The Hans Tausen drill: design, performance, further developments and some lessons learned

In the mid-1990s, excellent results from the GRIP and GISP2 deep drilling projects in Greenland opened up funding for continued ice-coring efforts in Antarctica (EPICA) and Greenland (NorthGRIP). The Glaciology Group of the Niels Bohr Institute, University of Copenhagen, was assigned the task of providing drilling capability for these projects, as it had done for the GRIP project. The group decided to further simplify existing deep drill designs for better reliability and ease of handling. The drill design decided upon was successfully tested on Hans Tausen Ice Cap, Peary Land, Greenland, in 1995. The 5.0m long Hans Tausen (HT) drill was a prototype for the ~11m long EPICA and NorthGRIP versions of the drill which were mechanically identical to the HT drill except for a much longer core barrel and chips chamber. These drills could deliver up to 4m long ice cores after some design improvements had been introduced. The Berkner Island (Antarctica) drill is also an extended HT drill capable of drilling 2 m long cores. The success of the mechanical design of the HT drill is manifested by over 12 km of good-quality ice cores drilled by the HT drill and its derivatives since 1995.

Book Reviews: Unveiling the atom

Abraham Pais, Niels Bohr’s Times, in Physics, Philosophy and Polity . Clarendon Press, Oxford, 1991. Pp. xvii + 565, £25.00. ISBN 019-85204-92 In 1982 Abraham Pais produced his much-acclaimed biography of Albert Einstein, entitled Subtle is the Lord .... Pais has now produced what is in effect a companion volume on Niels Bohr. The new book is planned on similar lines to the Einstein volume. Meticulously researched, biographical detail is interleaved with very clear and accurate presentations of the relevant physics, and interspersed with Pais’s own personal recollections and assessments. As with Einstein, Pais knew Bohr well in later life and so is ideally qualified to undertake both these biographies. In one of the most interesting sections of the new book, Pais compares and contrasts these two dominant figures in twentieth- century physics. Both were ‘possessed if not obsessed’ by physics, as Pais puts it. Einstein’s spectrum of scientific activities was the broader, comprehending, of course, statistical physics and quantum theory as well as relativity, while Bohr concentrated almost entirely on quantum theory and its ramifications. But there were two striking differences. Bohr identified very strongly with his native Denmark, and created a major research school in Copenhagen, the famous Niels Bohr Institute. Although he never supervised PhD students as such, he did his best work in endless discussion with the stream of visitors and research workers at the Institute. By contrast, Einstein never identified with any particular country, living and working in many different places, and although he had quite a number of collaborators on an individual basis, he never in any sense created a research school.