共查询到20条相似文献,搜索用时 796 毫秒
1.
B. Viaris de Lesegno J.C. Karam M. Boustimi F. Perales C. Mainos J. Reinhardt J. Baudon V. Bocvarski D. Grancharova F. Pereira Dos Santos T. Durt H. Haberland J. Robert 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(1):25-34
A new Stern Gerlach interferometer operating with a nozzle beam of metastable argon atoms Ar* (3p5 4s, 3
P
2) is described. The selection of incoming (polarisation) and outgoing (analysis) Zeeman sublevels is achieved by use of laser
induced transitions at two wavelengths, 811.5 nm (closed J = 2 → J = 3 transition) and 801.5 nm (open J = 2 → J = 2 transition). Linear superpositions of Zeeman sublevels, just beyond the polariser and just before the analyser, are prepared
by means of two zones where Majorana transitions take place. In between, a controlled magnetic field configuration (the phase
object) is produced within a triple μ-metal shielding. Standard interference patterns are obtained by scanning the field and
detecting the atoms by secondary electron emission from a Faraday cup. When a static radial magnetic gradient is used, the
beam profile is modulated by interference. The transverse pattern, which can be translated at will by adding a homogeneous
field, is observed for the first time using a multi-channel electron multiplier followed by a phosphor screen and a CCD camera.
The results satisfactorily agree with all theoretical predictions.
Received 27 June 2002 / Received in final form 20 September 2002 Published online 4 February 2003
RID="a"
ID="a"e-mail: perales@lpl.univ-paris13.fr
RID="b"
ID="b"UMR 7538 du CNRS 相似文献
2.
M. Gutfleisch D.I. Shin T. Dreier P.M. Danehy 《Applied physics. B, Lasers and optics》2000,71(5):673-680
Laser-induced thermal gratings (LITG) were generated in mixtures of ethylene and ammonia in nitrogen using mid-infrared laser
radiation from a grating-tuned, low-pressure, pulsed (5 ms pulse width) CO2 laser, and read out with a continuous wave Nd:YLF laser. The LITG signal intensity was measured as a function of pressure
(0.1–2 MPa) and temperature (300–800 K, at 0.1 and 1 MPa) by tuning the laser to the accidental coincidences of the 10P(14)
and 10R(6) emission lines with molecular absorption transitions of C2H4 and NH3, respectively. Comparisons are made with theoretical predictions for the grating efficiency from a simple thermalization
model. A theoretical comparison of the temporal LITG signal response for three excitation pulse shapes – a delta function,
a realistic pulse, and a square wave is presented. Furthermore, it is shown that for NH3, most of the decrease of the LITG signal intensity with increasing temperature is due to the corresponding decrease in fractional
molecular absorption of the pump beam radiation. The diagnostic capabilities of the mid-infrared LITG experiment is demonstrated
for spatially resolved ethylene measurements with long laser pulses in a premixed stoichiometric CH4–air flame at atmospheric pressure.
Received: 17 March 2000 / Revised version: 23 March 2000 / Published online: 13 September 2000 相似文献
3.
H. Shu S.-Z. Fu X.-G. Huang M.-X. Ma J. Wu J.-J. Ye J.-H. He Y. Gu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(2):367-370
Using the ninth laser beam (converted to 2ω) of
“Shenguang-II” laser facility and the beam smoothing technology of
lens-array [Appl. Opt. 25, 377 (1986); Phys. Plasmas. 9, 3201 (1995)],
a shock wave with 700 μm (the root-mean-square of
shock breakout time (RMS) RMS ≈ 6.32 ps) flat top was created. An Al-Al
four-step target was designed to do research on shock wave stability in an
Al target. And the shock stability experiment with the Al-Al four-step
target indicated that the shock wave steadily propagated in the Al target of
thickness of about 20–45 μm under the power density of ~ 1.0×1014 W/cm2. 相似文献
4.
A. Miffre M. Jacquey M. Büchner G. Trénec J. Vigué 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(2):353-365
Using an atom interferometer, we have measured the static electric
polarizability of 7Li α=(24.33 ±0.16)×10-30
m3 = 164.2±1.1 atomic units with a 0.66% uncertainty. Our experiment, which is similar to an experiment done on sodium in 1995
by Pritchard and co-workers, consists in
applying an electric field on one of the two interfering beams and measuring the resulting phase-shift. With respect to Pritchard's
experiment, we have made several improvements which
are described in detail in this paper: the capacitor design is such that the electric field can be calculated analytically;
the phase sensitivity of our interferometer is substantially better,
near 16 mrad/
; finally our interferometer is species selective so that impurities present in our atomic beam (other alkali atoms or lithium
dimers) do not perturb our
measurement. The extreme sensitivity of atom interferometry is well illustrated by our experiment: our measurement amounts
to measuring a slight increase Δv of the atom velocity v
when it enters the electric field region and our present sensitivity is sufficient to detect a variation Δv/v ≈6 ×10-13. 相似文献
5.
D. Sarkisyan T. Becker A. Papoyan P. Thoumany H. Walther 《Applied physics. B, Lasers and optics》2003,76(6):625-631
An extremely thin cell (ETC) with the thickness of a Rb atomic vapor layer in the range of 100–300 nm was fabricated. It is
demonstrated that a simple laser-diode technique with a single resonant light beam is sufficient to observe separately all
of the atomic hyperfine transitions of the D
2 line of Rb (780 nm) and also allows us to measure the relative transition probabilities of the hyperfine transitions. The
onset of collisional self-broadening of the hyperfine transitions as the number density of atoms increases was studied. The
detrimental role of the atoms with slow longitudinal velocity in the sub-Doppler response of the Rb ETC is demonstrated by
studies in which the cell is tilted from normal incidence of the laser beam. It is also shown that using an ETC allows us
to resolve in a moderate external magnetic field the Zeeman splitting of the hyperfine transitions of the 87Rb D
1 transition F
g=1F
e=1,2.
Received: 19 February 2003 / Revised version: 4 April 2003 / Published online: 2 June 2003
RID="*"
ID="*"Corresponding author. Fax: +374/32-31172, E-mail: david@ipr.sci.am 相似文献
6.
F.P. Heßberger S. Hofmann D. Ackermann 《The European Physical Journal A - Hadrons and Nuclei》2003,16(3):365-370
Radium isotopes with mass numbers from 209 to 212 have been produced by heavy-ion fusion reactions 204Pb( 12C, xn) 216-Ra. Radioactive decay properties were investigated by means of α- and α-γ-spectroscopy after in-flight separation of the evaporation
residues from the projectile beam by the velocity filter SHIP and implantation into a 16-strip position-sensitive Si detector.
For the even-even nuclei 210,212Ra we identified α transitions into the first-excited 2+-state of the daughter nuclei 206,208Rn. Weak α transitions into excited levels of the odd-A daughter nuclei 205,207Rn were also observed.
Received: 19 August 2002 / Accepted: 6 November 2002 / Published online: 18 February 2003
RID="a"
ID="a"e-mail: f.p.hessberger@gsi.de
Communicated by D. Guerreau 相似文献
7.
D. Chauvat J. Guéna P. Jacquier M. Lintz M.A. Bouchiat 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(2):169-176
While all Atomic Parity Violation experiments on highly forbidden transitions in a Stark field have used the detection of
fluorescence signals, our group is engaged in an experiment on the cesium transition that uses a pump-probe scheme. The role of the probe beam is to detect the 7S state by stimulated emission.
The detected Left-Right asymmetry () appears directly on the transmitted probe beam and the technique relies on differential-mode atomic polarimetry. We present
here experimental results which illustrate two essential features of this approach. First, is amplified when the optical thickness for the probe beam is increased, hence it is an increasing function of the Stark
field. Secondly, the experimental sensitivity to is simultaneously increase
d, as demonstrated by our measurements of the signal-to-noise ratio. We emphasize also the advantage of choosing a probe transition
that involves a “dark” state: the amplification is preserved at high levels of the probe intensity because saturation effects are greatly reduced.
Received: 8 october 1997 / Accepted: 21 November 1997 相似文献
8.
E. E. Eyler D. E. Chieda M. C. Stowe M. J. Thorpe T. R. Schibli J. Ye 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(1):43-55
We analyze several possibilities for precisely measuring electronic transitions in
atomic helium by the direct use of phase-stabilized femtosecond frequency combs. Because the comb
is self-calibrating and can be shifted into the ultraviolet spectral region via harmonic
generation, it offers the prospect of greatly improved accuracy for UV and far-UV transitions. To
take advantage of this accuracy an ultracold helium sample is needed. For measurements of the
triplet spectrum a magneto-optical trap (MOT) can be used to cool and trap metastable 23S
state atoms. We analyze schemes for measuring the two-photon 23S →43S interval, and for resonant two-photon excitation to high Rydberg states, 23S →33P →n3S, D. We also analyze experiments on the singlet-state spectrum. To accomplish this we propose schemes for producing and trapping
ultracold helium in the 11S or 21S state via intercombination transitions. A particularly intriguing scenario is the possibility of measuring the 11S →21S transition with extremely high accuracy by use of two-photon excitation in a magic wavelength trap that operates identically
for both states. We predict a “triple magic wavelength” at 412 nm that could facilitate numerous experiments on trapped helium
atoms, because here the polarizabilities of the 11S, 21S and 23S states are all similar, small, and positive. 相似文献
9.
A. Ghoshal P. Mandal 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(2):327-335
e+ + H(ns) ↦e+ + H(n′s) transitions for arbitrary n and
n′ have been studied using the distorted-wave formalism in the
momentum space [Ghoshal and Mandal, Phys. Rev. A 72, 032714 (2005)]. The distorted-wave
scattering amplitudes have been written in a simple closed analytical form. A detailed
study has been made on differential and total cross sections in the energy range 20–300 eV.
Resonance-like behaviour of the
differential cross section has been observed in the the region of lower scattering angles
for high Rydberg transitions. To the best of our knowledge the distorted-wave results for
differential and total cross sections for such arbitrary transitions are reported for the
first time in the literature. 相似文献
10.
《The European Physical Journal A - Hadrons and Nuclei》2008,35(3):291-293
In photoproduction experiments, a large number of final states yielding various resonance contributions are accessible. To
extract resonance parameters via partial-wave analysis not only the measurement of differential cross-sections is necessary,
but also the determination of polarization observables. At the electron accelerator ELSA (Bonn) the coherent bremsstrahlung
method was used to generate a linearly polarized photon beam. Using the CBELSA/TAPS detector setup, the beam asymmetry Σ in
the reaction γp → pπ0η was determined as a function of various masses and angles for photon energies between 970MeV and 1650MeV. 相似文献
11.
H. Guyot J. Dumas M. V. Kartsovnik J. Marcus C. Schlenker I. Sheikin D. Vignolles 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,58(1):25-30
The purple molybdenum bronze KMo6O17 is a quasi-two-dimensional
compound which shows a Peierls transition towards a commensurate metallic
charge density wave (CDW) state. High magnetic field measurements have
revealed several transitions at low temperature and have provided an unusual
phase diagram “temperature-magnetic field”. Angular studies of the
interlayer magnetoresistance are now reported. The results suggest that the
orbital coupling of the magnetic field to the CDW is the most likely
mechanism for the field induced transitions. The angular dependence of the
magnetoresistance is discussed on the basis of a warped quasi-cylindrical
Fermi surface and provides information on the geometry of the Fermi surface
in the low temperature density wave state. 相似文献
12.
Ch. Schlegel P. von Neumann-Cosel J. de Boer J. Gerl M. Kaspar I. Kozhoukharov M. Loewe H.J. Maier P.J. Napiorkowsky I. Peter M. Rejmund A. Richter H. Schaffner J. Srebrny M. Würkner H.J. Wollersheim 《The European Physical Journal A - Hadrons and Nuclei》2001,10(2):135-138
In-beam Coulomb excitation of the exotic odd-odd nucleus 180Ta has been studied by using a 136Xe beam and a setup consisting of five EUROBALL CLUSTER detectors and the Darmstadt-Heidelberg Crystal Ball array. Spectroscopic
information on the extremely rare 180Ta is obtained from the comparison between an enriched (3.6±0.3% 180Ta) and a natural tantalum target. Possible evidence for a depopulation from the long-lived high-spin J
π = 9- isomer to the short-lived J
π = 1+ ground state is searched for by different methods. The decay of low-K bandheads, which are nanosecond isomers, towards the ground-state band can be demonstrated in delayed spectroscopy. A γγ
coincidence analysis provides indications of K = 5 in-band transitions. Finally, when the Crystal Ball is used as an energy and γ multiplicity filter, signals of decay
into the K = 0 band are observed.
Received: 23 January 2001 / Accepted: 8 February 2001 相似文献
13.
J. Gautier P. Zeitoun C. Hauri A.-S. Morlens G. Rey C. Valentin E. Papalarazou J.-P. Goddet S. Sebban F. Burgy P. Mercère M. Idir G. Dovillaire X. Levecq S. Bucourt M. Fajardo H. Merdji J.-P. Caumes 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(3):459-463
We present a full optimization of the high harmonics wave front owing to the
use of a soft X-ray Hartmann sensor. The sensor was calibrated using a high
harmonic source with an accuracy of λ/50 root-mean-square (rms)
with λ around 30 nm. We observed a high harmonic wave front of
λ/7 rms, which is two times the diffraction-limit, astigmatism
being the dominant aberration for every condition of generation. By clipping
slightly the unfocused high harmonic beam, it is possible to produce a
diffraction-limited beam containing approximately 90% of the incident
energy. 相似文献
14.
B. Friman W. Nörenberg V.D. Toneev 《The European Physical Journal A - Hadrons and Nuclei》1998,3(2):165-170
We compute the modification of the quark condensate <ˉq q> in relativistic nucleus-nucleus collisions and estimate the 4-volume,
where the quark condensate is small (<ˉqq>/<ˉqq>0≤ 0.1–0.3) using hadron phase-space distributions obtained with the quark-gluon string model. As a function of the beam energy
the 4-volume rises sharply at a beam energy Elab/A ≃ (2–5) GeV, remains roughly constant up to beam energies ≃ 20 GeV and rises at higher energies. At low energies the reduction
of the condensate is mainly due to baryons, while at higher energies the rise of the 4-volume is due to the abundant mesons
produced. Based on our results we expect that moderate beam energies on the order of 10 GeV per nucleon are favourable for
studying the restoration of chiral symmetry in a baryon-rich environment in nucleus-nucleus collisions.
Received: 4 December 1997 / Revised version: 31 July 1998 相似文献
15.
F.G. Mitri 《Annals of Physics》2008,323(11):2840-2850
The exact analytical solution for the scattering of a generalized (or “hollow”) acoustic Bessel beam in water by an elastic sphere centered on the beam is presented. The far-field acoustic scattering field is expressed as a partial wave series involving the scattering angle relative to the beam axis and the half-conical angle of the wave vector components of the generalized Bessel beam. The sphere is assumed to have isotropic elastic material properties so that the nth partial wave amplitude for plane wave scattering is proportional to a known partial-wave coefficient. The transverse acoustic scattering field is investigated versus the dimensionless parameter ka(k is the wave vector, a radius of the sphere) as well as the polar angle θ for a specific dimensionless frequency and half-cone angle β. For higher-order generalized beams, the acoustic scattering vanishes in the backward (θ = π) and forward (θ = 0) directions along the beam axis. Moreover it is possible to suppress the excitation of certain resonances of an elastic sphere by appropriate selection of the generalized Bessel beam parameters. 相似文献
16.
C. Andreoiu D. Rudolph I. Ragnarsson C. Fahlander R.A.E. Austin M.P. Carpenter R.M. Clark J. Ekman R.V.F. Janssens T.L. Khoo F.G. Kondev T. Lauritsen T. Rodinger D.G. Sarantites D. Seweryniak T. Steinhardt C.E. Svensson O. Thelen J.C. Waddington 《The European Physical Journal A - Hadrons and Nuclei》2002,14(3):317-348
High-spin states in 59Cu were populated using the fusion-evaporation reaction 28Si + 40Ca at a beam energy of 122 MeV. The Gammasphere Ge-detector array in conjunction with the 4π charged-particle detector array
Microball allowed for the detection of γ-rays in coincidence with evaporated light particles. The resulting extensive high-spin
decay scheme of 59Cu is presented, which comprises more than 320 γ-ray transitions connecting about 150 excited states. Their spins and parities
have been assigned via directional correlations of γ-rays emitted from oriented states. Average quadrupole moments of rotational
bands have been determined from the analysis of residual Doppler shifts. Shell model calculations in the fp shell are invoked to study some of the low-spin states, while the experimental characteristics of the rotational bands are
analyzed in the configuration-dependent cranked Nilsson-Strutinsky (CNS) approach.
Received: 15 February 2002 / Accepted: 23 April 2002 相似文献
17.
R.?Wilfinger J.?Lettry the EURISOL?Task Workgroup 《The European physical journal. Special topics》2007,150(1):379-382
EURISOL foil-targets have to withstand a primary proton
beam of 1 GeV kinetic energy and up to 100 μA
beam current. These foil targets will be based on previous
high-power target concepts, i.e. the RIST target [J.R.J. Bennett et al.,
Nucl. Instrum. Meth. Phys. Res. B 126, 117 (1997)]
or high power targets used at
TRIUMF [P. Bricault et al.,
Nucl. Instrum. Meth. Phys. Res. B 204, 319 (2003), M. Dombsky et al.,
Nucl. Instrum. Meth. Phys. Res. B 204, 191 (2003)].
A single target unit is capable of dissipating up to 25 kW,
hence, several target units can be merged together by individual
transfer lines to one common ion source. The single target units
will be irradiated by a proton beam in a time sharing mode to
distribute the primary proton beam current to the individual
target units. In this feasibility study the necessary properties
of high-power foil targets are discussed and the requirements to
design a foil target according to the proton beam parameters
[CITE] for the future EURISOL facility
are given. 相似文献
18.
《The European Physical Journal A - Hadrons and Nuclei》2007,33(2):147-155
The beam asymmetry, Σ , was measured at ELSA in the reaction
p → ηp using linearly polarised tagged photon beams, produced by coherent bremsstrahlung off a diamond. The crystal was oriented
to provide polarised photons in the energy range E
γ = 800 to 1400MeV with the maximum polarisation of P
γ = 49 % obtained at 1305MeV. Both dominant decay modes of the η into two photons and 3π0 were used to extract the beam asymmetry from the azimuthal modulation of the cross-section. The measurements cover the angular
range Θcm ≃ 50 -150 degrees. Large asymmetries up to 80% are observed, in agreement with a previous measurement. The eta-MAID model
and the Bonn-Gatchina partial wave analysis describe the measurements, but the required partial waves differ significantly. 相似文献
19.
D.H.E. Gross E.V. Votyakov 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,15(1):115-126
Traditionally, phase transitions are defined in the thermodynamic limit only. We discuss how phase transitions of first order
(with phase separation and surface tension), continuous transitions and (multi)-critical points can be seen and classified
for small systems. “Small” systems are systems where the linear dimension is of the characteristic range of the interaction
between the particles; i.e. also astrophysical systems are “small” in this sense. Boltzmann defines the entropy as the logarithm of the area of the surface in the mechanical N-body phase space at total energy E. The topology of S(E,N) or more precisely, of the curvature determinant allows the classification of phase transitions without taking the thermodynamic limit. Micro-canonical thermo-statistics
and phase transitions will be discussed here for a system coupled by short range forces in another situation where entropy
is not extensive. The first calculation of the entire entropy surface S(E,N) for the diluted Potts model (ordinary (q=3)-Potts model plus vacancies) on a square lattice is shown. The regions in {E,N} where D>0 correspond to pure phases, ordered resp. disordered, and D<0 represent transitions of first order with phase separation and “surface tension”. These regions are bordered by a line
with D=0. A line of continuous transitions starts at the critical point of the ordinary (q=3)-Potts model and runs down to a branching point Pm. Along this line vanishes in the direction of the eigenvector of D with the largest eigen-value . It characterizes a maximum of the largest eigenvalue . This corresponds to a critical line where the transition is continuous and the surface tension disappears. Here the neighboring
phases are indistinguishable. The region where two or more lines with D=0 cross is the region of the (multi)-critical point. The micro-canonical ensemble allows to put these phenomena entirely
on the level of mechanics.
Received 18 October 1999 and received in final form 17 November 1999 相似文献
20.
R. Peeters G. Berden A. Apituley G. Meijer 《Applied physics. B, Lasers and optics》2000,71(2):231-236
A compact open-path optical ammonia detector is developed. A tunable external-cavity diode laser operating at 1.5 μm is used
to probe absorptions of ammonia via the cavity-enhanced absorption (CEA) technique. The detector is tested in a climate chamber.
The sensitivity and linearity of this system are studied for ammonia and water at atmospheric pressure. A cluster of closely
spaced rovibrational overtone and combination band transitions, observed as one broad absorption feature, is used for the
detection of ammonia. On these molecular transitions a detection limit of 100 ppb (1 s) is determined. The ammonia measurements
are calibrated independently with a chemiluminescence monitor. Compared to other optical open-path detection methods in the
1–2 μm region, the present result shows an improved sensitivity for contactless ammonia detection by over one order of magnitude.
Using the same set-up, a detection limit of 100 ppm (1 s) is determined for the detection of water at atmospheric pressure.
Received: 19 January 2000 / Revised version: 6 March 2000 / Published online: 7 June 2000 相似文献