In
nuclear and
particle physics, calorimetry refers to the detection or particles, and measurement of their properties, particularly
energy. There are a wide variety of types, but they all have in common the feature that the process is
destructive to the particle itself in the sense that once passed through a
calorimetric device, the
particle cannot go on to be detected by a
secondary device.
Calorimetric
particle detection was pioneered shortly after WWII, as
scintillation counters came into use. The combination of use of certain
crystals with the new invention of the
photomultiplier tube made possible a new age of
measurement of particle properties, accellerating
experimental particle physics to new heights.
As the 'energy frontier' of particle physics was pushed higher and higher by new generations of
particle accellerators, these '
shower counters' or '
calorimeters' as they are now called gradually became more and more the cornerstone of
experiments. The old method of examining the curvature of a particle's
bubble chamber track became harder as energies increased. (Curvature is
inversely proportional to
momentum, and momentums were getting huge.) To a great extent, the high accuracy of these devices has satiated the need for new ways to measure the energy/momentum
four-vectors of particles.
Moreover, as the energy frontier marches forward, the physics processes of interest became more and more rare, and it became necessary to trigger the equipment when the 'signature' of a particular process was detected. The new technology of the developing field of Calorimetry provided the much needed equipment. Also, the information of interest became not what a
bubble chamber photograph would tell you, but rather, measurements of more global event characteristics, such as 'missing' energy and the production of certain patterns of
particle jets. The cool thing about these
scintillators is that they provide this
information nearly
instantaneously, making
instrument triggering more functional than ever.
Recently, almost every
graduate student who has written a
thesis in
experimental particle physics has had to examine calorimeter
data. This new
paradigm has been the key to many new discoveries in this field.