Fundamental Problems of Neutron Physics at the Spallation Neutron Source

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Fundamental Problems of Neutron Physics at the
Spallation Neutron Source

• Vladimir Gudkov
• June 15, 2004
• University of South Carolina

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High Energy Physics with Low Energy Neutrons

• HEP

E ? ?
FNP
?E/E ? 0
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High Energy Physics with Low Energy Neutrons

• Neutron Reactions
• Neutron Energy 0.01 100 eV
• Nuclear Excitation Energy 6 7 MeV ?
  Energy
• 
  resolution 10-9
• Flux ? precision
• Polarization
• Low Energy enhancement
• Complex nuclear system by 106
• RELATIVE Measurements MANY Targets
• The possibility to eliminate Theoretical
  uncertainties
• ? Symmetry Tests Fundamental Constants

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Time Reversal Violation
n
n
n
n
s
p
s
X
W
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Theoretical predictions
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Fundamental Constants

• GF ? ?-decay
• Vud M ?GF ? Vud ?( ?)
• ? n-decay
• ? 0 ? 0 (theory input)
• ? ? n-decay

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Unitarity

• Vud 2 Vus 2 Vub 2
  1
• ? ?
• Vud Vus 0.2196 ? 0.0023
  Vub/ Vcb 0.090 ?0.025
• ? ? ?
• 
  Vcb 0.0402 ?0.0019
• 0.9740 ? 0.0005 nuclear ?-decay
• 0.9734 ? 0.0008 PDG
• 0.9713 ? 0.0014 n-decay
• 0.9740 ? 0.0010 unitarity
• 0.9771 ? 0.0056 ?-decay

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Vus
Courtesy of Vincenzo Cirigliano
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Nuclear Parity Violation
Courtesy of Barry R. Holstein
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Courtesy of Norval Fortson
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More new physics

• Right-Left Models
• H ?(V-A)(v-a)(xVyA)(va)h.c.
  
• (? 10-2)
• Scalar interactions (? 10-2)
• Tensor interactions (? 10-2)

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Radiative Corrections

• Level of contribution ? 2.2
• Detailed calculations for 0 ? 0 (Fermi)
• QCD perturbation approach and/or hadronic models
• Renormalization procedure ? mixture initially
  separated outer (well known) and inner (model
  dependent) parts

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Initiation of the collaboration

• Research history at the leading research centers
  of the world Europe, Japan, Australia and USA
• Involvement in the current research activity
  LANL, ORNL, SNS, NCSU
• Participation in workshops conferences
• ? To address the most urgent needs and to take a
  responsibility for difficult parts of the
  proposed research.

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How are we involved?

• Theoretical support for the proposed research
  (graduate)
• Exploration of new possibilities (graduate)
• Computational physics application (new)
  theoretical results for detector simulations and
  optimizations (graduate / undergraduate)

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The Fundamental Neutron PhysicsInstrument
Development Team

• There is a user community of 100 physicists in
  the US
• Our Instrument Development Team currently
  consists of 60 scientists from more than 20
  institutions

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Artist's conception of the SNS
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Aerial, April 2004
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The Fundamental Neutron Physics At the Spallation
Neutron Source

• Determination of the Neutron Lifetime Using
  Magnetically Trapped UCN First Version now
  underway at NIST. Will move to SNS when available
• Measurement of Parity Violation in n-p and n-d
  Capture First Version underway at LANSCE will be
  flux limited
• Precise Measurement of Correlations in Neutron
  Beta Decay Experiment now under development
  (ORNL, LANL, U of Va., Indiana
• New Search for an Electric Dipole Moment
  Experiment under Development at LANL
• Precise Measurement of Neutron Spin Rotation in
  H2 and He Continuation of program now at NIST
• Other

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FNP program for 20 years

• Working on the abBA proposal for neutron beta
  decay experiment at the SNS
• Established working relations with J-SNS
• Negotiating the possible collaboration with ILL
  (Grenoble) for Ultra Could Neutron research
  (NSF-?)
• ?SNS collaboration
• Plan to apply for DOE grant for theoretical
  research in FNP