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SuperCHICO; a 4 π heavy-ion detector

SuperCHICO; a 4 π heavy-ion detector. C.Y. Wu and D. Cline An arsenal of auxiliary charged-particle detectors must be an integral component of GRETA in order to achieve and exploit the ultimate in sensitivity and selectivity for nuclear science

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SuperCHICO; a 4 π heavy-ion detector

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  1. SuperCHICO; a 4π heavy-ion detector • C.Y. Wu and D. Cline • An arsenal of auxiliary charged-particle detectors must be an integral component of GRETA in order to achieve and exploit the ultimate in sensitivity and selectivity for nuclear science • The 4π heavy-ion detector, SuperCHICO, is designed to exploit γ-ray tracking arrays for study of quasi-binary reactions at both stable and exotic beam facilities, that is: • Coulomb excitation • Single and multi-nucleon transfer reactions • Deep inelastic reactions • Fission • SuperCHICO is based on the successful CHICO detector.

  2. CHICO Ge detector CHICO* M.W.Simon, D. Cline, C.Y. Wu R.W. Gray, R. Teng. C. Long Nucl. Inst. Meth. A452 (2000) 205 *Work supported by the NSF Scattering angle: 12 85 (Front Part) 95 168 (Back Part) Azimuthal angle total: 280 of 360 Position resolution:  1 in  and 9.3 in  Solid angle: 69% of 4π Time resolution:  500 ps Mass resolution Δm/m = 5% Q-value resolution: ≤ 20 MeV

  3. Doppler-corrected γ-ray spectra 1358 MeV 238U on 170Er C.Y. Wu, D. Cline, et al, Phys. Rev. C61 (2000) 21305(R) CHICO/Gammasphere Raw data Correction for U-like recoils Correction for Er-like recoils

  4. CHICO-GS Operation 1996-2006 • CHICO-Gammasphere ideal for quasi-binary type reactions: Coulomb excitation transfer reactions deep-inelastic reactions fusion-fission reactions • 24 experiments performed by 58 researchers from 17 institutions • 48 publications, including 2 Phys. Rev. Lett. and 2 in Phys. Lett. • 5 Ph.D. theses completed

  5. SuperCHICO performance • Angular coverage: 20o ≤ θ ≤ 85o, 95o ≤ θ ≤ 160o; 280o in φ • Angular resolution:Δθ = 1o, Δφ = 1.4o • Solid angle: 66% of 4π • Time resolution:Δt = 500ps • Mass resolution for kinematic coincidence:Δm/m = 5% • Q-value resolution: ≤ 20 MeV • GRETA Doppler-corrected γ-ray resolution: ~ 0.3%

  6. Advantages of SuperCHICO • Large solid angle: Study weak exotic beams or low cross-section processes • Large angular coverage:High kinematic coincidence efficiency Large range of impact parameters • Angular and time resolution:Mass, Q-value resolution; high selectivity • Achieve maximum Doppler-corrected γ-ray resolution for GRETA: • Identify γ-rays from each fragment • Very high count-rate capability:> 100kHz • Hardness to radiation damage: • High background suppression:PPAC blind to light ions, Kinematic coincidence requirement • Minimal mass:Minimal γ-ray absorption and Compton scattering • Low initial and operational costs:only 80 channels of electronics for 26,000 pixels

  7. Cost details: LLNL estimate • Assume most engineering carried out at LLNL • Mechanical • Design: 22 weeks, $100k • Fabrication: $100k • Electronics • Amplifier • Replace CHICO hybrid circuit design • Design: 6-8 weeks, $80k • Fabrication: $80k • Downstream • Recycled from CHICO • Replaced by FADC and computer-controlled gas-handling system at some future date • Total cost: $360k excluding scientific manpower at LLNL and Rochester. St. Louis Workshop

  8. Future Opportunities • SuperCHICO plus GRETA will be a powerful facility for nuclear spectroscopy using either stable or exotic beams • Stable beams: a) Probe quadrupole, octupole, or pairing collective modes of motion in nuclei. b) Extend studies of transuranic nuclei to higher spin, ≥40ħ c)Probe collective bands built on unusual isomeric states and determine the Eλand Mλ matrix elements involved to probe both collective and shell structure. • Exotic neutron-rich beams: a) Explore the evolution of collectivity and shell structure with isospin. b) Deep inelastic and transfer reactions will extend range of neutron-rich nuclei. c) Pair transfer to probe neutron pairing correlations in neutron-rich nuclei d) Exploit isomeric beams to probe unusual configurations in nuclear structure

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