Nuclear Physics experiments with high energy lasers

Nuclear Physics experiments with high energy lasers F Hannachi, C.Plaisir,F Gobet, M. Tarisien and M.M. Aléonard Centre d’Etudes Nucléaires de Bordeaux Gradignan (CENBG/ Université de Bordeaux/CNRS-IN2P3) V. Méot, G. Gosselin, P. Morel CEA/DAM/SPN ICUIL 2010 1

Nuclear level properties are studied since decades... in neutral or close to neutral atomic configurations Very little is known on the behavior of nuclear observables in highly excited ions or in plasma High energy lasers offer a unique opportunity to start such studies Outline • Nuclear level properties in special atomic conditions • Mechanisms for nuclear excitations and decays in plasma • Theoretical predictions • Experiments to observe the modification of nuclear level • lifetimes and to induce fast decays of nuclear isomers in plasma • - Conclusion ICUIL 2010

K e IC Atomic levels are sensitive to the nucleus charge distribution and nuclear properties depend on the atomic environment Effect of ionisation on nuclear lifetimes - 7Beneutral t1/2 =52 d (EC decay) while 7Be4+ : stable - first excited level of 125Te (Z=52, E=35.5 keV) Q=0 T1/2=1.5 ns (internal conversion + M1) Q= 47+ T1/2 = 6 ± 1 ns F.Attalah et al., Phys.Rev.Lett. 75(1995) 1715 ICUIL 2010

Nuclear excitation processes in plasma ? « Direct » excitation processes Photon Absorption Electron Inelastic Scattering ICUIL 2010

« nondirect » excitation processes: several NEEC Proposed by Gold’danski and Namiot (1976) Unobserved ICUIL 2010

NEET (Nuclear Excitation by Electronic Transition) • Resonnant process caracterized by: • Energy mismatch : d • Quantum selection rules M. Morita, Progr. Theor. Phys. 49, 1574 (1973) E.V.Tkalya Nucl. Phys.A539 209(1992) M.. Harston Nucl.Phys A690 447(2001) Observed for 3 nuclei in neutral atoms (synchrotron) 197Au PNEET = (5.0±0.6) 10-8 189Os PNEET< 4.5 10-10 193Ir PNEET= (2.8±0.4) 10-8 ICUIL 2010

MODELS AND PREDICTIONS By the CEA DAM Bruyeres le Chatel group: main ingredients: relativistic average atom, relativistic mean field, time dependent perturbation theory P. Morel, et al, Phys. Rev. A69, 063414 (2004) P.Morel et al, PRA69, 063414 (2004) G Gosselin et al, PRC 70, 064603 (2004) G Gosselin et al, PRC 76, 044611 (2007) G Gosselin et al, PRC 79, 014604 (2009) G Gosselin et al, PRC 81, 055808 (2010) Nuclear + atomic + plasma physics ICUIL 2010

Calculation of NEET probability in plasma (T, ρ): difficult task Coupling matrix element Probability to find a hole in shell f Number of electrons In shell i Statistical dispersion / average atom G. Faussurier, et al, Rev. E 56,3474 (1997). Relativisic average atom (thermodynamical equilibrium) B. F. Rozsnyai, Phys. Rev. A5 (1972) 1137 P.Morel et al, PRA69, 063414 (2004) ICUIL 2010

(V.Méot et al, Phys. Rev. C 75, 064306 (2007)) 81±5 ns 1.565 keV 1/2+ B(E2;1/2-→3/2-)= 0.2490.082 e2b2 a=6.5105 M1+E2 d2(E2/M1) = (2.1 ± 0.5) 10-4 B(M1;1/2-→3/2-)= (2.00.7)10-3mN2 0. keV 3/2+ Nucleus : 201Hg ICUIL 2010

NEET for the transition at 1.565 keV in 201Hg d =nuclear transition energy–atomic transition energy d=0 eV 42+ • 4s1/2 3d3/2 transition atomique (E2) pour un atome neutre:1577 eV • Mismatch avec la transtion nucléaire 12.2 eV • 6s1/2 4s1/2 transition atomique (M1) pour 42+:1566.7 keV • Mismatch avec la transition nucléaire 1.7 eV ICUIL 2010

Half life of 201Hg first excited state + NEET 201Hg 3 ms r=10-2 g/cm3 81. ns Experiment at LIL ? V. Méot et al., Phys. Rev. C 75, 064306 (2007) G. Gosselin et al. Phys. Rev. C76, 044611 (2007) ICUIL 2010

Fast decay of the 84Rb isomeric state Partial level scheme of 84Rb • Isomeric state Jπ = 6- • Isomer de-excitation characterized by 2 γ-rays : 215 keV and 248 keV. • Jπ = 5-excited state 3 keV above the isomeric state • Jπ = 5-de-excitation characterized by 2 γ-rays : 218.5 keV and 248 keV M1 E2 M3 E4 M1 ICUIL 2010

Excitation of the 84mRb isomeric state in plasma NEET dominant excitation process for temperature of 300 – 400 eV (Average charge state of 32) Rates.s-1.nucleus-1 466.6 keV 5- 9 ns 463.6 keV 6- 20.26 min 248.1 keV 84Rb Calculated by G. Gosselin and P. Morel ICUIL 2010 13

A challenging program to study de-excitation of isomeric state in plasma T1/2 = 20 min: requires an isomer « production facility » close to the high energy laser Production of 84Rb and 84Rbm with 85Rb(γ,n) reactions • PW laser focused on thin target : • e- beams production • e- converted into γ-rays (bremsstrahlung) • γ-rays induced nuclear reactions on 85Rb : • 84Rb and 84Rbm production ICUIL 2010 14

Experimental setup PETAL (500 fs, 1 kJ, 20µm) Al 85Rb converter   Segmented detector Electrons  Quad LIL ( 28 kJ, 20 ns, 700 µm) :plasma • High Energy laser focalized on activated Rb target Typical intensity: 1014 W.cm-2 during few ns Temperature of a few 100 eV and average charge state of 32 ICUIL 2010

Numbers….. 85Rb (,n) 84Rb PETAL electron beam converted into photons Target 85Rb (72%, density= 1,53g/cm3) of 30 µm thickness IS cross section = 50 mb ~ 1012 useful photons between 10 and 20 MeV E Lefebvre ( PETAL 700fs, 0,9 kJ, 10µm ~10 21 W/cm2 : 1012 photons/MeV/Sr between 10 MeV and 20 MeV with a 2 mm W converter) ~ 1000 isomers should be excited per laser shot ICUIL 2010

conclusion Real opportunities offered by PW + high energy lasers for nuclear excitation in plasma studies Aim: check the codes validity and reliability • Still lot of work to do: • design the experiments, laser conditions • Develop specific detection devices • Collaborators are welcome! ICUIL 2010

3) Effect of nuclear excitations on nuclear level lifetimes: In plasma, intermediate energy states can strongly modify the effective half-life of a nuclear state: β- β- 0 10 20 30 40 50 60 Plasma temperature [keV] N.Klay et al. PRC 44,2839 (1991) (n,γ) 108 K = 10 keV ICUIL 2010 18

Physique Atomique dans un plasma… à l’équilibre thermodynamique Modèle relativiste d’Atome moyen B. F. Rozsnyai, Phys. Rev. A5 (1972) 1137 • Effet de densité : atome dans une boite de rayon =r1/3 • Moyen : valeurs moyennes pour les énergies de liaison, • les taux d’occupation sont calculés par la distribution de Fermi-Dirac • Modèle champ moyen relativiste : Equation de Dirac-Fock G. D. Doolen, Phys. Rev. C18 (1978) 2547 T ICUIL 2010

NEET Constraints: Possible only for very few stable nuclei initially in their ground state: 57Fe, 181Ta, 201Hg, 235U Excited level 14.4 keV 6.2 keV 1.56 keV 76.8 eV Energy Lifetime 98.3 ns 6 µs 81 ns 27 min ICUIL 2010

Plasma :n, T Noyau : système à deux niveaux Quelle est la quantité d’états excités par rapport à l’état fondamental ? Loi de Boltzmann • Temps d’approche à l’équilibre: ICUIL 2010

Mercury ion T=220eV 6s1/2→ 4s1/2 r=0.01 g/cm3 ICUIL 2010

6s1/2 4s1/2Q = 42+ 10-2 g/cm3 Te220 eV 6s1/2 4f7/2 4f5/2 4d5/2 4d3/2 4p3/2 4p1/2 4s1/2 Hg42+ Core: Ni- 28 Théorie classique des fluctuations Atome moyen→Energie moyenne ICUIL 2010

Taux d’excitation 201Hg NEEC+PHOTON+NEET NEET NEEC r=10-2 g/cm3 T=1 keV. E.V.Tkalya, Laser Physics, 14 360(2004) PHOTON 42+ ICUIL 2010

Thermodynamic Equilibrium • Nucleus populations (Boltzmann law) in state i with an excitation energy Ei and spin Ji ICUIL 2010

Thermodynamic Equilibrium • Equilibration time (under stationary conditions) • Populations at equilibrium ICUIL 2010

Multi-field Modeling • Microscopic model : quantum tools • Fermi Golden rule • Time dependant perturbations • Partial wave scattering (PWBA, DWBA, …) • Macroscopic model • Relativistic average atom • Statistical Thermodynamics • Plasma Physics ICUIL 2010

Nuclear Physics experiments with high energy lasers