**4. Automated sample positioning system for gamma spectrometry**

Automation allows greater control of counting geometries, less error in positioning, increased productivity in the analyses, increased control and quality assurance of the analytical data and decreased doses received by the staff [18].

The automated system developed in the NAA laboratory fulfills the following objectives: Programming of analysis sequences, opening and closing of shields for sample positioning in the detector, and communication with the software for data acquisition. This has improved productivity by enabling 24/7 operation, and as a side benefit there is also less exposure to ionizing radiation.

This system is based on electromechanical components that can handle up to 64 sample readings in the same sequence of analysis, for which each step includes the collection of the sample from a sample rack, the positioning of the sample in the detector, data acquisition at pre-defined reading times, and the return of the sample to the rack where the other samples are located.

All of this is possible by means of a high precision positioning system based on linear actuators. The system is controlled by a human machine interface (HMI) where execution commands can be programmed. **Figures 21**–**24** show how everything is set up.

In principle, the presence of personnel in the gamma spectrometry room is limited while the positioning system is in operation. However, shielding for the sample rack is to be installed in the near future for radiological protection purposes.

**Figure 21.** Positioning system: 1. Detector A; 2. X-axis linear actuator; 3. Sample rack (64 positions); 4. Detector B; 5. Y-axis linear actuator; 6. Z-axis linear actuator; 7. Detector C; 8. Detector D; 9. Control panel.

Precision is determined by servomotors that provide the movement, which have a resolution of 1,048,576 pulses/revolution per axis. Coupled to the previously described servomotors, there are linear belt actuators (Accuracy ±1.0 mm) with their respective guides for alignment

**Figure 23.** Positioning system: 1. Electric motor to open/close shielding; 2. Shield sensor for opening; 3. Shield sensor for

Colombian Neutron Activation Analysis Laboratory (CNAAL): Applications and Development…

http://dx.doi.org/10.5772/intechopen.74395

45

closing; 4. Emergency stop; 5. Sample gripper; 6. Detector sample support; 7. Actuator motion limit sensor.

The system has two spatial adjustment options, point-to-point which displays the 64 positions of the sample rack and the 4 detector positions; and also single-point which is used to correct a common mismatch in all points using the point-to-point option, defining the first position of the rack, and allowing for the automatic adjustment of all the other positions. Both of these

and friction reduction throughout the working area.

**Figure 24.** Positioning system.

options are password protected for security reasons.

**Figure 22.** Positioning system: 1. HMI; 2. Emergency stop; 3. System status; 4. Electronic components; 5. Power control.

Colombian Neutron Activation Analysis Laboratory (CNAAL): Applications and Development… http://dx.doi.org/10.5772/intechopen.74395 45

**Figure 23.** Positioning system: 1. Electric motor to open/close shielding; 2. Shield sensor for opening; 3. Shield sensor for closing; 4. Emergency stop; 5. Sample gripper; 6. Detector sample support; 7. Actuator motion limit sensor.

**Figure 24.** Positioning system.

The automated system developed in the NAA laboratory fulfills the following objectives: Programming of analysis sequences, opening and closing of shields for sample positioning in the detector, and communication with the software for data acquisition. This has improved productivity by enabling 24/7 operation, and as a side benefit there is also less exposure to

This system is based on electromechanical components that can handle up to 64 sample readings in the same sequence of analysis, for which each step includes the collection of the sample from a sample rack, the positioning of the sample in the detector, data acquisition at pre-defined reading times, and the return of the sample to the rack where the other samples are located.

All of this is possible by means of a high precision positioning system based on linear actuators. The system is controlled by a human machine interface (HMI) where execution com-

In principle, the presence of personnel in the gamma spectrometry room is limited while the positioning system is in operation. However, shielding for the sample rack is to be installed in

**Figure 21.** Positioning system: 1. Detector A; 2. X-axis linear actuator; 3. Sample rack (64 positions); 4. Detector B; 5.

**Figure 22.** Positioning system: 1. HMI; 2. Emergency stop; 3. System status; 4. Electronic components; 5. Power control.

Y-axis linear actuator; 6. Z-axis linear actuator; 7. Detector C; 8. Detector D; 9. Control panel.

mands can be programmed. **Figures 21**–**24** show how everything is set up.

the near future for radiological protection purposes.

44 Advanced Technologies and Applications of Neutron Activation Analysis

ionizing radiation.

Precision is determined by servomotors that provide the movement, which have a resolution of 1,048,576 pulses/revolution per axis. Coupled to the previously described servomotors, there are linear belt actuators (Accuracy ±1.0 mm) with their respective guides for alignment and friction reduction throughout the working area.

The system has two spatial adjustment options, point-to-point which displays the 64 positions of the sample rack and the 4 detector positions; and also single-point which is used to correct a common mismatch in all points using the point-to-point option, defining the first position of the rack, and allowing for the automatic adjustment of all the other positions. Both of these options are password protected for security reasons.

The point-to-point adjustment option must be used to change the counting geometry on the detectors, which must be performed prior to the execution of the sequences as required by the operators.

This positioning system greatly reduces manual efforts during the analysis of radioactive samples; the only manipulation required by our staff is the setup of the 64 samples in the rack. The idea of the use of this rack is minimizing Radiation Exposure, and thus enhancing the safety and well-being of personnel.
