3 he cell production at nist m. jon dadras. outline basics of a 3 he cells basics of a 3 he cells...
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33He cell production at NISTHe cell production at NIST
M. Jon DadrasM. Jon Dadras
OutlineOutlineBasics of a Basics of a 33He cellsHe cellsBlowing/BakingBlowing/BakingFillingFillingUsesUsesOur new station at SNSOur new station at SNS
Blowing, Baking, & DistillingBlowing, Baking, & Distilling
GE180 glass (no boron)GE180 glass (no boron)Tubing is baked along with cell for Tubing is baked along with cell for
sterilizationsterilizationHow cool is the oven?How cool is the oven?
Baking after DistillationBaking after Distillation
Putting the metals in the cellPutting the metals in the cell
Measuring K vs Rb ratioMeasuring K vs Rb ratio
Final CutFinal Cut
Schematic of Filling StationSchematic of Filling Station
Optical Set-upOptical Set-up
Helmholtz CoilsHelmholtz Coils
NMR-FIDNMR-FID
ijkB )sin()cos(0 tBtBB
kjB )/( 0 BBr
NMR
Use a solenoid for holding field
Send RF pulse
Pick-up coil is same as RF coil
Results: K-cell, 400 hrs, ratio = 45, w. K Laser, P = 75%
How is How is 33He PolarizedHe Polarized Circularly polarized light impinges on an alkali-Circularly polarized light impinges on an alkali-
metal (Rb) resonant with gs metal (Rb) resonant with gs 1 1stst exc. transition exc. transition Light spin-polarizes the electronsLight spin-polarizes the electrons Spin-exchange occurs through binary collisionsSpin-exchange occurs through binary collisions
Meaning there’s a spin-spin interaction between the Meaning there’s a spin-spin interaction between the nucleus of the noble gas (nucleus of the noble gas (33He) and the spin-polarized He) and the spin-polarized electronelectron
Courtesy of 3
How to Perform the MeasurementHow to Perform the Measurement
Empty cell transmissionEmpty cell transmission Filled cell Filled cell P=0, T=eP=0, T=e--σσndnd
Finally we use AFP-NMR to Finally we use AFP-NMR to monitor the monitor the 33He polarizationHe polarization What is AFP-NMR?What is AFP-NMR?
n + 3He p + 3H