* Astronomy

The Helium-3 Shortage: Supply, Demand, and Options for Congress

The world is experiencing a shortage of helium-3, a rare isotope of helium with applications in homeland security, national security, medicine, industry, and science. For many years the supply of helium-3 from the nuclear weapons program outstripped the demand for helium-3. The demand was small enough that a substantial stockpile of helium-3 accumulated. After the terrorist attacks of September 11, 2001, the US federal government began deploying neutron detectors at the U.S. border to help secure the nation against smuggled nuclear and radiological material. The deployment of this equipment created new demand for helium-3. Use of the polarised helium-3 medical imaging technique also increased. As a result, the size of the stockpile shrank. After several years of demand exceeding supply, a call for large quantities of helium-3 spurred federal officials to realize that insufficient helium-3 was available to meet the likely future demand.
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Helium clue found in echo of the big bang

The subtle signal of ancient helium has shown up for the first time in light left over from the big bang. The discovery will help astronomers work out how much of the stuff was made during the big bang and how much was made later by stars.
Helium is the second-most abundant element in the universe after hydrogen. The light emitted by old stars and clumps of hot pristine gas from the early universe suggest helium made up some 25 per cent of the ordinary matter created during the big bang.
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The A-B phase boundary in superfluid 3He
The A-B transition is an exemplar first-order phase boundary. To date, we have measured the latent heat, surface tension, inter-phase contact angle at cell walls, and heterogeneous nucleation phenomena. Most recently, we have made a magnetic 'trap' so that the transition from the B to A phase can be induced away from the container wall, free from the influence of any impurities or defects. These will be the first ever measurements of such pure homogeneous nucleation.

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The Size of the Helium-8 Nucleus Has Been Measured
To be more precise, the charge radius of this heaviest of helium isotopes (containing two protons and six neutrons) has been measured for the first time. The charge radius tells you how widely the proton charge is spread out in space. The new work, conducted by a Argonne-Chicago-GANIL-Windsor (Canada)-Los Alamos collaboration, arrives at a value of 1.93 fm (1 fermi equals 10^-15 m). For comparison, the charge radius of the He-6 isotope, is 2.068 fm; that is, the lighter isotope actually has a larger charge radius, the result of the binding effect of the strong nuclear force. He-8 is very rare, hard to make, and represents the most neutron-rich material known on Earth. Still heavier helium groupings, such as He-10, are not really bound entities-they can only be considered as resonances.

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