During the decay of a tritium nucleus
into a helium-3 nucleus, a neutrino
and an electron are ejected
Neutrino
Neutron
Electron
Proton
Proton
Helium-3
Tritium
There is no way to directly measure
the mass of the neutrino but it can
be deduced by studying the energy
distribution of the electrons that are
emitted at the same time
Inside Katrin’s vacuum chamber,
electrons are channelled to flow very
nearly in the same direction by a
powerful magnetic field. This is how
it works ...
6
5
4
3
2
1
1. Rear section
Responsible for monitoring and
calibrating equipment
2. Tritium source
Tritium is placed in a device
known as a windowless gaseous
tritium source
3. Transport
Superconducting magnets
surrounding the pipe generate a
field 70,000 times as strong as
Earth’s magnetic field
4. Pre-spectrometer
Further limits the number of
electrons that might scatter on
residual gas molecules in the
vacuum chamber
5. Inside the spectrometer
Inside the huge vacuum
chamber, electrons spread out.
Only those with the highest
energy make it past the electric
force set up inside - roughly one
in 100bn reach the detector
Electric force
High-energy electron
Vacuum pump
Low-energy
electrons
6. The detector
By counting the number of electrons
that make it to the detector,
physicists can precisely measure the
endpoint of their spectrum and from
that deduce the mass of the neutrino
There is no way to directly measure the
During the decay of a tritium nucleus
mass of the neutrino but it can be deduced
into a helium-3 nucleus, a neutrino
by studying the energy distribution of the
and an electron are ejected
electrons that are emitted at the same time
Neutrino
Inside Katrin’s vacuum chamber, electrons
Neutron
Electron
are channelled to flow very nearly in the
same direction by a powerful magnetic
Proton
field. This is how it works ...
Proton
Helium-3
Tritium
6
5
4
3
2
1
1. Rear section
Responsible for monitoring and
calibrating equipment
2. Tritium source
Tritium is placed in a device known as a
windowless gaseous tritium source
3. Transport
Superconducting magnets surrounding the pipe generate a field
70,000 times as strong as Earth’s magnetic field
4. Pre-spectrometer
Further limits the number of electrons that might scatter on residual
gas molecules in the vacuum chamber
5. Inside the spectrometer tank
Inside the huge vacuum chamber, electrons spread out. Only those
with the highest energy make it past the electric force set up inside -
roughly one in 100bn reach the detector
High-energy electron
Electric force
Low-energy
electrons
Vacuum pump
6. The detector
By counting the number of electrons that make it to the detector,
physicists can precisely measure the endpoint of their spectrum and
from that deduce the mass of the neutrino