PEF

{
  "id": "MLC-T-OAG-002726",
  "term": "PEF",
  "field": "Oil and gas",
  "definition": "The photoelectric factor, the effective photoelectric absorption index per electron of the formation, which the litho-density tool derives from the low-energy part of the backscattered gamma-ray spectrum. It depends strongly on atomic number, roughly as Z to the power 3.6, so it separates lithologies, with typical values of about 1.8 for quartz, 5.1 for calcite and 3.1 for dolomite, and it is sharply raised by barite. It is quoted in barns per electron.",
  "subject": "Formation Evaluation",
  "url": "https://mlchart.com/terminology/oil-and-gas/pef/"
}