1. NATALIE: a multidetector system for activation techniques to characterize laser produced energetic particles M. Tarisien, F. Gobet, F. Hannachi, C. Plaisir, M.M. Aléonard Centre d’Etudes Nucléaires de Bordeaux-Gradignan, Université de Bordeaux, CNRS,IN2P3

2. Towards Nuclear Physics with ELI A laser with a high repetition rate and high intensity for Nuclear Physics A road paved with mile stones with recurrent requests: high repetition rate, > 1Hz : mbarn cross sections characterization of produced particles (electrons, protons) : - type and number| - energy distribution|==> tools: monitoring, characterization - angular distribution| Monitoring on line, shot after shot, to assess the quality of the data Characterization with nuclear activation: unsaturated, high solid angle technique, valid for different type of particles Gives their number and distributions for above MeV particle energy.

3. Typical electron energy distribution with a 30TW, 30fs laser and CH or Cu targets obtained with an electron spectrometer M. Gerbaux et al. RSI 79 (2008) 023504 Different temperatures for the energy distributions !

4. Nuclear activation techniques for particle characterization: Samples chosen to be activated on line - thickness and materials (lifetime) - geometries: integrated activation yield / angular distribution * for protons: RCF, Cu foils (µm thickness) stacks use (p,xn) reaction thresholds * for electrons: C, Cu pieces (mm thickness) use ( g,xn) reaction thresholds Shots monitoring for high repetition rate lasers: heavily collimated NaI scintillator (on line acquisition data) Use several diagnostics to check data quality: integral activation values cross checked with angular distributions using GEANT simulation tool

5. Schematic experimental setup On line Monitoring

6. Geometries for electron characterization via bremstrahlung Ta converter Activated sample Laser beam axis 63 Cu +  → 62 Cu + n and 62 Cu → 62 Ni + e + + ν e with T 1/2 ( 62 Cu) = 9,73 min et Et hresh = 9,8 MeV b + annihilation counting

7. Cu Stack Target (Al 9 µm) Laser Résultats protons 63 Cu + p → 63 Zn + n 63 Zn → 63 Cu + e + + ν e T 1/2 ( 63 Zn) = 38,5 min E seuil = 4 MeV n n n Time (min) Counts/minute 50 µm75 µm100 µm Proton characterization

8. NATALIE setup 3 cases ~ 1m 3 Used at RAL, LULI, ELSA (Bruyères le Chatel) < 1day to install and calibrate

9. NATALIE b + decay detection 13 detector pairs = 26 NaI scintillators 2”x2” 3 pairs = 6 NaI scintillators 3”x3” 511x511 keV coincidences efficiencies  low noise 2”x2” efficiencies: 4.84 +/- 0.12 (simulation: 5.0+/-0.2) 3”x3” efficiencies: 8.74 +/- 0.33 (simulation: 8.6) Possibility to use Ge detectors for b - decay detection or excited states detection in competing activation processes. Integrated electronic = 32 detectors => 64 electronic channels (energy and timing) + 64 Voltage power supply (low, HV)  integrated distribution

11. AMPLI+CFAMPLI+CF 16 NaI pairs NATALIE electronic schematics AMPLI+CFAMPLI+CF Computer USB Scaler (check) 32 chan 16 chan nel s 16 voies Scaler (check) 16 chan 16 chan nels NaI 16 chan nels Scaler (check) ADCADC TDC TDC P a tt e r n 32 chan TRIGGER UNITTRIGGER UNIT TRIG GATE NaI ScalerScaler TIMER TIMER 10kHz Start/Stop TTL Laser shot Timing (trigger / no trigger 16 chan nels Scalers and timer allow a direct dead time correction

12. Temperature T (electron spectrometer OR Cu/C (g,n) activations) Relative number of ( ,n) reactions in each sample (angular distribution) γ θ ( electron tracking in angular distribution geometry) Θ FWHM of electrons Chi2 Minimisation Analysis procedure Hypothesis on distribution 2 parameters: N 0 and  (fwhm)

13. 63 Cu(g,n) 62 Cu + 63 Cu(g,2n) 61 Cu + 65 Cu(g,n) 64 Cu (chi2=1,21) 63 Cu( g,n) 62 Cu (chi2=1,50)

14. Experimental and simulated 62 Cu, 11 C nuclei production  hot electrons Temperature obtained: (6.5+/- 0.3) MeV

15. Comparison of experimental and simulated activation yields All the activations processes use the same T° (6.5 MeV) and angular width (20.3+/2.5°) for the electron distributions  data are consistent with the known cross sections Same good fit for the vertical distribution !

16. Conclusive application: preplasma effect on the electron direction Angular distribution measurements with NATALIE  Interest of a wide solid angle apparatus Electron direction Normal to target Nb of Cu nuclei normalized C.Courtois et al., Phys. of Plasmas (2009) CH; e=3µm x y φ = 0 ° φ = 90 ° photons d= 300µm 1 Laser ps Laser ns 0 < delay 2 / 1 < 12ns

17. Conclusions: Nuclear activation techniques used in conjunction with GEANT simulations are an efficient tool: to characterize the number of activated nuclei, the angular and energy distributions of energetic electrons and protons

18. Nuclear activation setups : total number of particles, energy and angular distributions 63 Cu +  → 62 Cu + n and 62 Cu → 62 Ni + e + + ν e with T 1/2 ( 62 Cu) = 9,73 min et E seuil = 9,8 MeV θ φ = 180 ° x y φ = 0 ° φ = 90 ° φ = 270 ° Laser beam axis Thesis M Gerbaux (2007) C Plaisir (en cours) M.Gerbaux et al., Rev. Sci. Instrum 79, 023504 (2008) e-e-e-e- cible solide dépôt hydrogéné plasma p +- +- +- +- 63 Cu + p → 63 Zn + n 63 Zn → 63 Cu + e + + ν e T 1/2 ( 63 Zn) = 38,5 min E seuil = 4 MeV Natalie ANR+CRA GEANT4 Simulations M.Tarisien et al., 29 th E C LI M, Madrid, p592-597(2007) RCF Cu stack

19. beyond 6 MeV Boltzmann law adjust : Energy distribution along the laser beam axis (LOA)

20. 0 2 4 6 8 10 12 14 16 18 00.40.81.21.622.42.83.23.644.44.85.25.66 Amplitude du signal NaI (V) Nombre d'occurences Au Reproducibility of the laser-solid target interaction 0 1 2 3 4 5 6 7 8 9 10 00.40.81.21.622.42.83.23.644.44.85.25.66 Amplitude du signal NaI (V) Nombre d'occurences CH 0 1 2 3 4 5 6 7 8 9 10 00.40.81.21.622.42.83.23.644.44.85.25.66 Amplitude du signal NaI (V) Nombre d'occurences Cu 0 5 10 15 20 25 30 00.40.81.21.622.42.83.23.644.44.85.25.66 Amplitude du signal NaI (V) Nombre d'occurences Al Good reproducibility Reproducibility not terrific! Distribution of signal amplitude of the NaI monitor at LOA (30TW, 1J, 1Hz) Good correlation between the NaI monitor (horizontal scale) and the signal in the electron spectrometer diodes (vertical scale)  A large variation of the monitor signal is related to fluctuent reproducibility

21. 0 5 10 15 20 0 406080 Z Température ( MeV ) IOQ LOA Batani et al. LOA : fluctuations moyennées sur environ 10 tirs IOQ : fluctuations moyennées sur 12 tirs Comparaisons des « températures » LOA / IOQ Résultats issus des spectromètres à électrons + fit (moindres carrés) Les barres d’erreurs témoignent de l’accord entre l’ajustement en loi de Boltzmann et les points expérimentaux. Dans le cas de l’or (Z=79) au LOA, peu de points expérimentaux dont 1 très éloigné du fit.