It’s widely known that a smoke detector is a good ionizing radiation source, as they contain a small amount of americium-241, a side product of nuclear reactors. But what about other sources? [Carl Willis] got hold of an old Soviet era smoke detector and decided to tear it down and see what was inside. This, as he found out, isn’t something you should do lightly, as the one he used ended up containing an interesting mix of radioactive materials, including small amounts of plutonium-239, uranium-237, neptunium-237 and a selection of others. In true hacker fashion, he detected these with a gamma ray spectroscope he has in his spare bedroom, shielded from other sources with lead bricks and copper and tin sheets. Continue reading “Soviet Era Smoke Detector Torn Down, Revealing Plutonium”
Like many industrialized countries, in the period after the Second World War the United Kingdom made significant investments in the field of nuclear reactors. British taxpayers paid for reactors for research, the military, and for nuclear power.
Many decades later that early crop of reactors has now largely been decommissioned. Power too cheap to meter turned into multi-billion pound bills for safely coping with the challenges posed by many different types of radioactive waste generated by the dismantling of a nuclear reactor, and as the nuclear industry has made that journey it in turn has spawned a host of research projects based on the products of the decommissioning work.
One such project has been presented by a team at Bristol University; their work is on the property of diamonds in generating a small electrical current when exposed to radioactive emissions. Unfortunately their press release and video does not explain the mechanism involved and our Google-fu has failed to deliver, but if we were to hazard a guess we’d ask them questions about whether the radioactivity changes the work function required to release electrons from the diamond, allowing the electricity to be harvested through a contact potential difference. Perhaps our physicist readers can enlighten us in the comments.
So far their prototype uses a nickel-63 source, but they hope to instead take carbon-14 from the huge number of stockpiled graphite blocks from old reactors, and use it to create radioactive diamonds that require no external source. Since the output of the resulting cells will be in proportion to their radioactivity their life will be in the same order of their radioactive half-life. 5730 years for half-capacity in the case of carbon-14.
Of course, it is likely that the yield of electricity will not be high, with tiny voltages and currents this may not represent a free energy miracle. But it will be of considerable interest to the designers of ultra-low-maintenance long-life electronics for science, the space industry, and medical implants.
We’ve put their video below the break. It’s a straightforward explanation of the project, though sadly since it’s aimed at the general public it’s a little short on some of the technical details. Still, it’s one to watch.
If you are a certain age, there were certain science toys you either had, or more likely wanted. A chemistry set, a microscope, a transparent human body, and (one of several nuclear toys) a cloud chamber. Technically, a Wilson cloud chamber (named after inventor Charles Wilson) isn’t a toy. For decades it was a serious scientific tool responsible for the discovery of the positron and the muon.
The principle is simple. You fill a sealed chamber with a supersaturated water or alcohol vapor. Ionizing radiation will cause trails in the vapor. With a magnetic field, the trails will curve depending on their charge.
If you didn’t have a cloud chamber, you can build your own thanks to the open source plans from [M. Bindhammer]. The chamber uses alcohol, a high voltage supply, and a line laser. It isn’t quite the dry ice chamber you might have seen in the Sears Christmas catalog. A petri dish provides a clear observation port.
We live in a world transformed by our ability to manipulate the nucleus of atoms. Nuclear power plants provide abundant energy without polluting the air, yet on the other hand thousands of nuclear warheads sit in multiple countries ready to annihilate everything, even if it’s not on purpose. There are an uncountable number of other ways that humanity’s dive into nuclear chemistry has impacted the lives of people across the world, from medical imaging equipment to smoke detectors and even, surprisingly, to some of the food that we eat.
After World War 2, there was a push to find peaceful uses for atomic energy. After all, dropping two nuclear weapons on a civilian population isn’t great PR and there’s still a debate on whether or not their use was justified. Either way, however, the search was on to find other uses for atomic energy besides bombs. While most scientists turned their attention to creating a viable nuclear power station (the first of which would only come online in 1954, almost ten years after the end of World War 2), a few scientists turned their attention to something much less obvious: plants.
Random number generators come in all shapes and sizes. Some are software based while others, known as true random number generators, are hardware based. These can be created from thermal noise, the photoelectric effect and other methods. But none of these were good enough for [M.daSilva]. He would base his off of the radioactive decay of Uranium 238, and construct a working nuclear powered random number generator.
Because radioactive decay is unpredictable by nature, it makes for an excellent source for truly random data. The process is fairly simple. A piece of old fiestaware plate is used for the radioactive source. Put it in a lead enclosure along with a Geiger tube. Then wire in some pulse shaping circuitry and a microcontroller to count the alpha particles. And that’s about it. [M.daSilva] still has to do some statistical analysis to ensure the numbers are truly random, along with making a nice case for his project. But all in all, it seems to be working quite well.
Be sure to check out the video for quick rundown of [M.daSilva’s] project. If randomness is your thing, make sure you check out entropy harvested from uninitialized RAM, and the story behind the NIST randomness beacon.
This week’s film begins as abruptly as the Atomic Age itself, though it wasn’t produced by General Electric until 1952. No time is wasted in getting to the point of the thing, which is to explain the frightening force of nuclear physics clearly and simply through friendly animations.
[Dr. Atom] from the Bohr Modeling Agency describes what’s going on in his head—the elementary physics of protons, neutrons, and electrons. He explains that atoms can be categorized into families, with uranium weighing in as the heaviest element at the time. While most atoms are stable, some, like radium, are radioactive. This evidently means it stays up all night doing the Charleston and throwing off neutrons and protons in the process of jumping between atomic families. [Dr. Atom] calls this behavior natural transmutation.
Artificial transmutation became a thing in the 1930s after scientists converted nitrogen into oxygen. After a couple of celebratory beers, they decided to fire a neutron at a uranium nucleus just to see what happened. The result is known as nuclear fission. This experiment revealed more about the binding force present in nuclei and the chain reaction of atomic explosions that takes place. It seemed only natural to weaponize this technology. But under the right conditions, a reactor pile made from graphite blocks interspersed with U-235 and -238 rods is a powerful and effective source of energy. Furthermore, radioactive isotopes have advanced the fields of agriculture, industry, medicine, and biochemistry.
Here’s a hypothesis for you: radioactive decay varies over time, possibly with a yearly cycle. [Panteltje] decided to test this hypothesis, and so far has two year’s worth of data to comb over.
Radioactive decay can be easily detected with a photomultiplier tube, but these tubes are sensitive to magnetic fields and cosmic rays that would easily fly through just about any shielding [Pantelje] could come up with. Instead, the radiation in this setup is detected with simple photo detectors, pressed right up against a tritium-filled glass ampoule, a somewhat common lighting solution for fishing lures, watch faces, and compasses.
The experimental setup records the photo detectors, a temperature sensor, and a voltage reference, recording all the data to an EEPROM once an hour. All the important electronics are stuffed into a heatsinked, insulated, light-proof box, while the control electronics reside on a larger board with battery backup, alarm, indicator LEDs, and an RS232 connection.
After one year, [Pantelje] recorded the data and reset the experiment for another year. There are now two years worth of data available, ready for anyone to analyze. Of course, evidence that radioactive decay changes over the course of a few years would turn just about every scientific discipline on its head, so at the very least [Panteltje] has a great record of the output of tritium lights against the expected half-life.