SPECTECH. ST450 Scintillation SCA. ST450-PC System. Operating Manual. Spectrum Techniques, Inc. January 2015

Transcription

1 SPETEH ST0 Scintillation S ST0P System Operating Manual January 0 Spectrum Techniques, Inc.

2 ST0 System shown with ST0 ounter and detector. Model ST0 Introduction The ST0 Scintillation S is a selfcontained instrument for measuring energy specific gamma ray emission using a scintillation detector. The ST0 may also connect to a ST0 (replacement for the ST0) and serve as a single channel analyzer to provide gamma ray energy selection. The basic unit provides the following features: High Voltage supply to power the detector or photomultiplier. harge Sensitive Preamplifier Bipolar Shaping mplifier to process the signal prior to analysis djustable Baseline ontrol djustable window ontrol Integral and Differential Modes hen combined with the Spectech ST0 Radiation ounter and a P or Macintosh computer, the following features are added: Digital readout Preset Time Preset ounts RMP mode for automatic Baseline incrementing omputer ontrol Data Storage Other models of counter/timers that accept a positive logic input signal may be used by connecting them to the S output. The ST0 is designed to operate either with negative anode signals directly from a detector or with positive output signals from an external scintillation preamplifier. Scintillation detectors and photomultipliers utilizing a negative high voltage supply are not compatible with the ST0. Normally the ST0 utilizes a MHV high voltage connector, but this may be substituted with a SHV high voltage connector on special order.

3 Specifications Preamp In mp In mp Out S Out ST0 In High Voltage Power Input harge sensitive preamplifier for connecting to the anode output of the detector. This input is used for detectors with a simple voltage divider type tube base producing negative anode output signals. Direct input to the shaping amplifier, used for connecting an external preamplifier producing positive signals. Positive leading bipolar output from the shaping amplifier for connecting to a multi channel analyzer or other external electronics. 00 volt range set by coarse and fine gain controls, µsec. peaking time. Positive TTL compatible pulse output,.µsec. duration. Provides an interface to the ST0 via its GM tube connector for counting and remote baseline control volt positive supply with m maximum current capability. Fully regulated and controlled by 0turn direct reading potentiometer. MHV and SHV connectors. volt from power module supplied, P/N M00 for V operation. ontrols and Indicators Power High Voltage Push button turns on power to unit and lights the indicator. Push button turns on high voltage and lights the indicator. H. V. djust Direct reading 0turn potentiometer sets high voltage output level, 0000 volts. oarse Gain position rotary switch sets amplifier gain from X to X. Fine Gain 0turn direct reading potentiometer sets fine gain from 0.X to.x. Baseline 0turn potentiometer sets the baseline from 0% to 00%. indow turn potentiometer sets the window from % to 0%. ctivity Integral Mode External Scan Indicates when pulses are being received and processed by the ST0. Push button switches between Integral and Differential mode and lights the indicator. hen the Integral Mode is ON, the indow control is defeated and all counts from the Baseline setting to 00% are amplified and outputted. Push button switches the Baseline control from the Baseline dial on the front panel to the ST0 IN connector on the rear panel and lights the indicator. the baseline is now controlled by the high voltage setting on the ST0.

4 ST0 Front Panel ST0 Rear Panel

5 onnecting Peripherals to the ST0 Scintillation Detectors onnect the anode (signal) output from the detector to the Preamp In connector of the ST0. Using the appropriate cable (MHV or SHV, depending on the detector), connect the High Voltage output from the ST0 to the detector s high voltage connection. Multi hannel nalyzer To use the ST0 with a multi channel analyzer, connect the ST0 s mp Out to the M s D (direct) input. ST0 and ST0 To use the ST0 with the ST0 counter/timer or the ST0 rate meter, connect the ST0 s ST0 IN connector to the ST0/0 s GM TUBE connector. Other ounters and Tube Bases Other counters used with the ST0 must have a TTL compatible input. onnect the ST0 s S OUT to the counter s input. Some detector tube bases such as the Tennelec model T incorporate a builtin preamplifier which takes its power from the high voltage supply. In this instance, the output signal from the preamplifier must be connected to the MP IN connector on the ST0. lso, if an external preamplifier with a positive output signal is used, connect the preamplifier s output to the MP IN connector of the ST0. ST0 alibration The ST0 is normally calibrated using a S source with the Fine Gain set to.0, the oarse Gain set to, the Baseline set to.%, and the indow set to %. The High Voltage is then set to provide the maximum count rate at the S Out. alibrate the ST0 as follows (NOTE: a rate meter such as the ST0 or ST0 is required to perform this calibration):. onnect the detector to the ST0 as indicated above.. Place a S source in the well/tray of the detector.. onnect the ST0/0 s GM TUBE connector to the ST0 IN connector of the ST0. If using a rate meter with a TTL compatible input, connect it to the S OUT of the ST0.. Set the ST0 s controls to the following settings: Fine Gain:.00 oarse Gain: Baseline:.% indow: 0% High Voltage: ON H. V. djust: 00 Volts Integral Mode: OFF Ext Scan: OFF. hile monitoring the counts with a rate meter, slowly increase the detector s high voltage until the unit begins to count. ontinue increasing the high voltage, the countrate should peak and then reduce somewhat. ontinue adjusting the high voltage up and down until the peak countrate is obtained.. Set the indow to 0% and again, adjust the high voltage for the highest count rate.. Set the indow to % and adjust the Fine Gain to obtain the highest count rate. The Baseline control will now be calibrated to read directly in kev and the indow with set at 0 kev.

6 ST0 Operation Single hannel nalyzer Once the ST0 is calibrated with a detector, it may be used with the ST0 to isolate and count a specific energy peak. This is accomplished as follows:. onnect the ST0 to the ST0 as indicated in the onnecting Peripherals to the ST0 section.. Turn the EXT SN switch OFF.. Set the Baseline control to the energy of the peak to be measured. t this setting, the ST0 will amplify and output only the counts in the energy peak. s the resolution of the detector varies with energy, it is always best to adjust the indow setting to the approximate width of the peak and using a check source of the specific isotope to be measured, readjust the Baseline control to obtain the maximum countrate.. Set a Preset Time and press ount. The ST0 will display the counts in the specified energy peak when counting is complete. s Spectrum kev % indow Energy kev o Spectrum kev % indow kev Energy

7 Using the ST0 and ST0 ombination. The ST0 Radiation ounter provides a convenient counter/timer for use with the ST0. This instrument also offer interfacing to a P or Macintosh computer for data storage and external baseline control. This feature allows the user to acquire a complete gamma spectrum of the sample being measured and aids in the selection of the correct window setting. onnect the ST0 IN to the GM INPUT on the ST0. Manual Mode Turn on power to both instruments Ensure the EXT SN button is not depressed and the high voltage on the ST0 is set to zero. Select TIME and use the up/down buttons on the ST0 to select the required counting time. Return the selector switch to the OUNTS position and preset the OUNT key. The ST0 will acquire data for the selected preset time and display the counts. To use the RTEMETER mode, set the counting time to zero, select RTEMETER and press OUNT. The ST0 will now function as a digital ratemeter which is useful when calibrating the system. More information on useing the ST0 may be found in the instrument manual. omputer Operation onnect the serial cable from the ST0 to the P or Macintosh and load the appropriate software. Set the selector switch to the REMOTE position and turn on the power. Run the ST0 software. communication link will be established. Operation of the ST0 will now be from the computer. Data will now be recorded as a sequence file that may be saved as a SI file or transferred through the clipboard for opening with a spreadsheet such as Excel. Performing a Spectrum Sweep. The high voltage supply in the ST0 may be used to control the baseline setting of the ST0. This feature allows a complete gammaray spectrum of the sample to be acquired which can be very useful for determining correct calibration and window settings. the system is organized so that a high voltage setting of 00 volts on the ST0 corresponds to a baseline of zero (min.) and 00 volts corresponds to a baseline of 000 (max.). Using the Lablink software, set the ST0 high voltage to 00 volts. Set the voltage step to 0 volts and turn on the Ramp. Set Runs to 00. Set Preset Time to 0 sec. Set INDO on the ST0 to %.

8 Select the EXT SN button. Place the sample on the detector. Start the ST0 counting. The ST0 will now begin counting at zero baseline reference. t the completion of the 0 sec counting period the ST0 will record the data, increment the high voltage by 0 volts, decrement the run counter, reset the data and begin a new count. This process will continue until 00 measurements have be recorded to the maximum voltage value of 00 volts on the ST0 corresponding to a baseline value of 000. t the end of the run the ST0 voltage will be restored to 00 volts and the data may be saved as a *.TSV file for exporting to a spreadsheet such as Excel for graphing Typical Spectrum Sweep of s Source.

9 SIGNL OUT HIGH VOLTGE IN P/M SERIL PORT ST0 GM TUBE DT LINK/ REMOTE SINTILLTION DETETOR ST0 IN PREMP IN HIGH VOLTGE ST0 System onnection Diagram

10 ipe Testing ipe tests are inherently lowlevel measurements and it is necessary to perform background subtraction on all samples to generate accurate activity data. Because the background reading is low, it is normally counted for a longer period to improve the statistics. The following steps illustrate a typical wipe testing procedure:. Set up the ST0 as described in the Single hannel nalyzer section for the energy peak of the source being tested.. Remove all radioactive material from the vicinity of the detector.. Set a preset time of 00 sec. and begin the counting.. hen the unit completes the count, record the value and divide the reading by 0 to derive the background counts/min.. Position the sample into either the well of the detector or in the sample tray, depending on which detector is being used.. Set the preset time to 0 seconds and press STRT.. hen the unit timesout record the number of counts.. Subtract the background counts/min. and record the net value. This is the counts/minute for the sample. This concludes the ST0 Instruction Manual. If any problems are encountered or further information is needed, please contact Spectrum Techniques at (), spectech@esper.com. Manufactured by: Spectrum Techniques, Inc. 0 Union Valley Road Oak Ridge, TN 0 US Tel: () Fax: () 0

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