We measured the^(19)O+^(12)C fusion excitation function using the MATE active-target TPC at IMP for 9.7≤Ec.m.≤16.9 MeV.The results agree well with DC-TDHF and TDHF predictions,demonstrating the importance of dynamic...We measured the^(19)O+^(12)C fusion excitation function using the MATE active-target TPC at IMP for 9.7≤Ec.m.≤16.9 MeV.The results agree well with DC-TDHF and TDHF predictions,demonstrating the importance of dynamical effects near the barrier,but disagree with earlier MUSIC-based measurements.The^(19)O+^(12)C system exhibits a maximum fusion cross section consistent with those ofβ-stable O+C systems.A linear dependence of 1/E_(cr) and closest-approach distance on oxygen mass number is observed for^(17,18,19)O+^(12)C,indicating that additional valence neutrons lower the critical energy.V-shaped excitation structures appear for^(17)O and^(19)O,and the anomalous suppression previously reported for^(17)O calls for further experimental and theoretical study.展开更多
The ^(12)C+^(12)C fusion reaction was studied in the range of E_(c.m.)=8.9 to 21 MeV using the active-target Time Projection Chamber.With full information on all tracks of the reaction products,cross sections of the^(...The ^(12)C+^(12)C fusion reaction was studied in the range of E_(c.m.)=8.9 to 21 MeV using the active-target Time Projection Chamber.With full information on all tracks of the reaction products,cross sections of the^(12)C(^(12)C,^(8)Be)^(16)O_(g.s.)channel and the ^(12)C(^(12)C,3a)^(12)C channel could be measured down to the level of a few milibarns.The ^(12)C(^(12)C,^(8)Be)^(16)O_(g.s.)reaction channel was determined to be 10_(-8)^(+24) mb at E_(c.m.)=11.1 MeV,supporting the direct a transfer reaction mechanism.The ^(12)C(^(12)C,3α)^(12)C reaction channel was studied for the first time using an exclusive measurement.Our result does not confirm the anomaly behavior reported in the previous inclusive measurement by Kolata et al.[Phys.Rev.C 21,579(1980)].Our comparisons with statistical model calculations suggest that the 3 a channel is dominated by the fusion evaporation process at E_(c.m.)>19 MeV.The additional contribution of the 3 a channel increases the fusion reaction cross section by 10% at energies above 20 MeV.We also find that an additional reaction mechanism is needed to explain the measured cross section at E_(c.m.)<15 MeV at which point the statistical model prediction vanishes.展开更多
基金Supported by National Key Research and Development program(MOST 2022YFA1602304)the National Natural Science Foundation of China(12335009,U1632142,12505146).
文摘We measured the^(19)O+^(12)C fusion excitation function using the MATE active-target TPC at IMP for 9.7≤Ec.m.≤16.9 MeV.The results agree well with DC-TDHF and TDHF predictions,demonstrating the importance of dynamical effects near the barrier,but disagree with earlier MUSIC-based measurements.The^(19)O+^(12)C system exhibits a maximum fusion cross section consistent with those ofβ-stable O+C systems.A linear dependence of 1/E_(cr) and closest-approach distance on oxygen mass number is observed for^(17,18,19)O+^(12)C,indicating that additional valence neutrons lower the critical energy.V-shaped excitation structures appear for^(17)O and^(19)O,and the anomalous suppression previously reported for^(17)O calls for further experimental and theoretical study.
基金Supported in part by the Strategic Priority Research Program of Chinese Academy of Sciences(XDB34020200)the National Key Research and Development program(MOST 2016YFA0400501)from the Ministry of Science and Technology of China+2 种基金the State Key Laboratory of Nuclear Physics and Technology,PKU(NPT2020KFY06)the National Natural Science Foundation of China(U1632142,12175156),the National Natural Science Foundation of China(11905260)the Western Light Project of Chinese Academy of Sciences。
文摘The ^(12)C+^(12)C fusion reaction was studied in the range of E_(c.m.)=8.9 to 21 MeV using the active-target Time Projection Chamber.With full information on all tracks of the reaction products,cross sections of the^(12)C(^(12)C,^(8)Be)^(16)O_(g.s.)channel and the ^(12)C(^(12)C,3a)^(12)C channel could be measured down to the level of a few milibarns.The ^(12)C(^(12)C,^(8)Be)^(16)O_(g.s.)reaction channel was determined to be 10_(-8)^(+24) mb at E_(c.m.)=11.1 MeV,supporting the direct a transfer reaction mechanism.The ^(12)C(^(12)C,3α)^(12)C reaction channel was studied for the first time using an exclusive measurement.Our result does not confirm the anomaly behavior reported in the previous inclusive measurement by Kolata et al.[Phys.Rev.C 21,579(1980)].Our comparisons with statistical model calculations suggest that the 3 a channel is dominated by the fusion evaporation process at E_(c.m.)>19 MeV.The additional contribution of the 3 a channel increases the fusion reaction cross section by 10% at energies above 20 MeV.We also find that an additional reaction mechanism is needed to explain the measured cross section at E_(c.m.)<15 MeV at which point the statistical model prediction vanishes.
