CaGaS Phase II

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CaGaS Phase II is a repeat of capture gamma energy spectroscopy experiments performed during the summer of 2021 in the ISU clean room. The purpose of revisiting the capture gamma experiment is to use a new, higher activity 252Cf source (U2-622) and to investigate different thicknesses of Gadolinium foils and the effect on the high energy photon flux produced. This work is being performed in support of the main conversion process for the In-Situ Positron Annihilation Spectroscopy experiment being designed and performed by INL staff and external collaborators.

Impromptu To Do List

  • Investigate the difference with/out PUR (pile up rejection) enabled on spec amp
    • Look for differences with high count rate source
  • Build shielded tunnel for Gd optimal thickness measurements
    • Both Gd powder and foils
    • Design and print holders for foils and powder
    • Measure up as close to Gd as possible and then ~12" away to calculate the adjustment factors necessary for coincidences
  • Calculate the deadtime for each efficiency measurement using the method outlined on pgs. 83-84 of Practical Gamma Ray Spectrometry by Gordon Gilmore, poorly summarized below.
    • DT=RT-LT or we can rearrange using graduate level mathematics to LT=RT-DT
    • Note that the gate is "open" when the ADC is "NOT" busy (read as no pulse is currently being analyzed)
    • Real time = total measurement time
    • Dead time = amount of time gate is "closed" (effectively total counts x gate width(?))
    • Dead time as a percent is 100x(RT-LT)/RT
    • Calculate real count rate by total counts/live time
    • Could count number of gates on scalar to get relatively accurate number of total gates triggered, however RCGUI events should give the correct number (subtract 3 for prestart, start, and end events)

I) CaGaS Phase II Associated Equipment and Experimental Setup



Radioactive Sources

CH Cf252 Sources

CH Calibration Sources

Electronics Chain


II) Neutron Attenuation Measurements

Discriminator Dual Pulsing Investigation

CH Discriminator Dual Pulsing

Initial Measurements

CH He3 Attenuation Measurements

Revisited Measurements

CH He3 Attenuation Measurements: 3 Different Cf252 Sources

III) CaGaS Phase I Expansion

CaGaS Phase I Gadolinium

CaGaS Phase I Cadmium

IV) HPGe Measurements

PAS HPGe Detector

CH HPGe Efficiency

Previous Work

CaGaS Phase I

Useful Resources

CH ROOT Nonuniform Binning




CH NIM Bin Repair

Previous Page

PAS Experiment