Studying a strontium MOT – group meeting 01-12-08 Studying a strontium MOT James Millen.

Studying a strontium MOT – group meeting 01-12-08

Studying a strontium MOT

James Millen

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

MOT atom number

Rydberg & plasma physics using ultra-cold strontiumStrontium MOT

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

Studying a strontium MOT – group meeting 01-12-08

Example

∑C = μ ∑ Nγ

Studying a strontium MOT – group meeting 01-12-08

Number and density measurements

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

Release and recapture

Studying a strontium MOT – group meeting 01-12-08

To do

Studying a strontium MOT – group meeting 01-12-08

• Analyze more temperature data

• Investigate effect of intensity / detuning on temperature

• Get some decent density data

• Next: Turn on MCPMake some ionsMake some Rydbergs