Introduction; Assembly And Installation; Start-Up; Operating Controls - Velp Scientifica SE Manuel D'instructions

1. Introduction

The meter senses the four main types of ionizing radiation: alpha, beta, gamma, X-rays.
Calibrated by Cesium 137, is suitable to reveale also other sources of ionizing radiations. Shows maximum accuracy when
measuring Cesium 137 and isotopes of similar energies; some isotopes which can be revealed are Cobalt 60, Phosphorus
32, Strontium 90, and different forms of Radium, Plutonium, Uranium and Thorium.
Gamma and X radiations are measured in milli-Roentgens/hour (mR/hr), micro-Sieverts (µSv/hr) o milli-Sieverts (mSv/hr).
Alpha and Beta are measured in counts/minute (CPM) or counts/second (CPS).
The revelation of ionizing radiations is performed by means of a Geiger-Mueller tube having a thin mica window equipped
with a screen. Some levels of alfa or beta, gamma and X rays, having a low energy, which cannot penetrate the plastic
covering of the instrument or the GM tube walls, can be revealed through the window.
The GM tube is placed inside the instrument.
ON-OFF AUDIO SWITCH
When a ray or particle of ionizing radiation enters the GM tube or passes through it, it is electronically revealed and
visualized by means of a red count light.
If the switch is in AUDIO position, the instrument emits also an acoustic signal every time a radioactive event occurs.
5-25 counts/minute about ,with random intervals, in relation to position and altitude, are due to natural background radiation.

2. Assembly and installation

Check the integrity of the unit after unpacking. The box includes:
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SE Radiation detector

2.1 Start-up

Before turning on the instrument, install a 9 V alkaline battery. If a battery is already installed, turn the instrument on and
switch the range switch to the BATT position: battery condition will be indicated on the meter. If you don't think that high
levels of radiation are present, set the range switch in the X1 position. If the meter goes off scale, move the range switch to
the next higher setting, X10 or X100. For an audible signal , position the OFF/ON/ AUDIO switch to the AUDIO position.
NOTE: The flashes from the count light and the audible beeps are progressively shorter in X10, X100 positions. At the end
of the work cycle set the stirring speed knob on "0" rpm, the timer knob on "OFF" and turn off the light of central column. If
the instrument is not used for a long period it's better to disconnect the external power supply from the plug.

3. Operating controls

To determine whether the radiation detected is alpha, beta or gamma, move the top of the instrument toward the source.
Gamma: if there is an indication of radioactivity, it is most likely gamma or high energy beta.
Low energy gamma and x-rays (10-40 KeV) cannot penetrate the sidewall of the GM tube, but
may be detected through the window.
Beta: place a piece of aluminum about 1/8" (3mm) thick between the instrument and the source.
If the indication stops, decreases or changes, it is most likely beta radiation.
Most common isotopes emit both beta and gamma radiation.
For this reason, the signal could decrease or change, but not stop totally.
Alfa: if there is no indication through the back of the case (the side of the tube GM), position the window
close to but not touching the source. If there is an indication, it is alpha, beta or low energy gamma.
If a sheet of paper placed between the window and the source stops the indication, it is most likely alpha.
Do not hold the source above the window , to avoid particles falling into the instrument.
If you perform the alpha/beta test above and there is no change or only a very slight change in the
indication, the source is emitting primarily gamma radiation.
COUNT LIGHT
DETECTOR
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Instruction manual
MICA WINDOW
METER
RANGE SWITCH
(MC1K-X1, X10, X100)
Fig.1
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