Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 50 (2017)

Parallel Readout VME DAQ system
H. Baba,*1 T. Ichihara,*1 T. Isobe,*1 T. Ohnishi,*1 K. Yoshida,*1 Y. Watanabe,*1 S. Ota,*2 S. Shimoura,*2S. Takeuchi,*3 R. Yokoyama,*2 and J. Zenihiro*1
We have been developing the data acquisition(DAQ) system at RIBF. The parallel readout VME
DAQ system was constructed to improve the DAQ performance. The system is based on RIBFDAQ,1) andthe data readout of all VME modules is completely
parallelized by a mountable controller (MOCO).2) A
conceptual design of the system is shown in Fig. 1. A
typical VME-based system adopts a controller board
to read out data from multiple VME modules, whereas
this system uses MOCO together with a front-end computer: this combination acts as a readout controller
to each VME module. This system was introducedin the NP1312-RIBF113 and NP1512-RIBF79R1 experiments. CAT3) and ESPRI4) detectors were installed at the F8 and F12 focal planes, respectively.
The DAQ systems of both detectors worked independently, but the data of the DAQ system for beam-linedetectors (beam-DAQ) were common. To synchronize
absolute time information, a time-stamping system5)
was used. After the measurements, separately taken
data are merged based on time information. In thiscase, the live time ratio of the combined system will
be worse because the dead time of each system is notshared on an event-by-event basis. The trigger rate ofbeam-DAQ is relatively high because the trigger signals from CAT, ESPRI and the beam-line detectors(down-scaled) were applied. Therefore, we have introduced the parallel readout VME DAQ system for thebeam-line detector to minimize the dead time.
In the experiments, VME modules of CAEN V1190
TDC, CAEN V1290 TDC and Niki-glass LUPO9) wereused together with MOCO as front-end systems. Figure 2 shows the installation of VME modules. As inthe standard RIBFDAQ system, the dead time of each
event, which is managed by a generic trigger operator (GTO),6,7) is determined by the slowest front-endsystem. The slowest one was CAEN V1190 TDC +MOCO for LP-MWDC8) at the F3 focal plane. Its
dead time consists of the TDC time window (6 µs),the latency from the end of the TDC time window until the time when the data is ready (2 µs), and data
readout time by MOCO (the number of hits × 0.2 µs).
Each module’s data are buffered in MOCO once, after it is acquired by a front-end computer through theUSB bus. Next, the front-end computer packs data toconform to the RIBFDAQ-data format, and sends thedata to the back-end system (i.e., the event builder
in RIBFDAQ). If the data throughput of the front*1*2*3RIKEN Nishina Center
Center for Nuclear Study, University of Tokyo
Department of Physics, Tokyo Institute of Technology

1 module per
1 readout board

1 Controller Board readout all VME module data

MOCOParallelization

Fig. 1. Conceptual design of the system.

F3 focal plane
V1190 x 2for LP-MWDC

F5 focal plane
V1190 x 2for LP-MWDC

F7 focal plane
V1190 x 2for LP-MWDC

B2F
B3F
SHARAQ measurement room
V1290 x 1 for Diamond detectors

BigRIPS measurement rooms
V1290 x 1 fo
V1190 x 1 for PPACs
LUPO x 1 for Time Stamp

Fig. 2. VME modules for the experiments.

end computer is sufficiently high, additional dead time
does not occur. In these experiments, a Raspberry
Pi (Version 2, Model B) which is a very cheap computer was adopted. In fact, MOCO is capable of data
throughput up to 320 Mbps, but it is limited to 64
Mbps because of the limitations of Raspberry Pi. The
total data rate of beam-DAQ was 22 Mbps (typically 2Mbps per front-end system). This rate is much lower
than the limitation caused by Raspberry Pi. A livetime ratio of 99% could be achieved with respect tothe generated triggers.
In summary, the parallel readout VME DAQ systemsuccessfully worked with very good performance. Thissystem was temporally installed during the NP1312RIBF113 and NP1512-RIBF79R1 experiments. We
plan to install this system for the beam-line detectors
permanently.
References
1) H. Baba et al., Nucl. Instr. Meth. A 616, 65 (2010).
2) H. Baba et al., RIKEN Acc. Prog. Rep. 45, ix (2012).
3) S. Ota et al., J. Radio. Nucl. Chem. 305, 907 (2015).
4) Y. Matsuda et al., Phys. Rev. C 87, 034614 (2013).
5) H. Baba et al., Nucl. Instr. and Meth. A 777, 75 (2015).
6) H. Baba et al., RIKEN Acc. Prog. Rep. 46, 213 (2013).
7) H. Baba et al., RIKEN Acc. Prog. Rep. 47, 235 (2014).
8) H. Miya et al., Nucl. Instr. Meth. B 317, 701 (2013).
9) H. Baba et al., RIKEN Acc. Prog. Rep. 43, 222 (2010).

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