Gyrus Software
presents
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                   ##      Gamma Demo      ##
                   ##          by          ##
                   ##      R. McCarter     ##
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Gamma Demo is a freely distributable limited version of Gamma Counter  1992 Gyrus Software ALL RIGHTS RESERVED. You are encouraged to copy and send versions of Gamma Demo
to any interested users, however, Gamma Counter is a copyright protected commercial program and must not be reproduced for distribution to others.

Gamma Counter is a simulation of a gamma ray scintillation counter used to study radioactivity. This simulation has been developed to fill a void in the way students normally learn about radioactivity. Usually there are few lab
activities due to the expense of individual work stations, the danger and expense of radioisotopes and the time needed to carry out involved experiments.

Using the Gamma 2000 counter students will be able to simulate the measurement of the energies of the emissions of a variety of radioisotopes, to count
the emissions and to determine the half lives of the isotopes. Many exotic radioisotopes have been provided, some with such short half lives that they would only last for minutes in a normal laboratory. Several lab activities are provided to demonstrate the use of radioisotopes in science, medicine and
industry.

The Gamma 2000 has several advantages over the operation of conventional scintillation counters. This may detract from authenticity, however it simplifies and adds interest to the use of the equipment in a high school classroom. The counter does not have to be calibrated and is sensitive to a wide energy spectrum of beta particles, positrons and gamma rays. Time can be run quickly ahead or in reverse so that days pass in seconds and complex experiments can be done quickly. Calculation of half lives is simplified by a feature that allows the matching of a half life graph to the data recorded in an experiment.


Gamma Counter was written for the Amiga computer in Amos by:

                Bob McCarter
                Gyrus Software
                RR3 Site 312 C53
                Port Alberni, B.C.
                Canada
                V9Y 7L7

Copies of Gamma Counter can be ordered for $39.95 from the above address.

The complete version includes documentation, 14 different experiments that
illustrate the varied uses of radiation and can be readily copied onto a
hard drive.

Making a Copy of GammaDemo:

Gamma Counter is not copy protected. Boot up workbench and make a back up copy by dragging the icon for  the GammaDemo: disk over the icon for the empty disk or use "duplicate" from the workbench menu. Gamma Demo works only from df0:.

Using Gamma Demo

To start Gamma Demo click twice on the GammaDemo.exe atomic nucleus icon. When the title screen has loaded, the door can be opened by entering the code
"123" by clicking the mouse pointer on the key pad and then clicking on the
door handle. If you make a mistake entering the code, press "C" to clear the code and start again.

The Store Room

Reading Labels:

Once in the store room you can peruse the various radioisotopes and problems. In Gamma Demo, only one of the 14 possible labs is available. Position the mouse pointer over the label of a sample and press the right mouse key to read the label. Click the left mouse key to get rid of the label window.

Menu Items:

Position the mouse pointer elsewhere on the screen and press the right mouse button to see the menu. Under "options" highlight "problem" to read the current experimental problem. Highlight "help" to get some clues on how to solve the problem. Select "about" to find some useful information about who wrote Gamma Counter. Under "problems" highlight different selections to restock
your shelves with a new set of radioisotopes for different problems.

Moving Isotopes:

To select a radioisotope for study position the mouse pointer over the lead
canister and press and hold the left mouse button. Lift the canister from the shelf and release the mouse button to place it on the counter. Take the lid off by selecting it with the mouse pointer and pressing and holding the left mouse button. The bottle inside the canister can now be removed in a similar manner.

Before another sample can be selected, put the bottle back in the canister put on the lid and return it to its former position on the shelf. The canister shrinks in size when it is ready to be replaced.


The Counting Chamber

Once the scintillation bottle has been removed from the lead canister it can be taken to the counting chamber to the right of the screen. Simply lift the bottle to the right edge of the screen.

The bottle is now attached to the mouse pointer and can be placed into the counting tube by positioning the bottle and clicking the left mouse button. Click on the down arrow for the tube to descend into the counting chamber. The screen will automatically scroll to the counter. Pressing "stop" will cause the screen to scroll back to the counting chamber. Press the up arrow and
the bottle can be removed by clicking near its lid. Take the bottle to the extreme left of the screen to return to the store room.


The Scintillation Counter

There are several controls on the Gamma 2000.

Pressing "count" with the mouse pointer and left mouse key causes the counter to count the radiations from the sample. When finished the total count is
displayed in the count window. If "energy" has been selected a graph of number of counts against energy in kiloelectron volts (keV) will be displayed in green in the graph window. If "time" has been selected, a graph of total number of counts against the time at which the count was taken will be displayed as a single point in the graph window.

Selecting the arrows on the "timer" will increase or decrease the length of
time the count is taken for.

Selecting the "snd" knob with either the right or left mouse key will increase or decrease the sound.

Selecting the "brt" knob with either the right or left mouse key will change the background brightness of the graph screen.

Selecting the digits in the "time" window with the left mouse key will advance time. Use the right mouse key to go back in time. Select different digits to advance the time at different rates. Select the time unit with the left
mouse key to rotate through sec, min, hrs, day and yrs.

The arrow keys to the left and to the bottom of the graph screen allow you to change the scales of the screen. The vertical count axis can be adjusted in increments of 100 using either the up or down arrows to the left of the graph screen. The range of this axis is from a count of 0 to a maximum of the
value displayed to the top left on the graph screen.

The arrow keys to the bottom left of the graph screen adjust the low range of the graph. This value is displayed to the bottom left on the graph screen. Pressing the center key adjusts this value to 0. The bottom right arrow keys adjust the high range of the graph screen and display this value to the bottom left on the graph screen. Pressing the center key adjusts this value to 2000 keV if the graph is set to energy and to 500 if the graph is set to time.

The total count will change with the range of energies displayed on the graph. Only those radioactive disintegrations with energies between those of the low and high ranges on the graph will be counted. Certain ranges of energies can be selected for counting by adjusting the low and high ranges. The energies counted can be selected even more carefully by selecting the "window"
arrows. Pressing these keys when the graph is set on energy selects a narrow window of energies to be counted.

When the graph has been set to "time", the time units of the graph can be changed from sec to min to hrs to day to yrs by selecting the [sec] on the graph screen with the left mouse key.

Selecting the "hlife" key when the graph has already been set to "time" activates the half life function. Estimate the half live of the radioisotope and key this into to the time which is now displayed in yellow. The left key adjusts time up and the right key adjusts time down. Selecting the time unit cycles the time through "sec" to "min" to "hrs" to "day" to "yrs". When you have selected an estimated half life, press the "hflife" key again. A half life graph is drawn
on the screen. Correct your estimate and press the half life key again and repeat until the graph matches the data you have recorded at different times
for your sample. This time will be the half life of the radioisotope.


Student Exercises

Some of the problems are fairly complex and others are simple. To help the students work with the gamma counter, several worksheets are provided to help students with the more complex activities. The problems have been chosen to illustrate the uses of radiation in research, medicine, and industry. These problems are not available in Gamma Demo.

