925-SCINT Preamplifier, Amplifier, Bias Supply and SCA

ORTEC 925-SCINT ACE-MATE Preamplifier, Amplifier, Bias Supply, and Single Channel Analyzer (SCA)• Stand-alone instrument designed for bench-top operation
• Interfaces directly to photomultiplier tube bases such as Models 266, 276, and 296
• Protected against sudden positive or negative high-voltage spikes
• Amplifier provides a 10-volt linear output and features low input noise and a wide gain range to allow a variety of applications
• Lower Level and Upper Level can be set over a 200:1 dynamic range from 50 mV to 9.99 V
• Front-panel push-button selects setting in volts, or count rate in kcps, 3-digit display
• High-voltage supply is continuously adjustable from 50 to 2000 V dc, and the output polarity is selectable

The ACE Mate Preamplifier, Amplifier, Bias Supply, and SCA provides the link between scintillation detectors and most ORTEC Multichannel Analyzers. ACE Mate, a stand-alone instrument designed for bench-top operation, incorporates a low-noise preamplifier, a spectroscopy-type shaping amplifier, a single-channel analyzer, count-rate monitor, HV power supply, and a digital display to monitor these functions. The ACE Mate module interfaces directly to ORTEC photomultiplier tube bases such as the Models 266, 276, and 296, which can be coupled with the 905 series of scintillation detectors.
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    The preamplifier is noninverting and is intended for use with photomultiplier tubes. The input is ac-coupled and diode-protected against sudden positive or negative high-voltage spikes. A Printed Wiring Board (PWB) switch is provided to bypass the preamplifier when using external preamplifiers, thereby allowing the signal to be connected directly to the internal shaping amplifier.

    The spectroscopy shaping amplifier provides a 10-V linear output and features low input noise and a wide gain range to allow a variety of applications. Semi-Gaussian bipolar shaping is used to eliminate baseline shift with count rate change. Bipolar pulse shaping also eliminates the need for pole-zero adjustments, thus simplifying the setup of the ACE Mate.

    A single-channel analyzer (SCA) is incorporated in the ACE Mate. The input to the SCA is obtained from the amplifier output. The SCA operates in Windows mode; the Lower Level and Upper Level can be set over a 200:1 dynamic range from 50 mV to 9.99 V. The lower-level reference is selected by a PWB jumper for either the front panel potentiometer or an external signal.

    A three-digit display on the front panel allows the user to monitor either the high voltage (in kV), the lower-level and the upper-level SCA discriminator settings (in volts), or the count rate (in kcps). A front-panel push-button selects among these three choices.

    The high voltage supply provides the voltage necessary for the photo­multiplier tubes. The output is contin­uously adjust­able from 50 to 2000 V DC and internal PWB jumpers select the output polarity. Front-panel LEDs indicate the presence of high voltage and the polarity. The maximum load current is 1 mA to 2000 V. A front-panel On/Off switch controls the high voltage.

    A preamp power connector provides power to tube bases with internal pre­amplifiers.
  • Specifications +


    Preamplifier
    INPUT
    Input stage is ac-coupled. Diode protected against sudden positive or negative voltage spikes.
    IN/OUT PWB slide switch provides preamplifier selection. The IN position allows the internal preamplifier to function. The OUT position allows an external preamplifier to be directly connected to the amplifier using the Input BNC connector.

    Amplifier
    GAIN RANGE
    Continuously adjustable from 5 to 1250 using six-position front-panel COARSE GAIN switch and a ten-turn direct reading FINE GAIN potentiometer.

    PULSE SHAPE Peaking time equals 2 µs and is semi-Gaussian bipolar.
    POS/NEG PWB slide switch selects either positive or negative input pulse polarity.
    INPUT Accepts either the output of the internal preamplifier or a signal from the rear-panel BNC connector. External input signals can be positive or negative, with rise times <1­ µs and decay times >40 µs; Zin = 1000 Ω; ac-coupled; linear maximum input 2 V; absolute maximum 20 V.
    OUTPUT Rear-panel BNC connector with Zout <1 Ω is short-circuit proof and positive lobe leading, with a full-scale linear range from 0 to 10 V. Active filter shaping is incorporated.
    PREAMP POWER Rear-panel standard ORTEC preamp power connector (Amphenol 17-10090) mates with captive and noncaptive power cords on all ORTEC preamplifiers.

    Single Channel Analyzer
    SIGNAL INPUTS
    Front-panel BNC connector accepts positive, unipolar or bipolar signal, 0- to 10-V linear range. PWB jumper selects either dc- or ac-coupled input. For dc-coupled input, ±12 V maximum; width >100 ns; Zin = 1 kΩ. For ac-coupled input, ±100 V maximum, 0.2- to 10-µs width; Zin = 1 kΩ.
    LL REF EXT When the PWB jumper is on Ext, the rear-panel BNC connector accepts the lower-level biasing. (An input of –20 mV to –9.99 V on this connector corresponds to a range of 20 mV to +9.99 V for the lower-level discriminator setting.) Input protected to ±24 V.

    Outputs
    SCA OUT Front-panel BNC connector pro-vides positive NIM-standard output, nominally +5 V; 500 ns wide; Zo ≤ 10 Ω. Output occurs as the trailing edge of linear input crosses the LL threshold.
    LL OUT Rear-panel BNC connector provides positive NIM-standard output, nominally +5 V; 500 ns wide; Zo ≤ 10 Ω. Output occurs as the leading edge of linear input crosses the LL threshold.
    UL OUT Rear-panel BNC connector provides positive NIM-standard output, nominally +5 V; 500 ns wide; Zo ≤ 10 Ω. Output occurs as the leading edge of linear input crosses the UL threshold.

    Electrical and Mechanical
    Power Required +12 V, 145 mA; –12 V, 140 mA; +6 V, 400 mA.
    Weight Net  0.91 kg (2.0 lb).   Shipping  2.27 kg (5.0 lb).
    Dimensions NIM-standard single-width module, 3.43 X 22.13 cm (1.35 X 4.714 in.) per DOE/ER-0457T.

    Related Equipment
    The Model 850 is compatible with all ORTEC amplifiers and other amplifiers having a 0- to 10-V positive, linear output range.
  • Ordering Information +


    Model Description
    925-SCINT      ACE Mate Preamplifier, Amplifier, Bias Supply, and SCA