Measurement of absolute photo-ionization cross sections using magnesium magneto-optical traps

Madsen, Dorte; Thomsen, J.

doi:10.1088/0953-4075/35/9/314

Cited by 23 publications

(20 citation statements)

References 24 publications

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“…and we can focus on solving the radial equation hl,j u l,j (r) = ε l,j u l,j (r), u l,j (0) = 0, (7) hl,j = − 1 2…”

Section: A One-particle Hamiltonianmentioning

confidence: 99%

“…This makes the 3 P o manifold in the alkaline-earth-metal atoms interesting for several applications in the physics of cold atoms. The unique level structure triggered advances in laser-cooling technology and allowed to explore processes in a magneto-optical trap at a new level [3,4,5,6,7,8,9,10]. Current successful approaches to an optical frequency standard using neutral, laser-cooled atoms are based on the relatively small linewidth of the 1 S 0 → 3 P o 1 transition in calcium [11,12,13].…”

Section: Introductionmentioning

confidence: 99%

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Properties of metastable alkaline-earth-metal atoms calculated using an accurate effective core potential

2004

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The first three electronically excited states in the alkaline-earth-metal atoms magnesium, calcium, and strontium comprise the (nsnp) 3 P o J (J = 0, 1, 2) fine-structure manifold. All three states are metastable and are of interest for optical atomic clocks as well as for cold-collision physics. An efficient technique-based on a physically motivated potential that models the presence of the ionic core-is employed to solve the Schrödinger equation for the two-electron valence shell. In this way, radiative lifetimes, laser-induced clock shifts, and long-range interaction parameters are calculated for metastable Mg, Ca, and Sr.

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“…and we can focus on solving the radial equation hl,j u l,j (r) = ε l,j u l,j (r), u l,j (0) = 0, (7) hl,j = − 1 2…”

Section: A One-particle Hamiltonianmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Properties of metastable alkaline-earth-metal atoms calculated using an accurate effective core potential

2004

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“…These measurements involve collisions of trapped neutral particles with neutral atoms and molecules [20][21][22][23][24], electron beams [25][26][27], and trapped ions [28][29][30]. Photoionization cross sections have also been investigated though measurements of trap loss rates [31][32][33]. It has been shown for atoms exposed to background gas [34] and for molecules exposed * madison@phas.ubc.ca to supersonic beams of atoms and molecules [23,24] that inelastic, and particularly elastic, collisional cross sections for trap loss vary significantly with trap depth.…”

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confidence: 99%

Trap-depth determination from residual gas collisions

et al. 2011

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We present a method for determining the depth of an atomic or molecular trap of any type. This method relies on a measurement of the trap loss rate induced by collisions with background gas particles. Given a fixed gas composition, the loss rate uniquely determines the trap depth. Because of the "soft" long-range nature of the van der Waals interaction, these collisions transfer kinetic energy to trapped particles across a broad range of energy scales, from room temperature to the microkelvin energy scale. The resulting loss rate therefore exhibits a significant variation over an enormous range of trap depths, making this technique a powerful diagnostic with a large dynamic range. We present trap depth measurements of a Rb magneto-optical trap using this method and a different technique that relies on measurements of loss rates during optical excitation of colliding atoms to a repulsive molecular state. The main advantage of the method presented here is its large dynamic range and applicability to traps of any type requiring only knowledge of the background gas density and the interaction potential between the trapped and background gas particles.The particle loss rate from a trap is one of the primary observables for probing the collisional physics of trapped gases. Measurements of trap loss are routinely made in a variety of experiments to deduce elastic and inelastic collision cross sections for intratrap collisions and for collisions between trapped species and externally introduced particles. Trap depth often plays an important role in the interpretation of these measurements. A well-studied example of this is the large intensity-dependent variation displayed by the two-body intratrap loss-rate coefficient for atoms trapped in a magnetooptical trap (MOT). This variation results from an interplay of trap depth and the energy imparted to trapped atoms due to hyperfine or fine structure changing collisions, as well as radiative escape [1][2][3][4][5][6][7][8][9][10][11][12]. More recently, inelastic and elastic collision rates in dipole traps have been of interest, particularly for metastable species [13,14]. The fraction of elastic collisions resulting in an evaporated atom depends on trap depth, which is a key parameter for evaporative cooling [13,15,16]. The lifetime dependence of a state-insenstive dipole trap on trap depth for cesium atoms has also recently been investigated [17]. Of course the most fundamental role of trap depth is that it be large enough to provide sufficient confinement, which has been an issue for experiments with buffer-gas-cooled atoms or molecules [18,19].In recent years there has been interest in making precision determinations of collision cross-sections from measurements of particle loss rates due to externally introduced particles. These measurements involve collisions of trapped neutral particles with neutral atoms and molecules [20][21][22][23][24], electron beams [25][26][27], and trapped ions [28][29][30]. Photoionization cross sections have also been investigated though mea...

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“…Note that the magnetic trap lifetime 1= 2 is generally different from the MOT lifetime 1= 0 since additional two photon ionization losses are taking place in the MOT [19]. The solution to Eq.…”

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confidence: 99%

Experimental Determination of theMg24I(3s3p)P2<

Jensen¹,

He²,

Westergaard³

et al. 2011

Phys. Rev. Lett.

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We present the first experimental determination of the electric-dipole forbidden (3s3p)³P₂→(3s²)¹S₀ (M2) transition rate in ²⁴Mg and compare to state-of-the-art theoretical predictions. Our measurement exploits a magnetic trap isolating the sample from perturbations and a magneto-optical trap as an amplifier converting each ³P₂→¹S₀ decay event into millions of photons readily detected. The transition rate is determined to be (4.87 ± 0.3)×10⁻⁴ s⁻¹ corresponding to a ³P₂ lifetime of 2050(-110)(+140) sec. This value is in agreement with recent theoretical predictions, and to our knowledge the longest lifetime ever determined in a laboratory environment.

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Measurement of absolute photo-ionization cross sections using magnesium magneto-optical traps

Cited by 23 publications

References 24 publications

Properties of metastable alkaline-earth-metal atoms calculated using an accurate effective core potential

Properties of metastable alkaline-earth-metal atoms calculated using an accurate effective core potential

Trap-depth determination from residual gas collisions

Experimental Determination of theMg24I(3s3p)P2<

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