N=126 factory and r-process

1. N=126 factory and r-process Guy Savard Scientific Director of ATLAS Argonne National Laboratory & University of Chicago ATLAS Users Meeting ANL, May 15-16, 2014

2. R-process sensitivity to nuclear physics input Hot r-process Supernova neutrino-driven wind cold r-process Neutron-star merger cold r-process binding energy neutron-capture rate lifetime From R. Surman, M. Mumpower et al, arXiv:1039.0059v1 ATLAS Users Meeting Guy Savard, Argonne National Laboratory May 15-16, 2014

3. 238U 1 GeV/u 238U + 1H 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 ATLAS Users Meeting Guy Savard, Argonne National Laboratory May 15-16, 2014 3

4. Producing neutron-rich N=126 nuclei Production using deep-inelastic reaction: e.g.: 136Xe at 9 MeV/u and 5 pmA on a 10 mg/cm2198Pt rotating target All of these isotopes, except for 204Pt, are unknown … no mass, lifetime or decay properties known Extracted beam: ~ 15% of production Calculated using GRAZING (http://personalpages.to.infn.it/~nanni/grazing) ATLAS Users Meeting Guy Savard, Argonne National Laboratory May 15-16, 2014 4

5. 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, … target-like recoils beam dump extracted recoils to selection stage 136Xe rotating 198Pt target ATLAS Users Meeting Guy Savard, Argonne National Laboratory May 15-16, 2014 5

6. The CPT-II apparatus and low-energy stations for deep-inelastic reaction products Decay Station • 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 pmA while still providing required selection before precision Penning trap • Deep inelastic reactions down to ~0.01 mb … around 198Hf on N=126 line Mass separator (DM/M ~ 1/1000) ATLAS Users Meeting Guy Savard, Argonne National Laboratory May 15-16, 2014

7. Existing target wheel can handle expected high-intensity beams • Even with the most volatile metals, existing large rotating wheel can handle 10 pmA • For typical metal targets with melting points above 1000 C, can handle 100 pmA. Courtesy of F. Pellemoine (GANIL) ATLAS Users Meeting Guy Savard, Argonne National Laboratory May 15-16, 2014

8. Mass measurements of neutron-rich nuclides Original Area II 2012 CARIBU 2013 Original Original Area II 2012 • Masses determined via a measurement of the ions’ cyclotron frequency • Can measure the mass with a production rate of ~ 1 ion / s • Mass precision ~ 10-7 to 10-8 (10 -100 keV/c2) for masses approaching the r process • Canadian Penning Trap (CPT) has measured more than 100 neutron-rich nuclides, including more than 70 from CARIBU (including 6 isomers) • ~ 20 had never been previously measured by any technique • Currently reaching isotopes produced at the 10-6 fission branch level • For some nuclei, no prior information on the nuclide existed! J. Van Schelt et al., Phys. Rev. C 85, 045805 (2012) J. Van Schelt et al., Phys. Rev. Lett. 111,061102 (2013) ATLAS Users Meeting Guy Savard, Argonne National Laboratory May 15-16, 2014

9. Comparison with the 2003 atomic mass evaluation J. Van Schelt et al., Phys. Rev. C 85, 045805 (2012) J. Van Schelt et al., Phys. Rev. Lett., submitted (2013) In Sn Sb Te I Xe Cs Pr Nd Pm Sm Eu Gd Less binding Higher N • Trends indicate nuclei are less bound with neutron excess (affects the location of the r-process path • Good agreement with other Penning trap results and reaction Q value measurements • Large disagreement with results obtained with β-decay measurements ATLAS Users Meeting Guy Savard, Argonne National Laboratory May 15-16, 2014

10. Low-energy experimental equipment Beam properties • Delivers 1.5 kV to 10 kV beam to experimental stations • Pulsed beams with rates from ~ 50 ms to seconds • Low emittance • High purity • Experimental stations: BPT CPT (installed) X-ARRAY LASER LAB • Limited amount of space … but by now we are used to that ATLAS Users Meeting Guy Savard, Argonne National Laboratory May 15-16, 2014

11. 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. Provides: • Unique beams • High purity • Not high intensity but far reaching so well suited to sensitive low-energy experiments ATLAS Users Meeting Guy Savard, Argonne National Laboratory May 15-16, 2014