Sun Nuclear Corporation 1136 Manuel D’Utilisation
78
Section 5. Reference information
Data collection
At the beginning of the measurement, when the Pod is told to start measuring, the 16 millisecond
counter is zeroed. During Measurement, calculate the Dose and Rate from the FIFO array as
follows:
counter is zeroed. During Measurement, calculate the Dose and Rate from the FIFO array as
follows:
Dose:
where DA, DB, DC, DD are the dose values for channels A, B, C, D and CF
btn,A
, CF
btn,B
, CF
btn,C
,
CF
btn,D
, are the Calibration Factors for channels A, B, C, D on energy button ‘btn.’ (Tempcf)
btn,cnr
is defined below, cn
r
being A, B, C, D. This assumes that the timer counter was zeroed, i.e., A1,1
is the true elapsed time since pressing the energy key.
Rate:
where the RA, RB, RC, RD are the dose rate values for channels A, B, C, D during the past time
interval of A
interval of A
1,1
to A
2,1
.
Temperature correction factor
This section describes how the IVD Control Module allows users to set up temperature compen-
sation for their diodes.
sation for their diodes.
The routines are accessed from the “Temperature Coef” item from the main menu. A PIN code is
required to proceed, followed by 1 to 4 serial numbers. After the serial numbers are selected and
enter is pressed, the display then scans the active Pod’s calibration files, flagging as selectable
those which contain any of the chosen serial numbers. You can then choose which calibration(s)
are to be adjusted.
required to proceed, followed by 1 to 4 serial numbers. After the serial numbers are selected and
enter is pressed, the display then scans the active Pod’s calibration files, flagging as selectable
those which contain any of the chosen serial numbers. You can then choose which calibration(s)
are to be adjusted.
Two coefficients are associated with each diode pertaining to temperature: Tc and V’. Tc is the
diode’s change in sensitivity with respect to temperature. Its label is percent per degree Celsius.
A typical value for this is 0.5%/deg, which is stored internally as 50. V’ is a factor which allows the
IVD display to determine relative diode temperature from the diode’s junction voltage. Its units are
millivolts per degree Celsius (typical value, -2.0mV/deg, which is stored as 200). Formulae for Tc
and V’ are provided below.
diode’s change in sensitivity with respect to temperature. Its label is percent per degree Celsius.
A typical value for this is 0.5%/deg, which is stored internally as 50. V’ is a factor which allows the
IVD display to determine relative diode temperature from the diode’s junction voltage. Its units are
millivolts per degree Celsius (typical value, -2.0mV/deg, which is stored as 200). Formulae for Tc
and V’ are provided below.
After you select your calibrations, you are presented with the option of either entering Tc and V’
manually for each detector, or finding the coefficients through an experiment. If they are entered
manually, the values are simply stored in the selected calibrations for the selected detectors, and
the setup is complete.
manually for each detector, or finding the coefficients through an experiment. If they are entered
manually, the values are simply stored in the selected calibrations for the selected detectors, and
the setup is complete.
For diodes with unknown coefficients, or to verify a coefficient, the IVD allows for an experiment
instead of manual entry.
instead of manual entry.
Materials required for the experiment:
•
An IVD system with diodes connected
•
A 3 cm thick acrylic or solid water phantom
•
A laboratory thermometer with 0.1 degree C resolution
DA
A
1 2
,
A
1 1
,
–
BKGA
⋅
[
] CF
btn A
,
Tempcf
(
)
btn A
,
⋅
⋅
=
DB
A
1 3
,
A
1 1
,
–
BKGB
⋅
[
] CF
btn B
,
Tempcf
(
)
btn B
,
⋅
⋅
=
DC
A
1 4
,
A
1 1
,
–
BKGC
⋅
[
] CF
btn C
,
Tempcf
(
)
btn C
,
⋅
⋅
=
DD
A
1 5
,
A
1 1
,
–
BKGD
⋅
[
] CF
btn D
,
Tempcf
(
)
btn D
,
⋅
⋅
=
RA
A
1 2
,
A
2 2
,
–
(
)
A
1 1
,
A
2 1
,
–
(
)
–
BKGA
⋅
[
] CF
btn A
,
Tempcf
(
)
btn A
,
⋅
⋅
=
RB
A
1 3
,
A
2 3
,
–
(
)
A
1 1
,
A
2 1
,
–
(
)
–
BKGB
⋅
[
] CF
btn B
,
Tempcf
(
)
btn B
,
⋅
⋅
=
RC
A
1 4
,
A
2 4
,
–
(
)
A
1 1
,
A
2 1
,
–
(
)
–
BKGC
⋅
[
] CF
btn C
,
Tempcf
(
)
btn C
,
⋅
⋅
=
RD
A
1 5
,
A
2 5
,
–
(
)
A
1 1
,
A
2 1
,
–
(
)
–
BKGD
⋅
[
] CF
btn D
,
Tempcf
(
)
btn D
,
⋅
⋅
=