Fig. 13

TOFPET2 performance of a detector block consisting of a \(4\times 4\) Broadcom NUV-MT SiPM arrays one-to-one coupled to a \(4\times 4\) LYSO:Ce,Ca crystal matrix in comparison with exposing the SiPMs to laser pulses (406 nm) of an SiPM array. The performance with default configuration and DC readout can be optimized (1), (2), while laser pulses reveal timing limitations of the front end (3). Reducing the applied bias leads to a better intrinsic resolution (4), which is why baseline shifts are thought to be the cause of the problem. Pulse amplification and discrimination via a TLV3801, i.e., 16-channel HF electronics, are employed (5), delivering the same intrinsic timing resolution at higher overvoltages. Switching back to a full detector block with a scintillator, the performance is still limited by a high TLV threshold, which is needed due to unstable baselines at lower thresholds. (6). Adapting signal filters in the timing and energy signal paths reduces this noise and improve the CTR to DC level (7), which shows that the adapted HF readout board does not worsen the CTR and, hence, could be a good candidate for readout with the picoTDC