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Location: Chemistry/Physics Building, MUN
Time: 8:00 pm
Present: 23
Randy, our Vice President, gave the introduction, as Doug was busy with some work emergencies.
Gary Case noted that The Rooms will have a Space and Time exhibition, starting on March 28 and running into June. School students will be visiting on Thursday afternoons during the month of April. Our Centre has indicated we may be able to help them with the school groups, for example, by giving talks or demonstrations. We are also looking at doing a couple of public viewing events at The Rooms, probably on the Wednesdays closest to the first quarter moon in each of April and May. Gary is looking for members who want to assist in any of these events. The Rooms is also looking to mount interesting photos by our members to put on display (most have already been contacted). There will be no renumeration for this. Members can email any member of the executive if they are interested in helping out at public events.
Gary also explained that a letter of proposal has been sent to the government concerning a small observatory at Butterpot. He will let members know what is happening as events warrant.
Gary has recently spoken to an Upper Gullies Elementary kindergarten class. Fred Smith noted that Mount Pearl Senior High School now has an astronomy club. If members want to help him help them, they can get in touch with Fred.
Robert passed around a handout for the months of March to April. Some topics brought up:
Robert noted that despite the low relative inclination of Saturn's rings, he recently saw his best ever view of the C-ring. Robert also showed us some of his recent photos of the lunar eclipse.
Iconoclastic John Carter gave a short talk in which he presented his opinions on Global Warming, and tied it into an astronomical phenomenon... He noted that a Carbon Tax would be in his mind equivalent to putting a tax on air itself! Carbon is part of a natural cycle and he is far more concerned with the unnatural things that are going into the atmosphere, without as much recent ado. John drew our attention to a possible correlation of cosmic ray flux with our passage through the galaxy's arms, cloud cover, and periods of glaciation on the earth. [The sufficiently interested can google various takes on this evidence, and other possible influences.]
John's typed talk has been entered into our physical files.
Chris began with a demonstration with a Geiger counter of the fact that cosmic rays are passing through us all the time. An overview of the history of cosmic ray science, starting with Becquerel and Hess followed. They were first found because electroscopes were found to slowly discharge without any known source of radioactivity being around. Hess showed that the concentration increased with atmospheric height with his balloon trips.
Elucidated by Chris were the various kinds of rays: protons, alpha particles, electrons, and sometimes more exotic things like Carbon, Nitrogen, Oxygen, and muons. We were shown a graph of cosmic ray flux versus the energy. Basically, the more energetic the ray, the rarer it is to find.
Cosmic rays can be bent by magnetic fields, so tracking their source can be difficult if not impossible. Below 10 GeV there is a directional dependence due to the Earth's magnetic field. Above that, they tend to approach from all directions equally. In the Ultra-High Energy (UHE) case, with energies beyond 100 000 GeV, these have been correlated recently with Active Galactic Nuclei (AGN). Their directions would not be influenced much by cosmic electromagnetic and gravitational fields, due to their high energies. Something like a proton can have the equivalent amount of energy as a flying brick!
The sources are mainly known to be solar flares, the solar system's heliopause, supernova, and AGN.
The UHE events are usually detected via showers of particles created when they enter our atmosphere. There is also Cerenkov radiation created, and this can be detected by an array on the ground. Some examples of different detectors would be th Large Time-Coincidence Array, which has 1600 12 tonne tanks of water, with optical detectors looking for flashes. High schools have become involved in making some arrays. The CHICOS (http://www.chicos.caltech.edu/) array is student-made. The ALTA system (http://csr.phys.ualberta.ca/alta/) is student run, but the electronics are provided by the University of Alberta. The ALTA system uses 3 plastic scintillator detectors and is relatively cheap.
There followed a brief question and answer session.
Randy noted just before coffee, that the Centre has set a rate of $10 for Associate members.
[An Associate member of the Centre is a person who shares a household with an Ordinary, Youth, Affiliate or Life member of the Centre who has made application for such membership and who has paid the Associate membership fee referred to in Article 6.6.2 of our Constitution.]
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