The Hulk and Gammasphere

BuzzSkyline writes "The Hulk may be animated, but the Gammasphere that turns Bruce Banner's hissy fits into raging rampages is real. It's based on a gamma ray detector used at the Berkeley and Argonne National Labs. The actual machine doesn't make monsters, but it helps in studies of nuclear monstrosities. The American Institute of Physics reports on Gammasphere and its role in the movie at Inside Science News Service."

Comments

The more I read this article.

[AtariAmarok]

You know, the more I read this article, the angrier I get. You won't like me when I'm ...aaa .Arrgh
ARGGHHHH

HULK MOD-DOWN YOU PUNY TROLLS!

fun with gamma rays

[Mobster75]

You know... Back in college I was always taught that gamma rays would quickly and easily kill any human because of their short wavelengths and high frequencies....

There is a reason they are one of the extreme categories on the 6 category scale of wavelengths I was taught about... (Radio waves, IR, Visible light, UV, X rays, Gamma rays)

Re:fun with gamma rays

[reverseengineer]

Well, gamma rays are dangerous, of course, but how dangerous is a matter of scale and situation. There's an old puzzle that goes something like this: You are given three radioactive cookies, and told one is an alpha emitter, one is a beta emitter, and one is a gamma emitter. You are told which is which. You are also told that you must hold exactly one of the cookies in your hand, you must put exactly one in your pocket, and you must eat the third cookie.

It turns out that the "best" solution is to hold the alpha emitter in your hand, put the beta emitter in your pocket, and eat the gamma emitter. The thickness of your skin should be sufficient to stop an alpha particle, your clothing should be able to stop most beta particles. Why should you eat the dangerous gamma cookie? Gamma rays are so penetrating that it would take at least an inch of lead to stop them. The other two choices (hand or pocket) wouldn't offer any meaningful amount of protection, so it would be best to protect yourself from the alpha and beta rays, and just hope the gamma source doesn't kill you.

And it might well not- most of the gamma particles will pass right through you actually. Some of them probably will collide with particles in your body, of course, and may do some serious damage to your cells. Proteins and lipids can be damaged and denatured- radiation burns. If DNA is damaged, cells may die as new proteins are no longer able to be constructed. The possibility also exists for damaged DNA to have tumor suppressor genes damaged and "turned off" by the radiation, leading to cancers. Yes, gamma radiation can be very dangerous, but its penetrating ability that makes it so dangerous also limits its effects, since most gamma radiation will pass right through you. Look at an even more extreme example of penetrating radiation- neutrinos. At this very moment, billions of neutrinos emitted in fusion reactions in the sun are streaming through your body, and if one happens to strike an particle in your body, it can do damage just as surely as any other form of radiation. In fact, not too long ago there was a story on /. that involved a blue-sky theoretical plan to destroy nuclear warheads with neutrinos.

It all comes down to the idea of mean free path- the average distance a particle will travel before it contacts another particle. When I say that an inch of lead will stop gamma rays, that's just shorthand for saying that the vast majority of gamma ray photons, fired at the lead, will collide with particles in the lead- the mean free path of a gamma ray through lead, then, is less than one inch. In comparision, the mean free path of a neutrino through lead is over a light year. Odds are pretty good that you will live your entire life, bombarded by quadrillions of neutrinos, without a single one interacting with a particle in your body- they are penetrating to the extent of being basically harmless.

Mean free path is dependent in part on the density of the medium a particle passes through, as well as the characteristices of the particle in question. Alpha particles are essentially helium nuclei, 2 protons, 2 neutrons. The doubly positive charge and the large size of this particle (on a quantum scale, anyway) mean that almost any solid or liquid matter is dense enough to stop alpha particles almost immediately. Beta particles are just electrons ejected from the nucleus in beta decay (a neutron "becomes" a proton, an electron, and an antineutrino. The latter two are ejected, but the proton stays, raising the atomic number of the atom by 1), and so have a charge of -1 and have about 1/1800 of the mass of a neutron or proton. Still, they're easily absorbed by thick fabric or a sheet of foil. Gamma rays are photons, and so are massless, move at the speed of light, and have no electric charge. It takes a considerable amount of a dense substance (like lead) to absorb gammas.

The damaging effects of these

Re:fun with gamma rays

[Idarubicin]

Plutonium parts ("the pit") of the core of nuclear bomb as well as the depleted uranium-tipped ammunition is always electroplated with a thin layer of another metal (nickel, for example) to prevent people from getting "radiation burns" on the skin of their hands when handling these alpha emiting materials.

As I understand it, it actually doesn't have to do with direct radiation burns. When alpha decay takes place, a sizable amount of kinetic energy is divided up between the alpha particle and the remaining atomic nucleus. Sometimes the decay gives the remaining nucleus a sufficient kick in the right direction for it to come loose from the surface. This decay product is often radioactive as well, so instead of dealing with a solid lump of plutonium (bad enough) you also have radioactive dust on surrounding surfaces and in the air. Sealing the surface contains these decay products.

As well, plutonium is even more toxic as a chemical poison than as a radioactive one--coating the parts makes sense just to prevent contact with it.

Finally, pure plutonium is (IIRC) a fairly reactive metal. Electroplating it prevents it from oxidizing--you don't want your nuclear warheads to get 'rusty', do you?

Radiation burns from the alpha emission are actually relatively unlikely--even the most careless handler of plutonium would be wearing rubber gloves, and a sensible soul works in a shielded glove box full of inert gas. This is more than sufficient to stop any alpha particles.

Re:Invertable transducers

[krysith]

MonkeyBoyo,

I'm afraid it doesn't work quite like that. You see, gamma ray detectors (and most other detectors of ionizing radiation) detect the ionization produced by a ray passing through a material. The gamma ray passes through a material (in this case, a germanium crystal I believe) and knocks a few electrons around. That current is then collected, and by knowing the size and location of a pulse of current, they can determine the size and location of the photon which passed through. If you were to reverse the process, you could get some electrons to move around, but you couldn't make them dance in the exacting pattern which would be required to emit a bunch of photons which would combine to make a high energy gamma ray. It is less like turning a microphone into a speaker than it is like trying to get a thousand microphones to reproduce a sound a mile away, as if it had been produced at that point. In other words, it is theoretically possible to create a gamma ray by combining multiple ionizations, but only if you can control where those ionizations occur down to a nano-, maybe even pico- meter resolution. Generally, the best way to create a gamma ray is to ram two nuclei together at very high speed. Basically the same method the hulk uses...

"HULK SMASH!"