THE PIONIC HYDROGEN EXPERIMENT AT PSI
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P IONIC H YDROGEN AT PSI D. Gotta Institut für Kernphysik, Forschungszentrum Jülich EXOTIC ATOM PRECISION TESTS OF LOW - ENERGY QCD Moriond XXXVIII QCD’03 ATOMIC CASCADE N scattering at „rest“ 1s app a++ a– 1s –H 4p - 1s 3p - 1s 2p - 1s 1s 1s 3.04 2.88 2.43 –D 3.25 keV 3.08 keV 2.60 keV 7 2 eV 1 1 eV (a p o n ) 2 ( a – )2 M OTIVATION Chiral Perturbation Theory (PT) Low-energy approach of QCD Ecker, Gasser, Leutwyler, Meissner, Lyubovitzkij, Rusetski, Weinberg,... PRECISON AT THE % LEVEL H 1s , 1s N scattering length a+& a– D 1s N coupling constant T 3 He first calculations T 3He a + & a– Baru, Haidenbauer, Hanhart, Niskanen isospin breaking accessible ? quark masses u d f2N H - H ADRONIC N SHIFT 1S & S - WAVE ISOSPIN SCATTERING LENGTHS Coulomb- strong-int. interference 2nd order PT O(2) in = q, =1/137, =(md-mu) V.E. Lyubovitskij & A. Rusetsky, Phys. Lett. B 494(2000)9 LECs f 1 ,f 2 ,c 1 contribute to isospin breaking in O(2) predictions O(10%) V.E. Lyubovitskij et al., Phys. Lett. B 520(2001)204 P RINCIPLE OF M EASUREMENT crystal spectrometer highest possible energy resolution analysis of hit pattern background reduction High stop density high X - ray line yields bright X - ray source DEGRADER and TARGET SETUP inside CYCLOTRON TRAP super-conducting split coil magnet beam X - rays SPHERICALLY CURVED BRAGG CRYSTAL 100 mm cut Si 110 radius of curvature 2985.4 mm L ARGE -A REA F OCAL P LANE D ETECTOR pixel size 40 m 40 m 23 600 602 pixels per chip CCD 22 array frame transfer 10 ms frame buffer data processing 2.4 s operates at – 100°C cooling (LN 2 ) storage area flexible boards image area 150 eV @ 4 keV X 90% N. Nelms et al., Nucl. Instr. Meth 484 (2002) 419 quartz 10.1 Si 111 C quartz 10.1 resolution function CH4 12C(5d-4p) 13C(5g-4f) Bragg 38.6° 12C(5f-4d) 12C(5g-4f) ENERGY RESOLUTION 1500 mbar @ T = 295K = 500 10 meV (FWHM) = 524 16 meV (FWHM) @ C(5-4) - 2974 eV ENERGY CALIBRATION Bragg 40.0° 18O(6h-5g) quartz 10.1 16O(6h-5g) O energy calibration & check of dispersion mixture 4He / 16O2 / 18O2 (80%/50%/50%) 2 bar @ T = 86K EFFECTS FROM THE ATOMIC CASCADE p not an isolated system ! 2.4 keV 1. [(pp)p]ee – molecule formation („DH“) ? had significant radiative decay modes ? 2. Coulomb - de-excitation exists Doppler broadening non radiative process ni nf + kinetic energy had ? H line energy ! H line width isolated atomic system hadronic broadening 1s result of previous experiment: H.Ch.Schröder et al. Eur. Phys. J. C 21 (2001) 473 H(3p-1s) line width = 969 46 meV 3p = (12 5)% correction for Coulomb de-excitation increase of error ! 1s = 868 55 meV S TRATEGY S TUDY OF THE A TOMIC C ASCADE COLLISIONAL EFFECTS VARY WITH DENSITY ! 1. STEP EQUIVALENT PRESSURE 4 10 28 800 LH2 TRANSITION H(2p-1s) H(3p-1s) H(4p-1s) 16O(6g-5d) H(3p-1s) - DENSITY DEPENDENCE Si 111 Bragg 43.3° mixture H2 / 16O2 (98%/2%) 85K at 1.2 bar 4 bar equivalent density quartz 10.1 Bragg 40.0° H2 20K at 2 bar 28.5 bar equivalent density quartz 10.1 Bragg 40.0° H2 17K at 1 bar LH2 first time HADRONIC SHIFT H(3p-1s) 1s no density dependence identified strong-interaction shift in agreement with previous experiment ! ! D pred. T radiative from molecule increases radiative from molecule dominates energy shift H preliminary preliminary 7200 Si 111 qu 10.1 Si 111 / meV 7150 (3-1) 7100 7050 15 3.5 1994 2000 7000 previous experiment H.-Ch.Schröder et al. Eur.Phys.J.C 21(2001)473 3.9 28.5 LH2 2001 2001 2001 year of measurement 10 2002 bar LINE WIDTH AND INITIAL STATE Si 111 Bragg 54.2° H2 30K at 1.2 bar max. Tkin = 210 eV 10 bar equivalent density from n=1 Coul. deex. H(2p-1s) Si 111 Bragg 43.2° max. Tkin = 75 eV n=1 H(3p-1s) Si 111 Bragg 40.5° max. Tkin = 34 eV n=1 H(4p-1s) TOTAL LINE WIDTH line shape = R L D resolution 1s Doppler broadening C & ECRIT Coulomb de-excitation response function subtracted H(2p-1s) H(3p-1s) H(4p-1s) line width decreases Coulomb de-excitation not total line width H corrected for Coulomb de-excitation preliminary preliminary 1400 Si 111 crystal resolution qu 10.1 Si 111 subtracted / meV 1200 (2-1) (3-1) (4-1) 1000 800 15 3.5 1994 2000 previous experiment H.-Ch.Schröder et al. Eur.Phys.J.C 21(2001)473 3.9 28.5 LH2 2001 2001 2001 year of measurement 10 2002 bar HADRONIC WIDTH 1s (1) cascade theory H Kinetic Energy Distribution 3 -2 5-4 4-3 higher MC simulation T. Jensen, V.E.Markushin (2) fit to the line shape -- - - Doppler „boxes“ natural line width 1s total H (3p - 1s) Coulomb de-excitation 4-3 N SCATTERING LENGTHS a new results 1s = + 7.120 0.008 0.009 eV 1s = < 0.850 eV = (-7.2 2.9)% J. Gasser et al., - - - multilpe scattering & 3-body theory Baru & Kudryavtsev Phys.At.Nuc.60(1997)1475 Ericson,Loiseau & Thomas Phys.Scr.T87(2000)71 Weinberg, Tomozawa ‘66 current algebra << ! Eur. Phys. J. C 26 (2003) 13 Gasser, Rusetsky NEXT ... Electron-Cyclotron-Resonance IonTrap Resolution function of crystal spectrometer electronic H- and He-like atoms X = 10 - 40 meV TXplasma 5 eV Hitz et al., Rev.Sci.Instr.,2000 SETUP ECRIT and CRYSTAL SPECTROMETER March 2002 INITIAL MEASUREMENT HF 6.4 GHZ ARGON crystals silicon 111, quartz 10-1 FIRST PLASMA INSIDE HEXAPOLE Ar 16 + = 10-8 s E = 3104 eV FOLLOWING ... Muonic Hydrogen LINE SHAPE OF X-RAY TRANSITIONS µ-H(2p-1s) @ 15 bar 1.89 keV Monte-Carlo simulation from cascade model calculation (V.E. Markushin –PSI) SUMMARY experiment theory 1s 1s 210 -3 310 -2 1s 1s 710 -2 ? < 10 -2 2003 crystals ECRIT 2004 … H Coulomb de-excitation H high statistics finally 1s 1s 1% Experiment R-98.01 Paul-Scherrer-Institut (PSI), Villigen, Switzerland PIONIC HYDROGEN COLLABORATION Debrecen 1 – Ioannina 2 – Jülich 3 – Leicester 4 – Paris 5 – PSI 6 – Wien 7– ETH Zürich 8 D. F, Anagnostopoulos2, S. Biri1, S. Boucard5, M. Cargnelli7, S.Diehl5, A. Dax6, H. Fuhrmann7, M. Giersch7, D Gotta3, A. Gruber7, M. Hennebach3, A.Hirtl7, P. Indelicato5, Th. Jensen8, Y.-W. Liu6, B. Manil5, J. Marton7, V. E. Markushin6, N. Nelms5, P. A. Schmelzbach6, L. M. Simons6, M. Trasinelli5, J. Zmeskal7 Cascade PSI, ETH Zürich CCDs Leicester, PSI, Vienna Cryogenic target Vienna Crystal spectrometer Jülich Cyclotron trap PSI Data analysis Ioannina, Jülich, Paris, Vienna ECRIT Debrecen, PSI
