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CHICO-II; a 4 π heavy-ion detector LLNL-Rochester CHICO2 collaboration

CHICO-II; a 4 π heavy-ion detector LLNL-Rochester CHICO2 collaboration. LLNL: C-Y. Wu U. Rochester: A.B. Hayes, D. Cline, R. Flight, A. Melchionna, C. Zhou Engineering: D. Swan (Cathodes, GHz amplifiers, transmission lines), R. Fox ( DAQ software) Funding: DOE and NSF

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CHICO-II; a 4 π heavy-ion detector LLNL-Rochester CHICO2 collaboration

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  1. CHICO-II; a 4π heavy-ion detectorLLNL-Rochester CHICO2 collaboration • LLNL: C-Y. Wu • U. Rochester: A.B. Hayes, D. Cline, R. Flight, A. Melchionna, C. Zhou • Engineering: D. Swan (Cathodes, GHz amplifiers, transmission lines), • R. Fox ( DAQ software) • Funding: DOE and NSF • GRETINA Meeting, ANL, 1-2 March 2013

  2. CHICO-II purpose • CHICO-II, is designed to exploit GRETINA and Gammaspherefor study of quasi-binary reactions using stable or exotic beams: • Coulomb excitation • Single and multi-nucleon transfer reactions • Deep inelastic reactions • Fission • CHICO2 is an upgrade of the CHICO detector that has been used with Gammasphere since 1996.

  3. 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

  4. 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

  5. CHICO2 upgrade • Design and fabricate cathodes with high segmentation for both θ and ϕ • Fast amplifiers with improved signal to noise and anode energy-loss output signal • Replace 17 year-old FERA electronics with modern electronics to facilitate merging with the GRETINA and Gammasphere data acquisition systems. • Remove clamp lugs to allow use of CHICO2 with GRETINA. Developed a new clamping method. • Major renovation of most of the CHICO detector and ancillary equipment.

  6. CHICO2 cathode board

  7. Mounting an anode frame in CHICO2

  8. CHICO-II specifications • Angular coverage: 12o ≤ θ ≤ 85o, 95o ≤ θ ≤ 168o; 280o in φ • Angular resolution:Δθ = 1o, Δφ = 1.4o • Solid angle: 69% of 4π • Energy-loss output: Improved time, mass and Z resolution • Time resolution:Δt ≤ 500ps • Mass resolution for kinematic coincidence:Δm/m ≤ 5% • Q-value resolution: ≤ 20 MeV • Gammasphere γ-ray Doppler broadening:0.8%* • GRETINA γ-ray Doppler broadening:0.2%* *Ignores contribution due to intrinsic resolution etc.

  9. SCHEDULE • Completed: Implement upgrade of CHICO and test using 252Cf fission source • 9 -10 March: Move CHICO2 equipment (3100lbs) from Rochester to ANL • 11 – 17 March: Mechanical installation and vacuum test. • 18 – 25 March: Merge the CHICO2 and Gammasphere DAQ systems • 2 – 3 April: Stable beam test run • 10 – 21 April: Commence CHICO2/Gammasphere research program. • Coulex of a 144Ba beam from CARIBU

  10. CHICO2 plus GRETINA operation • CHICO2 operation should be fully proven and robust when GRETINA is available. Prior experience using CHICO2 with Digital Gammasphere should facilitate merging the GRETINA and CHICO2 data acquisition systems. • GRETINA modules can be used at angles 120 θ 1680 and all ϕ angles except where blocked by the target ladder at (θ,ϕ) = (900 ,900) or the alignment lugs at (θ,ϕ) = (900, 00) and (θ,ϕ) = (900 ,1800) • The GRETINA Gecrystal have an inner radius of 185mm while the cryostat is 178mm which is the radius of CHICO2. Thus it will be desirable to off-set GRETINA relative to CHICO2 by 2mm for clearance. • CHICO2 is robust and insensitive to high count rates and high radiation levels.

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