Pion Double Charge Exchange on<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">He</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>4</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>and Meson Exchange Currents

Stetz, A.W.; Swenson, L.W.; Davis, J.; Källne, J.; Minehart, R.; Whitney, R. R.; Perez‐Mendez, V.; Sagle, A.; Carroll, J.; McClelland, J. B.; Faucett, J.A.

doi:10.1103/physrevlett.47.782

Cited by 25 publications

(6 citation statements)

References 11 publications

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“…Stetz et al [14] appear to be systematically lower than the present results by approximately 30-50%. This difference is greater than the uncertainties arising from normalization and integration in both experiments (see Ref.…”

Section: Comparison With Other Measurementscontrasting

confidence: 72%

“…Binding effects were not included, but the resonance width was modified to account for Pauli blocking and absorption. The results of their calculation agreed qualitatively with the existing data, though they exceeded the measurement of Stetz et al [14] and did not reproduce its energy dependence.…”

Section: Previous Theoretical Workmentioning

confidence: 58%

“…Of the previous experiments [2,4,8,9,14,15] which have investigated the DCX reaction in 4 He in the energy region of the present experiment, only one [14,15] affords the possibility of comparison with the present results for the doubly differential cross sections. Two experiments [2,4] were searches for tetraneutron bound states, performed for a limited range of incident and outgoing pion energies at a scattering angle of 0 • .…”

Section: Comparison With Previous Measurementsmentioning

confidence: 77%

“…The first modern measurement of doubly differential cross sections for inclusive DCX, using a magnetic spectrometer to detect the outgoing pions, was made at the Schweizerisches Institut für Nuklearforschung (now PSI) for the 16 O(π + , π − ) reaction [13]. Subsequently, the 4 He(π + , π − ) reaction was studied by Stetz et al [14,15] using the EPICS spectrometer at the Los Alamos Meson Physics Facility (LAMPF). Stetz et al measured doubly differential cross sections for three incident pion energies (140, 200, and 295 MeV) at several angles in the range 30 • -120 • .…”

Section: Previous Experimental 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: Comparison With Other Measurementscontrasting

confidence: 72%

Section: Previous Theoretical Workmentioning

confidence: 58%

Section: Comparison With Previous Measurementsmentioning

confidence: 77%

Section: Previous Experimental Workmentioning

confidence: 99%

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Inclusive pion double charge exchange inHe4at intermediate energies

et al. 2005

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“…Pion spectra and total cross sections for pion double charge exchange were also measured in Refs. [40][41][42] for different incident pion energies. No evidence for 4 n was obtained.…”

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confidence: 99%

Search of Trineutron and Tetraneutron

Kezerashvili¹

2017

Fission and Properties of Neutron-Rich Nuclei

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In light of a new experiment which claims an identification of tetraneutron [3], we discuss the results of experimental search of trineutron and tetraneutron in different nuclear reactions. A summary of theoretical studies for trineutron and tetraneutron within variety of approaches such as variational methods, the method of Faddeev and Faddeev-Yakubovsky equations, and the method of hyperspherical harmonics are presented.The cataclysmic events that occur near the end of the life of a star lead to one of only three possible final states: a white dwarf, a neutron star, or a black hole. The mass of the star, particularly that of the core, appears to be the primary factor in determining the final state. A more massive star would need to be hotter to balance its stronger gravitational attraction. While a star is burning, the heat in the star pushes out and balances the force of gravity. When the star's fuel is spent, and it stops burning, there is no heat left to counteract the force of gravity. How much mass the star had when it died determines what it becomes. Detailed calculations have shown that for star with mass less than about 1.4 times the mass of our sun electron degeneracy pressure permanently halts collapse. White dwarfs are stable cold stars that are supported by electron degeneracy pressure. Calculations show that stars that have between 1.4 and 3 times the mass of the sun implode into neutron stars that are the end product of stellar evolution, and their outer core is composed of neutrons at truly enormous densities. The central region of the neutron star is supported by the degeneracy pressure of neutrons. A star with mass greater than 3 times than of the sun gets crushed into a single point -a black hole.At high density, when the sum of masses of a proton and electron, and Fermi energy over c 2 exceeds the neutron mass, it is energetically favorable to combine a proton and an electron into a neutron: p + e − → n + ν e . Both neutron and neutrino rich matter are produced at the core. Since the mean free path of neutrinos is much smaller than the radius of neutron stars neutrinos do not accumulate inside neutron stars. Therefore, at higher densities, matter becomes more and more neutron-rich. A progressive neutronization of matter at higher and higher densities makes a lower energy state. An attractive pairing interaction between neutrons, can couple them to form a state with integer spin and, therefore, paired neutrons act like bosons. These "bosons" can form a condensate-like state in which all of the bosons occupy the same quantum state and form a superfluid. Just as the pairing of protons that are charged fermions forms a superconductor. In that same general sense, we also can have superconductivity and superfluidity in neutron stars. Thus, we can have superconductivity and superfluidity in the outer core of neutron stars. Superconductivity and superfluidity, if observed in neutron stars, could tell us a lot about the pairing and hence inform us about aspects of nuclear physics that are mighty diffi...

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Very Neutron-Rich Very Light Nuclei

Ogloblin

Penionzhkevich

1989

Treatise on Heavy Ion Science

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Pion Double Charge Exchange onHe4and Meson Exchange Currents

Cited by 25 publications

References 11 publications

Inclusive pion double charge exchange inHe4at intermediate energies

Inclusive pion double charge exchange inHe4at intermediate energies

Search of Trineutron and Tetraneutron

Very Neutron-Rich Very Light Nuclei

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