60Co and the Death of Parity

Time Line1949: - Puzzle

Tau-Theta Puzzle

Tau-Theta Puzzle

•++++-

•++0

Tau-Theta Puzzle

•++++-

•++0

•P=-1

Tau-Theta Puzzle

•++++-

•++0

•P=-1

•P≠P

Time Line1949: - Puzzle

1956: Lee and Yang

Lee and Yang

Lee and Yang

•What if = ?

Lee and Yang

•What if = ?•Plenty of Evidence of P Conservation for

Strong Force and EM

Lee and Yang

•What if = ?•Plenty of Evidence of P Conservation for

Strong Force and EM

•No Experimental Tests of P Conservation for Weak Force

Lee and Yang

•What if = ?•Plenty of Evidence of P Conservation for

Strong Force and EM

•No Experimental Tests of P Conservation for Weak Force

•Does / Decay Violate Parity?

Parity Violation

Parity Violation

Parity Violation

Need a correlation between a vector (emission) and a pseudovector (spin)

Time Line1949: - Puzzle

1956: Lee and Yang

1957: 60Co Decay

Decay Parity Violation

Problems:

Alignment of Nuclear Spin

Measurement of Spin Alignment

Cryogenics

Solution:60Co

Reasons to Use 60Co

Strong Magnetic Moment Easy to Polarize

Emission Prefers Spin Axis Measurement of Polarization

Incorporation in a Crystal Adiabatic Demagnetization to <1°K

Co doped [2Ce(NO3)3

•3Mg(NO3)2 •24H2O] cooled to .01°K

Time Line1949: - Puzzle

1956: Lee and Yang

1957: 60Co Decay

1957: --e Channel

--e Parity Violation

Nevis Lab: 400MeV p+ Cyclotron

p+ collision ++e+

Direction of + beam defines spin axis

Look for asymmetries in spin alignment

Publications:

CS Wu, et al “Experimental test of parity conservation in beta decay.” Physical review, 1957

LM Lederman, RM Garwin, M Weinrich “Observations of the failure of conservation of parity and charge conjugation in meson decays: The magnetic moment of the free muon.” Physical review, 1957

Conclusions:

Conclusions:

Don’t share paradigm shifting results until you’re ready to publish!

Credit for images goes to:

George L. Trigg. Landmark Experiments in Twentieth Century Physics. New York: Crane, Russak & co., 1975

C.S. Wu and S.A. Moszkowski. Beta Decay. Hoboken:John Wiley & Sons, 1966

Leon Lederman. The God Particle. Boston: Houghton Mifflin co., 1993