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Progress on the BL2 beam measurement of the neutron lifetime



Shannon M. Hoogerheide, Jimmy P. Caylor, Evan R. Adamek, Eamon S. Anderson, Ripan Biswas, B. E. Crawford, Christina DeAngelis, Maynard S. Dewey, N Fomin, David M. Gilliam, Kyle Grammer, G L. Greene, Robert W. Haun, Jonathan Mulholland, Hans Pieter Mumm, Jeffrey S. Nico, William M. Snow, F E. Wietfeldt, Andrew Yue


A precise value of the neutron lifetime is important in several areas of physics, including determinations of the quark-mixing matrix element |Vud|, related tests of the Standard Model, and predictions of light element abundances in Big Bang Nucleosynthesis models. We report the progress on a new measurement of the neutron lifetime utilizing the cold neutron beam technique. Several experimental improvements in both neutron and proton counting that have been developed over the last decade are presented. This new effort should yield a final uncertainty on the lifetime of 1 s with an improved understanding of the systematic effects.
EPJ Web of Conferences


neutron lifetime, cold neutrons, weak interactions, fundamental symmetries


Hoogerheide, S. , Caylor, J. , Adamek, E. , Anderson, E. , Biswas, R. , Crawford, B. , DeAngelis, C. , Dewey, M. , Fomin, N. , Gilliam, D. , Grammer, K. , Greene, G. , Haun, R. , Mulholland, J. , , H. , Nico, J. , Snow, W. , Wietfeldt, F. and Yue, A. (2021), Progress on the BL2 beam measurement of the neutron lifetime, EPJ Web of Conferences, [online],, (Accessed May 27, 2024)


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Created April 17, 2021, Updated May 3, 2021