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neutron lifetime experiments

neutron lifetime experiments. higher order processes (2 W - exchange, photon production, …  “radiative correction” ). t n determines l. need other measurements to separately determine g A and g V . These are the basic parameters that determine H w. neutron lifetime experiments.

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neutron lifetime experiments

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  1. neutron lifetime experiments higher order processes (2 W- exchange, photon production, …  “radiative correction”) tn determines l need other measurements to separately determine gA and gV. These are the basic parameters that determine Hw . E. Beise, P441 notes

  2. neutron lifetime experiments Two techniques: 1) beam: send neutrons through a well-defined volume, determine the “loss rate” by counting decay products: decay product rate into a detector # neutrons incident on the defined volume 2) “bottle” or “storage”: trap neutrons, measure decay products vs time. other loss mechanisms E. Beise, P441 notes

  3. NIST Center for Neutron Research 20 MW reactor is source of “cold” neutrons: Tn~10-5-10-2 eV deBroglie wavelength: reactor core E. Beise, P441 notes

  4. Cold Neutron Research Facility (Guide Hall) E. Beise, P441 notes

  5. NIST lifetime experiment (beam type) E. Beise, P441 notes

  6. NIST lifetime experiment (beam) E. Beise, P441 notes

  7. UCN lifetime experiment on NG6-U E. Beise, P441 notes

  8. neutron lifetime measurement at ILL (Grenoble, FR) A.P. Serebrov, etal UCN trap cryostat UCN’s in E. Beise, P441 notes

  9. summary of measurements Serebrov, etal E. Beise, P441 notes

  10. UCNA experiment, Los AlamosExperimental Method from J. Martin, U. Winnipeg Endpoint energy 782 keV Focus electrons onto detectors using a strong (1 T) magnetic field E. Beise, P441 notes

  11. UCNA Experiment, Los Alamos from J. Martin, U. Winnipeg E. Beise, P441 notes

  12. Ultracold Neutrons: Superthermal Process slide from C.-Y. Liu, Indiana Univ. R. Golub and J. M. Pendlebury, Phys. Lett, A53, 133 (1975) • Cold neutrons downscatter in the solid, giving up almost all their energy, becoming UCN. • UCN upscattering (the reverse process) is suppressed by cooling the moderator to low temperatures. E. Beise, P441 notes

  13. slide from B. Filippone, Caltech UCNA experiment Experiment commissioning underway Initial goal is 0.2% measurement of A-correlation (previous measurements ~ 1% uncertainty) UCNA Liquid N2 Be reflector LHe Solid D2 77 K poly Tungsten Target E. Beise, P441 notes

  14. SS UCN Bottle 58Ni coated stainless guide Liquid N2 Flapper valve Be reflector LHe Solid D2 (5K) UCN Detector 77 K poly 5 K poly Tungsten Target Los Alamos prototype UCN source slide from A. Young, NCSU PhD Thesis: Chen-Yu Liu, Princeton Univ. , (now faculty at Indiana U) E. Beise, P441 notes

  15. Experimental Area B: UCNA Experiment beta-spectrometer magnet From UCN source beta detector polarizer magnet “prepolarizer” magnet UCN guide path

  16. UCNA spectrometer E. Beise, P441 notes

  17. Slide from P. Mumm, U Md, 2007 E. Beise, P441 notes

  18. Slide from P. Mumm, U Md, 2007 E. Beise, P441 notes

  19. emiT detector assembly from P. Mumm, 2007 E. Beise, P441 notes

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