[Triumf-seminars] TRIUMF Student Seminar today at 09:30

[postmaster@admin.triumf.ca]

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Date/Time: Wed 2005-06-15 at 09:30

Location:  Auditorium          

Speaker:   John Behr ()

Title:     Weak Interaction Symmetries with Laser Traps

Abstract: ``Table-top'' experiments can still probe physics complementary to 
particle searches at high-energy accelerators. 
A beta-neutrino correlation experiment using TRIUMF's neutral atom trap 
(TRINAT) has now set the best limits on general scalar interactions 
contributing to nuclear beta decay. 

Using the radiation pressure of laser light, 
TRINAT captures radioactive atoms in a 1 mm-sized
cloud in a vacuum chamber.
Such magneto-optical traps for stable isotopes are the first step
in many recent laser-cooled atom experiments, 
including Bose-Einstein condensates. 
The atomic nuclei undergo beta decay, which produces three decay products: 
a positron, a neutrino, and the daughter recoiling nucleus.
The daughter nucleus has very little energy and would stop
in a nanometer of material, but it freely escapes the trap.
By measuring its momentum in coincidence with the beta, 
the neutrino direction with respect to the beta 
can be deduced more directly than in previous
experiments. 

As far as we know, the Standard Model weak interaction is mediated by
``heavy light'', ``vector'' bosons with spin 1 which are heavy partners of
the photon. The present work
sees a beta-neutrino correlation consistent with the Standard Model, and
constrains the existence of other exchange bosons with spin 0.



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