Physics Commons^™

First Observation Of P-Odd Γ Asymmetry In Polarized Neutron Capture On Hydrogen, D. Blyth, J. Fry, N. Fomin, R. Alarcon, L. Alonzi, E. Askanazi, S. Baeßler, S. Balascuta, L. Barrón-Palos, A. Barzilov, J. D. Bowman, N. Birge, J. R. Calarco, T. E. Chupp, V. Cianciolo, C. E. Coppola, Chrisopher B. Crawford, K. Craycraft, D. Evans, C. Fieseler, E. Frlež, I. Garishvili, M. T. W. Gericke, R. C. Gillis, K. B. Grammer, G. L. Greene, J. Hall, J. Hamblen, C. Hayes, E. B. Iverson, Md Latiful Kabir, Mark Mccrea, R. Milburn, F. Simmons, Aaron P. Sprow, E. Tang

Physics and Astronomy Faculty Publications

We report the first observation of the parity-violating gamma-ray asymmetry A^np_γ in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the Spallation Neutron Source at Oak Ridge National Laboratory. A^np_γ isolates the ΔI = 1, ³S₁ → ³P₁ component of the weak nucleon-nucleon interaction, which is dominated by pion exchange and can be directly related to a single coupling constant in either the DDH meson exchange model or pionless effective field theory. We measured A^np_γ = [−3.0 ± 1.4(stat )± 0.2(syst)] × 10^{−8 …}