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Project RNG: Radiation-BasedRandom Number Generator
• Team Oregon Chub– Colton Hamm (Team Leader)– Alex Brotherston– Ashley Donahoo– Matt Johnson
University of Portland School of Engineering
Advisor:Dr. Hoffbeck, Dr. VanDeGrift,
Dr. Osterberg
Industry Representative:Mr. John Haner
Bonneville Power Administration
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Introduction
• Our project generates random numbers from radioactivity
• Building a radiation sensor, designing a MOSIS chip and using 7-segment displays
University of Portland School of Engineering
Senior Design
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Scorecard
• Completed Final Report v0.9
• Interfaced Geiger tube with CPLD
University of Portland School of Engineering
Senior Design
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Additional Accomplishments
• Gathered over 3700 bits of data to be analyzed for statistical tests.
• Replaced function generator with batteries to power device.– 3 batteries
University of Portland School of Engineering
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Plans• Conduct statistical tests
• Complete Final Report v.95
• Complete Final Report v1.0
• Add reset and hold buttons to device
• Work on Founder’s Day presentation
University of Portland School of Engineering
Senior Design
6University of Portland School of Engineering
MilestonesStatus Description Original
TargetPreviousTarget
PresentTarget
Completed Construct and test the prototype voltage multiplier.
14 Feb 11 14 Feb 11 11 Feb 11
Completed Construct final voltage multiplier 21 Feb 11 21 Feb 11 20 Feb 11
Completed Interface pulse generator, transformer, voltage multiplier,
and Geiger tube
14 Mar 11 14 Mar 11 22 Feb 11
Missed Final Report v0.9 13 Mar 11 13 Mar 11 25 Mar 11
Completed Interface Geiger tube and CPLD 30 Mar 11 30 Mar 11 21 Mar 11
Completed Interface all aspects of device 29 Mar 11 29 Mar 11 29 Mar 11
On Track Final Report v0.95 1 Apr 11 1 Apr 11 1 Apr 11
On Track Final Report v1.0 8 Apr 11 8 Apr 11 8 Apr 11
On Track Founder’s Day Presentation Complete
12 Apr 11 12 Apr 11 12 Apr 11
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Concerns/Issues
• Concerns regarding battery power, especially with the large display for Founder’s Day.
• Concerned about statistical tests proving that our numbers are truly random.
• Concerns that case may not be done by Founder’s Day and shielding issues.
University of Portland School of Engineering
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Conclusions• The Geiger tube, CPLD, and display have
all been interfaced and are working.
• Statistical tests will show if numbers are truly random.
University of Portland School of Engineering
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Questions?
University of Portland School of Engineering
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Secret Geiger Tube Slides
• Model: Geiger Tube as a Switch
• Switch=open, V=500v
• Switch Closes, V=
500v*10M/(1M+10M)=455v
• The capacitor blocks DC, so the signal starts at 0 volts, and falls by 45 volts when the switch closes
University of Portland School of Engineering
V
Senior Design
11University of Portland School of Engineering
0v
-40v
A Geiger–Müller tube consists of a tube filled with a low-pressure inert gas, such as neon, and an organic vapor or a halogen gas. The tube contains electrodes, between which there is a potential difference of several hundred volts, but no current flowing. The walls of the tube are either entirely metal or have their inside surface coated with a conductor to form the cathode while the anode is a wire passing up the center of the tube.
When ionizing radiation passes through the tube, some of the gas molecules are ionized, creating positively charged ions, and electrons. The strong electric field created by the tube's electrodes accelerates the ions towards the cathode and the electrons towards the anode. The ion pairs gain sufficient energy to ionize further gas molecules through collisions on the way, creating an avalanche of charged particles.
This results in a short, intense pulse of current which passes (or cascades) from the negative electrode to the positive electrode and is measured or counted.
-Wikipedia
