1. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 1 Precision Studies on Strong Interaction in Pionic Hydrogen J. Marton Stefan Meyer Institut (SMI) / ÖAW on behalf of the Pionic Hydrogen Collaboration @ PSI Coimbra – Debrecen – Ioannina – Jülich – Paris – PSI – SMI/Vienna

2. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 2 Outline Motivation Pionic hydrogen: Cascade Scattering lengths Layout of the experiment Measurements Preliminary results: Shift, width Summary and outlook

3. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 3 Physics Goals  N coupling constant (using Goldberger Miyazawa Oehme sum rule) pion-nucleon sigma term (measure of chiral symmetry breaking) High precision values for the hadronic shift ε 1s and width  1s of the 1s ground state of pionic hydrogen  p  pion-nucleon scattering lengths (isoscalar, isovector) with an accuracy at the percent level scattering lengths  basis for comparison of changes in the nuclear medium

4. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 4 Electromagnetic Cascade of  p  precise QED calculations ~ 10 -3  advanced cascade theory  p is not an isolated system  interaction with hydrogen atoms QED n n -1 I = 0 12 1 2 3 4 ~16 π 0 n + γn Stark mixing E Kα ~ 2.5 keV QED + Strong interaction X-ray transitions external Auger transitions Coulomb transition

5. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 5 Strong Interaction in  p Principal interaction: electromagnetic Transition energies 4p-1s, 3p-1s, 2p-1s (QED) TransitionEnergy [eV] QEDEnergy [eV] QED + strong interaction 2p – 1s2429.5062436.614 3p – 1s2878.8082885.916 4p – 1s3036.0943043.202

6. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 6 Extraction of a + and a -   = (-7.2  2.9) 10 -2 J. Gasser et al., Eur. Phys. J. C26 (2003) 13   = (0.6  0.2) 10 -2 P. Zemp, Proc. Workshop Hadatom05 Accuracy of a + strongly dependent on  ! Deser formulae:

7. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 7 Pion-Nucleon Scattering Lengths shift data from pionic hydrogen and pionic deuterium, width from pionic hydrogen (Schröder et al.,2001) Tomozawa-Weinberg – current algebra (chiral limit) a + = 0 a - = 0.079 m  -1

8. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 8 Scheme of Experimental Set-Up high stop density  high X - ray line yields  bright X - ray source position & energy resolution  background reduction by analysis of CCD hit pattern spherically bent Bragg crystal ultimate energy resolution

9. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 9 Set-Up at PSI crystal spectrometer spherically bent crystals CCD X-ray detector 2  3 matrix X-ray tube cryogenic target cyclotron trap II

10. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 10 Experimental Method Bragg crystal CCD X-ray detector Target and cyclotron trap

11. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 11 Cyclotron Trap -Target - Degraders X - rays   beam    stop efficiency f stop  density  1% @  stp 10 9  /s super-conducting split coil magnet

12. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 12 Spherically Curved Bragg Crystal 100 mm 

13. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 13 Large - Area Focal Plane CCD Detector N. Nelms et al., Nucl. Instr. Meth 484 (2002) 419 2  3 CCD 22 array pixel size 40  m  40  m 600  600 pixels per chip operation at – 100°C   150 eV @ 4 keV  X  90% image area storage area flexible boards cooling (LN 2 )  

14. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 14  high pion flux in  E5 at PSI p  =112 MeV/c, ~ 10 9  - /s  cyclotron trap for small stop volume and high stopping efficiency  Light weight cryogenic target for wide density range  spherically bent Bragg crystals characterization by ECRIT X-ray source  position sensitive X-ray detection with CCD array: CCD-22 background reduction by shielding and pixel analysis of CCD data  calibration lines (pionic oxygen) measured in parallel Features of the Experiment

15. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 15  p Hadronic Shift and Width e.m. transition without strong interaction attractive shift Goals: Shift 0.2% Width 1% Molecular effects Doppler broadening Coulomb deexcitation Precision in small effects ~10 -5 E B  careful study of systematic effects Stability & Calibration

16. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 16 Extention of parameter space measurements of shift and width with different Experimental Procedure  densities  X-ray transitions (4p-1s, 3p-1s, 2p-1s)  Investigations on molecular effects Coulomb transitions effecting the width  high statistic measurement

17. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 17 mixture H 2 / 16 O 2 (98%/2%) 85K at 1.2 bar  4 bar equivalent density H 2 20K at 2 bar  28.5 bar equivalent density H 2 17K at 1 bar LH 2 first time measurement Shift Measurement: Density Dependence

18. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 18  H(3p-1s) energy no density dependence identified  1s = + 7.120  0.008  0.007 eV  E QED = ± 0.006 eV P. Indelicato, priv. comm.   previous experiment LH 2 previous experiment ETHZ-PSIH.-Ch.Schröder et al. Eur.Phys.J.C 1(2001)473 Density Effect in ε 1s ? Molecular formation ("Vesman“ mechanism)  p + H 2  [(  pp) p] ee

19. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 19 Hadronic Width Low background (tails) High statistics Well-known response function Correction of Doppler effect (em cascade) Requirements for precise determination of  1s :

20. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 20 Electron Cyclotron Resonance Ion Trap cyclotron trap (4) + hexapole magnet (2) ( D. Hitz et al., Rev. Sci. Instr., 71 (2000) 1116)  large mirror ratio B max / B min ! argon / oxygen (1/9) 1.4  10 -6 mbar HF 6.4 Ghz Response Function H- and He-like electronic atoms T ion  5 eV "cold" plasma  narrow X-ray transitions  X = 10 - 40 meV  high X-ray intensity: short measuring time First plasma inside ECRIT

21. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 21 ECRIT and Crystal Spectrometer D.F.Anagnostopoulos et al., Nucl. Instr. Meth. B 205 (2003) 9 CCD detector aperture  6.4 GHz, 450 W  = 10 –8 s M1 transitions in He-like S, Cl and Ar  response function very well understood

22. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 22 previous experiment H.-Ch.Schröder et al. Eur.Phys.J.C 21 (2001) 473 not corrected for Coulomb de-excitation crystal resolution subtracted 15 3.5 3.5 28.5 LH 2 10 bar Line Width Analysis

23. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 23 NEUTRON - TOF (  – p ) ns   0 n non-radiative transitions  quasi-discrete velocity profile n – TOF / ns A. Badertscher et al., Eur. Phys. Lett. 54 (2001) 313 (  – H ) n + H=H  (  – H ) n-1 + H + H + kinetic energy Coulomb Transitions: PSI experiment

24. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 24 Coulomb Transitions Energy gain from Coulomb transitions 2p-1s 3p-1s 4p-1s Example: 3p-1s

25. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 25 Width – Doppler Corrected 907±34 meV 775±40 meV 812±60 meV  1s  823  19 meV (2.3%) Fit results including Doppler boxes with free weights Boxes: 0-2 eV 2-20 eV 29-33 eV 65-75 eV 210-220 eV Boxes: 0-2 eV 2-20 eV 29-33 eV 65-75 eV Boxes 0-2 eV 3-15 eV 27-34 eV (same apparatus, 10bar)

26. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 26 High Statistics Data Measurement (2005) of the X-ray transition 2p  1s in pionic hydrogen 1 ch = 28.9 meV in analysis

27. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 27 Coulomb de-excitation  low-energy component Coulomb de-excitation  high-energy components Muonic Hydrogen ----- Crystal response ECRIT 2004 µH R-98.01 December 2004

28. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 28 a + +a - = (93.2±2.9) [10 -3 m π -1 ] ε 1s : Extraction of scattering lengths dominated by ChPT correction   = (-7.2  2.9)% * J. Gasser et al., Eur. Phys. J. C 26, 13 (2003) ChPT correction   = (0.6  0.2)% * P. Zemp, Proceedings hadatom05, arXiv:hep-ph/0508193 (2005) p.16 a - = (86.4 ) [10 -3 m π -1 ]  pion nucl. coupling constant +0.99 -1.02 a + = (6.8±3.1) [10 -3 m π -1 ] * δ ε depend on three LEC: c 1,f 1,f 2 ; f 1 badly known,   depends on f 2 only  1s = 823  19 meV (2.3%) (Preliminary result 2005) a + and a - (preliminary results)

29. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 29 Pion-nucleon Coupling Constant GMO sum rule f 2 πN = 0.5712 a - [m π ] + 0.02488 J [mb -1 ] = 0.0763 M.L. Goldberger, H. Miyazawa, R. Oehme Phys. Rev. 99, 986 (1955) g πNN = 47.66 f πN = 13.165 J = - (1.082  0.032) mb T. E. O. Ericson et al. Phys. Rev. C 66, 014005 (2002) [ g 2 πNN /4π=13.79 ± ] 0.164 0.180 + 0.0009 - 0.0010 + 0.077 - 0.087 J

30. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 30 Pion-nucleon Coupling Constant preliminary PSI 2006 M. Saino

31. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 31 PSI Experiment R98-01 previous exp. present goal  1s /  1s 0.5%   0.2% 0.2% reached  1s /  1s 7 %   2 % 1% Results on Pionic Hydrogen Work in progress:  H Coulomb de-excitation  analysis  Hhigh statistic measurement (2005)  analysis  D measurements in 2006 – additional information

32. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 32 Status of  p Experiment Density dependence studies of the  1s  no effect of molecular effects at our accuracy found  value consistent with result of previous experiment Measurement of transitions from 4p, 3p and 2p to 1s  influence of cascade processes on width  Doppler effect ECRIT  response function extracted Precision measurement of µp X-ray spectrum  study of the Doppler broadening due to Coulomb transitions High statistic measurement 2005 – now in analysis

33. J. Marton, FB18, August 21 – 24, 2006, Santos, Brasil 33 Outlook Thank you for your attention Measurement program is finalized. Analysis of the data set is in progress. We are approaching our goal in accuracy of  1s.