The isomeric ratios in some photonuclear reactions (γ, n), (γ, p), (γ, 2n), and (γ, np) induced by bremsstrahlungs with end-point energies in the Giant Dipole Resonance region

We have determined the isomeric ratios in photonuclear reactions ¹¹⁶Cd(γ, n)^{115m, g} Cd, ¹³⁸Ce(γ, n)^{137m, g} Ce, ¹⁵³Eu(γ, n)^{152m, g} Eu, ⁹⁶Mo(γ, p)^{95m, g} Nb, ¹¹⁸Sn(γ, p)^{117m, g} In, ⁸⁹Y(γ, 2n)^{87m, g} Y, ¹⁰⁶Cd(γ, np)^{104m, g} Ag, and ¹¹²Sn(γ, np)^{110m, g} In induced by bremsstrahlungs with end-point energies in the Giant Dipole Resonance (GDR) region. The targets were irradiated at electron accelerator Microtron MT-25 of the Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Dubna. Gamma spectra of irradiated samples were measured with a spectroscopic system consisting of 8192-channel analyzer and high-energy resolution (180 keV at gamma ray 1332 keV of ⁶⁰Co) semiconductor detector CANBERRA. The results were discussed and compared with those of other authors. The article is published in the original.     

Calculations on (γ, p) and (γ, n) reactions at photon energies between 40 and 100 MeV

Shell-model calculations with and without short-range correlations have been carried out for the reactions (γ, p) and (γ, n) in the energy region from 40 to 100 MeV. The cross sections for the ¹⁶O(γ, p)¹⁵N process have been investigated in the single-particle model. The results strongly depend on the initial state wave functions especially at high energies. There are large effects on the cross sections if orthogonality between bound and continuum states is violated. For the reaction ¹⁶O(γ, n)¹⁵O it is shown that short-range correlations in the ground state of ¹⁶O do not contribute appreciably to the cross sections, at least up to a photon energy of 100 MeV.     

Excitation of isomeric states in the (γ,n), (n, 2n), and (γ, 2n) reactions on the 113In nucleus

The induced-activity method was used to measure the isomeric ratio of the yields of the (γ, n), (n, 2n), and (γ, 2n) reactions on the ¹¹³In nucleus. The energy dependence of the isomeric ratios of the yields of the photonuclear reactions ¹¹³In(γ, n)^112m,g In and ¹¹³In(γ, 2n)^111m,g In is studied in the energy range of 12–35 MeV.     

Study of the 4He (γ, p)3H and 4He(γ, n)3He reactions

The cross sections and angular distributions for ⁴He(γ, p)³H and ⁴He(γ, n)³He have been measured.     

New data on (γ, n), (γ, 2n), and (γ, 3n) partial photoneutron reactions

Systematic discrepancies between the results of various experiments devoted to determining cross sections for total and partial photoneutron reactions are analyzed by using objective criteria of reliability of data in terms of the transitional photoneutron-multiplicity function F _i = σ(γ, in)/σ(γ, xn), whose values for i = 1, 2, 3, ... cannot exceed by definition 1.00, 0.50, 0.33, ..., respectively. It was found that the majority of experimental data on the cross sections obtained for (γ, n), (γ, 2n), and (γ, 3n) reactions with the aid of methods of photoneutron multiplicity sorting do not meet objective criteria (in particular, F ₂ > 0.50 for a vast body of data). New data on the cross sections for partial reactions on ¹⁸¹Ta and ²⁰⁸Pb nuclei were obtained within a new experimental-theoretical method that was proposed for the evaluation of cross sections for partial reactions and in which the experimental neutron yield cross section σ ^expt(γ, xn) = σ(γ, n) + 2σ(γ, 2n) + 3σ(γ, 3n) + ..., which is free from problems associated with determining neutron multiplicities, is used simultaneously with the functions F _i ^theor calculated within a combined model of photonuclear reactions.     

Systematics of (γ, 2n) reactions

The (γ, n) and (γ, 2n) cross sections in I¹³⁷ and Au¹⁹⁷ were mesured from threshold up to 22 MeV. A comparison is made between the experimental result and the evaporation theory. Other data available in the literature are included.     

Cross sections for some (n,p) and (n, α) reactions

The cross sections for the Mg²⁴(n, p) Na²⁴, Al²⁷(n, α)Na²⁴, Si²⁸(n, p)Al²⁸, Cr⁵²(n, p)V⁵² and Fe⁵⁶(n, p)Mn⁵⁶ reactions have been measured for neutrons produced by the H³(d, n) He⁴ reaction. The activation method was used, with the gamma rays which are emitted following beta decay being counted with a Na(Tl) scintillation crystal. The Mg²⁴(n, p)Na²⁴ cross section is found to be 219±26 mb at 13.0 MeV. The Al²⁷(n, σ)Na²⁴ cross section varies smoothly from 139 mb at 13.0 MeV to 106 mb at 15.7 MeV. The Si²⁸(n, p)Al²⁸ cross section changes smoothly from 370 mb at 12.3 MeV to 160 mb at 18.3 MeV, with a broad peak at 13.5 MeV with the maximum value of 380 mb. The Cr⁵²(n, p)V⁵² cross section decreases slowly from 125 mb at 12.3 MeV to 72 mb at 18.3 MeV. The Fe⁵⁶(n, p)Mn⁵⁶ cross section is found to be 131±15 mb at 15.3 MeV. The results are generally in agreement in those cases where previous results of others exist.     

Cross sections and rates of the thermonuclear reactions 64Zn(p,γ)65Ga and 66Zn(p,γ)67Ga

The excitation functions for the reactions of radiative proton capture, ⁶⁴Zn(p,γ)⁶⁵Ga and ⁶⁶Zn(p,γ)⁶⁷Ga, which are of interest for stellar nucleosynthesis, have been measured in the range of incidentproton energies from 1 to 2.8 MeV. The astrophysical S factor and reaction rates have been derived from the reaction cross sections. The experimental results are compared with the predictions of the Hauser-Feshbach statistical theory.     

Excitation functions of 40Ar(p,p′γ)40Ar and 40Ar(p,γ)41K reactions

The excitation functions of ⁴⁰Ar(p,p′γ)⁴⁰Ar and ⁴⁰Ar(p,γ)⁴¹K reactions are measured in the E _p = 1.0–3.0 eV range of accelerated protons. The excitation function in the E _p > 2.6 MeV range of accelerated protons is measured for the first time. The strengths of all (more than 200) measured resonance states are calculated.     

Relaxation of the analyzing power of the (p, τX) and (p, αX) reactions in the continuum

The observed continuous decrease of the analyzing power for the reactions ($\text{p}$, τX) and ($\text{p}$, αX) on ⁹⁰Zr and ²⁰⁹Bi at E_p = 72 MeV as a function of the excitation energy of the final nucleus is described by a phenomenological relaxation process.     

Nuclear structure studies of 125Te with (n,γ), (d,p) and (3He,α) reactions

Levels in ¹²⁵Te were investigated in the range up to 3.3 MeV excitation energy by the (n,γ), (d,p) and (³He,α) reactions. Over 160 levels and about 360 γ-transitions were established, most for the first time. The states below 2.3 MeV with the most complete spectroscopic information were interpreted in terms of the interacting boson-fermion model (IBFM). Unitary treatment of both positive- and negative-parity states is achieved with the same model parameter close to the intermediate case between O(6) and U(5) limits. Excitation energies, electromagnetic transition rates, γ-branchings and spectroscopic factors are discussed in connection with the possible structures. A family of low-spin negative-parity states has been identified and understood by the IBFM proving their antialigned origin.     

Spectroscopy of 88Sr with the 87Sr(n, γ) and 87Sr(d,p) reactions

The γ-ray spectrum emitted after thermal neutron capture in ⁸⁷Sr was studied at the ILL high flux reactor with pair- and intrinsic Ge-spectrometers. 661 transitions were assigned to the reaction ⁸⁷Sr(n, γ)⁸⁸Sr and 205 of them were placed into a ⁸⁸Sr level scheme of 47 levels. This represents 88% of the observed intensity. The level energies were determined with a precision of better than 20 ppm; the neutron binding energy was determined as 11 112.69 (22) keV. To aid the analysis high resolution particle spectra of the reaction ⁸⁷Sr(d, p)⁸⁸Sr were measured at 20 MeV deuteron energy with the Munich Q3D spectrometer. 85 states were observed with this reaction. The data helped to establish newly found levels and to differentiate between primary and secondary transitions in the (n, γ) data. The observed level densities and primary transition strengths are compared with statistical model predictions and non-statistical effects are discussed.