J' McQuaid

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SAM 940
J. McQuaid

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SAM 940
SAM 940
Real Time Analysis Mode
1. Quadratic Compression Conversion (QCC)
Compression from 16K to 512 channels
2. Time slice update every second

• 3. Subtract background and tool out continuum
• ID when masked by another isotope 1000x intensity
• ID in presence of backscatter

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SAM 940
Importance of QCC Technology
4K Resolution QCC Acquired Spectrum compressed to
256 channels

• High peak to background over entire energy range

• Constant peak width allows efficient search
  algorithm

• Both low and high energy peaks are well resolved

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SAM 940
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Start up Screens
SAM 940

• Status Screen User Selection

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Search/ID Screens
SAM 940
Dial
Finder
Spectrum
Bars
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SAM 940
Identify using Dial or Finder Screens
1. Highlight the Identify Soft Key and ENTER
2. Default time is 1 minute. This can be
decreased or increased in 30 second intervals.
ENTER and hold to slew out to large time
intervals (e.g., 15 minutes)
3. Report appears after the acquisition period.
Spectrum and all data are stored with time, date
and number automatically.
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SAM report screen
SAM 940

• SAM report header, dose rate, gamma counts , and
  ID of isotope

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Stored Spectrum
SAM 940

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SAM 940
User Menu Screens
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SAM 940
User Menu Screens
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SAM 940
Isotope Specific Dose Rate

• The dose rate is calculated for each isotope less
  background and given in rem/h or Sv/h

• Based on ambient dose equivalent, H(10) and taken
  from ICRU report 57

• Dose rate of each isotope is summed and total
  given including background

• When no sources are present dose rate will be
  ambient background

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SAM 940
Taking a Background

• Highlight Background Soft Key and Press Enter

• Default Time is one Minute

• Slew to larger time interval

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SAM 940
Coarse Calibration
1. Generally not performed unless there is a very
large change in temperature since last used.
2. SAM should stay in calibration even when
temperature changes dramatically.
3. Coarse Calibration is performed by following
directions in Menu (1st Page).
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SUMMARY
SAM 940
SAM 940 Has Unique Features
1) The SAM 940 gives both real time response and
high sensitivity.  Our QCC patent allows one
second isotopic response at factors of 10 to 20
below background levels. 

2) The CF card with all the stored data (up to
10,000 spectra) can be read by any computer for
archival and quantitative analysis.
3) The SAM is designed to operate in any
background (high or low), including
Bremsstrahlung and Compton, with this
interference subtracted in real time.
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SUMMARY
SAM 940
SAM 940 Has Unique Features Contd
4) Stabilization is performed with K40.  Unlike
Cs137, K40 is NORM and needs no special
documentation or DOT approval.  It also does not
interfere with the detection of Cs137 or cause
anomalies that can produce false positives.  The
background subtraction of K40 is clean and
unambiguous.