August 16, 2023
BLOOMINGTON, Ind. -- Sepehr Samiei has won a fellowship from the German DAAD program for scientific work at the FRM research reactor near Munich, Germany for three months in early 2024. Sepehr will collaborate with FRM scientist Earl Babcock to conduct precision NMR spectroscopy and neutron transmission experiments on spin-exchange optically-pumped polarized 3He to determine for the first time the J=1 component of the neutron-3He cross section. The measurement of this reaction channel will provide new information to help determine the spin-dependent component of the poorly-constrained nucleon three-body force, which is now understood to be responsible for about 5% of the binding energy of stable nuclei. It will also enable a greatly-improved measurement of the spin-dependent component of the n-3He scattering length, also of interest for three nucleon physics. Sepehr led a recent measurement of neutron birefringence in 3He on the neutron spin echo spectrometer at the Spallation Neutron Source at Oak Ridge, where he worked with instrument scientist and former IU postdoc Piotr Zolnierczuk.