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

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

Historical Evolution CERN ICERN IICERN IIIBNLGOAL 3

HVP is determined from data

A world-wide effort exists to measure over full range

HVP evaluations by 2 groups, updated Tau’10 n Hagiwara, Liao, Martin, Nomura, Teubner (HLMNT) n M. Davier, A. Hoecker, B. Malaescu, Z. Zhang (DHMZ) u (BaBar team with access to preliminary data) a  exp – a  SM = (296 ± 81)  10 –11  3.6  Biggest difference is from high multiplicity states now measured at BaBar; > 1 GeV region  Reduces cross sections a  exp – a  SM = (259 ± 81)  10 –11  3.2 

The new HVP evaluations also affect  QED running … and enter the global electroweak fits … Big shift !

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

Theory uncertainty = 51 x (0.44 ppm) Experimental uncertainty = 63 x (0.54 ppm) 0.46 ppm statistical  limit was counts 0.21 ppm precession systematic 0.17 ppm field systematic The values & the new experimental goal Leads to  a  (Expt – Thy) = 297 ± 81 x  BNL E821 Experimental goal: 63  16 x Theory uncertainty expect: 51  30 x Leads to  a  (Expt – Thy) = XXX ± 34 x If central value remained,  a  would exceed 8 

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

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

13 SUSY contribution to a μ : difficult to measure at LHC Related processes in SUSY: Lepton Flavor Violation MEG Mu2e & COMET

Connection between a , EDM and the charged Lepton Flavor Violating transition moment  → e  → e a  (real) EDM (imaginary) SUSY slepton mixing

Note:  a  centered at 255 here SUSY and g-2: The power to resolve among models and break LHC degeneracies

16 Suppose the MSSM point SPS1a is realized and the parameters are determined at LHC- sgn(  gives sgn(  ) sgn (  ) difficult to obtain from the collider tan  poorly determined by the collider Assuming SPS1a; 100 fb -1 at 14 TeV LHC (Sfitter) Old g-2 New g-2  

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

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

ParameterFNAL/BNL p / fill0.25  / p 0.4  survive to ring 0.01  at magic P 50 Net0.05 The 900-m long decay beam: reduced flash; more store  /p Stored muons / POT Parameter BNL FNAL Gain FNAL/BNL Flash compared to BNL

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) P  magic momentum = GeV/c E field doesn’t affect muon spin when  = 29.3 (4) Parity violation in the decay gives average spin direction     µ 20

The anomaly is obtained from three well- measured quantities

The Storage Ring exists. It will be moved to FNAL

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

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

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

New tools allow us to simulate modified kicker pulse shapes and predict storage improvements Real LCR Kick Ideal Square Kick % stored

- p. 27/25 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

Improvement of Field by Shimming shimming At this level, one hardly needs to know the muon distribution

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

An “event” is an isolated positron above a threshold. e+e+ digitized samples N A NA 2 =0.4

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

Traditional method of determining  a is to plot Number of events above threshold vs. Time Event Method Geant N A NA 2 =0.4 Here, Asym is the average asymmetry of events above energy threshold cut

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

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

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

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

The Ring Assembly 37

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

39 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

40 Summary 30x P-989 goal 16x FNAL Future 15x Project X? 8x Project X ? 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 THEORY g-2 provides a unique opportunity, which will have a lasting impact on our ability to understand what we find at the energy frontier 40 ?

41 Backup …

SPS points and slopes n SPS 1a: ``Typical '' mSUGRA point with intermediate value of tan_beta. n SPS 1b: ``Typical '' mSUGRA point with relatively high tan_beta; tau- rich neutralino and chargino decays. n 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 n SPS 3: mSUGRA scenario with model line into ``co-annihilation region''; very small slepton-neutralino mass difference n 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 n SPS 5: mSUGRA scenario with relatively light scalar top quark; relatively low tan_beta n SPS 6: mSUGRA-like scenario with non-unified gaugino masses n SPS 7: GMSB scenario with stau NLSP n SPS 8: GMSB scenario with neutralino NLSP n SPS 9: AMSB scenario