The AUA College of Science and Engineering in collaboration with MIT is hosting a DIY workshop for measuring radiation on January 24-28, 2022.

In this rigorous, intense, yet enjoyable course students build and test their own Geiger Counters, and in doing so, explore different types and sources of radiation, how to detect them, how to shield them and how to accurately count / measure their activity.

Note:  participation is by invitation only.  We will be taking attendance to confirm that those students who signed up did attend.

Lead instructor:  Prof. Areg Danagoulian, MIT

TAs:  Zoe, Bethany, Brendan, Zach...Everyone!

​​Days: Jan 24-28

Times:

• Lectures: 16:30-18:30
• Labs: 16:30-20:30

Location:  

• Lectures: TBD -- information will be communicated via email to the selected applicants
• Labs: TBD

COURSE MATERIAL

You can find most of our lecture notes, course materials, code examples etc. in this Dropbox directory.

Ideal background:

• Basic knowledge of statistics and probability
• Basics of physics
• Basic knowledge of electrical circuits (e.g.. transistors, capacitors, resistors)
• Some coding and data analysis skills. Familiarity with python and the command line is a plus.
• Soldering skills are a plus.
• Proficiency in English

This week-long lab is modeled based on a similar one-week long course which was taught at MIT during the IAP of 2015 by Prof. Michael Short et al..  For more details about the MIT course see here.

What is Radiation?  Where is it?

Radiation is everywhere in our surrounding world.  Most of the materials that we are surrounded with in our daily lives contain naturally occurring radioactive isotopes.  For example:

• Bananas contain potassium (K).  Our own nerves use “potassium channels” to propagate the electrical signals that allow for our brain to work (and for this text to be written).  One of the isotopes of potassium is ⁴⁰K, which is an unstable isotope with a half life of 1.251×10⁹ years.  Yes, this means that our brain is radioactive!  

• Most rock surrounding us naturally contains uranium (U) and thorium (Th).  Uranium and thorium undergo alpha-decay, which leads to other unstable isotopes.  These too decay, emitting alpha particles and gammas.  Granite in particular is quite rich with U and Th.

• Many porous rocks, such as tuff (that many buildings in Armenia are built from), contain radon gas.  This gas, specifically ²²²Rn is a product of the decay of naturally occurring uranium.  Radon is an inert gas, which means that it easily goes through rock and escapes into the open air.  ²²²Rn is radioactive, it decays by emitting an energetic alpha particle.  If you breathe in radon then its decay alphas will irradiate your lungs.  Too much of this will cause cancer.  In many countries increased cancer rates are attributed to accumulation of radon in basements.  This can be mitigated easily by venting the basements (most homes in Armenia unfortunately do not have this).

How is Radiation Used by Humanity?

Intense (unnaturally high) radiation can be harmful to us.  Why?  Because radiation causes ionization in the water, forming hydroxyl groups and other free radicals.  These bind to and break up DNA.  While the cell is extremely good at repairing radiation damage to its DNA (otherwise life wouldn’t exist), sometimes  things go wrong and mutations occur.  These mutations sometimes accumulate, causing cancerous growth.  For this to happen you need large radiation doses.

However radiation can also be very helpful to humans if used ethically and correctly.  Here are a number of examples where radiation has significantly helped improve our lives:

• X-ray is a form of radiation, which is used to image the human body to discover broken bones and cancerous tumors.

• Computer Aided Tomography (CAT) uses X-ray to create a 3D image of your body to discover cancer and various life-threatening internal injuries.

• Positron Emission Tomography (PET) uses radioactive isotopes to map out tumors in a cancer patient’s body, allowing doctors to detect and diagnose the cancer.

• Gamma therapy uses beams of gammas to kill cancerous tumors and thus save lives.

• Physicists use various particle beams to study the fundamental laws of nature, thus improving our understanding of the world around us.

• Archeologists use radiocarbon dating to determine the age of various archeological artifacts.  This is (in part) how we know Yerevan-Erebuni’s age.

• Mars Perseverance Rover uses  a small “nuclear reactor,” a Radioisotope Thermal Generator as a source of its power.  This will allow Perseverance to study the surface of Mars, and possibly find life there.  Future space missions will continue to use radioactive sources for power, allowing them to explore the Solar system and beyond!

• Radiation inside nuclear reactors, when used responsibly and competently,  produces electrical power which doesn’t contribute to global warming and keeps the environment clean.  Currently 30-40% of Armenia’s electricity comes from the Metsamor Nuclear Power Plant.  Every third light bulb in your home (on average) is powered by Metsamor.

Radiation is everywhere and you cannot escape it.  You can understand it however, and learn how to use it to create good.  It is thus very important to understand radiation.  It means understanding the physics and the basic science behind radiation.  It also means developing an ability to measure and quantify radiation using specialized instruments and mathematical models.

Questions:

What is radiation?  What is a gamma, a beta, and an alpha particle?  Where do they come from?

How do you measure radiation?

How do you shield from radiation?

How do you use radiation?

Goals of the Lab

In this lab the students will learn the basics of nuclear physics, radiation and nuclear detection.  The goals of the lab are the following:

• Learn basics of nuclear physics related to radiation

• Learn introductory concepts on statistics that are relevant to nuclear detection

• The basics behind the electronics of a Geiger-Muller counter (Geiger counter, for short)

• Build a Geiger Counter

• Make measurements with the counter

Tentative Plan of the DIY Lab

Monday, Jan. 24th

Introduction to Nuclear Physics (~ 2hrs)

• Energy:  electron-Volt

• Photons and Electrons

• Photon interactions

  • Photoelectric effect

  • Compton Scattering

  • Pair production

• Nuclear detection, the simplest device:  Geiger-Muller Counter

• Shielding and attenuation:  how to calculate attenuation using mass attenuation coefficient

• Hands on exercise:

  • Calculate attenuation

  • …

Tuesday, Jan 25th

Statistics, read Knoll Chapter 3 (~ 2hrs)

• Random processes, independence

• Binomial distribution

• Poisson distribution

• Gaussian statistics and Central Limit Theorem

• Error propagation

• Statistical tests:

  • Z-score

  • Chi2 test

• Waiting time between two consecutive random events

• Hands on exercises:

  • Use Z-score to calculate the probabilities of a) a political party winning the elections, and b) that a radioactive source is present

  • Apply the chi2 test for three data points and verify whether they come from the same process

Wednesday, Jan 26th

Geiger counter

• Basics of electricity – how does the Geiger counter work?

• Start building the Geiger Counter (~3hrs)

  • Basic exercises with soldering

  • Start building the counter

Thursday, Jan 27th

Complete the Geiger Counter

• perform troubleshooting

• Start with the exercises with the Counter

Assignment:  write a python Data Acquisition (DAQ) code which will allow you to read in the pulse from the counter into your laptop’s audio input.  Your code should detect the pulse and record the time (in milliseconds) of the pulse. 

Friday, Jan 28th

Exercises with the Geiger Counter using your DAQ code

• Take two measurements:

  • Background

  • Source + background

  • Apply the Z-test to determine the probability that a source is present

• Make multiple measurements of the background or source:

  • Apply the chi2 test to verify that the background is stable

  • Plot the waiting time between consecutive hits – is it exponential?

• Test the statistical models and the Central Limit Theorem:

  • Plot the distribution of the 5-sec long measurements, such that you only get 1-2 counts – do you get a Poisson distribution?  

  • What if you do 1-min long measurements – do you get a Gaussian?

• Measurements of attenuation using different targets

  • Measure with a source

  • Measure with a source and a target/absorber

  • Does the number of counts correspond to the predictions that are based on the mass attenuation coefficient?

APPLICATION:

Participation in this course is on a competitive basis.  To apply please go HERE. The deadline is January 10th. The applicants will be informed about acceptance by Jan 15th.