Antiproton Interactions Research Articles

Low-energy antiprotons as a new probe of nuclear reaction mechanism

The experimental data of LEAR, KEK and BNL on low-energy antiproton interaction with nuclei are analysed in the framework of the Glauber-Sitenko approach. It is shown that antiproton-nucleus interaction gives new information on the nuclear reaction mechanism, on nuclear structure and on parameters of the p N amplitude.

Interaction and annihilation of antiprotons and nuclei

Experiments with slow antiprotons and nuclei reveal what happens when matter and antimatter come together and annihilate. Before the annihilation antiprotonic atoms are formed, and after the annihilation many fast particles are emitted and much lighter residual nuclei are left.

Book reviewss

Book reviewss

Low energy antiproton annihilation on nuclei

Data obtained in the study of the antiproton interaction on4He, Ne and photographic emulsion nuclei are reported. Charged prong multiplicities, branching ratios and reaction cross-section values are given. Some features of¯p annihilation deep inside the nuclear matter are described. Cosmological restrictions deduced from3He production in¯p 4He reactions are discussed.

Inelastic interaction of antiprotons with 4He nuclei between 200 and 600 MeV/c

The antiproton-helium reaction cross section has been measured at 19.6 and 48.7 MeV with a streamer chamber in a magnetic field. Charged prongs and negative pion multiplicities and cross sections for the production of 3He are given. A comparison with p 2H is performed. he previously obtained 179.6 MeV results are also taken into account.

The start-up of lear physics

The main features and present status of the LEAR facilities are reviewed. The first experimental results on proton — antiproton interactions include: X-rays of protonium which are seen, the status of ongoing searches for bound state and resonances in the p p system, first results in annihilation dynamics and meson spectroscopy. A programme on p interaction with nuclei has already given significant results: p - nucleus elastic and inelastic scattering, annihilation on nuclei (streamer chamber and elecronics technique) .

Experimental apparatus for studying the interaction of antiprotons with light nuclei

A description is given of the detector system (self-shunted streamer chamber in a magnetic field) used in the PS-179 experiment at LEAR for studying antiproton interactions with light nuclei.

Hydrodynamical-model analysis of high-energy interactions due to mesons, antiprotons and α-particles

The pseudorapidity distributions of secondary particles in 50–200 GeV meson and anti-proton interactions with various target nuclei and in α-emulsion interactions are compared with the predictions of the hydrodynamical model. The agreement between the experimental and the predicted distributions is excellent.

Quarks and the nucleon-antinucleon interaction

Experiments withlow momentum antiprotons have opened a new possibility to study nuclear interaction at short distances. For this part of the nuclear interaction the quark structure of the nucleons has to be considered explicitly. Interaction of antiprotons and strange particles with nuclei gives an additional constraint to the models of nuclear interaction.

Evidence for a narrow N [formula omitted] state at 2.02 GeV/ c2 in 6 and 9 GeV/ c antiproton interactions

We report evidence for the existence of a charged narrow state of mass M ∼ 2.02 GeV/ c 2 and widtt Γ ⪅ 0.04 GeV/ c 2, decaying into N N ̄ . The state is observed in the reaction pp → p fast n π +π −π − at 6 GeV/ c and in pp →π fast + pn π +π − at 9 GeV/ c in a triggered bubble chamber experiment at the SLAC Hybrid Facility.

Limits on baryonium production inp¯pinteractions at 8.3 and 13.0 GeV/c

Results are presented from a search for the production of narrow $\overline{p}p$ states in antiproton interactions at 8.3 and 13.0 GeV/c. Cross-section upper limits have been established for four candidate baryonium states. The upper limits (95% probability level) range from 0.21 to 1.29 \ensuremath{\mu}b for inclusive forward production, and from 0.11 to 0.89 \ensuremath{\mu}b for backward production in the final state ${\ensuremath{\omega}}_{f}^{0}(\overline{p}p)$.

Astrophysical aspects of antiproton interaction with 4He (antimatter in the universe)

We show that the experimental information on p 4He annihilation may impose limits on the possible amount of anti-matter in the early universe and other important cosmological topics, predicted by some variants of GUT cosmology.

Low energy antiproton-nucleus interactions

The interaction of 175-MeV antiprotons with nuclei is examined within the intranuclear cascade model. The experimental characteristics of nucleon-antinucleon annihilation and scattering are used as input, and the propagation of the resultant pions through the nucleus is treated realistically. The effect of the antiproton-nucleus strong attraction is also included. Overall characteristics of antiproton annihilation within nuclei, particularly the large, well-defined energy deposition, indicate that such collisions constitute a unique laboratory for the study of nuclei at very high excitations. The calculations also identify promising experimental observables and triggers.NUCLEAR REACTIONS 175 MeV antiproton-nucleus scattering and annihilations. Intranuclear cascade calculations. Nuclei at high excitations.

Antiproton interactions with light elements as a test of GUT cosmology

Antiproton interactions with light elements as a test of GUT cosmology

Interaction of antiprotons with deuterons at low energies

Approximate methods of solving the few-body problem are applied to describe the interaction of anti-protons with the deuteron. In cases available the results are compared with calculations based on solving the Faddeev equations.

Search for NarrowN¯NStates near Threshold

A missing-mass experiment in p-bard ..-->.. NX, where X is the system whose mass M/sub X/ is measured, was performed for interactions of antiprotons at rest and in flight below 500 MeV/c. The 4-standard-deviation upper limit for the production of narrow states, in the mass interval M/sub X/=1650--1930 MeV/c/sup 2/, is 2 mb for annihilations in flight and 0.3% of the annihilations at rest.

A search for direct electron production in low energy antiproton interactions

A search has been made for direct single electrons and positrons in the interactions of the 1.6 GeV/c antiprotons with nucleons. At the 90% confidence level the rate of production was found to be e − π charged < 5.5 × 10 −5 and e − π charged < 4.8 × 10 −5 . In addition, all the observed direct electron positron pairs can be accounted for by known processes.

Few remarks about hadron resonance and their effects in hadronic atoms

Interactions of antikaons, antiprotons and nucleons at very low energies are discussed in terms of separable potential models. Coulomb interactions are included and formulae for strong shifts of electromagnetic hadronic hydrogen are obtained. These are discussed as a way of determination of scattering amplitudes below thresholds. Applications to hadronic deuterium are mentioned.

Two-body hyperon final states in antiproton interactions at 2.2 GeV/c

The reactions\(\bar pp \to \bar \Lambda \Lambda \),\(\bar \Lambda \Sigma ^0 + C.C.\),\(\bar \Sigma ^ + \Sigma ^ + \) and\(\bar \Sigma ^ - \Sigma ^ - \) are studied at 2.2 GeV/c. The cross-section, differential cross-section, polarization and spin correlations (between the\(\bar \Lambda \) and Λ hyperons) are discussed.

Antiproton-deuteron low-energy cross-sections

About 45000 interactions of antiprotons of kinetic energy between 57 and 170 MeV have been measured in a deuterium bubble chamber. Total and annihilation cross-sections have been determined at 9 values of the antiproton energy together with the differential crosssection dσ/dt for scattering events. In spite of the peculiar behaviour of the deuteron target at these low energies a reliable measure of the antiproton-neutron annihilation cross-section has been obtained.