The PTOLEMY project aims to develop a scalable design for a Cosmic Neutrino Background (CNB) detector, the first of its kind and the only one conceived that can look directly at the image of the Universe encoded in neutrino background produced in the first second after the Big Bang. The scope of the work for the next three years is to complete the conceptual design of this detector and to validate with direct measurements that the nonneutrino backgrounds are below the expected cosmological signal. In this paper we discuss in details the theoretical aspects of the experiment and its physics goals. In particular, we mainly address three issues. First we discuss the sensitivity of PTOLEMY to the standard neutrino mass scale. We then study the perspectives of the experiment to detect the CNB via neutrino capture on tritium as a function of the neutrino mass scale and the energy resolution of the apparatus. Finally, we consider an extra sterile neutrino with mass in the eV range, coupled to the active states via oscillations, which has been advocated in view of neutrino oscillation anomalies. This extra state would contribute to the tritium decay spectrum, and its properties, mass and mixing angle, could be studied by analyzing the features in the beta decay electron spectrum.

Mercury (Hg) speciation by thermo-desorption is considered an alternative to laborious sequential chemical procedures; hence its popularity has increased in the last years. In this work, steps were taken to improve the information obtained by Hg speciation through thermo-desorption, specifically to improve peak resolution and increase the number of species that can be identified. The thermo-desorption behavior of Hg bound to iron oxides was characterized, as well as a new Hg-humic acid synthetic standard material. In contrast to previous studies, the peak corresponding to the Hg fraction associated with humic acids was clearly separated from the mineral fraction, and identified in some natural samples. With increasing temperature, Hg species are released in the following order: HgCl 2 = Hg associated with Fe 2 O 3 b Hg associated with humic acids b HgS b HgO, with an overlap of HgCl 2 and Hg associated with iron oxides. An evaluation of the effects of sample pre-treatment and storage on Hg speciation was also performed. It was found that sieving to b2 mm improved the sample homogeneity. The importance of fast sample analysis was highlighted, given that after 10 days of storage at room temperature, volatile Hg 0 could no longer be identified in the sample. The suitability of thermo-desorption for mercury speciation in soils and sediments is discussed.

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