The energy dependence of the differential cross section for $\pi^+ p$ elastic scattering at a c.m. angle near 174 ° has been measured. The momentum range of incident $\pi^+$ was 2.06-4.70 GeV/c. On this energy dependence one can see a structure, i.e. maxima corresponding to the baryon resonances $\Delta(2420)$ and $\Delta(2840)$. The structure is used for determination of the parities of these resonances.
No description provided.
No description provided.
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We have measured the cross section at 180° for K + p and K + n elastic scattering in the momentum range 1.0 to 1.5 GeV/ c . The K + n cross section was measured on deuterium and the K + p on hydrogen and deuterium. We were thus able to measure directly the difference between free nucleon (proton) scattering and bound nucleon (proton) scattering at large angles. This difference was found to be small and within our experimental accuracy the K + p(n) cross section should be equal to the K + p (free) cross section at 180°. We found no evidence for an s -channel resonance Z ∗ in either the K + p or K + n system. A comparison of our data and those of other groups with theoretical predictions is given.
DEUTERIUM TARGET. U IS ABOUT 0.1 GEV**2.
HYDROGEN AND DEUTERIUM TARGET DATA ARE IN GOOD AGREEMENT. THESE CROSS SECTIONS ARE A WEIGHTED AVERAGE.
The differential cross sections and vector analyzing powers for nd elastic scattering at En=248 MeV were measured for 10°–180° in the center-of-mass (c.m.) system. To cover the wide angular range, the experiments were performed separately by using two different setups for forward and backward angles. The data are compared with theoretical results based on Faddeev calculations with realistic nucleon-nucleon (NN) forces such as AV18, CD Bonn, and Nijmegen I and II, and their combinations with the three-nucleon forces (3NFs), such as Tucson-Melbourne 99 (TM99), Urbana IX, and the coupled-channel potential with Δ-isobar excitation. Large discrepancies are found between the experimental cross sections and theory with only 2N forces for θc.m.>90°. The inclusion of 3NFs brings the theoretical cross sections closer to the data but only partially explains this discrepancy. For the analyzing power, no significant improvement is found when 3NFs are included. Relativistic corrections are shown to be small for both the cross sections and the analyzing powers at this energy. For the cross sections, these effects are mostly seen in the very backward angles. Compared with the pd cross section data, quite significant differences are observed at all scattering angles that cannot be explained only by the Coulomb interaction, which is usually significant at small angles.
Cross section for N DEUT elastic scattering for data taken in 2003 in the backward direction in the centre-of-mass. Statistical errors only are given.
Cross section for N DEUT elastic scattering for data taken in 2000 in the backward direction in the centre-of-mass. Statistical errors only are given.
Cross section for N DEUT elastic scattering in the forward direction in the centre-of-mass. Statistical errors only are given.
A tagged medium-energy neutron beam has been used in a precise measurement of the absolute differential cross section for np back-scattering. The results resolve significant discrepancies within the np database concerning the angular dependence in this regime. The experiment has determined the absolute normalization with 1.5% uncertainty, suitable to verify constraints of supposedly comparable precision that arise from the rest of the database in partial wave analyses. The analysis procedures, especially those associated with evaluation of systematic errors in the experiment, are described in detail so that systematic uncertainties may be included in a reasonable way in subsequent partial wave analysis fits incorporating the present results.
Final differential cross sections averaged over data samples.
The angular distributions of the cross section, the proton analyzing power, and all proton polarization transfer coefficients of p→d elastic scattering were measured at 250 MeV. The range of center-of-mass angles was 10°–165° for the cross section and the analyzing power, and about 10°–95° for the polarization transfer coefficients. These are the first measurements of a complete set of proton polarization observables for p→d elastic scattering at intermediate energies. The present data are compared with theoretical predictions based on exact solutions of the three-nucleon Faddeev equations and modern realistic nucleon-nucleon potentials combined with three-nucleon forces (3NF), namely, the Tucson-Melbourne (TM) 2π-exchange model, a modification thereof (TM′) closer to chiral symmetry, and the Urbana IX model. Large effects of the three-nucleon forces are predicted. The inclusion of the three-nucleon forces gives a good description of the cross section at angles below the minimum. However, appreciable discrepancies between the data and predictions remain at backward angles. For the spin observables the predictions of the TM 3NF model deviate strongly from the other two 3NF models, which are close together, except for Kyy′. In the case of the analyzing power all 3NF models fail to describe the data at the upper half of the angular range. In the restricted measured angular range the polarization transfer coefficients are fairly well described by the TM′ and Urbana IX 3NF models, whereas the TM 3NF model mostly fails. The transfer coefficient Kyy′ is best described by the Urbana IX but the theoretical description is still insufficient to reproduce the experimental data. These results call for a better understanding of the spin structure of the three-nucleon force and very likely for a full relativistic treatment of the three-nucleon continuum.
Cross section and analyzing power measurements.
Proton polarization transfer coefficients.
Differential cross sections for Compton scattering from the deuteron were measured at MAX-lab for incident photon energies of 55 MeV and 66 MeV at nominal laboratory angles of $45^\circ$, $125^\circ$, and $135^\circ$. Tagged photons were scattered from liquid deuterium and detected in three NaI spectrometers. By comparing the data with theoretical calculations in the framework of a one-boson-exchange potential model, the sum and difference of the isospin-averaged nucleon polarizabilities, $\alpha_N + \beta_N = 17.4 \pm 3.7$ and $\alpha_N - \beta_N = 6.4 \pm 2.4$ (in units of $10^{-4}$ fm$^3$), have been determined. By combining the latter with the global-averaged value for $\alpha_p - \beta_p$ and using the predictions of the Baldin sum rule for the sum of the nucleon polarizabilities, we have obtained values for the neutron electric and magnetic polarizabilities of $\alpha_n= 8.8 \pm 2.4$(total) $\pm 3.0$(model) and $\beta_n = 6.5 \mp 2.4$(total) $\mp 3.0$(model), respectively.
Centre of mass differential cross sections for deuteron compton scattering at incident photon energy 54.6 MeV.
Centre of mass differential cross sections for deuteron compton scattering at incident photon energy 54.9 MeV.
Centre of mass differential cross sections for deuteron compton scattering at incident photon energy 55.9 MeV.
Precise measurements of deuteron vector and tensor analyzing powers Ayd, Axx, Ayy, and Axz in d−p elastic scattering were performed via 1H(d→,d)p and 1H(d→,p)d reactions at three incoming deuteron energies of Edlab=140, 200, and 270 MeV. A wide range of center-of-mass angles from ≈10° to 180° was covered. The cross section was measured at 140 and 270 MeV at the same angles. These high precision data were compared with theoretical predictions based on exact solutions of three-nucleon Faddeev equations and modern nucleon-nucleon potentials combined with three-nucleon forces. Three-body interactions representing a wide range of present day models have been used: the Tucson-Melbourne 2π-exchange model, a modification thereof closer to chiral symmetry, the Urbana IX model, and a phenomenological spin-orbit ansatz. Large three-nucleon force effects are predicted, especially at the two higher energies. However, only some of them, predominantly dσ/dΩ and Ayd, are supported by the present data. For tensor analyzing powers the predicted effects are in drastic conflict to the data, indicating defects of the present day three-nucleon force models.
Angular distribution for DEUT P elastic scattering at EKIN of 140 MeV with the SMART spectrograph.
Angular distribution for DEUT P elastic scattering at EKIN of 270 MeV with the D-room polarimeter.
Angular distribution for DEUT P elastic scattering at EKIN of 270 MeV with the SMART spectrograph.
The reported data are given for the mean angles measured rather than for the central angles. The data are normalized to the most recent Evaluated Nuclear Data File evaluated angle-integrated elastic-scattering cross section and refitted with a Legendre polynomial expansion.
Measured values of the N-P elastic scattering angular distributions. Data are normalized to the Breit-Hopkins total elastic cross section after radiative capture correction.
A precision measurement of absolute pi+p and pi-p elastic differential cross sections at incident pion laboratory kinetic energies from T_pi= 141.15 to 267.3 MeV is described. Data were obtained detecting the scattered pion and recoil proton in coincidence at 12 laboratory pion angles from 55 to 155 degrees for pi+p, and six angles from 60 to 155 degrees for pi-p. Single arm measurements were also obtained for pi+p energies up to 218.1 MeV, with the scattered pi+ detected at six angles from 20 to 70 degrees. A flat-walled, super-cooled liquid hydrogen target as well as solid CH2 targets were used. The data are characterized by small uncertainties, ~1-2% statistical and ~1-1.5% normalization. The reliability of the cross section results was ensured by carrying out the measurements under a variety of experimental conditions to identify and quantify the sources of instrumental uncertainty. Our lowest and highest energy data are consistent with overlapping results from TRIUMF and LAMPF. In general, the Virginia Polytechnic Institute SM95 partial wave analysis solution describes our data well, but the older Karlsruhe-Helsinki PWA solution KH80 does not.
Centre of mass absolute differential cross sections at pion kinetic energy 141.15 MeV using the liquid H2 target and single arm pion detection. There is an additional systematic error of 1.1 PCT for PI+ beams which is not included in the errors shown in the table.
Centre of mass absolute differential cross sections at pion kinetic energy 141.15 MeV using the liquid H2 target and two arm pion detection. There is an additional systematic error of 1.3 PCT for PI+ beams which is not included in the errors shown in the table.
Centre of mass absolute differential cross sections at pion kinetic energy 141.15 MeV using the liquid H2 target and two arm pion detection. There is an additional systematic error of 1.3 PCT (1.6 PCT) for PI+ (PI-) beams which is not included in the errors shown in the table.
Σ + p elastic scattering has been studied using a scintillating fiber block (SCIFI) which served as a target for the production of Σ + hyperons as well as for subsequent Σ + scattering on hydrogen. A new technique for the analysis of the hyperon-nucleon scattering in the SCIFI has been developed and established. In this paper, Σ + p elastic scattering events have been identified in the Σ + momentum range of 300–600 MeV/ c , and differential cross sections have been obtained at two angles. The results are compared with various theoretical baryon-baryon interaction models.
No description provided.
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