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.

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.

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.

Measurements of momentum correlation and interaction parameters between antiprotons

The two-particle momentum correlation is influenced by the nuclear force between two particles,which has been intensively studied for nucleons and nuclei,but not much for antinucleons or antinuclei.In this proceeding,we present our STAR measurements on momentum correlation function of antiproton-antiproton and proton-proton in Au+Au collisions at S_(NN)^(1/2)= 200 GeV at the Relativistic Heavy Ion Collider.Attractive nuclear force between two antiprotons is demonstrated,and the strong interaction parameters(the scattering length and the effective range) are determined.This measurement serves as an additional verification of CPT symmetry.The present information on the strong force in the antiproton-antiproton system provides a fundamental ingredient towards understanding the structure of more sophisticated antinuclei.

Nuclear dynamics induced by antiprotons

Reaction dynamics in collisions of antiprotons on nuclei is investigated within the Lanzhou quantum molecular dynamics model. The reaction channels of elastic scattering, annihilation, charge exchange and inelastic collisions of antiprotons on nucleons have been included in the model. Dynamics on particle production, in particular pions, kaons, antikaons and hyperons, is investigated in collisions of p on12 C,20Ne,40 Ca and181Ta from low to high incident momenta. It is found that the annihilations of p on nucleons are of importance to the dynamics of particle production in phase space. Hyperons are mainly produced via meson induced reactions on nucleons and strangeness exchange collisions, which lead to delayed emission in antiproton-nucleus collisions.

Antiproton-nucleus reactions at intermediate energies

Antiproton-induced reactions on nuclei at the beam energies from hundreds Me V up to several Ge V provide an excellent opportunity to study interactions between the antiproton and secondary particles(mesons, baryons and antibaryons) with nucleons. The antiproton projectile is unique in the sense that most of the annihilation particles are relatively slow in the target nucleus frame. Hence, the prehadronic effects do not much influence their interactions with the nucleons of the nuclear residue. Moreover, the particles with momenta less than about 1 Ge V/c are sensitive to nuclear mean field potentials. This paper discusses the microscopic transport calculations of the antiproton-nucleus reactions and is focused on three related problems:(i) antiproton potential determination,(ii) possible formation of strongly bound antiproton-nucleus systems, and(iii) strangeness production.

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.

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.

Monte Carlo simulation of an antiproton annihilation detector system

A renewed antiproton annihilation detector system has been developed for the ATRAP (Antihydrogen Trap Collaboration) experiment at CERN (European Organization for Nuclear Research). It counts the antihydrogen atoms and determines the annihilation vertex of the atoms. This diagnostic element will allow to optimize the production of cold antihydrogen sufficiently to permit the optical observations and measurements. Extensive Monte Carlo simulations concerning the detector system have been developed. Different event generators as well as different geometry representations were established and evaluated. Real-time measurement with the detector system was performed and the results are calibrated via the Monte Carlo simulations.

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.

CP破坏与超对称性及_B^+1结构讨论

讨论了宇宙早期的CP破坏与超对称性伴子的相互关系,给出了现时夸克、现时轻子与超对称性夸克、轻子因CP破坏而存在的不同结构和相互关联.探讨了超对称反质子B+1与费米型反质子F+1的区别,初步说明了F+1-B+1湮灭不会象F+1F+1湮灭那样全部转化为光子的原因.

在+^（12）C弹性散射中对一种唯象的N湮灭势的研究

在Ｇｌａｕｂｅｒ多重散射理论近似下，采用泡里关联的核波函数，使用一种唯象的湮灭势，对１８０ＭｅＶ的在１２Ｃ上的弹性散射微分截面，极化角分布和自旋旋转参数进行了计算。结果表明，自旋效应可以忽略，这种势模型与实验符合得较好。

寻找顶夸克的漫长过程

本文描述寻找顶夸克的漫长过程。从70年代末开始,美国的PEP,德国的PETRA,80年代日本的TRISTAN,欧洲核子中心CERN的SP PS质子反质子对撞机,90年代的CERN的LEP大型电子正电子对撞机,最后于1997年才由美国费米国家实验室的D0和CDF国际合作组找到了顶夸克存在的证据,并给出了顶夸克的质量为:174.3±3.2±4.0GeV。人们可以从这段历史获得有益的启示。

宇宙射线中Neutralino湮灭生成的反质子谱的计算

本文计算χ～χ～→ｇｇ湮灭过程的反应截面，并进一步计算了宇宙射线中通过不同的ｎｅｕｔｒａｌｉｎｏ混合湮灭生成的反质子谱，指出了这一反质子谱线在低能区具有可观测性。

激光场中正电子对反质子的辐射复合反应

在软光子近似下 ,计算了激光场中正电子对反质子的辐射复合过程 .辐射场作为经典场处理 ,入射正电子态用Coulomb Volkov波函数描述 ,末道形成的反氢缀饰态由含时间微扰论给出 .

激光辅助的电子偶素对反质子的反氢生成反应

在一级玻恩近似下 ,研究了在激光辅助的电子偶素 反质子碰撞中的反氢合成 .发现在小角范围内 ,平行于电子偶素入射方向极化的激光使反氢生成截面变小 .在中等角度范围 ,截面有一定的增加 ,特别当偏振方向垂直于入射方向时 。

对一种唯象的N周边湮灭势的研究

本文使用一种唯象的Ｎ周边湮灭势，对１８０ＭｅＶ的在^(１６)Ｏ上的弹性微分截面进行计算，理论结果与实验符合得较好。

反质子在核上的弹性散射和库仑效应

基于Ｇｌａｕｂｅｒ理论，用含有自旋项的二体元振幅，考虑库仑作用，对１８０ＭｅＶ的反质子在核上的弹性散射微分截面、极化角分布和自旋旋转参数进行计算，结果与实验相符。