1November Fission works in CEA DAM DIF, E.Bauge, Service de Physique Nucléaire CEA DAM DIF

2November  capture (Elastic), inelastic, (n,2n) Pas fission  ! neutron : 0<E<10 MeV actinide : Ex: 235 U actinide : 236 U E*=6.5MeV+En FF1 : Z1, A1 FF2 : Z2, A2 neutrons The fission phenomenon

3November Contradictory integral and differential trends Capture 238 UFission 238 U Integral tests

4November Diagnostic : Error compensation PNFS & CaptureInélastics 238 U 235 U (& 238 U) 235 U & 238 U  f 235 U : very well known 0D neutronics

5November PNFS measurements at WNR with FIGARO 235 U, 238 U, 239 Pu, 237 Np Fission chamber Today

6November LANSCE WNR WNR facility Unmoderated spallation neutrons source 800 MeV protons Figaro

7November Experiment principle TOF 2 / ~1 m Neutron detectors Fission Chamber TOF 1 / ~22 m Pulsed neutron Beam (1-~200 MeV) Double time of flight Incident n energy (22 m) Fission n energy (~1 m) Typical resolution: Incident: 1% at 2 MeV 15% at 200 MeV Fission: 15% at 800 keV 50% at 8 MeV Detection efficiency obtained by measuring known PFNS (252Cf spont. Fiss.) Total efficiency ~ 1 % Neutron/gamma pulse shape discrimination Fission neutrons measured between ~800 kev and ~ 8 MeV for bins of incident neutron energy in 1 – 200 MeV Measurements at side angles: not sensitive to preequilibrium PFNS compatible with Watt spectra within stat. either obtained directly in the region measured or by Watt or Maxwellian fits Mean multiplicity : relative measurements, normalized to references at low energy

8November Fission neutron energy spectrum Neutron energy (MeV) Neutron yield per MeV BRIC calculation (H. Duarte, BIII) 239 Pu(n,F), E n =50 MeV Pre-equilibrium Fragment evap. Prefission evap. Normalized Total Neutron spectrum Region of investigation (Watt domain)

9November Published results on for 238 U & 235 U BRC eval. are obtained independently BRC eval: ‘à la Los Alamos’ with Tudora- Vladuca prescription and BRC partial cross sections obtained from fits of Watt parameters 1 st unambiguous observation of dips at the opening of fission chances Phys. Lett. B 575, 221 (2003), PRL 94, (2005) PRL 101, (2008)

10November Published results on for 238 U & 235 U BRIC (BRIEF): MC Intra-Nuc. Cascade code (H. Duarte, PRC 75, ), includes evaporation and fission models Red curve: experimental angular cuts + Watt fit over MeV (same as experimental analysis)

11November Np results Data analysis: J. Taieb Presented by J. Taieb at ND-2007, Nice Results to be published (MeV) obtained from fits of Watt parameters Red curve: eval. by V. Maslov

12November Current investigation 239 Pu Data recorded in 2007 and : Technical problems: signal to noise ratio degraded due to neutron scattering off fission chamber structure materials Background noise monitored on-line 2008: Other fission chamber with less structure materials New neutron detectors provided by CEA-BIII: *Stilbene and para-ter-phenyl crystals to lower fission neutron energy threshold

13November Pu preliminary results 2007 data (analysis by A. Chatillon at BIII) Much better data in 2008 (stat. and syst.), analysis ongoing (AC) Green curve: BRC 2008 eval (1-7 MeV), obtained independently

14November He counter at WNR Grande efficacité: ≈ 30% Goal : et P( ) measurements 1st measuremnt : 239 Pu this fall 238 U(n,f) 235 U(n,f) Very high efficiency (few corrections) FIGARO meas. Tomorrow morning

15November PNFS measurements (n,xnf) at Geel (?) with CARMEN + energy and mass ratio of FF in coinc FF 1 m 1 v 1 FF 2 m 2 v 2 Dét1 Dét2 Cible très mince max 100  g/cm 2 Tomorrow PNFS as a function of x

16November NFS (neutrons for science) neutron source 40 MeV deuteron beam on C (or W) converter 20 m TOF low noise room Collimated neutron beam First beam 2012 in GANIL Future home of the CARMEN detector for PNFS studies Tomorrow

17November Ion-electron collider at GSI-FAIR « Perfect » FF detection (A,Z) (no threshold), in coinc with neutrons 1 er beam: 2015 ? Tomorrow

18November Animation Modélisation microscopique de la fission

19November Microscopic fission models

20November Fission microscopique Deformation Q20Deformation Q30 Deformation energy Neutron multiplicity (simplistic)

21November Microscopic fission yields : collective dyamics

22November Detailed FF decay In TALYS code (statistical decay) Phase I : simplistic inital conditions (Done !) Phase II : combined with inital conditions derived from microscopic calculations

23November Normalizing microscopic results With adjustement Microscpic barriers In TALYS Example : cross sections