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The SPD Technical Board was held on Thursday 14 December 2021.
Link to the page with slides: https://indico.jinr.ru/event/2650/
Attendance:
Afanasyev Leonid (JINR)
Alekseev Igor (ITEP)
Alexeev Gennady (JINR)
Alexeev Maxim (Turino Uni)
Anosov Vladimir (JINR)
Bedfer Yann (CEA Saclay)
Chepurnov Alexander (MSU)
Enik Temur (JINR)
Gavrischuk Oleg (JINR)
Guskov Alexey (JINR)
Korzenev Alexander (JINR)
Kulikov Anatoly (JINR)
Ladygin Vladimir (JINR)
Li Xiaomei (CIAE)
Livanov Alexey (JINR)
Tereschenko Vyacheslav (JINR)
Zamiatin Nikolay (JINR)
Agenda:
1. Milestones for TDR preparation / Alexey Guskov
2. Status of the SPD experimental hall / Alexey Livanov
3. Updates for the SPD experimental setup / Alexander Korzenev
4. Updated approach for DAQ and Front-End Electronics Interface / Vyacheslav Tereschenko, Leonid Afanasyev
Summary of discussion:
1. Milestones for TDR preparation / Alexey Guskov
* The result of our communication with the SPD DAC will be reported at the winter session
of PAC for Particle Physics on Jan 20. Concluding remarks sent to us by DAC:
Dear Alexey and colleagues,
we congratulate the collaboration for the progress made over the summer about the points
raised in the previous meeting. The answers to our questions were satisfactory and the
presentations during this second meeting were well received by the committee. Concerning
the SPD detector we particularly appreciated the improvements in the design with respect
to CDR, i.e.:
- the magnet placed outside the ECAL
- the possible use of a full silicon inner tracker
- the clarifications on the straws and ZDC
On the basis of this and on the previous discussion we will propose the PAC to approve
the SPD CDR and move forward to the TDR preparation.
* Important SPD dates:
- The TDR should pass through the Scientific & Technical Board(s) ~10.4.2022
- All the materials should be provided 2 months before PAC: ~20.4.2022
- Presentation at the summer session of the PAC for Particle Physics: ~20.6.2022
* Main changes in the setup with respect to CDR: (1) Magnetic system outside ECAL,
(2) No DSSD+MAPS combination for the vertex detector (disproved by DAC), (3) No aerogel
detector in barrel, (4) New DAQ concept.
* Due to money restrictions we should think about the minimal configuration of the SPD setup
for the beginning of data taking: Range system, magnet and tracker.
- It would be nice to have BBC, ZDC or ECAL at least in one endcap.
- Instead of the silicon vertex detector, we can try using MicroMegas to improve momentum
reconstruction
* Preliminary timescale of the project:
- TDR preparation: 2021-2022
- Detector construction: 2023-2025
- Detector assembling: 2026-2027
- Beginning of data taking: 2028
2. Status of the SPD experimental hall / Alexey Livanov
An overview of the work carried out in the SPD zone since the last TB meeting was presented:
* Access roads to the building are poured with concrete: September 2021
* The interior painting of the walls of the hall is being completed
* Self-leveling floors have been poured. Anti-static tape has been stuck into the floor over
its entire surface: 10/20/2021
* Work on the technological gutters in the concrete floor has been completed: 07/08/2021
* Water-type heating convectors are in the process of being connected
* The interior works in the main control room are almost complete
3. Updates for the SPD experimental setup / Alexander Korzenev
The status of the SPD hardware was reviewed. Updates with respect to the CDR version, which
was release last winter, were presented.
* After careful study, the magnet system with 6 isolated coils originally proposed in CDR
was disfavored. For the current version of the setup, the coils were placed outside ECal.
New figures for the schematic view of the SPD setup has been released.
* Two option for the magnet are being considered. They are based on two different cable type
technologies:
- The use of a Rutherford-type cable made of NbTi superconductor. This cable will be encased
in an Al stabiliser using a co-extrusion process that provides a good bond between Al and
superconductor in order to ensure quench protection during operation. Cooling will be
provided by liquid He which circulates in pipes welded to the outside of the coil former.
Proposed by the team of BINP Novosibirsk.
- The technology of superconducting coils manufacturing is based on a hollow high-current cable
similar to the one used for the Nuclotron magnets or the one used in the ITER systems. The
manufacturing technology of a hollow cable made of NbTi/Cu composite wires cooled at 4.5 K
with a forced helium flow is well developed at LHEP JINR. Proposed by team of LHEP JINR.
* In order to make the distribution of the efficiency ECal more uniform in azimuth, it was
proposed to group the calorimeter modules into rings, and not into sectors, as was done in MPD.
Two approaches for for the construction of ECal are under discussion: (1) Half-sector approach
as it is done in MPD, (2) Ring approach.
* Two MRPC proposals for the Time-of-flight system are under discussion: (1) Tsinghua proposal,
(2) Protvino proposal. The main difference is in the chamber configuration for endcaps.
* For the first years of the experiment, it is proposed to replace the silicon vertex detector
with a simpler and cheaper to manufacture MicroMegas. The proposal is largely based on
information obtained about MicroMegas for the vertex detector of the CLAS12 experiment at JLAb,
manufactured by the CEA/Saclay group.
* Agreement on the detector nomenclature scheme for the SPD design documentation has been achieved
4. Updated approach for DAQ and Front-End Electronics Interface / Vyacheslav Tereschenko,
Leonid Afanasyev
* The status of the FEE of the Range System, as the most advanced system for today, was reviewed
* An update for the last stage of DAQ was discussed, i.e. slice/frame building:
- Number of readout computers will be defined by the bandwidth of Multiplexers, now it is
estimated as 1 GB/s. Readout computer - diskless computer with 128GB RAM and 2 x 10 Gb or
1 x 25 Gb Ethernet.
- Builder computer - diskless computer with 64GB RAM, 10/25 Gb Ethernet and interface to Disk
Buffer. Number of builder computer will be defined by the loading about 0.5GB/s per 1 builder
computer.
- For the input flux of 20GB/s, the Ethernet switch should have at least 80x10 Gb or 60x25 Gb
connections and 2x100 Gb uplink connection (if needed). The Disk Buffer is estimated to have
2PB with 50GB/s read/write access.
- A contiguous set of slices (chunks) or a complete frame containing data from all detectors are
bullied by a pool of Builder computers under control of the Builder supervise.
The date of the next Technical Board meeting was set to the end of winter. The main subject for
discussion will be the TDR preparation.