Identification of anomalous optical magnetic resonances in the total emission of a mixture of neon isotopes

In the dependence of the emission of a glow discharge in a mixture of isotopes ²⁰Ne and ²²Ne on the longitudinal magnetic-field strength, we have revealed narrow resonances, while the waves have non-Lorentzian shapes and are shifted with respect to zero field. Variations in the concentration of isotopes and discharge current can vary the amplitude, the shape, and the number of resonances; however, the position of each of them on the scale of the magnetic field almost does not depend on the spectral composition of the registered emission. We have elucidated a relation between the positions of the resonances on the scale of the magnetic field and the isotope shifts of neon transitions.     

One-neutron knockout from Ne isotopes

One-neutron knockout reactions of ^24–28Ne in a beryllium target have been studied in the Fragment Separator (FRS), at GSI. The results include inclusive one-neutron knockout cross-sections as well as longitudinal-momentum distributions of the knockout fragments. The ground-state structure of the neutron-rich neon isotopes was obtained from an analysis of the measured momentum distributions. The results indicate that the two heaviest isotopes, ²⁷Ne and ²⁸Ne, are dominated by a configuration in which a s_1/2$s_{1/2}$ neutron is coupled to an excited state of the ²⁶Ne and ²⁷Ne core, respectively.     

Linear responses in time-dependent Hartree-Fock-Bogoliubov method with Gogny interaction

A numerical method to integrate the time-dependent Hartree-Fock-Bogoliubov (TDHFB) equations with Gogny interaction is proposed. The feasibility of the TDHFB code is illustrated by the conservation of the energy, particle numbers, and center of mass in the small amplitude vibrations of ²⁰O . The TDHFB code is applied to the isoscalar quadrupole and/or isovector dipole vibrations in the linear (small amplitude) region in oxygen isotopes, ^{18, 20, 22, 24}O , titanium isotopes, ^{44, 50, 52, 54}Ti , neon isotope, ²⁶Ne , and magnesium isotopes, ^{24, 34}Mg . The isoscalar quadrupole and isovector dipole strength functions are calculated from the expectation values of the isoscalar quadrupole and isovector dipole moments.     

Covalently bound molecular structures in the α + 16O system

Using the concept of covalent molecular orbitals for neutrons and the known properties of the local α + ¹⁶O potential the formation of asymmetric molecular structures in neon isotopes is discussed. Experimental evidence for parity doublets in ²¹Ne is reviewed and a corresponding band structure for the states in ²¹Ne at moderate excitation energy of E _x = 0-8 MeV is proposed. The structure of some bands can be interpreted as consisting of an instrinsic asymmetric ( ⁴He + ¹⁶O) structure bound by a covalent neutron in σ and π orbitals. An extension of the observed structures to symmetric molecular structures in isotopes of Mg and heavier nuclei is suggested. In particular shape isomers in isotopes of magnesium, namely (He)₂O molecules, can be predicted and an extended Ikeda diagram is proposed. Received: 11 July 2001 / Accepted: 22 August 2001     

Quadrupole collectivity of neutron-rich neon isotopes

The Angular Momentum Projected Generator Coordinate Method, with the quadrupole moment as collective coordinate and the Gogny force (D1S) as the effective interaction, is used to describe the properties of the ground state and low-lying excited states of the even-even neon isotopes ^20-34Ne, that is, from the stability valley up to the drip line. It is found that the ground state of the N = 20 nucleus ³⁰Ne is deformed but to a lesser extent than the N = 20 isotope of the magnesium. In the calculations, the isotope ³²Ne is at the drip line in good agreement with other theoretical predictions. On the other hand, rather good agreement with experimental data for many observables is obtained. Received: 19 Novemeber 2002 / Accepted: 24 January 2003 / Published online: 8 April 2003     

Magneto-optical trapping of bosonic and fermionic neon isotopes and their mixtures: isotope shift of the 3P2 ↔ 3D3 transition and hyperfine constants of the 3D3 state of 21Ne

We have magneto-optically trapped all three stable neon isotopes, including the rare ²¹Ne, and all two-isotope combinations. The atoms are prepared in the metastable ³P₂ state and manipulated via laser interaction on the ³P₂ ? ³D₃ transition at 640.2?nm. These cold (T ≈ 1?mK) and environmentally decoupled atom samples present ideal objects for precision measurements and the investigation of interactions between cold and ultracold metastable atoms. In this work, we present accurate measurements of the isotope shift of the ³P₂ ? ³D₃ transition and the hyperfine interaction constants of the ³D₃ state of ²¹Ne. The determined isotope shifts are (1625.9 ± 0.15)?MHz for ²⁰Ne ? ²²Ne, (855.7 ± 1.0)?MHz for ²⁰Ne ? ²¹Ne, and (770.3 ± 1.0)?MHz for ²¹Ne ? ²²Ne. The obtained magnetic dipole and electric quadrupole hyperfine interaction constants are A(³D₃) = (?142.4 ± 0.2)?MHz and B(³D₃) = (?107.7 ± 1.1)?MHz, respectively. All measurements give a reduction of uncertainty by about one order of magnitude over previous measurements.     

Frequency tuning peculiarities of enhanced power monomode He−Ne lasers

Experimental results are presented concerning some peculiarities of frequency tuning of single-longitudinal-mode He–Ne lasers at 632.8 nm which single-mode selection is performed by increasing the homogeneous broadening of laser transition. These include the observation of an asymmetry of tuning regions with respect to the output power maximum; a jump of lasing frequency during which output power drops; and a strong dependence of frequency tuning on gas pressure and output power. In the case of a mixture of ²⁰Ne and ²²Ne isotopes, analytical expressions for the dependence on frequency of output power, unsaturated gain and saturated gain are obtained and computed at different neon isotope concentrations, gas pressures and cavity losses. Simultaneous consideration of these dependences is proposed and used for an explanation of experimentally observed peculiarities in frequency tuning. The obtained results could be used for realization of a frequency-stabilized He–Ne laser of a few milliwatts power for the purposes of multidimensional interferometric measurements.     

Proton-induced direct capture on 21Ne and 22Ne

The direct capture process in the reactions ²¹Ne(p, γ)²²Na and ²²Ne(p, γ)²³Na has been investigated at E_p = 0.3–1.6 MeV using neon gas enriched to 91 % in ²¹Ne and to 99 % in ²²Ne, respectively. The gas was recirculated in a differentially pumped gas target system of the extended-static and quasi-point supersonic jet type. For ²²Ne(p, γ)²³Na, the direct capture process has been observed to several final states in ²³Na up to E_x = 8.83 MeV excitation energy. The deduced spectroscopic factors C²S are in fair agreement with the corresponding values from stripping reactions. The capture transition into the ²³Na ground state exhibits broad structures, which resemble Ericson fluctuations. The data remove the previously reported discrepancies in C²S for the ²³Na ground state. The excitation functions for the ²¹Ne(p, γ)²²Na reaction are dominated by broad and intense resonances, which hampered the measurement of the direct capture process. The nuclear and astrophysical aspects of the results are discussed.     

Optical magnetic resonances induced by the interference of reactive components in the near radiation-field zone of atoms in a glow discharge of a mixture of even neon isotopes

Four types of anomalous optical magnetic resonances shifted with respect to the zero magnetic field and with different shapes are found in radiation of a glow discharge in a mixture of even neon isotopes placed in a swept longitudinal magnetic field. This testifies to the manifestation of collective processes of synchronous light emission by oscillators belonging to isotopically different spatially separated atoms in discharge plasma. The origin of resonances is associated with nonstationary interference of reactive fields in the near radiation-field zones of emission of atoms, averaged over the lifetime of the fields (interference), while different types of resonances are associated with different methods of synchronization of the phases of the fields.     

The dissociative recombination of HeNe+ ions with electrons: The partial rate constants for the formation of atoms in the 2p 53p configuration

A simple experiment transparent for interpretation is presented in which afterglow of a discharge in helium with a small admixture of neon was studied. The intensities of the spectral lines of the Ne* atom at the stage of plasma decay were analyzed to find the conditions under which the dissociative recombination of heteronuclear ions HeNe⁺ + e ?? He + Ne* played a predominant role in the formation of part of the after-glow spectrum. The absolute values of partial coefficients responsible for the formation of excited neon atoms in the 2p ⁵3p configuration were determined.     

Resonances in Muon Transfer from Muonic Hydrogen to Oxygen and Neon

The influence of resonances on the muon transfer processes from muonic hydrogen to oxygen and neon (pμ)_1s + O⁸⁺ → p + (μO)_nl⁷⁺ and (pμ)_1s + Ne¹⁰⁺ → p + (μNe)_nl⁹⁺ is considered using the Smith lifetime matrix formalism. It is shown that the existence of a long lived resonance in the case of Ne induces a stronger dependence on collision energy of the muon transfer cross-section for this system. Present address: Chemistry Department, Vancouver University, Vancouver, BC V6T 1Z3, Canada     

Search for low-energy resonances in 21Ne(p, γ)22Na and 22Ne(p, γ)23Na

The reactions ²¹Ne(p, γ)²²Na and ²²Ne(p, γ)²³Na have been investigated at E_p(lab) = 70–355keV. Neon gas enriched to 91% in ²¹Ne and to 99% in ²²Ne was recirculated in a differentially pumped gas target system of the extended-static and quasi-point supersonic jet type. For ²¹Ne(p, γ)²²Na, new resonances were found at E_p = 126, 272, 291 and 352 keV. The 291 keV resonance corresponds to a new unbound state in ²²Na. Excitation energies, γ-ray decay schemes, resonance widths and strengths as well as J^π assignments are reported for all the resonances. Information on low-lying states in ²²Na is also obtained. Of the 9 expected resonances in ²²Ne(p, γ)²³Na none has been observed. Upper limits on their ωγy strengths are presented. The astrophysical as well as the nulcear structure aspects of the results are discussed.     

Role of neon in a decaying high-purity helium plasma

The evolution of the electron and atomic and molecular metastable densities and the radiation of the decaying plasma of helium with a 10^–5-fraction of neon additive is experimentally studied. A model of elementary processes in He–Ne plasma is constructed, which describes the formation and destruction of HeNe⁺ and Ne₂ ⁺ molecular ions and their contribution to the formation of the afterglow spectrum by the electronion recombination. The various criteria influence of neon on the parameters of the decaying plasma are studied. The possibility of determining the amount of neon in helium by measuring the relative intensities of helium molecular bands and neon spectral lines in the afterglow is considered.     

20Ne(p,p0)20Ne and states of 21Na

Cross-section and analyzing power angular distributions have been measured for ²⁰Ne(p, p)²⁰Ne and ²⁰Ne(p, p₁)²⁰Ne¹(1.63 MeV) for proton energies between 3.7 and 7.9 MeV. The measurements were made in 25 keV intervals between 3.7 and 4.4 MeV, and in 10 keV intervals over most of the region between 4.4 and 7.9 MeV. A phase-shift analysis of the elastic-scattering data has yielded resonance parameters for thirty-three levels in ²¹Na in the excitation energy region 6.0–9.9 MeV. Some of the strong even-parity resonances can be understood within the framework of the Nilsson model or the shell model. These resonances are also predicted by a macroscopic coupled-channels calculation involving rotational excitation of the 2⁺ and 4⁺ states of ²⁰Ne.     

On the Conductance of the Gas Discharge Plasma at Space Anisotropic Excitation

The galvanic manifestation of two transformations of degenerate magnetic states of the neon atom, namely self‐alignment → non‐alignment and alignment ? orientation is studied by monitoring the voltage across the discharge in a range of hollow cathode discharge (HCD) lamps. The application of a magnetic field to the discharge disorders the self‐alignment. Alignment and orientation are optically induced and their effect on the discharge conductance is compared by measuring the optogalvanic signals. The degenerate states investigated are found to contribute to the gas discharge conductance in a manner which depends on their degree of coherence. Various hollow cathode discharge media are studied including Ne/As, Ne/Cu, Ne/Ni, Ne/Cd, Ne/Li and Ne/Ca in the corresponding trademarked HCD spectral lamps. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

First on-line β-decay asymmetry measurements of oriented nuclei

We report the first on-line β-anisotropy measurements with nuclear orientation. Particle detectors operating at 4K are used. The first results were obtained on the mirror nuclei¹⁵O,¹⁷F and¹⁹Ne and on⁶⁹As. All isotopes were implanted in iron. With the same set-up⁸⁵KrFe was also measured. Important information on hyperfine fields, site occupancy, spin-lattice relaxation and magnetic moments was obtained.     

Spectroscopy of the continuum states of 24Mg using the 20Ne(α, α′) and 23Na(p, α) reactions

We have measured excitation functions for the ²⁰Ne(α, α′)²⁰Ne and ²³Na(p, α)²⁰Ne reactions in the energy ranges corresponding to, respectively, 17.85-21.67 and 19.35-20.65 MeV of excitation in ²⁴Mg, that is in the region of the sub-Coulomb resonances in ²⁴Mg observed in the ${}^{12}\text{C}\text{+}{}^{12}\text{C}$ reactions. By using statistical analysis techniques we have determined the energies of possible quasibound states in ²⁴Mg responsible for the deviations from the average trends in the above excitation functions and compared them to the energies of known sub-Coulomb resonances in ²⁴Mg. The comparison speaks in favour of interpreting the simple structures associated with the resonances as alpha-like configurations in the ²⁴Mg continuum.     

A new type of resonances in saturated absorption spectroscopy of 3-level systems

We report the experimental observation of new resonances in saturated absorption spectra of a J = 1 to J = 0 transition of Ne atoms in a static magnetic field. These resonances, which are distinct from the well-known Zeeman and cross-over resonances, result from the modification of stimulated Raman processes by the simultaneous resonant saturation of an optical transition. The light-shifts of the various resonances are also studied.     

The influence of isotope substitution of neon atom on the integral cross sections of rotational excitation in Ne-Na2 collisions

This paper applies the multiple ellipsoid model to the 16 Ne (20 Ne,28 Ne,34 Ne)-Na 2 collision systems,and calculates integral cross sections for rotational excitation at the incident energy of 190 meV.It can be seen that the accuracy of the integral cross sections can be improved by increasing the number of equipotential ellipsoid surfaces.Moreover,by analysing the differences of these integral cross sections,it obtains the change rules of the integral cross sections with the increase of rotational angular quantum number J,and with the change of the mass of isotope substitution neon atom.Finally,the contribution of different regions of the potential to inelastic cross sections for 20 Ne-Na 2 collision system is investigated at relative incident energy of 190 meV.     

SMILETRAP — Atomic mass measurements with ppb accuracy by using highly charged ions

In the SMILETRAP facility externally produced highly charged ions are captured in a Penning trap and utilized for high precision measurements of atomic masses. Accuracy tests on a ppb level have been performed, using highly charged carbon, oxygen and neon ions. In all cases hydrogen ions served as a reference for the calibration and monitoring of the magnetic field in the trap. Deviations smaller than 3 ppb from the expected results were found in mass measurements of the¹⁶O and²⁰Ne atomic masses. The proton atomic mass, determined from the reference measurements on hydrogen ions, is in good agreement with the accepted value [1]. A direct mass measurement on the⁸⁶Kr-isotope, using trapped⁸⁶Kr²⁹⁺-ions is reported.