Measurements of Neutron Activation of 76 Ge and 136 Xe
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Transcript of Measurements of Neutron Activation of 76 Ge and 136 Xe
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Measurements of Neutron Activation of 76Ge and 136Xe
James EsterlineMegha Bhike, Josh Bradt, Brent Fallin, Sean Finch, Matt Gooden,
Calvin Howell, John Kelley, Werner Tornow
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Measurements of Neutron Activation of 76Ge and 136Xe
James EsterlineMegha Bhike, Josh Bradt, Brent Fallin, Sean Finch, Matt Gooden,
Calvin Howell, John Kelley, Werner Tornow
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Neutron Activation
• Spallation from cosmic m• Interest in contributions to background in ROI
for 0n2b decay• Secondary interest as nuclear structure study• Analysis ongoing: progress and partial results
here presented
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Experimental Setup
• Neutrons generated by 2H(d,n)3He– Utilized deuteron beam from TUNL’s DENIS– Pulsed at 2.5 MHz to enable time correlations– Produced neutron at energies En = 8.0, 12.0 MeV– Only presenting at 8 MeV
• Ran in (presently disassembled) Shielded Source Area– Maximum suppression of background neutrons,
photons
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DENIS
Beam pickoff
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NTOF
DENIS
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Experimental Setup
• Illuminate samples with collimated neutron beam– Germanium as thick foil (irregular shape for
enriched)– Xenon in metal spheres
• Use Fe foils instead of direct neutron flux measurement for normalization
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Experimental Setup
• Illuminate samples with collimated neutron beam– Germanium as thick foil (irregular shape for
enriched)– Xenon in metal spheres
• Use Fe foils – unfortunately, shares prominent transition energy (847 keV) with germanium– Uncertainty of metal composition for Xe– Added Ni foils
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Experimental Setup
• Initially used clover detectors– One detector with only two of four segments
operational; other with all four• Switched to 60% HPGe detectors• Have small contributions from scattered
neutrons activating detectors
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Data Acquisition and Analysis• Time of flight between pickoff and detection
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Data Acquisition and Analysis• Time of flight between pickoff and detection
[Source g]
Desired neutron activation
Rescattered, breakup neutrons
[Walk]
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Data Acquisition and Analysis
• Energy deposited in germanium detectors
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Data Acquisition and Analysis
• Data processed in one- or two-hour runs• Flight time gates determined in aggregate
– 5% of peak height on signal peak– Focus on maximizing accidental gate width
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Data Analysis
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Data Analysis
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Data Acquisition and Analysis
• Data processed in one- or two-hour runs• Flight time gates determined in aggregate
– 5% of peak height on signal peak– Focus on maximizing accidental gate width
• Energy calibrations determined individually for each run using prominent peaks (both signal and background)
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Data Acquisition and Analysis
• Data processed in one- or two-hour runs• Flight time gates determined in aggregate
– 5% of peak height on signal peak– Focus on maximizing accidental gate width
• Energy calibrations determined individually for each run using prominent peaks (562 keV (Ge)/847 keV (Fe), 40K, n-p capture, 214Bi)
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Data Acquisition and Analysis
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Data Acquisition and Analysis
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Data Acquisition and Analysis
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Data Acquisition and Analysis
• Apply calibrations and time of flight cuts
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Data Acquisition and Analysis
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Data Acquisition and Analysis
• Shared energy between detectors
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Data Acquisition and Analysis
• Shared energy between detectors
• Also look at coincidence spectra
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Data Acquisition and Analysis
• Obtain (~ d.c.s.) values for various transitions
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Results
• Transitions in the ROI for Ge, Xe
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Ge Spectra
2035 keV(74Ge)
2040.7 keV (from E*(1+,2+) = 3951 keV)
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Ge Spectra
2035 keV(74Ge)
2040.7 keV (from E*(1+,2+) = 3951 keV)
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Ge Spectra
2035 keV(74Ge)
2040.7 keV (from E*(1+,2+) = 3951 keV)
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Xe SpectraJ. Bradt et al., 2012
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Future Work
• Obtain estimates of total cross sections• Apply scheme in full to natGe and 136Xe