next up previous contents
Next: Choice of the Up: Design of the Previous: Modularity of the

Thickness of the Calorimeter

Figure: Response of the calorimeter to decay events for three different detector thickness: 10, 12 and 14 radiation lengths. These calculations include the effects of light collection nonuniformity and photoelectron statistics. The calorimeter response to accidentally coincident Michel events is also shown. The actual thickness of was selected as a compromise between the cost and the energy resolution of the calorimeter.

The thickness of the calorimeter was determined after Monte Carlo simulations of its response to pion beta events. Different thicknesses of 10, 12, and 14 radiation lengths ) were considered during the simulations which included the effects of photoelectron statistics and light collection nonuniformity. The detection efficiency as a function of the thickness varied between (for ) and (for ). However, the higher thickness gave a better energy resolution (see figure gif) which is necessary in isolating the pion beta process from the background. Therefore, is a better choice for the thickness of the calorimeter whose volume, consequently the cost, increases with the cube of the outer radius. The actual thickness of was selected as a compromise: the energy resolution is worse but the cost of the calorimeter is less by than what it would be for .

Bernward Krause
Mon Jan 15 14:57:06 MET 1996