User manual

in microroentgen per hour, standardized to gamma rays from
cesium 137 +- 5%. Cesium 137 has an average gamma ray
energy level of 661 KEV (661,000 electron volts).
From 8 KEV up to 166 KEV, the RM-60 has a sensitivity to
X-rays as much as or more than the sensitivity to cesium 137
gamma rays, therefore, from 8 KEV to 166 KEV, the RM-60
will always provide you with, at least, the minimum micro-
roentgen per hour level.
At 8000 electron volts, the sensitivity is the same as the sensi-
tivity to cesium 137. The X-Ray sensitivity of the RM-60
increases from approximately 8 KEV to 60 KEV in relation
to cesium 137 sensitivity. From 60 KEV on up, the sensitivi-
ty drops back down to cesium 137 sensitivity. If you discov-
er any TV or computer monitor which generates a significate
increase in reading (very unlikely with anything but old tube
TVs), please phone us. Although it is always prudent to error
on the safe side, you may want to derate the reading observed
due to the increase in RM-60 sensitivity centered at 60 KEV.
This involves measuring the TV’s power supply voltage level,
multiplying by 0.666 then applying a correction factor. If you
have any questions or comments, please don’t hesitate to write
or phone us.
TIME BASE UNIT
A Time Base Unit (TBU) option from the Setup menu allows
the selection of a TBU of either 10 sec. or 60 sec. With a 10
sec. TBU, Aw-srad and the TSR program will display and
save data every 10 sec. Likewise, with a 60 sec. TBU, the
programs will display and save data every 60 sec. The data
saved is the average radiation level for a TBU period (10 sec.
or 60 sec.). Each of the two TBU modes of operation uses a
unique calibration factor (see below) so that the raw data
saved (either every 10 sec. or 60 sec) is displayed in micro-
roentgen/hr. The program will automatically choose the cor-
rect calibration factor for you. When loading a previously
gathered raw data file for viewing, the program automatically
detects the TBU used when the file was generated, and sets
the calibration accordingly. You should only use the 10
second TBU mode for plotting higher levels of radiation
because the files generated are six times larger. Also, 10
second averages at lower levels of radiation will swing over
a large range.
CALIBRATION FACTOR
As stated in the brochure, the RM-60’s tube is calibrated to
cesium 137, +/- 5%. Aw-srad includes a calibration factor
option from the program’s Setup menu for both the 10 second
Time Base Unit mode and the 60 second Time Base Unit
mode. The software stores data in the form of counts per unit
time (10 secs. or 60 secs.). When applying the calibration
factor for display, to avoid floating point arithmetic, the
program multiplies the count by 100 then divides by the
factor. The factor allows calibration to other sources, for
critical scientific work. To calibrate readings to a known
radioactive source:
Step 1: Gather raw radiation data to a disk file while sub-
jecting the RM-60 to a known ionizing flux level from the
source for 10 minutes to an hour or longer.
Step 2: Next display the file’s summary from the Display
menu. Observe summary’s "Average MicroR/hr" value.
Step 3: If the average doesn’t precisely match the calibrated
source flux level, select "Change settings" from the Display
menu, then select "Factor RAD calibration", and adjust the
factor accordingly.
Step 4: Next hit escape to return to the Display menu and
choose "Display Summary" again to observe the new "Aver-
age Micro/hr".
If need be, repeat Step 3.
Calibration factors can be saved to disk by activating the
"Disk Write Settings" selection from the Setup or Misc. menu.
The calibration factors have no effect on the gathering of the
raw radiation data. The factors are only utilized when the
program interprets the raw data while displaying to the screen
or DOS device.
CRITICAL APPLICATIONS - PROBLEMS
If you expect very high radiation levels (0.1 to 10 R per hr.)
add an external power supply as per the diagram at the end of
the manual. (See README, "EDIT README.TXT"). Also,
for very critical applications, perhaps it is best not to load
other TSR programs into computer memory, besides programs
from Aware. Since none of the Aware programs use extend-
ed-expanded memory, you can also remove all lines from the
config.sys file that load extended-expanded memory manag-
ers, many of which will switch the computer into virtual
mode. (You could make a BOOT floppy). The standard 640K
DOS memory is plenty to run all Aware programs, load DOS,
and most standard DOS programs. We mention this because
on rare occasion we noticed some complicated memory
managers (i.e. QEMM with "Stealth", etc.) can, after running
certain combinations of complicated programs (not Aware
programs), switch into a mode that interferes slightly with the
timer routines used in the Aware programs.
For very critical monitoring, perhaps an autonomous computer
($300 to $400) is advisable. Any AT should be more than
sufficient. Also, to allow maximum CPU freedom, reduce the
beep length to one or turn the beep off.
Running a disk compression program on a slow computer can
cause problems with a small "Write Buffer Cycle" (see RE-
ADME file "EDIT README.TXT").
RM-60 TREATMENT
In general treat your RM-60 no worse than you would treat a
portable computer. Do not place your RM-60 in water or
leave it in the rain. Do not place your RM-60 in a micro-
wave oven. The case is made of ABS which is very shock
resistance but somewhat soft. To avoid scratches when
transporting, keep unit in the heavy walled plastic bag. Wipe
clean with a soft cloth moistened with water or rubbing
alcohol. Avoid all other solvents.
If you plan to mount your RM-60 outside, you must prevent
14