NMX#

[1]:

import scipp as sc
import tof

import scippnexus as snx
from ess.reduce.unwrap import GenericUnwrapWorkflow
from ess.reduce.nexus.types import *
from ess.reduce.unwrap.types import *
from ess.reduce.unwrap.lut import LtotalRange, ChopperFrameSequence, SourceBounds

Chopper parameters#

[2]:

choppers = {
    "chopper1": {
        "frequency": {"value": 14.0, "unit": "Hz"},
        "open": {"value": [-38.5], "unit": "deg"},
        "close": {"value": [38.5], "unit": "deg"},
        "distance": {"value": 28.4, "unit": "m"},
        "phase": {"value": 111.2, "unit": "deg"},
        "type": "chopper",
        "direction": "clockwise",
        "name": "chopper1",
    },
    "chopper2a": {
        "frequency": {"value": 14.0, "unit": "Hz"},
        "open": {"value": [-70.0], "unit": "deg"},
        "close": {"value": [70.0], "unit": "deg"},
        "distance": {"value": 50.9774, "unit": "m"},
        "phase": {"value": 194.1, "unit": "deg"},
        "type": "chopper",
        "direction": "clockwise",
        "name": "chopper2a",
    },
    "chopper2b": {
        "frequency": {"value": 14.0, "unit": "Hz"},
        "open": {"value": [-70.0], "unit": "deg"},
        "close": {"value": [70.0], "unit": "deg"},
        "distance": {"value": 51.0024, "unit": "m"},
        "phase": {"value": 168.0, "unit": "deg"},
        "type": "chopper",
        "direction": "clockwise",
        "name": "chopper2b",
    },
}

[3]:

nmx_choppers = {}
for key, ch in choppers.items():
    nmx_choppers[key] = tof.Chopper.from_json(name=key, params=ch).to_diskchopper()

for key, ch in nmx_choppers.items():
    print(key)
    display(ch)

chopper1

DiskChopper

(cutout: 1)

axle_position
scipp
Variable
()
vector3
m
[ 0. 0. 28.4]
frequency
scipp
Variable
()
float64
Hz
-14.0
beam_position
scipp
Variable
()
float64
deg
0.0
phase
scipp
Variable
()
float64
deg
-111.2
slit_begin
scipp
Variable
(cutout: 1)
float64
deg
-38.5
slit_end
scipp
Variable
(cutout: 1)
float64
deg
38.5
slit_height
NoneType
()
None
radius
NoneType
()
None

chopper2a

DiskChopper

(cutout: 1)

axle_position
scipp
Variable
()
vector3
m
[ 0. 0. 50.9774]
frequency
scipp
Variable
()
float64
Hz
-14.0
beam_position
scipp
Variable
()
float64
deg
0.0
phase
scipp
Variable
()
float64
deg
-194.1
slit_begin
scipp
Variable
(cutout: 1)
float64
deg
-70.0
slit_end
scipp
Variable
(cutout: 1)
float64
deg
70.0
slit_height
NoneType
()
None
radius
NoneType
()
None

chopper2b

DiskChopper

(cutout: 1)

axle_position
scipp
Variable
()
vector3
m
[ 0. 0. 51.0024]
frequency
scipp
Variable
()
float64
Hz
-14.0
beam_position
scipp
Variable
()
float64
deg
0.0
phase
scipp
Variable
()
float64
deg
-168.0
slit_begin
scipp
Variable
(cutout: 1)
float64
deg
-70.0
slit_end
scipp
Variable
(cutout: 1)
float64
deg
70.0
slit_height
NoneType
()
None
radius
NoneType
()
None

Tof model#

[4]:

source = tof.Source(facility="ess", neutrons=1_000_000, pulses=2)
source_position = sc.vector([0, 0, 0], unit="m")
detector = tof.Detector(distance=sc.scalar(157.5, unit="m"), name="detector")

params = [
    tof.Chopper.from_diskchopper(ch, name=key) for key, ch in nmx_choppers.items()
] + [detector]

model = tof.Model(source=source, components=params)
res = model.run()
res.plot()

[4]:

Plot(ax=<Axes: xlabel='Time [μs]', ylabel='Distance [m]'>, fig=<Figure size 1200x480 with 2 Axes>)

[5]:

res["detector"].plot()

[5]:

Wavelength lookup table#

[6]:

wf = GenericUnwrapWorkflow(
    run_types=[SampleRun], monitor_types=[], wavelength_from="analytical"
)

wf[DiskChoppers[SampleRun]] = nmx_choppers
wf[LtotalRange[SampleRun, snx.NXdetector]] = sc.scalar(5, unit="m"), detector.distance
wf[Position[snx.NXsource, SampleRun]] = source_position

wf[SourceBounds] = SourceBounds(
    # The ESS pulse lasts 2.86 ms, but has a long tail, so we take a wider
    # time range to be safe.
    time=(sc.scalar(0.0, unit='ms'), sc.scalar(5.0, unit='ms')),
    # We cap the wavelength range at 12Å to avoid contamination from slow neutrons.
    wavelength=(
        sc.scalar(0.001, unit='angstrom'),
        sc.scalar(12.0, unit='angstrom'),
    ),
)

table = wf.compute(LookupTable[SampleRun, snx.NXdetector])
table.plot() + table.array['distance', -1].plot(errorbars='band')

[6]:

[7]:

frames = wf.compute(ChopperFrameSequence[SampleRun])
at_sample = frames.propagate_to(detector.distance)
at_sample.draw()

[7]:

(<Figure size 640x480 with 1 Axes>,
 <Axes: title={'center': 'Frame propagation through chopper cascade'}, xlabel='ms', ylabel='Å'>)