Configuration II
(note in the figure the Köln Plunger)

There are experimental situations where the most important feature of an array is not the detection limit but instead the total efficiency.
This is the case, for example, when measuring lifetimes (both with the DSAM or the Recoil Distance Plunger Technique) or Transient Field g-factor measurements, as the precision of the measurement is determined mainly by the collected statistics.
In many thick target experiments, where the line shape is not determined by the Doppler effect, the gain in efficiency is also desired.
For these cases the original GASP project foresaw the so called configuration 2 (C2). In this configuration the 80 inner ball BGO detectors are removed.
The collimator function of the inner BGO ball is obtained with a Pb shield made of two hemispheres smaller in diameter (19 cm) having the same symmetry as the inner ball. This shield has been made in collaboration with the Institut für Kernphysik, Köln in Germany.
In this way the CS germanium systems are moved nearer to the target. The first implementation of C2 reduce the target-germanium distance from 27 cm to about 20 cm for the 28 detectors in the hexagonal positions and from 27 cm to 24 cm for the 12 in pentagonal ones.
The total photopeak efficiency at 1.33 MeV is thereby almost doubled from the standard 3% up to 5.8%.

C2 is operational since 1995.