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.     

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...     

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.     

Resonance strength measurements of the 27Al(p,γ)28Si reaction in the energy range Ep= 0.8–2.0 MeV

An excitation function of the ²⁷Al(p,%)²⁸Si reaction has been measured over the proton beam energy range E_p = 800-2000 keV using a 4? NaI segmented crystal. In the above energy range 47 narrow resonances were measured and their strengths have been deduced. The absolute efficiency of the detection system has been determined for each one of the resonances via Monte-Carlo simulation, taking into account the decay scheme of each resonance. The results of the present work are compared with literature.     

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.     

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.     

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.     

Time features of delayed neutrons and partial emissive-fission cross sections for the neutron-induced fission of 232Th nuclei in the energy range 3.2–17.9 MeV

The energy dependence of the relative abundances of delayed neutrons and the energy dependence of the half-lives of their precursors in the neutron-induced fission of ²³²Th nuclei in the energy range 3.2–17.9 MeV were measured for the first time. A systematics of the time features of delayed neutrons is developed. This systematics makes it possible to estimate the half-life of delayed-neutron precursors as a function of the nucleonic composition of fissile nuclei by using a single parameter set for all nuclides. The energy dependence of the partial cross sections for emissive fission in the reaction ²³²Th(n, f) was analyzed on the basis of data obtained for the relative abundances of delayed neutrons and the aforementioned half-lives and on the basis of the created systematics of the time features of delayed neutrons. It was shown experimentally for the first time that the decrease in the cross section after the reaction threshold in the fission of ²³²Th nuclei (it has a pronounced first-chance plateau) is not an exclusion among the already studied uranium, plutonium, and curium isotopes and complies with theoretical predictions obtained for the respective nuclei with allowance for shell, superfluid, and collective effects in the nuclear-level density and with allowance for preequilibrium neutron emission     

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.     

Energy deposition and GDR emission in the reaction 209Bi(α,α′) at 240 MeV

Neutron fold distributions measured for the reaction ²⁰⁹Bi(α,α′) at 240 MeV have been analyzed with the help of Statistical Model calculations to determine the distribution of excitation energy, E_x, in the primary target fragments as a function of the projectile energy loss, EL. The reconstructed distributions in excitation energy feature a plateau which extends from the kinematical limit E_x = EL to very small excitations, indicating a variety of interactions of the beam particles with the target nucleus. The requirement of an additional coincidence with a light charged particle leads to the selection of a significant higher average excitation energy. Those results are extrapolated to explore the effects of including the excitation energy distributions in the analysis of previous GDR measurements in ²⁰⁸Pb. Corrections of the derived GDR parameters due to the partial transfer of excitation energy are suggested.     

Study of the reaction Li7(p, α)α up to 12 MeV proton energy

The Li⁷(p, α)α reaction has been studied up to 12 MeV proton energy. Four alpha emitting states in Be⁸ are observed. The results are discussed in terms of reaction mechanism and levels in Be⁸.     

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

New method based on ionization chamber with Frisch grid and digital signal processing was developed for experimental investigation of ¹⁹F(n, α)¹⁶N reaction. The chamber filling gas with CF₄ additive was used as the fluorine-containing target. The experimental investigation of ¹⁹F(n, α)¹⁶N reaction cross-section in 4–7.35 MeV energy range is represented in this work. The total cross section of ¹⁹F(n, α)¹⁶N reaction was measured as well as partial cross-section for sum of α₀-α₃ and sum of α₄ and α₅ reaction channels.     

The 11B(α, p)14C reaction below 1.7 MeV bombarding energy

For estimation of the production rate of the long-lived ¹⁴C isotope originating in the controlled thermonuclear synthesis ¹¹B + p the total cross section of the ¹¹B(α, p)¹⁴C reaction has been determined in the energy range of α-particles E_α = 0.9−1.7 MeV. Five resonances corresponding to states in ¹⁵N have been observed. The assignment of the resonance parameters is discussed.     

Microscopic analysis of the energy dependence of the 6He, 6Li + 28Si total reaction cross sections in the energy range E = 5−50 A MeV

The experimental data on the total cross sections of the ^{4, 6}He, ^{6, 7}Li + ²⁸Si reactions at energies E=5−50 A MeV are reported. The data for the ⁶Li, ⁶He + ²⁸Si reactions have been analyzed within the microscopic model of double-folding optical potential, in which the real and imaginary parts are calculated at different densities of the projectile nucleus. The cross sections calculated with the microscopic double-folding Coulomb potential and the standard Coulomb potential for uniform charge distribution are compared with each other. Semimicroscopic potentials providing agreement with experimental data have been constructed on the basis of renormalized microscopic potentials and their derivatives, added to take into account collective effects. Original Russian Text ￠ K.V. Lukyanov, E.V. Zemlyanaya, V.K. Lukyanov, I.N. Kukhtina, Yu.E. Penionzhkevich, Yu.G. Sobolev, 2008, published in Izvestiya Rossiiskoi Akademii Nauk. Seriya Fizicheskaya, 2008, Vol. 72, No. 3, pp. 382–386.     

Baryon resonances of the proton and few-body systems in the 200–800 MeV energy range

The total photoabsorption cross sections for ¹H, ²H, ³He, and ⁴H have been measured (for the first time for ³He) with high precision on the MAMI-B accelerator (Mainz, Germany) with a tagged photon beam and the large acceptance detector DAPHNE. The dynamics of baryon resonances along the periodic table is analyzed, and they are compared with the sum of partial reactions on proton and deuteron. Preparation and the first stage of polarization measurements of photoabsorption cross sections on proton in the Δ resonance region are reported.     

Search for e + e − → f 0(600)γ, f 0(980)γ, f 0(1350)γ, and f 2(1270)γ processes in the energy range from 1.05 to 1.38 GeV

In the energy range from 1.05 to 1.38 GeV, the upper limits for the cross sections of e ⁺ e ^? → f ₀(600)γ, f ₀(980)γ, f ₀(1350)γ, and f ₂(1270)γ → π⁰π⁰γ processes have been established. Measurements are performed in accordance with the statistics gathered in experiment with a spherical neutral detector (SND) on the VEPP-2M e ⁺ e ^? collider. The resultant upper limits vary from 6 to 42 pb depending on the energy and the model.