Authors

Citation

Dp. Watts et al., The C-12(gamma,NN) reaction studied over a wide kinematic range - art. no.014616, PHYS REV C, 6201(1), 2000, pp. 4616

Citations number

60

Language

INGLESE

art.tipo

Article

Categorie Soggetti

Physics

Journal title

PHYSICAL REVIEW C-NUCLEAR PHYSICS

ISSN journal

0556-2813
→ ACNP

Volume

6201

Issue

1

Year of publication

2000

Database

ISI

SICI code

0556-2813(200007)6201:1<4616:TCRSOA>2.0.ZU;2-9

Abstract

The C-12( gamma,np) and C-12( gamma,pp) reactions have been studied using t
he Glasgow photon tagging spectrometer at the Mainz MAMI electron microtron
for E gamma = 150-700 MeV over a kinematic range which extends well beyond
the approximately back-to-back detector arrangements of previous work. For
C-12(gamma,np) the general trends of the missing energy distributions are
reproduced over a wide range of kinematics and photon energies by the theor
y developed by the Valencia group. The corresponding C-12(gamma,PP) channel
is overestimated by a factor of similar to 3. Detailed comparisons of the
experimental data with a Monte Carlo simulation of the direct 2N knockout p
rocess provide the first evidence above the Delta resonance for direct 2N k
nockout and show that this process dominates the C-12(gamma,np) reaction at
low missing energies up to E gamma similar to 700 MeV. The C-12(gamma,pp)
reaction is somewhat less well described by the Monte Carlo simulation. A p
ossible explanation of the observed discrepancies within a direct 2N framew
ork is presented. At high recoil momenta both 2N reaction channels exhibit
an excess yield compared to the Monte Carlo prediction of direct 2N knockou
t. The excess yield in this region is compared with the predicted effects o
f short-range correlations and with the predicted contributions due to othe
r reaction mechanisms.