Production of high-spin isomers in proton induced reactions at100–500MeVonTa181

Abstract

Cross sections for production of a broad variety of high-spin isomers, i.e., 177 Hf m2 ͑37/2 − ͒, 179 Hf m2 ͑25/2 − ͒, 177 Lu m ͑23/2 − ͒, 180 Hf m ͑8 − ͒, and 178 Ta m ͑7 − ͒ from 181 Ta targets irradiated with 100, 145, 200, 350, and 500 MeV protons have been measured by off-line ␥-spectroscopy. A radiochemical procedure was used to achieve high sensitivity. Isomer ratios in products ranging down to 10 −3 were based on experimentally measured and theoretically calculated cross sections. It was demonstrated that the isomer ratio does not depend essentially on proton energy in the given range. Regularities in formation of isomeric states in different nuclear reactions are discussed.

Isomeric Ratio of the $^{181}\rm{Ta}(γ,3n)^{178m,g}\rm{Ta}$ Reaction Products at Energy $E_{\rm{γmax}}$ up to 95 MeV

“…In [41], the isomeric ratios of the reaction products 181 Ta(p, p3n) 178m,g Ta were obtained at proton energies of 100, 145, 200, 350, and 500 MeV using by off-line γ-spectroscopy. It is shown that the obtained isomeric ratios are constant and close to d(E) ∼ 0.37-0.38 at 100-500 MeV.…”

Production of the 178m2Hf isomer using a 4.5-GeV electron accelerator

“…This is not very surprising, recalling that the σ m /σ g ratio therefrom changes rather slowly with the proton energy [5,6], conˇrmed later in Ref. [14].…”

“…Finally, the contribution of the electronuclear interaction was found to be about 0.13 Y phr , where Y phr was the yield determined before for the photonuclear reaction. The calculated productivity under optimum conditions was then corrected to include both secondary and electron-induced processes, giving a total yield: Y opt = 3.2 • 10 9 atoms/(s • 100 µA) (14) for the 178m2 Hf isomer. This is about 8 times lower than the yield achieved at Los Alamos with a proton beam of the same current.…”

Production of isomeric states in the deuteron-induced reaction of gold at incident energy 4 GeV

“…As a result, the primary products originating from reaction remnants, have a wide range of angular momenta and excitation energies. The comparison of the measured isomer cross section ratios with calculations within different statistical models [2,3] helps to estimate the spin associated with the reaction products, produced in different exit channels.…”