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Precis ion Muon Capture at PSI

Precis ion Muon Capture at PSI. Peter Kammel Department of Physics and Center for Experimental Nuclear Physics and Astrophysics, University of Washington http:// www.npl.washington.edu / muon /. MuCap. MuSun. Chiral Dynamics, Aug 2012. MuLan. Outline.

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Precis ion Muon Capture at PSI

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  1. Precision Muon Capture at PSI • Peter Kammel • Department of Physics and Center for Experimental Nuclear Physics and Astrophysics, University of Washington • http://www.npl.washington.edu/muon/ MuCap MuSun Chiral Dynamics, Aug 2012 MuLan

  2. Outline • m  e n n Strength of Weak Interaction • MuLanGF • m + p  n + n Basic QCD Symmetries • MuCapgP • m+ d  n + n + n Weak few nucleon reactionsm+ 3He  t+ n and astrophysics • MuSun

  3. Muon Lifetime • Fundamental electro-weak couplings • Implicit to all EW precision physics • Uniquely defined by muon decay GFaMZ 9 ppm  0.6 ppm 0.37 ppb 23 ppm MuLan Collaboration PRL 106, 041803 (2011) Extraction of GF from tm : Recent two-loop calc. reduced error from 15 to ~0.2 ppm q QED

  4. MuLan Final Results t(R06) = 2 196 979.9± 2.5 ± 0.9 ps t(R07) = 2 196 981.2 ± 3.7 ± 0.9 ps t(Combined) = 2 196 980.3 ± 2.2 ps (1.0 ppm) Dt(R07 – R06) = 1.3 ps The most precise particle or nuclear or atomic lifetime ever measured New GF GF(MuLan) = 1.166 378 8(7) x 10-5 GeV-2 (0.6 ppm)

  5. Outline • m  e n n Strength of Weak Interaction • MuLanGF • m + p  n + n Basic QCD Symmetries • MuCapgP • m+ d  n + n + n Weak few nucleon reactionsm+ 3He  t+ n and astrophysics • MuSun

  6. Muon Capture on the Proton • Historical: V-A and m-e Universality • Today: EW current key probe for • Understanding hadrons from fundamental QCD • Symmetries of Standard Model • Basic astrophysics reactions -+ p  m+ n charged current Chiral Effective Theories Lattice Calculations

  7. Capture Rate LS and Form Factors • MuonCapture • Form factors - + p  m+ n rateLSat q2= -0.88 mm2 + second class currentssuppressed by isospinsymm. Lorentz, T invariance • gV, gM from CVC, e scattering • gA from neutron beta decay All form factors precisely known from SM symmetries and data. apart from gP = 8.3 ± 50% 0.45 % 9 % pre MuCap

  8. Axial Vector gA • PDG 2008gA(0)=−1.2695±0.0029 • PDG 2012gA(0)=−1.2701 ±0.0025 • Future ? (Marciano PDG12)gA(0)=−1.275 • Axial Mass • LA= 1 GeVnp, p electro production • 1.35 nuclear targets

  9. Pseudoscalar Form Factor gP • History • PCAC • Spontaneous broken symmetries in subatomic physics, Nambu. Nobel 2008 • State-of-the-art • Precision prediction of ChPT • Foundations for mass generation chiral perturbation theory of QCD gP = (8.74  0.23) – (0.48  0.02)= 8.26  0.23 leading order one loop two-loop <1% • gPexperimentally least known nucleon FF • solid QCD prediction (2-3% level) • basic test of QCD symmetries • recent lattice results Kammel & Kubodera, Annu. Rev. Nucl. Part. Sci. 2010.60:327 Gorringe, Fearing, Rev. Mod. Physics 76 (2004) 31 Bernard et al., Nucl. Part. Phys. 28 (2002), R1

  10. 45 years of effort to determine gP OMC RMC - + p  n +  + g Kammel&Kubodera “Radiativemuon capture in hydrogen was carried out only recently with the result that the derived gP was almost 50% too high. If this result is correct, it would be a sign of new physics... ’’ — Lincoln Wolfenstein (Ann.ReNucl.Part.Sci. 2003)

  11. “Rich” MuonAtomic Physics Makes Interpretation Difficult • Strong sensitivity to hydrogen density f (rel. to LH2) • In LH2 fast ppm formation, but lop largely unknown LT= 12 s-1 Lortho=506s-1 Lpara=200s-1 LS= 710 s-1

  12. Precise Theory vs. Controversial Experiments gP RMC @TRIUMF ChPT OMC@ Saclay TRIUMF 2006 exp theory lOP(ms-1) • no overlap theory & OMC & RMC • large uncertainty in lOP gP  50% ?

  13. MuCap Strategy • Precision technique • Clear Interpretation • Clean stops in H2 • Impurities < 10 ppb • Protium D/H< 10 ppb • Muon-On-Request • All requirements simultaneously

  14. MuCap Strategy Precision technique Clear Interpretation Clean stops in H2 Impurities < 10 ppb Protium D/H < 10 ppb Muon-On-Request All requirements simultaneously • mpnn rare, only 0.16% of menn • neutron detection not precise enough Lifetime method • S= 1/- - 1/+ • measureto 10ppm

  15. MuCap Technique t e m

  16. MuCap Strategy • Precision technique • Clear Interpretation • Clean stops in H2 • Impurities < 10 ppb • Protium D/H< 10 ppb • All requirements simultaneously At 1% LH2 density mostly pm atomsduring muon lifetime

  17. MuCap Strategy • Precision technique • Clear Interpretation • Clean stops in H2 • Impurities < 10 ppb • Protium D/H< 10 ppb • All requirements simultaneously

  18. Muons Stop in Active TPC Target m- to prevent muon stops in walls(Capture rate scales with ~Z4) 10 bar ultra-pure hydrogen, 1.12% LH2 2.0 kV/cm drift field ~5.4 kV on 3.5 mm anode half gap bakeable glass/ceramic materials Observed muon stopping distribution p e- E 3D tracking w/o material in fiducial volume

  19. MuCap Strategy Precision technique Clear Interpretation Clean stops in H2 Impurities < 10 ppb Protium D/H < 10 ppb Muon-On-Request All requirements simultaneously • CHUPS purifies the gas continuously • TPC monitors impurities • Impurity doping calibrates effect anodes time 2004:cN < 7 ppb, cH2O~20 ppb 2006 / 2007: cN < 7 ppb, cH2O~9-4ppb

  20. Experiment at PSI pE3 beamline Kicker TPC Muon On Request Quadrupoles Separator Slit MuCap detector

  21. MuCap Data *V.A. Andreev et al., Phys. Rev. Lett. 99, 03202 (2007) l+ known to 1 ppm fromMuLan

  22. Muon defined by TPC Signals digitized into pixels with three thresholds (green, blue, red) TPC side view Front face view Fiducial volume Fiducial volume TPC active volume TPC active volume muon beam direction transverse direction vertical direction vertical direction

  23. Electron defined by Independent e-Tracker • Small, but significantinterference with m track • simple, robust track reconstruction andits verificationessential

  24. Time Distributions are Consistent fittedlis constant No azimuth dependence 4/6/2012 24 Run groups Data run number (~3 minutes per run)

  25. Start and stop-time-scans consistency

  26. MuCap Results rates with secret offset, stat. errors only

  27. Disappearance rate l

  28. Error budget

  29. Determination of LS molecular formation bound state effect MuCap: precision measurement MuLan LS (MuCap prelim) = 714.9 ± 5.4stat ± 5.0syst s-1 LS (theory) = 711.5 ± 4.6 s-1 Czarnecki, Marciano, Sirlin, RC=2.8%

  30. gP: PreciseandunambiguousMuCapresultsolveslong-standing puzzle gP(MuCapprelim) = 8.04 ± 0.56 gP(theory) = 8.26 ± 0.23

  31. Outline • m  e n n Strength of Weak Interaction • MuLanGF • m + p  n + n Basic QCD Symmetries • MuCapgP • m+ d  n + n + n Weak few nucleon reactionsm+ 3He  t+ n and astrophysics • MuSun Laura Marcucci, Tuesday

  32. Motivation μ- + d  ν + n + nmeasure rate Λdinμd() atom to <1.5% • simplest nuclear weak interaction process with precise th.& exp. nucleon FF (gP) from MuCap rigorous QCD calculations with effective field theory • close relation to neutrino/astrophysics solar fusion reactionpp de+ νd scattering in SNO exp. • model independent connection to μd by single Low Energy Constant (LEC) μ + d determines this LEC in clean 2 N system “Calibrates the Sun” reduce LEC uncertainty from 100% to ~20%

  33. Precise Experiment Needed

  34. Muon Physics and Interpretation complex, can one extract EW parameters ? • Precision technique • Clear Interpretation • Clean stops in D2 • Impurities < 1ppb • H/D < 100 ppb Optimal conditions Muon-Catalyzed Fusion Breunlich, Kammel, Cohen, LeonAnn. Rev. Nucl. Part. Science, 39: 311-356 (1989)

  35. Precise Experiment Possible? • Precision technique • Clear Interpretation • Clean stops in D2 • Impurities < 1ppb • H/D < 100 ppb Active muon target

  36. MuSun Detector System Electron Tracker Liquid Ne Circulation CryoTPC TPC Digitizer Electronics Impurity filtering

  37. Fusions in TPC run2011, prelim mSC 3He  robust muon tracking algorithm at 10-5 level required ! t+p mSC 2 ms

  38. Status and Plans Analysis • analysis run 2011 data 4.8 x 109goodμ- stop 4 x 108μ+ stopevents • first physics publication • study detector upgrades Upgrades detector upgrades 2012 • cryo preamp • TPC optimization • improved purity and monitoring New beam line at PSI Commissioning run 2012 Final runs 2013-14 extendedπE1 oldπE1

  39. Summary: Evolution of Precision =8.04 ± 0.56 (mp)= 8.2 ± 0.7 (m3He exp+MKRSVtheo) in progress complete future complete

  40. Collaborations MuLan Boston University, USA University of Illinois at Urbana-Champaign, Urbana, USA James Madison University, Harrisonburg, USA University of Kentucky, Lexington, USAKVI, University of Groningen, Groningen, The Netherlands Paul Scherrer Institute (PSI), Villigen, Switzerland Regis University, Denver, USA University of Washington, Seattle, USA MuCap/MuSun Petersburg Nuclear Physics Institute (PNPI), Gatchina, RussiaPaul Scherrer Institute (PSI), Villigen, Switzerland University of California, Berkeley (UCB and LBNL), USA University of Illinois at Urbana-Champaign, Urbana, USA University of Washington, Seattle, USA UniversitéCatholique de Louvain, BelgiumUniversity of Kentucky, Lexington, USABoston University, USA Regis University, Denver, USA University of South Carolina, USA Supported by NSF, DOE, Teragrid, PSI and Russian Academy Science

  41. Backup

  42. Extinction ~ 1000 Accumulation Measuring Period 450 MHz WaveForm Digitization The MuLan experimental concept… 170 Inner/Outer tile pairs Real data Kicker On Measurement Period Number (log scale) time Fill Period -12.5 kV 12.5 kV Detector has symmetric design around stops

  43. Brendan Kiburg, University of Washington

  44. Brendan Kiburg, University of Washington

  45. Brendan Kiburg, University of Washington

  46. Brendan Kiburg, University of Washington The interference is time- and space-dependent N Blue Pixels N Blue Pixels

  47. First MuSun Production Run Performance 12 weeks incl. setup & tests in 2011 4.8 x 109goodμ-stops 4 x 108μ+ stops in fiducial vol. withdecayelectron 21.2 TB μ- & 2.5 TB μ+of clean data Importantupgradesbeforerun • producednew hydrogen-depleted deuterium gas (cp < 10-4) • stable HV at 80 kV (nosparks) • improvedfrontendelectronics • gas chromatography w. online sampling • new X-raydetectors (Ge, NaI) • drifttime effect impuritycontrol

  48. Muons in TPC run2011, prelim mSC m 2 ms m

  49. MuLan Final Errors and Numbers ppm units t(R06) = 2 196 979.9± 2.5 ± 0.9 ps t(R07) = 2 196 981.2 ± 3.7 ± 0.9 ps t(Combined) = 2 196 980.3 ± 2.2 ps (1.0 ppm) Dt(R07 – R06) = 1.3 ps New GF GF(MuLan) = 1.166 378 8(7) x 10-5 GeV-2 (0.6 ppm)

  50. Comments • Determination of gP • exp. precision at two-loop level • larger gA would shift LS(theory) from 711 to 716 • Using gP from HBChPT • CPT test: tm+ - tm- @ 20 ppm • gpNN from MuCap • 2nd class currents, beyond standard model couplings

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