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1. The measurement window is split in windows In the window at the top on left hand the five counters the guard counter are marked with corresponding counts Integral CPM standard deviation and last status In the window below the last ten measurements are displayed To make a measurement click the start button or cancel to quit the Window 18 The check menu The Check menu enables you to check the efficiency and the backgound of each counter in the GM multicounter MCI MC4 In the Background check window you can set the preset time in min normally 100 min and for the Stability Check window 5 min for each measurement The check data will be shown graphically over a year show data menu The counter check is normally done once a week or month 1 To make a GM multicounter check click check in the menu bar and the check pull down menu bar appears 2 Click MCI MC1 MC2 in the menu bar and the counter check window appears Background check MC1 EG Preset time for background check P 1 1 tT L Place background briks in multicounter Press Ok when ready or cancel to stop check 1 Place the background bricks in the multicounter as described in the text window 2 Click the OK button and the counter check measurement window appears 19 Counter check MC1 x Preset time for stability check Preset Time min Place t2. 11 Bubble chamber from guard counter 12 Output to GM multicounter unit 13 HV output to GM multicounter unit 14 Test output HV 0 5 1 5 V 15 HV man switch on off 16 Input from GM multicounter 17 Output to personal computer 18 Main supply switch 115 230V ul 1 2 3 4 5 6 7 8 9 10 11 12 Fig 4 INSTALLATION AND INITIAL START UP PROCEDURE FOR GM 25 5 BETA MULTICOUNTER Read the instruction manual carefully Fill PEG 400 oil Polyethylenglycol enclosed into the bubble chamber with a syringe approximately 3 4 Access to the bubble chamber is made by removing the yellow plate with inscription CAUTION This side up situated on top of the disc ant coinc module Be sure that the gas flow valve on the rear of the disc ant coinc module Fig 3 is closed fully clockwise Connect the gas alarm unit between the two regulators where the pressure is 8 10 bar as shown in Fig 4 The gas alarm will beep 0 5Hz if the pressure is less than 6 Bar If the gas alarm beeps then close the gas cylinder and change to a new one as soon as possible If the gas alarm beep s every min the battery 9V must be changed Adjust the pressure regulator on the gas cylinder to an output pressure of 0 2 Bar and close the main high pressure valve on cylinder Connect gas tubes according to the diagram in Fig 4 NB The soft gas tubes should be as short as possible Remove the top of t
3. switch on the rear of the disc anticoincidence module Fig 3 HV man LED on the front plate is on Place the Tc test source in position 5 the most distant hole while holding the green sample slide and push it into the GM multicounter Lift the source by inserting the red lift slide under the green sample slide Slowly increase the high voltage by turning the high voltage potentiometer clockwise Observe the counter LED controls on the front of the disc anticoincidence module Increase the voltage until the green counter 5 LED is flashing The high voltage should now be about 1100 1400 V Press the HV man switch once on the rear of disc anticoincidence module HV man LED goes off The HV supply is now in automatic mode and is awaiting control signals from the GM 25 5 software The described manual procedure is only needed for an initial start up of the system Exchange of gas cylinder can be made without any readjustments Be careful not to empty the gas cylinder completely which may cause a slight underpressure that can result in oil to be sucked back into the counter unit A reservoir chamber is placed in connection with the bubble chamber as an emergency arrangement see Fig 5 Access to the bubble chamber and reservoir is made by removing the plastic frames on the front and back of the disc anti coincidence module and lifting of the top cover Oil sucked into the reservoir can be removed by a syringe RESERVOIR BUBB
4. To run GM multicounter l forexample Click Run in the menu bar and the run pull down menu appears 2 Click MCI in the menu bar the file open dialog box appears File Open Ea Filename Directory c mcw runinfo Directories 3 In the File open box you select the run info file you want to open To make a new run info file write the new name in the filename box the extension must be RIF 4 Double click the file name or choose the OK button and The run information window appears 16 c mcew datal In the run information window you can make your own settings General ID Text to identify the measurements Preset time Integration time for counting Preset cycles Enter how many measurements you want Data path Set drives and path for you data files Data name Write your data file name here Select EXT You can select three types of extensions SAM for Sample measurements BAC for Background measurements CAL for Calibration measurements Header Short description of measurement Click the OK button and the measurement window appears fm MCI Bl xj 0 0 Elapsed 0 0 Presettime 0 0 Preset cycle 10 Filename test SAM 00 High voltage Date Time Cycle CH 1 CH 2 CH 3 CH4 CHS GUARD oo Start Stop TTL TTT ATLL TTT eooeooooeoooco jooocoococoeocooc
5. CONTENTS Page Specification Sae i e P 2 IDDOSGPIDl o a AA E 3 Installation and initial start 6 The GM 25 5 software version for Windows sese 9 Loading the GM 25 5 software for Windows 10 Sample preparations oisein ene a uL tut p EE D D a 22 Shielding sao do eue e usted iut 23 Diagrams Five sample Low Level Beta GM Multicounter system GM 25 5 SPECIFICATIONS Low level gas flow beta multicounter system for measurement of 5 samples simultaneously Sample size 25 mm diameter Counter gas 99 Argon N48 1 Isobutane N25 or 99 Argon 1 propane N25 Sample counter elements 25 mm diameter with aluminized Mylar window lt 1 mg cm2 Guard counter 100 mm x 250 mm x 12 mm Background in 100 mm lead shielding 0 2 CPM typically 0 15 CPM Efficiency Sr Y activity prepared on 25 mm diameter filter paper attached to 5 mm thick Thallium disc 54 SC activity deposited on a 25 mm diameter x 5 mm thick plastic disc 44 1 mm thick acrylic source 25 mm diameter 24 Te Electro plated on steel disc 42 Size Mechanical unit 50 x 100 x 250 mm Other dimensions on request disc anticoincidence module 250x250x65 mm Description The basic part of the Ris low level beta multicounter system is a gas flow unit with dimensions of 50x100x250 mm which incorporates f
6. LE CHAMBER TUBE TUBE i 4 FRONT OIL INPUT Fig 5 Bubble chamber and oil reservoir connection The GM 25 5 software version for Windows The instructions for the window version of the RIS GM 25 5 software assume that you are familiar with the Microsoft Windows terminology and procedures and that you have installed Windows on your computer If you have not set up Windows on your computer or if you are not familiar with the use of Windows please read your Windows documentation Hardware and software requirements You need the following or better computer configuration to use the Ris GM 25 5 beta counter for Windows Computer True IBM compatible computer based on a 486 CPU or higher One free ISA slot is needed for the multiscaler analyser board Memory Minimum of 16 megabytes of Random Access Memory RAM is required Monitor Display with Video Graphics Array VGA or better resolution Mouse A Windows compatible mouse You will need one of the following operating systems to run the Ris GM 25 5 beta counter software Microsoft Windows version 95 98 or ME The beta counter will not operate with Win NT Win 2000 and Win XP 10 10 Loading the GM 25 5 software for Windows Switch on the personal computer Load your Microsoft Windows program Place the GM 25 5 software disk in your floppy drive Make sure that you are in the Microsoft Windows Program Manager Window Choose Run from the file me
7. ape the SETUP menu Setup x Hardware setup Path setup GM 25 5A C MCW data GM 25 5B C MCW CHECK v GM 25 5C GM 25 5D CAMCWARUNINFOY 22 SAMPLE PREPARATION Samples for beta counting are prepared on the enclosed nylon disc rings which are according to the Health and Safety Laboratory Procedure Manual HASL 300 USAEC The nylon sample disc ring consists of 1 Nylon ring 2 Nylon disc 3 Steel discs are provided for further reduction of the background and for reflection to improve counter efficiency Sr How to prepare a sample 1 Arrange a flat sample on the nylon disc A 2 Cover the sample with Mylar foil B 1 mg cm2 3 Press the ring around the disc to fix the Mylar foil and cut the Mylar foil overhang with a pair of scissors C 7 7 aes 7 AN CAUTION The total sample highs must not exceed 8 mm as the counter windows may be damaged 23 Two special lead bricks Delivered by RIS N e 3 Two 1 5 mm steel plates Delivered by RIS TOTAL NUMBER OF LEAD BRICKS Full size 200 x 100 x 50 mm 32 pcs Half size 100 x 100 x 50 mm 6 pcs Total weight of lead bricks 385 Kg SUGGESTED LEAD SHIELDING FOR BETA MULTICOUNTER MODEL RIS GM 25 5
8. data files There are three types of files with extension SAM Sample files BAC Background files CAL Calibration files To view the data click Data in the menu bar and the data pull down menu appears Click View in the menu bar and the File Open Dialog Box appears File Open x Directory c mcw data Directories From the list of files select the file you want to open or if the file you want to open is on a different drive or directory then us the Directories box Double click the file name or choose the OK button and the View Window appears 13 By using the scroll bars you can move parts of your data into view if the entire data file is too large to be displayed imi View window File c mcw data 3497 bac Counter Counts CPM Status 1 180 0 16 7 5 Presettime 100 2 162 0 14 7 9 Presetcycle 0 3 160 0 14 7 9 4 165 0 15 7 8 5 201 0 18 7 1 Guard 161992 144 07 0 2 Date Time Cycle Ch 1 Ch2 Ch3 Ch4 Ch5 Guard 29 04 97 15 24 32 1 14 16 15 14 18 14673 29 04 97 17 04 33 2 12 18 10 17 15 14589 29 04 97 18 44 34 3 10 10 15 19 15 14386 29 04 97 20 24 36 4 22 15 17 17 24 14470 29 04 97 22 04 37 5 18 11 15 12 15 14563 29 04 97 23 44 39 6 13 15 14 11 24 14417 30 04 97 01 24 40 7 12 13 10 14 18 14340 30 04 97 03 04 42 8 20 15 22 18 14 14165 E Print view l To print files click Print view in the menu bar and the File Open Dialog Box appears 2 From the list of files se
9. he personal computer and insert the multiscaler analyser board into a free slot Connect electronic cables between the personal computer and the disc ant coinc module NB The personal computer and the disc anticoincidence module must be switched off Place the counter unit into the lead shielding and be sure that the sample slide can move smoothly and that cables and gas tubes are placed properly Open the main valve on the gas cylinder Slowly open the gas flow valve on the back of the disk anticoincidence module until a fast but uniform bubble rate is observed in the bubble chamber Leave the counter in this flushing condition for some hours to remove air from the counter After flushing reduce the gas flow control valve to a flow rate of about 60 bubbles per minute and leave the counter for 6 hours Switch on the disc anticoincidence module PRESSURE REGULATOR REAR OF DISC ANT COINC MODULE nN REG BUBBLE 0 2 BAR IN COUNTER 8 10 BAR GASALARM i REAR OF MULTICOUNTER GM 25 5 GUARD COUNTER SAMPLE COUNTER Flow diagram of the counter gas connections to the multicounter GM 25 5 The pressure from the cylinder is reduced to 0 2 bar and the gas flow is adjusted with the flow regulator reg to approx 50 60 bubbles per min after warm up Note that the gas is led through the guard counter first and then through the sample counters 13 14 15 Nb Nb Switch to manual mode by activating the HV man
10. he test source in channel 1 Press Ok when ready or cancel to stop check After end background check the Counter check window will appear l Type your preset time 2 Place the test source as described in the text window 3 Click the OK button and the counter check measurement window appears After all five channels are done the program will return to the main window 20 The show data menu The show data menu is where you may view the efficiency of each counter in the GM multicounter within a year 1 Click show data in the check pull down menu bar and the file open dialog box appears p In the file open box you select the check file you want to open The extension is a for multicounter and e g 97 is the year 3 Double click the filename or choose the OK button and the view check data menu appears Ch3 Max 1078 00 ChS Max 1062 00 Ch3 Min 932 00 CHS Min 962 00 check a97 Ch3 Max 018 ChS Max 021 Ch Min 0 10 ChS Min 0 17 I 21 The setup menu The SET UP menu is a hardware and path setup window where you select the numbers of counters A B C D which depend on the actual counters you have and path for Data Check and Run info The GM 25 5 software for Windows is designed to operate four multicounters independently at the same time In the check boxes you can select the number of counters you have available Click OK to esc
11. ic radiation The net signals from the sample counters are fed to a multiscaler analyser circuit board mounted directly into a slot of an IBM compatible personal computer A pulse height analysing system is provided to automatically control that the high voltage is maintained at a proper value i e well within the GM voltage plateau The analyser system continuously compensates for varying gas flow and atmospheric pressure The software controls start stop re cycle preset time and pulse height analysing functions The results of repeated measurements continuously appear on the computer screen by using different programs and data files can be stored for further calculations and analyses 4 GUARD COUNTER BES lt SAMPLE COUNTER V PRE AMP PERSONAL COMPUTER A COINC MULTISCALER ANALYSER BOARD Fig 2 Block diagram of the electronics for the five sample multicounter BETA MULTICOUNTER SYSTEM GM 25 5 Riso National Laboratory Denmark Fig 3 Discriminator anticoincidence module 1 LED indicators for sample counters 1 5 and the guard counter 2 Main power LED 3 HV man LED ON 4 HV man regulator 500 1500 V 1 10 on potentiometer 5 Bubble chamber 3 4 full with PEG 400 oil 6 Bubble chamber top 7 Main power ON OFF switch 8 Main fuse 9 Gas flow regulator 10 Gas input 0 2 bar from main gas regulator
12. ive individual GM sample counter elements and a common guard counter Fig 1 DTE ZZZ Eig 1 The five sample beta GM multicounter schematically 1 Guard counter 2 Mylar window 3 Sample counter 4 Sample 5 Sample slide 6 Lift slide 7 Preamp 8 Acrylic frame 9 Cu plate 10 Anodes The guard counter reduces the cosmic ray background by using anticoincidence technique Each sample counter element is provided with an aluminized Mylar window of density lt 1 mg cm2 and diameter 25 mm The counters are gas flow types designed for 99 Ar 1 isobutane or 99 1 propane counter gas A sample slide allows five samples to be inserted into the multicounter and be measured simultaneously lift mechanism minimizes the sample to window distance to obtain optimal efficiency The multicounter is normally placed inside a lead shielding of 100 mm thickness to reduce the ambient background radiation Another part is an electronic system for treatment of the signals produced by the beta particles in the GM multicounter A block diagram of the electronic circuit is shown in Fig 2 Preamplifiers placed on the gas flow counter unit produce signals from the individual counter elements that are fed to the discriminator anticoincidence module see Fig 3 which also incorporates an automatically controlled high voltage supply The anticoincidence circuits eliminate the background counts produced in the sample counters by cosm
13. lect the file you want to print and the print data file window appears 3 Click Print in the menu bar to print out data The high voltage menu The High Voltage menu enables you to control the high voltage in ways Manual or Auto Click High Voltage in the menu bar and the high voltage pull down menu appears Click MC1 in the menu bar and the high voltage setting window appears MCI is multicounter number 1 14 Auto control The Auto Control is a pulse height analyzing system and is provided to auto matically ensure that the high voltage is maintained at a proper value i e well within the GM voltage plateau Be sure that the HV man LED located at the front of the Disc anticoincidence module is switched off If not then press the man switch located at the rear of the Disc anticoincidence module Place the test source in position 5 the most distant hole while holding the green sample slide and push it into the GM multicounter see text window 1 Select Auto in the control check box 2 Click the Start button in the high voltage window The high voltage now slowly increases When the following text appears Plateau test finished then click the OK button The high voltage is now at the proper value Manual control The Manual control is only used to check the GM multicounter The Run Menu The Run menu is used to select which GM counter to run MCl MC4 1
14. nu to display the Run Dialogue box In the Command Line Text Box enter the text a install Click OK The GM 25 5 install program begins Make a Program Group named Beta Multicounter Click New from the File menu Select the Program Group option and click OK The Program Group Properties Dialogue box appears Type Beta Multicounter in the description box and click OK Click New from the File Menu Select the Program Item Option and click OK The Program Item Properties Dialog Box appears Type MCW in the description box and a mcw mcw exe in the Command Line Box Click OK You can now start the GM 25 5 multicounter program by double clicking its icon The Beta Multicounter Window 11 When you start MCW Multicounter for Windows the beta multicounter window appears in full screen size E Beta multicounter Risoe National Laboratory MT Software 1997 Version 1 50 Data High voltage Run Check Setup Beta Multicounter Menus Like many Windows applications the beta multicounter program has pull down menus that list commands by name Example Click Data in the menu bar and the data pull down menu appears The Beta multicounter include following pull down menus Data Run View Print view High voltage Check MCI MC2 MC3 MC4 MCI MC2 MC3 MC4 MCI MC2 MC3 MC4 Show data Setup MCI MC2 MC3 MC4 The Data menu View The Data menu lets you view and print
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