Measurements of spectra from the H2(π−,π0) reaction with a 500 MeV beam have been made from near zero degrees to 90 degrees. A peak corresponding to breakup or quasielastic scattering is observed, and its width, maximum, and differential cross section are reported. Peak shape determinations were also made with the H2(π+,π0) reaction. Results are compared to recent pion charge exchange data on deuterium at lower pion beam energies. A simple impulse approximation calculation accounts for the data at all angles.
No description provided.
We have measured the charge-changing cross sections of 10.6 GeV/nucleon Au197 nuclei interacting in targets of CH2 (polyethylene), C, Al, Cu, Sn, and Pb. Cross sections for H are calculated from those measured in C and CH2. The total charge-changing cross sections are higher than those measured at energies of ≤1 GeV/nucleon. The measured cross sections for the heavier targets are somewhat larger than those predicted by a model based on data taken at lower energies with lighter targets. Partial charge-changing cross sections for the production of fragments from the incident Au projectiles were measured for charge changes (ΔZ) from ΔZ=+1,80Hg, down to approximately ΔZ=-29,50Sn. In comparison to lower energy measurements, these partial cross sections are found to be smaller for small ΔZ and larger or the same for large ΔZ. The H partial cross sections are found to follow a power law in ΔZ similar to that for heavier targets, instead of the exponential form observed at lower energies. Factorization is found to hold for all partial cross sections with ΔZ greater than two. In the heavier targets, the cross sections for one and two proton removal have significant contributions from electromagnetic dissociation. The electromagnetic dissociation contribution to the total cross section is derived and found to be relatively small, but with a strong dependence on the charge of the target nuclei of the form ZT1.75±0.01.
TARGET NUCLEUS=CH2(POLYETHYLENE).
TARGET NUCLEUS=CH2(POLYETHYLENE).
We have conducted a search for bound states of a negative pion and a number of neutrons (pineuts) using the E814 spectrometer. A beam of Si28 at a momentum of 14.6A GeV/c was used to bombard targets of Al, Cu, Sn, and Pb. We describe our experimental technique, present measured upper limits for pineut production, and discuss the significance of our results.
AUTHORS NAMED CHARGED- BY PINEUT. Here ALL means the total number of interactions.
The vector analyzing power iT11 and the composite observable τ22=T22+T20/ √6 were measured at 10 incident pion energies between 100 and 294 MeV, in an angular range between 50° and 120°. Two different techniques were applied, the detection of the pion with a magnet spectrometer, and the πd coincidence method with scintillation counters. In the case of the first technique also two different target materials were used. Consistency among all data was obtained. The experimental data are compared to Faddeev calculations from one of us (H.G.). The discrepancies between theory and experiment are discussed, and an outlook for further research is given.
Vector analyzing power iT11 and composite observale TAU22 = T22 + T20/sqrt(6). LiDeut target.
Vector analyzing power iT11 and composite observale TAU22 = T22 + T20/sqrt(6). LiDeut target.
Vector analyzing power iT11 and composite observale TAU22 = T22 + T20/sqrt(6). LiDeut target.
An investigation of the production of neutron-rich isotopes from the fragmentation of Si28 projectiles at plab=14.6 GeV/c per nucleon was performed using the BNL-AGS-E814 spectrometer. We have measured the inclusive production cross sections of neutron-rich fragments (6He, He8, Li8, Li9, Be10, Be11, and B13). We have also measured the transverse momentum distributions for He6 and Li9, and the forward and transverse energy distributions associated with He6 production. The momentum distributions were analyzed in the context of the Goldhaber model. The question of whether the fragments are produced in the decay of the projectile following its electromagnetic excitation was also investigated.
No description provided.
We report on measurements of the differential π±p cross section at pion energies Tπ=32.7, 45.1, and 68.6 MeV. The measurements, covering the angular range 25°≤θlab≤123°, have been carried out at the Paul-Scherrer-Institute (PSI) in Villigen, Switzerland, employing the magnet spectrometer LEPS. The absolute normalization of the π±p cross sections have been achieved by relating them to the electromagnetic cross sections of μ±12C scattering. The results are in agreement with those of our preceding measurements at Tπ=32.2 and 45.1 MeV insofar as they overlap with the region of the Coulomb nuclear interference investigated there. A comparison with the predictions of the Karlsruhe-Helsinki phase shift analysis KH80, which has formed the basis for the determination of the ‘‘experimental’’ σ term, reveals considerable deviations. These are most pronounced for the π+p cross sections at Tπ=32.7 and 45.1 MeV. Single energy partial wave fits result in S-wave contributions, which are about 1° lower in magnitude then those specified by the KH80 solution. The data at 68.6 MeV are in good agreement with the phase shift analysis.
Statistical and systematic errors are addet in quadrature.
Statistical and systematic errors are addet in quadrature.
Statistical and systematic errors are addet in quadrature.
Simultaneous measurements of inclusive energy spectra and multiplicities of π±, K±, n, p, d, and t following antiproton annihilation on nuclei over a wide energy range and in the case of neutrons down to the evaporative part of the spectra are reported. Thirteen targets in the mass range of A=12–238 were used in a target mass dependent investigation of the fast stage of the antiproton-nucleus interaction. The deduced transferred, preequilibrium and equilibrium excitation energies agree very well with the dynamical picture drawn by the intranuclear cascade model (INC). Ratios of directly emitted neutrons to protons have been determined to be about twice the N/Z ratio in the target nucleus nearly independently of its mass. These unexpected values for this new sensitive observable are not completely understood in the standard framework of INC. Possible effects of isospin and nucleon densities as well as further schemes beyond the INC are discussed.
No description provided.
Systematic measurements of π− elastic scattering on C12 above the Δ-resonance region are reported. The differential cross sections were measured at 610, 710, 790, and 895 MeV/c over an angular range from 5° to 50°. The obtained data were compared with the first-order optical potential model. In the forward region, agreement with the calculation increases with the incident momentum. In the backward region, however, the calculation underestimates the data. The total cross section was extracted, and its energy dependence shows that the effect of Fermi averaging is important.
No description provided.
No description provided.
No description provided.
We have measured differential cross sections for the elastic scattering of charged pions from H3 and He3 into the backward hemisphere. Near the peak of the delta resonance, at Tπ=180 MeV, an angular distribution covering 114° to 168° in the laboratory extends our earlier measurements. At Tπ=142, 180, 220, and 256 MeV, we have measured an excitation function at angles approaching 170°. The cross sections for the reactions He3(π+,π+)3He, H3(π−,π−)3H show a rise at back angles which is not seen for He3(π−,π−)3He and H3(π+,π+)3H. There is a dip in the cross sections near 130° for Tπ=180 MeV.
No description provided.
No description provided.
No description provided.
Absolute π±p elastic scattering differential cross sections have been measured at five incident pion energies between 87 and 139 MeV. An active target of scintillator material (CH1.1) was used to detect recoil protons in coincidence with scattered pions. Pions were detected at forward angles between 27 and 98°c.m. where the low-energy recoil protons stop in the target. The cross sections, typically 5–10% lower than phase shift predictions for π+p and 10–20% lower for the π−p cross sections, are consistent with earlier measurements by this group.
No description provided.
No description provided.
No description provided.
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