SOLO
SOudan LOw Background Gamma Counting Facility

Current Status: Operational

The SOLO screening facility has been constructed by Brown University, in conjunction with PNL and Soudan Mine. The facility screens materials for the Majorana, CDMS, XENON and LUX experiments. The facility was established using HPGe detectors, and shielding, that were previously used in Double Beta Decay Experiments.

Requests for Screening: gaitskell@brown.edu

SOLO performance - Diode-M detector (0.6kg)

The spectra on the right shows the reduction of the gamma background using Pb shielding and Radon gas purge.

  • Blue - Background before the shield reconstruction and removal of Gator detector, on May 1st, 2007
  • Magenta - Background after the shield reconstruction on May 1st, 2007

For details on the shield reconstruction, please visit the SOLO internal pages linked on the sidebar (restricted access)

(click on picture to open it at full size)

Last Updated LdV 20070821

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2003-08-26

 

SOLO - TWIN Detector

Summary of Low Background Performance (pdf , movie)

The spectra on the right shows the reduction of the gamma background using Pb shielding and Radon gas purge.

  • (black) - Cavern background @ Soudan, showing lines from 40K, U/Th chain and 137Cs isotopes.
  • (magenta) - First iteration of shield, lines from 222Rn as expected, however, lines from 194Au/Hg were not expected ! (The latter isotopes were found to be caused by a limited number of "foreign" bricks that came from a proton accelerator experiment.)
  • (red) - Latest background - after 40 kg-days no lines are evident > 100 keV. The spectrum in the range 0-1200 keV is consistent with small 210Bi bremsstrahlung "leakage" through shield cracks which is currently being blocked with more ancient Pb.
  • (blue) - Spectrum from TWIN operation as Double Beta Decay at Homestake. Above 1200 keV the spectra have identical integrated rates.

The materials screening spectra will look similar to the cavern

Photographs of Facility  
Site at Soudan Mine (2000 meters water equivalent depth) prior to installation
Shield construction (John-Paul Thompson, MIke Attisha from Brown, and Jim Reeves, PNL)
Further along with construction (Diode M detector is in place on right - Cu housing can be seen). Pb walls are 14" thick, and include 2" inner liner of low 210Pb "ancient" Pb
Two (8")^3 cavities with TWIN (2124) and Diode M HP Ge detectors in place. Outer white casing for Rn purge also in place.
Screening facility closed up, and DAQ in place.

Last Updated rjg 030826