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Polarized neutron decay with Cold Beams

Polarized neutron decay with Cold Beams. The physics is important and interesting (Vud, Nucleosynthesis/Sun, BSM) 2. With new and existing tools (NIST, SNS, 3 He and FnPB Beta Decay Facililty) We are poised for US Leadership in the field. Tim Chupp

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Polarized neutron decay with Cold Beams

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  1. Polarized neutron decay with Cold Beams The physics is important and interesting (Vud, Nucleosynthesis/Sun, BSM) 2. With new and existing tools (NIST, SNS, 3He and FnPB Beta Decay Facililty) We are poised for US Leadership in the field Tim Chupp www.physics.lsa.umich.edu/chupp chupp@umich.edu World

  2. Polarized Neutron Decay p p e e n n N+ N- dW pe.pn meJpe pnpexpn _____________ = S(Ee)[1 + a ______ + b ___ + ___.(A____ +B____ +D _______ )] dEedWedWnEeEn Ee J Ee EnEeEn Vud RHC CP Vud

  3. World Leadership

  4. Cabibbo-Kobayashi-Maskawa Matrix Unitarity of first Row  0.94795 ± 0.0005  0.9483 ± 0.0008  0.0507 ± 0.0008  0.0482 ± 0.0011  2e-6 (negligible)  2e-6 (negligible)  0.9987 ± 0.001  0.9966 ± 0.0014 (1.3s) (2.2s) Towner & Hardy, Phys. Rev. C 71 055501 (2005) Summer 2006

  5. Vud from neutron decay The neutron lifetime depends on Vud and l and =gA/gV t -1=1.879x10-4 |Vud|2(1+3|l|2)(1+0.0739±0.0008)

  6. p,e p,e e,p e,p n n N+ N- M1 M2 polarizer analyzer Spin Flipper X N0(v) y neutrons P(v) TP(v) A(v) TA(v) R z Detector Detector 1 Detector 2 Neutron beam Into page +30 kV V0 ~ ~ ~ ~ Uniform field B PANDA:NIST, Los Alamos,Tulane, Hamilton, dePauw, WUM abBA and NabORNL, Los Alamos, NIST Utenn, UVa, ASU UM

  7. FnPB PAC recommended a “Common Magnet Facility”

  8. Systematics N+ - N- N+ + N- __________ = C PnA F (1-f) + Afalse background spin flip efficacy analyzing power neutron polarization Need to know: neutron polarization analyzing power spin flip efficiency backgrounds spin independent spin dependent (false asymmetry) e.g. False asymmetry from electrons emited from n-decay (BR) - study of proton energy dependence Noise, gain shifts, etc. - flip 3He Obs. INDEPENDENT of Pn, xy, L, tof, 3He, B, BR, … statistical power

  9. Neutron Polarization and Polarimetry M2 M1 polarizer analyzer Spin Flipper X N0(v) neutrons P(v) TP(v) A(v) TA(v) R Detector RExp= S( + ) + D( - ) =N0T1T2TP [G0+DPR] G±=S±D M1= N0e1+B1 M2= N0T1T2TPTAe3 [ 1+PAR] +B2 P/A Pn (5Å) Tn P2T features PSM 99.x% 10% 0.1 fixed; limited l bite 3He (60%) 80% 30% 0.2 flip P3; P3 varies Flipper: Ru= 1 (unflipped); Rf=F≈-1 (flipped) (-0.999 for AFP) (M2u - M2f) (M2u + M2f) _________ ~ PA(1-F) (1-f2) BR (1% need to know to 0.1%)

  10. 1/v 3He (n+3He _> p+t) TA/P=T0cosh aPA/P P/A=tanh aPA/P x10-3 Coulter technique npdgamma data Pn P3=0 P3=60% Opaque 3He Analyzer (A) (A) (1/v) (1/v)

  11. 3He spin filter Booboo is the Cell 12 cm GE-180 Glass (boron free) Cells get “milky” deposit over LONG TERM???? Evidence of FAST Rb depolarization????

  12. Summary The physics is important and interesting Unique tools - FnPB and NIST Needs: Magnet Facility, Increased 3He resources, Polarimetry development, Theory

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