Inelastic Neutrino-Nucleus Scattering Research by NCCU at ORNL
Dr. Diane Markoff1, Professor
Co-PI(s): Dr. R.J. Newby2, Dr. P.S. Barbeau3
1: North Carolina Central University, Durham, NC, 27707
2: Oak Ridge National Laboratory, Oak Ridge, TN, 37830
3: Duke University, Durham, NC, 27708
This proposal supports the inelastic neutrino-nucleus scattering (INNS) program being carried out by the North Carolina Central University (NCCU) Neutrino Group at the Spallation Neutron Source (SNS) located at Oak Ridge National Laboratory (ORNL). NCCU is a public, liberal arts, masters' granting, Historically Black University (HBCU). PI Markoff (NCCU), Co-I Barbeau (Duke University) and ORNL partner Co-I Newby are COHERENT collaborators engaged with a suite of detectors measuring neutrino interactions.
The COHERENT collaboration recently published measurements of INNS in lead (208Pb) and iodine (127I) that were lower than expected by calculations. The initial interest of the collaboration results from this inelastic interaction being a source of background neutrons that can interfere with low-energy recoil measurements of elastic neutrino scattering. This grant funds a systematic program of improved measurements in different target configurations to check the initial results and explore the discrepancy with theoretical models to determine whether the trend of low reaction rates exists in other nuclei.
What started as a study of background interactions has become a significant question for understanding the underlying cause for calculations to over predict the interaction rate. The lead result is about 30% of the predicted value while the iodine result is about 40% of predictions. Lower than expected values questions the model basis for the calculations. These low-energy INNS measurements provide a means to probe the models' capability to predict nonzero momentum transfer reactions with implications for calculations of neutrino-less double beta decay matrix elements and interpretation of the experimental results. Neutrino scattering in the SNS energy range provides information about astrophysical neutrinos from supernovae. Additional impacts include reduced expected signal rates for the Helium and Lead Observatory for Supernova Neutrinos (HALO) based on neutrino scattering on lead.
The objectives of the experimental program are to measure the INNS cross sections on lead in a different configuration and on other targets with similar atomic number. INNS scattering on 127I will be measured in a multi-ton array of NaI crystals. Target systems being considered are Pb-glass blocks, BGO (bismuth-germanium-oxide) crystals and a `metal sandwich' consisting of alternating layers of scintillating detector material and target metals, for example, Fe, Pb, Cu, Al. The prototypes and detectors will be deployed at the Spallation Neutron Source at ORNL in which neutrinos are produced in the spallation process providing a strong source of pulsed neutrinos.
NCCU MS and BS degree students will be involved in the design, testing, construction and deployment of the prototype detectors and the systems developed for production data, including simulations and analysis. The grant supports NCCU students to be at ORNL during the summer and semester breaks, and for DOE scientist to visit NCCU, providing interactive exposure to DOE opportunities.
