KamLAND Radioassay Progress in the United States. Lawrence Berkeley National Laboratory with University of Alabama California Institute of Technology University of Tennessee. Low Background Counting. Balloon Film. Goal: Assay radioimpurities in KamLAND construction materials.
KamLAND Radioassay Progress in the United States
Lawrence Berkeley National Laboratory
University of Alabama
California Institute of Technology
University of Tennessee
KamLAND balloon film inside
the Low Background Detector
Goal: Reliable, Independent monitor of Purity and Backgrounds
KamLAND Scintillator purity needs are stringent!
Reactor ( solar) experiment requirements are
K<10-10 (10–14)g/g Th<10-14 (10-16) g/g U<10-14(10-16) g/g
Activation Analysis Goals:
Why Activation Analysis?
41K + n 1.3b42K(12.4 h) β-42Ca
232Th + n 6.5b 233Th(22.3 m) β-233Pa(27 d) β-233U
238U + n 2.4b239U(23.5 m) β-239Np(2.4 d) β-239Pu
Develop liquidirradiation facility (Engineering Proposal by MIT)
Reactor irradiation fees are also significant! Optimize samples for efficiency.
Significant technical progress in the past year towards routine analysis of KamLAND scintillator!
Slowly evaporate scintillator to PPO residue.Ash residue in synthetic quartz.
Irradiate ~2g of PPO in plastic vials in the MIT reactor.
Test irradiations show promising sensitivity and identify challenges!
U < 10-13g/g Th~2x10-13g/g
232Th + n 233Th
233Pa( 39 days mean life)
233U+b+gs (311 keV)
(ICPMS: 4x10-13 gTh/g)
Test data showed NAA sensitivity may easily extend below 10-15 g/g through side activity background reduction.
Ge spectrum from activated scintillator
The 233Pa peak at 311 keV can be seen.
Background reduction would enhance
sensitivity by 2 orders of magnitude.
A new ultra low background
Germanium detector was
added to our capabilities in
Time for PPO counting,
The high efficiency detector
improves statistics of the
Ultra low activity materials
were carefully selected for
The shielding hut of the new
Ge detector spectrum from activated KamLAND PPO:The three spectra compare the spectra before radiochemistry(purple), the spectra after extraction ( actinide ion column)(red), and the ambient detector background(blue).The bottom plot shows a closeup of the 233Pa peak region.
Delayed β-γ-e- decay signatures may offer further
sensitivity. Spectrometers for this have been built.
Data from a feasibility study with a
239Np source. The TDC measures the
delay between a β and conversion e-
A Schematic coincidence
required for the KamLAND reactor experiment.
Equipment and procedures for sample transport
to the United States are now in place.
Operating costs in reactor irradiation fees, hazardous sample shipment from Japan, and clean materials will be substantial!