Double differential neutron yields from thick targets used in space applications

In March 2016, secondary neutron production from thick-target shielding experiments were conducted at the National Aeronautics and Space Administration's (NASA) Space Radiation Laboratory at Brookhaven National Laboratory. Ion beams of proton, helium, and iron projectiles were aimed at aluminum targets with areal densities of 20, 40, and 60 g/cm(2). The ion beams were extracted at energies of 400 and 800 AMeV and neutron yields were measured with liquid scintillators at 10 degrees, 30 degrees, 45 degrees, 60 degrees, 80 degrees, and 135 degrees off the beam axis. A second 60 g/cm(2) aluminum target was placed 3.5 m downstream from the middle of front target to study backscattered neutrons. Double differential thick-target neutron yields for various combinations of projectile, projectile energy, target material, target thickness, and detector location were produced using the time-of-flight technique. These measurements will help NASA perform uncertainty analyses on their transport codes and contribute to shielding design studies for future space applications.