Discussion guide: Next-generation muon g-2 David Hertzog & Lee Roberts for the E969 Collaboration

1. Discussion guide: Next-generation muon g-2David Hertzog & Lee Roberts for the E969 Collaboration • Status • From BNL E969 to Legacy experiment • Work plan requirements • Steve Vigdor: My goal for the proposed meeting … • Get a feeling for the level of resources that would be needed to mount a serious effort, • Whether there might be accelerator R&D funds to be sought, • What the impact might be on other C-AD projects, • How the g-2 collaboration would join in feasibility determination, etc.  This will all be necessary input to any decision regarding a go ahead or priority for the preparatory work to design a "legacy" measurement that improves the current g-2 result by something on the order of a factor of 5. 

2. Date 3.4 s Dam(expt-thy) = (29.5±8.8) x 10-10 (3.4 s) The science is now more compelling than ever Based on de Rafael’s theory summary (2007), using inputs from Davier (2006) and HMNT (2006). Rep.Prog.Phys. 70, 795 (2007).

3. A worldwide effort continues with the aim of improving the Standard Model uncertainty … • CMDII, SND – direct e+e- annihilation • Future: VEPP 2000 being commissioned … up to 2 GeV • KLOE, BaBar, Belle – radiative return e+e- annihilation • Multi-hadron final states • 2p is still to be announced … maybe this year • Belle, BaBar – hadronic tau decays (CVC tests) • Nio, Kinoshita, et al: 8th order QED and beyond • Many HLbL papers and debate  will increase in importance soon • Here, expect new efforts will be required and on implications for the New Standard Model • SUSY – See Stockinger review (2006) • Extra Dimensions • other

4. Topical Workshop on The Muon Magnetic Dipole Moment (g-2)m 25 and 26 October 2007School of Physics and AstronomyThe University of Glasgow A Workshop is planned to assemble all theory aspects, both SM and beyond SM, and to update the prospects for a new measurement. Lee and Dave will present the experimental situation. Clearly, we would like to send a message to the theory community that there is hope for an improved experiment

5. P3: Proposal / Politics / Planning • Fall 04: E969 Proposal approved • Goal: 0.2 ppm (0.14 ppm statistical) • Concept involves backward decay beam and novelanalysis ideas • Dec 04: T. Kirk letter to DOE outlining project • Feb 06: Director’s Review at BNL (Aronson) • Updates of proposal since submission • Beamline studies; BNL costing - post RSVP; Detector testing; … • Mar 06: P5 Panel hears presentation by Roberts • Goal: 0.25 ppm • Cost: ~$40 M (including running costs and AGS rehab costs) • Concept is relatively conservative extension of E821 • Sept 06: P5 report lists g-2 4th … after LHC start • Fall 06: Updated HVP theory  3.4 s effect • May 07: Nuclear LRP endorsement • Aims at “Legacy” experiment (we will define this) • Project part of New Standard Model Initiative • Positive expectation shifts concerning • Running costs • DOE NP support • Joint funding by NP and HEP agencies • Today: First discussion of how to proceed

6. Major existing resource: The BNL Storage Ring Cryo plant upgrade is a big item in the costing; “mothball” maintenance is also a concern

7. 2ND Major Resource: Collaboration Expertise Boston University Brookhaven National Laboratory Budker Institute of Nuclear Physics UC Berkeley and LBL Cornell University University of Illinois at Urbana-Champaign James Madison University KVI Groningen University of Kentucky University of Minnesota Osaka University Regis University University of Virginia Yale University

8. Original proposal: More Muons. Our plan in 5 steps Open inflector 3 New high-momentum pion arc 1 2 Quad doubling • x 5 more muons • Pion flash reduced (eliminated) • Segmented detectors • Systematics reduced 5 4 Segmented detectors Improved kicker

9. The P5 version was more conservative to hold to a smaller $ envelope and to reduce technical risk • Features – forward decay Pp = 1.03 Pmagic • No backward beam • new arc not well enough designed to cost or simulate • x 4 quads in FODO (x2 over proposal) • Open inflector • Increase AGS intensity by 10-20% over E821 • Uncertainties and risks • Muon storage rate based mainly on simulations • Pion background reduction estimated • Little margin of error in beam increase of x4-5 YearWks w/RHICPhysics WksCost (M$) 1st 12 3 $ 5.8 2nd20 15 $ 7.8 Total 34 18 $ 13.6 ~ $14 M equipment ~ $12 M for AGS ~ 14 M running costs

10. Nuclear Physics Long Range Plan Meeting encourages “Legacy” experiment: • Tentative Experimental Goal: • 0.1 ppm statistical error (~21 x the fitted muons in E821) • 0.1 ppm overall systematic (e.g., ~0.07 ppm each on wa and wp) • Total 0.14 ppm final error x 4 improvement over 0.54 ppm E821 • We are aiming at this benchmark • Can it be achieved at all ? We think “yes” • Recall that of the ~$40 M, only $14 (~1/3rd) was experimental equipment and beamline. • The other costs – AGS upgrade and running – do not necessarily increase in this more ambitious plan. • What is this plan? “… the proposed scheme concludes the logical sequence of seminal ideas from pion injection, to muon injection and finally to muon accumulationbefore injection, which were instrumental for the spectacular improvements in the precision of the muon anomaly over the last 40 years.” -- Beam study note in progress P. Kammel et al

11. E969 + BNL, together Legacy Plan • Muon Accumulator Ring (MAR) • Open inflector • Quad doubling • Kicker improvement • Improved scraping scheme • AGS multi bunch (12  36 or more) • Critical to lower instantaneous intensity • Segmented detectors • Modern DAQ, electronics • Field probe improvements • Shimming improvements • Q method, dual analysis Figure of Merit ~ x20 over E821 Increases m% stored Decreases m % stored Collaboration tasks

12. MAR:Muon Accumulator Ring Simple sketch • Studies to do: • Practical lattice layout • Fast kicker • Selection of real elements • Practical floorplan • Shielding Strawman design p/m Fluxes and Figure of Merit p/m Overkill Double Achromat m p

13. KICKER: Present kick shape is too wide and magnitude is too low:Only a few % are stored. In principle this can double (or more) incoming muons Quads BNL & Collab BNL Engineering and Modeling efforts needed

14. Multi-bunch • E821: 12 bunches per supercycle • Instantaneous rate on calorimeters ~few MHz • Hadronic flash created large baseline shift • E969: 36 bunches ? • Muon rate scales up ~10-15 • Multibunch reduces rate by ~3 • Segmentation reduces rate by ~3 • Hadronic flash absent Net effect: ~ same as E821

15. Optimistic Summary Preliminary Huge improvement due to MAR needs confirmation and conceptual design

16. The path forward • Tasks involving BNL • Steve, Lee, Dave meet with DOE NP & HEP (and possibly NSF), sometime in coming months • BNL provides development expertise in several key technical areas: • MAR conceptual design • g-2 Storage Ring Kicker pulse and/or plates re-engineering (conceptual) • Reality of multi bunch • Beam dynamics in the muon storage ring • Tasks for the Collaboration • Develop integrated muon transport simulations • Continue detector development • Evaluate systematic error task for 0.07 ppm level goal • Communications … toward a TDR • Teleconferences • Collaboration meeting at BNL early 2008 with progress reports due

17. Return to Steve’s Meeting goals: • Get a feeling for the level of resources that would be needed to mount a serious effort • AGS booster rehab + ES&H ~ $12 M (unchanged) • Experiment ~ $14 + MAR • Running scenario could remain approximately the same: • Debug using occasional shots during RHIC running • Engineering run ~6 weeks • Production run ~20 weeks • Whether there might be accelerator R&D funds to be sought, • BNL internal … highly welcome with obvious targets • What the impact might be on other C-AD projects, • BNL internal …

18. Return to Steve’s Meeting goals: • How the g-2 collaboration would join in feasibility determination, etc. • Close collaboration between Lab and Collaboration on MAR and beamline issues, g-2 kicker re-engineering, etc. • Suggest working teams with specific names attached • Define target date for progress reports including updated costing • Some items are limited to the Lab: AGS re-bunching, physical layout of MAR on site; shielding and other safety impacts. • Collaboration advances usual specific responsibilities related to executing the experiment: detectors, electronics, DAQ, systematics, simulations, field measurements, shimming, etc. • To revitalize efforts, some agency or laboratory funding is likely required. We need a “message” we can send to Collaboration and use with funding agencies and International collaborators.

19. Extra slides follow

20. Far Side Near Side This baseline limits how early we can fit data E821 used forward decay beam, which permitted a large p component to enter ring DP ~ 1.7% Pions @ 3.115 GeV/c Decay muons @ 3.094 GeV/c

21. Approximately the same muon flux is realized, but studies continue on this Both Sides Expected No hadron-induced prompt flash x 1 more muons ??? “Plan A” for the new experiment uses a backward decay beam with large mismatch in p/m momentum Pions @ 5.32 GeV/c Decay muons @ 3.094 GeV/c