Inclusive Double Differential Cross Sections Research Articles

14N break-up α emission with 59Co, 93Nb, and 197Au targets at an incident energy of 250 MeV

AbstractThe emission of α particles has been analyzed using a 14N projectile beam on 59Co, 93Nb, and 197Au targets at an incident energy of 250 MeV, in the angular range from 8° to 40°. The estimated α particles from the break-up channel and the pre-equilibrium mode were compared with the experimentally measured inclusive double differential cross sections at various angles at 250 MeV beam energy. The present results indicate that at such a high incident energy, a significant contribution to the α-particle emission comes from direct reactions, which are dominant at forward angles. At larger emission angles, non-equilibrium and evaporation processes increase and compete with direct reactions.

Non-equilibrium emission of alpha particles in the interaction of 14N with 59Co and 93Nb at incident energy of 250 MeV

In this work, the results of measured inclusive double differential cross sections of α particles emitted in the interaction of 14N with 59Co and 93Nb at incident energy of 250 MeV are presented. The experimental data were collected in a wide angular range from 8 to 100 degrees in the laboratory system. The analysis of these data suggests that the measured alpha spectra contains contributions of alpha particles originating from various reaction mechanisms, all of which are important at this high energy. We have also compared our experimental results with the calculations by using a recently developed theoretical model code. This recently developed pre-equilibrium model code is hereby put to a stringent test as to how it performs in case of heavy ion reactions at such high energies.

Seagull and pion-in-flight currents in neutrino-induced 1N and 2N knockout

[Background] The neutrino-nucleus ($\nu A$) cross section is a major source of systematic uncertainty in neutrino-oscillation studies. A precise $\nu A$ scattering model, in which multinucleon effects are incorporated, is pivotal for an accurate interpretation of the data. [Purpose] In $\nu A$ interactions, meson-exchange currents (MECs) can induce two-nucleon ($2N$) knockout from the target nucleus, resulting in a two-particle two-hole (2p2h) final state. They also affect single nucleon ($1N$) knockout reactions, yielding a one-particle one-hole (1p1h) final state. Both channels affect the inclusive strength. We present a study of axial and vector, seagull and pion-in-flight currents in muon-neutrino induced $1N$ and $2N$ knockout reactions on $^{12}$C. [Method] Bound and emitted nucleons are described as Hartree-Fock wave functions. For the vector MECs, the standard expressions are used. For the axial current, three parameterizations are considered. The framework developed here allows for a treatment of MECs and short-range correlations (SRCs). [Results] Results are compared with electron-scattering data and with literature. The strengths of the seagull, pion-in-flight and axial currents are studied separately and double differential cross sections including MECs are compared with results including SRCs. A comparison with MiniBooNE and T2K data is presented. [Conclusions] In the 1p1h channel, the effects of the MECs tend to cancel each other, resulting in a small effect on the double differential cross section. $2N$ knockout processes provide a small contribution to the inclusive double differential cross section, ranging from the $2N$ knockout threshold into the dip region. A fair agreement with the MiniBooNE and T2K data is reached.

Neutrino-induced reactions on nuclei

Background: Long-baseline experiments such as the planned Deep Underground Neutrino Experiment (DUNE) require theoretical descriptions of the complete event in a neutrino-nucleus reaction. Since nuclear targets are used this requires a good understanding of neutrino-nucleus interactions. Purpose: Develop a consistent theory and code framework for the description of lepton-nucleus interactions that can be used to describe not only inclusive cross sections, but also the complete final state of the reaction. Methods: The Giessen-Boltzmann-Uehling-Uhlenbeck (GiBUU) implementation of quantum-kinetic transport theory is used, with improvements in its treatment of the nuclear ground state and of 2p2h interactions. For the latter an empirical structure function from electron scattering data is used as a basis. Results: Results for electron-induced inclusive cross sections are given as a necessary check for the overall quality of this approach. The calculated neutrino-induced inclusive double-differential cross sections show good agreement with data from neutrino- and antineutrino reactions for different neutrino flavors at MiniBooNE and T2K. Inclusive double-differential cross sections for MicroBooNE, NOvA, MINERvA and LBNF/DUNE are given. Conclusions: Based on the GiBUU model of lepton-nucleus descriptions a good theoretical description of inclusive electron-, neutrino- and antineutrino-nucleus data over a wide range of energies, different neutrino flavors and different experiments is now possible. Since no tuning is involved this theory and code should be reliable also for new energy regimes and target masses. \end{description}

Inclusive and pion production neutrino-nucleus cross sections

We analyze the experimental data on the inclusive double differential cross section by neutrinos charged current, measured by T2K, with the same model which was successful for the MiniBooNE quasielastic cross sections. As in our previous analysis the multinucleon component is needed in order to reproduce the data. For the total cross section our evaluation is smaller than the SciBooNE data above 1 GeV. This indicates the opening of a new channel not included in our evaluation, presumably the two pion emission channel. We also check that our description holds for the exclusive single pion production channel by confronting our evaluation with the MiniBooNE double differential cross section for a single charged pion and the Q^2 distribution. Both are compatible with data.

Many-body interactions of neutrinos with nuclei: Observables

Background: The total inclusive cross sections obtained for quasielastic (QE) scattering in the Mini Booster Neutrino Experiment (MiniBooNE) are significantly larger than those calculated by all models based on the impulse approximation and using the world average value for the axial mass of ${M}_{A}\ensuremath{\approx}1\phantom{\rule{0.28em}{0ex}}\mathrm{GeV}$. This discrepancy has led to various, quite different explanations in terms of increased axial masses, changes in the functional form of the axial form factor, increased vector strength in nuclei, and initial two-particle interactions. This is disconcerting since the neutrino energy reconstruction depends on the reaction mechanism.Purpose: We investigate whether exclusive observables, such as nucleon knockout, can be used to distinguish between the various proposed reaction mechanisms. We determine the influence of 2p-2h excitations on the neutrino energy reconstruction.Method: We extend the Giessen Boltzmann--Uehling--Uhlenbeck (GiBUU) model by explicitly incorporating initial 2p-2h excitations.Results: We calculate inclusive cross sections and numbers and spectra of knockout nucleons and show their sensitivity to the presence of 2p-2h initial excitations. We also discuss the influence of 2p-2h excitations on the neutrino energy reconstruction.Conclusions: Inclusive double-differential cross sections, depending only on muon variables, are fairly insensitive to the reaction mechanism. 2p-2h excitations lead to an increase in the number $n$ of knockout nucleons for $n\ensuremath{\geqslant}2$, while only the $n=1$ knockout remains a clean signal of true QE scattering. The spectra of knockout nucleons are also changed, but their shape is hardly affected. In the energy reconstruction, 2p-2h interactions as well as $\ensuremath{\Delta}$ excitations lead to a downward shift of the reconstructed energy; this effect of 2p-2h excitations disappears at higher energies because the 2p-2h influence is spread out over a wider energy range.

Production of 3He and 6He fragments in the interaction of 12C with 93Nb at 400 MeV

Spectra of inclusive double differential cross sections of 3He and 6He fragments produced in the interaction of 12C with 93Nb at 400 MeV are measured and analyzed. As was found for the production of intermediate mass fragments in this and similar reactions involving light projectiles, the spectra can to a large extent be satisfactorily reproduced only by considering the contribution of projectile break-up as well as nucleon coalescence.

Alpha particle emission in the interaction of 12C with 59Co and 93Nb at incident energies of 300 and 400 MeV

The results of measured inclusive double differential cross section of α particles emitted in the interaction of 12C ions with 59Co and 93Nb at incident energies of 300 and 400 MeV are presented. The analysis of these data allows us to isolate the contributions of the different reaction mechanisms, thereby confirming previous conclusions of a comprehensive analysis of a large number of excitation function, forward recoil ranges and angular distributions of residues produced in the interaction of 12C with a target nucleus in the same mass range. In particular, the probabilities associated with α-particle reemission following incomplete fussion processes have been reaffirmed. Several refinements to the theoretical model proposed in earlier studies of the interaction of 12C with nuclei are presented.

A semiclassical model for inclusive nucleon inelastic scattering to continuum

We present a semiclassical DWBA theory of one-step inelastic nucleon scattering leading to continuous final nuclear states. A closed form formula for inclusive double differential cross section with no adjustable parameter is given. Calculated cross sections of (p, p′X) at 62 and 164 MeV are compared with experimental data, and with the exciton model and the multi-step direct reaction model.

Inclusive neutron production by 337 MeV/nucleon neon ions on carbon, aluminum, copper, and uranium

We measured inclusive double-differential cross sections at angles of 30, 45, 60, and 90 degrees for the production of neutrons above about 12 MeV from 337 MeV/nucleon neon ions bombarding targets of C, Al, Cu, and U. Three different energy regions can be distinguished in the neutron spectra: (1) a low-energy ''evaporation'' region. (2) a high-energy exponential tail reflecting the internal momentum distribution of the nucleons, and (3) an intermediate energy region reflecting quasifree and preequilibrium processes. The intermediate-energy region becomes less pronounced with increasing angle and is almost nonexistent at 90 degrees. This behavior is consistent with the interpretation that the intermediate-energy region consists mainly of scattering processes with a few direct collisions. The intermediate-energy region is relatively flat at the forward angles and merges into an exponential fall-off at wide angles. The 30-degree spectrum from the carbon target shows a broad peak around 150 MeV, which we interpret as a signature of quasi-free nucleon-nucleon collisions. Although the neutron detection threshold does not permit us to see the evaporation peaks, we do see evidence of the evaporation tails. The evaporation yields apparent in our spectra increase with the mass number of the target. The neutron spectra differ from protonmore » spectra reported for similar targets at 385 MeV/nucleon and 393 MeV/nucleon. The neutron-to-proton cross section ratios are fit well by an intranuclear-cascade model calculation, but poorly by a ''firestreak'' model calculation.« less

Measurement of the Inclusive Neutron Production by Relativistic Neon Ions on Uranium

Inclusive double-differential cross sections for neutron production were measured at 337 MeV/nucleon in the reaction $\mathrm{Ne}+\mathrm{U}\ensuremath{\rightarrow}n+X$. Neutrons were detected with energies between \ensuremath{\sim} 12 and \ensuremath{\sim} 600 MeV at laboratory angles of 30\ifmmode^\circ\else\textdegree\fi{}, 45\ifmmode^\circ\else\textdegree\fi{}, 60\ifmmode^\circ\else\textdegree\fi{}, and 90\ifmmode^\circ\else\textdegree\fi{}. The neutron spectra above \ensuremath{\sim} 30 MeV are comparable with the predictions of a firestreak calculation. The neutron spectra differ from proton spectra reported for U and Pb.