The Impact of Crystal Light Yield Non-Proportionality on a Typical Calorimetric Space Experiment: Beam Test Measurements and Monte Carlo Simulations

Calorimetric space experiments were employed for the direct measurements of cosmic-ray spectra above the TeV region. According to several theoretical models and recent measurements, relevant features in both electron and nucleus fluxes are expected. Unfortunately, sizable disagreements among the current results of different space calorimeters exist. In order to improve the accuracy of future experiments, it is fundamental to understand the reasons of these discrepancies, especially since they are not compatible with the quoted experimental errors. A few articles of different collaborations suggest that a systematic error of a few percentage points related to the energy-scale calibration could explain these differences. In this work, we analyze the impact of the nonproportionality of the light yield of scintillating crystals on the energy scale of typical calorimeters. Space calorimeters are usually calibrated by employing minimal ionizing particles (MIPs), e.g., nonshowering proton or helium nuclei, which feature different ionization density distributions with respect to particles included in showers. By using the experimental data obtained by the CaloCube collaboration and a minimalist model of the light yield as a function of the ionization density, several scintillating crystals (BGO, CsI(Tl), LYSO, YAP, YAG and BaF2) are characterized. Then, the response of a few crystals is implemented inside the Monte Carlo simulation of a space calorimeter to check the energy deposited by electromagnetic and hadronic showers. The results of this work show that the energy scale obtained by MIP calibration could be affected by sizable systematic errors if the nonproportionality of scintillation light is not properly taken into account

Characterization of the Calocube front-end electronics coupled with VTH2090 photodiode

The calorimeter Calocube is designed to bring a significant contribution to the direct observation of cosmic rays at high energy. This calorimeter will consist of scintillator (CsI(Tl)) cubes read out by photodiodes. In this report we present a study of the response of the front-end electronics of the Calocube prototype, that consists of 9 CASIS chips, coupled with the VTH2090 photodiode. The CASIS chip is a double-gain, large dynamic range Front-end ASIC for silicon detectors Read-Out. Thanks to some PSpice simulation, confirmed by measurements on the real circuit, we understood the causes of some anomalous behaviors of the front-end electronics that could disrupt the proper functioning of the prototype. We present also a few different circuit configurations that could partially eliminate this effects

The High-Voltage System of Calet Apparatus

CALET (CALorimetric Electron Telescope) is installed on the International Space Station since August 2015, is a mission devoted to measure the intensity of cosmic ray electrons and protons accelerated to near the speed of light. The apparatus is also designed to observe high energy gamma rays, nearby source of high energy radiation and it may even detect signatures of the elusive dark matter. One of the core components of the whole apparatus is the high voltage power supply system. It is based on hundred of independent DC/DC converters providing precise voltage regulation to two sections of CALET detectors. This paper presents the experience gained in the implementation of the CALET HV system: the system design requirements and the technical solutions adopted, the two system sections block schemes and the main characteristics of the DC/DC converters that guarantee the CALET HV system technical performance

The High-Voltage System of Calet Apparatus

CALET (CALorimetric Electron Telescope) is installed on the International Space Station since August 2015, is a mission devoted to measure the intensity of cosmic ray electrons and protons accelerated to near the speed of light. The apparatus is also designed to observe high energy gamma rays, nearby source of high energy radiation and it may even detect signatures of the elusive dark matter. One of the core components of the whole apparatus is the high voltage power supply system. It is based on hundred of independent DC/DC converters providing precise voltage regulation to two sections of CALET detectors. This paper presents the experience gained in the implementation of the CALET HV system: the system design requirements and the technical solutions adopted, the two system sections block schemes and the main characteristics of the DC/DC converters that guarantee the CALET HV system technical performance

Composition of essential oils of Helychrysum italicum (Roth) G. Don fil subsp. italicum fron Tuscan Archipelago islands

The essential oils obtained by water distillation from the aerial parts of Helichrysum italicum subsp. italicum growing on Tuscan Archipelago Islands were analyzed by CG-RI and CG-MS. These oils were characterized by the predominance of oxygenated compounds and by a qualitatively homogeneous composition. However, according to the amounts of β-diketones and neryl acetate, two chemical compositions were distinguishe