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Cross-sections and Spectroscopy of 243Es and 249Md

This study investigates the production cross-sections and detailed spectroscopy of 243Es and 249Md through prompt and delayed spectroscopy. The results provide valuable information on nuclear landscape and reaction mechanisms.

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Cross-sections and Spectroscopy of 243Es and 249Md

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  1. 243Es, 249Md: from production cross-sections to prompt and delayed spectroscopy Marine VANDEBROUCK A. Drouart, Z. Favier (PhD), T. Goigoux (Postdoc), B. Sulignano, Ch. Theisen INPC 2019 29 July – 2 August 2019

  2. Introduction • Detailed spectroscopy of VHN and SHN provide information on the nuclear landscape at the upper limit of the nuclear chart • Particular interest for odd nuclei • Information concerning reaction mechanism • and reliable predictive models are required Difficulty: low production cross-sections proton a-decay Spontaneous fission b+ or electron-capture b- neutron M. Vandebrouck

  3. Experimental setup Fusion-evaporation reactions 197Au(48Ca,2n)243Es and 203Tl(48Ca,2n)249Md at Jyväskylä CLOVER 197Au/203Tl target Recoil PLANAR Ge PIN-diode box 48Ca beam MWPC DSSSD SAGE Silicon And Germanium spectrometer RITU Recoil Ion Transport Unit GREAT Gamma Recoil Electron Alpha-Tagging • Gas filled separator • QDQQ • Prompt spectroscopy • 34 HPGe • + electron spectrometer • Delayed spectroscopy • MWPC + DSSD (ion implantation) • 1 planar Ge + 4 clovers Ge + Si tunnel M. Vandebrouck

  4. 197Au(48Ca,2n)243Es Results a-decay spectrum of 243Es What did we know about 243Es? Recoil-a correlations RITU @Jyväskylä SHIP @GSI 243Es Time distribution of a decays following the 243Es implantation R. Briselet, Ch. Theisen, M. Vandebroucket al. PRC 99, 024614 (2019) Random S. Antalicet al. EPJA 43, 35 (2010) • Observation of the 243Es a-decay • 243Es half-life: • - Fit taking into account random correlations • - Log scale spectrum shows 2 contributions : 243Es and random • Both approaches give compatible results T1/2(243Es) = 24 ± 3 s • Production cross-section in the time window T(243Es) = 270 s • s = 32 ± 9 nb(Ebeam = 208 MeV) and s = 37 ± 10 nb(Ebeam = 210 MeV) 243Es M. Vandebrouck

  5. 203Tl(48Ca,2n)249Md Results What did we know about 249Md? RITU @Jyväskylä SHIP @GSI BGS @LBNL a-decay spectrum of 249Md F. P. Hessbergeret al. EPJA 41, 145 (2009) J.M. Gates et al. PRC 78, 034604 (2008) Y. Hatsukawaet al. NPA500, 90 (1989) F. P. Hessberger et al. Physik A Atoms and Nuclei 322, 557 (1985) • Observation of the 249Md, 245Es and 249Fm a-decay R. Briselet, Ch. Theisen, M. Vandebroucket al. PRC 99, 024614 (2019) M. Vandebrouck

  6. 203Tl(48Ca,2n)249Md Results Time distribution of a decays following the 249Md implantation What did we know about 249Md? RITU @Jyväskylä SHIP @GSI T1/2(249Md) = 26 ± 1 s BGS @LBNL Time distribution of a decays of 245Es with respect to 249Md a decay R. Briselet, Ch. Theisen, M. Vandebroucket al. PRC 99, 024614 (2019) F. P. Hessbergeret al. EPJA 41, 145 (2009) J.M. Gates et al. PRC 78, 034604 (2008) Y. Hatsukawaet al. NPA500, 90 (1989) F. P. Hessberger et al. Physik A Atoms and Nuclei 322, 557 (1985) T1/2(245Es) = 65 ± 6 s • Observation of the 249Md, 245Es and 249Fm a-decay • Half-lives: T1/2(249Md) = 26 ± 1 s and T1/2(245Es) = 65 ± 6 s • Production cross-section in the time window T(249Md) = 207 s • s = 70 ± 40 nb(Ebeam = 213 MeV) • s = 300 ± 80 nb(Ebeam = 214 MeV) M. Vandebrouck

  7. Comparison with the models KEWPIE2 H. Lüet al. Computer Phys. Comm. 200, 381 (2016) What is it? Statistical fusion-evaporation code Method: reaction divided into 2 stages Capture Decay by light-particle evaporation in competition with nuclear fission and g-ray emission (probabilistic approach) • 3 parameters adjusted in mass region: • Friction parameter b • Shell-correction energy DEsh • Ignatyuk’s prescription R. Briselet, Ch. Theisen, M. Vandebroucket al. PRC 99, 024614 (2019) M. Vandebrouck

  8. Comparison with the models KEWPIE2 H. Lüet al. Computer Phys. Comm. 200, 381 (2016) What is it? Statistical fusion-evaporation code Method: reaction divided into 2 stages Capture Decay by light-particle evaporation in competition with nuclear fission and g-ray emission (probabilistic approach) • 3 parameters adjusted in mass region: • Friction parameter b • Shell-correction energy DEsh • Ignatyuk’s prescription • Fission barrier height or the friction parameter increased to reproduce the measurements for the 2n (243Es) evaporation channel • Adjustments that remain within the uncertainty intervals • To freeze/eliminate the impact of a specific parameter, need experimental inputs : • - large scan in excitation energy • - different evaporation channels R. Briselet, Ch. Theisen, M. Vandebroucket al. PRC 99, 024614 (2019) M. Vandebrouck

  9. Conclusion • Measurement of the 243Es and 249Md production cross-sections • Spectroscopy of 249Md: • Results of prompt spectroscopy Preliminary results of delayed spectroscopy Work of Thomas Goigoux Tagging of with its decay Search for an isomeric state: electron signal in DSSSD + Coincidence with rays and PIN diodes g (recoil tagged) Total decay energy: g-g (recoil tagged) Isomeric state > 910(15) keV g (recoil decay tagged) Preliminary 177.75 351.5 525.25 699 Eg [keV] M. Vandebrouck

  10. Thank you for your attention M. Vandebrouck

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