1. Calibration (processor.utilities.calibration)

@author: Steinn Ymir Agustsson, Davide Curcio, Maciej Dendzik

processor.utilities.calibration.correctOpticalPath(self, poly1=- 0.00020578, poly2=4.6813e-07, xCenter=1334, yCenter=1426)[source]

Apply corrections to the dataframe. (Maciej Dendzik)

Each DLD time is subtracted with a polynomial poly1*r + poly2*r^2, where r=sqrt((posx-xCenter)^2+(posy-yCenter)^2)

This function makes corrections to the time of flight which take into account the path difference between the center of the detector and the edges of the detector.

processor.utilities.calibration.e2t(e, toffset=None, eoffset=None, l=0.77)[source]

Same as energy2tof, but different name for retrocompatibility

Parameters:
e: float

The binding energy

toffset: float

The time offset from thedld clock start to when the fastest photoelectrons reach the detector

eoffset: float

The energy offset given by W-hv-V

l: float

the effective length of the drift section

Return:
t: float

The time of flight

Authors:

Davide Curcio <davide.curcio@phys.au.dk>

processor.utilities.calibration.energy2tof(e, toffset=None, eoffset=None, l=None)[source]

Transform eV to time of flight (ToF).

The functions (tof2energy and energy2tof) convert between binding energy (\(E_b\)) in eV (negative convention) and time of flight (ToF) in ns.

The formula used is based on the ToF for an electron with a kinetic energy \(E_k\). Then the binding energy \(E_b\) is given by

\[-E_b = E_k + W - hv - V = \frac{1}{2} mv^2 + W - hv - V\]

With W the work function, hv the photon energy, V the electrostatic potential applied to the sample, v the velocity of the electrons in the drift tube, m the mass of the electron. The velocity v in the drift tube can be calculated knowing the length (1m) and the flight time in the drift tube. The measured ToF, however, has some offset due to clock start not coinciding with entry in the drift section.

offs is supposed to include the time offset for when the electrons enter the drift section. Its main mainly affects peak spacing, and there are several strategies for calibrating this value,

  1. By measuring the photon peak and correcting by some extractor voltage-dependent offset

  2. Shifting the potential by 1V and imposing the same shift in the measured spectrum

  3. Imposing some calibrated spacing between features in a spectrum

eoffset is supposed to include -W+hv+V. It mainly affects absolute position of the peaks, and there are several strategies for calibrating this value,

  1. By getting the correct values for W, hv, and V

  2. It can be calibrated by imposing peak position

Parameters:
e: float

The binding energy

toffset: float

The time offset from thedld clock start to when the fastest photoelectrons reach the detector

eoffset: float

The energy offset given by W-hv-V

l: float

the effective length of the drift section

Return:
t: float

The time of flight

Authors:

Davide Curcio <davide.curcio@phys.au.dk>

processor.utilities.calibration.filterCircleDLDPos(self, xCenter=1334, yCenter=1426, radius=1250)[source]

Apply corrections to the dataframe. (Maciej Dendzik)

Filters events with dldPosX and dldPosY within the radius from (xCenter,yCenter).

processor.utilities.calibration.gen_sector_correction(prc, energies, eref, tofVoltage=None, sampleBias=None, monoEnergy=None)[source]

This function is helpful in generating the sector_correction list. This takes into account the time shift caused by the bit stealing hack plus is keeps track of the time shift due to detector misalignment by making sure all values of energies are at eref.

Usage: use the function to create the sector_correction list and assign it to prc.SECTOR_CORRECTION or paste it into the settings with no brackets

Parameters

  • prc –

  • energies –

  • eref –

Returns

processor.utilities.calibration.shiftQuadrants(self, shiftQ1=0.231725, shiftQ2=- 0.221625, shiftQ3=0.096575, shiftQ4=- 0.106675, xCenter=1350, yCenter=1440)[source]

Apply corrections to the dataframe. (Maciej Dendzik)

Each quadrant of DLD is shifted in DLD time by shiftQn. xCenter and yCenter are used to define the center of the division.

Q2

Q4

Q1

Q3

This picture is upside-down in plt.imshow because it starts from 0 in top right corner.

processor.utilities.calibration.t2e(t, toffset=None, eoffset=None, l=0.77)[source]

Same as tof2energy, but different name for retrocompatibility

Parameters:
t: float

The time of flight

toffset: float

The time offset from thedld clock start to when the fastest photoelectrons reach the detector

eoffset: float

The energy offset given by W-hv-V

l: float

the effective length of the drift section

Return:
e: float

The binding energy

Authors:

Davide Curcio <davide.curcio@phys.au.dk>

processor.utilities.calibration.tof2energy(t, toffset=None, eoffset=None, l=None)[source]

Transform ToF to eV.

The functions (tof2energy and energy2tof) convert between binding energy (\(E_b\)) in eV (negative convention) and time of flight (ToF) in ns.

The formula used is based on the ToF for an electron with a kinetic energy \(E_k\). Then the binding energy \(E_b\) is given by

\[-E_b = E_k + W - hv - V = \frac{1}{2} mv^2 + W - hv - V\]

With W the work function, hv the photon energy, V the electrostatic potential applied to the sample with respect to the drift section voltage, v the velocity of the electrons in the drift tube, m the mass of the electron.

The velocity v in the drift tube can be calculated knowing the length (1m) and the flight time in the drift tube. The measured ToF, however, has some offset due to clock start not coinciding with entry in the drift section.

toffset is supposed to include the time offset for when the electrons enter the drift section. Its main mainly affects peak spacing, and there are several strategies for calibrating this value,

  1. By measuring the photon peak and correcting by some extractor voltage-dependent offset

  2. Shifting the potential by 1V and imposing the same shift in the measured spectrum

  3. Imposing some calibrated spacing between features in a spectrum

eoffset is supposed to include -W+hv+V. It mainly affects absolute position of the peaks, and there are several strategies for calibrating this value,

  1. By getting the correct values for W, hv, and V

  2. It can be calibrated by imposing peak position

Parameters:
t: float

The time of flight

toffset: float

The time offset from thedld clock start to when the fastest photoelectrons reach the detector

eoffset: float

The energy offset given by W-hv-V

l: float

the effective length of the drift section

Return:
e: float

The binding energy

Authors:

Davide Curcio <davide.curcio@phys.au.dk>