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Measurement of the U-234(n,f) cross section with PPAC detectors at the n_TOF facility

Measurement of the U-234(n,f) cross section with PPAC detectors at the n_TOF facility. Carlos Paradela Dobarro Universidad de Santiago de Compostela. Contents. Motivation n_TOF facility and detection setup description. Data reduction and efficiency estimation.

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Measurement of the U-234(n,f) cross section with PPAC detectors at the n_TOF facility

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  1. Measurement of the U-234(n,f) cross section with PPAC detectors at the n_TOF facility Carlos Paradela Dobarro Universidad de Santiago de Compostela Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  2. Contents • Motivation • n_TOF facility and detection setup description. • Data reduction and efficiency estimation. • 234U fission cross sections results. • Conclusions. Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  3. Neutron-induced nuclear reactions Neutron scattering AXZ nucleus Cross Sections f Neutron capture (n,) neutron Target (AXZ nucleus) + Projectile (1n0) Fission (n,f) Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  4. Why we measure these cross sections? Measurement of cross sections are relevant for: • Nuclear Technologies • Waste transmutation (ADS) • Thorium fuel reactors • Nuclear Astrophysics • Heaviest element nucleosynthesis (“r” process) • Fundamental Nuclear Physics • Nuclear structure Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  5. Neutron Capture  decay Thorium-Uranium cycle “La fisión del torio y la fusión de deuterio-tritio […] son nuevas energías nucleares con residuos de corta duración y sin proliferación, capaces de proporcionar energía durante los próximos milenios.” El mundo de mañana,hoy, Carlo Rubbia, El País, 2 de Octubre. “Thorium fission and deuterium-tritium […] are new non-proliferation nuclear energies producing short-term wastes, that can provide energy for the next millenniums.” • 232Th + n  233Th  233Pa  233U (fissile) • 233U+n  234U • 233Pa+n 234Pa  234U 232U 233U 234U 235U 236U 237U 238U 231Pa 232Pa 233Pa 234Pa 235Pa 230Th 231Th 232Th 233Th 234Th Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  6. The n_TOF collaboration U.Abbondanno14, G.Aerts7, H.Álvarez24, F.Alvarez-Velarde20, S.Andriamonje7, J.Andrzejewski33, P.Assimakopoulos9, L.Audouin5, G.Badurek1, P.Baumann6, F. Bečvář 31, J.Benlliure24, E.Berthoumieux7, F.Calviño25,D.Cano-Ott20,R.Capote23,A.Carrillo de Albornoz30,P.Cennini4, V.Chepel17, E.Chiaveri4, N.Colonna13, G.Cortes25, D.Cortina24, A.Couture29, J.Cox29, S.David5, R.Dolfini15, C.Domingo-Pardo21, W.Dridi7, I.Duran24, M.Embid-Segura20, L.Ferrant5, A.Ferrari4, R.Ferreira-Marques17, L.Fitzpatrick4, H.Frais-Koelbl3, K.Fujii13, W.Furman18, C.Guerrero20, I.Goncalves30, R.Gallino36, E.Gonzalez-Romero20, A.Goverdovski19, F.Gramegna12, E.Griesmayer3, F.Gunsing7, B.Haas32, R.Haight27, M.Heil8, A.Herrera-Martinez4, M.Igashira37, S.Isaev5, E.Jericha1, Y.Kadi4, F.Käppeler8, D.Karamanis9, D.Karadimos9, M.Kerveno6, V.Ketlerov19, P.Koehler28, V.Konovalov18, E.Kossionides39, M.Krtička31, C.Lamboudis10, H.Leeb1, A.Lindote17, I.Lopes17, M.Lozano23, S.Lukic6, J.Marganiec33, L.Marques30, S.Marrone13, P.Mastinu12, A.Mengoni4, P.M.Milazzo14, C.Moreau14, M.Mosconi8, F.Neves17, H.Oberhummer1, S.O'Brien29, M.Oshima38, J.Pancin7, C.Papachristodoulou9, C.Papadopoulos40, N.Patronis9, A.Pavlik2, P.Pavlopoulos34, L.Perrot7, R.Plag8, A.Plompen16, A.Plukis7, A.Poch25, C.Pretel25, J.Quesada23, T.Rauscher26, R.Reifarth27, M.Rosetti11, C.Rubbia15, G.Rudolf6, P.Rullhusen16, J.Salgado30, L.Sarchiapone4, C.Stephan5, G.Tagliente13, J.L.Tain21, L.Tassan-Got5, L.Tavora30, R.Terlizzi13, G.Vannini35, P.Vaz30, A.Ventura11, D.Villamarin20, M.C.Vincente20, V.Vlachoudis4, R.Vlastou40, F.Voss8, H.Wendler4, M.Wiescher29, K.Wisshak8 1Atominstitut der Österreichischen Universitäten,Technische Universität Wien, Austria, 2Institut für Isotopenforschung und ernphysik, Universität Wien, Austria, 3Fachhochschule Wiener Neustadt, iener Neustadt, Austria, 4CERN, Geneva, Switzerland, 5Centre National de la echerche Scientifique/IN2P3 - IPN, Orsay, France, 6Centre National de la echerche Scientifique/IN2P3 - IReS, Strasbourg, France, 7CEA/Saclay - DSM, Gif-sur-Yvette, France, 8Forschungszentrum Karlsruhe GmbH (FZK), Institut für Kernphysik, Germany, 9University of Ioannina, Greece, 10Aristotle University of Thessaloniki, Greece, 11ENEA, Bologna, Italy, 12Laboratori Nazionali di Legnaro, Italy, 13Istituto Nazionale di Fisica Nucleare, Bari, Italy, 1Istituto Nazionale di Fisica Nucleare, Trieste, Italy, 15Università degli Studi Pavia, Pavia, Italy, 16CEC-JRC-IRMM, Geel, Belgium, 17LIP - Coimbra & Departamento de Fisica da Universidade de Coimbra, Portugal, 18Joint Institute for Nuclear Research, Frank Laboratory of Neutron Physics, Dubna, Russia, 19Institute of Physics and Power Engineering, Kaluga region, Obninsk, Russia, 20Centro de Investigaciones Energeticas Medioambientales y Technologicas, Madrid, Spain, 21Consejo Superior de Investigaciones Cientificas - University of Valencia, Spain, 22Universidad Politecnica de Madrid, Spain, 23Universidad de Sevilla, Spain,, 25Universitat Politecnica de Catalunya, Barcelona, Spain, 26Department of Physics and Astronomy - University of Basel, Basel, Switzerland, 27Los Alamos National Laboratory, New Mexico, USA, 28Oak Ridge National Laboratory, Physics Division, Oak Ridge, USA, 29University of Notre Dame, Notre Dame, USA, 30Instituto Tecnológico e Nuclear, Lisbon, Portugal, 31Charles University, Prague, Czech Republic, 32Centre National de la Recherche Scientifique/IN2P3 - CENBG, Bordeaux, France, 33University of Lodz, Lodz, Poland, 34Pôle Universitaire Léonard de Vinci, Paris La Défense, France, 35Dipartimento di Fisica, Università di Bologna, and Sezione INFN di Bologna, Italy, 36Dipartimento di Fisica Generale, Università di Torino and Sezione INFN di Torino, I-10125 Torino, Italy, 37Tokyo Institute of Technology, Tokyo, Japan, 38Japan Atomic Energy Research Institute, Tokai-mura, Japan, 39NCSR, Athens, Greece, 40National Technical University of Athens, Greece C. Paradela24 , 24Universidade de Santiago de Compostela, Spain, Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  7. n_TOF CERN Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  8. n_TOF facility (I) Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  9. FTN transfer line 7ns Lead target n_TOF facility (II) 4 - 7 x 1012 protons per pulse Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  10. Second Collimator TOF TUBE n_TOF facility (III) Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  11. Neutron beam monitors Micromegas SiMon n_TOF facility (IV) Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  12. Escape Line DAQ n_TOF facility (V) PPAC gas regulation Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  13. Y (mm) X (mm) n_TOF beam characteristics • Neutron spectrum • Energy resolution • Beam profile DEn/En < 10-3 @ En < 104 eV Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  14. Fission detection setup Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  15. Fission Detection Setup (I) Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  16. Fission Detection Setup (II) • Fissile target in a thin backing sandwiched by two detectors  Detection of both fission fragments in coincidence. • Fission event reconstruction: target position and emission angle. Efficiency limited by the cut at large angles. Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  17. Targets (I) Epoxy frame Uranium target 80 mm Ø 300 µg/cm2 2 µm Al backing Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  18. Targets (II) • Measurement of thickness and homogeneity by alpha counting. • High purity samples (> 99 % for U-234). 234U Y (mm) X (mm)  activity Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  19. Very thin detectors. High FF efficiency Fast timing (0.5 ns de resolution using anode signal). FF position by using cathode signals. PPAC (I) Parallel Plate Avalanche Counter Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  20. U-234: singles Discrimination with coincidences U-234: coincidences Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  21. Selection of fission events from 234U (target 0) Time & Amplitude selection Det0 Amplitud (a.u.) Time coincidencewindow Time difference (1/10 ns) Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  22. PPACs @ n_TOF • 10 detectors 9 targets • U-234(2) and Th-232(5) • Two reference targets: U-235 y U-238 • Less than 1 % of flux attenuation in the full setup. Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  23. Three detectors in coincidence Detector 1 Detector 0 Detector 2 LEFT TARGET n FF1 FF2 Detector 2 Detector 1 Detector 0 RIGHT TARGET n FF1 FF2 Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  24. Three detectors in coincidence Fissions from target on the left Fission from target on the right Correlation between time differences of detectors 0,1 and 2 Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  25. Cathode Positioning (I) • Positioning by using stripped cathodes and delay line readout. • The cathode signal is split in the delay line and transmitted to both ends Stripped Cathode Delay Line Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  26. Cathode positioning (II) Diagonal condition: (Tch1-Tanode)+(Tch2-Tanode)=DLT DLT: Total delay line length (~320 ns) The time difference between both cathode ends provides the position of the signal. Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  27. Cross section analysis Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  28. Cross Section Analysis •  (E): fission cross section • n (x,y,E): fission rate obtained from raw data •  (x,y): surface density of the target •  (E): detection setup efficiency a(x,y,E)/ b(x,y,E) ≈ 1 ± 0.01 (1%) Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  29. Efficiency estimation Factors determining the efficiency: • Setup angular acceptance. • Hardware threshold cut. • Fission fragment angular distribution Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  30. Expected angular acceptance 100% efficiency 70º Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  31. 50º 58º 50º 70º Angular acceptance Simulations Measurements Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  32. Hardware threshold cut Cathode signals for En < 100 keV Cathode signals for En > 1 MeV Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  33. HFF LFF Hardware threshold cut (II) HFF LFF Target 0 Energy < 10 MeV (Assymetric fission) Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  34. Hardware threshold cut (IV) E ~ 5 MeV Fit to a double Gaussian with the areas below the peaks: AHFF and ALFF Efficiency estimation obtained from the ratio: Detected events/Expected events where the expected events are assumed to be 2 x ALFF. AHFF ALFF E < 200 keV ALFF AHFF Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  35. High Energies Low Energies High Energies U-235 Low Energies Hardware threshold cut (V) Detected/Expected U-234 (Target 0) High Energies U-234 (Target 1) Low Energies Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  36. Log E =6.0 Log E =5.8 Log E =5.9 Cos () Cos () Cos () Log E =5.4 Log E =5.6 Log E =5.5 Fission Fragment Angular Distribution U-234 FFAD for neutron energies near the fission threshold Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  37. Fission Fragment Angular Distribution(II) W()1+Bcos2 , B  Anisotropy parameter W()= C(P0+P1cos  )(1+Bcos2), P0 and P1 intrinsic parameters Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  38. Fission Fragment Angular Distribution (III) U-238 this work Leachman +Tutin B U-238 anisotropy Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  39. Fission Fragment Angular Distribution (III) B U-234anisotropy Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  40. Efficiency estimation IN THE LOW ENERGY RANGE  B supposed as 0 U-235 Hardware threshold cut! U-234 (target 1) W()= CE (P0+P1cos ) U-234 (target 0) Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  41. E = 800 keV Efficiency estimation (II) IN THE HIGH ENERGY RANGE Efficiencies for both U-234 targets Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  42. Efficiency estimation (III) U-235 efficiencies in the full energy range Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  43. Efficiency estimation (IV) • The cosine distribution at very high energies is disturbed because of wrong trajectory reconstruction. Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  44. Cross section results Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  45. U-234(n,f) cross section Present work ENDF/B-VI Normalised to ENDF/B-VI in the 1-4 MeV interval Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  46. Resolved Resonance Region • 234U(n,f) cross section presents important subthreshold resonances. • Resolved Resonance Region extends to 1.5 keV. Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  47. Previous data Resolved Resonance Region (II) Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  48. Resolved Resonance Region (III) ------ ORNL 1977 ------ n_TOF PPAC 2003 f (b) E (eV) Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  49. Resolved Resonance Region (IV) ENDF/B-VI n_TOF PPAC 2003 JEFF-3.1 n_TOF PPAC 2003 Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

  50. Resolved Resonance Region (V) ------ ORNL 1977 ------ n_TOF PPAC 2003 f (b) Narrow intermediate structure shown by James and Rae1 1. G. D James and E. R. Rae,, Nucl. Phys. A118, 313 (1968) Measurement of 234U(n,f) cross section. Carlos Paradela. PhD dissertation

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