Haverah Park experiment
Encyclopedia
The Haverah Park experiment was a cosmic ray
air shower
detection array consisting of water Cherenkov detector
s distributed over an area of 12 km2on Haverah Park on the Pennine moorland
near Harrogate
, North Yorkshire
. The experiment was operated by University of Leeds
for 20 years, and was switched off in 1987.
Air showers of secondary particles generated from a primary cosmic ray hitting the Earth's atmosphere
are spread over many kilometers when they hit the ground. An array allows for detection of secondary particles caused by a single cosmic ray at several detectors. The geographic spread of the detectors allows for calculation of the following:
During its operation. many thousands of cosmic ray events were recorded including four exceptional events with energies over 1020 eV
. These results were somewhat controversial because they are beyond the GZK limit. Such particles were since observed by other experiments, such as Fly's Eye (Oh-My-God particle
) and AGASA
.
The water Cherenkov detector
array is one of two cosmic ray detection systems used by the currently operating Pierre Auger Observatory
.
Cosmic ray
Cosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray is historical as cosmic rays were thought to be electromagnetic radiation...
air shower
Air shower (physics)
An air shower is an extensive cascade of ionized particles and electromagnetic radiation produced in the atmosphere when a primary cosmic ray enters the atmosphere...
detection array consisting of water Cherenkov detector
Cherenkov detector
A Cherenkov detector is a particle detector using the mass-dependent threshold energy of Cherenkov radiation. This allows a discrimination between a lighter particle and a heavier particle ....
s distributed over an area of 12 km2on Haverah Park on the Pennine moorland
Moorland
Moorland or moor is a type of habitat, in the temperate grasslands, savannas, and shrublands biome, found in upland areas, characterised by low-growing vegetation on acidic soils and heavy fog...
near Harrogate
Harrogate
Harrogate is a spa town in North Yorkshire, England. The town is a tourist destination and its visitor attractions include its spa waters, RHS Harlow Carr gardens, and Betty's Tea Rooms. From the town one can explore the nearby Yorkshire Dales national park. Harrogate originated in the 17th...
, North Yorkshire
North Yorkshire
North Yorkshire is a non-metropolitan or shire county located in the Yorkshire and the Humber region of England, and a ceremonial county primarily in that region but partly in North East England. Created in 1974 by the Local Government Act 1972 it covers an area of , making it the largest...
. The experiment was operated by University of Leeds
University of Leeds
The University of Leeds is a British Redbrick university located in the city of Leeds, West Yorkshire, England...
for 20 years, and was switched off in 1987.
Air showers of secondary particles generated from a primary cosmic ray hitting the Earth's atmosphere
Earth's atmosphere
The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
are spread over many kilometers when they hit the ground. An array allows for detection of secondary particles caused by a single cosmic ray at several detectors. The geographic spread of the detectors allows for calculation of the following:
- The total number of particles detected can be used to estimate the number of particles in the air shower and from the model of the energy required to generate those particles, the energy of the primary cosmic ray.
- The difference in the time of arrival of recorded particles at multiple detectors can be used to estimate the arrival direction of the primary cosmic ray.
During its operation. many thousands of cosmic ray events were recorded including four exceptional events with energies over 1020 eV
Electronvolt
In physics, the electron volt is a unit of energy equal to approximately joule . By definition, it is equal to the amount of kinetic energy gained by a single unbound electron when it accelerates through an electric potential difference of one volt...
. These results were somewhat controversial because they are beyond the GZK limit. Such particles were since observed by other experiments, such as Fly's Eye (Oh-My-God particle
Ultra-high-energy cosmic ray
In astroparticle physics, an ultra-high-energy cosmic ray or extreme-energy cosmic ray is a cosmic ray with an extreme kinetic energy, far beyond both its rest mass and energies typical of other cosmic rays....
) and AGASA
AGASA
The Akeno Giant Air Shower Array is a very large surface array designed to study the origin of ultra-high-energy cosmic rays. It covers an area of 100 km2 and consists of 111 surface detectors and 27 muon detectors...
.
The water Cherenkov detector
Cherenkov detector
A Cherenkov detector is a particle detector using the mass-dependent threshold energy of Cherenkov radiation. This allows a discrimination between a lighter particle and a heavier particle ....
array is one of two cosmic ray detection systems used by the currently operating Pierre Auger Observatory
Pierre Auger Observatory
The Pierre Auger Observatory is an international cosmic ray observatory designed to detect ultra-high-energy cosmic rays: single sub-atomic particles with energies beyond 1020 eV...
.