How to Build a Cloud Chamber!

[JeffersonLab]

Portions of this video have been reshot and re-dubbed. Please follow the link in the description to view the updated video.

[athf226]

Couldn't you dismantle a smoke detector for a radioactive source to cut out speaking to a dealer?

To get the Americium. That is, of course, it is a smoke detector using Americium :P

[JeffersonLab]

@athf226 In theory, sure. I'm just not sure what regulations you violate by doing so. You can check Title 10, Code of Federal Regulations Part 30 to see.

[athf226]

@JeffersonLab Ah, fair enough! Mostly wondering because I knew that it had a source of radiation that most people have at hands. Was not aware of the regulation, thanks for pointing that out!

[cinedux]

apologies! :-)

[JeffersonLab]

@cinedux No worries.

[cinedux]

don'tcha mean halloween?

[JeffersonLab]

@cinedux No, since it looks a little like fireworks.

[JeffersonLab]

@DeafPizzaCrust It depends on how it's used. Holding a block of dry ice in your hand isn't the best move that you could make. I don't know what doctors do with dry ice, but I imagine they just don't stick it against your forehead. There are lots of ways I can hurt myself with a scalpel, too, but doctors use them anyway.

[panzuman]

why not take apart a smoke detecter? Am 241 is present in there

[JeffersonLab]

@panzuman Yeah...

The Am-241 source in smoke detectors is regulated by the the U.S. Nuclear Regulatory Commission. Specifically, the regulatory requirements are given in Title 10, Code of Federal Regulations Part 30. We are a Department of Energy lab and running afoul of CFRs would be classified as 'bad.' Buying an inexpensive, exempt source is far safer than potentially filming us breaking regs --- with a smoke detector we'd have to buy anyway.

[panzuman]

@JeffersonLab very true but it would work correct? also what is the purpose of the dry ice?

[JeffersonLab]

@panzuman Oh, it'll certainly work. It's just not something I can endorse or recommend.

The dry ice is used to cool the air in the chamber to a point where alcohol clouds can form. The charged particles create ions in the air where condensation can occur. If it's too warm, condensation doesn't happen. Same sort of reason why you see your 'breath' when it's cold but not when it's warm.

[panzuman]

@JeffersonLab so could you us pressure rather then the cold from dry ice? like iff i put a bit of the alcohol in a sealed jar that was relatively warm or if i cooled the jar down before hand would enough alcohol go into the "atmosphere" to where the dry ice would be irrelevent?

[JeffersonLab]

@panzuman Actually, the old bubble chambers worked by dropping the pressure with a big piston.

What you're suggesting is possible, but I don't think it's very practical. It's like putting some water in a bottle and having the temperature eventually drop to the point where clouds form in the bottle. You can make it happen, but... You don't really see it happen normally. With the dry ice, we're getting about a 200˚F temperature drop. Suspect you'd need a similar hot -> cold change your way.

[panzuman]

@JeffersonLab huh well ill try it and see how it goes iff it can show up on my camera i will post the video but with that piston idea perhaps i will use a syringe. also since bismuth has a rediculously long halflife can i just use a sample of bismuth metal? or would the time span between the emissions be to long to maintain intrest?

[JeffersonLab]

@panzuman You mean bismuth-209? They only discovered that it was radioactive in 2002. It's something like 10 billion times less active than U-238. You're not going to get a thing using it in a cloud chamber. But, let me know how it goes anyway. It'll be highly interesting if you get it to work!

[ScientificSolutions]

Thanks for the simple instructions for constructing a cloud chamber. I look forward to building my own and testing it with an Americium source (from an old smoke detector)!! Please keep up the informative videos!

[meowmeow5]

i noticed when steve is holding the radiation source, he put the canister down and when it zoomed in he is holding the canister again, and when it zoomed out its on the table again!

[JeffersonLab]

@meowmeow5 When you only have one camera, you don't necessarily shoot in sequence. Shooting an extreme close-up without zooming in required us to set-up a completely different shot. So, you'll sometimes get little continuity errors.You may also notice that the scene before a cut to a close-up is slightly different than the scene after the close-up. Everything you see from one camera position isn't necessarily from the same take.

[Unclesamslair]

I'm sorry, did you say I need a "source of radiation"? They don't just sell plutonium at your nearest Walgreens ya' know.

[JeffersonLab]

@Unclesamslair And that would be why we told you the name of the company we bought the source from.

[Unclesamslair]

@JeffersonLab umm, yeah. I know that. I was merely making a vague reference to the film "Back to the Future".

[JeffersonLab]

@Unclesamslair Ahhh, gotcha. That's my favorite movie but the quote was altered enough that I didn't recognize it. I assume you were altering "Doc, you don't just walk into a store and ask for plutonium. Did you rip this off?"

[Unclesamslair]

@JeffersonLab yeah, it's been ages since I saw the movie, the details are a little sketchy.

[theplatypus3]

could i use the radiation source from a smoke detector?



[JeffersonLab]

@theplatypus3 The americium source is mainly an alpha emitter, so it'll make tracks like our lead source. However, I'm under the impression that it isn't legal to physically remove the source from smoke detectors.

[canijitoveloz]

Ciencia al alcance de todos :-)

[Picapacapo]

So could I use Americium 241 for this? I believe it is mainly a alpha emitter, and it's also fairly safe.

[JeffersonLab]

@Picapacapo Yes, that'll work as well.

[nkip9230]

Hello!

How successful is this in looking at Cosmic Radiation? Im not so sure my school would allow me to use a radioactive source.

[JeffersonLab]

@nkip9230 This thing? Not very. It's too small to get a reasonable count rate with cosmic rays. You can detect them, but you'll need to be really, really patient.

[nkip9230]

@JeffersonLab Would a larger scaled version of this make this more successful? Or should I just try and go for a radioactive source?

[JeffersonLab]

@nkip9230 It's certainly easier with a source, but people tend to get overly agitated whenever the word radiation is spoken. The lead-210 source that we have has a long enough half-life that you won't jump through hoops on a yearly basis to replace it.

For a reasonable chance at catching cosmics, you need something about the size of a shoebox. It's certainly doable, but the tracks aren't nearly as good as the alphas you ultimately get from Pb-210.

[xylol1018]

First off, very good and informative video! My friend and I tried doing this for a Physics lab but we are having trouble making the clouds in the pitri dish. We have a 5lb block of dry ice (it's the smallest I could buy), a pitri dish with isopropyl soaked felt around it. We have the lid of the dish on also. We warm it up in our hands and place it on top of the block and we are not getting clouds in the dish. We get them if we take the lid of, but only for a second. Any suggestions?

[JeffersonLab]

@xylol1018 First of all, it does take some time for the inside of the Petri dish to get cold enough for the tracks to form. Through the magic of editing, we chopped about a minute or so of cool down time from our video, so don't use it as a basis for how quickly things should start working. Also, the isopropyl needs to be as pure as possible. You didn't say what percentage yours is, but the most commonly found type usually isn't good enough.

Good luck!

[JeffersonLab]

@xylol1018 Oh, one other thing. Early on, we found that it sometimes helped if part of the Petri dish extended out over the edge of the dry ice. This set up a temperature differential that created a 'breeze' inside the Petri dish. In our case, it helped distribute the alcohol vapor inside the Petri dish. That problem was largely solved with the alcohol soaked felt around the inside rim of the Petri dish, though...

[airsoftspain]

cool vid

oh dawg

[Sfredrick]

great!

[TenThousandSubbies]

Next time, would it be possible to hold the flashlight still?

Also, science isn't zany. Don't be zany. Be normal, or you're going to scare the normal kids away from science.

[JeffersonLab]

@TenThousandSubbies Yeah, it took us awhile to find the right angle for the tracks to show up. We should have gone back and reshot that sequence once we knew the right position. But, we didn't. The later footage is still pretty good, though, once you get past the first stuff.

As far as being zany... I don't see how any of this is zany. There's a throwaway exchange at the end and the bit where the gloves are tossed. Other than that, it's pretty cut and dry. It's not like pies were thrown.

[xzeen69x]

why cant you touch the needle?

[JeffersonLab]

@xzeen69x It isn't hard to transfer some of the radioactive material off of the needle. If you touch it, there's a chance you'll end up with some of the material on you.

[69iron69]

You should put a magnet on or in the cloud chamber and try and calculate the charged particle mass.

good video

[JeffersonLab]

@69iron69 We've actually been kicking that idea around. Plus, it'll give us a chance to pronounce polonium correctly!

[c0ldelement]

Ive actually used isotope from a smoke detector in my cloud chamber..

[ollyk22]

Wow, try to order any of those items here in the UK and you get the police ringing you as a terror suspect lol seriously people are being interviewed for purchasing isopropyl!

BTW what is the radioactive source within a smoke alarm or maybe it would be a bit silly pulling one of those apart...?

[JeffersonLab]

@ollyk22 The stuff in smoke detectors is americium-241 (mainly an alpha emitter), although I don't think it's legal to remove the source from smoke detectors.

[hellgodhaven]

lol did he just throw away the needed govles XD

[JeffersonLab]

@hellgodhaven Well, they weren't needed right then.

[milesjsandifer]

ponolium is not known to me, help me understand, is it like polonium?

[JeffersonLab]

Yes, it's the same thing, just mispronounced.

[10zaq10]

what are some other sources of radition i could possibly use?

[JeffersonLab]

The commercial sources are really the best. They aren't all that expensive and you know what you're dealing with.

The only thing I can really recommend for a home brew source is a Coleman lantern mantle. At one point, they contained thorium. I don't know if they still do or not, though.

[pepsifxr]

What a fun project! I am trying to interest my grandson in different sciences. I have him looking into a great many things. This will be one of them. Thanx for sharing.

[SonOfFurzehatt]

It alarms me slightly that these people are saying 'ponolium' instead of 'polonium'.

[JeffersonLab]

Well... as long as you are only slightly alarmed.

[iAlphatv]

Where can i buy one of these petric dishes!

[JeffersonLab]

Any science supply store will carry them. I believe we got ours from Carolina Biological. You can do a Google search for 'petri dish' and see whose ads appear.

[Hahaamproductions]

What happens if you dont have a radioactive needle will it work or no?

[JeffersonLab]

It will work, but you'll have to depend on particles created by cosmic rays. For that type of thing, the larger the volume of the chamber, the better. Our petri dish chamber is too small to effectively use cosmic rays as a source.

[SmokeWeedEveryHour]

@JeffersonLab So basically I could make this on a large scale without needing a radioactive source? And about how big would this have to be for it to use cosmic rays as a source? Also, is it possible to make something like this that works permanently? Because I was thinking this would make an awesome decoration, a lavalamp kind of thing, you know?

[JeffersonLab]

@SmokeWeedEveryHour Yes. The average flux of cosmic rays is about one per minute per square centimeter. Figure a cube about 20 centimeters on a side should give you several tracks per minute. They won't be as obvious as the tracks made by the alpha particles, but they'll be there.

You can also make it work permanently, but it'll take a fair amount of active control on your part. You have to keep the air inside saturated with alcohol vapor. It won't stay that way without help.

[SmokeWeedEveryHour]

@JeffersonLab That's very helpful, thanks alot! I guess it would be possible to make a slow release system to keep the sides covered in the alcohol. I'd need a cooling system though, hmm.

[919664]

what would happen if I  would touch the tip of the needle ?

[JeffersonLab]

It's possible for some of the radioactive material to be transferred from the needle to your finger.

[919664]

@JeffersonLab and what will happen then to me (or my finger)

[JeffersonLab]

Most likely nothing. The amounts of radiation involved are very small and a good portion of it is alpha radiation, which is blocked by the outermost (dead) layer of skin. If it works its way into your body, where it can come into contact with living tissue, that's more of a problem. But, again, the total amount of radioactive material on those needles is very small.

[Snopphooy]

haha 1.17-1.19 xD ur face man!! priceless

[Snopphooy]

haha why did you toss away your gloves man!?

[JeffersonLab]

We weren't going to handle the dry ice, so we didn't really need the gloves. The table was already crowded enough, so getting rid of them seemed to be the right thing to do.

[Envergure]

FYI it's "polonium," not "penolium," lol

Why don't beta emissions create trails?

[JeffersonLab]

The betas do create trails, but they are much more difficult to see. They have half of the charge of alpha particles, so they aren't as effective at ionizing the air. They are also ~7200 times less massive, so they travel much faster. As a result, their trails aren't as obvious as those created by alpha particles. In reviewing the footage, I see two tracks that are good beta candidates.

[dudegutarman12]

couldn't you just boil the isopropyl (sp?) alcohol & water solution to make it closer to 100% I'm assuming that the boiling point of water is lower here.

[JeffersonLab]

You could, but you would still need to condense the alcohol vapor again. If you happen to have a fractionating column you could give it a whirl. Don't know if the isopropanol/water mixture forms an azeotrope or not, so it may be more complicated than this.

[thedoors781]

:13 Hey!  LOL

[petwalk123]

how do u get if from a vender?

lol

[JeffersonLab]

The usual way. You place an order and pay for it, then they ship it to you.

[petwalk123]

what is the radiation source?

laser pen?

[JeffersonLab]

Lead-210.

[adheeb]

what type of radiation source will we need if we want to analyze or see muons in the cloud chamber?

[JeffersonLab]

I'm going to have to talk with a couple of people before I can give you a reasonable answer. Give me a few days...

[Pimpmastahanhduece]

hey, i have a tritium light source which uses phospheresence to make a green beacon. will this provide enough high speed electrons to catch in a cloud chamber?

[JeffersonLab]

It's hard to say without knowing the activity of your sign. We have a lantern mantle that our Geiger counter loves, but doesn't do anything in the cloud chamber.

Give it a try and let us know what happens!

[ScrewAttackChina]

@adheeb you can use Americium 241, just rip it out of a fire alarm

[JeffersonLab]

Radioactive sources don't have the energy to produce muons. You need an accelerator or need to get lucky with cosmic rays.

[gork42]

It's true that some places do carry 99% isopropanol, but in many places even finding the 91% can be tough.

There is a readily available alternative, however. You can get Iso-HEET (the red bottle) at most auto parts places. It's 99% isopropanol. It's not technically "lab grade" though and does have other contaminants (for instance it leaves soot when it burns) so be aware of this if it will be a problem for your application. For a cloud chamber it should be fine.

[JeffersonLab]

Good tip. Thanks for that.

[adcurtin]

My local grocery store carries 99% isopropyl alcohol, I don't think it would be too hard to find at a drugstore.

[beutifulsoul2359]

oo aaa what the heck?

[Tyler31246]

"when you handle dry ice, be sure to wear gloves" *throws gloves away* xD

[Cosmodot256]

Ok... So you pronounced Polonium (a radioactively unstable metalloid element) incorrectly, but the video was very helpful and interesting.

The setup is cheap to reproduce, so you guys could always make another video... I thumbed up this one on stumbleupon. 5 stars!

[JeffersonLab]

We may revisit this in the future to show how charged particles are deflected by a magnetic field. We have a lead on a coil that may give us enough field to see something. However, given our pronunciation difficulties, we may just skip saying the name of the element altogether. :-)

[snarfgibble]

They both said "ponolium".

[JeffersonLab]

Yeah, we both botched it. We were practicing ahead of time and were saying that the element is named 'polonium' as in Poland and not 'ponolium' as in linoleum. But, when the time came, we both said ponolium. We didn't catch the error until a few weeks later when we were making the closed captioning file. Since YouTube doesn't let you edit posted videos, we decided to let it stand. We've heard about this from people at the Lab as well. Getting made fun of by particle physicists is embarassing...

[snarfgibble]

lol - ponolium - it's kinda cute.

Didn't Mme Curie name polonium cuz she was from Poland??

Anyway, good vid, thanks.

[JeffersonLab]

Yes. It was named in honor of her homeland.

[QuantenMagier]

lol i first understood polynom because english is not my native lang, anyway i thought since Alexander Litwinenko was killed with it anyone knows polonium or didnt this story got over the great sea to amerika? :-/

[JeffersonLab]

Of course the Litvinenko story made it over here. The element's proper pronunciation, however, didn't lodge itself into our brains. It was three years ago, after all.

[DaCaSh100]

Were do you guys get your ideas for experements? They are really cool

[JeffersonLab]

Here and there. We have a show we do for school groups and a number of these videos have been adapted from that. There are other experiments that we just don't do because they aren't suited of large groups, but film well (things that are too small to see unless you're close to it. We see things at conferences from time to time that are cool. I guess when you've been around for awhile, you tend to pick things up.

[turner850]

Holy the flash light better

[JeffersonLab]

Yeah...

A lot of the problem with that is that the person holding the flashlight isn't seeing what the camera sees. When the person could see the tracks well, the camera couldn't and when the camera could see the tracks well, the person couldn't. It took us a little while to figure things out. We probably should have reshot that sequence once we found the right location but, we were so happy that it worked at all, we called it good and moved on.

[dgk990]

what happens if you use uranium insted of radioactive lead?

[JeffersonLab]

It would essentially be the same thing. U-238 is an alpha emitter, so you would get tracks similar to what we had. You would also get additional alpha and beta particles from the other isotopes in U-238's decay chain. The last three radioactive isotopes in U-238's decay chain? Lead-210, bismuth-210 and polonium-210, the very isotopes that we were using!

[X00C]

uranium isn't effective in radioactive protection, only lead is. Therefore it would not hold the radiation a a safe possition.

[JeffersonLab]

The original comment was asking about using uranium as a source, not as a shielding material. Also, lead isn't always the best shielding material. It depends on what type of radiation you are trying to shield. Want to shield gamma radiation or x-rays? Lead is a good choice. Want to shield neutron radiation? Then you're better off with something with a lot of hydrogen in it, like water or paraffin. Want to block alpha radiation? Then you just need a sheet of paper.

[icedbrasil]

Great vid!

Greetings from Brazil!

[kemry55]

w\you guys are cool

[refolexx]

I wish my science teacher made things seem as simple as you guys do -.-

[JeffersonLab]

Thanks! But, to be fair, we have the advantage of getting multiple takes and editing. Your teacher is live all the time.

[kurtu5]

Put a magnet on top! Lets see if we see any charged particles!

[JeffersonLab]

I tried that in testing. The alpha particles have a charge of +2, but... they are too massive for us to deflect with the magnets I have on hand. The betas are easy to deflect, but they don't show up that well in our chamber (there's only one that I see when I watch the video). I'm thinking of winding a coil around the Petri dish itself to see if that'll do anything. If it does, it has the advantage of allow me to reverse the current in the coil to reverse the curve of the tracks.

[L3G3nD0001]

Try Neodymium magnets. They're more effective in a cool temperature.

[stormrider1984]

That's SO cool!

[sriv121]

4th july lol!

[ScienceChicago]

Great science experiments! Keep up the great work,

Science Chicago

[tutorialconr]

Thanks guys!

[tutorialconr]

Thanks for posting again! I am waiting for more ;-D

[postonsucks22]

Awesome!