scippneutron.tof.chopper_cascade.FrameSequence

class scippneutron.tof.chopper_cascade.FrameSequence(frames)

A sequence of frames, created from a single neutron pulse, potentially chopped into subframes by choppers.

It is recommended to use the from_source_pulse() constructor to create a frame sequence from a source pulse. Then, a chopper cascade can be applied using chop().

__init__(frames)

Methods

__init__(frames)
acceptance_diagram()	Draw a chopper acceptance diagram.
chop(choppers)	Chop the frame sequence by a list of choppers.
draw([linewidth, fill, alpha, transpose, ...])	Draw frames using matplotlib.
from_source_pulse(time_min, time_max, ...)	Initialize a frame sequence from min/max time and wavelength of a pulse.
propagate_to(distance)	Propagate the frame sequence to a distance, adding a new frame.

Attributes

frames

__getitem__(item)

Get a frame by index or distance.

Return type:

Frame

acceptance_diagram()

Draw a chopper acceptance diagram.

See, e.g., J.R.D. Copley, An acceptance diagram analysis of the contaminant pulse removal problem with direct geometry neutron chopper spectrometers, https://doi.org/10.1016/S0168-9002(03)01731-5 for more background.

chop(choppers)

Chop the frame sequence by a list of choppers.

The choppers will be sorted by their distance, and applied in order.

Parameters:

choppers (List[Chopper]) – List of choppers.

Returns:

FrameSequence – New frame sequence.

draw(linewidth=0, fill=True, alpha=None, transpose=False, colors=None, grid=True, title='Frame propagation through chopper cascade', time_unit='ms', wavelength_unit='angstrom')

Draw frames using matplotlib.

Parameters:

• linewidth (Union[int, float], default: 0) – Line width of frame edges.

• fill (bool, default: True) – Fill frame with color.

• alpha (Optional[float], default: None) – Transparency of frame.

• transpose (bool, default: False) – Transpose axes.

• colors (Optional[List[str]], default: None) – List of colors to use for frames. If None, use default matplotlib colors.

• grid (bool, default: True) – Show grid.

• time_unit (str, default: 'ms') – Unit for time axis. Default is ms.

• wavelength_unit (str, default: 'angstrom') – Unit for wavelength axis. Default is angstrom.

Return type:

Any

static from_source_pulse(time_min, time_max, wavelength_min, wavelength_max)

Initialize a frame sequence from min/max time and wavelength of a pulse.

The distance is set to 0 m.

propagate_to(distance)

Propagate the frame sequence to a distance, adding a new frame.

Use this, e.g., to propagate to the sample position after applying choppers.

Parameters:

distance (Variable) – Distance to propagate.

Returns:

FrameSequence – New frame sequence.