RADIATION MONITORS 840007, 840026 INSTRUCTION MANUAL SPER SCIENTIFIC
TABLE OF CONTENTS INTRODUCTION ....................................................... 2 CAUTION .................................................................. 2 BATTERY REPLACEMENT ...................................... 3 OPERATION ............................................................. 3 READINGS ................................................................ 5 INTERPRETING READINGS .................................... 6 SPECIFICATIONS .....................................................
BATTERY REPLACEMENT The unit is powered by a 9-volt battery. With the on button activated, the LED should be brightly lit. When the LED is no longer bright or when the LED dims in the presence of a radiation source, replace battery. To replace the battery: 1. Slide the plastic door off the unit located in the back. 2. Carefully replace the battery. DO NOT reach into the unit through the battery compartment while unit is on. G-M tube activation voltage is over 200 VDC. 3. Replace plastic door. 4.
sonable average time should be at least two minutes or more. The Geiger-Mueller tube is located behind the slots in the upper edge of the case. The surface of the tube is very thin (0.004"). This allows beta radiation to penetrate and to be detected with greater efficiency. (Beta rays and other types of radiation will be discussed in the next section). This thin surface is fragile and poking sharp objects through the slots will damage the tube. Your Geiger Counter is designed to be sensitive to: 1.
THIS IS THE POSITION IN WHICH TO HOLD THE GEIGER COUNTER TO TAKE READINGS. It is important to understand this, for misleadingly high meter readings can result from allowing Beta rays to be measured with the gamma rays. The meter scale is calibrated for gamma radiation. FIG. 2 READINGS There are two Sper Scientific Radiation Monitor models: 840007 - 0.1 to 10mR/hr 840026 - 0 to 100mR/hr All units are tested at the factory using gamma radiation.
beeps, at a rate that increases as the radiation level increases. Although this range is not as accurate as the displayed range, beeping will begin approximately at 15mR/hr. A continuous beep occurs approximately at 20mR/hr. These built-in ranges greatly simplify operation and allow reasonably quick and accurate measurements to be made. The meter is not intended to indicate levels below 0.1 mR/ hr., therefore, readings taken below this level should be considered extremely crude.
It is important to note that the field intensity from a radioactive object decreases very quickly with distance. If the object is very small, increasing the distance from the object by a factor of two decreases the radiation level by a factor of four. This is called a square law situation, which demonstrates the dependence of proximity on dose for small radioactive sources. Larger sources, such as a large deposit of radioactive minerals, will show much less of this effect.
Atoms are composed of three basic particles: protons, neutrons and electrons. Electrons are extremely light, negatively charged particles that exist as a cloud around the center, or nucleus, of the atom. Sometimes the electrons are said to occupy orbits around the nucleus. These electrons are attracted to the nucleus because of the positively charged protons that, along with the neutrons, make up the nucleus. Atoms bond together in molecules when one atom gives up or shares an electron with another atom.
The energy released in each decay can be enormous. This decay process is utilized in atomic reactors and bombs. When certain very heavy isotopes of uranium or plutonium (or several other isotopes) decay, they may split apart. This process is called fission. In fission, the entire nucleus splits apart, causing two new atoms and releasing a very large amount of energy.
given off from natural radioactive minerals in the earth's crust is a major constituent of background radiation. For the most part, it is quite low, due to the long time required for the remaining radioisotopes to decay. In atomic reactions (either natural or forced by man) the decay process is sped up by the effect of neutrons given off in the fission process interacting with more unstable isotopes to cause immediate decay.
Neutrons, having no net charge, do not interact with matter as easily as other particles, and can drift through great thickness of material without incident. A free neutron, drifting through space, will decay in an average of 11.7 minutes, yielding a proton and an electron (beta ray). The neutron can also combine with the nucleus of an atom, if its path carries it close enough. When a neutron is absorbed into a nucleus, it is saved from its ultimate fate (decay), but may render the nucleus unstable.
LIMITED WARRANTY The 840007 and 840026 Geiger counters are warranted for 5 years on electronics and 1 year for G-M tube from the date of purchase. If a unit fails to function properly within the warranty period, Sper Scientific will repair or replace the unit, at its option. This warranty does not cover any damage to the unit as a result of misuse, accident or repair by unauthorized personnel. Sper Scientific reserves the right to make such determination on the basis of factory inspection.
