Speaker
Description
Radiation tolerance of commercial SFP+ transceivers (SFP-10GSR-85, FS) was evaluated for detector readout in high-energy physics experiments. Total Ionizing Dose (TID), Non-Ionizing Energy Loss (NIEL), and Single Event Effects (SEE) tests were performed using gamma rays, neutrons, and high-energy hadrons, respectively. No significant degradation was observed up to 64 Gy, 2.0×10$^{13}$ n/cm$^2$, and 2.7×10$^{11}$ HEH/cm$^2$. Sudden increases in bit error rate (BER) and temporary link losses were observed during irradiation but were recoverable by power cycling or resetting communication. These results demonstrate the feasibility of using COTS SFP+ transceivers in high-radiation environments.
Summary (500 words)
Optical transceivers play a critical role in data acquisition systems in high-energy physics experiments. When installed close to the detector, they are exposed to harsh radiation environments. Both cumulative and single-event radiation effects can significantly impact link reliability. Commercial Off-The-Shelf (COTS) components are attractive due to their availability and performance, but their radiation tolerance must be evaluated. Following a comparative evaluation of commercial SFP+ transceivers, FS SFP-10GSR-85 modules were selected for use in the Thin Gap Chamber (TGC) readout system of the ATLAS experiment at the High-Luminosity (HL)-LHC. Final radiation tolerance tests were performed on modules from the same production series intended for deployment.
Radiation tolerance was evaluated in terms of Total Ionizing Dose (TID), Non-Ionizing Energy Loss (NIEL), and Single Event Effects (SEE). The requirements are specified by absorbed dose, 1 MeV neutron equivalent fluence, and the flux of hadrons with kinetic energy above 20 MeV. The Radiation Tolerance Criteria (RTC) for TGC are 11 Gy, 4.3×10^11 n/cm^2, and 1.3×10^11 HEH/cm^2, including safety factors. Performance was evaluated by measuring optical output power and bit error rate (BER) during loopback transmission.
The TID test was performed at the Cobalt-60 facility of Nagoya University. No significant degradation was observed up to a total dose of 64 Gy (Fig. 1), exceeding the RTC. At 83 Gy, transmitter damage was observed in 7 of 30 modules. At 100 Gy, all modules showed damage in both transmitters and receivers. However, all modules recovered within three months at room temperature without power.
The NIEL test was performed using the Tandem Accelerator at Kobe University on four modules. No significant degradation was observed up to a neutron fluence of 2.0×10^13 n/cm^2, exceeding the RTC. At 1.5×10^13 n/cm^2, the BER increased sharply above 10^-3, and the communication link was lost. Normal operation was restored after power cycling.
The SEE test was performed at the CHARM facility of CERN. Up to 3.6 × 10^11 HEH/cm^2, two types of SEE with sudden increases in BER were observed in 10 modules. Five events with BER < 10^-3 and four with BER > 10^-3 were recorded; in both cases, the communication link was lost. Recovery was achieved by communication reset for the former and by power cycling for the latter. No significant degradation was observed up to 57 Gy, 8.2×10^11 n/cm^2, and 2.7×10^11 HEH/cm^2, exceeding the RTC. At higher levels (78 Gy, 1.1×10^12 n/cm^2, and 3.6×10^11 HEH/cm^2), damage was observed; however, no SEE-induced failure was observed, and the damage is likely due to TID effects based on the previous TID test.
To conclude, radiation tolerance evaluation of commercial SFP+ transceivers from FS was performed, covering TID, NIEL, and SEE effects. The modules exhibited stable operation within the tested ranges, with degradation primarily attributed to TID. Transient effects leading to link loss were observed, but normal operation was recovered through power cycling or communication reset. These results indicate that commercial SFP+ transceivers are promising candidates for use in high-radiation environments in high-energy physics experiments.