Testing Radiopure Cables for nEXO*

The subject of neutrinos has been a tricky one for physicists for decades. The discovery that they contain mass and can alter between different states leads to potential physics phenomena beyond the well established Standard Model. One possibility that can explain this behavior would be that neutrinos are Majorana particles, which means they can act as their own antiparticles and perform interactions that violate lepton number conservation. An effective way to ascertain whether they are Majorana particles would be searching for a process called neutrinoless double beta decay (0νββ). This decay mode includes two simultaneous beta decays in a nucleus. If neutrinos are Majorana particles, they can mutually annihilate resulting in the absence of any escaping neutrinos. nEXO is a 5 ton liquid xenon (LXe) Time Projection Chamber (TPC) that operates at cryogenic temperatures, proposed to search for 0νββ. Brookhaven National Laboratory is responsible for the photon readout electronics.  The detector is highly sensitive and measurement of 0νββ is on the order of keV. Consequently, the signal would be overwhelmed by any residual radioactive decay within the system. As a result, the  hardware is required to be as radiopure as possible. Hence, testing the performance of radiopure cables that will be part of the nEXO TPC is a high priority.  Furthermore, it will be important to test interconnections from the radiopure cables to prototype nEXO photon readout boards.