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The New Muon g-2 (and m EDM) Experiment at Fermilab  

The New Muon g-2 (and m EDM) Experiment at Fermilab  . David Hertzog University of Washington. Why mount a new experiment? Especially in “the LHC era?” What makes it different compared to BNL E821? Status. PSI2010: Physics of Fundamental Symmetries and Interactions. p. p. g. m. Z.

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The New Muon g-2 (and m EDM) Experiment at Fermilab  

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  1. The New Muon g-2 (and mEDM) Experiment at Fermilab   David Hertzog University of Washington • Why mount a new experiment? • Especially in “the LHC era?” • What makes it different compared to BNL E821? • Status PSI2010: Physics of Fundamental Symmetries and Interactions

  2. p p g m Z m p p B Weak Had LbL Had VP Had VP QED am= (g – 2)/2 is non-zero because of virtual loops, which can be calculated very precisely Known well Theoretical work ongoing The “g-2 test”: Compare experiment to theory. Is SM complete?

  3. GOAL BNL CERN III CERN II CERN I Historical Evolution 3

  4. HVP is determined from data

  5. A world-wide effort exists to measure over full range

  6. HVP evaluations by 2 groups, updated Tau’10 • Hagiwara, Liao, Martin, Nomura, Teubner (HLMNT) • M. Davier, A. Hoecker, B. Malaescu, Z. Zhang (DHMZ) • (BaBar team with access to preliminary data) Biggest difference is from high multiplicity states now measured at BaBar; > 1 GeV region  Reduces cross sections

  7. The new HVP evaluations also affect aQED running … and enter the global electroweak fits … Big shift !

  8. Hadronic Light by Light Scattering • Models converging … Noteworthy: PdRV* • Other theory newer efforts • Lattice – T. Blum et al (outlines a plan for real calc) • Dyson-Schwinger – C. Fischer et al (very controversial) • AdS/QCD – Deog-Ki Hong et al – confirm leading ps term • Data connection • KLOE-2 small angle tagger and g*g  p0and h to measure off-shell form factors … and compare to models am(HLbL)tot = 105 ± 26 x 10-11 *Prades, de Rafael, Vainshtein arXiv:0901.0306v1

  9. The values & the new experimental goal Theory uncertainty = 51 x 10-11 (0.44 ppm) Experimental uncertainty = 63 x 10-11 (0.54 ppm) • 0.46 ppm statistical  limit was counts • 0.21 ppm precession systematic • 0.17 ppm field systematic Leads to Dam(Expt – Thy) =297 ± 81 x 10-11 3.6 s BNL E821 Experimental goal: 63  16 x 10-11 Theory uncertainty expect: 51  30 x 10-11 Leads to Dam(Expt – Thy) =XXX ± 34 x 10-11 If central value remained, Damwould exceed 8s

  10. Precise knowledge of amwill aid in discrimination between a wide variety of standard model extensions • UED models (1D) typically predict “tiny” effects • Incompatible with a Dam of ~ 300 x 10-11 • SUSY models – there are many – predict am contributions of about the observed magnitude for Dam • These are rather well studied, so we will consider a few cases • The “Uninvented” – perhaps most importantly, sets a stringent experimental constraint for any new models

  11. What kind of new physics? Note: 42,000 more sensitive than electron C depends on the model M(GeV) D. Stockinger Note: Dam centered at 255 here

  12. difficult to measure at LHC Related processes in SUSY: Lepton Flavor Violation SUSY contribution toaμ: Mu2e & COMET MEG

  13. Connection between am, EDM and the charged Lepton Flavor Violating transition moment m → e SUSY slepton mixing am(real) EDM (imaginary) m→ e

  14. SUSY and g-2: The power to resolve among models and break LHC degeneracies Note: Dam centered at 255 here

  15. Suppose the MSSM point SPS1a is realized and the parameters are determined at LHC- sgn(D) gives sgn(m) • sgn (m) difficult to obtain from the collider • tan b poorly determined by the collider Assuming SPS1a; 100 fb-1 at 14 TeV New g-2 Old g-2 2s 1s LHC(Sfitter)

  16. µ 1 ppm contours Keys to an improved experiment: • Build on a proven technique • Make use of unique storage ring • New team built from E821 experts, augmented by significant new strengths • Obtain more muons • Control systematic errors

  17. Parasitic with n program Shared infrastructure with Mu2e Uses existing p-bar target hall Ideal bunch structure Long decay beam lines optimal Ideal muon delivery to storage ring using the excess proton batches from neutrino program

  18. The 900-m long decay beam: reduced flash; more store m/p Flash compared to BNL Stored muons / POT BNL FNAL Gain FNAL/BNL Parameter

  19. n p+ m+ 4 Key elements of the BNL & FNAL g-2 measurement (1) Polarized muons ~97% polarized for forward decays (2) Precession proportional to (g-2) (3) Pm magic momentum = 3.094 GeV/c E field doesn’t affect muon spin when g = 29.3 (4) Parity violation in the decay gives average spin direction µ 20

  20. The anomaly is obtained from three well-measured quantities

  21. The Storage Ring exists. It will be moved to FNAL

  22. The Storage Ring components affect muon storage Fast Kickers Superconducting inflector magnet incoming muons Electrostatic Quadrupoles

  23. The present inflector magnet has closed ends which scatter away ~half the incoming muon beam As-used Closed-ended m Prototype Open-ended Length = 1.7 m; Central field = 1.45 T Open end prototype, built and tested  x2 increase in stored muons

  24. Improvements in the kicker are planned because present one underkicks and pulse lasts too long. 149 ns cyclotron period Kicker waveform This kick affects the storage efficiency IDEAL kick  8% REAL kick  <3 % Kicker Amplitude

  25. Ideal Square Kick New tools allow us to simulate modified kicker pulse shapes and predict storage improvements % stored 10 8 6 4 2 0 Real LCR Kick

  26. The ± 1 ppm uniformity in the average field is obtained with special shimming tools. The dipole, quadrupole sextupole are shimmed independently 6 – 9 months required with cryogenics and ring on / off and in stable operating mode

  27. Improvement of Field by Shimming shimming shimming At this level, one hardly needs to know the muon distribution 2000 1999 2001

  28. The magnetic field is measured and controlled using pulsed NMR and the free-induction decay Electronics, Computer & Communication Position of NMR Probes Fixed Probes in the walls of the vacuum tank Absolute Calibration Probe: a Spherical Water Sample Trolley with matrix of 17 NMR Probes

  29. NA2 digitized samples N A <A>=0.4 An “event” is an isolated positron above a threshold. e+

  30. digitized samples An “event” is an isolated positron above a threshold. e+

  31. Geant Event Method NA2 N A <A>=0.4 Traditional method of determining wa is to plot Numberof events above threshold vs. Time Here, Asym is the average asymmetry of events above energy threshold cut

  32. Geant Event Method Same GEANT simulation Energy Method A complementary (integrating) method of determining wa is to plot Energy vs. Time We will operate this mode in parallel to above

  33. Parasitic Muon EDM Measurement using straw tube arrays BNL statistics limited • 1 tracking station • Late turn-on time • Small acceptance • Ran 2 out of 3 years FNAL: many stations, long runs, expect ~10,000 x the events The EDM tips the precession plane, producing an up-down oscillation with time (out of phase with wa) Technique: Measureup-going/down-going tracks vs. time, (modulo g-2):

  34. CALO X hodoscope e+ Hodoscope Detector systems • Calos: time and energy of decays • Hodoscopes: beam profiles, calo seeds, muon loss monitor • In-vacuum Straws: stored muon profile & independent EDM measurement E821

  35. Systematic error projections are in-line with statistical goal Magnetic field To here, requires “no” improvements. To 0.07 requires some R&D Improvement vs time  Precession

  36. The Ring Assembly 37

  37. Sikorsky S64F 12.5 T hook weight (Outer coil 8T) 38

  38. Status of the project … • March 09: Proposal presented • PAC positive • Committee to cost it • Summer 09: Costing • Oct. 09: Cost verifications • Nov. 09: PAC revisits • recommends Stage-1 approval • Feb. 10: DOE Briefing • Invitation to compete as new project • April 10: Proposal submitted to DOE • August 10: “Shootout” vs B factories • EMBARGOED result for now

  39. Project X? P-989 goal 16x10-11 8x10-11 30x10-11 15x10-11 Summary • The physics case for g-2 is stronger than ever • Lots of room for new groups to join and make it happen • The Fermilab Director is very optimistic about this happening ? FNAL Future g-2 provides a unique opportunity, which will have a lasting impact on our ability to understand what we find at the energy frontier Project X? THEORY 40

  40. Backup …

  41. SPS points and slopes • SPS 1a: ``Typical '' mSUGRA point with intermediate value of tan_beta. • SPS 1b: ``Typical '' mSUGRA point with relatively high tan_beta; tau-rich neutralino and chargino decays. • SPS 2: ``Focus point '' scenario in mSUGRA; relatively heavy squarks and sleptons, charginos and neutralinos are fairly light; the gluino is lighter than the squarks • SPS 3: mSUGRA scenario with model line into ``co-annihilation region''; very small slepton-neutralino mass difference • SPS 4: mSUGRA scenario with large tan_beta; the couplings of A, H to b quarks and taus as well as the coupling of the charged Higgs to top and bottom are significantly enhanced in this scenario, resulting in particular in large associated production cross sections for the heavy Higgs bosons • SPS 5: mSUGRA scenario with relatively light scalar top quark; relatively low tan_beta • SPS 6: mSUGRA-like scenario with non-unified gaugino masses • SPS 7: GMSB scenario with stau NLSP • SPS 8: GMSB scenario with neutralino NLSP • SPS 9: AMSB scenario www.ippp.dur.ac.uk/~georg/sps/sps.html

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