Plasmas Created in the Interaction of Antiprotons with Atomic and Ionized Hydrogen Isotopes. Suggested Fuels for Space Engines

The main objective of the present work is to investigate the properties of plasmas created by injecting a thermalized beam of antiprotons in two types of media. The first is hydrogen, deuterium, or tritium atoms localized in palladium crystals. The second medium is composed of protons, deuterons, or tritons localized in a magnetic cavity. Particularly, it is demonstrated that huge amounts of energy are released in both cases which could be used as fuels for space shuttle engines. A novel mathematical scheme is employed to calculate the energy yields in real space at different incident energies of the antiprotons.

Annihilation of Antiprotons in Light Nuclei

CR-39 detectors have been exposed to a 5.9-MeV antiproton beam using the low energy antiproton ring （LEAR） facility at CERN. At this energy, tracks of antiprotons appear in a CR-39 detector after 135 rain of etching in 6M NaOH at 70℃. Fluence of the antiproton beam has been determined using track density. We have also found tracks in the etched CR-39 detector at different depths （250-500μm）. These tracks have resulted from the annihilation of antiprotons with the constituents （H, C and O） of the CR-39 detector. The goal of the experiment is to develop a simple and low-cost method to study properties of antiparticles and those formed after annihilation of these particles with the target matter.

Impact of a nearby subhalo on the constraint of dark matter annihilation from cosmic ray antiprotons

Numerous simulations indicate that a large number of subhalos should be hosted by the Milky Way.The potential existence of a nearby subhalo could have important implications for our understanding of dark matter(DM)annihilation.In this study,we investigate the hypothetical presence of a nearby subhalo and set the upper limits on the DM annihilation cross section by analyzing the cosmic-ray antiproton spectrum.By presenting the ratios of annihilation cross section limits for scenarios with and without a nearby subhalo,we can quantitatively evaluate the potential impact of the nearby subhalo on the limits of the DM annihilation cross section.The impacts of the concentration model and the subhalo probability distribution have been considered.We explore the antiproton contribution of the potential nearby DM subhalo accounting for the DAMPE e+spectrum at~1.4 TeV and find that the current AMS-02 antiproton results do not limit this contribution.

Implications for Antigravity Tests of Dirac’s Negative Energy Antiparticles

P. A. M. Dirac conceived antimatter in 1928 as having negative energy by allowing a consistent representation of matter-antimatter annihilation into light. To achieve compatibility with special relativity, particle physics of the early 20th century made the theoretical assumption that antiparticles have positive energy, an assumption that remains in effect as of today. In this note we prove apparently for the first time a theorem stating that positive mass antiparticles violate Dirac’s particle-antiparticle annihilation into light. We then show the consequential unsettled character of the recent gravity test of the anti-Hydrogen atom due to the positive mass of its nucleus. We conclude by suggesting that a final scientific claim on matter-antimatter gravity requires tests on particles with clear antimatter character, such as the 1994 resolutory proposal for the comparative test of the gravity of very low energy electron and positron in horizontal flight on a supercooled vacuum tube.

Simulation of an Antimatter Beam Core Engine for Space Travel

An exciting prospect is the use of antimatter as a fuel source due to its ability to convert mass energy to kinetic energy. Upon annihilation of antimatter with matter, tremendous amounts of energy are carried away by charged and neutral particles. By redirecting the charged particles through an exhaust using a non-uniform magnetic field, an impulse can be generated capable of supplying thrust to an engine. Using the Geant 4 simulation toolkit developed by CERN, we simulate this process using a beam core engine design. By analyzing charged pions that result from antiproton-proton annihilation, we optimize the engine parameters and derive a specific impulse for antiproton fuel as used in the beam core configuration. A specific impulse of (2.49 ± 0.08) × 106 s was determined. This value is significantly higher than specific impulses of current chemical rocket fuels which range from 240 - 400 s.

Positron Induced Fusion Pulsed Space Propulsion through an Ultra-Intense Laser

A pulsed space propulsion system using position antimatter to induce Deuterium-Tritium fusion through an ultra-intense laser incident on a gold target is conceptually presented through fundamental performance analysis. As opposed to traditional strategies positron antimatter is considered rather than antiproton antimatter. Positron antimatter can be produced by an ultra- intense laser incident on a high atomic number target, such as gold. The ultra-intense laser production of positron antimatter mechanism greatly alleviates constraints, such as requirements for antimatter storage imperative for antiproton antimatter. Also the ultra-intense laser and associated energy source can be stationary or positioned remote while the pulsed space propulsion system using position antimatter to induce Deuterium-Tritium fusion is in flight. Various mechanisms for antimatter catalyzed fusion are considered, for which the preferred mechanism is the antiproton hotspot ignition strategy. Fundamental performance analysis is subsequently applied to derive positron antimatter generation requirements and associated propulsion performance. The characteristics of the pulsed space propulsion system using position antimatter to induce Deuterium-Tritium fusion through an ultra-intense laser incident on a gold target imply a promising non-chemical propulsion alternative for the transport of bulk cargo to support space missions.

Antiproton Production with a Fixed Target and Search for Superheavy Particles at the LHC

A proposal for an experiment to measure the cross section of antiproton production in a proton-nuclear collision in a kinematically forbidden region for nucleon-nucleon interaction on a fixed LHC target is considered. It is shown that this process can be separated from the kinematically allowed production process using the existing detectors of the ALICE facility at a proton energy of 7 TeV with a fixed nuclear target. Assuming the scale dependence of the cross section, the data obtained can be used to estimate the subthreshold cross section for the production of superheavy particles with a mass of several tens of TeV in the LHC lead nucleus beam.

1-4 Strangeness Production in Antiproton Induced Nuclear Reactions.

More localized energy deposition is able to be produced in antiproton-nucleus collisions in comparison withheavy-ion collisions due to annihilation reactions. Searching for the cold quark-gluon plasma (QGP) with antiprotonbeamshas been considered as a hot topic both in experiments and in theretical calculations over the past severaldecades. Strangeness production and hypernucleus formation in antiproton-induced nuclear reactions are importancein exploring the hyperon (antihyperon)-nucleon (HN) potential and the antinucleon-nucleon interaction, whichhave been hot topics in the forthcoming experiments at PANDA in Germany.

Superheavy Particle Production in High Energy Heavy Ion Collisions

The existence of several TeV superheavy particles (SHPs) is predicted by theories beyond the Standard Model. Particles with a mass exceeding the energy in the center of mass in the collision of protons with protons can be produced in subthreshold heavy ion collisions at the LHC. The purpose of the performed research was to estimate the rate of a rare process of SHPs production. It was shown that the data on the subthreshold production of antiprotons can be explained by the phenomenological parton model. The obtained parton distribution function was used to determine the number of SHPs produced in subthreshold heavy ion collisions at the LHC. In one month of collision of lead with lead, the yield of 16 TeVparticles is about 70 per year. To study the kinematically forbidden phenomena in proton-proton interactions in collisions of heavy nuclei at the LHC, an experiment on the production of antiprotons is proposed in the ALICE fixed target project.

Inelastic Scattering of Antiproton From ^(18)O

The differential cross sections of the inelastic scattering of antiproton leading to the2+ excited stae of 18O are calculated at 178.4 MeV by the Eikonal approximation and thecollective model of nucleus.It may be concluded that the 2+ state is a quadruple rotationalstate.The results are in good agreement with experimental data.

Form factor measurements with ANDA at FAIR

The high intensity and high energy antiproton beams which will be produced at FAIR open the possibility to determine time-like electromagnetic form factors in a wide kinematical range, through the annihilation reaction： p ＋ p → e^＋ ＋ e^-. The status of the proposed experiment as well as the expected results are presented on the basis of realistic simulations. The impact of these measurements on the understanding of the nucleon structure, of the asymptotic properties of form factors and of the reaction mechanism are discussed using model independent statements based on symmetry properties of the strong and electromagnetic interactions in connection with space-like data.

Antiproton production in heavy-ion collisions at subthreshold energies

Within the framework of the Lanzhou quantum molecular dynamics model,the deep subthreshold antiproton production in heavy-ion collisions has been investigated thoroughly.The elastic scattering,annihilation and charge exchange reactions associated with antiproton channels are implemented in the model.The attractive antiproton potential extracted from the G-parity transformation of nucleon selfenergies reduces the threshold energies in meson-baryon and baryon-baryon collisions,and consequently enhances the antiproton yields to some extent.The calculated invariant spectra are consistent with the available experimental data.The primordial antiproton yields increase with the mass number of the colliding system.However,annihilation reactions reduce the antiproton production which becomes independent of the colliding partners.Anti-flow phenomena of antiprotons correlated with the mean field potential and annihilation mechanism is found by comparing them with the proton flows.Possible experiments at the high-intensity heavy-ion accelerator facility(HIAF) in China are discussed.