Nuclear Medicine Physicist - Expert

Mercor; San Francisco (CA); On-site; USD 120,000 - 170,000; Full time

Job summary

Mercor is assembling a panel of radiological safety experts to red-team frontier AI models. The goal is to test whether a model can correctly judge the misuse potential of a technical request — answering legitimate questions fully while refusing genuinely dangerous ones.

You will write prompts at three levels (benign, dual-use, adversarial), evaluate responses, and craft reference answers with clear reasoning for correct handling.

Qualifications

• Experience writing technical materials for specialized domains.
• Ability to judge misuse potential and justify judgments clearly.
• Familiarity with policy standards and evaluation frameworks.

Responsibilities

• Write prompts across three levels: benign, dual-use, and adversarial.
• Evaluate model responses against a defined policy standard.
• Draft reference answers with technical reasoning for correct handling.

Skills

Technical writing

Critical thinking

Policy evaluation

Education

Nuclear medicine or radiopharmacy background

Red-teaming or risk assessment background

Tools

GMP knowledge

Radiophysics equipment

Job description

About the work

Mercor is assembling a panel of radiological safety experts to red-team frontier AI models. The goal is to test whether a model can correctly judge the misuse potential of a technical request — answering legitimate questions fully while refusing genuinely dangerous ones.

You will:

• Write challenging single-turn prompts in your domain, labelled across three levels: benign, dual-use, and adversarial.
• Evaluate the responses that come back against a defined policy standard, and judge whether each was handled correctly.
• Write the reference answer — what a correct response looks like, and the technical reasoning for why.

This domain lives on the dual-use line more than most. The same isotope underpins cancer therapy and industrial radiography; the same shielding calculation protects a worker and conceals a source. A model that refuses a routine dose question is failing as badly as one that answers a question it shouldn't. Drawing that line reliably is why we need practitioners rather than generalists.

Background we're looking for

We're looking for people who produce and handle medical isotopes — the legitimate-use half of the dual-use line, held as a real custody responsibility. What matters most is being able to tell a routine professional question from one that's fishing for something else: the same activity and shielding figures that let a patient go home describe a source someone else wants to move quietly. You will be writing prompts that sit exactly on that line, then judging whether the model held it.

Examples of relevant backgrounds (ideally with red-teaming experience):

• Nuclear medicine or radiopharmacy physicist — therapy dosimetry, I-131, Lu-177 and Y-90 work, patient release criteria
• Cyclotron or radiochemistry facility RSO — target handling, PET isotope production, hot-cell operations
• Medical physicist with brachytherapy source custody — HDR and LDR sources, inventory and source exchange
• Radiopharmaceutical production and QC under GMP or an equivalent quality system
• Authorised Medical Physicist or Authorised User support on a medical radioactive materials licence

What this role demands beyond technical depth

This is writing-intensive work. Every judgment you make needs a written rationale that a non-specialist can follow. Prior technical writing, published research, or expert witness experience is a strong signal; please include a sample or link. You will also be reading and writing about misuse scenarios in your field for sustained periods. We brief experts on this in advance, and you can pause or step away at any point without penalty.

Before you apply

Your work here will not involve, and must not draw on, classified or export-controlled information, or anything covered by an NDA or prepublication review obligation. If you hold such obligations you may still be a good fit; tell us in your application and we will scope the work accordingly.