Coulomb Dissociation of $^{27}$P for Study of $^{26}$Si(p,$\gamma$)$^{27}$P Reaction

The $^{26}$Si(p,$\gamma$)$^{27}$P reaction was investigated by the Coulomb dissociation of $^{27}$P. This reaction is suggested to be relevant to the synthesis of $^ {26}$Al whose 1.8~MeV $\gamma$-line distribution in the Galaxy is observed by satellite telescopes. In order to estimate the reaction flow around $^{26}$Al, we determined the gamma decay widths of excited states in $^{27}$P, which mainly determine the resonant capture reaction rate. The experiment was performed at RIPS beam line in RIKEN. A beam of the unstable $^{27}$P nucleus at 57~MeV/nucleon was produced by the fragmentation of a 115-MeV/nucleon $^{36}$Ar beam. The $^{27}$P beam bombarded a Pb target. The excitation energy of $^{27}$P was extracted by combining the momentum vectors of $^{26}$Si and proton. The three known excited states in $^{27}$P [1] as well as a new excited state at around 2.0~MeV were observed. The gamma decay width of the first excited state was deduced to be (1.3 $\pm$ 0.8) $\times$ 10$^{-3}$ eV. Details of experiment and astrophysical implications of the measured gamma decay widths will be presented.\\ \vspace*{0.5cm} \setlength \parindent{0 cm} [1] J.A. Caggiano {\em et al}., Phys. Rev. C {\bf 64}, 025802 (2001).