scholarly journals Application of the missing mass method in the fixed-target program of the STAR experiment

2021 ◽  
Vol 251 ◽  
pp. 04029
Author(s):  
Yuri Fisyak ◽  
Victor Ivanov ◽  
Hongwei Ke ◽  
Ivan Kisel ◽  
Pavel Kisel ◽  
...  
Keyword(s):  
Beam Energy ◽  
Fixed Target ◽  
Missing Mass ◽  
Production Chain ◽  
Event Selection ◽  
Online Mode ◽  
Event Reconstruction ◽  
Target Program ◽  
Star Experiment ◽  
Real Time Application

The search for short-lived particles is usually the final stage in the chain of event reconstruction and precedes event selection when operating in online mode or physics analysis when operating in offline mode. Most often such short-lived particles are neutral and their search and reconstruction is carried out using their daughter charged particles resulting from their decay. The use of the missing mass method makes it possible to find and analyze also decays of charged short-lived particles, when one of the daughter particles is neutral and is not registered in the detector system. One of the most known examples of such decays is the decay Σ− → nπ−. In this paper, we discuss in detail the missing mass method, which was implemented as part of the KF Particle Finder package for the search and analysis of short-lived particles, and describe the use of the method in the STAR experiment (BNL, USA). The method was used to search for pion (π± → μ±ν) and kaon (K± → μ±ν and K± → π±π0) decays online on the HLT farm in the express production chain. An important feature of the express production chain in the STAR experiment is that it allows one to start calibration, production, and analysis of the data immediately after receiving them. Here, the particular features and results of the real-time application of the method within the express processing of data obtained in the BES-II program at a beam energy of 3.85 GeV/n when working with a fixed target are presented and discussed.

scholarly journals Highlights from the STAR experiment

2019 ◽  
Vol 204 ◽  
pp. 01018
Author(s):  
Alexey Aparin
Keyword(s):  
Beam Energy ◽  
Star Collaboration ◽  
Fixed Target ◽  
Directed Flow ◽  
Decay Modes ◽  
Charm Quarks ◽  
Star Experiment ◽  
The One ◽  
Beam Energy Scan ◽  
Program Show

We present an overview of the recent results obtained by the STAR Collaboration at RHIC.We report the beam energy dependence of directed flow of strange particles. These results support the assumption, that directed flow is formed before hadronization and observed particles are formed via coalescence of constituent quarks. First evidence of a non-zero directed flow of D0 meson is reported. We present the precision measurement of elliptic flow of D0 meson and the first measurement of Λc baryon in Au+Au collisions at $\rad{}{s_{NN} } = 200\,{\rm{GeV}}$, which suggests thermalization of charm quarks. We report results of global Λ polarization measurements in Au+Au collisions, together with the investigation of polarization dependence of centrality and transverse momentum pT. Results from the STAR fixed-target program show good agreement with previously obtained results. A precise measurement of the $_{{\rm{\Lambda }}}^{3} H$ lifetime is presented. Mesonic decay modes are used to reconstruct the $_{{\rm{\Lambda }}}^{3} H$ from Au+Au collisions. The measured lifetime is about 50% shorter than the one of a free Λ, indicating a strong hyperon-nucleon interaction in the hypernucleus system. Finally, we give an outlook to detector upgrades for the Beam Energy Scan phase II.

scholarly journals Event reconstruction in the BM@N experiment

2019 ◽  
Vol 204 ◽  
pp. 07012 ◽  
Author(s):  
P. Batyuk ◽  
D. Baranov ◽  
S. Merts ◽  
O. Rogachevsky
Keyword(s):  
Experimental Data ◽  
Recent Progress ◽  
Detector Response ◽  
Fixed Target ◽  
Fully Integrated ◽  
Alignment Procedure ◽  
Automatic Mode ◽  
Event Reconstruction ◽  
Target Program ◽  
Experimental Runs

In the paper, the main accent is put on development of software to be used in the BM@N experiment. The experiment is considered as a first step towards a realization of fixed target program at the NICA complex. A brief description of software used for reconstruction of track parameters in the inner tracker of the experiment is presented. The alignment procedure in automatic mode was made using the Millepede package fully integrated in the software. The obtained results illustrate a quality assurance of alignment performed using existing experimental data from experimental runs and recent results, including methodological ones from a tracking procedure, which were used for event reconstruction in the inner tracker. The importance of a precise geometry description and a realistic detector response via micro-simulations done for the GEM part of the inner tracker used for processing experimental data is emphasized. Our recent progress in this activity is discussed.

scholarly journals MWPC Prototyping and Testing for STAR Inner TPC Upgrade

2018 ◽  
Vol 46 ◽  
pp. 1860079
Author(s):  
Shuai Wang
Keyword(s):  
Beam Energy ◽  
Qcd Phase Transition ◽  
Proportional Chamber ◽  
Physics Program ◽  
Momentum Resolution ◽  
Multiwire Proportional Chamber ◽  
Star Experiment ◽  
Transition Study ◽  
Time Projection ◽  
Beam Energy Scan

The STAR experiment at RHIC is upgrading the inner sectors of the Time Projection Chamber (iTPC) to increase the segmentation on the inner padplane from 13 to 40 rows and to replace the inner sector multiwire proportional chamber (MWPC). The upgrade will provide better momentum resolution, better dE/dx resolution, and most importantly it will provide improved acceptance at high rapidity to [Formula: see text]1.5 compared to the current TPC coverage of [Formula: see text]1.0. The enhanced TPC capabilities based on this upgrade are critical to the physics program of the Beam Energy Scan Phase II at RHIC during 2019-2020, in particular the QCD phase transition study. In this proceedings, the iTPC MWPC module fabrication and prototype testing results are discussed.

scholarly journals The PADME Detector

2018 ◽  
Vol 170 ◽  
pp. 01007 ◽  
Author(s):  
Paola Gianotti
Keyword(s):  
Beam Energy ◽  
Positron Beam ◽  
Precise Determination ◽  
Final State ◽  
Missing Mass ◽  
Dark Photon ◽  
Key Points ◽  
Background Events

The PADME experiment, by using the positron beam of the Frascati laboratory, aims at searching for signals of a dark photon, A′ . It will evaluate the final state missing mass of the process e+ e- → A′ γ by knowing the beam energy and measuring the four-momentum of the ordinary recoil photon. The precise determination of this quantity, and the capability to reject background events, are the key points for the success of the experiment. In this paper a description of each component of the PADME detector is given.

scholarly journals Fixed target experiments at the Fermilab Tevatron

2014 ◽  
Vol 29 (28) ◽  
pp. 1446008 ◽  
Author(s):  
Gaston Gutierrez ◽  
Marco A. Reyes
Keyword(s):  
Center Of Mass ◽  
Partial Wave Analysis ◽  
Fixed Target ◽  
Liquid Hydrogen Target ◽  
Hydrogen Target ◽  
Fixed Target Experiments ◽  
Center Of Mass Energy ◽  
Diffractive Production ◽  
Target Program ◽  
Central Production

This paper presents a review of the study of Exclusive Central Production at a center-of-mass energy of [Formula: see text] at the Fermilab Fixed Target program. In all reactions reviewed in this paper, protons with an energy of 800 GeV were extracted from the Tevatron accelerator at Fermilab and directed to a Liquid Hydrogen target. The states reviewed include [Formula: see text], ϕϕ and D*±. Partial Wave Analysis results will be presented on the light states but only the cross-section will be reviewed in the diffractive production of D*±.

Neural network trigger algorithms for heavy quark event selection in a fixed target high energy physics experiment

1992 ◽  
Vol 25 (4) ◽  
pp. 413-421 ◽  
Author(s):  
Lalit Gupta ◽  
Anand M. Upadhye ◽  
Bruce Denby ◽  
Salvator R. Amendolia ◽  
Giovanni Grieco
Keyword(s):  
Neural Network ◽  
Heavy Quark ◽  
High Energy Physics ◽  
High Energy ◽  
Fixed Target ◽  
Event Selection ◽  
Physics Experiment ◽  
Energy Physics

scholarly journals Online Event Reconstruction in the CBM Experiment at FAIR

2018 ◽  
Vol 173 ◽  
pp. 01002 ◽  
Author(s):  
Valentina Akishina ◽  
Ivan Kisel
Keyword(s):  
Heavy Ion ◽  
Time Slice ◽  
Mass Storage ◽  
Readout System ◽  
Reconstruction Procedure ◽  
Reconstruction Process ◽  
Event Selection ◽  
Huge Data ◽  
Event Reconstruction ◽  
High Interaction

Targeting for rare observables, the CBM experiment will operate at high interaction rates of up to 10 MHz, which is unprecedented in heavy-ion experiments so far. It requires a novel free-streaming readout system and a new concept of data processing. The huge data rates of the CBM experiment will be reduced online to the recordable rate before saving the data to the mass storage. Full collision reconstruction and selection will be performed online in a dedicated processor farm. In order to make an efficient event selection online a clean sample of particles has to be provided by the reconstruction package called First Level Event Selection (FLES). The FLES reconstruction and selection package consists of several modules: track finding, track fitting, event building, short-lived particles finding, and event selection. Since detector measurements contain also time information, the event building is done at all stages of the reconstruction process. The input data are distributed within the FLES farm in a form of time-slices. A time-slice is reconstructed in parallel between processor cores. After all tracks of the whole time-slice are found and fitted, they are collected into clusters of tracks originated from common primary vertices, which then are fitted, thus identifying the interaction points. Secondary tracks are associated with primary vertices according to their estimated production time. After that short-lived particles are found and the full event building process is finished. The last stage of the FLES package is a selection of events according to the requested trigger signatures. The event reconstruction procedure and the results of its application to simulated collisions in the CBM detector setup are presented and discussed in detail.

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