  Photoproduction of $\eta$ mesons from neutrons} \abstract{Results from
measurements of the photoproduction of $\eta$ mesons from quasifree protons and
neutrons are summarized. The experiments were performed with the CBELSA/TAPS
detector at the electron accelerator ELSA in Bonn using the
$\eta\to3\pi^{0}\to6\gamma$ decay. A liquid deuterium target was used for the
measurement of total cross sections and angular distributions. The results
confirm earlier measurements from Bonn and the MAMI facility in Mainz about the
existence of a narrow structure in the excitation function of $\gamma
n\rightarrow n\eta$. The current angular distributions show a forward-backward
asymmetry, which was previously not seen, but was predicted by model
calculations including an additional narrow $P_{11}$ state. Furthermore, data
obtained with a longitudinally polarized, deuterated butanol target and a
circularly polarized photon beam were analyzed to determine the double
polarization observable $E$. Both data sets together were also used to extract
the helicity dependent cross sections $\sigma_{1/2}$ and $\sigma_{3/2}$. The
narrow structure in the excitation function of $\gamma n\rightarrow n\eta$
appears associated with the helicity-1/2 component of the reaction.
