Study of the fission dynamics via Isomeric Ratio Measurements at Lohengrin - Development of a new Gas Filled Magnet spectrometer within the FIPPS project A. Chebboubi, G. Kessedjian, C. Sage, O. Meplan LPSC, Université Grenoble-Alpes, CNRS/IN2P3, Grenoble H. Faust, U. Köster, A. Blanc, P. Mutti Institut Laue-Langevin, Grenoble O. Serot, O. Litaize CEA-Cadarache, DEN/DER/SPRC/LEPh T. Materna, S. Panebianco CEA Saclay, DSM/IRFU/SPhN 1 Séminaire Doctorant, LPSC, Juin 2014
Outline • Nuclear fission and usefulness of nuclear data for applications and fundamental physics • Development of a new spectrometer : Gas Filled Magnet (GFM) • Properties of a GFM : experimental outcome • Comparison with a Monte Carlo Calculation • Isomeric Ratio measurements at Lohengrin (ILL) 2 Séminaire Doctorant, LPSC, Juin 2014
Outline • Nuclear fission and usefulness of nuclear data for applications and fundamental physics • Development of a new spectrometer : Gas Filled Magnet (GFM) • Properties of a GFM : experimental outcome • Comparison with a Monte Carlo Calculation • Isomeric Ratio measurements at Lohengrin (ILL) 3 Séminaire Doctorant, LPSC, Juin 2014
Part 1 : Nuclear Fission and Context of Nuclear Data Nuclear Fission Process 𝟐𝟏 −𝟐𝟕 − 𝟐𝟏 −𝟐𝟑 𝟐𝟏 −𝟕 − 𝟐𝟏 𝟘 𝟐𝟏 −𝟑𝟏 s Discovered by Hahn, Strassman and Meitner in 1938 → Chemistry Nobel Prize 1944 A heavy nucleus is broken into two lighter fragments. Emission of a few particles (neutron, 𝛿 ) 4 Séminaire Doctorant, LPSC, Juin 2014
Part 1 : Nuclear Fission and Context of Nuclear Data Context of the fission yield studies Impact of fission yields on the current and innovative fuel cycles 𝑍 𝐵, 𝑎, 𝐹 ∗ , 𝐾 𝜌 = 𝑍 𝐵, 𝑎 × 𝑄(𝐹 ∗ , 𝐾 𝜌 ) • Inventory of spent fuel • Isotopic composition → Residual power 𝑍(𝐵, 𝑎) • Radiotoxicity of spent fuel Modeling prompt particle emission (n/ 𝛿 ) • 𝑄 𝐹 ∗ , 𝐾 𝜌 → foreseen material damage/heating in reactor studies 5 Séminaire Doctorant, LPSC, Juin 2014
Part 1 : Nuclear Fission and Context of Nuclear Data Context of the fission yield studies 𝑍 𝐵, 𝑎, 𝐹, 𝐾 𝜌 = 𝑍 𝐵, 𝑎 × 𝑄(𝐹, 𝐾 𝜌 ) Measurements for fission process study • Improving the predictive power of fission models is necessary for the evaluations at different neutron energies → 𝑍 𝐵, 𝑎, 𝐹, 𝐾 𝜌 • Lack on dynamical aspect for fission process modelisation • Inconsistency between Models or evaluations and Experiments for heavy fragments and symmetric region Disagreement between fission models and experimental data assessment 6 Séminaire Doctorant, LPSC, Juin 2014
Part 1 : Nuclear Fission and Context of Nuclear Data How to measure Spin Distribution ? 𝑢ℎ 𝐵, 𝑎, 𝐹 ∗ , 𝐾 𝜌 = 𝑍 𝐵 × 𝑄 𝑎 𝐵 × 𝑄 𝐹 ∗ 𝐵,𝑎 × 𝑄 𝐾 𝜌 𝑍 𝐵,𝑎,𝐹 ∗ 15 Excitation Energy (MeV) States filled by fission Neutrons 10 Statistical ( prompt γ ) 5 Discrete 𝜹 Isomer emission 9 Spin(J) 6 3 To study Spin distribution, look at 𝛿 𝑞𝑠𝑝𝑛𝑞𝑢 , 𝑜 𝑞𝑠𝑝𝑛𝑞𝑢 structure effect at low excitation energy : Isomeric Ratio Isomer : state with longer half-life than neighboring states 7 Séminaire Doctorant, LPSC, Juin 2014
Part 1 : Nuclear Fission and Context of Nuclear Data How to measure Spin Distribution ? 𝑢ℎ 𝐵, 𝑎, 𝐹 ∗ , 𝐾 𝜌 = 𝑍 𝐵 × 𝑄 𝑎 𝐵 × 𝑄 𝐹 ∗ 𝐵,𝑎 × 𝑄 𝐾 𝜌 𝑍 𝐵,𝑎,𝐹 ∗ 𝑄 𝑂 𝑗𝑡𝑝𝑛𝑓𝑠 𝑄 𝛿 𝑞𝑠𝑝𝑛𝑞𝑢 𝐵,𝑎,𝐹 ∗ 𝑂 𝐻𝑇 𝐵,𝑎,𝐹 𝑙 • Isomeric ratio : Recent measurements on Lohengrin TOF Min/s Isomers : 98 136 132 130 129 129 99 𝐽, 𝑇𝑐, 𝑇𝑐, 𝑇𝑐, 𝑇𝑜, 𝑂𝑐, 𝑍 B µs Isomers : 𝛿 /n detectors 136 132 129 99 98 94 88 𝑌𝑓, 𝑈𝑓, 𝑇𝑐, 𝑍, 𝑍, 𝑍, 𝐶𝑠 ns Isomers : Gas-filled Almost all isotopes in heavy mass region Fragment (A,Z,E kin ) detection 8 Séminaire Doctorant, LPSC, Juin 2014
Part 1 : Nuclear Fission and Context of Nuclear Data How to measure Spin Distribution ? 𝑢ℎ 𝐵, 𝑎, 𝐹 ∗ , 𝐾 𝜌 = 𝑍 𝐵 × 𝑄 𝑎 𝐵 × 𝑄 𝐹 ∗ 𝐵,𝑎 × 𝑄 𝐾 𝜌 𝑍 𝐵,𝑎,𝐹 ∗ 𝑄 𝑂 𝑗𝑡𝑝𝑛𝑓𝑠 𝑄 𝛿 𝑞𝑠𝑝𝑛𝑞𝑢 𝐵,𝑎,𝐹 ∗ 𝑂 𝐻𝑇 𝐵,𝑎,𝐹 𝑙 • Isomeric ratio : Recent measurement on Lohengrin TOF Min/s Isomers : 98 136 132 130 129 129 99 𝐽, 𝑇𝑐, 𝑇𝑐, 𝑇𝑐, 𝑇𝑜, 𝑂𝑐, 𝑍 B µs Isomers : 𝛿 /n detectors 136 132 129 99 98 94 88 𝑌𝑓, 𝑈𝑓, 𝑇𝑐, 𝑍, 𝑍, 𝑍, 𝐶𝑠 ns Isomers : Gas-filled Almost all isotopes in heavy mass region Fragment (A,Z,E kin ) detection • FIPPS (Fission Product Prompt gamma-ray Spectrometer) Goals : - Direct measurement of prompt particles ( 𝛿 𝑞𝑠𝑝𝑛𝑞𝑢 , 𝑜 𝑞𝑠𝑝𝑛𝑞𝑢 ) - Fission product spectroscopy (astrophysics interest) - Neutron emission - Short lifetime isomers (ps,ns) 9 Séminaire Doctorant, LPSC, Juin 2014
Outline • Nuclear fission and usefulness of nuclear data for applications and fundamental physics • Development of a new spectrometer : Gas Filled Magnet (GFM) • Properties of a GFM : experimental outcome • Comparison with a Monte Carlo Calculation • Isomeric Ratio measurements at Lohengrin (ILL) 10 Séminaire Doctorant, LPSC, Juin 2014
Part 2 : GFM Development Back to the present : Lohengrin limits Lohengrin : selection with the mass over ionic charge ratios 𝐵 𝑟 and Kinetic energy over Ionic charge 𝐹 𝑙 𝑟 (A 1 ,E 1 ,q 1 )≡ (A 2 ,E 2 ,q 2 ) ≡(A 3 ,E 3 ,q 3 ) Limits : 2 µs time of flight (TOF) → no prompt particle study ( 10 −16 s) • A 1 ; A 2 ; A 3 Utility for GFM study : • Fission Fragment Source !! IC B RED 11 Séminaire Doctorant, LPSC, Juin 2014
Part 2 : GFM Development Experimental Setup for GFM study Setup : The RED magnet is now filled with various gases → GFM 𝐶𝜍 ∝ 𝐵 𝑤 𝑨 GFM : Spatial dispersion of fission 𝑟 𝑎 fragments according to Ionisation 𝑄,𝐻𝑏𝑡 the mass A and Nuclear charge Z 𝐶𝜍 ∝ 𝐵 Chamber [1] 1 𝑎 3 𝑩 𝟑 Goal : Study of properties of this device / feasibility IC B GFM 12 Séminaire Doctorant, LPSC, Juin 2014
Part 2 : GFM Development GFM separation power Ionisation Chamber 𝑩 𝟑 IC B GFM 13 Séminaire Doctorant, LPSC, Juin 2014
Part 2 : GFM Development Gas Comparison : Experimental results Gas Pressure Electronic density Resolution ratio 𝑂 2 7 mbar 1 2,2 % He 40 mbar 0,82 2,1 % 𝐵𝑠 − 𝐷𝐼 4 8,5 mbar 1,5 3,0 % Evolution of the magnetic resolution with 𝜍 𝑓 − density in several gases for A=98 𝐸𝑓𝑜𝑡𝑗𝑢𝑧 = 𝜍 𝑓 − 𝑂 2 , 𝑄 = 7𝑛𝑐𝑏𝑠 0,04 0,035 Magnetic resolution 𝑄 0,03 N2 0,025 0,02 He 0,015 Ar-CH4 0,01 Y98 (N2) 0,005 Poly. (N2) 0 0 0,5 1 1,5 2 Density (arbitrary unit) 14 Séminaire Doctorant, LPSC, Juin 2014
Part 2 : GFM Development Monte Carlo Calculation Architecture Trajectory inside GFM : Initial Condition: Effective charge : 𝑟 𝑓𝑔𝑔 • Position/Velocity/Ionic charge/Magnetic Field • Charge changing probability • Solution of motion equation • Energy loss calculation • Straggling effect Exit Condition: Is the particle detected? = 𝑦, 𝑧 ∈ Ionization Chamber 15 Séminaire Doctorant, LPSC, Juin 2014
Part 2 : GFM Development Gas Filled Magnet : What to compare along the pressure We will compare 𝐶 16 Séminaire Doctorant, LPSC, Juin 2014
Part 2 : GFM Development 𝑶 𝟑 Gas Filled Magnet : Test 98 Y & A=98 / E=90MeV / 233 U Energy loss in GFM for Mass 98 @ E=90MeV (Gaus) 𝑁𝐷𝐷 ± 1𝜏 𝐶 90 80 70 60 B Δ Egaz 50 July 2012 Experiment Preliminary results 40 30 Monte Carlo 𝜏 𝐶 : beam width 20 Calculation 10 0 0 5 10 15 Pressure (mbar) Big Three free parameters in 𝑂 2 𝜏 2𝑓− 𝑙 = 𝜏 𝑓− = 0,56 ± 0,05 • 𝜍 𝑟 𝑓𝑔𝑔 = 𝑟 𝐶𝑓𝑢𝑨 + 𝛾 ln 𝜍 0 → 𝛾 = −0,4 • • Δ𝑄 = P meas − P MCC = 0,5 ± 0,3 mbar 98 experimental data 𝑍 Set using A=98 & 17 Séminaire Doctorant, LPSC, Juin 2014
Part 2 : GFM Development 𝑶 𝟑 Gas Filled Magnet : Comparison E=95MeV / 235 U (Gaus) B Preliminary results Agreement for pressure below 10 mbar at 1𝜏 • shift • 𝑙 → 𝐶 • For 𝑄 > 10 𝑛𝑐𝑏𝑠 inconsistent calculation → Density effect on effective charge calculation Predictive calculation for light mass at 1 𝜏 Design the new spectrometer (find the better geometry) 18 Séminaire Doctorant, LPSC, Juin 2014
Outline • Nuclear fission and usefulness of nuclear data for applications and fundamental physics • Development of a new spectrometer : Gas Filled Magnet (GFM) • Properties of a GFM : experimental outcome • Comparison with a Monte Carlo Calculation • Isomeric Ratio measurements at Lohengrin (ILL) 19 Séminaire Doctorant, LPSC, Juin 2014
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