LUDLUM 2350-1 User manual

MODEL 2350-1 Data Logger
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LUDLUM MODEL 2350-1
DATA LOGGER
Calibration Routines,
Parts List, and Schematics
August 1999
LUDLUM MEASUREMENTS, INC.
501 OAK ST., P.O. BOX 810
SWEETWATER,TX79556
915/235-5494; FAX: [phone]

MODEL 2350-1 Data Logger
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MODEL 2350-1 Data Logger
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TABLE OF CONTENTS
1. INITIAL INSTRUMENT CALIBRATION .........................................................................
1.1 Equipment Required .........................................................................................
1.2 Instrument Preparation .....................................................................................
1.3 Threshold and Window Calibration ...................................................................
1.4 High Voltage Calibration ...................................................................................
1.5 Overload Calibration .........................................................................................
1.6 Alarm Setpoints ................................................................................................
2. CALIBRATION ROUTINES ...........................................................................................
Source Parameters and Typical Values for Dead Time and Calibration Constants .
2.1 High Voltage Ramp Routine .............................................................................
2.2 Calibration Constant and Dead Time Calibration with background subtract .....
2.3 Calibration Constant Using a Single Point with Background Subtract ..............
2.4 Dead Time Calibration Using 2 Source Method with Background Subtract ......
3.THEORY OF OPERATION ............................................................................................
3.1 Amplifier/Power Supply Board ..........................................................................
3.2 Central Processor Board ..................................................................................
3.3 I/O Interface Board ...........................................................................................
3.4 64k Memory Expander Board ...........................................................................
4. PARTS LIST, COMPONENT LAYOUT, AND SCHEMATICS ..........................................
4.1 Amplifier / Power Supply Board Component Layout .........................................
4.2 Amplifier / Power Supply Board Schematic ......................................................
4.3 Central Processor Board Component Layout ...................................................
4.4 Central Processor Board Schematic ................................................................
4.5 64k Memory Expander Board Component Layout ............................................
4.6 64k Memory Expander Board Schematic .........................................................
4.7 I/O Interface Board Component Layout ............................................................
4.8 I/O Interface Board Schematic .........................................................................
4.9 Backplane Board Component Layout ...............................................................
4.10 Backplane Board Schematic ..........................................................................
4.11 Chassis Wireing Diagram ...............................................................................
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1. INITIAL INSTRUMENT CALIBRATION
1.1 Equipment Required
All instruments used in calibrating the Model 2350-1 must be calibrated by standards traceable to the
National Institute of Standards and Technology and must have a current calibration label attached.
1. Ludlum Model 500 Pulser.
2. High Impedance voltmeter with at least 1000 megohms meter resistance and an accuracy of 0.5%.
3. Overload simulator (1000 megohm resistor).
1.2 Instrument Calibration
The following procedures will calibrate the electronics only. To program the instrument please refer to
section 6. OPERATING INSTRUCTIONS of the Model 2350-1 Data Logger Manual.
WARNING:
The following procedures require that the instrument be re-initialized. This will clear all
logged data and return all programmable settings to their default values. DETECTOR
SETUPS AND LOGGED DATA WILL BE PERMANENTLY LOST.
1. Turn the Model 2350-1 ON. The display will temporarily go black and then the following two displays
will appear for a few seconds each. Then the display that was active when the instrument was
turned off will appear.
2. Re-initialize the instrument by entering the cold initialize command (SSR).
3. Check the battery voltage on the parameters display (SVD1). If it reads below 5.5 volts replace the
batteries with fresh alkaline batteries and proceed.
Threshold and Window Calibration
4. Change the display time base to minutes (SB1) display units to counts (SU7), and the threshold to
100 (T100).
5. Turn the Model 500 Pulser polarity switch to the negative position.
6. Set the pulse amplitude range selector to the 50 mV position, and the LO-HI control to the maximum
clockwise position.
7. Set the pulse frequency multiplier to the 1k position and adjust the pulse frequency so that the
output is 400k cpm.
8. Connect the Model 2350-1 to the Pulser and verify that the ratemeter reads between 392-408kC/m.
9. Adjust the pulser amplitude control until the meter reads approximately 10 mV. The ratemeter
display should read approximately 75% of the count input (300 kC/m).
MEMORY TEST OK
CPU TEST OK BATTERY VOLTAGE
BAT = 6.3

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1. INITIAL INSTRUMENT CALIBRATION
10. If the instrument does not read approximately 300 kC/m adjust the gain pot (R10) on the main
board until it reads properly.
NOTE: The instrument threshold is now set at 100 = 10 mV
11. Turn the window ON (WON), and set it to 100 (W100).
12. Adjust the pulse amplitude control until it reads approximately 20 mV. The ratemeter reading
should again indicate approximately 75% of the counts (300 kC/m).
13.Adjustthethresholdsettingto200(T200),300(T300),and400(T400)repeatingtheaboveprocedure
each time to verify that the threshold and window settings are linear.
14.Turn the window off (WOFF) and reset the threshold to 100 (T100).
High Voltage Calibration
15. Disconnect the instrument from the pulser and connect it to a high impedance voltmeter.
16. Set the high voltage to 1500 volts (H1500).
17. If the voltmeter does not read from 1498 - 1502 volts adjust the HV pot (R52) on the main board
until it reads within tolerance.
18. Adjust the high voltage to 500 volts (H500). The voltmeter should read between 490 - 510 volts.
19. Adjust the high voltage to 2000 volts (H2000). The voltmeter should read between 1940 - 2060
volts.
Overload Calibration
21. Disconnect the instrument from the voltmeter, and connect it to the overload simulator resistor
box.
22. Change to the Alarm Display (SVD3).
23. Turn the overload on (OON), and set it to 15.0 mA (O150).
24. Change to the Parameter Display (SVD1).
25. Set the high voltage to 1500 volts (H1500).
26. Change to the Main Display (SVD0). The ratemeter display at the top of the screen should be
alternating between the ratemeter display and the word OVERLOAD at approximately 1 second
intervals.
27. If this is not occuring adjust the OVERLOAD pot (R7) on the main board until the display alternates
properly.
28. Adjust the high voltage to 1000 volts (H1000). The overload indicator should stop appearing.
29. Adjust the overlaod to 10.0 mA (O100). The OVERLAOD indicator should again begin to alternate
with the ratemeter indicator.
30. Repeat steps 28 and 29 again with a voltage setting of 500 (H500) volts and an overload setting of
5 mA (O50).
31. When properly completed turn the overload alarm off (OOFF).

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1. INITIAL INSTRUMENT CALIBRATION
1.2 Instrument Calibration (cont.)
Alarm Checkout
1. Connect the Model 2350-1 to the pulser.
2. Set the pulse frequency to 600k cpm.
3. Select the Alarm Display (SVD3).
4. Set the integrated dose alarm to 100k cpm (P1E5).
NOTE: If an alarm is indicated press the ACK/SCRL button to silence the audio.
5. Select the Main Display (SVD0) and zero the integrated dose (SIZ). The Integrated dose counter
should start counting immediately and an alarm should be indicated when it reaches 100k cpm.
After the alarm press the ACK/SCRL button to silence the audio.
6. Select the Alarm Display(SVD3) and set the scaler alarm to 60,000 counts (K60000).
7. Return to the Main Display (SVD0), set the scaler count time to 6 seconds (F6), and take a scaler
count (C). When the scaler reaches 60,000 counts an alarm should again be indicated. Press
the ACK/SCRL button again to silence the audio.
8. Adjust the pulse frequency of the pulser to less than 600k cpm.
9. Select the Alarm Display (SVD3) and set the ratemeter alarm to 600k cpm (J6E5).
10. Select the Main Display (SVD0) and readjust the pulse frequency to a setting of 600k cpm. The
ratemeter alarm should be triggered. Press the ACK/SCRL button to silence the audio.
11. Verify that the ratemeter (RAT), scaler (SCL), and integrated dose (DOS) indicators are all
alternating with the alarm (ALM) indicators at 1 second intervals.
12. Select the alarm display (SVD3)
13. Set all of the alarms to their default high settings (ratemeter, J1E9; scaler, K1000000;
integrated dose, P1E9)
14. Select the Main Display (SVD0) and reset all of the alarm indicators (X).
15. Disconnect the instrument from the pulser and place it into the instrument can.
The electronics have now been calibrated and functionally checked. All remaining calibration
procedures involve setting the programmable parameters of the instrument and are covered in the
Model 2350-1 Data Logger Instruction Manual.

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2. CALIBRATION ROUTINES
SOURCE PARAMETERS AND TYPICAL VALUES FOR MODEL 2350-1 CALIBRATIONS
To insure that the proper sized sources are used in calculating the calibration constant, and
dead time of the Model 2350-1 and detectors the following calculation should be performed.
% Dead Time Loss = No. of source counts in 1 second X Dead Time (in seconds)
The following list provides some typical LO and HI cal points and dead times for various
detectors:
TYPICAL DEAD TIME CALIBRATION, AND OVERLOAD POINTS
TYPICAL DEAD TIME AND CALIBRATION CONSTANT SETTINGS
DETECTOR DEAD TIME CALIBRATION CONSTANT
44-2 15 - 25 µsec. 1.0e10 - 0.3e10
44-6 65 - 135 µsec. 7.09e7- 0.65e7
44-7 250 - 270 µsec. 1.39e8- 0.1e8
44-9 50 - 120 µsec. 2.0e8- 0.3e8
44-38 65 - 135 µsec. 7.09e7- 0.65e7
43-68 Alpha 15 - 25 µsec. 1
43-68 Beta 18 - 26 µsec. 1
43-37 Alpha 18 - 20 µsec. 1
43-37 Beta 19 - 25 µsec. 1
DETECTOR LOW POINT HIGH POINT OVERLOAD POINT
44-2 500 µR/hr 15 mR/hr 100 mR/hr
44-6 20 mR/hr 400 mR/hr 1 R/hr
44-7 5 mR/hr 100 mR/hr N/A
44-9 6 mR/hr 200 mR/hr 1 R/hr
44-38 20 mR/hr 400 mR/hr 1 R/hr
44-116 6 mR/hr 60 mR/hr N/A

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The high voltage ramp routine is useful when a user needs to plateau a detector to
determine the proper operating voltage of the detector.The following display will appear when
performing the routine.
HV?
SCL
SCL
INC
SEC
END
10
0
CURRENT HV = 800
STR
PROCEED W/
000
OPR CNT = 0
A
B
C
D
E
F
G
I
H
HIGH VOLTAGE RAMP ROUTINE DISPLAY
A. INFORMATION PROMPT: Prompts the user for the parameters required for the ramping
routine. When the routine is first started the prompt will ask if the user wants to proceed
with the current parameters. If answeredYES the instrument will then prompt the user to
begintheroutinebyexecuting the scalercountcommand.If answered NO thenthefollowing
information prompts will appear immediately after the one before is answered.
Starting HV ?
Ending HV?
HV Increment?
The message DUMPING HEADER will then appear momentarily followed by the command
"Ent C to start".
B. RATEMETER BARGRAPH DISPLAY: A logarithmic display of the ratemeter reading in
cps.
C. HV IDENTIFIER: Identifies the current HV setting.
D. STR: Identifies the starting voltage of the HV ramping routine.
E. SCALER COUNT: Shows the scaler reading in progress.
F.SCALERTIMER: Shows the count time for the scaler.When a count is in progress the timer
will show the time remaining in the count.
G. END: Identifies the ending HV setting for the ramping routine.
H. INC: Identifies the increment the voltage will be increased by in each step of the routine.
I. OPR CNT: Identifies the count at the beginning knee of the plateau or the recommended
operating voltage.
2.1 HighVoltage Ramp Routine
2. CALIBRATION ROUTINES

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2. CALIBRATION ROUTINES
KEYSTROKES
SHR(x) ENTER
Where (x) = the number 0 or 1.
0 = Disables data dump to the serial port.
1 = Enables data dump to the serial port.
N ENTER
500 ENTER
1000 ENTER
25 ENTER
C ENTER
RESPONSE
The Model 2350 display will show the detector
displaywiththe current setofdetectorparameters.
There will be no prompt but you will need to select
a set of parameters to use in the routine. If the
current parameters are correct press "Y ENTER",
otherwise select the set of detector parameters
that you want to use and then press "Y ENTER".
The instrument will proceed with the routine by
displayingthescreen shown ontheoppositepage.
This answers the prompt
"PROCEED W/ HV" allowing the user to change
the parameters of the routine.
This set the beginning high voltage at 500
volts.
This sets the ending high voltage at 1000
volts.
This sets the HV increment to 25 volts.
(Thisincrementis theamountthatthe highvoltage
setting will change between each step of the
rampingroutine.)
This activates the routine by starting the
scaler counting.
"SHR0" will run the plateau routine, determine the operating votage, but will not dump
data to the RS-232 port. "SHR1" will run the plateau routine, determine the operating voltage,
and will dump the voltage setting and scaler count at each increment of the plateau routine.
When the routine is complete the following prompt will appear:
"SAVE? HV = XXX"
"Y ENTER" will save the voltage as the operating voltage of the detector and the
instrument will return to the screen that was active prior to the exucution of the routine. "N
ENTER" will return to the screen that was active prior to the exucution of the routine without
saving the voltage.
The following example demonstrates how to run a plateau on a Model 44-2 Gamma
Scintillator.
Note: Before performing the SHR(x) command,certain parameters must be set. The parameters
that need to be set include the threshold, window position, and count time.

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E
2. CALIBRATION ROUTINES
This routine will use a two point (low-hi) method to calculate the calibration constant
and dead time of the detector.The following display will appear when performing the routine.
L CAL 0.000e+00
H CAL 0.000e+00
LOW CAL POINT?
LO SMPL 0
HI SMPL 0
A
B
C
D
F
CALIBRATION CONSTANT/DEAD TIME ROUTINE DISPLAY
A. INFORMATION PROMPT: Prompts the user for the parameters required for the routine.
When the routine is first started the prompt will prompt the user low calibration point. Once
entered it will prompt for the following parameters in order.
HI CAL POINT
TAKE BACKGROUND
TAKE LOW SAMPLE
TAKE HI SAMPLE
SAVE NUMBERS?
B. RATEMETER BARGRAPH DISPLAY: A logarithmic display of the ratemeter reading in
cps.
C. L CAL: Identifies the low calibration point that will be used in the routine.
D. H CAL: Identifies the high calibration point that will be used in the routine.
E. LO SMPL: Shows the reading obtained from the low sample source.
F. HI SMPL: Shows the reading obtained from the high sample source.
NOTE: Line 1 will indicate the ratemeter reading when a sample is being taken,
and lines 3 and 4 will show the scaler taking a count.When the routine is
complete Line 3 will display the calculated calibration constant, and line
4 will show the calculated dead time constant. These numbers will be
saved into the active detector setup if the user answers yes to the prompt
to save the numbers.
2.2 Calibration Constant and DeadTime Calibration with Background Subtract