Critical mass in physics - an explanation

06-21  Source: Network gathering  Views:26 


Critical mass in physics - an explanation

The chain reaction needs a critical mass.

Nuclear fission - physics knowledge briefly

  • The two chemists Otto Hahn and Friedrich Strassmann discovered together with the physicist Liese Meitner in 1939 that a core of a particular uranium isotope (namely uranium-235) can be split by bombardment with slow neutrons in two moderate rubble cores. The cleavage products are (due to their neutron excess) usually radioactive.
  • Closer investigation some time later showed that this division is not only energy that was stored in the core, free will, but also 2-3 neutrons.
  • The released during nuclear fission neutrons can further uranium nuclei split, where more neutrons are released.
  • Are there enough uranium nuclei present, the process is growing like an avalanche - a chain reaction occurs in the vast amounts of energy are released (keyword: nuclear bomb).

Critical Mass - what is it?

  • Requirement for physical chain reaction in the cleavage of course is that the released neutrons in turn split uranium nuclei.
  • Here are a few conditions, however, must be met: The neutron afford to lose either by other reactions (eg trapping by other atomic nuclei or Wandeinfang.) Nor to the outside, ie can from the uranium-bearing material out, escape.
  • The simplest option is therefore to take as much fissile material (uranium-235) that formed neutron meet again only on fissile material, so make their way through the material to a new reactant before they leave it, or otherwise react.
  • Of course, you can achieve this by having a minimum mass of fissile material.
  • If this mass spherical, it is called the critical mass of the amount of fissile material that is at least necessary for the end of the chain reaction.
  • The critical mass of pure (!) Uranium-235 is about 50 kg Enriched Fissile materials correspondingly more.
  • Special Cases of neutron reflective material to reduce this critical mass, of course, so already about 15 kg U-235 and about 4.4 kg of the likewise fissile plutonium as a critical mass (military technical, so for a nuclear explosion) are sufficient.
Related articles
  • Critical mass in physics - an explanation 06-21

    The chain reaction needs a critical mass. Nuclear fission - physics knowledge briefly The two chemists Otto Hahn and Friedrich Strassmann discovered together with the physicist Liese Meitner in 1939 that a core of a particular uranium isotope (namely

  • Mechanics vs. Physics - an explanation for primary school children 02-01

    A steam engine can help a child to explain the mechanics. Physics is a school subject that is introduced to the mainstream school in the sixth grade. Reason for the rather late start of the tray during the school career, is that children need to have

  • Resonance in physics - an explanation 08-05

    Attempt to resonance Important terms for resonance Before it goes to a trial for the case of resonance, you should be familiar with the essential concepts: Frequency is the number of movements within a unit time. If it comes in trying so to increase

  • What's a nuclear bomb? 03-08

    It is a nuclear bomb. What atom bomb means To understand the concept, you should first look at a conventional bomb. These bursts when ignited in her explosive which is compressed in a tight container. The rapid combustion produces a large amount of g

  • AION: Kantor - Class Guide 12-16

    The Kantor is an important group of players in the virtual world of AION. Races, classes and subclasses in AION AION is where you operate a so-called MMORPG (massively multiplayer online role-playing game) with thousands of other players simultaneous

  • Subatomic particles - a statement 12-24

    Subatomic particles are parts of an atom. Subatomic particles are particularly small particles, where one researches in physics and which belong to particle physics. They are critical in quantum physics. These are subatomic particles When subatomic p

  • Power adapters for SATA - so you can keep your old power supply 07-28

    Power connector for SATA are electrically identical, but have a different form factor. Power supply of SATA drives Modern SATA hard drives have not only a more compact data cable as their used IDE ancestors, they also need a new power cord. Current p

  • How is a hype? - Exciting for trend development 02-18

    The emergence of a hype is greatly accelerated, especially through the Internet. This creates a hype A hype is nothing that can be planned. It must interact several factors that hype arises and persists. By definition is a hype something seen over ti

  • What is meant by total internal reflection? - A simple explanation of the physics 05-14

    Fiber optic cables work with total reflection. Refraction - this knowledge you need Light propagates when him "nothing will stand in the way" straight out. The best example of this are not only the laser beams, but also the sun's rays through a

  • Why is the world round? - A simple explanation of the physical phenomenon 06-22

    Our not quite round, blue planet. Gerd_Altmann / Pixelio At the beginning of the Big Bang was As a result of the Big Bang assumed swirled innumerable, very small particles of matter through the universe and began to come together. The closer the part

  • What is blood pressure? - An explanation of the physics 02-17

    Sphygmomanometers indicate a physical quantity. The heart makes the blood pressure In liquids can generate pressure by pumping. Also, the blood circulation is maintained by pressure generated by the heart muscle. This blood pressure depends on the ca

  • Why current flows? - An explanation of the physics 05-28

    A battery has separate charges. Current - what is that? Whether it is electricity from the grid or from accumulators and batteries, electricity are always moving charges. In the simplest case, it is with a current flowing through a metallic conductor

  • What is distilled water? - An explanation of the physics 06-29

    For experiments often distilled water is required. Distilled water - you should know For many chemical, physical and biological experiments are needed distilled water, for example, as a solvent for other substances. Finally, one wants to prevent this

  • The critical angle - a simple explanation 05-02

    The reflections below the water surface caused by total internal reflection. General information Refraction To understand what is a critical angle, you have to deal first with the fundamental questions of refraction. Surely you have already observed

  • Law of conservation of mass - a simple explanation 10-22

    Mass is not lost! GTÜ / Pixelio Conservation of mass - understand the law The law of conservation of mass is one in chemistry, specifically chemical reactions are involved in the majority of applications. The French chemicals Lavoisier notes in the 1

  • How can the atomic nuclei are split? - A physical explanation 05-29

    Atomic nuclei have on their outer shell negatively charged Elrktronen. Illustration_Marcus_Stark / Pixelio If you're wondering how atomic nuclei are split, you must first understand how an atom is constructed. General on the nuclear Atoms are the sma

  • How to recognize forces? - An explanation of the physics 06-21

    Forces deform springs. Forces in physics - you should know Intuitively everyone has probably an idea of ​​what "forces" are. But is this idea also in line with what is understood the physics including? For the word "power" is used in e

  • Magnetism of the earth - a physical explanation 07-24

    The Earth is surrounded by a magnetic field. easy to the point - magnetism The term magnet, lithos magnet, comes from the Greek and means "stone of magnesium". This rock attracts as iron, iron compounds, cobalt and nickel sharply. In principle,

  • Straight Curve - an explanation of the physics expert 09-15

    Masses curve spacetime. Straight Curve - the everyday world speaks against Although not all of mathematics education from the school is still present, a curve can - if common sense - not be straight. Because the property of curves it's that they have

  • Adiabatic compression - an explanation from physics 11-23

    The air pump is an example of adiabatic compression. Adiabatic compression explained simply When it comes to compression, gases are usually (rarely liquids) in a particular system in the game. In the model case, it involves a rarefied gas, which is a