Canada’s national laboratory for particle and nuclear physics and accelerator-based science

Leaning Out of Windows

Antimatter Seminar

Canada’s national laboratory for particle and nuclear physics and accelerator-based science

Matter-Antimatter Asymmetry and the Neutron Electric Dipole Moment Des Ramsay Researcher – Particle & Nuclear Physics

Possible development of Matter-Antimatter Asymmetry

After Electroweak Phase Transition

Now

Dipoles have two poles

S

N +

-

magnetic dipole

(e.g. bar magnet) electric dipole

What is a neutron EDM ?

l

dn = ql

+q

-q

Standard Model : 10-31 e·cm to 10-32 e·cm SUSY: ~10-26 e·cm Best experimental limit: < 3 x 10-26 e·cm Limit in 5 to 10 years: 10-27 e·cm

Neutron EDM violates time reversal invariance

spin

charge

Neutron spin precession

How to measure the neutron EDM

How to measure the precession frequency

Use a very precise method called “Ramsey resonance”:

Precise measure of precession frequency

“central fringe” of the Ramsey resonance curve

Solid nickel plate as seen by a fast neutron

1    

NICKEL PLATE

1 km

golf ball sized nucleus

golf ball sized nucleus

How to hold the neutrons in a bottle

• Make them ultra cold, ~3 mK (0.003 degrees above absolute zero)

•  speed ~7 m/s (25 km/hr)

•  long wavelength

•  bounce off walls

How to make the neutrons Ultra Cold

EDM History