EAGER: The Development of Axion Software for CUORE

University Of South Carolina At Columbia, Columbia SC

Investigators

Abstract

Multiple astronomical observations have established that about 85% of the matter in the universe is not made of known elementary particles. Deciphering the nature of this so-called Dark Matter is of fundamental importance to cosmology, astrophysics, and high-energy particle physics. One of the most exciting quests is the search for new particles beyond the Standard Model of Particle Physics, which describes all the known elementary particles and the interactions between them. Extensions of the model predict not only new particles with large masses but also some with very small masses. Such a candidate for the latter is the axion, which has been introduced to explain the smallness of the violation of the Charge-Parity (CP) symmetry in Quantum Chromodynamics, the theory describing the action of the strong force, for example, the interactions between protons and neutrons that make up atomic nuclei. The axion turns out to also be a prime candidate for a constituent of the dark matter in the universe. The conclusion that the strong CP problem is solved must await the experimental discovery of the axion. This award will provide funds to search for axions that are produced in the solar core by the decay of a particular excited nucleus (iron). The discovery of the axion could explain a number of phenomena in cosmology. This award will also provide a stimulating environment for an experienced graduate student to work on a very challenging software project involving state of the art data from a particle astrophysics experiment. This award will involve a technique to search for axions that are produced by the ground-state decay of a Fe-57 nucleus thermally excited to the 14.4-keV, 3/2+ state. This deexcitation is an M1 nuclear ground state transition. Theoretically, nuclear M1 transitions have a weak axion branch. This work involves developing sophisticated software to search the data from the CUORE detector for the modulations characteristic of the periodic behavior consistent with the known Bragg condition patterns associated with the known position of the sun at every instant of every day. The CUORE detector is an array of 988 aligned TeO2 single crystal bolometers operated in Laboratori Nazionale del Gran Sasso (LNGS) in Assergi, Italy. A major challenge is to evaluate the uncertainties in the orientation of every crystal in the array, and to evaluate its impact on conclusions drawn from the analysis. These uncertainties must be incorporated into the data analysis to be sure that if there are axions from the sun satisfying the Bragg conditions, the experiment is sensitive to them, and, most importantly, that the analysis does not create generate a false signal.