Mesons In Hydrogen Research Articles

Differential Cross Sections for the Scattering of 58-Mevπ+Mesons in Hydrogen

Differential Cross Sections for the Scattering of 58-Mev<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>Mesons in Hydrogen

Photoproduction of Neutral Mesons in Hydrogen at High Energies

Photoproduction of Neutral Mesons in Hydrogen at High Energies

Photoproduction of Neutral Mesons in Hydrogen

Photoproduction of Neutral Mesons in Hydrogen

Production ofπ∘Mesons in Hydrogen and Deuterium by High Energyγ-Rays

The angular distribution of the ${\ensuremath{\pi}}^{\ensuremath{\circ}}$'s and the dependence of the cross sections on the energy of the $\ensuremath{\gamma}$-rays have been studied for the reactions ${\ensuremath{\gamma}+P,\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{\circ}}+P,}{\ensuremath{\gamma}+P,\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{\circ}}+D(P,N).}$ For the first reaction, the angular distribution in the center-of-mass system has the form $a+b{sin}^{2}\overline{\ensuremath{\theta}}$, with $\frac{a}{b}\ensuremath{\simeq}1$, and the cross section is proportional to approximately the square of the excess energy of the $\ensuremath{\gamma}$-rays above the threshold; $\frac{{\ensuremath{\sigma}}_{\mathrm{D}}}{{\ensuremath{\sigma}}_{\mathrm{H}}}\ensuremath{\simeq}2$ at all energies and angles.

The Production of Positive Mesons by Photons

Experimental results are presented on the production of positive mesons in hydrogen and carbon, as a function of meson angle and energy. The principal results are as follows: The angular distribution in the case of hydrogen is rather flat in the region 45\ifmmode^\circ\else\textdegree\fi{}-135\ifmmode^\circ\else\textdegree\fi{} in the laboratory system, slightly peaked near 90\ifmmode^\circ\else\textdegree\fi{}. This demonstrates that the pion is not a scalar. The excitation function at 90\ifmmode^\circ\else\textdegree\fi{} rises approximately linearly to a plateau which starts at photon energies of about 260 Mev. This rise is slower than expected on the basis of a phase space argument. The total cross section for 255-Mev photons in hydrogen is 1.9\ifmmode\pm\else\textpm\fi{}0.3\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}28}$ ${\mathrm{cm}}^{2}$. The cross sections in carbon are lower, per proton, by a factor of approximately three. With respect to hydrogen, the meson energy distribution is shifted to lower energies and the angular distribution is shifted to the backward angles.

Meson-Nucleon Scattering and Nucleon Isobars

The scattering (including charge exchange) of ${\ensuremath{\pi}}^{\ensuremath{-}}$ mesons in hydrogen rises from 18 millibarns at 60 Mev to a broad plateau of about 60 millibarns at 200 Mev, and is smaller than the ${\ensuremath{\pi}}^{+}$ scattering at 60 Mev in the ratio of 0.63\ifmmode\pm\else\textpm\fi{}0.09. The general features of the ${\ensuremath{\pi}}^{\ensuremath{-}}$ scattering, except for the high energy plateau, are given qualitatively by pseudoscalar theory with pseudovector coupling in the weak coupling limit; the ratio of ${\ensuremath{\pi}}^{\ensuremath{-}}$ to ${\ensuremath{\pi}}^{+}$ scattering predicted by this theory in the weak coupling limit is, however, 1.67, which is much higher than the experimental result. A phenomenological theory of the scattering is developed by using the methods of Wigner and Eisenbud and imposing the restrictions of charge symmetry. By using the qualitative assignment of the resonance levels parameters as given by weak and strong coupling theory, satisfactory agreement with experiment is obtained. It is concluded that the apparently anomalous features of the scattering can be interpreted to be an indication of a resonant meson-nucleon interaction corresponding to a nucleon isobar with spin $\frac{3}{2}$, isotopic spin $\frac{3}{2}$, and with an excitation of 277 Mev.

Total Cross Sections of 60-Mev Mesons in Hydrogen and Deuterium

The total cross sections of positive and negative mesons of average energy 58 Mev have been measured in hydrogen and deuterium. The results are ${\ensuremath{\sigma}({\ensuremath{\pi}}^{+}+p),=27.8\ifmmode\pm\else\textpm\fi{}2.5 \mathrm{mb}}{\ensuremath{\sigma}({\ensuremath{\pi}}^{\ensuremath{-}}+p),=17.6\ifmmode\pm\else\textpm\fi{}2.2 \mathrm{mb}}{\ensuremath{\sigma}({\ensuremath{\pi}}^{+}+d),=38.3\ifmmode\pm\else\textpm\fi{}3.1 \mathrm{mb}}{\ensuremath{\sigma}({\ensuremath{\pi}}^{\ensuremath{-}}+d),=32.8\ifmmode\pm\else\textpm\fi{}3.1 \mathrm{mb}.}$ The deuteron cross sections are related to the elementary scattering amplitudes in the impulse approximation, and the observed interference is compared to that predicted in weak coupling meson theory.

Neutral Mesons Produced in the Capture ofπ−Mesons in Hydrogen

Neutral Mesons Produced in the Capture of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>Mesons in Hydrogen

Further Remarks on the Absorption ofπ−-Mesons in Hydrogen

Further Remarks on the Absorption of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>-Mesons in Hydrogen

The Gamma-Ray Spectrum from the Absorption ofπ−- Mesons in Hydrogen

The Gamma-Ray Spectrum from the Absorption of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>- Mesons in Hydrogen

The Average Specific Ionization of Cosmic-Ray Mesons in Hydrogen, Helium, and Argon

Counter-controlled, cloud-chamber photographs have been taken of cosmic-ray meson tracks in hydrogen, helium, and argon gases. The chamber was operated in such a way that the average probable ionization could be determined from the counted number of drops that condensed on positive ions. Clusters of droplets that required energy transfers up to 25 \ifmmode\times\else\texttimes\fi{} (average energy spent per ion pair) were included. The observed results were corrected for the ionization in the alcohol and water vapors used in the chamber. The ionization correction amounted to less than 25 percent for hydrogen and helium gases and less than one percent for argon gas. The average probable ionization per cm at N. T. P. in hydrogen gas was 8.00, in helium gas 9.67, and in argon gas 65.5. The probable error was about seven percent. The results were used to check with theory. There was very good agreement between theory and experiment for hydrogen, argon, and air, but in the case of helium the discrepancy exceeded the estimated experimental error.