The Science of RIA

Brad Sherrill Why build a high-power, heavy-ion LINAC?

• Introduction

• The intellectual challenges addressed by RIA (Nuclei, Chemical History of the Universe, Fundamental Symmetries)

• Production of rare isotopes – options and considerations

• What does SRF technology and the RIA concept make possible?

• Summary

LINAC 2004 We don’t know nuclei that well – Binding Energies

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50 60 70 80 90 100 110 120 130 140 G. Bollen N (Z = 55) LINAC 2004 An Example of a Nuclear Halo

A scaled cartoon 1 fm

Halo Nucleus Normal Nucleus

Two effects : QM penetration (halo) and a difference in

proton and neutron Fermi levels (skins) LINAC 2004 NRC Report: Connecting Quarks to the Cosmos

Eleven Science Questions for the New Century (2003) – National Academy Study, M. Turner Chair — What is dark matter? — What is the nature of the dark energy? — How did the Universe begin? — Did Einstein have the last word on gravity? — What are the masses of the neutrinos and how have they shaped the evolution of the universe? — How do cosmic accelerators work and what are they accelerating? — Are protons unstable? — Are there new states of matter at exceedingly high density and temperature? — Are there additional space-time dimensions? 9How were the heavy elements from iron to uranium made? — Is a new theory of matter and light needed at the highest energies? NEW: US Interagency Task Force stated that Underground Lab, RIA, RHIC II are needed to meet these goals. http://www.ostp.gov/

LINAC 2004 Rapid Neutron Capture Process (r-process)

How were the heavy elements from iron to uranium made? Two possibilities (there are others):

Woosley … Thieleman …

LINAC 2004 Importance of Nuclear Physics in the r-process

In r-process model calculations nuclear shell structure is important.

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10-4 100 120 140 160 180 200 220 A Dobaczewski, Nazarewicz, Kratz, …

Question:Question: Is Is this this difference difference due due to to shell shell quenching quenching for for neutron-richneutron-rich nuclei, nuclei, or or a a problem problem with with astrophysical astrophysical model? model? LINAC 2004 Possibilities to study r-process nuclei

Needed Data for r-process nuclei: 0 5 s 2 e •Masses c n • Decay properties a • Level structure bund • n capture rates (indirectly) a 0 0 100 2 98 ss 96 e 94 c 92 o 90 88 pr 86 84 188 190 - 186 r 82 80 78 184 180 182 76 178 0 176 5 74 164 166 168 170 172 174 1 72 162 70 160 68 158 66 156 154 64 152 150 62 140 142 144 146 148 1 1 60 138 134 136 0 58 130 132 0 0 128 1 56 0 54 126 1 -1 124 52 122 120 0 50 116 118 1 -2 48 0 112 114 110 0 3 0 1 46 - 108 1 106 44 0 104 100 102 42 1 98 96 40 92 94 N=126 38 88 90 86 36 84 82 34 80 78 32 74 76 30 72 70 28 66 68 64 26 62 N=82 28 60 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 LINAC 2004 Summary of the scientific justification for JWST

• What is the shape of the Universe? • How do galaxies evolve? • How do stars and planetary systems form and interact? • How did the Universe build up it present elemental/chemical composition? James Webb Space Telescope NASA/EESC/CSA • What is dark matter?

http://ngst.gsfc.nasa.gov/science/ScienceGoals.htm LINAC 2004 The Active Universe- Gamma Ray Astronomy

M.Wiescher

1 MeV-30 MeV γ-Radiation in Galactic Survey (26Al Half life: 700,0000 years)

44Ti in Supernova Cas-A Location 1.157 MeV γ-radiation (Half life: 60 years) LINAC 2004 Observation of 26Al Demonstrates Nucleosynthesis

N. Prantzos, Astonomy & Astro 420 (2004) The observation indicates 2 solar masses of 26Al produced per My (1.5x1042 atoms/s). How? • Type II Supernovae 60 26 ‰ Fe/ Al ratio is a problem

‰ measured by RHESSI to be 0.16 (predicted >0.4) 59 59 ‰ Fe(n,γ) is critical but Fe is radioactive • Novae • Wolf-Rayet Stars Needed: Better observations and better nucleosynthesis calculations

LINAC 2004 Rare Isotopes and Fundamental Symmetries

QWeak An example of the E158 so called running ? of fundamental constants.

Prediction of the Standard Electro- Weak Theory

G. Sprouce

Rare-isotope facilities provide a credible path to necessary improvements on parity non-conservation in atoms.

LINAC 2004 Radioactive Beam Production Mechanisms

• Projectile Fragmentation/Fission beam Fragment Separator Driver Accelerator beam target Beams used without stopping

Post Acceleration Gas cell catcher/ion source beam • Target Spallation and fragmentation Target/Ion Source target LINAC Post Acceleration • Neutron induced fission (2-step target) Neutrons LINAC Post Acceleration LINAC 2004 Optimum Mechanism for each Isotope

Optimum production method for low-energy beams Standard ISOL technique Two-step fission In-flight fission + gas cell Fragmentation + gas cell

Most facilities use only one production method.

LINAC 2004 Requirements

• Production cross sections for the interesting nuclei at the limits of stability are low (fb), thus as high as possible primary beam intensities are needed. Uranium Luminosity = 1 pb-1s-1 • There is no overall optimum production mechanism – we would like have access to all. • Secondary beams from 60 kV to 1 GeV/u are needed to extract the science. Solution: SRF technology – Primary, high intensity, linear accelerator and efficient secondary accelerator

LINAC 2004 Rare Isotope Accelerator - RIA

• Efficient acceleration of elements up to uranium at 2.4x1013/s and E > 400 MeV/nucleon. Beam power of 400 kW. • Possibility to optimize the production method for a given nuclide. • Secondary beams at energies from 60 kV to 400 MeV/u .

Schematic of the RIA Concept

LINAC 2004 Artist’s Conception of RIA at ANL

LINAC 2004 RIA SRF Cavities – All Tested by 2003

Legnaro MSU ßopt=0.49 805 MHz MSU/JLAB

ßopt=0.63 805 MHz MSU SNS

ßopt=0.83 805 MHz SNS

ßopt=0.041 ßopt=0.085 ßopt=0.285 80.5 MHz 80.5 MHz 322 MHz LINAC 2004 β=0.49 Cryomodule Prototype (THP70)

NSCL LINAC 2004 Tests of Nuclear Models – Binding Energies

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50 60 70 80 90 100 110 120 130 140 G. Bollen N (Z = 55) 100/d – 400 kW HI LINAC 2004 Changes in nuclear shell structure for n-rich nuclei

J. Dobaczewski and W. The nuclear mean field Nazarewicz 126126 p1/2 h f5/2 potential is dependent 9/2 3p i f5/2 13/2 N=5 2f p3/2 on the number and type p1/2 h9/2 p3/2 f f7/2 of nucleons present in 7/2 1h h 8282 11/ d the nucleus. 2 3/2 g7/2 3s h11/2 s1/2 d3/2 N=4 2d g7/2 s1/2 d5/2 Shell structure for very d5/2 1g 5050 asymmetric nuclear g9/2 g9/2 matter will be different nono ssppinin veryvery didiffusffusee orbitorbit aroundaround tthhee than for normal N=Z ssuurfacerface harmonicharmonic exoticexotic nuclei/nuclei/ valleyvalley ofof nuclear material. neneutronutron dripdrip lineline oscillatooscillatorr hypernucleihypernuclei ββ-stability-stability

Phil. Trans. R. Soc. Lond. A 356, 2007 (1998)

LINAC 2004 Weakening of Shell Structure in Exotic Nuclei

PROTON NUMBER 68 62 56 50 44 38 N=80 J. Dobaczewski and 24 N=82 W. Nazarewicz

) 20 N=84 N=86 e ne eV ne i n

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pl Phil. Trans. R. Soc. Lond. p r ri ( ri 12 ri A 356, 2007 (1998) nd n nd nd nd 2 ro o ro o t t

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1.2 1.5 1.8 2.1 2.4 N / Z RIA .01/s limit LINAC 2004 Extreme Halos Reachable at RIA

Example: 42Mg Theory BA Brown 10 0.50 42Mg - 40Mg Difference 0.40 Neutron 0.30 Proton 0.20 x density

2 0.10

1 r π

4 0.00

-0.10 0 5 10 15 20 Radius

0.1 x density (nucleons/fm) 2

r Neutron π 4 Proton

0.01 05101520 Radius (fm) Science: Pairing in low-density material - Interaction with continuum states - Efimov States - Reactions LINAC 2004 Nuclear Science needs to study n/p degree of freedom

Approach

Very hard

Necessary to know what effective RIA-Fair-ISAC interactions operate in nuclei

LINAC 2004 Nuclear Microphysics of the Universe X-ray burst (RXTE) RIA intensities (nuc/s) 4U1728-34 > 1012 102 331 1010 10-2

) z 106 10-6

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10 20 30 Wavelength (Α) Supernova (HST) EC

protons crust processes neutrons E0102-72.3

Big Bang (WMAP) LINAC 2004 What is Unique about the RIA linac?

• Possibility to optimize the production method • Multiple charge state acceleration – 400kW beam power – highest efficiency for rare stable isotope acceleration, e.g., 48Ca, 124Sn (this can yield gains of 100 to 1000) • Intense Uranium Beams at 400 MeV/u and 400 kW • Liquid Li production target + fragment separator + gas catcher system – Ability to handle 400 kW beams – Precision reaccelerated beams without chemical or half-life dependence – Same setup for all elements with short development times • 2.1 GeV 3He ( 1 GeV protons) at 400 kW intensity for ISOL targets LINAC 2004 Summary

• The science of rare isotope facilities: • Nature of nucleonic matter – nuclei with special features (e.g. 78Ni) and production of nuclei with sufficiently large N/Z ratios (1.5 now to 2.0) • Chemical evolution of the Universe (origin of the elements) – produce nuclei relevant to the various astrophysical processes • Test of symmetries – requires the production of Radon and Francium over a range of isotopes • There a number of approaches. The two main categories are in- flight and ISOL • RIA uses a superconducting LINAC to provide the most efficient acceleration of primary beams, access to all production mechanisms and a wide range of secondary beam energies.

LINAC 2004 At the moment we are limited in our view of the atomic nucleus

Some Basic Nuclear Property

LINAC 2004 RIA Will Greatly Expand Our Horizons

Thank you LINAC technology.

LINAC 2004 The Chart of the Nuclides

Heavy Elements?

Known Nuclei Fission Limit?

Proton Drip Line?

Neutron Drip Line?

LINAC 2004 Advantages/Disadvantages of ISOL/In-Flight

In-flight: •• PProvidesrovides beamsbeams withwith energyenergy nearnear thatthat ofof thethe primaryprimary beambeam GSI –– FForor experimentsexperiments thatthat useuse highhigh energyenergy reactionreaction mechanismsmechanisms RIKEN –– TThickhick secondarysecondary targets,targets, kinematickinematic focusingfocusing NSCL GANIL –– IIndividualndividual ionsions cancan bebe identifiedidentified RIA •• EEfficient,fficient, FastFast (100(100 ns),ns), chemicallychemically independentindependent separatiseparationon •• CCaptureapture inin storagestorage riringsngs •• PProductionroduction targettarget isis relativelyrelatively simplesimple ISOL: HRIBF •• GGoodood BeamBeam qualityquality ((ππ mm-mrmm-mr vvs.s. 10s10s ππ mm-mrmm-mr ttransverse)ransverse) ISAC •• SSmallmall beambeam energyenergy spreadspread forfor fusifusionon studiesstudies SPIRAL • Can use chemistry to limit the elements released ISOLDE • Can use chemistry to limit the elements released EURISOL •• 22-step-step targetstargets provideprovide aa pathpath toto 400kW400kW targetstargets RIA •• HHighigh beambeam intensityintensity leadsleads toto 100x100x gaingain inin secondarysecondary ionsions

LINAC 2004 Summary of the key science requirements

• Production of benchmark nuclei: traditional closed shell nuclei 100Sn, 132Sn, 78Ni and new magic nuclei 60Ca • Nuclei with large neutron skins (most extreme changes in structure) • Production of very weakly bound nuclei such as 42Mg. Nuclei along the neutron drip line as heavy as possible. • Nuclei along the r-process path. Particularly important are the N=126 closed shell nuclei. • Sufficient quantities of N=Z nuclei below 100Sn to study proton capture reactions (often this requires 1010 ions/s) – novae, X-ray burst, X-ray sources, … • Radon and Francium isotopes at (1011/s) over a wide range

LINAC 2004 Tests of the Standard Model

Symmetry studies in Francium 126 Specific nuclei offer new opportunities for 82 Weak interaction precision tests of: studies in N=Z nuclei • CP and P EDM search 50 in Radium violation 82 • Unitarity of 28 CKM matrix terra incognita proton number Z proton number 20 50 • Physics beyond

8 28 VA 2 20 2 •sinΘW at low q 2 8 neutron number N

LINAC 2004 Availability of Neutron Skin Nuclei

100/s 10/day RIA Rates Excess of Neutron Radius

R = Rn –Rp Mizutori et al. PRC 61(00) 044326

Two problems: (1) Make them (2) Study them LINAC 2004 Systematic Studies are Essential for Nuclear Theory

S. Pieper, R. Wiringa, et al. LINAC 2004 Difference in Fermi Levels Results in Skins*

* the neutron EOS also plays a role and the size of the neutron skin is related to the volume symmetry energy.

LINAC 2004