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Detailed introduction
Application of Detective-200 in large area searches (land and air)
In these non-maritime applications, the Detective-200 is easily installed on unmodified vehicles, cars, trucks and aircraft for higher speed and longer range mobile detection applications. Additional Detective-200 can be easily integrated into the system for increased sensitivity. Data can be combined using the Detective-Remote utility software. Multiple Detective-200s can be stacked vertically.
In another type of application, the instrumentation system is fixed and the potential source is mobile, for example as a monitor at traffic chokepoints (toll booths, bridges, tunnels), or for monitoring entrances to public events, monitoring road traffic or vessels passing underneath bridge structures. The measurements are essentially the same.
The configurability of the Detective-200 is extremely useful in both mobile and stationary applications and cannot be overemphasized here as requirements are constantly changing.
Maritime applications of Detective-200
- "Slow pass" material interception
Detective-200 is very suitable for installation on ships. IP67-rated packaging design is not affected by salt spray. The sturdy fold-down handle makes it easy to lift and install on a boat, or transport from one boat to another.
The shipboard Detective-200 system, consisting of one or more instruments, can be controlled wired or wirelessly via Detective-Remote and is capable of reliably detecting illicit materials on nearby vessels during slow "cruise" measurements. Figure 1 shows an example of the sensitivity of multiple Detective-200 instruments to unshielded HEU at representative speeds and distances.
choke point monitoring
Because fixed traffic entrance and exit monitors do not have 100% coverage, there is a need to be able to quickly set up and configure temporary or “ad hoc” entrance and exit systems to monitor moving traffic for nuclear devices, dirty bombs, or contaminated materials. One or more Detective-200 units can be placed unobtrusively at curbs, pedestrian walkways, supplier service entrances, warehouse docks or parking lots. Detective-200 internal battery power and "auto-identification" reporting simplify installation and operation.
Figure 2 provides estimated performance of multiple land-based Detective-200 instruments at 10 MPH and distances (up to 40 meters) with the same alarm conditions as Figure 1.
Long range detection
Long-range detection involves the issue of whether stationary or near-stationary radioactive sources at a distance can be correctly identified. The long-range detection limit basically depends on the signal-to-noise ratio in the detection system. Gamma rays are attenuated by air as distance increases, and a fixed field of view means that at greater distances more background is in the source's field of view. Both factors reduce the signal-to-noise ratio. As with other applications of low-resolution systems, background variation is an issue. The Detective-200's high resolution and its large area detector make it an ideal long-range tool, either alone or in an array. Figure 3 shows the time to identify 2.5 kg of bare HEU with >95% detection probability and <1 false alarm every 20 hours. (Note that the critical mass of highly enriched uranium is approximately 50 kg.)
IMPORTANT NOTE: Impact of alignment on system performance
In all applications discussed, detection times or detection limits may be adversely affected by radiation background, which reduces statistical counts and therefore lowers (raises) the minimum detectable (identifiable) nuclide activity. Background can be reduced by using shielded collimators to limit the field of view (FOV) of the detection system. The example data in Figures 1, 2 and 3 above all assume a collimated FOV of 120°. Collimation depends on the measurement speed, distance, and radioactivity of the specific environment. The overall effectiveness of the system depends on the number of Detective-200s and collimation selection. ORTEC scientists will be happy to advise you on the configuration to implement.
Detective-Remote Software
Detective-200 is compatible with versions of Detective-Remote software. Detective-Remote is a Windows-based application that "can" identify multiple Detective-200s and control them remotely via direct USB connection or via wireless LAN. Detective-Remote supports one or more Detectives as components of a multi-detector system, and can combine multiple instruments into a composite system based on multiple "nodes". Through sophisticated techniques (rather than simple spectral summation), the composite system can be operated like a single large detector with a certain positional sensitivity. Unlike a true single large detector, the Detective-200 which "does not see" the nuclide ID signal, as well as their background contribution, can be temporarily ignored, thereby enhancing the signal-to-noise ratio in the composite signal compared to a single large detector (as is the case with NaI "LOGS" usually used in scintillation detector mobile systems). Detective-Remote software supports not only the Detective-200, but any size or model of Detective, and any combination thereof. Data are collected by Detective-Remote in Lctive mode and individual spectra are stored in a localized database that can be exported to other applications (such as spreadsheets, GIS applications or reporting software).
“No other nuclide identification instrument offers such high sensitivity and accuracy in such a rugged and flexible package design.”
Detective-200 hardware features
Since the launch of the model in 2004, all ORTEC Detective identifiers have used the same principle technology and features, namely:
- High-resolution, high-purity germanium (HPGe) detector.
- Mechanical cooling is performed by a micro Stirling cycle refrigerator.
- Internal high-range GM tube provides gamma dose rate.
- Fast, easy and ultra-reliable classification of standard, medical, industrial, SNM and natural isotopes (shielded and unshielded).
- Touch screen or remote software operation.
- Complies with ANSI N42.34 and ANSI N42.42 standards.
- Powered by battery/AC/DC, highly stable digital electronic device.
- Wired USB, 802.11 wireless communication.
- Local storage of spectra.
- Advanced analysis algorithms developed on thousands of real recognition situations:
- Low false alarm rate in the presence of NORM (standard)
- High-fidelity identification of mixture ingredients
- Prevent "false positives" caused by masked sources
- Unaffected by changes in background radiation
- The intuitive touch screen GUI is easy to use and operating modes are configurable according to individual CONOPS, including long count mode for weak/far sources.
- Neutron detection model.
Detective-200 operating functions
Search mode
The gamma count rate is shown as a strip plot over time.
Monitor mode
Detective collects a spectrum every second and runs the ID algorithm against an 8-second sliding average. More sensitive to sources moving relative to the instrument. Monitoring mode is a meaningful search method and is also useful in applications such as ad hoc entrance and exit monitoring.
SNM search mode
SNM search mode is used to help avoid false negatives when determining SNM. It helps to find count rate points that may be consistent with SNM.
This mode monitors key regions of the spectrum to further determine the presence of U-235 (a key component of HEU) and Pu-239. Peak area confidence levels are displayed as a bar chart. High and stable readings indicate the possible presence of "radioactive isotopes" that warrant further study. Once a reading is found, press the OK key to start the full identification algorithm.
SNM search mode can indicate SNM, but the ID should always be verified to avoid false positives. The combination of SNM search and ID mode can minimize the probability of false negatives and false positives.
Γ dose rate
The gamma dose rate is monitored by HPGe detectors and internally compensated GM tubes. The dose rate is always displayed on the screen. Dose rate units can be selected as μSv/hr or mR/hr.
GPS location information
The internal GPS receiver will display GPS coordinates, which can be saved along with the spectrum data for future use.
Data storage (spectrum, search data, ID results)
Store to internal RAM and removable SD card.
computer interface
Connect to laptop's USB port. Spectral transmission via Microsoft® ActiveSync. Remote control via Microsoft "remotedsp.exe" (included). WiFi (802.11) communication. Wireless mobile MCB server software.
show
It adopts a large, bright and clear touch-sensitive LCD screen. Gamma count rate and gamma dose rate are displayed continuously as numbers and bar graphs. Menu navigation is very intuitive. Radionuclide gamma-ray spectra can be displayed and manipulated (e.g., vertical scale, zoom) similar to traditional multichannel analyzers. Y-axis units can now be displayed.
operating mode
In response to customer requests, Detective instruments can now operate in both "Classification" and "ANSI" modes.
Classification mode
The user presses the identification button and the instrument collects data until the instrument is manually stopped, no preset required. During collection, if suspicious nuclide classification information (such as "Suspicious Industrial 1") appears, it means that the presence of an industrial nuclide is suspected. As counting continues and the confidence level increases, the information may change to "Industrial 1 Found" or disappear as better statistics determine that the previously suspected nuclide is not actually present. Clicking on the Found or Suspicious message displays a list of actual found (or suspected) nuclides by name.
ANSI mode
This mode is similar to the classification mode, but instead of classifying, the names of suspected or discovered nuclides are directly displayed.
Default time
This is to allow CONOPS to count within a preset time (e.g. 60 seconds). At the end of the preset period, only what was found is reported, and no suspected nuclides are reported. If desired, the operator can request an extension of the count time to multiply the original preset time.
LCX (Low Confidence Expert) ID Mode
LCX mode is password protected. LCX stands for "Low Confidence Expert" and is suitable for expert users. This identification mode displays suspicious threat alerts and identification results with a lower confidence level than normal mode. This allows for the detection of more suspected threat nuclides.
Instrument calibration
The instrument has been calibrated before leaving the factory. The energy calibration can be checked and adjusted using any known source with clean gamma rays between 0 and 3 MeV. Higher energy is recommended. Cs-137 is often used. Calibration can be done manually or automatically. Background acquisition is now a required part of calibration. By allowing activity that is already present in the background, the system will no longer report nuclides detected in the background. Previous versions of these IDs sometimes confused users. The background must be updated according to the schedule selected by the privileged user.
Smart Stabilizer
The "Smart Stabilizer" stabilizes the gain of the K-40's 1460 keV peak very precisely, if present. The smart part is that if no K-40 is present or if Eu-152 is detected that could interfere with the K-40 peak, the stabilizer settings remain unchanged until "normal" conditions are restored. While Detective is a highly stable instrument, the Smart Stabilizer can also accurately determine more complex mixed spectra.
Mobile MCB Server
The Mobile MCB Server software application enables any ORTEC portable instrument with a PDA installed to communicate wirelessly with ORTEC software applications such as MAESTRO, MAESTRO-PRO, GammaVision and Detective-Remote. The mobile MCB server acts like a wireless version of a USB interface, allowing users to control and monitor any portable spectrometer over a wireless network.
Users can develop their own applications by using the optional A11 toolkit.
Detective-200 Mobile Detection System Rack Kit
Rack kits provide a simple, portable solution for building “ad-hoc” motion detection systems that do not require mounting on a vehicle.
- Up to four Detective-200s are supported in different configurations.
- Portable, lightweight and foldable.
- Easy to install and remove.
- Rugged rack for mobile applications.
- Can be configured for a variety of vehicle models.
- Carrying case for transporting the rack and two Detective-200s.
- Car computer installation kit.
Shoulder straps. Fixed on the instrument for easy portability. Each instrument has a shoulder strap. 
M-1-T2 tripod. 
Super power expander with charger.Powers the instrument, thereby maintaining the current state of charge of the internal battery. Does not charge the internal battery. Battery life > 8 hours. Supports hot swapping. Weight ~3 lbs.
Optional collimator
