Muon Unscripted Testing: FDA (Frequency Domain Analysis)

Introduction

These are unscripted tests for the Frequency Domain Analysis interface. The master testing guide is located at Muon Interfaces Unscripted Testing.

FFT Test

  • Open Frequency Domain Analysis (Interfaces > Muon > Frequency Domain Analysis)

  • Change Instrument to MUSR, found in the Home tab

  • In the loading bar enter 62260

  • Go to the Transform tab

    • Set the workspace to “MUSR00062260; Group; bkwd; Asymmetry; FD”

    • Click the calculate FFT button and a plot will appear

    • The plot window will show a broad peak

  • In the Fitting tab it will contain 3 workspace ending in Re_unit_MHz (real), Im_unit_MHz (imaginary) and mod_unit_MHz (modulus)

  • Go to the Transform tab

    • The “Apodization Function” determines the amount of smoothing of the data

    • Set the “Apodization Function” to None and press calculate

    • The plot will show a large peak at 0 and then lots of noise

    • Set the “Apodization Function” to Gaussian and press calculate

    • There will be a clear peak

    • The “padding” adds zeros to the end of the time domain data set, to improve the sampling of the FFT

    • Set the xrange for the plot to be from 0 to 2 by changing the x min and x max values below the plot

    • Set the “padding” to zero and press calculate

    • The plot should still have a peak, but it will be less smooth

    • Set the “padding” to 50 and press calculate

    • The plot will now be nice and smooth

  • At the top of the plotting window change the unit from “Frequency” to “Field”, the data will have different x axis

Phasequad Test

Muon data from all of the detectors can be combined into a pair of lines if there is a strong frequency peak. This is done by applying a phase shift to each of the detectors, such that they all have a phase of zero. The data can then be summed.

  • Open Frequency Domain Analysis (Interfaces > Muon > Frequency Domain Analysis)

  • Change Instrument to MUSR, found in the Home tab

  • In the loading bar enter 62260

  • Go to the Phase tab

  • Click “calculate phase table”

  • Enter ptable as the name of the table

  • Select the Phase Table from the menu below, the name of the table will contain ptable

  • Click the plus button, located in the left down of the tab, to enter a new Phasequad

  • Enter pq as the name of the Phasequad

  • Go to the transform tab

  • Tick the imaginary Workspace option

  • Select the real and imaginary parts of pq to be the Workspace and Imaginary Workspace respectively

  • Click calculate

Maxent Test

Maxent calculates the frequency spectra and then converts using an FFT to compare with the time domain data.

  • Open Frequency Domain Analysis (Interfaces > Muon > Frequency Domain Analysis)

  • Change Instrument to MUSR, found in the Home tab

  • In the loading bar enter 62260

  • Go to the Transform tab

  • Change the drop-down menu at the top of the interface to “MaxEnt”

  • The interface should look different

  • Click the Calculate MaxEnt button

  • The calculate button will be disabled and cancel enabled

  • Click the cancel button

  • Click Calculate MaxEnt

  • The plot should update to a mostly flat line with a peak

  • Make sure everything in the top table is ticked

  • Click calculate MaxEnt

  • In the plotting window change the plot to Maxent Dual Plot

  • You will now see 5 plots (1 frequency and 4 time domain)

  • In the ADS expand the MUSR62260 group

  • It will contain several workspaces

  • The workspace that ends with phase_convergence will show a plot that tends to a single y value as x gets larger (just check a spectrum or two)

  • The table that ends with dead_times will have two columns: spectrum number and dead time

  • The table that ends with phase_table will have three columns: spectrum number, asymmetry, and phase

  • The workspace that ends with reconstructed_spectra will look like the original data