Model 9DP-1

Pressurized Ion Chamber

Part Number: 48-3899

The Model 9DP-1 is a digital, hand-held pressurized ion chamber that provides highly sensitive exposure measurements of gamma and x-ray radiation at energies above 25 keV and beta radiation at energies above 1 MeV. This meter is specially designed for radiography work where pulsed fields are being measured. It correctly integrates 50 ns pulses (and wider) that other systems typically miss or measure inaccurately. Another feature of this instrument is that the detector chamber is only pressurized to 2.5 atm (22 psig), thus avoiding all (USA) HAZMAT concerns for shipping and handling. However, this reduced pressure also reduces sensitivity, so the minimum “good” measurement point is 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 exposure rate as well as simultaneously displaying either the integrated exposure rate or the peak exposure 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 exposure rate audibly indicates the exposure 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).


  • Range: 2 µSv/h to 500 mSv/h (200 µR/hr to 50 R/hr)
  • Special Design for Measuring Pulsed Fields
  • Low Pressure Chamber is Non-Hazmat
  • Shows Exposure Rate & Either Integrated Exposure or Peak Exposure Rate
  • Pulsed Mode for Measuring Pulsed Radiation
  • Sunlight Readable Color Display
  • Auto-Zeroing & -Ranging
  • Rechargeable Batteries
  • Audio & Visual Alarms
  • Data Logging
  • USB Connectivity
  • Free Firmware Updates Through Website




Radiation DetectedGamma & X-rays above 25 keV
Beta above 1 MeV
Correctly integrates pulsed fields with 50 ns pulse widths
Energy Response± 25% from 60 keV to 1.25 MeV (see Graph)
Detection Range
  • Sv/h units*: 2 – 50 μSv/h, 2 – 500 μSv/h, 0 – 5 mSv/h, 0 – 50 mSv/h, 0 – 500 mSv/h
  • R/h units:  0.2 – 5 mR/h, 0.2 – 50 mR/h, 0 – 500 mR/h, 0 – 5 R/h, 0 – 50 R/h
  • Gy/h units: 2 – 50 μGy/h, 2 – 500 μGy/h, 0 – 5 mGy/h, 0 – 50 mGy/h, 0 – 500 mGy/h
  • rem/h units: 0.2 – 5 mrem/h, 0.2 – 50 mrem/h, 0 – 500 mrem/h, 0 – 5 rem/h, 0 – 50 rem/h
* Users wanting to take measurements in Sv/h units should see the Model 9DP-1* which is specifically designed to measure ambient equivalent dose.
Measurement ReadoutsSimultaneous display of rate and either the integrated value, highest (peak) rate, or pulsed mode status
DriftLess than 0.3 µSv/h (30 µR/hr, 0.3 µGy/h, 30 µrem/h)
Chamber Volume220 cm3 volume pressurized to 2.5 atm (22 psig)
Chamber DensityChamber wall density is 601.7 mg/cm2, Can wall density is 332.5 mg/cm2. Total density of chamber + can is 934.2 mg/cm2.
Accuracy± 10%
Response TimeRanges from 5 seconds in lowest range to under 2 seconds in highest range when measuring from 10% to 90% of final value
DisplayLCD with 8.9 cm (3.5 in.) diagonal, 240 H x 320 W pixels, TFT active matrix, 232K colors, 220 cd/m2, automatic sensor-controlled backlighting
User Controls4 pushbuttons:
  • ON/OFF
  • FUNCTION (for peak rate, integrate, or pulsed modes)
  • AUDIO (on/off, volume)
  • ACK/RESET (for alarm acknowledgement, meter reset, and clearing integrated dose or peak rate)
Automatic FunctionsAuto-ranging, Auto-zeroing, Auto LCD backlighting
AlarmsTwo levels of radiation alarms available, each is user programmable throughout entire readout range.
Data LoggingData is stored to detachable USB drive in CSV format for easy retrieval by PC spreadsheet/database programs. Data points include date and time, rate, integrated reading, and instrument status. Logging time intervals are set by PC interface program or USB keyboard (see Options).
Audio OutputsBuilt-in unimorph speaker, > 60 dB at 0.6 meters (2 ft.).
Optional audio jack available for connection to an external headset. (see Options)
USB InterfaceSingle USB 2.0 port. May be connected to:
  • A USB keyboard (with no additional USB ports, and no integrated mouse or trackpad or audio controls) to facilitate password-protected parameter changes
  • A USB memory storage device for storing logged data
  • A PC with the optional Dimension Interface Kit for parameter editing and calibration (see Options)
Warm Up Time< 1 minute when the instrument is in temperature equilibrium with the surrounding environment
Temperature Range-20 to 40 °C (-4 to 104 °F)
Humidity0 – 95%, non-condensing
Geotropismless than 1%
PowerEight rechargeable “AA” NiMH batteries, supplied with wall charger for direct connection to instrument
Battery LifeApproximately 12 to 30 hours between charges depending on backlighting and USB usage
ConstructionDurable molded plastic with internal metal support
Size (H x W x L)21.9 x 11.6 x 24.5 cm (8.6 x 4.6 x 9.6 in.)
Weight1.5 kg (3.3 lb), including batteries

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