Working Group 2-2: Instrumentation, Nuclear Structure
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Transcript of Working Group 2-2: Instrumentation, Nuclear Structure
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Working Group 2-2: Instrumentation, Nuclear Structure
The discussion in the instrumentation session was a sort of firstresponse to the ATLAS Intensity Upgrade by this part of the usercommunity.
The discussion also referred to the plans for Digital Gammasphere.
A personal note: A sub-aspect of future Gammasphere plans is theVME readout that would be also beneficial for external detectorsassociated with Gammasphere (so-called auxiliary detectors).
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Presentations directly related to ATLAS intensity upgrade
Doug Cline, Rochester – “Chico experiments with Caribu beams”
Walter Reviol, Washington U. – “Towards Super Hercules andNanoball”
Andreas Heinz, Yale – “Prompt and delayed conversion electronspectroscopy of heavy nuclei”
Darek Seweryniak, ANL – “Gas-filled separator for nuclearstructure experiments at ATLAS
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Doppler-corrected γ-ray spectra 1358 MeV 238U on 170Er
Raw data
Correction for
U-like recoils
Correction for
Er-like recoils
C.Y. Wu, D. Cline, et al, Phys. Rev. C61 (2000) 21305(R)
Chico+Gammasherestable beam expt.
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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
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# det. elements (pixels) 64
Active fraction surface 0.89
Pixel size (mm2) 6x6
“Overall” light guide yes
8x8 Multianode PMT (Hamamatsu 8500)
The light guide is a 0.15-mmthick plastic sheet.
The PMT glass window causescross talk (established by tryingalso “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 PrototypeReviol
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PID Plot for Stilbene
Notice short charge-integration gates [50 x faster than CsI(Tl)].
97% pure material“home grown”
Reviol
Nanoball: PID needs only 130 ns (Microball: 8 μs)
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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.
Andreas Heinz – “Prompt and delayed e- spectroscopy”
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Needs for Delayed Conversion Electrons
• High detection efficiencies and resolution - especially at low electron energies.
• Alpha-electron coincidences• Electron-gamma coincidences
e spectrometer?
Recoils
Catcher (active?)
Ge
Ge
Degrader (active?) M. Asai et al., PRL 95, 102502 (2005)
253Fm
Andreas Heinz
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Darek Seweryniak – “Gas filled separator”
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Important design considerations
Large solid angle Good beam suppression Flexible and efficient coupling to GAMMASPHERE FRIB ready State-of-the art implantation facility (exists)
Heavy nuclei research– HK calorimetry – In-beam gamma and electron spectroscopy– K-isomers– Mass measurements
Heavy proton drip line nuclei
Flagship experiments on spectroscopy of heavy nuclei
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Si Detectors and Si Avalanche Photodiodes
Con Beausang, Richmond – “Stars at Gammasphere”
Lakshmi Soundara Pandian, Lowell – “Towards NuclearSpectroscopy with a Position Sensitive Avalanche Photo Diode”
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STARS-at Gammasphere?
d Beam @ 21&29 MeV
235U
E E1 E2
Clover (6 in all)
p
Fission-ESi Det
fis
Si Det
.5mm 1mm1mm.14mm
+12C**
**400 g/cm2 target with 12C backing
“raytrace”
48 Rings 16 Sectors
Con Beausang (p,t) reactionsNew needs for light ATLAS beams?
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08/09/09 138th Aug 2009 ANL User Workshop
14 mm
< 200 m thick Si
four-corner design
charge fractionation
14 mm
K.S. Shah et al., IEEE Trans. Nucl. Sci.49(4), 1687 (2002).
(RMD, Inc.)
Dr. Pandian, 224Ra source measurements
Position sensitive avalanche photo diode
Possibility for particle-gammacorrelations
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Kris Starosta
Geant simulations indicate 75% s.a. coverage
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Plunger Recoil-Distance Devices, Moving Tape Collectors
Kris Starosta, NSCL – “Recoil distance method for lifetimemeasurements near N=Z line”
Umesh Garg, Notre Dame – “The Gammasphere Plunger”
Kim Lister, ANL – “The beta-decay station for Caribu”
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Kim Lister – “beta-decay station”
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Thanks for your attention!