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DIAGNOSIS DEVELOPMENT

Experiments with Z/Z-Beamlet/Z-Petawatt achieve conditions which push the limits of technology and scientific understanding. Accordingly, conventional instruments are often not sufficient to manipulate or analyse essential details of the experiment. One of the mission relevant branches of research is therefore to develop diagnostics for experiments at extreme temperatures, high densities, or in general high energy density.

A well established and successful field of diagnostic research is the generation of x-rays and their application for radiography. The latter context is also a motivation to investigate the generation of intense proton beams. However, as a variety of radiation and particles are generated, several diagnostics are developed or improved to fit experimental needs The following table shows a selection of projects.

  X-ray CCD spectrometer Magnetic electron spectrometer
Sketch
Subject of diagnostic Detection of γ- and X-rays:
  • conversion efficiencies
  • temperatures
Detection of electrons:
  • focal intensities
  • conversion efficiencies
  • spatial distribution*
Underlying concept Histogram of single photon counts:
Different photon energies generate different CCD-pixel intensities
Lorentz force deflection:
Electrons of different energies are deflected to different locations
Detector X-ray CCD and computer Various choices:
  • Diode array
  • Imaging plate
  • X-ray film
  • Radiochromic film (RCF)
Range 10 ev - 50 keVº 0.8 MeV - 20 MeV
Major benefits
  • high spectral range
  • possibly 1D or 2D spatially resoved spectra³
    (if sensor size allows)
  • high energy resolution
  • compact setup
  • high repetition rate
    (with diode array)


  Absorbtive electron spectrometer Faraday cup
Sketch sheeba
faraday
Subject of diagnostic Detection of electrons:
  • focal intensities
  • conversion efficiencies
  • spatial distribution*
Detection of particle currents:
  • space charge
  • charge neutralization
  • acceleration processes
Underlying concept Material transformation by energy deposition:
Electrons of different energies are stopped in different depths of material. The detector material forms color centers when absorbing energy.
Ref.: SHEEBA detector
Capacitive accumulation of electronic charge
Detector Radiochromic film (RCF) Oscilloscope
Range 0.1 MeV - 20 MeV¹ 0 - 100 MeV²
Major benefits
  • robust setup
  • compact setup
  • possibly 1D or 2D spatially resolved spectra³
  • high repetition rate
  • robust setup

 

*: Multiple instruments or multiple shots at different positions allow to quantify the spectral distribution of electrons in dependence of their emission angle. This is crucial for the investigation of acceleration processes.
º: The lower edge is dependent on the signal to noise ratio of the CCD. A very well cooled CCD should be able to detect very low energies with single photon incidence. The upper edge is dependent on the CCD material and its electronic stopping power: If the photon is too energetic, it will eventually penetrate the sensor.
¹: Depending on the number of layers and the material of the shields between the RCF sheets, there is no upper limit for electron energies.
²: Very high electron energies lead to cascading effects or penetration through the detector. For high energies filtering and calibration will be neccessary.
³: This will work for sufficiently high radiation fluxes in conjunction with imaging slit or pinhole.

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