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Fission Studies at LAND-R3B The SOFIA project Studies On FIssion with Aladin

Fission Studies at LAND-R3B The SOFIA project Studies On FIssion with Aladin CEA Bruyeres, CEA Saclay, IPN Orsay, GANIL, CENBG, Univ. Santiago de Compostela, Univ Vigo, GSI, possibly TU Darmstadt. What is SOFIA. -Revival of the S104 proposal - Experience approved but never realised

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Fission Studies at LAND-R3B The SOFIA project Studies On FIssion with Aladin

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  1. Fission Studies at LAND-R3B The SOFIA projectStudies On FIssion with Aladin CEA Bruyeres, CEA Saclay, IPN Orsay, GANIL, CENBG, Univ. Santiago de Compostela, Univ Vigo, GSI, possibly TU Darmstadt

  2. What is SOFIA • -Revival of the S104 proposal • - Experience approved but never realised • - some remaining beam-time • - Measure the fission yield in electromagnetic induced fission of secondary beams

  3. GSI : overview Uranum-238

  4. 10 15 20 25 30 5 E* (MeV) Electromagnetic excitation in Pb • multipolar giant resonances are excited • Large excitation spectrum • most probable energy : 11 MeV= Bf + 5MeV Bf

  5. Exp KH Schmidt at al. 1996 Actinide

  6. SOFIA • Evolution of the ’96 experiment • Now :much more favorable conditions: • much stronger uranium beam (x100), • beam-line from FRS to Cave C, • technical improvements time-of-flight detectors, electronics, • Stronger team, • We can do something better : • - again the nuclear charges Z1,2 (both FF), • - The masses of both FF (A1,2) • - Their kinetic energy (improved resolution) • - Reduced systematic and statistical uncertainty

  7. 2ndary beam identification • Degrader at S1 or S2 • ToF-Brho from S2 to cave C target • Tracking + MUSIC before cave C target

  8. Fission Fragment identification: what we need • Typical identication method : • BRho, ToF, E • For BRho, Large acceptance magnet + tracking • - close to 100% efficiency for both FF • For ToF : high resolution timing detectors • For E : double-sided ionization chamber

  9. The SOFIA set up Neutrons wall 80 cm 1.7 m Tracking1 + Start ToF ALADIN 2nd beam TWIN Music Active target: 5x150mg/cm2Pb Tracking 2 Tracking 3 1.5 m Start ToF 7m Stop ToF Stop

  10. The main difficulty : get the mass • ALADIN is weak : low angular deflection • Difficult to get the proper Brho resolution (1/500) • The angular straggling induced uncertainty • - Reduce the amount of material in beam • - Only gazeous detector (low Z gaz) • - flight-path in Helium

  11. Mass resolution, constraints • To get the Brho resolution : proper position resol. • - 200 micrometers FWHM on the 3 tracking det. • To get the mass reso : proper ToF reso • - 40 ps FWHM on 7m flightpath • Too thick detectors spoil the mass reso due to angular straggling : 60 cm P10 is too thick !

  12. The tracking detectors • MWPC chosen • Vertical wires • Horizontal pads • Similar to ALICE MWPC • Design and construction at IPN Orsay • Expected resolution : 200 m and 1.6 mm • Very thin detector : ~50 m of Al

  13. ToF wall design • See talk yesterday • Vertical UFast plastic stripes, 30 mm wide, • 25 stripes (600 mm long, 4mm thick) for stop detector • Vertical position from the timing in a stripe • Expect. Y-resol. : 2mm FWHM • Flight Path : 7 m • Expect. ToF resol : 40 ps FWHM • Expect. Ekin resol : 1.3% FWHM

  14. Twin-MUSIC • Central cathode Twin-chamber • hole all along central traj. (2 cm diameter) • 20 x 20 x 60 cm3 • Horizontal pos. from drift time • Expect. Résol : 0.2-0.5 mm • 1 bar operation • Neon based gas to be tested ½ chamber Sec. beam Anode plane Frish grid

  15. Current development work • - MUSIC: Under development at GSI • -ToF wall : under (advanced) development at Bruyeres le Chatel • 2 Tracking det’ : under development at IPN • Prototype ready to be tested • Expecting some parasitic beam-time at GSI for testing purposes (all 3 det’)

  16. Some details • Strong sec. beam intensity : 103-5 /s • FF rate :20-2000 /s !! • Trigger on FF only (ToF wall) • Thin secondary target : 0.7 g/cm2 Pb total • Reduced straggling • limited double reaction rate : 3% (was 20 %) • Beam-time needed : 1 day for measuring 1 actinide with very good accuracy

  17. Conclusion • All development work under progress • Feasibility of the tof wall validated • All detectors to be tested beginning of 2011 • Acquisition to be validated in 2011 • Ready to run end of 2011

  18. Cost estimate • TWIN-MUSIC • Realised at GSI estimated cost 50 k€ • Diamond • Collaboration TU Munich, electronics 10 k€ • Tracking (2) MW • Collaboration IPN Orsay, cost 80 k€,

  19. Cost estimate (2) • ToF wall (CEA Bruyeres) • cost 140 k€, ANR (young scientist) funding request • Active target • Estimated cost 15k€ • chamber, gaz : 15 k€ • Various electronics: 20 k€ (maybe underestimated) • Overall cost : about 330 k€

  20. Some more details • No interaction of the sec. beams with detec. • No unneeded load of the detect. (TWIN-MUSIC) • Scint. and Twin designed to avoid the beam • Slits : secondary beam occupancy : • -1 < x < +1 cm • -1 < y < +1 cm

  21. The detector option 1 Neutrons wall 80 cm He, 1.7 m Stripped diamond ALADIN, He 2nd beam TWIN Music, Ne Active target: 5x150mg/cm2Pb MW MW He, 1.5 m Start ToF 7m Scintillator wall Stop

  22. Option 1 difficulty • The uncertainty : the diamond detector • - stripped diamond: 2.5x2.5cm2, 200 m strip • - Start ToF • Similar detector exists • - but prototype (Münich) • - Electronics issues… to be developed • Significant source of anxiety (short term project) !

  23. Seeking for option 2 • What we are willing to do : remove the Diamond • - Need of diamond : 1st tracking • - If no need of trackin’, a plastic can be used • How to get a another tracking det’ without an additional det’ ?

  24. The detector option 2 Neutrons wall 80 cm He, 1.7 m scintillator ALADIN, He 2nd beam TWIN Music, Ne TRACKING Active target: 5x150mg/cm2Pb MW MW He, 1.5 m Start ToF 7m Scintillator wall Stop

  25. Option 2 difficulty • Get the proper tracking resolution from MUSIC • A factor of 2-3 better that usual MUSIC drift resolution • Our ideas : • Multiple measure of position : about 20 anodes • Linear fit of the 30 measurements (angle) • Improved electronics

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