Model 9DP-1*

The Model 9DP-1* is a digital, hand-held pressurized ion chamber that provides highly sensitive ambient dose equivalent measurements of gamma and x-ray radiation at energies above 25 keV and beta radiation at energies above 1 MeV. Ambient dose equivalent is defined as the dose equivalent readout that would be measured at a (human) tissue depth of 10 mm. The Model 9DP-1* measures and displays the ambient dose equivalent in accordance with the ICRU (International Commission on Radiation Units) 30 cm tissue equivalent sphere. This requires a special ion chamber that can provide a conversion of the (air kerma) exposure rate to provide the ambient dose and dose rate.

This meter is also specially designed to measure pulsed radiation fields, correctly integrating 50 ns pulses (and wider) that other systems typically miss or measure inaccurately. Another feature is a detector chamber that is only pressurized to 2.5 atm (22 psig), eliminating (USA) shipping and handling HAZMAT concerns. However, this reduced pressure also decreases sensitivity, reducing the minimum measurement point to 2 µSv/h (200 µR/hr).

Measurements and instrument status are displayed on a large 232K-color, backlit LCD screen. The screen displays the current dose rate as well as simultaneously displaying either the integrated dose rate or the peak dose rate in Sv, R, Gy, or rem units. An additional mode, Pulsed Mode, locks the instrument in the highest measurement range in order to improve pulsed radiation response while sacrificing low radiation reading resolution.

The instrument is operated using the four push-buttons below the screen (ON/OFF, FUNCTION, AUDIO, ACK/RESET). In addition to the visual display, click audio proportional to the current dose rate audibly indicates the dose rate level. Two alarm levels can be set to alert the user whenever the pre-programmed level has been exceeded. Alarms are indicated on the display and by an audio tone. The instrument can also be configured for data logging. Logged data can either be stored in CSV format and written to a standard USB drive inserted in the instrument’s USB port, or written directly to a Microsoft Excel spreadsheet by connecting the instrument to a computer running Ludlum’s Model 9DP Logging Spreadsheet Software (see Options).

The Model 9DP parameter settings can be edited by connecting the instrument to a basic USB keyboard. Instrument setup and calibration can also be configured using the Ludlum Dimension Interface Kit, which includes the Dimension Configuration Manager Software and the required USB cable (see Options).