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Model 2015A

Spectroscopy

Amplifier/Timing SCA

User’s Manual

9231694B

01/05

Summary of Contents for 2015A

Page 1: ...Model 2015A Spectroscopy Amplifier Timing SCA User s Manual 9231694B 01 05...

Page 2: ...ing as part of a submission to regulatory or legal authorities pursuant to the purchaser s legitimate business needs No material in this document may be copied by any third party or used for any comme...

Page 3: ...djustments 8 Resolution Versus Count Rate and Shaping 12 Resolution Destroying Interfaces 14 SCA Operation 15 Setup 15 Reference Data on Cables 17 Preventative Maintenance 19 4 Performance Check 20 Eq...

Page 4: ...cuit 31 Gain Amplifier 31 Input Amplifier K1 32 Gain Amplifier K2 32 Integrator Amplifier A5 32 Amp OUTPUT Integrator and Driver 32 Restorer 33 SCA Section 33 SCA OUTPUT 33 Disc Output 35 Lower Level...

Page 5: ...Input Output 39 Controls 40 Internal Controls 40 Performance 41 Connectors 42 Power Requirements 42 Physical 42 Environmental 43 B Installation Considerations 44 iii...

Page 6: ...Notes iv...

Page 7: ...aping The Model 2015A is further enhanced by the addition of a timing SCA contained in the same package offering two modes of single channel pulse height energy analy sis In the SCA mode of operation...

Page 8: ...g mode the SCA OUTPUT logic pulse is placed consistently in time 200 nanoseconds past the AMPLifier OUTPUT pulse peak Thus the Model 2015A may serve to replace an amplifier and individual timing SCA s...

Page 9: ...re connected to the Model 2209A AUTO FLOW METER and subsequent scalers Figure 1 shows the SCA and DISC information being routed by the 2209A to the respective scalers indi cating alpha and beta events...

Page 10: ...ectors Front Panel This is a brief description of the 2015A s front panel controls and connectors For more detailed information refer to Appendix A 4 Controls and Connectors Figure 2 Front Panel Contr...

Page 11: ...Rear Panel This is a brief description of the 2015A s rear panel connectors For more detailed in formation refer to Appendix A 5 Rear Panel Figure 3 Rear Panel Connectors...

Page 12: ...Internal Controls 6 Controls and Connectors Figure 4 Internal Controls...

Page 13: ...t you will gain sufficient familiarity with this instrument to permit its proper use in the system at hand Spectroscopy System Operation Setup A block diagram of a typical Canberra gamma spectroscopy...

Page 14: ...in connector located on the 2015A rear panel Allow the total system to warm up and stabilize 3 Set the 2015A controls as indicated below SHAPING 2 ms internal COARSE GAIN 16 FINE GAIN 2 2 This will gi...

Page 15: ...de signals with long decay times in Figure 6 These are due to charge trapping in the detector and cannot be corrected by the pole zero control 9 Spectroscopy System Operation Figure 6 Correct Pole Zer...

Page 16: ...r e Set the scope s channel 1 vertical sensitivity to 5 volts cm and adjust the main time base to 0 2 ms cm Monitor the 2015A s AMP OUTPUT and adjust the square wave generator s amplitude control atte...

Page 17: ...set pulse Note 1 At high Count rates the pole zero adjustment is extremely critical for main taining good resolution and low peak shift For precise and optimum pole zero setting a scope vertical sensi...

Page 18: ...through an attenu ator to the preamp test input and repeat Performance Adjustments step 2 pole zero adjustment 4 The AMP OUTPUT DC level is factory calibrated to 0 5 millivolt 5 To get optimum resolu...

Page 19: ...as follows 1 Change C1 from 560 pF to 9100 pF 2 Change C2 from 1600 pF to 560 pF 3 Change R1 from 19 1 k ohms to 226 k ohms 4 Change R2 from 52 3 k ohms to 11 k ohms 5 Change C3 from 130 pF to 2000 pF...

Page 20: ...his may increase power line frequency 50 or 60 cycle ground loops 3 Ground Loops power line frequency interference can be caused by long cable connections between the detector preamplifier and shaping...

Page 21: ...of the AMP OUTPUT is 1 75X the shaping time constant Therefore a 12 s shaped pulse required 21 sec to reach full amplitude Many analyzers will not handle this instead of analyzing the peak of the sign...

Page 22: ...f 5 0 0 1 volts 8 Increase the 1407 PULSE HEIGHT until the 2015A SCA OUTPUT just begins to disappear Again measure the AMP OUTPUT visually on the oscilloscope or on a calibrated multichannel analyzer...

Page 23: ...he DISC B jumper plug back to the OUT position and the LLD jumper plug to the INT position Reference Data on Cables Figures 14 and 15 show a typical output pulse at the load end of the designated RG 5...

Page 24: ...e 50 ohms Upper Trace Rload 1k ohms Lower Trace Rload 50 ohms Scope Horizontal 0 1 s cm 18 Operating Instructions Figure 14 Typical Output Pulse Using a RG58 U Cable Figure 15 Typical Output Pulse Usi...

Page 25: ...ts Upper Trace Rload 1k ohms Lower Trace Rload 50 ohms Scope Horizontal 0 1 s cm Preventative Maintenance Preventative maintenance is not required for this unit When needed the front panel of the unit...

Page 26: ...ent used if questions or difficulties in their use arise Equipment Required In order to perform the checkout procedure detailed in subsequent steps the following equipment or equivalents will be requi...

Page 27: ...0 mA 12 V dc 150 to 170 mA 12 V dc 60 to 80 mA 24 V dc 40 to 60 mA Note A greater deviation in currents indicates a faulty unit Gross errors would probably be due to faulty or reversed capacitors sho...

Page 28: ...N OUTPUT to the 2015A front panel INPUT with RG 62 coax cable 4 Connect the 1407 NORMAL OUTPUT to the EXT TRIG input of the scope Set the scope triggering to EXT Outputs 1 Connect the AMP OUTPUT to th...

Page 29: ...litude should not decrease by more than 100 mV There should be no discernible distortion in the pulse shape Remove the terminator 6 Remove all 1407 ATTENUATION The AMP OUTPUT pulse should be clamped a...

Page 30: ...ionately with each COARSE GAIN setting 5 Set the 2015A CORSE GAIN to 128 6 Monitor the AMP OUTPUT on the scope and turn the 2015A FINE GAIN control to minimum The signal amplitude should decrease by a...

Page 31: ...nd adjust the 1407 PULSE HEIGHT until the tail pulse attains an amplitude of 100 mV 5 Monitor the 2015A AMP OUTPUT on the scope and adjust the pole zero for no under or overshoots see Figure 18 Adjust...

Page 32: ...T The pulser NORMAL OUTPUT should be 10 volts coinci dent with the amplifier OUTPUT peak Next while observing the summing point on the oscilloscope the amplifier fine gain is carefully adjusted to bri...

Page 33: ...nearity and instability in the pulser OUTPUT do not enter into the mea surement because both direct and attenuated outputs will be affected identically save for negligible effect of the pulser s atten...

Page 34: ...lts Width 350 to 650 nsec Rise Fall Time 25 nsec Max 2 Place the DISC A jumper plug in the ULD position the DISC ULD OUTPUT should disappear 3 Set the rear panel E RANGE switch to 1V the DISC ULD OUTP...

Page 35: ...the EXTernal position and the DISC B jumper in the IN position 2 With a jumper wire connect the 5 volt supply to the rear panel Disc BNC 3 Adjust the 1407 PULSE HEIGHT for a flickering SCA OUTPUT 4 Me...

Page 36: ...tegrator and dc restorer The processed signal is then connected to the SCA and front and rear panel BNC connectors J3 and J102 respectively The SCA Section The AMPlifier OUTPUT signal is connected to...

Page 37: ...he integration occurs As a re sult the input amplifier K1 is the dominant noise source Each of the two gain stages operate at relatively low closed loop gains providing stable operation with time and...

Page 38: ...FINE GAIN function Integrator Amplifier A5 ACTIVE INTEGRATOR A5 provides complex pole pairs where the locus of poles are equidistant from the abscissa on the S plane The real part of the complex poles...

Page 39: ...ance type amplifier that is it monitors the AMP OUTPUT TP1 OUTPUT voltage and develops a constant current of correct polarity at its OUTPUT junction of Q4 collector and A1e pin 15 The voltage on C24 i...

Page 40: ...the positive transition and sets flip flop A6b A6c The OUTPUT of A6c pin 8 is inverted by Al 2f and enables A7b to generate the internally selectable by J4 The low OUTPUT impedance can 500 nanosecond...

Page 41: ...entary low OUTPUT im pedance emitter followers The DISC OUTPUT is nominally 5 volts unterminated however will increase to approximately 8 volts unterminated if resistor RA 3 9k ohms is removed Lower L...

Page 42: ...ed to approximately 20 mV by R109 and R1 13 and repre sents 90 mV when referenced to the AMP OUTPUT signal Diode D18 clamps the OUTPUT of A16 pin 6 to 600 mV preventing A16 from saturating As the LOWE...

Page 43: ...ons refer to page 7 2 Check Associated Equipment An investigation should be made to ensure that the trouble is not a result of conditions external to the Model 2015A Check that the equipment used with...

Page 44: ...placement parts should be direct replacements unless it is known that a different component will not adversely affect instrument performance Many components in the Model 2015A are standard electronic...

Page 45: ...s Zout 50 BNC connectors located on front and rear panels short circuit protected OUTPUT amplitude can be changed to 8 V by means of an internal jumper Input Output DISC Rear panel BNC connector havin...

Page 46: ...er signal TIME CONSTANTS Internal pushbutton switch selects SHAPING TIME constant of 0 5 s or 2 0 s factory set to 2 0 s LOWER LEVEL E Ten turn locking dial precision potentiometer selects a base line...

Page 47: ...ARITY 0 05 of full scale OVERLOAD RECOVERY Recovers to 2 of full scale OUTPUT in two pulse widths for a X1000 overload with pole zero cancellation properly set NOISE CONTRIBUTION 7 V referred to the I...

Page 48: ...r LOWER LEVEL E and WINDOW E PULSE PAIR RESOLUTION With the SCA driven from a rectangular shaped pulser for LOWER LEVEL E thresholds 100 mV the pulse pair resolution is 500 ns over the full linear ran...

Page 49: ...G WEIGHT 2 3 kg 5 0 lb Environmental OPERATING TEMPERATURE 0 to 50 C RELATIVE HUMIDITY Up to 80 non condensing Tested to the environmental conditions specified by EN 61010 Installation Category I Poll...

Page 50: ...nd EMC on the system However care should be taken to maintain full compliance These considerations include A rack or tabletop enclosure fully closed on all sides with rear door access Single point ext...

Page 51: ...OR IN THE CASE OF DEFECTIVE SERVICES REPERFORMANCE AT CANBERRA S COST IS YOUR SOLE AND EXCLUSIVE REMEDY UNDER THIS WARRANTY EXCLUSIONS Our warranty does not cover damage to equipment which has been al...

Page 52: ...n a logic signal output is generated whenever the ampli er unipolar signal falls between the energy levels determined by the front panel controls E and E This mode is especially useful when a wide dyn...

Page 53: ...baseline from 0 1 V to 10 V for the timing SCA mode and 0 15 mV to 10 V for the normal SCA mode WINDOW E Ten turn locking dial precision potenti ometer selects window width from 0 to 10 V or 0 to 1 V...

Page 54: ...er for LOWER LEVEL E thresholds 100 mV the pulse pair resolution is 500 ns over the full linear range for the DISC LLD output TEMPERATURE DRIFT E and E 0 005 of full scale C 50 ppm POWER SUPPLY SENSIT...

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