Resolution control in X-ray fluorescence spectroscopy systems
An embodiment of a method for restoring detector resolution in an X-Ray fluorescence instrument is described that comprises: measuring a resolution value of a detector in the X-Ray fluorescence instrument using a standard material at a first temperature; determining that the measured resolution value deviates from a target value; and adjusting the temperature of the detector to a second temperature that restores the resolution value of the detector to the target value, wherein the temperature is adjusted by an amount defined by a relationship of temperature change to the degree of deviation of detector resolution from the target value.
1. A method for restoring detector resolution in an X-Ray fluorescence instrument, comprising:
measuring a resolution value of a detector in the X-Ray fluorescence instrument using a standard material at a first temperature;
determining that the measured resolution value deviates from a target value; and
adjusting the temperature of the detector to a second temperature that restores the resolution value of the detector to the target value, wherein the temperature is adjusted by an amount defined by a relationship of temperature change to the degree of deviation of detector resolution from the target value.
2. The method of claim 1 , wherein:
the target value comprises a value in a range of about 140 eV to about 200 eV.
3. The method of claim 1 , wherein:
the standard material is positioned in an internal space of a probe of the X-Ray fluorescence instrument.
4. The method of claim 1 , wherein:
the standard material is positioned in outside of a probe of the X-Ray fluorescence instrument.
5. The method of claim 1 , further comprising:
iteratively repeating the step of measuring at a defined interval.
6. The method of claim 5 , wherein:
the defined interval comprises a daily or weekly interval.
7. The method of claim 1 , wherein:
the temperature of the detector is adjusted while the X-Ray fluorescence instrument is in operation.
8. The method of claim 1 , wherein:
the temperature is adjusted when the measured resolution value deviates from a target value by about 3 ev.
9. The method of claim 1 wherein:
the temperature is adjusted when the measured resolution comprises a standard error of no more than ⅓ rd of an acceptable resolution range.
10. The method of claim 1 , further comprising:
measuring the resolution value of the detector using the standard material at the adjusted temperature.
11. The method of claim 1 , wherein:
the step of determining further comprises determining that a minimum number of the resolution measurements have been made at the first temperature since annealing or since a previous temperature adjustment.
12. The method of claim 11 , wherein:
the minimum number includes 5 resolution measurements.
13. The method of claim 1 , wherein:
the relationship of temperature change to the degree of deviation of detector resolution from the target value is computed from a series of resolution measurements at different temperatures.
14. The method of claim 13 , wherein:
the series of resolution measurements at different temperatures includes at least 4 measurements.
15. The method of claim 13 , wherein:
the series of resolution measurements at different temperatures include any range of temperature within a range of about −20 to −60° C.
16. The method of claim 1 , wherein:
the detector comprises a silicon drift detector that accumulates damage over time of use, wherein the damage degrades the resolution value of the detector.
17. The method of claim 1 , wherein:
the standard comprises a composition of mineral and polymer known to emit a particular spectral profile in response to exposure to X-Ray radiation.
18. A X-Ray fluorescence instrument, comprising:
a source adapted to direct X-ray radiation at a standard material;
a detector adapted to collect emissions responsive to the X-ray radiation from the standard material, wherein the detector is maintained at a first temperature; and
a controller adapted to:
measure a resolution value of the detector using the collected emissions;
determine that the measured resolution value deviates from a target value; and
adjust the temperature of the detector to a second temperature that restores the resolution value of the detector to the target value, wherein the temperature is adjusted by an amount defined by a relationship of temperature change to the degree of deviation of detector resolution from the target value.
19. The instrument of claim 18 , further comprising:
a shield that holds the standard in a positional relationship with the source and the detector.
20. The instrument of claim 18 , wherein:
the target value comprises a value in a range of about 140 eV to about 200 eV.
21. The instrument of claim 18 , wherein:
the target value is specified in a configuration file stored in the controller.
22. The instrument of claim 18 , wherein:
the controller is adapted to iteratively repeat the step of measuring at a defined interval.
23. The instrument of claim 22 , wherein:
the defined interval comprises a daily to weekly interval.
24. The instrument of claim 18 , wherein:
the temperature of the detector is adjusted while the X-Ray fluorescence instrument is in operation.
25. The instrument of claim 18 , wherein:
the temperature is adjusted when the measured resolution value deviates from a target value by about 3 ev.
26. The instrument of claim 18 , wherein:
the temperature is adjusted when the measured resolution comprises a standard error of no more than ⅓ rd of an acceptable resolution range.
27. The instrument of claim 18 , wherein:
the controller is further adapted to measure the resolution value of the detector using the standard material at the adjusted temperature.
28. The instrument of claim 18 , wherein:
the controller is further adapted to determine that a minimum number of the resolution measurements have been made at the first temperature since annealing or since a previous temperature adjustment.
29. The instrument of claim 28 , wherein:
the minimum number includes 5 resolution measurements.
30. The instrument of claim 18 , wherein:
the relationship of temperature change to the degree of deviation of detector resolution from the target value is computed from a series of resolution measurements at different temperatures.
31. The instrument of claim 30 , wherein:
the series of resolution measurements at different temperatures includes at least 4 measurements.
32. The instrument of claim 30 , wherein:
the series of resolution measurements at different temperatures include any range of temperature within a range of about −20 to −60° C.
33. The instrument of claim 18 , wherein:
the detector comprises a silicon drift detector that accumulates over time of use, wherein the damage degrades the resolution value of the detector.
34. The instrument of claim 18 , wherein:
the second temperature is different from the first temperature.
35. The instrument of claim 18 , wherein:
the standard comprises a composition of mineral and polymer known to emit a particular spectral profile in response to exposure to X-Ray radiation.