Dual-Readout Calorimeter: DREAM Richard Wigmans, Nural Akchurin, Heejong Kim, Hans Paar, John Hauptman CERN H2 beam – summer 2003

“Dual Readout” - Cerenkov+Scintillation in same event Fluctuations in pi-zero content of hadronic showers limits energy resolution, introduces a constant term, and results in a non-linear calorimeter response Cerenkov light is largely generated by electrons from photons from pi-zeros, and therefore measures the pi-zero content event-by-event Scintillation light measures all charged tracks

Basic unit: 4mm x 4mm Cu tube

Beam view of module: hexagons define geometric channels Module is 2 meters deep in beam direction

Rear of module: Cerenkov and Scintillation fibers go to separate R725 Hamamatsu PMTs Bright light shining through 2 meters of Cu

H2 Beam at CERN: not quite to scale

Pre-Shower Detector: clean IDs

Cerenkov and Scintillation pulse height distributions

Cerenkov vs. Scintillation

EM shower fraction distribution

(Q+S)/E

S corrected by Cerenkov-measured EM fraction

Before & After EM fraction correction

Pion Energy Resolution

Distributions of “center-of-light”

Before & After Cerenkov-measured EM fraction

Energy resolution of “interaction jets”