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Guy Savard Argonne National Laboratory and University of Chicago

4 th Workshop on Physics with a high-intensity proton source November 09-10 2009 Fermilab Standard Model via Nuclear Physics. Guy Savard Argonne National Laboratory and University of Chicago. Outline. Fundamental interactions at low energy: basic approach

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Guy Savard Argonne National Laboratory and University of Chicago

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  1. 4th Workshop on Physics with a high-intensity proton sourceNovember 09-10 2009FermilabStandard Model via Nuclear Physics Guy Savard Argonne National Laboratory and University of Chicago

  2. Outline • Fundamental interactions at low energy: basic approach • Choose from the wide variety of available systems the one that selectively enhances or isolates the effect • High Z simple atoms (Fr, Ra, Rn) • Clean decays (N=Z nuclei, n) • Opportunities offered by radioactive atoms/ions/neutrons • Electric dipole moments (atoms, electron, neutron) • Parity violation in atoms • Determination of Vud and test of CKM unitarity • Searches for interactions outside V-A • … • Status

  3. Search for an electric dipole moment and physics beyond the standard model A permanent EDM violates both time-reversal symmetry and parity + + - T P - - + EDM Spin EDM Spin EDM Spin To understand the origin of the symmetry violations, you need many experiments! Neutron Quark EDM Physics beyond the Standard Model: SUSY, Strings … Diamagnetic Atoms (Hg, Xe, Ra, Rn) Quark Chromo-EDM Paramagnetic Atoms (Tl, Fr) Molecules (PbO) Electron EDM

  4. Electro- 10-20 10-20 magnetic electron: 10-22 neutron: 10-24 Experimental Limit on d (e cm) Multi SUSY Higgs f ~ 1 f ~ a/p Left-Right 10-30 10-30 2000 1960 1970 1980 1990 10-32 10-34 StandardModel any positive signal is new physics … not SM 10-36 10-38 EDM measurements: the SM extension slayers Updated from Barr: Int. J. Mod Phys. A8 208 (1993)

  5. Enhanced EDM of 225Ra |a |b Parity doublet - = (|a - |b)/2 + = (|a + |b)/2 55 keV • Enhancement mechanisms: • Large intrinsic Schiff moment due to octupole deformation; • Closely spaced parity doublet; • Relativistic atomic structure. Haxton & Henley (1983) Auerbach, Flambaum & Spevak (1996) Engel, Friar & Hayes (2000) Enhancement Factor: EDM (225Ra) / EDM (199Hg) Schiff moment of 199Hg, de Jesus & Engel, PRC (2005) Schiff moment of 225Ra, Dobaczewski & Engel, PRL (2005)

  6. -1 +1 -1 +1 Bx x magnetic field Need an arsenal of tools to accumulate radioactive atoms … e.g. Magneto-Optical Trap In one dimension with J=0→J=1 transition Create damped harmonic oscillator: F = -k∙v+mBx mJ Energy Excited State J=1 Velocity-dependent force: Doppler shift alters laser frequency seen by atoms -1, 0, +1 -1, 0, +1 0 0 n laser s- s+ Position-dependent force: Zeeman shifts from magnetic field Ground State J=0 0 0 x

  7. Oven: 225Ra (+Ba) A proposed path for higher sensitivity: EDM of 225Ra at Argonne (Z.T. Lu et al.) • Status and Outlook • First atom trap of radium realized • Guest et al. Phys Rev Lett (2007) • Search for EDM of 225Ra in 2009 • Improvements will follow 225Ra Nuclear Spin = ½ Electronic Spin = 0 t1/2 = 15 days Zeeman Slower Magneto-optical trap • Why trap 225Ra atoms • Large enhancement: • EDM (Ra) / EDM (Hg) ~ 200 – 2,000 • Efficient use of the rare 225Ra atoms • High electric field (> 100 kV/cm) • Long coherence times (~ 100 s) • Negligible “v x E” systematic effect EDM probe Optical dipole trap

  8. 225Ra Source – Present and Future at a Rare Isotope Facility Present scheme 229Th 7300 yr • 1 mCi 229Th source  4 x 107 s-1225Ra • Projected EDM sensitivity: 10-26 – 10-27 e-cm • Equivalent to 10-28 – 10-30 e-cm for 199Hg • Current limit on 199Hg: 3 x 10-29 e-cm a 225Ra 15 d Search for 225Ra EDM at a rare isotope facility • Yield: 1 x 1012 s-1225Ra • Projected EDM sensitivity: 10-28 e-cm • Equivalent to 10-30 – 10-31 e-cm for 199Hg • Study systematics at 10-29 e-cm for 225Ra b A similar improvement path is possible with Rn isotope EDM searches (see T. Chupp talk in Oct 09 workshop).

  9. A proposed path to improve the e-EDM measurement • Best limit on the e-EDM comes from measurements with an atomic beam of Tl • 7 orders of magnitude improvements in 50 years • No improvements in the last 7 years • New technology needed  atomic fountains • Demonstrate feasibility with Cs • Obtain best limit with Fr ( 9 times more sensitive to e-EDM) • Fr production with 500 kW of 2 GeV protons would give a factor 100-1000 gain in Fr production over any existing facility Experimental upper limits to the e-EDM 1962-2009 Proof-of-principle atomic fountain EDM experiment Photo courtesy of H. Gould

  10. n-EDM searches … intense UCN sources needed • Large n-EDM experiment in preparation in the US at the SNS • UCN offer unique advantages for these studies and there is intense activity worldwide to create stronger sources • A few % of the 500 kW proton beam could provide a cutting edge facility for such studies in the US

  11. Weak interaction between the outer electron and the nucleus |nS>´=|nS>+|nP> QW(Experiment)*=-72.06±0.28exp±0.34th QW(Standard Model)= -73.20 First observation of anapole moment *PRL 82 (1999) 2484 for Cesium:

  12. The Boulder Cs PNC Experiment 1982-1999 • P-odd, T-even correlation: S• [E  B] • 5 reversals to distinguish PNC from systematics

  13. A natural path to an improved APV experiment • Want a larger signal in a “simple” atom • APV signal in Fr is 18X larger than in Cs • Remove theoretical uncertainties • Dominating uncertainty comes from atomic physics corrections • Measurement on n-rich and n-deficient Fr isotopes • Difference signal still larger than in Cs but dominating theoretical uncertainty is removed • Next leading uncertainty from neutron distribution • 208Pb work at JLAB and hyperfine anomaly measurements • Get the counting rate • Boulder Cs experiment used an atomic beam of 1013 /cm2/s • Equivalent to about 108 Fr atoms in an optical trap … requires a beam of 1010-1012/s Proposed Fr APV setup at TRIUMF

  14. VudVus Vub Vcd Vcs Vcb Vtd Vts Vtb Big effect if R-parity violating … can be more than 0.0020 At loop level if R-parity conserving …. ~ 0.0007 Superallowed Beta Decay • Precision tests of CVC • Determination of weak vector coupling constant • Unitary tests of the CKM matrix • For superallowed transitions between 0+ T=1 states Ft = ft ( 1 + dR ) ( 1 – dC) = from experiment; from calculations of radiative and charge-dependent effects • Test need for physics beyond the standard model Gv together with Gm yield the Vud quark mixing element of the CKM matrix • If matrix is not unitary then we need new physics Additional Z bosons, Right-handed currents, SUSY… K 2 GV2 ( 1 + DR ) d s b d’ s’ b’ = mass eigenstates rotation matrix weak eigenstates

  15. Low energy experimental direction  validate corrections This capability is a direct consequence of having many candidates.

  16. Sources of uncertainty in Vud determinations 161 18 18 18 16 16 16 Exp 14 14 14 12 12 12 Exp Uncertainty (10-4) 10 10 10 8 8 8 dR 6 6 6 DR DR DR 4 4 4 dC Exp 2 2 2 dR dR Nuclear 0+ to 0+ Vud = 0.9738  0.0004 Neutron decay Vud = 0.9740  0.0013 … or lower Pion beta decay Vud = 0.9760  0.0161 (latest tn lower by 6.5 s)

  17. Reduced by a factor of 2 by W. Marciano Status of CKM unitarity tests • New Penning trap Q-value measurements have uncovered an omission in the isospin-symmetry breaking corrections which has been resolved • |Vud| = 0.97425 ± 0.00022 • taking that latest value for Vud together with • |Vus| = 0.22534 ± 0.00093(from E865, KTeV, NA48, KLOE and FlaviaNet) • |Vub| = 0.00393 ± 0.00035 • yields |Vud|2 + |Vus|2 + |Vub|2 = 0.99995 ± 0.00061 • The largest contribution to the error is from f+(0), followed closely by the uncertainty in the nucleus independent radiative correction to Vud

  18. Further improvements possible • Neutron should eventually provide a complementary value for Vud, will be limited by the same radiative corrections, but susceptible to different new physics • Intense UCN source is critical for these improvements • On the superallowed front, further improvement in experimental inputs will allow to better test the nuclei dependent corrections and further improve the value of Vud • Weak branching ratios are critical and require RIB intensities in excess of what is currently available • Soon can obtain a higher precision test of unitarity independent of Vus and its associated uncertainties A large improvement in the top row unitarity test is within reach … already sensitive to SUSY.

  19. n b d W u Compare experimental values to SM predictions Put limits on terms “forbidden” by SM Nuclear Beta-Decay Coupling constants: CS, CV, CA, CT Differential Decay Rate:

  20. Weak Interactions in Nuclei Historically the V-A structure of the weak interaction was determined by measurements of the beta-neutrino correlation in noble gas nuclei in the 1960’s 32Ar,38mK,14O Today precise measurements of the beta-neutrino correlation are conducted to search for scalar or tensor contributions from exotic weak bosons. 21Na New approaches using atom and ion traps provide ideal sources to improve the accuracy of these measurements.

  21. Berkeley measurement of the b-n Angular Correlation in Magneto-Optically Trapped 21Na 21Na 3/2+3/2+a = 0.5243±0.0091 N.D. Scielzo et al., Phys. Rev. Lett. 93, 102501 (2004) Recoil-ion TOF 500,000 trapped atoms Ideal Source: negligible source scattering sample is isotopically pure localized in small volume atoms decay at rest potential for polarized sample a deduced from TOF

  22. Field Expansion Region e Neutron Absorber q n Measurement of A with UCN at LANSCE Detector 1 Detector 2 dW=[1+bPAcosq]dG(E)

  23. Requirements • The full modern low-energy arsenal • Penning traps • RFQ traps • magneto-optical traps • dipole traps • lots of laser power and build up cavities • radiation detectors (DSSD, MCP, HPGe, CCD) • lots of preparation, systematic checks • beamtime • Intense and pure low energy radioactive beams • lots of Fr … both n-rich and p-rich • highest achievable intensities of Rn, Ra • N=Z nuclei • UCN source A facility based at the proton driver can provide the required beams.

  24. Status Physics Opportunity The availability of high-intensity sources of radioactive ions and ultra-cold neutrons opens up important opportunities to test the Standard Model at low energy. The candidates presenting the best characteristics (large enhancement or specific decay) can be selected to enhance the sensitivity to new physics. Technical Developments The technological developments in atom trapping, ion trapping, atomic clock, detector technology and related techniques further enhance these new capabilities. Competitiveness These combined advances will maintain the competitiveness and complementarity of these low energy tests of the Standard Model to work performed at the high-energy frontier.

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