The Gamma Spectroscopy Group at IFIC is devoted to the investigation of several aspects of the structure of atomic nuclei and the applications of Nuclear Physics to related fields.
Exotic nuclei far from stability provide an unparalleled testing ground for nuclear models and reveal how nuclear structure evolves under extreme conditions. We investigate doubly magic systems such as ¹⁰⁰Sn and ¹³²Sn, where shell closures for both protons and neutrons reinforce nuclear stability and allow clean tests of isospin symmetry. These studies also provide data relevant for understanding decay processes in astrophysical nucleosynthesis.
We also study neutron-deficient mercury isotopes, which exhibit shape coexistence—different nuclear shapes existing at similar energies. By comparing beta-decay strength distributions with nuclear radius measurements, we explore the interplay between nuclear shape and decay properties.
Our expertise in Total Absorption Gamma-ray Spectroscopy (TAGS) allows us to investigate beta strength in nuclei near the proton drip line, with implications for the rapid proton-capture process (rp-process) occurring in explosive astrophysical environments such as type-I X-ray bursts.
Beta decay is a powerful tool not only for nuclear structure and astrophysics, but also for probing the fundamental properties of the weak interaction and neutrinos. Nuclear reactors produce vast numbers of electron antineutrinos, which have been key to studying neutrino oscillations. However, differences between predicted and observed spectra—the so-called reactor antineutrino anomaly—have sparked debate about possible new physics, such as sterile neutrinos.
Our group has led the use of TAGS measurements to obtain precise beta-intensity distributions for the most important fission products contributing to reactor antineutrino fluxes. By combining these data through the summation method, we have reduced the predicted-vs-measured flux discrepancy from about 6% to roughly 2%, challenging the existence of the anomaly. We are now extending this program to measure beta spectra shapes of key isotopes, which could explain both the residual flux difference and the observed distortion around 6 MeV.
Accurate nuclear decay data are critical for predicting decay heat—the residual energy released after a reactor shuts down. Decay heat represents about 7% of reactor power during operation and nearly all the heat after shutdown, making it a key safety parameter for cooling system design and emergency planning. Our high-precision beta-decay measurements directly improve these predictions, with impact on reactor safety, fuel management, and accident analysis.