Sie sind hier:


Dr. Bernard Riemann

Dr. Bernard Riemann

+49 (0)231 755-5302


Zentrum für Synchrotronstrahlung
Technische Universität Dortmund
Maria-Goeppert-Mayer-Str. 2
44227 Dortmund

Raum 72


Closed-Orbit Bilinear-Exponential Analysis

COBEA is an algorithm for studying betatron oscillations in storage rings, based only on closed-orbit response matrices and the trivial information of monitor-corrector ordering ("no lengths, no strengths") around the beam path. For more information, there is an IPAC paper [1] and my PhD thesis [2].

The cobea module for Python and its documentation can be downloaded at github [3]. Further usage of COBEA for orbit correction purposes is investigated by my colleague S. Kötter [4].

I have been thinking about orbit diagnostics since my Diploma thesis, and after a year or two, i was able to contribute an article [5] about a new diagnostics routine (which then evolved [6] and later became a sub-algorithm of COBEA).

Future Circular Collider (FCC) study

Computation of longitudinal and transverse resistive-wall impedances for the insertion regions [7].

Radio-Frequency (RF) cavities

I was able to contribute some ideas during the design process of the bERLinPro [8] and BESSY VSR [9] cavities. The idea of using cubic Bezier splines [10] has also been further investigated by my colleague B. Isbarn [11] and was mentioned in a systematical cavity study [12].


  1. B. Riemann et al.: "COBEA - Optical Parameters From Response Matrices without Knowledge of Magnet Strengths", in Proc. IPAC2017, MOPIK066, Copenhagen, Denmark (2017).
  2. B. Riemann: The Bilinear-Exponential Closed-Orbit Model and its Application to Storage Ring Beam Diagnostics, PhD Dissertation (TU Dortmund University, 2016). doi:10.17877/DE290R-17221
  3. cobea module for Python 3.6+ and 2.7+ (2017). Free software available at https://github.com/b-riemann/cobea
  4. S. Koetter et al.: "Status of the Development of a BE-Model-Based Program for Orbit Correction at the Electron Storage Ring DELTA", in Proc. IPAC2017, MOPIK065, Copenhagen, Denmark (2017).
  5. B. Riemann, P. Grete and T. Weis: "Model-independent and fast determination of optical functions in storage rings via multiturn and closed-orbit data", in Phys. Rev. ST Accel. Beams 14, 062802 (2011).
  6. B. Riemann et al.: "Two general orbit theorems for efficient measurement of beam optics", in Proc. IPAC2015, MOPWA035, Richmond, USA (2015).
  7. B. Riemann, "Resistive-Wall Impedance of interaction regions", presentation at EuroCirCol meeting, Geneva, Switzerland (2017).
  8. B. Riemann et al.: "First considerations concerning an optimized cavity design for the main linac of BERLinPro", in Proc. IPAC2011, MOPC080, San Sebastian, Spain (2011).
  9. B. Riemann et al.: "Axisymmetric Numerical Studies of Higher Order Mode Damping Techniques using Ring Ferrites for BESSY VSR", in Proc. IPAC2016, WEPOY059, Busan, Korea (2016).
  10. B. Riemann, A. Neumann and T. Weis: "Design of SRF cavities with cell profiles based on Bezier splines", in Proc. ICAP12, WEP14, Rostock, Germany (2012).
  11. B.D. Isbarn et al.: "Optimization of Multicell Microwave Cavities Using YACS", in Proc. IPAC2017, THPAB011, Copenhagen, Denmark (2017).
  12. V. Shemelin et al.: "Systematical study on superconducting radio frequency elliptic cavity shapes applicable to future high energy accelerators and energy recovery linacs", in Phys. Rev. Accel. Beams 19, 102002 (2016).