Cross sections for the ${}^{35}\mathrm{Cl}(n,\alpha ){}^{32}\mathrm{P}$ reaction in the 3.3–5.3 MeV neutron energy region

Cross sections for the ${}^{35}\mathrm{Cl}(n,\alpha ){}^{32}\mathrm{P}$ reaction were systematically measured at incident neutron energies in the range of 3.3 to 5.3 MeV. The experiment was carried out on the Van de Graaff accelerator EG-5 at the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Russia. Fast neutrons were produced in the reaction ${}^2\mathrm{H}(d,n){}^3\text{He}$. Alpha particles from the ($n,\alpha$) reactions were detected using a gridded ionization chamber (GIC) in which various ${}^{35}\mathrm{Cl}$ samples (NaCl and ${\text{BaCl}}_2$, on a tantalum backing) were placed back to back. The relative and absolute neutron fluxes were measured by two samples of ${}^{238}\mathrm{U}_3{}^{}\mathrm{O}_8$ ($99.999\%$) inside the GIC. Data obtained in this measurement were compared with other experimental data of the existing library and theoretical calculations by the talys code. Presented data for the ${}^{35}\mathrm{Cl}(n,\alpha ){}^{32}\mathrm{P}$ reaction should help to clarify discrepancies in the various published nuclear data.

Figure 1

Scheme of the experimental setup. 1-${}^{238}\mathrm{U}$ sample of fission chamber; 2,3,4-anode, grid, and cathode of the GIC, respectively; 5-samples on the sample changer; 6-Fission chamber cathode; PA-charge sensitive preamplifier; TFA-timing filter amplifier.

Figure 2

Calculated energy spectra of $\alpha$ particles from the reaction ${}^{35}\mathrm{Cl}(n,\alpha ){}^{32}\mathrm{P}$ at $E_n=5.0$ MeV (a) forward and (b) backward directions.

Figure 3

Two-dimensional calculated cathode-anode spectra of $\alpha$ particles from the reaction ${}^{35}\mathrm{Cl}(n,\alpha ){}^{32}\mathrm{P}$ at $E_n=5.0$ MeV, (a) forward and (b) backward directions with the contribution of background reactions.

Figure 4

Background-subtracted two-dimensional calculated cathode-anode spectra of $\alpha$ particles from the reaction ${}^{35}\mathrm{Cl}(n,\alpha ){}^{32}\mathrm{P}$ at $E_n=5.0$ MeV, (a) forward and (b) backward directions.

Figure 5

The anode spectrum of fission fragments for measuring the absolute neutron flux of the ${}^{238}\mathrm{U}(n,f)$ reaction at $E_n=5.0$ MeV.

Figure 6

Background subtracted two-dimensional spectra of the ${}^{35}\mathrm{Cl}(n,\alpha ){}^{32}\mathrm{P}$ reaction in the (a) forward and (b) backward directions at $E_n=5.3$ MeV.

Figure 7

The anode projection spectra of net events of the reaction ${}^{35}\mathrm{Cl}(n,\alpha ){}^{32}\mathrm{P}$ in the (a) forward and (b) backward directions at $E_n=5.3$ MeV.

Figure 8

Experimental and evaluated cross sections for the ${}^{35}\mathrm{Cl}(n,{\alpha }_{\text{total}}){}^{32}\mathrm{P}$ reaction and calculated results by talys-1.9.

Figure 9

Partial cross section of two groups for discrete levels of the ${}^{32}\mathrm{P}$ nucleus.

Figure 10

Alpha cluster preformation factor vs neutron energy for the ${}^{35}\mathrm{Cl}(n,\alpha ){}^{32}\mathrm{P}$ reaction.