A resonant interpretation of gross structure in 12C + 12C and16O + 16O inelastic scattering

A barrier-top-resonance model calculation is found adequate to describe the gross structure behavior thus far observed in ${}^{12}\text{C}\text{+}{}^{12}\text{C and}{}^{16}\text{O}\text{+}{}^{16}\text{O}$ inelastic scattering excitation functions.     

Them-state population of12C2+ in inelastic scattering

The spin alignment of the¹²C₂ ⁺ state in inelastic scattering of¹²c on⁶⁴zn at E_L=65 MeV has been measured using the γ-recoil-in-flight method. Good agreement with coupled channel calculations are obtained. The sensitivity of the spin alignment to reaction models is discussed.     

Limitation of angular momentum transfer in adiabatic calculations of rotational excitation by inelastic scattering

A new method is proposed for quantummechanical calculations of rotational excitation of nuclei by inelastic scattering. It is based on a combination of coupled-channels method (few-states approximation) and adiabatic method. Results are presented for α scattering from ¹⁷⁶Yb.     

Magnitude and alignment of transferred angular momentum in both quasi and deeply inelastic scattering

In-plane and out-of-plane angular correlations of fission fragments in coincidence with projectile-like fragments have been measured for the ⁸⁶Kr + ²³⁸U reaction at 730 MeV. The dependence of the magnitude and alignment of the angular momentum transferred to the fissioning heavy reaction product has been determined. Both quantities decrease strongly with decreasing energy loss in the quasi elastic region, in agreement with the predictions of a transport model.     

Transverse momentum in semi-inclusive deep inelastic scattering

Within the framework of perturbative quantum chromodynamics we derive the evolution equations for transverse momentum dependent distributions and apply them to the case of semi-inclusive deep inelastic scattering. The evolution equations encode the perturbative component of transverse momentum generated by collinear parton branchings. The current fragmentation is described via transverse momentum dependent parton densities and fragmentation functions. Target fragmentation instead is described via fracture functions. We present, to leading logarithmic accuracy, the corresponding semi-inclusive deep inelastic scattering cross-section, which applies to the entire phase space of the detected hadron. Some phenomenological implications and further developments are briefly outlined.     

Nonconservation of angular momentum in aharonov-bohm scattering

Aharonov-Bohm (AB) scattering by the vector potential of an infinitely long impenetrable solenoid of zero radius which carries magnetic flux is shown to violate the conservation of angular momentum. The difficulty is due to improper boundary conditions for a scattering problem used by AB.     

Spin alignment in12C+12C inelastic scattering

The spin alignment P_zz of¹²C(2 ₁ ⁺ ) produced in¹²C+¹²C inelastic scattering at bombarding energies in the region of known resonances between E_cm=18.5 and 32.8 MeV has been determined with a γ-ray detector positioned in the direction of the scattering normal. The values obtained in the centers of three resonances as well as those obtained off-resonance are spread over a range between ?.05 and +.80 with no clear indication in favour of simple pictures of molecular resonances.     

Spin alignment in resonant C+O inelastic scattering

The spin alignment of the 3⁻ state (6.13 MeV) of ¹⁶O from inelastic scattering of ¹²C+¹⁶O has been measured in the energy region of known resonances around E_cm=20 MeV. The result, that the population of the m=±3 magnetic substates is enhanced on four resonances at 19.7, 20.5, 22.0 and 22.6 MeV, indicates the dominance of the aligned configuration on these resonances.     

Intrinsic transverse momentum and structure function evolution in deep inelastic lepton hadron scattering

A model is constructed that allows to implement intrinsic transverse momentum and target mass in the QCD analysis ofQ ²-evolution of structure functions in deep inelastic lepton hadron scattering without losing the factorization property of mass singularities. The modified evolution equations are integrated numerically and the results are compared to experimental data. It turns out that no further higher twist contributions are required.     

Bombarding energy dependence of angular momentum transfer in deep inelastic collisions

Measurements of first and second moments of γ-ray multiplicity distributions from deep inelastic collisions of ⁸⁶Kr + ¹⁵⁴Sm are reported. A global systematics of the angular momentum distributions from deep inelastic reactions with projectile masses ? 40 is presented. The average angular momentum is found to depend linearly on the incident channel average angular momentum, while no simple systematics for the second moment appears obvious. In order to illuminate the question whether the angular momentum transfer process reaches statistical equilibrium in deep inelastic collisions, numerical calculations have been performed on two models: a two-sphere classical model including the collective modes of twisting, bending, wriggling and tilting, and a statistical equilibrium Fermi-gas model. The two-sphere classical model is not able to account for the observed second moments, and neither does the Fermi-gas model give an explanation of the deep inelastic multiplicity data.     

Width-fluctuation effects in angular correlation in inelastic nucleon scattering

The effects of level-width fluctuations on the nucleon-gamma angular correlations and double-differential cross sections have been studied on the basis of Moldauer's formulation. Computational procedures for pursuing the width-fluctuation studies on a routine basis for reactions following the compound nucleus mechanism have been developed. The width-fluctuation effects in (n, n'γ) reactions with ²⁴Mg and ⁵⁶Fe have been calculated. These calculations indicate that the inclusion of width-fluctuation considerations significantly reduces the double differential cross sections compared to those made on the basis of Hauser-Feshbach theory. However, as expected, the shape of the angular correlation function is not siginificantly altered by the width-fluctuation corrections.     

Failure of the molecular core-particle coupling model in C+C inelastic scattering

The single and mutual inelastic excitation of the predominantly single particle p_1/2 →s_1/2 transition in ¹³C has been studied at energies of 8–25 MeV in the center-of-mass system. The results are in striking disagreement with theoretical predictions made using the molecular particle-core coupling model. It is suggested that intermediate states involving different partitions of the valence nucleons among the cores play an important role in these reactions.     

CompleteO(α s 2 ) corrections to (2 + 1) jet cross sections in deep inelastic scattering

Complete next-to leading order QCD predictions for (2+1) jet cross sections and jet rates in deep inelastic scattering (DIS) based on a new parton level Monte Carlo program are presented. All relevant helicity contributions to the total cross section are included. Results on total jet cross sections as well as differential distributions in the basic kinematical variablesx, W ² andQ ² are shown for HERA energies and for the fixed target experiment E665 at FERMILAB. We study the dependence on the choices of the renormalization scale μ _R and the factorization scale μ _F and show that the NLO results are much less sensitive to the variation of μ=μ _F =μ _R than the LO results. The effect of an additionalp _T cut to our jet definition scheme is investigated.     

The inverse scattering transformation in the angular momentum plane

The inverse scattering transformation (IST) with the angular momentum () as a spectral variable turned out to be a useful method to deal with rotationally invariant problems in field theory at higher spatial dimensions [Refs. (1) and (2)]. We derive the direct and inverse scattering problems for thev-dimensional radial Schrödinger equation for variable and fixed energy (negative or positive). We determine the scattering data (SD) in one to one correspondence with the potential and derive the corresponding Gelfand-Levitan equation. A family of exactly solvable potentials for any and fixed energy is obtained. The trace identities associated to this IST are derived for both signs of the energy. They relate integrals of local polynomials in the potential and its derivatives timesr ^2n–1(n1) with the SD. The presence of this power ofr makes these relations useful in higher dimensions.Laboratoire associé au CNRS     

Fluctuations in12C+24Mg elastic and inelastic scattering

The data on the ϑ_c.m.=180° excitation functions of¹²C+²⁴Mg,¹²C* (4.43 MeV)+²⁴Mg and¹²C+²⁴Mg*(1.36 MeV) from 12.27 to 22.80 MeV, 16.53 to 27.47 MeV, and 11.33 to 26.40 MeV(c.m.) respectively have been subjected to statistical analysis. The effect of averaging interval, employed for data reduction, on the coherence widths as obtained from the autocorrelation function has been studied. The fluctuating features of the cross-sections turn out to be consistent with the statistical model expectations.