Double charge exchange and one-pion production in collisions at 1.7 GeV/c

Jeanneret, J.B.; Bogdanski, M.; Jeannet, E.

doi:10.1016/0375-9474(80)90463-7

Cited by 12 publications

(5 citation statements)

References 12 publications

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“…The total DCX cross section presumably falls at higher energy, as both collisions occur at energies above that of the ∆ resonance. Previous measurements at higher energies [5,7] do indeed support this hypothesis.…”

Section: Total Reaction Cross Sectionssupporting

confidence: 66%

“…This and several subsequent measurements [2,3,4] of DCX cross sections in 3 He and 4 He were undertaken as searches for bound three-or four-neutron states using the (π − , π + ) reaction. More broadly motivated studies of DCX in 4 He at energies above the ∆ resonance were carried out using liquid helium bubble chambers [5,6,7]. In the energy range 98-156 MeV total cross section measurements were performed by Falomkin et al [8,9] using a high-pressure helium streamer chamber.…”

Section: Previous Experimental Workmentioning

confidence: 99%

“…Jeanneret et al [7] considered a model of DCX in which pion-induced pion production (PIPP) is followed by two-nucleon absorption of one of the two final pions. The calculation is a convolution of the free PIPP cross section and pion absorption cross section in deuterium (π + d → pp), with some corrections for the available phase space.…”

Section: Previous Theoretical Workmentioning

confidence: 99%

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Inclusive pion double charge exchange inHe4at intermediate energies

et al. 2005

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A systematic experimental study of inclusive pion double charge exchange in 4 He has been undertaken. The reaction 4 He(π + , π − )4p was observed at incident energies 120, 150, 180, 240 and 270 MeV; the 4 He(π − , π + )4n reaction was observed at incident energies 180 and 240 MeV. At each incident energy, the doubly differential cross section was measured at three to five outgoing pion laboratory angles between 25 • and 130 • . At each angle, cross sections were measured over the range of outgoing pion energies from 10 MeV up to the kinematic limit for the reaction in which the final state consists of the oppositely charged pion plus four free nucleons.The spectra of outgoing pions are strikingly different from those observed for the inclusive double charge exchange reaction in heavier nuclei, but resemble those observed in the (π − , π + ) reaction in 3 He. The forward-angle spectra in the 3 He and 4 He reactions exhibit a prominent peak at high outgoing pion energies. Interpretation of the peaks in 3 He ( 4 He) as a three-(four-)nucleon resonance is ruled out by kinematic analysis. The results of a calculation, wherein the double charge exchange reaction is assumed to proceed as two sequential single charge exchange interactions, suggest that the high-energy peak is naturally explained by this double scattering mechanism.Non-static treatment of the πN interactions and the inclusion of nuclear binding effects appear to be important in reproducing the shape of the energy spectra at forward angles.Pion double charge exchange (DCX), a nuclear reaction in which two units of charge are exchanged between a pion and a nucleus, is an important tool with which to investigate the details of the pion-nucleus interactions as well as correlations between nucleons within the nucleus. DCX is unique among pion-nuclear scattering reactions, as it must involve at least two nucleons in order to conserve charge. Thus, the physiognomy of the DCX process revealed by the experimental cross section depends on the coordinates of two particles in the wavefunction of the nucleus. As a probe of the pion-nucleus interaction, DCX may be used to isolate contributions from different types of reaction mechanisms. Other pion-nucleus reactions appear to be dominated by single scattering mechanisms, but DCX must proceed through less simple mechanisms such as double scattering, as shown in Fig. 1(a).An experimental investigation of DCX in 4 He at intermediate energies has been performed in order to study the multiple scattering mechanisms of the π-nucleus reaction directly. The choice of 4 He as a nuclear target allows an investigation of DCX in an extensively studied few-body system for which microscopic treatment of the dynamics is possible in principle. At the same time, the 4 He nucleus has a large density which may allow some effects of the nuclear medium to be investigated. The final state is also relatively simple, consisting of a pion and either four protons or four neutrons, resulting from, respectively, the reactions 4 He(π + , π − )...

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Section: Total Reaction Cross Sectionssupporting

confidence: 66%

Section: Previous Experimental Workmentioning

confidence: 99%

Section: Previous Theoretical Workmentioning

confidence: 99%

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Inclusive pion double charge exchange inHe4at intermediate energies

et al. 2005

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“…1(a) [11,18] and on the alternative mechanisms illustrated in Figs. 1(b) [15], and 1(c) and 1(d) [19] have not achieved quantitative success in reproducing the available data [1,3,4, 19 -23]. Until recently, the theoretical literature on DCX in heavier nuclei was very sparse [24 -26].…”

Section: Introductionmentioning

confidence: 99%

Systematics of inclusive pion double charge exchange in the delta resonance region

et al. 1992

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A systematic study of inclusive pion double charge exchange is reported for nuclei between A = 16 and A =208. The doubly differential cross sections for the A(m. +,~) and A(m, m+) reactions in ' 0, Ca, ' Rh, and 'Pb were measured at incident energies between 120 and 270 MeV at three to five outgoing pion angles. Pion spectra were measured over the energy range from 10 MeV to the kinematic limit for double charge exchange. Integrating these spectra over outgoing pion energy generated angular distributions, and subsequently integrating these angular distributions generated total reaction cross sections. The shapes of the measured spectra are compared with those determined by the distribution of events in four-body phase space and with those predicted by a model in which the pion undergoes two sequential single charge exchanges on nucleons in a Fermi gas. The cross sections are compared with predictions of cascade calculations in which more than two interactions, including pion absorption and scattering without charge exchange, may occur. PACS number(s): 25.80.Gn, 25.80. Hp, 25.80.Ls major objective was to satisfy persistent curiosity about 'Present address: Continuous Beam Electron Accelerator Facility,

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“…10.+S Since nuclei are bound by the exchange of mesons it is reasonable to assume that, even in their ground states, nuclei should have some measurable properties due to their mesonic degrees of freedom. The search for "mesons in nuclei" has concentrated on corrections to nuclear magnetic moments, photonuclear reactions and sum rules, and low-energy electron scattering.…”

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confidence: 99%

Pion Double Charge Exchange onHe4and Meson Exchange Currents

et al. 1981

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We have measured the differential cross section cfto/d®, dT and estimated the total cross section u T for the double charge exchange reaction 4 He(7r + ^') Ap at 140, 200, and 295 MeV. The values for cr T are at least an order of magnitude larger than predictions based on sequential single charge exchange ir-N scatterings. It is possible, therefore, that 4 He(7r + ,7r") is dominated by other processes, such as the formation of a A in the intermediate state or scattering from meson exchange currents.PACS numbers: 25.10.+S Since nuclei are bound by the exchange of mesons it is reasonable to assume that, even in their ground states, nuclei should have some measurable properties due to their mesonic degrees of freedom. The search for "mesons in nuclei" has concentrated on corrections to nuclear magnetic moments, photonuclear reactions and sum rules, and low-energy electron scattering. 1 The mesonic effects, however, are usually small and always model dependent. Calculations that are sensitive to meson exchange currents are frequently sensitive to poorly known details of the nuclear wave functions as well.One promising class of reactions for studying meson exchange effects is pion double charge exchange. Conservation of charge automatically rules out the "first-order" processes that usually mask the weaker exchange effects. Recent work on double charge exchange has centered around transitions to discrete nuclear states. However, these cross sections are very small, and the nuclear-structure complications inherent in these transitions have made it unrealistic to use double charge exchange as a probe of exchange currents. There are some double charge exchange transitions between light nuclei and continuum states, however, which might be simple enough for a detailed study of the reaction mechanism. Double charge exchange on 4 He, as proposed by Germond and Wilkin, 2 has been the most widely studied. But even here the data are sparse and apparently inconsistent.We have recently completed an experiment on double charge exchange on 3 He and 4 He using the EPICS pion spectrometer at the Clinton P. Anderson Meson Facility. We report here our results for the total cross sections for the reaction 4 He-(7r + , 7r~)4/>, which can be compared directly with the work of Germond and Wilkin as well as with several other theories that assume other reaction mechanisms.The EPICS spectrometer has already been used in several double charge exchange experiments. 3 We mention only a few features that are peculiar to this experiment. Since we are interested in continuum states, it was necessary to use as much of the spectrometer acceptance as possible. The acceptance depends mainly on the deviation &-(p -Po)/Po from the central momentump 0 . It was calibrated over the range 6 = -0.08 to +0.11 782

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Double charge exchange and one-pion production in collisions at 1.7 GeV/c

Cited by 12 publications

References 12 publications

Inclusive pion double charge exchange inHe4at intermediate energies

Inclusive pion double charge exchange inHe4at intermediate energies

Systematics of inclusive pion double charge exchange in the delta resonance region

Pion Double Charge Exchange onHe4and Meson Exchange Currents

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