Calorimetric Events Research Articles

Clustering in the Heterogeneous Reconstruction Chain of the CMS HGCAL Detector

We present an important milestone for the CMS High Granularity Calorimeter (HGCAL) event reconstruction: the deployment of the GPU clustering algorithm (CLUE) to the CMS software. The connection between GPU CLUE and the preceding GPU calibration step is thus made possible, further extending the heterogeneous chain of HGCAL’s reconstruction framework. In addition to improvements brought by CLUE’s deployment, new recursive device kernels are added to efficiently calculate the position and energy of CLUE clusters. Data conversions between GPU and CPU are included to facilitate the validation of the algorithms and increase the flexibility of the reconstruction. For the first time in HGCAL, conditions data are deployed to the GPU and made available on demand at any stage of the heterogeneous reconstruction. This is achieved via a new geometry ordering scheme in which physical and memory locations are connected. This scheme is successfully tested with the GPU CLUE version reported here, and is expected to have a broad range of applicability for future heterogeneous developments in CMS. Finally, the performance of the combined calibration and clustering algorithms on GPU is assessed and compared to its CPU counterpart.

Probing calorimetric heat transfer phenomena in multi-nanophase substances: A case study of some over-stoichiometric nanoarsenicals

Thermochemical events recognized from heat flux DSC measurements involving dynamic and progressive step-cycling are identified in multi-nanophase substances exemplified by melt-quenched and nanomilling-derived AsxS100-x arsenicals enriched in As over As4S3 composition (As60S40, As62S38, As64S36). Thermal-alteration heat transfer in these alloys composed of normal- and plastic-crystalline phases supplemented by dual-nature amorphous substance are complicated by transformations in nanocrystalline dimorphite-type As4S3 and realgar-type As4S4 phases. Primary calorimetric events in the examined nanoarsenicals are shown to be as follows: (i) reduction in onset temperature from normal- (α′-As4S3) to plastic-crystalline (β-As4S3) phase; (ii) depression in pre-melting temperature of β-As4S3 phase; (iii) decrease in decomposition temperature of dimorphite-type phase supplemented by appearance of realgar-type β-As4S4 and amorphous phase, (iv) increase in crystallization temperature of β-As4S3 phase; (v) high-temperature shift in relaxation from liquid to stabilized heterogeneous state. The multiphase occurrence of nanoarsenicals results in unexpected increase in some heat transfer events detected in reheating modes.

Thermal investigation of biodiesel blends derived from rapeseed oil

Over the last few years, the production of biodiesel from vegetable oil has significantly increased in Romania due to its obligatory use in the composition of diesel fuel. In this study, biodiesel from rapeseed oil was produced using methanol and a base catalyst. Four samples of biodiesel/diesel blends were prepared for analysis to determine the main thermal decomposition processes and calorimetric events. The thermal profiles were compared to reference diesel. The data obtained on the Thermogravimetry/Differential thermogravimetry and DTA curves show the quality of biodiesel/diesel blends and the possibility that the fuel be used in diesel engines. It was found that biodiesel blends with higher percentage of biodiesel in their compositions were more thermally stable than diesel fuel.

Thermogravimetric and calorimetric evaluation of babassu biodiesel obtained by the methanol route

The growing petroleum deficit requires the development of alternative fuel sources. Biodiesel is a good alternative, as it is a biodegradable and renewable product, which obeys the carbon cycle. In this work, the biodiesel from babassu was synthesized using the methanol route, and characterized by physico-chemical analyses in order to make able the investigated biodiesel to fulfill with its properties the requirements of Brazilian National Agency for Petroleum, Natural Gas and Biofuel (ANP). Besides gas chromatography, IR spectroscopy experiments and thermoanalytical measurements in air and in nitrogen were done to determine the main thermal decomposition processes and calorimetric events. The evaporation temperature of babassu biodiesel was similar in both atmospheres, started around 52 in air and around 60°C in nitrogen.

Rapid Assessment of the Structural Relaxation Behavior of Amorphous Pharmaceutical Solids: Effect of Residual Water on Molecular Mobility

Use RH-perfusion microcalorimetry and other analytical techniques to measure the interactions between water vapor and amorphous pharmaceutical solids; use these measurements and a mathematical model to provide a mechanistic understanding of observed calorimetric events. Isothermal microcalorimetry was used to characterize interactions of water vapor with a model amorphous system, spray-dried raffinose. Differential scanning calorimetry was used to measure glass transition temperature, T (g). High-sensitivity differential scanning calorimetry was used to measure enthalpy relaxation. X-ray powder diffraction (XRPD) was used to confirm that the spray-dried samples were amorphous. Scanning electron microscopy (SEM) was used to examine particle morphology. Gravimetric vapor sorption was used to measure moisture sorption isotherms. Thermogravimetric analysis (TGA) was used to measure loss on drying. A moisture-induced thermal activity trace (MITAT) provides a rapid measure of the dependence of molecular mobility on moisture content at a given storage temperature. At some relative humidity threshold, RH(m), the MITAT exhibits a dramatic increase in the calorimetric rate of heat flux. Simulations using calorimetric data indicate that this thermal event is a consequence of enthalpy relaxation. RH-perfusion microcalorimetry is a useful tool to determine the onset of moisture-induced physical instability of glassy pharmaceuticals and could find a broad application to determine appropriate storage conditions to ensure long-term physical stability. Remarkably, thermal events measured on practical laboratory timescales (hours to days) are relevant to the stability of amorphous materials on much longer, pharmaceutically relevant timescales (years). The mechanistic understanding of these observations in terms of enthalpy relaxation has added further value to the use of RH-perfusion calorimetry as a rapid means to characterize the molecular mobility of amorphous solids.

Local icosahedral symmetries in Al-Mo alloys prepared by ball milling

Annealing products of mechanically treated Al 75Mo 25 powders have been studied by X-ray powder diffraction with the Rietveld method. The differential scanning calorimetry traces of as-milled powders showed transformation features whose temperature decreased as a function of mechanical treatment time. Different phases were identified across the calorimetric events, which were also reported in the high-temperature phase diagram of the Al-Mo system, such as Al 12Mo, Al 5Mo, Al 4Mo, Al 3Mo and Al 22Mo 5. Nevertheless, the solid state transformation processes activated in the calorimeter at ambient pressure are of different nature with respect to those observed by means of neutron diffraction during in situ annealing under vacuum. In the specimen mechanically alloyed for 32 hours the Al 12Mo phase was observed after annealing with both processes. In the crystal geometry of Al 12Mo, which is regarded as a first order approximation of the quasi-crystalline phase, the molybdenum atoms are arranged in a BCC fashion and are surrounded icosahedrally by twelve aluminum atoms.

Bhabha scattering at LEP1: calorimeter event selection

Analytical calculations have been used to describe the calorimeter event selection in small-angle electron-positron scattering at LEP1. The first-order QED correction to the Born cross section has been derived with leading log and next-to-leading log approximations. The second- and third-order corrections are computed with leading accuracy. Our analytical results are given and compared with the corresponding results obtained with the use of the Monte Carlo generator BHLUMI.

Small-angle Bhabha scattering at LEP1. Analytical results for wide-narrow angular acceptance

Analytical formulae for small-angle Bhabha scattering cross-section at LEP1 are given for the case of wide-narrow angular acceptance. Inclusive and calorimeter event selections are considered. Numerical results are presented.

Calorimeter event selection for small-angle Bhabha scattering at LEP1

An analytical method is applied for description of calorimeter event selection in small-angle electron-positron scattering at LEP1. The selections CALO1 and CALO2 are investigated specifically. The first-order correction to the Born cross section is given in the case of wide-narrow angular acceptance.

Perturbation of the chain melting transition of DPPC by galactose, agarose and Laurdan as determined by differential scanning calorimetry

Differential scanning calorimetry was used to determine the effects of agarose hydrogel, galactose and the fluorophore Laurdan on the thermal behavior of multilamellar liposomes of DPPC. Although the effect of agarose on the phase transition was found to be negligible at low concentrations (≦ 2.5%), higher concentrations results in an endotherm that broadens and splits into two calorimetric events, one of which is at a higher temperature than that of hydrated DPPC. Equal weight fractions of galactose produce similar effects, although both fractions have raised melting temperatures. The higher melting components may be produced by osmotically-driven dehydration of the inner liposomal monolayers, a physical interaction between the carbohydrates and lipid headgroups, or a combination of both. Laurdan has little effect on the phase transition of DPPC vesicles at the concentration used in the sensor (0.67 mol%); concentrations up to 5.4 mol% only slightly lowered the melting temperature.

Thermal effects associated with stress-induced martensitic transformation in a TiNi alloy

Stress-induced martensitic transformation in a polycrystalline TiNi alloy (Ti-50.1 at.%Ni) has been investigated by following the instantaneous temperature change during deformation, the effects of strain rate on the kinetics of transformation and the calorimetric effects associated with the thermally induced transformation. Two separate stages of transformation strain and temperature increment are observed during stress-induced martensitic transformation in this alloy. Differential scanning calorimetry results show two exothermic peaks during cooling. The sum of the enthalpy changes for these two events is exactly equal to the single enthalpy change during martensite-to-parent transformation. It is proposed that the two stages of transformation strain and temperature rise during stress-induced transformation are related to the two calorimetric events in thermally induced transformation. It is shown that the stress-strain hysteresis loop as well as the two stages of temperature rise are influenced by the strain rate.