Strangeness production in proton—proton and proton—nucleus collisions

We discuss the investigation of the strange meson production in proton-proton (pp) and proton-nucleus (pA) reactions within an effective Lagrangian model. The kaon production proceeds mainly via excitations ofN*(1650),N*(1710), andN* (1720) resonant intermediate nucleonic states, in the collision of two initial state nucleons. Therefore, the strangeness production is expected to provide information about the resonances lying at higher excitation energies. For beam energies very close to the kaon production threshold the hyperon-proton final state interaction effects are quite important. Thus, these studies provide a check on the models of hyperon-nucleon interactions. The inmedium production of kaons shows strong sensitivity to the self-energies of the intermediate mesons     

Phenomenological analysis connecting proton–proton and antiproton–proton elastic scattering

Based on the behavior of the elastic scattering data, we introduce an almost model-independent parameterization for the imaginary part of the scattering amplitude, with the energy and momentum transfer dependences inferred on an empirical basis and selected by rigorous theorems and bounds from axiomatic quantum field theory. The corresponding real part is analytically evaluated by means of dispersion relations, allowing connections between particle–particle and particle–antiparticle scattering. Simultaneous fits to proton–proton and antiproton–proton experimental data in the forward direction and also including data beyond the forward direction lead to a predictive formalism in both energy and momentum transfer. We compare our extrapolations with predictions from some popular models and discuss the applicability of the results in the normalization of elastic rates that can be extracted from present and future accelerator experiments (Tevatron, RHIC and LHC). PACS 13.85.Dz, 13.85.-t     

Jet production in polarized proton proton scattering

We propose a model of polarized partonic densities based on Regge behaviour, quark counting rules,U(1) _A Goldberger-Treiman relation and positivity constraints. The resulting polarized proton structure function is found to be in agreement with EMC and SLAC data. From this input we compute double helicity asymmetries for 1 and 2 jet inclusive production in polarized proton proton scattering at high energies. We obtain asymmetries of 10–20% at energies \(\sqrt s = 50 - 500\) GeV.     

Rise of proton proton total cross section and inclusive spectra

The origin of the rise of p-p total cross section (σ_t(pp)) is investigated by making use of the inclusive sum rule. The contribution to the rise of σ_t(pp) from the development of sharp peak near the kinematical boundary in the process p+p→p+ “anything” is almost completely canceled out by the decrease of the cross section in other x-region between s=45 (GeV/c)² and s=2820 (GeV/c)². Then the net contribution to the rise of σ_t(pp) from the process p+p→p+ “anything” is very likely to be zero. The true origin of the rise of σ_t(pp) is found to be the increase of inclusive cross sections at x ? 0 between PS and ISR energies. The contribution from the process p+p→π+ “anything” at x ? 0 to the rise of σ_t(pp) is estimated to be 3.2 mb, that from the process p+p→K + “anything”, 0.71 mb and that from the process p+p→$\text{p}$ “anything”, 0.62 mb. According to our conclusion we expect that all total cross sections will rise with energy at high energy.     

质子照相中成像磁透镜系统对次级质子的消除

 为了解成像磁透镜系统使用对提高质子照相品质的作用,研究了成像磁透镜系统对核反应产生的次级质子的消除作用。利用MCNPX模拟了次级质子的能谱,结果表明：次级质子的平均能量不足照相质子束的50%。从次级质子的能量特性和成像系统质子运动学方面的分析表明：成像磁透镜系统可消除次级质子的影响。利用程序MCNPX对含成像磁透镜系统的质子照相进行了模拟,结果显示：成像磁透镜系统将次级质子对光程的影响减小到2%以下,显著提高了图像品质。     

β-delayed proton decays near the proton drip line

We briefly reviewed the experimental study on β-delayed proton decays near the proton drip line published by our group during the period of 1996–2004, namely the first observation of the β-delayed proton decays of 9 new nuclides in the rare-earth region and the new measurements of β-delayed proton decays of 5 nuclides in the mass ∼90 region near theN=Z line with the aid of the “p-y” coincidence in combination with a He-jet tape transport system. In the meantime some important experimental technique details were supplemented. The experimental results, including the half-lives, spins, parities, deformations and production reaction cross sections for the 14 nuclei were summarized and compared with the current nuclear-model predictions, and then the following points were represented. (1) The experimental half-lives for⁸⁵Mo and⁹²Rh as well as the predicted “waiting point” nuclei⁸⁹Ru and⁹³Pd are 5–10 times longer than the theoretical predictions given by M?ller et al. using a macroscopic-microscopic model. It considerably influences the predictions of the abundances of the nuclides produced in the rp-process. (2) The current-model predictions are not consistent with the experimental assignments of the spins and parities for the proton drip-line nuclei¹⁴²Ho and¹²⁸Pm. However, the nuclear potential energy surface (PES) calculated by using a Woods-Saxon-Strutinsky method reproduced the experimental results. (3) The Alice code overestimated the production reaction cross sections of the studied 9 rare-earth nuclei by one order of magnitude or two, while HIVAP code overestimated them by one order of magnitude approximately.     

Small-angle proton - proton scattering cross-sections at 144 MeV

The differential cross-section in proton-proton scattering at 144 ± 1.5 MeV has been measured over the Coulomb-nuclear interference region. When the present data are included in a phase-shift analysis the resultant phas-shifts are only slightly changed from their previous values.     

Systematics of proton emission

A very simple formula is presented that relates the logarithm of the half-life, corrected by the centrifugal barrier, with the Coulomb parameter in proton decay processes. The corresponding experimental data lie on two straight lines which appear as a result of a sudden change in the nuclear shape marking two regions of deformation independently of the angular momentum of the outgoing proton. This feature provides a powerful tool to assign experimentally quantum numbers in proton emitters.     

Dynamics of proton glasses

The effects of random fields on the soft-spin dynamics of an Ising spin glass with infiniterange interactions are studied in the vicinity of instability line separating the ergodic and nonergodic phase.     

Isospin constraints for two particle distributions in proton proton interactions

From isospin invariance we derive inequalities which relate the (2I _A +1)(2I _B +1) two-particle spectra in the reactionp+p→A+B+ anything, where the measured particles in the final state belong to isospin multipletsI _A ,I _B =0, 1/2, 1.     

Heavy quark energy loss in proton proton collisions at LHC

A promising probe to study deconfined matter created in high energy nuclear collisions is the energy loss of (heavy) quarks. Experiments at the Relativistic Heavy Ion Collider (RHIC) have shown that heavy quarks, i.e. charm and bottom quarks show a remarkable high momentum suppression, comparable to light quarks. In this exploratory study we investigate the energy loss of heavy quarks in high multiplicity proton proton collisions at LHC energies. We will find a small, however non-negligible energy loss of high momentum charm quarks.     

Preparation and characterization of proton exchange membranes with through-membrane proton conducting channels

The primary goal of this study is to develop a novel PEMs with unique surface structure utilizing the high viscosity of the impregnation solution. SiO₂ nanofiber mats were prepared via the electrospinning method and introduced into sulfonated poly(ether sulfone) (SPES) matrix to prepare hybrid membrane. The effect of concentration of impregnation solution on the morphology and properties of the proton exchange membranes (PEMs), including thermal stability, water uptake, dimensional stability, proton conductivity, and methanol permeability were investigated. SEM results showed that a unique surface structure was prepared due to the high solution concentration. Moreover, the hydrophilic nanofibers on the surface constructed continuous proton pathways, which can enhance the proton conductivity of the membranes, a maximum proton conductivity of 0.125 S/cm was obtained when the SPES concentration was 40 wt% at 80 °C, and the conductivity was improved about 1.95 times compared to that of pure SPES membrane. The SiO₂ nanofiber mat-supported hybrid membrane could be used as PEMs for fuel cell applications.     

Fast proton decay

We consider proton decay in the testable flipped SU(5)×UX₍₁₎$\mathit{SU}(5)\times U{(1)}_X$ models with TeV-scale vector-like particles which can be realized in free fermionic string constructions and F-theory model building. We significantly improve upon the determination of light threshold effects from prior studies, and perform a fresh calculation of the second loop for the process p→e⁺π⁰$p\to e^{+}{\pi }^0$ from the heavy gauge boson exchange. The cumulative result is comparatively fast proton decay, with a majority of the most plausible parameter space within reach of the future Hyper-Kamiokande and DUSEL experiments. Because the TeV-scale vector-like particles can be produced at the LHC, we predict a strong correlation between the most exciting particle physics experiments of the coming decade.     

The elastic scattering of proton on proton at an energy of 8 GeV

The paper describes the measurement of the differential cross-section for pp scattering at an energy of 8 GeV. The results of the paper agree well with the assumption that there exists a real part of the scattering amplitude that is 33% of the imaginary part.     

Some theoretical aspects of the presence of spin in proton proton elastic scattering

Some theoretical aspects on the problem of spin in proton proton elastic scattering in the range of energy starting from few GeV/c up to ISR energies are discussed.Presented at the Symposium on Hadron-Hadron Scattering at High Energies, Liblice, Czechoslovakia, June 16–21, 1975.I thank A.Martin and J.Soffer for their help in preparing this talk.     

Production of charmed hadrons in neutrino proton and antineutrino proton charged current interactions

Usind data from avp and \(\bar v\) p experiment with BEBC at CERN, the rates for inclusive production ofD ^*+,Λ _c ⁺ andD ⁰ invp scattering and ofD ^*? in \(\bar v\) p scattering are measured. Some examples of the exclusive production ofD ^*+,Λ _c ⁺ and∑ _c ⁺⁺ are given. The cross section for the reactionvp→μ ^? _c ⁺⁺ is estimated.     

中能质子注量率测量

质子是太空辐射环境中的主要粒子成分,随着半导体工艺向着小尺寸高集成度方向不断发展,质子单粒子效应不容忽视.通过加速器模拟空间辐射进行地面实验是评价质子单粒子效应最重要的手段,质子注量率的准确测量是器件考核评估过程中最关键的环节.本文基于原子能院100MeV质子单粒子效应辐照装置,突破了宽量程中能质子注量率测量技术,开发了法拉第筒、塑料闪烁体探测器和二次电子发射监督器等探测工具,可以对束流进行宽量程范围准确测量,解决了质子注量率在10~6—10~7 p·cm^-2·s^-1范围内难以测量的关键难题,并进行了注量率不确定度的分析研究,同一注量率下法拉第筒和塑料闪烁体探测器的实验测量误差与理论分析误差相符.对中能质子注量率测量达到了国际同类装置水平.该研究建立的中能质子注量率测量系统和不确定度分析方法,为准确评估元器件辐射效应奠定了基础.     

The size of the proton

The root-mean-square (rms) charge radius r _p of the proton has so far been known only with a surprisingly low precision of about 1% from both electron scattering and precision spectroscopy of hydrogen. We have recently determined r _p by means of laser spectroscopy of the Lamb shift in the exotic “muonic hydrogen” atom. Here, the muon, which is the 200 times heavier cousin of the electron, orbits the proton with a 200 times smaller Bohr radius. This enhances the sensitivity to the proton’s finite size tremendously. Our new value r _p?=?0.84184 (67) fm is ten times more precise than the generally accepted CODATA-value, but it differs by 5 standard deviations from it. A lively discussion about possible solutions to the “proton size puzzle” has started. Our measurement, together with precise measurements of the 1S–2S transition in regular hydrogen and deuterium, also yields improved values of the Rydberg constant, R _?∞??=?10,973,731.568160 (16) m^???1.