A puzzle a day...
Barbara Warmbein (DESY), 26/11/2018
Uwe Kraemer (FLC, PhD). Image credit: DESY
With many deliverables achieved and a recent extension approval under their belts, scientists working on AIDA-2020 are going strong. The project has paved the way to quite a few small revolutions in detector development, such as the adoption of algorithms from small future to large current experiments, or the uniting of various detector communities, from hadron experiments to neutrinos. We, the On Track Editors, would like to introduce some of these researchers and their work.
This occasional series kicks off with PhD student Uwe Krämer, who works on a new-generation AIDA-2020 beam telescope, based at the German lab DESY in Hamburg. The telescope, part of Work Package 15 about the upgrades of beam and irradiation test infrastructures, will be the latest model of a series of beam telescopes in use at various labs. They will verify and validate data taken with prototype particle detectors and detector components in test beams; this telescope will be used in the DESY II test beam. Krämer is involved in the telescope’s development, construction and tests.
Originally from a small town near the German-French border, Krämer knew at a fairly early stage that he would choose an education in science. “I’ve always loved a good puzzle and the thrill of finding a solution to it,” he explains. “Physics is a lot like that, in particular when working on a hardware project like the beam telescope.” He studied physics at Karlsruhe Institute of Technology in Germany and, after a Master’s in astroparticle physics, he decided to go for a PhD in particle physics. That is how he came to DESY.
The technology and parameters for the beam telescope had already been chosen by that time, but he shaped its execution. Whereas the existing EUDET beam telescopes use pixel sensors as their detectors, the new one uses silicon strip sensors. They bring several advantages to the current telescopes: a much larger active area of 10 by 10 cm^2 (as opposed to 1 by 2 cm^2), better time resolution, lower power consumption and a lower heat production rate, which leads to less need for cooling systems.
One of the immediate next steps is the testing of and data taking, with a chip bonded directly onto the silicon strip sensor. The signals are routed through an additional metal layer to the chip on top of the sensor that is used for digitisation and readout. “We can read out a lot of channels through a small Kapton flex, instead of needing a large support PCB, as in a more typical strip sensor system. This allows us to save up on much needed space,” says Krämer. The step involves calibrating the chip, writing the analysis code – and putting all the pieces together to make the telescope work.
Uwe Krämer is also an avid gamer and, sometimes, the problem-solving skills he brings from physics feed right back into a tricky challenge in a game – and vice versa. “It’s also a way to experience a different world for a while,” he explains. He doesn’t only experience other worlds in computer games, though – and the bushy red beard he sports plays right into his hands for passion number two: live-action role play, or LARP. His older brother dragged him into this pastime, where people assume fictional characters, complete with costumes and toolkits. They meet for weekend conventions, acting as their characters, solving puzzles and other challenges.
Krämer is on the organising side of things; he helps with the logistics and the scenarios. He slips into different roles, so that others get the clues they need to get on with the game. He has been a Viking, a priest, a farmer or a bandit. His favorite character, however, is the bearded preacher of a doomsday cult called Rolosch. “I am actually quite optimistic in real life,” he grins, “so it’s fun to be the opposite of that when role-playing.” However, the only end that is currently nigh is that of his PhD, foreseen for next year.