Study of the isomeric ratios in photonuclear reactions of natural Selenium induced by bremsstrahlungs with end-point energies in the giant dipole resonance region

Coupling of (ultra-) relativistic atomic nuclei with photons

“…A higher enhancement can be obtained by taking into account the aberration of light, even from a collimated laser. 31−33 Indeed, for a cross-sectional beam area D 2 = (0.5mm) 2 we get an intensity I = P/D 2 = 4 × 10 17 w/cm 2 and an electric field E ≃ 5 × 10 7 statvolt/cm (all the other parameters being the same). In the rest frame of the ion the power increases by a factor (1−β) −1 , as before, but the cross-sectional area D ′ 2 of the beam, decreases by a factor (1−β)/(1+β) (≃ 1/4γ 2 ), as a consequence of the "forward beaming" (aberration of light); 28 we have D ′ 2 = D 2 (1 − β)/(1 + β), which leads to an enhancement factor (1+β)/(1−β) 2 for intensity and a factor (1+β…”

Photonuclear reactions on stable isotopes of selenium at bremsstrahlung end-point energies of 10−23 MeV

“…The ratio of the probabilities of excitation of states T > and T < is described by the following relation (6):…”

“…In [5], on bremsstrahlung, the cross section for reactions σ(γ, n) on all isotopes of natural selenium were measured up to an energy of 25 MeV. In [6], the same method was used to measure the cross sections for the reactions 78 Se(γ, n) 77m Se, 80 Se(γ, n) 79m Se, and 82 Se(γ, n) 81m Se. In [16−20], on a beam of quasi-monoenergetic photons obtained as a result of Compton backscattering, the cross sections for reactions σ(γ, n) were measured in the energy range from the threshold to 14.6 MeV on 76,77,78,80 Se isotopes.…”

“…The development of both nuclear physics research and applications based on photonuclear reactions is closely related to the development of attendant photon sources and measuring instruments. Photoneutron reactions on isotopes of natural mixture of selenium have been well studied using bremsstrahlung γ-radiation [5][6][7][8][9][10][11][12][13][14], positron annihilation in flight [15] and Compton backscattering of laser beam photons [16][17][18][19][20]. Cross sections of photonuclear reactions at selenium isotopes in the region of energy giant dipole resonance were measured in several works.…”