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Technical Articles
Over the years, Ludlum Measurements has written several technical articles in support of our products. These articles cover topics such as troubleshooting and repair tips, calibration techniques, and other information related to radiation detection and instrumentation.
Condensing Humidity
Occasionally a customer may experience a problem with condensing humidity causing dew or frost inside the instrument. Dew will form inside an instrument when it experiences a large decrease in temperature, such as moving from indoors to outdoors.
Operating Scintillation Detectors at 900 Volts
Many of our customers inquire about using scintillation and GM detectors interchangeably with the same instrument. To make this possible, a few extra steps must be taken because of the difference in operating voltages of these two types of detectors.
Repair Tips - High Background Count in Alpha Monitoring
A common problem many of our customers experience is that of excessive background count when monitoring alpha radiation with scintillation detectors. This can be caused by light leaks or contamination of the detector.
Detector Overload
Many of us have experienced the problem with punctures or "bad" seals (commonly referred to as "light leaks") in the thin mylar face of an alpha or beta scintillator. The problem symptom occurs with a detector that has been functioning properly and then suddenly will not respond to normal background count or a check source. The counting instrument appears to have "died", so it usually becomes the first suspect because of no response on the meter except maybe in the BAT position.
Combination Meter Scales
A common inquiry that we receive is the use of our survey meters and scintillation detectors with combination meter scales. The combination meter dial (counts per minute [cpm] and mR/hr) was designed so that a GM detector could be read in cpm and mR/hr simultaneously.
Repair Tips - Broken Detector Wires
A problem that customers sometime experience is broken detector wires. The Ludlum Models 43-2, 44-1, 44-3, and 44-21 are the most common detectors we have returned to us with this problem. The wires are often snapped when the end window cap is unscrewed to replace the mylar window or when the optical seal is checked.
Determining Alpha-Beta Detector Operating Parameters
Determining alpha-beta scintillation or proportional detector operating voltage, counter thresholds, and window parameters requires an understanding of the mechanics involved in simultaneous alpha/beta discrimination. The parameters involved in determining the alpha-beta detector operating points are: maximum alpha and beta efficiency, minimizing background count and "cross-talk" between alpha and beta counting channels, and uniformity across the detection area.
Gas Proportional Detectors
Questions occasionally come up about problems with gas proportional detectors. Some problems are eliminated or reduced with simple preventative maintenance. Some can be corrected with minor changes in how the detectors are set up for use. The following information should assist you in preventing or resolving common problems with your gas detectors. As always, if you need more information, please contact us.
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