ASTM E722 Standard Practice for Characterizing Neutron Fluence Spectra in Terms of an Equivalent Monoenergetic Neutron Fluence for Radiation-Hardness Testing of Electronics

ASTM E722 Introduction

ASTM E722 is used to measure neutron exposure in units of equivalent monoenergetic neutron fluence. Another major issue in electronic systems utilized in the aerospace industry, defense systems, nuclear facilities, and space missions is radiation effects. Single-event effects (SEE) and long-term damage in semiconductor devices can also be caused by neutrons, especially. This enables comparison of test results obtained in various facilities with different neutron spectra on a common basis. It is common practice in the qualification of microelectronics to radiation environments.

ASTM E722 Test Method

ASTM E722 Equipment and Sample Preparation

ASTM E722 Results and Interpretation

The product of this test method is the 1 MeV equivalent neutron fluence in silicon, which is the displacement damage potential of the neutron spectrum being tested. This is a measure of the similarity of the neutron environment of a facility to standardized testing conditions. The higher the fluence, the higher the displacement damage equivalence, which could have a considerable influence on the reliability of electronic devices.

ASTM E722 Related Test Methods

ASTM E1855 is used for neutron dosimetry, and ASTM E2006 for testing single-event effects in microelectronics. These standards collectively support radiation-hardness assurance programs.

ASTM E722 Applications in Industry 

The practice is common in aerospace and defense sectors, nuclear reactor plants, and space electronics qualification. It ensures that the components employed in satellites, spacecraft, and defense systems will withstand damage caused by neutrons. This method is also used by semiconductor manufacturers and research laboratories to standardize test results and to enable them to improve their design.

ASTM E722 Materials Commonly Tested

The practice is mostly used with silicon-based electronic components such as microelectronics, integrated circuits, power devices, and optoelectronic systems. The 1 MeV equivalent fluence has been normalized in terms of the displacement damage in silicon lattices because silicon is the most common semiconductor material. 

ASTM E722 Common Challenges and Troubleshooting

There could be problems in the correct quantification of neutron spectra at various facilities, which can lead to conversion to the same fluence. The uncertainty of variations in the semiconductor material responses and the variation in energy-dependent displacement functions can also be a source of uncertainty. Calibration of devices used to measure the magnitude of the displacement, and the use of standardized displacement damage functions, are essential to yield reliable results.

ASTM E722 Safety and Best Practices

Neutron source testing must be done with extreme care for radiation safety. Staff members should adhere to facility-based protocols regarding shielding, exposure surveillance, and management of irradiated samples. Electronic equipment must also be well-installed to prevent contamination and damage when it is exposed.

Importance of ASTM E722 Test Method

This method is necessary in helping the dependence of electronic systems on neutron radiation. This has enabled a consistent evaluation of the rigidity of the equipment, enables cross-facilities comparisons, and upgrades the development of radiation-crisp technologies through standardizing the representation of neutron flutes. The result of this exercise is ultimately a safe and reliable operation of important electronics in a rigid environment such as space, aviation, and atoms.