Adler, J. -O.; Andersson, B. -E.; Annand, J. R. M.; Nilsson, B.; Boland, M. J.; Fissum, K. G.; Hansen, K.; Harty, P. D.; Ireland, D. G.; AKKURT, İskender; Karlsson, M.; Lundin, M.; McGeorge, J. C.; Crawford, G. I.; Isaksson, L.; Miller, G. J.; Ruijter, H.; Sandell, A.; Schroder, B.; Sims, D. A.; Watts, D.
Description:
A comprehensive set of He-4(gamma,n) absolute cross-section measurements was performed at MAX-lab in Lund, Sweden. Tagged photons from 23 < E-gamma < 70 MeV were directed toward a liquid He-4 target, and neutrons were identified using pulse-shape discrimination and the time-of-flight technique in two liquid-scintillator detector arrays. Seven-point angular distributions have been measured for 14 photon energies. The results have been subjected to complementary transition-coefficient and Legendre-coefficient analyses. The results are also compared to experimental data measured at comparable photon energies as well as recoil-corrected continuum shell-model, resonating group method, and effective interaction hyperspherical-harmonic expansion calculations. For photon energies below 29 MeV, the angle-integrated data are significantly larger than the values recommended by Calarco, Berman, and Donnelly in 1983.