Ludlum Measurements 25024424, Manual

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44 CHAPTER 7. CONFIGURATION
• Ones Place (0-9)
• Tens Place (0-9)
• Hundreds Place (0-9)
Combined Range of Second Order Dead Time Correction Mantissa and Exponent: 000E-12
- 999E-6
ò
This should be set disabled when checking instrument with pulser or function
generator; otherwise, higher count rates will result in non-linearities.
Second Order Dead Time Correction Exponent - Value is used with Second Order Dead
Time Correction Mantissa to provide a second order linearization in high fields. An "-" is
always visible on the leftmost character (not flashing) to help signify this is a negative expo-
nent (see Dead Time Correction on page 55).
Configurable positions are:
• Exponent (-6 to -12)
Range: See Second Order Dead Time Correction Mantissa
Efficiency - Defines the efficiency of the detector. Value is only used when the selected dis-
play units are dpm, Bq, or disintegrations. Units are in percentage.
Normally the efficiency is used on a per detector basis or 4pi basis, i.e. the efficiency of the
detector is calculated by dividing the count rate received from a source by the total disin-
tegration rate of the source. When either dpm or Bq units are chosen, the use of the 4pi
efficiency allows the display of the source size or activity on the display.
But if the user desires to have the instrument show results in terms of dpm/100 cm
2
, the user
could manipulate the efficiency to produce this result by multiplying the efficiency times the
ratio of the detector area to 100 cm
2
. For example, using a detector with an area of 15 cm
2
,
if we start with the 10% efficiency to measure in dpm, then the parameter could be changed
to 1.5% to measure in dpm/100 cm
2
.
Or likewise for Bq/cm
2
, efficiency could be calcuated as effi count rate/disintegration
rate*detector area (in cm
2
). For example, with the same detector as above with an area of 15
cm
2
, and starting with and efficiency value of 10%, then the parameter could be changed to
150% to measure in Bq/cm
2
.
Configurable positions are:
• Ones Place (0-9)
• Tens Place (0-9)
Ludlum Measurements, Inc.