The CALICE collaboration is studying the design of high performance electromagnetic and hadronic calorimeters for future International Linear Collider detectors. For the electromagnetic calorimeter, the current baseline choice is a high granularity sampling calorimeter with tungsten as absorber and silicon detectors as sensitive material. A "physics prototype" has been constructed, consisting of thirty sensitive layers. Each layer has an active area of 18 × 18 cm 2 and a pad size of 1 × 1 cm 2 . The absorber thickness totals 24 radiation lengths. It has been exposed in 2006 and 2007 to electron and hadron beams at the DESY and CERN beam test facilities, using a wide range of beam energies and incidence angles. In this paper, the prototype and the data acquisition chain are described and a summary of the data taken in the 2006 beam tests is presented. The methods used to subtract the pedestals and calibrate the detector are detailed. The signal-overnoise ratio has been measured at 7.63 ± 0.01. Some electronics features have been observed; these lead to coherent noise and crosstalk between pads, and also crosstalk between sensitive and passive areas. The performance achieved in terms of uniformity and stability is presented.
The generation of betatron radiations by laser-accelerated electron beams is of great interest in the scientific community as it has many applications. In this paper, we propose a new method for the generation of short wavelength betatron radiations. In the new scheme, a high power laser pulse is sent into a capillary plasma waveguide at an off-axis position to intentionally enhance the betatron oscillation amplitude, which can lead to the production of shorter wavelength radiations. We demonstrated that the idea works by 2D particle-in-cell simulations and we also developed a theory to explain the phenomena. In this paper, details of the results are described.
Recent studies have shown that energetic laser-driven ions with some energy spread can heat small solid-density samples uniformly. The balance among the energy losses of the ions with different kinetic energies results in uniform heating. Although heating with an energetic laser-driven ion beam is completed within a nanosecond and is often considered sufficiently fast, it is not instantaneous. Here we present a theoretical study of the temporal evolution of the temperature of solid-density gold and diamond samples heated by a quasimonoenergetic aluminum ion beam. We calculate the temporal evolution of the predicted temperatures of the samples using the available stopping power data and the SESAME equation-of-state tables. We find that the temperature distribution is initially very uniform, which becomes less uniform during the heating process. Then, the temperature uniformity gradually improves, and a good temperature uniformity is obtained toward the end of the heating process.
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