The angular distribution of the $^{12}$C($\gamma$,pn) reaction for E$_\gamma=120-150$ MeV

T.T-H. Yau - et al.

doi:doi:10.1007/s100500050055

EPJ

a
b
c
d
e
ap
st
h
plus
ds
pv
ti
qt
am
n

2024 Impact factor 2.8

Hadrons and Nuclei

Eur. Phys. J. A 1, 241-244

Short note

The angular distribution of the ¹²C( $\gamma$ ,pn) reaction for E $_\gamma=120-150$ MeV

T.T-H. Yau¹ - I.J.D. MacGregor¹ - J. Ahrens⁴ - J.R.M. Annand¹ - R. Beck⁴ - D. Branford² - P. Grabmayr³ - S.J. Hall¹ - P.D. Harty¹ - T. Hehl³ - D.G. Ireland¹ - J.D. Kellie¹ - T. Lamparter³ - K. Livingston¹ - M. Liang², J.A. MacKenzie² - S. McAllister¹ - J.C. McGeorge¹ - R.O. Owens¹ - M. Sauer³ - R. Schneider³ - D.P. Watts¹

¹ Department of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
³ Department of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, UK
⁴ Physikalisches Institut, Universität Tübingen, D-72076 Tübingen, Germany
⁵ Institut für Kernphysik, Universität Mainz, D-55099 Mainz, Germany

Received: 3 September 1997 / Revised version: 17 December 1997 Communicated by Th. Walcher

Abstract
The angular distribution of nucleons emitted in the ¹²C( $\gamma$ ,pn) reaction has been measured using tagged photons at the Mainz microtron MAMI. The variation of the reaction strength with the polar angles of the two emitted nucleons is reported for E $_\gamma=120-150$ MeV. The proton angular distribution peaks at more backward angles than the ²H( $\gamma$ ,p) differential cross section indicating a departure from the simple quasi-deuteron model of 2N photo-emission. The distribution shape is in reasonable agreement with microscopic theoretical models which include both $\pi$ - and $\rho$ -exchange.