Spectrum Techniques STU ST365 User manual

User Manual
February 4, 2022
IMPORTANT NOTE
The ST365 Webpage Control application is included as a part of
each Spectrum Techniques ST365 hardware device. In order
to access this application it is necessary that the ST365 device
be LAN-connected to your network. With the device powered
on you may use a computer, smart phone, or tablet that is
connected to the same network to open a Chrome browser
window. From within this browser window you navigate to the
URL for the given ST365 device. Click the menu item labeled
“ST365 Webpage” to launch the control application.
Spectrum Techniques, LLC
106 Union Valley Road
Oak Ridge, TN 37830
Phone
[phone]
Fax
[phone]
E-mail
[e-mail]
Web Site
spectrumtechniques.com

2 Spectrum Techniques ST365 Webpage Rev. 1
Contents
Introduction ................................................................................................................................................. 3
System Setup ............................................................................................................................................... 3
Accessing the ST365 Webpage ................................................................................................................... 3
ST365 Home Page ........................................................................................................................................ 5
USING YOUR ST365 DEVICE ........................................................................................................................6
Assigning Parameter Values................................................................................................................... 11
Counts Command................................................................................................................................ 11
Plateau Experiment Command ..........................................................................................................13
Plateau Experiment Setup..................................................................................................................13
Plateau Experiment ............................................................................................................................15
Half-Life Experiment Command........................................................................................................ 18
Half-Life Experiment Setup ............................................................................................................... 18
Half-Life Experiment .......................................................................................................................... 19
Data Table....................................................................................................................................................21
Data Graph ................................................................................................................................................. 22
SYSTEM OPERATION ................................................................................................................................. 23
Basic GM Tube Setup and Operation.................................................................................................... 23
GM Tubes............................................................................................................................................ 24
GM Tube Plateau................................................................................................................................ 24
Creating a Plateau Chart.................................................................................................................... 24
Running the unit as a stand-alone unit ......................................................................................... 24
Using the ST365 application software.............................................................................................. 24
Resolving Time................................................................................................................................... 25
The Wipe Test System ...........................................................................................................................26
The Wipe Test.....................................................................................................................................26
Checking the System Calibration ...................................................................................................... 27
Taking a Background Reading........................................................................................................... 27
Measuring Wipes ............................................................................................................................... 27
System Re-calibration ........................................................................................................................ 27
Warranty and Repair Information..................................................................................................... 28

3Spectrum Techniques ST365 Webpage Rev. 1
Introduction
The purpose of this guide is to help you learn to use the ST365 Webpage application with your
Spectrum Techniques hardware device. The ST365 webpage allows the user to copy data to
your device’s clipboard and to use features described in the Using Your ST365 Device section
found later in this document. The webpage is located on a web server that resides within your
ST365 device.
System Setup
Connect a detector probe to your ST365 device. Note that each ST365 device has connector
jacks on the back of the box for connecting to Geiger-Mueller and Scintillator detectors.
Connect the detector you have available to the appropriate jack on your device. You should
follow the procedure outlined in the ST365 Spectrum Techniques setup manual when doing this.
Accessing the ST365 Webpage
The following discussion assumes that your ST365 device is already LAN-connected to your
network and the device is powered on. Further, this discussion assumes that you already know
the IP address of your ST365 device on your network. If you do not already know your ST365
device’s IP address, then you can use the Texas Instruments software utility called Finder.exe
to find it. This utility will help you find the IP address your ST365 device and all other ST365
device’s on your LAN.
Using a computer, smart phone, or tablet that is connected to the same network as your ST365
device open a Chrome browser window. From within the browser address bar enter the IP
address of your ST365 device. Doing this causes the browser window to display the following
page.

4Spectrum Techniques ST365 Webpage Rev. 1
Figure 1
The webpage you see is hosted by a web server located inside your ST365 device. The menu
buttons displayed in green are used to access various features of the device.
Click the menu button labeled ST365 Webpage. After a moment a new browser window
appears that looks like this:

5Spectrum Techniques ST365 Webpage Rev. 1
Figure 2
ST365 Home Page
Figure 2 shows the ST365 home page. This is your starting point for controlling your ST365
device through the web server. This is how the page initially looks each time you access the
device. Note that the page is oriented vertically. This is so as to accommodate how users
normally hold a smart phone when using their phone.
Note in Figure 2 that there is a red button labeled Click to Control ST365. This document refers
to this as the control button. This button is always visible regardless of what operation you
perform within the webpage. As long as the control button contains the label Click to Control
ST365 you do not have control of the ST365 device. The device will ignore any commands you
attempt to send to it. Occasionally, you might find that the device quits responding to your
commands. This could happen because someone else has acquired control of the device while
you were still using it. When this happens the next command button you click will cause this
message to appear:
Figure 3
This message tells you that someone has used another browser window to take control of the
same ST365 device that you have been using and that you no longer have control of the device.
The only option you have at this point is to click the Continue button. Doing this takes you back
to the webpage shown in Figure 2 above. Notice that the control button now says Click to
Control ST365.
This method of acquire-and-release exists in your ST365 LAN-connected device because of the
possibility that another user might go to its internal webpage and attempt to control the device at
the same time you are using it. To prevent two users from having control of the same device at

6Spectrum Techniques ST365 Webpage Rev. 1
the same time the web server uses a lockout mechanism that assures that only one user may
control a given ST365 device at a time.
To take control of the ST365 device click the control button. Assuming the device is not already
in use the control button will turn green and its label will update to say Click to Release ST365.
In the case where someone else is currently controlling the device the control button will instead
turn yellow and its label will update to say Locked by another user. Continue? If you click the
control button again the web server will disconnect the other user and give you control of the
ST365 device. The control button within your browser window turns green and its label updates
to say Click to Release ST365. As a courtesy to others you should take control of an ST365
device only after you have assured that the device is not in use by someone else. There is no
technical way to prevent a user from taking control of an already-in-use ST365 device.
When you first gain control of the ST365 device the home page updates to look like this:
Figure 4
When you are finished controlling the ST365 device you should click the control button again.
Doing this notifies the web server that the device has been released from use and is now
available for the next user to acquire control of the device and to begin using it. The control
button updates to say Click to Control ST365. This indicates that the ST365 device is ready for
someone else to take control of it and to begin using it.
USING YOUR ST365 DEVICE
The ST365 home page is comprised of five pushbuttons and two dropdown menus. The control
button is used to acquire and release control of the ST365 device. The function of this button
was described previously in this manual in the section entitled ST365 Home Page. The
following discussion assumes that the user has used the control button to acquire control of
their ST365 device and that the web server is now displaying its home page.

7Spectrum Techniques ST365 Webpage Rev. 1
Along the top row of the webpage is a button that says OFF. This is the high voltage button and
is used to toggle the high voltage on and off. Click this button once to turn the ST365 device
voltage on. The button now says ON. Click it once again to turn the ST365 device voltage off.
Notice that when the high voltage is off the button says OFF and is colored red. When the high
voltage is on the button says ON and is colored green. There is a physical button labeled HV
ON/OFF located on the ST365 device. See Figure 5 for location of HV ON/OFF button circled
in red.
Figure 5
The LED on this button will light up in green when the user toggles the high voltage button on
within the webpage. The LED on this button will go dark when the user toggles the high voltage
button off within the webpage.
Immediately below the control button is a Display dropdown menu. See Figure 6.
Figure 6
This menu allows the user to select from one of seven display options for the device. These
options are:
Counts
Counts per Second
Counts per Minute

8 Spectrum Techniques ST365 Webpage Rev. 1
Elapsed Time
High Voltage
Probe Type GM Tube
Probe Type Scintillator
Select any one of these seven display options to cause the information displayed in the Display
window to change. Initially, the text shown at the top of this window says Counts. However, the
user may change this to say Counts / Second, Counts / Minute, Elapsed Time, or High Voltage.
The number shown immediately below this text is the value of the selected display option.
Initially, the text shown at the bottom of this window says Probe Type:. However, the user may
change this to say Probe Type: GM Tube or Probe Type: Scintillator. Setting the probe type in
this manner instructs the ST365 device to use the corresponding jack on the back of the device
when acquiring count data from an attached probe.
Immediately below the Display dropdown menu is the Mode dropdown menu. See Figure 7.
Figure 7
This menu allows the user to select from one of nine mode options for the device. These
options are:
Home
Plateau Experiment
Half-Life Experiment
Set Preset Time
Set Preset Runs
Set Pause Time
Set High Voltage

9Spectrum Techniques ST365 Webpage Rev. 1
Data Table
Data Graph
Select any one of these nine mode options to initiate a mode change for your ST365 device.
Approximately midway down the webpage is a horizontal blue bar that extends the entire width
of the webpage. This is the Display window for the page. See Figure 8 for the location of the
Display window outlined in red.
Figure 8
Immediately below the Display window is a row of three pushbuttons. See Figure 9.

10 Spectrum Techniques ST365 Webpage Rev. 1
Figure 9
These are the Start Counts button, the Stop Counts button, and the Clear Counts button. The
Start Counts button is shown in Figure 10.
Figure 10
Click the Start Counts button to instruct the ST365 device to begin counting.
The Stop Counts button is shown in Figure 11.
Figure 11
Click the Stop button to instruct the ST365 device to stop counting.
The Clear Counts button is shown in Figure 12.
Figure 12
Click the Clear Counts button to reset the counts and the elapsed time to zero (0) as shown in
the Display and Elapsed Time windows.
Immediately below this row is a 3 x 2 grid of blue boxes. See Figure 13.

11 Spectrum Techniques ST365 Webpage Rev. 1
Figure 13
Taken together these six boxes show the current parameter settings for your ST365 device. As
you interact with your device the parameters displayed here may change depending on the
operation you are performing with your ST365 device.
Assigning Parameter Values
There are seven parameters available for assignment by the user. These are:
Preset Time
Preset Runs
Pause Time
High Voltage
Start Voltage
End Voltage
Step Voltage
The settings for these parameters determine how your ST365 device behaves when it executes
one of three possible counting commands. These commands are named Counts, Plateau
Experiment, and Half-Life Experiment. Not all of these commands use all seven parameters
when executing a command. The following discussion describes each of these commands in
detail and discusses which parameters are used by each command.
Counts Command
The Counts Command is the simplest of the three commands. There are four parameters used
by this command and that control how it operates. They are:
Preset Time
Preset Runs
Pause Time
High Voltage

12 Spectrum Techniques ST365 Webpage Rev. 1
The Preset Time parameter determines the amount of time (in seconds) that the ST365 device
spends counting in order to obtain a counts result. If you leave this parameter set to zero, then
the device will continue counting until you tell it to stop.
The Preset Runs parameter determines the number of times that the ST365 device counts
starting at zero up to the preset time. If you leave this parameter set to zero or set to one, then
when you start counts the device will only count for preset time seconds and then stop. If you
set this parameter to the value of two or larger, then when you start counts the device will count
multiple times in a row based on the preset time and preset runs that you specified.
The Pause Time parameter determines the amount of time (in seconds) that the ST365 device
waits before starting another run. This parameter applies when the Preset Runs parameter is
set to a value of two or larger. If you leave Pause Time set to zero, then there will be no time
delay between runs. Setting Pause Time to a non-zero value is useful when you have the
device configured for several preset runs and your want to see what the counts are at the end of
each run before the next run starts.
The High Voltage parameter determines the voltage for the selected probe; either Geiger-Muller
or Scintillator. When you set this parameter the voltage change takes place immediately; it
does not wait for you to begin counts for the voltage to get assigned. Note that the voltage gets
applied to the probe only if the High Voltage button is set to ON and is colored green. While the
High Voltage button is set to OFF there is no voltage applied to the probe.
Once you have these four parameters set you should specify the probe type for the probe you
have connected to your ST365 device. Make sure you have only one probe physically
connected to the back of your ST365 device before you run a counts command. Do not have
both a GM tube and a scintillator probe connected to the device at the same time. This assures
that the device receives counts from only one source while a counts command is in progress.
To specify which probe is used click the Display dropdown menu and observe that there are
menu options Probe Type GM Tube and Probe Type Scintillator located at the bottom of the
menu. Select the option that applies for the probe you have connected to your device. Confirm
that the probe type you selected now displays within the Display window. After confirming that
you have the correct probe selected be sure to click the Display dropdown menu again and
select Display Counts. This step is needed in order to display the number of counts during
execution of a counts command.
At the top of the window notice that high voltage is turned OFF. Click the OFF button to turn on
the high voltage. After you do this the button will update to look like this:
Figure 14
The HV ON/OFF button on the ST365 device lights up confirming that high voltage is now on.
You are now ready to start counting with your ST365 device. To execute a counts command
click the Start Counts button. Assuming you have a probe connected to the device and that you
have an active isotope sample located under the probe you should see counts begin to appear
within the display window on the ST365 device and on the Display window within your web
browser. If counts do not appear from the beginning, then this is likely because the voltage
simply is not high enough for the probe to be able to generate counts. For the duration of the

13 Spectrum Techniques ST365 Webpage Rev. 1
counts the parameters section on the web page will update to show the current status of the
counts. The Counts command remains active until the specified number of runs has fully
elapsed and counting has completed.
Plateau Experiment Command
The correct operating voltage for a Geiger-Mueller tube or a scintillator probe may be
determined experimentally using a long-lived radioactive source such as Cs-137 or Co-60. The
plateau experiment consists of repeatedly running counts of a fixed length of time while the high
voltage gets increased by a constant step amount between each run. The resulting graph of
count vs. runs can be examined to determine the optimum voltage to set for the detector
attached to the ST365 device.
The Plateau Experiment Command is useful for finding the optimum high voltage value for a
particular isotope sample located under the probe that is connected to an ST365 device. This
optimum voltage is typically found within a narrow voltage range where for each run the number
of counts remains relatively constant for the voltages used when executing a counts command.
To assist the user in locating this optimum voltage the plateau experiment includes an on-
screen data graph and data table. Once a plateau experiment has completed the user may
inspect the data graph and data table so as to locate the optimum voltage for the given isotope
sample used.
There are four parameters used by the plateau experiment and that control how it operates.
They are:
Start Voltage
End Voltage
Step Voltage
Preset Time
The Start Voltage parameter determines the voltage the ST365 device is set to at the start of
the plateau experiment. When you set this parameter the voltage change takes place
immediately; it does not wait for you to begin counts for the voltage to get assigned. Note that
the voltage gets applied to the probe only if the High Voltage button is set to ON and is colored
green. While the High Voltage button is set to OFF there is no voltage applied to the probe.
The End Voltage parameter determines the voltage the ST365 device is set to at the end of the
plateau experiment. During the experiment it is used by the device to decide whether to
increase the voltage and perform another run.
The Step Voltage parameter determines the voltage increment that gets added to the high
voltage in the device before performing another counting run. The experiment will continue
making counting runs until it has performed a run at the end voltage.
The Preset Time parameter determines the amount of time (in seconds) that the ST365 device
spends counting in order to obtain a counts result. If you leave this parameter set to zero, then
the device will continue counting until you tell it to stop.
Plateau Experiment Setup
Before setting up a plateau experiment make sure you have only one probe physically
connected to a jack on the back of the ST365 device. Do not have both a GM tube and a

14 Spectrum Techniques ST365 Webpage Rev. 1
scintillator probe connected to the device at the same time. This assures that the device
receives counts from only one source during a plateau experiment. To specify which probe is
used click the Display dropdown menu and observe that there are menu options Probe Type
GM Tube and Probe Type Scintillator located at the bottom of the menu. Select the option that
applies for the probe you have connected to your device. Confirm that the probe type you
selected now displays within the Display window. After confirming that you have the correct
probe selected be sure to click the Display dropdown menu again and select Display Counts.
This step is needed in order to display the number of counts during execution of a plateau
experiment. Typically, a plateau experiment gets performed using a GM tube but a scintillator
probe may be used instead.
The standard operating voltage for a GM tube is usually between 800 to 1200 volts. If the
manufacturer’s recommended operating voltage is not known, the correct operating voltage may
be determined experimentally using a radioactive source such as Cs-137 in the GM tube when
running an experiment.
A properly functioning GM tube will exhibit a "plateau" effect, where the counting rate remains
nearly constant even while the high voltage is incremented from one run to the next. A plateau
curve is generated by using the same preset time to count activity from a source for several
runs, while increasing the high voltage by some constant amount between runs. The procedure
below describes this process in detail.
Click the Mode dropdown menu and select the option Plateau Experiment. Doing this takes you
to a page that lets you set four plateau experiment parameters. See Figure 15.
Figure 15
From here you may either type in the values you want to use or you may click the up or down
arrow buttons to increment or decrement the parameter settings until each matches the value
that you want. This example shows a typical plateau experiment setup where the start voltage

15 Spectrum Techniques ST365 Webpage Rev. 1
is 600 volts and the end voltage is 1000 volts. The voltage will step up 20 volts between runs
and each run will last for a preset time of 60 seconds. All the collected data will be recorded in a
data table for later inspection and evaluation.
Once you have all four parameters set the way you want click the Set button located at the
bottom of the page. The Set button turns green to let you know that you have clicked the button.
Click the Set button a second time in order to assure that the device has accepted the new
parameter values.
Plateau Experiment
Once you are satisfied with the parameter settings, click the Back button. Doing this takes you
to a page that looks like Figure 16.
Figure 16
The parameters that you entered are shown in blue boxes on the left-hand side of the page. At
the top of the window notice that the high voltage is turned OFF. Click the OFF button to turn
on the high voltage. After you do this the button updates to look like this:
Figure 17
The HV ON/OFF button on the ST365 device will light up confirming that high voltage is now on.
The right-hand side of the window contains a data graph at the top and a data table at the
bottom. During execution of a plateau experiment the data graph and data table will
automatically update with each run in the experiment. The data graph will update to show the
number of counts associated with each run. The data table will update to show the run number,
counts, elapsed time, and voltage associated with each run. See Data Table section later on in

16 Spectrum Techniques ST365 Webpage Rev. 1
this user manual for a discussion of how to copy the data table contents to your device’s
clipboard.
You are now ready to begin a plateau experiment with your ST365 device. To execute this
command click the Start Counts button. Assuming you have a probe connected to the device
and that you have an active isotope sample located under the probe you should eventually see
counts begin to appear within the display window on the ST365 device and on the Display
window within your web browser. If counts do not appear from the beginning, then this is likely
because the voltage simply has not reached a level high enough where the probe is be able to
generate counts. For the duration of the experiment the parameters section on the web page
will update to show the current status of the counts. The plateau experiment command remains
active until runs over the full voltage range have executed and counting has completed.
Figure 18 shows a typical result after completion of a plateau experiment.

17 Spectrum Techniques ST365 Webpage Rev. 1
Figure 18
Note that the data graph has a region located roughly between 860 and 880 volts where the
measured counts from one run to the next remains fairly constant. This result from the plateau
experiment indicates that the optimum voltage setting for the given isotope is around 870 volts.

18 Spectrum Techniques ST365 Webpage Rev. 1
Half-Life Experiment Command
The Half-Life Experiment Command is useful for verifying the half-life of an isotope with a
relatively short half-life. An ideal isotope to use with this experiment is a Spectrum Techniques
Cs-137/Ba-137m isotope Generator set (Item ID: ISO). This isotope generator allows the user
to ‘milk’ a Cs-137 source to produce a small sample of Ba-137m with a half-life of 2.55 minutes.
The half-file experiment involves taking repeated count runs of an isotope using the same
preset times and detector voltages. The radioactive decay of the isotope is measured by the
decrease in the number of counts across several runs.
There are three parameters used by the half-life experiment and that control how it operates.
They are:
Number of Runs
Preset Time
High Voltage
The Number of Runs parameter determines how many times the ST365 device measures the
number of counts for a given isotope during a half-life experiment.
The Preset Time parameter determines the amount of time (in seconds) that the ST365 device
spends counting in order to obtain a counts result. If you leave this parameter set to zero, then
the device will continue counting until you tell it to stop.
The High Voltage parameter determines the voltage the ST365 device uses when running a
half-life experiment. When you set this parameter the voltage change takes place immediately;
it does not wait for you to begin counts for the voltage to get assigned. The voltage remains at
this setting for the duration of the half-life experiment. Note that the voltage gets applied to the
probe only if the High Voltage button is set to ON and is colored green. While the High Voltage
button is set to OFF there is no voltage applied to the probe.
Half-Life Experiment Setup
Before setting up a half-life experiment make sure you have only one probe physically
connected to a jack on the back of the ST365 device. Do not have both a GM tube and a
scintillator probe connected to the device at the same time. This assures that the device
receives counts from only one source during a half-life experiment. To specify which probe is
used click the Display dropdown menu and observe that there are menu options Probe Type
GM Tube and Probe Type Scintillator located at the bottom of the menu. Select the option that
applies for the probe you have connected to your device. Confirm that the probe type you
selected now displays within the Display window. After confirming that you have the correct
probe selected be sure to click the Display dropdown menu again and select Display Counts.
This step is needed in order to display the number of counts during execution of a half-life
experiment. Typically, a half-life experiment gets performed using a GM tube but a scintillator
probe may be used instead.
Click the Mode dropdown menu and select the option Half-Life Experiment. Doing this takes
you to a page that allows you to set three half-file experiment parameters. See Figure 19.

19 Spectrum Techniques ST365 Webpage Rev. 1
Figure 19
From here you may either type in the values you want to use or you may click the up or down
arrow buttons to increment or decrement the parameter settings until each matches the value
that you want. This example shows a typical half-life experiment setup where the number of
runs is 10 and each run will last for a preset time of 60 seconds. The half-life experiment runs at
850 volts. All the collected data will be recorded in a data table for later inspection and
evaluation.
Once you have all three parameters set the way you want click the Set button located at the
bottom of the page. The Set button turns green to let you know that you have clicked the button.
Click the Set button a second time in order to assure that the device has accepted the new
parameter values.
Half-Life Experiment
Once you are satisfied with the parameter settings, click the Back button. Doing this takes you
to a page that looks like Figure 20.

20 Spectrum Techniques ST365 Webpage Rev. 1
Figure 20
The parameters that you entered are shown in blue boxes on the left-hand side of the page. At
the top of the window notice that the high voltage is turned OFF. Click the OFF button to turn
on the high voltage. After you do this the button will update to look like this:
Figure 21
The HV ON/OFF button on the ST365 device will light up confirming that high voltage is now on.
The right-hand side of the window contains a data graph at the top and a data table at the
bottom. During execution of a half-life experiment the data graph and data table will
automatically update with each run in the experiment. The data graph will update to show the
number of counts associated with each run. The data table will update to show the run number,
counts, elapsed time, and voltage associated with each run. See Data Table section later on in
this user manual for a discussion of how to copy the data table contents to your device’s
clipboard.
You are now ready to begin a half-life experiment with your ST365 device. To execute this
command click the Start Counts button. Assuming you have a probe connected to the device
and that you have an active isotope sample located under the probe you should see counts
begin to appear within the display window on the ST365 device and on the Display window
within your web browser. If counts do not appear from the beginning, then this is likely because
the voltage simply is not high enough for the probe to be able to generate counts. For the
duration of the experiment the parameters section on the web page will update to show the
current status of the counts. The half-life experiment command remains active until it has
counted for the specified number of runs.
Figure 22 shows a typical result after completion of a half-life experiment.