First measurement of the Gerasimov-Drell-Hearn sum rule for H-1 from 0.7 to 1.8 GeV at ELSA

ISSN
1079-7114
0031-9007
Date Issued
2003
Author(s)
Dutz, H.
Helbing, Krister
Krimmer, J.
Speckner, T.
Zeitler, G.
Ahrens, J.
Altieri, S.
Annand, JRM
Anton, G.
Arends, H. J.
Beck, R.
Bock, A.
Bradtke, C.
Braghieri, A.
von Drachenfels, W.
Frommberger, F.
Godo, M.
Goertz, S.
Grabmayr, P.
Hasegawa, S.
Hansen, K.
Harmsen, J.
Heid, E.
Hillert, W.
Holvoet, H.
Horikawa, N.
Iwata, T.
van Hoorebeke, L.
d'Hose, N.
Jennewein, P.
Kiel, B.
Klein, F.
Kondratiev, R.
Lang, M.
Lannoy, B.
Leukel, R.
Lisin, V.
Menze, D.
Meyer, Werner
Michel, Tanja Maria
Naumann, J.
Panzeri, A.
Pedroni, P.
Pinelli, T.
Preobrajenski, I.
Radtke, E.
Reicherz, G.
Rohlof, C.
Rostomyan, T.
Schoch, B.
Schumacher, M.
Tamas, Gabor
Thomas, Andy
van de Vyver, R.
Weihofen, W.
Zapadtka, F.
DOI
10.1103/PhysRevLett.91.192001
Abstract
To verify the fundamental Gerasimov-Drell-Hearn (GDH) sum rule for the first time experimentally, we measured the helicity dependent total photoabsorption cross section with circularly polarized real photons and longitudinally polarized nucleons in the photon energy range 0.68-1.82 GeV with the tagged photon facility at ELSA. The experiment was carried out with a 4pi detection system, a circularly polarized tagged photon beam, and a frozen spin polarized proton target. The contribution to the GDH sum rule in this photon energy range is [49.9+/-2.4(stat)+/-2.2(syst)] mub.