Clean-Water Control — 500214 (sunlight)

Overview

500214 was placed in clean, recirculating water in direct sunlight at 12:30 PM MT on 2026-07-20 (the default window starts there; earlier data is pre-test). Because the water is clean and unchanging, the true tryptophan signal is constant — so any variation in the raw mon2 is instrument response, not water. The sun drives a large temperature swing (SiPM often 20–29 °C), which makes this an ideal controlled quench characterization: mon2 vs SiPM temperature here is the pure temperature-quench curve, with no confounding water signal.

Three questions this page answers: (1) does the raw signal move only with temperature (as it should)? (2) what is 500214's quench coefficient ρ over this wide, clean range? (3) does the temperature correction flatten the signal back to constant — the direct test of “the TLF signal should not change.”

Load Window

Raw TLF (mon2_val) & Temperature

Raw calibrated-combo mon2 (left axis) with SiPM temperature (right axis). In clean water the two should be mirror images — mon2 falls as it warms (fluorescence quench), rises as it cools. Any move in mon2 that is not mirrored by temperature is a real anomaly (light leak, bubble, drift).

Quench Curve — TLF vs SiPM Temperature

Every reading as a point: mon2 vs SiPM temperature. Clean water + wide sunlit range = the pure quench curve. The fit is the exponential model mon2 = A·eρ(T−20) (Watras 2011 / Bedell 2022); ρ is 500214's temperature coefficient measured over the full range — the characterization the narrow creek window could not give.

Temperature-Corrected TLF — Does It Stay Flat?

Raw mon2 corrected to 20 °C SiPM via the fitted ρ (mon2·eρ(20−T)). If the correction holds over this wide range, the corrected trace is a flat line — confirming the signal doesn't change in clean water. The residual scatter is the correction's accuracy; a slope or curve means the single-ρ model doesn't fully capture the response.

The right axis reads the same trace as a tryptophan concentration equivalent (ppm), zeroed on the clean-water baseline using a nominal LED-512 gain. Because the bath is clean water with no tryptophan, the true value is 0 ppm across the whole test — any excursion is instrument noise/offset, not concentration (500214 has no dilution of its own, so the ppm scale is approximate).

ToF Turbidity & Diagnostics

ToF backscatter (signal_per_spad_kcps) should also be flat in clean water; a rise flags particles, bubbles, or a sunlight/ambient-IR artifact.

All Three Temperature Sensors — SiPM, Board, UV-LED

The Lume’s three on-board temperatures together: SiPM (the detector, and the correct thermal covariate for the quench correction), board (self-heats most in direct sun), and UV-LED. In clean sunlit water they follow the same ambient swing but at different offsets and lags — the board runs hottest, which is why SiPM temperature is used to correct mon2.