What to write?

I have struggled to write this blog. My small daily actions, what and how much I eat, how I manage my walk in the evening, my tough moments and my better moments, all assume great importance to me, but accounting for them is hardly the philosophy I promised. Friends ring, email and visit, though I tend to tire a bit with talking.

One dear friend of 40 years, Maurice Ormsby, proposed a solution to my philosophical problem in a wonderful long letter, finishing with the suggestion that I write to my grandchildren. My son suggested I write more, a sort of synopsis of my life with stories from the family. That also, I am now doing. And in starting this writing, I remembered that I had penned a brief account of my scientific life, published last year by OUP in a multi-author volume, improbably entitled "Diffusion MRI: Theory, Methods and Applications" and edited by Derek Jones. It was reprinted late last year, with permission from OUP, in Chemistry in New Zealand. I think it would be of interest to readers of my blog, and so, with indulgence from OUP, I will present it here in installments.

Part 1: Wanganui, Wellington and Oxford

I was born, and grew up in Wanganui, where physics seemed to surround me. I built my first crystal set radio while at primary school and was delighted to be able to pick up two radio stations. When I was 10 years old, Sputnik was launched, with many more satellites following, some of which could be seen at night with the naked eye, repeating their orbit after 90 minutes. In my early teens I was a boy chemist, with a backyard laboratory and pursuing adventures that would today be considered foolhardy at best, and criminal at worst. There was a 200-meter-long tunnel in a local hill that led to an elevator that allowed hilltop residents to avoid the 70-meter climb. It made wonderful echoes, over a second apart.

Among that mix of radio waves, molecules, echoes, and the evident triumph of the laws of physics may have been sown the seeds of a life in magnetic resonance (MR). Certainly I had never heard of it. I first came across MR as a final-year physics student at Victoria University of Wellington. But my interests then were in nuclear physics and solid-state physics. I discovered a field of research that combined them, the use of hyperfine interactions to orient radioactive nuclei. And so my doctoral ambitions took me, courtesy of a UK Commonwealth Scholarship, to the Clarendon Laboratory at Oxford University, where I joined the team of Nick Stone and grandfatherly mentor, Nicholas Kurti. There we used adiabatic demagnetization of paramagnetic salts to get down to 10 milliKelvin, at which temperature the hyperfine interaction would overwhelm the Boltzmann energy to cause radioactive nuclei in a ferromagnetic host metal, attached to the cold finger of the apparatus, to align, so directing their gamma rays preferentially along the quantization axis. The degree of orientation could be used as a measure of the interaction strength, so that nuclear magnetic moments or local fields could be measured. But by far the best way of precisely measuring that interaction was by sweeping an RF field in the vicinity of the Larmor frequency. At resonance, the gamma rays would suddenly change their angular distribution and the axial count rate would change dramatically.

So that was my introduction to magnetic resonance, a phenomenon detected through gamma emissions! It wasn’t until the last year of my DPhil that I came across Faraday detection and the mainstream. In 1973 I had the chance to go to a conference in Krakow, Poland, the 1^st Specialized Colloque Ampere. It was a most remarkable meeting and one that completely changed my professional life. I knew only one person there, Erwin Hahn, a regular Oxford visitor of Nicholas Kurti. Alex Pines presented his work, Proton Enhanced Nuclear Induction Spectroscopy. Peter Mansfield spoke about nuclear magnetic resonance (NMR) diffraction in solids. Someone asked if he had seen the paper by Lauterbur, Fourier Zeugmatography, which had just come out in Nature. And a young graduate student from the Ljubliana group, Metka Luzar spoke about using pulsed magnetic field gradients to measure diffusion in liquid crystals. I was fascinated. Many years later, in the early 1990s, I met up with Metka at an NMR meeting in Portoroz, on the tiny coastline of her Slovenian homeland. I sat down next to her and said: Metka Luzar, you changed my life. I am sure she thought me quite mad. Sadly, she died of cancer less than a decade later.