How much light does a neutrino strike produce?

The following article got me thinking about neutrino detectors. The
subject of the article itself is pretty fascinating in its own right,
about super-high-energy neutrinos coming from cosmic sources.

BBC News - Neutrinos from the cosmos hint at new era in astronomy
http://www.bbc.co.uk/news/science-environment-22540352

As we know, when a neutrino strikes an atomic nucleus, it creates a
bright flash of Cherenkov Radiation, which is then detected by these
detectors. But my question is how much Cherenkov radiation will be
detected? How bright is the Cherenkov, that a single measly neutrino
striking a single measly atomic nucleus would produce enough photons to
be able to see it through hundreds of feet of ice? Would a single event
be energetic enough to produce the billions and trillions of Cherenkov
photons needed to be detected separately at various detectors placed
strategically around the ice?

Yousuf Khan

Yousuf Khan wrote:

As we know, when a neutrino strikes an atomic nucleus, it creates a
bright flash of Cherenkov Radiation, which is then detected by these
detectors. But my question is how much Cherenkov radiation will be
detected? How bright is the Cherenkov, that a single measly neutrino
striking a single measly atomic nucleus would produce enough photons to
be able to see it through hundreds of feet of ice? Would a single event
be energetic enough to produce the billions and trillions of Cherenkov
photons needed to be detected separately at various detectors placed
strategically around the ice?

A photomultiplier tube can detect a single photon. Hope this helps.

Steve

On 16/05/2013 9:56 AM, Steve Pope wrote:
Yousuf Khan wrote:

As we know, when a neutrino strikes an atomic nucleus, it creates a
bright flash of Cherenkov Radiation, which is then detected by these
detectors. But my question is how much Cherenkov radiation will be
detected? How bright is the Cherenkov, that a single measly neutrino
striking a single measly atomic nucleus would produce enough photons to
be able to see it through hundreds of feet of ice? Would a single event
be energetic enough to produce the billions and trillions of Cherenkov
photons needed to be detected separately at various detectors placed
strategically around the ice?

A photomultiplier tube can detect a single photon. Hope this helps.

I understand, but how many photons are created by the single neutrino
strike by itself? Is there somebody who knows?

Yousuf Khan

In article ,
Yousuf Khan wrote:

On 16/05/2013 9:56 AM, Steve Pope wrote:
Yousuf Khan wrote:

As we know, when a neutrino strikes an atomic nucleus, it creates a
bright flash of Cherenkov Radiation, which is then detected by these
detectors. But my question is how much Cherenkov radiation will be
detected? How bright is the Cherenkov, that a single measly neutrino
striking a single measly atomic nucleus would produce enough photons to
be able to see it through hundreds of feet of ice? Would a single event
be energetic enough to produce the billions and trillions of Cherenkov
photons needed to be detected separately at various detectors placed
strategically around the ice?

A photomultiplier tube can detect a single photon. Hope this helps.

I understand, but how many photons are created by the single neutrino
strike by itself? Is there somebody who knows?

It would depend on the energy of the neutrino and the medium that
absorbs the energy. The initial impact doesn't produce photons AFAICT;
rather, ionizing radiation from the nuclear reaction disturbs electrons
in the ice molecules, which then emit photons. You could roughly
estimate the number by dividing the impact energy by the energy of a UV
photon, something like 50 eV. For a better result you'd have to
integrate the frequency distribution of Cherenkov radiation, which is an
odd one -- intensity proportional to frequency up to a cutoff (for
water, in the near X-ray IIRC) where the index of refraction decreases
to 1. Most of the radiated energy will come from the high-frequency
photons, but it takes more low-frequency (visible) photons to contribute
a given amount of energy. Anyway, supposing the energy a beta particle
carries away from the nucleus to be in the MeV range, it should produce
thousands of photons along its track.

--
Odysseus

On 16/05/2013 2:10 PM, Odysseus wrote:
It would depend on the energy of the neutrino and the medium that
absorbs the energy. The initial impact doesn't produce photons AFAICT;
rather, ionizing radiation from the nuclear reaction disturbs electrons
in the ice molecules, which then emit photons. You could roughly
estimate the number by dividing the impact energy by the energy of a UV
photon, something like 50 eV. For a better result you'd have to
integrate the frequency distribution of Cherenkov radiation, which is an
odd one -- intensity proportional to frequency up to a cutoff (for
water, in the near X-ray IIRC) where the index of refraction decreases
to 1. Most of the radiated energy will come from the high-frequency
photons, but it takes more low-frequency (visible) photons to contribute
a given amount of energy. Anyway, supposing the energy a beta particle
carries away from the nucleus to be in the MeV range, it should produce
thousands of photons along its track.

Okay thanks, that makes sense.

Yousuf Khan

On Thu, 16 May 2013 02:10:10 -0600, Odysseus wrote:

... The initial impact doesn't produce photons AFAICT; rather, ionizing
radiation from the nuclear reaction disturbs electrons in the ice
molecules, which then emit photons....

ionizing radiation = high-energy photons

In article ,
Lofty Goat wrote:

On Thu, 16 May 2013 02:10:10 -0600, Odysseus wrote:

... The initial impact doesn't produce photons AFAICT; rather, ionizing
radiation from the nuclear reaction disturbs electrons in the ice
molecules, which then emit photons....

ionizing radiation = high-energy photons

Ionizing radiations includes not only gamma rays, but also nuclear
fragments, electrons (beta radiation), positrons, and other charged
species. The latter kind is what I was referring to.

--
Odysseus

On 5/30/2013 9:41 PM, Lofty Goat wrote:
On Thu, 16 May 2013 02:10:10 -0600, Odysseus wrote:

... The initial impact doesn't produce photons AFAICT; rather, ionizing
radiation from the nuclear reaction disturbs electrons in the ice
molecules, which then emit photons....

ionizing radiation = high-energy photons


actually, no. betas, alphas, and fission fragments are also ionizing
radiation.