My research interests extend into two fields, both in experimental nuclear physics. For the first one, I study nuclear reactions that take place inside stars and - through different astrophysical processes - are responsible for the synthesis of all known elements. My second field of interest is focused on the structure of light nuclei, which are so neutron-rich that they are beyond the limits of existence.
The elements that we observe today on earth were all created inside stars through different types of nuclear reactions. Starting with hydrogen and helium, the light elements are produced by reaction cycles that burn the existing fuel and slowly build the heavier nuclei up to the region of iron. Above iron, most elements are created through two processes (s- and r-process), which involve neutron-induced reactions together with β-decays. There is also a small group of proton-rich nuclei, called “p-nuclei”, which cannot be created by these neutron-processes but rather by a different process called “p process”. There are several open questions governing the synthesis of the heavy elements. My work as an experimentalist is to study the nuclear reactions involved in these astrophysical processes. For this purpose, my group developed the SuN detector - a total absorption gamma-ray spectrometer that is used for measuring reaction rates and beta-decay properties involved in the nucleosynthesis and, in particular, related to the r- and p-processes.
At the same time, I’m also a member of the MoNA collaboration, which focuses on experiments to study extremely neutron-rich nuclei along the neutron drip line. These nuclei live for such a small time that no device can capture them to study their properties. In our experiments, we observe the products of their decay, which are a high-energy neutron and the remaining charged nucleus. From these products we can reconstruct the original exotic nucleus and study its structure. The Modular Neutron Array (MoNA) detects the emitted neutrons, providing information about their energy and position. This experimental setup has been used by the MoNA Collaboration to study the properties of nuclei along the neutron drip line with many exciting findings, such as new magic numbers and dineutron decays.
Different possible two-neutron decays. We observed a dineutron from the ground state of 16-Be, which was the first observation of such a decay. Figure credit T. Baumann.
Novel technique for constraining r-process (n,γ) reaction rates. A. Spyrou, et. al., Physical Review Letters 113 (2014) 232502
Measurement of the 58Ni(α,γ)62Zn reaction and its astrophysical impact. S. J. Quinn, A. Spyrou, et al., Physical Review C 89 (2014) 054611
Probing the production mechanism of the light p-nuclei. S.J. Quinn, A. Spyrou, A. Simon, et. al. Physical Review C Rapic Communication, 88 (2013) 011603
First Observation of Ground State Dineutron Decay: 16Be, A. Spyrou, Z. Kohley, et al., Physical Review Letters 108 (2012) 102501
Nuclear structure experiments along the neutron drip line, T. Baumann, A. Spyrou, M. Thoennessen, Reports on Progress in Physcis, 75 (2012) 036301