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CHICO experiments with CARIBU beams

CHICO experiments with CARIBU beams. D. Cline, A. Hayes, and C.Y. Wu CHICO: Designed to exploit Gammasphere for study of quasi-binary reactions Coulomb excitation Single and multi-nucleon transfer reactions Deep inelastic reactions Fission

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CHICO experiments with CARIBU beams

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  1. CHICO experiments with CARIBU beams • D. Cline, A. Hayes, and C.Y. Wu • CHICO: Designed to exploit Gammasphere for study of quasi-binary reactions • Coulomb excitation • Single and multi-nucleon transfer reactions • Deep inelastic reactions • Fission • Motivation: Exotic neutron-rich beam physics motivation: • Explore the evolution of collectivity and shell structure with isospin. • Deep inelastic and transfer reactions will extend range of neutron-rich nuclei. • Pair transfer to probe neutron pairing correlations in neutron-rich nuclei • Exploit isomeric beams to probe unusual shell configurations

  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  4.6 in  Solid angle: 69% of 4π Time resolution:  500 ps Mass resolution Δm/m = 5%

  3. Fission products Fission products Deep-inelastic products Deep-inelastic products CHICO Mass and Q-value 283.7 MeV 48Ca on 208Pb S. Zhu, R.V.F. Janssens, et al, NS06, 2006

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

  5. Coulomb excitation of 178Hf by 650 MeV 136XeA.B. Hayes1, D. Cline1, C.Y. Wu1, M.W. Simon1, R. Teng1, J. Gerl2, Ch. Schlegel2, H.J.Wollersheim2, A.O. Macchiavelli3, K. Vetter3, P. Napiorkowski4, J. Srebrny41)Rochester, 2)GSI, 3)LBNL, 4)Warsaw Physical Review Letters 89 (2002) 242501

  6. Triple γ-γ-γ spectrum gated on the 377keV (18+→17+) plus 398keV (19+→18+) peaks of the K=16+ isomer band in 178Hf for Coulomb excitation of a 178Hf beam by a 208Pb target • Clean well-resolved spectra • Peak to background ratio ~100:1 • Peak areas up to several thousand counts

  7. Advantages of CHICO for CARIBU research • 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 Gammasphere: • Identify γ-rays from each fragment • Very high count-rate capability:> 100kHz • Hardness to radiation damage:242mAm target (1.6 mCi, 1 MHz α’s, 500 kHz x-rays) • High background suppression:Can adjust threshold to suppress light ions (p, d, α, C) Kinematic coincidence requirement • Minimal mass:Minimal γ-ray absorption and Compton scattering • Low initial and operational costs:Only 80 channels of electronics for 4,200 pixels Operational costs negligible

  8. Staging CHICO for CARIBU research Advantages: • CHICO operates with Gammasphere both stand-alone or at the FMA • Initial set up time is 1 week, • Reliable and trouble-free operation during month-long campaigns • Minimal maintenance and costs required during operation • Weak exotic beams should eliminate radiation damage to the foils. Concerns: • Sensitive to pilot error when operating vacuum controls. • Requires expert knowledge to handle and change thin foils • Will require an ATLAS in-house Chico expert to support the Rochester group if long running periods are scheduled

  9. Future: SuperCHICO plus GRETINA • 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%

  10. CHICO + Gammasphere portable data analysis codes Data sorting and reduction: ANL Root-basedGSSort (T. Lauritsen, S. Zhu) , Radware (Radford) __________________________________________________ GOSIA: Coulomb excitation least-squares search codes: Can fit <1000 electromagnetic matrix elements coupling 100 levels to thousands of Coulex data 1980: Fortran code originally developed at Rochester, (T. Czosnyka, D. Cline, C.Y. Wu) 2008-09: Major updates to methods and coding, (D. Cline, A. Hayes, P. Napiorkowski, N. Warr) The codes are more reliable, and robust using modern compilers. Input and operation simplified. The Gosia User Manual has been extensively revised, and expanded to facilitate use. Download the latest versions of the suite of Gosia codes plus the User Manual available at Gosia web site: http://www.pas.rochester.edu/~cline/Gosia/index.html ________________________________________________________________

  11. Bambino Si CD Heavy-ion detector (LLNL; Rochester) • Forward and backward annular Si CD heavy-ion detectors • Angular coverage: • 20o < θ < 50o, 130o < θ < 160o • 00 < φ < 315o • Angular resolution; • Δθ = 1.22o, Δφ = 22.5o http://www.pas.rochester.edu/~cline/Research/index.html CAP Congress Saskatoon, 18 June 2007 Douglas Cline for TIGRESS Collaboration

  12. Summary of CHICO performance • Angular coverage: 12o ≤ θ ≤ 85o, 95o ≤ θ ≤ 168o; 280o in φ • Angular resolution:Δθ = 1o, Δφ = 9.3o • Solid angle: 69% of 4π • Time resolution:Δt = 500ps • Mass resolution for kinematic coincidence:Δm/m = 5% • Q-value resolution: ≤ 20 MeV • Gammasphere Doppler-corrected γ-ray resolution: ≥ 0.8% Further information about CHICO available at http://www.pas.rochester.edu/~cline/Research/index.html

  13. Coulomb excitation of 1360 MeV 238U by 208PbM.W. Simon, D. Cline, C.Y. Wu, R. Teng, K. Vetter, M.P. Carpenter, R.V.F. Janssens, I. Wiedenhover

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