Martin Riopel

TRIDENT: An Infrared Differential Imaging Camera Optimized for the Detection of Methanated Substellar Companions

ABSTRACT We describe a near‐infrared camera in use at the Canada‐France‐Hawaii Telescope (CFHT) and at the 1.6 m telescope of the Observatoire du mont Megantic (OMM). The camera is based on a Hawaii‐1 1024 × 1024 HgCdTe array detector. Its main feature is the acquisition of three simultaneous images at three wavelengths across the methane absorption bandhead at 1.6 μm, enabling, in theory, an accurate subtraction of the stellar point‐spread function (PSF) and the detection of faint close, methanated companions. The instrument has no coronagraph and features fast data acquisition, yielding high observing efficiency on bright stars. The performance of the instrument is described, and it is illustrated by laboratory tests and CFHT observations of the nearby stars GL 526, υ And, and χ And. TRIDENT can detect (6 σ) a methanated companion with \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \use...

Is inhibition involved in overcoming a common physics misconception in mechanics

Abstract Science education is often challenged by students׳ misconceptions about various phenomena. Recent studies show that these misconceptions coexist with scientific conceptions, even after a conceptual change occurs. However, the mechanisms involve in overcoming the interference caused by this coexistence remain poorly understood. A possible explanation is that inhibition could play a role in learning science. An fMRI protocol was used to obtain functional brain images of novices and experts while performing a cognitive task in mechanics, a scientific discipline for which misconceptions are known to be frequent and persistent. The results show that experts, significantly more than novices, activate brain areas associated with inhibition: the right ventrolateral prefrontal cortex and the left dorsolateral prefrontal cortex. This suggests that the experts׳ misconceptions in mechanics have not been eradicated or transformed during learning; they would rather have remained encoded in their brain and were then inhibited to provide a correct answer.

CPAPIR: a wide-field infrared camera for the Observatoire du Mont Mégantic

CPAPIR is a wide-field infrared camera for use at the Observatoire du mont Megantic and CTIO 1.5 m telescopes. The camera will be primarily a survey instrument with a half-degree field of view, making it one of the most efficient of its kind. CPAPIR will provide broad and narrow band filters within its 0.8 to 2.5 μm bandpass. The camera is based on a Hawaii-2 2048x2048 HgCdTe detector.

An Optimized Data Acquisition System Without Reset Anomaly for the Hawaii and Hawaii-2 Arrays

This paper presents the data acquisition software system used for controlling near-infrared cameras/spectrometers designed and built by the Laboratoire ďAstrophysique Experimentale of the Universite de Montreal. These instruments are used on the 1.6-m Mont Megantic Observatory and/or the 3.6-m Canada-France-Hawaii Telescope (CFHT). The system features a modified DS9 imaging display with custom user interface functions written in Tcl/Tk. It includes standard coadd and multi-sample readout modes with pixel rates up to 1 MHz (demonstrated on HAWAII array with a SDSU-II coadder board). Its fast readout mode coupled with other efficient data management functions yield very high observing efficiencies virtually unlimited by the array controller speed. This feature is particularly crucial for applications requiring very short exposures on bright objects such as searching faint companions close to nearby bright stars. The system also features a unique clocking pattern that eliminates the reset anomaly effect of the HAWAII and the HAWAII-2 arrays without penalizing observing efficiency, and reduces temperature drifts of the arrays.

CFHT-WIRCam: Interlaced science and guiding readout with the Hawaii-2RG IR sensor

CFHTs experience with interlacing science and guide pixel readout using the Hawaii-2RG infrared sensors on WIRCam has been problematic due to timing limitations inherent to this approach as well as unexpected behaviour in the sensors themselves. These problems have been overcome by implementing high-speed readout (1.4 s per read) for WIRCams array of four Hawaii-2RG sensors, obviating the need for interlaced readout. The effect of the reset anomaly on the science and guide frames has been minimized by introducing suitable delays and a clocking scheme that does not significantly impact the minimum exposure time of the camera.

Portrait des différences entre les genres dans le contexte de l'apprentissage de l'électricité en fonction de la certitude exprimée lors de la production de réponses

RésuméCette recherche exploratoire poursuit l’objectif de décrire les évolutions de la «sensation de connaître» («feeling-of-knowing» [FOK]) lors d’apprentissages par la découverte de notions de base en électricité par des élèves du secondaire. L’analyse se concentre d’abord sur l’état initial des garçons et des filles en fonction de l’expérience préalable et de la perception qu’ils entretiennent de leurs capacités en sciences et technologie, puis sur l’évolution de la performance (i.e. les changements conceptuels effectués) et du FOK de ces mêmes groupes alors qu’ils vivent l’activité «les défis électroniques». Les résultats semblent indiquer que le traitement pédagogique utilisé ne produit pas de différences entre les genres en ce qui a trait aux apprentissages, mais qu’il favorise les garçons en ce qui concerne les certitudes qu’ils entretiennent quant aux réponses qu’ils fournissent.AbstractThis exploratory research aims to describe changes in the “feeling-of-knowing” (FOK) experienced by high school students who are being introduced to the fundamental concepts of electricity through learning by discovery. The analysis focuses first on the initial state of boys and girls in terms of their prior experience and the perception they have of their abilities in science and technology, then on the change in their performance (i.e. the conceptual shifts that take place) and the FOK of these same groups as they participate in “electronic problem-solving” activities. The results seem to indicate that this pedagogical approach produces the same results among both sexes in terms of learning acquisition, but favors boys in terms of the certainty they have of the solutions they provide.

The on-chip guiding system of the wide-field infrared camera at CFHT

The Canada-France-Hawaii Telescope (CFHT) is commissioning a new Wide field Infrared Camera (WIRCam) that uses a mosaic of 4 HAWAII-2RG near-infrared detectors manufactured by Rockwell. At the heart of the instrument is an On-Chip Guiding System (OCGS) that exploits the unique parallel science/guide frame readout capability of the HAWAII-2RG detectors. A small subsample of each array is continuously read at a rate of 50 Hz while the integration of the science image is ongoing with the full arrays. Each of these guiding windows is centered on a star to provide an error signal for the telescope guiding. An Image Stabilizer Unit (ISU) (i.e. a tip-tilt silica plate), provides the corrections. A Proportional Integral Differential (PID) closed loop controls the ISU such that telescope tracking is corrected at a rate of 5 Hz. The guide window size and readout rate are adjustable but typical numbers are 8×8-16×16 boxes read at 50 or 1.5 Hz. This paper presents the technical architecture of the guiding system and performance measurements on the sky with WIRCam.

TRIDENT: an infrared camera optimized for the detection of methanated substellar companions of nearby stars

A near-infrared camera in use at the Canada-France-Hawaii Telescope and at the 1.6m telescope of the Observatoire du Mont-Mégantic is described. The camera is based on a Hawaii-1 1024×1024 HgCdTe array detector. Its main feature is to acquire three simultaneous images at three wavelengths (simultaneous differential imaging) across the methane absorption bandhead at 1.6 micron, enabling an accurate subtraction of the stellar point spread function (PSF) and the detection of faint close methanated companions. The instrument has no coronagraph and features a fast (1 MHz) data acquisition system without reset anomaly, yielding high observing efficiencies on bright stars. The performance of the instrument is described, and it is illustrated by CFHT images of the nearby star Ups And. TRIDENT can detect (3 sigma) a methanated companion with Delta H=10 at 0.5” from the star in one hour of observing time. Non-common path aberrations between the three optical paths are the limiting factors preventing further PSF attenuation. Reference star subtraction and instrument rotation improve the detection limit by one order of magnitude.

The extinction to the H2 line emission in the DR 21 outflow source

The v = 1→0 S(1) and Q(3) lines of H 2 have been measured in four regions of the DR 21 H 2 line-emission source, in order to determine whether the observed morphology of the emission represents the distribution of the excited H 2 or is modified by nonuniform extinction across the source. The measured lines originate from the same upper level and their ratio is a direct measure of the reddening. The line ratios show that the extinction is quite uniform across the source and that there is no correlation between the intensity and the extinction.

Interest and Disinterest from College Students for Higher Education in Sciences

Although science plays an important role in society, a lack of interest of the youth for scientific studies is currently observed worldwide. Indeed, the proportion of science students in universities has been continuously decreasing for the last 15 years and an increasing gap is observed between the social demand and the scientific expertise. Several reasons influence the youth in their choice of program. Beyond personality and taste, factors related to interest for science can influence positively or negatively their enrollment in a college Science program. To bring to light the most striking factors, we questioned more than 1000 students of various pre-university college programs to probe their interest and motivation for sciences and to understand what had incited them to enroll in Sciences or not in college. We will present factors associated with the interest or the disinterest of students for higher education in sciences. We will consider the influence of faculty on students’ engagement, as well as self-efficacy, self-determination, amotivation and grade motivation.