Benchmarking the Active Catcher Array for Detecting Heavy Elements Produced in Multi-Nucleon Transfer Reactions

All known elements from Fm to Og have been synthesized by heavy-ion fusion reactions, and are neutron-deficient relative to beta-stability. Multi-Nucleon Transfer (MNT) reactions have been suggested as an alternate pathway to synthesize new neutron-rich heavy nuclei and to approach the N=184 shell. The limited success of making heavy nuclides in radiochemical studies in the 70’s and 90’s led to skepticism over the veracity of these predictions. A reexamination of older data, and new predictions from microscopic and macroscopic models have reinvigorated efforts directed at making neutron-rich isotopes of Z=104-108 with these reactions.

The Active Catcher Array (AC) is a device at Texas A&M University built to study heavy residues produced in MNT reactions. It consists of 40 YAP scintillators coupled to PMTs at forward angles, and 8 IC-Si detectors at backward angles. A measurement of the ²³⁸U + ²³²Th reaction showed promising signatures of residues with Z up to 116 being produced in this reaction.

A new campaign of experiments aims to benchmark the AC, develop an algorithm for identifying alpha chains, and make the case for a much improved active catcher array with higher granularity, better energy resolution and linear energy response using single crystal diamond detectors.