AMANDA Maps Cosmic Neutrinos 19
Uosdwis writes "Remember those 'little neutral ones', neutrinos? You know those little guys have no charge, are invisible and just about no mass. Well a University of Wisconsin-Madison professor has created an array, burried in the antarctic, to detect them with help from the National Science Foundation and produced a map of nuetrinos in the cosmos. A different method than the tau neutrinos found a few years ago, and show the 'natural' neutrinos are at a higher energy level."
link to the map? (Score:1)
Re:link to the map? (Score:5, Informative)
Link to a different map (Score:2)
http://newscientist.com/news/news.jsp?id=ns9999395 2
Dark matter map seems to show that neutrinos are not the 'dark matter' people talk about.
DarkWing Duck! Let's get dangerous.
Re:Link to a different map (Score:1)
Link to AMANDA site (Score:4, Informative)
AMANDA Maps Cosmic Neutrinos [berkeley.edu]
It's probably just as well the link wasn't included in the original story, 'cause I bet it won't take many downloads of those multi-meg
Wow (Score:1)
duh? (Score:1, Interesting)
Is this a stupid analogy or what? This can be said about any type of light detector. This is like saying a digital camera works like a light bulb in reverse... duh? So these "modules" are just simply really sensitive digital cameras networked together.
When I first read about these things I thought it had something to do with solid glass spheres that for some reason, in combination with the ice, had optical properties that allowed them to capture neu
Re:duh? (Score:4, Interesting)
Not quite. These are photomultiplier tubes, designed to detect single photons. A photon strikes a photosensitive material, generating an electron. This electron is accelerated down a high-voltage tube, knocking additional electrons free from electrodes, creating an electron cascade that can be detected.
The electron cascade may or may not be detected using camera-like photosensors (using a phosphor screen to turn the electron cascade back into light) (nightvision goggles do something like this, photon-counting tubes may measure the charge transfer directly).
When I first read about these things I thought it had something to do with solid glass spheres that for some reason, in combination with the ice, had optical properties that allowed them to capture neutrinos.
Ice is used because it's reasonably transparent. That's about it. Neutrino detection in this detector seems to be purely based on scattering of neutrinos against other particles with enough energy to produce Cherenkov light as the other particles fly off. How they plan to focus exclusively on muons is beyond me. With electron neutrinos you'd mainly get electron scattering as opposed to direct synthesis of muons. While mu neutrinos could produce muons via Weak-force interactions, they'll have scattering interations as well, and you have plenty of electron neutrinos present too.
A good introduction to neutrino detection is at http://www.sno.phy.queensu.ca/sno/sno2.html [queensu.ca] (Sudbury Neutrino Observatory page).
No, they're just cameras. Why make it sound more complex than it really is?
Cameras produce images. Photomultiplier tubes don't (they just indicate that a photon hit the tube). Determination of the path of the neutrino is done by looking at the timing of photon events in many detectors in the array, and looking at which detectors registered events at all.
Re:duh? (Score:3, Informative)
Ice is used in this case because you want these detectors deep under the Earth's surface to shield from atmospheric muons and other background
Re:duh? (Score:1)
SETI Anyone? (Score:4, Interesting)
Yes and no. (Score:5, Informative)
The reason for this is any civilization advanced enough to have fission--much less fusion, MAM, quark-gluon conversion or other exotic energies--is first going to progress through a much lower-tech level, during which point their civilization is going to glow like a supernova in certain bands of the electromagnetic spectrum. (Earth, for instance, far outshines the Sun in several wavelengths.)
Rather than peek at the cosmos with a neutrino telescope to see the (relatively small) signatures of an individual fusion reactor here or there, it makes more sense to look at the cosmos with radio-astronomy tools to look for planets that are brighter than stars. Find one like that, and dollars to donuts says it's got intelligent life.
To give you an idea of just how quiet the cosmos is... if you were to stand on Pluto and turn on a cell phone, you'd create a radio signal so loud it would drown out literally everything in the night sky (at least on its band). It's quiet out there.
Re:Yes and no. (Score:4, Insightful)
The Cosmic Background Radiation at about 900MHz is about 10^(-21) W/(m^2 sr Hz). A 3 W cell phone radiating into a sphere puts out per square meter about 2.5x10^(-10) W/(sr Hz). This means that the strengths of the two signals are equal at about 500,000 meters, or only 500 km. Pluto's diameter is about 2,000 km, so you'd be lost in the noise without even leaving Pluto.
Re:SETI Anyone? (Score:1)
I'd think you would need an incredibly sensitive detector in terms of determining the angle of origin of the neutrinos. Remember that most such civilizations will have an enormous fusion reactor -- aka a star -- right nearby, generating more such particles than the civili
Re:SETI Anyone? (Score:2)
While a civilization using any of several varieties of nuclear power could produce substantial neutrino emissions, these would be swamped by the neutrinos emitted by their parent star.
Also, the fusion reactions proposed for power production do not produce substantial numb
AMANDA (Score:1)
"Amanda Huggankiss! I need Amanda Huggankiss!"
-Moe
Not a signal map (Score:4, Informative)