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E528S Neutron correlation in 6 He studied through its nuclear break-up.

Reaction : 6 He + Pb @ 20 MeV/A 4 He + n + n + Pb. E528S Neutron correlation in 6 He studied through its nuclear break-up. M.Assie , J.A.Scarpaci , D.Lacroix , M.Alahari, J.C.Angelique, T.Aumann, D.Bazin, Y.Blumenfeld, D.Beaumel, W.Catford, M.Chabot, A.Chatterjee, M.Fallot,

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E528S Neutron correlation in 6 He studied through its nuclear break-up.

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  1. Reaction : 6He + Pb @ 20 MeV/A 4He + n + n + Pb E528SNeutron correlation in 6He studied through its nuclear break-up. M.Assie, J.A.Scarpaci, D.Lacroix, M.Alahari, J.C.Angelique, T.Aumann, D.Bazin, Y.Blumenfeld, D.Beaumel, W.Catford, M.Chabot, A.Chatterjee, M.Fallot, D.Mengoni, J.Nyberg, C.Petrache, F.Skaza, H.Iwasaki, T.Tuna 6He is an archetype of a Borromean nucleus ; high intensities most suitable nucleus to investigate new experimental approach and develop new theoretical tools SPIRAL beam Di-neutron configuration Cigar configuration Zhukov et al., Phys. Rep. 231 (1993) 151

  2. d/dd d/dd Small impact parameters Nuclear break-up cigar di-neutron n n Small differences in relative angles di-neutron cigar Measure neutrons at large angles Needs a theoretical development 0° 60° 0° 60° Neutron angular emission Large impact parameters Coulomb break-up cigar di-neutron extension of TDHF (TDDM) (M.Assie-D.Lacroix) G.Normand, PhD thesis 2004 F.M.Marques, PR C64, 2001

  3. Set-up for E528S EDEN Gazeous profiler 6He 20 MeV/u EDEN I = 106~107 pps

  4. Strips 6He 4He SiLi neutrons Measurement NWall

  5. di-neutron cigar Experimental relative angular distribution All Nwall and EDEN 10 < En < 30 MeV Uncorrelated (mixed events)

  6. 8% remains Detector Number Detector Number Close detectors Ecalc=time of flight Eout=Ecalc-Eloss Eijmin=minimum E to go from i to j • Rejection criterea : • Ecalc<Eloss ==> cross talk • Eout(i)>Eloss(j)& Eout(i)> Eijmin ==>might be crosstalk Eloss(j) Eout(i) Ecalc(i) Measurement of crosstalk with 12C + 208Pb 10B 1n+1p 12C For En > 10MeV 20% of the events are cross-talk events 11C 11B 10B

  7. Test of the rejection algorithm with GEANT4 One emitted neutron - 2 detectors hit Only 15% of the crosstalk events remain

  8. With and without crosstalk for >40° (nuclear break-up) 10 < En < 30 MeV with crosstalk without crosstalk PRELIMINARY Counts for rel <20° : 1 492 860 (with crosstalk) 953 203 (without crosstalk) 63% remains

  9. 35% of the events remains in the Neutron Wall after subtraction of the crosstalk pour rel<20° 10 < En < 30 MeV degrees in the NWall Without crosstalk correction With crosstalk correction PRELIMINARY

  10. Correlations subtracted from the cross-talk 10 < En < 30 MeV PRELIMINARY

  11. New neutron detector characteristics • No cross-talk! (think of the best protocol to remove it) • Variable thickness (two sets of detectors) • Large angular coverage (nuclear break-up, SPIRAL2) • Compact electronics • New materials!

  12. Efficiencies measured with Californium and calculated ? Seuil =100 keVee

  13. Exp E337 Neutron energy spectra 11Be 10Be + n +  @ 41 MeV/A 48Ti 10Be no- S2s = 0,47± 0,04 n-detectors TDSE calc. 2s 48Ti  11Be Château de cristal 3m incoincidence 10Be S1d= 0,50 ± 0,20 S1p= 3.9 SPEG 4*1p 0.5*1d TDSE Calculation non-perturbative V.Lima et al., Bormio 2004 V.Lima, Ph.D. Paris XI, oct 2004 V.Lima et al., in preparation

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