mihai viteazul

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```							         CRESCERE

COSMIC RAYS IN A EUROPEAN
SCHOOL ENVIRONMENT: A
REMOTE EXPERIMENT
…
COLEGIUL NATIONAL “Mihai Viteazul”, Sf. Gheorghe, ROMANIA
THAT REACHED VARIOUS CORNERS
OF THE CONTINENT:

PORTUGAL, ITALY AND…
ROMANIA
In the following, we will
show you some pictures
from our country
MEASUREMENT OF COSMIC RAYS
FLOW
The team:
Aralda Chiriţă
Anda Panaitiu
Alin Iordache
Oana Muntean
Laurenţiu Gavrilă
Bogdan Ciambur
Anca Lăcătuşu
Bogdan Stîngă
Ştefan Grădinar
Cristian Buceceanu

coordinated by prof.
Luminiţa Curceanu…
…AND THE TEAM’S

COLEGIUL NATIONAL

“MIHAI VITEAZUL”
The cosmic rays are particles
coming from every corner of the
Universe, generating a shower of
many other particles that eventually
reach the Earth’s surface. The most
numerous of the latter are called
“muons” which have the same
electric charge as the electron but
are 210 times heavier.
The so-called shower forms due to
the very high energy of the initial
particle.
The aim of the experiment from LIP is the measurement of
the flow of cosmic rays at the earth’s surface. This is done
with the help of the Cosmic Rays Telescope (CRT), by
using the detectors it is composed of, which have the
following components:

• two detection modules, made of:

- a plastic scintillator block of the following
dimensions: 1 x 0,5 x 0,01
- a light guide
- a photomultiplier

• a data acquisition board installed into a PC
The cosmic rays flow is defined as expressed in the formula:

no.events
Flow 
t(1  dtf)  Eff  S

Eff = efficiency
S = scintillator surface
t = time
Dtf represents the time fraction in which the equipment does not
acquire data due to the fact that it is processing the data provided
by the last particle that hit the scintillator, Eff represents the
efficiency for the selected threshold and high voltage, and the
surface ( of the scintillator) is equal to 0.5 m2.
The equipment is handled through a LabView interface, via web.
At the beginning of the data acquisition, the school in
possession of the red code needs to select values for the number
of events that will be acquired, the threshold, the high voltage and
the Trigger Type button must be set to ‘Muon’.
Based on the acquired data and on the acquisition conditions, the
following must be performed:
• the measurement of the cosmic rays flow;
• the measurement of the energy deposited in the scintillator;
• the study of the flow-threshold dependence;
• the study of the signal amplitude - high voltage dependence.
(1) The measurement of the cosmic rays flow :

no.events
Flow 
t(1  dtf)  Eff  S

The error of the flow is expressed by the formula:

No.events
ΔΦ 
t  (1  dtf)  Eff  S
1. Between 10:54:47 - 11:06:10, with a total number of 500 events
throughout a time period of 683s, for the selected threshold of 80mV
and a high voltage of 1441 V, with dtf = 0.04 and Eff = 0.01

2. Between 11:21:11 - 11:53:59, with a total number of 1500 events
throughout a time period of 1968s, for a selected threshold of 80mV
and a high voltage of 1441 V, with dtf = 0.07 and Eff = 0.01

3. Between 11:57:26 - 12:20:18, with a total number of 1000 events
throughout a time period of 1372s, for a selected threshold of 60mV
and a high voltage of 1441 V, with dtf = 0.06 and Eff = 0.01
The value of the flow obtained from the data
in the first flow is:

F1 = 152.51342 ± 6.820607 ev./(s*m2)

The value of the flow obtained from the data
in the second file is:

F2 = 163.91293 ± 4.232213 ev./(s*m2)

The value of the flow obtained from the data
in the third file is:

F3 = 155.07723 ± 4.903972 ev./(s*m2)
The average value of the flow can be determined according to the formula:

N
Fi
 F2

 F  iN1     i
1
 F2
i 1    i

The error for the average flow can be determined according
to the formula:
1
  F 
N
1
 F2
i 1   i

•The average value of the flow is:
< F > = 158.681195 ± 2.899984 ev./s*m2
(2) The measurement of the energy deposited in the scintillator
The energy of a particle, corresponding to one event, is determined by
using the formula:

E  0,0077  Area(Ch 1 )  1,16 MeV
The average value of the energies corresponding to the events found in
one set of data is determined according to the formula:

1 N  E1i  E4i 
 E              
N i 1   2     
The average value of the energy deposited in the first scintillator can be
determined by using the formula:

1 N
 E  1    E1i
N i 1
• For the first file, the average value of the energy deposited in the first
scintillator is:

<E>1 = 2,645838 MeV = 4,2333 * 10-13 J;

• For the second file, the average value of the energy deposited in the first
scintillator is:

<E>1 = 3,020358 MeV = 4,8325 * 10-13 J;

• For the third file, the average value of the energy deposited in the first
scintillator is:

<E>1 = 2,8495571 MeV = 4,5592 * 10-13 J;
We can also introduce the variation of the energy:

2
1          E1i  E4i
N

V(E)                        E 
N  1 i 1      2            

Thus, the error of the average value of the energy can be determined as
follows:

V(E)
Δ  E 
N
The variation of the energy deposited in the first scintillator can be written as
follows:
N
  E   E  
1
V(E) 
2
1i
N -1         i 1
• For the first file, the variation of the energy is:
V(E) = 52.6303 MeV2 = 134.7335 * 10-26 J2;


• For the second file, the variation of the energy is:
V(E) =55.6536 MeV2 = 142.4732 * 10-26 J2;

• For the third file, the variation of the energy is:
V(E) =55.0641 MeV2 = 140.964 * 10-26 J2;
For the first file, the error of the average energy deposited in the first
scintillator is:
<E> = 0.3244 MeV = 0.519 * 10-13 J;

For the second file, the error of the average energy deposited in the first
scintillator is:

<E> = 0.1926 MeV = 0.3081 * 10-13 J;

For the third file, the error of the average energy deposited in the first
scintillator is:

<E> = 0.2346 MeV = 0.3753 * 10-13 J;
(3) The study of the flow-threshold dependence:
In order to perform this experiment, different values of
threshold (between 30mV and 80mV) need to be selected.
( 4 ) The study of the amplitude of the signals-high
voltage dependence
In order to realize this study, different high voltage
values need to be selected, by varying by 50 V, so that
the values are no higher than 1500 V and no lower than
1200 V. Also, in order to accomplish this, the threshold
value needs to be maintained the same.
When we deal with two sets of data that have identical acquisition
conditions – threshold and high voltage – the compatibility can be
determined. The latter is defined by the following formula:

Φ1  Φ 2
compatibil ity 
ΔΦ1  ΔΦ 2
2
2

where F1 and F2 represent the flows determined based on the two data sets,
and F1 and F2 are the corresponding errors.

If the determined value is between 1 and 3, the two data sets are
compatible.

The value obtained is 1.42015
Before concluding, we wish to express a few of
our thoughts and feelings in that which
concerns the CRESCERE project, in general,
and this experiment in particular. Thus, before
anything else, we would like to mention that
we are thankful for having been part of this
project and for having had the chance of
getting a closer view on the world of research.
We are very grateful for the opportunity we
have been given. This project has meant a lot
to us because we found out what research in
physics and in general means and what it
implies. We have worked in teams and learned
how to complete, to understand and help each
other, it has made us bond and understand
what team work is really all about.
Because this project has been a gateway to the
world, we also communicated with most of the
high schools in Romania and kept in touch.
Nothing would have been possible if the initiators
of the CRESCERE project wouldn’t have thought
that if young students are not implied in research
in physics during their studies in high school, they
cannot chose to study and involve themselves
later in this extremely interesting scientific area.
This is why we have to thank PEDRO ABREU, our
online teacher, who guided us throughout this
project and the entire team from Portugal. We are
thankful, and hope that this initiative will continue
and that its results will be noticed, even later on,
when the next generations of physicists, who took
part to these ambitious project, will continue to
discover what is still unknown our days.

```
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