IF anyone from a school or a college is reading this, and is interested in setting up a detector as a project, and also joining a very interesting worrldwide project, check out Cosmic Pi
Boffins have built what could be one of the world's smallest working detectors of elusive neutrino particles. Grad students Bjorn Scholz and Grayson Rich hold neutrino detector CosI during installation. It looks like they are trying to illustrate the concept of a handheld neutrino detector, or maybe mix a martini, but in …
By that logic, you can't observe anything directly - all observations are records of something interacting with something else...
Even light - that's the interaction between a photon and the cells in your eye.
In the early days of particle physics - the interaction between a particle and the (supersaturated) gas in a cloud chamber, forming (essentially) a vapour trail... which is observed by... light.
The first observations for neutrinos - the interaction between the neutrino and by the (very occasional) atoms that happened to be hit by one, gaining the energy required to, at a later point, emit a photon of light.
(...but, before people start thinking there's a theme here...)
The experiments Ray Davis performed down in a mine involved the transmutation of Chlorine into (a radioactive isotope of) Argon, which could be collected and counted.
(Mine's the one with the Physics Degree in the pocket...)
'Learned said he tried using a 2kg scintillator detector to sniff out neutrinos before , but it failed to detect any because it was seeing too much noise from a nuclear reactor it was next to.'
I'm not a physicist but did he try moving it away from the nuclear reactor? I mean surely that's the advantage of an instrument that only weighs 2kg, it's man portable.
"I'm not a physicist but did he try moving it away from the nuclear reactor?"
While I don't know the details of the case, the problem when dealing with particles that can pass through the entire Earth as if it's not there is that "next to" can take fairly large values. In order to move it far enough away it could well have needed to move to a different campus or town rather than just to the next room or even building. That's not necessarily easy, especially if it's a fairly small experiment and the person running it has many other things to do, many of which may be considered more important.
Perhaps the choice of article is the problem, or a nano-typo. (the) reactor it was near was perhaps a convenient source of neutrinos for a test run, but it also generated neutrons and other garbage not easily shielded from. 'A' reactor implies it was just some random irrelevant reactor, which I find unlikely; researchers can expect to find noise from a nuclear reactor.
Hm. Slight confusion, here. A proton accelerator produces photons from the collisions, which is the light that the detectors pick up. However, to be clear: it's the beam of protons that smashes into the sample, producing the light. I've made it clearer in the piece.
Don't forget to email email@example.com if you spot any problems, so they can be fixed quickly.
I still don't think this is right.
The "Spallation Neutron Source" produces neutrons from slamming mercury with protons.
Directly from Le Wiki-Pédia:
The spallation process at SNS begins with negatively charged hydrogen ions that are produced by an ion source. Each ion consists of a proton orbited by two electrons. The ions are injected into a linear particle accelerator, or linac, which accelerates them to very high energies (eventually to 90% the speed of light).[citation needed (no seriously, WTF!)] The ions pass through a foil, which strips off each ion's two electrons, converting it to a proton. The protons pass into a ring-shaped structure, a proton accumulator ring, where they spin around at very high speeds and accumulate in “bunches.” Each bunch of protons is released from the ring as a pulse, at a rate of 60 times per second (60 hertz). The high-energy proton pulses strike a target of liquid mercury, where spallation occurs. The spalled neutrons are then slowed down in a moderator and guided through beam lines to areas containing special instruments where they are used in a wide variety of experiments.
So that's the idea. Where do we get those neutrinos from?
In the extra-interesting presentation about "COHERENT Elastic Neutrino-Nucleus Scattering" by Kate Scholberg ("CEνNS is a possibility but those internal Greek letters are annoying.. CEvNS, pronounced “sevens”... spread the meme!")
we find the explanation on 21 ("Stopped-Pion (πDAR) Neutrinos"):
The proton hits the Hg nucleus, eliciting Pions from nature's infinite bag of probablistic stuff: a pion+ and a pion- (these are quark-antiquark pairs), unsure what happens to the Hg nucleus.
The pion- is captured by another Hg nucleaus with high probability.
The pion+ decays into a muon and a muon neutrino.
The muon then decays into a positron, an anti-muon-neutrino and an electron-neutrino. That last one is the one we want.
Photons are not involved anywhere!
The must be some additional trickery regarding focusing of the neutrinos, we want a beam after all.
a) If it's a term of endearment, you should have included a pronunciation guide. I never heard of "cossl", which was my first guess at how the rebus the scientists invented was envisaged as conveying its sound.
2) It might have been worth pointing out that the huge detectors mentioned in the article typically are watching for neutrinos from the Sun, which requires as large a detector volume as can be practically engineered in order to maximize the chances of seeing an event originating from the sun and traveling in a presumed radial trajectory thereafter. Eight light minutes of distance from source means that the target detector has a vanishingly small footprint due to the realities of triangular geometry. Or something. There's probably a 2 Pi Cos theta involved. There almost always is.
The iWatch neutrino detector will be useful for people operating in environments where a lethal dose of neutrinos is a hazard.
Reminder that future muon factories present a Neutrino Hazard.
Yes, really! Potential Hazards from Neutrino Radiation at Muon Colliders - January 1999
Prepare for Greens Waving Boards.
Yes you can. Cosmic rays can and do directly affect the visual pathway neurons. That is as direct as possible.
Cosmic ray visual phenomena, or "light flashes" (LF), are spontaneous flashes of light visually perceived by some astronauts outside the magnetosphere of the Earth, such as during the Apollo program. While LF may be the result of actual photons of visible light being sensed by the retina, the LF discussed here could also pertain to phosphenes, which are sensations of light produced by the activation of neurons along the visual pathway.
Lethal dose of neutrinos says that one supernovae may emit 10^57 neutrinos.
This location says there are 3.28 x 10^80 particles in the observable Universe.
This location says that a neutrino is a particle, of course.
From the number of particles calculation site:
The physics professor developed a way to estimate the total number of particles in the universe, not counting photons or neutrinos, due to their lack of or near-lack-of mass.
Sorry, but the 10^80 is incorrect. Mass is massive no matter how light it each bit is. That includes photons since they have no rest mass but they do have energy and energy = mass. That is why photons have momentum.
Never mind so called "black matter", how many particles are there?
That's a question that pops up in my mind from time to time. And every time it does, I do a little "research", i.e. I feed some words into an internet search engine and go wherever the links take me. Nothing conclusive yet, all I've come up with so far is a very rough guestimate: a lot.
Never mind so called "black matter", how many particles are there?
That actually depends on the observer!
An accelerating observer sees additional particles in front while particles towards the back are disappearing behind an event horizon. See: Rindler Metric (no I am not a specialist). This is apparently related to new particles being pumped out of black holes (and are black holes only largish particles?)
And then there are the virtual particles, which are literally uncountable...
It is best to think that there are no fixed amount of particles, as these are just answer to a question asked of the corresponing particle field---
I remember that the idea floated about how a neutrino detector/emitter pair would be useful was to allow flash traders to send trading information right through the earth and so one-up the competition by a few sub-milliseconds (presumably going via fiber laid on a great circle).
Humanity is doomed.
I'm most likely horribly wrong, and this comes from a vague memory during a 1992 A-Level Physics talk about Neutrinos.
The Detectors work by have a huge volume of water in a dark place surrounded by very sensitive light sensors. The neutrino which is travelling at light speed unhindered by pesky stuff like matter, has a one in a billion chance collision with said wet matter. A physical particle is then accelerated for a fraction of a second at a speed faster than light in water. This creates a tiny cone of light which is detected.
"I'm most likely horribly wrong"
Nope, that's pretty much correct. The important part, however, is that it's not simply "a particle" that gets hit by a neutrino and accelerated to silly speeds, but specifically an electron, which is light enough to be accelerated to the speeds needed to produce Cherenkov radiation. You need such big detectors with tons of water because the chance of a neutrino actually hitting an electron is extremely small, so you need an awful lot of them to actually see anything. The trick with the detector in the article is that it instead looks for neutrinos hitting nuclei, which are much bigger targets and therefore you can still see a decent amount of collisions with only a small detector. The tricky part is that since nuclei are so much heavier as well, it's much harder to actually see the collisions since they don't produce Cherenkov radiation.