SPECTROSCOPY AMPLIFIER 
(A 225) 



A225 Spectroscopy Amplifier is a high performance amplifier, ideally suited for use with all types of detectors such as germanium, silicon surface barrier and Si(Li) detectors. This is a single width NIM module with pile-up rejector (PUR), gated baseline restorer (BLR), auto threshold, unipolar and bipolar outputs, BUSY and count-rate output as some of the key features designed into it. 

 SPECIFICATIONS 

 PERFORMANCE 

Gain Range Continuously variable from x4 to x1500.
Pulse Shaping 7-pole quasi-gaussian and quasi-triangular.
Shaping time 0.5, 1, 2, 3, 6 and 10 micro sec.
Input Noise 5 microvolt r.m.s. with 3 micro sec. shaping time.
Integral Nonlinearity < 0.05% from 0 to 10V.
Crossover Walk Bipolar zero cross over walk is < ± 3 nsec. in 50:1 dynamic range.

INPUTS 

INPUT

BNC connectors on front and rear panels accept 0 to 10V of either polarity.
INH IN 

Rear panel BNC inhibit input connector accepts reset signals from preamplifiers.
LG

Rear panel BNC connector accepts the TTL- compatible linear gate signals from the associated ADC.

OUTPUTS 

UNI 

Unipolar front and rear panel BNC, with full scale linear range 0 to +10V.
BI

Bipolar front and rear panel BNC with a linear range of ±10V.
BUSY

Rear panel BNC provides +5V logic signal for the duration that the input pulses exceed threshold. This is used for dead time corrections with associated ADC.
LIM

A push-button switch on the front panel which inserts a diode limiter on the unipolar output. This enables observation of the baseline in sensitive ranges of the oscilloscope during PZ adjustment without over-loading the oscilloscope input.

CONTROLS 

Coarse Gain Front panel six position switch selects gain factors of X20, X50, X100, X500 and X1000.
Fine Gain

Front panel ten turn locking dial precision potentiometer selects variable gain factor of X0.5 to X1.5 
PZ Adj. Screwdriver adjustment of the PZ cancellation using 20 turn potentiometer on the front panel.
POS/NEG Front panel toggle switch for selecting either positive or negative input signals.
Attn. A front panel toggle switch selects an input attenuation factor of X1 or X2.5
Shaping

Front panel six position switch for selecting shaping times of 0.5,1,2,3,6 and 10 microseconds.
Tri/Gauss

Front panel toggle switch for selecting quasi-gaussian or quasi-triangular unipolar output shape.
BAL Adj

Screwdriver adjustment to match the gains of normal and differential reference inputs for maximum common mode noise rejection in DIFF mode using 20 turn potentiometer on the front panel.

APPLICATIONS 

  1. In nuclear pulse height spectroscopy 

  2. In nuclear timing spectroscopy 

  3. Counting Systems 

FACILITIES REQUIRED FOR COMMERCIAL PRODUCTION 

EQUIPMENTS 

Any standard working place where electronic instruments are being manufactured is suitable for fabrication and testing of this system. The electronic lab should have following facilities for test and calibration purposes: 

  1. NIM BIN (International std.) 

  2. Oscilloscope ( 100MHz ) 

  3. Precision tail pulse generator ORTEC model 419 or equivalent 

  4. Set of standard tools (including soldering station) and hardware required in electronics development laboratory. 

  5. Digital multimeter 

  6. True RMS voltmeter ( Fluke model 8922A or equivalent ) 

The approximate cost of the above equipment (if not already available) will be of the order of 5.0 lakhs. 

SPACE REQUIRED 

If the activity is to be started afresh, an area of around 10 sq. meter would normally be sufficient 

ELECTRICAL POWER 

230VAC, 5A 

MAN POWER 

One experienced Electronics Engineer and one Assistant / Technician will be required for production, testing and calibration of this system. 

    For details contact :
       

        Head, Technology Transfer & Collaboration Division,
        BHABHA ATOMIC RESEARCH CENTRE,
        TROMBAY, MUMBAI - 400 085
        Tel : 091-022-5505337/5593897
        Fax : 091-022-5505151
        Email : headttcd@barc.gov.in