Enhanced suppression of background in capture reaction measurements with LAMBDA-II in ground laboratories

However, extremely low reaction yields combined with the cosmic-ray-induced background make these measurements highly challenging, particularly for capture reactions. This work demonstrates the second configuration of the Large-scale Modular BGO Detection Array (LAMBDA-II) designed to capture reaction measurements, and introduces a method for suppressing γ-ray detection background in ground laboratories.

By employing active and passive shielding, the background of LAMBDA-II was significantly reduced by approximately two orders of magnitude, reaching 8.1 × 10−3 and 1.0 × 10−3 keV−1h−1 in the 6–11 and 11–20 MeV energy ranges, respectively. When combined with a mA-scale intensity beam, this reduced background enables the investigation of several capture reactions of astrophysical interest in ground laboratories.