Dwarf Ball: a 4π light-charged particle multidetector system for heavy-ion reaction mechanisms and spectroscopy

The design and construction of a new spectrometer for heavy-ion reaction mechanism studies and for high spin spectroscopy is reported. The first version of this spectrometer consists of 72 fast-slow scintillator phoswiches packed with the same geometry as the spin spectrometer at the Holifield Heavy-Ion Research Facility and is small enough to fit inside the spin spectrometer. An improved version of the Dwarf Ball incorporates up to 85 detectors consisting primarily of CsI(T1) scintillators in a 4π arrangement and provides far superior performance in terms of energy resolution, particle identification, and dynamic range for energy measurements. The capabilities of the device for recording proton and α-particle spectra is discussed. The new possibilities for heavy-ion reaction studies and for nuclear spectroscopy that this device offers will be discussed