共查询到20条相似文献,搜索用时 32 毫秒
1.
A continuous cold atomic beam from a magneto-optical trap 总被引:3,自引:0,他引:3
L. Cacciapuoti A. Castrillo M. de Angelis G.M. Tino 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(2):245-249
We have developed and characterized a new method to produce a continuous beam of cold atoms from a standard vapour-cell magneto-optical
trap (MOT). The experimental apparatus is very simple. Using a single laser beam it is possible to hollow out in the source
MOT a direction of unbalanced radiation pressure along which cold atoms can be accelerated out of the trap. The transverse
cooling process that takes place during the extraction reduces the beam divergence. The atomic beam is used to load a magneto-optical
trap operating in an ultra-high vacuum environment. At a vapour pressure of 10-8mbar in the loading cell, we have produced a continuous flux of 7×107atoms/s at the recapture cell with a mean velocity of 14 m/s. A comparison of this method with a pulsed transfer scheme is
presented.
Received 19 February 2001 相似文献
2.
An atom faucet 总被引:3,自引:0,他引:3
W. Wohlleben F. Chevy K. Madison J. Dalibard 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(2):237-244
We present a simple and efficient source of slow atoms. From a background vapour loaded magneto-optical trap (MOT), a thin
laser beam extracts a continuous jet of cold rubidium atoms. The jet that is typical to leaking MOT systems is created without
any optical parts placed inside the vacuum chamber. We also present a simple three dimensional numerical simulation of the
atomic motion in the presence of these multiple saturating laser fields combined with the inhomogeneous magnetic field of
the MOT. At a pressure of P
Rb87 = 10-8 mbar and with a moderate laser power of 10 mW per beam, we generate a flux Φ = 1.3×108 atoms/s with a mean velocity of 14 m/s and a divergence of 10 mrad.
Received 13 January 2001 相似文献
3.
P. Cren C.F. Roos A. Aclan J. Dalibard D. Guéry-Odelin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(1):107-116
We demonstrate experimentally the continuous and pulsed loading of a slow and cold atomic beam into a magnetic guide. The
slow beam is produced using a vapor loaded laser trap, which ensures two-dimensional magneto-optical trapping, as well as
cooling by a moving molasses along the third direction. It provides a continuous flux larger than 109 atoms/s with an adjustable mean velocity ranging from 0.3 to 3 m/s, and with longitudinal and transverse temperatures smaller
than 100 μK. Up to 3×108 atoms/s are injected into the magnetic guide and subsequently guided over a distance of 40 cm.
Received 19 February 2002 Published online 28 June 2002 相似文献
4.
M. D. Hoogerland J. P. J. Driessen E. J. D. Vredenbregt H. J. L. Megens M. P. Schuwer H. C. W. Beijerinck K. A. H. van Leeuwen 《Applied physics. B, Lasers and optics》1996,62(4):323-327
Using a three-step transverse laser cooling scheme, a strongly diverging flow of metastable Ne(3s
3
P
2] atoms is compressed into a well-collimated, small diameter atomic beam (e.g., 1.4 mrad HWHM divergence at 3.6 mm beam diameter) with an unmodified axial velocity distribution centered at 580 m/s. The maximum increase in beam flux 1.04 m downstream of the source is a factor 1400; the maximum increase in phase space density, i.e., brightness, is a factor 160. The laser power used is only 140 mW. The scheme is extendable to a large variety of atomic species and enables the application of bright atomic beams in many areas of physics. 相似文献
5.
高强度的亚稳态惰性原子束流在原子分子物理实验研究中具有广泛的应用.使用射频电离方法和激光横向冷却技术制备了高强度的亚稳态氪原子束流,并使用数值模拟方法对横向冷却激光场中的原子径迹进行了分析.通过激光诱导荧光光谱方法测量原子束的束流特性,结果显示,横向冷却后在束流源下游230 cm处的原子束流强度达1.6atoms/(s*sr),束流强度提高了两个量级.利用这种高强度原子束流,我们成功囚禁了1.3×1010个亚稳态84Kr原子,同时冷原子装载速率达到了3.0×1011atoms/s;并利用该装置成功地实现了高亮度的亚稳态氩原子束和原子阱.
关键词:
横向冷却
原子束
原子阱
惰性气体 相似文献
6.
F. Pereira Dos Santos F. Perales J. Léonard A. Sinatra Junmin Wang F. Saverio Pavone E. Rasel C.S. Unnikrishnan M. Leduc 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(1):15-22
We present experimental results on the two-body loss rates in a magneto-optical trap of metastable helium atoms. Absolute
rates are measured in a systematic way for several laser detunings ranging from -5 to -30 MHz and at different intensities,
by monitoring the decay of the trap fluorescence. The dependence of the two-body loss rate coefficient β on the excited state
( 23
P
2) and metastable state ( 23
S
1) populations is also investigated. From these results we infer a rather uniform rate constant K
sp = (1±0.4)×10-7 cm3/s.
Received 8 September 2000 and Received in final form 19 December 2000 相似文献
7.
G. Stancari S. N. Atutov R. Calabrese L. Corradi A. Dainelli C. de Mauro A. Khanbekyan E. Mariotti P. Minguzzi L. Moi S. Sanguinetti L. Tomassetti S. Veronesi 《The European physical journal. Special topics》2007,150(1):389-392
Francium is one of the best candidates for atomic parity
nonconservation (APNC) and for the search of permanent electric
dipole moments (EDMs). APNC measurements test the weak force
between electrons and nucleons at very low momentum transfers. They
also represent a unique way to detect weak nucleon-nucleon
interactions. EDMs are instead related to the time-reversal
symmetry. Preliminary to these fundamental measurements are
precision studies in atomic spectroscopy and the development of
magneto-optical traps (MOT), which partially compensate for the lack
of stable Fr isotopes. At LNL Legnaro, francium is produced by
fusion of 100-MeV 18O with 197Au in a thick target,
followed by evaporation of neutrons from the compound nucleus.
Francium diffuses inside the hot target (1200 K) and is surface
ionized for injection at 3 keV in an electrostatic beamline.
Typically, we produce 1×106 (210Fr ions)/s for a
primary flux of 1.5×1012 particles/s. We have studied
Fr yields as a function of primary beam energy, intensity, and
target temperature. Information on the efficiency of bulk
diffusion, surface desorption and ionization is deduced. The beam
then enters a Dryfilm-coated cell, where it is neutralized on a
heated yttrium plate. The escape time of neutral Fr (diffusion +
desorption) is approximately 20 s at 950 K, as measured with a
dedicated setup. In the MOT, we use 6 orthogonal Ti:sapphire laser
beams for the main pumping transition and 6 beams from a stabilized
diode repumper. Fluorescence from trapped atoms is observed with a
cooled CCD camera, in order to reach noise levels from stray
light equivalent to approximately 50 atoms. Systematic tests are
being done to improve the trapping efficiency. We plan to further
develop Fr traps at LNL; in parallel, we will study APNC and EDM
techniques and systematics with stable alkalis at Pisa, Siena, and
Ferrara. 相似文献
8.
V. Wippel C. Binder L. Windholz 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(1):101-104
In a magneto-optical trap (MOT) we are able to simultaneously trap and cool 7Li and Na. We investigated the loading behavior of the cloud of Li atoms in presence of the overlapped cloud of cold Na atoms,
and, by blocking the weak repumping beam for Na, compared it with the loading curve for Li atoms only. Out of these loading
curves we calculated the collision cross-section of Na on Li to be 10-11 cm
3
/s.
Received 11 January 2002 / Received in final form 5 April 2002 Published online 24 September 2002 相似文献
9.
We have established a caesium double magneto-optical trap (MOT) system for
cavity-QED experiment, and demonstrated the continuous transfer of cold caesium
atoms from the vapour-cell MOT with a pressure of ~ 1×10-6 Pa to
the ultra-high-vacuum (UHV) MOT with a pressure of ~ 8×10-8 Pa via a
focused continuous-wave transfer laser beam. The effect of frequency detuning as
well as the intensity of the transfer beam is systematically investigated, which
makes the transverse cooling adequate before the atoms leak out of the vapour-cell
MOT to reduce divergence of the cold atomic beam. The typical cold atomic flux got
from vapour-cell MOT is ~2×107 atoms/s. About 5×106
caesium atoms are recaptured in the UHV MOT. 相似文献
10.
We demonstrate an experimental setup for the production of a beam source of cold 87Rb atoms. The atoms are extracted from a trapped cold atomic cloud in an unbalanced three-dimensional magneto-optical trap. Via a radiation pressure difference generated by a specially designed leak tunnel along one trapping laser beam, the atoms are pushed out continuously with low velocities and a high flux. The most-probable velocity in the beam is varied from 9 m/s to 19 m/s by varying the detuning of the trapping laser beams in the magneto-optical trap and the flux can be tuned up to 4×109 s-1 by increasing the intensity of the trapping beams. We also present a simple model for describing the dependence of the beam performance on the magneto-optical trap trapping laser intensity and the detuning. 相似文献
11.
E. Rasel F. Pereira Dos Santos F. Saverio Pavone F. Perales C.S. Unnikrishnan M. Leduc 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(3):311-316
We report a study of transverse laser cooling on a metastable helium beam using spectrally broadened diode lasers (“white
light") to increase its flux. For this purpose, beam profile and atomic flux versus laser power and other parameters have been characterized. We have performed experiments to compare this technique with other
transverse cooling methods using monochromatic light. Best results are obtained with a “ziz-zag" configuration using “white
light".
Received 21 December 1998 and Received in final form 27 May 1999 相似文献
12.
Ch. Lisdat O. Dulieu H. Knöckel E. Tiemann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(3):319-328
We present a new determination of the potential curves and interactions of the coupled electronic states A
1
Σ
+
u
and b
3
Π
u
of the potassium dimer, based on new laser spectroscopy measurements within a molecular beam, combined with data available
in the literature. We used a new global deperturbation approach, involving the Fourier Grid Hamiltonian method for energy
level calculation. A standard deviation of 1.2 is obtained corresponding to a variance of 7.5×10
-3
cm-1, representing a significant improvement compared to the standard deviation of 4 yielded by the traditional local deperturbation
approach.
Received 12 June 2001 and Received in final form 3 September 2001 相似文献
13.
A. Gopalan J. Bömmels S. Götte A. Landwehr K. Franz M.-W. Ruf H. Hotop K. Bartschat 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(1):17-29
A novel electron scattering apparatus for high resolution studies of angle-differential elastic and inelastic electron scattering
from atoms and molecules in the gas phase is described and its performance characterized. It combines a laser photoelectron
source, a triply differentially pumped collimated supersonic beam target (half angle 0.015 rad, background to beam density
ratio < 0.01), and several electron multipliers for simultaneous detection of elastically scattered electrons and metastable atoms (or
molecules) due to inelastic scattering. In detailed test measurements of the yield for the production of metastable He*(23S1) atoms around its threshold, the dependence of the overall energy width on various experimental parameters has been investigated.
So far a resolution down to 7 meV (FWHM) has been obtained. Under such conditions we have investigated the profile of the
He- (1
s
2
s
2
2
S
1/2
) resonance at the scattering angles 22
°
, 45
°
, and 90
°
. From a consistent fit of the measured profiles by resonant scattering theory we determine a new value for the resonance
energy ( E
r
= 19.365(1) eV) and an accurate resonance width ( Γ = 11.2(5) meV). These results are consistent with the previously recommended values.
Received 23 July 2002 Published online 29 October 2002
RID="a"
ID="a"e-mail: hotop@physik.uni-kl.de
RID="b"
ID="b"Permanent address: Department of Physics and Astronomy, Drake University, Des Moines, IA 50311, USA. 相似文献
14.
L. Natarajan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(3):287-292
In this work, the multiplet splitting in terms of a spin-dependent model is analyzed. The spin-polarized and unpolarized single
configuration Dirac-Fock-Slater wavefunctions have been used in the evaluation of the total energies of highly ionized argon
with different L shell population The transition energies of hollow argon atom with initial configurations 1s
0
1/22s
m
1/22p
n
1/22p
l
3/2 with m = 0 to 2 and n + l varying from 6 to 1 are reported in this work. The calculations have been carried out by taking into account a relativistic
exchange potential in the Dirac-Slater potential. To account for the correlation effects, a correction term has also been
considered perturbatively. The present calculations show that the spin-polarized technique which is mainly applied to the
ground states of atoms may also be applied to atoms ionized in the inner shells with a good degree of accuracy.
Received 5 December 2000 and Received in final form 9 April 2001 相似文献
15.
M. Saleem N. Amin S. Hussain M. Rafiq S. Mahmood M. A. Baig 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(2):277-283
New measurements of photoionization cross-sections of the lithium isotopes
are reported employing a Time of Flight (TOF) mass spectrometer in
conjunction with an atomic beam apparatus. Using a two-step selective
photoionization and saturation technique, we have simultaneously measured
the photoionization cross-section of the 2p excited state of both the
isotopes Li6 and Li7 as 15±2.5 Mb and 18 ±2.5 Mb
where as the corresponding number densities have been determined as
N0≈5.3×1010 atoms/cm3 and
N0≈6.2×1011 atoms/cm3 respectively. 相似文献
16.
R. Jung S. Gerlach R. Schumann G. von Oppen U. Eichmann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(3):415-419
We report on the first successful loading of a magneto-optical trap (MOT) with metastable He atoms from a Stark-slower. Thereby,
deceleration of the atoms relies on laser-atom interaction in an inhomogeneous electric field. We show that the results obtained
are comparable with early results from other groups achieved with a Zeeman slower. The Stark slower, which is able to fully
control the final velocity of the atomic He beam, is the first step in achieving complete spin independent kinematic control
based solely on electric fields.
Received 2 October 2002 / Received in final form 20 January 2003 Published online 29 April 2003
RID="a"
ID="a"e-mail: eichmann@mbi-berlin.de 相似文献
17.
V. Wippel C. Binder W. Huber L. Windholz M. Allegrini F. Fuso E. Arimondo 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(3):285-291
A two element magneto-optical trap (MOT) for Na and 7Li or 6Li is used to cool and trap each of them separately. A fraction of the cold atoms is maintained in the first 2P3/2 excited state by the cooling laser. These excited state atoms are ionized by laser light in the near-UV region, giving rise
to a smaller number of trapped atoms and to different loading parameters. Photoionization cross-sections were derived out
of these data. They are in reasonable agreement with data previously obtained using thermal samples and with theoretical predictions.
Received 21 March 2001 and Received in final form 3 August 2001 相似文献
18.
D. Lucas P. Horak G. Grynberg 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(3):261-267
We study one-dimensional Sisyphus cooling on the transition of
87
Rb atoms in the electric field created by two counter-propagating linearly polarized laser beams with an angle of between the polarization directions. The neighbouring F
'=0 and F
'=2 excited states are found to play an important role in the cooling mechanism, e.g., by inhibiting a significant population of the velocity-selective dark state. Our experimental data, such as temperatures
and probe absorption coefficients, agree well with the results of quantum Monte-Carlo wavefunction simulations.
Received 26 November 1998 and Received in final form 20 April 1999 相似文献
19.
M. Lontano D. Ryutov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(3):347-351
We demonstrate the in situ detection of cold 87Rb atoms near a dielectric surface using the absorption of a weak, resonant evanescent wave. We have used this technique in
time of flight experiments determining the density of atoms falling on the surface. A quantitative understanding of the measured
curve was obtained using a detailed calculation of the evanescent intensity distribution. We have also used it to detect atoms
trapped near the surface in a standing-wave optical dipole potential. This trap was loaded by inelastic bouncing on a strong,
repulsive evanescent potential. We estimate that we trap 1.5×104 atoms at a density 100 times higher than the falling atoms.
Received 14 May 2002 Published online 8 October 2002
RID="a"
ID="a"e-mail: spreeuw@science.uva.nl 相似文献
20.
V. Milosavljević S. Djeniže 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(1):99-104
Characteristics of the Stark broadened and overlapping 447.1 nm He I spectral line and its forbidden 447.0 nm components have
been measured at electron densities between 4.4×1022 m-3 and 8.2×1022 m-3 and electron temperatures between 18 000 K and 33 000 K in plasmas created in five various discharge conditions using the
low pressure pulsed arc as an optically thin plasma source operated in helium-nitrogen-oxygen gas mixture. Good agreement
was found among our measured line characteristics and their existing calculated values, based on the quasistatic approximation.
Possible influence of the singly ionized oxygen impurity atoms (O II) on the intensity values of the dip between allowed and
forbidden components was found that can explain the disagreement among some existing experimental and calculated line characteristics
data, at higher electron temperatures and densities. On the basis of the observed asymmetry of the 447.1 nm spectral line
profile we have obtained the ion contribution parameter at 1022 m-3 electron density and 8 000 K electron temperature.
Received 20 February 2001 and Received in final form 25 April 2001 相似文献