Sciencemadness Discussion Board - What would you do with an Electron Accelerator?

What would you do with an Electron Accelerator?

KyleO - 11-7-2016 at 17:08

Good evening everyone,

I represent the Huntley High School Experimental Science Society, and we are a student founded, student run organization dedicated to a whole host of sciences.

One of our projects which has been in the works for a while now, is the construction of a Linear Electron Accelerator. The accelerator will use a modular beam usage system, allowing us to easily and effectively swap a wide range of experiments/sensors into the target chamber, at our discretion. That said, we are aiming to make the beam 1.5 MeV strong, so that we may create and detect positrons.If you had access to a 1.5 MeV electron beam, what would you use it for?

Some other thoughts would be [attempting to] making tin powder, electron welding, testing the effects of radiation, what else could a beam of that power be used for?

Below is a bunch of information about the project, hopefully clear up any questions. If anybody thinks of a cheaper/better/more effective way to do something, by all means!

Also note, we do recognize that we are to be held liable to our own actions in any legal disputes, should they arise (They shouldn't, see the "safety" below)
_________________________________________________
A bit more about the accelerator
Principle
In a sentence, the accelerator will function by utilizing a very large negative charge near our source, which when coupled with the positive charge near our target, creates a difference potential which we will utilize to accelerate our electrons to total of 1,500,000 eV.

Power
You can’t just plug a particle accelerator into the wall. Therefore, we’ll be utilizing pure static sources. We’ll be using custom made van de Graaff generators, coupled with a series of Leyden Jar style capacitors. This equipment will allow us to reach the voltages we need, in a safe and cost effective manner.

Source
We will be utilizing a Tungsten filament, generously donated by Kimball physics, for our source of electrons. When activated, electrons will be emitted at approximately 5 eV, just enough to enter our electric fields.

Vacuum
Our vacuum system has two parts: First, a two-stage mechanical pump removes 99.9% of the air from the pipe. For this, we will be using an Edwards vacuum pump, also kindly donated by Kimball Physics. Secondly, an oil diffusion pump removes the remaining 99.99999% of the remaining air. The quality of our oil diffusion pump will depend on our budget.

Location
Due to expansions on the School, a new courtyard has been created. We will be constructing the machine in this location. Not only is the area locked off from the general public, it is spacious enough that we may easily expand should the budget permit. The core machine is dismantlable, so that in the winter, we may move sensitive components indoors for storage.

Safety
Radiation
A machine of this size and caliber will cause radiation. There is no way around this. However, we are prepared beyond a doubt. Not only are all of our operators trained in radiation from the school curriculum, but we have an additional training program required for all student members. Our much more rigorous course includes all information required for us to be IEMA compliant, and then some.

We utilize A.L.A.R.A principles in operation, and design. First and foremost, our largest protection will be shielding. Over half the budget will inevitably be spent on lead shielding around the reaction chamber, the accelerator, and the areas around the courtyard. In addition to our own installed shielding, the courtyard itself provides excellent coverage. By definition, the school is required double as a storm shelter, which means heavy doors, and heavy brick. The machine will be operated largely from indoors, for the extra protection for our members.

In addition, for personnel who are not indoors during operation, lead aprons will be supplied. As if all of that isn’t enough, our operators will also be supplied with pocket ionization chambers, for the added peace of mind.

Electrical
A machine of this size and caliber will be utilizing a high amount of high voltage electricity. Therefore, not unlike our course for radiation, we will be training our personnel similarly for electricity. In addition to this, our entire machine has been designed to be O.S.H.A compliant for electrical construction, in accordance to 1926.400 subpart K. All of our machines will be accessible via our operators, in such a way, that we may safely discharge our capacitors from several feet away. This, when combined with radiation safety, culminates in a safe, efficient, and effective environment with which to operate.
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This isn't the point of this post, but if you're feeling generous and would want to contribute to the project financially, we're not going to say no! We go to a public school. We're getting squat from them. Of course, as with all amateur experimentalism, it isn't the cheapest pursuit. https://www.gofundme.com/accelerator if you're interested.

Yours in Science,
Kyle ~ Grade 12

j_sum1 - 11-7-2016 at 19:00

What would I do with an electron accelerator??
Watch TV.

phlogiston - 12-7-2016 at 01:51

Lichtenberg figures

To be honest, I find your post a little odd, but possibly that is because of your young age. You are working on a very ambitious project and seem completely confident about the technical challenges of building and operating it safely, but need ideas on what to use it for? Why have you chosen to build it then?

I know it is not the purpose of your post, but regarding safety, you appear extremely confident in your ability to build and operate it safely… a little too confident to my taste. Would it not be better to be more critical about it? Continuously doubt it. Worry about it. Picture accidents in your mind.
For instance, you intend to buy massive quantities of lead, but mention dosimeters almost as if they are a luxury. Just to ‘be safe’ after you bought all that lead. Shouldn’t dosimeters and other measuring equipment be a far higher priority? How are you going to know if you have sufficient shielding in the right places? Which areas around the machine are safe, which are not? Maybe you need far less shielding than you think. Maybe you can simply put some more distance between people and the machine.

[Edited on 12-7-2016 by phlogiston]

Sulaiman - 12-7-2016 at 05:36

I too suggest Lichtenberg figures in acrylic https://www.google.co.uk/search?q=Lichtenberg+figures&so...

You could earn quite a bit of cash for the project via eBay
http://www.ebay.co.uk/sch/Collectables/1/i.html?_from=R40&am...
and give souvenirs to your main sponsors (you really should)

a few metres of air will probably be enough 'shielding' for 1.5 MeV electrons

IF you can get to 1.5 MV (good luck with that !) the current will be minute,

BUT
I believe that 'hard' X-ray generation is the main hazard, at a very low doserate.

There is a strong possibility of causing non-radioactive materials (hand tools etc.) to become hazardous waste

KyleO - 12-7-2016 at 07:34

Quote: Originally posted by phlogiston

Lichtenberg figures

To be honest, I find your post a little odd, but possibly that is because of your young age. You are working on a very ambitious project and seem completely confident about the technical challenges of building and operating it safely, but need ideas on what to use it for? Why have you chosen to build it then?

I know it is not the purpose of your post, but regarding safety, you appear extremely confident in your ability to build and operate it safely… a little too confident to my taste. Would it not be better to be more critical about it? Continuously doubt it. Worry about it. Picture accidents in your mind.
For instance, you intend to buy massive quantities of lead, but mention dosimeters almost as if they are a luxury. Just to ‘be safe’ after you bought all that lead. Shouldn’t dosimeters and other measuring equipment be a far higher priority? How are you going to know if you have sufficient shielding in the right places? Which areas around the machine are safe, which are not? Maybe you need far less shielding than you think. Maybe you can simply put some more distance between people and the machine.
[Edited on 12-7-2016 by phlogiston]

I forget, I'm not talking to school officials on this board

- You need the confidence (or at least, the appearance of it) if you want them to let you build the thing on school grounds

Excellent points - we're trying to get lead through donations mostly, but in the event that gets cut by budget our (very likely) plan B is going to be a filled, concrete block wall, possibly surrounded with a lead foil because that is a heck of a lot cheaper, but we could do without it as well. If I did my math correctly with the Half Value Layers, we should be able to get the energy down to roughly 100 KeV with plan B. From there, as Sulaiman pointed out, "it should be a few metres of air will probably be enough 'shielding' for 1.5 MeV electrons" - so we'll just let the inverse square law take its hold for the remainder of it. I do think we'll need to take your advice and redirect our funds to some more dosimeters, especially if we go with plan B. Knowledge is power!

Also, the idea to go modular is fairly recent - our original goal was to do pair production, but we redesigned the target chamber to allow easier access, then started thinking about finding some linear attenuation coefficients, and now we're here! And I'm glad I asked, because Lichtenberg figures are pretty great, and something I think we could manage - perfect for sponsors!

ParadoxChem126 - 12-7-2016 at 09:29

Nice project. In terms of power supplies it may be more economical and practical for you to use conventional high voltage power supplies/electronics vs. the Van de Graff generators. You will be able to supply more power and have much greater control over voltage and emission current. There would be fewer moving parts and it would be considerably more compact as well. Good deals on high voltage equipment frequently appear on eBay, so it may be worth a look.

Morgan - 12-7-2016 at 11:49

I was thinking the same thing.
https://www.youtube.com/watch?v=xoKloJwmLjI#t=1m43s
https://www.youtube.com/watch?v=h57xNxG_tSg

Bert - 12-7-2016 at 11:57

Good luck.

Obviously, the next thing to do once you have a reliable beam output is set up a particle storage ring fed from this linac, then develop uses for the synchrotron radiation emmited at the bending magnets- such as vaccuum UV microcircuit etching, nano-scale device optical fabrication stations (and for your honors class project, your very own free electron LASER).

Ion pumps with Ti getters in addition to your other vacuum pumps... And cement with Iron ore as aggregate for cheaper bulk radiation shielding, just sayin'.

My skinny 20 ish year old self helped build this machine... But I certainly was not on the design team.

[Edited on 12-7-2016 by Bert]

KyleO - 13-7-2016 at 05:35

Bert - O b v i o u s l y, that is the next step

; that may be a bit of scope creep, but hey, if we have money and time left over (somehow), its something to think about. Also, two gems in one post! Ti getters and iron aggregate... I would've never thought of Iron Aggregate, and I didn't even know Ti Getters were a thing which existed, so that's something to look into~ As for the project you worked on, that's really cool! I'm trying to figure it out by looking at the picture, but I'm stumped - where did you build that? Didn't you need to worry about any radiation?

phlogiston/Sulaiman/Morgan - I don't know how much any of you know about this process, but I was looking into Litchenberg Figures, and most producers (https://www.youtube.com/watch?v=9Po35g23fYI) seem to have the target area outside of a vacuum. This particular video obviously does, because they wouldn't bring an entire room to a vacuum, and they reference the accumulation of O3. So, here is my question: What do people use at the end of the accelerator itself to contain the vacuum, yet allow beta particles to still pass through to hit the acrylic? My thought would be, they just use a chunk of Tungsten at the end, and let the bremsstrahlung radiation do its thing...Then you're blasting the block with radiation though, right? Thoughts?

Thanks!
Yours in Science,
Kyle

Sulaiman - 13-7-2016 at 06:01

A 55 MeV electron accelerator that I helped commission used a titanium foil window for lower power 'testing'

Bert - 13-7-2016 at 06:49

That is a picture of the University of Wisconsin's Alladin synchrotron storage ring, which was built in a 12-20 ft. deep hole (down to the bed rock, for stability and radiation shielding) near Stoughton, WI. I watched the excavation... And ended up working on various control systems for 3 years as a student employee. Only "film badge" job I have ever had-

My father had helped build an earlier machine, Tantalus, for MURA about 1/2 mile away. The nice flat stable bed rock there was an important factor in choosing both sites.

KyleO - 13-7-2016 at 07:17

Quote: Originally posted by Sulaiman

A 55 MeV electron accelerator that I helped commission used a titanium foil window for lower power 'testing'

So, just to be sure I understand this correctly, you essentially took a sheet of Titanium, and stuck it on the end of the tube?

=====| <~ Like that?

For 55 MeV? Oh boy...

And bert, the 20 foot deep hole clears up a LOT - Somehow I didn't get that from the picture

Marvin - 13-7-2016 at 07:33

I wouldn't start with 1.5Mev. Scientific American Amateur Scientist has a design for an electron accelerator, about 100kev I think. Uses a VDG and a supported aluminium foil exit window. This is enough to examine things like radiation effects on seeds.

Lead is a bad plan for shielding. Expensive, and High Z materials produce dangerous X-rays when hit by energetic electrons which are much harder to shield.

KyleO - 13-7-2016 at 08:01

Quote: Originally posted by Marvin

I wouldn't start with 1.5Mev. Scientific American Amateur Scientist has a design for an electron accelerator, about 100kev I think. Uses a VDG and a supported aluminium foil exit window. This is enough to examine things like radiation effects on seeds.

Lead is a bad plan for shielding. Expensive, and High Z materials produce dangerous X-rays when hit by energetic electrons which are much harder to shield.

I think I know the article you're talking about...wasn't that from like 1960?

Bert - 13-7-2016 at 12:35

That building (and the full size basement, made up of the machine vault and a support shop) had a footprint a bit larger than 2 football fields. We used to play Frisbee in there on our lunch break, until the researchers showed up and occupied every square foot with beam line ports and experimental aparatus.

[Edited on 13-7-2016 by Bert]

KyleO - 14-7-2016 at 10:03

Quote: Originally posted by Bert

That building (and the full size basement, made up of the machine vault and a support shop) had a footprint a bit larger than 2 football fields. We used to play Frisbee in there on our lunch break, until the researchers showed up and occupied every square foot with beam line ports and experimental aparatus.

[Edited on 13-7-2016 by Bert]

Incredible... Absolutely Incredible