SERL _ MRP

Facilities and Equipment:

Last revised: 06 December, 2004

The Schaefer Environmental Radiation Laboratory (SERL) is a cluster of a rooms within the Physics Department that contain instruments for measuring radon, environmental sampling, and spectroscopy systems for alpha and gamma radiation. This facility is dedicated to the spirit of Thomas O. Schaefer, SJU '81. Tom's pioneering senior thesis work on the gamma spectra of outdoor radioactive particulates opened an era of collaborative research on environmental radiation by students and Dr.Steck . Employing hard work, dedication, and initiative, Tom built both a useful detection system and a tradition. Tom, a Marine pilot, died in a military aircraft accident in 1984. This facility was dedicated to his memory in 1985. Most of the research activity of the Minnesota Radon Project (MRP) is conducted in this facility.

    Since we're physicists, we tend to enjoy developing and using instruments that are sometimes more sophisticated than needed for "typical" radon measurements. We have some sophisticated alpha and gamma spectrometers for low level radioanalytic analysis. But we also have radiation detection systems that are inexpensive and low tech, like track registration radon and radon progeny monitors (see Getting Tested).

Radon and Progeny Concentrations:

• Radon monitors :
  • Durridge RAD7 (2) with bubbler for Radon in Water
  • Pylon AB5+PFT (4)
  • 4 Ludlum 2200s + 218 & 182 photomultiplier assemblies - computer interfaced  
  • 32 ZnS flow through scintillation chambers ranging in volume from 35 to 600 mL.

We maintain a calibration of these monitors through the annual intercomparison exercises conducted by calibrated government and private radon chambers.

• Radon Progeny monitors:
  • SARAD EQF 3120
  • Thomson-Neilsen TN-2
  • Pylon WLx.
  • 5 scintillation based WL counters

• Radon chambers:
  • A "bedroom sized" exposure room (30 m^3) with controllable air exchange, aerosols, humidity, and radon concentration. Radon concentrations up to 150 pCi/L with monitoring for radon, radon progeny ( cluster and attached modes),  ventilation, T, Rh, air velocity, pressure, ion density
  • A 0.5 m^3 chamber for concentrations from 20 to 3000 pCi/L and a 0.025m^3 chamber that has achieved concentrations up to 500,000 pCi/L.

• Surface alpha activity:
  • 15 semiconductor CAM diodes, from 900 mm^2  to 2000mm^2,
  • Four PIPS diodes from 300 mm^2 to 900 mm^2
  • Canberra alpha spectroscopy vacuum chamber
  • Preamplifiers
  • Amplifiers
  • Power supply
  • Portable PC based MCAs (Aptec) (3 systems)
  • 6 Ludlum 2220+43-1 ZnS.

• Surface gamma survey instruments:
  • Ortec HpGe-55195 Gamma cage in Canberra 717, 2" Pb shield connected to Aptec PC MCA
  • Odyssey Bicron 3MT3/3 NaI in Gamma Products 3" Pb shield connected to portable Aptec PC MCA Ludlum model 12S microR meter (for remote surveying)
  • Computer-interfaced GPS system for automapping
• Integrating radon and progeny monitors:
  • Alpha Track radon Detectors (ATDs): 2 indoor and 1 outdoor models
  • EPERM system
  • Retrospective Reconstruction Detector (RRDs)

Radon transport in soil characterization:

• Field permeability:
  • Our permeometer is a 1 m long, 8mm diameter tube coupled to an electronically timed, pressure monitored 16 L manifold. The manifold is evacuated to approximately 50 kPa. Then a 2 to 5 point pressure decay curve is measured. The linear least squares fit to the logarithm of the pressure decay curve produces a estimate for the permeability.

• Diffusivity:
  • In the lab we have measured the diffusivity of packed soil samples (cylindrical; 10 cm long x 6 cm diameter) be fitting the time dependence of a scintillation chamber fitted with the soil column which serves as a diffusive leak.. In the field we estimate the soil's diffusivity from the ratio of the radon gas concentration at 0.3 m to the radon gas concentration at 1 m.

Mapping-GIS:

• PC ArcInfo+ArcView with address geocoding
• SURFER countouring software+Mapviewer
• Calcomp digitizing table 36"x48"
• Color scanners and printers

 Back to the MRP Homepage

Questions/Comments, e-mail: Dr. Steck

Last revised : 06 December, 2004 

Visitor since 12/06/04

Disclaimer
The views and opinions expressed on the web sites hosted on this server are strictly those of the author.
The contents of the web sites on this server have not been reviewed or approved by the College of St. Benedict|St. John's University.