5-7 February 2005, Univ. of Hawaii
· Basically the white paper sketching out a plan for a gigaton deep-ocean MeV threshold energy anti-neutrino detector, survived the critical discussions. There is no question about the existing technical capability to monitor reactors throughout the earth, it is a matter of cost. The suggested cost scale for the ultimate gigaton scale detector seems not far off.
· Aside from the exciting science that can be done with this instrument, enough to engage a large research community for many years, some new science goals were identified. In particular the potential to detect few-day precursor anti-neutrino levels from an incipient supernova within our galaxy caught everyone's attention. Also much interest was expressed in the search for a geo-reactor (ultimately responsible for the geomagnetic field, and which seems to some increasingly plausible), which would pose a steady but irremovable background for reactor monitoring.
· Photodetection remains the most needed development area for cost control. Traditional phototube makers estimate modest reduction in quantity costs with hand labor. Industrialization can reduce costs by a factor of ten. Next generation developments are indeed on the horizon, with some crucial technology in flexible circuits and other new developments available, but need work and funding to bring to fruition.
· Ocean engineering presents challenges, but there are no apparent show-stoppers at the 10 megaton bag level. Smaller is of course easier.
· Water doping for increased light output seems distinctly possible and economical. Some studies are underway, more needed. Addition of low-40K salt for neutron detection is attractive. Gadolinium chloride is very interesting, but world supplies may be a problem (at the gigaton detector size).
· Small detectors for placement near (10s of meters) reactors certainly can make useful monitors for reactor burning. But this only works for cooperating reactor operators. IAEA is apparently supportive of this; costs are a problem.
· Some concerns were raised about the cost effectiveness of the large detection scheme, when contrasted to traditional means for intelligence gathering about possible surreptitious manufacture of weapons material. Detection of a reactor of 30 MW(t), capable of producing 10 kg of Pu per year-- 1% of the power of the nominal 1000 MW(e) power reactor would be possible at distances of 200 km, but not much more.
· None of the beam scenarios discussed for weapons deactivation or destruction are close to possible realization.
· The scheme of making a steerable PeV neutrino beam to shoot through the earth at stored weapons, seemed to be incredible to most attendees. There appear to be problems with beam acceleration, magnets, synchrotron radiation, possible side effects from earth heating near the muon ring, etc. While a look at the Livingston plot suggests that such an accelerator may be three or four decades out, nobody can see how to achieve the goals at this point.
· One alternative discussed would be to use an accelerator of TeV energies from earth orbit to produce muon beams to penetrate bunkers. While perhaps constructable with present technology, cost and power are problems. However, vulnerability to inexpensive attack appears to be an insurmountable objection.
· Another alternative would involve a multi-PeV (positron – electron making Z's) accelerator on the moon, making (resonant electron anti-) neutrinos that could be precisely placed on earth (to 20 km depth). Such an installation would appear to be defendable (unlike low earth orbit). However, such an accelerator is not yet practical. Of course, costs would be enormous on the moon.
· The only scheme we discussed for X-raying bunkers is via a 10 TeV neutrino beam from the other side of the earth (or at a slant angle from nearer locations). One would have to overfly the site with large area precision muon detectors at precise times. Certainly 10 TeV accelerators exist (CERN, LHC), but intense and steerable neutrino beams of this energy pointing through the earth are not yet practical. This may bear further investigation.
· There needs to be a study of reactor detectors in realistic backgrounds and with various trial locations and sizes, and various targets of potential interest.
· There needs to be study of the gigaton array design, in terms of module sizes, detectors, noise rates, threshold sensitivity, backgrounds and depth, etc.
· Ocean engineering is needed to study container options, construction and filling, deployment, maintenance, and the like.
· Examine "roadmap" options, such as intermediate sized prototype anti-neutrino detectors that could detect a geo-reactor and do interesting science while developing technology. An interesting possibility to have an ocean bottom detector (between Korea and China) located in the neutrino beam from J-Parc in Japan, bears further consideration.
· There should be a dedicated next-generation photodetection workshop.
· Interested groups should cooperate upon study proposals for both photodetection and water additives for increased light output.
· Should develop plans to stay in contact with EU plan for KM3 (cubic kilometer high energy neutrino telescope) in the Mediterranean, particularly in light of interesting discussions for a possible large (perhaps 100 kilotons) scintillator detector near Pylos, Greece.
· We should encourage accelerator development towards new means of acceleration gradients, going beyond the present maximum of 200 MeV/m.
· Further thought should be given to the problem of detecting underground cavities.
· Several attendees suggested a follow-up workshop in 24 months to evaluate progress and identify next goals.