ESS Gold A Proposal for a Next Generation European Neutron Source K H Andersen, European Spallation Source & C J Carlile, Uppsala University

ESS will be the most intense neutron source in the world First ideas 1985, full specification by 2025? 16th September 2016

Neutron source fluxes Berkeley 37-inch cyclotron 350 mCi Ra-Be source Chadwick 1930 1970 1980 1990 2000 2010 2020 105 1010 1015 1020 1 ISIS Pulsed Sources ZINP-P ZINP-P/ KENS WNR IPNS ILL X-10 CP-2 Steady State Sources HFBR HFIR NRU MTR NRX CP-1 1940 1950 1960 Thermal flux n/cm2-s (Updated from Neutron Scattering, K. Sköld and D. L. Price, eds., Academic Press, 1986) FRM-II SINQ SNS ESS J-PARC

Usable neutron brightness

Usable neutron brightness Spallation 4 x brightness per decade Fission 1.2 x brightness per decade

The neutron response to a delta-function proton pulse One, 5MW, 105ns pulse

Matched proton pulse/neutron moderation time The Goldilocks solution Not too hot, not too cold, but just right ! Matched proton pulse/neutron moderation time

The Goldilocks solution ISIS, SNS, J-PARC have a 0.6 ms proton pulse length ESS has a 2.86 ms proton pulse length Moderation time for cold neutrons ~80 ms (22 l [Å] ms) Short-pulse sources are mismatched by 80/0.6 = 140 times Long-pulse sources are mismatched by 2860/80= 35 times Both kinds of source are significantly mismatched

Why should we build ESS Gold ? To understand the diversity & complexity of new Materials Thus to create better Materials for health, climate & energy And build better devices for industry Nota bene! Materials science is INCREMENTAL

…? Material Science & Innovation “The Stone Age didn’t end for lack of stone” Ahmed Zaki Yamani Today 2016 Yesterday 1990 The future 2026 …? We have to build the best facilities with the best instruments if we are to develop, understand, and harness New Materials

broad scientific reach Neutrons have a broad scientific reach

Materials Science and Society NEW MATERIALS FUNCTIONAL FOOD SOLAR ENERGY MEDICINE TAILOR MADE MATERIALS COSMETICS PACE- MAKERS MOBILE PHONES BIO FUEL TRANSPORT GEO SCIENCE IMPLANTS LIGHTING

What will a factor of 1000 facilitate? The interplay of magnetic & electrical (sc) functionality Routine polarisation analysis – exotic magnetism Sample polarisation – contrast scanning – video protein crystallography Fine resolution vibrational spectroscopy of molecular robots Microscopic geometrical properties of topological materials Microscopic understanding of medical healing processes The dynamics of pharmaceutical lock & key mechanisms – delivery channels Precision studies of bodily membranes – skin & cell walls Engineering stresses in sub-mm3 gauge volumes – spider silk… Dynamic tomography of combustion and corrosion Nuclear magnetism at mK temperatures Entanglement using interferometry Gravitational quantisation, waves and gravitons A finite value for the edm of the neutron The probability of neutron-antineutron oscillations The neutron lifetime to 100ms precision

time (μs) 0 100 200 300 Intensity

short-pulse Intensity time (ms) 0 1 2 3

Intensity long-pulse time (ms) 0 1 2 3

Intensity time (ms) 0 1 2 3

Intensity time (ms) 0 1 2 3

Intensity time (ms) 0 1 2 3

Intensity time (ms) 0 1 2 3

80 msec pulse 35x brightness Intensity time (ms) 0 1 2 3

…now that they’ve found LHC ! The World’s Ultimate Slow Neutron Source ? …now that they’ve found the Higgs boson 1000 x SNS & 35 x ESS

Potential Upgradeability 2nd target and neutrino source Compressing the msec pulse to match the moderating time of cold neutrons 2.86ms to 80µs 4 rings of 1100m Oce Each containing 25 pulses of 105ns Permanent magnets Peak intensity gain of 35 times Total gain of 1000 times today Reduces the instantaneous power on the target cf short pulsed source D. McGinnis, M. Lindroos & R. Miyamoto IPAC 2013

2065 ESS Gold