BL4S COMPETITION - Experiment Proposal

2016BL4S COMPETITION
Experiment Proposal
Liceo Scientifico Galileo Ferraris
Turin - Italy
TEAM “I Taurinesi”
Edoardo Calvello
Claudia Concaro
Giacomo Giannuzzi
Berardo Iuliano
Fabio Luongo
Beatrice Motetti
Isabella Sofia
Elia Zamiri
BL4S COMPETITION - Experiment Proposal
TEAM “I Taurinesi”
- Abstract Technology is assuming a key role in our everyday life becoming more and more important
day by day. But is the environment in which we’re living nowadays so adapted to
technology’s functioning not to ever interfere with it? Cosmic rays arriving at our planet’s
surface every moment can interact with transistors, electrical circuit components present in
every electronic device that we use each day, sometimes causing errors defined as softerrors. Our experiment’s goal is to recreate a particle beam inside the accelerator and make
it hit an array of transistors (processor) positioned inside this accelerator. We will observe
the soft-errors analyzing the binary code using a software. After that we will make a
statistical analysis of the phenomenon in order to write down probabilistic hypothesis with
which we could one day theorize and elaborate a possible prevention measures.
- Why we want to go to CERN to conduct our
experiment There are many reasons why we want to go to CERN to conduct our experiment. The Italian
school system mostly focuses on theory and theoretical work, so first of all we would like to
concretely use our knowledge by realizing an experiment which is completely different from
all the experiences we could ever deal with at school and CERN puts the chance and the
instruments we need at our disposal. By going forward with this project we have grown so
fond of the possibility of concretizing what we have theorized that we cannot wait to come.
And of course, CERN is a symbol of scientific progress itself, and it would be a pleasure for
us to work in this magnificent factory of innovation and to be a part, even if a very small
one, of the “acceleration of science”.
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BL4S COMPETITION - Experiment Proposal
TEAM “I Taurinesi”
2016
- Transistors, soft errors and cosmic rays A. Cosmic rays
Every day the Earth is bombarded by rays of many particles that come from the deepest
corners of space, and that when colliding with the nuclei of atoms in our atmosphere give
birth to new particles such as pions, protons, muons, electrons. These arrive at the Earth’s
surface and can sometimes interfere with the correct functioning of electronic devices or of
their components, such as transistors.
B. Transistors
In order to understand our experiment,
Personal photograph
Taken on 26.1.2016
it's necessary to know how a transistor
works. Because they accomplish a wide
variety of tasks, there are different types
of them. As an example we've taken in
consideration a BJT (bipolar junction
transistor) because its functioning is
roughly similar to the one of others.
Figure 1: Different types of transistors
BJTs consist of three semiconductors, two of which are the same: the different density of
electrons between the two zones in contact lets these particles diffuse until the electrostatic
force stops them at the junction; at that point the electrons act as a barrier against any
electric current. The possibility of the passage of an electric current can be restored by
applying an electric potential difference to the middle zone in the transistor, so that the
electrostatic force is weakened and so is the electron barrier.
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BL4S COMPETITION - Experiment Proposal
TEAM “I Taurinesi”
C. Soft errors
Personal schematic representation
Made with the software “Blender” on
29.2.2016
Proton
Gate
Boron atom
Phosphorus atom
Figure 2: Proton hitting the gate of a transistor
Sometimes transistors may lose their original functionality and produce errors in the
processes they are involved in. This strange behavior could be the result of several
phenomena: as said before, one of the most important among these is the collision
between a nucleus of a semiconductor material and a cosmic ray. Positively charged
particles are able to cause soft errors: when they hit the gate this absorbs the charges,
permitting other electrons to pass from the source to the drain because of the electrostatic
attractive force overcoming the repulsive one.
We believe that we can obtain the same effect if the proton collides with the atom. The
reason is that the proton would transfer enough kinetic energy to “knock away” an electron
liberating it from the nucleus’ orbit, thus altering both the electric potential difference and
the correct functioning of the transistor.
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BL4S COMPETITION - Experiment Proposal
TEAM “I Taurinesi”
2016
Personal schematic representation
Made with the software “Blender” on
29.2.2016
Electron
Boron atom
Proton
Phosphorus atom
Figure 3: Proton colliding with an atom thus releasing an electron
- Explanation of our experiment When hitting the target the primary beam will give way to a new secondary one consisting
in a myriad of different particles.
Our first task is to isolate all the heavy positively charged particles. We will do this by using
bending magnets and selecting particles that have a high energy. A collimator will
significantly reduce the number of different particles. We can then use the Cherenkov
detectors already built in the T9 Beam Line to reveal the identity of these particles and to
furthermore select high energy positively charged particles such as pions, kaons and most
importantly protons.
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BL4S COMPETITION - Experiment Proposal
TEAM “I Taurinesi”
When entering the experimental area the beam will almost entirely be made up of these
particles, we will significantly reduce the diameter of the beam by focusing it with a
quadrupole magnet. We will then place a collimator in order to reduce the density of the
beam by only selecting particles of a certain momentum thus stopping other particles. This
gives us the chance to analyze more accurately the effect that each single particle has on
the transistor’s correct functioning.
We will place two scintillators and two DWC tracking devices to obtain the correct number,
position and trajectory of the particles in the beam. Knowing that some particles that may
remain in the beam such as pions and kaons could decay in muons we will then place a
muon filter to avoid any interferences with our experiment.
Then there will be the processor. We will place a computer with a simple setup, the
processor of which will be the main target for the beam. It will have the job of running a
simple program that will cyclically execute a series of operations of which the expected
result is known, thus involving the different elaboration sites in the processor, and of which
the experimental results are saved on a permanent storage device. By starting the program
before the irradiation and by maintaining it in function during the process, we can observe if
any error occurs. We will then conduct a statistical analysis of the errors in order to identify
the elaboration sites that are most affected. We also want to determine the frequency with
which errors occur and study the properties of this phenomenon so that in the future we
could even look into prevention methods.
Because we predict that in some instances the proton will collide with the atom instead of
with the gate, we want to monitor the particles which could be “knocked away” because of
the transfer of energy between the proton and the atom. In order to do this we will place
two scintillators and two DWC tracking devices to check if any particle passes through;
finally we will place a Cherenkov detector to identify the identity of the incoming particle
(we predict it will be an electron).
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BL4S COMPETITION - Experiment Proposal
TEAM “I Taurinesi”
Personal schematic representation
Made on 18.3.2016
Figure 4: A schematic representation of the T9 Beam Line and of our planned Experimental Area
- Acknowledgements We would like to thank our beloved and great mathematics and physics teacher Tiziana La
Torella for having presented this great opportunity to us, for having supported and incited
us every moment and of course for having taught all of us the fundamental principles of
physics and for having transmitted to us the love for thus extraordinary subject.
We also would like to thank Giovanni Organtini, researcher at the Italian National Institute
of Nuclear Physics (INFN) for having given us some valuable information and help in
understanding the functioning of the beam line.
Finally we want to thank our principal Stefania Barsottini for having supported us and for
having given us the possibility to film inside the school.
It wouldn't have been possible without you!
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2016