Charged Particle Pseudorapidity Distributions Measured with the STAR EPD
Abstract
:1. Introduction
1.1. The EPD
2. Methodology
2.1. Charged Particle Pseudorapidity Measurement with the EPD
2.2. From Raw EPD Data to Pseudorapidity Distribution []
2.3. Extracting Charged Particle Pseudorapidity Distribution
- Bin-by-bin correction of the already unfolded using the charged particle fraction from MC data;
- Bin-by-bin correction of the raw EPD data via from MC data; then unfolding of the EPD charged particle distribution.7
- Mark neutral particles as background and fill the response matrix as in the second method, except that the hits from neutral primaries are considered as “fake”.
2.4. Consistency Check of the Unfolding Methods
3. Systematic Checks
3.1. Dependence on Input MC Distribution
3.1.1. Tightening and Shifting the Input MC
3.1.2. Broadening the Input MC
3.2. Changing the Charged Fraction in the MC Training Dataset
3.3. Changing the Slope of the MC Training Dataset
3.4. Centrality and z-Vertex Selection
3.5. z-Vertex Choice
3.6. Unfolding Method Choice
3.7. EPD Related Uncertainties
4. Results
Comparison with the PHOBOS Results
5. Discussion
Funding
Institutional Review Board Statement
Informed Consent Statement
Acknowledgments
Conflicts of Interest
Abbreviations
QGP | quark–gluon plasma |
RHIC | Relativistic Heavy-Ion Collider |
STAR | Solenoidal Tracker |
EPD | Event Plane Detector |
BES | Beam Energy Scan |
MIP | minimum ionizing particle |
ADC | analog-to-digital converter |
MC | Monte Carlo (simulation) |
QCD | quantum chromodynamics |
1 | The EPD is more sensitive to charged particles, as detailed subsequently. |
2 | The rings are numbered from 1 to 32 in the following manner: the innermost East EPD ring is the #1 which follows outward until #16; then, the #17 continues on the West EPD side’s outermost ring until #32 being the innermost one. |
3 | In the ultrarelativistic limit, it approaches to rapidity (in unit system, c being the speed of light): , with E being the energy of the particle. |
4 | Fill(, ); naturally, “measured” and “truth” here stand for the training datasets obtained from MC (simulation). |
5 | Miss() and Fake(). |
6 | Caused by both primary and secondary particles. |
7 | In this case, another type of response matrix has to be used that was filled only with the charged particles’ data. |
8 | Note that the mentioned unfolding procedure was at this stage still done on the MC EPD ring distribution and thus on the training sample. |
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Source | Systematic Uncertainty |
---|---|
MC input tightening, shifting | 6% |
MC input broadening | 4% |
Charged fraction in MC | 6% |
slope change in MC | 1% |
Centrality selection | 2% |
z-vertex selection | negligible |
z-vertex choice | 1% |
Unfolding method choice | 8% |
EPD related uncertainties, electronics, efficiency | negligible |
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Molnár, M., for the STAR Collaboration. Charged Particle Pseudorapidity Distributions Measured with the STAR EPD. Universe 2023, 9, 335. https://doi.org/10.3390/universe9070335
Molnár M for the STAR Collaboration. Charged Particle Pseudorapidity Distributions Measured with the STAR EPD. Universe. 2023; 9(7):335. https://doi.org/10.3390/universe9070335
Chicago/Turabian StyleMolnár, Mátyás for the STAR Collaboration. 2023. "Charged Particle Pseudorapidity Distributions Measured with the STAR EPD" Universe 9, no. 7: 335. https://doi.org/10.3390/universe9070335