Search results for "impulse"
showing 10 items of 159 documents
Electromagnetic Production of the Hypertriton
1996
Kaon photoproduction on He3, gamma + He3 --> K+ + Hypertriton, is studied in the framework of the impulse approximation. Realistic He3 wave functions obtained as solutions of Faddeev equations with the Reid soft-core potential are used along with different Hypertriton wave functions. Results are compared for several elementary operator models, which can successfully describe the elementary kaon production off the proton up to a photon lab energy of k = 2.2 GeV. It is found that the corresponding cross sections are small, of the order of several nanobarns. It is also shown that the influence of Fermi motion is important, while the effect of different off-shell assumptions on the cross sec…
Coherent pion electroproduction on the deuteron in the Δ(1232) resonance region
1999
Coherent pion electroproduction on the deuteron is studied in the Δ(1232) resonance region in the impulse approximation, i.e., neglecting pion rescattering and two-body effects. The elementary reaction on the nucleon is described in the framework of an effective Lagrangian approach including the dominant P33(1232) resonance and the usual background terms of the Born contributions for π0 production. We have studied the influence of these different contributions on the various structure functions which determine the unpolarized exclusive differential cross section in a variety of kinematic regions.
Photoproduction of pions on 3He and 3H
1969
Abstract In this paper the photoproduction of pions on nuclei with three nucleons is considered in the “elastic” channels. The calculation is done using the impulse approximation and neglecting rescattering effects.
Comparison of recoil polarization in the C12(e→,e′p→) process for protons extracted from s and p shells
2020
Abstract We present the first measurements of the double ratio of the polarization-transfer components ( P x ′ / P z ′ ) p / ( P x ′ / P z ′ ) s for knock-out protons from the s and p shells in C 12 measured by the C 12 ( e → , e ′ p → ) reaction in quasi-elastic kinematics. The data are compared to theoretical predictions in the relativistic distorted-wave impulse approximation. Our results show that the differences between s- and p-shell protons, observed when compared at the same initial momentum (missing momentum), largely disappear when the comparison is done at the same proton virtuality. We observe no difference in medium modifications between protons from the s and p shells with the…
Two-body Mechanisms in Pion Scattering and Pion Photoproduction on the Trinucleon
1995
A breakdown of the Impulse Approximation is studied in pion photoproduction and pion charge exchange on 3He at high momentum transfers. The usual DWIA formalism with Faddeev wave functions which works well for small momentum transfers deviates from experimental measurements by up to two orders of magnitude for Q 2 > 6 fm−2. It is found that the explicit inclusion of two-body mechanisms, where the photon or pion is absorbed on one nucleon and the pion is emitted from another nucleon removes most of the disagreement with the data.
Measurement of the ExclusiveH3e(e,e′p)Reaction Below the Quasielastic Peak
2004
New, high-precision measurements of the 3He(e,ep) reaction using the A1 Collaboration spectrometers at the Mainz microtron MAMI are presented. These were performed in antiparallel kinematics at energy transfers below the quasielastic peak, and at a central momentum transfer of 685 MeV/c. Cross sections and distorted momentum distributions were extracted and compared to theoretical predictions and existing data. The longitudinal and transverse behavior of the cross section was also studied. Sizable differences in the cross-section behavior from theoretical predictions based on the plane wave impulse approximation were observed in both the two- and three-body breakup channels. Full Faddeev-ty…
Annular binary filters for controlling the axial behaviour of optical systems
1998
The one-dimensional (1D) version of the iterative Fourier transform algorithm (IFTA) and a modified error diffusion algorithm are proposed for binarizing rotationally symmetric pupil filters designed to shape the axial impulse response of optical system. The resulting binary masks consist of a set of transparent and opaque annular zones of equal area or equal width. A numerical experiment in which we examine the performance of the binarization methods is carried out. In this experiment the resemblance between the axial diffractive behaviour of the binary version of an axially superresolving pupil filter, and that of the original continuous-tone filter is evaluated. It is shown that the perf…
Measurement ofN14(γ, π+)C14(g.s.)at 200 MeV: A Test of the Distorted-Wave Impulse Approximation for Charged-Pion Photoproduction below theΔ(1232)Reso…
1985
Differential cross sections for $^{14}\mathrm{N}(\ensuremath{\gamma}, {\ensuremath{\pi}}^{+})^{14}\mathrm{C}(\mathrm{g}.\mathrm{s}.)$ (${0}^{+}$1) have been measured for an incident photon energy ${E}_{\ensuremath{\gamma}}=200$ MeV at laboratory angles of 45\ifmmode^\circ\else\textdegree\fi{}, 60\ifmmode^\circ\else\textdegree\fi{}, 75\ifmmode^\circ\else\textdegree\fi{}, 90\ifmmode^\circ\else\textdegree\fi{}, 120\ifmmode^\circ\else\textdegree\fi{}, and 140\ifmmode^\circ\else\textdegree\fi{}. Momentum-space distorted-wave-impulse-approximation calculations, using a complete treatment of a one-body pion-photoproduction operator, are found to be in excellent agreement with the experimental data…
Eta photoproduction from nuclei
2008
Low-energy eta photoproduction from complex nuclei is investigated in a distorted wave impulse approximation (DWIA) framework carried out in momentum spaces. The elementary operator is fixed by the hadronic reactions πN→πN, πN→ππN and π−p→ηn as well as the process γN→πN to constrain the electromagnetic vertex. The resonances S11(1535), P11(1440) and D13(I520) are used to generate s-, p- and d-wave interactions. This coupled channels approach fulfils unitarity and allows the prediction of γp→ηp cross sections. The η final state interaction has been included via a simple optical potential using the ηN t-matrix as an input. We find that coherent eta production is dominated by the D13(1520) iso…
Lärm als Umweltproblem
1976
Noise as an Environmental Problem. Anatomical structure and physiological function of the human ear are described. It is shown that constant noise stress leads to damage of certain parts of the inner ear. These damages proceed characteristically and may be diagnosed relatively early by means of audiometric tests. VDI-instructions 2058 (sheet 2) prescribes screening-tests for an earliest possible detection of incipient noise damage. In addition to ear-damaging effects of noise there have also been recorded physiological reactions under noise influence. Such disturbances, however, cannot as yet be described as an “Extraaural disease”. On the other hand, the fact that high sound intensities of…