Astroparticle Physics

58 4 Physics of Particle and Radiation Detectionsandwich calorimeterprinciple. A sandwich calorimeter is a system where absorberand detector layers alternate. Particle multiplicationoccurs preferentially in the passive absorber sheets, whilstthe shower of particles produced is recorded in the activedetector layers. Sandwich calorimeters can be compactlyconstructed and highly segmented, however, they are inferiorto crystal calorimeters as far as the energy resolution isconcerned.4.5 Cryogenic Detection Techniques“Ice vendor to his son: ‘Stick to it, thereis a future in cryogenics.’”Anonymouscryogenic detectorsThe detection of very small energies can be performed incryogenic detectors. Cooper bonds in superconductors canalready be broken by energy deposits as low as 1 meV (=10 −3 eV). The method of classical calorimetry can also beused for particle detection at low temperatures. At low temperaturesthe specific heat of solids varies with the cube ofthe temperature (c sp ∼ T 3 ), therefore even the smallest energydeposits E provide a measurable temperature signal.These detectors are mainly used in the search for hypotheticalweakly interacting massive particles (WIMPs). To thiscategory also supersymmetric partners of ordinary particlesbelong. On the other hand, cryogenic detectors are also employedin the realm of high-resolution X-ray spectroscopywhere energy resolutions of several eV can be achieved.4.6 Propagation and Interactionsof Astroparticles in Galacticand Extragalactic Space“Space tells matter how to move ...andmatter tells space how to curve.”John A. Wheelerpropagation of astroparticlesneutrinosNow that the principles for the detection of primary andsecondary particles have been described, the interactions ofastroparticles traveling from their sources to Earth throughgalactic and extragalactic space shall be briefly discussed.Neutrinos are only subject to weak interactions withmatter, so their range is extremely large. The galactic or in-