Mengliang Instrument palmRAD 907 User manual

palmRAD 907
Nuclear Radiation Monitor
Operating Manual
Shanghai Mengliang Instrument Co., Ltd.
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URL:www.menglianggroup.com

Revision: September 2005
Shanghai Mengliang Instrument Co., Ltd.
TEL:[phone]
URL:www.menglianggroup.com

Copyright 1996, 2005 by Berkeley Nucleonics Corporation. All rights reserved.
Shanghai Mengliang Instrument Co., Ltd.
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Contents
1 Introduction 1
How the palmRAD 907 Detects Radiation 1
Precautions 2
2 Features 3
The Display 4
The Switches 5
The Detector 6
The Input/ Output Ports 7
3 Operation 8
Units of Measurement 8
Starting the palmRAD 907 8
Operating in the Dose Rate Modes 8
Operating in Total/ Timer Mode 9
Operating Ranges and Response Times 10
Using the Alert 11
The Utility Menu 11
Interfacing to an External Device 12
4 Common Procedures 13
Establishing the Background Count 13
Environmental Area Monitoring 13
Checking for Surface Contamination 14
5 Maintenance 15
Calibration 15
Troubleshooting 17
Service 18
6 Basics of Radiation and Its Measurement 19
Ionizing Radiation 19
Radiation Measurement Units 20
Appendix A Technical Specifications 21
Appendix B Technical Update 22
Warranty 23
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1
1 Introduction
The palmRAD 907 is a health and safety instrument that is optimized to detect low
levels of radiation. It measures alpha, beta, and gamma radiation. Its applications
include:
Detecting and measuring surface contamination
Monitoring possible radiation exposure while working with radionuclides
Alerting you with an audible alarm if the radiation goes above the an alert level that
you set
Screening for environmental contamination
Detecting noble gases and low energy radionuclides
How the palmRAD 907 Detects Radiation
The palmRAD 907 uses a Geiger- Mueller tube to detect radiation. The Geiger tube
generates a pulse of electrical current each time radiation passes through the tube and
causes ionization. Each pulse is electronically detected and registers as a count. The
palmRAD 907 displays the counts in the mode you choose: counts per minute (CPM),
milliroentgens per hour (mR/ hr), or total counts. In SI units, counts per second (CPS)
and microsieverts per hour ( Sv/ hr) are used.
The number of counts detected by the palmRAD 907 varies from reading to reading due
to the random nature of radioactivity. A reading is expressed more accurately as an
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average over time, and the average is more accurate over a longer time period. For more
information, see Operating in Total/ Timer Mode in Chapter 3.
Precautions
To keep the palmRAD 907 in good condition, handle it with care, and observe the
following precautions:
Do not contaminate the palmRAD 907 by touching it to radioactive surfaces or
materials. If contamination is suspected, you can replace the rubber strips above
and below the rear label with the extra strips supplied with the palmRAD 907.
Do not leave the palmRAD 907 in temperatures over 122 F (50 C) or in direct
sunlight for extended periods of time.
Do not get the palmRAD 907 wet. Water can damage the circuitry and the coating
of the mica surface of the Geiger tube.
Avoid making measurements with the detector window in direct sunlight; this could
affect the readings if the coating of the mica surface of the Geiger tube has been
damaged by moisture or abrasion.
Do not put the palmRAD 907 in a microwave oven. It cannot measure microwaves,
and you may damage it or the oven.
If you expect to not use the palmRAD 907 for longer than one month, remove the
battery to avoid damage from battery corrosion.
Change the battery promptly when the battery indicator appears on the display.
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3
2 Features
The palmRAD 907 measures alpha, beta, gamma, and x- ray radiation. It is optimized to
detect small changes in radiation levels and to have high sensitivity to many common
radionuclides. For more information, see Appendix A, "Technical Specifications."
This chapter briefly describes the palmRAD 907's functions. For more information on
how to use the palmRAD 907, see Chapter 3, "Operation."
The palmRAD 907 counts ionizing events and displays the results on the liquid crystal
display (LCD) (4). You control which unit of measurement is shown by using the mode
switch.
Whenever the palmRAD 907 is operating, the red count light (1) flashes each time a
count (an ionizing event) is detected.
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4
The Display
Several indicators on the LCD show information about the mode setting, the current
function, and the battery condition.
The numeric display (A) shows the current radiation level in the unit specified by
the mode switch setting.
A small battery (B) appears to the left of the numeric display to indicate low battery
voltage.
A radiation symbol (C) appears when the Alert feature is on.
An hourglass (D) appears during a timed count.
TOTAL (E) appears when the palmRAD 907 is in Total/ Timer mode.
X1000 (F) appears when the radiation level is displayed in X1000 mode.
MENU (not shown) appears when you are in the Utility menu.
CAL (G) appears while you are calibrating the palmRAD 907.
SET (H) appears when you are setting the timer, the Alert level, and the calibration
factor, or working in the Utility menu (the numeric display shows the setting you
are adjusting instead of the current radiation level).
The current unit of measurement (I)- - CPM, CPS, mR/ hr or Sv/ hr- - is
displayed to the right of the numeric display.
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5
The Switches
The palmRAD 907 has two switches on the front, and one switch and three buttons on
the end panel. Each switch has three settings, which are described below.
On/ Off/ Audio Switch (7)
Audio. The palmRAD 907 is on, and it makes a clicking sound for each radiation
event detected.
On. The palmRAD 907 is operating, but audio is off.
Off. The palmRAD 907 is not operating.
Mode Switch (6)
mR/ hr Sv/ hr. The numeric display shows the current radiation level in
milliroentgens per hour from .001 to 100. When SI units are used, it shows the
current radiation level in microseiverts per hour, from .01 to 1000.
CPM CPS. The display shows the current radiation level in counts per minute from
0 to 350,000. When X1000 is shown, multiply the numeric reading by 1000 to get
the complete reading. When SI units are used, the display shows the current
radiation level in counts per second from 0 to 5000.
Total/ Timer. The display shows the accumulated total of counts starting when the
switch is turned to this position, from 0 to 9,999,000. When X1000 is shown,
multiply the numeric reading by 1000 to get the complete reading.
Timer Switch (10)
Off. The timer is not operating.
Set. You can now set the length of the timed period using the + and - buttons. If
the timer is already operating, the display shows the time remaining in the timed
period.
On. The timer is operating, and the display shows the total counts so far in the
timed period.
+ , - , and SET Buttons (8)
These buttons are used for setting the alert level and the timer. They are also used
for calibration and for using the Utility Menu. For more information, see "Taking a
Timed Count," Using the Alert, and The Utility Menu in Chapter 3 and
"Calibration" in Chapter 5.
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6
The Detector
CAUTION: The mica surface of the Geiger tube is fragile. Be careful not to let anything
penetrate the screen.
Internal For palmRAD 907 Only
The palmRAD 907 uses a two- inch round Geiger tube, commonly called a "pancake
tube." The screen on the back of the palmRAD 907 is called the window. It allows alpha
and low- energy beta and gamma radiation, which cannot get through the plastic case
and the stainless steel detector body, to penetrate the mica surface of the tube. The
small radiation symbols on the front label (5) and the end label (9) indicate the center of
the Geiger tube.
External For palmRAD 907 EXP Only
The palmRAD 907 EXPhas the pancake detector in an external probe instead of inside
the instrument. To connect the probe, plug one end of the cable into the connector on
the end of the palmRAD 907 EXPand the other end to the probe.
CAUTION: The connectors are directional. Be sure to line them up properly before
fitting them together. If the probe is not connected when you turn the palmRAD 907 EXP
on, the instrument will not function properly.
CAUTION: Do not remove the probe while the instrument is on.
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7
The Input/ Output Ports
There are two ports on the left side of the palmRAD 907. The palmRAD 907 has a third
port on the end panel.
The calibration input port (2) is used for calibrating electronically using a pulse
generator. For more information, see Calibrating Electronically in Chapter 5.
The output port (3) below the calibration input port allows you to interface the palmRAD
907 to a computer, data logger, or other device using a 3.5 mm stereo plug. For more
information, see Interfacing to an External Device in Chapter 3.
The probe port on the end panel of the palmRAD 907 EXPallows you to plug the
external probe into the instrument.
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3 Operation
The guidelines in this chapter describe how to use the palmRAD 907.
Units of Measurement
The palmRAD 907 is designed both for users of conventional units (milliroentgens per
hour and counts per minute) and for users of SI units (microsieverts per hour and
counts per second). To switch between conventional and SI units, use the Utility Menu.
See The Utility Menu in this chapter.
Starting the palmRAD 907
Be sure that a standard 9- volt alkaline battery is installed in the battery compartment in
the lower rear of the palmRAD 907. Note: When installing the battery, place the
battery wires along the side of the battery and not under it.
Before you start the palmRAD 907, make sure the timer switch on the end panel is set to
Off.
To start the palmRAD 907, set the top switch to the mode you want, and set the bottom
switch to On or Audio. The palmRAD 907 then does a four- second system check,
displaying all the indicators and numbers.
After the system check, the radiation level is displayed in the selected mode. Thirty
seconds after you start the palmRAD 907, a short beep indicates that enough
information has been collected to ensure statistical validity.
When using the palmRAD 907, always be sure there is no obstruction between the
detector window and the source you are surveying or monitoring.
Operating in the Dose Rate Modes
When the mode switch is set to mR/ hr Sv/ hr or CPM CPS, the numeric display is
updated every three seconds. At low count rates, significant changes in the radiation
level displayed can take up to 30 seconds to stabilize. See Operating Ranges and
Response Times in this chapter for more information.
CPM (or CPS) and total counts are the most direct methods of measurement; mR/ hr (or
Sv/ hr) is calculated using a conversion factor optimized for Cesium- 137, so this mode
is less accurate for other radionuclides, unless you have calibrated the palmRAD 907 for
a specific radionuclide using an appropriate source. It is more appropriate to measure
alpha and beta activity using CPM than using mR/ hr. Conversion for alpha and beta
emitters is calculated differently, and the palmRAD 907 s reading in mR/ hr may not be
accurate.
The most immediate indicators of the radiation level are the count light, the audio beep,
and the alert. It takes three seconds before an increase is shown on the numeric display
in the dose rate modes.
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Operating in Total/ Timer Mode
When the mode switch is set to Total/ Timer, the palmRAD 907 starts totaling the counts
it registers, and the numeric display is updated every second.
Taking a Timed Count
When a timed count is taken over a longer period, the average count per minute is more
accurate, and any small increase is more significant. For example, if one 10- minute
average is one count higher than another 10- minute average, the increase may be due
to normal variation. But over 12 hours, a one- count increase over the 12- hour
background average may be statistically significant.
The palmRAD 907 can give you a total count for a timed period of from one minute to
24 hours. Follow these steps:
1. With the palmRAD 907 operating, set the Mode switch to Total/ Timer. The display
shows TOTAL.
2. Set the Timer switch on the end panel to Set. The display shows SET, the hourglass,
and the most recent timing period used. The first time you use the timer, the
setting is 00:01, which means one minute.
3. Use the + and
buttons to set the timing period. The timed period can be for 1 to
10 minutes in one- minute increments, for 10 to 50 minutes in ten- minute
increments, or for 1 to 24 hours in one- hour increments.
4. Set the Timer switch to On. The palmRAD 907 beeps three times and starts
counting. The hourglass indicator flashes during the timed period.
If you want to see how many minutes remain, set the Timer switch to Set. The
display counts down from the time setting in hours and minutes to zero. For
example, if the display says 00:21, 21 minutes remain. Be sure to set the switch
back to On to see the total count when the timed period is finished.
5. At the end of the timed period, the palmRAD 907 beeps three times, and repeats
the beeping several times. The number displayed is the total count.
6. To find the average dose rate for the timed period in counts per minute, divide the
total by the number of minutes.
7. Set the Timer switch to Off to return to normal operation.
As long as the Timer switch is set to On, the timer mode is active in the background
even when the Mode switch is set to one of the dose rate modes. For example, during
and after the timed period, you can switch back and forth between Total/ Timer and
mR/ hr; when the timed period is over, the total is displayed whenever you switch back
to Total/ Timer. The hourglass indicator is shown on the display in any mode setting; it
is blinking while the timer is totaling counts.
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Taking a Total Count
The timer can take timed counts of up to twenty- four hours. In certain situations, you
may want to take a total count without the timer; for example, taking a count for longer
than twenty- four hours. Follow these steps:
1. Place the palmRAD 907 in the location where you plan to take the count.
2. Note the time.
3. Immediately when you note the time, set the mode switch to Total/ Timer.
4. At the end of the time period, note the time and the total on the numeric display.
5. Subtract the starting time from the ending time to determine the exact number of
minutes in the timing period.
6. To get the average count, divide the total reading by the number of minutes in the
timing period.
Operating Ranges and Response Times
In some modes, when radiation levels increase over certain preset levels, the palmRAD
907 uses autoranging, automatically changing to the X1000 scale. Whenever X1000 is
shown above the numeric display, multiply the displayed reading by 1000 to determine
the radiation level. The following table shows the radiation levels the palmRAD 907
measures in each mode and how they are displayed.
Mode Regular Range X1000 Range
mR/ hr .001- 110 NA
Sv/ hr .01- 1100 NA
CPM 0- 9999 10,000- 350,000
(displayed as 10.00- 350,
with X1000 indicator)
CPS 0- 5000 NA
Total/ Timer 0- 9999 10,000- 9,999,000
(displayed as 10.00- 9999,
with X1000 indicator)
Maximum level. When the maximum level for the current mode is reached, the
palmRAD 907 beeps for three seconds, pauses for three seconds, and repeats that
pattern. The numeric display flashes. The beeping pattern and the flashing continue
until the level decreases or the palmRAD 907 is turned off.
Display update and response time. In Total/ Timer mode, the numeric display is updated
each second. In the dose rate modes, the numeric display is updated every three
seconds. When the radiation level is less than 6,000 CPM, the reading in any of the dose
rate modes is based on the radiation detected in the immediately previous 30 seconds.
In order to give a quicker response to changes, when the radiation level exceeds 6,000
CPM in any 30- second period, the reading is based on the previous 6 seconds, and
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when it exceeds 12,000 CPM, the reading is based on the previous 3 seconds, as shown
in the following table. This automatic change in response time is called auto averaging.
Radiation level Basis for reading
(after first 30 seconds)
< 6000 CPM or < 1.75 mR/ hr 30 seconds
(< 100 CPS)
6000- 12000 CPM or 1.75- 3.6 mR/ hr 6 seconds
(100- 200- CPS)
> 12000 CPM or > 3.6 mR/ hr 3 seconds
(> 200 CPS)
Note: You can set the response time to 3 seconds at all radiation levels using the Utility
Menu; see The Utility Menu in this chapter.
Using the Alert
The palmRAD 907 can sound an audible alert whenever the radiation reading reaches a
certain level. The + , - , and Set buttons on the end of the palmRAD 907 allow you to
turn Alert mode on and off and to set the alert levels.
To use Alert mode, follow these steps:
1. Press the Set button on the end panel. The current alert level is displayed. It is in
CPM, CPS, mR/ hr, or Sv/ hr, depending on the palmRAD 907 s current settings.
The radiation symbol and SET icon are displayed.
2. If you want to change the displayed alert level, use the + and
buttons to adjust
the level up or down.
3. When the desired alert level is displayed, press the Set button again to save the new
level and continue in Alert mode.
The radiation symbol is displayed to show that the palmRAD 907 is in Alert mode.
4. If you want to reset the alert level while you are in Alert mode, press the Set button
twice (Off, then Set).
5. To turn off Alert mode, press the Set button once.
When you start Alert mode, the palmRAD 907 restarts counting, and beeps after 30
seconds to show that the reading is statistically valid.
When you first start the palmRAD 907, the alert levels are preset at .10 mR/ hr, and the
equivalent in CPM, Sv, and CPS. If you set the alert level in one mode, the settings for
the other modes are automatically updated to the equivalent values.
The best alert level is one that rarely gives a false alarm, yet warns you when the
radiation is higher than normal.
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The Utility Menu
The Utility Menu allows you to change the default settings for several operating
parameters. When you change a setting, it remains in effect after you turn off the
palmRAD 907 and until you change it again.
To activate the Utility Menu, hold down the + button on the end panel while you turn on
the palmRAD 907. The word MENU appears at the bottom right of the numeric display,
and the display shows 1 for menu option 1. To scroll through the menu, push the plus
(+ ) and minus ( ) buttons. To select an option, push the Set button. Once an option is
selected, use the + and
buttons to scroll among settings. After you choose the setting
you want, select option 0 to exit the Utility Menu.
The options are:
0 Resume normal operation.
1 Auto Averaging. on (the default) selects Auto averaging; oFF selects 3- second (fast
response) averaging at all radiation levels.
2 Units of measurement. CPM mR/ hr selects counts per minute and milliroentgens
per hour; CPS Sv/ hr selects counts per second and microseiverts per hour.
3 Cal 100 Reset. Selecting this option automatically resets the calibration factor to
100 and restarts the instrument.
4, 5, 6 Reserved for future options.
7 Cal Factor Adjust. Displays the current calibration factor, which you then adjust to
the new factor you want. See Calibration in Chapter 5.
8 Factory Default Reset. Selecting this option automatically resets the items 1, 2, and
3 to Auto averaging, CPM and mR/ hr, and 100, and restarts the instrument
9 Revision #. Displays the software version number.
Interfacing to an External Device
The lower output jack on the left side of the palmRAD 907 is a dual miniature jack that
provides a data output that can be used to drive a CMOSor TTL device. You can use it to
record the counts on a computer, data logger, or accumulating counter. Use a 3.5 mm
stereo plug to access this port. The output at the tip of the plug provides a positive (3.3
volt) pulse each time the Geiger tube detects a count. A cable with an RS- 232 connector
for an IBM PC- compatible computer serial port and accompanying software are available
from Berkeley Nucleonics Corporation.
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4 Common Procedures
The following sections give instructions for several commonly- used procedures. With
any procedure, the user must determine the suitability of the instrument or procedure
for that application.
Establishing the Background Count
Normal background radiation levels vary at different locations, even in different areas of
the same room. To accurately interpret the readings you get on the palmRAD 907, it is
a good idea to establish the normal background radiation level for each area you plan to
monitor. You can do this with a timed count. Use the following steps to get a ten-
minute average.
1. With the palmRAD 907 operating, set the Mode switch to Total/ Timer.
2. Set the Timer switch on the end panel to Set. Unless you have previously changed
it, the display reads 00:01, which means one minute.
3. Press the + button nine times. The display should read 00:10, for ten minutes.
4. Set the Timer switch to On. The palmRAD 907 beeps three times and starts
counting.
If you want to see how much of the ten minutes remains, set the Timer switch to
Set. The display counts down from ten minutes to zero. For example, if the display
says 00:03, seven minutes have passed and three minutes remain. Reset the switch
to On to return to the radiation level display.
5. At the end of the ten minutes, the palmRAD 907 beeps three times, and repeats the
beeping several times. Note the total reading.
6. To find the average counts per minute, divide the total by ten (the number of
minutes).
A ten- minute average is moderately accurate. You can repeat it several times and see
how close the averages are. To establish a more accurate average, take a one- hour
timed count. If you need to determine whether there is prior contamination, take
averages in several locations and compare the averages.
For more information on using the timer, see "Taking a Timed Count" in Chapter 3.
Environmental Area Monitoring
You can keep the palmRAD 907 in CPM or mR/ hr mode whenever you want to monitor
the ambient radiation, and look at it from time to time to check for elevated readings.
You can also use Alert mode to warn you if the radiation increases above the alert level.
If you suspect an increase in ambient radiation, use the timer to take a five or ten
minute count, and compare the average to your average background count. If you
suspect an increase that is too small to detect with a short timed reading, you can take
a longer count (for example 6, 12, or 24 hours).
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Checking for Surface Contamination
To check a surface, hold the palmRAD 907 with the alpha window facing and close to
the surface. If you want to find out if a surface is slightly radioactive, place the
palmRAD 907 next to it and take a timed count or a longer accumulated count.
CAUTION: Never touch the palmRAD 907 to a surface that may be contaminated. You
may contaminate the instrument. The rubber strips on the back can be replaced if they
become contaminated. Replacement strips are supplied with the palmRAD 907.
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5 Maintenance
The palmRAD 907 should be handled with care and can be calibrated as necessary to
comply with regulations. Use the following guidelines to maintain the palmRAD 907
properly.
Calibration
The palmRAD 907 should be calibrated as often as your regulations require. The best
way to calibrate is using a calibrated source. If no source is available, it is possible to
calibrate electronically using a pulse generator.
The standard radionuclide for calibration is Cesium- 137. A certified calibration source
should be used. To calibrate the palmRAD 907 for another radionuclide, you must use a
calibrated source for that radionuclide or the appropriate conversion factor referenced
to Cs- 137.
CAUTION: In calibration mode, the smallest increment that can be adjusted is .010,
which prevents fine adjustment of the calibration factor. Thus, errors can occur if you
use a low- level source or background to set the calibration factor.
Calibrating Using a Source
Before you calibrate the palmRAD 907, make sure the distance between the palmRAD
907 and the source is correct to produce the appropriate dose rate. Follow these steps:
1. Start with the palmRAD 907 turned off and the Mode switch set to mR/ hr Sv/ hr.
2. Hold down the
button on the end panel while you turn the On/ Off/ Audio switch to
On. (Don t use the Audio setting.)
The display shows CAL, and the palmRAD 907 counts down for 15 seconds,
beeping each second. This delay gives you a chance to move out of the field and
then expose the source. At the end of the 15 seconds, the palmRAD 907 beeps
several times.
3. The palmRAD 907 collects data for 30 seconds, beeping as it does so, with CAL and
the hourglass indicator flashing. At the end of the 30 seconds, it beeps several
times. The display shows CAL and SET. You can now seal or close the source.
4. Press the + and - buttons to adjust the reading to what it should be. When the
reading is correct, press the Set button. The new calibration factor is automatically
calculated from the adjustment you make.
5. The new calibration factor is displayed for several seconds, then the palmRAD 907
beeps and resumes regular operation.
The calibration factor is set to 100 (percent) at the factory. If you change the reading,
for example, to 20%higher than the factory reading, the new calibration factor would be
120. The current calibration factor is displayed during the system check when the
palmRAD 907 is first turned on.
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Calibrating Electronically
You can calibrate electronically using a pulse or function generator. Electronic
calibration requires a cable with a 2.5 mm plug, with the tip carrying the signal. Follow
these steps:
1. Set the signal height to 3.3 volts (positive pulse) and the pulse width to 80
microseconds.
CAUTION: Do not inject a pulse when the palmRAD 907 is turned off. Do not
exceed 5 volts.
2. Plug the cable into the upper jack.
3. Start with the palmRAD 907 turned off and the Mode switch set to mR/ hr Sv/ hr.
Hold down the
button on the end panel while you turn the On/ Off/ Audio switch to
On. (Don t use the Audio setting.)
The display shows CAL, and the palmRAD 907 counts down for 15 seconds,
chirping each second. At the end of the 15 seconds, the palmRAD 907 beeps
several times.
4. The palmRAD 907 collects data for 30 seconds, beeping as it does so, with CAL and
the hourglass indicator flashing. At the end of the 30 seconds, it beeps several
times. The display shows CAL and SET.
5. Use the following table to check the palmRAD 907 s accuracy. The table shows
appropriate pulse generator count rates to calibrate for Cs137. If the accuracy is
not within desired limits, follow steps 5- 7. Note that the palmRAD 907
automatically compensates for lost counts due to GM tube dead time. Thus, the
display reading in CPM mode does not equal the input frequency. You can display
uncompensated counts in CPM mode by continuously holding down the
(minus)
button; the reading now corresponds to the input frequency.
Pulse
Generator
Input (PPM)
CPM
mR/ hr
Sv/ hr
CPS
31,423
33,400
10
100
557
59,335
66,800
20
200
1,113
127,043
166,999
50
500
2,783
177,752
267,200
80
800
4,453
205,031
334,031
100
1,000
5,567
6. Press the + and - buttons to adjust the reading to what it should be. When the
reading is correct, press the Set button. The new calibration factor is automatically
calculated from the adjustment you make.
7. The new calibration factor is displayed for several seconds, then the palmRAD 907
beeps and resumes regular operation.