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Application The LB 111 Micro Gamma is a versatile instrument to measure local doses and doserates in one or two channels. It can be software programmed for manifold applications, and contains all facilities for data storage and data transmission.
The LB 111 Micro-Gamma can be employed as a stand-alone system with local result and alarm indication. Several LB 111 systems may be connected to one central data station inside one premise via a local network with leased line, eg. RS 485 bus system. Transfer of the data protocol to a central station via the local communication network with telephone modem connection is possible for large-area environmental monitoring.
System Assembly The measuring electronics are installed in a compact, shielded wall housing with the signal column for local alarm indication mounted on top. One or two probes are connected. Gamma and neutron detectors are suitable for connection, and include an internal high voltage generator and a standard pulse output .
The measurement is performed in two separate channels. The measured values of both channels can also be added, for example, to extend the range, with automatic switchover between low-dose and high-dose probes, or for summation of the gamma and neutron dose equivalent.
The standard version of the signal column includes a green/red light for regular operation and alarm status. It may be equipped with different alarm components (constant, blinking or flashing light or horn). The instrument includes 5 relay outputs as standard for remote communication of alarm and status messages.
A unidirectional RS 232 interface is available for data transfer and data communication in measuring networks; another interface is provided for printer connection. Furthermore, two electrically separated 0/4 - 20 mA analog outputs are available for connection of a recorder. Data acquisition and system control functions are undertaken by a microprocessor.
System Calibration The LB 111 system has been type-tested and approved by the German National Bureau of Standards (PTB Braunschweig). The calibration factor determined by PTB can be applied to all systems without further individual calibration. Individual calibration, however, by a national laboratory is available on request as an option. Parameters essential to calibration and settings are locked, and are accessible only by breaking a seal affixed after the calibration procedure.
Result Indication The results are indicated on an LCD display. Supertwist technique and background illumination ensure a good readability even in badly lit environments. The following displays can be called up while the measurement is running:
Measuring Methods The count rates supplied by both digital channels can be corrected with regard to inherent background and dead-time of the connected probes before they are converted into the doserate. The digital ratemeter operates with a basic time of one second, using a sliding time constant for averaging, which is dependent upon the live countrate and the preselected statistical error constant.
The short and long measuring times, which can also be preselected, determine the printout and data transfer interval, and in the case of data communication, define the storage in FIFO. With activated dose integration (balancing) the radiological data are added up in the short measuring time interval to determine the dose. A built-in "life-time counter" sums up the counts of GM-counter tube probes and indicates the elapsed life-time in percent or the total count rate.
Utility Programs The utility programs include several very useful service functions, for example, background determination, calibration and system test. The results obtained can automatically be entered in a user file as parameters (e. g. background values, calibration factors.
Settings
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Measuring and help functions
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Thresholds and outputs
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Data storage
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Operation The instrument is operated via a foil keypad and menu-driven dialogs using softkeys. The program includes three basic functions: set parameters, run measurements and activate utilities.
Home Radiation Contact For further information email radiation@berthold.com.au