The bipolar amplification and charge collection in Junctionless Double-Gate MOSFETs (JL-DGFET) submitted to heavy-ion irradiation are investigated. The transient response of JL-DGFET is compared to that of conventional devices operating in inversion-mode (IM-DGFET). We show that the bipolar amplification is higher in junctionless devices than in conventional inversion-mode devices mainly due to the higher doping levels in the channel which induce larger floating body effects.