Excellent PhD theses 2014

The PhD Awards 2014 of the Excellence Cluster Universe go to the experimental works of Tobias Prinz and Jonathan Bortfeldt from the Ludwig-Maximilians-Universität. Jonathan Bortfeldt has refined a detector technique used in many particle physics experiments nowadays in a way that it significantly expands the application range of the detector. The Excellence Cluster Universe PhD Award was officially given to Jonathan Bortfeldt during the Science Week 2014 in last December. The second awardee, Tobias Prinz, has explored the X-ray-emissions of supernova remnants of massive stars gaining important new insights. Being currently abroad, Tobias Prinz will receive his award in spring 2015.

About the work of Tobias Prinz
In his thesis "Exploring the End States of Massive Stars using X-ray emission of neutron stars and supernova remnants", Tobias Prinz investigated the radiation properties of supernova remnants of massive stars in the X-ray-range. The first part of his work is dedicated to the object Puppis-A in the constellation Puppis, one of the brightest spots in the sky in an X-ray telescope. For the first time, his measurements give clear evidence that the object Puppis-A is a remnant of a stellar explosion. Tobias Prinz also could determine the movement speed of Puppis-A with unprecedented accuracy, and subsequently estimate its age. His result differs significantly from the values previously published and shows that Puppis-A seems to move much slower than previously thought.

Based on the ROSAT all-sky survey and data from XMM-Newton and Chandra, Tobias Prinz could also clearly identify two objects as supernova remnants out of a group of 200 supernova candidates, which he examined in detail. Furthermore, Tobias Prince investigated the X-ray properties of pulsars. He discovered a total of 18 pulsars that were previously not known to emit X-rays.

"The results of Tobias Prinz represent a significant contribution to the research of radiation properties of supernova remnants. For his outstanding work Tobias Prinz is awarded the Universe PhD Award 2014", says Prof. Dr. Joachim Trümper on behalf of the PhD Award Committee.

On Jonathan Bortfeldt's thesis
In his thesis "Development of Floating Strip Micromegas Detectors" Jonathan Bortfeldt presents a new design for a gas detector. Micromegas detectors are used in various particle physics experiments, because they accurately measure particle tracks even at very high rates. However, the efficiency of the detector is limited by unavoidable high voltage discharges that cause detector downtimes.

Jonathan Bortfeldt’s approach combines the advantages of the traditional with the "resistive strip" design that significantly reduces the impact of discharges: Here, the copper strips forming the read-out structure are individually supplied with high voltage, which restricts the effects of discharge to a small area of the detector, reducing the downtime by about two orders of magnitude compared to the conventional design. Jonathan Bortfeldt has developed three types of "floating strip" detectors and has examined and in detail characterized their behaviour under different irradiation scenarios.

"For his impressive, detailed and extensive work Jonathan Bortfeldt deserves the PhD Award 2014, said laudator Prof. Dr. Konrad Kleinknecht at the award ceremony in December 2014.