Particle receivers are gaining much interest mainly for their potential of high temperature opera... more Particle receivers are gaining much interest mainly for their potential of high temperature operation and as thermal energy storage Dense gas-solid suspensions thanks to their excellent thermal properties RECEIVER: Collection of highly concentrated (100-1000 suns) incident solar radiation EXCHANGE: heat transfer to the working fluid of the thermodynamic cycle STORAGE: thermal energy for equalizing the inherent timevariability of the incident solar radiation System optimized to accomplish three complementary tasks: Challenge: compartmented fluidization without physical confinements just by partitioning of the fluidizing gas to a compartmented distributor to preserve the fluidized bed thermal properties Conclusions
A study on the hydrodynamics in gas-solid fluidized beds where the primary gas injection is achie... more A study on the hydrodynamics in gas-solid fluidized beds where the primary gas injection is achieved through a nozzle-type gas distributor has been carried out, using an innovative X-ray imaging technique. Qualitative and quantitative results are reported, with particular regards to the jet penetration length. Results show that the lighter and the finer are the particles, the larger is the jet penetration. A new non-dimensional correlation is proposed, since the experimental data do not match predictions available in literature, based on hydrodynamic scaling and Froude number. The new correlation takes into account the effects of jet velocity, particle density and particle size. A tentative mechanistic explanation for the departure from purely hydrodynamic scaling is offered.
The unceasing concern for climate change, closely related to the exploitation of fossil fuels, pu... more The unceasing concern for climate change, closely related to the exploitation of fossil fuels, pushes the scientific community to develop new technologies for CO 2 capture and utilization (CCU). Moreover, the growth and diffusion of solar energy requires new energy storage systems that put solar fuels at the forefront. Methane seems to be a suitable energy vector, which could both store solar energy and exploit fossil fuel derived CO 2 . Moreover, methane has the main advantage of an already existing distribution and storage infrastructure. The methanation reaction from hydrogen and carbon dioxide (or monoxide) is generally carried out in staged adiabatic catalytic fixed beds operated at high pressure in order to overcome thermodynamic limitations. A recently proposed alternative pathway is the sorptionenhanced methanation concept, which is based on the employment of a sorbent able to capture in situ the H 2 O produced during reaction, to shift equilibrium towards the formation of CH 4 . In this work a CaO, derived from natural limestone, and a commercial 3A Zeolite were tested as sorbent materials for H 2 O capture in a new configuration for the sorption-enhanced methanation based on the concept of chemical looping in dual interconnected fluidized bed systems. The experimental campaign was aimed at studying the sorbent performance in terms of hydration and dehydration at different operating conditions relevant for catalytic methanation. The results showed that CaO has a good capacity to capture and release steam in the temperature range of interest. Unfortunately, even at the lowest temperatures tested, the sorbent is affected by the presence of CO 2 , which worsens its performance in terms of H 2 O capture capacity. The zeolite has a more stable behavior than CaO under all investigated conditions. Comparing the performance of the two materials, the zeolite on average has better capture capacity (0.017-0.049 g/g) than CaO (0.006-0.025 g/g) and it is not affected by deactivation during the cycles.
Environmental Engineering and Management Journal, 2013
The preliminary assessment of a cost-effective flow-sheet for the production of biodiesel from mi... more The preliminary assessment of a cost-effective flow-sheet for the production of biodiesel from microalgae lipid fraction was carried out. The study was based on approximated cost-estimation methods integrated with the simulation software Aspen Plus ® . Several scenarios were investigated to compare costs regarding the main steps of the biodiesel production process. Ranges of input variables from downstream literature and experimental data were used to simulate the sections that define concrete process routes for production of algal biofuels: the extraction of the lipid fraction from aqueous solution, the lipid transesterification, and the methyl esters (FAMEs) and glycerol recover. The design variables were selected so as to correspond to the main degrees of freedom of the process: number of equilibrium stages, solvent recycle flow rate, transesterification time, methanol to triacylglycerols ratio, plate number and reflux ratio of the distillation unit for methanol recovery. The cost estimation for the conceptual design of the flowsheet dedicated to the FAMEs production from microalgae was carried out according to Happel's method. Data were worked out to assess the venture profit and the selling price (s) for mass unit of FAMEs. The minimization of s was adopted as the objective function. A preliminary determination of plausible values of the cost for unit of mass of biodiesel was attempted as a function of operating conditions.
An appropriate hydrodynamic model of the whole system in order to point out "stable" operating co... more An appropriate hydrodynamic model of the whole system in order to point out "stable" operating conditions. Most of numerical simulations of CLR in DIFB are focused only on kinetic scheme
Background: Succinic acid is one of the most interesting platform chemicals that can be produced ... more Background: Succinic acid is one of the most interesting platform chemicals that can be produced in a biorefinery approach. In this study, continuous succinic acid production by Actinobacillus succinogenes fermentation in a packedbed biofilm reactor (PBBR) was investigated. The effects of the operating conditions tested, dilution rate (D), and medium composition (mixture of glucose, xylose, and arabinose-that simulate the composition of a lignocellulosic hydrolysate)-on the PBBR performances were investigated. The maximum succinic acid productivity of 35.0 g L -1 h -1 and the maximum SA concentration were achieved at a D = 1.9 h -1 . The effect of HMF and furfural on succinic acid production was also investigated. HMF resulted to reduce succinic acid production by 22.6%, while furfural caused a reduction of 16% in SA production at the same dilution rate. Conclusion: Succinic acid production by A. succinogenes fermentation in a packed-bed reactor (PBBR) was successfully carried out for more than 5 months. The optimal results were obtained at the dilution rate 0.5 h -1 : 43.0 g L -1 of succinic acid were produced, glucose conversion was 88%; and the volumetric productivity was 22 g L -1 h -1 .
Nuovo Cimento Della Societa Italiana Di Fisica A-nuclei Particles and Fields, 2017
DarkSide is a dark matter direct search experiment at Laboratori Nazionali del Gran Sasso (LNGS).... more DarkSide is a dark matter direct search experiment at Laboratori Nazionali del Gran Sasso (LNGS). DarkSide is based on the detection of rare nuclear recoils possibly induced by hypothetical dark matter particles, which are supposed to be neutral, massive (m > 10 GeV) and weakly interactive (WIMP). The dark matter detector is a two-phase time projection chamber (TPC) filled with ultra-pure liquid argon. The TPC is placed inside a muon and a neutron active vetoes to suppress the background. Using argon as active target has many advantages, the key features are the strong discriminant power between nuclear and electron recoils, the spatial reconstruction and easy scalability to multi-tons size. At the moment DarkSide-50 is filled with ultra-pure argon, extracted from underground sources, and from April 2015 it is taking data in its final configuration. When combined with the preceding search with an atmospheric argon target, it is possible to set a 90% CL upper limit on the WIMP-nuc...
DarkSide uses a dual-phase Liquid Argon Time Projection Chamber (TPC) to search for WIMP dark mat... more DarkSide uses a dual-phase Liquid Argon Time Projection Chamber (TPC) to search for WIMP dark matter. The paper will present the latest result on the search for low mass ($M_{WIMP} 100\,Gev/c^2$) WIMPs from the current experiment, DarkSide-50, running since mid 2015 a 50-kg-active-mass TPC, filled with argon from an underground source. The next stage of the DarkSide program will be a new generation experiment involving a global collaboration from all the current Argon based experiments. DarkSide-20k, is designed as a 20-tonne fiducial mass TPC with SiPM based photosensors, expected to be free of any background for an exposure of >100 ton x years. Like its predecessor DarkSide-20k will be housed at the Gran Sasso (LNGS) underground laboratory, and it is expected to attain a WIMP-nucleon cross section exclusion sensitivity of $10^{-47}\,cm^2$ for a WIMP mass of $1\,TeV/c^2$ in a 5 yr run. A subsequent objective, towards the end of the next decade, will be the construction of the ul...
Journal of Cosmology and Astroparticle Physics, 2021
Future liquid-argon DarkSide-20k and Argo detectors, designed for direct dark matter search, will... more Future liquid-argon DarkSide-20k and Argo detectors, designed for direct dark matter search, will be sensitive also to core-collapse supernova neutrinos, via coherent elastic neutrino-nucleus scattering. This interaction channel is flavor-insensitive with a high-cross section, enabling for a high-statistics neutrino detection with target masses of ∼50 t and ∼360 t for DarkSide-20k and Argo respectively. Thanks to the low-energy threshold of ∼0.5 keVnr achievable by exploiting the ionization channel, DarkSide-20k and Argo have the potential to discover supernova bursts throughout our galaxy and up to the Small Magellanic Cloud, respectively, assuming a 11-M☉ progenitor star. We report also on the sensitivity to the neutronization burst, whose electron neutrino flux is suppressed by oscillations when detected via charged current and elastic scattering. Finally, the accuracies in the reconstruction of the average and total neutrino energy in the different phases of the supernova burst,...
Proportional electroluminescence (EL) in noble gases is used in two-phase detectors for dark matt... more Proportional electroluminescence (EL) in noble gases is used in two-phase detectors for dark matter searches to record (in the gas phase) the ionization signal induced by particle scattering in the liquid phase. The “standard” EL mechanism is considered to be due to noble gas excimer emission in the vacuum ultraviolet (VUV). In addition, there are two alternative mechanisms, producing light in the visible and near infrared (NIR) ranges. The first is due to bremsstrahlung of electrons scattered on neutral atoms (“neutral bremsstrahlung”, NBrS). The second, responsible for electron avalanche scintillation in the NIR at higher electric fields, is due to transitions between excited atomic states. In this work, we have for the first time demonstrated two alternative techniques of the optical readout of two-phase argon detectors, in the visible and NIR range, using a silicon photomultiplier matrix and electroluminescence due to either neutral bremsstrahlung or avalanche scintillation. The...
Aria is a plant hosting a$${350}\,\hbox {m}$$350mcryogenic isotopic distillation column, the tall... more Aria is a plant hosting a$${350}\,\hbox {m}$$350mcryogenic isotopic distillation column, the tallest ever built, which is being installed in a mine shaft at Carbosulcis S.p.A., Nuraxi-Figus (SU), Italy. Aria is one of the pillars of the argon dark-matter search experimental program, lead by the Global Argon Dark Matter Collaboration. It was designed to reduce the isotopic abundance of$${^{39}\hbox {Ar}}$$39Arin argon extracted from underground sources, called Underground Argon (UAr), which is used for dark-matter searches. Indeed,$${^{39}\hbox {Ar}}$$39Aris a$$\beta $$β-emitter of cosmogenic origin, whose activity poses background and pile-up concerns in the detectors. In this paper, we discuss the requirements, design, construction, tests, and projected performance of the plant for the isotopic cryogenic distillation of argon. We also present the successful results of the isotopic cryogenic distillation of nitrogen with a prototype plant.
The high temperatures and heating rates typical of PF are known to induce thermal annealing of ch... more The high temperatures and heating rates typical of PF are known to induce thermal annealing of char and loss of its reactivity. Several authors investigated this effect for coals in inert atmospheres, while little is known about the effects of CO 2 rich atmospheres, typical of oxycombustion and gasification, on the course of thermal annealing. Thermal annealing of biomass has been scarcely investigated in the literature, however available studies reported that also biomass can suffer from thermodeactivation. The present study aims to provide further insight on thermal annealing of biomass in the context of gasification and oxy-combustion. A lignin rich biomass (Walnut shells) has been heat treated in a heated strip reactor (HSR) at temperatures of 1573-2073 K with a holding time of 3 s using atmospheres of either N 2 or CO 2 . Similar experiments have been performed with a high volatile bituminous coal (Colombian coal) used as reference. The char samples have been analyzed by thermogravimetric analysis and Raman spectroscopy. Results have been further compared with those reported in previous studies where heat treatment of the same fuels were performed in fixed bed, fluidized bed and drop tube reactors at lower temperature or shorter holding time.
The biosynthesis of poly-β-hydroxybutyrate (PHB) by bioconversion of CO 2 is a sustainable altern... more The biosynthesis of poly-β-hydroxybutyrate (PHB) by bioconversion of CO 2 is a sustainable alternative to the non-renewable, petroleum-based polymer production. Indeed, the PHB production by conversion of CO 2 contributes to the reduction of the greenhouse-gas concentration in the atmosphere. A kinetic dynamic model of PHB production by autotrophic cultures of Synechocystis PCC6803 was proposed and developed by means of the biochemical networks simulator COPASI. Two classes of cells were assumed to be present in the broth: growing cells, PHB producing cells. The model included the two classes of cells and their nitrogen and phosphate internal quota. The dynamics of the cell growth and PHB production were described taking into account: cellular growth rate; lysis rate; nitrate and phosphate utilization rate; PHB production rate. The assessment of the kinetic parameters and of the yields (model calibration) was carried out by the regression of experimental data. Tests were carried out in photobioreactors under dynamic light system (light/dark cycle) using media characterized by initial nitrate concentration ranging between 0 and 1.5 g/L. The developed model was validated with respect to independent experimental set. The proposed model successfully reproduced the experimental data (cell concentration, nitrogen and phosphate concentration and PHB content): the square correlation coefficient of the investigated variable concentrations ranged between 0.81 and 0.99. Parameter sensitivity analysis was carried out to assess the role of the selected parameters on cell growth and PHB accumulation. The dynamics of cellular growth were not significantly affected by a ± 20% variation of maximum specific growth rate, of velocity of conversion to PHB producing cells, and of maximum uptake rate of nitrate. The PHB accumulation dynamics were particularly sensitive to the variation of the value of the investigated parameters. The proposed model may support the design and the optimization of a PHB production process by means of autotrophic cultures.
In this work, after a briefly excursus on two models of academic "learning contexts", the experie... more In this work, after a briefly excursus on two models of academic "learning contexts", the experience underway at the University of Naples Federico II is described. The path from a FabLab 1.0 born on the field, by spontaneous initiative of some teachers and students, towards a new structured and institutional learning is described. This new FabLab 2.0 constitutes an opportunity, based on the international experiences of "FabLab" and "Learning Factory", of facing the educational challenges posed by the transition to the context of "Industry 4.0".
Building on the successful experience in operating the DarkSide-50 detector, the Dark-Side Collab... more Building on the successful experience in operating the DarkSide-50 detector, the Dark-Side Collaboration is going to construct DarkSide-20k, a direct WIMP search detector using a two-phase Liquid Argon Time Projection Chamber (LAr TPC) with an active (fiducial) mass of 23 t (20 t). The DarkSide-20k LAr TPC will be deployed within a shield/veto with a spherical Liquid Scintillator Veto (LSV) inside a cylindrical Water Cherenkov Veto (WCV). Operation of DarkSide-50 demonstrated a major reduction in the dominant 39 Ar background when using argon extracted from an underground source, before applying pulse shape analysis. Data from DarkSide-50, in combination with MC simulation and analytical modeling, shows that a rejection factor for discrimination between electron and nuclear recoils of >3 × 10 9 is achievable. This, along with the use of the veto system, is the key to unlocking the path to large LAr TPC detector masses, while maintaining an "instrumental background-free" experiment, an experiment in which less than <0.1 events (other than ν-induced nuclear recoils) is expected to occur within the WIMP search region during the planned exposure. DarkSide-20k will have ultra-low backgrounds than can be measured in situ. This will give sensitivity to WIMP-nucleon cross sections of 1.2 × 10 -47 cm 2 (1.1 × 10 -46 cm 2 ) for WIMPs of 1 TeV/c 2 (10 TeV/c 2 ) mass, to be achieved during a 5 yr run producing an exposure of 100 t yr free from any instrumental background. DarkSide-20k could then extend its operation to a decade, increasing the exposure to 200 t yr, reaching a sensitivity of 7.4 × 10 -48 cm 2 (6.9 × 10 -47 cm 2 ) for WIMPs of 1 TeV/c 2 (10 TeV/c 2 ) mass.
We report on the cryogenic characterization of Red Green Blue -High Density (RGB-HD) SiPMs develo... more We report on the cryogenic characterization of Red Green Blue -High Density (RGB-HD) SiPMs developed at Fondazione Bruno Kessler (FBK) as part of the DarkSide program of dark matter searches with liquid argon time projection chambers. A cryogenic setup was used to operate the SiPMs at varying temperatures and a custom data acquisition system and analysis software were used to precisely characterize the primary dark noise, the correlated noise, and the gain of the devices. We demonstrate that FBK RGB-HD SiPMs with low quenching resistance (RGB-HD-LR q ) can be operated from 40 K to 300 K with gains in the range 10 5 to 10 6 and noise rates at a level of around 1 Hz/mm 2 .
The design and optimization of photobioreactors for intensive microalgal cultures are key issues ... more The design and optimization of photobioreactors for intensive microalgal cultures are key issues to increase process performance. A model to assess the photosynthetic performance of tubular, bubble column and flat photobioreactors is presented. The model has coupled microalgal light distribution, photosynthesis kinetics and gas-liquid hydrodynamics. A lumped kinetic parameter model of photosynthetic unit (PSU) has been adopted for photosynthetic reactions. The dynamics of a microalgal cell has been described according to the gas-liquid flow of a bubble column. The flow field induced by liquid turbulence and bubbles uprising throughout the photobioreactor have been simulated with ANSYS-FLUENT. A representative domain of the flat photobioreactor has been selected by adopting proper periodic boundary conditions. Turbulence dispersion fields have been assessed by numerical simulations for several bubble size. A random-walk model developed in MATLAB has been adopted to microalgal cells to assess the irradiance experienced by the PSU-cell in the photobioreactors. The photobioreactor performances -expressed in terms of global photosynthesis rate -have been assessed. Irradiance level and biomass concentration have been changed in the range of operating conditions typically adopted for known processes.
Particle receivers are gaining much interest mainly for their potential of high temperature opera... more Particle receivers are gaining much interest mainly for their potential of high temperature operation and as thermal energy storage Dense gas-solid suspensions thanks to their excellent thermal properties RECEIVER: Collection of highly concentrated (100-1000 suns) incident solar radiation EXCHANGE: heat transfer to the working fluid of the thermodynamic cycle STORAGE: thermal energy for equalizing the inherent timevariability of the incident solar radiation System optimized to accomplish three complementary tasks: Challenge: compartmented fluidization without physical confinements just by partitioning of the fluidizing gas to a compartmented distributor to preserve the fluidized bed thermal properties Conclusions
A study on the hydrodynamics in gas-solid fluidized beds where the primary gas injection is achie... more A study on the hydrodynamics in gas-solid fluidized beds where the primary gas injection is achieved through a nozzle-type gas distributor has been carried out, using an innovative X-ray imaging technique. Qualitative and quantitative results are reported, with particular regards to the jet penetration length. Results show that the lighter and the finer are the particles, the larger is the jet penetration. A new non-dimensional correlation is proposed, since the experimental data do not match predictions available in literature, based on hydrodynamic scaling and Froude number. The new correlation takes into account the effects of jet velocity, particle density and particle size. A tentative mechanistic explanation for the departure from purely hydrodynamic scaling is offered.
The unceasing concern for climate change, closely related to the exploitation of fossil fuels, pu... more The unceasing concern for climate change, closely related to the exploitation of fossil fuels, pushes the scientific community to develop new technologies for CO 2 capture and utilization (CCU). Moreover, the growth and diffusion of solar energy requires new energy storage systems that put solar fuels at the forefront. Methane seems to be a suitable energy vector, which could both store solar energy and exploit fossil fuel derived CO 2 . Moreover, methane has the main advantage of an already existing distribution and storage infrastructure. The methanation reaction from hydrogen and carbon dioxide (or monoxide) is generally carried out in staged adiabatic catalytic fixed beds operated at high pressure in order to overcome thermodynamic limitations. A recently proposed alternative pathway is the sorptionenhanced methanation concept, which is based on the employment of a sorbent able to capture in situ the H 2 O produced during reaction, to shift equilibrium towards the formation of CH 4 . In this work a CaO, derived from natural limestone, and a commercial 3A Zeolite were tested as sorbent materials for H 2 O capture in a new configuration for the sorption-enhanced methanation based on the concept of chemical looping in dual interconnected fluidized bed systems. The experimental campaign was aimed at studying the sorbent performance in terms of hydration and dehydration at different operating conditions relevant for catalytic methanation. The results showed that CaO has a good capacity to capture and release steam in the temperature range of interest. Unfortunately, even at the lowest temperatures tested, the sorbent is affected by the presence of CO 2 , which worsens its performance in terms of H 2 O capture capacity. The zeolite has a more stable behavior than CaO under all investigated conditions. Comparing the performance of the two materials, the zeolite on average has better capture capacity (0.017-0.049 g/g) than CaO (0.006-0.025 g/g) and it is not affected by deactivation during the cycles.
Environmental Engineering and Management Journal, 2013
The preliminary assessment of a cost-effective flow-sheet for the production of biodiesel from mi... more The preliminary assessment of a cost-effective flow-sheet for the production of biodiesel from microalgae lipid fraction was carried out. The study was based on approximated cost-estimation methods integrated with the simulation software Aspen Plus ® . Several scenarios were investigated to compare costs regarding the main steps of the biodiesel production process. Ranges of input variables from downstream literature and experimental data were used to simulate the sections that define concrete process routes for production of algal biofuels: the extraction of the lipid fraction from aqueous solution, the lipid transesterification, and the methyl esters (FAMEs) and glycerol recover. The design variables were selected so as to correspond to the main degrees of freedom of the process: number of equilibrium stages, solvent recycle flow rate, transesterification time, methanol to triacylglycerols ratio, plate number and reflux ratio of the distillation unit for methanol recovery. The cost estimation for the conceptual design of the flowsheet dedicated to the FAMEs production from microalgae was carried out according to Happel's method. Data were worked out to assess the venture profit and the selling price (s) for mass unit of FAMEs. The minimization of s was adopted as the objective function. A preliminary determination of plausible values of the cost for unit of mass of biodiesel was attempted as a function of operating conditions.
An appropriate hydrodynamic model of the whole system in order to point out "stable" operating co... more An appropriate hydrodynamic model of the whole system in order to point out "stable" operating conditions. Most of numerical simulations of CLR in DIFB are focused only on kinetic scheme
Background: Succinic acid is one of the most interesting platform chemicals that can be produced ... more Background: Succinic acid is one of the most interesting platform chemicals that can be produced in a biorefinery approach. In this study, continuous succinic acid production by Actinobacillus succinogenes fermentation in a packedbed biofilm reactor (PBBR) was investigated. The effects of the operating conditions tested, dilution rate (D), and medium composition (mixture of glucose, xylose, and arabinose-that simulate the composition of a lignocellulosic hydrolysate)-on the PBBR performances were investigated. The maximum succinic acid productivity of 35.0 g L -1 h -1 and the maximum SA concentration were achieved at a D = 1.9 h -1 . The effect of HMF and furfural on succinic acid production was also investigated. HMF resulted to reduce succinic acid production by 22.6%, while furfural caused a reduction of 16% in SA production at the same dilution rate. Conclusion: Succinic acid production by A. succinogenes fermentation in a packed-bed reactor (PBBR) was successfully carried out for more than 5 months. The optimal results were obtained at the dilution rate 0.5 h -1 : 43.0 g L -1 of succinic acid were produced, glucose conversion was 88%; and the volumetric productivity was 22 g L -1 h -1 .
Nuovo Cimento Della Societa Italiana Di Fisica A-nuclei Particles and Fields, 2017
DarkSide is a dark matter direct search experiment at Laboratori Nazionali del Gran Sasso (LNGS).... more DarkSide is a dark matter direct search experiment at Laboratori Nazionali del Gran Sasso (LNGS). DarkSide is based on the detection of rare nuclear recoils possibly induced by hypothetical dark matter particles, which are supposed to be neutral, massive (m > 10 GeV) and weakly interactive (WIMP). The dark matter detector is a two-phase time projection chamber (TPC) filled with ultra-pure liquid argon. The TPC is placed inside a muon and a neutron active vetoes to suppress the background. Using argon as active target has many advantages, the key features are the strong discriminant power between nuclear and electron recoils, the spatial reconstruction and easy scalability to multi-tons size. At the moment DarkSide-50 is filled with ultra-pure argon, extracted from underground sources, and from April 2015 it is taking data in its final configuration. When combined with the preceding search with an atmospheric argon target, it is possible to set a 90% CL upper limit on the WIMP-nuc...
DarkSide uses a dual-phase Liquid Argon Time Projection Chamber (TPC) to search for WIMP dark mat... more DarkSide uses a dual-phase Liquid Argon Time Projection Chamber (TPC) to search for WIMP dark matter. The paper will present the latest result on the search for low mass ($M_{WIMP} 100\,Gev/c^2$) WIMPs from the current experiment, DarkSide-50, running since mid 2015 a 50-kg-active-mass TPC, filled with argon from an underground source. The next stage of the DarkSide program will be a new generation experiment involving a global collaboration from all the current Argon based experiments. DarkSide-20k, is designed as a 20-tonne fiducial mass TPC with SiPM based photosensors, expected to be free of any background for an exposure of >100 ton x years. Like its predecessor DarkSide-20k will be housed at the Gran Sasso (LNGS) underground laboratory, and it is expected to attain a WIMP-nucleon cross section exclusion sensitivity of $10^{-47}\,cm^2$ for a WIMP mass of $1\,TeV/c^2$ in a 5 yr run. A subsequent objective, towards the end of the next decade, will be the construction of the ul...
Journal of Cosmology and Astroparticle Physics, 2021
Future liquid-argon DarkSide-20k and Argo detectors, designed for direct dark matter search, will... more Future liquid-argon DarkSide-20k and Argo detectors, designed for direct dark matter search, will be sensitive also to core-collapse supernova neutrinos, via coherent elastic neutrino-nucleus scattering. This interaction channel is flavor-insensitive with a high-cross section, enabling for a high-statistics neutrino detection with target masses of ∼50 t and ∼360 t for DarkSide-20k and Argo respectively. Thanks to the low-energy threshold of ∼0.5 keVnr achievable by exploiting the ionization channel, DarkSide-20k and Argo have the potential to discover supernova bursts throughout our galaxy and up to the Small Magellanic Cloud, respectively, assuming a 11-M☉ progenitor star. We report also on the sensitivity to the neutronization burst, whose electron neutrino flux is suppressed by oscillations when detected via charged current and elastic scattering. Finally, the accuracies in the reconstruction of the average and total neutrino energy in the different phases of the supernova burst,...
Proportional electroluminescence (EL) in noble gases is used in two-phase detectors for dark matt... more Proportional electroluminescence (EL) in noble gases is used in two-phase detectors for dark matter searches to record (in the gas phase) the ionization signal induced by particle scattering in the liquid phase. The “standard” EL mechanism is considered to be due to noble gas excimer emission in the vacuum ultraviolet (VUV). In addition, there are two alternative mechanisms, producing light in the visible and near infrared (NIR) ranges. The first is due to bremsstrahlung of electrons scattered on neutral atoms (“neutral bremsstrahlung”, NBrS). The second, responsible for electron avalanche scintillation in the NIR at higher electric fields, is due to transitions between excited atomic states. In this work, we have for the first time demonstrated two alternative techniques of the optical readout of two-phase argon detectors, in the visible and NIR range, using a silicon photomultiplier matrix and electroluminescence due to either neutral bremsstrahlung or avalanche scintillation. The...
Aria is a plant hosting a$${350}\,\hbox {m}$$350mcryogenic isotopic distillation column, the tall... more Aria is a plant hosting a$${350}\,\hbox {m}$$350mcryogenic isotopic distillation column, the tallest ever built, which is being installed in a mine shaft at Carbosulcis S.p.A., Nuraxi-Figus (SU), Italy. Aria is one of the pillars of the argon dark-matter search experimental program, lead by the Global Argon Dark Matter Collaboration. It was designed to reduce the isotopic abundance of$${^{39}\hbox {Ar}}$$39Arin argon extracted from underground sources, called Underground Argon (UAr), which is used for dark-matter searches. Indeed,$${^{39}\hbox {Ar}}$$39Aris a$$\beta $$β-emitter of cosmogenic origin, whose activity poses background and pile-up concerns in the detectors. In this paper, we discuss the requirements, design, construction, tests, and projected performance of the plant for the isotopic cryogenic distillation of argon. We also present the successful results of the isotopic cryogenic distillation of nitrogen with a prototype plant.
The high temperatures and heating rates typical of PF are known to induce thermal annealing of ch... more The high temperatures and heating rates typical of PF are known to induce thermal annealing of char and loss of its reactivity. Several authors investigated this effect for coals in inert atmospheres, while little is known about the effects of CO 2 rich atmospheres, typical of oxycombustion and gasification, on the course of thermal annealing. Thermal annealing of biomass has been scarcely investigated in the literature, however available studies reported that also biomass can suffer from thermodeactivation. The present study aims to provide further insight on thermal annealing of biomass in the context of gasification and oxy-combustion. A lignin rich biomass (Walnut shells) has been heat treated in a heated strip reactor (HSR) at temperatures of 1573-2073 K with a holding time of 3 s using atmospheres of either N 2 or CO 2 . Similar experiments have been performed with a high volatile bituminous coal (Colombian coal) used as reference. The char samples have been analyzed by thermogravimetric analysis and Raman spectroscopy. Results have been further compared with those reported in previous studies where heat treatment of the same fuels were performed in fixed bed, fluidized bed and drop tube reactors at lower temperature or shorter holding time.
The biosynthesis of poly-β-hydroxybutyrate (PHB) by bioconversion of CO 2 is a sustainable altern... more The biosynthesis of poly-β-hydroxybutyrate (PHB) by bioconversion of CO 2 is a sustainable alternative to the non-renewable, petroleum-based polymer production. Indeed, the PHB production by conversion of CO 2 contributes to the reduction of the greenhouse-gas concentration in the atmosphere. A kinetic dynamic model of PHB production by autotrophic cultures of Synechocystis PCC6803 was proposed and developed by means of the biochemical networks simulator COPASI. Two classes of cells were assumed to be present in the broth: growing cells, PHB producing cells. The model included the two classes of cells and their nitrogen and phosphate internal quota. The dynamics of the cell growth and PHB production were described taking into account: cellular growth rate; lysis rate; nitrate and phosphate utilization rate; PHB production rate. The assessment of the kinetic parameters and of the yields (model calibration) was carried out by the regression of experimental data. Tests were carried out in photobioreactors under dynamic light system (light/dark cycle) using media characterized by initial nitrate concentration ranging between 0 and 1.5 g/L. The developed model was validated with respect to independent experimental set. The proposed model successfully reproduced the experimental data (cell concentration, nitrogen and phosphate concentration and PHB content): the square correlation coefficient of the investigated variable concentrations ranged between 0.81 and 0.99. Parameter sensitivity analysis was carried out to assess the role of the selected parameters on cell growth and PHB accumulation. The dynamics of cellular growth were not significantly affected by a ± 20% variation of maximum specific growth rate, of velocity of conversion to PHB producing cells, and of maximum uptake rate of nitrate. The PHB accumulation dynamics were particularly sensitive to the variation of the value of the investigated parameters. The proposed model may support the design and the optimization of a PHB production process by means of autotrophic cultures.
In this work, after a briefly excursus on two models of academic "learning contexts", the experie... more In this work, after a briefly excursus on two models of academic "learning contexts", the experience underway at the University of Naples Federico II is described. The path from a FabLab 1.0 born on the field, by spontaneous initiative of some teachers and students, towards a new structured and institutional learning is described. This new FabLab 2.0 constitutes an opportunity, based on the international experiences of "FabLab" and "Learning Factory", of facing the educational challenges posed by the transition to the context of "Industry 4.0".
Building on the successful experience in operating the DarkSide-50 detector, the Dark-Side Collab... more Building on the successful experience in operating the DarkSide-50 detector, the Dark-Side Collaboration is going to construct DarkSide-20k, a direct WIMP search detector using a two-phase Liquid Argon Time Projection Chamber (LAr TPC) with an active (fiducial) mass of 23 t (20 t). The DarkSide-20k LAr TPC will be deployed within a shield/veto with a spherical Liquid Scintillator Veto (LSV) inside a cylindrical Water Cherenkov Veto (WCV). Operation of DarkSide-50 demonstrated a major reduction in the dominant 39 Ar background when using argon extracted from an underground source, before applying pulse shape analysis. Data from DarkSide-50, in combination with MC simulation and analytical modeling, shows that a rejection factor for discrimination between electron and nuclear recoils of >3 × 10 9 is achievable. This, along with the use of the veto system, is the key to unlocking the path to large LAr TPC detector masses, while maintaining an "instrumental background-free" experiment, an experiment in which less than <0.1 events (other than ν-induced nuclear recoils) is expected to occur within the WIMP search region during the planned exposure. DarkSide-20k will have ultra-low backgrounds than can be measured in situ. This will give sensitivity to WIMP-nucleon cross sections of 1.2 × 10 -47 cm 2 (1.1 × 10 -46 cm 2 ) for WIMPs of 1 TeV/c 2 (10 TeV/c 2 ) mass, to be achieved during a 5 yr run producing an exposure of 100 t yr free from any instrumental background. DarkSide-20k could then extend its operation to a decade, increasing the exposure to 200 t yr, reaching a sensitivity of 7.4 × 10 -48 cm 2 (6.9 × 10 -47 cm 2 ) for WIMPs of 1 TeV/c 2 (10 TeV/c 2 ) mass.
We report on the cryogenic characterization of Red Green Blue -High Density (RGB-HD) SiPMs develo... more We report on the cryogenic characterization of Red Green Blue -High Density (RGB-HD) SiPMs developed at Fondazione Bruno Kessler (FBK) as part of the DarkSide program of dark matter searches with liquid argon time projection chambers. A cryogenic setup was used to operate the SiPMs at varying temperatures and a custom data acquisition system and analysis software were used to precisely characterize the primary dark noise, the correlated noise, and the gain of the devices. We demonstrate that FBK RGB-HD SiPMs with low quenching resistance (RGB-HD-LR q ) can be operated from 40 K to 300 K with gains in the range 10 5 to 10 6 and noise rates at a level of around 1 Hz/mm 2 .
The design and optimization of photobioreactors for intensive microalgal cultures are key issues ... more The design and optimization of photobioreactors for intensive microalgal cultures are key issues to increase process performance. A model to assess the photosynthetic performance of tubular, bubble column and flat photobioreactors is presented. The model has coupled microalgal light distribution, photosynthesis kinetics and gas-liquid hydrodynamics. A lumped kinetic parameter model of photosynthetic unit (PSU) has been adopted for photosynthetic reactions. The dynamics of a microalgal cell has been described according to the gas-liquid flow of a bubble column. The flow field induced by liquid turbulence and bubbles uprising throughout the photobioreactor have been simulated with ANSYS-FLUENT. A representative domain of the flat photobioreactor has been selected by adopting proper periodic boundary conditions. Turbulence dispersion fields have been assessed by numerical simulations for several bubble size. A random-walk model developed in MATLAB has been adopted to microalgal cells to assess the irradiance experienced by the PSU-cell in the photobioreactors. The photobioreactor performances -expressed in terms of global photosynthesis rate -have been assessed. Irradiance level and biomass concentration have been changed in the range of operating conditions typically adopted for known processes.
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Papers by Piero Salatino