Stable and radioactive beam studies @ ALTO Georgi Georgiev, CSNSM, Orsay, France
The ALTO facility 15 MV 50 MeV 2013 2014 2015 Users 200 135 143 Beam-time 2983 h 2297 h 2736 h 373 UT 287 UT 342 UT 18 Sept. 2015, Kraków, Poland
Experimental areas Split-Pole ISOL spectrometer Bacchus production cave ISOL e LINAC mass separator Licorne experimental lines g -spectrometers ORGAM MINORCA PARIS cluster, molecular & droplets beams Radioactive beam lines Stable beam w/o spectrometer Stable beam with spectrometer 18 Sept. 2015, Kraków, Poland
26 Al nucleosynthesis in massive stars N. de Séréville & A. M. Laird N-SI-36 Astrophysical motivation: ● Gamma-ray emission associated with 26 Al observed in our galaxy. ● 26 Mg coming from 26 Al decay observed in presolar grains ● 26 Al yields depends strongly on reactions 26 Al(n,p) 26 Mg and 26 Al(n, a ) 23 Na 27 Al spectroscopy (E R , J p , G p , G a ) above ● Need for better neutron threshold (S n = 13 MeV) Credit: MPE Garching / R. Diehl 26 Al(n,p) 26 Mg and 26 Al(n, a ) 23 Na in massive star → Populating resonances with the 27 Al(p,p') 27 Al* reaction Split-Pole spectrometer (ALTO) + DSSSDs in reaction chamber Adsley et al. to be submitted 30 new states above neutron threshold in 27 Al S. Benamara, N. de Séréville et al, PRC 89, 065805 (2014) 18 Sept. 2015, Kraków, Poland
LICORNE II – fast-neutron source H 2 pressure and flow Hydrogen gas cells control system Development of a kinematically focused neutron source with the p( 7 Li,n) 7 Be inverse reaction M.Lebois, J.N. Wilson et al., Nucl. Instrum. Meth. A 735 145 (2014) 18 Sept. 2015, Kraków, Poland
TDRIV on H-like ions: 24 Mg beam: 24 Mg @120 MeV (5 MeV/u) target: 2.4 mg/cm 2 93 Nb reset Foil: 1.7 mg/cm 2 197 Au Previous measurement: |g(2 + )| = 0.51 (2) R.F. Horstman et al., NPA 248, 291 (1975) Our result: |g(2 + )|= 0.538 (13) A. Kusoglu et al. PRL 114, 062501 (2015) 24 Mg 2 + state USD shell model: g(2 + )=0.544 High-accuracy g-factor measurements are essential for constraining the theories! 18 Sept. 2015, Kraków, Poland
MINORCA in Orsay (June 2014 – March 2015) 12 ORGAM CS HPGe x 0.1% 8 Miniball TC at ~14 cm from target 7.3% efficiency @ 1.33 MeV ancillary detectors: - Orsay plunger (OUPS) - particle detector - DSSD 18 Sept. 2015, Kraków, Poland
MINORCA – experiments performed like 56 56 Fe 1. 1. Tim ime de dependent reco recoil in vac vacuum for for Na-like Fe ion ons - spo spokespersons: s: A. . St Stuchbery, D. . Bala alabanski coexistence in 74 74 Se 2. 2. Sh Shape coe Se stu studied through com complete low ow-spin spe spectroscopy af afte ter Cou Coulo lomb excitation exc - spo spokespersons: s: M. . Zie Zielinska, , K. K. Wrzosek-Lipska 3. 3. Mea easurement of of octu octupole coll collectivity in Nd Nd, , Sm Sm an and Gd Gd nu nuclei usin using Cou Coulo lomb exc excitation - spo spokespersons: s: P.A. Butler, M. . Zie Zielinska n the 238 238 U( 4. 4. Spe Spectroscopy of of the ne neutron-ric ich fi fiss ssion frag fragments pro produced in U(n,f) rea reactio ion - spo spokespersons: s: J. . Wils ilson, M. . Le Lebois of the 96 96 Mo γ Strength Fu 5. 5. Eva Evalu luatio ion of of the Ang ngular Mom omentum De Dependence of Functio ion - spokesperson: B. . Gol oldblum of 100 100 Ru 6. 6. Lif Lifetim ime Measurement of Ru: A poss possible le can candid idate for for the E(5 E(5) cr crit itic ical po poin int sym symmetry - spokesperson: Th Th. . Konstantinopoulos n 113 113 Te 7. 7. Lif Lifetim ime mea easurements in Te: De Dete termining Op Optim imal eff effectiv ive ch charges ap approaching the N=Z=50 do doubly-magic she shell l cl closure. . - spokesperson: D.M .M. . Cul ullen 18 Sept. 2015, Kraków, Poland
Most-recent results D. Suzuki et al. • First in-beam experiments of Demonstrator bacchus • 2,048 Micromegas pads • 4 DSSDs + 12 Pad Si integrated • Newly-made GET electronics to take data • 2 successful runs (June to July ’15) • 12 C @80 MeV + He gas • 6 Li @11 to 23 MeV + He gas • 35 visitors (16 domestic, 19 international) 12 C 4 + ? stable 10 B 11 B stable stable 8 Be 9 Be 10 Be 5.6 eV stable 1.5 My 6 Li 7 Li ? [MeV] stable stable p α α n d Micromegas Pad Si DSSD molecular like Hoyle like 18 Sept. 2015, Kraków, Poland
ACTAR TPC: Demonstrator • Two experiments performed at ALTO: bacchus • a -clustering in light nuclei Beam 18 Sept. 2015, Kraków, Poland
ALTO - RIB First operational RIB facility based on photo-fission populating the GDR of 238 U Y. . Oganess ssian et al. al. , NPA A 70 701 1 (20 (2002 02) 87 87c standard ISOLDE target ∅ = 14 mm; L = 140 mm ρ = 3.2 g/cm 3 ; T ≤ 2100 o C Estimated yields for 10 µA, 50 MeV e - beam 18 Sept. 2015, Kraków, Poland
Rialto: Resonant laser ionisation at Alto S. Franchoo et al. Mezzanine of the mass separator/RIB zone Nd:Yag pump laser (532 nm, 90 W) 2 dye lasers (540-850 nm, 8W @ 30W pump, 10 ns pulse width, 3 GHz line width) BBO doubling units (270-425 nm, >100 mW) 18 Sept. 2015, Kraków, Poland
Nuclear structure in b -decay fast timing neutron detection BEDO setup LaBr3 TETRA up to 5 Ge detectors (ε = 5-6%) 80 3 He tubes ε( 252 Cf) = 53% Fast-timing studies using 4π β trigger borated polyethylene shielding LaBr 3 detectors 18 Sept. 2015, Kraków, Poland
Results from BEDO in b - delayed γ -spectroscopy mode (2) ubiquitous presence of intruder states of the type 1p-2h 82 Ge→ 82 33 As 49 → signature of shape coexistence shape coexistences: (1) problem of the spectral distribution of 1 + states a general phenomenon? in the N=50 region (→ responsible for the half -life of the mother nucleus, possible consequences on the r-process) 50 interpreted by the theoretical work of Severyukhin… Giai et al. (influence of couplings to 2p-2h and tensor ? interaction) [Heyde & Wood, Rev. Mod. Phys. 83 (2011)] 1+ 50 Though this phenomenon seems to concern all shell-closure regions: not a single study at N=50 for more than 3 decades! (Z=50 a textbook case) ν d 5/2 conclusion: an «island of 1p-2h 50 inversion» is « missed » at N=50 by 0.5 MeV only ! ν g 9/2 A. Etilé et al. , Phys. Rev. C 91, 064317 (2015) 18 Sept. 2015, Kraków, Poland
Present setups and near-future projects Parrne mass separator Identification station TETRA LTNO (existing) ( 3 He/ 4 He) TAS POLAREX (project) (project) MLL Trap (project) Mass BEDO/TETRA measurements (existing) LINO (project) Laser-Induced nuclear orientation (µ,Q, J p ) 18 Sept. 2015, Kraków, Poland
► Stable and Radioactive beam facility ► R&D on ISOL & RIB ► low-energy physics program based on photo-fission ► R&D and physics at ALTO a step towards a next-generation ISOL RIB facility: initiate physics program, train ISOL physicists, develop instruments and methodologies
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