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2. Data headers in Gamman

When processing data in Gamman, data is shown in a spreadsheet as shown below. The columns which are available depend on the imported data and the processing which has been applied. This document gives some information on the available headers.

When data is being imported, all data is being synchronized to the gamma spectra. In other words, all data is connected to the gamma spectra, giving one row of data for each gamma spectrum. If data has not been received at the same moment in time, interpolation is applied. Each spectrum is given a unique number.

Columns often contain a suffix such as "_GPS" or "_SPC". These indicate the origin of the data. In these cases a GPS and a gamma spectrometer. 

Headers

Header label

Description

Spectrum no

A unique number for each spectrum.

7-5-2015

"7-5-2015" is the date on which the data was recorded. The column shows data such as 42132.500000. These are "Excel type" time stamps, the number of days since 30 Dec 1899. The fraction part stands for the amount of time passed on the day. 42132.500000 means the 42132nd day since 30 Dec 1899, at 12:00. The same day at 18:00 will show as 42132.750000

UnixDateTime

A time stamp that shows the amount of milleseconds passed since January 1st 1970.

X_GPS

X position in meters. This is data created by converting from WGS84 latitude/longitude to the UTM coordinate system. Metric coordinates allow for easy calculation of distances.

Y_GPS

Y position in meters.

Z_GPS

Altitude. Similar to the altitude as provided by the GPS.

Latitude_GPS

The latitude as provided by the GPS.

Longitude_GPS

The longitude as provided by the GPS.

s_Latitude_GPS

Uncertainty in latitude in meters as provided by the GPS. May be -1 if not known.

s_Longitude_GPS

Uncertainty in longitude in meters as provided by the GPS. May be -1 if not known.

Altitude_GPS

Altitude as provided by the GPS in meters.

s_Altitude_GPS

Uncertainty in the altitude in meters as provided by the GPS. May be -1 if not known.

Fix_Time_GPS

Fix time as provided by the GPS. As a fraction of a day (i.e. 0.75 stands for 18:00)

GPS_quality_GPS

Quality indication from the GPS. The meaning may differ for different brands of GPS systems.

GPS_system_GPS

Which system (GPS/GLONASS) was used by the GPS to determine the location

GPS_DOP_GPS

Dillution of position as provided by the GPS. An indication for the GPS quality. Lower numbers means a better accuracy.

Wall_clock_SPC

The time as provided by the spectrometer. Same format as before. In some cases, the spectrometer starts at 1 January 1970 after each reboot.

Real_time_SPC

The time elapsed during the recording of the spectrum in seconds.

Live_time_SPC

The actual time the spectrometer has been collecting data while recording the spectrum in seconds. Depending on the count rate, this number is normally slightly smaller than the real time

Cosmics_SPC

The number of counts in cosmics channel of the unprocessed gamma spectrum.

Total_counts_SPC

The total number of counts in the unprocessed, unstabilized spectrum, uncorrected for live time. This number depends on hardware settings and temperature! More info

Count_rate_SPC

The count rate in the unprocessed, unstabilized spectrum. This number depends on hardware settings and temperature! More info 

P (kPa) PTH

The pressure as measured by the PTH sensor

T (C) PTH

The temperature as measured by the PTH sensor

H (%) PTH

The humidity as measured by the PTH sensor

Voltage_1_ADC

The voltage read from ADC 1 in Volts.

Stab

Stabilization parameter a1, as determined during stabilization of the gamma spectrum.

The following columns appear only after processing

40-K

The activity for the radionuclide 40K in Bq/kg. To convert these numbers to PPM, read the section on Radiation unit conversions

S 40-K

The uncertainty for 40K in Bq/kg. The uncertainty is provided as one standard deviation.

Countrate

The count rate after stabilization and analysis of the gamma spectrum. This number does not depend on hardware settings and temperature. This number is usually much lower than the value in the Count_rate_SPC column, as only the analysis interval (typically 300 keV to 2900 keV) of the spectrum is taken into account. More info on count rates in Gamman.

Chi2

Quality of the fit. Gamman uses standard spectra to process the recorded gamma spectra. The Chi2 is an indication of how well the measured spectrum matches to the standard spectra. Chi2 should be a low number. If the number is too high, this means the recorded spectrum does not match properly with the standard spectra in the MCF file. Possible reasons may include:

  • Wrong calibration file selected

  • An unknown source of radiation

  • Outdated calibration




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