|Petr Parfenov 5c769ad61e Latest version of P. Batyuk's code||1 year ago|
|analysis_of_output_tree||1 year ago|
|analysis_task||1 year ago|
|draw_output||1 year ago|
|identity_analysis||1 year ago|
|README.md||1 year ago|
|utils.C||1 year ago|
Precise determination of the moments of multiplicity distributions of identified particles could be challenging due to the misidentification in detectors. The so-called Identity Method [1-3] allows one to solve this problem. Using the code placed in this folder, performance of the Identity Method was tested on the A–A events simulated in the conditions of the MPD experiment at NICA (using TPC dE/dx vs mometum histograms). Namely, moments within a single kinematic window as well as coefficients of forward-backward pseudorapidity correlations are extracted.
 M. Gazdzicki et al., Phys.Rev. C 83, 054907 (2011)
 M. Gorenstein, Phys.Rev. C 84, 024902 (2011)
 A. Rustamov, M. Gorenstein, Phys.Rev. C 86, 044906 (2012)
The analysis consists of several steps. Note that at each step one needs to properly set paths, filenames, and other parameters inside the scripts.
As the first step, trees with event- and track-level information are extracted from the DST root-files (that contain MC and reconstructed data)
using the task
get_tree_MPD_task.cc from the folder
For that, DST files from a chosen directory (e.g. on NICA cluster) are merged into a chain (file names are taken from
Execution of the analysis can be started using the
Obtained trees can be then processed using a script
get_info_and_identity_tree.cxx in the
The script does several things:
1) it extracts a special tree with tracks for Identity Method (called "treeIM") - to be used below,
2) it also performs calculations for Forward-Backward correlations analysis at SIM, REC_PRIMARY and REC_ALL levels,
3) a lot of supplementary information is extracted as well.
After that, the script
get_dEdx_vs_mom_and_true_pi_K_p_moments_from_tree.C runs over obtained
an_results.root file in order to:
1) extract the dEdx vs pTPC distributions and put them in
file_dEdx_in_bins.root (IMPORTANT: this is done with utilizing the PID info from simulations! With real data, this is not possible to do, and sophisticated fits of dE/dx distributions in narrow momentum slices will be required.)
2) calculate the true (i.e. primary-particle level) moments (first, second, cross-moments) and put them in
In the identity_analysis folder, the script
fit_dEdx_pt_slices.C takes the
file_dEdx_in_bins.root file and fit narrow momentum slices for each particle species with a function (i.e. Gaus).
The results for all slices are then stored into
Now everything is ready to run the analysis of the moments with the Identity Method itself. The main script is
analyse_identity_dEdx.C, which requires the
as well as the root-file
an_results.root with the identity tree "treeIM" (which has a structure shown in the cartoon
This code is based on the Identity module created by A. Rustamov and M. Arslandok, NIM A 946 (2019) 162622, https://arxiv.org/abs/1807.06370, and also a more advanced script provided by A.Rustamov.
In order to load necessary libraries from the identity_analysis/src directory, the analysis should be started via the
The main output is a
Finally, truth moments from
file_truth_moments_IM.root can be compared with those reconstructed with the Identity Method (
file_extracted_moments_IM.root) by running a script
draw_comparison_truth_IM.C in the
A set of results obtained with this code can be found in Altsybeev, Petrov, J. Phys.: Conf. Ser. 1690 012124 (2020), https://arxiv.org/abs/2010.08742.