55. Jahrestagung der ÖPG, September 2005 Pionischer Wasserstoff: Präzisionsmessungen zur starken Wechselwirkung J. Marton Stefan Meyer Institut der ÖAW on behalf of the Pionic Hydrogen Collaboration

55. Jahrestagung der ÖPG, September 2005 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 and width of the 1s ground state of pionic hydrogen  pion-nucleon scattering lengths (isoscalar, isovector) with an accuracy at the percent level scattering lengths  basis for comparison of changes in the nuclear medium

55. Jahrestagung der ÖPG, September 2005 Pion-Nucleon Scattering Lengths shift data from pionic hydrogen and deuterium, width from pionic hydrogen (Schröder et al.,2001) >>> W. Thirring 1954

55. Jahrestagung der ÖPG, September 2005 Electromagnetic Cascade of  p 1 observables: shift and width 1s state Pion decay  ~10 -8 s slow compared to reaction rates  precise QED calculations  advanced cascade theory  p is not an isolated system  interaction with hydrogen

55. Jahrestagung der ÖPG, September 2005 Principle of 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

55. Jahrestagung der ÖPG, September 2005 SET-UP at PSI crystal spectrometer spherically bent crystals CCD X-ray detector 2  3 matrix X-ray tube cryogenic target cyclotron trap II

55. Jahrestagung der ÖPG, September 2005 Experimental Method Bragg crystal CCD X-ray detector Target and cyclotron trap

55. Jahrestagung der ÖPG, September 2005 Cyclotron Trap with Target and Degraders X - rays   beam    stop efficiency f stop  density   stp 10 9  /s super-conducting split coil magnet

55. Jahrestagung der ÖPG, September 2005 Spherically curved Bragg crystal 100 mm 

55. Jahrestagung der ÖPG, September 2005 Large - Area Focal Plane CCD Detector N. Nelms et al., Nucl. Instr. Meth 484 (2002)  3 CCD 22 array pixel size 40  m  40  m 600  600 pixels per chip operated at – 100°C   keV  X  90% image area storage area flexible boards cooling (LN 2 )  

55. Jahrestagung der ÖPG, September 2005  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

55. Jahrestagung der ÖPG, September 2005 πp Hadronic Shift and Width e.m. transition without strong interaction attractive shift Goals: Shift 0.2% Width 1% Molecular effects Doppler broadening Coulomb deexcitation required resolution: 1: careful study of small effects Stability & Calibration

55. Jahrestagung der ÖPG, September 2005  extention of parameter space: measurements of shift and width with different  Doppler broadening of width to be measured with muonic hydrogen X-rays (no hadronic interaction) Experimental Procedure  densities  X-ray transitions (4p-1s, 3p-1s, 2p-1s)  Investigations on molecular effects Coulomb transitions effecting the width

55. Jahrestagung der ÖPG, September 2005  H(3p-1s) energy no density dependence identified  1s =   eV  E QED = ± 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 ? Molecular formation ("Vesman“ mechanism)  p + H 2  [(  pp) p] ee

55. Jahrestagung der ÖPG, September 2005 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  mbar HF 6.4 Ghz Response Function H- and He-like electronic atoms T ion  5 eV "cold" plasma  narrow X-ray transitions  X = meV  high X-ray intensity: short measuring time First plasma inside ECRIT

55. Jahrestagung der ÖPG, September 2005 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

55. Jahrestagung der ÖPG, September 2005 previous experiment H.-Ch.Schröder et al. Eur.Phys.J.C 21 (2001) 473 not corrected for Coulomb de-excitation crystal resolution subtracted LH 2 10 bar Line Width Analysis

55. Jahrestagung der ÖPG, September 2005 Hadronic Width (preliminary) Hadronic width – corrected for Doppler effect due to Coulomb de-excitation Preliminary average value for the hadronic width  1s = 785 ± 27 meV

55. Jahrestagung der ÖPG, September 2005 Coulomb de-excitation  low-energy component Coulomb de-excitation  high-energy components Muonic Hydrogen Crystal response ECRIT 2004 µH R December 2004

55. Jahrestagung der ÖPG, September 2005 PSI Experiment R98-01 previous exp. 1. step goal  1s /  1s 0.5%   0.2% 0.2% reached  1s /  1s 7 %   3 % 1% Results on Pionic Hydrogen Work in progress:  H Coulomb de-excitation  analysis  Hhigh statistic run

55. Jahrestagung der ÖPG, September 2005 Status of πp 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 (due to Coulomb de-excitation) visible  Doppler effect ECRIT  response function extracted Precision measurement of µp X-ray spectrum  study of the Doppler broadening due to Coulomb transitions

55. Jahrestagung der ÖPG, September 2005 Outlook Analysis in progress High statistics measurement / high resolution crystal Thank you for your attention