Sun Nuclear Corporation 1136 Manuel D’Utilisation
64
Section 4. Software operation
In TBI beams where the SSD is 300 to 400 cm, the instantaneous dose rate will be 1/10 of that at
100 cm. Here also, it may be advisable to remeasure the temperature coefficient for TBI applica-
tions. In different beam energies, the instantaneous dose rate within a pulse is typically within a
factor of 2 or 3 and should not contribute to measurable changes of temperature coefficient.
100 cm. Here also, it may be advisable to remeasure the temperature coefficient for TBI applica-
tions. In different beam energies, the instantaneous dose rate within a pulse is typically within a
factor of 2 or 3 and should not contribute to measurable changes of temperature coefficient.
To measure temperature coefficient
1
1
Position the diodes on a room-temperature phantom, in the same manner as used for dose
calibration. The phantom is required as a thermal mass during the test. See Figure 4-23 for
diode spacing.
calibration. The phantom is required as a thermal mass during the test. See Figure 4-23 for
diode spacing.
Figure 4-23. Place water bag over diodes prior to exposure
2
Connect and energize the Pod(s) you want to calibrate.
3
Click the Temperature Calibration view tab at the bottom of the screen. The Password dialog
box opens.
box opens.
4
Enter your PIN and click OK.
5
Now follow the on-screen “Check List” (Figure 4-24).
•
•
The Check List is in the upper right corner of the Temperature Calibration view.
•
Starting at the top, complete each item.
•
If a diode is being used on multiple setups, the same temperature calibration can be
applied to all setups by selecting each setup using that diode and selecting its input for
temperature calibration.
applied to all setups by selecting each setup using that diode and selecting its input for
temperature calibration.
•
For each item on the Check List, there may be Additional Instructions below.
•
When an item on the Check List is completed, click the check box and go to the next
item.
item.
•
Continue through the entire check list.
NOTE: The displayed temperature coefficients are in terms of fractional response change to a junc-
tion voltage change of the diode. The junction voltage is a linear function of temperature. The
junction voltage is measured with an analog to digital counter, displayed in “A2D” counts. There-
fore, the displayed temperature coefficient is not a very recognizable quantity.
tion voltage change of the diode. The junction voltage is a linear function of temperature. The
junction voltage is measured with an analog to digital counter, displayed in “A2D” counts. There-
fore, the displayed temperature coefficient is not a very recognizable quantity.
6
Validate the application of the temperature coefficients as follows: