Precision Experiments with Exotic Nuclei at Relativistic Energies

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Precision Experiments with Exotic Nuclei at Relativistic Energies. Hans Geissel, GSI and JLU Giessen. Introduction Precision Measurements: a) with the Magnetic Spectrometer (FRS) b) with the Storage Ring (ESR) Super-FRS, the Next-generation Facility.
Precision Experiments with Exotic Nuclei at Relativistic Energies Hans Geissel, GSI and JLU Giessen
  • Introduction
  • Precision Measurements:
  • a) with the Magnetic Spectrometer (FRS) b) with the Storage Ring (ESR)
  • Super-FRS, the Next-generation Facility
  • ISOL and In-FLight Facilities in EuropeBjörn Jonson (2000)Kinematics of Projectile Fragmentation and Fission Secondary Nuclear Beam Facility at GSIFRS: In-flight Separator & High-Resolution Spectrometer31SIS2
  • Decay Spectroscopy,
  • High-resolution momentum measurements
  • Masses, Lifetimes, Direct Reactions,
  • Isomeric Beams
  • Reactions Studies (Complete Kinematics)
  • Advantages of Projectile Fragmentationand – Fission at Relativistic Energies (0.5-1GeV/u)High luminosity Thick targets ( 5 g/cm2 )In -flight separation Time limit 200 ns  T1/2, q=Z Single-atom spectroscopy (pb range) Mono-isotopic beams of all elements Cocktail beams, optionalKinematic focusing Injection into storage rings Full solid angle coverage Complete kinematics reaction experimentsSimple reaction Sudden approachmechanism Glauber model G. MünzenbergAnn. Rev. Nucl. Part. Sc. 45The FRS as an Energy-Loss SpectrometerIncident energy shifts do not show upat the final focusE01,E02,E03E01,E02,E03TargetE1E2E3The Projectile Fragment Separator FRSW. Schwab et al.Z. Phys. A350, 2838B + C 7Be1500 MeV/u12C7BeNuclear Structure via Precise Momentum Measurements at Relativistic Energies Knockout Reactions lead to Discovery of Halo-Nuclei12C + Be 8BP.G. Hansen, B. JonsonEur. Phys. Lett. 4 (1987) 409I. Tanihata et al., Phys. Rev. Lett. 55 (1985) 26761000 MeV/u12C8BTarget8B 7gBe87%13%Spectroscopic factors D. Cortina-Gil et al. Phys. Lett. B529 (2002) 36Halo Studies: Momentum Measurements in Coincidence with Gamma Ray Emission7Be*.GSIand MSUDataP.G. Hansen2004Experimental FacilitiesMonoisotopic Fragment BeamsStored in the ESRSchottky Mass SpectrometryIsochronous Mass SpectrometryPrecision Mass Measurements in the ESRNew and Reference Masses in the same SpectrumHigh Resolution and Sensitivityaccuracy: 30 keVSchottky Mass Spectrometry950 MeV/u 209Bi + Be  Projectile Fragmentsnoise power density a.u.frequency [Hz]Decay of Single Atoms Stored in the ESRYu. Litvinov Results compared with Theory srms = 650 keVS. Goriely et al.PR C66 2002Predictive Power of the Relativistic Mean Field Model (RMF)G.A. Lalazissis et al. ADNDT 71 (1999)1even-even nuclei, NL3, srms= 2.6 MeVsrms = 3831 keVYu. Litvinov207Tl81+207Tl81+207mTl81+207Pb81+207mTl81+207Pb81+Lifetime Measurements of Short-lived Nuclei Applying Stochastic and Electronic CoolingBound-state Beta-Decay of 207Tl81+Lifetime Measurements of 207mTl
  • Shorter cooling time allowed to see isomeric state of 207Tl (E* = 1348 keV, half-life of 1.33 ± 0.11 s for neutral atom)
  • Measured half-life of bare nuclei, transformed in the rest frame:
  • Half-life Measurements of 207Tl81+ Bound-state Beta DecayD. Boutin, PhD8BKey-Results from FRS ExperimentsAdvantages of High EnergiesNP A665 (2000) 221New Fission StudiesNP A667 (2000) 75New Mass MeasurementsPR C65 (2002)064603EPJ A14 (2002) 279100Sn2-p RadioactivityPRL 86 (2001) 5442Bound-state b--decayGiant DipoleResonanceto be publishedPionic AtomsPRL 88 (2002) 122301NP A720 (2003) 3New Fission Fragments78NiPL B 444 (1998) 32Halo NucleiShells far off Stability 11LiSkin NucleiPRL 91 (2003) 162504FAIR: The International Accelerator Facilityfor Beams of Ions and AntiprotonsNuSTAR FacilityLayout of the Super-FRSDesign ParametersThe main technical challengesare at the Pre-SeparatorExperiments withLow-energy andStopped beams Laser spectroscopy Decay spectroscopy Ion and atom trapsThe high-energy branch of the Super-FRS:Reactions with Relativistic Radioactive Beams The setup
  • Goals:
  • identification, tracking and momentum measurement, Dp/p ~10-4
  • exclusive measurement of the final state:
  • - coincident measurement of neutrons, protons, gamma-rays, light recoil particles
  • applicable to a wide class of reactions
  • CRNESRRESRFutureSuper-FRSELISeGas targetILIMAEXLWhy light-ion scattering ? - select specific spin-isospin transitions ! - transition form factor sensitive to multipolarity ! - low nuclear absorption !Why in a storage ring ? - information on form factor at low momentum transfer  very thin (windowless) target  gain luminosity !beam cooling beam recirculation (NESR ~ 106 s-1)  high resolution (recoil kinematics)negligible straggling effects in target and electron cooling EXotic nuclei studied in Light-ion induced reactions at the NESR storage ring (EXL)Elastic (p,p) , (a,a) …Inelastic (p,p’), (a,a’) ...Transfer (d,p), (p,t) …Charge exchange (3He,t), …Quasi-free (p,2p), (p, pa) … ~ 0.1 …. 0.8 GeV/uKey issues: matter distribution (halo,skin) shell structure nn correlations, cluster new collective modes r-, rp-process (GT, capture..) in-medium interactions inasymmetric and low-density matterSummary
  • Studies of exotic nuclei will contribute significantly to the basic knowledge of matter.
  • Precision experiments with stored exotic nuclei open up a new field for nuclear structure physics and astro-physics.
  • The next–generation facility will present unique conditions for research and education.
  • There are many technical challenges inviting especially also the next-generation scientists.
  • Let us move to the common future of NuSTAR Physics at FAIR!
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