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Novel Technique to Measure the Polarizability of the Nucleon*

Novel Technique to Measure the Polarizability of the Nucleon*. Olena Yevetska Institut für Kernphysik, TU Darmstadt. Motivation Experimental Setup Experiments Results Summary and Outlook. SFB 634. *Supported by the DFG within SFB 634. E. B. Motivation. a , b - electric and

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Novel Technique to Measure the Polarizability of the Nucleon*

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  1. Novel Technique to Measure the Polarizability of the Nucleon* Olena Yevetska Institut für Kernphysik, TU Darmstadt • Motivation • Experimental Setup • Experiments • Results • Summary and Outlook SFB 634 *Supported by the DFG within SFB 634 10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 1

  2. E B Motivation a, b- electric and magnetic polarizabilities m = bB d = aE describe the response of the nucleon internal structure to applied electric and magnetic fields V. Olmos de Leon et al., Eur. Phys. J. 10 (2001) 207 M. Lundin et al., Phys. Rev. Lett. 90 (2003) 192501 Goal: better accuracy of these constants 10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 2

  3. Point t ~ a+b a-b Motivation Low energy Compton scattering ( E < 140 MeV) Low Energy Theorem: Powell cross section for the point like proton with anomalous magnetic moment Structure term Terms of higher order structure constants V. Petrun‘kin et al., Sov. J. Part. Nucl. 12 (1981) 278 10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 3

  4. Experiment with Compton Scattering previous now Eg´ Eg´ Detector Detector 1023 protons/cm2 1022 protons/cm2 Eg, qg qg qg´ qg´ Target Ep,d qp,d Liquid H/D-target Active high pressure H/D-target Ep = 0.4 – 8 MeV • high luminosity: • 106g/MeV/s 109g/MeV/s • background suppression: • redundancy of kinematic values • Bremsstrahlung spectrum has to be known 10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 4

  5. S-DALINAC Accelerator Hall Experimental Hall 5 m Design Parameters Maximum energy: 130 MeV Energy spread : 10-4 Maximum current: 20 mA Material: Niobium Temperature: 2K g,g g, n) - Experiments ( ´) & ( Compton Scattering on Nucleon g,g ´x)- Experiments at NEPTUN Tagger ( (e,e´x) & 180°- Experiments at QCLAM Spectrometer (e,e´) - Experiments at Lintott Spectrometer 10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 5

  6. Experimental Setup 6 7 7 2 5 1 8 1m 9 3 4 6 4 5 – High pressure ionisation cahmber 6 – NaI(Tl) spectrometer (10“x14“) 7 – Collimator system 8 – BPM, Quantameter 9 – NaI(Tl) spectrometer (10“x10“) 1 – Bremsstrahlung facility 2 – Collimator system 3 – Faraday cup 4 – Concrete shield 10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 6

  7. Bremsstrahlung Ee= 71.3 MeV t = 40 min Ie = 200 pA under 0° 10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 7

  8. Experimental Setup 6 7 7 2 5 1 8 1m 9 3 4 6 4 6 – NaI spectrometer (10“x14“) 7 – Collimator system 8 – BPM, Quantameter 9 – NaI spectrometer (10“x10“) 1 – Bremsstrahlung facility 2 – Collimator system 3 – Faraday cup 4 – Concrete shield 5 – High pressure ionisation chamber 10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 8

  9. High Pressure Ionisation Chamber Determination of the energy and the position of the recoiled protons Strips in the direction of the recoiled protons p e 20 MeV ≤ Eg≤ 90 MeV 0.4 MeV ≤ Ep≤ 8 MeV 10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 9

  10. Proton Signals FADC IK Flash ADC (FADC) Sampling: 105 MHz, 10 ns Time window: 4.5 ms NaI(Tl) Trigger 10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 10

  11. High Pressure Ionisation Chamber 1 cm 10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 11

  12. Compton kinematics Proton vs. electron Arrange q and mass Normalisation identical kinematics qp = 90° 130° qe = 1.89° 2.42° 10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 12

  13. Experimental Setup 6 7 7 2 5 1 8 1m 9 3 4 6 4 6 – NaI spectrometer (10“x14“) 7 – Collimator system 8 – BPM, Quantameter 9 – NaI spectrometer (10“x10“) 1 – Bremsstrahlung facility 2 – Collimator system 3 – Faraday cup 4 – Concrete shield 5 – High pressure ionisation chamber 10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 13

  14. Normalisation Ng‘ – number of Compton events Ng – number of incoming photons NT– number of target nuclei e– detector efficiency DW – solid angle C 10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 14

  15. Experiments 10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 15

  16. First Results 10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 16

  17. Summary and Outlook • Experiments were performed • Preliminary results were shown • Analysis is running • Simulations with GEANT4 • Better statistics • Experiment with deuteron SFB 634 10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 17

  18. Institut für Kernphysik, TU Darmstadt, Darmstadt, Germany: O. Yevetska A. Richter G. Schrieder S. Watzlawik • Petersburg Nuclear Physics Institute, Petersburg, Russia: V. Chizhov V. Iatsioura E. Maev E. Orishchin G. Petrov L. Sergeev Y. Smirenin • Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz, Germany: J. Ahrens 10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 18

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