Characterization of Large Volume 3.5 x 8 inches LaBr3:Ce Detectors

The properties of large volume cylindrical 3.5 x 8 inches (89 mm x 203 mm) LaBr3:Ce scintillation detectors coupled to the Hamamatsu R10233-100SEL photo-multiplier tube were investigated. These crystals are among the largest ones ever produced and still need to be fully characterized to determine how these detectors can be utilized and in which applications. We tested the detectors using monochromatic gamma-ray sources and in-beam reactions producing gamma rays up to 22.6 MeV; we acquired PMT signal pulses and calculated detector energy resolution and response linearity as a function of gamma-ray energy. Two different voltage dividers were coupled to the Hamamatsu R10233-100SEL PMT: the Hamamatsu E1198-26, based on straightforward resistive network design, and the LABRVD, specifically designed for our large volume LaBr3:Ce scintillation detectors, which also includes active semiconductor devices. Because of the extremely high light yield of LaBr3:Ce crystals we observed that, depending on the choice of PMT, voltage divider and applied voltage, some significant deviation from the ideally proportional response of the detector and some pulse shape deformation appear. In addition, crystal non-homogeneities and PMT gain drifts affect the (measured) energy resolution especially in case of high-energy gamma rays. We also measured the time resolution of detectors with different sizes (from 1x1 inches up to 3.5x8 inches), correlating the results with both the intrinsic properties of PMTs and GEANT simulations of the scintillation light collection process. The detector absolute full energy efficiency was measured and simulated up to gamma-rays of 30 Me

Characterization of Large Volume 3.5″ x 8″ LaBr3:Ce Detectors for the HECTOR+ array

A selection of the properties of large volume, cylindrical 3.5" x 8" LaBr 3 :Ce scintillation detectors coupled to a 3.5" PMT (model R10233-1000SEL from HAMAMATSU) and a special designed Voltage Divider (LABRVD) will be discussed. A number of 10 of such detectors constitute the HECTOR + array which, in fall 2012, measured at GSI coupled to the AGATA DEMOSTRATOR at the PRESPEC experimental setup. These crystals are among the largest ever produced and needed to be characterized. We have performed several tests and here we discuss, in particular, the energy resolution measured using monochromatic γ −ray sources and in-beam reactions producing γ −rays up to 22.6 MeV. As already measured in two previous works a saturation in the energy resolution was observed in case of high energy gamma rays. Crystal non-homogeneities and PMT gain drifts can affect the resolution of measurements especially in case of high energy γ −rays

Challenging Mafia territorial power. Operate among market and culture to sanction Cosa nostra, a case study on Addiopizzo

Addiopizzo is an anti-mafia movement established in Palermo (2004) to struggle extortion racket. It aims to sustain, spread and consolidate a culture based on legality, as well as an economic development free from mafia constraints. Addiopizzo association have fostered the creation of a community composed by entrepreneurs who refuse Mafia protection system. We argue that refuse to pay pizzo and above all the willing to denunciate any extortion attempt , question the legitimacy of mafia\u2019s territorial power. Consequently these attitudes can be conceptualized as a sanction against Cosa nostra. For a shopkeeper, joining Addiopizzo network assumes the meaning of sharing the aforementioned attitudes and entails to signal it out. This implies an increasing perception of a possible change, namely a market field where is possible to avoid relationship with the mafia realm and to remain consistent with an ethical orientation founded on anti-mafia values and a culture of legality. Our paper intends to inquire the dynamics that make Addiopizzo\u2019s experience so effective and lasting. In particular, how a community can organize a sanction system, jointly at economical and culturall level, to challenge territorial power of crime organizations. One crucial point concern the role played by values and culture in this process. The aim is to contribute understanding the possibilities of change in a context marked by a rooted presence of organised crime through the use of a post-heroic approach, that is an incremental transformation driven by a collective action of actors otherwise weak and powerless