Model 30-4 Neutron Meter

3He proportional detector

Ludlum Measurements

Model 30-4 Neutron Meter Model 30-4 display Model 30-4 neutron meter, bottom

The Ludlum Model 30-4 joins the Model 30 digital display unit with a 22.9 cm (9 in.) REM ball containing a 3 He detector, thereby providing a significant weight reduction and more compact, maneuverable instrument for determining neutron dose rates.Three modes of operation – RATE, MAX, and COUNT – are available for the user. Measurements can be collected in two sets of units (primary and secondary) for RATE and MAX modes in cps, cpm, rem/hr, or Sv/h units. An internal switch is used to enable or disable the front-panel setup feature to protect desired settings from inadvertent modification. Setup is also available via software from Ludlum Measurements.

This instrument features a large, easily-readable LCD (liquid crystal display) that may be rotated for maximum ease of use for the operator. The connecting cable is threaded through the rugged carrying handle to simplify use. In addition the display unit may be detached from REM ball permitting the operator to position the detector and the display unit to best advantage within the limits of the cable length. Other features are an audio warning tone and easy, intuitive, user-friendly design. Splash-resistant construction allows the Model 30 to be used in outdoor environments. The instrument body is constructed of lightweight, durable, high-impact plastic.

Indicated Use Neutron dose rate
Detector 3He proportional detector, 1.6 x 2.5 cm (0.6 x 1.0 in.) (D x L), surrounded by a 22.9 cm (9.0 in.) diameter cadmium loaded polyethylene sphere
Measurement Range 0 to 99.9 mSv/h (0 to 9.99 rem/hr)
Sensitivity (bare AmBe neutrons) Typically 10 cpm per μSv/h (100 cpm per mrem/hr)
Energy Response Provides approximate inverse RPG curve for neutrons from thermal through 7 MeV, provides response up to 12 MeV
Linearity Reading within 10% of actual value
Gamma Rejection (137Cs gamma) < 10 cpm through 0.1 Sv/h (10 R/hr)
LCD Display 3 digit LCD with large 13.4 mm (0.53 in.) digits, low-battery indicator, MAX, ALARM, MUTE
Units (k)cps, (k)cpm, (µ)(m)Sv(/h), (µ)(m)rem(/h)
Display Range
0.0 cps to 99.9 kcps
0.00 cpm to 999 kcpm
0.00 rem/hr to 999 rem/hr
0.00 µSv/h to 999 Sv/h
Display range can be set to limit display to calibrated range
Backlight Built-in ambient light sensor automatically activates low-power LED backlight, unless internal dipswitch is set to continuous-On (will reduce battery life). Alarm light intensity varies based on ambient light levels.
Controls
ON/OFF/ACK Press to turn ON; Tap to acknowledge alarms and silence alarm tone; Press to reset Sigma Audio alarm, turn “click” audio On/Off, turn Sigma Audio beep On/Off; Press and hold for OFF
Mode Alternates between NORMAL (count rate), MAX (captures peak rate), COUNT (user-selectable preset count time from 0 to 10 min.). Number of modes can be reduced in setup.
Units Changes the units between count rate (cpm, cps) or dose/exposure (µSv/h, rem/hr)
Response Time User-selectable from 1 to 60 s, or Auto-Response Rate FAST or SLOW
Alarms Count rate, exposure/dose, and scaler alarm setpoints adjustable over the display range
Overload High count rate saturation protection prevents false display of lower count rates
Dead Time Correction Employs first and second order corrections for extended performance
Operating Voltage Approximately 1200 Vdc
Threshold -2 mV
Audio Greater than 75 dB at 0.6 m (2 ft), approximately 4 kHz
Power Two alkaline or two rechargeable “AAA” batteries
Battery Life Approximately 100 hours of operation, 24-hour low battery warning
Construction High-impact plastic with water-resistant rubber seals and separate battery compartment
Working Environment Splashproof shields for outdoor use
Temperature Range -20 to 50 °C (-5 to 122 °F)
May be certified for operation from -40 to 65 °C (-40 to 150 °F)
Environmental Rating NEMA rating of 3x or IP rating of 52 with audio hole seal option (hole seal option will reduce maximum volume by approximately 10 dB)
Size Display Unit: 8.5 x 8.0 x 4.8 cm (3.4 x 3.1 x 1.9 in.) (H x W x L)
Detector 22.9 cm (9 in.) diameter REM ball with 3He detector (1.6 x 2.5 cm)(D x L)
Weight Display Unit: 174 g (0.38 lb)
REM Ball Component 6.6 kg (14.5 lb)

Ludlum Model 30 series manual

Manual