584 Constant-Fraction Discriminator

Specifications

PERFORMANCE

INPUT Accepts negative input signals from 0 V to –5 V without saturation; dc-coupled; Z_in =50 W; reflections £±5% for t_r £2 ns.

THRESHOLD RANGE –5 mV to –1 V.

THRESHOLD INTEGRAL NONLINEARITY £±0.25% of full scale.

THRESHOLD INSTABILITY £±100 µV/°C, 0 to 50°C.

PROPAGATION DELAY Nominally 25 ns, with external CF Delay »2 ns.

MINIMUM PULSE-PAIR RESOLUTION £20 ns.

DEAD TIME Nominally 20 ns or Blocking Output Width, whichever is greater.

BLOCKING OUTPUT WIDTH Adjustable from £10 to ³1000 ns.

TIME WALK £±100 ps for the 100:1 input range from –20 mV to –2 V. Conditions: External CF Delay = 2 ns; input rise time £1ns; input pulse width = 10 ns.

INPUTS

INPUT Front-panel BNC connector accepts fast negative input signals from 0 V to –5 V without saturation; dc-coupled; Z_in = 50 W; reflections £±5% for t_r ³2 ns.

G + Jumper Position Accepts slow positive NIM input signal levels for gating; dc-coupled; Z_in >1 kW.

GATE INPUT Rear-panel BNC connector; input signals accepted according to PWB Gate Input Jumper.

G – Jumper Position Accepts fast negative NIM input signal levels for gating; dc-coupled; Z_in = 50 W.

OUTPUTS

TIMING Two front-panel BNC connectors provide simultaneous NIM-standard fast negative logic signals; t_r »2 ns; t_f »3 ns; t_w »5ns.

BK OUT Front-panel BNC connector provides a NIM-standard fast negative logic pulse that occurs simultaneously with the Timing Outputs; width variable by front-panel adjustment from £10 to ³1000 ns; t_r @2 ns.

POSITIVE Front-panel BNC connector provides NIM-standard slow positive logic pulse simultaneously with Timing Outputs; Z_o <10 W; width variable by PWB width adjustment from £0.5 to ³2.5 µs. The associated LED is triggered for approximately 3 ms (updating) by each positive output pulse.

CONTROLS

THRESHOLD Front-panel 10-turn precision locking potentiometer determines the discriminator threshold setting in the range from –5 mV to –1 V.

TIMING MODE SWITCH Front-panel 3-position locking toggle switch selects one of the three timing modes:

CF (Constant-Fraction) Attenuation factor is internally set at f = 0.2 (can be changed upon request). An external 50-W coaxial cable must be provided for the constant-fraction shaping delay (CF Delay).

SRT (Slow-Rise-Time) Reject Provides constant-fraction timing and inhibits output signals that would be produced by leading-edge timing from the leading-edge arming discriminator. An input signal that does not cross the discriminator threshold before the constant-fraction zero-crossing time does not produce an output pulse.
LE (Leading-Edge) Inhibits timing from the constant-fraction circuitry. The timing is derived as the leading edge of the input signal crosses the discriminator threshold level.

CF DELAY Two front-panel BNC connectors accept 50-W coaxial cable to set the required constant-fraction shaping delay for the CF and SRT Modes: total delay is »0.8 ns plus the delay of the external cable. In the LE Mode, the user may either connect a piece of 50-W coaxial cable between these two connectors or connect a 50-W termination to each of the two connectors.

WALK Front-panel 20-turn screwdriver adjustment sets the walk compensation for each application.

CF MON Front-panel BNC connector permits observation of the constant-fraction bipolar timing signal; Z_o = 50 W. 50-W coaxial cable required; 50-W termination suggested.

WIDTH Front-panel 20-turn screwdriver adjustment sets the width of the Blocking Output pulse. Variable from £10 to ³1000 ns. Sets the instrument dead time for widths greater than nominally 20 ns.

GATING MODE SWITCH Rear-panel 2-position locking toggle switch controls the use of the Gate Inputs. (One of three Gate Input signal paths is selected by a PWB jumper.)
Gated A "true" logic level from the selected Gate Input permits output signals to be generated by the discriminator. A "false" logic level from the selected Gate Input inhibits output signals from being generated by the discriminator. A set of Output signals already in progress is not terminated prematurely by a logic "false" signal from the selected Gate Input.
Ungated The signal level of the selected Gate Input does not inhibit normal generation of output signals from the discriminator (i.e., the discriminator is always enabled).

LOGIC CURRENT SWITCH Rear-panel 2-position locking toggle switch selects either the –6 V or the –12 V NIM supply line for providing current for the high-speed ECL logic used in the discriminator.

NOTES:
(1) The module is within the current allotment for a single NIM width when using the –6 V position with a NIM Class V power supply or equivalent.
(2) The module exceeds the current allotment for a single NIM width on the –12 V supply when using the –12 V position. However, this position permits using the discriminator in bins with power supplies not providing –6 V.

GATE INPUT JUMPER (G+, G–, or BG) PWB jumper selects one of three Gate Input signal paths:
G+ Selects the rear-panel BNC Gate Input connector to accept slow positive NIM input signal levels for gating; dc-coupled; Z_in >1 kW.
G– Selects the rear-panel BNC Gate Input connector to accept fast negative NIM input signal levels for gating; dc-coupled; Z_in = 50 W.
BG Selects the Bin Gate line (pin 36 of the NIM power connector block) to accept slow positive NIM input signal levels >+2 V for gating; dc-coupled; Z_in >1 kW.

POSITIVE OUTPUT WIDTH (+ Width) PWB 4-turn potentiometer sets the width of the slow positive NIM output signal in the range from £0.5 to ³2.5 µs.

POSITIVE OUTPUT SIGNAL POLARITY (PO or ) PWB jumper selects the slow positive NIM output signal (PO) or the complement output signal ().

ELECTRICAL AND MECHANICAL

WEIGHT
Net 1.2 kg (2.6 lb).
Shipping 2.25 kg (5.0 lb)

DIMENSIONS NIM-standard single-width module 3.43 X 22.13 cm (1.35 X 8.714 in.) per DOE/ER-0457T.

ORDERING INFORMATION