EXL. EXotic nuclei studied in Light-ion induced reactions at the NESR storage ring. A unique opportunity at the future FAIR facility

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1 EXL EXotic nuclei studied in Light-ion induced reactions at the NESR storage ring A unique opportunity at the future FAIR facility Marielle Chartier FAIR UK Meeting, Daresbury, January 25-26, 2006

2 The Nuclear Chart: Theoretical Perspective Tackling the nuclear many-body problem Nucleon-nucleon forces and mean-field models with effective interactions Effective field theories QCD Experimental data and new phenomena challenge our theoretical descriptions of the nucleus

3 EXotic nuclei studied in Light-ion induced reactions at the NESR storage ring ~ 15 ~ 740 MeV/nucleon Key Key physics issues Matter Matter distributions (halo, (halo, skin ) skin ) Single-particle structure evolution (magic (magic numbers, shell shell gaps, gaps, spectroscopic factors) factors) NN NN correlations, clusters New New collective modes modes (different deformations for for p and and n, n, giant giant resonances strengths) Astrophysical r r and and rp rpprocesses (GT, (GT, capture ) In-medium interactions in in asymmetric and and low-density matter matter The experimental nuclear landscape Light-ion scattering Elastic Elastic (p,p), (p,p),(α,α) (α,α) Inelastic (p,p ), (p,p ),(α,α ) (α,α ) Charge Charge exchange (p,n), (p,n),(( 3 3 He,t), He,t), (d, (d, 2 2 He) He) Quasi-free (p,pn), (p,pn),(p,2p), (p,2p),(p,pα) (p,pα) Transfer (p,t), (p,t),(p, (p, 3 3 He), He), (p,d), (p,d),(d,p) (d,p) TERRA INCOGNITA 20 known exotic nuclei 114 unknown exotic nuclei pathways of stellar nucleosynthesis

4 Li+p (IKAR) 10-1 ρ m (r) [fm -3 ] Li 11 Li matter Li core r [fm] Theory: P.-G. Reinhard Ex: 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)

Investigation of the Giant Monopole Resonance In Doubly Magic Nuclei by Inelastic α-scattering GMR gives access to nuclear compressibility K

isoscalar Disentangle different contributions to K A = K vol + K surf A -1/3 + K sym ((N-Z)/A) 2 + GMR 208 Pb GMR 132 Sn Investigation of new

5 Investigation of the Giant Monopole Resonance In Doubly Magic Nuclei by Inelastic α-scattering GMR gives access to nuclear compressibility K nm (Z,N) ~ ρ 02 d 2 (E/A) / dρ 2 ρ 0 Key parameter of EOS Investigation of isotopic chains arround 132 Sn, 56 Ni, with high δ = (N-Z)/A isoscalar Disentangle different contributions to K A = K vol + K surf A -1/3 + K sym ((N-Z)/A) 2 + GMR 208 Pb GMR 132 Sn Investigation of new collective modes Breathing mode of neutron skin Experimental conditions to investigate the GMR (α,α ) inelastic scattering at very low momentum transfer

6 Feasibility Study with EXL Elastic proton scattering 132 Sn (Matter Distribution) Skin and haloes in heavy neutron-rich nuclei, nuclear potential parameters Inelastic alpha scattering on Sn isotopes (Giant Monopole Resonance) Collective modes in asymmetric nuclei, nuclear matter compressibility counts per hour High sensitivity of the method (simulation of experimental conditions as expected at the NESR with a luminosity of cm -2 s -1 )

7 Kinematical Conditions for Light-Ion Induced Direct Reactions in Inverse Kinematics The EXL low-momentum transfer is essential for elastic & inelastic scattering and charge-exchange reactions E recoil (MeV) (α,α ) θ CM = 20 0 θ CM = 10 0 θ CM = 5 0 θ θ CM = 5 0 CM = 5 0 θ CM = ints are: θ CM = 1, 5, 10 and 20 0 ( 3 He, t) θ lab (deg) 132 Sn(p, p) E=740 MeV/u, E* = 0 MeV 18 C(α, α) E=400 MeV/u, E* = 0 MeV 18 C(p, p') E=400 MeV/u, E* = 25 MeV 196 Pb(α, α') E=400 MeV/u, E* = 15 MeV 196 Pb( 3 He, t) E=400 MeV/u, E* = 0 MeV 12 Be( 3 He, t) E=400 MeV/u, E* = 0 MeV 22 C(p, d) E=15 MeV/u, E* = 0 MeV 132 Sn(d, p) E=15 MeV/u, E* = 0 MeV (p,p) EXL Required beam beam energies E ~ MeV/nucleon (except (except for for transfer reactions) Required targets Light Light nuclei nuclei (e.g. (e.g. 1,2 1,2 H, H, 3,4 3,4 He) He) Most Most important information in in the the region region of of low-momentum transfer detect detect recoil recoil particles of of low low energies need need thin thin targets targets for for sufficient angular angular and and energy energy resolution

8 Light-Ion Scattering with Radioactive Ion Beams Rather limited applications to date The EXL experiment, a huge leap forward: Heavy-ion storage ring Internal gas/liquid jet target Inverse kinematics CR RESR NESR Measurements at at low low energy/momentum transfer need need very very thin thin (windowless) (windowless) target target need need to to regain regain luminosity luminosity from from beam beam accumulation accumulation from from beam beam recirculation recirculation (NESR (NESR ~ ss -1-1 )) need need high high resolution resolution (recoil (recoil kinematics) kinematics) regain regain beam beam quality quality by by electron electron cooling cooling Physics overlap with R 3 B at the external target and with ELISe at the e-a collider Complementarity

9 Predicted the NESR Storage Ring Assumptions: 740 MeV/nucleon (6x10 11 ions/spill) > cm -2 s -1 over a large range of nuclei H gas-jet target (10 14 atoms/cm 2 ) Cycle time 1.54 s Including: Production rates Transmission through Super-FRS and into Collector Ring Losses due to nuclear decay (half-life) and electron capture in target or electron cooler Options to be explored: Deceleration, Multi-charge state operation (increase luminosity)?

10 External Target versus Internal Target ( for 1.5 mrad resolution ) Luminosity R 3 B EXL (10 6 pps) Max. external target thickness ρ, mg/cm E-3 1E-4 EXL only EXL CH 2 target + R3B lih 2 target LH 2 CH 2 Quasifree Elastic scatt. Giant Resonances Spin-isospin excitation E p, MeV 1E28 1E27 1E26 1E25 1E24 1E23 1E22 Luminosity, s Sn Sn Sn..

Advantages / Disadvantages of Storage Rings for Direct Reactions in Inverse Kinematics Gain Gain of of luminosity luminosity Continuous Continuous beam

Low Low background background Pure Pure windowless windowless 1,2 1,2 H, H, 3,4 3,4 He He targets targets Separation Separation of of isomers isomers

11 Advantages / Disadvantages of Storage Rings for Direct Reactions in Inverse Kinematics Gain Gain of of luminosity luminosity Continuous Continuous beam beam accumulation accumulation and and recirculation recirculation High High resolution resolution Beam Beam cooling, cooling, thin thin target target Low Low background background Pure Pure windowless windowless 1,2 1,2 H, H, 3,4 3,4 He He targets targets Separation Separation of of isomers isomers But: Lifetime limit for very short-lived exotic nuclei (> 500 ms) Active Target (low rate capabilities very exotic, short-lived nuclei) EXL R 3 B CR RESR NESR

12 NUSTAR Experiments with Stored Radioactive FAIR Collector Ring Bunch rotation Fast stochastic cooling RESR RIB (740 MeV/nucleon) from SUPER-FRS ELISe pbara NESR Electron cooling Continuous accumulation Internal jet targets CR ILIMA NESR EXL PIONIC gas target 100 m RESR Deceleration (1T/s) to MeV/nucleon

The EXL Experimental Set-up: Concept and Design Goals Design goals Gas jet Heavy-Ion Spectrometer Neutrons / Charged Ejectiles Recoil Detector Beam in Storage Ring Universality: applicable to a wide

13 The EXL Experimental Set-up: Concept and Design Goals Design goals Gas jet Heavy-Ion Spectrometer Neutrons / Charged Ejectiles Recoil Detector Beam in Storage Ring Universality: applicable to a wide class of reactions High energy and angular resolution Fully exclusive kinematical measurements High luminosity (> cm -2 s -1 ) Large solid angle acceptance UHV compatibility (in part) Internal jet target (>10 14 cm -2 ) Detection systems for: Target recoils and gammas (p,α,n,γ ) Forward ejectiles (p,n,γ) Heavy fragments Big R&D effort needed!

The EXL Recoil and Gamma Array Si DSSD ΔE, x, y 300 µm thick,

(FWHM) Thin Si DSSD tracking <100 µm thick, spatial resolution

thick, large area 100 x 100 mm 2, E = 50 kev (FWHM) CsI crystals

14 The EXL Recoil and Gamma Array Si DSSD ΔE, x, y 300 µm thick, spatial resolution better than 500 µm in x and y, E = 30 kev (FWHM) Thin Si DSSD tracking <100 µm thick, spatial resolution better than 100 µm in x and y, E = 30 kev (FWHM) Si(Li) E 9 mm thick, large area 100 x 100 mm 2, E = 50 kev (FWHM) CsI crystals E, γ High efficiency, high resolution, 20 cm thick Synergy with R 3 B & NUSTAR.

15 The EXL Recoil and Gamma Array Simulations (Si array) Energy resolution Θ CM, deg First layer 100 μm First layer 50 μm No first layer, 2nd 50 cm from target First layer 30 μm ΔΘ, mrad Θ CM, deg First layer 100 μm First layer 50 μm No first layer, 2nd 50 cm from target First layer 30 μm 132 Sn(p,p') E = 740 MeV/u ΔE *, MeV Sn(p,p') E = 740 MeV/u E p, MeV C.M. angle resolution E p, MeV Design goals on resolutions are attainable. But first silicon layer must be as thin as possible!

8 Backward angles (90 120 ) covered by 726 single crystals (5 different types) Modular Design Angular

16 The EXL Recoil and Gamma Array Calorimeter Forward angles (10 90 ) covered by 1304 single crystals (2 different types) Angular resolution: Δθ= 1.2 ΔΦ= 8.8 Backward angles ( ) covered by 726 single crystals (5 different types) Modular Design Angular resolution: Δθ= 2.3 ΔΦ= 7.8 elastic charge quasifree transfer and exchange reactions scattering inelastic reactions scattering Synergy with R 3 B & NUSTAR.

17 EXL Electronics R&D Large number of channels Large dynamic range, low thresholds UHV capabilities, baking, low power dissipation Space constraints Detectors channels DSSD and SiLi UHV cards- approx s on 1750 cards (32 channels/) Intelligence Intelligence Intelligence Intelligence Intelligence Intelligence Intelligence Intelligence EXL Electronics (Jan 2005) ADC cards ADCs on 219 cards (320 channels/adc) ADC ADC ADC ADC ADC ADC ADC ADC XPort Intelligence Ethernet (slow control) Synergy with NUSTAR.

18 The EXL Forward Ejectile Detector Kinematically complete measurements: detection of forward light particles emitted from the projectile (momenta measured) excitation energy of projectile residue, momentum (angular) correlations High-resolution TOF and position measurements Full solid angle (forward focus) Calorimeter: scintillator + iron converter (similar to LAND) Synergy with R 3 B.

19 The EXL In-Ring Heavy-Ion Spectrometer Ion-optical mode for NESR as fragment spectrometer 3 heavy-ion detector stations: in front of first dipole magnet for 'reaction tagging (main mode) inserted into dipole section for 'tracking' of fragments inserted into quadrupole section for 'imaging' properties of magnetic spectrometer (limited acceptance) Synergy with ELISe and AIC.

Test Experiments at the ESR Vacuum chamber with multiwire proportional chamber ESR Storage Ring Vacuum chamber with position sensitive PINdiode and

detection of fast ejectiles Silicon strip detector Gas-jet target UHV capable Si-strip detector for recoil protons Active area: 40 40 mm 2 Thickness: 1

20 Test Experiments at the ESR Vacuum chamber with multiwire proportional chamber ESR Storage Ring Vacuum chamber with position sensitive PINdiode and scintillator Scintillators with iron convertors 350 MeV/nucleon 136 Xe beam H 2 gas-jet target Luminosity s -1 cm -2 Scintillator array for the detection of fast ejectiles Silicon strip detector Gas-jet target UHV capable Si-strip detector for recoil protons Active area: mm 2 Thickness: 1 mm 40 Strips (Pitch: 1 mm) connected for read-out in groups of 8, each one with two output pins Energy resolution 35 ± 5 kev for α-particles with E = 5.5 MeV

21 Some Exciting Challenges Today... Recoil detector: High resolution: ΔE ~ 50 kev, Δϑ ~ 1 mrad Low thresholds UHV compatible (in part) Target: Cluster jet density and extension ( 1 mm) Alternative targets (pellet; fibre; He superfluid jet; polarized)? Ion-optical mode for NESR as fragment spectrometer Options to be explored: Deceleration down to ~ 15 A.MeV? Multi-charge state operation? For Some Exciting Physics Tomorrow!

22 The EXL Collaboration Univ. São Paulo TRIUMF Vancouver Spokesperson: M. Chartier (Liverpool) Deputy: P. Egelhof (GSI) 15 countries, 32 institutes, ~ 130 participants IPN Orsay GSI Darmstadt, TU Darmstadt, Univ. Frankfurt, FZ Jülich, Univ. Mainz, Univ. Munich INR Debrecen SINP Kolkata, BARC Mumbai Univ. Tehran INFN/Univ. Milano Univ. Osaka KVI Groningen JINR Dubna, NPI/KRI/Univ. St Petersburg, KI Moscow CSIC Madrid, Univ. Madrid Göteborg, Univ. Lund, Mid Sweden Univ., TSL Uppsala Univ. Basel Univ. Birmingham, CLRC Daresbury, Univ. Liverpool, Univ. Surrey

The Ring Branch. Nuclear Reactions at. Mass- and Lifetime Measurements. off Exotic Nuclei. Internal Targets. Electron and p. Experiments: Scattering

The Ring Branch. Nuclear Reactions at. Mass- and Lifetime Measurements. off Exotic Nuclei. Internal Targets. Electron and p. Experiments: Scattering stochastic cooling Exotic nuclei from Super-FRS Degrader for fast slowing down The Ring Branch TOF Detector MCPs E anode ion B CR Electron cooler NESR secondary electrons Experiments: Mass- and Lifetime