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