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Parity%20Violation%20and%20the%20Neutron%20

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Physics at the SNS, Oak Ridge Nat. Lab. Christopher Crawford Cosmic Lunch 2010-02-19 Interactions and Symmetries Properties of the Neutron Spallation Neutron Source (SNS) – PowerPoint PPT presentation

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Title: Parity%20Violation%20and%20the%20Neutron%20


1
Parity Violation and the Neutron Physics at the
SNS, Oak Ridge Nat. Lab.
  • Christopher Crawford
  • Cosmic Lunch
  • 2010-02-19
  • Interactions and Symmetries
  • Properties of the Neutron
  • Spallation Neutron Source (SNS)

Madison
Spencer
2
Standard Model of Particles
EM Interaction
Hadronic Interaction (residual nuclear force)
Weak Interaction
3
Standard Model of Automobiles
Annihilation
Higgs?
Degenerate Fermi Gas
Particle Decay
4
Symmetries
  • Continuous Symmetries
  • space-time translation
  • rotational invariance
  • Lorentz boosts
  • gauge invariance
  • Noethers Theorem continuous symmetries
    correspond to conserved quantities
  • energy-momentum
  • angular momentum
  • center-of-momentum
  • electric charge
  • Discrete Symmetries
  • parity P x ? -x
  • time T t ? -t
  • charge C q ? -q
  • particle exchange P12 x1 ? x2
  • Discrete Theorems
  • spin-statistics theorem
  • CPT theorem

5
Car Symmetries
L
R
CPT theorem ALL laws are invariant under CPT
6
Parity-violation in weak interaction (1956)
Parity-transformation (P)
October 1, 1956 issue of the Physical Review
7
Madame C.S. Wu
8
Properties of the Neutron
  • spin 1/2 isospin 1/2
  • mn mp me 782 keV
  • ?n 885.7 0.8 s
  • qn lt 2 x 10-21 e
  • dn lt 3 x 10-26 e cm
  • ?n -1.91 ?N
  • rm 0.889 fm
  • re2 -0.116 fm2
  • 3 valence quarks sea
  • exponential magnetization distribution
  • pion cloud

p
n
uud
udd
up
down
data from BLAST
9
Neutron sources - Reactors
ILL, Grenoble, France
10
Spallation Neutron Source (SNS)
Oak Ridge National Laboratory, Tennessee
  • spallation sources LANL, SNS
  • pulsed -gt TOF -gt energy
  • LH2 moderator cold neutrons
  • thermal equilibrium in 30 interactions

11
Spallation Neutron Source (SNS)
  • spallation sources LANL, SNS
  • pulsed -gt TOF -gt energy
  • LH2 moderator cold neutrons
  • thermal equilibrium in 30 interactions

12
Beamline 13 Allocated for Nuclear Physics (FnPB)
7 - Engineering Diffractometer IDT CFI Funded
Commission 2008
11A - Powder Diffractometer Commission 2007
9 VISION
6 - SANS Commission 2007
12 - Single Crystal Diffractometer Commission
2009
5 - Cold Neutron Chopper Spectrometer Commission
2007
13 - Fundamental Physics Beamline Commission 2007
4B - Liquids Reflectometer Commission 2006
14B - Hybrid Spectrometer Commission 2011
4A - Magnetism Reflectometer Commission 2006
15 Spin Echo
3 - High Pressure Diffractometer Commission 2008
17 - High Resolution Chopper Spectrometer Commiss
ion 2008
18 - Wide Angle Chopper Spectrometer Commission
2007
1B - Disordered Matls Commission 2010
2 - Backscattering Spectrometer Commission 2006
13
FnPB Cold UCN Line
14
FnPB Fundamental Neutron Physics Beamline
Choppers
Shutter
14 m guide, 10x12 cm2, 1 m from moderator
15
What can we do with neutrons?
  • scattering / diffraction
  • complementary to X-ray Bragg diffraction
  • large penetration
  • large H,D cross section
  • life sciences
  • fuel cell research
  • oil exploration
  • fundamental tests ofquantum mechanics
  • neutron interferometry
  • scattering lengths
  • neutron charge radius
  • spinor 4? periodicity
  • gravitational phase shift
  • quantum states in a gravitational potential

16
What can we do with neutrons?
  • fundamental symmetry tests of the standard model
  • neutron decay lifetime and correlations
  • PV NPDGamma, 4He spin rotation
  • T reversal electric dipole moment

nEDM
17
Neutron Traps
  • ultra cold neutrons slow enough to be
    completely reflected by 58Ni optical potential
  • kinetic 8 m/s
  • thermal 4 mK
  • wavelength 50 nm
  • nuclear 335 neV (58Ni)
  • magnetic 60 neV (1 T)
  • gravity 102 neV (1 m)

18
Car Traps
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