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Hey !
Today I feel like writing about some of the experiences I made with my job as a junior physicist and how I contributed to the AMS particle detector, which will (after completion) be operated from the ISS space station.
It was an awesome opportunity to use modern technology and the really interesting physical background might even appeal to some of you.
The basic construction scheme of AMS can be seen on the bottom left of this website, which also holds some other information and many links to talks, etc. :
http://www1b.physik.rwth-aachen.de/~schael/AMS.html
AMS is being developed by about 500 physicists from 56 institutes and 16 countries. It is a multi million dollar project and will hopefully begin it's flight to the ISS in 2010. (There are some problems with the NASA, because the they canceled the flight but the last word has not been spoken there. The problem is that NASA wants to limit the remaining flights of the space shuttle because of the heat issue)
Ok, I'll start with some background information.
I am 22 years old and live in Aachen / germany, close to the belgian/dutch border. I study physics at the RWTH (which as an university is mostly covering engineering and natural sciences). I will start my 5th semester now and since the beginning of the 3rd semester I have been working for the "1. Physikalisches Institut B" (physical institute 1B) of our physics department on a 10 hours per week basis.
This position was a great chance for me to gather experience regarding the job as a physicst and to learn lots of new stuff about particle detectors, programming and scientific work in general. Also working in a team was great fun for me so far.
The AMS experiment is basically meant to count elementary particles in space. For example, some of the particles of interest are protons, electrons and positrons (the anti matter counterpart to the electron). This has to be done because currently only very little is known about the behavior of dark matter and anti matter. Also, there are some mysteries concerning the production of anti matter because the usual decay processes cannot be responsible for the production of all the anti matter in the universe. This is the place where dark matter enters as a possible production source.
There are theories involving new elementary particles in order to solve some of those riddles, and in order to test these theories a particle detector in space is needed.
Particles will fly through the detector and pass through the different elements of the detector.
For example the magnet is used in order to make the paths of particles bend so that particles with different charge can be separated by the curvature of their path in the tracker. This allows to separate electrons (negative charge) from protons/positrons (positive charge).
However it is also needed to separate protons and positrons because ideally you'd want to identify particles uniquely and measure their energy (or their velocity) with which they travel through the detector. Therefore additional means are needed.
One of these means is the transition radiation detector (TRD). I won't go into detail but the TRD basically uses a number of fleece layers through which the particle has to pass. If the particle is an electron / positron radiation will be produced and can be detected. Protons usually don't deposit any energy in the detection chambers. This way protons and positrons can be separated. (This detector unit is not enough though because the rejection of misidentified particles is not big enough, a separate and independent test is needed.)
My first assignments consisted of programming simulation routines and programs for the TRD. We compared monte carlo simulations with actual data taken in the "test beam run" at CERN (european research center in Geneve Switzerland) in 2000 and tried to find out how different construction and analysis parameters behaved. The main goal was to find out how well the seperation between protons and positrons was working out and how far it could be pushed.
After those things were finished I worked on the light transportation cables for another part of the detector (the ACC).
I found it somehow cool that my DNA on the cables will (hopefully) go into space :D
I worked on many other things and it was a really great time overall.
If you want to read more, please have a closer look at the website I posted. I also might come back and write some more if there is interest.
Your
Bastian
 
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oh, this is more or less hard to understand to me, but it looks like fun and i will make a effort to read it more carefully 
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it is hard to understand... nonetheless I want to read more about what you do! Keep posting please.
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Yeah I noticed that I wrote way to much about the physics and not enough about my own involvement 
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Have a look at these pictures:
http://www1b.physik.rwth-aachen.de/~schael/AMS ACC Photos.html
In the bottom right you can see the panels we built. The green fibres produce light once a particle runs through them and this light will be transported through light transportation cables which I also helped to build.
Afterwards the light will be detected by detectors at the other end of those cables.
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sounds fun, is it common for students to work with a project like you do? I have probably studied very similar subjects in Sweden, however I have never heard of a student working in a team like you do. The only thing we do is help teach the younger students math (if you are decent and want to).
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more physics info please!
I like the information about the various theories/techniques
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Physician
United States4146 Posts
I guess detecting neutrinos is out the question.
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That's cool. But I have a question, how hard was it to get involved/do they do these frequently?
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On September 04 2007 06:40 Physician wrote:
I guess detecting neutrinos is out the question.
Read this (atleast look at the picture!) http://strangepaths.com/the-sun-seen-through-the-earth-in-neutrino-light/2007/01/06/en/
To get an idea of how hard it is to detect them. Neutrinos are created in every reaction chain where H go to He through fusion processes. There is a tremendous amount of reactions in the suns core every second. Yet the resolution over 503 days from the sun isnt high. Very few neutrinos detected.
There was a famous supernovae 1987. About 30! neutrinos were detected..
Unless science has evolved very rapidly the last few months its impossible to build a space ship large enough to carry the required detectors. I think there would be a lot of noise due to bad shielding from other particles in space too.
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Nice write-up!
I always have fun talking to people who I know who are on these big collaborative experiments (Brown has a couple of profs working at D0 at Fermilab and also one prof doing dark matter searches with a collaboration in Italy). It's not my cup of tea (I like having more control over my experiment) but the hardware, planning and logistics involved in any of these high-energy/particle type projects astound me.
But yeah, small science/big science is always a fun comparison to make.
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Physician
United States4146 Posts
On September 04 2007 08:48 Jim wrote:Show nested quote +On September 04 2007 06:40 Physician wrote:
I guess detecting neutrinos is out the question. Read this (at least look at the picture!) http://strangepaths.com/the-sun-seen-through-the-earth-in-neutrino-light/2007/01/06/en/To get an idea of how hard it is to detect them. Neutrinos are created in every reaction chain where H go to He through fusion processes. There is a tremendous amount of reactions in the suns core every second. Yet the resolution over 503 days from the sun isnt high. Very few neutrinos detected. There was a famous supernovae 1987. About 30! neutrinos were detected.. Unless science has evolved very rapidly the last few months its impossible to build a space ship large enough to carry the required detectors. I think there would be a lot of noise due to bad shielding from other particles in space too. and thus my pun.. I was prodding for fun, as in i.e the nerd in me made a joke; nice link though, thanks
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I feel very stupid after reading that.
Whatever it is that you do, its sure impressive.
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very interesting, I had to read it a few times over (lol).
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Thanks for the replies so far.
Regarding the neutrino question:
Have you heard about the icecube experiment? The prof who gave basic physics lectures in my first 3 semesters is working for this experiment. I have read an article in a science magazine but I'm not an expert on this experiment. But here's a link :
http://icecube.wisc.edu/
About my position:
Yes it is rather uncommon for students to work for these kinda projects this early.
I had a lecture on data analysis given by this prof and afterwards he came to me and told me that I had big potential. He then went on to tell me that they are always trying to support gifted students and offer them positions working in modern experiments (although I know of only 2 people doing it currently).
I'm still very young and haven't even had any lectures on elementary particles / cosmology or anything like that. So most of the info I can give is what I learned at work and by reading. I am by far the youngest person in our institute.
The entire thing is more meant like a learning experience for me rather than producing results for them (which I obviosly do to some extent, but I can't match the big guns here since I still make beginner mistakes etc.).
To Clutch3:
I'm actually doing a lot of work for the "PEBS" experiment, too.
It is a very small experiment at the moment and has a lot in common with AMS. So I kinda see what you mean. It will get rid of the necessity to go into space and thus be very much cheaper. It is still in heavy design phase and none of it has been built yet. There are only 2 universities working for it (Aachen and Pisa / Italy).
Also I have a lot of colleagues working for the CMS detector at the LHC in geneve. That project is like so ridicolously big that I often feel it doesn't really benefit anymore.
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On September 04 2007 15:25 ToT)SiLeNcE( wrote:
To Clutch3:
I'm actually doing a lot of work for the "PEBS" experiment, too.
It is a very small experiment at the moment and has a lot in common with AMS. So I kinda see what you mean. It will get rid of the necessity to go into space and thus be very much cheaper. It is still in heavy design phase and none of it has been built yet. There are only 2 universities working for it (Aachen and Pisa / Italy).
Also I have a lot of colleagues working for the CMS detector at the LHC in geneve. That project is like so ridicolously big that I often feel it doesn't really benefit anymore.
Yeah, working on the LHC or Fermilab large experiments (CDF, D0) is almost like being in the army. You're given very specific, set tasks and that's what you work on. It's an amazing thing that we are even able to do the things that those groups regard as the norm, but at the same time you don't have almost any control over the experiment. Plus, there's so many things predicted by the Standard Model that are out of our ability to test.
I will try to look up a little bit about the PEBS experiment. One of the experiments at Brown (the one some of my buddies are on) is written up here, in non-technical terms:
Dark Matters
And, by contrast, the experiments I do are generally 1-3 person affairs, and the total time to set-up the equipment to make the samples is about 6 months, while the time to set up a new variety of experiment ranges from 2 weeks to 2 months. So it's definitely "small science" in that sense. If you are interested, some of the stuff I've done lately is available here (all papers with Schrag as the first author give you an idea of my main research focus, the others are projects led by other people in the group I worked in at Brown or at the company I work for now):
Micro Magnetics publications page
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EPT
