Count is a numerical value, which express the coarseness or fineness diameter of the yarn and also indicate the relationship between length and weight the mass per unit length or the length per unit mass of that yarn.
The industrial-scale conversion of lithium-6 to tritium is very similar to the conversion of uranium into plutonium In both cases the feed material is placed inside a nuclear reactor and removed for processing after a period of time.
Alternatively, neutrons from earlier stage fusion reactions can be used to fission lithium-6 in the form of lithium deuteride for example and form tritium during detonation.
This approach reduces the amount of tritium-based fuel in a weapon. For this reason, tritium is included in nuclear weapon components only when it causes more fission than its production sacrifices, namely in the case of fusion-boosted fission.
Of the four basic types of nuclear weapon, the first, pure fission, uses the first of the three nuclear reactions above. The second, fusion-boosted fission, uses the first two.
The third, two-stage thermonuclear, uses all three. Pure fission weapons[ edit ] The first task of a nuclear weapon design is to rapidly assemble a supercritical mass of fissile uranium or plutonium. A supercritical mass is one in which the percentage of fission-produced neutrons captured by another fissile nucleus is large enough that each fission event, on average, causes more than one additional fission event.
Once the critical mass is assembled, at maximum density, a burst of neutrons is supplied to start as many chain reactions as possible.
Early weapons used an " urchin " inside the pit containing polonium and beryllium separated by a thin barrier. Implosion of the pit crushed the urchin, mixing the two metals, thereby allowing alpha particles from the polonium to interact with beryllium to produce free neutrons.
The resulting small-scale fusion produces neutrons at a protected location outside the physics package, from which they penetrate the pit. This method allows better control of the timing of chain reaction initiation.
In practical applications, the amount of material required for criticallity is modified by shape, purity, density, and the proximity to neutron-reflecting materialall of which affect the escape or capture of neutrons.
To avoid a chain reaction during handling, the fissile material in the weapon must be sub-critical before detonation. It may consist of one or more components containing less than one uncompressed critical mass each.
A thin hollow shell can have more than the bare-sphere critical mass, as can a cylinder, which can be arbitrarily long without ever reaching criticality. A tamper is an optional layer of dense material surrounding the fissile material. Due to its inertia it delays the expansion of the reacting material, increasing the efficiency of the weapon.
Often the same layer serves both as tamper and as neutron reflector. Gun-type assembly weapon[ edit ] Main article: See Little Boy article for a detailed drawing. Before the detonation, the uranium was formed into two sub-critical pieces, one of which was later fired down a gun barrel to join the other, starting the nuclear explosion.
Despite its inefficiency, this design, because of its shape, was adapted for use in small-diameter, cylindrical artillery shells a gun-type warhead fired from the barrel of a much larger gun.
Such warheads were deployed by the United States untilaccounting for a significant fraction of the U in the arsenal, and were some of the first weapons dismantled to comply with treaties limiting warhead numbers. The rationale for this decision was undoubtedly a combination of the lower yield and grave safety issues associated with the gun-type design.
Implosion-type weapon[ edit ] For both the Trinity device and the Fat Manthe Nagasaki bomb, nearly identical plutonium fission through implosion designs were used.
The Fat Man device specifically used 6. See Fat Man article for a detailed drawing. During detonation, criticality was achieved by implosion.
The plutonium pit was squeezed to increase its density by simultaneous detonation, as with the "Trinity" test detonation three weeks earlier, of the conventional explosives placed uniformly around the pit.
The explosives were detonated by multiple exploding-bridgewire detonators. Flash X-Ray images of the converging shock waves formed during a test of the high explosive lens system.
An implosion shock wave might be of such short duration that only part of the pit is compressed at any instant as the wave passes through it. To prevent this, a pusher shell may be needed.
The pusher is located between the explosive lens and the tamper. It works by reflecting some of the shock wave backwards, thereby having the effect of lengthening its duration. It is made out of a low density metal —such as aluminiumberylliumor an alloy of the two metals aluminium is easier and safer to shape, and is two orders of magnitude cheaper; beryllium has high-neutron-reflective capability.
Fat Man used an aluminium pusher. The series of RaLa Experiment tests of implosion-type fission weapon design concepts, carried out from July through February at the Los Alamos Laboratory and a remote site Once the chain reaction started in the plutonium, the momentum of the implosion had to be reversed before expansion could stop the fission.For the direct determination of LDL cholesterol in nonfasting patients or in patients whose fasting triglycerides are > mg/dL, where the estimation of LDL by .
For the direct determination of LDL cholesterol in nonfasting patients or in patients whose fasting triglycerides are > mg/dL, where the estimation of LDL by .
Nuclear weapon designs are physical, chemical, and engineering arrangements that cause the physics package of a nuclear weapon to detonate. There are three existing basic design types: pure fission weapons were the first nuclear weapons built and have so far been the only type ever used in warfare.; boosted fission weapons improve on the implosion design..
Boosting can more than double the. Determine the combined mass of the cylinder and the water to the nearest g. 4. Calculate the density of the water and record this as the density of a 0% solution.
If no parasites are observed report out as “No parasites seen.” 2. Iodine Wet mount. a. Place a drop of Lugol's iodine solution on a slide.
Apparatus. A list of equipment requirements is contained in AASHTO R13 and ASTM D Procedure. The preliminary geotechnical report .