Laser tests

Status of laser tests technique

A well-defined and cheap method of detector testing is now available

Main benefits

Main features and capabilities

Deeper understanding of laser beam interaction with Si detectors

Other possible effects influencing laser tests

Containt of laser tests

Testing procedures of strip detectors

The test system integrates: ROOT based software allows:

Detail list of needed informations and laser tests for strip detectors

Mandatory:(M), recommended:(R)

  1. Testing structure (detector) (M)
  2. Readout: electronics and DAQ software, negative or positive charge collection (M)
  3. Simulation of response (R)
  4. Environment under control: temperature (M), cooling (M), humidity (R), special atmosphere (R), emergency system (M)
  5. Light source: semiconductor laser
    1. wavelength 650nm (R) (surface scans, charge generation up to 4um)
    2. wavelength 1050nm (M) (silicon bulk response, charge generation 4mm)
  6. Position system 2D (M), 3D+1R (R)
  7. Triggering system (R) (for real beta sources)
  8. Calibration tests of laser system:
    1. Mechanical stability (4.0um, 0.1deg) (M)
    2. Optical stabylity of beam to separate this effects (amplitude, timing jitter, noise) (M)
    3. Trigger system: scintilators, delay units (R)
    4. Focusing of laser (M)
    5. Absolute reflectivity measurement (R)
  9. Standard tests of detector without laser:
    1. IV curve (M)
    2. noise scan (M)
    3. response curve scan (M)
    4. time walk scan(M)
  10. Laser beam tests of detector:
    1. Perpendicular response scan (M)
    2. Different charge injection scan (0 - 10 fC) (M)
    3. Bias scan (depletion voltage measurement) (M)
    4. Pulse shape scan - measurement of pulse shapes for injected charge ranging from fractions to thousands MIPs (M)
    5. Interstrip scans of efficiency and cluster size measurements (M)
    6. Surface charge generation scan (R) (check efficiency and timing of collection of charge from surface space - checking of detector design, electrical fields close surface, charge losses)
    7. Cluster size scan (M)
    8. Efficiency scan (signal / noise ratio) (M)
    9. Injection of extra large charge for regeneration time measurement or assessment of electronics damage (R)
    10. Measurement of high-rate charge injection (double pulse) (R)
    11. Thickness homogeneity of sensor with precision in about 100nm sensitivity (R)
  11. Points 9. and 10. repeat for irradiated modules with different dose, different irradiated components (M)
    1. Simulation of response of irraditad module, additional diffusions, inhomogeneities (R)