UC Berkeley, Geology & Geophysics
Cameca SX51 Microprobe
I have completed the final specification testing on the instrument and the last few outstanding items have been cleared up to my satisfaction. These were:
1d. Averaged filament life. Data for filament usage was recorded over a period of 1 year and was less than 300 hours for 10 filaments. In negotiations with Sam Pindrys we have agreed to accept a compensation of 32 filaments (16 already received) for failure to meet this specification. Sam Pindrys has stated to me that reducing the emission from 70 to 60 uA will improve the average filament life to over 700 hours. He has promised that if we do not experience such an improvement after another year, he will supply another 28 filaments for free.
3i. Count rates. It has been noted that the LiF count rates are marginal. This appears to be due to the use of Ar as a flow gas for all detectors including the high energy LiF spectrometers. Due to the less efficient absorption of Ar (compared to Xe for example), we calculate a 50% drop in count rates at Zn ka energies.
We suggest that Cameca investigate the use of stronger windows and higher pressures to improve count rates for high energy x-rays.
4a. Resolution test. Images at 70 angstroms at 20 kev using SE image on Au test sample were finally obtained. This test was completed due to the superb efforts of Edgar Chavez who found a tight cable against the stage housing that caused large vibrations in the imaging system.
8b. Stage reproducibility to 1 micron. This specification can now be meet due to the use of a task routine which reduces the stage speed by about 10%. Edgar Chavez again supplied this information and we accept it in lieu of a modified EPROM.
Therefore, we fully accept the instrument. Please begin the extended warranty for full coverage of the spectrometer and stage mechanisms for 2 years as stated in specification (I) 3, as of June 5th, 1997. If there are any questions about these results please contact me at the address below. Thanks.
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