Obituary of Torben Huus

The Danish physicist, Torben Huus, has died, aged 86, on August 31, 2006. Throughout his carrier he was employed at the Institute for Theoretical Physics of Copenhagen University (later, The Niels Bohr Institute) of which he became the director during the period 1976-1980. Torben’s main field of research was experimental nuclear physics. He will be especially remembered for his decisive contribution to the discovery in 1953 of the Coulomb excitation reaction, whereby the intrinsic motion of the nucleus is affected by the electric field of a passing projectel. The possibility of such reactions had been theoretically discussed, but in the known experiments this process was inseparable from reactions involving the much stronger short range nuclear forces. On learning about new theoretical studies Torben realized that background radiation that he had seen in experiments carried out at Cal Tech in which a target of a light element had been mounted on a tantalum backing might h! ave been produced by Coulomb excitations of a known level in 181Ta. In fact the bombarding energy (2.7 Mev protons) was well below the Coulomb barrier for Ta(Z=73). Torben could immediately confirm this conjecture in a new experiment* carried out in Copenhagen in collaboration with the Yugoslav physicist Črtomir Zupančič. The experiment verified the theoretical excitation function as given by K.A. Ter-Marterosyan (Leningrad) and K. Alder and A. Winther (Copenhagen), and revealed a second excited state which confirmed the rotational character of the excitations of 181Ta. These discoveries opened a fruitful field in the study of atomic nuclei, which remains as a valuable tool in nuclear spectroscopy.

Torben became director of the Niels Bohr Institute during a period with changing institutional structure and new administrative rules involving the total membership of the Institute including students. He was remarkably successful in guiding the Institute through this period as a result of his recognized objectivity and the respect and confidence shown him from all sides. His disarming humor often helped to break the ice in difficult negotiations.

*T. Huus and Č. Zupančič, Dan.Mat.Fys. Medd. 28 no. 1 (1953)