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Appendix B - Performance Adjustments

Model 9660-9660A ICB Digital Signal Processor

Figure 33 Correct Pole/Zero Comp with Noisy

Detector

Scope:
Vertical: 500 mV/div
Horizontal: 50

s/div

Source:

Count rate: 2 kcps
Shaping: 8

s rise time

2.4

s flat top

Figure 34 Overcompensated Pole/Zero with

Noisy Detector

Scope:
Vertical: 500 mV/div
Horizontal: 50

s/div

Source:

Count rate: 2 kcps
Shaping: 8

s rise time

2.4

s flat top

Содержание 9660

Страница 1: ...Model 9660 9660A ICB Digital Signal Processor User s Manual 9231014G...

Страница 2: ...purchaser s legitimate business needs No material in this document may be copied by any third party or used for any commercial purpose or for any use other than that granted to the purchaser without t...

Страница 3: ...DSP Filter Parameters 13 Acquisition Window Adjust Screen 14 Stabilizer Parameters 14 DSP Gain Parameters 16 DSP Filter Parameters 18 4 Genie VMS User Interface and Controls 19 Defining a Detector Inp...

Страница 4: ...Correction With a Live Source 49 PUR Guard 51 PUR Guard Setup 53 PUR Guard Adjustment Using a Live Spectrum 54 Live Time Correction Using the LFC Module 54 LFC System Setup 55 A Specifications 56 Inp...

Страница 5: ...t Discriminator Threshold 72 Operation with Reset Preamps and Selecting Inhibit Mode 72 Configuring the Preamp Reset Mode 72 Pole Zero Setting for Reset Preamps 73 Using the Reset Inhibit 73 C Data an...

Страница 6: ...Notes iv Model 9660 9660A ICB Digital Signal Processor...

Страница 7: ...th improved resolution and enhanced stability The weighting function applied in the Model 9660 filter algorithm produces a sym metrical and near ideal Triangular Trapezoidal filter function Trapezoida...

Страница 8: ...ption installed To verify the model please check the serial num ber tag located on the NIM power connector For the Model 9660A the pole zero ad justment can be performed automatically the process is i...

Страница 9: ...nel This is a brief description of the 9660 ICB DSP s front panel LED indicators and con nectors For more detailed information refer to Appendix A Specifications User s Manual ICN 9231014G 3 Front Pan...

Страница 10: ...ription of the 9660 ICB DSP s rear panel connectors For more de tailed information refer to Appendix A Specifications Chapter 2 Controls and Connectors 4 Model 9660 9660A ICB Digital Signal Processor...

Страница 11: ...ly during factory calibration SW1 is the ICB slave address switch Select one of sixteen addresses 0 through 9 A through F for the 9660 The address must be unique in any one system The factory default...

Страница 12: ...onfigure the 9660 If the jumpers are removed by mistake please replace them as shown in Figure 4 W6 jumper plug installed Chapter 2 Controls and Connectors 6 Model 9660 9660A ICB Digital Signal Proces...

Страница 13: ...iate software Genie PC Genie 2000 or Genie VMS are required For specific details on using the host computer software please refer to the appropriate software user s manual Defining a Detector Input Th...

Страница 14: ...nfiguration only pa rameters some can be only programmed via the Adjust screen adjust only parame ters some can be programmed in both places In any event if the setting is adjusted then the new value...

Страница 15: ...following controls Gain Centroid Sets the centroid in channels of the reference peak at the high end of the spectrum for gain stabilization Figure 8 User s Manual ICN 9231014G 9 MID Editor Figure 7 MI...

Страница 16: ...the centroid in channels of the reference peak at the low end of the spectrum for zero intercept stabilization Zero Window Sets the width in channels of the upper and lower sampling windows on either...

Страница 17: ...e and Super Fine Gains will produce the total desired gain Fine Gain Sets the device s Fine Gain multiplier S Fine Gain Sets the device s Super Fine Gain value The combination of Coarse and Fine Gain...

Страница 18: ...or LLD as a percentage of the ADC s full scale Zero Sets the device s zero intercept as a percentage of the device s full scale Conv Gain Sets the device s conversion gain It can be set from 256 to th...

Страница 19: ...ime and count rate With set tings of SOFT MEDIUM and HARD the baseline restorer is set to fixed rates as selected Preamp Type Selects the Preamplifier type as either TRP Transistor Reset Preamp type o...

Страница 20: ...s The Stabilizer settings screen Figure 11 for the 9660 contains the following controls Gain Centroid Sets the centroid in channels of the reference peak at the high end of the spectrum for gain stabi...

Страница 21: ...intercept stabilization Zero Window Sets the width in channels of the upper and lower sampling windows on either side of the zero reference peak Zero Spacing Sets the spacing in channels between the u...

Страница 22: ...The combination of Coarse and Fine Gain sets the overall system gain to match the re quirements of the detector and energy application overall gain is continuously vari able from x2 0 to x1 536 The F...

Страница 23: ...uard time GT multiplier to reject trailing edge pileup in the event of detector preamp anomalies The PUR guard sets the pileup reject interval which is defined by GT x TRisetime TFlattop LT Trim Allow...

Страница 24: ...ets the flat top portion of the digital filter time response The flat top matches the fil ter to the detector charge collection characteristics to minimize the effects of ballistic deficit The flat to...

Страница 25: ...o briefly described here 1 First get control of the AIM module that you will use to control the DSP device MCA RESERVE NI30C 2 Next get a list of the ICB devices attached to the AIM You should see the...

Страница 26: ...i ther an AMP or ADC When you select the DSP Module option you will see a dialog like the one shown in Figure 15 Each of the setup parameters should be set up to match the device detector configuratio...

Страница 27: ...h the de vice is NI30C the enter NI30C 6 for the address Note that if the DSP address is not blank you cannot use an ICB Amp or ADC with this input of the AIM The DSP is mutually exclusive with the AM...

Страница 28: ...nity Coincidence Mode Sets the devices gating mode ANTIcoincidence or COINCidence In COINCidence mode a positive GATE pulse enables the conversion of the event in process in ANTI coincidence mode a po...

Страница 29: ...hibit reset input to the polarity of the preamplifier s Inhibit output Inhibit Polarity Sets the device s Inhibit signal polarity to either positive or negative If you are using a TRP preamplifer the...

Страница 30: ...placed so that a shift in the reference peak reflects a significant change in count rate through the window For broad peaks the spacing should be set so that the window s edges are not on the flat par...

Страница 31: ...eak Gain Correction Range Correction range 1 Ge or 10 NaI This control selects the Gain Correction range that can be provided to correct for drift Select 1 for germanium detector or 10 for a sodium io...

Страница 32: ...ing edge pileup in the event of detector preamp anomalies The PUR guard sets the pileup reject interval which is defined by GT x TRisetime TFlattop Inhibit Mode TRP Inhibit Selects inhibit mode NORMAL...

Страница 33: ...ne Gain 1 5003e 2 Pole Zero Setting 2048 Coincidence Mode Anti Offset 0 LLD 0 0103 Zero 0 0 Conversion Gain 8192 ADC Range 8192 Fast Discriminator Mode Auto Fast Discriminator 1 0 Input Polarity Posit...

Страница 34: ...Div 1 Zero Rate Div 1 Gain Correction Range Ge Zero Correction Range Ge Zero Mode Off Gain Mode Off Preamp Type RC PUR Mode On PUR Guard 1 1 Inhibit Mode Reset Chapter 4 Genie VMS User Interface and C...

Страница 35: ...ional ADC s Mixer Routers etc is not recommended In addition to the reconstructed Trapezoid signal a small amount of digital noise may also be observed mixed in with the signal This is an artifact of...

Страница 36: ...selection of shaping time When the 9660 senses increased detector noise it automatically in creases the signal baseline to maintain the signal and noise within the dynamic range of the fast digitizin...

Страница 37: ...eted return to the de sired rise time and or gain setting Again the MCA spectrum is not affected due to the large dynamic range of the 9660 s digital filter Note The optimum Pole Zero setting is indep...

Страница 38: ...alog spectroscopy amplifiers This scale factor 10 8 must be taken into consideration when verifying the 9660 gain factor For example when the 9660 Gain is set as follows Coarse Gain 120 Fine Gain x0 8...

Страница 39: ...s tem please refer to the Genie manual set for your Genie software Installing the 9660 in a NIM Bin The Model 9660 ICB Digital Signal Processor requires a NIM Bin which provides 6 volts The Canberra M...

Страница 40: ...tics When power is first applied to the Model 9660 it will go through an initialization and self diagnostics process The BDC Busy LED on the front panel will blink for duration of the process which re...

Страница 41: ...nections to the detector preamp preamp power signal BNC cable HV power supply cable etc can setup ground loops which may be sensitive to EMI noise pickup These effects can cause resolution degrada tio...

Страница 42: ...d running with a typical detector and to become acquainted with its operation For the following setup a detector with preamp gain of 500 mV MeV and a 60 Co radioactive source will produce a 6 5 to 7 v...

Страница 43: ...djustments be sure to save the MID File 8 MCA Adjust Screens The following parameters can be accessed and set using the Gain and Filter Device Adjust screens The adjustments can be saved to the dataso...

Страница 44: ...f 0 If using a detector with a Reset preamp such as the Canberra 2101 or 2008 change the preamp type from RC to TRP With TRP selected the Pole Zero compensation is au tomatically set to a value of 0 r...

Страница 45: ...tus Page of the Acquisition and Analysis window Select Update to update the ICR Status whenever the radioactive source is adjusted Note Although any radioactive source may be used the most accurate ad...

Страница 46: ...to RC b Pole zero failed to converge This message may result from any of the following reasons P Z Time Out Error The Auto P Z has failed to complete within a maximum time of two minutes The preamp fa...

Страница 47: ...une the Pole Zero setting to optimize performance at high rates For additional discussion on manual Pole Zero adjustment refer to Manual Pole Zero Matching on page 41 7 Verifying Pole Zero Accuracy Th...

Страница 48: ...t the Pole Zero slider bar located in the Filter Device Adjust screen so that the trailing edge of the trapezoid pulse returns to the baseline with no overshoots or undershoots Figure 21 shows the cor...

Страница 49: ...Manual ICN 9231014G 43 Detector Matching Figure 21 Correct Pole Zero Compensation Scope Vertical 50 mV div Horizontal 10 s div Source 60 Co 1 33 MeV peak at 6 V amplitude Count rate 2kcps Shaping 5 6...

Страница 50: ...r traditional ana log signal processing users are forced to manually inspect the peak shape of the MCA energy spectrum and optimize the shaping time selection For detectors that exhibit ballistic defi...

Страница 51: ...the ICR status whenever the radioactive source is adjusted Note Although any radioactive source may be used the most accurate adjustment is obtained using simple sources such as 57 Co 137 Cs or 60 Co...

Страница 52: ...may be set manually select FLAT TOP under the Filter parameter group b Incoming Count Rate Too High The incoming count rate ICR exceeds 20 kHz The Auto BDC will not operate properly if the ICR exceeds...

Страница 53: ...tects the arrival of input events and is capable of discriminating be tween multiple events separated by less than 500 ns If the fast discriminator detects two or more events within the processing tim...

Страница 54: ...cquire to OFF clear the memory and set acquire to ON Accumulate a spectrum with the LTC ON 8 Save the spectral file or print the spectrum or make note of the background counts and sum peaks for compar...

Страница 55: ...trapezoid signal Accurate Live Time Correction is obtained when the en ergy threshold and dynamic range of the fast channel and slow channel are the same In practice however the energy threshold of th...

Страница 56: ...Source Method which assumes that source A is 60 Co and source B is 137 Cs The 1173 2 keV peak of 60 Co will be used as a reference The upper peak at 1332 5 keV is not a good choice because the sum pea...

Страница 57: ...ing the effect of adding background counts Cs137 661 keV 11 Set the LTC ON OFF switch to Off Repeat steps 4 through 9 Compare the deviation of source A s spectrum when the LTC is ON and the LTC is OFF...

Страница 58: ...epted The default Guard Time 1 1x is minimum and provides opti mum performance and maximum throughput for most detector applications For the example shown above the second event begins before the firs...

Страница 59: ...rd Setup The default PUR Guard Time is 1 1x This Guard Time is minimum and does not ex tend the pile up rejection interval beyond the peaking time For events that exhibit sec ondary time constants or...

Страница 60: ...ed pole zero Verify the Pole Zero is correctly opti mized refer to Detector Matching on page 38 If the Pole Zero is not the problem set the PUR Guard to 2 5x and acquire a new spec trum If the symmetr...

Страница 61: ...directions and calibration instructions as indicated in the Model 599 LFC User s Manual 4 Initially set the PET Monostable as indicated in step 3 5 1 Gaussian Shaping Amplifiers of the Model 599 LFC...

Страница 62: ...it Mode is selected NORM selected resets and inhibits the pileup rejector and extends the Dead Time signal for the duration of the INH signal RESET preamp se lected inhibits the 9660 during the preamp...

Страница 63: ...c Deficit Correc tion matching function ON continuously while trapezoid flat top is automatically matched to the charge collection time of the detector OFF when proper matching is achieved active only...

Страница 64: ...performance for a wide range of applications LTC Mode ON OFF LFC ON Enables pile up rejector and live time corrector LTC LTC generates dead time to extend the acquisition time to compensate for events...

Страница 65: ...ing the associated slider bar Auto P Z 9660A only Available only for the 9660A with the automatic pole zero option installed Computer command initiates the automatic p z process AUTO BDC Computer comm...

Страница 66: ...linearity GAIN DRIFT 50 ppm C ZERO DRIFT 10 ppm C OVERLOAD RECOVERY Recovers to within 1 of full scale output from x1000 overload is 2 5 non overlapped pulse widths of full gain at any shaping process...

Страница 67: ...e cables are ordered separately please specify the following Model C1560 12 port ICB connecting cable Model C1703 2 AIM AMX data cable Physical SIZE Standard double width NIM module 6 86 x 22 12 cm 2...

Страница 68: ...tion 9660 ICB programmable Digital Signal processor 9660A ICB programmable Digital Signal Processor with automatic pole zero option installed Appendix A Specifications 62 Model 9660 9660A ICB Digital...

Страница 69: ...riangular shaping when the Flat Top is set to minimum or zero The triangular trapezoidal shaping function is symmetrical The fall time cannot be set independently it always equals the Rise Time select...

Страница 70: ...lude LEGe Si Li and X ray detectors resolution will be equal to or better than that obtained with traditional analog systems when the Rise Time and Flat Top filter parameters are optimized for resolut...

Страница 71: ...result of increased processing time and the effects of pulse pile up The optimum shaping time constant depends on the detector characteristics such as size noise characteristics and collection charac...

Страница 72: ...tion for ballistic deficit will be achieved by running the Auto BDC function again or manually checking the flat top setting if the rise time is increased or decreased by a factor of two or more Trian...

Страница 73: ...t the Pole Zero slider bar for correct pole zero compensation Figure 28 shows the correct P Z setting Figures 29 and 30 show under and over compensation for the preamplifier decay time constant As ill...

Страница 74: ...the LB1502 can still be used to make the pole zero adjustment see Figure 31 where the gain has been ad justed to produce wrap around Appendix B Performance Adjustments 68 Model 9660 9660A ICB Digital...

Страница 75: ...anual ICN 9231014G 69 Pole Zero Matching Supplementary Information Scope Vertical 50 mV div Horizontal 10 s div Source 60 Co Count rate 2 kcps Shaping 5 6 s rise time 0 8 s flat top Scope Vertical 500...

Страница 76: ...o Comp with Noisy Detector Scope Vertical 500 mV div Horizontal 50 s div Source 60 Co Count rate 2 kcps Shaping 8 s rise time 2 4 s flat top Figure 34 Overcompensated Pole Zero with Noisy Detector Sco...

Страница 77: ...s flexible and allows adjustment for varying baseline conditions affected by detector type noise and count rate The base line restorer rate is selected using the BLR mode drop down menu in the Filter...

Страница 78: ...by blinking green occasionally The fast discriminator threshold is properly set Note With the Fast Discriminator in the manual mode the threshold must be re checked and adjusted if the Detector Preamp...

Страница 79: ...her adjustment is required If RC is selected the pole zero value in the Filter Device Adjust screen must be manu ally set to zero Using the Reset Inhibit During the preamp reset interval the preamp re...

Страница 80: ...aseline Using a Tee connector connect the preamp s Inhibit signal to the INHIBIT BNC connector located on the rear panel of the 9660 Monitor the preamp s Inhibit signal and the 9660s Trapezoid signal...

Страница 81: ...6 s and Flat Top set to 0 8 s and using a Canberra Model 2101 preamp and 60 Co source User s Manual ICN 9231014G 75 Operation with Reset Preamps and Selecting Inhibit Mode Figure 36 Setting Reset Prea...

Страница 82: ...READY is set true The address data is now valid and can be accessed and used by the MCA or CPU Due to a two deep data buffer the 9660 can begin processing the next event even though data transfer to...

Страница 83: ...cessary signals for connection to the MCA Negative true signals are shown with a trailing asterisk ACEPT all other signals are positive true User s Manual ICN 9231014G 77 Data Connector Figure 38 Repr...

Страница 84: ...in detail All input and out put signals are TTL compatible Unless otherwise noted the input signal levels are Low 0 to 1 0 volts High 2 0 to 5 0 volts And the output signal levels are Low 0 to 0 5 vol...

Страница 85: ...o the MCA READY will be reset after receipt of signal ACEPT ACEPT 2 INPUT Data Accepted Signals the ADC that the data has been accepted by the MCA ACEPT may reset when READY resets handshake ENC or EN...

Страница 86: ...ions This section describes the function of each interface signal in detail All input and out put signals are TTL compatible Unless otherwise noted the input signal levels are Low 0 to 1 0 volts High...

Страница 87: ...line 7 LWE 14 Input Write Enable This signal is active when the ICB Master is writing to the ICB LDS 16 Input Data Strobe Used to latch the data into a slave during a write cycle or gate the data onto...

Страница 88: ...to cover open front panel Bin area Compliant grounding and safety precautions for any internal power distribution The use of CE compliant accessories such as fans UPS etc Any repairs or maintenance s...

Страница 89: ...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...

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