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Rare Isotope Spectroscopic INvestigation at GSI
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abrasion ablation σ f [cm 2 ] for projectile fragmentation + fission luminosity [atoms cm -2 s -1 ] Rate Estimate Count Rate Estimate 70% transmission SIS – FRS ε trans transmission through the fragment separator FRS event rate[s -1 ] = luminosity[cm -2 s -1 ] * σ[cm 2 ] * 0.7 * ε trans
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20% speed of light deflecting magnets focussing magnets acceleration Max. 90% speed of light experiment UNILAC IonNumber of injections Intensity [spill -1 ] at FRS Ion source Date 58 Ni16*10 9 MEVVA3.2006 107 Ag13*10 9 MEVVA2.2006 124 Xe15*10 9 MUCIS3.2008 136 Xe45*10 9 MEVVA7.2006 208 Pb301.3*10 9 PIG3.2006 238 U12.0*10 9 PIG9.2009 Primary Beam Intensity 15.5% speed of light eff. puls width for injection: 47μs 36.2% efficiency intensity[s -1 ]=0.5*intensity[spill -1 ] period of one revolution 4.7 μs, 10 turns will be accepted for injection, acceleration: 0.5s, extraction 1s, magnet resetting 0.5s
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RIBs produced by fragmentation or fission
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Nuclear Reaction Rate The optimum thickness of the production target is limited by the loss of fragments due to secondary reactions Primary reaction rate: Example: 238 U (10 9 s -1 ) on 208 Pb (x=1g/cm 2 ) → 132 Sn (σ f =15.4mb) reaction rate: 44571[s -1 ] Primary + secondary reaction rate: 10.79 21.25 31.47 41.55 51.53 61.45 Example: Example: 124 Xe (10 9 s -1 ) on 9 Be (x=1g/cm 2 ) → 104 Sn (σ f =5.6μb) reaction rate: 375[s -1 ]
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Nuclear reaction rate Reaction rate (thin target): Reaction rate (thick target): Example: Reaction rate: 57941[s -1 ] transmission (SIS/FRS)=70%, transmission (FRS) 1.9%
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Optimization of the target thickness Primary reaction rate: Example: Primary + secondary reaction rate: 10.79 21.25 31.48 41.56 51.54 61.46
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Reaction Parameters for Heavy-Ion Collisions The relevant formulae are calculated if A 1, Z 1 and A 2, Z 2 are the mass (in amu) and charge number of the projectile and target nucleus, respectively. Nuclear radius for homogeneous (sharp) mass distribution: Nuclear radius for diffuse (Fermi) mass distribution: Nuclear interaction radius: Nuclear reaction cross section at relativistic energies:
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Secondary Beam Rate at S4 IonReactionσ[b]ε FRS [%]Rate[s -1 ] 36 Si 48 Ca+ 9 Be6.6·10 -5 15622 50 Ca 82 Se+ 9 Be4.5·10 -6 1442 46 Cr 58 Ni+ 9 Be1.6·10 -5 32342 68 Ni 86 Kr+ 9 Be5.3·10 -5 25886 82 Ge 86 Kr+ 9 Be0.8·10 -6 5932 104 Sn 124 Xe+ 9 Be5.6·10 -6 55206 134 Te 136 Xe+ 9 Be3.7·10 -4 4511137 179 W 208 Pb+ 9 Be8.8·10 -4 3319425 88 Kr 238 U+ 208 Pb2.6·10 -2 0.3226 132 Sn 238 U+ 208 Pb1.5·10 -2 1.2521 Beam intensity: 10 9 [s -1 ] Target thickness: 1[g/cm 2 ]
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Secondary Beam Intensities at S4 transmission SIS-FRS: 70% primary Xe-beam intensity: 2.5·10 9 [s -1 ] Be-target thickness: 4g/cm 2 transmission through FRS: 60% primary U-beam intensity: 10 9 [s -1 ] Pb-target thickness: 1g/cm 2 transmission through FRS: 2%
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Experimental set-up MUSIC ionization chamber; Z scintillator Z A/Q multiwire chamber; beam position Y X
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Experimental set-up FRS + RISING setup 56 Cr Z A/Q 86 Kr, 480MeV/u CATE Y X MWPC
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E CsI detectors Mass identification ∆E 0.3 mm thick Si detectors Z identification Position sensitive CAlorimeter TElescope R. Lozeva et al., NIM A, 562 (2006) 298 EE E 56 Cr Y X
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15 Clusters (105 Ge crystals) ΔE γ =1.6% (1.3 MeV, d=70cm) ε γ = 2.8% Experimental set-up FRS + PreSPEC setup Ringangular range 110.5 0 -21.3 0 227.6 0 -38.4 0 330.6 0 -41.4 0 LYCCA-0 TPC 86 Kr, 480MeV/u
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DSSSD ΔE energy loss DSSSD ΔEΔE x, y FRS beam A, Z E~100MeV/u Target Be/Au CsI-detector E res residual energy Plastic scintillator t Start Plastic scintillator t Stop Cluster Ge-Detectors Fragmentation or Coulomb-excitation Particles have to be identified again Energy loss ΔE ~ Z 2 Total energy (E res +ΔE) and velocity → A Time-of-flight measurement Scattering angle (twice position) Future goal: Reduce number of detectors Experimental set-up FRS + PreSPEC setup Diamond t Start LYCCA-0
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Reaction Types at Relativistic Energies secondary beam intensity: 10 3 [s -1 ] target Au thickness: 0.4[g/cm 2 ] Coulex cross section: 0.50[b] RISING γ-efficiency: 3% reaction rate: 66[h] secondary beam intensity: 10 3 [s -1 ] target Be thickness: 0.7[g/cm 2 ] fragmentation cross section: 0.03[b] RISING γ-efficiency: 3% reaction rate: 152[h]
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Scattering Experiments at 100MeV/u target thickness (mg/cm 2 ) angular width (mrad) Coulomb excitation: projectile mass number A 1 grazing angle (mrad)
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target: Au,Be
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Bremsstrahlung electric field lines (v/c=0.99) slowing down of a moving point-charge
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Radiative electron capture (REC) capture of target electrons into bound states of the projectile: Primary Bremsstrahlung (PB) capture of target electrons into continuum states of the projectile: Secondary Bremsstrahlung (SB) Stopping of high energy electrons in the target: Atomic Background Radiation
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Radiative electron capture (REC) capture of target electrons into bound states of the projectile: Primary Bremsstrahlung (PB) capture of target electrons into continuum states of the projectile: Secondary Bremsstrahlung (SB) Stopping of high energy electrons in the target: Atomic Background Radiation
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1381807 Additional Background Radiation
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HECTOR BaF 2 Additional Background Radiation 132 Xe beam (150 MeV/u) → Au target (0.2 g/cm 2 ) time spectrum (ns) At the very beginning… prompt (target) 142 0 84 Kr beam (100 MeV/u) → Au target time spectrum (ns) 142 0 prompt (target)
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HECTOR BaF 2 Additional Background Radiation Early gamma radiation 5ns, coming from the beam line, caused by the light particles, ranging to very high energies (0-20 MeV) 8-12ns after 15ns after
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HECTOR BaF 2 Additional Background Radiation prompt CATE time spectrum Coulomb excitation: A/Q - 37 Ca, CATE - Ca prompt time spectrum Fragmentation: A/Q - 37 Ca, CATE -K (mainly 36 K) 37 Ca beam at 196MeV/u
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511 20040060080010001200 548 ~600MeV/u 68 Ni secondary beam ~100MeV/u 54 Cr secondary beam ~200MeV/u 132 Xe primary beam Incoming-outgoing projectile selection, Au target 197 Au Coulex line( ~35mb) ? Additional Background Radiation
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for with Doppler Broadening Δ
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with for Doppler Broadening Δβ
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for Velocity distribution at the moment of a prompt γ-ray decay after the production of 36 Ca. (T=130 AMeV and different 9 Be target thicknesses) target thickness [mg/cm 2 ] ΔE γ0 /E γ0 [%] 3003.4 5003.8 7005.3 ringangular range 110.5 0 -21.3 0 227.6 0 -38.4 0 330.6 0 -41.4 0 Doppler Broadening Δβ
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Triaxiality in even-even nuclei (N=76) T.R. Saito et al. (2005) First observation of a second excited 2 + state populated in a Coulomb experiment at 100AMeV using EUROBALL and MINIBALL Ge-detectors. collective strength shape symmetry 2 1 + 0 + 2 2 + 0 + 2 2 + 2 1 + 136 Nd energy [keV] counts
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LYCCA-0 commissioning June 2010 July 2010 measurements with projectile fragments FRS-detectors: S2-finger detector, 4 TPCs at S2 & S4, 2 MUSIC, SC-41 ΔE, E res resolution (DSSSD, CsI) Δtof (diamond-plastic) (plastic-plastic) γ-ray background (HECTOR) degrader, Fe-window, Pb-brick wall, LYCCA-0 Cluster Ge-detector fragment-γ-ray coincidences, Doppler-shift correction MUSIC fast readout test of S2 finger detector AGATA-detector 37 energy signals readout (DGF)
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First fast-beam PreSPEC proposals Proposed experiment: 25 Si, 29 S and 33 Ar PreSPEC-Array, LYCCA ToF- E-E-Telescope Coulomb excitation of 104 Sn Proposal by M. Gorska, J. Cederkall Mixed-symmetry states in 88 Kr Proposal by J. Jolie, N. Marginean
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132 Xe (662 keV) v/c = 0.000 What happens to the spectral shape, when one applies Doppler correction? „662 keV”
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132 Xe (662 keV) v/c = 0.100
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132 Xe (662 keV) v/c = 0.200
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132 Xe (662 keV) v/c = 0.300
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132 Xe (662 keV) v/c = 0.320
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132 Xe (662 keV) v/c = 0.330
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132 Xe (662 keV) v/c = 0.340
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132 Xe (662 keV) v/c = 0.345
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132 Xe (662 keV) v/c = 0.350
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132 Xe (662 keV) v/c = 0.355
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132 Xe (662 keV) v/c = 0.360
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132 Xe (662 keV) v/c = 0.370
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132 Xe (662 keV) v/c = 0.380
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132 Xe (662 keV) v/c = 0.390
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132 Xe (662 keV) v/c = 0.400
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132 Xe (662 keV) v/c = 0.410
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132 Xe (662 keV) v/c = 0.420
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132 Xe (662 keV) v/c = 0.430
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132 Xe (662 keV) v/c = 0.440
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132 Xe (662 keV) v/c = 0.450
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132 Xe (662 keV) v/c = 0.355 132 Xe (662 keV) v/c = 0.355 Spectral shape is NOT Bremstrahlung! The nearly constant γ-background is compressed by Doppler correction.
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