A method of eta' decay product selection to study partial chiral symmetry restoration

In case of chiral U_A(1) symmetry restoration the mass of the eta' boson (the ninth, would-be Goldstone boson) is decreased, thus its production cross section is heavily enhanced. The eta' decays (through one of its decay channels) into five pions. These pions will not be correlated in terms of Bose-Einsten correlations, thus the production enhancement changes the strength of two-pion correlation functions at low momentum. Preliminary results strongly support the mass decrease of the eta' boson. In this paper we propose a method to select pions coming from eta' decays. We investigate the efficiency of the proposed kinematical cut in several collision systems and energies with several simulators. We prove that our method can be used in all investigeted collision systems.Comment: Talk at the VI Workshop on Particle Correlations and Femtoscopy, Kiev, September 14-18, 2010. 6 pages, 3 figures. This work was supported by the OTKA grant NK73143 and M. Csanad's Bolyai scholarshi

The Bergen proton CT system

The Bergen proton Computed Tomography (pCT) is a prototype detector under construction. It aims to have the capability to track and measure ions’ energy deposition to minimize uncertainty in proton treatment planning. It is a high granularity digital tracking calorimeter, where the first two layers will act as tracking layers to obtain positional information of the incoming particle. The remainder of the detector will act as a calorimeter. Beam tests have been performed with multiple beams. These tests have shown that the ALPIDE chip sensor can measure the deposited energy, making it possible for the sensors to distinguish between the tracks in the Digital Tracking Calorimeter (DTC)

Anomalous Broadening of Jet-Peak Shapes in Pb-Pb Collisions and Characterization of Monolithic Active Pixel Sensors for the ALICE Inner Tracking System Upgrade

Two-particle angular correlations are presented from Pb-Pb and pp collisions at 2.76 TeV. These measurements are powerful tools to study jets in a transverse momentum regime where they cannot be reconstructed over the large fluctuating background produced in heavy-ion collisions. In these studies, the distribution of azimuthal angle (Δφ) and pseudorapidity (Δη) differences of particle pairs is calculated. Jets manifest themselves as a peak around (Δφ, Δη) = (0, 0) and as a structure elongated in Δη at Δφ = π. The jet peak is studied as a function of transverse momentum and centrality in Pb-Pb collisions, and it is compared to pp collisions and to results from A Multi-Phase Transport model (AMPT). In Pb-Pb collisions, an asymmetric broadening of the jet peak towards central collisions at low transverse momentum is found, and in addition an unexpected depletion around (Δφ, Δη) = (0, 0) is observed. The comparison to AMPT suggests that the two effects are connected to large radial and longitudinal flow, therefore they can arise from an interplay of the jets with the flowing medium produced in the collisions of heavy-ions. The measurements are done by the ALICE detector, which will be upgraded during the second long shutdown of the LHC in 2019-2020. During this upgrade, the Inner Tracking System of ALICE will be replaced by a detector consisting of seven concentric layers of Monolithic Active Pixel Sensors. The prototypes of this detector and the setup used for their characterization are discussed in details. Tests at test beam facilities are carried out on unirradiated sensors and irradiated sensors are tested as well to study the long term functionality of the detector. The results of these measurements are presented, and it is found that the prototypes fulfill the requirements of the upgrade in terms of detection efficiency, spatial resolution and noise occupancy both before and after irradiation, making them suitable for the operation in the environment in the ALICE experiment

Anomalous Broadening of Jet-Peak Shapes in Pb-Pb Collisions and Characterization of Monolithic Active Pixel Sensors for the ALICE Inner Tracking System Upgrade

Two-particle angular correlations are presented from Pb-Pb and pp collisions at 2.76 TeV. These measurements are powerful tools to study jets in a transverse momentum regime where they cannot be reconstructed over the large fluctuating background produced in heavy-ion collisions. In these studies, the distribution of azimuthal angle (Δφ) and pseudorapidity (Δη) differences of particle pairs is calculated. Jets manifest themselves as a peak around (Δφ, Δη) = (0, 0) and as a structure elongated in Δη at Δφ = π. The jet peak is studied as a function of transverse momentum and centrality in Pb-Pb collisions, and it is compared to pp collisions and to results from A Multi-Phase Transport model (AMPT). In Pb-Pb collisions, an asymmetric broadening of the jet peak towards central collisions at low transverse momentum is found, and in addition an unexpected depletion around (Δφ, Δη) = (0, 0) is observed. The comparison to AMPT suggests that the two effects are connected to large radial and longitudinal flow, therefore they can arise from an interplay of the jets with the flowing medium produced in the collisions of heavy-ions. The measurements are done by the ALICE detector, which will be upgraded during the second long shutdown of the LHC in 2019-2020. During this upgrade, the Inner Tracking System of ALICE will be replaced by a detector consisting of seven concentric layers of Monolithic Active Pixel Sensors. The prototypes of this detector and the setup used for their characterization are discussed in details. Tests at test beam facilities are carried out on unirradiated sensors and irradiated sensors are tested as well to study the long term functionality of the detector. The results of these measurements are presented, and it is found that the prototypes fulfill the requirements of the upgrade in terms of detection efficiency, spatial resolution and noise occupancy both before and after irradiation, making them suitable for the operation in the environment in the ALICE experiment