Scientific motivation Conceptual plan and technical requirements

1. e Momentum Spin A proposal to measure the muon anomalous magnetic moment to 0.14 ppm precisionThe New g-2 Collaboration • Scientific motivation • Conceptual plan and technical requirements • FNAL is the right place to do this • Cost and timescale D. Hertzog and L. Roberts – PAC Fermilab – March 6, 2009

2. Built on the foundation of E821, with important new strength added a @ 20 Institutions

3. 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 100- and 10-x better than proposed precision Known  current precision; Expect ~40% reduction in the future dam = 51 x 10-11 arXiv:0809.3085 Eduardo De Rafael (CPT)

4. Where we are and where we are going • Present Status: • Experimental uncertainty = 63 x 10-11 (0.54 ppm) • 0.46 ppm statistical • 0.28 ppm systematic • Theory uncertainty = 51 x 10-11 (0.44 ppm) Leads to Dam(Expt – Thy) =295 ± 81 x 10-11 3.6 s Limit was counts • Proposal: • Experimental uncertainty 63  16 x 10-11 • 0.1 ppm statistical  21x the E821 events • 0.1 ppm systematic overall • 0.07 ppm field  0.17  0.07 • 0.07 ppm wa0.21  0.07 • Theory uncertainty: 51  30 x 10-11 Future: Dam(Expt – Thy) =xx ± 34 x 10-11 (If xx remains 295, the deviation from zero would be close to 9s)

5. 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 • Extended technicolor or generic models with naturally vanishing bare muon mass, • Implies L mass scale very large • 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 “Un-invented” – perhaps most importantly, sets a stringent experimental constraint for any new models

6. SUSY: Muon g-2 is very sensitive through loops, which are amplified by tanb Difficult to obtain at the LHC R-parity conserving Supersymmetry (vertices have pairs) See full Topical Review: D. Stöckinger J.Phys. G34 (2007) R45-R92

7. UED The Snowmass Points and Slopes are 10 representativeSUSY models with typical parameters for MSUSY masses and tanb, etc. They serve as test points to indicate the discrimination power of experiments. Muon g-2 is a powerful discriminatorno matter where the final value lands Illustration of “resolving power” among SUSY models Present Present Future? Universal Extra Dimensions 1D Model SPS Definitions

8. Suppose the MSSM reference point SPS1a* is realized and parameters determined by global fit (from full LHC results) • sgn(m) difficult to obtain from the collider • tanbpoorly determined by collider New g-2  Old g-2  LHC 10.2 ± 4.5(Sfitter) 2s 1s g-2 is complementary to the LHC * SPS1a is a ``Typical '' mSUGRA point with intermediate tanb = 10

9. Typical CMSSM 2D space showing g-2 effect(note: NOT an exclusion plot) Present: Dam = 295 ± 88 x 10-11 Here, neutralino accounts for the WMAP implied dark matter density scalar mass 2s Excluded for neutral dark matter gaugino mass This CMSSM calculation: Ellis, Olive, Santoso, Spanos. Plot update: K. Olive Topical Review: D. Stöckinger hep-ph/0609168v1

10. Typical CMSSM 2D space showing g-2 effect(note: NOT an exclusion plot) Future Dam = 295 ± 34 x 10-11 Here, neutralino accounts for the WMAP implied dark matter density Historically muon (g-2) has played an important role in restricting models of new physics. It provides constraints that are independent and complementary to high-energy experiments. scalar mass Excluded for neutral dark matter gaugino mass With new experimental and theoretical precision and same Dam This CMSSM calculation: Ellis, Olive, Santoso, Spanos. Plot update: K. Olive Topical Review: D. Stöckinger hep-ph/0609168v1

11. SUSY slepton mixing m→ e MDM, EDM ~ ~ Connection between MDM, EDM and the charged Lepton Flavor Violating transition moment m → e

12. The keys to a more precise experiment involve more stored muons and reduced systematic errors • Build on a proven formula • E821  studies to improve at BNL, J-PARC, or FNAL  P989 • Many studies completed, much documentation • Shovel ready experiment • Why FNAL is uniquely appropriate • Runs parasitically with high-energy neutrinos • Efficient use of facility • Proton intensity and beam structure ideal for required statistics • 1.8 x 1011 events in final fits • Reduced hadronic-induced background at injection • Long decay beamline is key to reducing many systematic errors • Increased fill frequency reduces instantaneous rate • x4 at FNAL compared to BNL • Longer running period available • High statistics, many systematic runs possible • Synergy with new and future laboratory direction in “intensity frontier” • Many beam developments will aid in Mu2e development

13. Double Blind Analysis The measurement involves determining 3 quantities to high precision (1) Precession frequency (2) Muon distribution (3) Magnetic field map B

14. n p+ m+ 4 key elements of the g-2 measurement • Polarized muons forward decays, captured in FODO, ~97% polarized source • Precession proportional to (g-2) • Pm magic momentum = 3.094 GeV/c E field doesn’t affect muon spin when g = 29.3 • Parity violation in the decay gives average spin direction µ

15. Uses 6/20 batches parasitic to n program Proton plan up to AP0 target is almostthe same as for Mu2e Uses the same target and lens as the present p-bar program Modified AP2 line (+ quads) New beam stub into ring Needs simple building near cryo services Polarized muons delivered and stored in the ring at the magic momentum, 3.094 GeV/c

16. The 900-m long decay beam reduces the pion “flash” by x20 and leads to 6 – 12 times more stored muons per proton (compared to BNL) Flash compared to BNL Stored Muons / POT

17. incoming muons Quads The Storage Ring exists and will be moved to FNAL Power supplies Quads Vacuum system Fiber harps Kickers

18. Into the ring AP-3 stub • Beamline “stub” Design for FNAL • Open-end inflector* x2 increase in transmission • Kicker deflects beam onto orbit Improvements planned for pulse shape / magnitude Existing Proposed *This was built at one-third length, tested, but final design had closed ends

19. NA2 2.5 ns samples N A <A>=0.4 An “event” is an isolated electron above a threshold. Segmented detectors and modern electronics will record more complete data stream and reduce pileup e+

20. 2.5 ns samples An “event” is an isolated electron above a threshold. Segmented detectors and modern electronics will record more complete data stream and reduce pileup e+

21. Segmenting detectors will reduce pileup. New W-SciFi calorimeter built and tested (and published) • 20-fold segmentation for PMTs • 0.7 cm X0 • 10% resolution at 2 GeV • R&D option, 35-fold segmentation using onboard SiPM Low E High E

22. Geant simulation using new detector schemes Event Method NA2 N A <A>=0.4 Traditional method of determining wa is to plot Number vs. Time Here, Asym is the average asymmetry of events above energy threshold cut

23. Geant simulation using new detector schemes Event Method Same GEANT simulation Energy Method A complementary method of determining wa is to plot Energy vs. Time Here, all events that hit detectors contribute

24. 1 ppm contours The magnet will be carefully shimmed and precisely mapped Measured in situ using an NMR trolley Continuously monitored using 366 fixed probes mounted above and below the storage region (Final BNL) ppm 0.05 0.09 0.05 0.07 0.10 0.17

25. g-2 budget estimate; contingencies included(assumed protons are delivered to AP0 at 15 Hz operation of booster) Relatively standard beamline elements Ring relocation NSF+Intl. PROTONs; 15 Hz Booster assumed covered by stimulus package g-2; perhaps Mu2e Mu2e & g-2 common

26. Technically driven schedule • March 2009 • Scientific approval • Summer 2009 • CD0 and some R&D funds made available • Summer 2009  Year 0 [ at least 1 year ] • Planning / designs / technical reviews • CD#’s as required • Year 1 (with modest $) • Building started  key driver for timeline • Modifications of proton complex • Pack and move ring and other items from BNL • Detector, electronics tests and pre-construction • Special beam rate tests • Year 2 • Install and assemble ring at FNAL • Complete modifications of beamlines related to g-2 • Special rate tests of pion / muon flux at key test points • Detector, electronics production • Year 3 • Complete ring construction and commission • Shim magnet (9 mo) • Calibrations of detectors, integrate counting room, DAQ • Year 4 • Physics commissioning • Start real data taking A fairly uniform flow of funds is required … no big “spike” for any single purchase

27. Immediate R&D tasks • Lithium lens at 18 Hz • Test lithium lens for 18 Hz operation at the reduced power for 3.1 GeV/c beam • Decay channel and stored muon simulations • Complete end-to-end beam simulation to make the most complete and cost-effective choices for • Optimization of the beam focus on the target and Li lens optics • Addition of quads for AP2 beam line and transport efficiency thru AP-3 • Design of beamline stub into ring • Storage ring acceptance versus kicker performance • Half-length kicker plate test • Reduced inductance is key to shorter pulse of greater magnitude; carry out test with a half-length kicker in lab on existing setup • Tracking of the magnetic field • Re-optimize fixed probe locations to increase the number of working fixed probes • Large-scale W/SciFi prototype with SiPM readout • Full-scale prototype; PMT and SiPM readout. • In-vacuum straw chambers for EDM and traceback • A test setup is underway now at FNAL to investigate this concept.

28. Summary • Unique physics opportunity with decades-long track record of being important and influential to our field, including > 1400 citations (170 in 2008) • Will provide important constraints on the interpretation of any new physics found at the LHC or elsewhere. • Window of opportunity after Tevatron completion and before the major Mu2e and DUSEL projects take center stage • Great return on investment, given the impact and the natural alignment with FNAL’s future UED g-2 can help distinguish BSM possibilities SUSY

29. Possible topics for further discussion • Theory • Current / future status of Hadronic Vacuum Polarization • Current / future status Hadronic Light-by-Light • Magnetic field shimming and monitoring • What are the SPS points? • Show us more about the Sfitter results w/wo g-2 • How general is the UED “tiny effects” prediction? • Technique • More on a parasitic EDM measurement • Why a longer beamline? • What drives the detector choice? • Beamline and more muons • How was the event rate obtained? • What is involved in moving the ring? • Other • More on yellow “proton complex” budget box • What about JPARC? D. Hertzog and L. Roberts – PAC Fermilab – March 6, 2009

30. Back error2 (from F. Jegerlehner) contribution Analyticity and the optical theorem: • Future efforts will reduce errors • Additional KLOE data (in hand, near term) • CMD3 at VEPP2000, up to 2.0 GeV (next 5 years) • perhaps Belle

31. Back |Fp |2 from KLOE, CMD2 and SND agree well weighted contribution recall that:

32. Back Suppose the hadronic contribution increased to remove the difference? • A similar dispersion integral enters elsewhere • Increasing s (s) to remove the (g-2) difference lowers the Higgs mass limit PRD 78, 013009 (2008) • This cross section is important for am and for any precision EW physics. • Future work continues in Frascati and Novosibirsk. Belle is also beginning to explore this possibility.

33. Back arXiv:0901.0306v1 Note, with Dam = 295 x 10-11 … If HLBL is the source of the difference with SM, it would need to increase by 11 s .... Dynamical models with QCD behavior

34. Back The p0 (Goldstone) contribution fixes sign of the contribution From cpt and large Nc QCD • The magnitude of the HLBL is about the same as the magnitude of the 3-loop HVP which can be calculated from the dispersion relation. • It’s hard to believe that the HLBL would be huge compared to the other 3-loop contributions. Examples of other 3-loop hadronic contributions:

35. Back How general is the UED “tiny effects” prediction? • UED models (1D) typically predict “tiny” effects • Incompatible with a Dam of ~ 300 x 10-11 The statement refers to the UED models originally proposed and studied by Appelquist, Cheng, and Dobrescu, and also by Rizzo in 2000/2001. The results for g-2 in the UED models with one extra dimension is (according to these references) below 50 x 10-11 as written in our proposal. While there might be modified UED models with larger contributions to g-2, this again demonstrates that g-2 is very powerful tool to discriminate between different new physics models. (D. Stockinger)

36. Back Sfitter LHC global fit (Alexander, Kreiss, Lafaye, Plehn, Rauch, Zerwas; Les Houches 2007, Physics at TeV Colliders) Result for the general MSSM parameter determination at theLHC in SPS1a. Flat theory errors (non-gaussian) are assumed. The fit is done with and without inclusion of the current measurement of g-2. With g-2, many are improved, some significantly

37. Back 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 SPS PLOT www.ippp.dur.ac.uk/~georg/sps/sps.html

38. Parasitic Muon EDM Measurement using straw tube arrays Back arXiv:0811.1207v1 The EDM tips the precession plane, producing an up-down oscillation with time (out of phase with wa) E821 straw-tube array Measure upward-going vs. downward-going decay electrons vs. time with straw tube arrays

39. Back E821 Data:up-going/down-going tracks vs. time, (modulo the g-2 frequency): • BNL traceback measurement was entirely statistics limited • 1 station • Late turn-on time • Small acceptance • Ran 2 out of 3 years EDM (g-2) EDM Signal: Average vertical angle modulo g-2 period. Out-of-phase by 90° from g-2; this is the EDM signal (g-2) signal: # Tracks vs time, modulo g-2 period, in phase.

40. Back The new idea imagines in-vacuum straws, matched with out-of-vacuum pre-calorimeter straws (used also for shower impact) Out-of-vacuum straws / impact detector We are already studying at FNAL, in-vacuum straw chambers for “traceback” systems on many of the stations, which will serve as EDM measurement stations as well

41. Back How was event rate obtained? Proton complex parameters and plans Compared to achieved BNL stored muon per proton rate and detailed factors for beamline differences Monte Carlo and simple calculations This is the key factor. We have calculated 11.5 so far, so we have included a “100% contingency” in estimating the beam time request to allow for something to go wrong. MARS model of target, beamline simulation to capture / decay pions

42. Back The Precision Field: Systematic errors • Why is the error 0.11 ppm? • That’s with existing knowledge and experience • with R&D defined in proposal, it will get better Next (g-2)

43. Back What drives the detector choice? • Compact based on fixed space • Non-magnetic to avoid field perturbations • Resolution is not critical for dwa • Useful for pileup & gain monitoring • E821 “8%”; We propose 10% for tungsten-based calorimeter • Pileup depends on signal speed and shower separation • 4/5 events separated was goal • GEANT sim work in good shape Many more details and studies available. See also,

44. Back Benefits of a longer beamline • Reduced pions • Permits “forward” decays • Collects “all” muons • Eliminates “lost muon” systematic from muons born just prior to the ring

45. Back Ring relocation • Heavy-lift helicopters bring coils to barges • Rest of magnet is a “kit” that can be trucked

46. Back The “yellow” budget box is related to accelerator improvements for the intensity frontier in general • Recycler Ring RF • For g-2: makes 4 mini bunches out of each booster injection. Each is then extracted for g-2 as a whole to strike the target and make a pion/muon bunch • For Mu2e: “could” be used to alleviate concern about space charge limits, but has adverse affect of raising instantaneous rate. This issue is being discussed between the accelerator group and the collaboration. The accelerator group recommends using this scheme if rates can be handled Stimulus packg see below Must do for Mu2e, g-2 and any other expt.

47. Back P5 suggested we “determine the optimal path toward a next generation experiment” by examining JPARC and FNAL • Feb. 2008 • Technical note sent to P5 by collaboration outlining generic comparisons (and some rough cost considerations) • June 2008 • 2-day, joint Japan / US collaboration meeting held to examine technical possibilities at three labs (BNL, FNAL, JPARC). • Conclusions • It is difficult to stage the “magic g” experiment at JPARC. Real estate exists only for a short backward decay beamline. • Need bunch splitting to achieve h = 90 which is difficult • J-PARC regulations for cryogenics (probably) prohibit SC coil design from E821 to be used. Coils would have to be rebuilt from scratch at J-PARC at significant cost • Single user mode, so flux delivered in very intense period for small fraction of a year, certainly less attractive than FNAL running scheme • Current thoughts for JPARC • “Small ring” idea being explored off Booster. The idea is in its infancy. E821 collaborators who have considered it have raised a number of significant issues which will be difficult to solve. • Possible future focus on small ring dedicated EDM effort has significant promise and has been strongly encouraged by E821 colleagues

48. Back Beamline considerations