Showing papers on "Calorimeter published in 2008"

Determination of the enthalpy of PCM as a function of temperature using a heat-flux DSC—A study of different measurement procedures and their accuracy

Abstract: Thermal energy storage by latent heat allows storing high amounts of energy working in narrow margins of temperature. The use of phase change material (PCM) for the latent heat storage has been studied in different applications and it has been commercialized in containers to transport blood, products sensible to temperature, to decrease their energy demand. The use of PCM in cooling and refrigeration has been attracting a lot of interest lately, but for all applications, the properties of these materials need to be known with sufficient accuracy. Regarding heat storage, it is necessary to know the enthalpy as a function of temperature. The most widely used calorimeter is the heatflux differential scanning calorimetry (hf-DSC). The objective of this study is to investigate different methods for hf- DSC analysis, namely the dynamic method and the step method, and to test their accuracy in the determination of enthalpy–temperature relationship of PCM. For the dynamic method, a strong influence of heating/cooling rate was observed. For the step method, the resulting enthalpy–temperature relationship is independent of heating/cooling rate. Commercial PCM RT27 was chosen as sample material to avoid subcooling and kinetic effects in the test measurements. The approach introduced in this study can be used to carry out similar investigations for other classes of PCM and/or other DSC instruments.

The ATLAS Level-1 Calorimeter Trigger

Abstract: The ATLAS Level-1 Calorimeter Trigger uses reduced-granularity information from all the ATLAS calorimeters to search for high transverse-energy electrons, photons, τ leptons and jets, as well as high missing and total transverse energy. The calorimeter trigger electronics has a fixed latency of about 1 μs, using programmable custom-built digital electronics. This paper describes the Calorimeter Trigger hardware, as installed in the ATLAS electronics cavern.

Design and electronics commissioning of the physics prototype of a si-w electromagnetic calorimeter for the international linear collider

Abstract: 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 cm2 and a pad size of 1 × 1 cm2. 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-over-noise 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.

Design, performance, and calibration of CMS forward calorimeter wedges

Abstract: We report on the test beam results and calibration methods using high energy electrons, pions and muons with the CMS forward calorimeter (HF). The HF calorimeter covers a large pseudorapidity region (\(3\leq|\eta|\leq5\)), and is essential for a large number of physics channels with missing transverse energy. It is also expected to play a prominent role in the measurement of forward tagging jets in weak boson fusion channels in Higgs production. The HF calorimeter is based on steel absorber with embedded fused-silica-core optical fibers where Cherenkov radiation forms the basis of signal generation. Thus, the detector is essentially sensitive only to the electromagnetic shower core and is highly non-compensating (e/h≈5). This feature is also manifest in narrow and relatively short showers compared to similar calorimeters based on ionization. The choice of fused-silica optical fibers as active material is dictated by its exceptional radiation hardness. The electromagnetic energy resolution is dominated by photoelectron statistics and can be expressed in the customary form as \(\frac{a}{\sqrt{E}}\oplus{b}\). The stochastic term a is 198% and the constant term b is 9%. The hadronic energy resolution is largely determined by the fluctuations in the neutral pion production in showers, and when it is expressed as in the electromagnetic case, a = 280% and b = 11%.

Microcombustion calorimetry as a tool for screening flame retardancy in epoxy

Abstract: Through the use of microcombustion calorimetry several polymer nanocomposite, flame retardant (FR), and polymer nanocomposite + FR systems were screened for flammability performance. The use of this technique allowed for the creation of small batch (less than 50 g) epoxy formulations as compared to 400–500 g needed for cone calorimeter testing of epoxy + fiberglass panels. The results from the microcombustion calorimeter screening suggested that the system with the best flammability performance was a combination of organophosphonate and zinc borate, and not one of the polymer nanocomposite systems. This best candidate was then scaled up and fabricated into a fiberglass-reinforced composite which was further tested by a cone calorimeter. This paper shows some of the correlations between the microcombustion and cone calorimeter results for this single sample, provides some reasons for why the polymer nanocomposite samples did not provide the best results in flammability reduction, and suggests some caveats when using microcombustion calorimetry as the only screening tool for flammability. Copyright © 2008 John Wiley & Sons, Ltd.

Laser monitoring system for the CMS lead tungstate crystal calorimeter

Abstract: We report on the multiple wavelength laser monitoring system designed for the compact muon solenoid (CMS) lead tungstate crystal calorimeter. Results are presented for the test-beam performance of the system designed to achieve ⩽0.2% relative optical transmittance inter-calibration for 75 848 lead tungstate crystals. The system cycles continuously over the calorimeter to follow each crystal's evolution under the irradiation and recovery periods foreseen during operation at the LHC.

Hazard ratings for organic peroxides

Abstract: Nine of commercially available organic peroxides were assessed with differential scanning calorimeter (DSC) and adiabatic calorimeters. These organic peroxides are cumene hydroperoxide (CHP), di-tert-butyl peroxide (DTBP), methyl-ethyl-ketone peroxide (MEKPO), tert-butyl hydroperoxide (TBHP), benzoyl peroxide (BPO), hydrogen peroxide, lauroyl peroxide (LPO), tert-butyl peroxybenzoate (TBPBZ), and dicumyl peroxide (DCPO). Exothermic onset temperatures, self-heat temperature and pressure rates, and heats of decomposition were measured and assessed. Adiabatic runaway reaction characteristics were determined by using ARC (accelerating rate calorimeter) and VSP2 (vent sizing package). Incompatibility, tests with several potential contaminants, was made using DSC, VSP2, and microcalorimeter. An incompatibility rating was developed using onset temperature, lowering of the onset temperature, heat of decomposition, maximum self-heat rate, adiabatic temperature rise, maximum pressure of decomposition, and maximum pressure rising rate, etc. © 2008 American Institute of Chemical Engineers Process Saf Prog 2008

The ATLAS Forward Calorimeter

Abstract: Forward calorimeters, located near the incident beams, complete the nearly 4π coverage for high pT particles resulting from proton-proton collisions in the ATLAS detector at the Large Hadron Collider at CERN. Both the technology and the deployment of the forward calorimeters in ATLAS are novel. The liquid argon rod/tube electrode structure for the forward calorimeters was invented specifically for applications in high rate environments. The placement of the forward calorimeters adjacent to the other calorimeters relatively close to the interaction point provides several advantages including nearly seamless calorimetry and natural shielding for the muon system. The forward calorimeter performance requirements are driven by events with missing ET and tagging jets.

Densities, Viscosities, and Heat Capacities of Ammonia + Lithium Nitrate and Ammonia + Lithium Nitrate + Water Solutions between (293.15 and 353.15) K

Abstract: The density, dynamic viscosity, and heat capacity of ammonia + lithium nitrate and ammonia + lithium nitrate + water mixtures were measured between (293.15 and 353.15) K at 1.8 MPa, using a vibrating-tube densimeter, a piston-style viscosimeter, and a heat flux Calvet-type calorimeter, respectively. The measured data were correlated as a function of temperature and composition using simple polynomial equations. Kinematic viscosity data of binary and ternary mixtures were also determined.

Chip calorimetry and its use for biochemical and cell biological investigations

Abstract: The presented paper analyzes the potential of chip calorimetry for biochemical and cell biological investigations. From the thermo-physical properties of the heat power detectors of a chip calorimeter can be deduced that relevant applications mainly refer to fast reactions in extremely small samples. In contrast, the use of chip calorimeters for studying slow processes such as biochemical or microbial reactions is restricted. However, careful optimization of chip calorimeters concerning signal resolution and sample volume enables the investigation of enzymatically catalyzed reactions and the measurement of microbial growth heat as subsequently demonstrated with some typical examples from the literature.

Improvement of High Heat Flux Measurement Using a Null-Point Calorimeter

Abstract: K ENNEDYet al.first proposed transient heatfluxmeasurements using swept null-point calorimetry in 1972 [1]. They published a copper sensor design, the form of which is still in use. It is shown in Fig. 1. The interior design of the sensor is shown in Fig. 2. The heat flux is estimated from a temperature measurement. The location of the temperature measurement is chosen such that the null-point scenario is given [2,3]. This means that the measured temperature history at the backside, i.e., the null point, is assumed to be identical to the surface temperature history. Then, the temperature at the null point can be inserted into a one-dimensional inverse heat conduction problem for a semi-infinite solid to determine the heat flux at the surface. The theoretical assumption of one-dimensional and linear heat conduction is strengthened by an appropriate sensor design (see Fig. 2). Because of the high enthalpy flow condition, the essentially uncooled sensors have to be passed very quickly across the flow diameter. The sensors in the current configuration are moved with a velocity of 1 m=s across the flow. Considering the plasma flow diameter of about 30mm, one heat fluxmeasurement is performed in 0.03 s, which is about half the time the sensor is supposed to be used [1,4]. However, the recorded temperature profile allows to deduce the heat flux along the measured direction, i.e., perpendicular to the flow axis, which is the radial profile. For the temperaturemeasurement itself, there are historically three different approaches: coaxial surface thermocouples, thin-film resistance thermometers, and null-point calorimeters. As mentioned, the fundamental assumption in the heat flux estimation using such devices is that of linear one-dimensional heat conduction. If a homogeneous temperature between the probe surface and the measurement location during the experiment can be assumed, the thin-film theory is applied and the heat diffusion problem can be solved analytically [5]. In contrast, the thick-film theorymeans that it is assumed that the temperature at the opposite end of the surface which is exposed to the heat flux rests constant throughout the experiment, which corresponds to semi-infinite behavior and leads also to an analytical solution. Usually, the thin-film theory is applied to resistance thermometers and the thick-film theory to surface thermocouples and null-point calorimeters. To characterize the plasma flow, the radial profile of heat flux has to be measured, which is only applicable to sensors according to the thick-film theory [4]. However, as will be shown later, the especially short measurement times lead to the conclusion that the one-dimensional conditions are no longer valid. Moreover, the thermocouple’s junction never reaches a homogeneous temperature level during exposure time, which means that the measured signal, that is a voltage drop, cannot be related to the junction temperature using the thermoelectric calibration as it is proposed up to now. Hence, this well-known measurement technique has to be further investigated to adapt it to Received 27 March 2007; revision received 8 October 2007; accepted for publication 22 October 2007. Copyright © 2007 by the authors. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. Copies of this paper may be made for personal or internal use, on condition that the copier pay the $10.00 per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923; include the code 0022-4650/08 $10.00 in correspondence with the CCC. ∗Research Engineer, Laboratoire TREFLE, Esplanade des arts et metiers, 33405 Talence; stefan.loehle@dlr.de. Member AIAA. Professor, Laboratoire TREFLE. Research Engineer, Avenue du General Niox. Research Engineer, Route des Gargails. JOURNAL OF SPACECRAFT AND ROCKETS Vol. 45, No. 1, January–February 2008

Indirect measurement of the magnetocaloric effect using a novel differential scanning calorimeter with magnetic field.

Abstract: A simple and high-sensitivity differential scanning calorimeter (DSC) unit operating under magnetic field has been built for indirect determination of the magnetocaloric effect. The principle of the measuring unit in the calorimeter is based on Peltier elements as heat flow sensors. The high sensitivity of the apparatus combined with a suitable calibration procedure allows very fast and accurate heat capacity measurements under magnetic field to be made. The device was validated from heat capacity measurements for the typical DSC reference material gallium (Ga) and a La0.67Ca0.33MnO3 manganite system and the results were highly consistent with previous reported data for these materials. The DSC has a working range from 200 to 340 K and has been tested in magnetic fields reaching 1.8 T. The signal-to-noise ratio is in the range of 102–103 for the described experiments. Finally the results have been compared to results from a Quantum Design® physical properties measuring system. The configuration of the sys...

A fully automated adiabatic calorimeter for heat capacity measurement between 80 and 400 K

Abstract: A fully automated adiabatic calorimeter controlled on line by a computer used for heat capacity measurements in the temperature range from 80 to 400 K was constructed. The hardware of the calorimetric system consisted of a Data Acquisition/Switch Unit, 34970A Agilent, a 7 1/2 Digit Nano Volt /Micro Ohm Meter, 34420A Agilent, and a P4 computer. The software was developed according to modern controlling theory. The adiabatic calorimeter consisted mainly of a sample cell equipped with a miniature platinum resistance thermometer and an electric heater, two (inner and outer) adiabatic shields, two sets of six junction differential thermocouple piles and a high vacuum can. A Lake Shore 340 Temperature Controller and the two sets of differential thermocouples were used to control the adiabatic conditions between the cell and its surroundings. The reliability of the calorimeter was verified by measuring the heat capacities of synthetic sapphire (α-Al2O3), Standard Reference Material 720. The deviation of the data obtained by this calorimeter from those published by NIST was within ±0.1% in the temperature range from 80 to 400 K.

Design and implementation of the Front End Board for the readout of the ATLAS liquid argon calorimeters

Abstract: The ATLAS detector has been designed for operation at CERN's Large Hadron Collider. ATLAS includes a complex system of liquid argon calorimeters. The electronics for amplifying, shaping, sampling, pipelining, and digitizing the calorimeter signals is implemented on the Front End Boards (FEBs). This paper describes the design, implementation and production of the FEBs and presents measurement results from testing performed at several stages during the production process.

ATLAS liquid argon calorimeter front end electronics

Abstract: The ATLAS detector has been designed for operation at CERN's Large Hadron Collider. ATLAS includes a complex system of liquid argon calorimeters. This paper describes the architecture and implementation of the system of custom front end electronics developed for the readout of the ATLAS liquid argon calorimeters.

Advanced kinetics-based simulation of time to maximum rate under adiabatic conditions

Abstract: An adiabatic calorimeter is very often used for the investigation of runaway of exothermic reactions However the ideal adiabatic environment is a theoretical state which during laboratory scale testing cannot be obtained but may only be approached Deviation from the fully adiabatic state comes from (i) the thermal inertia of the test system or heat lost into the sample container and (ii) the loss of heat from the container itself to the environment that reflects the ‘operational adiabaticity’ of the instrument In addition to adiabatic testing, advanced kinetic approach based on the kinetic parameters determined from DSC data performed under different heating rates can be applied It enables to simulate what may happen on a large scale by testing and up-scaling results obtained with a small amount of the sample

An Improved Shashlyk Calorimeter

Abstract: Shashlyk electromagnetic calorimeter modules with an energy resolution of about 3 % / E ( GeV ) for 50 – 1000 MeV photons have been developed, and a prototype tested. Details of these improved modules, including mechanical construction, selection of wave shifting fibers and photo-detectors, and development of a new scintillator with improved optical and mechanical properties are described. How the modules will perform in a large calorimeter was determined from prototype measurements. The experimentally determined characteristics of the calorimeter prototype show energy resolution of σ E / E = ( 1.96 ± 0.1 ) % ⊕ ( 2.74 ± 0.05 ) % / E , time resolution of σ T = ( 72 ± 4 ) / E ⊕ ( 14 ± 2 ) / E ( ps ) , where photon energy E is given in GeV units and ⊕ means a quadratic summation. A punch-through inefficiency of photon detection was measured to be e ≈ 5 × 10 - 5 ( Θ beam > 5 mrad ) .

Heat Capacities of Tetracene and Pentacene

Abstract: New solid state heat capacity data for tetracene and pentacene are reported in the temperature range (258 to 600) K. The heat capacity measurements were performed using the step method with a Setaram Micro DSC III calorimeter (Institute of Chemical Technology, Prague) and a Setaram TG-DSC 111 (University of Alberta) calorimeter. These new heat capacity data are shown to be in good agreement with one another and with several solid state constant-pressure heat capacity estimation methods and quantum mechanical calculations. The new results highlight errors in the solid state heat capacity and melting point databases for polynuclear aromatic hydrocarbons.

Design and Electronics Commissioning of the Physics Prototype of a Si-W Electromagnetic Calorimeter for the International Linear Collider

Abstract: 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 18x18 cm2 and a pad size of 1x1 cm2. 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-over-noise 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 Measurement of Metal Droplet Temperature in GMA Welding by Infrared Two-Color Pyrometry

Abstract: The temperature of metal droplets is essential for clarifying the phenomenon of metal droplet transfer and the melting behaviour of wire; also, it governs the emission of fumes. On the other hand, in situ measurement of the temperature of a metal droplet formed at the tip of a wire during welding was difficult. Hence, this temperature was obtained in many experiences of measurements by such a way that several numbers of metal droplets were collected in a calorimeter to measure the amount of heat content of metal droplet and the heat was converted to temperature. With this way, however, the reliability of the measurement is not necessarily high because the heat loss of the metal droplet during the time when detaching from the wire tip and entering into the calorimeter has to be estimated properly. In this research, two-colour pyrometry has been conducted to obtain the temperature of metal droplets, in which metal droplets have been photographed by a high-speed camera during arc welding, two wavelengths (95...

Intercalibration of the barrel electromagnetic calorimeter of the CMS experiment at start-up

Abstract: Calibration of the relative response of the individual channels of the barrel electromagnetic calorimeter of the CMS detector was accomplished, before installation, with cosmic ray muons and test beams. One fourth of the calorimeter was exposed to a beam of high energy electrons and the relative calibration of the channels, the intercalibration, was found to be reproducible to a precision of about 0.3%. Additionally, data were collected with cosmic rays for the entire ECAL barrel during the commissioning phase. By comparing the intercalibration constants obtained with the electron beam data with those from the cosmic ray data, it is demonstrated that the latter provide an intercalibration precision of 1.5% over most of the barrel ECAL. The best intercalibration precision is expected to come from the analysis of events collected in situ during the LHC operation. Using data collected with both electrons and pion beams, several aspects of the intercalibration procedures based on electrons or neutral pions were investigated.

High-pressure isobaric heat capacities using a new flow calorimeter

Abstract: An automated flow calorimeter has been developed for the measurement of high accurate isobaric heat capacities for pure compounds and mixtures over the range 250–400 K and 0–20 MPa. The technique has been checked for different compounds and at different conditions of temperature and pressure and the results have been compared with the literature values available. The conclusion of this comparison is that the new calorimeter can measure heat capacities with an estimated total uncertainty better than 0.5%. This paper report describes the new equipment, its set-up and gives new heat capacity data for toluene and ethyl tert-butyl ether at different temperatures and pressures.

Utilization of microcalorimetry for an assessment of the potential for a runaway decomposition of cumene hydroperoxide at low temperatures

Abstract: The exothermic decomposition of cumene hydroperoxide (CHP) in cumene liquid was characterized by isothermal microcalorimetry, involving the thermal activity monitor (TAM). Unlike the exothermic behaviors previously determined from an adiabatic calorimeter, such as the vent sizing package 2 (VSP2), or differential scanning calorimetry (DSC), thermal curves revealed that CHP undergoes an autocatalytic decomposition detectable between 75 and 90°C. Previous studies have shown that the CHP in a temperature range higher than 100°C conformed to an nth order reaction rate model. CHP heat of decomposition and autocatalytic kinetics behavior were measured and compared with previous reports, and the methodology and the advantages of using the TAM to obtain an autocatalytic model by curve fitting are reported. With various autocatalytic models, such as the Prout-Tompkins equation and the Avrami-Erofeev rate law, the best curve fit among models was also investigated and proposed.

Energy calibration of the ATLAS liquid argon forward calorimeter

Abstract: One of the two ATLAS Forward Calorimeters (FCal), consisting of three modules, one behind the other, was exposed to particle beams of known energies in order to obtain the energy calibration. The data were taken in the H6 beamline at CERN in the summer of 2003, using electron and hadron beams with energies from 10 to 200 GeV. The beam test setup and collected data samples are described in detail. Using data samples taken with a minimal amount of material upstream of the calorimeter, the FCal response to electrons and pions, as measured by the linearity and resolution as a function of energy, is extracted and compared to ATLAS performance requirements.

Radiation qualification of the front-end electronics for the readout of the ATLAS liquid argon calorimeters

Abstract: The ATLAS detector has been built to study the reactions produced by the Large Hadron Collider (LHC). ATLAS includes a system of liquid argon calorimeters for energy measurements. The electronics for amplifying, shaping, sampling, pipelining, and digitizing the calorimeter signals is implemented on a set of front-end electronic boards. The front-end boards are installed in crates mounted between the calorimeters, where they will be subjected to significant levels of radiation during LHC operation. As a result, all components used on the front-end boards had to be subjected to an extensive set of radiation qualification tests. This paper describes radiation-tolerant designs, radiation testing, and radiation qualification of the front-end readout system for the ATLAS liquid argon calorimeters.

Power compensated thin film calorimetry at fast heating rates

Abstract: With the goal of measuring the heat released or absorbed during phase transitions occurring in small samples, we have developed a power-compensated membrane-based calorimeter that can maintain linear heating rates spanning 1–1000 K/s under nonadiabatic conditions. The device works in the intermediate range of heating rates between conventional, β β > 10 4 K/s, scanning calorimeters. Active control in real time during heating/cooling experiments is achieved using the NI-7831 card, which includes a 1 M field programmable array with a control loop timer of 20 μs. The performance capabilities of the instrument are demonstrated using a case study: the melting of 100-nm-thick In films. A dynamic sensitivity below 1 μJ is currently achieved. We show that under the present development, heating rates above 200–300 K/s in ambient gas result in a widening of the melting peak because of uncompensated thermal effects. Power loss corrections are applied to obtain the heat capacity of the sample and therefore correct enthalpy values of the transition.