Using a Quartz Crystal Oscillator as a Deposition Monitor
-Robert Wild
Problem
-What is the efficiency of the detector? Is it worth trying to improve the detector efficiency to get a larger atom count rate?
Solution
-Get an independent measurement of beam flux
-Deposit atoms onto a quartz crystal oscillator
-Calculate the mass deposited from the change in frequency
-Extrapolate the flux to the detector position
-Compare to the measured flux for the efficiency
Result
The detector has an efficiency of about 3 to 4 %
Data of Crystal in and out of beam
Crystal Frequency Change
Data taken over longer time range
Crystal Frequency Change
Diagram of the beam profile at detector
Calculation of deposited mass
Flux ratios from crystal to detector
Efficiency
Future Goals
-Improve the efficiency of detector
-Possible methods
-cleaning the wire
-ion optics (focusing the ions using a
magnetic field)
-making sure CEM works properly