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NIM 715


The Model 715 is a high performance, five-channel constant fraction timing discriminator packaged in a single width NIM module. It exhibits typical time walk plus slewing of +/-75 pSEC from threshold to 100 times threshold.

Each channel has independent threshold adjustment, output width adjustment, and shaping delay. The threshold is variable from -25 mV to -1 Volt and is monitored from a front panel test point providing a DC voltage ten times the actual threshold setting. The outputs are non-updating with the output width adjustable from 5 nSEC to 150 nSEC. The shaping delay circuit is made complete by connecting the appropriate cable length between two LEMO connectors, allowing the user to optimize time resolution by easily matching the characteristics of each detector. A monitor is also provided to observe the constant fraction shaped pulse to verify that the delay is correct.

A fast veto input allows simultaneous inhibiting of all five channels to reject unwanted events early in the system. Similarly, a bin gate will inhibit the entire module when applied via the rear connector.

The 715 has three individually driven, current switching outputs per channel. Two are normal NIM levels and one com- plemented. They have typical risetimes and falltimes of 1 nSEC helping to preserve the excellent timing characteristics. The output transition times and shapes are unaffected by the loading conditions of the other outputs.



One LEMO connector per channel; 50 ohms
+2%, direct coupled; less than 5% input
reflection for a 2.0 NSEC input risetime; input
protection clamps at +.7 V and -6 V and can
withstand +/-2 amps(+/-1OO Volts) for a duration of
1 USEC with no damage to the input.
Continuously variable from -25 mV to -1 Volt,
15-turn screwdriver adjustment; better than
0.20%/degC stability, front panel test point provides
a DC voltage ten (10) times the actual threshold
Fast Veto:
One LEMO connector input common to all five
channels; accepts normal NIM level pulse
(-500 my), 50 ohms direct coupled; must overlap
the negative going edge of the input pulse
plus the shaping delay time to inhibit all channels;
5 NSEC minimum input width.
Din Gate:
Rear panel slide switch enables or disables bin
slow gate in accordance with TID-20893.
Inhibits entire module within 10 NSEC from
application of bin gate.

Three (3) LEMO connector outputs per channel;
two normal NIM level outputs and one comple-
mentary output. The normal outputs deliver
pulses of -16 mA (-800 mV across 50 ohms). The
complemented output is quiescently -16 mA
(-800 my) and goes to zero mA (O Volts) during
output. Output risetimes and falltimes are less
than 1.5 NSEC from 10% to 90% levels.

CF Monitor.-
One LEMO connector output per channel; drives
50 ohm load, permits observation of the shaped
constant fraction pulse to verify the shaping delay
is optimized for the input pulse.

Width Control
One control per channel; 15-turn screwdriver
adjustment; output width is continuously
variable from 5 NSEC to 150 NSEC; better than
+0.2%/OC stability, nonupdating output


Shaping Delays

Requires a 50 ohm coaxial cable: recommended delay range of 500 PSEC to 100 NSEC;
the maximum delay is
limited only by the cable attenuation, a factor of two attenuation can be tolerated
without significant
degradation of the time resolution,, stability is better than 10 PSEC/degC. The
shaping delay time should
approximately equal the input risetime plus one nanosecond.
Continuous Repetition Rate.-
Greater than 100 MHz; with output width set at minimum. (I NSEC shaping delay)
Pixel Pair Resolution

Better than 10 NSEC, with output width set at minimum. ( I NSEC shaping delay)
Input to Output Delay:

Less than 10 NSEC; with 1 NSEC shaping delay.
Multiple Pulsing

One and only one output pulse regardless of input pulse amplitude or duration.
Power Supply Requirements:
-6 V @ 390 mA +6 V @ 240 mA
-12 V @ ISO mA +12V@ OmA
-24 V @ 45 mA +24 V @ 35 mA
115 VAC @ 30 mA
Note: All currents are within NIM specification limits promitting a full powered bin to be
operated without overloading.
Operating Temperature:
O@C to 70@C ambient.
Standard single width NIM module in accordance with TID-20893 and Section ND-524.
Quality Control:
Standard 36-hour cycled burn-in with switched power cycles.

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