Investigation of excited baryonic matter at the internal target of - - PowerPoint PPT Presentation

Investigation of excited baryonic matter

at the internal target of the Nuclotron

Robert POENARU Katarína MICHALIČKOVÁ

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Project members

• Robert Poenaru – 3rd year of

bachelor degree - Faculty of Physics, University of Bucharest (Romania)

• Katarína Michaličková – 1st of

master degree – Faculty of Science, Pavol Jozef Šafárik University in Košice (Slovakia)

Project supervisors

• Sergey V. Afanasev -

Researcher at JINR

• Dmitriy K. Dryablov –

Researcher at JINR

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Laboratory

• Our project was in the Laboratory of High Energy Physics

(Veksler And Baldin Laboratory Of High Energy Physics - VBLHEP) from the Joint Institute for Nuclear Research (JINR) located in Dubna, Russia.

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Project objective

• The purpose of this project is to search and study the baryonic

matter obtained in the d + A reactions, in our case we are interested in the formation of η-mesic nuclei.

• An η-mesic nuclei is a nuclear system which has the η-meson bound

by strong interaction with nucleons. The bound state can be considered as a meson moving in the mean field of the nucleons in the nucleus.

• η-meson was discovered in 1961 and is a meson made of a mixture
• f up, down and strange quarks and their antiquarks.

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Mass η: 547.862 0.018 MeV

η-mesic nuclei

• meson–nucleon interactions provides important information about

the nature of the strong forces. However, because of the short lifetime of most of mesons the investigations can be performed only by studying the final state interaction of the meson with a nucleon or a nucleus.

• η-mesic nuclei are very unstable formations, with the decay width

estimated around Γ ≈ 10-20 MeV

• So far no firm experimental confirmation of the existence of mesic

nuclei has been achieved.

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η-mesic nuclei formation

• Slow η-meson is produced, accompanied with flying forward

nucleons, when the beam (with an energy of ≈ 2GeV) interact with the nucleon.

• Reactions:
• d+A → η(A-1) + X → π + N + X’
• d+A → η(A-1) + X → N + N +X’

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Facility of the project

• The research of baryonic

matter(η-mesic nuclei) is taking place at the internal target of the Nuclotron.

• The Nuclotron is a basic JINR

facility aimed at obtaining multicharged ions (nuclei) with the energy up to 6 GeV per nucleon, proton beams as well as polarized deuteron beams.

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The internal target of the Nuclotron

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How do we search for η-nuclei?

• The present project is directed on creation of a three-arm hybrid

magnetic spectrometer SCAN3 for research of excited baryonic matter at the internal beam of the Nuclotron.

• The spectrometer is:
• intended for registration and analysis charged particles (π, K, p) and

neutral particles (n).

• designed for research of the pairs of the particles emitted from an

interaction point at an angle close to 180 degrees ( so-called wide angular pair correlations).

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The possibility of registering such pairs allows the study of a wide range of physical phenomena:

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FR, FL, BR, BL - scintillator monitor counters; P1,P2,P3, K1,K2K3, M1,M2,M3 - trigger time-of-flight scintillation detectors of P, K and M arms; Pch, Kch, Mch – threshold Cherenkov detectors for p-π identification; Magnet – magnet SP-46 with the 40cm magnetic track and field value up to 7-10kGs; Мс1, Мс2 – biplanar drift chamber for precise measurement of the coordinates; Мс3 – multiwire proportional chamber; M4 – scintillation detector for complete absorption of the M-arm; Р4 and K4 – 2 sets of 8 scintillation detectors, which are used for the registration and spectrometry

• f neutrons;

Р5, K5 и М5 – veto detectors for separation of fast particles.

Project tasks

The major tasks of this project were:

• Determination of the M1 scintillation detector dimensions (with the help
• f special simulations and ROOT)
• Create and test the M1 detector
• Create a simulation of the SCAN3 spectrometer using GEANT4

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Determination of the M1 scintillation detector dimensions

• We use M1 detector like a trigger in the time-of-flight method of

the M arm.

• We determine the size of the M1 detector with the help of

GEANT3 and ROOT, where we simulate the beam-target interaction, and from the obtained results we get the optimal size of scintillation detector.

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Position distribution of the M1 detector

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Position distribution of the M1 detector

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Position distribution of the M1 detector

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Momentum distribution of the M1 detector

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Momentum distribution of the M1 detector

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Momentum distribution of the M1 detector

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Determination of the M1 scintillation detector dimensions

• Conclusion:
• From these graphics we see that the optimal dimensions for the

Y and Z axis are 2 and 8 cm respectively.

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Creating and testing the M1 detector

• The M1 is made of 1 scintillator detector, 2 photomultipliers and

2 voltage dividers and the mounting tubes.

• The scintillation detector is made of polystyrene (C8H8(n)) with

paraterphenyl (PTP-1.5%) and POPOP(C24H16N2O2-0.05%).

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Creation process of the M1 detector

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Cutting machine for the Scintillation detector: PROXXON MP70 (Japan model)

1.Create isolation for the photomultiplier 2.Find the center of the scintillator 3.Fixing the scintillator in the mounting tube 4.Isolation for the entire detector with black paper

Photomultiplier

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• Diameter: 2cm
• 11 dinodes
• Rounded glass for better

time resolution

• Model: FEM 87

Detector M1

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Radioisotopes used in testing

• For testing and calibrating the M1 we used:
• Strontium-90 for scintillator (β source)
• Americium-241 (α source)

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Testing of the detector M1

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Signal amplitudes for both PM using Strontium source

Obtained results

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Testing of the first PM with the Am-241 source

Obtained results

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Testing of the second PM with the Am-241 source

Testing of the detector M1

• With the CAEN High Voltage source we apply a potential to both of

multipliers, so we can check the time resolution of the detector

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1800 V and 2100 V on the photomultipliers 1850 V and 2200 V on the photomultipliers

TR = 0.237 ns TR = 0.238 ns

2 1

Testing of the detector M1

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• For the detection of the η-mesic nuclei using the TOF method

we need a good time resolution and we looked for “almost” similar amplitudes of the signal for both the photomultipliers (image 2 in the previous slide).

• So we adjust the voltage until we find the best distributions. The

final voltage value for the photomultipliers were 1800 for the first

• ne and 2100 for the second one.

Simulation on GEANT4

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Conclusions

• We found the optimal dimension of the M1 detector
• We created the detector
• We found the time-resolution of the detector (0.238 ns)
• We began the simulation of the M arm using GEANT4

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• Thank you for your attention!!!

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Robert POENARU Katarína MICHALIČKOVÁ