ZapperZ said:
How do you propose to do that beyond the existing neutrino detectors, or base on what we currently know about neutrino detection?
Zz.
By "do that" you mean increase the effective area in such a way that you could observe astrophysical signals?
First things first:
When one tries to do neutrino physics without accelerators or reactors, (or geoneutrinos =>just saying for completeness)
the possible signals come from the following:
Solar neutrinos (MeV), Supernova Neutrinos(~100 MeV), Atmospheric neutrinos (GeV - TeV), astrophysical neutrinos (diffuse-point sources, GZK, top down scenarios, the unknown =>
~10 TeV -).
In each of the above scenaria you optimize your detector to be able to record neutrino interaction outcomes with the best possible directional and energy resolutions. The detector design itself imposes an energy threshold appropriate for the physics you want to do.
In all examples illustrated below, I shall use the muonic channel.
Low threshold = large photocathode area coverage => a very densely packed detector (Take for example trying to do MeV-GeV physics. To measure energy you need to measure the range of the muons. And what's more, the best option would be to have them contained in your detector - or at least have their starting point or ending point - take for example SuperK).
Now, as one goes to the astrophysical neutrinos realm, they have to face the following problems:
1) It is signal limited science (a handful of events per year in a km3 detector)
- This means that you have to grow your detector as big as possible to increase the probability of observing a UHE neutrino interaction. You should also optimize in order to increase the effective area (the most beautiful feature of a neutrino telescope is that it can detect muons even though they may pass outside its instrumented volume!). Bigger effective area => More detected events for a given neutrino flux. Now this comes with the drawback of making your detector sparser-> therefore increasing the energy threshold.
The above results in changing your experimental environment from deep mines to the deep ocean, sea or ice, since mines have a very specific volume they can instrument. Deep comes from eliminating cosmic muon background.
2) You cannot measure energy reliably since muons pass through your setup (even though it may be a km3 grid of photodetectors)
- Therefore your energy resolution for muons becomes worse than in the mine case. It is not coincidence that you measure the resolution in units of logE . This means that you overestimate or underestimate your energy by a factor of 1.5 to 5 sometimes!
- However, one needs to discriminate atmospheric neutrino background from astrophysical neutrinos. In the point source analysis this is easier. But in general diffuse searches, you have to impose a threshold (at some tens of TeV usually) to diminish the background.
Therefore to answer your question (finally!) one needs to grow a detector as much as possible, optimizing its design (taking into account the available depth, environmental parameters etc) so as to reach maximum effective area and after all sensitivity for astrophysical neutrino detection.
About Vanadium50's question, as explained above, in the neutel jargon, when talking about astrophysical neutrinos, we refer to the energy scale of TeV-PeV and so on.
Bill_K, same thing here. I believe that when they speak about high energy they mean the above TeV scale.
To you the aim is only this? Finding point or diffuse sources?
Because if this is the case, the next question is "after this, what?"