Speaker
Description
Advancements in low-cost FPGA-integrated digitizers are reshaping timing techniques in nuclear spectroscopy, enabling compact digital solutions for coincidence measurements. In this work, we present a fully digital time-differential perturbed angular correlation (TDPAC) spectrometer based on a commercial CAEN DT5730S digitizer (8 channels, 14-bit ADC, 500 MS/s) combined with PACIFIC², an in-house Python framework for flexible online and offline γ–γ coincidence analysis. [1]
The system allows efficient processing of list-mode data and reconstruction of coincidence spectra in multi-detector configurations. Experimental validation was performed using metallic indium and layered perovskite samples probed with $^{111}$In and $^{111m}$Cd isotopes. The results demonstrate reliable real-time acquisition and processing of γ–γ coincidence events.
Time resolution optimization was investigated using 511–511 keV γ–γ coincidences from positron–electron annihilation in a $^{22}$Na source, detected with LaBr$_3$:Ce scintillators coupled to Hamamatsu R2083 photomultiplier tubes. After optimization of the digitizer's digital constant fraction discriminator parameters, a coincidence time resolution of approximately 450 ps FWHM was achieved with the 500 MS/s digitizer. [1]
The PACIFIC² framework also enables flexible coincidence analysis strategies, including ongoing developments aimed at evaluating γ₁–γ₂ correlations detected within the same detector channel, which may further extend the applicability of digital timing methods.
These results demonstrate that compact multi-channel digitizers combined with modern data-analysis frameworks provide an accessible and versatile platform for timing-based nuclear spectroscopy and hyperfine interaction studies.
Acknowledgments:
This work was supported by the Portuguese Foundation for Science and Technology (FCT) under projects UIDB/04968/2025, UIDP/04968/2025, LA/P/0095/2020, and CEECIND-2023.07340.CEECIND/CP2833/CT0006.
References:
[1] Rocha-Rodrigues et al., NIM A 1087 (2026) 171440, https://doi.org/10.1016/j.nima.2026.171440