ORTEC Fission Meter FM-P3, Руководство пользователя

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ORTEC
®
Fission Meter
®
(FM-P3) Portable Neutron Source Identification System 931026D / 060118
10
To perform a static search, place the instrument in the area where the alarm occurred, or where there is an
otherwise suspected source, and start the Static Search Mode. Static Search Mode relies on a static count
rate. Therefore,
it is critical that the instrument remain static with respect to the area being monitored. This
measurement can take several hours to obtain an accurate partitioning of the total count rate into cosmic
and non-cosmic fractions. If the count rate is adequate and the source is significantly multiplying, Static
Search will indicate so, and you will switch to the third mode, Characterization Data Collect.
The Advanced Static Search Mode is discussed in Section 3.3.3
.
2.1.3 Characterization Data Collect (“ Triage ”) Mode
Following the determination by Static Search mode that an actual fissioning neutron source is present, this
mode allows for the collection of much more data (~1,000,000 counts) to be transmitted for expert analysis.
An e-mailing feature allows you to connect the Ranger PDA to a PC with internet access so suspicious neutron
data can be sent to the appropriate authorities for analysis and recommended action (see Section 3.4).
This mode also allows you to graph the characterization data in two ways. The first is the multiplicity plot. It
shows a Poisson (random) distribution matched in mean count to the data. Deviation of the data from a
purely random distribution could indicate the presence of non-cosmic neutrons. The second plot is the
neutron lifetime, which can aid in detecting moderating material such as polyethylene shielding.
The Advanced Characterization Mode is discussed in Section 3.4.1.
2.2 How the Fission Meter Acquires and Stores Data
The Fission Meter software fetches data from a hardware buffer every 0.25 seconds and updates the Ranger
display accordingly. We refer to this 0.25 second interval as a
data acquisition cycle .
2.2.1 Data File Contents and Filenames
The data for each acquisition in Characterization Mode are written to a
2A.log
file, which contains
information about the hardware settings and a list of the neutron multiplicities in the Fission Meter’s time
subgates for each data acquisition cycle.
2
The filenames are based on the date and time data acquisition
begins, and are formatted as:
MMDDYYYY_HHmmSS-2A.log
For example, file
03102018_142032-2A.log
was created on March 10, 2018, at 2:20.32 p.m.
2 The Real_Time.log data files are for a specialized purpose and can be deleted.