Experimental investigation of the 19F(n, α)16N reaction excitation function in the neutron energy range of 4 to 7.35 MeV

The interaction of neutrons with light nuclei study is of interest for understanding nuclear-reaction mechanisms. Fluorine nuclei are worth particular attention because they are abundant in the core of the promising molten-salt reactors and can noticeably affect the chain reaction kinetics. In this work we have experimentally investigated the ¹⁹F(n, α)¹⁶N reaction cross-section at neutron energies ranging from 4 to 7.35 MeV.     

Investigation of the 9Be(3He,n)11C reaction in the energy range 3.5–10 MeV

The excitation functions and angular distributions of neutrons from the ⁹Be(³He, n)¹¹C reaction leading to the ground and first excited states of ¹¹C have been measured in the energy range 3.49–9.96 MeV. The behaviour of the excitation cruves and the oscillatory pattern of angular distributions indicate that a direct interaction process is predominant in the ⁹Be(³He, n)¹¹C reaction especially at the incident energies above 5 MeV. The angular distributions obtained at several bombarding energies have been compared with the results of DWBA calculations based on a two-nucleon stripping process, and good agreement is obtained for the data taken at 9.93 MeV. The agreement is not satisfactory at lower incident energy region, where the reaction process seems to be more complex. The neutron group leading to the first excited state of ¹¹C shows a L = 2 pattern in higher energy region in contrast with the L = 0 pattern of the photon group observed in the mirror reaction ⁹Be(³He, p)¹¹B. This is consistent with a selection rule for the di-proton stripping reaction and indicates that the two-nucleon stripping process is predominant in the ⁹Be³He reaction.     

Study of the reaction 12C (α, γ0)16O in the excitation energy range 14 to 24.7 MeV

The differential cross-section at 45⁰ for the reaction ¹²C (α, γ₀)¹⁶O has been measured for incident energies from 8.75 to 23.50 MeV. Over the entire range the cross-section is smaller than 0.5 μb/sr. Three major resonances were investigated and their parameters are presented.     

An analysis of the 12C(d, α)10B reaction in the energy range 9.2–13.9 MeV

Previous measurements of the ¹²C(d, α)¹⁰B reaction at E_d = 9.2−13.9 MeV leading to the ground state and to the first, third and fourth excited states of ¹⁰B have been analysed in terms of the Glendenning two-nucleon transfer theory. The theoretical results are in poor agreement with experiment. At E_d = 19.7 MeV, better agreement has been obtained between theory and experiment. Excitation functions of low-energy resolution, derived from differential cross sections in the (d, α), (d, d) and (d, p) channels, show resonances indicating that effects due to the intermediate nucleus ¹⁴N play a role in the processes investigated.     

Modeling the efficiency of neutron detection scintillators in the energy range of 5–70 MeV

The instrumental functions for neutron godoscope detectors used in studying the nd-breakup reaction are obtained. The effect on light output of contributions from different processes that occur in a scintillator under the effect of neutrons is examined at different energies of the incident neutrons. The relationship between the detector??s efficiency and neutron energies ranging from 5 to 70 MeV is obtained for different thresholds.     

Study of the 24Mg(α, 12C)16O reaction in the energy range Elab = 24.9–27.76 MeV

The ²⁴Mg(α,¹²C)¹⁶O and ²⁴Mg(α, α')²⁴Mg reactions have been used to search for resonances in the ²⁸Si compound nucleus. The excitation functions were measured in the energy range between 24.9 and 27.76 MeV. Angular distributions of ¹²C nuclei and elastic and inelastic scattering of α-particles have been measured at energies corresponding to extrema of excitation functions. Significant anomalies have been found at E_ex = 31.5 and 33,1 MeV. The spins and parities of these structures are assigned as 9⁻ and 11⁻, respectively.     

18F production in the 19F(γ, n) reaction

A race-track microtron is used to measure the yield of ¹⁸F in the reaction ¹⁹F(γ, n) at an energy of the electron beam of 55 MeV. ¹⁸F is widely used in positron emission tomography for high-sensitivity diagnostics. The currently available data are not sufficient to make accurate estimates of the yield of ¹⁸F in isotope production experiments using the reaction (γ, n). The value of σ^?1 estimated in this work is (1.7 ± 0.1) mb.     

Measurements of differential and angle-integrated cross sections for the ~(10)B(n, α)~7Li reaction in the neutron energy range from 1.0 eV to 2.5 MeV

Differential and angle-integrated cross sections for the ~(10)B(n,α)~7 Li,~(10)B(n,α_0) ~7 Li and ~(10)B(n,α_1) ~7 Li~*reactions have been measured at CSNS Back-n white neutron source.Two enriched(90%) ~(10)B samples 5.0 cm in diameter and～85.0 μg/cm~2 in thickness each with an aluminum backing were prepared,and back-to-back mounted at the sample holder.The charged particles were detected using the silicon-detector array of the Light-charged Particle Detector Array(LPDA) system.The neutron energy En was determined by TOF(time-of-flight) method,and the valid a events were extracted from the E_n-Amplitude two-dimensional spectrum.With 15 silicon detectors,the differential cross sections of a-particles were measured from 19.2°to 160.8°.Fitted with the Legendre polynomial series,the(n,a) cross sections were obtained through integration.The absolute cross sections were normalized using the standard cross sections of the ~(10)B(n,α) ~7 Li reaction in the 0.3-0.5 MeV neutron energy region.The measurement neutron energy range for the ~(10)B(n,α) ~7 Li reaction is 1.0 eV≤E_n 2.5 Me V(67 energy points),and that for the ~(10)B(n,α_0) ~7 Li and~(10)B(n,α_1) ~7 Li~*reactions is 1.0 eV≤E_n1.0 MeV(59 energy points).The present results have been analyzed by the resonance reaction mechanism and the level structure of the ~(11)B compound system,and compared with existing measurements and evaluations.     

Investigation of the40Ca(γ,N) reaction at 60 MeV

The values of the angle-integrated cross section for the decay to various low-lying states in³⁹K following the⁴⁰Ca(,) reaction at a mean photon energy of 60 MeV are reported on, together with the values of the reduced Legendre coefficientsa _i . The⁴⁰Ca(,gp) and⁴⁰Ca(,n) reactions yield the same angular cross-section values and these agree with the corresponding RPA-calculations.Senior Research Associate NFWO     

Cross-sections of isomeric state excitation of the 119Te and 121Te nuclei in (γ, n) reactions in an energy range of 9–20 MeV

The dependence of isomeric yield ratios upon the maximum bremsstrahlung gamma-quanta energy for the ¹²⁰Te(??, n)^119m,g Te and ¹²²Te(??, n)^121m,g Te reactions within an energy range of the giant dipole resonance is investigated. Cross-sections of excitation of metastable states with J ^?? = 11/2^? of the ¹¹⁹Te and ¹²¹Te nuclei are obtained. Experimental data are compared with computation results obtained using the TALYS-1.2 software package.     

On the spin assignment of neutron resonances in 149Sm using (n, α) reaction

Measurements of thermal-neutron cross sections for the ¹⁴⁹Sm(n, α)¹⁴⁶Nd reaction have been done using a 99% enriched ¹⁴⁹Sm target. Results are compared with theoretical values of cross sections calculated on the basis of the compound nucleus and statistical model. Experimental and calculated values are consistent only when assuming that the spins of the bound state and the 0.0967 eV resonance in ¹⁴⁹Sm+n are 3⁻ and 4⁻, respectively. For such a spin sequence the 2200 m/sec experimental neutron cross sections are: 46.0±5 mb for ¹⁴⁹Sm(n, α) ¹⁴⁶Nd₂₊ and 8.5±1.5 mb for ¹⁴⁹Sm(n, α)¹⁴⁶Nd₀₊.     

Investigation of 238U in the (n,n′γ) reaction

An irradiation of ²³⁸U with a beam of reactor fast neutrons permits revealing about 550 gamma transitions associated with the respective (n, n′γ) reaction and with fission fragments. The use of all known data on gamma radiation from fission fragments makes it possible to identify gamma transitions belonging to ²³⁸U with a high probability. The scheme of levels and gamma transitions is composed for ²³⁸U. New levels (including those of spin-parity J ^π = 0⁺) at excitation energies below 2 MeV are proposed. The low-lying levels in the rotational band for two-phonon octupole excitations are determined. It is found that a hybrid state is formed upon the crossing of this band and the band based on two-quasiparticle excitations. This hybrid state must involve excitations of both types. A small value of the rotational-band parameter in the isomer of energy 2559.0(4) keV is explained by the contribution to this state from two-quasiparticle configurations belonging to the 1k _17/2 subshell. The same circumstance may also be responsible for an enhanced yield of ternary fission for this isomer.     

Pion-Nucleus potentials in the energy range of 0–80 MeV

Data for the elastic scattering of 30–80 MeV positive and negative pions by a wide range of nuclei is analysed with an Ericson-Ericson MSU type optical potential. By use of consistent sets of data for π⁺ and π⁻ and of experimental results for total reaction cross sections we obtain for the first time optical potentials that describe well all the data without the need of introducing non-standard charge-dependent effects.     

14N(n, α)11B reaction at 14.1 MeV

Natural N₂ gas was bombarded with 14.1 MeV neutrons, and alpha particles from ¹⁴N (n, α)¹¹B reactions were observed with a telescope consisting of two proportional counters and a CsI(Tl) scintillator. Absolute differential cross sections were measured for the (n, α) transitions to the ground state and to the 2.14 MeV level of ¹¹B. The observed angular distributions were fitted with curves, calculated using two-mode PWBAE, ³He pick-up and diffraction theories.     

Measurement of the $$^{232}$$ Th(n,f) cross section with quasi-monoenergetic neutron beams in the energy range 2–18 MeV

The European Physical Journal A - The E1 contribution to the capture reaction $$^7\mathrm {Li}(n,\gamma )^8\mathrm {Li}$$  is calculated at low energies. We employ a coupled-channel...     

Measurement of the 85Rb(γ, n)84mRb cross-section in the energy range 10-19 MeV with bremsstrahlung photons

We study the charmonium 2S states ??? and ??? _c , and the bottomonium 2S states ???? and ??? _b , using the light-front quark model and the 2S state wave function of harmonic oscillator as the approximation of the 2S quarkonium wave function. The decay constants, transition form factors and masses of these mesons are calculated and compared with experimental data. Predictions of quantities such as Br(???????? _c ) are made. The 2S wave function may help us learn more about the structure of these heavy quarkonia.     

Investigation of 166Er in the respective (n,n′γ) reaction

Physics of Atomic Nuclei - The spectrum, angular distribution, and linear polarization of gamma rays from the (n, n′γ) reaction on 166Er were measured in a beam of reactor fast neutrons....