Fix chopper rotations in optimize_for and Chopper#144
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| nrot = ( | ||
| max( | ||
| int( | ||
| sc.ceil( | ||
| ( | ||
| self.omega * time_limit.to(unit='s') | ||
| - smallest_angle.to(unit='rad') | ||
| ) | ||
| / two_pi | ||
| ).value | ||
| ), | ||
| 1, | ||
| ) | ||
| + 1 |
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Can a helper variable help with readability here? This is too many lines :D
| sc.ceil( | ||
| ( | ||
| self.omega * time_limit.to(unit='s') | ||
| - smallest_angle.to(unit='rad') |
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It is not completely obvious whether this is correct for "very positive" openings. there are tests like test_chopper_with_very_negative_angles_performs_enough_rotations_to_cover_timescale, but what happens if the smallest angle is so large that one would need to rotate backward to cover the full range?
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Good point, we probably need a safety net in the other direction as well!
SimonHeybrock
approved these changes
Jun 24, 2026
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When trying to use
optimize_forin the Trex instrument case, no neutrons were making it through.The pulse-shaping and monochromatic choppers were not performing enough rotations and were thus blocking all neutrons.
Giving them a timescale to dictate how long they should rotate for helped (in this PR also), but did not fix everything.
The pulse-shaping chopper 2 was still not performing enough rotations.
It was because it has some cutout angles < -360 deg, meaning that it was still missing at least one rotation to cover the requested timescale.
Instead of guessing from the rotation frequency and timescale alone, we now find the smallest cutout angle and compute how many rotations need to be done to reach the requested timescale.
We can now make a T-rex model, optimized for the choppers in the beamline, with 0 blocked neutrons:
@bingli621