Nuclear Structure Physics with Advanced Gamma- Detector Arrays, Padova June 10-12, 2013 Gamma spectroscopy in the fermium region at SHIP Stanislav Antalic Comenius University, Bratislava
Collaboration GSI Darmstadt F. P. Heßberger D. Ackermann S. Hofmann S. Heinz B. Kindler I. Kojouharov B. Lommel R. Mann B. Sulignano (presently in Saclay) Comenius University (Bratislava) S. Antalic Š. Šáro Z. Kalaninová B. Streicher (presently in GSI Darmstadt) University of Jyväskylä M. Leino JAEA Tokai K. Nishio Helmholtz Institut Mainz L.-L. Andersson 22. 6. 2013 Padova, 9th - 13th of June 2013 2
Transuranium nuclei Region accesible by present technique Production rate 1 event / week Desired region of double magic nuclei No chance to access it with present technique Region accessible for nuclear spectroscopy 10 1000 nuclei / hour Rich source for the nuclear structure data 22. 6. 2013 Padova, 9th - 13th of June 2013 3
Efficiency ~30 % Flight time ~ 1-2 ms SHIP separator Detectors: S. Hofmann and G. Münzenberg, RMP 72, 733 (2000) Separator: G.,Munzenberg, et al., NIM 161, 65 (1979) + high intensity beam + reliable setup + low background - Low granularity - Lack of beamtime Recoils Esc. a, b CE, RTG 48 Ca ~ 1200 pna e ff a Bi 2 O 3, PbS target 400 mg/cm 2 Rotating wheel 31 cm diameter B. Kindler et al. NIM A561,107 (2006) Back detector PSSD Ge-Clover 22. 6. 2013 Padova, 9th - 13th of June 2013 4
Fm Studies at SHIP since 2010 Topic for this talk 253 Fm single particle isomer 253 No K isomer Published data since 2010 Opened projects Bh Md Fm 0.18 s Md 0.35 s 8.64 8.68 243Fm 3 ms 0.9 ms 8.18 244Fm No Md 4.4 s 4.2 s 246 Md 1.0 s Rf Lr 1.12 0.26 s 8.74 8.56 e 8.42 245Fm 8.25 1.1 s 247Md 0.2 s Db Sg No 248Md e 8.32 20 8.36 e 8.03 246Fm 9.2 s 6 8.86 7 s 247Fm 35 s 7.87 7.93 0.25 ms 24 s 36 s Rf Lr 9.02 250No 2 µ s 714 783 249Md 7.87 e 7.83 7.53 48 ms 0.36 s 52 s Db 253Rf 252Lr 8.72 255Db Sg 256Db 2.9 ms 258Sg Mt Hs 0.48 s Ds Bh 259Sg 9.62 9.81 9.36 9.76 9.03 9.72 257Db 258Db 11.8 ms 261Bh 10.40 10.10 10.03 3.6 ms 8.0 ms 262 102 ms 10.08 10.37 10.24 9.74 260Sg 0.23 s 9.56 9.52 9.47 259Db Hs 10.43 261Sg 260Db Ds 3µs 267 11.60 Mt 1.7 ms 266 11.74... 10.46 264Hs 0.26 ms 6.1 ms 0.8 ms 265Hs 1.7 ms 1.9 ms Ds 170 µs 269Ds 180 µs 270Ds 5.1 ms 1.1 ms 271 56 ms 10.74 11.11 10.97 10.95 10.68 10.71 Mt 70 ms 268 10.24 10.10 266Hs 59 ms 267 10.57 9.88 50 10.34 10.30 9.83 50 10.52 10.37 10.17 9.75 Bh 262Sg 264 440 ms 9.62 9.48 0.3 s 263 0.9 s 9.25 9.06 261Db 262Db 1.6 s 3.6 ms 0.76 s 1.5 s 4.4 s 0.5 s 1.5 s 1.8 s 34 s 27 s 9.12 9.07 9.17 9.13? 9.01 9.07 9.08 67 9.08 >90 >50 8.66 67 8.89 e 9.16? 8.97? 9.01 33 e 9.47 9.05 <10? 8.93 <50 8.45 33 8.36 57 1.49 s 250Md 23 ms 8.79 4.0 m 254Rf 8.72 8.77 253Lr 0.57 s 1.64 s 255Rf 48 52 8.79 62 ms 256Rf 3.9 s 0.6 98 9.16 255Lr 257Rf 4.0 s 8.78 8.74 25.9 s e? 256Lr 13 ms 0.65 s 258Rf 3.1 s 259Rf 8.87 8.77 257Lr 258Lr 20 ms 0.36 s 260Rf 8.28 259Lr 78 s 3 m 261Rf 67 33 e <1? 260Lr 8.65 8.46 8.52 8.62 8.41 22 e 8.31 8.43 8.86 8.59 42;209;305? 8.46 8.37 8.39 8.80 8.56 8.45 23 8.03 25 e 252No 251 Md 7.82 e 7.75 93 e 7.55... 99 e 248Fm 2.6 m 251No 249Fm 85 e 1.8 s I? 7.43 250Fm 30 m 6.78 13 s 55 s 53 ms 2.3 s 1.7 m 8.82 8.58 911 204 75 I? 143...? 886 I? 8.37 25 8.01 2.3 m 5.30 h 254Lr 2.6 s 253No 0.26 s 53 842 943 252Md 254No <50 <50 e e 353? 251Fm 7.04 92 e 7.00 I? 8.74 6 m 25.9 s 55 s 25.4 h 8.12 8.08 e 7.93 187...?;e 253Md 252Fm 3.1 m 255No 2.91 s 256No 3.9 s 26 s 257No 61 8.32 39 e 8.45 8.27 8.40 0.53 8.22 254Md 255Md 256Md 1.2 ms 258No 7.58 7.55 7.52 257Md 58 m 259No e 258Md 10 m 28 m 27 m 1.30 h 5.52 h 57 m 51 d 7.07 6.76 7.01... 6.72 85 7.33... 92 e 7.22 371 85 e 369 15e e e 453;405? 7.15... 91 e 325...? e 488...? 3.0 d 253Fm 3.24 h 254Fm 20.1 h 255Fm 70 ns 256Fm 2.63 s 100 d 257Fm 6.94 7.19 7.02 6.92 8 6.67 88 e 7.15 6.96 231 I? 369? 6.52 0.21?;e 272...? 99;44...?;e 81;58...?;e 369... 488 92 242;180...? 2.1 s 39 m 263 262 Bh 1 s? 266Bh 17 s 267 9.30 8.85 Sg 261Lr 260 160 ms 95 m 0.38 ms 7.4 s 265Sg 8.94 8.84 8.76 9.69 259Md 258Fm 3.6 h 31.8 d 1.5 s 262 e 260 259 8.52 No 21 s 5 ms 266? 262 Mt 270 819 ms 10.03 Hs 20.9 s 269 9.18 22. 6. 2013 Padova, 9th - 13th of June 2013 5
253 Fm single particle isomer Applied reaction 48 Ca+ 207 Pb 253 No + 2n (1.8 x 10 6 nuclei) 253 Fm Produced via 45% beta decay of 253 No and beta decay of 253 Md Electron - coincidences γ delayed after CEs CE-γ coincidences γ before CEs S. Antalic et al. EPJ A47, 62 (2011) First beta decay data in region Z>100 22. 6. 2013 Padova, 9th - 13th of June 2013 6
a vs. b decay production of 253 Fm 253 Fm produced via a decay of 257 No at JAERI M. Asai et al. PRL 95, 102502 (2005) S. Antalic et al. EPJ A47, 62 (2011) How is isomer connected to g.s.? Opened problem: How to connect upper part populated by beta decay of 253 Md, with the lower part populated by 257 No alpha decay [M. Asai et al., PRL 95, 102502 (2005)]? 22. 6. 2013 Padova, 9th - 13th of June 2013 7
253 Fm and N=153 isotones S. Antalic et al. EPJ A47, 62 (2011) How is isomer connected to g.s.? Opened problem: How to connect upper part populated by beta decay of 253 Md, with the lower part populated by 257 No alpha decay [M. Asai et al., PRL 95, 102502 (2005)]? 22. 6. 2013 Padova, 9th - 13th of June 2013 8
K isomers Multi-quasiparticle states are located typically above 1 MeV. Very complex decay schemes Rich source of data on the structure (chance to populate many low lying levels) K-isomers might have additional hindrance against radioactive decay and might play a important role for enhanced stability of superheavy nuclei. In some cases lifetime of the isomer exceeds the g.s. lifetime. (see e.g. 270 Ds or 250 No.) [experiment: S. Hofmann et al., Eur. Phys. J. A 10, 5 (2001) and D. Peterson et al., (2006). Phys. Rev. C74 014316] J 1 2 3 22. 6. 2013 Padova, 9th - 13th of June 2013 9 K
254 No complex decay scheme 48 Ca+ 208 Pb 254 No+2n ~ 270 000 nuclei ~ 6300 in K=16 isomer Known isomer since 1973 A. Ghiorso et al. PRC 7, 2032 (1973) 0 25 50 75 100 125 150 175 200 225 250 JYFL: R.D. Herzberg et al. Nature 442, 896 (2006) E / Argonne: S.K. Tandel et al_prl97, 082502 (2006) 22. 6. 2013 Padova, 9th - 13th of June 2013 /18 Ereignisse Ereignisse Ereignisse F.P. Hessberger et al., EPJ A43, 55 (2010) 80 60 40 20 25 20 15 10 5 0 250 275 300 325 350 375 400 425 450 475 500 60 50 40 30 20 10 301.8 311.9 325.5 111.4 347.1 133.3 605.7 143.6 147.5 168.5 156.9 0 500 525 550 575 600 625 650 675 700 725 750 179.5 No254m2_clo_einzel_r229_r247 9.5.2007
E electron / 253 No K isomer Back to the 48 Ca+ 207 Pb 253 No + 2n Decay spectroscopy E / S. Antalic et al. EPJ A47, 62 (2011) F.P. Hessberger, Phys. At. Nucl. 70, 1445 (2007) Crucial requirement: We need low background to see low-energy electron- coincidences! 22. 6. 2013 Padova, 9th - 13th of June 2013 11
253 No Produced in rection 48 Ca+ 207 Pb 253 No + 2n (1.8 x 10 6 nuclei) Delayed e - - coincidences showed the presence of second isomer with many lines Decay spectroscopy In-beam spectroscopy S. Antalic et al. EPJ A47, 62 (2011) F.P. Hessberger, Phys. At. Nucl. 70, 1445 (2007) 9/2-[734]: R.D. Herzberg et al., EPJ A42, 333 (2009) 7/2+[624]: P. Reiter. et al, PRL 95, 032501 (2005) 032501 Isomer helped to detect rotational band and provide independent information about its assignment. 22. 6. 2013 Padova, 9th - 13th of June 2013 12
Possible decay scheme Suggested decay scheme from VASSILISSA@JINR Dubna Multi-quasi particle isomer Opened problem: Despite of high statistics (1.8 x 10 6 nuclei) very weak - coincidences. A. Lopez-Martens et al. NPA852 15 (2011) Single-particle isomer To confirm the decay scheme, more detailed spectroscopy data are necessary. 22. 6. 2013 Padova, 9th - 13th of June 2013 13
60 60 122 Geant simulations for present setup How important is the detector granularity? 802 73 % 27 % 802 802 714 Germanium clover: 60 x 60 x 140 mm Encapsulated in 1 mm Al 142 140 26% 209 9% 188 10% 89 209 Al Ge 22. 6. 2013 Padova, 9th - 13th of June 2013 14
GEANT simulation (40 000 events) 4 crystals 20 crystals 188 209 714 802 single spectrum 188 209 single spectrum 714 802 single spectrum 3 counts 30 counts coinc. to 802 140 counts 140 counts coinc. to 802 28 counts coinc. to 714 205 counts coinc. to 714 Increase from one to 5 clovers brought significant increase for Ga-Ga coincidences (factor of 5-6) 22. 6. 2013 Padova, 9th - 13th of June 2013 15
Conclusion Interesting new data are on the way (see examples 253 No and 253 Fm) Present limit for spectroscopy is Sg (Z = 106), however already for Rf (Z = 104) its challenging. Requirements for these measurements: High intense beam (1 pma and more) low background (low energy electrons and gammas delayed after ER implantation) high-sensitivity detectors (granularity is critical) Still lot of work is waiting for us and we need to do many small steps to understand superheavy elements! Thank you 22. 6. 2013 Padova, 9th - 13th of June 2013 16