Skip to content

142A/B/C Preamplifiers

ORTEC 142A 142B 142C Preamplifier
  • Optimum performance for (A) low-, (B) medium-, and (C) high-capacitance charged-particle or heavy-ion detectors 
  • Extremely low noise
  • Accepts 0 to ±1 kV bias
  • Separate fast-timing output signal with rise time from <5 ns
  • Operates in vacuum
  • Small size

The ORTEC Models 142A, 142B, and 142C Preamplifiers are low-noise, fast-rise-time, charge-sensitive preamplifiers designed for optimum performance with charged-particle or heavy-ion detectors.
  • Literature +

  • More Information +

    The Model 142A is optimized for extremely low noise and fast timing for detectors with capacitance up to 100 pF. This makes it the ideal selection for high-resolution alpha- and beta-particle spectroscopy applications.

    Model 142B is optimized for extremely low noise and fast timing for detectors with capacitance greater than 100 pF but less than 400 pF. 

    Model 142C is optimized for extremely low noise and fast timing for detectors with capacitance greater than 400 pF.

    These preamplifiers have a separate fast-timing output with pulse widths of ~50 ns and rise times ranging from less than 5 ns for 0 pF detectors to less than 20 ns for 1000 pF detectors. This timing output, when used in conjunction with  ORTEC's standard electronics, provides excellent time resolution; also, its fast-differentiated shape often permits direct coupling to the timing discriminator.

    The performance of many spectroscopy systems can be enhanced by these preamplifiers being able to operate in vacuum enclosures. This allows the input cable length to be minimized. The small size of the preamplifiers is of significant importance when operating in such enclosures due to the limited space available.
  • Specifications +

    Performance specifications apply to E output unless stated otherwise.
      Model     Detector Capacitance (pF)     Maximum Noise (keV) (Si)  
    Integral Nonlinearity ≤0.03%, 0 to ±7 V open circuit or ±3.5 V terminated in 93 Ω.
    142A  <±50 ppm/°C from 0 to 50°C.
    142B  <±100 ppm/°C from 0 to 50°C.
    142C  <±100 ppm/°C from 0 to 50°C.
    Open Loop Gain 142A  >40,000.
    142B  >80,000.
    142C  >80,000.
    Charge Sensitivity
    (Si equivalent)
    142A  Nominally 45 mV/MeV.
    142B  Nominally 20 mV/MeV.
    142C  Nominally 20 mV/MeV.
    Energy Range 142A  0–200 MeV.
    142B  0–400 MeV.
    142C  0–400 MeV.
    E2CRP Maximum energy-squared count-rate product:
    142A  2 X 107 MeV2/s.
    142B  5 X 107 MeV2/s.
    142C  5 X 107 MeV2/s.
    Rise Time (0 to 0.5 V
    pulse at E output
    on 93 Ω load)
    142A  <5 ns at 0 pF; <12 ns at 100 pF.
    142B  <5 ns at 100 pF; <25 ns at 1000 pF.
    142C  <11 ns at 400 pF; <20 ns at 1000 pF.
    Decay Time 142A  Nominally 500 µs.
    142B  Nominally 1000 µs.
    142C  Nominally 1000 µs.
    Range of Input
    142A  0 to 100 pF.
    142B  100 to 400 pF.
    142C  400 to 2000 pF.
    Detector Bias Voltage ±1000 V maximum.

    Accepts positive or negative charge input (normally from a semiconductor detector) from any type detector; BNC connector.
    Bias Accepts detector bias from bias supply and applies it to detector through the INPUT connector; maximum ±1000 V; SHV connector or ORTEC type C-38.
    Test Input for pulse generator to test and calibrate the system; BNC connector.
    Power Input power through 10-ft captive power cable from ORTEC main amplifier or ORTEC Model 4002P Portable Power Supply.

    Positive or negative linear tail pulse for energy measurement. BNC connector.
    T Negative or positive linear fast-clipped pulse for timing. This output is generated using an inverting transformer that differentiates the energy output. Its rise time ranges from <5 ns to <25 ns. BNC connector.

    Electrical and Mechanical
    142A  +24 V, 20 mA; –24 V, 10 mA; +12 V, 15 mA;  –12 V, 15 mA.
    142B  +24 V, 40 mA; –24 V, 10 mA; +12 V, 15 mA;  –12 V, 15 mA.
    142C  +24 V, 40 mA; –24 V, 10 mA; +12 V, 15 mA;  –12 V, 15 mA.
    Weight Net  0.32 kg (0.75 oz).   Shipping  1.25 kg (2.75 lb).
    Dimensions 3.81 X 6.10 X 13.3 cm (1.5 X 2.4 X 5.25 in.).

    Selecting 142A, 142B, or 142C
    To choose among Models 142A, 142B, or 142C:

    1. Find the depletion depth of your detector. If it is an ORTEC detector, the last group of 2 to 4 digits is the depth in µm.

    2. Find the depletion depth on the graph above and read the capacitance in pF/mm2 on the top of the chart.

    3. Multiply by the area of your detector in mm2. This is the middle 3-digit number for an ORTEC detector. Choose a Model 142A if the capacitance is less than 100 pF, a Model 142B if the capacitance is more than 100 pF but less than 400 pF, or a Model 142C if the capacitance is greater than 400 pF. Example: An ORTEC D-025-200-100 detector will have about 1 pF/mm2 for its 100-µm depletion depth. This, then, is 200 pF for the 200 mm2 area, and a Model 142B Preamplifier is preferred.
  • Ordering Information +

    Model Description
    142A Preamplifier (for 0 to 100 pF)
    142B Preamplifier (for 100 to 400 pF)
    142C Preamplifier (for 400 to 2000 pF)