Puzzles of MultiplicityParticle Production in pp Interaction

with High Multiplicity at 50 GeV

Prepared ByM. A. Allosh, SVU, Egypt

Z. M. Shakfe , Cairo university, EgyptSupervision

Assit. Prof. Elena Kokoulina,LHEP JINR, Dubna, Russia

June 1, 2012

Scientific Program:

• High Multiplicity (more than mean multiplicity) the number of secondary particles study in pp interaction.

The main tasks

General task: Investigation of collective phenomena in the process p + p → 2N + nπ nπ=20 : 40

Multiplicity distributions for neutral and charged particles at high energies in lepton, hadron and nuclei interactions in framework of gluon dominance model.

Getting acquainted with the work of the main detectors of SVD-2 setup: vertex detector, drift tube tracker, magnetic spectrometer, electromagnetic calorimeter and scintillator hodoscope.

Alignment task. Drift tube calibration procedure.

High energy physics began with registration of known at that time charged hadrons: protons and electrons.

Later the number of kinds of secondary particles significantly increased.

All of them were produced at high energy collisions of hadrons, nuclei or leptons.

Different models and theoretical approaches began to develop for the description of multiparticale production.

introduction

At present the ended understanding of the process of multiparticle production is absent. It is stipulated by unknown of hadronization: “ how invisible quarks and gluons are transformed to observable hadrons”.

That is why there is significant discrepancy between theoretical predictions and experimental data for multiplicity behavior.

introduction

Fig. 1. Scheme of the relativistic heavy ion interaction: quark-gluon scattering and hadron jet formation.

introduction

The formation of the quark-gluon system with the following transformation to hadrons under the extreme conditions can give additional information concerning multiplicity processes.

In SVD (Spectrometer with Vertex Detector) Collaboration events with the number of secondary particles significantly more than the mean multiplicity (extreme multiplicity) are investigated.

Manifestation of the collective behavior of secondary

particles will help to understand better the above tasks.

introduction

10 mMagnetic Spectrometer

Vertex Detector

ECal

Č

Drift tube tracker

H2 Target

High Mult Trig.

Fig. 3 . SVD-2 (Spectrometer with Vertex Detector)

Cherenkov counter

Liquid hydrogen target

Scintillation hodoscope for the registration of rare events with HM:

20 elements (“petals”): triangle h=18, 1.8 mm thick.

Straw Drift tubes• Gaseous detectors which used as track detectors

especially in the high-rate environment.• In SVD_2, There are 3 modules of drift tubes. Each

consists of 3 planes ( U,V,Y).• To reconstruct tracks , The hits in each DT cell are

reconstructed from the measured drift time associated to them as recorded by the TDCs (Time to Digital Converters).

Calibration of Drift tubes

• The min. and max. values of drift time t0 ,tmax are obtained from calibration runs.

• To do such calibration, we used ROOT generator .

Examples of Our work

root [0] .L calibDT.Croot [1] main()root [2] NTuberoot [3] 153

root [0] mcroot [1] lsroot [2] cdroot [3] rootroot [4] .L libDT.Croot [5] main(153)root [6] .L arin2.Croot [7]main (153)

TDC Distributions of all 9 planes with min and max values of drift time for each tube

TDC distribution and calibration function of V2 plane, Tube num.150

TDC distribution and calibration function of U1 plane, NTube 130

TDC distribution and calibration function of Y3 plane, Tube num.40

We notice that this not very good tube because of small number of entries (only 1791)

TDC distribution and calibration function of V2 plane, Tube num.90

Acknowledgments

To Elena Kokoulina for her guidance and efforts to help us in our project.

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