Rare ISotope INvestigation at GSI Status of the
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Rare ISotope INvestigation at GSI Status of the relativistic beam campaign Introduction Fast beam physics program Experimental methods Status and perspectives P. Reiter for the RISING collaboration Workshop: RISING with stopped beams University of Surrey, March 29 – 30, 2004
RISING introduction • RISING physics with stopped beams, March 29/30, 2004 Surrey • GSI Program Advisory Committee January 26/27, 2004 Darmstadt 4 RISING proposals • Commissioning & first experiments August-October 2003 • GSI Program Advisory Committee June 20/21, 2002 Darmstadt 12 RISING proposals • Physics with RISING at GSI, March 22, 2002 Orsay • RISING physics with relativistic HI-beams, April 6, 2001 Darmstadt • RISING physics with stopped beams, March 9, 2001 Göttingen • RISING physics with slowed-down beams, April 2/3, 2001 Legnaro • Physics with EUROBALL detectors at GSI, November 23/24, 2000 Darmstadt
High resolution -spectroscopy at the FRS • fragmentation and fission of primary beams • projectile energy 400 – 750 Me. V/u • primary targets: Be or Pb FRS • Dipoles: • Identification of fragmentation product (A, Z) g-spectroscopy at secondary target • Channel selection after target (A, Z) • Tracking before/after secondary target RISING
RISING approved experiments No. Nuclei of Interest Primary Beam Spokespersons Experiment Type approved (days) 1 32, 34 Mg 48 Ca P. Mayet 2 step fragmentation lifetime 6 2 45 Cr, 53 Ni, 45 Sc, 53 Mn 58 Ni M. Bentley 2 step fragmentation 7 3 68 Ni 86 Kr A. Bracco Coulex, E 1 strength 7 4 36 Ca, 66 Fe 86 Kr H. Grawe, H. Hübel P. Reiter Coulex, 2+1 13 5 69 Br 78 Kr F. Becker 2 step fragmentation 7 6 88 Kr, 90 Sr, 86 Se 238 U J. Jolie Coulex, 2+2 10 7 104 -112 Sn 124 Xe C. Fahlander M. Górska Coulex , 2+1 7 8 132 Sn 238 U G. de Angelis Knock-out 5 9 132 Xe 136 Xe A. Maj Coulex, Angular Distr. 3 10 134 Te 136 Xe K. -H. Speidel Coulex, g-factor 7 11 136 Nd 144 Sm T. Saito Coulex 7 12 185, 186, 187 Pb 238 U J. Gerl, A. Andreyev G. D. Dracoulis 2 step fragmentation lifetime 8
Physics program 104 -112 Sn 134 Te 132 Sn 53 Ni 68 Ni 66 Fe 32, 34 Mg Shell structure of unstable magic- and double magic nuclei
Isospin symmetry at N=Z 45 Cr, 49 Fe, 53 Ni f 7/2 -shell 69 Br 55 Ni 55 Co 53 Fe 49 Fe 50 Mn 45 Cr 46 Cr 45 V 42 Ti 43 Ti 41 Sc 42 Sc 43 Sc 50 Cr 46 V 45 Ti 46 Ti 45 Sc ? 41 Ca 42 Ca T= 1/2 T= 1 T=3/2 no excited states
Shapes and shape coexistence 136 Nd 185, 186, 187 Pb 3+ 2+ potential energy surface for 186 Pb
-decay of the GDR in the Exotic Nucleus 68 Ni • Giant Dipole Resonance (GDR) : basic collective excitation modes • effective NN interactions • Evolution of GDR strength in exotic nuclei : • Fine structures • GDR strength at lower energy • astrophysical implications 48 Ni 58 Ni 68 Ni 78 Ni RISING: relativistic Coulomb excitation (virtual photon scattering) -decay branch: G /Gtot ~ 10 -3 - 10 -2 Relativistic RPA, Vretenar et al.
experimental methods Established methods: • Coulomb excitation - first 2+ states => B(E 2) - giant dipole resonance (virtual photon absorption) • Secondary fragmentation - excited states at higher spins and excitation energy
RISING new developments Coulomb excitation - Low lying states B(E 1), B(E 2, 0+gs -> 2+1, 2, 3) - 2+ states + angular correlation - 2+ states + g-factor
-decay of the GDR in the Exotic Nucleus 68 Ni Excited via Coulomb Excitation HECTOR reaction 6 Ba. F 2 detectors 68 Ni (400 Me. V/A) + nat. Pb (2 g/cm 2) efficiency at high energies: Ba. F 2 for the whole GDR strength function Ge cluster for the Pygmy part
knock-out reactions Spectroscopic factors: -ray intensity of excited states in the A-1 fragment. g-decay of excited states No l-value of ejected nucleon, missing momentum distribution. Recoil momentum 132 Sn
Shape evolution in n-rich Mg nuclei Primary beam : 48 Ca Secondary beam : 38 Si SIS Secondary fragmentation & lifetime measurement FRS 38 Si S 4 0. 7 mm 32 Mg , b 1 2. 1 mm 32 Mg , b 2 32 Mg , b 3 100 Me. V/u 1 targets: Au : 3 x 0. 3 g/cm 2 E 3 E 2 2 E 1 3 E
RISING timetable 2003 22. 4. - 16. 5. 2003 Cluster shipment 22. 4. - 4. 8. 2003 annealing, assembly, testing and mounting 16. 6. - 20. 6. 2003 assembly of support structure 14. 7. - 5. 8. 2003 VXI-MBS tests (S 4) beam time • Commissioning II • New Shell Structure at N>>Z • Isospin Symmetry, Coulomb Effects • Coulomb Excitation Near 100 Sn beam 132 Xe 84 Kr 58 Ni 124 Xe date Aug 06 – Aug 11 Sep 12 – Sep 21 Sep 22 – Sep 28 Oct 11 - Oct 20 Oct 21 - Oct 27
short term outlook 2004 Block 2/2004: March 31 - May 21 (Therapy: March 31 - April 30) RISING: May 1 – 18 - E 1 strength in 68 Ni RISING & HECTOR - Shell structure in N>>Z nuclei SIS beam time is shared between: • HADES • FRS & ESR mass measurements • RISING & MINIBALL Block 3/2004: July 14 - October 7 (Therapy: July 14 - August 13) Block 4/2004: Oct. 27 – Dec. 16 (Therapy: Oct. 27 – Nov. 26) RISING: Nov. 29 – Dec. 12 RISING & MINIBALL 2005 Ø Winter: RISING & MINIBALL Increased -efficiency: 4 - 10 %
Summary RISING fast beam campaign - started data taking on time in 2003 First experiments - Coulomb excitation of stable 84 Kr (commissioning) - Coulomb excitation of fragments: 56 Cr, 108 Sn, 112 Sn - Spectroscopy after secondary fragmentation of 55 Ni see talks: N. Hashimoto, M. Gorska, A. Bürger, M. Bentley
