1 Introduction
3
in the densest materials (of the order few meters in iron). Therefore the detectors for
hadronic cascades are composed of a sandwich of absorber material interspersed
with elements to detect the deposited energy. In such a device, only a certain fraction
of the total energy is sampled. The challenge of the design consists in making this
fraction as much as possible proportional to the total energy. The main advantage
of calorimeters, apart from the sensitivity to both charged and neutral particles, is
that their size increases only logarithmically with the energy of the incident particle,
hence much less than for magnetic spectrometers, albeit with an energy resolution
inferior to magnetic spectrometers below about 100 GeV. They require therefore
comparatively little space which is of paramount importance for colliders where the
solid angle around the interaction area has to be covered in most cases as fully as
possible.
Other detectors have been developed for particular applications, e.g. for muon
and neutrino detection or the observation of cosmic rays in the atmosphere or deep
underground/water. Experiments in space pose completely new problems related to
mechanical stability and restrictions on power consumption and consumables.
The main aim in the development of all these detectors is higher sensitivity, better
precision and less influence by the environment. Obviously, reduction of cost has
become a major issue in view of the millions of detector channels in most modern
experiments.
New and more sophisticated detectors need better signal processing, data acquisition and networking. Experiments at large accelerators and colliders pose special
problems dictated by the beam properties and restricted space. Imagination is the
key to overcome such challenges.
Experiments at accelerators/colliders and for the observation of cosmic rays
have become big projects involving hundreds or even thousands of scientists and
the time from the initial proposal to data taking may cover one to two decades.
Hence it is sometimes argued that they are not well adapted for the training of
students. However, the development of a new detector is subdivided in a large
number of smaller tasks (concept of the detector, building prototypes, testing,
computer simulations and preparation of the data acquisition), each lasting only a
few years and therefore rather well suited for a master or PhD thesis. The final “mass
production” of many detection channels in the full detector assembly, however,
is eventually transferred to industry. These kinds of activities may in some cases
have little to do with particle physics itself, but they provide an excellent basis
for later employment in industry. Apart from specific knowledge, e.g., in vacuum,
magnets, gas discharges, electronics, computing and networking, students learn
how to work in the environment of a large project respecting time schedules and
budgetary restrictions—and perhaps even most important to be trained to work in
an international environment.
Because the development of detectors does not require the resources of a large
project but can be carried out in a small laboratory, most of these developments
are done at universities. Indeed most of the progress in detector development is
due to universities or national laboratories. However, when it comes to plan a
large experiment these originally individual activities are combined and coordinated
3
in the densest materials (of the order few meters in iron). Therefore the detectors for
hadronic cascades are composed of a sandwich of absorber material interspersed
with elements to detect the deposited energy. In such a device, only a certain fraction
of the total energy is sampled. The challenge of the design consists in making this
fraction as much as possible proportional to the total energy. The main advantage
of calorimeters, apart from the sensitivity to both charged and neutral particles, is
that their size increases only logarithmically with the energy of the incident particle,
hence much less than for magnetic spectrometers, albeit with an energy resolution
inferior to magnetic spectrometers below about 100 GeV. They require therefore
comparatively little space which is of paramount importance for colliders where the
solid angle around the interaction area has to be covered in most cases as fully as
possible.
Other detectors have been developed for particular applications, e.g. for muon
and neutrino detection or the observation of cosmic rays in the atmosphere or deep
underground/water. Experiments in space pose completely new problems related to
mechanical stability and restrictions on power consumption and consumables.
The main aim in the development of all these detectors is higher sensitivity, better
precision and less influence by the environment. Obviously, reduction of cost has
become a major issue in view of the millions of detector channels in most modern
experiments.
New and more sophisticated detectors need better signal processing, data acquisition and networking. Experiments at large accelerators and colliders pose special
problems dictated by the beam properties and restricted space. Imagination is the
key to overcome such challenges.
Experiments at accelerators/colliders and for the observation of cosmic rays
have become big projects involving hundreds or even thousands of scientists and
the time from the initial proposal to data taking may cover one to two decades.
Hence it is sometimes argued that they are not well adapted for the training of
students. However, the development of a new detector is subdivided in a large
number of smaller tasks (concept of the detector, building prototypes, testing,
computer simulations and preparation of the data acquisition), each lasting only a
few years and therefore rather well suited for a master or PhD thesis. The final “mass
production” of many detection channels in the full detector assembly, however,
is eventually transferred to industry. These kinds of activities may in some cases
have little to do with particle physics itself, but they provide an excellent basis
for later employment in industry. Apart from specific knowledge, e.g., in vacuum,
magnets, gas discharges, electronics, computing and networking, students learn
how to work in the environment of a large project respecting time schedules and
budgetary restrictions—and perhaps even most important to be trained to work in
an international environment.
Because the development of detectors does not require the resources of a large
project but can be carried out in a small laboratory, most of these developments
are done at universities. Indeed most of the progress in detector development is
due to universities or national laboratories. However, when it comes to plan a
large experiment these originally individual activities are combined and coordinated