Crilin (Crystal Calorimeter with Longitudinal Information) is a
semi-homogeneous, longitudinally segmented electromagnetic calorimeter based on
high-$Z$, ultra-fast crystals with UV-extended SiPM ...readout. The Crilin design
has been proposed as a candidate solution for both a future Muon Collider
barrel ECAL and for the Small Angle Calorimeter of the HIKE experiment. As a
part of the Crilin development program, we have carried out beam tests of small
($10\times10\times40$~mm$^3$) lead fluoride (PbF$_2$) and ultra-fast lead
tungstate (PbWO$_4$, PWO) crystals with 120~GeV electrons at the CERN SPS to
study the light yield, timing response, and systematics of light collection
with a proposed readout scheme. For a single crystal of PbF$_2$, corresponding
to a single Crilin cell, a time resolution of better than 25~ps is obtained for
$>$3 GeV of deposited energy. For a single cell of \pwo, a time resolution of
better than 45~ps is obtained for the same range of deposited energy. This
timing performance fully satisfies the design requirements for the Muon
Collider and HIKE experiments. Further optimizations of the readout scheme and
crystal surface preparation are expected to bring further improvements.
An intense positron sources is a demanding element in the design of future lepton colliders. A crystal-based hybrid positron source could be an alternative to a more conventional scheme based on the ...electron conversion into positron in a thick amorphous target. The conceptual idea of the hybrid source is to have two separate objects, a photon radiator and a photon-to-positron converter target. In such a scheme an electron beam crosses a thin axially oriented crystal with the emission of a channeling radiation, characterized by a considerably larger amount of photons if compared to Bremsstrahlung. The net result is an increase in the number of produced positrons at the converter target. In this paper we present the results of a beam test conducted at the DESY TB 21 with 5.6 GeV electron beam and a crystalline tungsten radiator. Experimental data clearly highlight an increased production of photons and they are critically compared with the outcomes of novel method to simulate the number of radiated photons, showing a very good agreement. Strong of this, the developed simulation tool has been exploited to design a simple scheme for a positron source based on oriented crystal, demonstrating the advantages in terms of reduction of both deposited energy and the peak energy deposition density if compared to conventional sources. The presented work opens the way for a realistic and detailed design of a hybrid crystal-based positron source for future lepton colliders.
Crilin (Crystal Calorimeter with Longitudinal Information) is a semi-homogeneous, longitudinally segmented electromagnetic calorimeter based on high-\(Z\), ultra-fast crystals with UV-extended SiPM ...readout. The Crilin design has been proposed as a candidate solution for both a future Muon Collider barrel ECAL and for the Small Angle Calorimeter of the HIKE experiment. As a part of the Crilin development program, we have carried out beam tests of small (\(10\times10\times40\)~mm\(^3\)) lead fluoride (PbF\(_2\)) and ultra-fast lead tungstate (PbWO\(_4\), PWO) crystals with 120~GeV electrons at the CERN SPS to study the light yield, timing response, and systematics of light collection with a proposed readout scheme. For a single crystal of PbF\(_2\), corresponding to a single Crilin cell, a time resolution of better than 25~ps is obtained for \(>\)3 GeV of deposited energy. For a single cell of \pwo, a time resolution of better than 45~ps is obtained for the same range of deposited energy. This timing performance fully satisfies the design requirements for the Muon Collider and HIKE experiments. Further optimizations of the readout scheme and crystal surface preparation are expected to bring further improvements.
Bacteria able to accumulate porphyrins can be inactivated by visible light irradiation thanks to the photosensitizing properties of this class of aromatic pigments (photodynamic therapy, PDT). Since ...the bacterial resistance to antibiotic is growing, PDT is becoming a valid alternative. In this context, the pathogen Helicobacter pylori (Hp) is a suitable target for PDT since it spontaneously produces and accumulates porphyrins. It is then important to understand the spectroscopic behavior of these endogenous species to exploit them as photosensitizers, thus improving the results given by the application of PDT in the treatment of Hp infections. In this work we extracted porphyrins from both a laboratory-adapted and a virulent strain of Hp, and we performed spectroscopic and chromatographic experiments to collect information about the composition and the spectrophotometric features of the extracts. The main components of the porphyrin mixtures were identified and their relative contribution to the global red fluorescence was examined.
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•Bacteria producing photosensitizers are optimal targets for photodynamic therapy.•Helicobacter pylori (Hp) produces a mixture of endogenous porphyrins.•Porphyrins were successfully extracted from Hp.•The main porphyrinic components of the extract were identified.•Their relative contribution to the global red fluorescence was examined.
In nanoscale magnetic systems, the possible coexistence of structural disorder and competing magnetic interactions may determine the appearance of a glassy magnetic behavior, implying the onset of a ...low-temperature disordered collective state of frozen magnetic moments. This phenomenology is the object of an intense research activity, stimulated by a fundamental scientific interest and by the need to clarify how disordered magnetism effects may affect the performance of magnetic devices (e.g., sensors and data storage media). We report the results of a magnetic study that aims to broaden the basic knowledge of glassy magnetic systems and concerns the comparison between two samples, prepared by a polyol method. The first can be described as a nanogranular spinel Fe-oxide phase composed of ultrafine nanocrystallites (size of the order of 1 nm); in the second, the Fe-oxide phase incorporated non-magnetic Au nanoparticles (10-20 nm in size). In both samples, the Fe-oxide phase exhibits a glassy magnetic behavior and the nanocrystallite moments undergo a very similar freezing process. However, in the frozen regime, the Au/Fe-oxide composite sample is magnetically softer. This effect is explained by considering that the Au nanoparticles constitute physical constraints that limit the length of magnetic correlation between the frozen Fe-oxide moments.
Soybean (Glycine max L.) monocropping have had a great socio-economic and environmental impact on the world and agroforestry systems has been considered an alternative for more sustainable ...production. The aim of this study was to evaluate the effect of different arrangements of agroforestry systems of the species E. urophylla x E. grandis and P. dubium and the pruning of the trees on the dynamics of solar radiation and soybean yield. A field experiment was conducted in Southern Brazil. In order to achieve the objective of the study, the solar radiation transmissivity and the productive performance of the soybean were evaluated. In this study, the soybean yield was determined by the arrangement of the agroforestry system and forest species utilized. The soybean crop cultivated in the understory of the P. dubium trees showed the highest yield response. The use of silvicultural practices for the management of forest species should be considered to generate the balance of the productive system. In this context, tree pruning is a viable side for agroforestry systems, as it promotes an increase in the incidence of solar radiation in the understory, resulting in an increase in soybean yield, especially when integrated with P. dubium.
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