Cloud Chamber Experiment (1 Viewer)

[shadowRRL]

Can someone give me fine details of how the cloud chamber experiment is done?

 

[deweydude]

Ok, have you ever looked up into the sky to see the jets forming a vapour trail? It is much like that! I'm going to put this into laymans terms for you (no offence dude). The cloud chamber is cooled to very cold temperatures (in the experiment we did we used dry ice), there is an alcahol inside the chamber which, when cooled, causes a mist to form. We attach the source (alpha, beta, or gamma) to the chamber and as the particles shoot through the chamber they kind of 'cut' the vapour, leaving trails. By analysing these trails we can tell how the particals move and we could also 'see' the particles for the first time. It is really really weird to watch, you should have done it in class.....why didn't you take notes?

 

[Constip8edSkunk]

well none of the 99 students in my school did it, and its a selective school so im pretty sure heaps of other school didnt do it. besides isnt the dot point only asking for describing your observations anyway on how it detects radiations? the supersaturated vapour within the chamber condenses around ions ionised by the radiation, thus leaving a visible trail showing the path of the radiation. Look at the colour pictures in jacaranda and describe what you see.

 

[deweydude]

My school isn't selective, but our teachers are kind of different. They have this way of doing this really really well, and really really quickly so we have time for lots of stuff at the end. And everyone understands what is happening and stuff. It's just so much better if you see it done, it looks so cool and it helps you to understand so much more better than just seein some pictures. It's like the difference between tryin to describe goin on the Space Probe and actually going on it.

Your school did take you to wonderland when you were doing Space didn't it?

 

[deweydude]

You go to wonderland to learn about things like G-Forces incase you were wondering.

 

[Constip8edSkunk]

nope we go there in year ten when we first do the newtonian laes etc

 

[shadowRRL]

By the way for those who dont know which topic this is from, it is from Quanta and Quarks...

 

[Skunkylicious]

our school did the chamber experiment but it never worked! but we got the general idea!

 

[Q2Q]

Ok this is gonna be an extentsion of the main Question... just to make sure.. does gamma radiation actually leave a trail? u know how its a wave and not a particle hence is does not ionise by collision .. so whats the deal?

 

[t-i-m-m-y]

Originally posted by shadowRRL
By the way for those who dont know which topic this is from, it is from Quanta and Quarks...

oh okay.... i was wondering had me scared for a moment

 

[Dave85]

i do med physcis but learnt bout cloud chambers in chem... not sure if this will help but this is wat i know bout them (from memory):

cloud chambers contain a super saturated vapour of either water or alchohol. When radiation is present, it causes air to ionise... These ions then form nuclei which forms liquid droplets. When radiation is present, it causes the path to be shown.

Sory if that doesnt help!

 

[shadowRRL]

thanx alot people u all have been a great help to my understanding of this experiment...

salute to all

 

[walla]

Can anyone answer Q2Q's question on whether cloud chambers can detect gamma radiation?

 

[allyteaded]

Originally posted by Q2Q
.. does gamma radiation actually leave a trail? u know how its a wave and not a particle hence is does not ionise by collision .. so whats the deal?

Yes, you're right. It does not leave a trail which is why you cannot perform the cloud chamber experiment on Gamma radiation. Good someone else spotted that - because I thought I was imagining things for a second and panicked like a headless turkey...

I wasn't present when the teacher did the prac in front of the class but he explained it to me later and showed me the apparatus. I remember him saying the cloud Chamber can only detect Alpha and Beta particles (I have a good memory for listening... I only really study in class and I came first in phys this year ). I have notes from when he explained it all to me... but I have yet to go through them and rewrite them properly.

Aside from describing the prac, you gotta make some observations right? Like why Beta particles have a thinner trail than Alpha? Because Alpha particles are much larger in size; they consist of Two Protons and Two neutrons whereas the Beta particle is a fast moving electron.

 

[Constip8edSkunk]

you should be able to see gamma rays using the cloud chamber. the vapour so not condense on the alpha particle or the beta particle but the ionised particles in the air. Although gamma is a weaker ioniser than alpha and beta particles, it still ionises.. and the the vapours would condense around the ions

alpha particles had thicker trails cuz it has the greatest ionising ability

 

[AK Gumbi]

yeh skunk ur right. you can see gamma rays. we got a 'cloud chamber' prac handout sheet and i quote directly from the sheet:
"Observe gamma or X-ray tracks from a source such as Cobalt-60. These are seen as very obvious squiggly lines that follow a short, random path."

So...

alpha particles: short, shooting lines from alpha source (eg Am-241)
beta particles: faint wavelike, parallel lines visible for only short period of time (source: St-90 or Cs-137)
gamma rays: obvious squiggly lines that follow a short, random path (source Co-60 for eg)

 

[pocydto]

My school never performed the wilson cloud chamber experiment and I still don't understand everything about it.

What does it mean by ionisation? I heard this term lots and never get an explanation.

Finally, does alpha particles leave wavy tracks or straight tracks?

Also, I came across a question in a past paper, and it asks how to distinguish the trails left by alpha and beta particles. Apart from the beta particles being thinner, what else is different?

Thx in advance

 

[AK Gumbi]

Ionisation: removal of electron/s from atom
Alpha particles: sharp, shooting lines (straight)
Beta particles: they are fainter, travel in parallel lines

 

[Roors]

does anyone have like a review sheet or some notes on the experiment...i'm so lost, my teacher never mentioned it!

 

[pocydto]

Roors: I found this site after searching in google http://www.geocities.com/CapeCanaveral/Hall/1410/lab-Project-04.html

It's not really all that helpful but that was the best I could find...