Dual-readout calorimetry

The developments in observational sciences such as biology, astronomy and physics have always been driven by the quality of the tools with which the observations are being made. The development of the microscope, the telescope and ever more powerful particle accelerators have led to quantum leaps in our understanding of the functioning of living organisms, the notion of our place in space and time and the innermost structure of matter. Sometimes, factors unrelated to the quality of our instruments prevent further im- provement. For example, the angular resolution of a telescope is ultimately limited by diffraction. However, in practice atmospheric turbulence limits the resolution to values that are much larger than the diffraction limit. In such situations, ingenuity is needed: Using optical interferometry between different telescopes, the effects of this turbulence can be measured and thus greatly reduced. In the last quarter century, calorimeters have evolved as the particle detectors of choice in experiments at the energy frontier. However, development of the full potential of these detectors, which are based on total absorption of the particles to be measured, is hampered by an effect comparable to the atmospheric turbulence mentioned above. In this case, the problem is caused by the fact that electrons and photons generated in the absorption process produce significantly larger signals than equally energetic protons and pions generated in this process. This phenomenon, commonly referred to as non- compensation, is responsible for poor energy resolution, a non-linear response, and a non-Gaussian response function when detecting hadrons and jets. Dual-Readout calorimetry offers a solution for these problems. The DREAM Col- laboration is exploring the limits of the possibilities offered by this technique, by sytematically eliminating the limiting factors, one after the other. Powerful tools in this context are the simultaneous measurement of scintillation light and Cherenkov light generated in the absorption process, and a detailed measurement of the time structure of the signals. As a result, calorimetric measurements of hadrons and jets with a preci- sion level comparable to that achieved for electrons and photons now seem to be within reach. In this talk, the latest results of this generic detector R&D pro ject will be presented.