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Achim Stahl

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Nationality: German
Date-of-birth: Sept. 14th 1962, married, 2 children

Current Position since Dec. 2004

Chair
III. Physikalisches Institut B
RWTH Aachen University

Research Interests:

  • CMS-Experiment:
    Data-analysis with tau leptons
    Operation of the CMS tracker
    R&D for phase-2 upgrade
    Operation of a Tier-2 and a national Tier-3 grid-station
  • Neutrino Physics: mass hierarchy and CP-violation with DoubleChooz, T2K and JUNO.
  • CP-Violation: search for electric dipole moments of protons and light ions with an electrostatic storage ring. A future project at FZ Jülich with the COSY storage ring.
  • Medical Physics: radiation therapy, GEANT4 simulations, measurements of nuclear cross sections, treatment planning for movable tumors.

I am the chair and director of the institute with approximately 70 scientists, engineers and administrators. I am PI of the CMS group, the institute’s largest project. I am also involved in some of the neutrino projects.
Since July 2012 I am the national representative of Germany in the CMS collaboration and spokesperson of the BMBF research focus FSP-102 “Particle Physics with the CMS experiment” (see http://www.fsp102-cms.de/)
In recent years a close collaboration between RWTH Aachen University and the nearby HGF research center FZ Jülich developed under the name JARA (Jülich Aachen Research Alliance). I am founding member and current director of the JARA section FAME focusing on CP-violation and the matter–antimatter asymmetry in the universe.
In 2013 I was awarded the title distinguished professor at the RWTH Aachen University as one out of currently four distinguished professors in Aachen.

Hardware experiences:
Construction of a CMS tracker endcap. Development, construction, and operation of the trigger and timing system of the DoubleChooz experiment. Time-of-flight spectrometer and calorimeter for measurement of nuclear cross sections for medical phyiscs.

DESY Feb. 2001 - Nov. 2004

Leading scientist
Head of TESLA research group @ DESY-Zeuthen

Research Interests:

TESLA-project (later ILC), data-analysis and detector R&D, accelerator physics

  • Instrumentation of the very-forward region, beam-strahlung and beam monitoring, luminosity measurement, beam backgrounds.
  • Development of a source of polarized positrons, test experiment E166 @ SLAC.
  • Physics case and technical challenges of a gamma-gamma collider within the TESLA project.

Hardware experience:
Transmission polarimeter for E166. Diamond sensors for the TESLA beam calorimeter.

University of Bonn Oct. 1992 - Jan. 2001

Postdoc and research assistant
with Prof. Norbert Wermes, OPAL experiment.
Scientific associate at CERN from Nov. 1999 to Oct. 2000

Research Interests:

  • Major contributions to the data analysis in tau physics. Supervision of 20 thesis from which 11 OPAL papers arose, i.e. the measurements of the strange and non-strange spectral functions and \(\alpha_S\), the limit on the mass of the \(\nu_\tau\), searches for CP-violation in the \(\tau\)-production, or the first test of CPT from the mass of \(\tau^+\) and \(\tau^-\).
  • Introduction of the likelihood method for particle identification in OPAL tau physics and many other areas in OPAL.
  • Transfer of the \(\tau\)-identification tools from LEP-1 to the SUSY searches at LEP-2 while scientific associate at CERN.
  • Major update of the Monte Carlo simulation of the preshower endcap detector (PE)

Venia Legendi
Habilitation with a book on “\(\tau\)-lepton physics” submitted in 1998 and published as a separate volume in Springer Tracts in Modern Physics. Awarded the title “Privatdozent” in July 1999.

Hardware experience:
R&D on BaF crystals for a \(\tau\)-charm factory detector.

SLAC Mar. 1996 - Feb. 1998

Feodor-Lynen fellow of the Alexander-von-Humboldt Foundation
Postdoc with Group E in BaBar (Prof. Rafe Schindler and Prof. Marin Perl)
On leave of absence from University of Bonn.

Research Interests:

  • Coordination of the mechanical construction and integration of the barrel of the BaBar CsI(Tl) calorimeter. The calorimeter was built during these two years by a team of two engineers, ten technicians, some students and me.
  • In parallel some work on \(\tau \)-lepton physics (CP-violation) with SLD.

Hardware experience:
CsI(Tl) crystals, large scale detector construction. Mechanics, electronics, cooling.

University of Heidelberg – PhD Mar. 1989 - Feb. 1993

Graduate student
Supervisor: Prof. Klaus Tittel, ALEPH experiment
Research stays at CERN for trigger operation: Jul. 1989 – Dec. 1999 and Apr. – Jul. 1991

Research Interests:

  • Analysis of the decay \(\tau\rightarrow\mu\nu\nu\). Measurement of the \(\tau\) polarization, branching ratio, Michel parameters and a search for lepton number violating \(Z \rightarrow\tau\mu\) events.
  • Installation and operation of the ALEPH level-1 trigger. Development of a concept of redundant triggers for all major Z-decay channels and first determinations of the trigger thresholds and efficiencies.

PhD:
Title of the thesis “Installation, optimization and analysis of the ALEPH event trigger and investigation of muonic decays of tau leptons”, accepted in Feb. 1993 with distinction.

Hardware experience:
Trigger systems, discrete electronics.

University of Tübingen – Diploma Oct. 1982 - Oct. 1988

Studies of Physics
Diploma in Physics with the optimal mark 1.0

Diploma thesis in atomic physics with Prof. Werner Nagel:
“Measurement of the momentum distribution of K-shell electrons in silver"

Further Responsibilities

  • National representative of Germany in the CMS collaboration
  • Member of the board of advisors of the particle physics section of the German Physical Society.
  • Member of the particle data group
  • Member of the Neutrino Strategy Group in the European Strategy Process at CERN
  • Referee for Physical Review Letters, Physical Review D, and Physics Letters
  • Referee for Deutsche Forschungsgemeinschaft DFG, German-Israeli Foundation GIF, Deutsche Studienstiftung, Alexander-von-Humboldt Foundation, Karl-Zeiss Foundation and others.
  • Member of the scientific advisory committee of the workshop on tau lepton physics since 2004. This is the major conference on tau lepton physics. I am organizing the upcoming 2014 conference in Aachen.
  • Teaching:
    • regular lectures on experimental physics, particle physics
    • coordinator of the international master program in physics
    • responsible for the advanced lab courses in particle physics
    • I supervised more than 50 PhD and around 100 diploma and master thesis

Publications

I am author / coauthor of approximately 750 refereed publications leading to an h-index of currently 64 (see http://www.researcherid.com/rid/E-8846-2011 for details).

The most important publications are:

  1. A. Stahl, “Physics with tau leptons”, Springer Tracts Mod.Phys.160 (2000) 1.
  2. S. Chatrchyan et al. [CMS Collaboration], “Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC”, JHEP 06 (2013) 081.
  3. K. Abe et al. [T2K Collaboration], “Indication of Electron Neutrino Appearance from an Acceleratorproduced Off-axis Muon Neutrino Beam”, Phys.Rev.Lett. 107 (2011) 041801.
  4. Y. Abe et al. [DoubleChooz Collaboration], “Indication for the disappearance of reactor electron antineutrinos in the Double Chooz experiment.”, Phys.Rev.Lett. 108 (2012) 131801
  5. J. Beringer et al. [Particle Data Group] “Review of Particle Physics”, Phys.Rev. D86 (2012) 010001.