Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session C14: Mini-Symposium:The Neutron Lifetime Anomaly - current status
1:30 PM–3:06 PM,
Saturday, April 13, 2019
Sheraton
Room: Plaza Court 3
Sponsoring
Unit:
DNP
Chair: Nadia Fomin, University of Tennessee
Abstract: C14.00006 : Measurement of systematic effects in the UCN$\tau$ experiment
2:54 PM–3:06 PM
Presenter:
Eric M Fries
(Caltech)
Author:
Eric M Fries
(Caltech)
One of the most important open questions about the fundamental properties of the neutron is the free neutron lifetime $(\tau_n).$ Experimental measures of $\tau_n$ can be broadly described in one of two ways: either a measurement using a cold neutron beam, or a measurement using ultracold neutrons (UCN) stored in a trap. There is a $\sim4\sigma$ discrepancy in measured $\tau_n$ between the two methods. The UCN$\tau$ experiment at Los Alamos Neutron Science Center fills an asymmetric magneto-gravitational trap with UCN, and then counts the surviving UCN after various holding times to measure $\tau_n.$ The UCN$\tau$ collaboration has published a systematic uncertainty of $^{+0.4}_{-0.2}$ s based on the analysis of our 2016-2017 data set. The effect of the depolarization of UCN is measured by varying the magnetic holding field magnitude. The effects of microphonic heating of trapped UCN and of insufficient cleaning of UCN with energies above the trapping potential are measured by detecting surviving high-energy UCN. The effect of phase space evolution of UCN is measured by comparing the time distributions of the surviving UCN after various holding times. We will present details of how these systematic effects are measured and projections of how they will be better constrained.
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700