The idea of non-destructive elemental composition analysis is reviewed. The term non-destructive has many definitions in many different fields, as well as different definitions within a single field. The definition of non-destructive is discussed for several different fields: archeology, paleontology, forensics, space science, geochemistry. Activation analysis techniques, claimed to be used non-destructively in many fields, are used as a lens to provide a unique perspective on what non-destructive means. A list of criteria was created to create a broad, general definition of non-destructive. Finally, photon activation analysis is discussed as a potential non-destructive technique for bulk elemental composition analysis of large samples.

The CNO cycle is the main energy source in massive stars during their hydrogen burning phase, and, for our sun, it contributes at the $\approx 1\%$ level. As the ${}^{14}\mathrm{N}(p,\gamma ){}^{15}\mathrm{O}$ reaction is the slowest in the cycle, it determines the CNO energy production rate and thus the CNO contribution to the solar neutrino flux. These CNO neutrinos are produced primarily from the $\beta$ decay of ${}^{15}\mathrm{O}$ and, to a lesser extent, from the decay of ${}^{13}\mathrm{N}$. Solar CNO neutrinos are challenging to detect, but they can provide independent new information on the metallicity of the solar core. Recently, CNO neutrinos from ${}^{15}\mathrm{O}$ have been identified for the first time with the Borexino neutrino detector at the INFN Gran Sasso underground laboratory. There are, however, still some considerable uncertainties in the ${}^{14}\mathrm{N}(p,\gamma ){}^{15}\mathrm{O}$ reaction rate under solar temperature conditions. The low energy reaction data presented here, measured at the CASPAR underground accelerator, aim at connecting existing measurements at higher energies and attempts to shed light on the discrepancies between the various data sets, while moving towards a better understanding of the ${}^{14}\mathrm{N}(p,\gamma ){}^{15}\mathrm{O}$ reaction cross section. The present measurements span proton energies between 0.27 and 1.07 MeV, closing a critical gap in the existing data. A multichannel $R$-matrix analysis was performed with the entire new and existing data sets and is used to extrapolate the astrophysical $S$ factors of the ground state and the 6.79 MeV transition to low energies. The extrapolations are found to be in agreement with previous work, but find that the discrepancies between measured data and $R$-matrix fits, both past and present, still exist. We examine the possible reasons for these discrepancies and thereby provide recommendations for future studies.

The primordial elemental abundance composition of the first stars leads to questions about their modes of energy production and nucleosynthesis. The formation of ${}^{12}\mathrm{C}$ has been thought to occur primarily through the $3\alpha$ process, however, alternative reaction chains may contribute significantly, such as ${}^7\mathrm{Li}(\alpha ,\gamma ){}^{11}\mathrm{B}(\alpha ,n){}^{14}\mathrm{N}$. This reaction sequence cannot only bypass the mass $A=8$ stability gap, but could also be a source of neutrons in the first star environment. However, the efficiency of this reaction chain depends on the possible enhancement of its low energy cross section by $\alpha$-cluster resonances near the reaction threshold. A new study of the reaction ${}^{11}\mathrm{B}(\alpha ,n)$ ${}^{14}\mathrm{N}$ has been undertaken at the CASPAR underground facility at beam energies from $300\text{–}700\mathrm{keV}$. A $4\pi$ neutron detector in combination with pulse shape discrimination at low background conditions resulted in the ability to probe energies lower than previously measured. Resonance strengths were determined for both the resonance at a laboratory energy of $411\mathrm{keV}$, which was measured for the second time, and for a new resonance at $337\mathrm{keV}$ that has been measured for the first time. This resonance, found to be significantly weaker than previous estimates, dominates the reaction rate at lower temperatures ($T<0.2\mathrm{KG}$) and reduces the reaction rate in first star environments.