Measurement of the strong interaction parameters in antiprotonic deuterium

Antiprotonic deuterium K_α X-rays were seen for the first time. Their analysis resulted in spin-averaged 1s strong interaction parameters, namely −1050±250 eV (repulsive) for the 1s shift and 1100±750 eV for the 1s width. The large errors are mainly due to low statistics. In addition, values for the K_α/L_α and L_total/L_α yields at low pressure (20 mbar) were obtained: 0.005±0.003 and 1.34±0.05. Furthermore, a 2p mean absorption width of 80 ≤Γ_2p≤ 350 meV was deduced. The results for the 1s ground state are somewhat surprising, especially the narrow 1s width which is similar to the spin-averaged antiprotonic hydrogen 1s width. However, our 1s width is in agreement with low-energy scattering data [A. Zenoni et al., Phys. Lett. B 461 (1999) 413] (see preceding paper).     

Theoretical analysis of collisional shift and broadening of antiprotonic helium spectral lines

Effect of medium density on shift and broadening of ( ) spectral lines is considered in the framework of binary-collision approximation with an effective ( )–He potential including the long-range attraction and short-range repulsion. Quantum calculations of the scattering phase shifts at reasonable values of the potential parameters allow to explain the main features of the observed density effect on the shape of ( ) spectral lines in low-temperature helium. This revised version was published online in August 2006 with corrections to the Cover Date.     

Precision measurement of antiprotonic hydrogen and deuterium X-rays

X-rays from antiprotonic hydrogen and deuterium have been measured at low pressures. Using the cyclotron trap, a 105 MeV/c antiproton beam from LEAR was stopped with an efficiency of 86% in 30 mbar hydrogen gas in a volume of only 100 cm³. The X-rays were measured with Si(Li) detectors and a Xe-CH₄ drift chamber. The strong interaction shift and broadening of the Lyman transition and the spin-averaged 2p width in antiprotonic hydrogen was measured with unprecedented accuracy. The triplet component of the ground state in antiprotonic hydrogen was determined for the first time.The authors would like to thank the LEAR staff for their efforts in providing the antiproton beam. The help of P. Gauss from the CERN cryogenic group and of P. Zettwoch from the PS workshop is gratefully acknowledged. We wish to thank K.-P. Wieder for his help with the drawings. This work is part of the Ph.D. thesis of one of us (K.H., University of Karlsruhe, 1990).     

High-precision laser spectroscopy of antiprotonic helium atomcules and effects of collisions at high-density conditions

We have performed laser spectroscpy of metastable antiprotonic helium atoms (or “atomcules”) ( He⁺) and have observed a density dependence of the resonance vacuum wavelengths for the known transitions (n,l)=(39,35)→(38,34) and (37,34)→(36,33). They showed linear red-shifts of 0.61±0.01 GHz and 0.22±0.02 GHz per 1 g℞, respectively. With the shift parameters above, the transition vacuum wavelengths were extrapolated to zero-density limits, yielding λ₀ = 597.2570± 0.0003 nm and λ₀ = 470.7220±0.0006 nm, respectively. These values were compared with the result of recent theoretical calculations on the energy of the Coulombic three-body system, including relativistic corrections and the Lamb shift. The agreements between our experimental values and the calculations have become as good as 2×10^-6. This sets a severe constraint on the antiproton charge ( ) and mass ( ) with |Q _p - |/e < 5 × 10^-7 and |M _p - |/M _p < 5 × 10^-7, under a more precisely known constraint on the charge-to-mass ratio. Thus we have opened a new possibility of measuring fundamental constants of the antiproton. This revised version was published online in August 2006 with corrections to the Cover Date.     

氢及氘的宽区物态方程研究进展

氢是自然界最丰富的元素,是天体物理和惯性约束聚变（ICF）研究的重要对象。简要综述了国内外氢及氘宽区物态方程研究进展,特别评述了OMEGA激光装置上的最新冲击压缩实验和理论模型的对比分析情况。在以往数据分析评估基础上,利用改进的化学自由能模型、第一原理数值模拟结果及多参数物态方程模型,构建了氢的宽区物态方程,适用温度、密度范围分别为20～10⁸ K,10⁻⁷～2000 g/cm³。与已有多类实验如冲击压缩实验、静高压等温线实验、声速等实验结果对比表明,新构建的氢宽区物态方程具有较高的置信度,为天体物理、惯性约束聚变、国际热核实验堆等工程物理设计提供高精度的支撑数据。氢宽区物态方程的构建及验证方法亦可适用于其同位素氘,该方法构建的氘宽区物态方程与2019年最新发表的主雨贡纽、二次冲击雨贡纽数据的吻合程度明显优于当前国外模型。指出了未来研究需要关注的状态区域。     

Interaction of hydrogen and deuterium with intrinsic atomic defects in high-purity electron-irradiated nickel

Abstract

High-purity nickel was irradiated with 2 MeV electrons at temperatures below 80 K to a dose of 1 × 10²³ e^?/m² in the as-prepared state and after charging with H or D. By means of magnetic after-effect measurements relaxations of anisotropic radiation-induced defects and of defect-hydrogen complexes were investigated in the temperature range between 4.2 and 500 K. The isochronal annealing behaviour of these relaxations and the isochronal recovery of the residual resistivity was measured simultaneously on the same specimens. At temperatures below the hydrogen mobility (< 160 K) in charged irradiated specimens relaxation maxima are observed at 45, 100, 115 and 140 K which show no isotope shift for H and D charging. The maxima below 160 K are explained by defect-hydrogen complexes, where radiation-induced defects reorient around immobile hydrogen atoms. Above 160 K, where hydrogen atoms get mobile, in charged irradiated specimens a broad relaxation maximum appears at 170 K which shows an inverse isotope shift for H and D charging. This 170 K maximum anneals in Stage III. A hydrogen diffusion maximum observed in charged specimens at 215 K prior to irradiation is missing after electron irradiation. The 170 K relaxation is explained by defect-hydrogen complexes, where hydrogen atoms reorient around immobile radiation-induced defects while the long-range hydrogen diffusion is suppressed by these defects. In such relaxation measurements hydrogen and deuterium atoms are used as a “probe” to investigate radiation-induced defects.     

Measurement of the 4f strong interaction level width in light antiprotonic atoms

The yields of the atomic 4→3 transitions in antiprotonic¹⁴N,^16,17,18O,¹⁹F, and²³Na were measured at the CERN antiproton facility, LEAR. From these, the widths Γ_up of the 4f levels were determined to be 136±19meV (¹⁴N); 603±22 meV (¹⁶O); 731±35 meV (¹⁷O); 795±23 meV (¹⁸O); 2.79±0.16 eV (¹⁹F); and 23.8±7.4 eV (²³Na).     

Collisional quenching of metastable states of antiprotonic helium by hydrogen and deuterium molecules

The quenching of metastable states of antiprotonic helium by collisions with hydrogen and deuterium molecules was studied. A systematic investigation of the delayed annihilation time spectra at various H₂ and D₂ admixture ratios at the ppm level revealed characteristic changes of their shape, which indicated a strong principal and orbital quantum number dependent quenching of levels in both cases. Applying a laser spectroscopy technique to measure the lifetimes of individual states and cascades we deduced H₂ and D₂ quenching cross-sections for the states (n, l )= (39, 35) and (37, 34). These cross-sections establish for D₂ molecules the strong increase of the quenching efficiency with increasing principal quantum number n of the state under investigation previously reported for the case of H₂ admixtures. Our experiments indicate that the low-n state (37, 34) is somewhat less affected by D₂ than by H₂, while the high-n state (39, 35) is equally quenched by both isotopes. Received 2 October 2000     

Hydrogen and deuterium diffusion in non-stoichiometric spinel

High pressure/temperature annealing experiments are used to determine diffusivities of H⁺ and D⁺ in non-stoichiometric spinel, a low-pressure analogue for nominally anhydrous minerals in Earth’s mantle. Data are fitted to the following Arrhenius law: Diffusivity (m²/s)?=?4?±?1?×?10^?12 exp(?54?±?2 kJ?mol^?1/RT). At low temperatures, H⁺ and D⁺ diffusion in non-stoichiometric spinel is charge balanced by flux of O vacancies, with infrared data consistent with protonation of both octahedral and tetrahedral O–O edges in non-stoichiometric spinel, and additional fine structure due to Mg–Al mixing and/or coupling of structurally incorporated H⁺ with cation vacancies. Absence of changes in the fine structure of O–H absorption bands indicates that H⁺ can become locally coupled and uncoupled to other defects during bulk diffusion. As such, proton conductivity in spinel group minerals, arising from faster flux of uncoupled H⁺, can only be calculated from H⁺ mobility data if the extent of defect coupling is constrained.     

K-原子体系与强相互作用

K-原子体系满足KleinGordon方程,通过考虑K-介子与核子之间的强相互作用,引入相应的光学模型势,经求解并数值计算得到的一组K-原子能级,与实验数据吻合得很好,其结果支持了光学模型势描述强相互作用的正确性     

强磁场中氢分子离子H2^＋能级的绝热及绝热变分计算

采用绝热近拟和绝热变分近似两种方法,计算了均匀强磁场（１０≤β≤１０００）中Ｈ２＾＋的σｇ,πｕ,δｇ,Φｕ,γｇ,ηｕ态的能有有原子核间的平衡距离,并与前人的结果进行了比较。     

High accuracy calculation of the hydrogen negative ion in strong magnetic fields

Using a full configuration-interaction method with Hylleraas-Gaussian basis function, this paper investigates the 1¹0⁺, 1¹(–1)⁺ and 1¹(–2)⁺ states of the hydrogen negative ion in strong magnetic fields. The total energies, electron detachment energies and derivatives of the total energy with respect to the magnetic field are presented as functions of magnetic field over a wide range of field strengths. Compared with the available theoretical data, the accuracy for the energies is enhanced significantly. The field regimes 3 < γ < 4 and 0.02 < γ < 0.05, in which the 1¹(–1)⁺ and 1¹(–2)⁺ states start to become bound, respectively, are also determined based on the calculated electron detachment energies.     

离子镀制备Cr/W混合过渡层的氢氘辐照效应研究

用双离子束镀膜方法在W基底表面制备不同厚度的Cr薄膜. 用冷场扫描电镜能谱分析仪对镀膜样品成分深度分布进行分析, 使用重离子加速器对镀膜样品进行高能、低束流的氢或氘辐照, 用扫描电镜对样品表面形貌变化进行分析, 运用粒子注入射程模拟软件SRIM对氢粒子在Cr/W双层块体中的射程进行模拟分析. 实验结果表明, 运用双离子束镀膜法能够在膜与基底的接触面区域制得Cr/W混合过渡层; 在高能、低束流的氢或氘辐照下, Cr/W混合过渡层易于使气体滞留而起泡, 双离子束制备的Cr膜层不易聚集氢或氘气体成泡.     

Quenching of metastable antiprotonic helium atoms in collisions with deuterium molecules

Quenching of metastable antiprotonic helium atoms in collisions with deuterium molecules has been studied using laser spectroscopy at CERN's new Antiproton Decelerator facility. The quenching cross-sections of the states (n, l )= (39, 36), (39, 37), and (39, 38) were determined from the decay rates of the states which were observed using the “deuterium-assisted inverse resonance” (DAIR) method. The results revealed a similar (n, l )-dependence of the quenching cross-sections as in the case of hydrogen but the values were smaller by a factor of ∼1.5. Received 6 July 2001     

Structural transitions in hydrogen and deuterium at ultrahigh pressures

Abstract

Raman measurements indicate that normal hydrogen and deuterium compressed in a diamond-anvil cell at 77 K undergo phase transformations at 145 (±l5) GPa and 190 (±l20) GPa, respectively. The new observations reported for deuterium indicate that the transition in both isotopes is a structural change not associated with a simple rotational ordering mechanism. The possibility of a structural transition driven by band-gap closure is discussed.     

Vibrational relaxation of a molecule in strong interaction with a reservoir: Nonmonotonic temperature dependence

This theoretical study of the vibrational relaxation of a molecule in interaction with a reservoir uncovers a noteworthy temperature (T) dependence of the time evolution of the relaxation. Its rate increases with T in one interval but decreases in another. The feature arises not for a weak molecule-reservoir interaction but only for coupling strong enough to require polaronic dressing transformations. Our treatment, based on a recent generalization of the well-known Montroll–Shuler equation for relaxation and an explicit calculation of bath correlations from the microscopically specified Hamiltonian, could provide an alternative explanation of an “inverted” T-dependence of relaxation in an experimental report by Fayer and collaborators on W(CO)₆ dissolved in CHCl₃.     

Formic acid in deuterium and hydrogen matrices

ABSTRACT

Formic acid (HCOOH, FA) was studied experimentally, by infrared spectroscopy, in H₂ and D₂ matrices, with focus on the preparation and characterisation in these matrix media of structures containing the higher-energy (cis) conformer. The cis-FA monomer and the cis-FA^?…?N₂ complex were successfully produced by selective vibrational excitation of corresponding trans-FA based species, and vibrationally characterised. The tunneling-induced conversion of the cis-FA^?…?N₂ complex in the studied matrices into the corresponding trans-FA complex was also investigated, and the found tunnelling properties discussed, in particular in comparison with those observed for the spontaneous conversion of cis-FA monomer into trans-FA. This article constitutes the first report on the infrared spectrum of FA conformers and stability of cis-FA monomer in a D₂ matrix, and on the structure, spectroscopy and stability of the cis-FA^?…?N₂ complex in both H₂ and D₂ matrices. Different attempts to prepare the cis-FA^?…?H₂O complex in the two investigated matrices are also described in detail, both from previously in situ generated cis-FA monomer followed by thermal mobilisation and by direct selective vibrational excitation of the trans-FA-H₂O complex.     

Study of strong interaction between Pt and TiO2 under oxidizing atmosphere

The strong interaction between Pt and TiO₂ under oxidizing atmosphere was studied by means of X-ray photoelectron spectroscopy (XPS) and Ar⁺ sputtering test. The results obtained show that under oxidizing atmosphere Pt⁰ atoms can thermally diffuse into TiO₂ lattice and be oxidized to Pt²⁺ to substitute for Ti⁴⁺ or form the interstitial ions at 673 K.     

An effective potential method for the calculation of hydrogen molecule ion energy in a strong magnetic field

Using the adiabatic approximation and adiabatic variational approximation with an effective potential, the total energies and the equilibrium internuclear separations of H₂⁺ ion in states σ_g, π_u, δ_g, φ_u, γ_g, η_u in strong magnetic fields have been calculated. Our results reproduced those obtained by Vincke and Baye (Vincke M and Baye D 1985 J. Phys. B: At. Mol. Phys. 18 167), which are considered the most reliable. We found a basic function with better convergence than the Landau functions.     

高密度氢气的分子间相互作用与状态方程

本文从高密度氢气的分子间相互作用出发进行分析,在修改范德瓦耳方程的基础上,提出了一种新的适用于高密度氢气的状态方程,并用来系统地计算了氢气在临界区的等温压缩线.在缺乏实验数据的情况下,这些理论计算结果很有用.