Experimental study of the halo nucleusHe6using theLi6(γ,π+)He6reaction

Autor: J. R. M. Annand, K. Föhl, I. J. D. MacGregor, D. Branford, S. Waddell, D. P. Watts, F. Moschini, Ian Martin, A. Reiter, K. Livingston, P. Grabmayr, R. Beck, D. Hornidge, T. Hehl, E. Roche, N. P. Harrington, K. Monstad, J. C. McGreorge, Stuart Young
Rok vydání: 2007
Předmět:
Zdroj: Physical Review C. 75
ISSN: 1089-490X
0556-2813
DOI: 10.1103/physrevc.75.044311
Popis: The reaction $^{6}\mathrm{Li}$($\ensuremath{\gamma},{\ensuremath{\pi}}^{+})$$^{6}\mathrm{He}$ was studied over the angular range ${\ensuremath{\theta}}_{\ensuremath{\pi}}=40$--150$\ifmmode^\circ\else\textdegree\fi{}$ with the aim of investigating the halo structure of $^{6}\mathrm{He}$. Photons from a bremsstrahlung beam were tagged in the energy range ${E}_{\ensuremath{\gamma}}=170$--220 MeV at a resolution of $\ensuremath{\Delta}{E}_{\ensuremath{\gamma}}=630$ keV, and positively charged pions detected using high resolution stacked HpGe detectors. The measured angular distributions for the resolved $^{6}\mathrm{He}$ ground and 1.80 MeV excited states are compared to previous measurements and theoretical calculations based on the impulse approximation. It is deduced that the ground state rms radius of the $^{6}\mathrm{He}$ nucleus may be larger than previously thought and that the first excited 1.80 MeV state may also be a halo state.
Databáze: OpenAIRE