1. Simulation study of effects induced by final granularity of detector in particle flow deduced from experimental data in relativistic heavy ion collisions
Master student:
Scientific supervisor :
Scientific adviser :
Prozorov Alexandr, TPU, Russia, Tomsk
Andrej Kugler , RNDr. CSc., head of department OJS, ÚJF AV ČR, Řež
Ondřej Svoboda, Ing. Ph.D., ÚJF AV ČR, Řež
Goryunov A.G., Dr. of tech. sciences, head of department EAFU , TPU
24th of May 2017

2. Goals
1 Create a particle detection model to investigate dependence between particle flow and detector cells the with different sizes
2 Justify that method of correction of experimental data from reaction Au+Au at 1.23 A GeV measured by the HADES spectrometer proposed by HADES group works correctly
Tasks
Read IQMD generator input data
Create a model of registration for different cell size
Study of efficiency of registration and effects
Create a correction matrix that takes into account
unregistered particles
Compare corrected model data to original data
* -
Alexandr Prozorov 2

3. Experiment HADES Description of spectrometer and tracking system
RPC
Description of spectrometer and tracking system
Alexandr Prozorov 3

4. Collision characteristics
Definition of centrality for Glauber model b
Alexandr Prozorov 4

5. Study of particles Directed flow Rapidity characterizes
longitudinal momentum of particle
Alexandr Prozorov 5

6. Experimental data v1 θ[°] φ[°] y Preliminary Preliminary
All particles distribution
θ[°] v1 y
φ[°]
Pavel Tlusty, private communication,
Alexandr Prozorov 6

7. Screenshot of one of IQMD files
Structure of iQMD file
Number of event
Number of particles
Energy per nucleon
Impact parameter
Overall events
Energy of particles px py pz
Particle id
Screenshot of one of IQMD files
Alexandr Prozorov 7

8. Code algorithm in ROOT 5.34 Read the header for one event (collision)
Calculate and remember angles of particles in one event
Cycle through cells ( -180 ≤ φ < 180 и 0 ≤ θ < 180). If a cell contains more than one particle only one of particles is selected and put into the "tree".
Next event or file
After all events the directed flow is calculated for different types, centralities and rapiditiy ranges using particles contained in the "tree“ file.
Alexandr Prozorov 8

9. Simulation results
V1 for v1 y
Alexandr Prozorov 9

10. Comparison v1 v1 y y Experiment (preliminary) IQMD original data v1
Pavel Tlusty,
(Private Communication)
Alexandr Prozorov 10

11. Comparison v1 v1 y y Experiment (preliminary)
Model for cellsize 6°x 6° v1 v1 v1 y y
Pavel Tlusty,
(Private Communication)
Alexandr Prozorov 11

12. Proton flow v1 v1 y y Experiment (preliminary)
Model for cellsize 6°x 6° v1 v1 y y
Pavel Tlusty,
(Private Communication)
Alexandr Prozorov 12

13. Proposed method
Express efficiency of registration as a linear function of the mean multiplicity of particles
Construct a correction matrix in the azimuthal and polar angles
Record the histogram information about the flow taking into account the correction matrix.
Select the parameter k such that the directed flows are symmetric and pass through the zero point
ε=1−𝑘∗〈 𝑚𝑢𝑙𝑡 〉
Alexandr Prozorov 13

14. Multiplicities θ[°] θ[°] φ[°] φ[°] Multiplicity of all particles
Multiplicity for 6x6 degrees model
Multiplicity – average number of particles that hit a cell during one event
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15. Efficiency of registration
θ[°]
θ[°]
φ[°]
φ[°]
Efficiency of registration is a number between 0 and 1 showing which part of all particles was registered.
It is a ratio between multiplicity for registered and for all particles
Alexandr Prozorov 15

16. Efficiency vs Multiplicity
k=0.44
ε=1−𝑘∗〈 𝑚𝑢𝑙𝑡 〉
Alexandr Prozorov 16

17. Different slopes v1 y
Flow dependence on different efficiency of registration
Alexandr Prozorov 17

18. Experimental way for finding k
V1 x 103
(y=0)
k=0.38 k
v1 (y > -0.1 & y < 0.1) for different coefficient k
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19. Chi-square minimum Data points Model expectation Uncertainty k
dependence on k
N=10 points
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20. Corrected flows v1 v1 y y Experimental way for v1=0 at midrapidity
Chi square minimum
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21. Comparison for Efficiency
θ[°]
θ[°]
φ[°]
φ[°]
Constructed efficiency of registration for k=0.42
True efficiency of registration
Alexandr Prozorov 21

22. Results and conclusions
A particle detection model similar to the experiment was made
The dependence of efficiency of registration on the size of cells
is investigated
Proposed method of correction* is justified
* - Pavel Tlusty, private communication,
Alexandr Prozorov 22

23. Thank you for attention
Alexandr Prozorov 23