142A, B, and C Preamplifiers

Specifications

PERFORMANCE

Performance specifications apply to E output unless stated otherwise.

NOISE  (see Fig. 2)

INTEGRAL NONLINEARITY £0.03%, 0 to ±7 V open circuit or ±3.5 V terminated in 93 W.

TEMPERATURE INSTABILITY
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 1.5 x 10⁷ MeV²/s.
142B 3 x 10⁷ MeV²/s.
142C 3 x 10⁷ MeV²/s.

RISE TIME (0 to 0.5 V pulse at E output on 93-W 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.

RECOMMENDED RANGE OF INPUT CAPACITANCE
142A 0 to 100 pF.
142B 100 to 400 pF.
142C 400 to 2000 pF.

DETECTOR BIAS VOLTAGE ±1000 V maximum.

INPUTS

INPUTS Accepts positive or negative charge input (normally from a semiconductor detector) from any type detector; BNC connector.

BIAS Accepts detector bias from supply and applies it to detector through the INPUT connector; maximum ±1000 V; SHV connector of 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.

OUTPUTS

E 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

POWER REQUIRED
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.).

SELECTION GUIDE TO 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 in Fig. 4 and read the capacitance in pF/mm² on the top part of the chart.

3.  Multiply the area of your detector in mm². This is the middle three-digit number for an ORTEC detector. Choose a Model 142A if the capacitance is less than 100 pF, a Model 142B is the capacitance is more than 100 pF but less than 400 pF, a Model 142C if the capacitance is greater than 400 pF. An ORTEC D-025-100-200 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.

Fig. 1.  Typical Time Resolution vs. Energy for different capacitance detectors using ORTEC standard electronics.

Fig. 2.  Typical noise as a function of input capacitance measured with an ORTEC Model 572 Amplifier and 2-µs time constant.

Fig. 3.  Typical rise time as a function of input capacitance with rise time compensation optimized at each data point. (Values given are for a +0.5 V signal into 93 W from the E channel.)

Fig. 4.  Silicon Detector:  specific capacitance in pF/mm²

ORDERING INFORMATION