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N=126 factory Guy Savard Scientific Director of ATLAS Argonne National Laboratory & University of Chicago ATLAS Users Meeting ANL, May 15-16, 2014
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2 ATLAS Users Meeting Guy Savard, Argonne National Laboratory May 15-16, 2014 208 Pb 238 U Accessing new regions: deep-inelastic reactions to reach the far north-east of the nuclear chart The Science: nuclear shell structure at the extremes r-process: second abundance peak, fission recycling and termination fission barriers of neutron-rich nuclei and symmetry energy connection of hot-fusion SHE island and mainland Unusual GT vs 1st forbidden beta decay ratios 2
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3 ATLAS Users Meeting Guy Savard, Argonne National Laboratory May 15-16, 2014 238 U 1 GeV/u 238 U + 1 H Armbruster et al. difficult to reach via fragmentation cannot be reached via fusion unique physics, critical to the r-process, which is wide open for a facility able to reach there, even in the FRIB era 3
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4 ATLAS Users Meeting Guy Savard, Argonne National Laboratory May 15-16, 2014 Producing neutron-rich N=126 nuclei Production using deep-inelastic reaction: e.g.: 136 Xe at 9 MeV/u and 5 p A on a 10 mg/cm 2 198 Pt rotating target Calculated using GRAZING (http://personalpages.to.infn.it/~nanni/grazing)http://personalpages.to.infn.it/~nanni/grazing All of these isotopes, except for 204 Pt, are unknown … no mass, lifetime or decay properties known Extracted beam: ~ 15% of production 4
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5 ATLAS Users Meeting Guy Savard, Argonne National Laboratory May 15-16, 2014 Collecting the N=126 recoils Deep inelastic reactions used in the past to produced n-rich isotopes, the products identified in complex setups (Mayer 1985, Corradi 1999, …), but no system has so far been able to collect them efficiently. But the cross-section are high and with high primary beam intensity and efficient collection efficiency sizable yield in unexplored n-rich regions are reachable Proposed collection system capitalizes on High primary beam intensity High -intensity gas catcher technology Feed low-energy systems: mass measurements, decay spectroscopy, … 136 Xe extracted recoils beam dump rotating 198 Pt target to selection stage target-like recoils 5
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G. Savard May 3-5 2010 ATLAS Operation’s Review 6 The CPT-II apparatus and low-energy stations for deep-inelastic reaction products Designed to push back space charge limit –RFQ ion guide now operating in DC mode to avoid space charge build up –Rough mass separation by in- flight mass separator before isobar separator –Rest of system essentially the same Can operate at up to 5-50 p A while still providing required selection before precision Penning trap Deep inelastic reactions down to ~0.01 b … around 198 Hf on N=126 line Mass separator ( M/M ~ 1/1000) Decay Station
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7 ATLAS Users Meeting Guy Savard, Argonne National Laboratory May 15-16, 2014 Status Main components are being constructed Production system will be installed in experimental area III in early 2015 CPT moved to this area later in 2015 to start mass measurement program in this region Low-energy beamline to deliver these beams to various experiments to be stationed temporarily in area III to follow
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