So You Want To See Alpha Particles With Your Eyes PART 5

So You Want To See Alpha Particles With Your Eyes PART 5

Visually, this is the most boring way to see alpha particles (or their impact on the physical world at least) in my series. It's also the easiest and cheapest. Unlike my previous 4 posts on this subject, there will be no need for: high voltage; dry ice; Geiger-Mueller tubes or even simple phosphors slopped onto a glass slide.

Nope! All this project takes is any old cheap webcam-and source of alpha radiation. You'll also need a desktop computer to run the webcam with, and a couple screwdrivers.

At my local Disabled American Vets resale shop (kind of like the Salvation Army shops) they have a big box of webcams for .99 cents each! In previous posts I pried the IR filter off of one to make an infrared camera. This time we're prying off the lens in addition to the IR filter.

The steps were simple: take out the screws of the casing. Rip off the lens bezel. Unscrew the lens completely out.

Here's where webcams differ: some have the IR filter as the last part of the lens: the end that is normally inside the camera. Hold the lens at different angles and if you can see green/red coatings that's probably the IR filter. If not, there will be a teeny-tiny little greenish piece of glass inside the camera that used to nearly touch the inside end of the camera. Anytime I've ever taken a webcam apart this filter has always just fell out for me. Sometimes you'll have to pry it out.

Next, all you do is set it up in a dark container and lay an alpha particle source onto the CCD chip of the camera: BOOM! You'll get little white and blue dots zinging all over. Lift off the alpha source and no more moving spots or specs.

I experimented many times, placing and removing the alpha radiation source and starting at my computer screen. The dots disappear when the alpha source is removed. A couple times they did not come back--it turns out I had the alpha source (I have many) flipped around the wrong way: flip it face down onto the CCD and the moving dots returned.

Here's a video showing radiation on and off: I edited down, but the results were the same for dozens of tests: radiation shows up as white and blue dots zinging around. Removing the radiation results in no dots. Placing radiation sources upside down showed no-greatly reduced amounts of dots.

The results are similar to my alpha sphinthariscope only I don't have to wait 10 minutes for my eyes to adjust to darkness-and I don't have to shove my eye inches away from a pile of radioactive material! Let the webcam get blasted in the face with radiation.

The mesmorizing waves of dots and dashes looks like the surface of a lake at night during a full moon in the sphinthariscope, in my webcam alpha particle detector it's more hit or miss. The moon reflected in a small puddle.

The webcam's CCD is way more high-tech than the sphinthariscope though.

CCD stands for "Charge-Coupled Device" and are the sensor that "sees" in many webcams. These pure silicon dioxide is used to change photos to electrons. Light to digital information. Many times these are "doped" with other chemicals to give the silicon dioxide a better affinity for certain inputs. There are different types of dopants, but webcams use "P" dope, which can use our friends from the last post: indium and gallium! Those two help snatch infrared light.

In my last post I mentioned the super lattice of eutectic alloys. There is a similar theory in CCDs where the crystal lattice is missing a component and this empty spot grabs electrons and helps move them around over and over again as a charge carrier. The 'hole' moves all around as the electrons keep moving to file the hole, which leaves a new hole.

This is actually the function of MOSFET and MOS transisistors: like a quantum bug-zapper waiting for photons. Then they carry this info down to the actually CCD which just digitizes this information. So really, the MOSFETs do the interesting work of "seeing".

OK hole, slide me toward the CCD!

A couple more times and then the Meowfet will dump it's charge to the CCD and then it's sent to a pixel! 

Ouch! Crammed into a dead pixel square again.

see atomic particles with your own eyes huh? Part II

So you wanna see atomic particles with your own eyes huh? Part II

Was der Fall ist, die Tatsache, ist das Bestehen von Sachverhalten.

(What is the case, the fact, is the existence of atomic facts.)

-Ludwig Wittgenstein

Wittgenstein was a fascinating weirdo, but in the second proposition to his only (seventy-five page long) contribution to the world of philosophy and logic (the Tractatus Logico Philosophicus) he wrote the quote above. He wasn't denying art, religion, myth, but when speaking of absolute truth there are facts (atomic and otherwise) and then there is everything else.  Stay in there, it gets less boring real soon...

Basically he went against metaphysics (sort of) and Plato, et al and piled on a bunch of stuff about words and the world and truth functions (like actual math functions but with words) and examining the world using language. If any of the above grabs you: search "atomic sentence" and there's a whole world of true/false wordy-math formula semantic whatever. Anyway, Wittgenstein argued for unalterable objects/forms in direct opposition to eastern philosophy where Forms are ever changing, relative substances in a constant state of flux (sounds just like radioactive elements becoming different substances by adding/losing electrons and particles through decay. Think back to the last post about changing the dime's silver "form" to different isotopes 107, 108, 109 and 110. Flux. Change. Pretty much the opposite of Wittgenstein's ideas, but my quest to see atoms isn't.

Anyway, Wittgenstein claimed he solved all the problems of philosophy(!) so there's no need to continue in that vein. Here's an Atomic Facts of my own: I've seen the trails left by alpha, beta and gamma particles with my cloud chamber. This was covered in one of my previous posts. Think of the nuclear cloud chamber like standing in fog and watching bullets zing past you ripping lines through the fog. Cool-but I want more!

This is where my new toy comes in: a radioscope / sphinthariscope. A radioscope is a screen with zinc-sulfide paste smeared on it. It also has a magnifying eyepiece attached. You hold it up to alpha emitting radioactive objects to see tiny flashes of light when the alpha particles hit the zinc-sulphide crystal and form a phosphor (not to be confused with the chemical element phosphorus). It glows in the dark, well actually it scintillates. 

The word sphinthariscope comes from the Greek word for scintillate or sparkle. A sphinthariscope comes with a built in piece of radioactive material to "power" it-a radioscope is the same thing but with the radioactive material removed, along with the bottom of the device so that you can plop it on top of your own radioactive materials.

For $29 you can buy one from United Nuclear-but for about $9 you buy the activate zinc-sulfide and smear it on your own homemade scope. I opted to order one first, I'll probably make one from scratch for the fun of it in the future.

William Cooke made/discovered the first spinthariscope when using a phosphor screen to look for bits of radioactive material he spilled on the floor (been there-done that). He was lighting the screen with an even about of materials, but crawling around on the floor let him see tiny amounts of (alpha) radiation as individual flashes-not just an even glow. 

They became popular novelties in the early 1900s to 1950s: nice brass ones that people took to fancy dinner parties were the "in" thing. The famous Lone Ranger Atomic Ring was a later one that tons of kids received after making their Kix Cereal boxtops in. Then the fad waned.

So how did my radioscope work?

At first there was nothing, but after about ten minutes in a dark room I could see the alpha sparks. My eyes took time to adjust, but the zinc-sulfide coating glows in the dark for a few minutes as well.  At 6400 ISO with a fast f/1.8 lens I couldn't photograph them. Digital camera: 1, human eyeball: 1.

My uranium ore had random green flashes like looking out at a vast field and watching for fireflies to flash. There were some sideways "zingers" and bigger, smeared flashes like lightening behind clouds.

As "hot" as my uranium is to my Geiger counter (which measures beta, gamma and x-ray) there wasn't too much alpha going on. It was nice and subtle and I could have watched for hours, but I didn't like having uranium two inches from my face blasting intense radiation into my eyeball like some brain cancer inducing Medusa.

I moved my radioscope off the pile of uranium and plopped it on top of my little piece of Americium radioisotope 241 (AM-241). AM-241 spews out lots of alpha and a fair amount of gamma radiation. It's what ionizes the chamber inside many cheap smoke detectors: smoke particles block the alpha particles (they're weak) and trigger the alarm.

The verdict with Americium? Wow!! At first it was a dense, waving matrix of corruscating green dots like an old computer monitor from the 1980s that was being reflected in a wavy lake at night. Green dots pulsating, then the dots would surge and swirl like a Hindu mandala (which metaphysically symbolize the universe-Wittgenstein would not approve). 

Imagine the pattern on m my kilim rug, if the rug was hanging on a clothes line and the wind was blowing it toward and away from you in billowing ripples. Mesmerizing!

Sometimes it looked as though the dots were fruit flies or tiny gnats swarming (if gnats glowed in the dark). 

So, while the cloud chamber I built was like having bullets cut trails through fog, this radioscope is kinda like driving a fast car with your headlights off through a pitch black field and having fireflies splattering on the windshield...plus swirling and pulsing like a car wash on that windshield. I have lots of experience with glowing insects on my vehicle (still no idea what the one I took a photo of above was).

The surging and receding coruscating waves appear to be just like the magnetic ferri fluid (iron particles in liquid showing the magnetic field). The lapping waves of radiating particles being emitted in all directions (but viewed as they hit the flat bottom of the radioscope). 

In this flower photo the red tips are like the green alpha dots. By their speed, number and brightness you can infer many things (like the yellow paths). The charge of alpha particles was first investigated with a sphinthariscope, and research on the charge of electrons was furthered by its use; along with the correct form of atoms and their nucleus.

Imagine instead of black magnetic fluid outlining a magnetic field, green dots outlining a field radiation-smashed against the flat viewing window of my radioscope.

With these two easy to make/cheap to buy devices I've seen the paths of radioactive particles and partially how the radiate.

I think I can see the particles too! Meow.