ALICE (A Large Ion Collider Experiment) is one of the four main experiments of the Large Hadron Collider (LHC) which is located in the Franco-Swiss border and run by the European Organization for Nuclear Research (CERN). Its main physics goal is the study and characterization of a new state of matter known as quark-gluon plasma (QGP) created in high energy heavy-ion collisions. The quarks are the components of neutrons and protons in the atomic nucleus and locked inside them (there are no free quarks in nature). However, they can become deconfined in this new state, forming a high density, low viscosity fluid in which they are almost free to move, and where there are no more hadronic boundaries.

ALICE is unique among other experiments at the LHC due to its excellent particle identification capabilities, low transverse momentum (pT) threshold, and their coverage in eight units of pseudorapidity. This makes ALICE an ideal tool for the study of diffractive physics. A diffractive event happens when two proton exchange a phenomenological particle carrying the quantum numbers of the vacuum, called pomeron. In this type of interaction, no color is exchanged by the protons so each of them preserve their identity. However, in diffractive events, momentum transfer will cause one (single diffraction) or both protons (double diffraction) to become an excited system and then fragment into several particles. The topology of these events are characterized by rapidity gaps between, i.e. a large angle interval devoid of particles between the forward products of the diffracted protons.

The PUCP HEP Group is an official member of the ALICE collaboration. We carried out the performance studies of the new AD detector (ALICE Diffractive), which enhances the ALICE ability to tag diffractive events. These studies lead to the approval and construction of the detector. Our group also participated in the successful commissioning and installation of the AD detector in 2014 and beginning of data taking in 2015. Now the focus is on the analysis of data produced by the AD and other ALICE detectors in order to measure the diffractive cross sections at an energy of 13 TeV at the LHC.

The group also participates in the construction of the Muon Forward Tracker (MFT), a new Si-tracking detector designed to add vertexing capabilities to the muon spectrometer of ALICE. The MFT will allow ALICE to extend the precision measurements of the QGP fundamental properties towards the forward rapidity region and opens the path to new measurements not accessible with the present apparatus (open charm/beauty separation, ψ in central Pb–Pb collisions and J/ψ from b-hadron decays measurements). The basic detection elements of the MFT are CMOS Monolithic Active Pixel Sensors (MAPS), which are  silicon pixel sensors that combine the active semiconductor sensor and the front-end readout electronics in a single device. The PUCP HEP Group is involved in the characterization and performance testing of the recently developed prototype pixel sensors and the development of the read-out electronics for the final detector which will contain roughly 1000 of these pixel sensors.

Estado DGI: En proceso