May 29, 2018 to June 3, 2018
Hyatt Regency Indian Wells Conference Center
US/Pacific timezone

Measurement of the Neutron Lifetime Using a Magneto-Gravitational Trap

May 30, 2018, 4:10 PM
North Foyer | Kachina Room (Hyatt Regency Indian Wells Conference Center)

North Foyer | Kachina Room

Hyatt Regency Indian Wells Conference Center

44600 Indian Wells Lane, Indian Wells, CA 92210, USA


Mr Nathan Callahan (Indiana Univeristy)


Precision measurements of the free neutron lifetime $\tau_n$, when combined with measurements of the axial vector coupling, can be used to test unitarity of the CKM matrix. Nonunitarity is a signal for physics Beyond the Standard Model (BSM). Sensitivity to BSM physics requires measurements of $\tau_n$ to a precision of 0.1 s. However, the two dominant techniques to measure $\tau_n$ (colloquially beam and bottle measurements) disagree by nearly 10 s. UCN$\tau$ is a neutron lifetime experiment using a magneto-gravitational trap and an $\textit{in-situ}$ neutron detector. Neutrons in this trap are not susceptible to loss on material walls as in previous bottle measurements. Additionally, the $\textit{in-situ}$ detector allows spectral monitoring of the trapped Ultracold Neutrons. In this talk, I will present our most recent result $\tau_n=877.7\pm0.7_\mathrm{(stat.)}+0.4/-0.2_\mathrm{(sys.)}$. I will also present Monte Carlo simulations of systematic effects in the experiment.
E-mail [email protected]
Collaboration name UCNtau

Primary author

Mr Nathan Callahan (Indiana Univeristy)

Presentation materials