The magnetized steel and scintillator calorimeters of the MINOS experiment

The Main Injector Neutrino Oscillation Search (MINOS) experiment uses an accelerator-produced neutrino beam to perform precision measurements of the neutrino oscillation parameters in the ""atmospheric neutrino"" sector associated with muon neutrino disappearance. This long-baseline experiment measures neutrino interactions in Fermilab`s NuMI neutrino beam with a near detector at Fermilab and again 735 km downstream with a far detector in the Soudan Underground Laboratory in northern Minnesota. The two detectors are magnetized steel-scintillator tracking calorimeters. They are designed to be as similar as possible in order to ensure that differences in detector response have minimal impact on the comparisons of event rates, energy spectra and topologies that are essential to MINOS measurements of oscillation parameters. The design, construction, calibration and performance of the far and near detectors are described in this paper. (C) 2008 Elsevier B.V. All rights reserved.

Construção de um calorímetro isotérmico diferencial de alta sensibilidade e baixo custo

The high cost of sensitivity commercial calorimeters may represent an obstacle for many calorimetric research groups. This work describes the construction and calibration of a batch differential heat conduction calorimeter with sample cells volumes of about 400 μL. The calorimeter was built using two small high sensibility square Peltier thermoelectric sensors and the total cost was estimated to be about US$ 500. The calorimeter was used to study the excess enthalpy of solution of binary mixtures of liquids, as a function of composition, for the following binary systems of solvents: water + 1,4-dioxane or + dimethylsulfoxide at 298,2 ± 0,5 K.

High-p(T) pi(0) production with respect to the reaction plane in Au plus Au collisions at s(NN)=200 GeV

Measurements of the azimuthal anisotropy of high-p(T) neutral pion (pi(0)) production in Au+Au collisions at s(NN)=200 GeV by the PHENIX experiment are presented. The data included in this article were collected during the 2004 Relativistic Heavy Ion Collider running period and represent approximately an order of magnitude increase in the number of analyzed events relative to previously published results. Azimuthal angle distributions of pi(0) mesons detected in the PHENIX electromagnetic calorimeters are measured relative to the reaction plane determined event-by-event using the forward and backward beam-beam counters. Amplitudes of the second Fourier component (v(2)) of the angular distributions are presented as a function of pi(0) transverse momentum (p(T)) for different bins in collision centrality. Measured reaction plane dependent pi(0) yields are used to determine the azimuthal dependence of the pi(0) suppression as a function of p(T), R(AA)(Delta phi,p(T)). A jet-quenching motivated geometric analysis is presented that attempts to simultaneously describe the centrality dependence and reaction plane angle dependence of the pi(0) suppression in terms of the path lengths of hypothetical parent partons in the medium. This set of results allows for a detailed examination of the influence of geometry in the collision region and of the interplay between collective flow and jet-quenching effects along the azimuthal axis.

Measurement of the production of neighbouring jets in lead-lead collisions at √sNN=2.76 TeV with the ATLAS detector

This Letter presents measurements of correlated production of nearby jets in Pb+Pb collisions at sNN−−−√=2.76 TeV using the ATLAS detector at the Large Hadron Collider. The measurement was performed using 0.14 nb−1 of data recorded in 2011. The production of correlated jet pairs was quantified using the rate, RΔR, of ``neighbouring'' jets that accompany ``test'' jets within a given range of angular distance, ΔR, in the pseudorapidity--azimuthal angle plane. The jets were measured in the ATLAS calorimeter and were reconstructed using the anti-kt algorithm with radius parameters d=0.2, 0.3, and 0.4. RΔR was measured in different Pb+Pb collision centrality bins, characterized by the total transverse energy measured in the forward calorimeters. A centrality dependence of RΔR is observed for all three jet radii with RΔR found to be lower in central collisions than in peripheral collisions. The ratios formed by the RΔR values in different centrality bins and the values in the 40--80 % centrality bin are presented.

Respiratory quotient evolution during normal pregnancy: what nutritional or clinical information can we get out of it?

Food intake increases to a varying extent during pregnancy to provide extra energy for the growing fetus. Measuring the respiratory quotient (RQ) during the course of pregnancy (by quantifying O2 consumption and CO2 production with indirect calorimetry) could be potentially useful since it gives an insight into the evolution of the proportion of carbohydrate vs. fat oxidized during pregnancy and thus allows recommendations on macronutrients for achieving a balanced (or slightly positive) substrate intake. A systematic search of the literature for papers reporting RQ changes during normal pregnancy identified 10 papers reporting original research. The existing evidence supports an increased RQ of varying magnitude in the third trimester of pregnancy, while the discrepant results reported for the first and second trimesters (i.e. no increase in RQ), explained by limited statistical power (small sample size) or fragmentary data, preclude safe conclusions about the evolution of RQ during early pregnancy. From a clinical point of view, measuring RQ during pregnancy requires not only sophisticated and costly indirect calorimeters but appears of limited value outside pure research projects, because of several confounding variables: (1) spontaneous changes in food intake and food composition during the course of pregnancy (which influence RQ); (2) inter-individual differences in weight gain and composition of tissue growth; (3) technical factors, notwithstanding the relatively small contribution of fetal metabolism per se (RQ close to 1.0) to overall metabolism of the pregnant mother.

A high-sensitivity differential scanning calorimeter with magnetic field for magnetostructural transitions

We have developed a differential scanning calorimeter capable of working under applied magnetic fields of up to 5 T. The calorimeter is highly sensitive and operates over the temperature range 10¿300 K. It is shown that, after a proper calibration, the system enables determination of the latent heat and entropy changes in first-order solid¿solid phase transitions. The system is particularly useful for investigating materials that exhibit the giant magnetocaloric effect arising from a magnetostructural phase transition. Data for Gd5(Si0.1Ge0.9)4 are presented.

A high-sensitivity differential scanning calorimeter with magnetic field for magnetostructural transitions

We have developed a differential scanning calorimeter capable of working under applied magnetic fields of up to 5 T. The calorimeter is highly sensitive and operates over the temperature range 10¿300 K. It is shown that, after a proper calibration, the system enables determination of the latent heat and entropy changes in first-order solid¿solid phase transitions. The system is particularly useful for investigating materials that exhibit the giant magnetocaloric effect arising from a magnetostructural phase transition. Data for Gd5(Si0.1Ge0.9)4 are presented.

Contribution to the Development of the LHCb Vertex Locator Readout Electronics

L'expérience LHCb sera installée sur le futur accélérateur LHC du CERN. LHCb est un spectromètre à un bras consacré aux mesures de précision de la violation CP et à l'étude des désintégrations rares des particules qui contiennent un quark b. Actuellement LHCb se trouve dans la phase finale de recherche et développement et de conception. La construction a déjà commencé pour l'aimant et les calorimètres. Dans le Modèle Standard, la violation CP est causée par une phase complexe dans la matrice 3x3 CKM (Cabibbo-Kobayashi-Maskawa) de mélange des quarks. L'expérience LHCb compte utiliser les mesons B pour tester l'unitarité de cette matrice, en mesurant de diverses manières indépendantes tous les angles et côtés du "triangle d'unitarité". Cela permettra de surdéterminer le modèle et, peut-être, de mettre en évidence des incohérences qui seraient le signal de l'existence d'une physique au-delà du Modèle Standard. La reconstruction du vertex de désintégration des particules est une condition fondamentale pour l'expérience LHCb. La présence d'un vertex secondaire déplacé est une signature de la désintégration de particules avec un quark b. Cette signature est utilisée dans le trigger topologique du LHCb. Le Vertex Locator (VeLo) doit fournir des mesures précises de coordonnées de passage des traces près de la région d'interaction. Ces points sont ensuite utilisés pour reconstruire les trajectoires des particules et l'identification des vertices secondaires et la mesure des temps de vie des hadrons avec quark b. L'électronique du VeLo est une partie essentielle du système d'acquisition de données et doit se conformer aux spécifications de l'électronique de LHCb. La conception des circuits doit maximiser le rapport signal/bruit pour obtenir la meilleure performance de reconstruction des traces dans le détecteur. L'électronique, conçue en parallèle avec le développement du détecteur de silicium, a parcouru plusieurs phases de "prototyping" décrites dans cette thèse.<br/><br/>The LHCb experiment is being built at the future LHC accelerator at CERN. It is a forward single-arm spectrometer dedicated to precision measurements of CP violation and rare decays in the b quark sector. Presently it is finishing its R&D and final design stage. The construction already started for the magnet and calorimeters. In the Standard Model, CP violation arises via the complex phase of the 3 x 3 CKM (Cabibbo-Kobayashi-Maskawa) quark mixing matrix. The LHCb experiment will test the unitarity of this matrix by measuring in several theoretically unrelated ways all angles and sides of the so-called "unitary triangle". This will allow to over-constrain the model and - hopefully - to exhibit inconsistencies which will be a signal of physics beyond the Standard Model. The Vertex reconstruction is a fundamental requirement for the LHCb experiment. Displaced secondary vertices are a distinctive feature of b-hadron decays. This signature is used in the LHCb topology trigger. The Vertex Locator (VeLo) has to provide precise measurements of track coordinates close to the interaction region. These are used to reconstruct production and decay vertices of beauty-hadrons and to provide accurate measurements of their decay lifetimes. The Vertex Locator electronics is an essential part of the data acquisition system and must conform to the overall LHCb electronics specification. The design of the electronics must maximise the signal to noise ratio in order to achieve the best tracking reconstruction performance in the detector. The electronics is being designed in parallel with the silicon detector development and went trough several prototyping phases, which are described in this thesis.

Selvityksiä reaktiokalorimetrin soveltuvuudesta hydrometallurgiaan

Tämän työn tavoitteena oli reaktiokalorimetrin käyttöönotto sekä sen käyttökelpoisuuden selvittäminen hydrometallurgisten sovellusten ja erityisesti sinkkisulfidin liuotuksen tutkimiseen. Työn kirjallisuusosassa on käsitelty yleisellä tasolla kalorimetrian ja reaktiokalorimetrian teoriaa, termodynamiikkaa sekä sinkkirikasteen liuotuksen kemiaa. Lisäksi työssä esitellään erilaisten kalorimetrien ja termoanalyyttisten mittauslaitteiden toimintaperiaatteita. Työn kokeellisessa osassa selvitettiin reaktiokalorimetrin mittaustulosten tarkkuutta vesi- kokeiden avulla. Laitteistolla määritettiin myös reaktiolämmöt sinkkisulfidin liukenemisreaktiolle sekä elohopeasuolan saostusreaktiolle. Lisäksi tutkittiin sekoitusnopeuden, lämpötilan ja kiintoainepitoisuuden vaikutusta mittaustuloksiin. Reaktiokalorimetrillä suoritettujen kokeiden perusteella havaittiin, että reaktiolämpöjen absoluuttisten arvojen määrittäminen laitteistolla on käytännössä vaikeaa. Koska reaktiokalorimetrillä pystytään määrittämään vain mittauksen aikana tapahtunut kokonaislämpömuutos, vaikuttavat mahdolliset faasimuutokset ja reaktorin lämpöhäviöt mittaustuloksiin. Näiden tekijöiden vaikutus on pyrittävä eliminoimaan tai niiden vaikutus on tunnettava tarkkaan, jos laitteella halutaan saada luotettavia reaktiolämpömittaustuloksia. Laitteiston mittaustarkkuus huononee huomattavasti, kun reaktorin lämpötila nousee yli 60 °C:een. Laitteistolla mitatut reaktiolämmöt poikkeavat huomattavasti vastaavista kirjallisuuden arvoista. Vedelle määritetyt ominaislämpökapasiteetit poikkeavat kirjallisuuden arvoista enintään 5 alle 90 °C:een lämpötilassa.

Construção de um calorímetro isotérmico diferencial de alta sensibilidade e baixo custo

The high cost of sensitivity commercial calorimeters may represent an obstacle for many calorimetric research groups. This work describes the construction and calibration of a batch differential heat conduction calorimeter with sample cells volumes of about 400 μL. The calorimeter was built using two small high sensibility square Peltier thermoelectric sensors and the total cost was estimated to be about US$ 500. The calorimeter was used to study the excess enthalpy of solution of binary mixtures of liquids, as a function of composition, for the following binary systems of solvents: water + 1,4-dioxane or + dimethylsulfoxide at 298,2 ± 0,5 K.

Effets des recuits ultra-rapides (10^5 K/s) sur la formation des siliciures métalliques en phase solide

La synthèse de siliciures métalliques sous la forme de films ultra-minces demeure un enjeu majeur en technologie CMOS. Le contrôle du budget thermique, afin de limiter la diffusion des dopants, est essentiel. Des techniques de recuit ultra-rapide sont alors couramment utilisées. Dans ce contexte, la technique de nanocalorimétrie est employée afin d'étudier, in situ, la formation en phase solide des siliciures de Ni à des taux de chauffage aussi élevés que 10^5 K/s. Des films de Ni, compris entre 9.3 et 0.3 nm sont déposés sur des calorimètres avec un substrat de a-Si ou de Si(100). Des mesures de diffraction de rayons X, balayées en température à 3 K/s, permettent de comparer les séquences de phase obtenues à bas taux de chauffage sur des échantillons de contrôle et à ultra-haut taux de chauffage sur les calorimètres. En premier lieu, il est apparu que l'emploi de calorimètres de type c-NC, munis d'une couche de 340 nm de Si(100), présente un défi majeur : un signal endothermique anormal vient fausser la mesure à haute température. Des micro-défauts au sein de la membrane de SiNx créent des courts-circuits entre la bande chauffante de Pt du calorimètre et l'échantillon métallique. Ce phénomène diminue avec l'épaisseur de l'échantillon et n'a pas d'effet en dessous de 400 °C tant que les porteurs de charge intrinsèques au Si ne sont pas activés. Il est possible de corriger la mesure de taux de chaleur en fonction de la température avec une incertitude de 12 °C. En ce qui a trait à la formation des siliciures de Ni à ultra-haut taux de chauffage, l'étude montre que la séquence de phase est modifiée. Les phases riches en m étal, Ni2Si et théta, ne sont pas détectées sur Si(100) et la cinétique de formation favorise une amorphisation en phase solide en début de réaction. Les enthalpies de formation pour les couches de Ni inférieures à 10 nm sont globalement plus élevées que dans le cas volumique, jusqu' à 66 %. De plus, les mesures calorimétriques montrent clairement un signal endothermique à haute température, témoignant de la compétition que se livrent la réaction de phase et l'agglomération de la couche. Pour les échantillons recuits a 3 K/s sur Si(100), une épaisseur critique telle que décrite par Zhang et Luo, et proche de 4 nm de Ni, est supposée. Un modèle est proposé, basé sur la difficulté de diffusion des composants entre des grains de plus en plus petits, afin d'expliquer la stabilité accrue des couches de plus en plus fines. Cette stabilité est également observée par nanocalorimétrie à travers le signal endothermique. Ce dernier se décale vers les hautes températures quand l'épaisseur du film diminue. En outre, une 2e épaisseur critique, d'environ 1 nm de Ni, est remarquée. En dessous, une seule phase semble se former au-dessus de 400 °C, supposément du NiSi2.

Effects of 3-nitrooxypropanol on methane emission,digestion, and energy and nitrogen balance of lactating dairy cows

The objective was to measure effects of 3-nitrooxypropanol (3NP) on methane production of lactating dairy cows and any associated changes in digestion and energy and nitrogen metabolism. Six Holstein-Friesian dairy cows in mid-lactation were fed twice daily a total mixed ration with maize silage as the primary forage source. Cows received 1 of 3 treatments using an experimental design based on two 3 × 3 Latin squares with 5-wk periods. Treatments were a control placebo or 500 or 2,500 mg/d of 3NP delivered directly into the rumen, via the rumen fistula, in equal doses before each feeding. Measurements of methane production and energy and nitrogen balance were obtained during wk 5 of each period using respiration calorimeters and digestion trials. Measurements of rumen pH (48 h) and postprandial volatile fatty acid and ammonia concentrations were made at the end of wk 4. Daily methane production was reduced by 3NP, but the effects were not dose dependent (reductions of 6.6 and 9.8% for 500 and 2,500 mg/d, respectively). Dosing 3NP had a transitory inhibitory effect on methane production, which may have been due to the product leaving the rumen in liquid outflow or through absorption or metabolism. Changes in rumen concentrations of volatile fatty acids indicated that the pattern of rumen fermentation was affected by both doses of the product, with a decrease in acetate:propionate ratio observed, but that acetate production was inhibited by the higher dose. Dry matter, organic matter, acid detergent fiber, N, and energy digestibility were reduced at the higher dose of the product. The decrease in digestible energy supply was not completely countered by the decrease in methane excretion such that metabolizable energy supply, metabolizable energy concentration of the diet, and net energy balance (milk plus tissue energy) were reduced by the highest dose of 3NP. Similarly, the decrease in nitrogen digestibility at the higher dose of the product was associated with a decrease in body nitrogen balance that was not observed for the lower dose. Milk yield and milk fat concentration and fatty acid composition were not affected but milk protein concentration was greater for the higher dose of 3NP. Twice-daily rumen dosing of 3NP reduced methane production by lactating dairy cows, but the dose of 2,500 mg/d reduced rumen acetate concentration, diet digestibility, and energy supply. Further research is warranted to determine the optimal dose and delivery method of the product. Key words: 3-nitrooxypropanol, methane, digestion, rumen, dairy cow

The upgraded DO detector

The DO experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid -argon calorimeters and central muon detector, remaining from Run 1, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to DO. (c) 2006 Elsevier B.V. All rights reserved.

The CMS experiment at the CERN LHC

The Compact Muon Solenoid (CMS) detector is described. The detector operates at the Large Hadron Collider (LHC) at CERN. It was conceived to study proton-proton (and lead-lead) collisions at a centre-of-mass energy of 14 TeV (5.5 TeV nucleon-nucleon) and at luminosities up to 10(34)cm(-2)s(-1) (10(27)cm(-2)s(-1)). At the core of the CMS detector sits a high-magnetic-field and large-bore superconducting solenoid surrounding an all-silicon pixel and strip tracker, a lead-tungstate scintillating-crystals electromagnetic calorimeter, and a brass-scintillator sampling hadron calorimeter. The iron yoke of the flux-return is instrumented with four stations of muon detectors covering most of the 4 pi solid angle. Forward sampling calorimeters extend the pseudo-rapidity coverage to high values (vertical bar eta vertical bar <= 5) assuring very good hermeticity. The overall dimensions of the CMS detector are a length of 21.6 m, a diameter of 14.6 m and a total weight of 12500 t.

Observation and studies of jet quenching in PbPb collisions at root s(NN)=2.76 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)