The Euroball Project

The Euroball project is concerned with the design and development of gamma-ray detectors with substantially improved qualities to be employed in different kinds of set-ups ranging from a single detector up to 4-pi spectrometers. All activities are carried out by a well organized collaboration of more than 30 european nuclear structure groups.

Since April 1999 the 4-pi array Euroball IV is operating at IReS Strasbourg. Preparations have started for a Euroball campaign at GSI employing the Clover and Cluster detectors.

Historically three phases have been defined in accordance with the progress in the development of new detector types and the availability of funds.

• The phase I arrays Eurogam I in Daresbury Laboratories, England and GASP at LNL Legnaro, Italy have been, respectivly are very successful. In these set-ups, large tapered Ge-crystals are used to detect gamma-rays with a total full energy efficiency of 3 to 4 percent.

• The elements of Eurogam I have been incorporated into the phase II array Eurogam II which is in operation at IReS, Strasbourg since June 1994. The main components of this array are Clover detectors each consisting of four closely packed Ge-crystals, reflecting the basic idea of all Euroball developments, i.e. to build composite detectors consisting of several Ge crystals. This enables unique detector efficiencies (photopeak efficiency larger than 20 percent) and provides small solid angles per element to preserve the necessary energy resolution deteriorated by Doppler effects in many applications.

• For the third phase, Euroball III, an even more advanced detector concept was realized. The Cluster detector composed of seven large encapsulated Ge-diodes with hexagonal front face.

Arrays of five and six Cluster detectors were employed in 1996 prior to the start of Euroball III in a Euroball campaign at the Max-Planck-Institut für Kernphysik at Heidelberg and a campaign at GSI.

Operation of Euroball III at Legnaro started in early 1997 and finished in November 1998. Afterwards the array was moved to Strasbourg to be used as Euroball IV with a BGO Inner Ball until the end of 2002.