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Working Group 2-2: Instrumentation, Nuclear Structure

Working Group 2-2: Instrumentation, Nuclear Structure. The discussion in the instrumentation session was a sort of first response to the ATLAS Intensity Upgrade by this part of the user community. The discussion also referred to the plans for Digital Gammasphere .

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Working Group 2-2: Instrumentation, Nuclear Structure

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  1. Working Group 2-2: Instrumentation, Nuclear Structure The discussion in the instrumentation session was a sort of first response to the ATLAS Intensity Upgrade by this part of the user community. The discussion also referred to the plans for Digital Gammasphere. A personal note: A sub-aspect of future Gammasphere plans is the VME readout that would be also beneficial for external detectors associated with Gammasphere (so-called auxiliary detectors).

  2. Presentations directly related to ATLAS intensity upgrade Doug Cline, Rochester – “Chico experiments with Caribu beams” Walter Reviol, Washington U. – “Towards Super Hercules and Nanoball” Andreas Heinz, Yale – “Prompt and delayed conversion electron spectroscopy of heavy nuclei” Darek Seweryniak, ANL – “Gas-filled separator for nuclear structure experiments at ATLAS

  3. 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 Chico+Gammashere stable beam expt.

  4. 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% Doug Cline Higher segmentation compared to Chico → higher count rate

  5. 8x8 Multianode PMT (Hamamatsu 8500) The light guide is a 0.15-mm thick plastic sheet. The PMT glass window causes cross talk (established by trying also “individual” light guides). The cross talk can be turned into an advantage (tracking). Four PMT’s will be arranged in a “Gobi” geometry. Super Hercules Prototype Reviol

  6. Reviol PID Plot for Stilbene 97% pure material “home grown” Notice short charge-integration gates [50 x faster than CsI(Tl)]. Nanoball: PID needs only 130 ns (Microball: 8 μs)

  7. Andreas Heinz – “Prompt and delayed e- spectroscopy” Needs for Heavy Nuclei • High detection efficiency also at low energies. • e-gamma, e-e, gamma-gamma correlations; i.e. a spectrometer coupled to GAMMASPHERE/GRETINA. • Channel selection (coupled to FMA) • Usable at high beam currents.

  8. Andreas Heinz Needs for Delayed Conversion Electrons • High detection efficiencies and resolution - especially at low electron energies. • Alpha-electron coincidences • Electron-gamma coincidences e spectrometer? 253Fm Catcher (active?) Recoils Ge Degrader (active?) M. Asai et al., PRL 95, 102502 (2005) Ge

  9. Darek Seweryniak – “Gas filled separator”

  10. Flagship experiments on spectroscopy of heavy nuclei Important design considerations • Heavy nuclei research • HK calorimetry • In-beam gamma and electron spectroscopy • K-isomers • Mass measurements • Heavy proton drip line nuclei • Large solid angle • Good beam suppression • Flexible and efficient coupling to GAMMASPHERE • FRIB ready • State-of-the art implantation facility (exists)

  11. Si Detectors and Si Avalanche Photodiodes Con Beausang, Richmond – “Stars at Gammasphere” Lakshmi Soundara Pandian, Lowell – “Towards Nuclear Spectroscopy with a Position Sensitive Avalanche Photo Diode”

  12. Con Beausang (p,t) reactions New needs for light ATLAS beams? STARS-at Gammasphere? “raytrace” .14mm g .5mm 1mm 1mm 48 Rings 16 Sectors p d Beam @ 21&29 MeV 235U + 12C** fis Fission-E DE E1 E2 Si Det Si Det Clover (6 in all) 400 mg/cm2 target with 12C backing **

  13. Dr. Pandian, 224Ra source measurements Possibility for particle-gamma correlations four-corner design charge fractionation (RMD, Inc.) 14 mm 14 mm < 200 m thick Si Position sensitive avalanche photo diode K.S. Shah et al., IEEE Trans. Nucl. Sci.49(4), 1687 (2002). 8th Aug 2009 ANL User Workshop

  14. Kris Starosta Geant simulations indicate 75% s.a. coverage

  15. Plunger Recoil-Distance Devices, Moving Tape Collectors Kris Starosta, NSCL – “Recoil distance method for lifetime measurements near N=Z line” Umesh Garg, Notre Dame – “The Gammasphere Plunger” Kim Lister, ANL – “The beta-decay station for Caribu”

  16. Kim Lister – “beta-decay station”

  17. Thanks for your attention!

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