Preamplifier Model 3000

Preamplifier Model 3000

The Model 3000 low-noise charge-sensitive preamplifier integrates the charge pulse from a PMT (decoupled from the anode) and converts it into a convenient positive voltage pulse output. The peak amplitude of each output pulse is linearly proportional to the total charge output of the PMT during each amplified photo event. The pulse is set to decay at a nominal  50 μs time constant, and interfaces directly with any of IAP spectroscopy amplifiers. The Model 3000 includes a diode protection network on the preamplifier input to keep sudden application or removal of the PMTs bias voltage from damaging the preamps circuits. A test is also provided to aid system testing, gain calibration, or troubleshooting. The 3000 generates a positive polarity output pulse in response to typical input signal from a photomultipliers decoupled anode. This amplifier has a high voltage transient protection for long-term use in the lab. Also, this instrument is used in timing applications due to the low noise contribution for better resolution and rise time of less than 20 ns.

Specifications

INPUTS

• Input Detector: Accepts decoupled negative charge pulses from scintillation detectors PMT; input limit ± 100VDC ; as coupled.
• Test Input: Accepts a negative polarity tail pulse from a test pulse generator; charge coupled 100 PC/V to preamplifier input; voltage gain to output is 0.45 V/V, nominal
• High Voltage Input: ± 2000 V

 

Output

• Provides unipolar positive pulses linearly proportional in peak amplitude to charge delivered from PMT. Decay time constant = 50 μs , nominal; rise time < 20 ns; delivers up to 10 V, peak.

 

Integral Non-Linearity

• < ±0.04%

 

Power Requirement

• +12 V dc- 15 mA dc, nominal
• -12 V dc- 15 mA dc, nominal

 

Calibration

Connect the preamplifier to a 12 V dc, 15mA power Supply with the 3m (10ft) cable supplied with the 3000. Power for the 3000 is available on the Nal Plus board and on the rear panel of all IAP amplifiers. Next. connect the decoupled anode output of a PMT to the input of the 3000 with a coaxial cable. Then connect the detector output to an oscilloscope and verify that the preamp is providing a positive tail pulse in response to detected scintillation events. For best result, the preamp output pulse must be less than preamp bias or saturation. If the output pulse from the 3000 is greater than 10 volts you should adjust the voltage to the PMT until the preamp output is 10 volt or less. Once you have adjust the PMT voltage and the output of the preamp is at a satisfactory level, you are ready to connect to the amplifier and the rest of your detector system.

 

General Notes and Cautions

Preamplifier noise contribution increases and rise time degrades as a function of the input capacitance attached to the preamp. These undesirable effects can be minimized by selecting a low capacitance cable and keeping the cable between the detector and the preamp as short as possible.

 

Delivery Test

• Power test
• Match test the amplifier output with MCA input
• Stability test
• Spectroscopy test with DAS software

 

Installation Requirements 

• Laboratory
• A table for placing device
• Bin power supply model and amplifier model 3600
• Detector
• Computer
• The equipped room with an air conditioning for constant temperature and humidity
• Power
• Pulse Generator

 

Long Term Warranty And After Sales Service