ATLAS/CARIBU Status

ATLAS/CARIBU Status

Guy SavardScientific Director of ATLAS

Argonne National Laboratory&

University of Chicago

Workshop on Future GRETINA Science CampaignsArgonne National Laboratory, March 1, 2013

2ATLAS\CARIBU Status Guy Savard, Argonne National Laboratory February 15, 2013

Existing ATLAS facility Stable beams at high intensity and energy up to 10-20 MeV/u Light in-flight radioactive beams

– light beams, no chemical limitations, close to stability, acceptable beam properties CARIBU beams

– heavy n-rich from Cf fission, no chemical limitations, low intensity, ATLAS beam quality, energies up to 15 MeV/u

State-of-the-art instrumentation for Coulomb barrier and low-energy experiments Operating over 5000 hrs/yr at about 95% efficiency

– Users performing experiments at ATLAS: FY10: 390 FY11: 326 FY12: 394– About 10 Ph.D. theses per year (16 in FY12)

Suite of experimental equipment

3 injectors


Neutron-rich beam source for ATLAS: CARIBU “front end” layout

Main components of CARIBU– PRODUCTION: “ion source” is

252Cf source inside gas catcher • Thermalizes fission fragments• Extracts all species quickly• Forms low emittance beam

– SELECTION: Isobar separator• Purifies beam

– DELIVERY: beamlines and preparation

• Switchyard• Low-energy buncher and

beamlines• Charge breeder to Increase

charge state for post-acceleration

• Post-accelerator ATLAS and weak-beam diagnostics


CARIBU gas catcher: transforms fission recoils into a beam with good optical properties Based on smaller devices developed at ANL

– Radioactive recoils stop in sub-ppb level impurity Helium gas– Radioactive ion transport by RF field + DC field + gas flow– Stainless steel and ceramics construction (1.2 m length, 50 cm

inner diameter)– Fast and essentially universally applicable – Extraction in 2 RFQ sections with μRFQs for differential pumping

He gas

DC gradient

To acceleration and mass separator

RF

(cone)

RF (body)

252Cf


CARIBU building with first experiment (CPT mass spectrometer) April 2011


1 Ci 252Cf sourceabout 20% of total activity extracted as ionsworks for all speciescomplementary to uranium fission

Extracted isotope yield at low energy (50 keV)

> than 500 neutron-rich species extracted at > 1/s

> 150 whose masses have never been measured


CPT Measurement campaigns


Atomic Mass Evaluation comparison

Trend: more neutron-rich nuclei are found to be less bound than expected away from stability

In Sn Sb Te I Xe Cs Pr Nd Pm Sm EuGd

Higher N

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ATLAS\CARIBU Status Guy Savard, Argonne National Laboratory February 15, 2013


1437 - Being completed from previous PAC

1481 -measurements for r-process studies

1480 - measurements for new isotope discovery

Ongoing heavy-peak measurements

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• First Coulex with 141Cs – two goals:

1. Demonstrate feasibility & study backgrounds from stable beam contamination and decay with 850 MeV beam on Pb; i.e., “unsafe” Coulomb excitation; 4300 part/sec for 14.5 hours run.

2. Measure B(E2) of the 11/2+ state in 141Cs, via “safe Coulex” at 601 MeV for ~62 hours with ~3360 part/sec.

• B(E2) = 20(5) W.u., smaller than the 2+ level in 142Ba (32(1) W.u.), but similar to the value for the 2+ state in 140Xe (25.6(8) W.u). Figure: Gamma-ray spectra from 601- &

850- MeV 141Cs with the Coulomb excitation line at 369.2 keV. S. Zhu et al., to be published

First Coulomb excitation measurement with a CARIBU beam

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ATLAS layout with ongoing and planned upgrades

CARIBU

New in-flight separator (AIRIS)

EBIS

MHB RFQ new cryomodule

cryomodule and rebuncher rearranged

High-Intensity ECR

New low-energy experimental hall

Improved instrumentation

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Novel design from Accelerator R&D

group

World record performance

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All PMP milestones have been met, beam tune developed, now operational.

Parameter Required Value Demonstrated DesignBeam Output Energy ~220 keV/u 293 keV/u 293 keV/u Transmission for any test ion beam with input normalized rms emittance 0.1 -mm-mrad

65% 83% 83%

Charge-to-mass ratio of a test ion beam Q/A < 1/5 1/5.7 1/7Duty cycle 100% 100% 100%

ARRA funded upgrade: New RFQ accelerator section of PII linac

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Installation of cryomodule components (liquid helium manifold, helium and nitrogen plumbing, slow tuners, RF coupler warm windows, temperature sensors,…) and alignment of evacuated cavity-solenoid string is in progress

Cryomodule vacuum vessel is ready to receive cavity-solenoid string

Plans for FY2013 1) Complete off-line assembly and cold testing 2) Install into the beam line (Jun.-Sept. 2013)

and commission with beam

ARRA funded upgrade: Replacement of first booster cryostat module and liquid helium upgrade

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1st stage of ARRA funded upgrade – Front end reconfiguration (RFQ, PII cavities

rearrangement, electrostatic optics) completed– Commissioning completed

• Total transmission of 80% demonstrated– New tunes have been developed, ready for

operation …. actually running today!!!

2nd stage of ARRA funded upgrade– Construction of cryostat and cavities completed– Mock up assembly completed, final assembly

on-going– Preparation for new cryostat installation and

booster rearrangement ongoing– Expecting to shut down ATLAS for installation

at the end of May for ~ 4 months– Restart in October, facility operational when

GRETINA is ready for operation at ATLAS

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Summary of ongoing intensity and efficiency upgrade

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Community plan for GRETINA in coming years:– Complete MSU campaign by July 1 2013;– Move to ATLAS and installation;– ATLAS/CARIBU campaign from October 2013 to December 2014.– Return to MSU

Preparation for GRETINA @ATLAS campaign:– Site preparation ongoing for stand-alone operation and operation in front of the FMA;– GRETINA WORKSHOP (March 1-2 at Argonne);

• Day 1: discuss and exchange information with GRETINA users on the detailed science opportunities at ATLAS. Provide guidance for the coming call for proposals,

• Day 2: discuss science opportunities and future siting of GRETINA beyond the ATLAS campaign.

– Call for proposals including ATLAS/CARIBU beams to GRETINA (early March 2013)– ATLAS/GRETINA PAC (May 2013)– GRETINA installation at ATLAS (July-October 2013)– Completion of ATLAS ARRA funded upgrade and installation of new source at

CARIBU (September-October 2013)– Start of GRETINA campaign at ATLAS (October 2013)

Preparation for GRETINA campaign at ATLAS

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ATLAS next few years running plan FY2012 ( 5100 + 800 hrs):

– CARIBU started (1542 hrs) move to stronger Cf source– ATLAS running (6140 hrs) + modifications to prepare RFQ installation

FY2013 ( 3100 + 1500 hrs):– Fall PAC: accepted experiments for ATLAS and low-energy and reaccelerated CARIBU beams– Fall RFQ installation ATLAS running tandem beams, CARIBU running low-energy with “1Ci source”– Winter/Spring: ATLAS + low-energy and reaccelerated CARIBU beams available– Spring PAC: accepting GRETINA experiments + all other ATLAS/CARIBU experiments– Summer booster reconfiguration low-energy CARIBU beams, no ATLAS beams, GRETINA arrives

FY2014 ( 5500 + 1500 hrs):– GRETINA + CARIBU/ATLAS beams, low-energy CARIBU beams– Deep-inelastic production along N=126 for CPT/X-array, move tandem out, new CARIBU source

FY2015 (5500 + 1500 hrs):– Fall EBIS installation Low-energy CARIBU beams, ATLAS beams, GRETINA leaves– Winter/Spring/Summer AGFA installation, large CARIBU experimental area available, all beams

available

( 6140 + 1542 hrs)

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Status ATLAS is preparing for the GRETINA campaign

– ARRA funded upgrade being completed by Oct 2013– Ongoing preparation for GRETINA

• In “stand alone” mode on APEX beamline• In front of FMA

– New stronger 252Cf source requested for the fall– Running a number of CARIBU reaccelerated beam experiments this spring

Need input from the community– What experiments do you want to be able to do with GRETINA at ATLAS?

• Are the two locations the right ones? Are they enough? Are they both needed?• What auxiliary detectors need to be accommodated?

– Should we setup campaigns?– What information do we need to provide to users?– What experiments are best done with GRETINA, what experiments are best done with

Digital Gammasphere? – How do we handle the data?

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Gammasphere Digital GammasphereGammasphere World-leading -spectrometer 100 HPGe Compton suppressed In front of FMA or in stand-alone mode Ancillary detectors

– CHICO: Coulomb Excitation– HERCULES: Evaporation residues– MicroBall: charged particles– Neutron wall– Rotating target wheel: High intensity– Plungers: Lifetime studies– X-ray counters

~ 40% of beamtime at ATLAS

Digital upgrade Goal: Increase rates x 4-12 Digitize energy signals

Done … no loss in resolution, X4 gain in countrate capability

Use Gretina digitizers Digitize BGO shields Status: Ongoing Completion: 2013

Digital GS @ 40K/s and 1 s shaping is as good as

“Old” GS @10K/s and 10 s shaping

ATLAS/CARIBU Status

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