Search results for "PION"
showing 10 items of 1304 documents
Large-angle production of charged pions by 3 GeV/c-12 GeV/c protons on carbon, copper and tin targets
2008
A measurement of the double-differential pi(+/-) production cross-section in proton-carbon, proton-copper and proton-tin collisions in the range of pion momentum 100 MeV/c <= p <800 MeV/c and angle 0.35 rad <= theta < 2.15 rad is presented. The data were taken with the HARP detector in the T9 beam line of the CERN PS. The pions were produced by proton beams in a momentum range from 3 GeV/c to 12 GeV/c hitting a target with a thickness of 5% of a nuclear interaction length. The tracking and identification of the produced particles was done using a small-radius cylindrical time projection chamber (TPC) placed in a solenoidal magnet. An elaborate system of detectors in the beam line ensured th…
Measurement of the production cross-section of positive pions in the collision of 8.9 GeV/c protons on beryllium
2007
The double-differential production cross-section of positive pions, $d^2\sigma^{\pi^{+}}/dpd\Omega$, measured in the HARP experiment is presented. The incident particles are 8.9 GeV/c protons directed onto a beryllium target with a nominal thickness of 5% of a nuclear interaction length. The measured cross-section has a direct impact on the prediction of neutrino fluxes for the MiniBooNE and SciBooNE experiments at Fermilab. After cuts, 13 million protons on target produced about 96,000 reconstructed secondary tracks which were used in this analysis. Cross-section results are presented in the kinematic range 0.75 GeV/c < $p_{\pi}$ < 6.5 GeV/c and 30 mrad < $\theta_{\pi}$ < 210 mrad in the l…
Pion interaction with the trinucleon up to the eta production threshold
1993
Pion elastic, charge exchange scattering and induced eta production on the trinucleon systems are investigated in a coupled-channels approach in momentum space with Fadeev wave functions. The channel $\pi N \rightarrow \eta N$ is included using an isobar model with S-, P-, and D-wave resonances. While the coherent reactions like $^3$He($\pi,\pi)^3$He can be reasonably well reproduced up to $T_{\pi}$=500 MeV, large discrepancies appear for the incoherent processes, $^3$He($\pi^-,\pi^0)^3$H and $^3$He($\pi^-,\eta)^3$H at backward angles and energies above $\Delta$-resonance. In the forward direction the $(\pi,\eta)$ calculations underestimate the experimental measurements very close to thresh…
The nucleon axial mass and the MiniBooNE CCQE neutrino-nucleus data
2011
We analyze the MiniBooNE CCQE $d\sigma/dT_\mu d\cos\theta_\mu$ data using a theoretical model that has proved to be quite successful in the analysis of nuclear reactions with electron, photon and pion probes. We find that RPA and multinucleon knockout turn out to be essential for the description of the MiniBooNE data. We show these measurements are fully compatible with former determinations of nucleon axial mass $M_A$, in contrast with several previous analyses, which have suggested an anomalously large value. We find, $M_A=1.08 \pm 0.03$ GeV. We also argue that the procedure, commonly used to reconstruct the neutrino energy for QE events from the muon angle and energy, could be unreliable…
Status and prospects of Rn measurements at Mainz
2013
Parity-violating electron scattering is particularly sensitive to the neutron density. The recent PREX experiment at the Jefferson Laboratory (JLab) has demonstrated the feasibility of this method meanwhile outlining its major experimental challenges. On the other side intermediate energy photons are an ideal probe for studying the properties of strongly interacting matter from the nuclear scale down to the sub-nuclear components of the nucleus. Among others, coherent pion photoproduction on nuclei is an attractive approach to obtain information on the existence and nature of neutron skins in nuclei. The simultaneous combination of different techniques allows a systematic determination of t…
pp and ππ intensity interferometry in collisions of Ar+KCl at 1.76A GeV
2011
Results on pp, π+π+, and π-π- intensity interferometry are reported for collisions of Ar+KCl at 1.76$A$~GeV beam energy, studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18/GSI. The experimental correlation functions as a function of the relative momentum are compared to model calculations allowing the determination of the space-time extent of the corresponding emission sources. The π π source radii are found significantly larger than the pp emission radius. The present radii do well complement the source-size excitation functions of the collision system of size $A+A \simeq 40+40$. The pp source radius at fixed beam energy is found to increase linearly with the cube r…
Suppression of away-side jet fragments with respect to the reaction plane in Au + Au collisions atsNN=200GeV
2011
Pair correlations between large transverse momentum neutral pion triggers (p(T) = 4-7 GeV/c) and charged hadron partners (p(T) = 3-7 GeV/c) in central (0%-20%) and midcentral (20%-60%) Au + Au collisions at root s(NN) = 200 GeV are presented as a function of trigger orientation with respect to the reaction plane. The particles are at larger momentum than where jet shape modifications have been observed, and the correlations are sensitive to the energy loss of partons traveling through hot densematter. An out-of-plane trigger particle produces only 26 +/- 20% of the away-side pairs that are observed opposite of an in-plane trigger particle for midcentral (20%-60%) collisions. In contrast, ne…
The (γ, n) reaction on 16O between giant resonance and pion threshold
1982
Abstract A new TOF facility has been built for measurements of differential (γ, n) cross sections to discrete final states of light nuclei in the photon energy range between giant resonance and pion threshold. The observed neutron angle θn can continuously be varied between 0° and 150°, and additionally measurements at 175° and 180° are possible. Differential cross sections for the reaction 16O(γ, n0)15O are presented for Eγ = 60 MeV (40° ⩽ θn ⩽ 149°) and for θn = 90° (60 MeV ⩽ Eγ ⩽ 160 MeV). The results, combined with the corresponding (γ, p0) cross sections, indicate an absorption mechanism of high energy photons by neutron-proton pairs.
Inclusive charged-current neutrino-nucleus reactions
2011
We present a model for weak CC induced nuclear reactions at energies of interest for current and future neutrino oscillation experiments. This model is a natural extension of the work of Refs.[1,2], where the QE contribution to the inclusive electron and neutrino scattering on nuclei was analyzed. The model is based on a systematic many body expansion of the gauge boson absorption modes that includes one, two and even three body mechanisms, as well as the excitation of Delta isobars. The whole scheme has no free parameters, besides those previously adjusted to the weak pion production off the nucleon cross sections in the deuteron, since all nuclear effects were set up in previous studies o…
Can relativistic pionic stripping explain (p,π+) reactions?
1978
The relativistic pionic stripping formalism is used to study pion production data on $^{12}\mathrm{C}$ and $^{40}\mathrm{Ca}$ in order to determine the appropriate form of the pion-nucleon vertex and to determine whether pionic stripping is the dominant mechanism for pion production.