1. Muon capture @ PSI Peter Winter University of Washington gPgP L 1A / d R

2. Outline Muon capture on the proton (MuCap) Motivation and general overview Motivation and general overview MuCap experiment MuCap experiment Systematics and results Systematics and results Muon capture on the deuteron (MuSun) Motivation and general overview Motivation and general overview Current status Current status dddd pppp

3. Outline Muon capture on the proton (MuCap) Motivation and general overview Motivation and general overview MuCap experiment MuCap experiment Systematics and results Systematics and results Muon capture on the deuteron (MuSun) Motivation and general overview Motivation and general overview Current status Current status dddd pppp

4. -- pn  - + p  n + M ~ G F V ud ·    (1-  5 )   ·  n (V  -A  )  p q 2 = -0.88m  2 Nucleon form factors

5. Conserved Vector Current and isospin symmetry  g S (q 2 ) = 0 g V, g M : strong program JLab, Mainz,... V  = g V (q 2 )   + i g M (q 2 )   q  /2M N + g S (q 2 ) q  /m  M ~ G F V ud ·    (1-  5 )   ·  n (V  -A  )  p

6. Second class current suppressed by isospin  g T (q 2 ) = 0 g A (q 2 ) measured in neutron decay A  = g A (q 2 )    5 + i g T (q 2 )   q  /2M N  5 + g P (q 2 ) q  /m   5 M ~ G F V ud ·    (1-  5 )   ·  n (V  -A  )  p Nucleon form factors

7. solid QCD prediction via ChPT (2-3% level)solid QCD prediction via ChPT (2-3% level) NNLO < 1%: N. Kaiser, PRC67 (2003)NNLO < 1%: N. Kaiser, PRC67 (2003) basic test of chiral symmetries and low energy QCDbasic test of chiral symmetries and low energy QCD Recent reviews: T. Gorringe, H. Fearing, Rev. Mod. Physics 76 (2004) 31 V. Bernard et al., Nucl. Part. Phys. 28 (2002), R1 Pseudoscalar form factor g P g P (q 2 ) = - - g A (0)m N m  r A 2 2m N m ¹ g A (0) q 2 -m ¼ 2 1 3 g P (q 2 ) = - 2m N m  g A (0) q 2 -m  2 PCAC pole term (Adler, Dothan, Wolfenstein) NLO (ChPT) Bernard, Kaiser, Meissner PR D50, 6899 (1994) g P = 8.26 ± 0.23  pn  W g  NN ff

8. How to access g P ? In principle any process directly involving axial current: -  decay: Not sensitive since g P term ~ q - scattering difficult to measure Muon capture most direct source for g P 

9. Experiments: Observed Processes - Ordinary muon capture (OMC):  - p  n - Radiative muon capture (RMC):  - p  n  -  - 3 He   3 H or other nuclei

10. Experiments: Observed Processes - Ordinary muon capture (OMC):  - p  n - Radiative muon capture (RMC):  - p  n  -  - 3 He   3 H or other nuclei

11. OMC: Methods to measure Neutron experiments: - Measure outgoing neutrons N N - Requires knowledge of neutron efficiency - Separation of decay  's from neutrons - Typical experiments 8-13% precision in  S Lifetime method: -  S  1/  - - 1/  +

12.  Hydrogen density, (LH 2 :  =1) Muon kinetics μ pμ ↑↑ pμ ↑↓ p  T ~ 12s -1  S ~ 700s -1  >0.01 <100ns

13. Muon kinetics pμ ↑↓  S ~ 700s -1 OP ortho (J=1) ppμ   OF para (J=0) ppμ   PF  OM ~ ¾  S  PM ~ ¼  S pp  formation depends on density  pp  formation depends on density  Interpretation requires knowledge of  OM,  PM and OP Interpretation requires knowledge of  OM,  PM and OP

14.  = 1 (Liquid) Rel. Population Time after  p Formation  = 0.01 (~10 bar gas) Time after  p Formation Rel. Population pμ ↑↓  S ~ 700s -1 OP ortho (J=1) ppμ   OF para (J=0) ppμ   PF  OM ~ ¾  S  PM ~ ¼  S

15. Previous results ChPT OP (ms -1 )  Cap precision goal exp theory TRIUMF 2005  p  n @ SACLAY  p   n  @ TRIUMF gPgP no overlap theory, OMC & RMC no overlap theory, OMC & RMC large uncertainty in OP  g P ± 50% large uncertainty in OP  g P ± 50%

16. Requirement of clean target pμ ↑↓  S ~ 700s -1 OP ortho (J=1) ppμ   OF para (J=0) ppμ   PF  OM ~ ¾  S  PM ~ ¼  S  Isotopically and chemically pure H 2, ideally: c d <1 ppm, c Z <10 ppb μd c d c d pd μZ cZcZZcZcZZ dd  Z ~  S Z 4 diffusion

17. Outline Muon capture on the proton (MuCap) Motivation and general overview Motivation and general overview MuCap experiment MuCap experiment Systematics and results Systematics and results Muon capture on the deuteron (MuSun) Motivation and general overview Motivation and general overview Current status Current status dddd pppp

18. MuCap in a nutshell Lifetime method: 10 10  decays   S to 1% precisionLifetime method: 10 10  decays   S to 1% precision Low gas density  Capture mostly from F=0Low gas density  Capture mostly from F=0 Active gas target (TPC)  Clean  stopActive gas target (TPC)  Clean  stop Ultra pure gas system with in-situ monitoring c Z ~ 10 - 30 ppb (Z = N 2, H 2 O)Ultra pure gas system with in-situ monitoring c Z ~ 10 - 30 ppb (Z = N 2, H 2 O) Isotopically pure hydrogen gas c d ~ 100 ppb (deuterium separation)Isotopically pure hydrogen gas c d ~ 100 ppb (deuterium separation)

19. The facility:  E3 beamline at PSI

20. The Kicker Kicker Design at TRIUMFDesign at TRIUMF MOSFET basedMOSFET based 50 ns switching time50 ns switching time

21. Other elements Quadrupoles Detector Separator Separator: Suppression of e + or e - in beam

22.  e

23. TPC - the active target 10 bar ultra-pure H 210 bar ultra-pure H 2 2.0 kV/cm drift field2.0 kV/cm drift field ~ 5.4 kV on 3.5 mm anode half gap~ 5.4 kV on 3.5 mm anode half gap bakeable glass/ceramic materialsbakeable glass/ceramic materials Operation with pure H 2 challenging, R&D @ PNPI, PSI

24. TPC - the active target pp E e-e- --  entrance: lower energy loss  stop: Bragg peak 3d tracking without material in fiducial volume Clean muon stop definition away from high-Z y x z xz projection from anodes and strips zy projection from anodes and drift time xy projection from strips and drift time

25. Lifetime spectra Normalizedresiduals

26. Outline Muon capture on the proton (MuCap) Motivation and general overview Motivation and general overview MuCap experiment MuCap experiment Systematics and results Systematics and results Muon capture on the deuteron (MuSun) Motivation and general overview Motivation and general overview Current status Current status dddd pppp

27. Internal corrections to - (statistical uncertainty of - : 13.7 s -1 )

28. CHUPS c N2, c O2 < 10 ppb Continous H 2 Ultra-Purification System NIM A578 (2007), 485

29. Impurity monitoring 2004 run: c N < 7 ppb, c H2O ~30 ppb 2006 / 2007 runs: c N < 7 ppb, c H2O ~10 ppb Imp. Capture:    Z  (Z-1) n

30. Internal corrections to - (statistical uncertainty of - : 13.7 s -1 )

31. MuCap's unique capability World Record: c d < 100 ppb On site purification since 2006 MuCap 2004 data:MuCap 2004 data: c d = 1.49 ± 0.12 ppm AMS, ETH Zurich AMS, ETH Zurich c d = 1.44 ± 0.15 ppm

32. Precise and unambiguous MuCap result V.A. Andreev et al., Phys. Rev. Lett. 99, 03202 (2007) Using new MuLan   average

33. Recent muon capture review: P. Kammel and K. Kubodera, Ann. Rev. Nucl. Part. Sci., Vol 60 (2010) g P evaluation

34. Final analysis (10 10 muon decays) 50% of final statistics Many hardware upgrades (readout, purification, kicker) 10x higher statistics Analysis far advanced (many subtle effects studied) Unblinding expected in first half of 2011

35. Outline Muon capture on the proton (MuCap) Motivation and general overview Motivation and general overview MuCap experiment MuCap experiment Systematics and results Systematics and results Muon capture on the deuteron (MuSun) Motivation and general overview Motivation and general overview Current status Current status dddd pppp

36. MuSun: "Calibrating" the sun  + d  n + n +  + d  n + n + model-independent connection via EFT & L 1A Aim: Measure rate  d from  d(  ) to < 1.5 %

37. Theory One body currents well definedOne body currents well defined Two body currents not well constrained by theory (short dist.)Two body currents not well constrained by theory (short dist.) Methods:Methods: Potential model + MEC  less or hybrid EFT (L 1A / d R ) Potential model + MEC  less or hybrid EFT (L 1A / d R ) Muon capture soft enough to relate to solar reactionsMuon capture soft enough to relate to solar reactions MEC EFT L 1A, d R

38. Precise experiment needed Potential Model + MEC pionless, needs L 1A hybrid EFT consistent ChPT

39. Outline Muon capture on the proton (MuCap) Motivation and general overview Motivation and general overview MuCap experiment MuCap experiment Systematics and results Systematics and results Muon capture on the deuteron (MuSun) Motivation and general overview Motivation and general overview Current status Current status dddd pppp

40.  d kinetics μ μd ↑↑ μd ↑↓ dμd μZ DD n + n + μ 3 He + n μ + 3 He + n μ + t + p

41.  d(  )  d(  ) dd   He Optimized conditions Clean interpretation at: Clean interpretation at: T = 30 K,  = 5% LH 2 density

42. Cryo-TPC development Cold head Neon condensor Neon heat pipe Vibration-freesupport Cryo-TPC Vacuum vessel

43. Cryo-TPC development 500 Mhz waveform digitization

44. Come by and take a sunny tour.... Current status: T = 30 K T = 30 K HV = 80 kV HV = 80 kV Purity excellent Purity excellent Improved resolution of TPC Improved resolution of TPC

45. Overall summary MuCap: – First precise g P with clear interpretation – Consistent with ChPT expectation, clarifies long-standing puzzle – Factor 3 additional improvement on the way (unblinding in first half of 2011) MuSun – Muon-deuteron capture with 10x higher precision – Calibrates basic astrophysics reactions and provides new benchmark in axial 2N reactions Recent muon capture review: P. Kammel and K. Kubodera, Ann. Rev. Nucl. Part. Sci., Vol 60 (2010)