DGA-C High Sensitivity Focused Gamma Tool
DGA-C
High Sensitivity Directional Gamma Tool (1.36” OD)
The DGA-C High Sensitivity Gamma Tool is ideal for Azimuthal Geosteering applications. It is a Tungsten-collimated version of the NGT-T gamma tool and has 50% higher sensitivity than the DGA. These tools are sometimes referred to as “focused” or “shielded” gamma tools. In this design, a 78° “window” is machined along the length of the Tungsten shield that surrounds the crystal/phototube detector. Only gamma ray entering from the formation through this window can be detected and counted. When aligned with the tool face or other physical reference, the DGA-C indicates the direction from which gamma ray energies originate.
The DGA-C is interchangeable with the standard NGT-T gamma tool just like the DGA. Because of the required thickness of the Tungsten shield, the Nal(TI) scintillator crystal is a smaller diameter and a longer length than the NGT-T’s to provide maximum sensitivity. The DGA-C crystal diameter and length are both larger than the DGA’s, offering greater volume to provide higher sensitivity.
To protect your gamma investment and ensure the best performance use CBG original SNB Snubbers-Shock & Vibration Isolators.
DGA-C
High Sensitivity Directional Gamma Tool (1.36” OD)
The DGA-C, High Sensitivity Directional Gamma Tool, is a Tungsten-collimated version of the NGT-T gamma tool and has 50% higher sensitivity than the DGA. This is due to its custom designed tungsten shield and larger crystal size. These tools are sometimes referred to as “focused” or “shielded” gamma tools. In this design a 78° “window” is machined along the length of the Tungsten shield that surrounds the crystal/phototube detector. Only gamma ray entering from the formation through this window can be detected and counted. When aligned with the tool face or other physical reference, the DGA-C indicates the direction from which gamma ray energies originate.
The DGA-C is interchangeable with the standard NGT-T gamma tool just like the DGA. Because of the required thickness of the Tungsten shield, the Nal(TI) scintillator crystal is a smaller diameter and a longer length than the NGT-T’s to provide maximum sensitivity. The DGA-C crystal diameter and length are both larger than the DGA’s, offering greater volume to provide higher sensitivity.
To protect your gamma investment and ensure the best performance use CBG original SNB Snubbers-Shock & Vibration Isolators.
DGA-C Specifications
P/N 202-100-000
| Detector | Scintillator Crystal | Sodium Iodide, Na(TI) |
|---|---|---|
| Photomultiplier | R3991A (Hamamatsu) | |
| Mechanical | Diameter (OD) | 1.36” |
| Length (make-up) | 13.7” | |
| Weight | 3.0 lb | |
| End Connectors | Micro-D Subminiature, 15-Pin | |
| Material | Aluminum Alloy (chassis), Tungsten (shield) | |
| Performance | Sensitivity | 0.52* CPS/API |
| Front/Back Count Ratio (using source at 6”) | 14.0 using Barium-133 2.72 using Cesium-137 |
|
| Accuracy | +/- 5% to 150°C +/- 10% to 175°C |
|
| Environmental | Operating Temperature | -18°C to 175°C |
| Survival Temperature | -40°C to 200°C | |
| Heat/Cool Rate, Max. | 2.8°C (5°F) per minute | |
| Vibration (3 axis) 50-1000Hz, Random | 30G (20G RMS) | |
| Shock (3 axis) | 1000G, 0.5ms, half-sine | |
| Power Requirements | DC Input Voltage | 17-48 VDC, 50VDC Max. |
| Tool Current | 8-11 mA | |
| Output Signal | Negative Pulse | +5V to GND, 5 uSec width |
* Counts are collected with gamma tool mounted within a standard BeCu pressure barrel, (OD 1.875″, ID 1.500″). API Calibration performed with AEA Technology, QSA Inc., KUTh Field Verifier #188074, S/N 255 Radionuclides: K-40(11.7%), U-238(90 ppm), Th-232(40 ppm).