Laser Calibration and Measurement – IMB

Seven muons in IMB detector

Dr. Lessure’s initial work in optics was the development of a Nanosecond UV Light Source for the calibration of the original IMB calorimeter. The IMB detector consisted of an array of high speed large area photomultiplier tubes. The original calibration system consisted of a pulsed Nitrogen laser triggered via computer control with a set of attenuation filters in a filter wheel to vary the the light pulse intensity from a fraction of a photoelectron level up to > 1000 pe. The laser pulses were coupled into an optical fiber which delivered the light to a Rayleigh scattering sphere in the detector and delivered the calibration pulses upon request. The detector has been featured in Physics Today and discussed in Scientific American. The neutrino burst detected from Supernova 1987a was on the cover of Time magazine.

References/Further Reading

  1. Irvine-Michigan-Brookhaven Proton Decay Detector
  2. IMB Literature References
  3. Other detectors which use a variation of the IMB calibration technique:
  4. Physics Today – Underground experiments will look for proton decay – January 17, 1980
  5. Time Magazine – The Nature of the Universe – Mar. 23, 1987
  6. Scientific American – The Search for Proton Decay – June 1985
  7. Popular Science – Hunting Neutrinos – May 1988