Search for unbound excited states of proton rich nuclei SAMURAI WS@RIKEN 9-10 March 2011 Search for unbound excited states of proton rich nuclei Naohito IWASA Department of Physics, Tohoku University

Motivation E(21+) and B(E2) in even-even nuclei 46Fe 48Fe E(21+) and B(E2) in even-even nuclei collectivity/shell structure Systematical　studies 　magicity disappearance around 32Mg-32Ne → new magic number N=14, 16 in 22,24O 　B(E2) anomaly of 16,18C Isotope E(2+) B(E2;↑) 42Cr 44Cr 46Cr 0.892 900±10 40Ti 42Ti 1.55 870±250 44Ti 1.08 650±160 preliminary 36Ca 3.02 （71±13) 36Ca 3.02 38Ca 2.21 96±21 40Ca 3.90 99±17 42Ca 1.52 420±30 32Ar 1.82 266±68 34Ar 2.09 240±40 36Ar 1.97 300±30 38Ar 2.17 130±10 40Ar 1.46 330±40 24Si, 28S (Tz=-2): small B(E2) 　 0gs+→21+: neutrons plays important role 　 subshell closure (Z=14,16) effect? 　 E(21+) are not high: not magic. 36Ca: B(E2): smallest in Ca isotopes 　 E(21+): 0.3MeV smaller than that of mirror nucleus 36S. 28S 1.51 28S 1.51 (102±16) 30S 2.21 324±41 32S 2.23 300±13 34S 2.13 212±12 36S 3.29 104±28 38S 1.29 235±30 22Si 24Si 1.88 (60±20) 24Si 1.88 (60±20) 26Si 1.80 356±34 28Si 1.78 326±12 30Si 2.24 215±10 32Si 1.94 113±33 34Si 3.33 85±33 36Si 1.40 190±60 20Mg 1.61 177±32 22Mg 1.25 370±130 24Mg 1.37 432±11 26Mg 1.81 305±13 28Mg 1.47 350±50 30Mg 1.48 295±26 32Mg 0.885 454±78 34Mg 0.656 631±126 18Ne 1.89 176±30 20Ne 1.63 340±30 22Ne 1.28 230±10 24Ne 1.98 170±60 26Ne 2.02 228±41 28Ne 1.32 132±23 30Ne 0.79 32Ne 0.72 16O 6.92 41±4 18O 1.982 45±2 20O 1.67 28±2 22O 3.17 21±8 24O 4.72 14C 7.01 18±3 16C 1.77 2.7±0.7 18C 1.62 4.3±1.0 20C 1.59 22C

Proposals Search for unbound excited states in Tz=-3 nuclei. 46Fe 48Fe Search for unbound excited states in Tz=-3 nuclei. Coulomb dissociation of 22Si Search for 01+ and 21+ states in 34Ca using 2n-knockout reaction of 36Ca Proton inelastic scattering of 42Cr, 48Fe Isotope E(2+) B(E2;↑) 42Cr 44Cr 46Cr 0.892 900±10 40Ti 42Ti 1.55 870±250 44Ti 1.08 650±160 34Ca 36Ca 3.02 （71±13) 38Ca 2.21 96±21 40Ca 3.90 99±17 42Ca 1.52 420±30 32Ar 1.82 266±68 34Ar 2.09 240±40 36Ar 1.97 300±30 38Ar 2.17 130±10 40Ar 1.46 330±40 28S 1.51 (102±16) 30S 2.21 324±41 32S 2.23 300±13 34S 2.13 212±12 36S 3.29 104±28 38S 1.29 235±30 22Si 24Si 1.88 (60±20) 26Si 1.80 356±34 28Si 1.78 326±12 30Si 2.24 215±10 32Si 1.94 113±33 34Si 3.33 85±33 36Si 1.40 190±60 20Mg 1.61 177±32 22Mg 1.25 370±130 24Mg 1.37 432±11 26Mg 1.81 305±13 28Mg 1.47 350±50 30Mg 1.48 295±26 32Mg 0.885 454±78 34Mg 0.656 631±126 18Ne 1.89 176±30 20Ne 1.63 340±30 22Ne 1.28 230±10 24Ne 1.98 170±60 26Ne 2.02 228±41 28Ne 1.32 132±23 30Ne 0.79 32Ne 0.72 16O 6.92 41±4 18O 1.982 45±2 20O 1.67 28±2 22O 3.17 21±8 24O 4.72 14C 7.01 18±3 16C 1.77 2.7±0.7 18C 1.62 4.3±1.0 20C 1.59 22C

Coulomb dissociation of 22Si B(E2↑)～200e2fm4: 16O+6p B(E2↑)<100e2fm4: Z=14 subshell closure is significant To determination of E(21+) and B(E2) in 22Si, we propose Coulomb dissociation experiment. Z=14(subshell), N=8(magic) Sp=1.2 MeV No excited states are known Mirror 22O: E(21+)=3.17MeV N=14 in 22O: new magic number. 22Si 3.xx ? ??? 24Si 1.88 (60±20) 24Si 1.88 60±20? 26Si 1.80 356±34 28Si 1.78 326±12 30Si 2.24 215±10 32Si 1.94 113±33 34Si 3.33 85±33 36Si 1.40 190±60 g Doppler corrected g energy energy of excited states Excitation 20Mg invariant mass 22Si breakup virtual photon 2protons charged particles Pb

Coulomb dissociation of 22Si If excited states in 21Al exist between 1.4～2.0MeV, 18Ne+4p channel 3.17 2+ 2.55 2.25 19Na+3p 18Ne+4p Coulex 1.5 1.2 21Al+p -0.1 0+ 20Mg+2p 22Si 22O Measurement of all the channel →　excitation cross section can be measured

Proposals Search for unbound excited states in Tz=-3 nuclei. 46Fe 48Fe Search for unbound excited states in Tz=-3 nuclei. Coulomb dissociation of 22Si Search for 01+ and 21+ states in 34Ca using 2n-knockout reaction of 36Ca Proton inelastic scattering of 42Cr, 48Fe Isotope E(2+) B(E2;↑) 42Cr 44Cr 46Cr 0.892 900±10 40Ti 42Ti 1.55 870±250 44Ti 1.08 650±160 34Ca 36Ca 3.02 （71±13) 38Ca 2.21 96±21 40Ca 3.90 99±17 42Ca 1.52 420±30 32Ar 1.82 266±68 34Ar 2.09 240±40 36Ar 1.97 300±30 38Ar 2.17 130±10 40Ar 1.46 330±40 28S 1.51 (102±16) 30S 2.21 324±41 32S 2.23 300±13 34S 2.13 212±12 36S 3.29 104±28 38S 1.29 235±30 22Si 24Si 1.88 60±20? 26Si 1.80 356±34 28Si 1.78 326±12 30Si 2.24 215±10 32Si 1.94 113±33 34Si 3.33 85±33 36Si 1.40 190±60 20Mg 1.61 177±32 22Mg 1.25 370±130 24Mg 1.37 432±11 26Mg 1.81 305±13 28Mg 1.47 350±50 30Mg 1.48 295±26 32Mg 0.885 454±78 34Mg 0.656 631±126 18Ne 1.89 176±30 20Ne 1.63 340±30 22Ne 1.28 230±10 24Ne 1.98 170±60 26Ne 2.02 228±41 28Ne 1.32 132±23 30Ne 0.79 32Ne 0.72 16O 6.92 41±4 18O 1.982 45±2 20O 1.67 28±2 22O 3.17 21±8 24O 4.72 14C 7.01 18±3 16C 1.77 2.7±0.7 18C 1.62 4.3±1.0 20C 1.59 22C

Search for 01+ and 21+ states in 34Ca MED=E(2+;Tz=-T)-E(2+;Tz=T) Standard shell model: zero MED exp. : |MED|≦0.1MeV extremely large MED of 14O, 36Ca 21+ states are unbound 36Ca The extremely large MED can be reproduced by shell model calc. with the sd shell isospin symmetric interaction USD using experimental proton and neutron SPE from the　 A = 17, T = 1/2 isospin doublet. 36Ca 14O The new shell model predicted that the island of inversion in proton rich region may start at N = 14 in 34Ca. Is Isospin violated ? Experimental determination of E(2+) and B(E2) of 34Ca are desired. P. Doornenbal et al., PLB 647 (2007) 237 Small correction of Z=14, N=14 gap P. Doornenbal et al., PLB 647 (2007) 237

Search for 01+ and 21+ states in 34Ca Mass formula (AUDI1995) g.s. of 34Ca is bound, but 34Ca is not found yet. Upper limit of the half life was measured to be 35ns at GANIL. 34Ca might have diproton radioactivity?? Coulomb diss. meth. cannot be used. x B(E2) We propose to measure the mass and E(21+) of 34Ca using 2n knockout reaction of 36Ca. 0.9 33K+p -0.7 34Ca ? 32Ar+2p 32Ar 2n knockout 34Ca 36Ca 36Ca breakup 9Be 2 protons 2 neutrons

Search for 01+ and 21+ states in 34Ca 36Ca + 9Be →34Ca*(gs, 2+)→32Ar+2p Mass of 34Ca can be determined. Mass of 33K is expected to be determined. E(21+) is expected to be measured. 9Be(36Ca,34Ca) 2+ g? 0.9 33K+p 0+ -0.7 34Ca not found seems to be unbound 2 proton decay 32Ar+2p E(21+) =～3MeV→34Ca is not in island of inversion ～1MeV→34Ca is in island of inversion

Proposals Search for unbound excited states in Tz=-3 nuclei. 46Fe 48Fe Search for unbound excited states in Tz=-3 nuclei. Coulomb dissociation of 22Si Search for 01+ and 21+ states in 34Ca using 2n-knockout reaction of 36Ca Proton inelastic scattering of 42Cr, 48Fe Isotope E(2+) B(E2;↑) 42Cr 44Cr 46Cr 0.892 900±10 40Ti 42Ti 1.55 870±250 44Ti 1.08 650±160 36Ca 3.02 （71±13) 38Ca 2.21 96±21 40Ca 3.90 99±17 42Ca 1.52 420±30 32Ar 1.82 266±68 34Ar 2.09 240±40 36Ar 1.97 300±30 38Ar 2.17 130±10 40Ar 1.46 330±40 28S 1.51 (102±16) 30S 2.21 324±41 32S 2.23 300±13 34S 2.13 212±12 36S 3.29 104±28 38S 1.29 235±30 22Si 24Si 1.88 60±20? 26Si 1.80 356±34 28Si 1.78 326±12 30Si 2.24 215±10 32Si 1.94 113±33 34Si 3.33 85±33 36Si 1.40 190±60 20Mg 1.61 177±32 22Mg 1.25 370±130 24Mg 1.37 432±11 26Mg 1.81 305±13 28Mg 1.47 350±50 30Mg 1.48 295±26 32Mg 0.885 454±78 34Mg 0.656 631±126 18Ne 1.89 176±30 20Ne 1.63 340±30 22Ne 1.28 230±10 24Ne 1.98 170±60 26Ne 2.02 228±41 28Ne 1.32 132±23 30Ne 0.79 32Ne 0.72 16O 6.92 41±4 18O 1.982 45±2 20O 1.67 28±2 22O 3.17 21±8 24O 4.72 14C 7.01 18±3 16C 1.77 2.7±0.7 18C 1.62 4.3±1.0 20C 1.59 22C

Search for 21+ states in 42Cr, 46Fe 42Cr: Z=24, N=18 40Ca+4p-2n Sp=1.11MeV(mass formula) No excited states are known. Mirror 42Ar: E(2+)=1.21MeV 46Fe: Z=26, N=20(magic) 40Ca+6 protons configuration? Sp=1.42MeV (mass formula) No excited states are known. Mirror 46Ca: E(2+)=1.35MeV 2.48 2+ 2.57 4+ (3-,4+) 2.41 2.42 0+ (1.42) 1.21 1.35 (1.11) 2+ 2+ 45Mn+p 41V+p 0.360 40Ti+2p 0+ 44Cr+2p 0+ 42Cr 42Ar 46Fe 46Ca

Experimental Setup High resolution mode of SAMURAI. DALI 2 for g measurement Pb, Be Liq. H2targets 22Si, 36Ca,… 3×2 SSD (xyu, xyv) ICF, FDC, plastic PDC, plastic 2 protons 20Mg, 32Ar,… SSD should be in vac. chamber. →breakup events and breakup positions are identified Focus: good mass res. Less influence of MS Target chamber, SSD and SSD chamber should be constructed.

Yield estimation 22Si @250AMeV 100cps from 100pnA 36Ar @400AMeV 100cps from 33pnA 28Si @400AMeV Assuming σCx～10mb at 250AMeV 34Ca @ 250AMeV 3kcps 36Ca from 40pnA 40Ca @400AMeV purity ～20% limit: 2kcps 2n knockout cross section: 0.1mb target 100mg/cm2 thick 9Be efficiency: 40% (Erel=3～4MeV) 48events/day～330 events/week Target 200mg/cm2 thick Pb 22Si+Pb→20Mg+2p coincidence efficiency 40% (Erel～3MeV, rough*) 20 events/day ～ 140 events/week *We use simulation results of 7Be+p coincidence efficiency of KaoS at GSI.

Yield estimation for 42Cr, 46Fe 42Cr @250AMeV 0.04cps from 30pnA 84Kr @345AMeV 10 times higher intensity beam is available*, (p,p’) measurement is possible. 0.4cps 42Cr beam Target 200mg/cm2 Liq. H2 σ= 5mb, 80% coin.eff . 16 events/d = 116 events/week g eff.: 20% 29 events/week 46Fe@250AMeV 0.007cps from 30pnA 84Kr @345AMeV 60 times higher intensity beam is available*, (p,p’) measurement is possible. 0.4cps 46Fe beam Target 200mg/cm2 Liq. H2 σ= 5mb, 80% coin. eff. 16 events/d = 116 events/week g eff.: 20% 29 events/week * 1pmA 84Kr beam will be available. For B(E2) measurement, intensity of several ten particle/sec is necessary.

Summary Coulomb dissociation reaction, knockout reaction and proton inelastic scattering are powerful tool to study collectivity and nuclear structure. Coulomb dissociation of 22Si into 20Mg+2p may provide information on Z=14 subshell closure near the drip line. From an experiments of 2n knockout reaction of 36Ca, mass and E(2+) of 34Ca are expected to be determined. The question why 34Ca is not found is expected to be solved. Proton inelastic scattering experiments of 42Cr and 46Fe can be performed when high-intensity 84Kr beam is available.