Polarization of 12B in deep-inelastic heavy-ion reaction 100Mo(14N, 12B)

Spin polarization of ¹²B was measured for ¹⁰⁰Mo(¹⁴N, ¹²B) at $\text{E}{}_{\mathrm{<mtext>i</mtext>}}\text{(}{}^{14}\text{N}\text{) ? 200}\text{MeV}$ as a function of $\text{Q}$ value down to $\text{Q ? ?150}\text{MeV}$, and was found anti-parallel to $\text{k}{}_{\mathrm{f}}\text{×}\text{k}{}_{\mathrm{i}}$ in the deep-inelastic region. The data together with those at lower incident energies show a systematic trend in $\text{Q}$-value dependence of the polarization.     

Beta-ray spectra of 12B and 12N and conserved vector current

In order to investigate spectral shape factors of ¹²B and ¹²N, we make a new formalism of β-decay theory, where the radial wave functions of leptons are treated with no approximation and, therefore, the nuclear matrix elements are electron-energy dependent. With this formalism we can show strong support for the conserved vector current hypothesis in analyzing the experimental data which were given by Wu, Lee and Mo in 1963 and revised by them in 1977 using the latest experimental results on the end-point energies and branching ratios of the inner β-groups, in addition to the correct Fermi functions for the positron. In fact, the average slopes of the spectral shape factors for ¹²B and ¹²N are in excellent agreement with those in our theory. Recent experimental data given by the Heidelberg group are also in good agreement with the theory if we analyze the difference of the average slopes for ¹²B and ¹²N. There are, however, small discrepancies with the theory in their individual values. The relation of the present formalism with traditional theories of β-decay is discussed.     

Semiclassical analysis of the spin polarization of 12B in the 100Mo(14N, 12B)102Ru reaction

Polarization of ¹²B in the ¹⁰⁰Mo(¹⁴N, ¹²B)¹⁰²Ru reaction at 90 MeV incident energy is studied on the basis of the semiclassical theory of transfer reactions proposed by Brink. Gross behaviors of both the polarization and the cross section as functions of product kinetic energy can be predicted successfully by the theory. But disagreement in the numerical values of the polarization is found for low-energy ¹²B.     

Beta-ray angular distribution in aligned 12B and 12N and G-parity irregular induced tensor current

We made an explicit formula for beta-ray angular distribution by taking into account the radiative corrections, Coulomb corrections of the finite-size nucleus, weak magnetism, induced pseudoscalar, second-class induced tensor, and contributions of the d-wave leptons. Experimental data on the beta decays of aligned ¹²B and ¹²N given at Osaka are carefully investigated, and it is shown that these data are compatible with no induced tensor current, $\text{?}{}_{\mathrm{T}}\text{?}{}_{\mathrm{A}}\text{=}\text{?(0.44 +-0.88)}\text{2M}$. The nuclear parameter y is 3.3±0.9 in excellent agreement with the predicted value 3.6.     

The compound nucleus reaction 12C(11B, 2α) 15N

Energy spectra and differential cross sections of nitrogen products formed in the reaction 28 MeV ¹¹B + ¹²C have been measured using a ΔE?E counter telescope. The energy spectra are smooth and therefore indicate that the nitrogen products were formed by a compound nucleus mechanism, via the formation and decay of the compound nucleus ²³Na. The experimental results are compared with statistical model calculations and good agreement is obtained. This result provides further evidence for the importance of the compound nucleus mechanism in heavy ion reactions with light nuclei and also gives added validity to the statistical model for light compound systems.     

The 26Mg(14N, 10B)30Si and 26Mg(14N, 11B)29Si reactions

Reactions induced by ¹⁴N on ²⁶Mg at bombarding energies of 60–95 MeV have been studied. Angular distributions for states populated in ²⁹Si by the (¹⁴N, ¹¹B) reaction and in ³⁰Si by the (¹⁴N, ¹⁰B) reaction have been compared with Hauser-Feshbach and DWBA calculations to determine the reaction mechanism and to deduce spectroscopic information. The cross sections for the states populated in ²⁹Si and ³⁰Si are in poor agreement with statistical model calculations, indicating a non-compound nucleus mechanism.     

New measurements of the masses of 15B and 19N

The neutron-rich nuclei ¹⁵B and ¹⁹N have been produced in reactions between ¹⁸O and ⁴⁸Ca. Mass excesses of 28.968 ± 0.025 MeV and 15.872 ± 0.020 MeV respectively were deduced from the reaction Q-values. These results are compared with previous measurements and theoretical predictions. Updated predictions using two different mass formulae are presented.     

11B nuclear quadrupole interaction in metal hexaborides (MB6)

The magnitude of the electric field gradient at the boron nucleus, ¦eq¦, in divalent- and trivalent-metal hexaborides (MB₆) as well as in mixed-valent SmB₆ has been measured by the nuclear magnetic resonance method. In each group of divalent- and trivalent-metal hexaborides, ¦eq¦ decreases remarkably with increasing lattice parameter. At a given lattice parameter, ¦eq¦ for the trivalent-metal hexaborides is smaller than that for the divalent-metal hexaborides. The value of ¦eq¦ for SmB₆ is situated between those for the divalent- and trivalentmetal hexaborides. On the basis of these results, the electronic structure of the hexaborides is discussed.     

New measurements and reanalysis of 14N elastic scattering on 10B target

The angular distributions of elastic scattering of ¹⁴N ions on ¹⁰B targets have been measured at incident beam energies of 21.0 and 24.5 MeV. Angular distributions at higher energies 38–94.0 MeV (previously measured) were also included in the analysis. All data were analyzed within the framework of the optical model and the distorted waves Born approximation method. The observed rise in cross sections at large angles was interpreted as a possible contribution of the α-cluster exchange mechanism. Spectroscopic amplitudes SA₂ and SA₄ for the configuration ¹⁴N→ ¹⁰B +α were extracted. Their average values are 0.58±0.10 and 0.81±0.12 for SA₂ and SA₄, respectively, suggesting that the exchange mechanism is a major component of the elastic scattering for this system. The energy dependence of the depths for the real and imaginary potentials was found.     

Aspects of photonuclear (12N, 12B)-activity detection of explosives taking into account background photoneutrons

Some new approaches are proposed, which are aimed at estimating the neutron flux from the radiator and tested object, reducing the role of background photo- and neutron-nuclear reactions (including a two-layer radiator with an advantage for neutrons up to 3.6), and increasing the sensitivity under irradiation from two lateral sides of tested objects and detection of decay γ′ photons from four sides within a solid angle up to 8π/3. Original Russian Text ? L.Z. Dzhilavyan, 2009, published in Izvestiya Rossiiskoi Akademii Nauk. Seriya Fizicheskaya, 2009, Vol. 73, No. 6, pp. 846–852.     

Angular distributions of neutron polarization from the 14C(p,n)14N and 11B(α, n)14N reactions and R-matrix analysis oF 15N in the excitation-energy range between 11.5 and 12.5 MeV

Angular distributions of neutron polarization from the ¹⁴C(p, n)¹⁴N and ¹¹B(α, n)¹⁴N reactions have been studied for the particle energies E_p = 1.788, 2.025, 2.272 and 2.450 MeV, and E_α = 2.049 MeV. The polarization was derived from the left-right asymmetry induced by elastic scattering from ⁴He. Together with existing measurements of angular distributions and total cross sections for several reaction channels leading to ¹⁵N with an excitation energy between 11.5 and 12.5 MeV, these data were used to deduce from R-matrix analysis a set of resonance parameters for the ¹⁵N levels in this energy range.     

Light particle emission and projectile fragmentation in 14N + 12C

Quasi-complete in-plane correlations are measured between two heavy fragments (¹²C, ¹²C; ¹²C, ¹³C) which leave a missing mass such as n, p, d or p + n in ¹⁴N + ¹²C at 48 MeV. The use of two position-sensitive telescopes in coincidence allows an observation of data over 675 combinations of angles. The strongest coincidence yield concerns the ¹²C + ¹³C + p exit channel in which the target (¹²C) is left either in its ground state or in its first excited state ($\text{σ ? 40}\text{and}\text{15}\text{mb}$ respectively). No significant yield is found for the dissociations ¹²C + ¹²C + d, ¹²C + ¹³N + n or ¹²C + ¹⁰B + α at this energy.Using the reconstructed proton velocities, we obtain a source pattern in the rapidity plot which is roughly centered in the so-called mid-rapidity region. On the other hand, the Dalitz plot exhibits an enhancement of events which could be due to a projectile fragmentation $\text{(}{}^{14}\text{N}\text{→}{}^{13}\text{C}\text{+}\text{p}\text{)}$ via a real or virtual excitation energy of 8.7 MeV.     

Unexpected interference patterns observed in the 12C(14N, 13N)13C reaction at energies close to the Coulomb barrier

The reaction ¹²C(¹⁴N, ¹³N)¹³C has been measured at 28, 32, 34 and 36 MeV beam energies. The energy dependence of the measured interference pattern cannot be reproduced by DWBA calculations which take account of the interference between proton and neutron transfer. A rather strong asymmetry of the angular distributions about θ_c.m. = 90° has been observed.     

Temperature dependence of the hyperfine interactions of the β-emitter 12N in Ni

The temperature dependence of the magnetic hyperfine field and the nuclear spin-lattice relaxation time of ¹²N in Ni was determined in the region from 98 K to 773 K by use of NMR detection. The results are compared with recent predictions by a realistic band calculation.     

Sequential calculations for heavy-ion induced two-nucleon transfer on 14N, 15N and 16O

¹¹B and ¹³C induced two-nucleon transfer data on ¹⁴N, ¹⁵N and ¹⁶O are compared with exact finite-range sequential transfer calculations. The data appear to be consistent with this reaction model and the assumed shell-model structure of the states populated. Single-nucleon transfer data on these targets is also analyzed using the DWBA. Modifications to the exit channel optical potential are required to obtain agreement with shell-model spectroscopic factors.     

Angular distributions for target residues in reactions of 14N and 12C with 115In

Mechanisms of the reactions of ¹²C and ¹⁴N with ¹¹⁵In have been investigated by measuring the angular distributions of the target residues. Various possible transfer mechanisms are discussed with the help of kinematic analysis and a semiclassical transfer model. Interesting secondary (or tertiary) peaks are seen near 90 in the angular distributions for most target residues.     

Exact finite-range DWBA analyses of (12C, 11B) and (12C, 13C) reaction from 208Pb

A fast way to carry out the exact-finite range DWBA calculation is discussed, and is applied to the analyses of (¹²C, ¹¹B) and (¹²C, ¹³C) reaction from ²⁰⁸Pb.     

The 14N quadrupole coupling constants and barrier to internal rotation of ethylcyanide-d5

The microwave spectrum of ethylcyanide-d₅ has been recorded from 18.0 to 40.0 GHz. Both a-type and b-type transitions were observed and assigned. Also, the R-branch assignments have been made for three excited states of the internal torsional mode and two excited states of the CN inplane bending mode as well as an excited vibrational state involving both of these motions. The barrier to internal rotation was determined to be 3.00 ± 0.15 kcal/mole from the E, A splittings of the third excited state. The quadrupole coupling constants of the¹⁴N nucleus were found to have values of ?3.213, 1.168, and 2.045 MHz for χ_aa, χ_bb, and χ_cc, respectively. These results are compared to those previously obtained on the corresponding hydrogen compound.     

Three-nucleon transfer on 12C: The 12C(α, p)15N reaction at 96.8 MeV

Angular distributions of protons from the ¹²C(α, p)¹⁵N reaction have been measured over the angular range from 10–70° at an α-particle bombarding energy of 96.8 MeV. Well defined particle groups are observed up to an excitation energy of 18 MeV in ¹⁵N. The relatively small number of states excited implies a selectivity both in the reaction mechanism and in structure effects. DWBA calculations using a semi-microscopic three-nucleon form factor have been performed using several different sets of wave functions. Good agreement in the ratio σ_exp/σ_th is obtained for most states using the ¹⁵N wave functions of de Meijer. The strongest state in the (α, p) spectrum is observed at 15.397 MeV in ¹⁵N and DWBA calculations give good agreement for a $\text{13}\text{2}{}^{\mathrm{+}}$ assignment. This state has been observed only in other three-nucleon transfer reactions involving heavy ions. The recent discovery of a $\text{9}\text{2}{}^{\mathrm{+}}$ state at 10.693 MeV in a p+¹⁴C resonance measurement is supported by our analysis.     

Internal rotation and 14N quadrupole coupling of 3- and 5-methylisoxazole

In the following we present a ¹⁴N quadrupole hyperfine structure, a fourth-order centrifugal distortion, and an IAM methyl internal rotation analysis of 3- and 5-methylisoxazole. The measurements were done in the frequency range of 8 to 26 GHz employing a microwave Fourier transform spectrometer.