Proposal to put 232 Th Source in m K for > 2MeV Gamma Detection
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Transcript of Proposal to put 232 Th Source in m K for > 2MeV Gamma Detection
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Proposal to put 232Th Source in K for > 2MeV
GammaDetectionBobby Lanza
May 1, 2008
Neutron Meeting
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The case for 232Th
• Why are ’s with E > 2MeV important?– Muons interacting with the bedrock at Soudan create
photons at this energy scale.– Source of background.
• What can K do? ’s above the 2MeV threshold can impart enough energy to
electrons to make them Cherenkov radiate in K.– Calibration with a test source would inform possible future
tests at Soudan.
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•Why 232Th instead of the Depleted Uranium we have?– DU has many sticking points in its decay chain (long lived daughters), before
the high energy gammas.
– DU chemically purified approx. 30 years ago, so not in equilibrium yet.
Sticking Points
> 2MeV ’s
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– 232Th Approx. 10-15 yrs old (longer than combined daughter half-lives), so likely in equilibrium.
– Above threshold gammas available from 208Tl --> 208Pb decay.
2.6 MeV ’s
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We have a 232Th Source
• 0.1g of 232Th in liquid solution.
• 400 decays per second expected.
• Standard calibration source.
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Near Future (Proposed)
• Design simple containment vessel for 232Th & install in K.
• Take data with liquid 232Th source.
• Do Monte Carlo & compare to data.
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--Thanks--