Publications Details
Secondary beams and dose enhancement experiment at Brookhaven National Laboratories
Over the past three years, several experiments have been conducted at the Brookhaven National Laboratory Radiation Effects Facility. These experiments have been investigations of proton induced radiation effects in individual electronic components, circuits, operational subsystems and full systems. Our investigations using 170--200 MeV protons have included total dose effects up to 12 Mrad, dose rate effects of the ionizing radiation in the 10{sup 5} to 10{sup 8} rad/s range, the displacement damage effects of the protons up to 10{sup 15} p/cm{sup 2}, and the proton induced thermal shift and thermal-rate effects. The target thickness of many test devices was an appreciable fraction of the range of 200 MeV protons. In our proton beam testing experiments at BNL, dosimetry placed downstream of the target consistently yielded higher dose in rad and in particle fluence than in dosimetry placed upstream of the target. We designed and performed an experiment to study this dose enhancement. The objective of the experiment was to determine the effect of sample thickness on our three methods of dosimetry. The data from the PIN diodes and tantalum calorimeters were consistent and followed the expected DE/DX curve. They show a dose enhancement effect. The proton beam interacts and loses energy as it travels through thick targets. The exiting lower energy beam deposits more energy into the dosimetry because the stopping power increases with decreasing proton energy.