Michiaki Furukawa

Excitation Functions for ( p , n ) Reactions with Titanium, Vanadium, Chromium, Iron and Nickel up to Ep=14 MeV

The absolute ( p , n ) cross sections on Ti 47 , Ti 48 , V 51 , Cr 52 , Fe 56 , Fe 57 , Ni 61 and Ni 64 were measured by the activation method at proton energies up to 14 MeV. The experimental results were compared with the predictions based on statistical model in terms of σ( p , n )/σ total , and it was shown that the predictions based on this simple model are not necessarily in disagreement with the experiments.

Excitation Function for the Reaction B 11 ( p , n )C 11 up to E p =15 MeV and Energy Levels of C 12

Excitation function for the B 11 ( p , n )C 11 reaction was measured by the activation method with improved energy resolution for the proton energies ranging from 4.7 to 15.0 MeV. The excitation function exhibited rather clear peaks at proton energies of 8.5, 9.9, 10.9, 11.5 and 13.6 MeV in the laboratory system and a broad peak at the energy region between 13.8 MeV and 14.5 MeV. A considerable number of uncertain peaks were also observed. The excitation function for the O 16 ( p , α)N 13 reaction was also obtained above E p =9.7 MeV.

Excitation Function for the Reaction O16(a, pn)F18

The energy dependence of cross sections for the reaction O/sup 16/( alpha ,pn)F/sup 18/ was determined for alpha-particle energies from 21 to 40 Mev. The results are plotted as an excitation function. The observed production of F/ sup 18/ below the thereshold energy (23.2 Mev) for the ( alpha ,pn) reaction is attributed in part to the ( alpha ,d) reaction with a threshold energy of 20.4 Mev. The half life of F/sup 18/ was determined to be the same as the literature value (112 min). (D.L.C.)

Reactions of Iron-54 with Alpha-Particles

Excitation functions for the (α, p ), (α, n ), (α, p n ), (α, 2 n ), (α, p 2 n +α, 3 n ), (α, α n ), (α, α p n ) and (α, α2 n ) reactions on Fe 54 were measured by the activation method using a “stacked-foil” technique, the alpha-particle energies ranging from 10 MeV to 40 MeV. The predominance of proton emission over neutron emission has been observed. The ratios of σ(α, p )/σ(α, n ) and σ(α, p n )/σ(α, 2 n ) in the region of maximum yield were found to be 3.4 and 60, respectively. The ratio of σ(α, α p n )/σ(α, α2 n ) at 40 MeV was about 180. A small “knee” was observed at the incident alpha-particle energy of about 20 MeV in the excitation function for the (α, 2 n ) reaction. The total reaction cross section was found to agree with the value calculated from continuum theory for a nuclear radius constant r 0 of 1.7×10 -13 cm assuming a nuclear square well potential.

Excitation Functions for Alpha-Induced Reactions on Manganese-55

Excitation functions for the reactions Mn/ sup55/( alpha ,n)Co/sup 58/, 5/( alpha ,n)Mn/sup 55/ and hod using a stacked-foil technique, the alpha- particle energies rangnng from 10 to 40 Mev. Bombardments were made with the alpha-particle beam of 32 and 40 Mev from the 160 cm INSJ cyclotron. The beam was collected in a Faraday cup and measured by a current integrator. After bombardments, manganese, cobalt, and iron were chemically separated. The disintegration rates of product nuclei Co/sup 58/, Co/sup 57/, Co/sup 56/, and Mn/ sup 54/ were obtained by the gamma-ray scintillation spectrometry, while that of Mn/sup 56/ by a calibrated end-window type Geiger counter. The reaction cross section was found to agree with calculated value for a nuclear radius constant r/ sub 0/ of 1.7 x 10/sup -13/ cm. Competition between different reactions was analyzed in terms of the statistical model of nuclear reaction by use of a level density expression of mu = c expSTA2(aE)/sup 1/2!, and agreed with the calculated values for a = 2 Mev/sup -1/. (auth)

Reactions of Argon-40 with Alpha-Particles

Excitation functions for the (α, p ), (α, n ), (α, p n ), (α, 2 n ), (α, p 2 n +α, 3 n ), (α, α n ), (α, α p n ) and (α, α2 n ) reactions on Fe 54 were measured by the activation method using a “stacked-foil” technique, the alpha-particle energies ranging from 10 MeV to 40 MeV. The predominance of proton emission over neutron emission has been observed. The ratios of σ(α, p )/σ(α, n ) and σ(α, p n )/σ(α, 2 n ) in the region of maximum yield were found to be 3.4 and 60, respectively. The ratio of σ(α, α p n )/σ(α, α2 n ) at 40 MeV was about 180. A small “knee” was observed at the incident alpha-particle energy of about 20 MeV in the excitation function for the (α, 2 n ) reaction. The total reaction cross section was found to agree with the value calculated from continuum theory for a nuclear radius constant r 0 of 1.7×10 -13 cm assuming a nuclear square well potential.

EXCITATION FUNCTIONS FOR ALPHA-PARTICLE REACTIONS ON Fe

Excitation functions for the (α, p n ), (α, p 2 n ), (α, 3 n ) and (α, α p n ) reactions on Fe 56 and the (α, α p ) reaction on Fe 57 were measured by the activation method using a stacked-foil technique, the alpha-particle energies ranging from 17 to 40 MeV. The measured excitation functions for the alpha-particle reactions on Fe 56 (present work) were compared with those for the proton reactions on Co 59 (Sharp et al.); the compound nucleus Ni 60 being the same for two cases. The comparison gives a test of the validity of compound nucleus theory. The ratios of corresponding cross sections seem to agree well with the theory (except in the case of resulting Co 57 ). However, it may be seen that the two curves corresponding to the same residual nucleus in each case do not entirly coincide in energy.

sup 56

Excitation functions of the Fe54( alpha ,n)Ni57 Fe54 ( alpha ,p)Co54, Fe54( alpha ,2n)Ni56, and Fe54( alpha ,p n)Co56 reactions were measured by the activation methods at 32 Mev.