The Active Target for R 3 FAIR Peter Egelhof GSI Darmstadt, Germany ACTAR Workshop Bordeaux, France June 16 – June 18, 2008 FAIR

I. Introduction II. The First Generation Active Target IKAR at GSI III.Perspectives at the Future Facility FAIR IV. Experimental Conditions for an Active Target at FAIR V. Conclusions The Active Target for R 3 B at FAIR FAIR

I. Introduction future perspectives at FAIR:  explore new regions of the chart of nuclides and new phenomena  use new and powerful methods:  one speciality of RIB`s at FAIR: intermediate energies: MeV/u classical method of nuclear spectroscopy:  light ion induced direct reactions: (p,p), (p,p'), (d,p),...  to investigate exotic nuclei: inverse kinematics proton- detector beam of exotic nuclei A X 1 H ( A X, 1 H) A X 1 H - target past and present experiments:  light neutron-rich nuclei: skin, halo structures  only at external targets  new technologies: active targets LH 2 target

II. The First Generation Active Target IKAR at GSI 11 Li P 11 Li-beam from FRS (provided by PNPI St. Petersburg) detection principle: H 2 -target = detector for recoil protons operating conditions: H 2 -pressure:10 atm entrance window: 0.5 mm Berylium target thickness:30 mg/cm² (6 independent sections) beam rate:  10 4 /sec but: method limited to Z  6!

Detection Principle of IKAR 11 Li- projectile SS TRTR ZvZv RR z p 11 Li from pulse analysis: integral  recoil energy T R (  E FWHM  90 KeV) risetime  recoil angle  R (  FWHM  0.6°) Start  vertex point Z V (  z FWHM  110  m)

Investigation of Nuclear Matter Density Distributions of Halo Nuclei by Elastic Proton Scattering Experimental Setup: Active Target IKAR and Aladin Magnet target + recoil detector: IKAR  T R,,  R, Z V trajectory-reconstruction:PC 1-4 (Multiwire proportional chambers)   S beam identification:S 1-3, Veto (plastic scintillators)   E, TOF, trigger ALADIN-magnet discrimination of + position sensitive scintillator wall projectile breakup 

The IKAR Experimental Setup

Investigation of Nuclear Matter Density Distributions of Halo Nuclei by Elastic Proton Scattering at Low Momentum Transfer data: IKAR-Collaboration all experimental data are well described by Glauber calculations

nuclear matter distributions: nuclear matter radii: nucleusR matter, fmR core, fmR halo, fm 4 He1.49 (3)-- 8 He2.53(8)1.55 (15)3.08 (10) 9 Li2.43 (7)-- 11 Li3.62 (19)2.55 (12)6.54 (38) extended neutron distribution in 8 He and 11 Li obtained size of core, halo and total matter distribution determined with high accuracy Investigation of Nuclear Matter Density Distributions of Halo Nuclei by Elastic Proton Scattering at Low Momentum Transfer

III. Perspectives at the Future Facility FAIR FAIR: Facility for Antiproton and Ion Research 100 m UNILAC SIS 18 SIS 100/300 HESR Super FRS NESR CR RESR GSI today Future facility ESR FLAIR Rare-Isotope Production Target Antiproton Production Target

Primary Beams /s; GeV/u; 238 U 28+ Factor over present in intensity 2(4)x10 13 /s 30 GeV protons /s 238 U 73+ up to 35 GeV/u up to 90 GeV protons Secondary Beams Broad range of radioactive beams up to GeV/u; up to factor in intensity over present Antiprotons GeV Cooled beams Rapidly cycling superconducting magnets Key Technical Features Storage and Cooler Rings Radioactive beams e – A collider stored and cooled GeV antiprotons FAIR: Facility Characteristics 100 m UNILAC SIS 18 SIS 100/300 HESR Super FRS NESR CR RESR GSI today Future facility ESR FLAIR Rare-Isotope Production Target Antiproton Production Target

Optimized for efficient transport of fission products III Three experimental areas I High intensity primary beams from SIS 100 (e.g U / sec at 1 GeV/u) II Superconducting large acceptance Fragmentseparator SIS-100 Nuclear Physics with Radioactive Beams at FAIR: NUSTAR: NUclear STructure, Astrophysics and Reactions

Expected Production Rates r-process presently known nuclei

known exotic nuclei unknown exotic nuclei pathways of stellar nucleosynthesis regions of interest:  towards the driplines for medium heavy and heavy nuclei Perspectives at the GSI Future Facility FAIR physics interest: matter distributions (halo, skin…) single-particle structure evolution (new magic numbers, new shell gaps, spetroscopic factors) NN correlations, pairing and clusterization phenomena new collective modes (different deformations for p and n, giant resonance strength) parameters of the nuclear equation of state in-medium interactions in asymetric and low-density matter astrophysical r and rp processes, understanding of supernovae

for almost all cases: region of low momentum transfer contains most important information elastic scattering (p,p), ( ,  ), … nuclear matter distribution  (r), skins, halo structures inelastic scattering (p,p’), ( ,  ’), … deformation parameters, B(E2) values, transition densities, giant resonances transfer reactions (p,d), (p,t), (p, 3 He), (d,p), … single particle structure, spectroscopic factors, spectroscopy beyond the driplines, neutron pair correlations, neutron (proton) capture cross sections charge exchange reactions (p,n), ( 3 He,t), (d, 2 He), … Gamow-Teller strength knock-out reactions (p,2p), (p,pn), (p,p 4 He)… ground state configurations, nucleon momentum distributions Light-Ion Induced Direct Reactions at Low Momentum Transfer

Investigation of Nuclear Matter Distributions:  halo, skin structure  probe in-medium interactions at extreme isospin (almost pure neutron matter)  in combination with electron scattering ( ELISe FAIR ): separate neutron/proton content of nuclear matter (deduce neutron skins ) method: elastic proton scattering  at low q: high sensitivity to nuclear periphery Experiments to be Performed at Very Low Momentum Transfer – Some Selected Examples Investigation of the Giant Monopole Resonance:  gives access to nuclear compressibility  key parameters of the EOS  new collective modes (breathing mode of neutron skin) method: inelastic  scattering at low q  Investigation of Gamow-Teller Transitions:  weak interaction rates for N = Z waiting point nuclei in the rp-process  electron capture rates in the presupernova evolution (core collaps) method: ( 3 He,t), (d, 2 He) charge exchange reactions at low q

Proposed Experiments at FAIR e investigation of nuclear matter distributions along isotopic chains towards proton/neutron asymmetric matter s investigation of the same nuclei by (e,e) (ELISe) and (p,p) (EXL) scattering  separate neutron/proton content of nuclear matter  unambiguous and “model independent” determination of size and radial shape of neutron skins (halos) theoretical prediction: P.-G. Reinhard example: Sn isotopes at the nuclear surface: almost pure neutron matter  probe isospin dependence of effective in-medium interactions  sensitivity to the asymmetry energy (volume and surface term!)

The ELISe Experiment at FAIR ELISe: ELectron Ion Scattering in a Storage Ring e-A Collider MeV electrons MeV/u RIBs - spectrometer setup at the interaction zone nuclides of interest may be studied by leptonic and hadronic probes

Investigation of the Giant Monopole Resonance in Doubly Magic Nuclei by Inelastic  -Scattering GMR gives access to nuclear compressibility K nm (Z,N) ~  0 2 d 2 (E/A) / d  2 |  0  key parameter of EOS investigation of isotopic chains arround 132 Sn, 56 Ni, … with high  = (N-Z)/A  disentangle different contributions to K A = K vol + K surf A -1/3 + K sym ((N-Z)/A) GMR 208 Pb GMR 132 Sn

Kinematical Conditions for Light-Ion Induced Direct Reactions in Inverse Kinematics required beam energies: E  200 … 740 MeV/u (except for transfer reactions) required targets: 1,2 H, 3,4 He most important information in region of low momentum transfer  low recoil energies of recoil particles  need thin targets for sufficient angular and energy resolution ( ,  ‘) ( 3 He, t) (p,p) EXL

Nuclear Reactions with Relativistic Radioactive Beams at FAIR  EXL: EXotic Nuclei Studied in Light-Ion Induced Reactions at the NESR Storage Ring  Ring Branch  R 3 B: Reactions with Relativistic Radioactive Beams  High Energy Branch

EXL: EXotic Nuclei Studied in Light-Ion Induced Reactions at the NESR Storage Ring Electron cooler RIB‘s from the Super-FRS EXL Design goals: Universality: applicable to a wide class of reactions High energy resolution and high angular resolution Large solid angle acceptance Specially dedicated for low q measurements with high luminosity (> cm -2 s -1 ) Detection systems for: Target recoils and gammas (p,α,n,γ) Forward ejectiles (p,n) Beam-like heavy ions

Advantage of Storage Rings for Direct Reactions in Inverse Kinematics gain of luminosity due to: continuous beam accumulation and recirculation high resolution due to: beam cooling, thin target low background due to: pure, windowless 1,2 H 2, 3,4 He, etc. targets separation of isomeric states but: lifetime limit for very short lived exotic nuclei T 1/2 ≥ 1 sec

RIB production Rates at FAIR

A universal setup for kinematical complete measurements of Reactions with Relativistic Radioactive Beams The R 3 B experiment: identification and beam "cooling" (tracking and momentum measurement,  p/p ~10 -4 ) exclusive measurement of the final state: - identification and momentum analysis of fragments (large acceptance mode:  p/p~10 -3, high-resolution mode:  p/p~10 -4 ) - coincident measurement of neutrons, protons, gamma-rays, light recoil particles applicable to a wide class of reactions

IV. An Active Target for R 3 B at FAIR  well suited as alternative technique to EXL for:  short lifetimes (T ≤ 1 sec)  low RIB intensities (≤ 10 5 sec -1 )

The Active Target Setup at R 3 B

Cylinder with Be windows 500 um Beam shield d = 2 cm Beam tracking + vertex reconstruction Pressure P in the range 10 to 20 bar

Angular Region of Interest for (p,p) on Sn

Sensitivity on the Nuclear Radius

Kinematics

Dynamic Range

Feasibility Study reaction: p ( 132 Sn, p ), E = 700 MeV/u assumed intensity: 5 X 10 3 sec -1 assumed target: active target of 1m at 1 bar

Count Rate Estimate

Time Schedule Schedule determined by civil construction progress  delay of 1-2 years  first experiments at R 3 B: 2013

FAIR – Facility for Antiproton and Ion Research in 2015 Thank you First experiments at Super-FRS 2013 Austria China Finnland France Germany Greece India Italy Poland Spain Sweden Russia Great Britain Romania

V. Conclusions investigations of direct reactions at low q are of high interest the active target performance at R 3 B is complemantary to that of EXL (short lifetimes, small beam intensities) for these conditions the active target setup will provide sufficient luminosities the requirements are different to those of low energy experiments (large volume, large dynamic range) still some questions to be solved: - requirements for other reactions - magnetic field or high pressure ? - shielding of the large emittance beam (2cm)