Nuclear Pion Research Articles

Properties of Inclusive (π+, π0) Reactions in Nuclei

Nuclear pion single charge exchange has been studied using a method of ${\ensuremath{\pi}}^{0}$ detection based on the spectroscopy of the band-angle decay $\ensuremath{\gamma}$ ray. For incident 100-MeV positive pions, charge-exchange scattering from nuclei ranging from Be to Pb was studied. For all targets the ${\ensuremath{\pi}}^{0}$ spectra were broad, extending over the entire range 0-100 MeV. Data were taken at 40\ifmmode^\circ\else\textdegree\fi{} and 120\ifmmode^\circ\else\textdegree\fi{} and in all cases the data show a backward peaking. The yields vary about as ${A}^{\frac{2}{3}}$.

Calculation of π − photoproduction in 12C leading to the 12N ground state

We calculate charged pion nuclear photoproduction with the complete transition operator, Coulomb and nuclear pion distortion, and initial nuclear motion in impulse approximation. Theoretical results for 12C(γ, π −) 12N gd using a Helm model description, are compared with two recent experiments.

Nuclear pion production as a direct reaction

Nuclear pion production as a direct reaction

Final state interactions in nuclear pion photoproduction over the (3, 3) resonance

An impulse approximation calculation is made on the reaction 51V( γ, π +) 51Ti from the region just above photopion threshold to the tail of the (3, 3) resonance. Pion final state distortions are taken into account through realistic optical potentials. Results are compared to those for plane-wave and surface-produced pions and to recent experiment. Comparison is made between surface-produced pions and pions distorted by the s-wave component of the optical potential.

The role of two-step contributions in nuclear coherent and incoherent pion production

Abstract The recent CERN measurements of 3π and 5π production on nuclear targets are analysed in terms of one- and two-step production. We argue that the value of the 5π nucleon total cross section is an effect which can be ascribed to interference between one- and two-step terms. For the A 3 case the evidence for two-step contributions is at present rather weak.

Elementary particle approach to some nuclear pion reactions

Elementary particle approach to some nuclear pion reactions

Elementary-particle approach to some nuclear pion reactions

An elementary-particle approach is applied to the nuclear pionic pion capture and charge-exchange pion-nucleus scattering under the soft-pion hypothesis. A relation between the muon capture, radiative pion capture and pionic pion capture is discussed.

Inelastic photopion production with excitation of giant resonance analogs: application to 16O

Using a generalized Goldhaber-Teller model of the giant multipole resonances in 16O, we have evaluated the differential cross section for the photoproduction of positive pions near threshold leading to giant resonance spin-flip state of various multipolarities in 16N, and have obtained the corresponding pion spectra assuming monochromatic incident photons. A possible subsequent neutron emission was also considered We find that at forward angles of the emitted pion the spectra are dominated by the dipole resonances, but that at larger angles the quadrupole resonances appear strongly, making it possible to experimentally identify the two types of resonances Owing to the variability of its momentum transfer, inelastic nuclear pion photo- production is potentially as powerful for a study of analog excitation, as inelastic electron scattering has become for ΔT 3 = 0 nuclear excitations

Radiological Physics of Pions

Pions, and in particular negative pions, are of interest to radiology for at least three outstanding reasons: First, a beam of negative pions can produce in tissue depth and isodose distributions which, for treatment of deep-seated tumors, give a considerably better tumor-to-total-dose ratio than any other commonly used therapeutic radiation source (1). This improved ratio with pion irradiation is largely due to the short-ranged, heavily ionizing products resulting from nuclear pion interactions at the end of the pion track. Thus, second, an additional effectiveness of the dose delivered to the tumor relative to that delivered to healthy tissue is likely because of the oxygen effect observed with heavily ionizing radiation (2). Third, a pion beam seems at present to be the best choice in order to create a well-defined region in which nuclear reactions or nuclear stars give a substantial contribution to the radiation dose. Such conditions are essential for dosimetry and radio-biological research of strong nuclear interactions and thus for approaching a deeper understanding of the particular problems of high-energy dosimetry and radiobiology (3). In the following discussion, some experimental studies of the pion beam from the CERN 600-MeV Synchro-Cyclotron are reported. The results are limited to dosimetry and radiation quality measurements in a water phantom exposed to a 70-MeV pion beam; an attempt was also made to evaluate the average local energy deposition per stopped pion. The results are of a preliminary nature, and more extensive experimental investigations along the same lines are continuing.