  A 50 element BaF2 gamma-multiplicity filter has been designed, fabricated and
installed successfully at the Variable Energy Cyclotron Centre (VECC), Kolkata
for angular momentum selection in heavy ion collision reactions. A thorough
GEANT3 Monte Carlo simulation was performed to optimize the individual detector
shape and geometrical structure of the array. The detectors have been
fabricated in-house from bare barium fluoride crystals (each measuring 5 cm in
length and having cross-sectional area of 3.5 x 3.5 cm2). The basic detector
properties have been studied using the lab standard -ray sources. The response
function of the filter has been studied using GEANT3 for mapping the fold
distribution of the filter onto the angular momentum space. The multiplicity
filter has been used successfully to measure the high angular momentum of the
compound nuclei populated in the reaction 20Ne (E = 145 & 160 MeV) + 93Nb, 27Al
as well as low angular momentum events from the fission fragments of 252Cf
spontaneous fission source. The filter has also been used successfully for
correcting non-statistical events involved in the heavy ion fusion reaction.
