Model 702i and 711i
Technical Manual
Section 2
Ludlum Measurements, Inc.
2-1
December 2018
Getting Started
Turn on the Model 702i or 711i unit by holding down the power key (which is also the B
ACK
key)
until the status screen appears. Press E
NTER
to move to the log-in screen, and then press E
NTER
(
) again to advance to the user-mode search screen (generally Dial). At the bottom of the screen
there will be a message indicating auto calibration is in progress. This may take one to three minutes.
The instrument is then ready for use.
Basic Operation
Refer to the following screen drawing, where three soft keys will be seen (
Identify
,
Background
,
Finder
). These are accessed by the L
EFT
(
) or R
IGHT
(
) arrow keys and then pressing E
NTER
.
The far right soft key allows the user to select between the available search modes. The Dial and
Finder screens are the simple modes of operation where the Dial gives count rate information in the
form of a speedometer. When radioactive material gives an indication in the green region, this
signals proper source intensity for identification with gamma count rate. The other colored regions
indicate the source is too far (gray) or too close (red). The Finder mode allows location of the
source by displaying intensity vertically and time horizontally. The midscale “ID” shows the proper
intensity for identification. In addition, an audio signal can aid in finding the source. The other two
search modes (Bars and Spectrum) are more advanced and must be enabled in the administrator
menu. These two screens allow the user to view isotopes in the form of vertical “Bars” or a
“Spectrum,” where the isotope is identified or its presence is seen in real time. These modes also
give isotope category and dose rate in real time.
Identification may be performed in any one of the four modes. Simply highlight the
Identify
soft
key and press E
NTER
. A report appears after the acquisition period. Isotopes identified are shown
with a statistical confidence number ranging from 0 to 100%. This is based on source strength,
length of acquisition, number of energy lines, and statistical factors. The default for taking a
background or acquiring a spectrum is one minute. The length of acquisition can be increased or
decreased by pressing E
NTER
when the soft key is on ±30 seconds. If E
NTER
is held down, the
length of time can be changed rapidly. Pressing the B
ACK
key allows the user to return to the search
modes. Holding down the B
ACK
/ power key for a count of three seconds turns the instrument off.
Section
2
