Ice-nine fusion

ICE-NINE FUSION

Ice-nine fusion is the name coined in a July, 1999 Scientific American Letter by Nobelist Frank Wilczek for the runaway fusion of a strangelet, a theoretical particle that experimentalists have attempted to create at the AGS and the RHIC without success. Under some theories of strange matter, the great stability of the strangelet nucleon, which consists of approximately equal numbers of up, down and strange quarks, could allow for a runaway fusion reaction with normal nucleons, which consist solely of up and down quarks. This would require either a neutral strangelet so that the Coulomb barrier to fusion is not present, a negative strangelet so that it is attracted to a positive nucleus, or under some speculative theories, even a positive strangelet which could come within one Angstrom of the abundant Helium and Hydrogen nuclei and engage in spontaneous fusion.

The barrier to creation of a strangelet is the energy required to create a strange quark. Prior to the RHIC, the AGS could only create Lambda particles with only a single strange quark. The RHIC might create quite a few more. The Large Hadron Collider is projected to collide Lead nuclei at energies some 30-fold greater than the RHIC, and might create enough strange quarks to create a strangelet. Searches are planned upon commencement of collisions at the ALICE detector. Since strangelet theory predicts that they are highly radioactive at low mass, but become increasingly more stable as they become more massive, it would require creation of more than a few strange quarks to create a stable strangelet that could engage in runaway fusion.

STRANGELET THEORY WHICH ALLOWS FOR RUNAWAY "ICE-NINE" FUSION

Nucleons with only a few strange quarks are highly unstable. The known particles with strange quarks are unstable because the strange quark is heavier than the up and down quarks, so strange particles, such as the Lambda particle, which contains single up, down, and strange quarks, always lose their strangeness, radioactively decaying, via the weak interaction to lighter particles containing only up and down quarks. However this instability of strangelets might cease to be true for states with a sufficiently large number of quarks. This is the "strange matter hypothesis" of Bodmer and Witten. According to this hypothesis, when you collect a large enough number of quarks together, the lowest energy state is one that has roughly equal numbers of up, down, and strange quarks, namely a strangelet. The theories show that with increasing mass, the stability of a strangelet increases, increasing the radioactive half-life until with sufficiently large mass, they are fully stable. Various theories predict either positive, neutral or negative strangelets.

FUSION REQUIREMENTS

In order to engage in fusion, any newly created strangelet would be required to come into close contact with normal matter, allowing the strong force to bind the quarks from both nucleons, with a release of fusion energy. The newer, larger strangelet, following fusion, would have an excess positive charge , which would require subsequent emission of a positron as a radioactive decay mode. The time delay for this radioactive decay would slow down the spontaneous fusion that might otherwise take place, as the larger positive charge of the strangelet would keep it further away from the positively charged normal nuclei in the vicinity. This time delay might be sufficient to allow the spontaneous decay of the strangelet, ending the fusion reaction.

However, in the presence of large quantities of low-Z material such as Hydrogen and Helium, this difficulty might be overcome, as they have only 1 or 2 positivbe charges, respectively. One of the objections to the proposed Lead-Lead collisions at the LHC is that they will be done in conditions of high concentrations of Helium and Hydrogen , not normally present on the moon in large concentrations where high energy cosmic rays tend to mimic LHC collisions. However, even this mimicry is not identical, as the LHC collides high-Z nuclei, and cosmic rays involve protons colliding with medium-Z nuclei. Thus, the LHC might provide an excellent growing ground for strangelet fusion, which would not take place in nature in similar conditions.

SEARCHES FOR STRANGELETS

Numerous searches for strangelets have been undertaken since their theoretical prediction of existence, without success. These include searches for positive, neutral or negative strangelets at the AGS in the 1990s, searches for strangelets at the RHIC when the AGS became the RHIC injector, and searches for strangelets generated by cosmic rays. These extensive searches have all yielded negative results, with no detection of a strangelet.
The probable reason is that strangelets require conditions for creation that do not exist either in nature, or at the RHIC/AGS. Those probable conditions by theory are creation of a large number of strange quarks, something even high-energy proton cosmic ray impacts might not create when striking our atmosphere . All such searches have presupposed the benign nature of strangelets, i.e. that they are not capable of engaging in ice-nine fusion.

"AT REST" STRANGELETS AT COLLIDERS COMPARED TO RELATIVISTIC STRANGELETS IN NATURE

There are two primary distinctions between colliders and nature for strangelet production. The LHC collider creates conditions somewhat different in nature, by colliding Lead on Lead, whereas in nature, even if the center-of-momentum energy of collision is equal to or greater than in a collider, the cosmic ray impacts are almost entirely high energy protons striking medium-Z nuclei such as Iron, Silicon or Nitrogen, which have far fewer up and down quarks initially than for Lead-Lead collisions. Whether this distinction will allow for production of strangelets at the LHC, when none have been found in nature, is still the subject of intense debate in 2008.

The other distinction is that if strangelets are exclusively neutral, then any produced in nature would be relativistic in speed relative to earth. If they have charge, as most theories suggest, then they would rapidly decelerate as they ionized their surroundings, and come to rest. However, if they have no electric charge, they would zip through earth in about 1/4 second at 99.99+% c. At such speeds, they would be relatively inert due to their time delay for fusion, and should be harmless. Conversely, if neutral strangelets are produced in a collider, they would be relatively "at rest" near to a good growing ground of low-Z material , and would endlessly orbit through earth, giving repeated opportunity to interact and grow.

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