BGG-01 Borehole Spectral Density Probe

The BGG-01 is a fully digital spectral density probe that samples 256 channels of backscatter gamma rays over the energy range of 50 keV to 1.5 MeV. The emitter is a sealed Cs137 gamma source with a 36cm source to detector spacing. The source is a single peak emitter at the energy of 662 keV and a strength of 5mCi. The total backscatter spectrum is integrated over 1 second. The detector used in the density probe is a 25mm by 76 mm crystal ( 1”x 3 “ CsI ). When not in use the source is stored in a lockable shielded container.

The spectral density probe is designed for use with all IFG logging systems that include the BIN-04 digital data interface, 4 conductor logging cable and the data acquisition software. The probe is controlled by an on-board microprocessor that transmit the digital values (Spectrum) along the logging cable to the surface console (BIN-04) for the re-formatting and transferring to a microcomputer.

The microcomputer and the acquisition software (GDAS) displays and records the data in real time. The acquisition software allows up to 10 energy windows to be displayed and examined during logging. The data can be viewed in either graphic or numeric format. For improved statistics, individual spectrums can be accumulated up to 4 minutes in continues or incremental logging mode.

Post processing software (Spectra) is available to display and process the recorded spectrum data. This software is used to calibrate the gamma spectrum and to compute up to a maximum of 10 energy windows. The output data is in column ASCII format, for recording to a data file.

Detector Type Nal crystal, resolution 7.5%
Csl crystal, resolution 9.5%
BOG crystal, resolution 15.5%
Detector Size 25mm x 76mm
Gamma Source Cs137 , 5m Curie (0.1887 GBq)
Spacing 36cm
Sample Period 1 second
Sectrum Channels 50 keV to 1.5 MeV range Resolution
5.86 KeV per channel
Probe Housing Stainless Steel
Maximum Depth 2000 meters
Connection 4 pin connector (Gearhardt Owen)
Temperature Range Storage: -35°C to +70°C
Operating: 0°C to +70°C
Output 10mA current loop, 4800 baud
Supply Voltage 24Vdc @ 0.2A (at probe header)
Probe Dimensions 40mm diameter x 133cm long
Probe Weight 4.5 kg

Larger diameter detectors are available on special order. The larger detector sizes increase the probe diameter to:

38mm x 76mm Detector Probe diameter = 52 mm Weight = 5.5 kg
50mm x 76mm Detector Probe diameter = 65 mm Weight = 6.6 kg
76mm x 76mm Detector Probe diameter = 90 mm Weight = 9.0 kg