Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Performance of a new operating system by FELIX board for INTT insPHENIX
G. Nukazuka,∗1 Y. Akiba,∗1 J. Bertaux,∗2 K. Fujiki,∗1,∗3 M. Fujiiwara,∗4 T. Hachiya,∗1,∗4 S. Hasegawa,∗1,∗5M. Hata,∗4 H. Imai,∗1,∗3 M. Kano,∗4 T. Kato,∗1,∗3 T. Kondo,∗6 C. M. Kuo,∗7 R. S. Lu,∗8 I. Nakagawa,∗1Y. Namimoto,∗1,∗4 R. Nouicer,∗9 C. W. Shih,∗7 M. Shimomura,∗4 R. Shishikura,∗1,∗3 M. Stojanovic,∗2Y. Sugiyama,∗4 R. Takahama,∗1,∗4 W. C. Tang,∗7 H. Tsujibata,∗4 M. Watanabe,∗4 and X. Wei∗2sPHENIX is scheduled to start operationsn at theRelativistic Heavy Ion Collider at Brookhaven NationalLaboratory in 2023 to study quark-gluon plasma andcold-QCD.1) The Intermediate Tracker (INTT) is a silicon barrel tracker located between the other two tracking detectors of the sPHENIX detector complex. INTT
is responsible for tracking and jet ﬂavor tagging withhigh precision and low background. It inherits muchof the electronics, such as the readout card (ROC),
from the FVTX detector2) in the PHENIX experiment to signiﬁcantly reduce development time and cost.
FVTX is controlled by slow control commands from theVME modules, Front-End Module (FEM), and FEM
Interface Board (FEM-IB), and data from the detector
was initially processed by FEM and recorded by DataCollecting Module-II (DCM-II) and other equipment(Fig. 1).
The original slow control
and readout system(same as PHENIX FVTX)FPGASlowControl
Datafrom/toINTT ladders

FEMInterfaceBoardLAN Cable

VME busFPGAFrontEndModuleThe new slow control
and readout system(Felix system)

FPGA

from/to
INTT ladders

Optical Fiber DCM-II

LAN Cable

SlowControlDataPC

FelixFPGA boardPC

was hired and optimized for each detector. INTT has
almost completed the migration to the new system with
Felix (Fig. 1), although the initial plan was to assume
control of the FEM/FEN-IB system from FVTX.
To evaluate the performance of the Felix system,measurements of pulses generated by the ROC, referred
to as calibration, were performed. The chips received
pulses with various amplitude and performed analog-todigital conversion. Further, caliblation provides the correlation between analog amplitude and digitized value.
Another crucial performance evaluated from calibration is the number of the chip responses, which canbe predicted, as the readout system must receive signals from the chip under many restrictions such as timing. Figure 2 shows the channel distribution of a readout chip, comprising 128 channels, from the calibration performed with the FEM/FEM-IB or Felix systems. Both measurements yielded consistent results.
The slight diﬀerences are owing to ﬂuctuations aroundthe thresholds. Calibration with the Felix system wascontinuously performed to conﬁrm good stability. The
diﬀerence in the number of data from the expectation
was no more than 0.1% provided as the data in the lowamplitude noisy region were excluded. The INTT operation with Felix was conﬁrmed stable and consistent
with the FEM/FEM-IB system.

Event Buffer,
Data Compressor,…, to Computing Center

Channel Distribution

350300
Entries

As part of the transition from PHENIX to sPHENIX,
all tracking detectors including INTT adopted a
streaming readout (data readout without triggering).
The streaming readout can collect two to three ordersof magnitude more data than calorimeter triggers andeliminate trigger bias.1) To enable streaming readout,the Felix board3) used in ATLAS experiment at CERN
∗2∗3∗4∗5∗6∗7∗8∗9FELIX

400

Fig. 1. Schema of the INTT operating system using theFEM/FEM-IB (top) or the Felix board (bottom).

∗1FEM

450

RIKEN Nishina Center
Department of Physics and Astronomy, Purdue University
Department of Physics, Rikkyo University
Department of Mathematical and Physical Sciences, Nara
Women’s University
Japan Atomic Energy Agency
Tokyo Metropolitan Industrial Technology Research InstituteDepartment of Physics, National Central University
Department of Physics, National Taiwan University
Physics Department, Brookhaven National Laboratory

2502001501005000204060

Channel80100120Fig. 2. Comparison of the channel distribution of a readoutchip using the FEM (black) or the Felix (red) system.

References
1) sPHENIX collaboration, sPHENX Beam Use Proposal(2020).
2) C. Aidala et al., Nucl. Instrum. Methods Phys. Res. A755, 44 (2014).
3) J. Anderson, et al. (ATLAS Collaboration), J. Phys.
Conf. Ser. 664, 082050 (2015).

- 115 -