物理蓋革-彌勒管(gm管)急

蓋革-彌勒管原理是怎樣??
In short, a Geiger-Muller tube is essentially a thin-walled gas-filled metallic tube with a needle electrode projected within. It detects the radiating particle indirectly. The particle penetrates the thin wall and ionizes the gas. A current is momentarily set up, which is detected and after suitable amplification, measured by conection to a counter or milliammeter.
For details, please see
www.iki.rssi.ru/mirrors/stern/Education/wgeiger.html
為什麼它可以測得g(gama)射線,而測不到紅外線?那x射線,測得倒嗎??
GM tube works on the principle of ionizing. Gamma ray and X rays are ionizing radiation, they causes ionizing in substances (i.e. producing ion pairs) and hence can be detected by a GM tube.
Infrared cannot produce ionization and thus cannot be detected using a GM tube.
本底幅射是否一定能被GM管測得??
Not all background radiation can be detected by a GM tube. Extrememly high energy cosmic rays, radiation from radons and its decay products etc are mot sensitive to GM tube.
電視除了放出可見光外 ,還會放出什麼電磁波 , 為什麼它是本底幅射的來源?
TV sets in operation emits very soft X-rays and radiofrequency electromagentic waves. Strictly speaking, radiation from TV sets is not included in background radiation, which generally refer to the natural background. Those radiation from TV sets are artifical radiation.
希沃特是什麼的單位?
Sievert(希沃特) is a unit for "effective dose". It has taken into account the effects of all types of radiation and the biological effects of various body organs. Hence, it can indicate the degree of radiation hazard to an exposed individual.
In Hong Kong, the background radiation is around 0.0025 Sivert in a year, and a chest X-ray delivers a dose of about 0.00006 Sievert.

工作时，两个电极间加以一定的直流电压。当粒子或射线在气体中通过，由于碰撞电离而产生许多离子对，它们在电场作用下分别向两电极运动而被收集。这时在外线路里有电信号输出，借助电子仪器即可纪录和分析入射的粒子或射线的数目。

A Geiger-Mller tube consists of a tube filled with a low-pressure (~0.1 Atm) inert gas such as helium, neon or argon, in some cases in a Penning mixture, and an organic vapor or a halogen gas and contains electrodes, between which there is a voltage of several hundred volts, but no current flowing. The walls of the tube are either metal or the inside coated with metal or graphite to form the cathode while the anode is a wire passing up the center of the tube.

When ionizing radiation passes through the tube, some of the gas molecules are ionized, creating positively charged ions, and electrons. The strong electric field created by the tube's electrodes accelerates the ions towards the cathode and the electrons towards the anode. The ion pairs gain sufficient energy to ionize further gas molecules through collisions on the way, creating an avalanche of charged particles.

This results in a short, intense pulse of current which passes (or cascades) from the negative electrode to the positive electrode and is measured or counted.

Most detectors include an audio amplifier that produce an audible click on discharge. The number of pulses per second measures the intensity of the radiation field. Some Geiger counters display an exposure rate (e.g. mRh), but this does not relate easily to a dose rate as the instrument does not discriminate between radiation of different energies.

希沃特是輻射劑量的單位