N=126 factory and r-process

N=126 factory and r-process

Guy SavardScientific Director of ATLAS

Argonne National Laboratory&

University of Chicago

ATLAS Users Meeting

ANL, May 15-16, 2014

R-process sensitivity to nuclear physics input

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

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From R. Surman, M. Mumpower et al, arXiv:1039.0059v1

Hot r-process

Supernova neutrino-driven wind cold r-process

Neutron-star merger cold r-process

binding energy neutron-capture rate lifetime

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


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


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Existing target wheel can handle expected high-intensity beams

Even with the most volatile metals, existing large rotating wheel can handle 10 pA

For typical metal targets with melting points above 1000 C, can handle 100 pA.

Courtesy of F. Pellemoine (GANIL)

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Mass measurements of neutron-rich nuclides

• 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!

• 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

• Masses determined via a measurement of the ions’ cyclotron frequency

OriginalOriginal

Area II 2012

Original

Area II 2012

CARIBU 2013

J. Van Schelt et al., Phys. Rev. C 85, 045805 (2012)

J. Van Schelt et al., Phys. Rev. Lett. 111,061102 (2013)

-200

0

200

400

600

800

1000

1200

ME

(CP

T)

- M

E(A

ME

03)

(keV

)

Comparison with the 2003 atomic mass evaluation

In Sn Sb Te I Xe Cs Pr Nd Pm Sm Eu Gd

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

J. Van Schelt et al., Phys. Rev. C 85, 045805 (2012)

J. Van Schelt et al., Phys. Rev. Lett., submitted (2013)

Less

bin

ding


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Low-energy experimental equipment

Beam properties

Delivers 1.5 kV to 10 kV beam to experimental stations

CPT

(installed)

X-ARRAY BPT

• Pulsed beams with rates from ~ 50 ms to seconds

• Low emittance

• High purity

• Experimental stations:

• Limited amount of space … but by now we are used to that

LASER LAB


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

Documents

N=126 factory and r-process