12 research outputs found
Magneto-optical trap for metastable helium at 389 nm
We have constructed a magneto-optical trap (MOT) for metastable triplet
helium atoms utilizing the 2 3S1 -> 3 3P2 line at 389 nm as the trapping and
cooling transition. The far-red-detuned MOT (detuning Delta = -41 MHz)
typically contains few times 10^7 atoms at a relatively high (~10^9 cm^-3)
density, which is a consequence of the large momentum transfer per photon at
389 nm and a small two-body loss rate coefficient (2 * 10^-10 cm^3/s < beta <
1.0 * 10^-9 cm^3/s). The two-body loss rate is more than five times smaller
than in a MOT on the commonly used 2 3S1 -> 2 3P2 line at 1083 nm. Furthermore,
we measure a temperature of 0.46(1) mK, a factor 2.5 lower as compared to the
1083 nm case. Decreasing the detuning to Delta= -9 MHz results in a cloud
temperature as low as 0.25(1) mK, at small number of trapped atoms. The 389 nm
MOT exhibits small losses due to two-photon ionization, which have been
investigated as well.Comment: 11 page
Evaluatie van de Twinningfaciliteit Suriname-Nederland
De Twinningfaciliteit Suriname-Nederland (TF) is een subsidiefonds om de samenwerking tussen maatschappelijke organisaties uit Nederland en Suriname te bevorderen. Doel van deze evaluatie van de Inspectie Ontwikkelingssamenwerking en Beleidsevaluatie was na te gaan welke resultaten met de gefinancierde projecten zijn behaald en of deze hebben bijgedragen aan de beoogde doelstellingen