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 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).

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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 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

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Doppler-corrected ?-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
ChicoGammashere stable beam expt.
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Future SuperCHICO plus GRETINA
Doug Cline

• Angular coverage 20o ? 85o, 95o ?
  160o 280o in f
• Angular resolution ?? 1o, ?f 1.4o
• Solid angle 66 of 4p
• Time resolution ?t 500ps
• Mass resolution for kinematic coincidence ?m/m
  5
• Q-value resolution 20 MeV
• GRETA Doppler-corrected ?-ray resolution 0.3

Higher segmentation compared to Chico ? higher
count rate
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8x8 Multianode PMT (Hamamatsu 8500)
det. elements (pixels) 64
Active fraction surface 0.89
Pixel size (mm2) 6x6
Overall light guide yes
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 PMTs will be
arranged in a Gobi geometry.
Super Hercules Prototype Reviol
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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)
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Needs for Heavy Nuclei
Andreas Heinz Prompt and delayed e-
spectroscopy

• 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.

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Needs for Delayed Conversion Electrons
Andreas Heinz

• 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
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Darek Seweryniak Gas filled separator
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Important design considerations
Flagship experiments on spectroscopy of heavy
nuclei

• 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)

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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

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Con Beausang (p,t) reactions New needs for light
ATLAS beams?
STARS-at Gammasphere?
raytrace
g
.14mm
.5mm
1mm
1mm
p
d Beam _at_ 2129 MeV
235U

12C
fis
Fission-E
DE
E1
E2
Si Det
Si Det
Clover (6 in all)
400 mg/cm2 target with 12C backing

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Dr. Pandian, 224Ra source measurements
Possibility for particle-gamma correlations
four-corner design
charge fractionation
(RMD, Inc.)
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mm
14 mm
lt 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
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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
  lifetime
• measurements near NZ 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!