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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 on 172
pages (ISBN 978-3-9815227-2-3). See also
https://www-alt.gsi.de/documents/DOC-2015-Apr-43-1.pdf
Superconducting Dipole Magnet
The detailed specifications have been completed. The collaboration contract between
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 microstrip 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-
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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 electrodes has 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 the MUCHGEM detectors in a dual-gain mode. Major progress has been made in the design of
the mechanical structures for the mounting of the detector 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 lowmass carriers with dedicated tools has been developed. Also, it was demonstrated,
that the latest generation of CMOS sensors reaches the time resolution required for
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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 at SIS-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 to FLES and to interact with the controls
system. It is also the central point for the clock distribution and time synchronization.
The planned implementation 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 been specified. Many
building blocks (IP cores) have been implemented and are currently been tested.
First tests of a full read-out chain are planned for 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
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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 now allow 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 inmedium 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
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
HAMAMATSU
Signed -Order to
CERN made
5
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 preparation
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 preparation
9.7.2014
MUCH
PNPI
Gatchina
Construction
of absorbers,
mechanical
structures,
gas system
3.022
39%
In preparation
requested
for June
2015
MUCH
JINR
Dubna
Straw tube
chambers
0.49
6%
In preparation
requested
for June
2015
TOF
ITEP
Moscow
Inner TOF
In preparation
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Status In-kind contracts
Project
Partner
Institution
Task
Costs
Costs
Status
Council
k€
2005
k€
2015
In-Kind
contract
decision
STS
AGH,
Crakow,
Poland
Design and
Construction
of STSXYTER chip
572
722
ready
to be
signed
requested
for June
2015
STS
JU,
Development
of test
procedures
for STSXYTER chip
and FEE
968
1221
In preparation
HADES
ECAL
200
245
ready
to be
signed
Requested
for June
2015
260
328
Warsaw,
Poland
Development
of Data
Processing
Boards
(DPBs)
first draft
prepared
requested
for June
2015
TOF
IFIN-HH,
Bukarest,
Romania
RPC
chambers
and FEE
748
943
In preparation
requested
for June
2015
MUCH
VECC,
Kolkata and
Indian CBM
Collaboration
GEM
chambers
and FEE
Not yet
defined
Not yet
defined
In preparation
Crakow,
Poland
HADES
JU,
Crakow,
Poland
STS
WUT,
Mechanical
frame
14th June 2015, Peter Senger