Fragment production in proton–induced reaction on ${}^{209}\mathrm{Bi}$ target at intermediate energy range

We used the phasotron of the Laboratory of Nuclear Problems at JINR to irradiate isotopically pure ${}^{209}\mathrm{Bi}$ target with 660 MeV protons. Cross sections of the fragment production with mass numbers $24\le A\le 210$ u were measured for the first time using the direct $\gamma$-spectrometry method with a high-resolution HpGe detector. The $\gamma$ lines of the fragments have been identified, and the cross sections determined by the deimos code. The results of the measured nuclide cross section have been parametrized in terms of a three-parameter equation in order to reproduce the real isobaric distribution. Fission and spallation mass yields have been reconstructed on the base of charge distribution of reaction products. The main reaction results have been compared with other experimental data obtained from the proton-induced reaction at 600 MeV as well as with theoretical model calculations using the crisp code.

Figure 1

Mass-yield distribution for the interaction of 660 MeV proton-induced reaction on a ${}^{209}\mathrm{Bi}$ target. The black continuous curve corresponds to the fission cross section, the dashed indicates the spallation cross section, and experimental data are represented by the solid squares.

Figure 2

Fissility $D$ as a function of $Z^2/A$ of the fissile system. Presented symbols for the experimental data are $p+{}^{241}\mathrm{Am}$ ($▴$), $p+{}^{237}\mathrm{Np}$ ($\circ$) [12], $p+{}^{238}\mathrm{U}$ ($▵$) [13], and $p+{}^{209}\mathrm{Bi}$ ($•$) (present work). The solid line is displayed as a guide.

Figure 3

Contribution of the symmetric fission to the total fission cross section (${\sigma }_{\mathrm{sym}}/{\sigma }_f$) as a function of the total number of emitted neutrons (${\nu }_T$). Presented symbols for experimental data are $p+{}^{241}\mathrm{Am}$ ($▴$) [12], $p+{}^{238}\mathrm{U}$ ($▵$) [13], $p+{}^{237}\mathrm{Np}$ ($\circ$) [12], and $p+{}^{209}\mathrm{Bi}$ ($•$) (present work). The dashed line is displayed as a guide.

Figure 4

Cross section ratios, ${\sigma }_p\left(660\right)/{\sigma }_p\left(600\right)$, of residues from 660 and 600 MeV proton-induced reactions of present work and from Ref. [1].

Figure 5

Calculated fission and spallation mass-yield distribution for the interaction of 660 MeV proton-induced reaction on a ${}^{209}\mathrm{Bi}$ target. Black dashed line represents the fission mass yield while the blue dotted line represents the spallation mass yield. The solid red line stands for the total mass yield.