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TPC for 2p radioactivity studies

TPC for 2p radioactivity studies. Bertram Blank, CENBG. 1 0. 0 1 2 3 4 5 6. Energy (MeV). four 2p decay events. two-proton decay of iron-45 from GANIL 2000 / GSI 2001. GANIL. GSI. Discovery of two-proton radioactivity.

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TPC for 2p radioactivity studies

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  1. TPC for 2p radioactivity studies Bertram Blank, CENBG

  2. 1 0 0 1 2 3 4 5 6 Energy (MeV) four 2p decay events two-proton decay of iron-45 from GANIL 2000 / GSI 2001 GANIL GSI Discovery of two-proton radioactivity However: - only decay energy - no individual energies - no proton-proton angle TPC

  3. Principle of a time projection chamber - individual energies - proton-proton angle

  4. time projection chamber for 2p studies 1500 electronics channels GEM: Gas electron multiplier beam Hybrid boards Hybrid boards Daughter boards Daughter boards

  5. z y x x Double-sided micro-strip gas detector • Anodes: • 768 micros-strips of copper on a capton • substrate (2x100m) • Epoxi frame • Cathodes: • 768 micros-strips of copper (200m)

  6. z y x x Mother board + detector (15x15 cm2) + 3 GEMs

  7. time projection chamber Detector mount Detector mount TPC chamber Electronics card Strip-strip matrix GEM  = 70mm d = 100mm

  8. time projection chamber

  9. y Implantation at end Implantation at entrance saturation x Silicon detector beam x energy | x time|yenergy| y time TPC: Implantation events 48Ca + 9Be  26P, 25Si,…. Threshold for implantation events Threshold for radioactivity events End of TPC Center of TPC Entrance of TPC Different implantation depths by changing the Br

  10. y b-delayed decay Collimated a source x Silicon detector beam x energy | x time|yenergy| y time b-delayed decay TPC: Decay events b-delayed decay

  11. time projection chamber: details Detector: double-sided microstrip detector (CERN) GEM: Gas electron multiplier (CERN) Detector gas: P10 at 1atm Active detection volume: 15 x 15 x 15 cm3 ASICS: VAT/TAT by IDEAS, Norway TAC window: 10 s channels per chip: 32 time and energy Electronics and data acquisition: PXI – VME Dead time: 1.5 ms (max) Problems - up-grades 4 GEMs to increase the gain new a source collimation system non-linearity of the gain (-30% on sides) retract drift frames

  12. -17% Non-linearities of gain: 3-alpha source -33% 20 mm 30 mm beam GEM spectra 28 mm Top view Possible reason: drift frames for field homogeneities

  13. Experiments: • two-proton radioactivity: 45Fe, 54Zn, 59Ge ? • 2p radioactivity: 22Al, 23Si, 26P, 27S, 31Ar,….. •  correlations ???? • ??? Collaboration: • CENBG: Exotic nuclei group • Electronics group • Intrumentation group • Mechanics group • GANIL: DAQ group • LISE group

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