13 Neutrinos Oscillate and Hence They Weigh
103
must be conserved. The mesons then decay and produces neutrinos, i.e.
p + p → p + n + (π
+ , K
+ ) with (π
+ , K
+ ) → (μ
+
+ ν μ , e
+
+ ν e ), which
are used in laboratory experiments. This is much like what happens in the
atmosphere naturally, as was already mentioned above. The main difference
is that the distance from the source to the detector could now be controlled.
These neutrinos are allowed to travel an appropriate distance from their source
so that some of them would have oscillated to another species of neutrinos
whose associated charged lepton produced in the subsequent reaction could
be detected. These experiments had names like K2K (an experiment in Japan),
MINOS in the USA (Fermilab), and more recently NOVA (also in the USA).
They confirmed the ν μ to ν τ oscillation and thereby the original SuperK atmospheric neutrino oscillation results. Currently there is a major effort
involving a new experiment, called DUNE (Deep Underground Neutrino
Experiment), which will use neutrinos produced in the Fermilab accelerator and look for matter–anti-matter asymmetry involving the neutrinos, a
phenomenon that has been known to exist among mesons (and hence their
underlying constituents, the quarks) since 1964.
Another important experiment that clinched the case for the conclusions
from the solar neutrino observations was the KamLand experiment in Japan.
It looked at electron type anti-neutrinos coming from a bunch of reactors, to a
detector located at a central place at the right distance, to see oscillations. The
results of this experiment confirmed the oscillation pattern of solar electron
neutrinos and confirmed again that neutrinos do have a mass and the mass
differences concluded from other experiments were correct. This was followed
by another set of reactor experiments—conducted using reactor-emmitted
anti-neutrinos from the Daya Bay reactor in China, Double CHOOZ reactor
in France, and RENO experiment using a South Korean reactor. These
setups determined the mixing between the ν e and ν τ —thus showing that
all neutrinos mix among themselves in the most general way with varying
strengths. These discoveries will prove invaluable in deciphering the nature
of new physics as well as using neutrinos in practical applications.
13.8 Understanding the Sun Using Solar
Neutrinos
As mentioned earlier, why the Sun shines and how it has been doing it for
billions of years without failing remained a major mystery of nineteenth
century physics. With the understanding of the atomic nucleus and nuclear
103
must be conserved. The mesons then decay and produces neutrinos, i.e.
p + p → p + n + (π
+ , K
+ ) with (π
+ , K
+ ) → (μ
+
+ ν μ , e
+
+ ν e ), which
are used in laboratory experiments. This is much like what happens in the
atmosphere naturally, as was already mentioned above. The main difference
is that the distance from the source to the detector could now be controlled.
These neutrinos are allowed to travel an appropriate distance from their source
so that some of them would have oscillated to another species of neutrinos
whose associated charged lepton produced in the subsequent reaction could
be detected. These experiments had names like K2K (an experiment in Japan),
MINOS in the USA (Fermilab), and more recently NOVA (also in the USA).
They confirmed the ν μ to ν τ oscillation and thereby the original SuperK atmospheric neutrino oscillation results. Currently there is a major effort
involving a new experiment, called DUNE (Deep Underground Neutrino
Experiment), which will use neutrinos produced in the Fermilab accelerator and look for matter–anti-matter asymmetry involving the neutrinos, a
phenomenon that has been known to exist among mesons (and hence their
underlying constituents, the quarks) since 1964.
Another important experiment that clinched the case for the conclusions
from the solar neutrino observations was the KamLand experiment in Japan.
It looked at electron type anti-neutrinos coming from a bunch of reactors, to a
detector located at a central place at the right distance, to see oscillations. The
results of this experiment confirmed the oscillation pattern of solar electron
neutrinos and confirmed again that neutrinos do have a mass and the mass
differences concluded from other experiments were correct. This was followed
by another set of reactor experiments—conducted using reactor-emmitted
anti-neutrinos from the Daya Bay reactor in China, Double CHOOZ reactor
in France, and RENO experiment using a South Korean reactor. These
setups determined the mixing between the ν e and ν τ —thus showing that
all neutrinos mix among themselves in the most general way with varying
strengths. These discoveries will prove invaluable in deciphering the nature
of new physics as well as using neutrinos in practical applications.
13.8 Understanding the Sun Using Solar
Neutrinos
As mentioned earlier, why the Sun shines and how it has been doing it for
billions of years without failing remained a major mystery of nineteenth
century physics. With the understanding of the atomic nucleus and nuclear