Experiments with Radioactive Beams at GSI and FAIR

Thomas Aumann

May 21st, 2010

10th INTERNATIONAL SPRING SEMINAR ON NUCLEAR PHYSICS

NEW QUESTS IN NUCLEAR STRUCTURE

VIETRI SUL MARE

* Modularized start version of FAIR

- NuSTAR science with modules 0 to 3

- What is missing

- Conclusion

* Physics program on the way to FAIR

Example: Quasifree scattering at R3B

Single-particle structure of nuclei an N-N correlations

FAIR Modularized Start Version

Cost: 1027 M€

Available: 1039 M€

104 M€

19 M€

Modules 4 and 5 will be implemented as additional funds become available!

FAIR Modularized Start Version

• Significant cost increases in civil construction and site development cost ( Germany pays additional 95 M€ for site specific costs)

• Modularized Start Version of FAIR A defined in White Paper Draft

– Module 0: Heavy-Ion Synchrotron SIS100

– Module 1: Experiment hall at SIS100 for beam diagnostics, HADES/CBM, APPA, and detector calibration.

– Module 2: Super-FRS for NUSTAR including all three branches and the energy buncher

– Module 3: Antiproton facility for PANDA (LINAC; target, CR, HESR) and CR also for NuSTAR

– Module 4: LEB cave, NESR storage ring for NUSTAR und APPA, FLAIR building, cave for APPA

– Module 5: RESR storage ring for a higher beam intensity for PANDA and parallel operation with NUSTAR

• Cost 0-1-2-3: 1.027 M€ (2005) using updated civil construction cost and cost book values (CB 5.0) for accelerators

• Accepted available funds amount to 1.039 M€ (2005)

– another 62 M€ not firm + 12 M€ from Saudi Arabia (new partner)

• Construction schedule foresees readiness for installation end 2016

Implementation Scenario for NuSTAR Experiments in Modules 0-3

R3B

DESPECat MF-4 ??

HISPECAt LEB focus??

MATS & LASPECbehind R3B ??

ILIMA in CR

NuSTAR Experiments Modules 0-3

ILIMA• Isochronous mode • shortest-lived nuclei• limited precision

R3B • full capability

DESPEC• full capability

HISPEC• full capability

MATS & LASPEC• full capability

Delays possible for • EXL in NESR (Module 4)• ILIMA in NESR (Module 4)• ELISe (FAIR B)

(+ building for energy buncher)

R3B:

reaction studies at the highest energies in complete kinematics

full R3B programme will be accessible (world-wide unique)

–few body correlations at and beyond the drip-lines in break-up reactions (halo nuclei, open quantum systems)

–dipole response below and above the particle threshold using Coulomb excitation and breakup (Pygmy response, neutron skins, neutron matter properties, EOS)

–Evolution of shell structure and single-particle occupancies using knock-out and quasi-free scattering experiments (tensor force, shell quenching)

–Nuclear dynamics in fission and the symmetry energy at supra-saturation density in fragmentation reactions (large scale collective motion EOS)

–Measurement of (gamma,n) reaction rates for r-process nuclei (origin of the heavy element)

NuSTAR science within Modules 0-1-2-3

NuSTAR science within Modules 0-1-2-3

DESPEC:

decay spectroscopy using gamma-ray and neutron spectroscopy following isomeric or beta-decay of very exotic nuclei

Experiments with production rates between 1000 per second and 1 per hour possible ( farthest reach towards the drip lines)

– Measurement of absolute Gamow Teller strength values

– Investigations of 100Sn and nuclei along/beyond the proton dripline

– Structure of nuclei in heavy r-process region

– Measurement of g-factors of isomeric states and half lives of very short

isomers

NuSTAR science within Modules 0-1-2-3

HISPEC:

• high resolution in-flight gamma-spectroscopy (HISPEC with AGATA)

– Probing the evolution of nuclear shell structure in very n-rich medium-heavy nuclei using Coulomb-excitation, knock-out, and secondary fragmentation

– Probing the evolution of nuclear collectivity far from stability using Coulomb-excitation, lifetime and g-factor measurements

NuSTAR science within Modules 0-1-2-3

MATS and LASPEC:

• precision masses, ground-state moments

• short-lived nuclei and refractory elements not available with ISOL

• using ion-traps and laser spectroscopy after gas-stopping cell

NuSTAR science within Modules 0-1-2-3

ILIMA in CR:

• direct mass measurements of nuclei with half-lives in the millisecond region (most exotic, r-process)

• half-life experiments on highly-charged exotic ions

• studies of long-lived isomeric states.

Highlight:

Half-lives and masses of r-process nuclei responsible for the A~195 abundance mass peak

What is missing?

NESR

ILIMA:• precise masses and half-lives of many nuclei• unique decay modes

ELISe:Elastic and inelastic electron scattering(charge distributions, giant resonances)

EXL:Elastic scattering and low-q reactions(matter distributions, monople resonances, capture reactions, trnasfer, knock-out)

Experiments with stored electron cooled ion beams• World-wide unique• Conceptionaly new

AIC:Antiproton anihilation on nuclear surface(neutron skin thickness)

Conclusions

• Modules 0-1-2-3 of FAIR will allow for unique, exciting, and world-unique experiments

• Modularized FAIR start version is an essential step towards establishing the FAIR GmbH

• However: NuSTAR experimental programme will bring to fruition only a fraction of its full potential Need for NESR with world-wide unique experimental Need RESR for availability of parallel beams at FAIR Need SIS300 for full multi-user capabilities and maximum efficiency of FAIR

facility We need to continue to work towards the full FAIR facility!!

Continue to work on TDRs for NuSTAR experiments Continue a vigorous program at GSI FRS and ESR

Deviation from the independent-particle picture:

Correlations: Configuration mixing,

Coupling to collective phonons

Short-range correlations → high momenta

→ reduced single-particle strength

(occupations, spectroscopic factors)

The nucleus: single-particle motion in a mean field ?

Ingo Sick

Spectroscopic factors for neutron-proton asymmetric nuclei

Figure from Alexandra Gade, Phys. Rev. C 77, 044306 (2008)

Comparison e- induced knockout and

knockout in inverse kinematics with light target (Be)

Spectroscopic factors for neutron-proton asymmetric nuclei

weakly bound nucleons

Figure from Alexandra Gade, Phys. Rev. C 77, 044306 (2008)

Spectroscopic factors for neutron-proton asymmetric nuclei

strongly bound nucleons

?

Origin unclear

isospin dependence of correlations ?

Figure from Alexandra Gade, Phys. Rev. C 77, 044306 (2008)

weakly bound nucleons

Correlations in asymmetric nuclei and nuclear matter

Subedi et al.

protons

neutrons

ρ = 0.32 fm−3

ρ = 0.16 fm−3

Electron-induced knockout (JLab)

Sensitivity of Coulomb and nuclear breakup

Reaction probabilities

Coulomb breakup

Overlap with continuum wave function

Halo-Neutron Densities

Sensitivity to the tail of the wave function only

Alternative approach: quasi-free scattering: (p,2p), (p,pn) etc. at LAND and R3B

or (e,e'p) at the e-A collider at FAIR

Nuclear breakup

Future: Quasi-free scattering in inverse kinematics

• kinematical complete measurement of

(p,pn), (p,2p), (p,pd), (p,a), .... reactions

• redundant experimental information:

kinematical reconstruction from proton momenta

plus gamma rays, recoil momentum, invariant mass

• sensitivity not limited to surface

→ spectral functions

→ knockout from deeply bound states

• cluster knockout reactions

Measurement of proton recoils after knockout reactions with a CH2 target

x, Eproton

CsI, NaI

Si, stripCH2 target

projectile Z,AB

n,p, ...

Experimental Setup: LAND@Cave C

Beam

Target

• box of DSSDs for proton tracking• polar angle coverage ≈ 15°≤ ≤ 80°• resolution: x ~ 100 m; E ~ 50 keV• range: 100 keV < E < 14 MeV

• Crystal Ball detector • 162 20cm long NaI(Tl) crystals• additional low gain readout of forward 64 crystals • 4 gammas • 2 light particles

“New” Target Recoil Detector for Quasifree Scattering

Experimental Setup: LAND@Cave C

Beam

Target

• box of DSSDs for proton tracking• polar angle coverage ≈ 15°≤ ≤ 80°• resolution: x ~ 100 m; E ~ 50 keV• range: 100 keV < E < 14 MeV

• Crystal Ball detector • 162 20cm long NaI(Tl) crystals• additional low gain readout of forward 64 crystals • 4 gammas • 2 light particles

“New” Target Recoil Detector for Quasifree Scattering

Quasifree Scattering with Exotic Nuclei:17Ne(p,2p)15O+p The two-proton Halo (?) nucleus 17Ne

Nucleus of interest Excited Fragment

A

A-1

Free Target Proton

Recoil q

Photon(s)

Bound Proton

Separation Energy

0121 TTTTE AS

Internal Momentum

0211 ppppq A

q

p,n,d,t,...

Evaporation

0

1

2

Scattered Protons:

• opposite angles• opening angle 90°

Pilot experiments with 12C, 17Ne and Ni isotopes already performed at the LAND-R3B setup are under analysis …

Angular Correlations measured with Si-strip detectors for 17Ne(p,2p)15O+p

~180°, ~83° (sim. as for free pp scattering)

Gamma Spectrum in Coincidence with 12C(p,2p)11B Reaction Channel

M. Yosoi, PhD Thesis, 2003, Kyoto University

preliminary

Eγ(MeV)

Cou

nts

inverse kinematics

gamma spectrum after p knockout

s proton knockout

energy spectrum from invariant mass analysis

V. Panin et al.

Quasi-free cluster knockout

L. Chulkov et al., NPA 759(2005) 43

6He + p → + p' + XMomentum distribution

Experiment S174: Proton elastic scattering (P. Egelhof et al.)

Spectroscopic factors:

neutron: 1.7(2)

alpha: 0.8(1)