SPECTROSCOPY AMPLIFIER - [ Type : SA 524 ]
Technical Data
Spectroscopy Amplifier Type : SA524 is a high performance nuclear pulse shaping 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, diode limited unipolar output, BUSY and count-rate output as some of the key features designed into it. Some of the main applications of spectroscopy amplifier involve nuclear pulse height spectroscopy, nuclear timing spectroscopy, Counting Systems etc.
The input to SA524 can be either positive or negative signal from a detector preamplifier. The output pulses, 0 to 10V for unipolar pulse and ±10V for bipolar pulse, provided on both front and rear panel, are suitable for use with single channel and multi channel pulse height analyzers. When long connecting cables are used between detector preamplifier output and the amplifier input, noise induced in the cable from ground loop currents can reduce the signal to noise ratio thereby causing spectrum degradation. This may be minimized by using amplifier in the differential input mode. Six different shaping time constants are provided for optimizing resolution and count rate performance. To minimize baseline shift due to drift as well as count rate dependent shift at medium and high frequencies a gated baseline restorer (BLR) has been incorporated. Automatic noise threshold stage derives a threshold voltage proportional to the noise level and ensures that BLR gating works just above noise level. The pile up reject output logic pulses may be fed to an associated multi-channel analyzer that can be used to suppress spectrum distortion caused due to piling up of pulses on each other at high counting rates.
Specifications
A. PERFORMANCE
Gain Range
Continuously variable from X4 to X1500.
 
Pulse Shaping
Quasi-gaussian and Quasi-triangular.
 
Shaping time
0.5, 1, 2, 3, 6 and 10 ms
 
Input Noise
5 mv r.m.s with 3 ms shaping time
 
Overload
Recovers to within 2% of baseline in 15x shaping time from x200 overload.


Integral Non-Linearity
< 0.05% from 0 to 10V.
 
Crossover Walk
Bipolar zero cross over walk is < ± 3 ns in 50:1 dynamic range.
 
B. CONTROLS
FINE GAIN
Front panel 10 turns precision potentiometer provides a continuously adjustable, gain factor from 0.5 to 1.5.
 
COARSE GAIN
Front panel six-position switch selects gain factors of X20, X50, X100, X200,X500 and X1000.
 
PZ
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.
 
ATN
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 ms.
 
TRI/GAUSS
Front panel toggle switch for selecting quasi-gaussian or quasi-triangular unipolar output shape.
 
BAL
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.
 
LIM
A push-button switch on the front panel to prevent oscilloscope input from overloading and thus enabling observation of the baseline in sensitive ranges of the scope.
 
Note : Manufactured by NUCLEONIX SYSTEMS based on Technology from Bhabha Atomic Research Center, Mumbai.
C. INPUTS
IN
BNC connectors on front panel & rear panel accepts 0 to 10V of either polarity.
 
INH
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.
 
D. OUTPUTS
UNI
Unipolar output on front panel BNC, full-scale linear range 0 to +10V.
 
UNI
Unipolar output on rear panel BNC, full-scale linear range 0 to +10V, output is series terminated with 91 ohm.
 
BI
Bipolar output on front panel BNC, linear range of ±10V.
 
BI
Bipolar output on rear panel BNC, linear range of ±10V, output is series terminated with 91 ohm.
 
PUR
Inhibit output, rear panel BNC provides a + 5V logic signal when pulse pile up occurs. This is used as an anticoincidence input for ADC.
 
CRM
Count-rate meter output, rear panel BNC provides +5V logic signal for every input pulse. This is used as an input to a rate-meter or counter.
 
BUSY
Deadtime output, 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.
 
E. POWER CONNECTORS
  NIM standard, as per AEC specifications TID 20893 (Rev) Type AMP 204186-5 or Amphenol connector type 26-159-24P-H (24 pin type) (+24V, -24V, +12V, -12V and ground)
PREAMP POWER
Rear panel power connector provides preamp power (+24V, -24V, +12V, -12V and ground) to the associated preamplifier.