MRI Consortium: Development of an Array of Germanium Detectors for COHERENT at the Spallation Neutron Source

Duke University, Durham NC

Investigators

Abstract

One of the major intellectual achievements of the 20th century was the development of the Standard Model (SM) of particle physics. This model succeeded in classifying all of the elementary particles known at the time into a hierarchy of groups having similar quantum properties. The validity of this model to date was confirmed by the discovery of the Higgs boson at the Large Hadron Collider at CERN. However, the Standard Model as it currently exists leaves open many questions about the universe, including such fundamental questions as to why the Higgs mass has the value it has and why there is no antimatter in the universe. One of the primary areas to search for answers to these and other open questions about the universe, how it came to be, and why it is the way it is, is to focus on a study of the properties of neutrinos and to use what we know and can learn about neutrinos as probes of science Beyond the Standard Model (BSM). The Standard Model predicted that there were three different kinds of neutrinos, all massless, that were distinguishable through the different interactions that they undergo whenever they interact with matter. But recent measurements have totally changed our picture of neutrinos. We now know that neutrinos do have a mass and because they do, they can actually change from one type to another. Additionally, experimental measurements have indicated the possibility of yet an additional type of sterile neutrino. Detailed measurements of the interactions of these unusual particles are one of the most promising ways to probe for new physics beyond the Standard Model. This project is led by group members of the COHERENT collaboration that has been the first to observe Coherent elastic neutrino-nucleus scattering. The reaction was predicted in the early 1970s and has now been observed nearly a half century later, given the advances in highly-sensitive, low-noise instrumentation and very high beam fluxes, for example at the Oak Ridge National Laboratory Spallation Neutron Source facility. To understand the nature of this process, a range of nuclear targets must be studied, as the cross section for the scattering scales approximately with the square of the number of neutrons in the target nuclei. Through this MRI award, the group from Duke, North Carolina State and North Carolina Central Universities will build and then operate a Germanium (Ge) detector for which the neutron dependence of the cross section can be verified. Germanium is a natural choice for such a measurement given the excellent energy sensitivity afforded by this material. In the broader context, the Ge instrumentation to be developed here has the potential for applications in nuclear reactor monitoring. And the instrumentation development will provide extensive experience for post docs and students in the technically challenging research techniques of low-energy recoil measurements. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.