Photon marking system
A photon marking system is a system used in high-energy physics to generate high-energy photons with individually precisely known properties, in particular energy, time of origin and polarization. The photon energy is in the range of a few hundred MeV to a few GeV.
functionality
The starting point for photon generation is a high-energy electron beam from a particle accelerator . The electrons are made to emit a high-energy photon in the system, alternatively by generating bremsstrahlung on a target or by Compton scattering of photons from a laser . In the case of a single control event, the photon energy is almost equal to the energy loss of the electron involved. The residual energy of the electrons involved in a scattering process is measured in a spectrometer and the energy of the photon is calculated from this.
The photons generated are then used in an experiment, the detectors of which are connected in coincidence with the photon marking system. In addition, the photon generation system transmits each photon energy measurement value to the experiment.
Locations of bremsstrahlung photon marking systems
- Photons of up to 1.5 GeV can be generated at the Mainz microtron at the University of Mainz .
- The electron stretcher system at the University of Bonn generates linear and circularly polarized photons up to 3.5 GeV.
- A facility for generating linearly polarized 12 GeV photons is currently under construction at the TJNAF in Newport News .
Compton photon marking facility locations
- At the European Synchrotron Radiation Research Center ESRF in Grenoble , photons polarized by Compton backscattering of photons from an ultraviolet argon ion laser (351.2 nm corresponding to a photon energy of 3.53 eV) on the 6 GeV electron beam with a maximum energy of 1.47 GeV.
Web links
Individual evidence
- ↑ Crystal-Barrel @ ELSA experiments. Retrieved on February 13, 2010 (German).
- ↑ B1 Project Collaborative Research Center / Transregio 16, tagger. Retrieved February 13, 2010 .
- ↑ Design of a focal plane detector for the photon marking system at ELSA, diploma thesis. (Postscript; GZIP ; 4.9 MB) Kathrin Fornet-Ponse / University of Bonn , November 2004, accessed on February 13, 2010 (German).
- ↑ 12 GeV Upgrade Project, DESIGN SOLUTIONS DOCUMENT, The Hall D Detector. (PDF; 469 kB) Jefferson Lab, May 4, 2008, accessed on February 13, 2010 .
- ↑ GRAAL on BM7: Gamma-Ray Beam (page 30). ESRF , May 19, 1998, accessed February 14, 2010 .
- ↑ ESRF The beamlines. ESRF , February 4, 2009, accessed February 14, 2010 .
- ↑ Large AAL photon beam. June 8, 2004, accessed February 13, 2010 .