Our colleague and friend Per Olof has passed away after a very brief period of illness. Peo, as we all called him, played a key role in the field of neutrino physics, both nationally and in the international arena. He started his career with six years at CERN (1976-1982), and was coordinator and spokesperson for several neutrino experiments using bubble chambers. In the early 1990’s, he started the experimental particle astrophysics activities in Sweden, first hoping that a high-energy neutrino telescope could be built in the Torneträsk lake of northern Sweden. After realizing that the transparency of the lake water was not adequate for a large Cerenkov telescope, Peo led the Swedish effort in AMANDA, the neutrino telescope buried in the Antartic ice and the predecessor of IceCube. Peo was the first spokesperson of the IceCube collaboration in 2001-2005, at the crucial stage which included the first year of deployment at the Pole. IceCube quickly grew to be a world leading observatory, now using 5160 light sensors deep in the ice to look for the rare signals from astrophysical neutrinos. These were indeed discovered in 2013, a spectacular achievement and a great satisfaction for Peo, who remained a figure in the experiment, also after retirement. Peo’s commitment to Physics and enthusiasm for his work left no room for hesitation. He went to the remote experimental site at South Pole 11 times, and would have gladly gone there again and again. He was a constant source of inspiration for younger colleagues. We are proud to have had him as a colleague and friend. We will miss him dearly.
– Lars Bergström, Chad Finley, Ariel Goobar, Klas Hultqvist and Christian Walck on behalf of the colleagues at OKC.