Improved Neutron Lifetime Measurement with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>UCN</mml:mi><mml:mi>τ</mml:mi></mml:mrow></mml:math>
Francisco M. González, E. M. Fries, C. Cude-Woods, Thomas L. Bailey, M. Blatnik, L. J. Broussard, Nathan Callahan, J. H. Choi, Steven Clayton, S. Currie, Maria Dawid, Eric Dees, B. W. Filippone, W. Fox, P. Geltenbort, E. M. George, L. Hayen, K. P. Hickerson, Mark A. Hoffbauer, Keenan Hoffman, A. T. Holley, T. M. Ito, A. Komives, C.-Y. Liu, M. Makela, C. L. Morris, R. Musedinovic, C. O’Shaughnessy, R. W. Pattie, J. Ramsey, D. J. Salvat, A. Saunders, E. I. Sharapov, S. Slutsky, Vin‐Cent Su, X. Sun, Christopher Swank, Z. Tang, W. Uhrich, J. Vanderwerp, P. L. Walstrom, Zhehui Wang, W. Wei, A. R. Young
Abstract
We report an improved measurement of the free neutron lifetime τ_{n} using the UCNτ apparatus at the Los Alamos Neutron Science Center. We count a total of approximately 38×10^{6} surviving ultracold neutrons (UCNs) after storing in UCNτ's magnetogravitational trap over two data acquisition campaigns in 2017 and 2018. We extract τ_{n} from three blinded, independent analyses by both pairing long and short storage time runs to find a set of replicate τ_{n} measurements and by performing a global likelihood fit to all data while self-consistently incorporating the β-decay lifetime. Both techniques achieve consistent results and find a value τ_{n}=877.75±0.28_{stat}+0.22/-0.16_{syst} s. With this sensitivity, neutron lifetime experiments now directly address the impact of recent refinements in our understanding of the standard model for neutron decay.