RAM 100 Operating Manual - Rotem Radiation · RAM 100 / Operating Manual Page 4 1. The RAM 100 1.1. General Description The RAM 100 radiation contamination meter is a state-of-the-art

RAM 100

Surface Contamination Meter

Operating Manual

DPM / CPM

Version 3.0 - November 2000

Document # PRIR75R0.DOC

R TEM INDUSTRIES LTD. ROTEM Industrial Park, 5000 Highlands Parkway,

P.O.Box 9046, Beer-Sheva 84190, ISRAEL Suite 150 Smyrna, Georgia 30082, USA

Tel: 972-8-6571312/6568652 Tel: (770) 432-2744,

Fax: 972-8-6555984/6568005 Fax: (770) 432-9179

E-Mail: [email protected]

Web Site: http://www.rotemi.co.il

RAM 100 / Operating Manual Page 2

Version / Revision Log: RAM 100 / Operating Manual

Ver./Rev.# Date Revised Pages Comments

2ed

edition July 1993 DPM version, Doc. # BM9304.WP

CPM version, Doc. # BM9307.WP

3.0 November 2000 1-3 Doc. # PRIR75R0.DOC

DPM + CPM updated WORD version

Updated ROTEM address, table of contents,

addition of this log, letter size pages

13 Err. value corrected

WARNING:

For air delivery, the detector should be placed in a sealed container to ensure gradual changes

in pressure, which otherwise may cause irreparable damage to the GM tube.

ROTEM Industries Ltd. reserves the right to change specifications without advance notice.

Ref. PRIR75R0.DOC


Table of Contents

1. The RAM 100 ............................................................................................................................... 4

1.1. General Description.................................................................................................................. 4

1.2. Ordering Information................................................................................................................ 5

2. Specifications................................................................................................................................ 6

3. Operating Instructions ................................................................................................................ 8

3.1. Preparation for Use................................................................................................................... 8

3.2. Starting-up ................................................................................................................................ 8

3.3. General Functions..................................................................................................................... 8

3.4. Special Functions...................................................................................................................... 8

3.5. Alarms .................................................................................................................................... 11

3.6. Push-buttons Function ............................................................................................................ 12

3.7. Battery Replacement............................................................................................................... 12

4. Calibration ................................................................................................................................. 13

4.1. General Description................................................................................................................ 13

4.2. Calibration Procedure............................................................................................................. 13

4.3. Base Unit Fixed “Calibration”................................................................................................ 14

4.4. Pulser Adapter – Model A-0270............................................................................................. 15


1. The RAM 100

1.1. General Description

The RAM 100 radiation contamination meter is a state-of-the-art microprocessor-based

instrument, designed to detect very low levels of alpha, beta and gamma surface radiation

contamination. Two versions are available: RAM 100 DPM and RAM 100 CPM.

RAM 100 DPM version reads directly in disintegration units. The user should select the

efficiency factor. This value can be selected from the following values: 8, 9, 10, 11, 12,

13, 14, 15, 16, 17, 18 and 100 (%). When 100 (%) is selected the RAM 100 actually

displays the cpm value. After the efficiency factor is selected, the RAM 100 can be

calibrated to give the exact dpm reading that fits to a specific isotope.

The dpm calculation is:

cpm x 100

EFF.

When: EFF. = Efficiency factor

In RAM 100 CPM version, the efficiency factor value equals 100 and it cannot be

changed by the user.

The RAM 100 meter is built of two parts:

a. detector, amplifier and HV assembly.

b. base unit including rate-meter and display.

The RAM 100 detached detector is a GM

pancake tube of 1.75" effective diameter,

with a thin mica window covered by a

protective copper beryllium screen. The

detachable detector offers extra flexibility

for getting at underneath surfaces and

hard-to-reach places.

The meter is a one-hand-operation

instrument, portable, lightweight and

compact. Only three push-buttons are

needed for operation: ON/OFF, RESET/

MODE and SPEAKER/→→→→.

Three ways of indications enable the RAM 100 user to monitor and survey surface

contamination rapidly and accurately: a large four 7-segment LCD, an audible click

whose rate varies directly with count rate, and a LED indicator RESPONSE that flashes

with each incident radiation pulse.


The sophisticated software offers special features and optimal performance. A wide

dynamic range of up to 999,000 disintegration per minute, is obtained by the automatic

dead time correction, according to the preset calibration. A special averaging function

“smoothes” the readout and maintains fast response time, while keeping the standard

deviation at a minimum.

An automatic self-diagnostic procedure continuously checks both counter and detector,

and reports any case of detector failure. The meter also alarms in any case of reading

exceeding threshold value, reading overflow or low battery. Threshold can be selected

from a range of 9 preset threshold values. When the meter is turned off, the last threshold

value is kept in memory.

The RAM 100 meter can be placed in a holder. The detector surface is covered with a cap

for protection against mechanical damage.

1.2. Ordering Information

Item description Model No.

RAM 100 (incl. counter, detector, holder, cover cap, tel. connector) <dpm> RTM 9025

RAM 100 (same as RTM 9025 with threaded head) <dpm> RTM 9022

RAM 100 (incl. counter, detector, holder, cover cap, tel. connector) <cpm> RTM 9009

RAM 100 (same as RTM 9009 with threaded head) <cpm> RTM9024

RAM 100 detector (GM-10) with telephone connector 3-0020-01

RAM 100 detector (GM-10) with threaded head 3-0020-05

RAM 100 detector (GM-10) threaded head with telephone connector 3-0020-06

RAM 100 holder A-0110

Detector tester A-0070

Telephone cable A-0120

Belt hanger A-0130

Pancake hexagonal protective screen A-0141

Pulser adapter A-0270


2. Specifications

Display LCD readout showing:

- four digits for accurate and easy readout

- detector failure

- low battery

- overflow

- threshold

LED Count rate indication

Audio Internally mounted piezo-electric element

Measuring unit dpm - disintegration per minute

cpm - counts per minute

Controls - ON/OFF push-button

- RESET/MODE push-button for accurate measurement of

low level contamination and mode selection

- SPEAKER/→→→→ push-button to control audible indicator

volume and threshold and efficiency values

Power source One 9-Volt cell battery

- 50 hours minimum continuous operation, using an alkaline

battery (speaker off)

- Automatic battery check under full load

Detector Pancake GM tube (LND 73118 or equivalent)

Effective diameter 1.75”

Window thickness Mica, 1.5 to 2 mg/cm² protected by a copper beryllium screen

Background reading Approx. 500 dpm when 10% efficiency factor is selected

Sensitivity (137

Cs) Approx. 35000 dpm/mR/h when 10% efficiency factor is

selected

Count rate range 0 to 999,000 dpm

Accuracy ±15% of reading

Temperature range Operation: -10°C to +50°C (15°F to 122°F)

Storage: -20°C to + 60°C (-5°F to 140°F)

Humidity range 40% to 95% RH (non condensing)


Casing High impact plastic

Dimensions Counter Detector

Width: 6.7 cm (2.6") 7.1 cm (2.8")

Length: 11.0 cm (4.3") 27.0 cm (10.6")

Height: 4.6 cm (1.8") 8.9 cm (3.5")

Weight 780 g (1.7 lb)

Surface sensitivity (in contact), when efficiency value = 10%, using a hexagonal

cooper beryllium screen

Minimum

Detectable Level*

Isotope Energy

E or Emax

keV

Sensitivity

Kdpm/µµµµCi

Surface Sensitivity

__dpm__ __dpm__

pCi/cm² Bq/cm² pCi/cm² Bq/cm²

14C (β) 156 900 13 350 500 20 147

Pm (β) 224 4300 67 1800 108 3.8 99

Tc (β) 290 5150 76 2060 91 3.4 90

Sr+90

Y(β) 580+2280 14400 217 5880 16 0.6 36

Cl (β) 714 6850 98 2640 79 2.7 210

Pb (β) 1160 7950 120 3240 64 2.1

MDL - Minimum Detectable Level calculations are based on background reading of 500

dpm, and the confidence level is 99%.

Surface sensitivity (in contact) in cpm units when using a hexagonal cooper beryllium

screen

Minimum

Detectable Level*

Isotope Energy

E or Emax

keV

Sensitivity

Kcpm/µµµµCi

Surface Sensitivity

__cpm__ __cpm__

pCi/cm² Bq/cm² pCi/cm² Bq/cm²

14C (β) 156 93 1.3 34.8 50 2

147Pm (β) 224 432 6.7 180 10.8 0.38

99Tc (β) 290 516 7.6 206.4 9.1 0.34 90

Sr+90

Y(β) 580+2280 1446 21.7 588 1.57 0.06 36Cl (β) 714 686 9.8 264 7.9 0.27 210

Pb (β) 1160 796 12 324 6.42 0.21

* Minimum Detectable Level calculations are based on background reading of 50 cpm, and

the confidence level is 99%.


3. Operating Instructions

3.1. Preparation for Use

Remove the instrument from the shipping container and check for physical damage.

In case of damage, report it immediately to the carrier.

Do not attempt to install or operate damaged equipment since safety and performance

may be affected

3.2. Starting-up

Press the ON/OFF push-button. When the meter is turned on, it carries out a short self-

test procedure and the following sequence is displayed:

- all the segments + a short beep

- thr. LCDs

- last threshold value

- EFF. LCDs (only in DPM version)

- last efficiency value (only in DPM version)

After this sequence the actual reading is displayed and the meter is ready for use.

3.3. General Functions

a. Readout: The measuring units are disintegration per minute. Values through 9999

dpm are expressed in 1 to 4 digits. For higher values, up to 999,000 dpm, a factor of

1000 will be indicated by displaying E.

For example: 10,400 = 10.4E

127,000 = 127E

b. LED: The LED indicator RESPONSE located above the LCD, blinks with each

incident radiation pulse.

c. Reading reset: To reset the reading press the RESET push-button. The reset function

provides a rapid means of discharging the display reading and enables accurate

measurement of low level contamination.

d. Audible indication: When the meter is turned on, the audible indication is activated

at its high volume, so that the rate and trend of measurement are noticed. To decrease

speaker volume, press SPEAKER push-button once, to turn it off press once again. This

volume control effect is specially activated at low rates of measurement.

3.4. Special Functions

Definitions:

Short press - RESET push-button, press and release it before 2 seconds are elapsed.

Long press – MODE push-button, press and hold at least for 2 seconds.


Special Functions enable to carry out threshold setting, efficiency factor (dpm version) and

calibration (through a sequential procedure).

RAM 100 DPM Special Functions Block Diagram

RAM 100 CPM Special Functions Block Diagram


3.4.1. Threshold setting

The first press on the MODE push-button activates special functions. The thr. LCDs will

be displayed.

Advance to the chosen value by pressing the SPEAKER/→→→→ push-button. The following

threshold values may be selected:

2000, 2500, 3000, 3500, 4000, 10.0E, 50.0E, 100E, 200E, 999E.

Pressing the RESET push-button activates the calibration mode.

Pressing the MODE push-button returns to normal operation.

3.4.2. Efficiency factor setting – only in DPM version

When entering the efficiency factor setting, the EFF. LCDs will be displayed.

Advance to the chosen efficiency value by pressing the SPEAKER/→→→→ push-button.

The following efficiency values may be selected:

8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, and 100%.

Pressing the RESET push-button activates the efficiency factor.

Pressing the MODE push-button returns to normal operation.

3.4.3. Calibration mode (see chapter 4)

The CAL. LCDs will be displayed.

Press the SPEAKER/→→→→ push-button to perform the calibration procedure, according to

section 4.2. The actual reading will blink on the display. Press the RESET/MODE push-

button to go into normal operation.

Note: When the thr., EFF. or CAL. LCDs are displayed you don't have to enter these

modes, just press the MODE push-button instead of the SPEAKER/→→→→ push-button to

advance to the next function. To exit special functions mode, either complete the

sequence or press the RESET push-button. The selected values of the alarm threshold

and the efficiency factor are stored in a non-volatile memory, and are also retained after

the instrument is turned off.

The first value to be displayed when entering a special function is the last selected

value.


3.5. Alarms

a. Detector alarm: If the detector is defective or disconnected, the Err. LCDs blink on

the display

b. Battery alarm: If battery voltage decreases below 6.2V, the bAt. LCDs blink on the

display, and an interrupted audible alarm is activated.

To display the measured readings and mute the audible alarm, press the SPEAKER/→→→→

push-button. After the SPEAKER push-button is pressed, the bAt. LCDs will reappear

every 5 minutes for 2 seconds, and every 30 minutes accompanied by an audible beep to

remind of low battery condition.

c. Overflow alarm: If the displayed count rate is over 999E (999,000 dpm), the OFLO

LCDs blink on the display.

d. Threshold alarm: If the reading exceeds threshold value, the ALr. LCDs and the

reading are displayed alternately, accompanied by an audible beep.

Pressing the SPEAKER/→→→→ push-button mutes the audible alarm, but the ALr. LCDs and

the reading are continuing to be displayed alternately, until the reading decreases to 0.75

from threshold value.

In case the reading exceeds threshold value and then decreases below 0.75 of threshold

value, the ALr. LCDs and the beep sound are automatically cancelled, even though the

SPEAKER/→→→→ push-button has not been pressed.


3.6. Push-buttons Function

Push-button Pressing Mode Function

ON / OFF meter on / off

RESET momentary reading reset

SPEAKER speaker volume modification

MODE long press enter /exit special mode

RESET short press step to next mode (in special

functions)

(exit special functions mode after the

sequence is completed)

SPEAKER/→→→→ Change alarm and/or efficiency value

Enter into calibration mode

(when CAL. LCDs are displayed)

3.7. Battery Replacement

The battery compartment is located at the back of the instrument. To replace the battery,

slide out the battery compartment cover carefully. Use one 9-Volt alkaline battery; ensure

to connect it with the right polarity.

Figure 3-1. RAM 100 Battery Compartment

External Power Supply

The RAM 100 is equipped with external DC input. It can be operated either with a 9V

battery or an external 9V DC power supply. The battery can be used in conjunction with the

external power supply. In case of external power failure the battery supplies the current. The

DC voltage should be 10 to 12 Volts, to avoid drain current from the battery.


4. Calibration

4.1. General Description

The RAM 100 is built of two parts:

a. detector, amplifier and HV assembly.

b. base unit including rate-meter and display.

The amplifier assembly receives 5 Volts from the base unit, to generate high voltage for

the GM pancake tube. The GM pancake tube pulses are amplified in the amplifier

assembly, and sent to the base unit for processing and displaying.

A calibration factor circuitry is built into the amplifier assembly. The calibration factor

adjustment is used to compensate for the GM pancake tube efficiency changes. This

factor usually changes to less than 15% on GM pancake tube replacement, so it can be

ignored when replacement is performed in the field. Nevertheless, when the unit is back

in the lab it should be rechecked and re-calibrated. The replaced GM tube has to be

calibrated (see section 4.2). When the meter is turned ON, the calibration factor value

should be between the ranges of 0.60 to 1.40. In case the factor value deviates from these

ranges, the Err. LCDs blink on the display.

4.2. Calibration Procedure

Note: Calibration should be performed by an authorized technician.

Necessary equipment:

- DVM, adequate HV probe (1:1000)

- Calibration jig or reference source such as 90

Sr/90

Y, 137

Cs, 99

Tc or mix 60

Co/137

Cs

-. DRW #10723-2, PC #1541

a) Open the detector housing by untightening the 3 Philips screws.

b) Connect the detector to the meter.

c) Connect the HV probe to the D1 cathode, see figure 4-2.

d) Turn the meter on. Caution! High Voltage on circuit.

e) Turn R14 to obtain 875 ±5V, see figure 4-2.

f) Place the detector on the calibration jig in its right position, or use a known calibrated

source.

g) Enter calibration mode, see section 3.4 Special Functions. A blinking display

indicates calibration mode.

h) Turn R12 (factor adj.) gradually to obtain on the meter an identical average reading

to that indicated on the jig. The source has to placed against the detector, and the

calibration potentiometer in the detector should be adjusted to obtain the expected

result.

i) Turn the meter off.

j) Put the detector back into its housing. Tighten the 3 Philips screws. The detector is

calibrated and ready for operation.


Figure 4-1. The Amplifier Assembly Electronic Board

HV Measure R14 HV Adjust R12 Factor Adjust

Figure 4-2. The Amplifier Assembly Component Location

4.3. Base Unit Fixed “Calibration”

The base unit counts the input pulses, calculates dead time, averages results and displays

the reading. To check the base unit "calibration" perform the following procedure:

a. Disconnect the detector from the base unit.

b. Adjust the pulser output to obtain a 5 Volts amplitude and 10 µsec width pulse., or use

a standard mini pulser with the pulser adapter.

c. Connect the pulser output to the pulser adapter via a BNC to BNC cable.

Connect the pulser adapter to the base unit via a telephone cable.

d. First turn the meter on, and then turn the pulser on. Set the base unit efficiency to 100.

Obtain the base unit reading (±10%) according to the following Table 1:


Input Frequency

<Hz>

Display (±10%)

<cpm>

50 3000

100 6000

500 30.0E

2764 172E

3176 207E

3960 274E

5063 378E

7650 692E

10692 OFLO

Table 1

4.4. Pulser Adapter – Model A-0270

The pulser adapter converts the "mini pulser" pulses into standard TTL level pulses.

The adapter can be used either with positive or negative pulses. Positive pulses amplitude

should be higher than 0.6 Volts. Negative pulses amplitude should be higher than

1.7 Volts.

The mini pulser can be connected in parallel, either to BNC or MHV input connectors.

The pulser adapter output is connected to the meter’s input.

Figure 4-3. Pulser Adapter Connection Diagram

RAM SURF

Telephone cable

Pulser adapter Pulser

Model A-0270


RAM 100 / Operating Manual

Notes:

Documents

RAM 100 Operating Manual - Rotem Radiation · RAM 100 / Operating Manual Page 4 1. The RAM 100 1.1. General Description The RAM 100 radiation contamination meter is a state-of-the-art