An unusual and highly effective career started by physics: Tom Neff, 1943 – 2024

From the Stanford Physics Department Annual Newsletter 2024/25

Some of you may remember Tom Neff as a graduate student of Richard Blankenbecler and Sid Drell in the SLAC theory group. Tom received his PhD in 1973 with the thesis “Eikonal Methods and Absorptive Effects in Hadronic Production Processes” (SLAC preprint 156).

However, his foray in theoretical physics was soon replaced by work on nuclear non-proliferation and arms control, as an assistant to Sid and Pief Panofsky. In 1991, Tom was a Senior Researcher at MIT’s Center for International Studies when he came up with the idea of a deal whereby Russia would “downblend” a large amount of their highly enriched, weapon grade uranium and sell it to the US as reactor fuel.

In the immediate aftermath of the fall of the Berlin wall, in 1989, there was great concern that the breakup of Soviet Union and the resulting confusion and economic hardship, would result in nuclear weapons being lost, or that countries of the former Soviet Union would suddenly become nuclear powers. Great efforts were made by the US government to help account for Soviet weapons and, in fact, to return them to Russia.

Yet, there was another problem: Russia inherited a giant stockpile of uranium highly enriched in the isotope 235, as required for weapons manufacturing. In addition, and dangerously, Russia’s economy was in shambles, and, at some point, the Russian State could not even pay the salaries of the scientists and engineers working in the nuclear complex and, effectively, controlling the weapon’s material. Tom’s idea was essentially to pay Russia to undo their isotope enrichment work and dilute the so expensively concentrated uranium 235 into the much lower enrichment grade required for civilian power reactors. The ceramic samovar (right) branded “ECP” for ElectroChemical Plant, one of the soviet “Closed Cities”, near Krasnoyarsk, is meant to symbolize this process from the perspective of Russian tea-making!

Tom discussed this idea in an editorial in the NY Times (“A Grand Uranium Bargain”, Oct 24, 1991) and, over the years, worked to smooth out the many kinks in the way of making his idea a reality. See, for instance, W. Broad’s NY Times obituary “Thomas Neff, Who Turned Soviet Warheads into Electricity, Dies at 80”, 20 Jul 2024. The Highly Enriched Uranium Deal (HEU Deal), as the program became known, proceeded for many years, fueling US nuclear reactors on the cheap, while destroying weapon’s grade material and providing work for many Russian scientists and technicians.

But there is a less known coda to the HEU Deal: in the early 2000s, I was looking for a large amount (for the time) of xenon enriched to 80% in the isotope 136, which is present in natural Xe at only about 9% concentration. This had nothing to do with fissile materials and, in fact, the Xe was to be used in the EXO-200 neutrinoless double-beta decay detector, designed to investigate the quantum-mechanical structure of the neutrino, neutrino masses, and the puzzle of why there is way more matter than antimatter in the universe.

Somehow, I got in touch with Tom who readily introduced me to the right people in the Russian ex-closed cities where the isotope separation technology developed for uranium could be re-deployed to enrich Xe in the isotope 136. Tom and I took a first trip to Siberia together, visiting ECP in 2003. This and more trips I later took to UEP (Ural Electrochemical Plan, not too far from what is now Ekaterinburg-Sverdlovsk in Soviet times) resulted in the very successful procurement of the 200 kg of enriched Xe for EXO-200. At the time, this was the largest amount of any isotope ever produced for basic science!  EXO-200 ran at an underground site in New Mexico for about six years, establishing that the neutrinoless double-beta decay half-life is greater than 3.5×10  years (or 3.5×10  times the age of the Universe!). Alas, EXO-200 did not discover neutrinoless double-beta decay (if it had, by now you would know everything about it!)

The photo above shows Tom (extreme right) and a younger version of the author (next to him), along with a number of colleagues from ECP on a cruise on the Yenisei River in Siberia. These were very enjoyable trips, occurring at a happy time when there was real good will between Russia and the US. Indeed, Tom’s HEU Deal produced, as “extra credit”, trust, and a preferential channel of communication between scientists and technologists from the two sides. This facilitated other interactions and, indeed, was further fed by such interactions. It is regrettable that current events have all but killed such channels with Russia, and political expedience has prevented the development of similar channels with China.

Tom was very modest about his achievements and liked to say that the moral of his story is “that private citizens can actually do something” and that there are great advantages in academics talking directly to colleagues abroad, without the formality and the lack of imagination of the federal government.  He was clearly right, but I would add the other moral: “an education in physics can serve you well in life, no matter what you may end up doing”.

-- G. Gratta, With thanks to Sandy Fetter and Michael Turner who shed some light on Tom’s PhD work at Stanford.