IFAE People

My name is Dr. Thorsten Lux and I am senior researcher at Institut de Física d’Altes Energies (IFAE).

Originally from Lüneburg (Germany) where I was born in 1974, I followed in 1996 my scintific interests and started to study physics at the University of Hamburg, Germany.

Since particle physics was also a highly interesting topic for me, I first became a CERN summer student in 1999 and afterwards I started my diploma thesis in 2000 in the research group of Prof. Dr. Heuer at DESY. At that time the R&D about the usage of Micro Pattern Gas Detectors (MPGD) for the readout of time projection chambers (TPC) started in the framework of the linear collider project TESLA/ILC. The topic of my diploma thesis was the design, construction and commissioning of a setup for measurements of the ion-feedback in a triple Gas Electron Multiplier (GEM) system.

This was the starting point for me to work with gaseous detectors, a field in which I am still involved after more than 15 years in which I slowly expanded my expertise to more and more different kind of gas detectors.

From October 2001 to June 2005, I was continuing to work in the same research group as PhD student. The thesis consisted of two topics. The instrumentation part of the thesis was about the construction of a prototype TPC which afterwards I used to take data in a superconducting 5 T magnet at DESY, while the analysis part was about data taken with the H1 detector at the ep accelerator HERA at DESY. I studied the semi-muonic decay channel of the b-flavoured hadrons : ep-> e bbar X-> e muon j (j) X'.

In summer 2005 I started to work as PostDoc with the neutrino group at the Universitat Autonoma de Barcelona (UAB), Spain. The topic of my work was again related to gas detectors, this time aiming on the construction of the first full size TPC with MPGD ever built for a phycis experiment. The idea was to use 3 TPCs as central tracker of the near detector of the long baseline oscillation experiment Tokai-To-Kamikande, T2K. After a short but intensive R&D phase to define the final detector design, I contributed to the quality control of the MicroMegas (MM) readout modules and other design aspects of the experiment.

From 2008 on I worked at IFAE on a Double Beta decay experiment. The project opened me the possibility to extend my knowledge about gas detectors from two points of view: 1) for the first time I worked with gas detectors operated at pressures above ambient pressure and 2) instead of using a MPGD based readout, we studied the possibility to use an electroluminescence (EL) readout based on APDs as light sensors.

Since 2015 I am not senior researcher at IFAE. Now as Co-PI of the neutrino and instrumention group, I am working again on T2K, this time on the upgrade of the detector we had installed 10 years ago and of course again on TPCs. I am also involved on a double phase (DP) liquid argon (LAr) TPC development in the framework of the next generation neutrino oscillation project, DUNE. Beside of these fundamental physics projects, I am also working on smaller projects in the field of applied physics. More details on my current projects can be found in the tab “Research”. Outreach is another field in which I am active.

Research Topics:

• Experimental Physics
• Neutrino Physics
• Instrument Development

My research is currently focussed on the development of on detectors for current and future neutrino oscillation experiments: Tokai-To-Kamiokanda (T2K) and WA105/ Deep Underground Neutrino Experiment (DUNE). Beam neutrino oscillation experiments are based on a set of at least 2 detectors: a near detector located close to the production point of the neutrinos and a far detector in a distance where the oscillation probability for the neutrinos is maximal. The aim is to measure the flavor of the neutrinos before oscillation and the flavor when the oscillation is maximal.

T2K

T2K is situated in Japan. An intense beam of muon neutrinos is generated at the J-PARC nuclear physics site on the East coast of Japan and directed across the country to the Super-Kamiokande neutrino detector in the mountains of western Japan. The beam is measured once before it leaves the J-PARC site, using the near detector ND280, and again at Super-K. The IFAE neutrino group is involved since 2005 in the near detector, ND280, of T2K. ND280 consists of a set of targets and sub-detectors to reconstruct the neutrino interaction events. A key element of ND280 are the 3 TPCs used to measure the tracks of the charged particles and to identify these via their dE/dx deposition. At IFAE we were involved in the R&D for the detector design, the construction and commissioning of the final detectors and the analysis of the data taken with ND280 over the last years. Currently design studies are ongoing to optimize ND280 for the T2K-II phase. The main change will be the introduction of 2 new TPCs which will be installed horizontally above and below of a plastic scintillator target. IFAE is involved in the development of these TPCs from the mechanics point of view. The challenge is here to develop walls which are thin, light, gas tight and stable against deformations under pressure. The overall integration of all new sub-detectors into ND280 is another field I am working on. The TPCs will be installed in ND280 in 2021. However, to ensure that the final TPCs fulfill all requirements, a prototype will be constructed in 2018 and tested in a suitable testbeam.

DUNE

While T2K is an experiment currently running and which will continue to run until around 2024, the preparation for the next generation long baseline experiments are already ongoing. This next generation promises to be more sensitive than current experiments and thus will allow to give a deeper view into the nature of neutrinos. One of the options is DUNE. As far detector for this experiment 4 liquid argon (LAr) TPCs filled with 10 kton each are foreseen. The first TPC is supposed to start data taking around 2026. IFAE is participating in the R&D related to the Dual Phase (DP) LAr TPC. In this detector concept the neutrino interaction happens in the LAr. The ionization electrons released in the LAr by charged particles produced in the interation, are drifted with an electrical field towards the anode. However, the anode is not immersed the LAr so that the electrons first have to be extracted from the LAr to the gaseous phase. In the gaseous, before reaching the anode, the ionization electrons are multiplied by a MGPD amplification stage. The amplified electron signal is detected by the segmented anode and allows the 3D reconstruction of the event. However, to determine the absolute z position of the interaction, the drift time of the electrons has to be known. This time can be measured by exploiting the fact that in the ionization process, not only electrons but also light, the so-called primary scintillation light, is produced. The Spanish research groups from CIEMAT and IFAE are working together on the development of a suitable light detection system based on PMTs for this light as also the calibration system to ensure its quality control while installed in the LAr TPC. The detector concept is tested with large prototypes. A detector of 3x1x1 m3 is currently operated at CERN. A larger prototype, protoDUNE-DP or WA105, is foreseen to be commissioned in 2018 at CERN.

Selected publications:

• Long-Baseline Neutrino Facility (LBNF) and Deep Underground Neutrino Experiment (DUNE) Conceptual Design Report, Volume 4 The DUNE Detectors at LBNF Jan 2016 [arXiv]

• A noble gas detector with electroluminescence readout based on an array of APDs Bourguille, B.; Garcia Soto, A.; Gil-Botella, I.; et al. Journal of Instrumentation Volume: 10 Published: DEC 2015 [Link]

• Development and characterization of a multi-APD xenon electroluminescence TPC Lux, T.; Garcia Soto, A.; Ballester, O.; et al. Journal of Instrumentation Volume: 10 Published: MAR 2015 [Link]

• LBNO-DEMO: Large-scale neutrino detector demonstrators for phased performance assessment in view of a long-baseline oscillation experiment Published: 2014 [arXiv]

• Characterization of the Hamamatsu S8664 Avalanche Photodiode for X-Ray and VUV-light detection Lux, T.; Freitas, E. D. C.; Amaro, F. D.; et al. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Volume: 685 Pages: 11-15 Published: 2012 [Link]

• Time projection chambers for the T2K near detectors Abgrall, N.; Andrieu, B.; Baron, P.; et al. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Volume: 637 Issue: 1 Pages: 25-46 Published: 2011 [Link]

• A study with a small prototype TPC for the international linear collider experiment Ackermann, K.; Arai, S.; Arogancia, D. C.; et al. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Volume: 623 Issue: 1 Pages: 141-143 Published: 2010 [Link]

• Secondary scintillation yield in high-pressure xenon gas for neutrinoless double beta decay (0νββ) search Freitas, E. D. C.; Monteiro, C. M. B.; Ball, M.; et al. Physics Letters B Volume: 684 Issue: 4 Pages: 205-210 Published: 2010 [Link]

• Large bulk Micromegas detectors for TPC applications Anvar, S.; Baron, P.; Boyer, M.; et al. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Volume: 602 Issue: 2 Pages: 415-420 Published: 2009 [Link]

• The NEXT experiment Diaz, J.; Yahlali, N.; Ball, M.; et al. Fourth Symposium on Large Tpcs For Low Energy Rare Event Detection Volume: 179 Published: 2009 [Link]

• Bulk micromegas detectors for large TPC applications Bouchez, J.; Burke, D. R.; Cavata, Ch; et al. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Volume: 574 Issue: 3 Pages: 425-432 Published: 2007 [Link]

• Measurement of beauty production at HERA using events with muons and jets Aktas, A; Andreev, V; Anthonis, T; et al. European Physical Journal C Volume: 41 Issue: 4 Pages: 453-467 Published: JUN 2005 [Link]

Selected outreach activities:

• Design and Construction of a Cloud Chamber for Outreach
  I built a cloud chamber based on an aquarium and operated with dry ice which easily can be assembled and disassembled, thus making it useful for science fairs for the general public. Dec 2016 - Jul 2017

• Design of a Multi Wire Proportional Chamber (MWPC) for Outreach
  I participated in the design of the mechanics and electronics of a MWPC detector for outreach events. The challenge was to develop a detector which is cheap enough that even schools can allow to construct one or more of these. Dec 2016 - Jul 2017

• “Bojos per la Fisica” Programme
  A programme addressed to high school students Apr 2017

• “Ciencia entre Tots” Fair
  Science fair for high school students in Girona in which, among others, we presented the cloud chamber Apr 2017

• “Bojos per la Fisica” Programme
  A programme addressed to high school students Sep 2016

• “Beam for Schools”
  Supporting a high school from Mataro, Spain, to prepare a proposal for the “Beam for Schools” call from CERN Sep - Dec 2016

• “Ciencia entre Tots” Fair
  Science fair for high school students in Girona in which, among others, we presented the cloud chamber Apr 2016

• “Ciencia entre Tots” Fair
  Science fair for high school students in Girona in which, among others, we presented the cloud chamber Apr 2015

• “Festival Ciencia” Fair
  Presenting the cloud chamber and poster at the general public science fair organized in the Parc de la Ciutadella, Barcelona May 2014

• Fundamental Physics Breakthrough Prize

As member of the T2K collaboration for studying the physics of neutrino oscillation 2016