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Preamplifiers

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Model 2003BT Silicon Detector Preamplifier

Model 2003BT Silicon Detector Preamplifier

Description

The CANBERRA Model 2003BT charge sensitive FET input preamp is designed for optimum performance with Silicon detectors such as the CANBERRA Passivated Implanted Planar Silicon (PIPS®) detectors and legacy Silicon Surface Barrier (SSB)detectors. Operating as a charge to voltage converter, the unit accepts charge carriers produced in the detector during each absorbed nuclear event. The output then provides a voltage in direct proportion to the collected charge at the rate of 0.45 V per pC. This translates to a gain of 20 mV per MeV for room temperature silicon detectors.

For typical use with positively biased silicon detectors, the extremely linear energy output provides a positive polarity pulse ideal for energy spectroscopy. The coincident timing output provides a negative polarity fast differentiated pulse ideal for resolution of nuclear events in time.

The high charge rate capability of the design is evidenced by an energy rate capacity of greater than 2 x 106 MeV per second when used with silicon detectors. In order to take full advantage of such a high count rate capability, a main amplifier with a correspondingly high count rate ability, such as the CANBERRA Model 2025 or Model 2026, should be used.

The basic operation of the preamplifier is indicated in the functional schematic. The first stage acts as an operational integrator which produces an output potential proportional to the accumulated charge on the feedback capacitor Cf. The integrator drives the energy output directly. The timing output is derived from the integrator error signal through a pulse shaping network. Such an arrangement allows for the low noise and fast rise times, as in Table 1 (see spec sheet). To preserve pulse fidelity the energy output is buffered through a series terminating resistor of 93 Ω.

The preamplifier offers a noise contribution of only 2.0 keV, FWHM, Si, with a rate of increase with increasing input capacitance of ±10 eV per pF. All necessary power is provided by a CANBERRA main amplifier through the 300 cm (10 ft) compatible cable furnished with the preamp.

Model 2003BT Silicon Surface Barrier Detector Preamplifier

Features

  • Low noise design: less than 2.0 keV (Si) at 0 pF
  • High energy rate capability: up to 2 x 106 MeV per second
  • FET input, diode protected
  • Independent energy and fast timing outputs
  • Fast rise time less than 3 ns at 0 pF
  • Small size
  • Capable of operating in a vacuum chamber
Model 2004 Semiconductor Detector Preamplifier

Model 2004 Semiconductor Detector Preamplifier

Description

The CANBERRA Model 2004 charge sensitive FET input preamplifier was designed for use with both low and high capacitance semiconductor detectors. The preamp converts the charge carriers developed in the detector during each absorbed nuclear event to a step function voltage pulse, the amplitude of which is proportional to the total charge accumulated in that event. The output provides a positive polarity signal when used with detectors requiring positive bias and decays with a nominal time constant of 50 ms.

The high charge rate capability of the design is evidenced by a charge rate capacity of better than 2 x 10-7 coulombs per second, or 4.5 x 106 MeV per second for silicon detectors. In order to take full advantage of such a high count rate capability, a main amplifier with a correspondingly high count rate ability, such as the CANBERRA Model 2020, should be employed.

As shown in the functional schematic, the first stage acts as an operational integrator which produces an output potential proportional to the accumulated charge. This integrator is coupled to an output buffer stage through a pole/zero trim network. A feature of particular importance to certain users is a removable socketed resistor on the printed circuit board for disabling the pole/zero circuit. For low count rate applications using high leakage detectors, the resulting low frequency noise bandwidth may improve resolution.

The preamplifier offers a noise contribution of only 2.8 keV, FWHM, Si, with a rate of noise increase with increasing input capacitance of only 10 eV per picofarad, FWHM, Si. Conversion gains of nominally 9 mV per MeV or 45 mV per MeV (Si) may be selected by a jumper plug on the printed circuit board inside the unit.

In addition, the input circuit includes a protection network to prevent damage to the input FET from transient high voltage waveforms caused by sudden application or removal of detector bias, or a detector fault. All necessary power is provided by a CANBERRA main amplifier through the 300 cm (ten ft.) compatible cable.

Model 2004 Semiconductor Detector Preamplifier

Features

  • Low noise design: less than 2.8 keV (Si) at 0 pF
  • High charge rate capability: up to 4.5 X 106 MeV/sec
  • FET input, diode protected
  • Pole/zero select or defeat
  • High voltage operation up to ±2000 V dc
Model 2005 Scintillation Preamplifier

Model 2005 Scintillation Preamplifier

Description

The CANBERRA Model 2005 is a charge sensitive preamplifier which collects the charge output from scintillation/photomultiplier detectors for presentation to a pulse shaping main amplifier. For the typical application with input from the decoupled anode signal from a photomultiplier tube base, the preamplifier generates a positive polarity energy pulse output.

Functionally the unit operates as an integrator utilizing an operational type configuration by which the potential difference across the feedback capacitor is directly proportional to the charge accumulated from the detector input. The integrator is followed by a pole/zero cancellation circuit for optimum overload performance, and a differentiator to provide the 50 ms tail pulse. In addition, a buffer stage allows the Model 2005 to drive a long cable length without pulse degradation.

Charge conversion gains of nominally 4.5 or 22.7 millivolts per picocoulomb may be selected by a jumper plug on the printed circuit board inside the unit. Power for the unit is usually supplied from the associated main amplifier through the 3 m (10 ft) power cable provided with the preamp.

Model 2005 Scintillation Preamplifier

Features

  • Low noise design: less than 10-15 coulombs rms
  • High charge rate capacity (up to 9 mC/s) for high count rate applications
  • FET input, diode protected
  • Fast risetime: less than 15 ns
Model 2006 Proportional Counter Preamplifier

Model 2006 Proportional Counter Preamplifier

Description

The CANBERRA Models 2006 preamplfier is designed for use with proportional counter detectors. The preamp converts the ionization charge from the detector into a step voltage pulse whose amplitude is proportional to the total charge collected in each event. The pulse decays with a time constant of 50 ms for presentation to a main amplifier.

For typical use with a positive HV bias to the anode of the detector, the preamplifier generates positive polarity energy pulses which are shaped in the amplifier as necessary for counting or low energy x-ray analysis.

This preamplifier contains a diode-protected FET input stage optimized for low noise operation. The first stage acts as an operational integrator which produces an output potential proportional to the accumulated charge. This integrator configuration is followed by a pole/zero adjustment to return the unipolar pulse to a reference or baseline level without overshoot, and a differentiator to provide the 50 ms tail pulse. The second active stage operates as a buffer for driving various cable lengths without pulse degradation. Conversion gains of nominally 47 mV/M-ion-pairs or 235 mV/M-ion-pairs may be selected by a jumper plug inside the unit. The higher scale factor is especially useful for best signal-to-noise ratio in experiments involving low energy sources.

The noise level is equivalent to less than 350 ion pairs with zero source capacitance using 2 ms near-Gaussian pulse shaping, and degrades less than 1 ion pair per pF of input capacitance. As illustrated in Table 1, low noise and fast rise time prevail over a wide range of input capacitance. The high count rate capability of the design is evidenced by a charge rate capacity greater than 2 x 10-7 coulombs per second. In order to take full advantage of such a high count rate capability, a high count rate main shaping amplifier is recommended.

A test input is provided to assist in system setup. The test capacitor value is certified in the unit test report for reference use as a secondary charge calibration standard. The nominal voltage gain from the test output is X 1 for the output scale factor of 47 mV/M-ion-pairs and X 5 for the output scale factor of 235 mV/M-ion-pairs.

Power is supplied from the associated CANBERRA pulse shaping amplifier. The power lines are filtered within the unit to provide high noise immunity. A 3 m (10 ft) power cable is provided with the preamp.

Model 2006 Proportional Counter Preamplifier

Features

  • Low noise design: <350 ion pairs at Cs = 0 pF
  • High charge rate capacity for high count rate applications; up to 2 x 10-7 coulombs/second
  • FET input, diode protected
  • Fast risetime: <20 ns at Cs = 0 pF
  • High voltage operation up to ±2000 V dc
Model 2007B Scintillation Preamplifier

Model 2007B Scintillation Preamplifier

Description

The Model 2007B low-noise charge-sensitive preamplifier integrates the charge pulse from a PMT (decoupled from the anode) and converts it into a convenient positive voltage pulse output. The peak amplitude of each output pulse is linearly proportional to the total charge output of the PMT during each amplified photo event. The pulse is set to decay at a nominal 50 ms time constant, and interfaces directly with any of CANBERRA's spectroscopy amplifiers.

The 2007B generates a positive polarity output pulse in response to a typical input signal from a photomultiplier's decoupled anode. This amplifier features high voltage transient protection for a longer life in your lab, low noise contribution for better resolution and a rise time of less than 20 ns for use in timing applications.

Model 2007B Scintillation Preamplifier

Features

  • Low preamp power requirement ±12 V dc at 15 mA
  • Compatible with Accuspec NaI Plus
  • HV transient protection.
Model 2007/2007P Photomultiplier Tube Base/Preamplifier

Model 2007/2007P Photomultiplier Tube Base/Preamplifier

Description

The CANBERRA Models 2007 and 2007P are compact PM tube bases containing a high-voltage divider network to supply all necessary bias voltages for most common 10-stage PM tubes. A focus control provides for optimization of detector resolution and a gain control permits trimming the HV bias when several tubes must be matched for array setups.

Designed for compatibility with the CANBERRA Model 802 Series scintillation detectors, or equivalent, the tube base connects directly to the PMT, providing one integrally mounted assembly.

The Model 2007 includes high-voltage blocking capacitors to couple the anode and dynode signal outputs to a preamplifier, such as the CANBERRA Model 2005, or to a constant fraction discriminator, such as the CANBERRA Model 2129.

The Model 2007P includes a preamplifier which integrates the charge impulse from the anode of the PM tube to a pulse-shaping main amplifier, such as the CANBERRA Model 2020. The preamp features high-voltage transient protection, noise contribution less than 0.1 fC rms, and a rise time of less than 20 ns.

Model 2007/2007P Photomultiplier Tube Base/Preamplifier

Features

  • Mounts directly on photomultiplier tube (PMT)
  • Up to + 2 kV dc PMT bias
  • Separate focus and gain controls
  • Model 2007 has separate anode and dynode outputs
  • Model 2007P combines tube base with low noise, charge sensitive preamplifier with HV transient protection