The Super-FRS Project at GSI

Transcription

1 2 m A G A T A The Super-FRS Project at GSI FRS facility The concept of the new facility The Super-FRS and its branches Summary Martin Winkler for the Super-FRS working group CERN, Energy Buncher Low-Energy Branch Pre-Separator Main-Separator High-Energy Branch ea-collider SIS-2 Production Target Super-FRS CR NESR SIS-18 Ring Branch

2 Projectile Fragmentation and Projectile Fission Projectile Fragmentation Projectile Target Projectile Fragment Nucleon-Nucleon-Collissions (Abrasion Ablation) Vf V p Projectile Projectile Fission V V + V f p fission Target Fission Fragments Coulomb Excitation in Peripheral Collisions EPAX cross section (barn) 129 Xe fragmentation 238 U projectile fission Fragment Mass Number A K.Sümmerer

3 Kinematics of Exotic Nuclei produced in Projectile Fragmentation and Projectile Fission U + C Ni - (Fission) p/p Fission Fragmentation U + C Sn - (Fission) 4 σ α / mrad Fission Fragmentation Energy / (MeV/u) α / mrad Xe + C Sn - (Fragmentation) p/p

4 Bρ- E-Bρ Separation Method

5 Experiments with the FRS Nuclear structure and reactions Explore the properties of dripline nuclei, search for new structures and shells, study hadronic atoms Nuclear astrophysics and applications Exotic nuclei are the key to understand the formation of elements in the universe Atomic interactions of heavy ions with matter Basic atomic collision studies and applications PET, isotope separation, stopping of fragments in a gas cell New Fission Studies New Mass Measurements B= p B= n B=4MeV F r-process Halo Nuclei Pionic Atoms 8 B New Fission Fragments 78 Ni Shells far off Stability 11 Li Skin Nuclei

6 The Present Secondary Beam Facility at GSI PRODUCTION TARGET FRS Branches 3 ALADIN SIS FRS 1 2 ESR LAND INJECTION FROM UNILAC Limitations of the facility: Low primary beam intensity (e.g U /s) Low transmission for projectile fission fragments (4-1% at the FRS) Low transmission for fragments into the storage ring and to the experimental areas Limited maximum magnetic rigidity

7 The Energy-Z Operating Domain for In-Flight Separation Energy [MeV/u] Nb 5% nuclear absorption q=z 95% 9% 8% Z

8 Comparison of the FRS and the Super-FRS FRS Super-FRS Degrader Degrader 2 Degrader 1 B ρ max p/p Φ x Φ y resolving power FRS 18 Tm 1. % + 13 mrad + 13 mrad 15

9 Transmission Gain for Fission Products Super-FRS FRS Z

10 Rates for Exotic Nuclei at the Super-FRS

11 Ion-Optical Design of the Super-FRS y x /cm dipole quadrupole quadrupole + hexapole octupole D 1 D 2 D 3 D 4 D 5 D 6 hexapole F 1 F 2 F 3 F 4 F 5 F Length / m at F1 at F2 at F4 at F6 (x,x) (x,a) (x,p) (a,x) (a,p) (y,y) (y,b) (b,y)

12 Separation performance using two degrader stages Pre-Separator Main-Separator Z Features of two degrader stages Reduction of contaminants from fragments produced in the degrader Optimization of the fragment rate on detectors in the main-separator Introduction of another separation cut in the A-Z plane Possible usage of pre- and main-separator for secondary reaction studies N

13 Separation Characteristics for 1 Sn with 1 and 2 Degrader Stages 5 primary fragments ( ) 4 Z 3 2 secondary fragments ( ) N

14 The Super-FRS and it s Facility SIS-2 SIS-18 Production Target Pre-Separator Super-FRS Main-Separator 2 m Energy Buncher AGATA CR Low-Energy Branch High-Energy Branch NESR ea-collider

15 The High-Energy Branch Reaction Physics goals Ions/s Knockout Unbound states, properties beyond the driplines 1-1 Single particle structure.1-1 Electromagnetic Single particle structure.1-1 Excitation Soft dipole modes 1-1 Giant dipole resonance 1 Giant quadrupole strength 1 3 B(E2), evolution of shell structure Astrophysics, rp-process, (p,γ) S-factor Fission Shell structure, dynamical properties 1 3 Fragmentation γ spectroscopy, high spin 1 Multifragmentation EOS, phase transitions (p,n) Spin-dipole exc., neutron skin, GT strength Quasi-free scattering Single particle structure 1 Spallation Reaction theory (applications, e.g. hybrid reactors) 1 4

16 Instrumentation of the Low-Energy Branch.γ-ray spectroscopy +p δ p -p δ p p p AGATA LASER spectroscopy Decay spectroscopy NaI - Crystals Si-Detectors Super-Clover Ge-Detector NaI - Crystals Trap system Detector Precision trap Cooler trap 1m Extraction RFQ

17 Instrumentation for Experiments with Stored Beams 1 m

18 Summary Large momentum and angular acceptance Super-FRS consists of three branches feeding caves for different types of experiments High secondary-beam transmission to all experimental areas and into the CR/NESR Increase of secondary beam intensities of more than 1 compared to now Super-FRS needs more than one separation stage to provide sufficient background reduction Unambigious fragment identification (q=z) Higher separation quality Higher sensitivity and selectivity Physics with single exotic atoms

19 Intensity distribution in the preseparator of Super-FRS First quadrupoles: up to 3% In the first dipole most of the fragments will drop out, everything with dp/p > 3% 2.5 m 1% Target: up to 25% of primary beam dump of primary beam 6% remaining intensity 1% of primary beam 1. m beam lost or target all intensities in percent of the primary beam intensity in particles per sec. Degrader: further fragmentation of up to 4% of the fragments. 9% of fragments stopped in slit remaining intensity.1% of primary beam

20 The GSI Upgrade