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The NPD  Experiment David Bowman

The NPD  Experiment David Bowman. I Scientific goals II Status. NPD  Collaboration. Institutions Dayton, Dubna, Hamilton, Indiana, Jlab, KEK, LANL, NIST, ORNL, TRIUMF, Berkeley, Manitoba, Michigan, New Hampshire, Tennessee Sponsors DoE, NSF, NSERC, LANL, collaborating institutions.

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The NPD  Experiment David Bowman

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  1. The NPD ExperimentDavid Bowman I Scientific goals II Status

  2. NPD Collaboration • Institutions • Dayton, Dubna, Hamilton, Indiana, Jlab, KEK, LANL, NIST, ORNL, TRIUMF, Berkeley, Manitoba, Michigan, New Hampshire, Tennessee • Sponsors • DoE, NSF, NSERC, LANL, collaborating institutions

  3. Scientific goal of the experiment

  4. Hadronic weak interaction • Weak NN force interferes with the strong NN force. • Changes parity of the NN pair. • Changes INN by 0, 1, or 2. • Produces parity-violating admixtures in nuclear wave functions and PV asymmetries • HWI is described by a meson exchange potential

  5. The value of is controversial • 18F gamma circular polarization experiments give 0. Haxton interprets result to give =0±1.0 10-7. • 133Cs anapole moment gives non-zero value. Flambaum interprets result to give =7±3 10-7. • The goal of the NPDg experiment is to measure with an accuracy of 0.5 10-7. • Goal error is 5% of the DDH reasonable range.

  6. Status of NPD experiment • 04-5 commissioning run complete • 06 production at LANSCE • Measure A to ±10-7 • Move to SNS in 06-7 • Measure A to ±10-8

  7. Apparatus to measure A

  8. Neutron Intensity Monitors

  9. 3He neutron polarizer

  10. Determine 3He polarization • Stable operation for several weeks • 3He polarization = 46±2%

  11. Commissioning the RFSR FP12 neutron guide RF Spin Rotator M2 M1 3He Spin Filter

  12. Preliminary Spin-flipper efficiency

  13. Liquid Para-Hydrogen Target • 20 liter liquid volume, 30 cm diameter • and 30 cm long • Absorbs 65% of neutron beam • 1% neutron depolarized at 17K (0.05% of • LH2 in ortho-state) due to large scattering • cross section • No false asymmetriesfrom target material • Use 6Li to shield CsI from neutrons Ortho (total) Para (total) Capture cross section

  14. CsI detector 48 (15cm)3 modules

  15. noise/counting statistics • Electronic noise << counting statistics • Experiment operates close to counting statistics limit

  16. Electronic asymmetries(beam off) • Time to determine electronic asymmetries << run time • False asymmetries are  10-8

  17. Measured asymmetries • Time to determine background asymmetries << run time • False asymmetries ~ asymmetry  f-bkg are  5 10-8

  18. Spin interactions

  19. Estimated sizes of false asymmetries

  20. Apparatus performance • All components of the apparatus performed as designed • Several physics measurements have been

  21. LH target must be finished, tested, and installed • We request a thorough-going safety review to insure a safe target.

  22. Beam time request • The estimate is based on measured performance • 3He polarization = .55 • Cell diameter = 10 cm • Projected FPNB projected intensity • 7000 MWh for data and systematics • 1000 h at > ,14 MW for tuning and systematics

  23. Schedule • We request that NPD run after the beam line is commissioned • 9/06 Move to SNS • 9/07 Beam line ready • 12/07 Experiment installed • 3/08 Commissioning complete • 6/08 Start production

  24. Geoff’s questions • Technical issues - hydrogen target • Funding $K 2500 already spent for apparatus at LANL • 20 transport to SNS • 160 shielding • 20 supports and stands • 20 Air conditioning • 130 target infrastructure • 30 instrumentation/cabling • Safety - hydrogen target • Complex installation - one block • ~ 40 users • 3 PhD’s to date, trained several undergraduate students, Expect several PhD’s from SNS run

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