VAMOS « Hot » results and perspectives * Spectroscopy of n-rich nuclei produced by fission * New gas-filled spectrometer-separator for fusion Getting ready for SPIRAL2 ? C.S. for the VAMOS group LEA COLLIGA, Nov 2009, Paris Still other results presented by J.Ljungvall and N.Le Neindre

The VAriable MOde Spectrometer Q h Q v (WF)D B – type optical device under vacuum beam C.S. for the VAMOS group LEA COLLIGA, Nov 2009, Paris focalisation dispersion B  =A. v/Q Pullanhiotan et al., NIM A 593 (2008) 343 Detection system -> (x,y,T of,  E,E res ) * Wide acceptance:  ~ 60msr,  p/p ~  10% * High selectivity * Versatility * Easy coupling with other detectors (EXOGAM, MUST2,TIARA,INDRA,…)

Prompt spectroscopy of isotopically identified fission-fragments * One of the two FF enters 20° * Prompt  -rays of both FF detected in EXOGAM C.S. for the VAMOS group LEA COLLIGA, Nov 2009, Paris Assets of inverse kinematics: - Z identification of heavy FF + Increased acceptance Direct kinematics PRISMA+CLARA N.Marginean et al., PRC 80 (2009) (R) - Detected FF -> (A,Z,Q,v,,  ) 2 possible Doppler - Two-body kinematics used to reconstruct corrections ! the velocity vector of the undetected FF Fission in inverse kinematics 238 U (6.1AMeV) + 12 C Goals: FF production yields FF  -spectroscopy F. Rejmund et al. E516 experiment

M.Caamano, F.Rejmund et al., in preparation Isotopic (Z, A) identification of fission-fragments M/Q M M M Ru Xe C.S. for the VAMOS group LEA COLLIGA, Nov 2009, Paris More than 300 FF isotopically identified from A~80 to A~150  Z/Z~1/65  A/A~1/160

A.Shrivastava et al., PRC (2009) (R) in press Prompt  spectroscopy of the detected fission fragment C.S. for the VAMOS group LEA COLLIGA, Nov 2009, Paris 109 Ru 110 Ru 104 Ru 106 Ru 107 Ru 108 Ru 111 Ru 112 Ru Counts/2keV E (keV)

A.Shrivastava et al., PRC (2009) (R) in press Prompt  spectroscopy of the un-detected fission fragment C.S. for the VAMOS group LEA COLLIGA, Nov 2009, Paris 238 U+ 12 C -> 250 Cf* Analyzed pairs from fusion- fission : Zr-Ce, Mo-Ba, Ru-Xe, Pd-Te, Cd-Sn Ex: Xe identified in VAMOS - Fission partners (Ru) velocity vector from kinematics Gamma-spectroscopy feasible independent whether the FF is detected or not ! 133 Xe detected Corrected for Ru Ru detected Corrected for Ru 133 Xe detected corrected for Ru Ru detected corrected for Ru

Prompt  -ray spectrum in coincidence with 134 Xe in VAMOS Mis-assignment to 135 Xe via high-fold  -  coincidences States above the 7 - (T 1/2 =290ms) and 10 + (T 1/2 =5  s) isomers revealing of the configuration of these isomers C.S. for the VAMOS group LEA COLLIGA, Nov 2009, Paris Advantage of the direct isotopic identification A.Shrivastava et al., PRC (2009) (R) in press Shell model calculation by K.Sieja using new GCN 5082 interaction for Z=50,N=82 region

C.S. for the VAMOS group LEA COLLIGA, Nov 2009, Paris & * Prompt  -spectroscopy of both light and heavy fission fragments can be performed * Significance of unambiguous identification of the fission fragment in a spectrometer Prompt  -spectroscopy of n-rich nuclei spanning a wide range in (A,Z) and with virgin level schemes NB: here only two EXOGAM detectors, thin target, limited I beam

New gas-filled operation mode for fusion reactions Tasks of the large acceptance spectrometer for 0° operation - Discriminate all open channels (fusion-evap, fission, Coulomb excitation) - Select efficiently the fusion-ERs - Reject the intense incoming beam !!!! Heavy-ion analyzer mandatory with increasing I beam and decreasing  ‘s VAMOS How to optimize the use of 0° ? Beam/ER separation according to B  vacuum sufficient in very asym direct kinematics limited in more sym and inverse kinematics Gas-filled operation mode of VAMOS for ~ FREE !!! Solution of the gas-filling:  Q distribution changes and gets narrow  B  ~ A : powerful beam/ER separator  larger transmission C.S. for the VAMOS group LEA COLLIGA, Nov 2009, Paris

VAMOS From vacuum to gas He gas - C foil before the target for vacuum/gas separation - He gas-filling ~1mbar - beam stopper (Ta plate) 50mb  ER  -radioactive residues ( 186 Pb, 186 Hg, 185 Tl, 187 Tl,…) Measurement: 40 Ca (196MeV) Sm  190 Pb* 200mb  fission 250mb  fusion ERs identified via  decay in Si wall and/or prompt  -rays in EXOGAM C.S. for the VAMOS group LEA COLLIGA, Nov 2009, Paris  E,E,T of

Selection and identification of fusion evaporation residues * Selection -> Direct beam -> Scattered target like nuclei -> Fusion ERs -> Beam scattered from dump Proper selection of the fusion ER * Identification Prompt  -radiationRadioactive  -decay Protons from reactions in the beam dump C.S. for the VAMOS group LEA COLLIGA, Nov 2009, Paris

Performances of the gas-filled VAMOS Scan in B  0 and He pressure to optimize beam rejection and transmission Optimal conditions (with present simple set-up) : Bρ 0 =1.65Tm and p ~ 1mbar Beam rejection factor > (no direct beam on the detectors for Ca sent in VAMOS) Transmission from ion-optics calculations (ZGOUBI) ~ 60% for  evaporation channels ~ 90% for neutron channels P R E L I M I N A R Y P R E L I M I N A R Y Large aperture Big detectors C.S. for the VAMOS group LEA COLLIGA, Nov 2009, Paris Existing gas-filled separators VAMOS CS et al., in preparation SHIP M.Mazzocco S al., NIMB266(2007)3467

C.S. for the VAMOS group LEA COLLIGA, Nov 2009, Paris & * Feasibility of a gas-filled VAMOS * Significance for measurements employing fusion in (nearly) symmetric and inverse kinematics the « standard » with SPIRAL2 heavy RIB NB: Gas-filled set-up not optimized, not ready to be used for physics

Further improvements C.S. for the VAMOS group LEA COLLIGA, Nov 2009, Paris * Vaccum mode - Doubling of the size of the detectors  (msr) B  /B  0 today tomorrow * Gas-filled mode - Beam dump farthest and shielded (  beam rejection factor) - Differential pumping system (  transmission) - Recoil Decay Tagging with MUSETT