Probing Light Neutron-Rich Systems Nigel Orr Group “Exotiques” LPC-Caen for the DEMON-CHARISSA Collaboration.

Probing Light Neutron-Rich Systems Nigel Orr Group “Exotiques” LPC-Caen for the DEMON-CHARISSA Collaboration

… toujours la même chose avec lui … mieux vaut peut-être rester ici avec mon ballon de rouge

1.Motivation 2.Breakdown in the N=8 shell closure - 12 Be 3.Structure beyond the driplines 1.Spectroscopy of 13 Be 2.N=4: 5 H, 4n 4.Conclusions & Perspectives... Probing Light Neutron-Rich Systems

Structure of light, very neutron-rich systems... 10 Li A Z = core+xn  correlations/clustering … driplines and beyond experimentally accessible ab initio calculations tractable, Shell Model in Continuum,... 9 He 4n4n

Jean-Luc Lecouey, Seminar N=8 shell closure - 12 Be ? * psd-shell ordering in 12 Be? psd-shell ordering in 12 Be? 1s 1/2 1p 3/2 11 Be 0 0.32 1/2 + 1/2 -- [1p 1/2 ] 2 [2s 1/2 ] 2 pn 1.80 5/2 + [1d 5/2 ] 2 n-threshold  Figure courtesy Jeff Tostevin, UNiS * nb: first proposed by Fred Barker [J. Phys. G (1976) ]

Jean-Luc Lecouey, Seminar High-Energy, Single-Nucleon Removal 1.  -1n ~ 10-100mb,  s ~ 100 mg/cm2 2. forward focussing p0p0 core+1N Target core T+1N d  / dp  REVIEW: Hansen, Tostevin, Ann. Rev. Nucl. Part. Sci. (2003)  E x core  d  /dp  n  -1n (J  core )  C 2 S

Jean-Luc Lecouey, Seminar * A. Navin et al., PRL (2000) G. Gori et al., PRC (2004) C 2 S ( p 1/2 )  0.4     C 2 S ( s 1/2 )  0.5 C 2 S ( d 5/2 ) = ??  p 1/2 ) 2,  s 1/2 ) 2,  d 5/2 ) 2  30%, 20%, 50% p 1/2 ) 2,  s 1/2 ) 2,  d 5/2 ) 2  30%, 20%, 50% N=8 shell closure: C( 12 Be, 11 Be  ) @ 78 MeV/nucleon *  expt vs  Glauber  E  =320 keV

Jean-Luc Lecouey, Seminar N=8 shell closure - 12 Be (d 5/2 ) 2 admixture psd-shell ordering in 12 Be? psd-shell ordering in 12 Be? 1s 1/2 1p 3/2 11 Be 0 0.32 1/2 + 1/2 -- [1p 1/2 ] 2 [2s 1/2 ] 2 pn 1.80 5/2 + [1d 5/2 ] 2 n-threshold  10 Be+n Figure courtesy Jeff Tostevin, UNiS

Jean-Luc Lecouey, Seminar Single-Nucleon Removal to Unbound States/Nuclei: “Complete Kinematics” T+1N Target v core vnvn v0v0 v0v0 p core+n = p core + p n E rel =  (v core - v n ) 2 /2  core-n p core+n = p core + p n E rel =  (v core - v n ) 2 /2  core-n

Jean-Luc Lecouey, Seminar Neutrons  DEMON 90 modules ( NE213 )  ToF & position   n ~ 10%  nn ~ 1% + Cross-talk Rejection !! Experimental Setup “Complete Kinematics” Fragment  CHARISSA 16 x Si-Si–CsI Identification (  E-E)  Position (~1mm)  Energy (~1%)

Jean-Luc Lecouey, SeminarResolution Experimental Response Function * Complex geometry  simulations Efficiency * CHARISSA+DEMON @ ~30-40 MeV/nucleon  nn FWHM ~ 0.3 E d 1/2 nnnn

Jean-Luc Lecouey, Seminar Benchmark System - 7 He E r =0.44,  0 =0.16 MeV (g.s.)

Jean-Luc Lecouey, Seminar N=8 shell closure: C( 12 Be, 10 Be+n) @ 41 MeV/nucleon LPC-CHARISSA-DEMON S. Pain, W.N. Catford, N.A. Orr et al. Counts E x ( 11 Be) MeV 5/2 + 3/2 - 5/2 - E x ( 11 Be) = E rel ( 10 Be+n) + S n

Jean-Luc Lecouey, Seminar N=8 shell closure: C( 12 Be, 10 Be+n) @ 41 MeV/nucleon LPC-CHARISSA-DEMON S. Pain, W.N. Catford, N.A. Orr et al. E x ( 11 Be) MeV  (5/2 + ) = 23±5 mb  C 2 S ( d 5/2 )  0.4 * 5/2 + 3/2 - 5/2 - Counts * J.A. Tostevin : Preliminary

Core-n correlations: modelling two-neutron halo systems

3-body systems  n-n and core-n interactions

Core-n correlations: modelling two-neutron halo systems 3-body systems  n-n and core-n interactions 14 Be  12 Be-n interaction  spectroscopy of 13 Be

VfVf VnVn V f -V n Target 14 B 13 Be  12 Be+n Single-Proton Removal: C( 14 B, 12 Be+n) @ 41 MeV/nucleon projectile neutron configuration preserved projectile neutron configuration preserved  Final states populated: s 1/2 and d 5/2 s 1/2 and d 5/2

C( 14 B, 12 Be+n) @ 41 MeV/nucleon LPC Group “Exotiques” - JL Lecouey et al. E d (MeV)

LPC Group “Exotiques” - JL Lecouey et al. s-wave resonance E r  0.7 MeV  0  2 MeV E d (MeV) C( 14 B, 12 Be+n) @ 41 MeV/nucleon

LPC Group “Exotiques” - JL Lecouey et al. s-wave resonance E r  0.7 MeV  0  2 MeV d-wave resonance E r = 2.5 MeV  0 = 0.4 MeV E d (MeV) C( 14 B, 12 Be+n) @ 41 MeV/nucleon

Jean-Luc Lecouey, Seminar Angular Correlations: C( 14 Be, 12 Be+n) @ 287 MeV/u * * H. Simon et al., priv. comm. 14 Be 13 Be 12 Be n1n1 n2n2

13 Be: Experiment-Theory

13 Be : E x ~ 2.5 MeV d 5/2

13 Be: Experiment-Theory 13 Be ground state: s 1/2 resonance (?)

13 Be: Experiment-Theory 13 Be : p 1/2 E x ??

Jean-Luc Lecouey, Seminar 5 H : correlations beyond the dripline 1.most neutron-rich system known - N/Z=4 2.extreme test of models 3.n-n correlations beyond the dripline 4.contradictory observations...

Jean-Luc Lecouey, Seminar 5 H : correlations beyond the dripline 1.most neutron-rich system known - N/Z=4 2.extreme test of models 3.n-n correlations beyond the dripline 4.contradictory observations... p( 6 He,pp) @ 36 MeV/u Korsheninnikov et al., PRL (2000) t(t,ptn) @ 19 MeV/u Golovkov et al., PLB (2004)

Jean-Luc Lecouey, Seminar C( 6 He,t+n+n)X @ 30 MeV/nucleon Correlations beyond the dripline: 5 H Group Exotiques - G. Normand et al.

Jean-Luc Lecouey, Seminar C( 6 He,t+n+n)X @ 30 MeV/nucleon Uncorrelated t+n+n/no FSI Correlations beyond the dripline: 5 H Group Exotiques - G. Normand et al. (“event mixing”)

Jean-Luc Lecouey, Seminar C( 6 He,t+n+n)X @ 30 MeV/nucleon Uncorrelated t+n+n/no FSI Correlations beyond the dripline: 5 H E r =1.8 ±0.2 MeV  0 =2.1 ± 0.5 MeV Group Exotiques - G. Normand et al.

Jean-Luc Lecouey, Seminar 1p 3/2 1s 1/2 pn Single-proton Removal from 6 He 1s 1/2 1p 3/2 6 He 5H5H5H5H -1p J=0+J=0+

Jean-Luc Lecouey, Seminar 1p 3/2 1s 1/2 pn Single-proton Removal from 6 He 1s 1/2 1p 3/2 6 He 5H5H5H5H -1p J=0+J=0+ J  =1/2 + [g.s.]  1s 1/2  1p 3/2 ) 2 j=0 +  1s 1/2  1p 3/2 ) 2 j=2 + J  =3/2,5/2 +

Jean-Luc Lecouey, Seminar 5 H: Comparison 3-body theory * * 3-BODY MODEL: Shul ’gina et al.,PRC61(00)014312 1/2 + 3/2 + 5/2 + 1/2 + (plane wave/ (plane wave/ no FSI) Cross-talkincluded Cross-talkeliminated

Jean-Luc Lecouey, Seminar Meister et al., NUPA723(03)13 3-BODY MODEL: Shul ’gina et al., PRC61(00)014312 C( 6 He,t+n+n) @ 240 MeV/nucleon

Jean-Luc Lecouey, Seminar Two-Neutron Intensity Interferometry: HBT Effect FM Marqués et al., PLB (2000) Correlation Function - C nn

Jean-Luc Lecouey, Seminar 5 H Decay: t+n+n Dalitz plot analysis * * Dalitz plots and 3-body correlations in breakup F.M. Marqués et al., PRC64(01)233 Group Exotiques G. Normand et al.

Jean-Luc Lecouey, Seminar 4 H: C( 6 He,t+n)X @ 30 MeV/u E r  1.9 MeV  0  3.2 MeV Group Exotiques - G. Normand et al.    60 fm/c

Jean-Luc Lecouey, Seminar 5 H: C nn + Gaussian Source RMS r nn = 5.5 ± 1.7 fm deuteron r np  3.8 fm Group Exotiques - G. Normand et al.

Jean-Luc Lecouey, Seminar * P. Regan (on numerous occassions after a few beers) “ … and what about the tetraneutron ?? ” * 1.Clustering within nuclei  can free A n exist ? 1.Beyond 2 n (S n ~ -70keV) 4 n most likely 1. 4 He(  -,  + ), 7 Li( 11 B, 14 O) …  New approach * P. Regan (on numerous occassions after a few beers) “ … and what about the tetraneutron ?? ” * 1.Clustering within nuclei  can free A n exist ? 1.Beyond 2 n (S n ~ -70keV) 4 n most likely 1. 4 He(  -,  + ), 7 Li( 11 B, 14 O) …  New approach

Jean-Luc Lecouey, Seminar Production: 14 Be (35 MeV/u) + C  10 Be + 4 n S n ( 14 Be) = 5.2 MeV

Jean-Luc Lecouey, Seminar Detection à la Chadwick

Jean-Luc Lecouey, Seminar Detection à la Chadwick Detection via breakup

Jean-Luc Lecouey, Seminar Detection à la Chadwick Detection via breakup Single-neutron response FM Marqués et al., PRC (2002)

Jean-Luc Lecouey, Seminar Results: 14 Be + C  A Be + x n FM Marqués et al., PRC (2002)

Jean-Luc Lecouey, Seminar Results: 8 He + C  A He + x n Group Exotiques: V. Bouchat et al. CHARISSA-DEMON

Jean-Luc Lecouey, Seminar Results: 8 He + C  A He + x n Group Exotiques: V. Bouchat et al. CHARISSA-DEMON PRELIMINARY

Jean-Luc Lecouey, Seminar... 4 n as a (low-lying) resonance ? 1.Not considered in original background/pileup estimates 1.Resonance does not live long enough to reach DEMON...  Focusing of neutrons from decay of 4 n from decay of 4 n  compatible with signal  compatible with signal but C 2 S, E,  … ?? but C 2 S, E,  … ??

Conclusions New reaction probe - high-energy nucleon removal - and analysis techniques to explore structure and correlations at and beyond the driplineNew reaction probe - high-energy nucleon removal - and analysis techniques to explore structure and correlations at and beyond the dripline  N=8 not a closed shell for 12 Be (nor for 11 Li)  N=9 s 1/2 - d 5/2 inversion for 13 Be ( 14 B, 15 C) … 14 Be halo  5 H : broad J  = 1/2 + g.s. (??  i   f )

Jean-Luc Lecouey, Seminar N=4 4 n : d( 8 He, 6 Li) MUST@SPIRAL (see S.F. talk) DEMON: C( 8 He,  4 n) preliminary results DEMON: C( 8 He,  4 n) preliminary results C( 15 B, 10 Be 4 n) autumn 2005 C( 15 B, 10 Be 4 n) autumn 2005 N=7 5 H : different  i … p( 8 He,  ) MUST@SPIRAL Perspectives 9 He : spectroscopy with different  i C( 11 Be, 8 He+n)  s 1/2 C( 11 Be, 8 He+n)  s 1/2 C( 14 B, 8 He+n)  s 1/2  d 5/2 C( 14 B, 8 He+n)  s 1/2  d 5/2 N=9 12 Li : search for low-lying resonances C( 14 B, 11 Li+n)  s 1/2 / d 5/2 C( 14 B, 11 Li+n)  s 1/2 / d 5/2

Jean-Luc Lecouey, Seminar … questions ??

5 H: Conclusions & Perspectives C( 6 He,tnn) …  broad structure E d ~ 2 MeV (no narrow  )  “consistent” with 3-body model J  g.s. = 1/2 +  reasonable agreement with GSI C( 6 He,tnn)  poorer agreement with RIKEN p( 6 He,pp)  rms R nn  6 fm “Moral of the story *”...  i  REACTION  f  2005...  p( 8 He,  ) MUST@SPIRAL [ P. Roussel-Chomaz et al. ] * see also Grigorenko, EPJ (2004) * see also Grigorenko, EPJ (2004)

STOP PRESS... “DEMON in Dubna” t(t,ptn) @ 19 MeV/u Golovkov et al. PRL 93 (04) 262501

Jean-Luc Lecouey, Seminar 12 Be+n Coincidences: Behaviour of virtual s-states a s =-20 fm Thoennessen et al., PRC 63 (2000) 014308

Jean-Luc Lecouey, Seminar Acceptance Effects  n < 5°

Jean-Luc Lecouey, Seminar G. Normand, Thèse, LPC (2004) A Be  9 He :  i   f 12 Be  9 He 11 Be  9 He [x4] 12 Be  9 He 12 Be  9 He s, p, d - states x4

Jean-Luc Lecouey, Seminar High-Energy, Single-Nucleon Removal 1.  -1n ~ 10-100mb,  s ~ 100 mg/cm2 2. forward focussing p0p0 core+1N Target core T+1N d  / dp  REVIEW: Hansen, Tostevin, Ann. Rev. Nucl. Part. Sci. (2003)  E x core  d  /dp  n  -1n (J  core )  C 2 S

Jean-Luc Lecouey, Seminar Single-Neutron Removal: p-sd shell Expt v ’s Glauber Theory + Shell Model: Sauvan, et al., PRC (2004) 43-68 MeV/nucleon 1-600 pps  -1n ~ 50 - 200 mb FWHM ~ 50 - 240 MeV/c

Jean-Luc Lecouey, Seminar N=8 shell closure - 12 Be? Closed p-shell in 12 Be Closed p-shell in 12 Be 1s 1/2 1p 3/2 pn 1p 1/2 Nucleons + potential courtesy Jeff Tostevin, Surrey

Jean-Luc Lecouey, Seminar Figure courtesy Jeff Tostevin, Surrey N=8 shell closure - 12 Be? psd-shell ordering in 12 Be? psd-shell ordering in 12 Be? 1s 1/2 1p 3/2 11 Be 0 0.32 1/2 + 1/2 -- [1p 1/2 ] 2 [2s 1/2 ] 2 -1n pn 1.80 5/2 + [1d 5/2 ] 2 n-threshold 2s 1/2  level inversion

Jean-Luc Lecouey, Seminar A. Navin et al., PRL (2000) N=8 shell closure: C( 12 Be, 11 Be  ) @ 78 MeV/nucleon  (1/2 - ) = 18±3 mb      (1/2 + ) = 32±5 mb

Jean-Luc Lecouey, Seminar C 2 S ( p 1/2 )  0.4     C 2 S ( s 1/2 )  0.5 N=8 shell closure: C( 12 Be, 11 Be  ) @ 78 MeV/nucleon  expt vs  Glauber  A. Navin et al., PRL (2000)

Probing Light Neutron-Rich Systems Nigel Orr Group “Exotiques” LPC-Caen for the DEMON-CHARISSA Collaboration.

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Probing Light Neutron-Rich Systems Nigel Orr Group “Exotiques” LPC-Caen for the DEMON-CHARISSA Collaboration.

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Presentation on theme: "Probing Light Neutron-Rich Systems Nigel Orr Group “Exotiques” LPC-Caen for the DEMON-CHARISSA Collaboration."— Presentation transcript:

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