Choose timezone
Your profile timezone:
Weak Interaction Discussion Group (WIDG)
Weak Interaction Discussion Group Talk (WIDG) - Chen-Yu Liu, Indiana University, “Neutron Lifetime Measurements: Much Ado About 1 second”
→
US/Eastern
WLC 108
WLC 108
Description
Eighty years after Chadwick discovered the neutron, physicists today still debate over how long the neutron lives. Measurements of the neutron lifetime have achieved the 0.1% level of precision (~ 1 s), however, experiments using the bottle technique yield lifetime results systematically lower than those using the beam technique. It is important to resolve this discrepancy surrounding the neutron lifetime because of its critical roles in refining the theory of the electroweak interaction, Big Bang Nucleosynthesis, and solar fusion.
Measuring the neutron lifetime is difficult for several reasons: the low energy of the decay products, the impossibility of tracking slow neutrons, and the fact that the neutron lifetime is long (880.3 +/- 1.1 s, PDG2014). In particular, slow neutrons are susceptible to many loss mechanisms other than beta-decay, such as upscattering and absorption on material surfaces; these act on time scales comparable to the beta-decay lifetime and thus make the extraction of the lifetime very challenging. In the UCNtau experiment, we trap ultracold neutrons (UCN) in a magnetic-gravitational trap. The apparatus, installed at the Los Alamos UCN source, has been used to develop new techniques, with an aim to reducing the uncertainty to 1 s and below.
I will report our first competitive results and discuss plans to quantify systematic effects.
