Create a time-of-flight lookup table for DREAM#

This notebook shows how to create a time-of-flight lookup table for the DREAM instrument.

[1]:

import scipp as sc
from ess.reduce import time_of_flight
from ess.dream.beamline import InstrumentConfiguration, choppers

Select the choppers#

We select the choppers for the ‘high-flux’ configuration.

[2]:

disk_choppers = choppers(InstrumentConfiguration.high_flux)

Setting up the workflow#

[3]:

wf = time_of_flight.TofLookupTableWorkflow()

wf[time_of_flight.LtotalRange] = sc.scalar(60.0, unit="m"), sc.scalar(80.0, unit="m")
wf[time_of_flight.NumberOfSimulatedNeutrons] = 200_000  # Increase this number for more reliable results
wf[time_of_flight.SourcePosition] = sc.vector([0, 0, 0], unit='m')
wf[time_of_flight.DiskChoppers] = disk_choppers
wf[time_of_flight.DistanceResolution] = sc.scalar(0.1, unit="m")
wf[time_of_flight.TimeResolution] = sc.scalar(250.0, unit='us')
wf[time_of_flight.LookupTableRelativeErrorThreshold] = 0.02
wf[time_of_flight.PulsePeriod] = 1.0 / sc.scalar(14.0, unit="Hz")
wf[time_of_flight.PulseStride] = 1
wf[time_of_flight.PulseStrideOffset] = None

Compute the table#

[4]:

table = wf.compute(time_of_flight.TimeOfFlightLookupTable)
table

[4]:
Show/Hide data repr Show/Hide attributes
scipp.DataArray (921.04 KB)
    • distance: 204
    • event_time_offset: 287
    • distance
      (distance)
      float64
      m
      59.85, 59.95, ..., 80.050, 80.150
      Values:
      array([59.85, 59.95, 60.05, 60.15, 60.25, 60.35, 60.45, 60.55, 60.65,
       60.75, 60.85, 60.95, 61.05, 61.15, 61.25, 61.35, 61.45, 61.55,
       61.65, 61.75, 61.85, 61.95, 62.05, 62.15, 62.25, 62.35, 62.45,
       62.55, 62.65, 62.75, 62.85, 62.95, 63.05, 63.15, 63.25, 63.35,
       63.45, 63.55, 63.65, 63.75, 63.85, 63.95, 64.05, 64.15, 64.25,
       64.35, 64.45, 64.55, 64.65, 64.75, 64.85, 64.95, 65.05, 65.15,
       65.25, 65.35, 65.45, 65.55, 65.65, 65.75, 65.85, 65.95, 66.05,
       66.15, 66.25, 66.35, 66.45, 66.55, 66.65, 66.75, 66.85, 66.95,
       67.05, 67.15, 67.25, 67.35, 67.45, 67.55, 67.65, 67.75, 67.85,
       67.95, 68.05, 68.15, 68.25, 68.35, 68.45, 68.55, 68.65, 68.75,
       68.85, 68.95, 69.05, 69.15, 69.25, 69.35, 69.45, 69.55, 69.65,
       69.75, 69.85, 69.95, 70.05, 70.15, 70.25, 70.35, 70.45, 70.55,
       70.65, 70.75, 70.85, 70.95, 71.05, 71.15, 71.25, 71.35, 71.45,
       71.55, 71.65, 71.75, 71.85, 71.95, 72.05, 72.15, 72.25, 72.35,
       72.45, 72.55, 72.65, 72.75, 72.85, 72.95, 73.05, 73.15, 73.25,
       73.35, 73.45, 73.55, 73.65, 73.75, 73.85, 73.95, 74.05, 74.15,
       74.25, 74.35, 74.45, 74.55, 74.65, 74.75, 74.85, 74.95, 75.05,
       75.15, 75.25, 75.35, 75.45, 75.55, 75.65, 75.75, 75.85, 75.95,
       76.05, 76.15, 76.25, 76.35, 76.45, 76.55, 76.65, 76.75, 76.85,
       76.95, 77.05, 77.15, 77.25, 77.35, 77.45, 77.55, 77.65, 77.75,
       77.85, 77.95, 78.05, 78.15, 78.25, 78.35, 78.45, 78.55, 78.65,
       78.75, 78.85, 78.95, 79.05, 79.15, 79.25, 79.35, 79.45, 79.55,
       79.65, 79.75, 79.85, 79.95, 80.05, 80.15])
    • distance_resolution
      ()
      float64
      m
      0.10000000000000142
      Values:
      array(0.1)
    • error_threshold
      ()
      float64
      𝟙
      0.02
      Values:
      array(0.02)
    • event_time_offset
      (event_time_offset)
      float64
      µs
      0.0, 249.750, ..., 7.118e+04, 7.143e+04
      Values:
      array([    0.        ,   249.75024975,   499.5004995 ,   749.25074925,
         999.000999  ,  1248.75124875,  1498.5014985 ,  1748.25174825,
        1998.001998  ,  2247.75224775,  2497.5024975 ,  2747.25274725,
        2997.002997  ,  3246.75324675,  3496.5034965 ,  3746.25374625,
        3996.003996  ,  4245.75424575,  4495.5044955 ,  4745.25474525,
        4995.004995  ,  5244.75524476,  5494.50549451,  5744.25574426,
        5994.00599401,  6243.75624376,  6493.50649351,  6743.25674326,
        6993.00699301,  7242.75724276,  7492.50749251,  7742.25774226,
        7992.00799201,  8241.75824176,  8491.50849151,  8741.25874126,
        8991.00899101,  9240.75924076,  9490.50949051,  9740.25974026,
        9990.00999001, 10239.76023976, 10489.51048951, 10739.26073926,
       10989.01098901, 11238.76123876, 11488.51148851, 11738.26173826,
       11988.01198801, 12237.76223776, 12487.51248751, 12737.26273726,
       12987.01298701, 13236.76323676, 13486.51348651, 13736.26373626,
       13986.01398601, 14235.76423576, 14485.51448551, 14735.26473526,
       14985.01498501, 15234.76523477, 15484.51548452, 15734.26573427,
       15984.01598402, 16233.76623377, 16483.51648352, 16733.26673327,
       16983.01698302, 17232.76723277, 17482.51748252, 17732.26773227,
       17982.01798202, 18231.76823177, 18481.51848152, 18731.26873127,
       18981.01898102, 19230.76923077, 19480.51948052, 19730.26973027,
       19980.01998002, 20229.77022977, 20479.52047952, 20729.27072927,
       20979.02097902, 21228.77122877, 21478.52147852, 21728.27172827,
       21978.02197802, 22227.77222777, 22477.52247752, 22727.27272727,
       22977.02297702, 23226.77322677, 23476.52347652, 23726.27372627,
       23976.02397602, 24225.77422577, 24475.52447552, 24725.27472527,
       24975.02497502, 25224.77522478, 25474.52547453, 25724.27572428,
       25974.02597403, 26223.77622378, 26473.52647353, 26723.27672328,
       26973.02697303, 27222.77722278, 27472.52747253, 27722.27772228,
       27972.02797203, 28221.77822178, 28471.52847153, 28721.27872128,
       28971.02897103, 29220.77922078, 29470.52947053, 29720.27972028,
       29970.02997003, 30219.78021978, 30469.53046953, 30719.28071928,
       30969.03096903, 31218.78121878, 31468.53146853, 31718.28171828,
       31968.03196803, 32217.78221778, 32467.53246753, 32717.28271728,
       32967.03296703, 33216.78321678, 33466.53346653, 33716.28371628,
       33966.03396603, 34215.78421578, 34465.53446553, 34715.28471528,
       34965.03496503, 35214.78521479, 35464.53546454, 35714.28571429,
       35964.03596404, 36213.78621379, 36463.53646354, 36713.28671329,
       36963.03696304, 37212.78721279, 37462.53746254, 37712.28771229,
       37962.03796204, 38211.78821179, 38461.53846154, 38711.28871129,
       38961.03896104, 39210.78921079, 39460.53946054, 39710.28971029,
       39960.03996004, 40209.79020979, 40459.54045954, 40709.29070929,
       40959.04095904, 41208.79120879, 41458.54145854, 41708.29170829,
       41958.04195804, 42207.79220779, 42457.54245754, 42707.29270729,
       42957.04295704, 43206.79320679, 43456.54345654, 43706.29370629,
       43956.04395604, 44205.79420579, 44455.54445554, 44705.29470529,
       44955.04495504, 45204.7952048 , 45454.54545455, 45704.2957043 ,
       45954.04595405, 46203.7962038 , 46453.54645355, 46703.2967033 ,
       46953.04695305, 47202.7972028 , 47452.54745255, 47702.2977023 ,
       47952.04795205, 48201.7982018 , 48451.54845155, 48701.2987013 ,
       48951.04895105, 49200.7992008 , 49450.54945055, 49700.2997003 ,
       49950.04995005, 50199.8001998 , 50449.55044955, 50699.3006993 ,
       50949.05094905, 51198.8011988 , 51448.55144855, 51698.3016983 ,
       51948.05194805, 52197.8021978 , 52447.55244755, 52697.3026973 ,
       52947.05294705, 53196.8031968 , 53446.55344655, 53696.3036963 ,
       53946.05394605, 54195.8041958 , 54445.55444555, 54695.3046953 ,
       54945.05494505, 55194.80519481, 55444.55544456, 55694.30569431,
       55944.05594406, 56193.80619381, 56443.55644356, 56693.30669331,
       56943.05694306, 57192.80719281, 57442.55744256, 57692.30769231,
       57942.05794206, 58191.80819181, 58441.55844156, 58691.30869131,
       58941.05894106, 59190.80919081, 59440.55944056, 59690.30969031,
       59940.05994006, 60189.81018981, 60439.56043956, 60689.31068931,
       60939.06093906, 61188.81118881, 61438.56143856, 61688.31168831,
       61938.06193806, 62187.81218781, 62437.56243756, 62687.31268731,
       62937.06293706, 63186.81318681, 63436.56343656, 63686.31368631,
       63936.06393606, 64185.81418581, 64435.56443556, 64685.31468531,
       64935.06493506, 65184.81518482, 65434.56543457, 65684.31568432,
       65934.06593407, 66183.81618382, 66433.56643357, 66683.31668332,
       66933.06693307, 67182.81718282, 67432.56743257, 67682.31768232,
       67932.06793207, 68181.81818182, 68431.56843157, 68681.31868132,
       68931.06893107, 69180.81918082, 69430.56943057, 69680.31968032,
       69930.06993007, 70179.82017982, 70429.57042957, 70679.32067932,
       70929.07092907, 71178.82117882, 71428.57142857])
    • pulse_period
      ()
      float64
      µs
      71428.57142857142
      Values:
      array(71428.57142857)
    • pulse_stride
      ()
      int64
      1
      Values:
      array(1)
    • time_resolution
      ()
      float64
      µs
      249.7502497502497
      Values:
      array(249.75024975)
    • (distance, event_time_offset)
      float64
      µs
      nan, nan, ..., 6.975e+04, 7.002e+04
      σ = nan, nan, ..., 206.499, 180.395
      Values:
      array([[           nan,            nan,            nan, ...,
                   nan,            nan,            nan],
       [           nan,            nan,            nan, ...,
                   nan,            nan,            nan],
       [           nan,            nan,            nan, ...,
                   nan,            nan,            nan],
       ...,
       [70009.20286516, 70313.87842294, 70569.95741317, ...,
        69489.90287304, 69781.39514441, 70009.20286516],
       [70011.62386551, 70308.75716885, 70550.36091072, ...,
        69469.76636845, 69784.53347276, 70011.62386551],
       [70016.91880707, 70281.58220837, 70528.09218571, ...,
        69487.42744838, 69749.28125898, 70016.91880707]], shape=(204, 287))

      Variances (σ²):
      array([[           nan,            nan,            nan, ...,
                   nan,            nan,            nan],
       [           nan,            nan,            nan, ...,
                   nan,            nan,            nan],
       [           nan,            nan,            nan, ...,
                   nan,            nan,            nan],
       ...,
       [32086.15833881, 28931.59936597, 34879.95248697, ...,
        41964.37008744, 25873.51651456, 32086.15833881],
       [35256.65205708, 35110.26889642, 33830.23977112, ...,
        35514.28297794, 36059.18608987, 35256.65205708],
       [32542.43968036, 35834.79016416, 28934.63079971, ...,
        34425.33833899, 42641.82165578, 32542.43968036]], shape=(204, 287))
[5]:

table.plot()

[5]:
../../_images/user-guide_dream_dream-make-tof-lookup-table_8_0.svg

Save to file#

[6]:

# Save chopper metadata
# TODO: storing the choppers as a PyObject is skipped when saving to disk
table.coords['choppers'] = sc.scalar(disk_choppers)
# Write to file
table.save_hdf5('DREAM-high-flux-tof-lookup-table.h5')

Writing with dtype=PyObject not implemented, skipping.