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Appendix A  Specifications  

A.  Specifications 

Input 

TEST INPUT - Accepts signal from external pulser; Z

in

 = 93 

Ω

; gain nominally X 

10; rear panel BNC. 

Outputs 

ENERGY OUTPUT - Provides positive, linear near-Gaussian shaped unipolar pulses 
proportional to energy, linear to + 10 V; max output 12 V; dc restored; Z

out

 = 10 

Ω

; 

short circuit protected; rear panel BNC. 

TP (Test Point) - Replica of the energy output signal; isolated by 1 k

Ω

 resistance; 

front panel mounted pin jack. 

COUNTS OUTPUT - NIM-standard positive logic pulse available on rear panel 
BNC connector for driving external counter; pulse width nominally 3.5 

µ

s for any 

event above discriminator setting; Z

out

 

≈

 50 

Ω

, dc coupled. 

Display 

Multi-purpose 5-digit LED display shows chamber pressure in 

µ

m Hg (mm Hg on 

the 7401VR), detector leakage current (

µ

A), gross counts, elapsed time, preset time, 

high voltage bias, discriminator level (MeV), and calibration pulser level (MeV); 
time readout in seconds or hours. 

Front Panel Controls and Indicators 

BIAS ON/OFF - Toggle switch controls high voltage supply 

BIAS LED Indicator - Blinks when high voltage is inhibited and while supply is 
increasing to preset value; solidly illuminated when supply approaches final value. 

FUNCTION LED Indicators - One of eight LEDs is illuminated when corresponding 
function is selected for display; COUNTS LED blinks when counter is active; CAL 
LED blinks when calibration pulser is active. 

INCREMENT/DECREMENT - Dual purpose momentary toggle switch selects 
display function and sets preset time, HV bias, calibration pulser level or 
discriminator level. 

DIGIT SELECT - Pushbutton switch chooses display digit to be incremented or 
decremented; operable when setting preset time, HV bias, calibration pulser, or 
discriminator level. 

20 

7401/7401VR Alpha Spectrometer User’s Manual - 9231603C 

Содержание 7401

Страница 1: ...Model 7401 7401VR Alpha Spectrometer 9231603C User s Manual ...

Страница 2: ...gal 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 commercial purpose or for any use other than that granted to the purchaser without the written permission of Mirion Technologies Canberra Inc Mirion Technologies Canberra Inc 800 Research Parkway Meriden CT 06450 Tel 203 238 2351 FAX 203 235 1347 http ...

Страница 3: ...g Bias the First Time 10 Previous Bias Setting 11 Sample Placement 11 System Calibration 11 Using the Discriminator Counter Timer 12 Multiple 7401s On a Single Pump 12 4 Circuit Description 16 Preamp Amp 16 Auxiliary Circuits 17 Power Supplies 17 Vacuum Gauge 18 Calibration Pulser 18 Discriminator 19 Analog to Digital Converter 19 Microprocessor and Control Circuits 19 A Specifications 20 Input 20...

Страница 4: ...ation 25 Cleaning 25 C Power On Error Codes 26 D Self Test 27 Switch Test Test 1 27 Display Test Test 2 28 A D Test Test 3 28 HV Bias Test Test 4 28 Calibration Pulser Pot Test Test 5 28 Discriminator Digital Pot Test Test 6 29 Pulser Amp Discriminator Test Test 7 29 E Chamber Cleaning 30 F Installation Considerations 31 G FCC Notice 32 ii 7401 7401VR Alpha Spectrometer User s Manual 9231603C ...

Страница 5: ...of caution symbol wherever marked Earth tree symbol indicates the connection point for the primary earth ground supply Product complies with appropriate current EU directives Low Voltage EMC Product complies with appropriate current FCC UL CSA 61010 1 directives Low Voltage EMC Manufacturer s Address Mirion Technologies Canberra Inc 800 Research Parkway Meriden CT 06450 USA 7401 7401VR Alpha Spect...

Страница 6: ...Notes iv 7401 7401VR Alpha Spectrometer User s Manual 9231603C ...

Страница 7: ...mature application of bias to the detector a switchable interlock inhibits the bias supply until proper pressure is reached then the high voltage is slowly increased to its predetermined setting in approximately one minute The preamp and amplifier provide optimal pulse shaping and signal conditioning for detectors used in Alpha Spectroscopy Gain and offset of the amplifier can be adjusted by means...

Страница 8: ... and Connector This is a brief description of the 7401 s controls and connectors For more detailed information refer to Appendix A Specifications Front Panel Figure 1 Front Panel Connectors 2 7401 7401VR Alpha Spectrometer User s Manual 9231603C ...

Страница 9: ...Rear Panel Rear Panel Figure 2 Rear Panel Connectors 7401 7401VR Alpha Spectrometer User s Manual 9231603C 3 ...

Страница 10: ...Chapter 2 Controls and Connector Internal Controls Figure 3 Internal Controls 4 7401 7401VR Alpha Spectrometer User s Manual 9231603C ...

Страница 11: ...um Chamber Vacuum Chamber Note For Reverse Sample Bias Kit installation see drawing B 26491 which can be ordered from Canberra Figure 4 Vacuum Chamber 7401 7401VR Alpha Spectrometer User s Manual 9231603C 5 ...

Страница 12: ...f the unit is seated in the Bin s top and bottom guide rails After seating the unit firmly into the Bin s power connector turn the 7401 s front panel captive screws clockwise until finger tight The Model 7401 can be operated where the ambient air temperature is between 0 and 50 C 120 F maximum Perforations in the top and bottom of the 7401 allow cooling air to circulate through the unit When the 7...

Страница 13: ...Pump The vacuum pump is connected to the Model 7401 vacuum fitting located on the rear panel The outside diameter of the fitting is 9 5 mm 3 8 in Use metal tubing and high quality rubber couplers wherever possible in the vacuum line to minimize outgassing and to ensure a short pumpdown time Connecting the MCA Using 93 ohm cable type RG 62 connect the ENERGY Output of the 7401 to the ADC input of t...

Страница 14: ...nd to change the 7401 s settings To change the display function first make sure that no single digits are blinking If a single digit is blinking press the DIGIT SELECT Switch one or more times until all digits are steadily lit Then use the INCrement DECrement Switch to choose a different function The selected function s LED will turn on If all digits on the display are blinking at once an overrang...

Страница 15: ...If the BIAS Function is selected the display always indicates the voltage applied to the detector bias network If the BIAS Switch is turned off the bias will remain close to zero volts Once the BIAS Switch is turned on the display will show the detector voltage as it increases to the bias level stored in internal memory Initializing The Display The front panel display is initialized to show the Bi...

Страница 16: ...he high voltage has been reset to approximately zero volts turn the BIAS Switch on CAUTION Avoid applying excess voltage to the detector Wait approximately one minute after turning on the BIAS Switch until the BIAS on off LED stops blinking before increasing the voltage This will allow time for the bias voltage to stabilize 3 Starting with the bias at approximately zero slowly increment the bias t...

Страница 17: ...re 6 After the chamber is pumped down and the Bias voltage has stabilized data collection may be started At the end of the experiment set the BIAS Switch to off vent the chamber and open the door to remove or replace the sample System Calibration To calibrate the system insert a known source in the chamber accumulate a spectrum and use the 7401 gain control to position the isotope peak at the desi...

Страница 18: ...ont panel switches to initialize the display see Initializing the Display on page 4 The COUNTS output on the rear panel is available to drive an external counter with the discriminator output Multiple 7401s On a Single Pump A single vacuum pump can be connected to more than one 7401 however the pump down time may increase To connect more than one unit to the vacuum pump you must install a fitting ...

Страница 19: ...and open the chamber door Let the valve return to the HOLD position See Figure 6 Vacuum in adjacent chambers should not change 4 After servicing the chamber firmly close the chamber door 5 Pull the chamber valve handle to the PUMP position and lock it by rotating the handle 1 4 turn counterclockwise Figure 6 The pressure in adjacent chambers will momentarily rise then decrease as the pump removes ...

Страница 20: ...he 7400 14 makes it possible to service individual chambers without affecting the pressure in other chambers attached to the same pumping system The 7400 14 requires one vacuum pump such as the Model 7400 01 or 7400 02 for each of the unit s two manifolds The manifolds are connected to the vacuum chambers by means of three way valves In this way the high vacuum manifold can remain at constant pres...

Страница 21: ...ctrometers in the system Routine Operation of the 7400 14 1 Always evacuate chambers with the valve in the Pump Down position 2 When the pressure in the chamber reaches the normal operating range turn the valve to the High Vacuum position 3 Before opening a chamber turn the associated manifold valve to the pump down position 4 Before re evacuating a chamber check to see that the associated manifol...

Страница 22: ...ifier Q12 and Q11 output follower FET Q13 and current sinks Q20 and Q19 This group of devices functions as an inverting feedback amplifier whose closed loop gain is set by the charge integrating capacitor C122 Internal bias currents for FET Q14 loop gain and compensation are set to provide best performance for the large area thin detectors most commonly employed for low level alpha particle counti...

Страница 23: ...itor C120 couples the positive pulse into the simple restorer provided by Q23 This circuit stabilizes the dc reference level for the pulse in order to maintain a proper baseline from which the output may be quantized in an ADC or SCA Output amplifier A26 provides the final stage of gain and permits the introduction of a dc offset zero adjust controlled by a front panel potentiometer D5 limits the ...

Страница 24: ... back to back Zener diodes D17 and D18 and through RV15 into a current transformer The gauge output is a dc voltage representing the temperature of a thermally isolated heater wire as influenced by static air pressure or vacuum in the chamber Amplifier A2 boosts the low level DC signal and sends it to comparator A1 and to the A D for digitizing and subsequent linearization by the microprocessor Th...

Страница 25: ...rcuits The microprocessor controls the front panel switch and display functions the counter timer and the three digital pots It also reads the internal A D converter scaling and linearizing the data for display The processor sends display information to display driver A21 whose power supply is regulated by shunt regulator D32 This regulator prevents excessive low frequency ripple from appearing on...

Страница 26: ...oss counts elapsed time preset time high voltage bias discriminator level MeV and calibration pulser level MeV time readout in seconds or hours Front Panel Controls and Indicators BIAS ON OFF Toggle switch controls high voltage supply BIAS LED Indicator Blinks when high voltage is inhibited and while supply is increasing to preset value solidly illuminated when supply approaches final value FUNCTI...

Страница 27: ...threshold Internal Controls VACUUM BIAS INTERLOCK SET POINT Dual position jumper chooses vacuum level at which bias is enabled 7401 nominal trip level is 100 or 500 µm Hg 13 or 67 Pa factory set to 500 µm Hg 67 Pa 7401VR nominal trip level is 0 3 mm Hg 0 04 kPa or 10 mm Hg 1 33 kPa factory set to 10 mm Hg 1 33 kPa BIAS POLARITY Toggle switch sets polarity of HV supply and internal pulser Factory s...

Страница 28: ...er than 50 ppm C Display Resolution 10 keV DISCRIMINATOR Range 0 1 to 10 MeV Display Resolution 10 keV DETECTOR CURRENT MONITOR Range 0 to 20 00 µA Display Resolution 0 01 µA VACUUM GAUGE 7401 Range 0 to 1000 µm Hg 0 to 133 Pa 7401VR Range 0 to 20 mm Hg 0 to 2 67 kPa COUNTER Count Range 0 to 99 999 counts Time Range 0 to 99 999 seconds or 0 to 999 99 hours Preset Time Range Same as Time Range Time...

Страница 29: ...m fitting mounted through rear panel DETECTOR Axial microdot Power Requirements 12 V dc 250 mA 24 V dc 100 mA 12 V dc 50 mA 24 V dc 50 mA Physical SIZE Standard double width NIM module 6 86 X 22 12 cm 2 70 X 8 71 in per DOE ER 0457 1990 NET WEIGHT 2 5 kg 5 5 lb SHIPPING WEIGHT 3 2 kg 7 0 lb VACUUM CHAMBER AND HARDWARE 8 16 X 6 03 X 6 25 cm 3 25 X 2 375 X 2 5 in height width depth Stainless steel c...

Страница 30: ...1010 Installation Category I Pollution Degree 2 Options MODEL 7401 RSB Reverse Sample Bias Includes four 3 V batteries mounted on the sample shelf The average battery life is 8 years MODEL 7401VR Alpha Spectrometer Same as 7401 except the pressure gauge has a range of 0 to 20 mm Hg 0 to 2 67 kPa also includes Model 7401 RSB Reverse Sample Bias option Model 7401SH 3 sample holder for 19 mm 3 4 in s...

Страница 31: ...ce at least one detector diameter away from the detector face Resolution will not be as good with the source closer because of the more acute angle of particle travel through the entrance window Alpha sources do not emit monoenergetic alphas but have an intrinsic line width that contributes to system resolution Our detectors are tested using good quality sources such as the NBS 4904G The use of ol...

Страница 32: ...AM is on board the micro processor E2 Checksum error for program code in EPROM on board the microprocessor E3 A D error No change in A D status line within a 100 ms time period E4 The ac power line was not detected by the module Module will use internal timer as time base E5 The ac power line was detected by the module but the line frequency is not within 0 5 Hz of 50 or 60 Hz Module will use inte...

Страница 33: ...cates an error After each test is finished the program returns to the select mode NOTE When the self tests are executed the digital pot settings for Bias Calibration pulse level and Discriminator level will be altered After completing the self tests resume normal operation by cycling power or using the front panel switches to reset the unit see Initializing the Display on page 9 Switch Test Test 1...

Страница 34: ...RT switch must be pressed to continue Before starting this test turn on the bias voltage If the test is begun with the bias off the bias on off LED will blink reminding you to turn on the bias It takes about a minute to stabilize the high voltage E 4 0 Pot cannot be set to lowest setting E 4 1 Pot fails mid point check E 4 2 Pot fails high setting check E 4 3 Pot fails step size check After comple...

Страница 35: ...t fails mid point check E 6 2 Pot fails high setting check E 6 3 Pot fails step size check Pulser Amp Discriminator Test Test 7 Checks that test pulser amplifier and discriminator are calibrated and work correctly as a system E 7 0 No counts detected with discriminator level below pulser level E 7 1 Erroneous counts detected with discriminator level above pulser level 7401 7401VR Alpha Spectromete...

Страница 36: ...void contaminating the vacuum path Plug the hole if necessary Also avoid introducing cleaners into the vacuum gauge mounted at the top of the chamber If the large detector mounting bushing is removed for any reason or if the detector BNC Microdot connector is removed from the bushing care must be taken when re threading the plastic parts Care must also be exercised when removing and replacing the ...

Страница 37: ...MC 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 external cable access Blank panels 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 A...

Страница 38: ...ce pursuant to Part 15 of the FCC Rules These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment This equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with the instruction manual may cause harmful interference to radio communications Operation of this...

Страница 39: ... OTHERWISE SHALL APPLY IN NO EVENT SHALL WE HAVE ANY LIABILITY FOR ANY SPECIAL EXEMPLARY PUNITIVE INDIRECT OR CONSEQUENTIAL LOSSES OR DAMAGES OF ANY NATURE WHATSOEVER WHETHER AS A RESULT OF BREACH OF CONTRACT TORT LIABILITY INCLUDING NEGLIGENCE STRICT LIABILITY OR OTHERWISE REPAIR OR REPLACEMENT OF THE SOFTWARE OR EQUIPMENT DURING THE APPLICABLE WARRANTY PERIOD AT OUR COST OR IN THE CASE OF DEFECT...

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