Reactions with Relativistic Radioactive Beams

Transcription

1 MINISTERIO DE EDUCACIÓN Y CIENCIA CONSEJO SUPERIOR DE INVESTIGACIONES CIENTÍFICAS Reactions with Relativistic Radioactive Beams A universal setup for kinematical complete measurements O. Tengblad Instituto de Estructura de la Materia, Madrid Outline: Where What:i.e.Research objectives How: Developments for R 3 B@FAIR calorimeter 1

2 FAIR - Facility for Antiproton & Ion Darmstadt Germany FAIR: Beams of stable as well as exotic ions and anti-protons up to an energy of 30 GeV/u Present GSI NUSTAR RESR CR SIS100, SIS300 SFRS NESR HESR SIS100, SIS300: Stable ions Z=1-92 Energy < 30 A GeV Intensities > ions/s SFRS: Production and separation of exotic nuclei CR: Storage and precision Measurements with exotics RESR: Antiproton storage deceleration of exotic nuclei NESR: collisions e - exotic nuclei collisions anti(p)- exotic nuclei deceleratión de anti(p) & exotics. HESR: PANDA collisions anti(p)-p 2

3 NUSTAR a facility for NUclear STructure & Astrophysis Research Superconducting Fragment Separator High Energy Reaction Set-up Multi-Storage Rings Energy bunched and stopped beams Low energy and stopped beams R 3 B collaboration: 50 institutes 180 scientists R 3 B Research with Relativistic Radioactive Beams Cooled and stored beams Super-FRS Secondary beams produce by fragmentation and fission 3

4 High-energy reactions using Radioactive beams R 3 B A universal fixed-target experiment for complete (charged particles, neutrons, gamma rays) inverse-kinematics reactions with relativistic RIBs (~ MeV/u), fully matched to the Super-FRS production method Experiments with the most exotic (<1 ion/s) and short-lived nuclei - exploring the isospin frontier at and beyond the drip-lines using a long range of reaction classes Concept built on existing ALADIN-LAND experiment at GSI 4

5 Based on the High Energy Reaction Studies: presently performed in Cave Reaction mechanism: Coulomb dissociation Diffraction Absorption Final state interaction Exp. variables: Beam energy MeV/A Target material C Pb Projectile 6 He 19 C Observables: n-momentum distribution Charge fragment momentum Invariant mass Angular correlations 5

6 What do we gain by FAIR Higher Primary beam energy Higher secondary beam intensity Thicker reaction targets In the order of 1 g/cm 2 extended detection scheme & better resolution Reaction products Kinematically forward focused Possible study more exotic nuclei efficient down to 1 ion/s, short lived 6

7 R 3 B Physics goals 7

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9 Quasifree hadronic scattering Probes valence and deeply-bound nucleons Simple picture is modified by nuclear medium : distortion of distributions, absorption etc. Single particle structure in nuclei Long- and short-range correlations in nuclei Density and isospin dependence of in-medium n-n interaction 9

10 Electromagnetic excitation Electromagnetic processes in heavy-ion interactions at energies far above the Coulomb barrier give access to a wealth of nuclear-structure information on exotic nuclei. Surface vibrations and particular giant resonances can be studied even with moderate beam intensities. The large cross sections allow experiments with minimum beam intensities of 1 to 1000 ions/s, provided efficient devices for γ-ray and particle detection are implemented. Charge-exchange reactions The (p,n) charge-exchange reaction can be used to excite Gamow-Teller (GT) and spin-dipole resonances by utilizing a liquid hydrogen target andmeasuringtheslow neutrons with plastic scintillators surrounding the target. Studies of the GT strength are beside their importance in nuclear structure of particular astrophysical interest. 10

11 A first summary A versatile reaction setup with high efficiency, acceptance, and resolution for kinematically complete measurements of reactions with high-energy radioactive beams. a variety of scattering experiments: heavy-ion induced electromagnetic excitation knockout and breakup reactions light-ion (in)elastic and quasi-free scattering in inverse kinematics enabling a broad physics programme with rare-isotope beams to be performed. 11

12 How does it look then? 12

13 R 3 B fragment ID GSI Large Acceptance Dipole GLAD CEA Saclay RPCs promising technology for TOF walls R&D on RPCs for neutrons - NewLAND 13

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15 NeuLAND concept 15

16 Research with Relativistic Radioactive Beams The Physics: Nuclear structure far off stability The Method: Scattering experiments with radioactive nuclei at high energy R 3 B set up in the NUSTAR FAIR Technical development: Total-absorption gamma spectrometer Requirements: High efficiency for high-energy γ (~10MeV) High γ sum-energy efficiency Good resolution in energy (~2-3% including Doppler broadening) Stop protons <300 MeV With good energy and angular resolution Tracking of protons & gammas 16

17 R3B calorimeter and tracker Calorimeter geometry Tracker prototypes (AMS type) Calorimeter w. inner tracker Demonstrator 17

18 Developments for calorimeter of R 3 B@FAIR The work carried out up to now have permitted to divide the calorimetro CALIFA in two parts : a cylindrical Barrel around the central zone and a second solution for the forward end cup ( ). novel solution using crystals of new generation and detectors formed by two layers of crystals (Phoswich) are being studied. 18

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20 Forward cap Zone B 30 cm Zone A 8 0 Phoswich: Volume Protons 20

21 Phoswich: p- Energy resolution E ΔΕ 1 +σ (ΔΕ 1 ) ΔΕ 2 + σ (ΔΕ 2 ) Ep= 200MeV 20 mm LaBr ΔE =31 ±1 MeV E = f( Δ E 1 ) + g( Δ E 2 ) Ep= 200MeV 30mm LYSO 200±10MeV (σe/e=5%) ΔE = 67.5±1.8 MeV Protons: Using two ΔE-detectors one can determine the full proton energy with a resolution of <5%. 200±7MeV (σe/e=3.5%) Gammas: Second detector placed to solve the ambiguity on the signal 21

22 Phoswich and gamma detection 1. Simulations show that the probability of some interaction in first layer is very high, up to 80% 2. Simulations also show that the fraction of energy absorbed in 5 cm of LYSO is > 80% 22

23 Simulations: crystal length 6 cm 6 cm Geant4, MCNPX Photon distance range in the material to be detected in the photopeak L l L l 15 cm 6 cm 10 cm 5 cm 23

24 Simulations: crystal length LYSO 15 cm 10 cm LaBr3 15 cm 10 cm CsI 15 cm 10 cm 24

25 Phoswich Solutions to be tested Two crystals of different materials with a unique readout system? Optically compatible LaBr 3 LaCl 3 E mm Δ E 1 Δ E 2 Two crystals of different materials but with separate readout system? LaBr 3 LYSO Δ E 1 E mm Δ E2 Ordered, awaiting delivery from Saint- Gobain 25

26 Summary: Key features of the experimental approach capable to accept the maximum beam energy (max rigidity of Super-FRS: 20Tm) max transmission for fission products (max intensity) access to short-lived nuclei (flight path ~μs) use of thick targets (~ g/cm2) luminosity gain kinematical complete measurement full-solid angle measurement plus high detection efficiency quantitative description of reaction mechanisms large cross sections for many reactions (e.g. elm excitation ~1 b, knockout ~100 mb) compensating low beam intensities experiments possible for very exotic and short-lived nuclei (even with low rates, ~1 ion/sec) 26

27 R 3 B collaboration Argonne National Laboratory, USA ATOMKI, Debrecen, Hungary CCLRC Daresbury Laboratory, UK CEA Saclay, France Chalmers Uni of Tech, Göteborg, Sweden IFIC - CSIC, Valencia, Spain CUPP project, Pyhaesalmi, Finland Dep. of Phys & Astro, Univ Aarhus, Denmark Forschungszentrum Rossendorf, Germany GANIL, Caen, France GSI, Darmstadt, Germany IFJ PAN Krakow, Poland IN2P3/IPN Orsay, France Inst of Modern Physics, Lanzhou, China IEM - CSIC, Madrid, Spain Inst de Fisica, Univ de Sao Paulo, Brazil IPN Lyon, France IPPE Obninsk, Russia Jagellonski University, Krakow, Poland Johannes Gutenberg Univ, Mainz, Germany J W Goethe Univ, Frankfurt, Germany Joint Inst Nuclear Research, Dubna, Russia Justus-Liebig-Univ, Giessen, Germany Kurchatov Inst, Moscow, Russia Max-Planck Inst Heidelberg, Germany Michigan State Univ, East Lansing, USA PNPI, Petersburg, Gatchina, Russia RIKEN, Japan Russian Academy of Sciences, Moscow, Russia Saha Inst of Nuclear Physics, Kolkata, India Tata Inst of Research, Mumbai, India Technische Universität Darmstadt, Germany Technische Universität München, Germany Univ Santiago de Compostela, Spain Universität zu Köln, Germany Univerity of Bergen, Norway University of Birmingham, UK University of Complutense Madrid University of Keele, UK University of Liverpool, UK University of Manchester, UK University of Paisly, UK University of Surrey, Guildford, UK University of York, UK Yale Univerity, USA R 3 B collaboration: 50 institutes 180 scientists 27