Oak Ridge National Laboratory

Physics Division

Physics Division Seminars

Physics Division Seminars bring us speakers on a variety of physics related subjects. Usually these are held in the Building 6008 large Conference Room, at 3:00 pm on the chosen day, but times and locations may vary. For more information, contact our seminar chairman,

Alfredo Galindo-Uribarri
Tel (Office): (865) 574-6124  (FAX): (865) 574-1268


Thu., March 20, 2014, at 3:00 pm - 4:00 pm (Refreshments at 2:40PM)

Weak Interaction Studies with Laser-Trapped 6He

David W. Zumwalt, Center for Experimental Nuclear Physics and Astrophysics, University of Washington, Seattle, WA
ORNL, Bldg. 6008 Large Conference Room

6He beta decay is an excellent case to test the nature of the weak interaction through a precise measurement of the β-antineutrino angular correlation parameter a. According to the Standard Model, the pure Gamow-Teller decay of 6He should be ruled by an axial-vector interaction only, which leads to a = -1/3. Any deviation due to tensor coupling contributions would indicate new physics beyond the Standard Model. The high precision goal of this experiment, Δa/a = 0.1%, requires a large statistical sample along with small and well known systematic uncertainties. To satisfy these constraints, neutral 6He atoms are captured with laser light in a magneto-optical trap (MOT). Laser trapping allows observing the decay products with minimal perturbations. 6He (t1/2 = 807 ms) is produced on-line through the 7Li(d,3He) 6He nuclear reaction by impinging a molten lithium target with an intense 18-MeV deuteron beam provided by the Tandem Van de Graaff accelerator available at the Center for Experimental Nuclear Physics and Astrophysics of the University of Washington. Up to 1010 6He atoms per second are extracted from the target, transferred to the atomic beam line, and subsequently trapped in a two stage MOT. The angular correlation parameter is obtained by detecting the 6Li+ recoil ions incoincidence with the beta particle. The details of the setup and preliminary results will be presented.

This work is supported by DOE, Office of Nuclear Physics, under contract nos. DE-AC02-06CH11357 and DE-FG02-97ER41020.

Contact: Alfredo Galindo-Uribarri, (865) 574-6124