CH Weekly Reports

09/19/22

• Investigated non-linearity of peak sensing ADC due to issues arising in energy calibrations and efficiency measurements.

• Modified existing calibration code to use non-linear regression to account for ADC.

• Sourced material needed for CaGaS Phase II setup.

• Calculated ADC dead time for live-time correction to efficiency measurement count rates and calculated dead time per experiment.

• Designed holder for Gd foils needed for CaGaS Phase II experiment. To be 3D printed and tested for tolerances.

09/26/22

• Printed both parts of the Gd foil holder for CaGaS Phase II.
  • Parts fit together adequately considering they're 3D printed and not machined.
  • M3 bolts threaded through first part of the holder.
  • M3 nuts pressed into the second part of the holder.
  • Parts printed out of PETG plastic with low density infill (10%).

• Edited rebinning code for energy calibrations for data sets collected with ADC to account for changes in calibration code.
  • Energy calibration script now uses 2nd order polynomial regression to account for nonlinearity of ADC
  • The coefficients from the regression are passed to another script to rebin ADC data from channel to energy, preserving bin count, but bin width will increase as a function of energy.
    • End goal is to pass coefficients into rebinning function and draw energy calibrated plot in the same script.

• Designed Gd₂O₃ powder holder for CaGaS Phase II.
  • Have spray on clear coat to seal plastic after printing is complete in hopes that powder will not stick between printed layers when used.

• Documented Gd holders in wiki with rendered images and a description of intended use.

• Continued to research live time correction for HPGe count rates and think I have applied the correction correctly at the initial measurement level, which will be propagated through to efficiency calculations.

• Researched and tested different integration methods for more accurate measurement of counts in energy peak to compare to Gaussian fit.

• Created tentative list of committee members with major advisor for PhD proposal defense and future dissertation defense.

10/03/22

• Sat in on 30 minute proposal defense presentation by another Ph.D. candidate.

• Began the 3D print of Gd₂O₃ holder for CaGaS Phase II.
  • Both parts printed and fit together tightly. Need to be sealed for use with powder.
  • Updated wiki documentation with images of the holders.

• Working with ISU Environmental Health & Safety to set up time to treat and coat lead bricks to build CaGaS Phase II setup.
  • Air monitoring and respirators are required per ISU EH&S safety protocols.

• Designed and printed a holder for Cs137 calibration source for storage in lab (signed off with RSO) for easy point calibrations using HPGe.

• Researched dead time adjustment in Practical Gamma-ray Spectrometry by Gordon Gilmore
  • Collected 50 data points for ADC gate width, read out controller trigger width, and the delay between end of gate and beginning of read trigger.
  • Found dead time per pulse which includes memory storage time, thanks to reading the aforementioned book.

• Worked to re-plot and integrate Eu152 peaks, but source data file seems to be corrupted. Will collect new set of data on Monday (10/10/22) when I can access calibration sources.
  • Re-plotting is necessary for new integration with 2nd order polynomial binning and new live time correction.
  • Collecting a new Eu152 spectrum is needed before CaGaS Phase II for new energy calibration as NIM bin has been power cycled and spec-amp gain has shifted.

10/10/22

• Moved extra lead for CaGaS Phase II from lead storage at ISU to lab for coating prior to use.

• Coated 30 lead bricks for CaGaS Phase II setup.

• Fixed energy calibration code thanks to input from a colleague.
  • Machine precision and how ROOT interprets bins was cause of the issue.

• Designed tools to use to level and compact powder into the powder holder for use during CaGaS Phase II.
  • Designed new covers for powder holder to better accommodate for different thicknesses of powder.

• Experimentally confirmed minimum dead and maximum bounds on dead time of data acquisition system per event after questions from colleague and plotted voltage traces for documentation.

• Refit ¹⁵²Eu energy peaks with gaussians + linear background and recalculated efficiencies using live time correction.
  • Finished replotting and calculating uncertainty in HPGe efficiency measurements to present next week, all calibration sources (¹⁵²Eu, ¹³⁷Cs, & ⁶⁰Co).

• Met with collaborators and discussed FY23 work scope.
  • Setup recurring meetings biweekly starting 10/19/22.

• Contributed to Paul's SOW for FY23.

10/17/22

• Uploaded new versions of efficiency measurement plots to wiki.

• Wrote up efficiency measurement results, explained in detail how the calculations work.
  • Wrote up and defined equations for uncertainty calculations, found lack of count statistics is highly influencing uncertainty in efficiency measurements. Working to rectify by collecting new data sets with ¹⁵²Eu with increased run time.
  • Collected new on & off axis ¹⁵²Eu spectra and overnight background for background subtraction. -> Power stability issues to clean room crashed DAQ2 for background run.
    • Had data acquisition failure due to high count rate halfway through one run, estimated run time based on ratio of rates from previous measurements and decay of ¹⁵²Eu source between past and present runs.

• Created slides and presented HPGe Efficiency write up to collaborators.
  • Met with advisor and verified methods for calculations were reasonable.

• Adjusted design of powder flattening tool to make it easier to use and 3D print.

• Continued work on write up of experimental design and results for CaGaS Phase I.

• Started drafting run plan for CaGaS Phase II.
  • Currently includes runs using He3 tube to measure thermal neutron rate in detector tunnel as a function Gd thickness.
  • HPGe using varying thicknesses of Gd foils and powder.
  • Plan is to vary the distance between detector & gadolinium to be able to account for coincidence peaks problem.

10/24/22

• Finished 3D printed all Gd₂O₃ powder flattening/compacting tools designed previously.

• Stayed up to date with INL required training modules.

• Used feedback from Ph.D. committee members to improve efficiency measurements.

• Debugged and replaced part of signal propagation chain for HPGe electronics chain.

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