Charge Amplifiers for Neutron Scattering

Features

• 4 functions: charge preamplifier, amplifier, filter, adjustable distriminator, HV filter
• Equivalent capacity: 0.05 or 0.025 pF
• Sensitivity: 20 or 40 V.pC^-1
• resolving time: 10 or 3 µs
• Time characteristics optimized for Time-of-Flight measurements: 0.07 µs time jitter
• Very competitive cost
• Small size
• Easy to use

Description

These charge amplifiers have been optimized for the process of low amplitude pulses delivered by Helium-3 neutron detectors operating in proportional mode. They offer both small size and low cost while combining four main functions: charge preamplifier, filter-amplifier, adjustable discriminator and high voltage filter. They include test input, analog and digital outputs, threshold and discriminator adjustment potentiometers with connectors for device control.

The general purpose ACHEM7F amplifier offers relatively long time constants allowing good thermal peak resolution at low counting rates which are generally encountered in neutron scattering experiments.

The faster ACHP96F amplifier may be used for higher counting rates. It has been specially designed for Time-of-Flight (TOF) measurements: the digital pulses delay with respect to analog pulses has been lowered as much as possible.
Among our references, more than 400 ACHEM7F units operate on the FOCUS spectrometer of PSI at Viligen (Switzerland), following 1 300 ACHN92 units at the NIST (Washington).

Upon request, ACHEM7FCON and ACHP96FCON amplifiers may be proposed to the user with 8 or 7 complementary connectors for manufacturing connecting cables of its own.
The ACHEM7H and ACHP96 versions are equipped with connector for male HN detector, which can be directly plugged on the female HN connector of 25 or 50 mm diameter Helium-3 detectors.

For quantities superior to 25 pieces, the ACHEM7FCI and ACHP96CI printed circuit boards, equipped with all necessary components and electrical outputs on flexible wires may be proposed: a strong experience in analog low level circuitry ts then mandatory to ensure proper operation.