Determining Detector Voltages when no previous data is accessible
Issue
An issue has occurred such as hard drive failure where no recent performance reports or LabBooks are accessible in order to determine the detector voltages in use prior to the failure
Environment
- iCAP Q
- iCAP RQ
- iCAP TQ
- ECCN: EAR99
Resolution
1. Raise the voltages to a point where you think you can attempt a mass calibration.
2. Run course mass calibration. If ArAr peak is resolved, note the intensity. If it is significantly higher than 5Mcps, adjust the voltages down and re-run mass course mass calibration until intensity is between 5-10Mcps. If no peak is resolved at all, increase voltages and reattempt course mass calibration.
3. Once mass calibration has passed, adjust detector voltages until reasonable counts are observed for Setup/Calibration solution elements, i.e. >200k for Lithium and >1Mcps for Uranium.
4. Run cross calibration and note factor for one of the mid-masses in the range of mass 109 - 140. Ideally the factor should be close to 100,000. If the factory is too low (i.e. 10,000), decrease analog voltage and/or increase counting voltage until the factor is closer to 100,000. Is doesn't have to be within +/- 10% for example but if is can get to 60-140k, the detector voltages should be good enough to run with for a HV setup
5. Note the Analog and Counting voltages
Analysis
One of the most difficult thing to do when no previous data is recoverable is determine the detector voltages. Even if the persistent data folder is accessible on Intenso drive the detector voltages have changed significantly since the time these parameters were stored there. The cross calibration factor can be used as a gauge to rough in the detector voltages to a point where a good starting point can be determined in order to run a HV setup