AMANDA Maps Cosmic Neutrinos

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."

Comments

duh?

[greywire]

" The glass modules work like light bulbs in reverse"

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 neutrinos. No, they're just cameras. Why make it sound more complex than it really is?

Re:duh?

[Christopher Thomas]

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.

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 (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.

SETI Anyone?

[TechnoGrl]

I can't help but wonder if a high tech civilization using fission, fusion, antimatter and who knows what.... would generate high levels of nutrino flux and if results from detectors such as these could be used as a device to detect such?