N=126 factory

Guy SavardScientific Director of ATLAS

Argonne National Laboratory&

University of Chicago

ATLAS Users Meeting

ANL, May 15-16, 2014

2ATLAS Users Meeting Guy Savard, Argonne National Laboratory May 15-16, 2014

208Pb

238U

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

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3ATLAS Users Meeting Guy Savard, Argonne National Laboratory May 15-16, 2014

238U1 GeV/u 238U + 1HArmbruster 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

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4ATLAS Users Meeting Guy Savard, Argonne National Laboratory May 15-16, 2014

Producing neutron-rich N=126 nuclei

Production using deep-inelastic reaction: e.g.: 136Xe at 9 MeV/u and 5 pA on a 10 mg/cm2 198Pt rotating target

Calculated using GRAZING

(http://personalpages.to.infn.it/~nanni/grazing)

Production rate for N=126 nuclei

1.0E-01

1.0E+00

1.0E+01

1.0E+02

1.0E+03

1.0E+04

1.0E+05

1.0E+06

196 197 198 199 200 201 202 203 204 205

Mass (A)Y

ield

(io

n/s

)

All of these isotopes, except for 204Pt, are unknown … no mass, lifetime or decay

properties known

Extracted beam: ~ 15% of production

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5ATLAS 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, …

136Xe

extracted recoils

beam dump

rotating 198Pt target

to selection stage

target-like recoils

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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 pA while still providing required selection before precision Penning trap

Deep inelastic reactions down to ~0.01 b … around 198Hf on N=126 line Mass

separator (M/M ~ 1/1000)

Decay Station

7ATLAS 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