How does the Cerenkov effect work for neutrinos, despite them having no charge?

[bjaw]

Hi everyone,

I just have a question regarding a project I'm doing at the moment. I decided to write about the detection of neutrinos, and hence have to explain the Cerenkov effect which is used in the water detectors. What I can't understand is that, from what I've read so far, the Cerenkov effect only works for charged particles, and neutrinos have no charge! Can someone explain why the effect still occurs? Also, why is the light produced necessarily blue? I've seen why the angle produced occurs, but nothing I've read mentions the energy of the photons produced.

Thanks so much for any help

 

[ZapperZ]

Hi everyone,

I just have a question regarding a project I'm doing at the moment. I decided to write about the detection of neutrinos, and hence have to explain the Cerenkov effect which is used in the water detectors. What I can't understand is that, from what I've read so far, the Cerenkov effect only works for charged particles, and neutrinos have no charge! Can someone explain why the effect still occurs? Also, why is the light produced necessarily blue? I've seen why the angle produced occurs, but nothing I've read mentions the energy of the photons produced.

Thanks so much for any help

To the first part of your question, when neutrinos intract with matter, such as water, they will knock out either relativistic electrons or muons. It is these electrons and muons that are producing the cerenkov radiation.

As to why it is blue (actually, most of it is in the UV, but something we can't see with our eyes), you may want to read here:

http://www.physics.upenn.edu/balloon/cerenkov_radiation.html

Zz.

 

[jtbell]

In fact, the only way that we can detect neutrinos in any kind of detector, is by detecting the particles that they produce when they interact. For example, when a high-energy muon-neutrino interacts with a nucleon in an atomic nucleus, you typically get a single muon and a "jet" of other particles (mostly pions, protons, neutrons, etc., but also e+e- and mu+mu- pairs from pair production). Muon-neutrino detectors look for events with this "signature."

 

[bjaw]

Thanks for the swift reponses! That's helped a lot.

 

[Andrew Mason]

As far as using Cherenkov light to detect neutrinos, this http://www.sno.phy.queensu.ca/sno/sno2.html#interactions" explains the interaction of a neutrino and the deuterium nucleus in which the nucleus emits a high speed electron. It also describes the interaction of gamma rays and electrons (the gamma rays are produced after the nucleus interacts with a neutrino sending off a free neutron which is then captured by a chlorine nucleus) and of a neutrino directly with an electron. All three produce Chenenkov light which is detected in the photomultiplier tubes around the heavy water.

AM

 

[Gib Z]

Not to mention neutrons has no NET charge. They are made up of charged quarks though.

 

[d_leet]

Not to mention neutrons has no NET charge. They are made up of charged quarks though.

Neutrons are, but this thread seems to be discussing neutrinos which are fundamental particles and are not the same things as neutrons.