We investigate the neutron scattering spectrum in iron pnictides based on the random-phase approximation in the five-orbital model with a realistic superconducting (SC) gap, Delta=5meV. In the normal state, the neutron spectrum is suppressed by large inelastic quasi-particle (QP) scattering rate gamma* ~ Delta. In the fully-gapped s-wave state without sign reversal (s++), a hump-shaped enhancement appears in the neutron spectrum just above 2Delta, since the inelastic QP scattering is prohibited

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... by the SC gap. That is, the hump structure is produced by the dissipationless QPs for Ek<3Delta. The obtained result is more consistent with experimental spectra, compared to the results of our previous paper with Delta=50meV. On the other hand, both height and weight of the resonance peak in the fully-gapped s-wave states with sign reversal (s+-) are much larger than those observed in experiments. We conclude that experimentally observed broad spectral peak in iron pnictides is created by the present "dissipationless mechanism" in the s++ -wave state.