International education at National nuclear research university "MEPHI"
The method of the low-energy antiproton identification by stopping in the coordinate- sensitive...
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![Page 1: The method of the low-energy antiproton identification by stopping in the coordinate- sensitive PAMELA calorimeter 1 Svetlana Rodenko (MEPhI) Moscow International.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bffc1a28abf838cc1b02/html5/thumbnails/1.jpg)
The method of the low-energy antiproton identification by stopping in the coordinate-
sensitive PAMELA calorimeter
1
Svetlana Rodenko (MEPhI) Moscow
International conference on particle physics and astrophysics National Research Nuclear University MEPhI
5-10 October 2015
![Page 2: The method of the low-energy antiproton identification by stopping in the coordinate- sensitive PAMELA calorimeter 1 Svetlana Rodenko (MEPhI) Moscow International.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bffc1a28abf838cc1b02/html5/thumbnails/2.jpg)
2
An interaction between p and the calorimeter matter
By deflection in the magnetic field;
By searching for an annihilation in the calorimeter matter;
The identification of antiprotons:
![Page 3: The method of the low-energy antiproton identification by stopping in the coordinate- sensitive PAMELA calorimeter 1 Svetlana Rodenko (MEPhI) Moscow International.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bffc1a28abf838cc1b02/html5/thumbnails/3.jpg)
3
Electromagnetic calorimeter
The imaging calorimeter is used for separation of electrons and positrons from antiproton and proton.
![Page 4: The method of the low-energy antiproton identification by stopping in the coordinate- sensitive PAMELA calorimeter 1 Svetlana Rodenko (MEPhI) Moscow International.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bffc1a28abf838cc1b02/html5/thumbnails/4.jpg)
4
Simulation
Antiprotons: 0.75 GeV in the aperture of PAMELA.
Protons: 0.35 ‒ 0.95, 1, 1.1, 1.5, 2, 2.5, 3, 4, 5, 7.5, 10, 12.5, 15 GeV.
π-mesons: 0.75, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 4, 5 , 7.5, 10, 12.5, 15 GeV.
We want to identify an antiprotons on a background of protons and π-mesons.
![Page 5: The method of the low-energy antiproton identification by stopping in the coordinate- sensitive PAMELA calorimeter 1 Svetlana Rodenko (MEPhI) Moscow International.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bffc1a28abf838cc1b02/html5/thumbnails/5.jpg)
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The antiproton identification algorithm
Search for the point of entry of particle into the calorimeter and calculation
Search for the point of annihilation and calculation
Analysis of topology of annihilation (tracks of secondary particles)
![Page 6: The method of the low-energy antiproton identification by stopping in the coordinate- sensitive PAMELA calorimeter 1 Svetlana Rodenko (MEPhI) Moscow International.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bffc1a28abf838cc1b02/html5/thumbnails/6.jpg)
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Searching for the point of entry into the calorimeter
![Page 7: The method of the low-energy antiproton identification by stopping in the coordinate- sensitive PAMELA calorimeter 1 Svetlana Rodenko (MEPhI) Moscow International.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bffc1a28abf838cc1b02/html5/thumbnails/7.jpg)
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Searching for point of annihilation
Select the first few points with maximum energy release
Connect them with the point of entry
Calculate an energy release in cylinder around this direction ± 1 strip
Select cylinder with the maximum energy release
![Page 8: The method of the low-energy antiproton identification by stopping in the coordinate- sensitive PAMELA calorimeter 1 Svetlana Rodenko (MEPhI) Moscow International.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bffc1a28abf838cc1b02/html5/thumbnails/8.jpg)
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The energy release distribution
Energy release, mipEnergy release, mip
Energy release, mip Energy release, mip
Even
t
Even
tEven
t
Event
p (1 GeV)
p (2.5 GeV) p (5 GeV)
_p (0.75 GeV)
the point of entry the point of entry
the point of entry the point of entry
the point of annihilation
the point of annihilation
the point of annihilation
the point of annihilation
![Page 9: The method of the low-energy antiproton identification by stopping in the coordinate- sensitive PAMELA calorimeter 1 Svetlana Rodenko (MEPhI) Moscow International.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bffc1a28abf838cc1b02/html5/thumbnails/9.jpg)
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Energy release, mip
Energy release, mipEnergy release, mip
Energy release, mip
Event
Event
Event
Event
p (1 GeV)
p (2.5 GeV) p (5 GeV)
p (0.75 GeV)_
The total energy release distribution
![Page 10: The method of the low-energy antiproton identification by stopping in the coordinate- sensitive PAMELA calorimeter 1 Svetlana Rodenko (MEPhI) Moscow International.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bffc1a28abf838cc1b02/html5/thumbnails/10.jpg)
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Analysis of topology of annihilation (tracks of secondary particles)
Θ, deg
Sti
p n
on z
ero
energ
y r
ele
ase
,
mip
Θ 1 Θ 2 Θ 3 Θ4
Θ
![Page 11: The method of the low-energy antiproton identification by stopping in the coordinate- sensitive PAMELA calorimeter 1 Svetlana Rodenko (MEPhI) Moscow International.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bffc1a28abf838cc1b02/html5/thumbnails/11.jpg)
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Triggered strips dependence on angle Θ mean
Antiprotons (0,75GeV)
Protons (5 GeV)
Θ mean, deg
![Page 12: The method of the low-energy antiproton identification by stopping in the coordinate- sensitive PAMELA calorimeter 1 Svetlana Rodenko (MEPhI) Moscow International.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bffc1a28abf838cc1b02/html5/thumbnails/12.jpg)
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Example of selected antiproton from MC
![Page 13: The method of the low-energy antiproton identification by stopping in the coordinate- sensitive PAMELA calorimeter 1 Svetlana Rodenko (MEPhI) Moscow International.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bffc1a28abf838cc1b02/html5/thumbnails/13.jpg)
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Example of selected antiproton from MC
![Page 14: The method of the low-energy antiproton identification by stopping in the coordinate- sensitive PAMELA calorimeter 1 Svetlana Rodenko (MEPhI) Moscow International.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bffc1a28abf838cc1b02/html5/thumbnails/14.jpg)
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Example of selected proton from MC
![Page 15: The method of the low-energy antiproton identification by stopping in the coordinate- sensitive PAMELA calorimeter 1 Svetlana Rodenko (MEPhI) Moscow International.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bffc1a28abf838cc1b02/html5/thumbnails/15.jpg)
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The effectiveness of the selection and backgroundParticle Energy, GeV Selected Total amount
of eventsEfficiency /rejection
Antiprotons 0,75 2573 10 000 0,25
Protons
0,75 0 46 031 0
1 0 46 256 0
1,25 0 46 166 0
1,75 2 46 166 4,3e-5
2 9 46 119 1,9e-4
2,5 9 46 440 1,9e-4
3 29 46 223 6,3e-4
4 57 46 251 1,2e-3
5 77 46 048 1,7e-3
10 147 41 929 3,5e-3
15 174 41 825 4,2e-3
π-mesons:1 3 46 160 6,5e-5
1,25 7 41 825 1,7e-4
![Page 16: The method of the low-energy antiproton identification by stopping in the coordinate- sensitive PAMELA calorimeter 1 Svetlana Rodenko (MEPhI) Moscow International.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bffc1a28abf838cc1b02/html5/thumbnails/16.jpg)
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Conclusion
AC and TOF may be used for protons and high energy π-mesons rejection.
High energy protons have a speed close to 1 (β ~ 1), antiprotons are slow, therefore it is possible to build a velocity distribution measured by the TOF and cut off protons.
Apply a method to experimental data