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Quasi-free Compton scattering and the polarizabilities of the neutron |
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| Authors: | K Kossert M Camen F Wissmann J Ahrens JRM Annand H-J Arends R Beck G Caselotti P Grabmayr O Jahn P Jennewein MI Levchuk AI L'vov JC McGeorge A Natter V Olmos de León VA Petrun'kin G Rosner M Schumacher B Seitz F Smend A Thomas W Weihofen F Zapadtka |
| Institution: | II. Physikalisches Institut, Universit?t G?ttingen, D-37073 G?ttingen, Germany, DE Institut für Kernphysik, Universit?t Mainz, D-55099 Mainz, Germany, DE Department of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK, GB Physikalisches Institut, Universit?t Tübingen, D-72076 Tübingen, Germany, DE B.I. Stepanov Institute of Physics, Belarussian Academy of Sciences, 220072 Minsk, Belarus, BY P.N. Lebedev Physical Institute, 117924 Moscow, Russia, RU |
| Abstract: | Differential cross-sections for quasi-free Compton scattering from the proton and neutron bound in the deuteron have been measured using the Glasgow/Mainz photon tagging spectrometer at the Mainz MAMI accelerator together with the Mainz 48]cm ;SPMOslash; × 64]cm NaI(Tl) photon detector and the G?ttingen SENECA recoil detector. The data cover photon energies ranging from 200]MeV to 400]MeV at θLAB γ = 136.2°. Liquid deuterium and hydrogen targets allowed direct comparison of free and quasi-free scattering from the proton. The neutron detection efficiency of the SENECA detector was measured via the reaction p(γ,π+ n). The “free” proton Compton scattering cross-sections extracted from the bound proton data are in reasonable agreement with those for the free proton which gives confidence in the method to extract the differential cross-section for free scattering from quasi-free data. Differential cross-sections on the free neutron have been extracted and the difference of the electromagnetic polarizabilities of the neutron has been determined to be αn - βn = 9.8±3.6(stat)+2.1 -1.1(syst)±2.2(model) in units of 10-4]fm 3. In combination with the polarizability sum αn + βn = 15.2±0.5 deduced from photoabsorption data, the neutron electric and magnetic polarizabilities, αn = 12.5±1.8(stat)+1.1 -0.6(syst)±1.1(model) and βn = 2.7±1.8(stat)+0.6 -1.1(syst)±1.1(model) are obtained. The backward spin polarizability of the neutron was determined to be γ(n) π = (58.6±4.0)×10-4 fm 4. Received: 21 August 2002 / Accepted: 16 October 2002 / Published online: 11 February 2003 RID="a" ID="a"Part of the Doctoral Thesis. RID="b" ID="b"Present address: Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig. RID="a" ID="a"Part of the Doctoral Thesis. RID="b" ID="b"Present address: Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig. RID="c" ID="c"Part of the Habilitation Thesis. RID="d" ID="d"e-mail: schumacher@physik2.uni-goettingen.de Communicated by Th. Walcher |
| Keywords: | PACS 13 60 Fz Elastic and Compton scattering – 14 20 Dh Protons and neutrons – 25 20 Dc Photon absorption and scattering |
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