studying a strontium mot – group meeting 01-12-08 studying a strontium mot james millen
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Theory
689nm
7.6kHz
Up to
13mins*
*Yasuda, Katori
Phys. Rev. Lett. 92, 153004 (2004)
(5s2) 1S0
461nm
32MHz
(5s5p) 1P1
620Hz
(5s4d) 1D2
0.33
(105Hz)
(5s5p) 3P2
0.67
(213Hz)
3P1
679nm
(1.4MHz)707nm
(6.4MHz)
(5s6s) 3S0
3P07.6kHz
Studying a strontium MOT – group meeting 01-12-08
Studying a strontium MOT – group meeting 01-12-08
Using the photodiode
• One nW of light corresponds to (27.8±0.2)mV of signal
• The photodiode “sees” a solid angle Ω of the emitted light
• Each atom scatters R photons
• Each atom emits a power
• Hence there are NA atoms
Atom number experimental sequence
Controlled by LabView via FPGA cardMOT beams always on
A) B-field & slowing
light off
B) Slowing light on
C) B-field and slowing
light on
D) B-field on, slowing
light off
E) B-field & slowing
light off
Studying a strontium MOT – group meeting 01-12-08
MOT atom number
Rydberg & plasma physics using ultra-cold strontiumStrontium MOT
• Isat corresponds to 19mW of MOT beam power
Some preliminary results – MOT lifetime
Rydberg & plasma physics using ultra-cold strontiumStrontium MOT
Black line I = Ipeak Blue line I = Iaverage Green line I = αIpeak
Studying a strontium MOT – group meeting 01-12-08
Using the camera
• We use a pco. pixelfly qe CCD camera, with 1392x1024 pixels
• It has an internal shutter that shutters in about 8μs
• Each pixel is 6.45μm2, and we use a 1:1 magnification
• Calculated counts per pixel per photon μ = 0.132
• Allows us to calculate atom number, but also MOT size
Time of flight measurement
Studying a strontium MOT – group meeting 01-12-08
• Create a MOT, let it go, and after some variable time image it and record its width.
• Assume Gaussian cloud shape and velocity distribution
T = 5.9±0.5mK(Doppler limit 4.8mK)
Release and recapture
A) MOT and slower light on (molasses)
B) MOT coils on(MOT fills)
C) Slower light off(8ms)
D) MOT light off
E) MOT light back on
Studying a strontium MOT – group meeting 01-12-08
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