Improved electronics for BeEST sterile neutrino search

In a search for ôBeyond the Standard Modelö (BSM) physics, the BeEST experiment is searching for massive sterile neutrinos in the sub-MeV range by measuring the decay of 7Be to 7Li by electron capture in from 7Be ions implanted in Ta Superconducting Tunnel Junctions (STJs). Conservation of momentum allows the neutrino mass to be deduced from the 7Li ion's recoil energy which is less than 150eV. STJ detectors can measure energy with an accuracy of 1-2eV, provided that they have suitable electronics. Existing electronics not only lack the data collection features required of a modern Nuclear Physics Data Acquisition (DAQ) system but can no longer be manufactured due to parts obsolescence. As the manufacturers of the original STJ electronics, we are members of the BeEST DAQ team and have analyzed the requirements of next-generation STJ array electronics. These consist primarily of reducing noise levels, preferably by a factor of 10 or more, and producing DAQ electronics that have trace capture and coincidence timing features. We will approach this problem by first redesigning the preamplifier to use new parts to achieve both better energy resolution and lower power and then apply our experience building standard NP DAQ systems to design and construct a system specifically tailored to the specific requirements of STJ detectors. In Phase I we will primarily focus on the issues associated with improving energy resolution. In the preamplifier this will entail identifying and removing issues that are are limiting the current design. In the DAQ electronics this will primarily entail identifying the optimum bandwidth and sampling rate of the input analog to digital converter. In preparation for Phase II, we will work with the whole BeEST team to produce a DAQ design document that includes all the features required to make the experiment as sensitive as possible to the sought-after neutrinos. The most important benefit of a successful project will be the availability of a new measurement tool for Nuclear Physics, since STJ Array detectors are excellent at accurately measuring all types of nuclear reaction product at very low energies, as the SALER instrument will demonstrate at FRIB. As BeEST is demonstrating, these detectors also enable cutting edge science by small research groups, which will create improved R&D opportunities in the nuclear sciences and allow universities to train the next generation of Nuclear Physicists in quantum measurement techniques. Finally, instrument sales will enhance our local economy and improve the nation's balance of trade through overseas sales.