Project 8 and Neutrino Mass Measurement at Penn State

The neutrino mass is one of the most important open questions in physics. The most sensitive direct searches for the neutrino mass rely on the beta decay method: beta decays emit an electron and a neutrino, and thanks to energy conservation, one can determine the mass of the neutrino from the shape of the electron spectrum near its endpoint, that is, the maximum energy of the emitted electrons. The Project 8 experiment has developed a novel technique called Cyclotron Radiation Emission Spectroscopy (CRES) to precisely measure the beta decay spectrum in tritium, and thus obtain a neutrino mass measurement with sensitivity surpassing that of existing experiments. An electron trapped in a uniform magnetic field will emit cyclotron radiation with frequency that depends on its kinetic energy, so that a measurement of the radiation provides a nondestructive electron energy measurement. The Project 8 collaboration has already demonstrated the viability of this technique using a small-scale (~10 cm3) prototype. However, an attempt at measuring the neutrino mass will require a vast increase in the number of tritium decays, which can be accomplished through an increase in detector volume to 10-100 m3. One crucial feature of such detector is the ability to identify single electrons in a large cavity instrumented with multi-channel antenna array, which will present unique challenges for the acquisition and reconstruction of signals. This project will develop the signal reconstruction techniques and electronics needed to take CRES to the next level, such as the use of digital beam-forming for single electron detection and tracking in large volumes. This research project will include the simulation of expected electron signal in software and hardware; building of test chambers instrumented with multiple prototype antennas and electronics; development of signal reconstruction algorithms; and the construction and operation of the Project 8 detector, with a focus on signal acquisition, electronics, and data analysis. The successful completion of this project will extend the functionality of the CRES technique to large scales, providing essential tools and support that will allow Project 8 to move into the next phases of its experimental program, and lead to the ultimate neutrino mass experiment.