1. NUCLEUS-NUCLEUS COLLISION Centrality Determination For NICA/MPD
ZDC RESOLUTION
A.M. SEHONE
Supervisor: A. Litvinenko
17 November 2018
Alfred Mogotsi Sehone

2. Outline. Introduction Multiplicity ZDC Conclusions 17 November 2018
Alfred Mogotsi Sehone

3. Nuclotron-based Ion Collider fAcility - NICA
Nuclei up to the gold
Energy up to 4 – 4.5 GeV/(N) (each beam)
17 November 2018
Alfred Mogotsi Sehone

4. Multi-Purpose Detector - MPD
Collision Region
Detectors: Inner Tracker (IT)
Barrel Tracker (BT)
End Cap Tracker (ECT)
Time of Flight (TOF)
Electromagnetic Calorimeter (ECAL)
Beam-Beam Counters (BBC)
Zero Degree Calorimeter (ZDC)
17 November 2018
Alfred Mogotsi Sehone

5. Why people study nucleus-nucleus collisions?
To describe particle formation with the application of statistical models.
Information about the phase diagram (QCD phase diagram)
Production of Hadrons that carry strange and charm quarks (exotic particles) with information about the QGP phase.
To give some information on the early evolution of the universe.
17 November 2018
Alfred Mogotsi Sehone

6. Can the impact parameter (b) measured?
b cannot be measured directly.
Experimental results are presented in windows of energy deposited in a zero-degree calorimeter, number of participants, multiplicity, etc. b
17 November 2018
Alfred Mogotsi Sehone

7. Centrality Classification:
Central collision --- b = 0
Small number of spectator particles
Large number of participant particles
Peripheral collision --- b ~ 2R (R = nuclei radii)
Large number of spectator particles
Small number of participant particles 2R
17 November 2018
Alfred Mogotsi Sehone

8. How centrality is measured in other experiments:
Multiplicity
Number of particles produced in a collision
Needs more time to reach equilibrium after the interaction.
Cannot get a reliable data in the hot QGP.
γ emission
17 November 2018
Alfred Mogotsi Sehone

9. ZDC
A Hadron calorimeter or a Zero Degree Calorimeter is a detector that detects and measures the energy of neutrons, protons and light nuclei emitted along the direction of the beam.
Event characterization and triggering purposes.
A compensated/corrected Iron-Modular scintillators - to obtain equal signals produced by hadronic and electromagnetic showers.
17 November 2018
Alfred Mogotsi Sehone

10. Results from the NA49 ( Pb+Pb Collision)
17 November 2018
Alfred Mogotsi Sehone

11. Layout of the ZDC ZDC > 20 Fe + 5 Sc Interaction length = 5
Fe (20mm)
Scintillator (5mm)
1 set
40 sets
Spectators
PMT
Light fibers
Beam
17 November 2018
Alfred Mogotsi Sehone

12. ZDC CENTRAL COLLISION PERIPHERAL 17 November 2018
Alfred Mogotsi Sehone

13. ZDC
Evaporated nucleons
Uniform
17 November 2018
Alfred Mogotsi Sehone

14. Energy distribution for nucleons of different energies
ZDC No.1
17 November 2018
Alfred Mogotsi Sehone

15. Monte-Carlo simulation results + Root package:
The kinetic, mean and dispersion energy of the detected particles were fitted in a linearity graph using a statistical model.
Determines whether the difference between the
observed and predicted values are significant.
17 November 2018
Alfred Mogotsi Sehone

16. ZDC Resolution and Linearity
pN = 3GeV/c
pN = 4GeV/c
pN = 5GeV/c
pN = 3GeV/c
pN = 4GeV/c
pN = 5GeV/c
17 November 2018
Alfred Mogotsi Sehone

17. Conclusions
The energy deposited by the spectator particles to the ZDC and the ZDC signal are linearly related.
The resolution of the ZDC can be used in a Monte-Carlo simulation to specify the impact parameter for centrality purposes and event triggering.
With the use of Root package and statistical models, a better fitting results for the resolution can be obtained.
17 November 2018
Alfred Mogotsi Sehone

18. THANK YOU FOR YOUR ATTENTION...
17 November 2018
Alfred Mogotsi Sehone

19. BACKUP SLIDES
17 November 2018
Alfred Mogotsi Sehone

20. Number of participants
Number of collisions
17 November 2018
Alfred Mogotsi Sehone

21. NA49 ZDC Only PHOBOS Paddle only PHENIX BBC & ZDC 17 November 2018
Alfred Mogotsi Sehone

22. 17 November 2018
Alfred Mogotsi Sehone

23. 17 November 2018
Alfred Mogotsi Sehone

24. Magnetic Field
17 November 2018
Alfred Mogotsi Sehone