by Virginia Greco. Published: 10 November 2017

Alexander is a PhD student at GSI and a member of the ALICE TPC upgrade group. While writing his thesis, due by the end of November, he had his first shift as Run Manager.

After three years spent at CERN working on the Time Projection Chamber (TPC) upgrade, Alexander Deisting has gone back to his home institution, GSI in Darmstadt (Germany), to finalize his PhD thesis. Recently he returned for a short time and covered his first shift as Run Manager in the ALICE control room.

Alexander studied physics at the University of Bonn and completed his Master’s course with a thesis on the improvement of background suppression in one of the gaseous detectors of the CERN Axion Solar Telescope (CAST) experiment.

Then he enrolled in the PhD programme of GSI, where he found he could do a thesis on hardware, building on his previous experience with gaseous detectors. He entered the ALICE experiment and joined the group working on the upgrade of the TPC for the Run 3, which will start in 2021 after the long shutdown of the LHC. The accelerator will then provide lead-lead collisions at a higher interaction rate (50 kHz); to exploit these the TPC will be equipped with new readout chambers, based on stacks of gas electron multiplier (GEM) chambers, which will allow for continuous readout and guarantee a performance as high as that achieved with the current TPC. In order to ensure that these chambers are stable while  operated at the LHC, studies of the discharge behaviour were performed. Alexander carried out these tests, inducing discharges in prototype detectors, equipped with one or two GEMs. He also tested various gas mixtures  to investigate the ion mobility and, thus, the space charge density of positive ions in the drift chamber of the detector. He compared the results of these measurements with simulations that he realized using the software tools ANSYS and Garfield. “I enjoyed the atmosphere both at GSI and in ALICE,” comments Alexander. “I like that in such a large collaboration you have a continuous turnover, with new people joining and bringing in new ideas and fresh perspectives. I think this is very positive for the experiment.

During these years at CERN, Alexander has also got familiar with the ALICE Run Control Centre, where he has covered the role of Shift Leader and, now, of Run Manager. “I enjoyed more the experience as Run Manager, since this role gives you more flexibility. You have to keep an eye on everything, but you can also work on your research or go home when everything is running smoothly. On the contrary, the shift leader has to sit in the control room and keep his attention on the run even when nothing special is happening. Of course, it is better when no problems occur, but it can be boring.

Alexander has now taken a break from work because he has to focus on the writing of his thesis, which has to be submitted by the end of the month, even though the defence will not happen before February. “Once the PhD is concluded,” he explains, “first of all I will take some vacations, thing that I didn’t do after my Master’s degree. Then, I will look around for a postdoc position.” For the moment, he wants to remain in the research field; he is not attracted to industry, business or finance. He might stay in ALICE, since there is still a lot to do for the upgrade of the TPC, but he might also consider other opportunities, in particular since he would like to be able to work and live in the same region as his girlfriend.

He has taught only a little up to now, but he will probably have to do it more if he goes for a postdoc. “I think it can be interesting, but I also know that doing research and teaching at the same time is complicated. They are competing activities in terms of time allocation, in particular considering that I would need to prepare the lessons. I would probably get stressed trying to keep up with both things and obtain satisfactory results in both.

During his spare time, Alexander likes to go running, taking photos or bouldering, but in these days all his energy is drawn by finishing his thesis.