Trapped Bose–Einstein condensates with quadrupole–quadrupole interactions

We numerically investigate the ground-state properties of a trapped Bose–Einstein condensate with quadrupole–quadrupole interaction.We quantitatively characterize the deformations of the condensate induced by the quadrupolar interaction.We also map out the stability diagram of the condensates and explore the trap geometry dependence of the stability.     

Analytical transfer matrix of a quadrupole fringe

The analytical linear transfer matrices for different quadrupole fringes including quadratic, high order power and exponential models are deduced in this paper. As an example, the transfer matrices of the quadrupole BEPCⅡ/ 105Q are computed for the above three models and compared with hard edge and slice-by-slice models in cases of near 60° and 90° FODO cells. These models' results are much better than the hard edge model's, and can meet the requirement of accurate calculation.     

New nuclear quadrupole resonance technique in β-NMR

The -NMR technique has been modified in order to detect efficiently the nuclear quadrupole effects in the NMR spectra. -NMR is detected as a function of coupling frequency; all RFs that correspond to the coupling frequency were applied simultaneously.     

Cooling induced by parametric resonance in a magnetic quadrupole trap

It is demonstrated experimentally that the anharmonic property of the quadrupole trap can be exploited to cool trapped atoms by modulating the trap potential anisotropically.This cooling effect arises from the energy-selective removal of the most energetic trapped atoms and the thermal equilibrium of the remaining atoms.The frequency dependences of the temperature and the fraction of the atoms left in the trap after the modulation are explored.It is also demonstrated that the cooling induced by parametric resonance can also increase the phase space density of the trapped atoms.     

Measurement of the electric quadrupole moments of 26–29Na

The nuclear electric quadrupole moments of the isotopes ²⁶Na, ²⁷Na, ²⁸Na and ²⁹Na were measured by -NMR spectroscopy in single crystals of LiNbO₃ and NaNO₃. High degrees of nuclear polarization were produced by optical pumping of the sodium atoms in a fast beam with a collinear laser beam. The polarized nuclei were implanted into the crystals and NMR signals were observed in the -decay asymmetries. Preparatory measurements also yielded improved values for the magnetic moments of ^27-31Na and confirmed the spin I=3/2 for ³¹Na. The results are discussed in comparison with large-basis shell model calculations. Received: 1 February 2000 / Accepted: 3 April 2000     

Precise measurement of the quadrupole moment of β-emitting12B

Hyperfine interactions of¹²B(I ,T _1/2=21 ms) implanted in the substitutional site of B atoms (stable) in a (single crystal like) BN (hexagonal) was studied by use of a -NMR detection. For efficient and simple measurements, the conventional -NMR has been modified as a new nuclear quadrupole resonance technique (NNQR). For the present case with the nuclear spinI=1 the detection efficiency is improved about 30 times compared with the one with the old method. The quadrupole moment of¹²B was determined precisely as ¦Q(¹²B; 1⁺)¦=13.21±0.26 mb.     

Study of the SF 6 − ion lifetime in a rf quadrupole trap

We use an experimental apparatus to study SF ₆ ^– ions lifetimes. These ions are created inside a quadrupole rf trap by charge exchange between highly excited argon atoms and SF₆ molecules. Ions are observed from 200 s up to 15 ms after their creation time. In order to explain experimental results, collisions with SF₆ molecules and the influence of ionized core of argon are taken into account. A part of SF ₆ ^– ions are stabilized by the last influence. These results evidence a radiative stabilization phenomenon, the lifetime of which is estimated at about 5 ms.Equipe de Recherche associée au C.N.R.S. 0898Laboratoire associé au C.N.R.S. 0282     

Optical polarization of neutron-rich sodium isotopes and β-NMR measurements of quadrupole moments

The nuclear quadrupole moments of neutron-rich sodium isotopes are being investigated with the help of in-beam polarization by optical pumping in combination with-NMR techniques. First measurements have yielded the quadrupole splittings of NMR signals in the lattice of LiNbO₃ for the isotopes²⁶Na,²⁷Na and²⁸Na. Interaction constants and ratios of the electric quadrupole moments are derived. In view of future experiments,-decay asymmetries for the sequence of isotopes up to theN=20 neutron shell closure,^26–31Na, have been measured.     

Electric quadrupole moment of the 9/2− isomer in171Ta

The electric quadrupole moment of the 9/2^– isomer in the¹⁷¹Ta nucleus, populated in the¹⁵⁹Tb(¹⁶O,4n)¹⁷¹ Ta reaction, has been measured for the first time using the TDPAD technique. The measured value Q(9/2^–)=3.09(19) b andB(M1)/B(E2) ratios, deduced from the existing -ray spectroscopic data, have been used to derive shape parameters for the h_11/2 band based on this isomer. The present results are consistent with a quadrupole deformation=0.22(1),=0⁰±10⁰.     

57Fe Mössbauer-effect studies of quadrupole splitting distributions in icosahedral Al-TM-Fe quasicrystals

Room temperature⁵⁷Fe Mössbauer effect spectra of several Al-TM-Fe icosahedral quasicrystals are reported. Results of fits to discrete sites and to various distributions of quadrupole splittings are presented. Mean isomer shifts, \(\overline \delta \) , and quadrupole splittings, Δ, are shown to be insensitive to the fitting procedure used. Trends in \(\overline \delta \) and \(\overline \Delta \) for the icosahedral phase may be indicative of a Hume-Rothery stabilization mechanism.     

Mineral Mössbauer spectroscopy: Correlations between chemical shift and quadrupole splitting parameters

The variety of coordination numbers, symmetries, distortions and ligand environments in thermally-stable iron-bearing minerals provide wide ranges of chemical shift () and quadrupole splitting () parameters, which serve to characterize the crystal chemistries and site occupancies of Fe²⁺ and Fe³⁺ ions in minerals of terrestrial and extraterrestrial origins. Correlations between ferrous and ferric chemical shifts enable thermally-induced electron delocalization behavior in mixed-valence Fe²⁺-Fe³⁺ minerals to be identified, while chemical shift versus quadrupole splitting correlations serve to identify nanophase ferric oxides and oxyhydroxides in oxidized minerals and in meteorites subjected to aqueous oxidation before and after they arrived on Earth.     

Aharonov–Anandan quantum phases and Landau quantization associated with a magnetic quadrupole moment

The arising of geometric quantum phases in the wave function of a moving particle possessing a magnetic quadrupole moment is investigated. It is shown that an Aharonov–Anandan quantum phase (Aharonov and Anandan, 1987) can be obtained in the quantum dynamics of a moving particle with a magnetic quadrupole moment. In particular, it is obtained as an analogue of the scalar Aharonov–Bohm effect for a neutral particle (Anandan, 1989). Besides, by confining the quantum particle to a hard-wall confining potential, the dependence of the energy levels on the geometric quantum phase is discussed and, as a consequence, persistent currents can arise from this dependence. Finally, an analogue of the Landau quantization is discussed.     

A preliminary quadrupole asymmetry study of a β=0.12 superconducting single spoke cavity

An Accelerator Driven System(ADS) has been launched in China for nuclear waste transmutation. For the application of high intensity proton beam acceleration, the quadrupole asymmetry effect needs to be carefully evaluated for cavities. Single spoke cavities are the main accelerating structures in the low energy front-end. The single spoke cavity has small transverse electromagnetic field asymmetry, which may lead to transverse RF defocusing asymmetry and beam envelope asymmetry. A superconducting single spoke resonator(PKU-2 Spoke) of β=0.12 and f =325 MHz with a racetrack-shaped inner conductor has been designed at Peking university. The study of its RF field quadrupole asymmetry and its effect on transverse momentum change has been performed. The quadrupole asymmetry study has also been performed on a β=0.12 and f =325 MHz ring-shaped single spoke cavity. Our results show that the quadrupole asymmetry is very small for both the racetrack-shaped and the ring-shaped single spoke cavity.     

Fine structure of the isoscalar giant quadrupole resonance in Ca due to Landau damping?

The fragmentation of the Isoscalar Giant Quadrupole Resonance (ISGQR) in ⁴⁰Ca has been investigated in high energy-resolution experiments using proton inelastic scattering at Ep=200 MeV$E_{\mathrm{p}}=200\text{MeV}$. Fine structure is observed in the region of the ISGQR and its characteristic energy scales are extracted from the experimental data by means of a wavelet analysis. The experimental scales are well described by Random Phase Approximation (RPA) and second-RPA calculations with an effective interaction derived from a realistic nucleon–nucleon interaction by the Unitary Correlation Operator Method (UCOM). In these results characteristic scales are already present at the mean-field level pointing to their origination in Landau damping, in contrast to the findings in heavier nuclei and also to SRPA calculations for ⁴⁰Ca based on phenomenological effective interactions, where fine structure is explained by the coupling to two-particle–two-hole (2p–2h) states.     

A preliminary quadrupole asymmetry study of a Iβ=0.12 superconducting single spoke cavity

An Accelerator Driven System (ADS) has been launched in China for nuclear waste transmutation. For the application of high intensity proton beam acceleration, the quadrupole asymmetry effect needs to be carefully evaluated for cavities. Single spoke cavities are the main accelerating structures in the low energy front-end. The single spoke cavity has small transverse electromagnetic field asymmetry, which may lead to transverse RF defocusing asymmetry and beam envelope asymmetry. A superconducting single spoke resonator (PKU-2 Spoke) of β =0.12 and f=325 MHz with a racetrack-shaped inner conductor has been designed at Peking university. The study of its RF field quadrupole asymmetry and its effect on transverse momentum change has been performed. The quadrupole asymmetry study has also been performed on a β =0.12 and f=325 MHz ring-shaped single spoke cavity. Our results show that the quadrupole asymmetry is very small for both the racetrack-shaped and the ring-shaped single spoke cavity.     

Mössbauer NMR double resonance in57Fe. Coupling between quadrupole split states

In order to describe the interaction of a nucleus (in a static electric field gradient) with a radiation field, we have introduced the concept of dressed nucleus. The eigenvalues of its Hamiltonian are calculated, which leads to expressions for the different energies of -rays produced by spontaneous emission. We have calculated these energies as well as their relative probabilities in the case ofI _e=3/2^--I_g=1/2^- Ml transitions. We have shown that a Mössbauer spectrum using as a source an ensemble of dressed nuclei and a single line absorber consists of six lines: two lines of the original quadrupole doublet and four sidebands, each of them having the same intensity.     

Site analysis and calculation of the quadrupole splitting of Prussian Blue Mössbauer spectra

The insoluble Prussian Blue (IPB) structure, Fe\(^{\mathrm {3+}}_{~~~4}\)[Fe ^II(CN)₆]₃.14H₂O, is shown to have ten distinctly different ferric sites, as well as the single ferrous site. The statistical probability of these sites was determined and the point charge model used to calculate the relative quadrupole splitting values. Previous Mössbauer spectra of IPB have fitted the ferric site with one doublet. Our results show that there is a large difference between the quadrupole splittings of the different ferric sites and hence it is not a reasonable approximation to fit them using a single doublet.