73 research outputs found
Test in a beam of large-area Micromegas chambers for sampling calorimetry
Application of Micromegas for sampling calorimetry puts specific constraints
on the design and performance of this gaseous detector. In particular, uniform
and linear response, low noise and stability against high ionisation density
deposits are prerequisites to achieving good energy resolution. A
Micromegas-based hadronic calorimeter was proposed for an application at a
future linear collider experiment and three technologically advanced prototypes
of 11 m were constructed. Their merits relative to the
above-mentioned criteria are discussed on the basis of measurements performed
at the CERN SPS test-beam facility
MICROMEGAS chambers for hadronic calorimetry at a future linear collider
Prototypes of MICROMEGAS chambers, using bulk technology and analog readout,
with 1x1cm2 readout segmentation have been built and tested. Measurements in
Ar/iC4H10 (95/5) and Ar/CO2 (80/20) are reported. The dependency of the
prototypes gas gain versus pressure, gas temperature and amplification gap
thickness variations has been measured with an 55Fe source and a method for
temperature and pressure correction of data is presented. A stack of four
chambers has been tested in 200GeV/c and 7GeV/c muon and pion beams
respectively. Measurements of response uniformity, detection efficiency and hit
multiplicity are reported. A bulk MICROMEGAS prototype with embedded digital
readout electronics has been assembled and tested. The chamber layout and first
results are presented
Large Area Micromegas Chambers with Embedded Front-end Electronics for Hadron Calorimetry
AbstractMicromegas (Micro-mesh gaseous structure) is an attractive technology for applications in particle physics experiments (TPC, calorimeters, muon systems, etc.). The most important results of an extensive R&D program aiming to develop a new generation of a fine-grained hadron calorimeter with low power consumption digital readout using Micromegas chambers as an active element are presented. In 2010, the first large scale prototype of Micromegas chamber with almost 8000 readout channels has been built and tested with high energy particle beams at CERN. The fundamental results, such as detection effciency, hit multiplicity, gain stability, response uniformity and effect of power pulsing of the detector front-end electronics are reported. Eventually, the development and test of the second generation of the large scale prototype with new readout electronics and some important improvements of its mechanical design is described and the prospective towards the construction of a technological prototype of a 4.5 λ deep digital calorimeter for a future linear collider is also given
Micromegas for imaging hadronic calorimetry
The recent progress in R&D of the Micromegas detectors for hadronic
calorimetry including new engineering-technical solutions, electronics
development, and accompanying simulation studies with emphasis on the
comparison of the physics performance of the analog and digital readout is
described. The developed prototypes are with 2 bit digital readout to exploit
the Micromegas proportional mode and thus improve the calorimeter linearity. In
addition, measurements of detection efficiency, hit multiplicity, and energy
shower profiles obtained during the exposure of small size prototypes to
radioactive source quanta, cosmic particles and accelerator beams are reported.
Eventually, the status of a large scale chamber (1{\times}1 m2) are also
presented with prospective towards the construction of a 1 m3 digital
calorimeter consisting of 40 such chambers.Comment: 6 pages, 9 figures, CALOR2010 conferenc
Recent results of Micromegas sDHCAL with a new readout chip
Calorimetry at future linear colliders could be based on a particle flow
approach where granularity is the key to high jet energy resolution. Among
different technologies, Micromegas chambers with 1 cm2 pad segmentation are
studied for the active medium of a hadronic calorimeter. A chamber of 1 m2 with
9216 channels read out by a low noise front-end ASIC called MICROROC has
recently been constructed and tested. Chamber design, ASIC circuitry and
preliminary test beam results are reported
Modelo de estresse crônico por imobilização na vigência de tratamento oral com midazolam: efeitos comportamentais em ratos
Modelo de estresse crônico por imobilização na vigência de tratamento oral com midazolam: efeitos comportamentais em ratos
Members of the Norwegian Parliament were interviewed about the decision process concerning national road investments. Most of them found cost-benefit analysis useful, but apparently not as a device for ranking projects. Rather, the cost-benefit ratio was used to pick project proposals requiring political attention among the large number of projects included in the plan. However, information about project-related local conflicts seemed to be used much more extensively for this latter purpose. Attitudes towards cost-benefit analysis varied along the left-right political axis. These findings are shown to be consistent with a hypothesis that politicians rationally maximize subjective perceptions of social welfare
Effect of repeated stress on novelty-induced antinociception in rats
There is extensive evidence that acute stress induces an analgesic response in rats. On the other hand, repeatedly stressed animals may present the opposite effect, i.e., hyperalgesia. Furthermore, exposure to novelty is known to induce antinociception. The effects of repeated restraint stress on nociception after exposure to novelty, as measured by the tail-flick latency (TFL), were studied in adult male rats. The animals were stressed by restraint 1 h daily, 5 days a week for 40 days. The control group was not submitted to restraint. Nociception was assessed with a tail-flick apparatus. After being familiarized with the TFL apparatus, each group was subdivided into two other groups, i.e., with or without novelty. Animals were subjected to the TFL measurement twice. For the animals exposed to novelty, the first TFL measurement was made immediately before, and the second 2 min after a 2-min exposure to a new environment. While the control group presented an increased TFL after exposure to a novel environment, chronically stressed animals did not show this effect. These results suggest that repeated restraint stress induces an alteration in the nociceptive response, perhaps as a result of an alteration in endogenous opioids in these animals
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