What wires should I use for my wire chamber?

[BiemNL]

TL;DR Summary

Scientists use gold plated tungsten wires for wire chambers, and I wonder if it can be done with other (and cheaper) materials as well (like silver).

I want to make my own multi-wire chamber for school, and I wonder what kind of effect different wires will have on the efficiency. After reading many papers containing research for wire chambers, I saw that all of them did tests with wires made of gold plated tungsten wires with a diameter of 0,02 to 0,03 mm. I really don't have enough money for those kind of wires, so I was thinking of cheaper alternatives. First, I wanted to know why the scientists in the paper chose gold-plated tungsten wires at all. The answer was nowhere to be found. They all just state that they are using it, not why. I concluded that it had to do with oxidation on the wires. An efficient wire chamber should be able to "absorb" the electrons, and that would be why they chose for a gold coating. Gold is a noble metal, so it almost doesn't oxidize at all. Meaning, there wouldn't be an insulating barrier for incoming electrons. At least, that is my theory.

If my theory is right, and that the low oxidation rate is the only characteristic necessary for an efficient wire chamber, I can buy silver wires instead.

I would love to hear people's opinions about it, and also hear what other characteristics of gold plated tungsten wire made people use it for wire chambers.

 

[Vanadium 50]

The answer was nowhere to be found.

Really? It couldn't possibly be that the answer was in the literature but that you didn't look hard enough to find it? Did you look at Charpak and Sauli? That's a whole article of "why".

Your theory is wrong. Oxidation requires oxygen (hence the name) and these chambers do not use oxygen, and for good reasons there is no oxygen in the chambers. It is a by-product of the light bulb industry, and both applications require a wire radius with minimal variation. A quick look at the web shows you can get a roll of this for $20 or so.

If $20 is too much, I can't see how this is ever going to work. What are you going to use for gas? What are you going to use for high voltage? What are you going to use for readout electronics?

 

[BiemNL]

Well first of all, I don't have the literature for it, I have to do it with random papers. Second, I am building the chamber myself, so moving the thread from the roll to the chamber will still make the thread oxidised (my house is not a vacuum). And third, for that one ad on aliexpress there is an uncertainty about the length of wire that I will be purchasing. I have contacted the buyer and he still hasn't answered. All other wires are like 100 euro a meter.

 

[Vanadium 50]

Well first of all, I don't have the literature for it, I have to do it with random papers.

Then you should pick another topic. It's hard to make these work, especially your first one, Trying to do this without proper instructions - i.e. the relevant papers - is not a good plan.

Second,

One of us has built, operated, repaired and rebuilt many of these devices including buying many miles of such wire from Osram Sylvania() before. The other one hasn't. Who should we believe?

And third

Well, then don't buy it from the shady vendor. Buy it from someone else. Google finds vendors with 1m spools.

But you seriously need to be thinking about the other issues I brought up, What are you going to use for gas? What are you going to use for high voltage? What are you going to use for readout electronics?

 

[BiemNL]

Then you should pick another topic. It's hard to nake these work, especially your first one, Trying to do this without proper instructions - i.e. the relevant papers - is not a good plan.

One of us has built, operated, repaired and rebuilt many of these devices including buying many miles of such wire from Osram Sylvania() before. The other one hasn't. Who should we believe?

Well, then don't buy it from the shady vendor. Buy it from someone else. Google finds vendors with 1m spools.

But you seriously need to be thinking about the other issues I brought up, What are you going to use for gas? What are you going to use for high voltage? What are you going to use for readout electronics?

I don't know if you understand what i'm saying. If I use a metal that oxidizes easily, it will get oxidized when making the chamber. It won't oxidize anymore when it's already in the chamber, but it will when building it. I am just asking if that is a big issue, which I think it it, but I need someone to confirm. IF I can get a spool for less, I would love to know. The 1m spools go out of my budget (I need around 14 meters). If you somehow do know a place where I can get the wire for low prices, can you at least give me a link?

If you really want to know, I am going to use 82% Ar 18% CO2 welding gas. I am still figuring out the electronics, but the type of wires is my main concern, cuz I really can't find why I need to use that type of wire.

 

[Vanadium 50]

Again. I have built these devices. You have not. Your theory is wrong. I've actually used steel for wires. I do not recommend it, but it can be made to work. Your theory claims this is impossible.

Maybe...just maybe...it would be better to wait until you've successfully built one of these before pushing your own theories.

Your gas will be very hard to make work. CO2 as a quenching agent is very fussy - you are much better off with a big molecule, like ethane. Furthermore, welding gas is of variable quality: a little air left in the tank and you get no signal - nitrogen is electronegative and oxygen even more so. Furthermore, you will need a way to put high voltage on this, and vary the high voltage: you will have a very small plateau with Ar-CO2 in general.

14 m of wire is way, way too much. You do not need to build something this big, or with this many wires - and if you can't afford the wire, you cannot afford the electronics for many channels. What does it look like? 14 m long and 1 channel? That's crazy! 1 m long and 14 channels? 10 cm long and 150 channels? You are being way, way, way too ambitious - and since the wire costs are a tiny part of the total cost (on a recent project they were 1%) if you can't afford the wire, you can't afford the project.

You also haven't described how you are going to tell that this thing is actually working.

I think you need to pick another project.

 

[berkeman]

Just out of curiosity, what's a wire chamber?

 

[Bystander]

https://en.wikipedia.org/wiki/Wire_chamber

 

[berkeman]

https://en.wikipedia.org/wiki/Wire_chamber

Thanks @Bystander -- I did a Google search on wire chamber physics but that didn't get me to links like yours. I need to refine my Google skills...

 

[berkeman]

And I see now why @Vanadium 50 said this:

14 m of wire is way, way too much.

 

[Vanadium 50]

Would you prefer we call them "gas chambers"?

 

[Vanadium 50]

In addition to all the other problems, how do you plan on demonstrating that this wire chamber is working?

 

[BiemNL]

Well, I don’t need 14 meters for one, I need it for 4. It would be like 3 meters for one box (15 wires of around 20 cm) I will stack them on top of each other. Let me show you one of the papers that inspired this. https://indico.cern.ch/event/505644...achments/1323221/1985287/mwpc_paper_rev_2.pdf
They also use Ar/Co2 gas.
The electronics can be really cheap right? I just mainly need a voltage amplifier for every wire and with other components I will send the information about what wire it was to a computer. I can stack my 4 detectors cross like so I will be able to generate a vector as a visualization. Can you also tell me more about the steel wire and it’s efficiency compared to gold plated tungsten?

 

[Vanadium 50]

They also use Ar/Co2 gas.

That doesn't mean it's a good gas for beginners. ArCO2 has a very short plateau. It's used because it is non-flammable, but other gasses work better - P10 (argon-methane), argon-etahne, argone-isobutane, even argon-CO2-freon.

Your welding gas likely has too much air in it. And you need some sort of gas flow system. Two flowmetgers, some tygon tubing, a valve for your tank of gas and you're tank. $20 here and $50 there and you're already more expensive than the wire.

The electronics can be really cheap right?

Nope. Usually the most expensive part. And you will need high voltage of a few thousand volts. And some way to read out your signal on top of this high voltage. If you have a half volt signal on top of 3000 V of HV, how do you plan to detect it?

And how will you know that it's working? A detector of the size you are talking about - which is way bigger than it needs to be to demonstrate the principle, and will end up costing a lot - will see about 1 or 2 Hz of cosmic rays. The electronics will determine the noise, but it's likely to be in the kHz range unless you operate it in Geiger mode. A lot of problems go away if you make it a Geiger counter, but you will get some new ones.

That should sort of set the scale - an actual Geiger counter (not the Chinese junk sold on E-nay) is $1-2K. You are triyng to build a more capable device without the benefits of economies of scale. Expect it to cost more - and if a few tens of dollars for the wire is too much, you can't afford the whole device.

 

[BiemNL]

The electric signal problem you are talking about can easily be countered. I will just put a high negative voltage on the cathode, so the field lines remain the same. The wires will stay neutral until a current will flow through it. That small voltage is everything I need, and it can be amplified easily.
About the gases, I am speaking to my local university to see if they have the equipment I need.
But anyway, instead of talking about the other problems, can you please just answer my original question, ant tell me what important factors there are for the wires used for this, and also tell me how much the efficiency has tanked of the steel wire you used?

 

[Vanadium 50]

I will just put a high negative voltage on the cathode

I think we're starting to cross the boundary of "unsafe". By doing it this way, you have HV very close to the outside of the chamber where people can touch it. Not good. You need to make sure there is no chance of a short from your cathode to your enclosure. The usual solution to this is a blocking capacitor. Yours essentially uses the chamber itself as a giant blocking capacitor - which means you have a LOT more stored energy. This is dangerous.

It will also wreck your signal. Now you're trying to get a small, fast signal out through a giant capacitor.

My original thought was that the biggest problem was that you'd have to cut so many corners that the chamber was unlikely to work. Now it's that you will hurt yourself or others. You should pick another project.

 

[Vanadium 50]

I'm going to suggest the following - draw up a list of all the parts you need: including screws and such, and drawings of how it goes together. It should be detailed enough for someone else to build. It should also include all the hazards and their mitigation. It should also include a "run plan" - how do you plan on operating it, and how you will know it's working.

I am concerned that you are going to mkae something dangerous.. This would convince people otherwise.

 

[Mark44]

Thread locked temporarily as being an unsafe activity, but possibly may remain locked.

 

[berkeman]

The electric signal problem you are talking about can easily be countered. I will just put a high negative voltage on the cathode, so the field lines remain the same. The wires will stay neutral until a current will flow through it. That small voltage is everything I need, and it can be amplified easily.

I think we're starting to cross the boundary of "unsafe".

We agree with V50. The thread will remain closed.

@BiemNL -- Please find a local Mentor that you can learn from and will supervise your projects like this. That is the only way to learn how to deal with high voltages and quality signal processing. Trying to do this on your own with only Internet forums as your guide is a very bad idea. Please be safe.