Open Charm Measurements at CERN SPS Energies with the New Vertex Detector of the NA61/SHINE Experiment

A Merzlaya

doi:10.18502/ken.v3i1.1738

Abstract

The heavy-ion programme of the NA61/SHINE experiment at the CERN SPS has been expanded to allow precise measurements of exotic particles with short lifetime. The study of open charm meson production is a sensitive tool for new detailed investigations of the properties of hot and dense matter formed in nucleus-nucleus collisions. In particular, it offers new possibilities for studies of such phenomena as in- medium parton energy loss and quarkonium dissociation and possible regeneration, thus providing new information to probe deconfinement. A new high resolution Vertex Detector was designed for the NA61/SHINE experiment for measurements of the very rare processes of open charm production in nucleus- nucleus collisions at the SPS. It will meet the challenges of track registration and of very precise spatial resolution in primary and secondary vertex reconstruction required for the identification of

Highlights

The SPS Heavy Ion and Neutrino Experiment (NA61/SHINE) [1] at CERN was designed for studies of the properties of the onset of deconfinement and search for the critical point of strongly interacting matter
For open charm measurements in nucleus-nucleus collisions at SPS energies, the experiment NA61/SHINE was upgraded with the new Small Acceptance Vertex Detector (SAVD) [3,4,5]
The low yields of D mesons and their short lifetime require detectors located close to the primary vertex that are capable of providing high tracking efficiency and high primary and secondary vertex resolution

Summary

Track and vertex reconstruction

After the primary vertex is found, the step of track reconstruction searches for 3-hit tracks using the Hough transform method (for more details see [8]). It uses a parametric description of the track by a set of parameters. Once a parametric description of the track in the coordinate space is given, the hit position measurements are transformed into the track parameter space In this so-called accumulation space track candidates are obtained as local maxima using the voting procedure: the most popular candidates are accepted as real tracks. The magnetic field in the Vertex Detector volume allows momentum reconstruction of the SAVD-tracks [8]. The obtained values are useful for verifying track matching between SAVD-tracks and TPC-tracks

Track matching

Reconstruction of D0 signal

Findings

Summary