50 ps) in a high multiplicity / high rate environment. This has been proven in a test measurement at the CERN-SPS in Ar + Pb reactions at 10A GeV and 20 AGeV. Moreover, in this experiment the operation of a free running TOF readout system under realistic conditions has been also successfully tested. At the ELBE accelerator at HZDR the timing resolution of ceramic MRPCs with Rogowski electrodeshas been measured.

Muon Chamber System

The TDR for the Muon Chamber System (MuCh) has been approved by FAIR in January 2015. A full size prototype for the 1st MUCH station has been built and tested with X-rays and proton beams at COSY FZ Jülich. The read-out ASIC for the Silicon Detector System (STS-XYTER) has been modified to be used for theMUCH-GEM detectors in a dual-gain mode. Major progress has been made in the design of the mechanical structures for the mounting of thedetector chambers, a prototype is presently being built at VECC Kolkata. The readout ASIC of the CBM TOF detector (PADI) has been successfully tested for the readout of the CBM Straw tube chambers. Realistic feasibility studies have been performed for dimuon signals from heavy-ion collisions at low SIS100 beam energies.

Micro-Vertex Detector

In 2015, the MVD activities focus on prototyping with PRESTO, the characterization of CMOS pixel sensors and simulations on the di-electron physics case. PRESTO is a full-size prototype of a quadrant of the 2nd MVD station, read-out by a TRBv3 based DAQ and comprising ultra-light cables. The integration of M26 sensors on low-mass carriers with dedicated tools has been developed. Also, it was demonstrated, that the latest generation of CMOS sensors reaches the time resolution required for operating the MVD with the ambitioned rates required at SIS-100. Moreover, a novel concept for improving the radiation tolerance of the sensors was validated. The simulation software required for the di-electron physics case was updated with latest knowledge on the sensor response and MVD geometry. Preliminary results suggest improvements in background suppression by employing the MVD in tracking.

Transition Radiation Detector

For the CBM-TRD the development of large-size (i.e. 100 x 100 cm2) prototypes of the readout chambers has been finalized. The large chambers are foreseen for the outer regions of the final detector setup, where the hit densities are lower. It is planned to test the performance of these prototypes in upcoming beam times and to integrate them in a setup for cosmics data taking together with other CBM detectors. A special feature of the large-size chambers is a newly developed supporting grid for the entrance cathode foil made from carbon fiber.R&D work for the CBM TRD gas system has been started and a first prototype system is under development. This system will be used in upcoming in beam tests to monitor the gas flux and quality, and is therefore a key factor for the quality of in-beam data.Performance studies for di-lepton measurements with the CBM-TRD atSIS-100 are being performed. A special focus of this studies is the investigation of the intermediate mass range (1 GeV < mee < 3 GeV) where access to thermal radiation is possible. These studies will be an important ingredient for the finalization of the technical design report.

Electromagnetic Calorimeter

The TDR on the Electromagnetic Calorimeter is planned to be ready end of June 2015. The"Shashlik" technology suggested for the calorimeter is well established and tested in big experiments (PHENIX, HERA-B, LHCb). The efforts concentrated on feasibility studies of various physics cases. The ITEP group has prepared for this summer tests of the calorimeter modules at SPS (CERN) to study the uniformity of transverse light collection efficiency in new modules.

Data Acquisition

The central stage of the CBM DAQ system is the DPB layer. It handles the optical links coming from the detector front-ends with detector specific data formats and provides a generic interface to send data toFLES and to interact with the controls system. It is also the centralpoint for the clock distribution and time synchronization. The plannedimplementation is based on FPGA based boards with micro-TCA form factor.The first prototypes boards were received in May from WUT (Warsaw). All firmware designs required for operation in 2015 and 2016 have beenspecified. Many building blocks (IP cores) have been implemented and arecurrently been tested. First tests of a full read-out chain are plannedfor the second half of 2015.

First Level Event Selection

In the first months of 2015, R&D towards a TDR for the CBM Online Systems have continued. Concerning the First-level Event Selector (FLES), several important steps have been taken towards establishing a complete online readout and reconstruction chain. An important step forward here was the implementation of the FLES input interface as a VHDL design module. Another key advance was the modularization of the FLES data management software framework, adding interfaces at microslice level, which now allows a common framework to accommodate both beam tests and software analysis chain prototypes. Work has also progressed significantly in the area of FLES timeslice building, where an optimized Infiniband routing has allowed us to demonstrate the required simultaneous any-to-any communication at full bandwidth (>5 GB/s per node) in a medium-sized cluster.

Computing

Substantial progress was achieved in the development of high-speed time-slice building as envisioned for the FLES. Prototypes of this software were successfully employed for in-beam tests of CBM detector systems in spring 2015. A high-level implementation based on MPI is under investigation. In data reconstruction, the 4-d track finding algorithm in the STS was further optimised, and a first version of event definition from free-streaming data was developed. In parallel, standalone track reconstruction in the muon system based on the Cellular Automaton algorithm was implemented, which is suitable for online data selection based on charmonium signatures. Reconstruction of particle decays was improved by adding information from PID detectors on the decay products and by improved mathematics.On the infrastructure side, a component database was deployed which offers a tool for the detector project teams to monitor the upcoming mass productions.

Simulations

The improved particle decay reconstruction algorithms nowallow now to study gamma conversion in the detector materials as well as hyper-nuclei. These new features were used to study the sensitivity of CBM to hyper-nuclei and the feasibility to detect photonic decays of light mesons. A dedicated di-lepton analysis software package was implemented to facilitate further studies on these observables. Moreover, progress was made in developing a realistic event generator for in-medium lepton pairs, which is essential to judge the performance of CBM with respect to di-lepton measurements.

Status of purchase

contracts / Value M€ / partner / Status
Purchase RICH MAPMT
HAMAMATSU / 1.65 / GSI / Signed - Order to company made
STS module assembly contract / 1.1 / KIT Karlsruhe / Signed by GSI
Purchase iron for beam dump / 0.25 / KIT Karlsruhe / Signed
Purchase ASIC GBTx / 1.245 / CERN / Signed -Order to CERN made

Status Collaboration contracts with Russia

Project / Partner in Russia / Task / Costs
M€ (2005) / Fraction of total costs / Status / Council
Decision
SC dipole magnet / JINR
Dubna / Design and
Construction / 3.758 / 100% / In prepa-ration / 9.7.2014
STS / JINR
Dubna / Construction of detector ladders / 2.115 / 23% / signed / 10.12.13
PSD / INR Troitzk / Design and
Construction / 0.778 / 81% / Ready to be signed / requested for June 2015
RICH / PNPI Gatchina / Construction of mechanical structures, gas system / 1.45 / 28% / In prepa-ration / 9.7.2014
MUCH / PNPI Gatchina / Construction of absorbers, mechanical structures, gas system / 3.022 / 39% / In prepa-ration / requested for June 2015
MUCH / JINR
Dubna / Straw tube chambers / 0.49 / 6% / In prepa-ration / requested for June 2015
TOF / ITEP Moscow / Inner TOF / In prepa-ration

Status In-kind contracts

Project / Partner Institution / Task / Costs
k€ 2005 / Costs
k€
2015 / Status
In-Kind contract / Council
decision
STS / AGH,
Crakow, Poland / Design and
Construction
of STS-XYTER chip / 572 / 722 / ready
to be signed / requested for June 2015
STS / JU,
Crakow, Poland / Development of test procedures for STS-XYTER chip and FEE / 968 / 1221 / In prepa-ration
HADES / JU,
Crakow, Poland / HADES ECAL
Mechanical frame / 200 / 245 / ready
to be signed / Requested for June 2015
STS / WUT,
Warsaw, Poland / Development of Data Processing Boards (DPBs) / 260 / 328 / first draft prepared / requested for June 2015
TOF / IFIN-HH,
Bukarest, Romania / RPC chambers
and FEE / 748 / 943 / In prepa-
ration / requested for June 2015
MUCH / VECC, Kolkata and Indian CBMCollaboration / GEM chambers
and FEE / Not yet defined / Not yet defined / In prepa-ration

14th June 2015, Peter Senger