The low-lying spectra of
8He and
10He nuclei were studied in the
3H(
6He,
p)
8He and
3H(
8He,
p)
10He transfer reactions. The
0
+
ground state (g.s.) of
8He and excited states,
2
+
at
3.6
–
3.9
...MeV
and
(
1
+
)
at
5.3
–
5.5
MeV
, were populated with cross sections of 200, 100–250, and 90–125 μb/sr, respectively. Some evidence for a
8He state at about 7.5 MeV was obtained. We discuss a possible nature of the near-threshold anomaly above 2.14 MeV in
8He and relate it to the population of a
1
−
continuum (soft dipole excitation) with a peak value at about 3 MeV. The lowest energy group of events in the
10He spectrum was observed at ∼3 MeV with a cross section of
∼
140
μb
/
sr
. We argue that this result is consistent with the previously reported observation of
10He providing the new
10He g.s. position at about 3 MeV.
The yields of evaporation residues, fusion-fission, and quasifission fragments in the {sup 48}Ca+{sup 144,154}Sm and {sup 16}O+{sup 186}W reactions are analyzed in the framework of the combined ...theoretical method based on the dinuclear system concept and advanced statistical model. The measured yields of evaporation residues for the {sup 48}Ca+{sup 154}Sm reaction can be well reproduced. The measured yields of fission fragments are decomposed into contributions coming from fusion-fission, quasifission, and fast-fission. The decrease in the measured yield of quasifission fragments in {sup 48}Ca+{sup 154}Sm at the large collision energies and the lack of quasifission fragments in the {sup 48}Ca+{sup 144}Sm reaction are explained by the overlap in mass angle distributions of the quasifission and fusion-fission fragments. The investigation of the optimal conditions for the synthesis of the new element Z=120 (A=302) show that the {sup 54}Cr+{sup 248}Cm reaction is preferable in comparison with the {sup 58}Fe+{sup 244}Pu and {sup 64}Ni+{sup 238}U reactions because the excitation function of the evaporation residues of the former reaction is some orders of magnitude larger than that for the last two reactions.
We analyzed the experimental data of the pre-scission neutron multiplicity in connection with fission fragments in the reaction
58Ni
+
208Pb at the incident energy corresponding to the excitation ...energy of the compound nucleus
E
∗
=
185.9
MeV
, which was performed by DéMoN group. The relation between the pre-scission neutron multiplicity and each reaction process having different reaction time is investigated. In order to study the fusion–fission process accompanied by neutron emission, the fluctuation–dissipation model combined with a statistical model is employed. It is found that the fusion–fission process and the quasi-fission process are clearly distinguished in correlation with the pre-scission neutron multiplicity.
The L X-ray spectra of Ta, Au and Th induced by 0.6–4 MeV/nucleon Kr beams have been studied by means of a LiF (1 0 0)-equipped crystal spectrometer having an overall resolution of 30 eV at 8.146 ...keV. The mean energy shifts of the main L lines were measured and electron vacancy configurations deduced. At the highest beam energies L diagram lines have been observed and attributed to the internal conversion of transition energies between nuclear Coulomb excited levels. From the intensities of the main L lines, thick target yields and X-ray production cross sections are deduced.
The specific decay mode of hot nuclei surviving fission or fragmentation and leading in the final state to the production of a large residue has been studied in Ar+Au collisions at 60
AMeV. The ...temperature of these residues has been obtained by analysing the kinematical characteristics (angular and kinetic energy distributions) of the coincident neutrons detected by the DEMON neutron detector. A total cross section of 50 mb has been measured for the production of residues with an initial temperature of 6 MeV or more. This result is compared with the predictions of a microscopic transport model.
We analyzed the experimental data of the pre-scission neutron multiplicity in connection with fission fragments in the reaction $^{58}$Ni+$^{208}$Pb at the incident energy corresponding to the ...excitation energy of compound nucleus $E^{*}$=185.9 MeV, which was performed by D\'{e}MoN group. The relation between the pre-scission neutron multiplicity and each reaction process having different reaction time is investigated. In order to study the fusion-fission process accompanied by neutron emission, the fluctuation-dissipation model combined with a statistical model is employed. It is found that the fusion-fission process and the quasi-fission process are clearly distinguished in correlation with the pre-scission neutron multiplicity.
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