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1.- Introduction 2.- MAMI Accelerator

Institut für Kernphysik. Physics at MAMI. 1.- Introduction 2.- MAMI Accelerator Virtual Photons: Three Spectrometer Setup, KaoS Real Photons: GDH DAPHNE , Crystal Ball/TAPS 3.- Recent Physics Results 4.- Conclusions and Outlook. NSTAR 2007

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1.- Introduction 2.- MAMI Accelerator

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  1. Institut für Kernphysik Physics at MAMI 1.- Introduction 2.- MAMI Accelerator Virtual Photons: Three Spectrometer Setup, KaoS Real Photons: GDH DAPHNE , Crystal Ball/TAPS 3.- Recent Physics Results 4.- Conclusions and Outlook NSTAR 2007 WORKSHOP ON THE PHYSICS OF EXCITED NUCLEONS5 - 8 September 2007Bonn, Germany Andreas Thomas A2- and CBall@MAMI- Collaborations

  2. RTM 2 51 Turns 180MeV RTM 1 18 Turns 15MeV RTM 3 90 Turns 880MeV, LINAC 3.5MeV, v=99,1%·c MAMI A, 1979 + 1983 H. Herminghaus et al. MAMI B, 1990 H. Herminghaus et al. MAMI B Microtron-Cascade

  3. 250 t 250 t 250 t 250 t Double Sided Microtron (K.H. Kaiser et al.) 2000 to 2000 to 43 Turns, 855MeV  1,5GeV

  4. Dipole with Fieldgradient Focussing Top view Defocussing Side view F B (Force F perpendicular Magnet.Field B) Compensation of 45°-Edge-Defocussing ? 45°

  5. 250t, 1.539T 90° Dipole Magnet Designed at IKPH Produced 2002 in close Collaboration with Industrial company (France)

  6. Harmonic Double Sided Microtron (HDSM) 45°

  7. Intensity signal of the 2.45GHz Linac-Monitor 20.12.2006 Umlauf 1 Umlauf 43 2.45GHz linac RTM 3 1508MeV 855MeV MAMI C operational

  8. MAMI C • Parameter • 1507MeV, sE=0.100MeV • max. 100mA • eh=9 nm rad, ev=0.5 nm rad • as MAMI B ! MAMI B • Beam Parameter (beam since 1990) • 885MeV, sE=0.068MeV • max. 103mA cw • eh=8 nm rad, ev=0.5 nm rad • (Beam Focus ~mm) • Halo: < 10-5 bei r > 5∙sr • ca. 6000h – 7000h operation / year

  9. Since 23.Feb.2007 first Experiment in A1: 1.508GeV, 10mA, polarised Electrons ( 80%) Targetasymmetry puzzle in h production beam on target: >80% Short high current test: 50mA Fr., 23.02.2007, 12.00 Mo., 05.03.2007, 6.00

  10. !!!Transversely Pol. Target „Isobar“ models, e.g. EtaMaid (Breit-Wigner resonances + background) failed !!

  11. Electroproduction of the h-Mesons at low Q2 Three-Spectrometer-Setup A1: Electron scattering

  12. Electroproduction of the h-Mesons at low Q2 p(e,e‘p)h Data taking 170h I=10mA Kinematic: Measurement of the degree of proton recoil and electron polarisation (via Moeller polarimeter: 79%)

  13. Reconstruction of the h-meson in the‚missing mass‘- Spectrum 1.9 * 106 h-Mesons Background ~ 10% Random background ~2.5% Goal of the measurement: Cross-section + Recoil polarisation

  14. Red curves: Multipole analysis based on S11 dominance and data from ds/dW, S and T (strong phase change between E0+ and E2− + M2−) L.Tiator et al., Phys. Rev. C60 035210 (1999) Recoil polarization and beam-recoil double polarization measurement of η electroproduction on the proton in the region of the S11(1535) resonanceH. Merkel et al., arXiv:0705.3550v1 , submitted to Phys. Rev. Lett.

  15. A2 Tagging system (Glasgow,Mainz) 1. Production und energy measurement of the Bremsstrahlungs photons Determination of the degree of polarization of the electron beam (Moeller Polarimeter); Circularly pol. photons 2. 3. Coherent production of linearly polarized photons on a diamond radiator Primary "Vacoflux" Foil Moeller trigger Coincidence beam = ± 8 . 1 0 . 2 % p t E e - E e - e - Electron beam Radiator (Moeller target)

  16. Tagger Microscope Energy resolution of our standard tagger ladder (352 plastics) 2 MeV per Channel. • 96 Plastic Scintillator Fibers (3x2 mm). • 1/3 Overlap of the fibers with its neighbor. Overlap region defines the Mikcroscope chanal μch(191 channels). • Energy resolution: 0.3 MeV per microscope channel (μch). • Microscope Tagger is positioned in the electron energy range from 153 to 209 MeV. Beam energy E0=883 MeV corresponds to a photon energy range from 674 MeV to 730 MeV (η-threshold ~707 MeV).

  17. Polarised Photons @ MAMI C Eg = 75 ... 1425 MeV DEg = 4 MeV Ng = 2 . 105 s-1 MeV-1

  18. 4p photon Spectrometer @ MAMI TAPS: 510 BaF2 detectors Max. kin. energy: p+- : 180 MeV K+- : 280 MeV P : 360 MeV Crystal Ball: 672 NaJ detectors Max. kin. energy: m+- : 233MeV p+- : 240 MeV K+- : 341 MeV P : 425 MeV Vertex detector: 2 Cylindr. MWPCs 480 wires, 320stripes PID detector: 24 thin plastic detectors

  19. Crystal Ball / TAPS

  20. Crystal Ball Detector: UCLA

  21. Results from the first round (3600h) with CB@MAMI B (882MeV) in 2004 and 2005 • Data set with high statistics for pion and double pion production. • Helicity Asymmetry in double pion production. • Precision measurement to determine the h-mass. • 30*106h produced for the investigation of rare h-decays (C, CP-Violation) and the h - Dalitz-decay h -> e+e-g . • Dalitz Plot Parameter in the h -> p0p0p0 decay. Sensitiv to the quark-mass-differenz mu-md. • Investigation of h-mesic nuclei (7Li-, 3He-target). • Magnetic Moment of the D-Resonance. • Data set on nuclei (modified pp Interaction in nuclear matter). • Coherent p0 production on nuclei.

  22. Rot TAPS Daten Kurven:ChPT Data set with high statistics for p and pp production [F.Zehr, S.Schumann] gp  pp0p0

  23. Helicity asymmetry in pp – Production [PhD, D.Krambrich, publication in preparation] Productionplane ( Pion, Pion) Reactionplane (Photon k, Proton p‘)

  24. Valencia-Model - Phenomenological Model, aprox. 25 Diagrams - Good description of unpol. Observablen (e.g. σTot) in all 3 reaction channels Braghieri, A., et al.:Phys. Lett B 363:46, 1995Kotulla, M.: Diss. Gießen, 2001Assafiri, Y., et al.: INPC 2001, P362-365Gomez, J.A., et al.: Nucl. Phys A 600:413-435 Roca, L: Nucl. Phys. A748 (2005) 192-205: I⊙ sensitive on Interference therms!

  25. Results: (p) π0π0 Preliminary Curves: „private Comminication“ - L. Roca: Prediction for Center of Intervall - A. Fix: Prediction in Intervall Additional Observable to improve models

  26. Now running: first experiment @ MAMI C with CB and TAPS detectors (600 hours of beamtime approved)

  27. Data from the GDH experiment @ MAMI B with DAPHNE detector

  28. Bonn Polarized target [C.Bradtke et al., NIM A436, 430 (1999)] „Frozen Spin Mode“ • Polarization : DNP at high B-Field (2.5 T) • Measurement : very low T ´freeze´ up the spin (0.4 Tesla) relaxation time T 200 h » New Technology: horizontal cryostat with integrated solenoid (holding field) 1.2 Kelvin 0.42 Tesla equiv. 780mm Cu (100mm NbTi) World record in Deuteron polarisation due to new doping material with small ESR from Bochum. [W.Meyer et al.]

  29. Butanol (C4H9OH)

  30. Bonn Frozen Spin Target at A2 / MAMI [C.Bradtke et al., NIM A436, 430 (1999)]

  31. Measurements in 1998 at MAMI with DAPHNE and Bonn PT Partial reaction channels Input for PWA to extract resonance parameters

  32. New: First measurement of the helicity dependence for the gp  pp+p-reaction J.Ahrens et al., submitted to EPJ A FA [A. Fix and H. Arenhövel, Eur. Phys. J. A 25 (2005) 115. ] Effective Lagrangian approach including four-star resonances with masses up to 1700 MeV. Valencia model [J. Nacher and E. Oset, Nucl. Phys. A 697 (2002) 372.]

  33. Kinematical overdetermination in DAPHNE acceptance  Experimental helicity dependent invariant mass distributions for the pp system Full curves: [A. Fix and H. Arenhövel, Eur. Phys. J. A 25 (2005) 115. ] Dashed: simple DPPS model - uniform Dp phase space distribution Further theoretical and experimental studies needed to check prod. mechanism.

  34. Data from the GDH experiment @ MAMI B with DAPHNE detector gp  ph J.Ahrens et al.: EPJ A17 (2003) 241

  35. h-Photoproduction MAID2003 DSG E Dominated by S11(1535) at low photon energy  E=1  calibration PBPT For the next round of experiments a high efficiency for multi-photon final states and a PT is required to determine precisely the h- and p0- production

  36. Frozen Spin Target for Crystal Ball @ MAMI 3He/4Helium Dilution cryostat [JINR Dubna] with 4Helium-evaporator as precooler: T<30mK; Pp=90%; Pd=70%.

  37. 7.June 2007

  38. 70mKelvin at 30.June2007

  39. New Projects

  40. Recoil Polarimeter [D. Watts, D. Glazier] Preliminary

  41. Conclusion and Outlook MAMI C is delivering polarised beam with 1508 MeV and high Intensity for the experiments. First experiment: ’Recoil polarisation and beam-recoil double polarisation of eta electroproduction on the proton in the region of the S11(1535) resonance’ at the Three Spectrometer Setup. Data from ‚Crystal Ball‘ detector in combination with TAPS and further detectors at MAMI B (882MeV) in the years 2004/5 are under analysis. First Publications planned for this year: Measurement h-mass, rare h-decays, Dalitz Plot Parameter a, MDM Experiments with ‚Crystal Ball@MAMI C‘ started. First measurement is dedicated to h‘ production with unpol. H2 target. Future projects: We will start experiments with the KaoS Spectrometer in A1. Comissioning runs this year. In A2 we will do double polarised experiments with polarised beam, polarised target and recoil-polarimeter.

  42. Three-Spectrometer-Setup A1: Electron scattering

  43. KaoS Spectrometer short live-time of the kaons (ctK =3.71 m) short orbit Spectrometer in forward direction • Very compact magnetic spectrometer suitable especially for the detection of kaons. • Detectors for triggering, particle identification and momentum determination by ray-tracing. • Plastic scintillator hodoscopes, Cherenkov detectors and wire chambers.

  44. The GDH collaboration J.Ahrens9,S.Altieri15,16,J.R.M.Annand6,G.Anton3,H.-J.Arends9,K.Aulenbacher9,R.Beck9,C.Bradtke1,A.Braghieri15,N.Degrande4,N.d'Hose5,H.Dutz2, S.Goertz1,P.Grabmayr17,K.Hansen8,J.Harmsen1, S.Hasegawa13,T.Hasegawa11,E.Heid9, K.Helbing3,H.Holvoet4, L.VanHoorebeke4,N.Horikawa14,T.Iwata13,P.Jennewein9, T.Kageya14,B.Kiel2,F.Klein2,R.Kondratiev12,K.Kossert7,J.Krimmer17,M.Lang9,B.Lannoy4,R.Leukel9,V.Lisin12,T.Matsuda11,J.C.McGeorge6,A.Meier1,D.Menze2,W.Meyer1,T.Michel3,J.Naumann3,A.Panzeri15,16,P.Pedroni15,T.Pinelli15,16,I.Preobrajenski9,12,E.Radtke1,E.Reichert10,G.Reicherz1,Ch.Rohlof2, G.Rosner6, D.Ryckbosch4,F.Sadiq6,M.Sauer17,B.Schoch2, M.Schumacher7,B.Seitz7, T.Speckner3,M.Steigerwald9,N.Takabayashi13,G.Tamas9, A.Thomas9, R.van de Vyver4, A.Wakai14,W.Weihofen7,F.Wissmann7,F.Zapadtka7,G.Zeitler3 1Institute of Experimental Physics, Ruhr-University,Bochum, Germany 2Physics Institute, University of Bonn, Germany3Physics Institute, University of Erlangen-Nuernberg,Erlangen, Germany 4Nuclear Physics Laboratory, Gent, Belgium 5CEA Saclay, DSM/DAPNIA/SPhN, Gif-sur-Yvette, France 6Department of Physics & Astronomy, University of Glasgow, U.K.7II.Physics Institute, University of Goettingen, Germany8Department of Physics, University of Lund, Sweden9,10Institute of Nucl. Physics and Inst. of Physics, University of Mainz, Germany 11Faculty of Engineering, Miyazaki University, Miyazaki, Japan 12INR, Academy of Science, Moscow, Russia 13,14 Department of Physics and CIRSE, Nagoya University, Nagoya, Japan 15,16 INFN Sezione di Pavia and Dept. of Nucl. Physics of the University , Pavia, Italy 17 Physics Institute, University of Tuebingen, Germany

  45. Crystal Ball @ MAMI Collaboration Run 2004/2005  700 Stunden Tests 3600 Stunden Datennahme 12 PhD

  46. Excitation Spectrum of the nucleon Pion Production Eta Production polarisation observables essential

  47. lin lin circ g Beam P P P g g g unpol æ p ö æ p p ö + - ç ÷ ç ÷ Target 0 , , è 2 ø è 4 4 ø æ ö s d S ç ÷ P - - unpol W è d ø P - - H F x P T P - - y P - - G E z Photoproduction of pseudoscalar p, h, h‘, K with polarised beam and target Strahl Target

  48. N N Pion Photoproduction with Polarized Beam and Polarized Target EL, ML Multipole components of the electromagnetic radiation Angular momentum and parity conservation Multipole amplitudes: Angular momentum Parity EL : ML :

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