SUNFLOWER --- In-beam Gamma-ray spectroscopy at RIBF He Wang RIKEN Nishina Center The 9 th Japan-China Joint Nuclear Physics Symposium (JCNP 2015), November 7-12, 2015, Osaka University
Content Introduction to SUNFLOWER Experiment details Selected results Perspective
SUNFLOWER S pectroscopy of U nstable N uclei with F ast and s LOW beam E xperiments at R IBF http://www.nishina.riken.jp/collaboration/SUNFLOWER
Function The collaboration offers a forum of discussion and information exchanges. --- Proposals may be amended after consulting with the SUNFLOWER members in advance of the PAC meeting. Arranges the tasks and resources necessary to accomplish experiments. --- The spokes persons of proposed experiments may ask members of SUNFLOWER to collaborate. Provides technical information and consults regarding the utilization of non-standard detectors. Coordinates research programs and equipment use. --- Arranges experimental campaigns. Mediates between conflicting experiments when similar subjects are proposed. Discusses the strategy of detector developments.
SUNFLOWER experiments 2008 Dayone/ 48 Ca 32 Ne H. Scheit, P. Doornenbal PRL 103(2009)032501 31,33 Na H. Scheit, P. Doornenbal PRC 81(2010)041305 2009 48 Ca 32 Mg K. Li, H. Scheit CPL 29(2012)102301, PRC 92(2015)014608 2010 48 Ca ~ 42 Si S. Takeuchi, M. Matsushita PRL 109(2012)182501 36,38 Mg P. Doornenbal, H. Scheit PRL 111(2013)212502 29 F P. Doornenbal ~Al, P D. Steppenbeck 33 Mg D. Bazin 40 Mg test P. Fallon, H.L.Crawford PRC 89(2014)041303 31 Ne, 22 C T. Nakamura, N. Kobayashi PRL 103(2009)262501, PRL 112(2014)142501, PRC 86(2012)054604 2011 238 U 78 Ni K. Yoneda ~ 132 Sn HW, N. Aoi PRC 88(2013)054318, PTEP 2014:023D02, CPL 30(2013)042501 2012 124 Xe/ 70 Zn 10x Sn A. Obertelli, P. Doornenbal PLB 743(2015) 451, PRC 90(2014)061302 54 Ca D. Steppenbeck, S. Takeuchi Nature 502(2013)207, PRL 114(2015) 252501 2013 238 U 74 Ni G. de Angelis 2014 238 U 130 Cd HW, N. Aoi SEASTAR P. Doornenbal, A. Obertelli PRL 115(2015)192501 2015 238 U/ 78 Kr 73,77 Cu E. Sahin, Z.Y. Xu, G. de Angelis 136 Te A. Jungclaus, P. Doornenbal SEASTAR P. Doornenbal, A. Obertelli 70,72 Kr W. Korten, P. Doornenbal
SUNFLOWER workshops 2015/9/30 4th SUNFLOWER Workshop Osaka University Osaka, JAPAN 2014/9/15,16 3rd SUNFLOWER Workshop University of Tokyo Tokyo, JAPAN 2013/9/10 SUNFLOWER Workshop TU Darmstadt Darmstadt, GERMANY 2013/2/20 SUNFLOWER - In-beam gamma and MINOS mini-WS RIKEN Nishina Center, Wako, JAPAN
RI Beam Factory
RI Beam Factory Primary beam intensity Primary beam intensity records 78 Kr Superconducting Ring Cyclotron (SRC) 35 pnA U @ Oct. 2015 H. Okuno, et al., Prog. Theor. Exp. Phys. (2012) 03C002. Heavy ion beams (up to U) of 345 A MeV at SRC Fast RI beams by projectile fragmentation and U-fission at BigRIPS
New isotope search at RIBF More than 120 species T.Ohnishi, T.Kubo et al., JPSJ 77 (2008) 083201. T.Ohnishi, T.Kubo et al., JPSJ,79 (2010) 073201.
Experiment RI Beam Factory : BigRIPS and ZeroDegree BigRIPS/ZeroDegree
Nuclear reactions with Fast beams Reacted beam target beam Fast beam and thick target -- Increased luminosity -- Event-by-event identification -- Gamma-ray spectroscopy on the exotic nuclei
Experimental setup Reacted beam target beam Primary beam Production target Tagging BigRIPS ZeroDegree
BigRIPS fragment separator BigRIPS separator 1 st stage
BigRIPS fragment separator BigRIPS separator 2 nd stage
ZeroDegree spectrometer F11 F8
Experimental setup Ejectile PID@ZeroDegree Projectile PID@BigRIPS DALI2 Array 55 Sc 54 Ca Atomic number Z Atomic number Z Mass-to-charge ratio A/Q 238 U Mass-to-charge ratio A/Q Production target Tagging 2 nd target BigRIPS ZeroDegree
Experimental setup@F8 186 NaI(Tl) detectors θ coverage 11 to 165 degrees ZeroDegree Spectromete r DALI2 Array Inside F8 S. Takeuchi, et al., NIMA, 763:596, 2014.
In-beam γ spectroscopy Doppler correction E cm = γ E lab (1- b cos( θ lab )) 32 Mg( p , p ’) b ≈ 0.3 (a) Laboratory frame Energy (keV) (b) Projectile frame 160 ° 20 ° H.Hasegawa, Master’s thesis, Rikkyo Univ., 2003 Emission angle of g rays
In-beam γ spectroscopy Doppler correction E cm = γ E lab (1- b cos( θ lab )) Δ θ = 8 o b = 0.6 Δ b =10% Δ E int =7.5% Efficiency ≈ 20% ΔE/E ≈15% (FWHM) (@1 MeV γ -ray, b ≈ 0.6)
Region of Interest ~ 132 Sn ~ 100 Sn ~ 78 Ni N =34 in 54 Ca Magic number Collectivity: B (E2) Type of Collectivity: E x (2 + ) / E x (4 + ) Single Particle level: E x , J π Island of Inversion
N =28 in Mg( Z =12) and Si( Z =14) E x (2 + ) is an indicator of “ magicity ” 32 Mg 20 34 Mg 30 Ne 28 8 Island of Inversion 32 Mg: T. Motobayashi et al. , PLB 346, 9 (1995). 31 F: H. Sakurai et al. , PLB 448, 180 (1999). 34 Mg: K. Yoneda et al. , PLB 449, 233 (2001). 30 Ne: Y. Yanagisawa et al. , PLB 556, 84 (2003).
N =28 in Mg( Z =12) and Si( Z =14) Counts / 25 keV Counts / 25 keV 60 2 All M 38 10 g 38 Mg Mg 37 36 C( Al, Mg), M <3 40 38 C( Si, Mg) g 40 80 2 M <4 10 g 656(6) All M 662(6) g 20 36 Mg 10 60 60 39 38 C( Al, Mg) 1370(20) 40 1 0 1000 10 40 All M 1360(20) g 20 0 1000 2000 20 1 32 Mg 20 34 Mg 0 10 0 1000 2000 3000 V 0 1000 2000 3000 4000 Energy (keV) Energy (keV) 14 12 36,38 Mg: 28 10 P. Doornenbal, et al. , 8 PRL 111, 212502 (2013). Island of Inversion 48 Ca primary beam~70 pnA 40 Si: 3000 pps, 230 MeV/u 39 Al: 110 pps, 220 MeV/u F8 target: nat.C, 2.54 g/cm2
N =28 in Mg( Z =12) and Si( Z =14) Counts / 25 keV Counts / 25 keV 60 2 All M 38 10 g 38 Mg Mg 37 36 C( Al, Mg), M <3 40 38 C( Si, Mg) g 40 80 2 M <4 10 g 656(6) All M 662(6) g 20 36 Mg 10 60 60 39 38 C( Al, Mg) 1370(20) 40 1 0 1000 10 40 All M 1360(20) g 20 0 1000 2000 20 1 32 Mg 20 34 Mg 0 10 0 1000 2000 3000 V 0 1000 2000 3000 4000 Energy (keV) Energy (keV) 14 12 42 Si: 28 10 42 Si S. Takeuchi et al. , 8 PRL 109, 182501 (2012). Island of Inversion 48 Ca primary beam~70 pnA 44 S: 40000 pps, 210 MeV/u F8 target: nat.C, 2.54 g/cm2
N =28 in Mg( Z =12) and Si( Z =14) 5 E x (2 + ) (MeV) + 2 Si SDPF-M Sound magicity 1 + [MeV] 4 Si SDPF-MU Mg 1 + 2 Mg 34 Si SDPF-U-MIX in Si @ N = 20 4 1 + 4 Mg 3DAMP+GCM x 1 Si E Magicity disappeared 3 in Si @ N = 28 + 4 1 Magicity disappeared 2 32 Mg in Mg @ N = 20 42 Si + 1 2 1 4/2 Large collectivity R 4/2 R 3 in Si and Mg @ N ~28 Smooth transition in Si 2.5 R Si Almost identical in 34,36,38 Mg 4/2 R Mg 4/2 2 20 22 24 26 28 Neutron Number N
Appearance of new magic number 70 Zn primary beam ~100 pnA N =34 in 54 Ca Be( 55 Sc, 54 Ca*), Be( 56 Ti, 54 Ca*) F8 target: 9Be, 1.85 g/cm2 124 pps/pnA 56 Ti 12 pps/pnA 55 Sc 54 Ca Collectivity: B (E2) Type of Collectivity: E x (2 + ) / E x (4 + ) Single Particle level: E x , J π Island of Inversion D. Steppenbeck, S. Takeuchi, et al., Nature(London) , 502:207, 2013.
Nuclear structure around 100 Sn and 132 Sn ~ 132 Sn ~ 100 Sn ~ 78 Ni N =34 in 54 Ca Magic number Collectivity: B (E2) Type of Collectivity: E x (2 + ) / E x (4 + ) Single Particle level: E x , J π Island of Inversion
Nuclear structure in light and heavy Sn Constancy of E x (2 + ) A high 2 + state at N =82 Sudden drop at N =84 N =50 N =82
Neutron driven collectivity HFB+QRPA with Gogny D1M interaction, no model space limitation M.Martini, S.Peru and M.Dupuis, PRC 83 , 034309 (2011) 104 Sn( p,p ’ ) 0 + → 2 + 0 + → 2 + A. Corsi et al., PLB 743, 451 (2015) Neutron contribution dominant in the first 2 + state Reduction of neutron collectivity from 112 Sn to 104 Sn
Nuclear structure in light and heavy Sn What is the role of neutron in the neutron-rich Sn isotopes? Constancy of E x (2 + ) A high 2 + state at N =82 Sudden drop at N =84 N =50 N =82
Gamma-ray spectroscopy in 136 Sn Xe I Te Sb Sn 136 Sn In Cd Ag Pd 74 70 72 76 78 80 82 84 86 2 + state known 2 + state unknown
Particle Identification 136 Sn 50+ and 133 Sn 49+ Δ A/Q =136/50-133/49=5.7x10 -3 9 Be( 137 Sb, 136 Sn) A/Q resolution 2.7x10 -3 (rms) Projectile PID@BigRIPS Ejectile PID@ZeroDegree 137 Sb A+3 A A-1
Particle Identification 136 Sn 50+ and 133 Sn 49+ Δ A/Q =136/50-133/49=5.7x10 -3 9 Be( 137 Sb, 136 Sn) A/Q resolution 2.7x10 -3 (rms) Charge states ID by TKE Ejectile PID@ZeroDegree 136 Sn 50+ Q = Z Q = Z-1
The first 2 + state in 136 Sn One-proton removal reaction HW, N. Aoi et al., Prog. Theor. Exp. Phys. 2014, 023D02(2014)
PRL113, 132502 (2014) Systematics of E x (2 + ) Z =50 magicity in N =86 isotones Constant E x (2 + ) beyond N =82 Seniority scheme Asymmetric E x (2 + ) pattern around N =82 Mass number A Mass number A Present work ~500 keV
Possible reason Reduction of pairing? Δ (3) ( N )=(-1) N [ B ( N -1)+ B ( N +1)-2 B ( N )]/2 N <82 N >82 J. Hakala, et al., PRL 109, 032501(2012)
Future Beam intensity will continue increasing Expansion of region More elaborate measurements Higher excited states Low energy reactions (OEDO) New detectors LaBr 3 based Ge based (tracking array?)
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