Argonne National Laboratory is a U.S. Department of Energy laboratory managed by UChicago Argonne, LLC.

ATLAS OVERVIEW AND STATUS

8TH AUGUST 2019

GUY SAVARDDirector of ATLAS

ATLAS/CARIBU FACILITY

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§ Stable beams at high intensity and energy up to 10-20 MeV/u§ Light in-flight radioactive beams with RAISOR

– 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 5000-6500 hrs/yr (+ 2000 hrs/yr CARIBU stand alone) at about 93% efficiency

– Common PAC for ATLAS and CARIBU– 200-400 “single users” per year performing experiments at ATLAS

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Soon: N=12

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facto

ry

LIGHT IN-FLIGHT RADIOACTIVE BEAMS WITH RAISORUncertainties up to one order of magnitudeCollective Nuclei

Pairing in NucleiSingle-Particle StructureNuclear ReactionsNuclear AstrophysicsFundamental Symmetries

Multi-Purpose● Increased intensities, purities, & reach for

ATLAS in-flight beams● Momentum selection (magnetic chicane)

followed by velocity selection (RF sweeper) àA/q selection

● Accessibility to more experimental areas

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IN FLIGHT BEAMS PRODUCED WITH RAISOR

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Eight beams and six measurements§ 19O – commissioning measurement at ATSCAT§ 16C – Fusion cross sections @ MUSIC [LSU

(Hood) / ANL (Santiago-Gonzalez)]§ 30P – 30P(d,p) with GODDESS [ORNL (Pain)]§ 12B – 12B(t,p) @ HELIOS [UCONN (Wuosmaa)]§ 8Li – 8Li(t,p) @ HELIOS [UCONN (Wuosmaa)]§ 31Si – 31Si(d,p) @ HELIOS [LSU/ANL (Wilson)]§ 22Mg – Development of 22Mg @ MUSIC [ANL

(Avila)]§ 29Al – 29Al(d,p) @ HELIOS [Univ. Manchester

(Sharpe)]

IN FLIGHT BEAMS PRODUCED TO VARIOUS TARGET LOCATIONS

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§ 19O – commissioning measurement at ATSCAT§ 16C – Fusion cross sections @ MUSIC [LSU

(Hood) / ANL (Santiago-Gonzalez)]§ 30P – 30P(d,p) with GODDESS [ORNL (Pain)]§ 12B – 12B(t,p) @ HELIOS [UCONN (Wuosmaa)]§ 8Li – 8Li(t,p) @ HELIOS [UCONN (Wuosmaa)]§ 31Si – 31Si(d,p) @ HELIOS [LSU/ANL (Wilson)]§ 22Mg – Development of 22Mg @ MUSIC [ANL

(Avila)]§ 29Al – 29Al(d,p) @ HELIOS [Univ. Manchester

(Sharpe)]

Eight beams and six measurements

12B

8Li 31Si

29Al

19O16C 22Mg

22Mg

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 and MR-TOF

• 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

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EBIS CHARGE BREEDER AT ATLAS

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Recent experiments with reaccelerated CARIBU beams using EBIS : Coulomb excitation of 104,106Mo, 110Ru, 100Zr

CARIBU + EBIS charge breeder + GRETINA + CHICO2

Similar improvement for 110Ru, new data allows to determine gD.T. Doherty et al., data analysis in progress

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§ Recently delivered radioactive ion beams (RIB) and purities- A/Q=106/20: 94% RIB (106Mo and 106Tc)- A/Q=134/28: 99% RIB (134Te and 134I)- A/Q=138/25: 96% RIB (138I and 138Xe)- A/Q=143/28: 96% RIB (143Ba and 143La)- A/Q=145/28: 83% RIB (145Ba and 145La)- A/Q=146/27: 99% RIB (146Ba and 146La)

Reaccelerated beams (EBIS)

Low-energy beams§ Using MRTOF: single isotope purity is possible (depends on

the mass isotopic mass differences)§ Fast HV switches (BNG, 0.1-0.2 µs wide) removes

contaminants§ Example: A/Q=150/2+ (mixture of Ce,Pr,La)§ MRTOF → higher purity, less intensity (some trade-offs… used

all the time for mass measurements, becoming more frequent for decay spectroscopy)

PrCe

LaStable contaminants

BEAM PURITY

CARIBU BEAMS DELIVERED TO EXPERIMENTS SO FAR

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All of these beams now available in the new low-background low-energy area (Area 1)

ECR3 NOW OPERATING

§ ECR2 responsible for majority of beams

§ ECR3 is a permanent magnet source

originally developed under SBIR

§ Benefits to ATLAS

– Enable development of new beams

– Shorter downtime between beam

setups

– Increase scheduling flexibility

– Radioactive (14C, 225Ra) and

hazardous (Be) material source

§ Commissioning being completed,

preparing paperwork for authorization to

extract 14C beam

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ATLAS BEAMS§ Stable beams (protons to Uranium)

– up to 10 pµA, limited by ion source performance and radiation safety– Pulse separation of 82 ns or n X 82 ns with n=1, 2, 3, …– Pulse timing down to ~100 ps– Energy range from ~ 0.5 MeV/u up to 10-20 MeV/u depending on mass

§ CARIBU beams have similar properties …. but much lower intensity– All species, even the most refractory, are extracted efficiently

§ In-flight radioactive beams (RAISOR): all light species, close to stability, but some compromises between beam properties, intensity and purity

Unique capabilities worldwide + coupled to unique instruments

A few other facilities worldwide can produce these beams but none have the ATLAS experimental equipment suite (e.g. HELIOS).

Most of the CARIBU beams (species and energy) are not available anywhere else.

LAYOUT OF ATLAS FACILITY

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Experimental area 1

Old CARIBU exp area

Experimental areas 3 - 4

Experimental area 2

CARIBU beams 3-400 keV

ATLAS + CARIBU + RAISOR beams 2-15 MeV/u

ATLAS + CARIBU beams 2-7 MeV/u

DISTRIBUTION OF EXPERIMENTAL EQUIPMENT

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CPT mass spectrometer

X-array

Ion Trap

Ion Source

90o Deflector

Laser Beam

Laser Lab

Si-array (Ludwig) and Enge spectrometer

AGFA

Beta decay Paul trap

+ outside instruments: GRETINA, CHICO-II, HERCULES, GODDESS, VANDLE, MTAS, SUN …

HELIOS spectrometer

Digital Gammasphere

FMA

AGFA

GAMMASPHERE/GRETINA

Laser spectroscopy

MUSIC

ATLAS FACILITY PERFORMANCE

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Operating Statistics Machine Operation ATLAS

FY2013 Booster

FY2014 Upgrade

FY2015

FY2016 FY2017

FY2018

FY2019 (proj.)

Research Hours (on Target) 3345 2801 5559 4953 4318 4497 5500 Beam Study Hours 152 228 56 352 310 255 300 Tuning/Restore 607 786 671 855 840 995 600 Total Delivered Hours 4104 3815 6286 6160 5468 5747 6400 Unscheduled failure hours 487 248 479 433 452 612 400 Total Scheduled Hours 4591 4063 6765 6593 5920 6359 6800 Availability (%) 89.4 93.9 92.9 94.4 92.4 90.4 94.1 CARIBU Research Hours 1980 2131 1884 2820 2260 652 2000 Beam Study Hours 340 172 376 464 204 240 300 Total Delivered Hours 2320 2303 2260 3284 2464 892 2300

§ FY18-19: Install existing permanent magnet ECR ion source to provide more flexibility and development time for ion sources

§ FY18: reduced CARIBU low-energy hours due to installation of new source and focus on developing CARIBU reaccelerated beams with EBIS

§ FY19: aiming at 6400 hours delivered despite completion of RAISOR installation § FY20-FY24: targeting 6200-6400 depending on facility improvements/scheduling

The AGFA gas filled spectrometer has now been commissioned and used for first experiments

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Gammasphere STATUS• Developed new system to move GAMMASPHERE between FMA and AGFA

beamlines.

• Changed bases on BGO detectors (side shields and back plugs) – 1540 bases.

• Replaced all LN Manifold valves.

• Repair of HPGe detectors.• Only 75-80 detectors are in array• After shut down, large percentage not operating properly• Various problems, pre-amps, HV filters, FET, transistor reset, crystal• Since June 1st, hired electronics technician for diagnostics and repairs• Technician Partially funded by Army Research Lab @ $250k• Team: M. Oberling, E. Boron , P. Copp, J. Wu and M. P. Carpenter

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COMING SOON: N=126 FACTORY … MULTI-NUCLEON TRANSFER VERSUS FRAGMENTATION FOR NEUTRON-RICH HEAVY ISOTOPES

Fragmentation

MNT reactions(calculation)

MNT reactions(measurement)

Fragmentation

136Xe + 198Pt at 10 MeV/u (best multi-nucleon transfer (MNT) reaction)

Hirayama et al., EPJ Web Conferences 109,08001 (2016)

208Pb + 9Be at 1 GeV/u (best fragmentation reaction cross-sections for N = 126)

versus

Isotopes available, mass separated, at

> 1/s for mass measurements or

decay studies

N=126 and much more … slide from our users

PAC Statistics:• Trends persist, i.e., high number of proposals & oversubscription (factor 2-3)• Continue to operate with priority I & II modes to optimize efficiency of program• Introduced more backlog to allow additional needed flexibility in scheduling• Most recent PAC in March 2019: over 420 days of beamtime requested, only 167 days could be approved for priority 1 running

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PAC STATISTICS

ATLAS MULTI-USER UPGRADE§ EBIS beams represents 1-3% duty factor§ Combine pulsed EBIS beam with stable ECR beam

– Address high demand on facility– Enable long duration experiments– Maximize efficient accelerator usage

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t

Combine beams

Separate beams

EBIS pulse, ~1 ms @ 10Hz ECR stable beam, ~95 ms

4-7 MeV/u

4-15 MeV/u

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CARIBU: STATUS AND PATH FORWARD§ The annoying:

– cannot run in optimal conditions right now because of a cold leak in the gas catcher àwill open to fix the gas catcher in August-September (CARIBU down for ~ 5 weeks … no

impact on non-CARIBU running)

§ The bad … but we believe we have a solution:

– Source needs to be changed roughly every 3 years and it has proven very challenging to

obtain a good thin 252

Cf source

• The 1.7 Ci source, installed in May 2014, needed to be replaced in 2017

– Decayed to ~ 0.59 Ci + too thick (~11% release) à effectively 0.06 Ci

• R&D at ORNL and a 3-plate source configuration with a larger area developed at ANL

to try to resolve the thickness issue

• actual 252

Cf deposition however yielded irreproducible results

• First (side)plate was promising à 0.52 Ci with 40-50% release

• Next 3 attempts yielded no usable deposits

– Delays started to encroach on ATLAS schedule and we needed to move forward

• designed a modified holder to accept the one successful (side)plate

• installed at ANL in May 2018

Proposed solution: a neutron-generator-based source of fission fragments to obtain more reliable and higher intensity (goal is factor of 10 gain) access to fission products … implemented in two years instead

of replacing source

NEUTRON GENERATOR UPGRADE§ Replace 252Cf source by neutron-induced fission on actinide foils

– More reliable source of fission products– Operationally easier to maintain and operate– Higher fission yield feeding in the 132Sn region

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OR

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STATUS§ ATLAS is the DOE low-energy nuclear physics national user facility

– Running reliably and logging in a large number of operating hours– Accomplishing its current science goals– A coherent upgrade program to add accelerator and experimental capabilities

that build on each other to provide new capabilities to better address the community’s evolving science goals• Improving suite of experimental equipment

– HELIOS, digital Gammasphere and DSSD, X-array – AGFA, N=126 factory, laser lab, beta-delayed neutron trap

• Improving in-flight beams: RAISOR + ATLAS upgrade + new high power targets

• Improving background for decay work: CARIBU + MRTOF + new low-energy (+ neutron generator)

• Improving purity of reaccelerated beams: CARIBU + ATLAS upgrade+ EBIS charge breeder (+ neutron generator)

§ Providing unique capabilities to a broad user community and further increasing beamtime availability with multi-user upgrade

SUPPLEMENTARY MATERIAL

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• Spectroscopy of the heaviest isotopes

• Recoil and gamma efficiencies are now optimized, beam intensity limited by rate in germanium detectors … the main knob left is running longer

• Production of new neutron-rich isotopes of the heaviest elements

• Small cross-sections and large running time

• Detailed single-particle spectroscopy in the medium mass region

• Limited intensities

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NEED FOR AMUU: NEW OR CONTINUING STABLE BEAM PROGRAMS WITH VERY HIGH BEAMTIME REQUIREMENTS

RAISOR +HELIOS

Zagrebaev et al

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Looking at D-D (300 keV and 3 MeV) and p-7Li (3 MeV)NEUTRON-GENERATOR OPTION STUDIES

Simulations by Jeongseog Song

beam (d or p)

target (d or 7Li)

235U thin foil

gas catcher volume

132Sn

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NEUTRON GENERATOR OPTION STUDIES• Currently in contact with 3 companies:

• PHOENIX• Starfire• Ion Linac System

• All 3 have visited CARIBU and have been briefed on the requirements/constraints

• Working on optimizing geometries and cost estimates for partial or full system • accelerator only• accelerator+target• accelerator+target+thermalizer/shielding

• It appears that all options can meet our minimal goal of 10X more effective fissions than currently available with thick 252Cf source

• Draft proposal complete by end of next week; Director’s review in mid-August

• The Neutron-generator upgrade proposal (nuCARIBU) will be submitted to DOE by the end of September

OR

SCHEDULING: EXPERIMENTAL CAMPAIGNS AND IMPLEMENTATION OF UPGRADES§ ATLAS is moving towards longer schedules which are driven by:

– Campaigns with large community instruments (e.g. GRETINA)– Timely exploitation of new capabilities (e.g. AGFA and RAISOR)– Need to adapt schedule to minimize impact of maintenance or installation of

new equipment on running schedule

§ Efforts to increase flexibility are critical to maintain > 6000 hrs/yr delivered– e.g. the new ECR3 will allow for the installation of half of the AMUU hardware

while the facility is delivering beam

§ Broad lines of running schedule set within that framework:– FY19 Q1-Q3: focus on GRETINA and newly commissioned RAISOR– FY19 Q4-FY20 Q1: focus on AGFA+GS and HELIOS with downstream

detector array– FY20 Q2-Q3: focus on GS (moved to FMA) + AGFA experiments without GS– FY20 Q4-FY21 Q1: focus on HELIOS with upstream detector array– FY21 Q2-FY22 Q2: focus on GRETINA experiments at the FMA – …

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EXPERIMENT SCHEDULING

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§ Accelerated RIB beams, CARIBU and RAISOR, now budgeted for two startup days due to complexity

§ New RAISOR beams may get development time prior to experiment scheduling to demonstrate feasibility

§ Schedule Complexity– Typically published 2-4 months in

advance

§ User Liaison responsibilities led by D. Santiago-Gonzalez, with assistance from low energy research staff

C-12 3.1%H-1 3.8%

Li-6 13.0%

Ca-40 2.4%

Ni-58 7.5%

Ca-48 7.9%

Cs-133 1.4%Ba-142 0.3%

Ce-150 0.7%Pr-150 0.7%Ba-144 0.3%La-145 0.3%Ba-143 2.7%

Mo-106 2.7%

Mo-104 2.1%

Ru-110 2.1%

F-19 2.4%Fe-56 2.7%

Gd-160 2.7%Ge-76 1.7%

He-4 1.7%

O-16 0.3%

I-138 1.4%Xe-136 8.2%

Cs-142 1.0%O-16/Ar-40/Ne-20 1.0%

Mg-24 2.7%

Mg-26 2.1%

Mo-100 1.4%Ne-22 0.3%

Mo-92 0.3%Zr-92 0.3%

O-18 2.7%

Pb-208 5.1%

Zr-100 2.4%

Zn-70 2.7%

La-144 1.0%

O-18/O-19 4.5%

Beam Species for Fiscal Year 2018(percentage of beam hours delivered)

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38 unique speciesStableIn-flightEBIS/CARIBU

LAYOUT OF ATLAS FACILITY

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Experimental area 1

Old CARIBU exp area

Experimental areas 3 - 4

Experimental area 2

CARIBU beams 3-400 keV

ATLAS + CARIBU + RAISOR beams 2-15 MeV/u

ATLAS + CARIBU beams 2-7 MeV/u

109 MHz CRYOSTAT UPGRADE

§ 2009 Energy Upgrade cryomodule§ Accelerating gradient limited by VCX fast

tuner

Overview

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Cavity Voltage [MV]

(VCX limit)

Voltage [MV]

(NO VCX limit)

1 1.96 2.88

2 1.89 2.75

3 2.13 3.75

4 2.29 3.13

5 2.12 2.75

6 1.92 2.08

7 2.24 3.75

Total 14.55 21.1

4.5 m

109 MHz CRYOSTAT UPGRADE

§ Clean current resonators

§ Install additional resonator

§ New Digital LLRF

§ New power couplers

§ Drive resonators with new 4 kW solid

state amplifiers

Scope

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Status Voltage [MV]

Current (de-rate) 10-12

After cleaning 14.5

Additional resonator 16.5

Overcoming VCX limit 20

Cryostat accelerating gradient

109 MHz CRYOSTAT UPGRADE

§ Amplifiers on order from Rohde and Schwarz§ Digital LLRF

– Hardware fully developed by BNL– Framework to standardize facility– Increased reliability and maintainability

§ Resonator components formed, ready for machining then welding

§ Power couplers ready§ Installation planned at end of 2019

Status

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ATLAS RADIATION INTERLOCK SYSTEM(ARIS) UPGRADE

§ Developed in the ‘90s to monitor radiation levels and safeguard personnel from radiation hazards§ Allows access to areas with beam present when safe§ Limitations

– Difficult to expand further – functionality not optimal, especially for multi-user upgrade– Data accessibility– Designed to restrict beam along one path

§ ARIS upgrade goals– Modernize hardware and architecture– Upgrade software to meet facility needs– Prepare facility for Multi-User Upgrade

§ Benefits– Enable multiple beam paths– Improve access to system information– Save time configuring and recovering system– More customizable to fit changing ATLAS needs– Additional monitoring will minimize HP surveys

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Current exclusion areas for high radiation beam delivered to SPSIII