Improved neutron lifetime measurement with UCN$\tau$

F. M. Gonzalez; E. M. Fries; C. Cude-Woods; T. Bailey; M. Blatnik; L. J. Broussard; N. B. Callahan; J. H. Choi; S. M. Clayton; S. A. Currie; M. Dawid; E. B. Dees; B. W. Filippone; W. Fox; P. Geltenbort; E. George; L. Hayen; K. P. Hickerson; M. A. Hoffbauer; K. 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, Jr.; J. Ramsey; D. J. Salvat; A. Saunders; E. I. Sharapov; S. Slutsky; V. Su; X. Sun; C. Swank; Z. Tang; W. Uhrich; J. Vanderwerp; P. Walstrom; Z. Wang; W. Wei; A. R. Young

doi:10.1103/physrevlett.127.162501

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arXiv · 2106.10375

Improved neutron lifetime measurement with UCN$\tau$

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Abstract

We report an improved measurement of the free neutron lifetime $\tau_{n}$ using the UCN$\tau$ apparatus at the Los Alamos Neutron Science Center. We counted a total of approximately $38\times10^{6}$ surviving ultracold neutrons (UCN) after storing in UCN$\tau$'s magneto-gravitational trap over two data acquisition campaigns in 2017 and 2018. We extract $\tau_{n}$ from three blinded, independent analyses by both pairing long and short storage-time runs to find a set of replicate $\tau_{n}$ measurements and by performing a global likelihood fit to all data while self-consistently incorporating the $\beta$-decay lifetime. Both techniques achieve consistent results and find a value $\tau_{n}=877.75\pm0.28_{\text{ stat}}+0.22/-0.16_{\text{ syst}}$~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.

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F. M. Gonzalez, E. M. Fries, C. Cude-Woods, T. Bailey, M. Blatnik, L. J. Broussard, N. B. Callahan, J. H. Choi, S. M. Clayton, S. A. Currie, M. Dawid, E. B. Dees, B. W. Filippone, W. Fox, P. Geltenbort, E. George, L. Hayen, K. P. Hickerson, M. A. Hoffbauer, K. 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, Jr., J. Ramsey, D. J. Salvat, A. Saunders, E. I. Sharapov, S. Slutsky, V. Su, X. Sun, C. Swank, Z. Tang, W. Uhrich, J. Vanderwerp, P. Walstrom, Z. Wang, W. Wei, A. R. Young. 2021-06-18. Improved neutron lifetime measurement with UCN$\tau$. https://doi.org/10.1103/physrevlett.127.162501

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