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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. 


Header labelDescription
Spectrum noA 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
X_GPSX position in meters. This is data is created by convertin from WGS84 latitude/longitude to the UTM coordinate system. Metric coordinates allow for easy calculation of distances.
Y_GPSY position in meters.
Z_GPSAltitude. Similar to the altitude as provided by the GPS.
Latitude_GPSThe latitude as provided by the GPS.
Longitude_GPSThe longitude as provided by the GPS.
s_Latitude_GPSUncertainty in latitude in meters as provided by the GPS. May be -1 if not known.
s_Longitude_GPSUncertainty in longitude in meters as provided by the GPS. May be -1 if not known.
Altitude_GPSAltitude as provided by the GPS in meters.
s_Altitude_GPSUncertainty in the altitude.
Fix_Time_GPSFix time as provided by the GPS. As a fraction of a day (i.e. 0.75 stands for 18:00)
GPS_quality_GPSQuality indication from the GPS. The meaning may differ for different brands of GPS systems.
GPS_system_GPSWhich system (GPS/GLONASS) was used by the GPS to determine the location
GPS_DOP_GPSDillution of position as provided by the GPS. An indication for the GPS quality. Lower numbers means a better accuracy.
Wall_clock_SPCThe 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_SPCThe time elapsed during the recording of the spectrum in seconds.
Live_time_SPCThe 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_SPCThe number of counts in cosmics channel of the unprocessed gamma spectrum.
Total_counts_SPCThe 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_SPCThe count rate in the unprocessed, unstabilized spectrum. This number depends on hardware settings and temperature! More info 
Voltage_1_ADCThe voltage read from ADC 1 in Volts.
StabStabilization parameter a1, as determined during stabilization of the gamma spectrum.
40-KThe activity for 40K in Bq/kg. To convert these numbers to PPM, read the section on Radiation unit conversions
S 40-KThe uncertainty for 40K in Bq/kg. The uncertainty is provided as one standard deviation.
CountrateThe 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.

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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