Monitoring Gamma Radiation

Meteorological and radiological sensors are attached on NEWNET stations to the Data Collection Platform (DCP).

The DCP takes meteorological measurements every second and radiological measurements every minute. All data are averaged every 15 minutes. The data are immediately available on the NEWNET Data page.

The gamma data are evaluated for quality assurance. Comments regarding data quality and station information are also available. Information describing the station sensors is available in the instrumentation section below.

The data listing contains 15-minute sensor averages. Note that when a data value is not available, the data position is filled with asterisks, "*". This happens when a station does not have a particular sensor, or when a transmission error occurs. The data are generated as a "text/plain" file.

Gamma radiation, barometric pressure, temperature, and humidity are measured and recorded. Wind data are recorded but are not checked for quality assurance and are not guaranteed.

Terms used in NEWNET Data Listings are explained below:

• Date and time = universal time (the date and time at zero longitude) or what is sometimes referred to as Greenwich Mean Time (GMT) or ZULU Time.
• Gamma = The level of gamma radiation is reported in micro Roentgens (µR) per hour. A "Roentgen" is a unit that describes the ionizations, or removal of electrons from atoms, in air that are caused by gamma rays. One µR = .001 milliRoentgens (mR) or .000001 Roentgens (R).
• Doses from nuclear radiation are expressed in "rem," which stands for Roentgen equivalent man. The rem accounts for the fact that different types of radiation may have different biological effects. It is a measure of absorbed radiation dose. One Roentgen (R) of gamma radiation over the whole body is approximately 1 rem.

The government has established Radiation limits. These limits are 5 rem per year for occupational exposure (radiation workers), as well as a limit of 100 millirem per year above background from man-made sources for the general public. Background radiation levels vary with altitude (increased cosmic radiation at higher elevations) and local geology. You can calculate the radiation in your environment using the Dose Calculator in the NEWNET Interactive section.

The following is a brief description of the instrumentation on a typical NEWNET Data Collection Platform (DCP). Specifications are from the manuals and data sheets provided by the instrument manufacturers, and may be dependent on periodic calibration being performed at the manufacturer's recommended interval.

• Gamma Radiation
  • Gamma radiation is measured by a Reuter-Stokes High Pressure Ionization Chamber, model RSS-120 (RSS-1013 includes the electronics). This instrument has an ionization chamber filled with argon to a pressure of 25 atmospheres. Reuter-Stokes is a subsidiary of General Electric.
    • Range: 0-100 mR
    • Precision: ±5%
    • Ionization chamber volume: 7.9 liters
    • Energy response: 0.07 to 10 MeV
• Temperature
  • Temperature is measured by a Met One model 064-2 temperature sensor mounted in a model 075 solar shield to reflect solar radiation.
    • Range: -50 to +50° C
• Humidity
  • Humidity is measured with Rotronic Hygromer™, model 200 series.
    • Humidity Range: 0-100% RH
    • Precision at 68-77° F: ± 2% RH
    • Temperature limits at sensor: -5 to 212° F (-20 to 100° C)
• Barometric Pressure
  • Barometric pressure is measured by a Met One Barometric Pressure Sensor Model 090D. This is available in a number of calibration ranges, determined by the elevation of the station. Barometric pressure decreases by about 1" Hg per 1000 ft of elevation. The value is converted to milibars of barometric pressure, and is reported unadjusted for elevation. (Values normally reported in weather reports have been adjusted to pressure at sea level.)
    • Calibration Range (standard model): 26-32" Hg at 0-1500 feet (elevation)
    • Accuracy: ± 0.7%
    • Operating temperature range: -22 to 50° C
• Wind
  • Wind data is measured by Met One Model 6266/037 and Model 013/023 Wind Finder Systems, each consisting of a wind speed sensor (anemometer cup) and wind direction sensor (vane). The wind-speed data are not checked for quality assurance and are not necessarily accurate. They should only be used as relative indications, not as absolute measurements.
    • Range: 0-100 mph; 0-360 degrees
    • Threshold: 1.0 mph, speed and direction indicators
    • Precision: ±0.25 mph or 1.5%; ±8 degrees
    • Distance Constant: LT 5 feet (speed); LT 1.5 feet (direction)
    • Damping Ratio: 0.25 (direction)
    • Temperature Range: -50 to +85° C (speed); -50 to 70° C (direction)